guideline of possible application of slurries in industries demanding micronized materials and valor
DESCRIPTION
This guideline present an overview of the possible industrial applications of the slurries from stone manufacturing used for substituting micronized raw materials in several industrial sectors, considering not only the requirements of the raw materials but also the potential demand of those sectors.TRANSCRIPT
Guideline of possible application of slurries in industries Page 1
LIFE Project Number
LIFE10 ENV/ES/000480
Reporting Date
30/03/2012
LIFE+ RECYSLURRY
Valorisation and recycling of slurries produced during
manufacturing stone sector to use as raw materials for
industrial applications
Deliverable 2.1
Deliverable: Guideline of possible application of slurries in industries
demanding micronized materials and valorization of slurries
Reported by
AIDICO. AITEMIN, CEVALOR and IMM CARRARA
Guideline of possible application of slurries in industries Page 2
Index
1. Summary of the report .......................................................................................................... 3
2. Introduction of the deliverable ............................................................................................. 4
3. Overview of the industrial sector with high demand of micronized raw materials ............. 7
4. Possible applications of the slurries and preliminary results of introduction of the slurries
as raw materials .......................................................................................................................... 13
Slurries used as raw materials for the cement and concrete industries ................................ 13
Slurries used as raw materials for the agglomerate stone industry ....................................... 17
Slurries used as raw materials for other uses ......................................................................... 28
5. Potencial application of Marble Slurry ................................................................................ 29
Fillers for conversion of waste paper ...................................................................................... 29
Paper Industry - Sludge compatibility ..................................................................................... 30
Fillers and pigments for the manufacture of water paints ..................................................... 30
Plastic fillers (for PP and PVC) ................................................................................................. 31
Neutralization of acidic farmlands .......................................................................................... 32
Production of fertilisers ........................................................................................................... 33
Desulphurisation of fumes from thermoelectric plants .......................................................... 33
Production of animal food ...................................................................................................... 35
Recovery of lead from flat batteries ....................................................................................... 35
Production of Solvay soda ....................................................................................................... 36
Iron and steel manufacture ..................................................................................................... 36
6. Case Studies ........................................................................................................................ 37
Pigments and fillers used in the paper industry ..................................................................... 37
Neutralisation of acidic by-products ....................................................................................... 37
Desulphurisation of waste gas ................................................................................................ 38
Recovery of lead from car batteries ........................................................................................ 38
A new technology of marble slurry waste utilization in roads ................................................ 38
Recycling of Natural Stone Wastes Enriched in Calcium and Lithium for the Manufacture of
New Glass Ceramics and Glazes .............................................................................................. 38
Utilization of Marble Powder Residue in Paper Industry ........................................................ 39
7. Discussion and Conclusions ................................................................................................. 39
8. References and bibliography related to the recycling of slurries ....................................... 41
Guideline of possible application of slurries in industries Page 3
1. Summary of the report
This report presents the activities carried
out by the partners involved in the
activities of WP2: APPLICATION and REUSE
of the Slurry. The information and data
reported in this deliverable have been
obtained during the execution of the
Subaction 2.1: Identification of potential
uses for slurries. This sub-action has been
coordinated by AIDICO, which has received
the collaboration of AITEMIN, CEVALOR
and IMM CARRARA.
The activities have been carried out during
the period from 01/10/2011 to
30/03/2012. These activities are focused
on the achievement of the requirements of
the sub-action in order to describe and
identify the potential uses of the slurries
and compile this information in a guideline.
The reports present an overview of the
possible industrial applications of the
slurries used for substituting micronized
raw materials in several industrial sectors,
considering not only the requirements of
the raw materials but also the potential
demand of those sectors. In this way, an
introduction of those sectors and the
presentation of pilot laboratory
experiences done by the involved partners
at laboratory scale will be presented for
illustrating the possibilities and the viability
of the recycling procedure for this residue.
Finally, the presentation of the conclusions
and discussion will permit to establish a
starting point to carry out the activities of
the project.
Guideline of possible application of slurries in industries Page 4
2. Introduction of the
deliverable
Nowadays, the exploitation of natural
stone quarries is performed considering
environmental plans for recovering the
quarries after the end of the extraction
activities, including restoration of holes
and landscapes, reforestation of the area,
avoiding uncontrolled pouring of
pollutants, and re-using of the vegetal soils.
Nevertheless, processing of Natural stone
at factories is still producing a series of sub-
products or residues which originate an
important environmental impact because
those products are usually poured in
dumps.
Figure 1. Mountains of White slurries deposited in abandoned clays quarries in the area of Novelda, Spain.
The nature of the residues produced during
the processing varies depending on the size
of the particles. Part of those residues,
mainly large size particles, are actually
demanded by other industries to produced
agglomerated stone or aggregates used in
the building sector. On the other hand,
micronized particles, such as slurries, are
not frequently reused and are generally
poured in poorly controlled dumps. Slurries
are produced on the elaboration of natural
stone products during different stages of
the processing: cutting of blocks, cutting of
slabs and polishing of the slabs and tiles. In
those processes, very fine particles of the
stone are originated and mixed with water
which transports those residues. Particles
and water form a fluid mixture which is
usually conduced to large decantation
pools, where sediments are deposited at
the bottom. In those pools, water is almost
recuperated and recycled whereas slurries
are treated in filter-press. After filter-press,
Guideline of possible application of slurries in industries Page 5
the slurry is composed by fine particles and
water with a relationship on weight 80%
particles / 20 % water.
Chemical composition of the marble
slurries allow classifying them as inert
waste according to the European Directive
2003/33/CE due to they are composed
basically by mineral particles (calcite,
dolomite, with trace components quartz,
micas, feldspar, and clay minerals) with
ppm quantities of flocculants and remains
of resins. In case of granite, the slurries
content also significant amounts of metallic
steel grid which are used to facilitate the
cutting process in the gang-saws. These
slurries have similar physic-chemical
characteristics to the fillers that other
industrial sectors are demanding for the
elaboration of their products.
Subsequently, those residues may be used
as raw materials for other industrial
applications after characterization and
valorisation procedures.
The quantification of the slurries problem
in the natural stone sectors has been
tackled to estimate the global importance
in terms of environmental impact. In
Europe the production of natural stone is
around 22.5 Mt (data from 2005, FDP,
2008 annual report) having and estimation
of 6 Mt of slurries (referred to dry slurries).
The total amount of natural stone
processed yearly is varying depending on
the demand of the construction sector;
however, it could be accepted that for each
ton of processed natural stone products;
200 kg of slurries are generated and could
be susceptible of being used in other
applications.
In this deliverable, an detailed analysis of
possible solutions for recycling and
revalorizing the slurries has been done by
means of analysing the industrial sectors
which demand similar raw materials and
studying the previous research studies
where slurries has been used to substitute
conventional raw materials. It is important
to remark that the current management of
this waste is clearly in contradiction with
the established principles of the
environmental legislation, which point out
that recycling and revalorisation of
industrial residues becoming into a raw
material for other industries must be
always desirable to a direct deposition on
dumps.
This deliverable presents, firstly, an
overview of the industrial sectors which
demand actually raw materials with
characteristics similar to the characteristics
of the slurries. We have consider that
according to the requirements of the raw
materials the most promising sectors could
be listed as cement and concrete
production, structural ceramics including
prefabricate concrete products, bricks and
tiles, agglomerated stone industry, and
finally other potential uses such as fillers
for paintings and paper industry. A series
of conclusions will be presented in order to
consider the future applications during the
real scale tests at factories.
Guideline of possible application of slurries in industries Page 6
Figure 2. Scheme of the production of slurries in the Natural Stone processing plants
SLURRIES
RESIDUAL
WATERS
PRIMARY WATER
POND FLOCULLANT
DECANTATION CONE FLOCULLANT
RECYCLED WATER WET SLURRIES
PRESS FILTER
CUTTING AND POLISHING
PROCESS
RECYCLED WATER
REC
YCLE
D W
ATE
R
PRESSURE PUMP
PUMPING
PUMPING
GRAVITY FLOW MOVEMENTS
Guideline of possible application of slurries in industries Page 7
3. Overview of the industrial
sector with high demand
of micronized raw
materials
According to up-to-date statistical
information we can see that the waste
production in the processing of natural
stone, at a world-wide scale, reached in
2009 (Montani, 2010) values of about 42.9
million tones, which corresponds to a net
production of the processing plants of
roughly 59%.
Raw
Production
(000 tons)
Waste
Production
(000 tons)
Net
Production
(000 tons)
2003 75000 30750 44250
2004 81250 33300 47950
2005 85250 34950 50300
2006 92750 38000 54750
2007 103500 42500 61000
2008 105000 43000 62000
2009 104500 42850 61650
Table 1. World stone industry. Waste produced in processing (Montani, Stone 2010).
Figure 3. World stone industry. Waste produced in processing (Montani, Stone 2010).
Analysing the precedent data it’s possible
to observe that from 2007 to the present
days the values of
production have a small variation, what
indicates a stabilization of the markets.
Nevertheless it´s important to consider
also that the same relation waste/final
product is occurring through the years
what reflects the lack of improvement in
the overall efficiency of the productive
process. Thus the impact of the waste
production in the environment continues
has an important aspect to be considered
Guideline of possible application of slurries in industries Page 8
when we talk about the processing of the
dimensional stone.
The search for proper waste management
plans should be a priority together with all
the actions that can provide a reduction of
the wastes production at the source.
According to some data for Portugal,
obtained in the last major survey carried
out in 1998 (National Plan for Industrial
Waste Prevention – PNAPRI – 2000-2015)
were produced annually around 350,000
ton/year of sludge in the manufacturing
sector of ornamental rocks.
The extractive sector is also considered in
the statistics and also presents a significant
value for mud waste generation
corresponding to about 260,000 ton/year.
Thus it can be said that together the two
subsectors related to the exploitation of
the rock for ornamental purposes
produced annually, in Portugal,
approximately 610,000 ton/year.
It’s a fact that during the production of the
marketable elements considerable
amounts of wastes are generated, and we
can consider that the quantity of waste for
both calcite and silicate materials exceeds
always 30% of the raw material and can
reach medium values about 41% (Montani,
2010).
The processing waste can be classified in
three main categories (Figure 1) depending
on the size of the piece (OSNET vol. 9,
2004):
• Large to medium size waste called
scrap, with dimensions of several
centimeters, which originate from
broken or defective slabs. One or
more surfaces may be polished,
depending on the stage of
processing at which the waste was
created.
• Medium to small size waste
consisting of splints, flakes, chips.
These are created during trimming
of blocks or slabs.
• Small size waste consisting of fine
particles such as dust or slurry.
Figure 4. Typical waste types produced during processing operations. (I-Stone, 2006).
1. Processing
1.1. Large-medium
size waste (broken
slabs)
1.2. Medium-small size
waste (broken strips,
chips from trimming)
1.3. Fine waste
(sludge)
Guideline of possible application of slurries in industries Page 9
In what respects to the waste
production for operation we can
observe the following table which
is considered has reference for
Portugal.
Operation Wastes Quantity
(ton/year)
Sawing Stone debris
Slurry
Dust
Scrap
281.462
Cut and Polish Stone debris
Slurry
Dust
Other wastes
186.044
Selection and
Finishing
Stone debris
Dust
10.542
Table 2. Wastes produced in Portugal in the processing of dimensional stone, for operation (PNAPRI,
2001).
The values corresponding to table 2 are
referred to the total quantities of the
produced wastes. From that we can see
that the slurry production is the highest
with approximately 73% of the total. The
remain part corresponds to stone debris
and other wastes.
The composition of the slurries generated
from the processing activities depends on
the raw material and on the abrading
agents that are used in the processing
equipment which are required to process
harder stones like granite. All processing
operations (sawing, polishing, etc) require
water for equipment cooling and surface
cleaning, and thus slurries are usually
produced with a water content that
depends on the treatment developed in
the factory. Usually it’s assumed a medium
water content around the 20%-30%. The
waste will be either calcium carbonate
based or silica/aluminates based
depending on whether the original
material was marble or granite.
A waste can be considered any material
that has lost its usefulness for a particular
primary use inherent to the activity where
it was generated. In this sense and
considering the fact that the slurries are
constituted mainly with the original
material (Natural stone), while not having
the characteristics to be used in the
ornamental stone market, they keep in
theory the necessary characteristics for
their use as a raw material in other
industrial sectors. This is true especially if
we consider that the chemical constitution
of the sludge, in the case of calcareous
rocks is essentially calcium carbonate, and
in the case of the siliceous stones, silicates,
which are both of them raw material for
several industries.
Guideline of possible application of slurries in industries Page 10
The management of these wastes in order
to prevent or minimize their adverse effect
in the environment or a better efficiency of
the productive process is an essential key
for the correct functioning of the natural
stone industry considering it’s
sustainability in a more holistic approach
than considering only or in a separated way
the environmental or the economic
aspects.
An adjusted management plan in order to
try to solve the problem of the wastes
proceeding from the stone processing
industry must have in consideration some
alternative solutions to the most common
deposition in superficial dumps,
considering even that it’s possible and
desirable the value addition to the waste
with the correct preparation.
Following what it´s being stated, we can
consider that the processing (sawing, cut
and finishing) of marble and granite stone
generates large quantities of sludge which
have the potential for a broad range of
applications in a number of sectors,
including:
• Cement manufacture
• Concrete products
• Ceramics
• Paper Industry
• Fillers for pigments
• Plastics fillers (for PP and PVC)
• Treatment of acid sulphate soils
• Fertilisers
• Desulphurisation of fumes
• Animal food production
• Bituminous mixes
• Marble resin products
• Recovery of lead from batteries
• Production of Solway soda
• Iron and Steel industry applications
• Glass industry
• Disposal site liners
According to the specification of each
potential industrial application some
special attention in the preparation of the
slurries must be given taking into
consideration a wide range of variables
including: particle size and grading,
moisture content, colour, quality control,
presence of impurities and trace metals,
resource quantities and location, costs of
processing, freight, alternative materials
and so on.
One particular aspect and maybe one of
the most conditioning characteristic of the
raw materials for the referred industrial
sectors is the particle size, since some of
the applications are very exigent and have
very strict ranges. So the preparation and
control of the slurries grading curve is a
fundamental condition for the feasibility of
their use in most part of the applications.
The micronized raw materials are an
important use to consider for the majority
of the listed applications, excluding those
where particle size has a broader range like
the cement manufacture, the concrete
products or the ceramics which are at the
same time less exigent and have the
capacity to absorb the greatest waste
quantities. The problem with this “high
consuming” applications is that the waste
doesn´t have any added value and it’s
management is depending in a decisive
way from the costs related to the travel
Guideline of possible application of slurries in industries Page 11
distance between the producer and the
end user.
From the analysis of some data regarding
the use of mineral raw materials, namely
those related to Calcium Carbonate, it´s
possible to observe that, in Portugal, the
extraction of the so called industrial
minerals involving carbonated rocks has
been decreasing for the last three years.
However we must consider that the
reported uses are related mainly to the
sector of construction, what justifies the
less consumption of cement or quicklime,
and for the same reason the raw materials
associated with their production.
The quarries in Portugal produced in 2010
industrial minerals achieving values around
the 14 thousand tons, where the minerals
for the production of cement and
quicklime are the majority with
approximately 11 thousand tons.
The following table and graphic represents
the evolution in Portugal for the period
2000-2010, of the extracted minerals from
carbonated rock quarries.
Figure 5. Extracted minerals from carbonated rock quarries in Portugal.
As we stated above the use of calcium
carbonate is much more diverse and it´s
not restricted to the construction sector,
have high demands in other industries.
Recent news states that the market of
CaCo3 is a growing market being expected
for example has reported by Global
Industry Analysis, Inc, that the global
calcium carbonated market will reach the
108.5 million tons by 2015:
“GIA announces the release of a
comprehensive global report on Calcium
Carbonate markets. The global market for
calcium carbonate is forecast to reach
108.5 million tons by the year 2015.
Increasing use of calcium carbonate in
paper industries; growing demand for
Guideline of possible application of slurries in industries Page 12
precipitated calcium carbonate (PCC)1 and
nano calcium carbonate, conversion of
existing paper mills from acid-based
process technology to alkaline-based
process technology are few of the key
factors influencing market growth. Asia is
expected to spearhead growth in the
consumption of PCC worldwide, fuelled by
the significant rise in number of paper mills
and growth in plastics sector in the region
over the recent years. Meanwhile, ground
calcium carbonate (GCC)2 continues to
enjoy increasing demand from the paper
industry in paper coating applications as
well as fillers.”
(http://www.prweb.com/releases/calcium_car
bonate/ground_precipitated/prweb8064439.ht
m)
According to what is reported the Calcium
Carbonate is assumed has the “principal
inorganic mineral, primarily used as
commercial and functional filler in paper,
rubber, plastic, architectural materials,
coatings and light chemicals. Along with
talc and kaolin, the mineral (known as filler
or body pigment) finds extensive usage in
metalloid mineral applications. In addition,
calcium carbonate has long been
recognized as a useful additive for
thermoplastics and in PVC for many
applications.”
Asia-Pacific is actually the largest market
for the CaCO3, followed by Europe. By
application the Paper industry, is the
largest market for the ground calcium
carbonate, following by the plastic
industry. The ground calcium carbonate
1 PCC is made by direct carbonation of hydrated lime, known as the milk of lime process. (www.specialityminerals.com) 2 GCC is obtained directly from the limestone and marble by physical processes (crushing).
(GCC) is the preferred because of its high-
quality performance in the productive
process and also for the brightness it
confers.
In the plastic industry the GCC is the most
common filler although it competes with
Alumina Trihydrate and Talc in more
demanding applications.
The global consumption of precipitated
calcium carbonate for the paper industry is
stated to be largely concentrated in Asia
being Europe in the second position and
North America in the third. Nevertheless
the expectations for the future of the
market are quite different since Asia is
expected to grow and the others
particularly the European market is
expected to decrease due to the economic
recession.
Guideline of possible application of slurries in industries Page 13
4. Possible applications of the
slurries and preliminary
results of introduction of
the slurries as raw
materials
In this chapter of the deliverable, it is
pretended to evaluate the possibilities for
recycling the slurries after the valorisation
and characterization process according to
the demand of raw materials by other
industries. In the previous chapter, a
complete overview of the industries
demanding raw materials have been done,
and subsequently, it is intended here to
show the experiences which have been
previously developed in order to obtain
products which have been performed using
slurries as raw materials. Next points
resume those experiences and decipher
the future actions to carry out during the
real scale tests.
Slurries used as raw materials for the
cement and concrete industries
The cement and concrete industries could
be potential sectors where the marble
slurries could be used as raw materials.
Those sectors demands important
quantities of carbonates to elaborate the
products either as a raw material for the
elaboration of the cement or as a filler to
correct the granulometry and fine content
in the concrete industries. Several studies
have been carried out at laboratory scale in
order to introduce the slurries in the
production of those products showing
positive results, which will be outlined
here:
Use of marble slurries for the production of
cement
Cement is probably the most demanded
product for the building and construction
sector. The estimations about the global
production of cement in the world are
around 3300 millions of tons during 2011,
which means that a huge amount of raw
materials are demanded in order to
produce those amounts of cement. Raw
materials for cement could be resumed as
clays (silicates) and limestone. Those raw
materials are mixed and calcined for the
preparation of the clinker and after a very
fine milling process the cement is obtained.
As it was previously indicated, mineralogy
of the marble slurries (specially derived
from the processing of calcitic marbles and
recrystallized limestone) is basically
carbonates. Those slurries could
satisfactorily substitute part of the
limestone used in the fabrication of
cement. Nevertheless, even when the
suitability of the slurries as raw material for
the fabrication of cement is demonstrated,
the economic feasibility of the recycling
process will deeply depend on the distance
between the plant of processing natural
stone and the plant for fabrication of
cement.
Moreover, the control of the slurries
should be done in concordance with the
specifications of the raw materials
demanded for the fabrication of concrete,
and in this way the chemical composition
of the slurries must be controlled to ensure
the quality of the concrete.
Guideline of possible application of slurries in industries Page 14
Considering those premises, it can be
established that the recycling of the
slurries from marble industries could be
very efficient when the processing plants
of natural stone are relatively close to
plants for fabrication of cement. In those
case, the recycling of the slurries could be
total due to the demand of limestone of
the cement plants will probably pass the
production of slurries in the companies.
The costs associated to the valorisation and
characterization of the slurries is smaller
than the cost of conventional raw
materials, so it could be considered as
economically feasible.
Use of marble slurries for the production of
Self-Compacted concrete
Self compacted concretes were firstly
developed at Japan in order to enhance the
durability of the structures and increase
the sustainability of buildings at the decade
of the 80. Since that moment, SCC has
been extendedly used worldwide for civil
applications and building, representing the
most developed technology of the
concrete in last decades. This product can
be defined as the concrete compacted by
its own weight without the need of
vibrating mechanical energy or any other
system or method with no segregation,
bleeding or thick aggregate blocking.
In order to obtain the characteristics
properties of fluidity and cohesion at fresh
stage of the SCC, it is usual to increase the
volume of the mixture paste. The
increment of volume is also related to the
lubrication of the systems triggering the
fluidity capability of the mixture. Increased
paste volume will demand greater cement
content and/or the use of fine minerals
known as fillers due to their filling function,
with a particle size smaller than 125 µm;
for example, micronized limestone is
currently one of the most common fillers,
obtained by the crushing or pulverizing
process for aggregates. It is in this context
where slurries could be used after a
process of valorisation as potential filler in
SCC.
Essentially, marble slurries are mainly
composed by calcium carbonate, which is
chemically comparable to the crushed
limestone filler produced in the crushing
plants. Many researchers have
demonstrated in different studies that the
addition of calcareous (limestone)
micronized is suitable for the elaboration
of the SCC increasing the cohesion of the
admixtures and substituting part of the
cement and sand without affecting the
resistance of the concrete.
Moreover, some of those studies
compared the differences between adding
slurries or crushed fillers demonstrating
that the effect of adding the slurries could
be even advantageous against the crushed
fillers due to a high resistance to
compression and a notorious low
permeability. Other tests performed in
laboratory have shown that an increment
in the filler content could be also reduce
the addition of additives, decreasing, in this
way the cost of the SCC and keeping into
mind that the resistance of the concrete
are always comparable to the resistance
with conventional fillers and methods.
Guideline of possible application of slurries in industries Page 15
The above reasons point out that the
recycled slurries could be considered as an
excellent raw material for the elaboration
of SCC, permitting not only to re-use this
current waste but also to develop new SCC
with better performance and more
economic.
Nevertheless, there is still a significant lack
of studies at real scale tests and only a few
authors (Correia Gomes et al., Girbes I. Et
al, Calmon et al.) have carried out more
detailed studies about this topic. In some
of those studies, the results are even more
positive demonstrating that additions of 50
% in weight respect to the cement do not
affect the, or even enhance, the final
properties of the SCC products. Other
authors (Calmon et al.) demonstrated that
the slurries could entirely substitute the
addition of limestone fillers maintaining, or
even enhancing (Topcu et al) the
properties of self-compacting and
resistance of the SCC.
After all those studies, a complete
comparison between the characteristics of
the limestone fillers and the slurries was
done by Valdez et al. showing that the
grain size distribution of the slurries is
slightly smaller than the filler (figure 2) and
the chemical composition of both materials
is similar (the silicates content in the fillers
is higher than in the slurries but this issue
that not play a direct role in the
development of SCC).
According with the studies, it has been
possible to determinate that the SCC using
valorized slurries have shown very
promising results. The addition of the
slurries has not negatively influenced any
of the most important properties
demanded to the SCC and, therefore, those
residues could be considered as potential
raw materials for this industrial sector.
Guideline of possible application of slurries in industries Page 16
Figure 6. Grain size distribution and comparison between limestone filler and slurries (after Valdez et
al.)
Table 3. Chemical composition comparison (according to Valdez et al.)
In conclusion, the studies at laboratory
scale that until now have been carried out
in order to obtain a fruitful recycling of the
slurries in the industry of the SCC have
demonstrate a real potential as raw
material not only in the concrete paste but
also in the final SCC. Slurries may be
considered as appropriate filler after a
valorization process focused on the drying
and disaggregation of the slurries. This
issue represents several advantages for the
industry:
1.- It is a continuous production of this raw
material which could be supplied to the
demanded industries.
2.- The performed tests have demonstrate
that the properties of the SCC are similar or
even better than conventional products
with calcareous filler;
3.- Part of the cement may be substitute
with the slurries, reducing, subsequently
the cost of the final products.
Last, but not least, the recycling of this
residue produces and enhancement of the
environment by different ways such as
avoiding of uncontrolled pouring, reducing
Guideline of possible application of slurries in industries Page 17
the needs of exploit micronized limestones,
supply of fillers with low energy demands,
etc.
Use of marble slurries for the production of
precast concrete
The industry of precast concrete is
nowadays producing a vast amount of
products which are used in construction
and building to facilitate the building
process, decrease the prices and costs and
assure the sustainability of the sector.
Moreover, those products have many
advantages respect to the casting on the
building places such as control of the
parameters of curing, safety of workers,
repeatability using the same moulds, etc.
doing those products suitable for many
different applications in the building
sector.
Self-compacted concrete or standard
concrete could be used for the fabrication
of precast concrete, but currently it is most
common to develop products based on
SCC. In this way, as it was explained above,
the marble slurries could be used as a
potential raw material for this industrial
sector because the properties and
characteristics of the slurries (after a
previous valorisation process) are similar
and equivalent to the properties of the
micronized limestone that this sector
demand for the fabrication of precast
products. Furthermore, in this case, the
industry also requests aggregates and sand
which could be also supplied by the natural
stone companies due to those companies
produce and important volume of residues
of rocks which could be milled and used as
aggregates.
Slurries used as raw materials for the
agglomerate stone industry
Agglomerate stones (artificial stone) are
nowadays considered as a high-added
value product for the building sector. In the
construction sector, many companies are
producing different types of composites
imitating the visual aspect of the natural
stone. Those products have a good
acceptance by the final users, specially for
countertops, tables, and paving products.
Many different typologies of agglomerate
stones are in the market and all of them
demand micronized minerals for the
fabrication process. Agglomerate stone
consist basically in a mixture formed by
mineral fillers (with different
granulometries) and resins. The ratio
between fillers and resins is approximately
90-94% filler/10-6% resin.
Generally, the elaboration process of these
materials is performed by means of a
mixture of the thermal-stable resins with
the mineral fillers, which is strongly
agitated; afterwards, the mixture is poured
in moulds where vibro-compression can be
applied. In this moulds, the polimerization,
hardening and curing of the resins occur.
Then the pieces are extracted from the
moulds and finally a polishing treatment is
applied to obtain the polished finishing of
the materials. The pieces are very resistant
to flexural and compressional strengths
and lighter than conventional natural stone
products, on the other hand the thermal
resistance of those materials is limited due
to the presence of the resins.
Guideline of possible application of slurries in industries Page 18
In this context slurries could be considered
suitable raw materials for the process after
drying (for those resin based on solvents)
or wet (when the resins are water-bone
resins). The recent development of water-
borne thermosetting polymers have been
possible the addition of wet slurries (no
need for drying!) doing this process
economically feasible. The higher price of
the water-borne resins is compensated by
the savings produced by the reutilization of
slurries as raw material
AIDICO has been working on this topic in a
previous research project in order to test
the possibilities of recycling of the slurries
for agglomerate stone. In those studies,
the elaboration of agglomerated stone was
done using water-borne thermosetting
resins and slurries with the grade of
humidity normal after the filter-press
process (around 20%).
First stages of the studies were focused on
the identification of the properties and
characteristics of the slurries by means of
determination of the grain size distribution,
mineralogy, the chemical composition, and
the colour because those factors may
influence the final aspect and properties of
the developed products. Some of the
results are shown here in order to provide
a general overview of the raw material:
• Grain size analysis by laser ray diffraction.
Due to the very grain size of the slurries
particles, a dispersion of the particles using
ultrasounds was previously done, and after
adding distilled water the measurement
was performed and recorded in the
following table.
Obtained data Particle size, µm
d(0.1)
10 % of particles with diameter smaller than 1.259 μm
d(0.5)
50 % of particles with diameter smaller than 5.014 μm
d(0.9)
90 % of particles with diameter smaller than 30.332 μm
D[4.3] average diameter of the particles 12.239 μm
Table 4. Grain-size analysis
Guideline of possible application of slurries in industries Page 19
Particle Size Distribution
0.01 0.1 1 10 100 1000 3000
Particle Size (µm)
0
1
2
3
4
5 V
olum
e (%
)
RESILODOS/ RBO3O2O5, 10 February 2005 13:54:33
Figure 7. Results of the grain-size analysis of the slurries particles
• Mineralogy and chemical composition
Determination of the mineral and chemical composition of the slurries coming from the
processing of marble were done using two different techniques: X ray fluorescence and X-ray
diffraction. The results of the analysis are shown below:
SiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O TiO2 P2O5 SO3 L.O.I
0.36 0.00 0.04 0.01 0.44 55.32 0.02 0.01 0.02 0.25 0.10 43.35
Table 5. Chemical composition of the slurries with main chemical groups
Figure 8. X-ray diffraction diagram
The X-ray diffraction diagram shows that the slurries is mainly composed by calcium
carbonate (calcite) with traces of dolomite and clay minerals
0
929
1858
2787
3716
4645
5574
6503
7432
8361
9290
5 10 15 20 25 30 35 40 45 50 55 60 65 70
2Theta (Degrees)
INT
EN
SIT
Y (
Arb
itra
ry U
nit
s)
Guideline of possible application of slurries in industries Page 20
• Colour analysis
The measurement of the colour of the slurries was done using a spectrum colorimeter. This
parameter is strongly influenced by the quantity of chromatic elements present in the slurries
(Fe, Cr, Al…) and varies according with the processed natural stone. Nevertheless it is possible
to establish systems for separating the different colour of the slurries which could be used for
different application as “pigment filler”. The measurements are:
Sa
mp
le
L* (1
)
De
sve
st
a*
(2)
De
sve
st
b*
(3)
De
sve
st
i-b
lan
cura
De
sve
st
i-a
ma
rill
ez
De
sve
st
i-co
lor
De
sve
st
1 93,78 0,10 0,46 0,17 4,79 0,21 66,98 1,00 8,10 0,40 -2,92 0,30
2 92,34 0,13 0,81 0,18 6,13 0,31 57,12 1,25 11,70 0,47 -4,11 0,24
3 92,74 0,14 0,97 0,16 5,88 0,27 59,32 1,34 10,68 0,48 -4,26 0,26
4 91,53 0,14 1,73 0,25 6,96 0,23 51,29 0,89 13,46 0,38 -6,06 0,41
Table 6. Colour analysis
Afterwards, several mixtures with different proportion between slurries and resins were tested
and finally the developed products were characterized showing in general a good behaviour.
Nevertheless, the results are shown that the addition of dry slurries could produce better
results, especially when other course filler are also added to the admixture.
Figura 9. Samples of products performed with wet slurries.
Guideline of possible application of slurries in industries Page 21
Samples of products performed with wet
slurries.
The addition of wet slurries implies a
longer hardening time due to the
important water contents that are
introduced into the system. Moreover, the
addition of micronized slurries produces
and effect of filling the voids. This effect is
even more evident when sand particles are
also added to the mixture producing a
decrease on the hardening time and an
enhancement of the mechanical properties
of the products. In general, the tests have
also shown that the use of dry slurries with
conventional solvent-borne resins produce
products with better mechanical
properties, especially in terms of durability
and ageing of the samples.
Slurries used as raw materials for the
structural ceramic industries (tiles and
bricks)
Ceramic industry could be a potential user
of marble slurries, as raw materials.
Moreover has been analyzed which is the
actual situation of the market with regard
to prices, utilized amounts, delivering
times, transport and quality of the calcium
carbonate utilized in the ceramic industries
studied.
The European Union (EU) ceramic industry
is an integral part of the Community’s
economics structure, and is perhaps one of
the area’s oldest industries. It covers a
wide range of sub-sectors ranging from the
more traditional (tableware, wall and floor
tiles) to the more high-tech (technical and
refractory ceramics).
The EU ceramic industry is a world leader
in producing value added, uniquely
designed high quality ceramic products
manufactured by flexible and innovative
companies, mainly SMEs. The ceramics
industry represents an annual turnover of
around € 30 billion, accounting for
approximately 25% of the global
production, and around 350,000 jobs
throughout the EU.
The major producing countries in the EU
are Italy, Spain, Germany, the UK and
France. Production in the new Member
States of the EU appears to be strongest in
the Czech Republic, Poland and Hungary,
which all have strong ceramics sectors and
have traditionally exported to other EU
countries.
The EU ceramic industry is export oriented
with 30% of its productions sold outside
the EU market. It is generally competitive
both domestically and on international
markets. However, since the last decade
the market situation has changed
considerably with the rise of low-cost
products from new competitors in
emerging and developing countries (China,
Brazil, India, United Arab Emirates) while
persisting trade barriers prevent effective
access to important new markets.
Guideline of possible application of slurries in industries Page 22
Figure 10: European ceramic industry production value (2005-2010). Cerame-Unie.
Spain’s ceramic tile or fine industry is one of the country’s most dynamic and innovative
sectors, and is positioned firmly at the forefront of the worldwide ceramic tile industry in
terms of technological development, design and standards of service.
65% of its global turnover comes from exports, and the rest from sales on the domestic
market. The ceramic tile sector is a key industry for the Spanish economy, providing a clear
trade surplus for the country as a whole, with a coverage rate in excess of 2,000% (2010 data).
The sector's vast export capacity has positioned it amongst Spain's top 12 exporters and as the
second largest surplus contributor to Spain’s trade balance.
One of the most notable features of the Spanish ceramic tile sector is the industrial hub in the
province of Castellón (industrial cluster), centred in the area bordered to the north by Alcora
and Borriol, to the west by Onda, the south by Nules and the east by Castellón de la Plana. In
2010, around 94% of Spain’s total production came from this province, home to 81% of the
companies operating in the sector. The Spanish ceramic tile sector is estimated to provide
direct employment for around 16,200 workers, mainly in small and medium-sized enterprises.
Employment · 16.200 direct employees and more than 5.000 indirect. Total Sales · 2.548 million €
Industry Production and Sales
2005 2006 2007 2008 2009 2010
Production 609,20 608,40 584,70 495,20 324,40 366,00
Domestic Sales 1.609,20 1.799,10 1.871,00 1.460,30 918,00 801,00
Export 2.040,90 2.183,10 2.295,00 2.210,90 1.673,20 1.746,80
Total Sales 3.650,10 3.982,20 4.166,00 3.671,20 2.591,20 2.547,80
Table 7. Sales in EUR millions and production in square meters millions. Spanish ceramic tile industry.
(ASCER).
The Spanish structural ceramic sector is the
largest producer in Europe of ceramic
materials for building, with a production of
over 10 million tonnes per year (2009). This
Guideline of possible application of slurries in industries Page 23
sector is composed by 280 companies (year
2009). The Spanish structural ceramic
sector is estimated to provide direct
employment for around 9300 workers. The
Spanish structural ceramic sector is the
industrial hub in the regions of Castilla - La
Mancha, Andalucia, Valencia and Cataluña.
Besides, the calcium carbonate is used
both for structural ceramic products
(bricks and tiles) and for fine ceramics
products (pavements and coverings:
pastes and enamels), mainly white. The
calcium carbonate is added to the clay
mixture to confer it special properties
such as whiteness or correct certain
pathologies such as the expansion
caused by humidity; this last showed to
be an application with high potential
even using the marble waste mud itself
as a whole.
Then, the main re-using application
detected is the inclusion of the marble
waste mud in the clay paste to produce
salmon-like colour façade bricks. The
standard clay paste for salmon-like
colour façade bricks is normally
obtained by mixing clay for red ceramic
and clay for white ceramic (calcareous
clay); mixtures (of samples and clay for
red ceramic). The manufacture of
salmon-like colour facade bricks used
up to 15 % of CO3Ca and in order to
correct certain pathologies such as the
expansion caused by humidity could be
necessary between 2 % - 3 % of calcium
carbonate.
The two following tables show the
requirements and characteristics for the
CaCO3 and clays used in ceramic industry.
Figure 11. Spanish structural ceramic industry production (2009). HISPALYT
Characteristics Ud. Value
Guideline of possible application of slurries in industries Page 24
Characteristics Ud. Value
CaCO3 (CaO) % 99,3 (55,61)
SiO2 % 0,30
Al2O3 % 0,10
MgO % 0,20
SO3 (S) % 0,1 (0,04)
Loss on ignition (LOI) % 43,6
Whiteness (dry) % 89
Humidity % 0,14
Granulometry (µm) %
100>x>50 2,1
50>x>20 14
20>x>10 11,7
10>x>5 17,8
5>x>2 40,1
x<2 14,3
Table 8. CaCO3 characteristics in structural ceramic industry (preparation: own source).
Requirements Ud. Value
CaCO3 % Very high
F2O3 % 0,05
Granulometry % 98 % < 27 µm
Humidity % 0,1 (0,04)
Supply Regular and
homogeneous
Table 9. CaCO3 requirements in fine ceramic industry (preparation: own source).
Id Quartz Feldspar Calcite Dolomite Phyllosilicates
Red Clay 7 % 21 % - - 72 %
White Clay 3 % - 63 % Signs 34 %
Table 10. Mineralogical composition of clays (preparation: own source).
With the obtained data from the market
survey and with the specifications of use
that we have
been taken as reference in each case,
below are indicated the possibilities of
Guideline of possible application of slurries in industries Page 25
application of the wastes for ceramic
industry.
• The ceramic sector saw the
utilization of the marble mud
wastes as possible, as example, for
the manufacturing of salmon-like
coloured façade bricks, if that did
not alter negatively the physical-
mechanical characteristics of the
ceramic products.
• The marble mud waste can be a
good substitute of the commercial
calcium carbonate for its use as
corrector of the expansion due to
humidity in ceramic products.
• The muds obtained from the
mixture of different marble (kind
all-one), have lower possibilities of
reusing in some applications
(caused by color and particle size
differences)
• The humidity content of the marble
mud wastes is a problem that has
influence in the feasibility of their
use of them in other industrial
applications, particularly in the
ceramic industry. Up to this
humidity value, the mud wastes
can be transported by means of
tub-type trucks without problems.
This problem can be solve carrying
out some simple control
procedures during their pre-
treatment. It must specially be
controlled the humidity of the mud
wastes at the exit of the press-filter
that, could never be higher than
27%.
• The drying of the mud wastes could
be carried out without the need of
making high investments in drying
installations, so far as it can be
performed by natural means at
ambient temperature, being
necessary, in this case, around
three weeks of natural drying for
the mud wastes to have an
acceptable humidity value (<10%)
for their posterior manipulation.
• With regard to the application
of the recycled (from marble
wastes) calcium carbonate to
the ceramic industry (for
increasing whiteness and/or
conferring certain properties)
detailed studies had been
carried out (AITEMIN) for
determining the goodness of
the recycled waste as additive.
Characterization muds testing
The characterization testing carried out
and the methods utilized are shown in
table below. Marble waste samples were
provided by marble transformation plants
from Spain, Portugal and Italy.
Characterisation results are shown in Table
12.
Guideline of possible application of slurries in industries Page 26
Table VI: List of characterization testing.
Testing Procedures or techniques used
Mineralogy X-Ray Diffraction
Chemical
Analysis
Elements expressed as oxides were determined by X-Ray
fluorescence
Sulphur was determined with elemental analyzer LECO
PLAS ICP-AES Spectroscopy determined the rest of elements
Granulometry Galai-CIS-1
Whiteness HUNTER; ASTM E3 13
Humidity PE-027 (internal procedure)
Table 11: List of characterization testing.
SAMPLE 1 2 3 4 5 6 7MINERALOGY % Calcite 78 86 100 100 0 100 100
% Dolomite 22 14 0 0 100 0 0% Quartz 0 0 0 0 0 0 0
CHEMICAL % CaO 50,11 52,77 55,89 54,3 31,79 54,4 52,63ANALYSIS % MgO 4,43 2,74 0,59 1,24 21,37 0,55 1,43
% SiO2 0,72 0,33 0,53 0,39 0,37 1,1 2,11
% Al2O3 0,33 0,45 0,29 0,4 0,39 0,75 1,01
% Fe2O3 0,11 0,09 0,09 0,13 0,37 0,14 0,15
% TiO2 0,006 < 0,10 < 0,10 < 0,10 < 0,10 < 0,10 < 0,10
% K2O < 0,10 < 0,10 < 0,10 < 0,10 < 0,10 < 0,10 < 0,10
% P2O5 < 0,10 0,04 0,05 0,02 < 0,02 0,11 0,03
% S 0,02 0,02 0,02 0,04 0,02 0,02 0,02% Na2O 0,08 0,027 0,094 0,04 0,027 0,04 0,054
ppm Mn 41 40 22 51 134 54 81ppm Ba 6 7 9 8 5 6 23ppm Nb < 10 < 10 < 10 < 10 < 10 < 10 < 10ppm Zn 14 < 10 < 10 < 10 < 10 < 10 167ppm Cu < 8 < 8 < 8 < 8 37 < 8 253ppm Ni < 10 < 10 < 10 < 10 < 10 < 10 < 10ppm Cr 7 3 5 < 2 < 2 5 4ppm Pb < 10 < 10 < 10 < 10 < 10 < 10 16ppm As < 20 < 20 < 20 < 20 < 20 < 20 < 20ppm W < 10 < 10 < 10 < 10 < 10 < 10 < 10ppm Sr 142 115 86 172 101 86 160% LOI 44,05 43,56 42,46 43,45 45,64 42,89 42,48
GRANULOMETRY % x <2 31,47 15,14 9,54 14,55 8,5 9,11 8,67% 5>x>2 48,03 42,93 41,33 46,26 29,02 30,24 28,78% 10>x>5 20,36 20,54 24,98 31,09 24,04 16,62 24,22% 20>x>10 0,14 17,49 17,5 8,12 20,25 11,7 20,71% 50>x>20 0 3,89 6,64 0 18,19 15,81 17,61% 100>x>50 0 0 0 0 0 16,5 4,65
WHITENESS WI Hunter 83,4 92 90,3 95,3 87,4 87,6 94,7WI ASTM E313 34 61,3 54,7 81,7 37,1 40,3 73,9L 88,88 95,33 93,84 96,49 93,23 92,57 96,78
Table 12. Characterisation results of marble wastes.
An abstract of the main results is showed:
Guideline of possible application of slurries in industries Page 27
With regard to mineralogy, Calcite (CaCO3),
Dolomite (CaMg (CO3)2) and traces of
Quartz (SiO2) are the expected main
components.
Samples picked after the press-filter are
mixed wastes with higher proportion of
calcite (78-86%) than dolomite (14-22%)
while the rest of samples are practically
pure calcite except one of them which is
practically pure dolomite.
Regarding the chemical composition the
results suit those of the mineralogical
composition showing a major composition
of CaO and a minor one of MgO (which is
relevant for the samples with dolomite).
There are also present traces of SiO2 and
metallic oxides such as Al2O3 and Fe2O3,
apart from Sulphur and trace metals.
Granulometrical profiles show a very low
fraction over 20µm, which is 0%–3.9% for
samples picked after the press filter and
0%–6.7% for samples picked after the
sawing process, while it is higher (18.2%–
32.3%) for samples picked after the cut &
polishing processes and after decanting.
All the samples analyzed have a Fe2O3
upper to the requirements for fine ceramic
industry (0,05 %).
The results confirm than the utilization of
the marble mud wastes as possible, for the
manufacturing of salmon-like coloured
façade bricks.
Technological testing at laboratory scale
Once that was confirmed the possibility of
use of the marble wastes in the structural
ceramic industry some technological
testing were made at laboratory scale to
verify that the use of marble waste as
substitutive of the calcium carbonate do
not suppose one lost of the physico-
mechanical characteristics of the ceramic
product.
The laboratory testing were made to check
the influence of the mud for combating
expansion due to humidity in the ceramic
products and also to check its behaviour in
the process for manufacturing façade
salmon-like colored bricks.
0,677
0,753
0,583
0,479
0,538
0,439
0,367
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
Without addition With 1% CaCO3 With 5% CaCO3 With 10% CaCO3 With 1% waste # 1 With 5% waste # 1 With 10% waste # 1
VALUE (mm/m)
FIRED TEST PIECE
Figure 12. Correction expansion due to humidity. Fired test pieces.
Guideline of possible application of slurries in industries Page 28
Conclusions
According with the results:
• That all types of mud can be
utilized as additive to the structural
ceramic paste to correct the
expansion due to humidity.
• The utilization of the marble mud
wastes (also the commercial
CaCO3) to combat this pathology in
ceramic pieces has a negative
incidence (as it could be expected)
on the mechanical resistance of
the products, and could limit their
use for some types of products.
• The relation quality/price of the
calcium carbonate used, the very
homogeneous supply of this and
the low price made non-viable the
utilization of wastes marble in fine
ceramic sector.
• The high humidity content of
slurries and the high cost of
transport made non-viable the use
of marble waste in fine ceramic
sector..
Figure 13. Powder of mud and test samples
obtained with different % of muds
In conclusion, the marble mud waste can
be a good substitute of the commercial
calcium carbonate for its use as corrector
of the expansion due to humidity in
structural ceramic products, but it´s not
possible reuse marble muds into fine
ceramic industry by market (relation
quality/price of the calcium carbonate used
in this moment) and technical reasons
(humidity and Fe2O3 content)
Slurries used as raw materials for
other uses
The last two decades have been quite
productive regarding the development of
studies aimed at the assessment and
analysis of the use of waste from cutting
and sawing of natural stone, slurries in
particular, in other industrial activities.
It is true that scientific and technical results
have been positive and in general quite
indicative of a high potential for the use of
these materials as raw materials in various
sectors with qualitative requirements
ranging high and low exigencies, as the
pharmaceutical industry, inks, paper,
animal feed, building, etc.
However it turns out in practice that some
factors, mainly economic, overlaps the
technical possibilities and are preventing
the regular use (in significant quantities) of
these materials which could be considered
by-products. Following this the values for
the reuse and/or recycling are kept low
and the environmental impacts associated
with the current treatment – soil
deposition - prevails.
Although in general it is not possible to
consider that it was achieved a main
solution for the recovery of the slurries
produced in the manufacture of the
natural rock, it is possible to present some
successful case studies that validate
experiences that have been made and
continue to be developed, in order to
Guideline of possible application of slurries in industries Page 29
implement, mainly calcium carbonate, in
industries that need this chemical
compound as raw material.
Usually when it tackles the issue of the
management of sludge, or other residues
derived from the production process of
dimensional stones, the main approach
goes toward uses that can absorb the
largest possible quantity of residue and
therefore are not as demanding in terms of
characteristics of the raw material. This
uses include the generality of those related
to the construction, highlighting the
inclusion of waste in the manufacture of
cement, bituminous, concrete products, or
structural ceramics.
These reuses may have a very important
role in the resolution of the current
environmental problem created by the
deposition of waste at landfills; however
they present a problem that objectively, is
coming to derail the practical
implementation of that solution, already
perfectly validated. This problem has to do
with purely economic factors related to the
transport distances between the waste
producer and the location of the “recycling
plant” (cement and concrete products
factories, structural ceramics factories).
Since the residue has a low added value,
even though you do not need any extra
cost with their preparation and that the
end-user receives also at no cost (or
payment), the price of transport under the
responsibility of the producer turns
unfeasible the waste treatment under
these circumstances.
So it is important in addition to solutions
that consider massive uses, but only are
feasible if the deployment of the
"treatment place" is in the immediate
vicinity of the waste production areas,
consider other solutions of reuse that even
needing the accounting of additional costs
for the chemical or physical preparation of
the sludge pass through an appreciation of
this by-product and make it "desirable" to
other industries which, although more
exigent, may pay the added value, wich will
eliminate the distance factor as a limitation
for the use of this raw material.
Italy assumes itself as a country at the
forefront of this kind of experiences,
mainly in their regions related to the
marble industry such as Carrara and
Verona. So much of the case studies for the
reuse of sludge resulting from the
processing of natural stone, have been
taking place in Italy. However the concern
with the management of the stone wastes
is transversal and occurs in most countries
where the manufacturing sector of rocks
presents some meaning.
To define alternative paths for the reuse of
the slurries is important to consider the
specifications of some applications and
also some experiments conducted with
success.
5. Potencial application of
Marble Slurry
Fillers for conversion of waste paper
In the production of paper from waste
paper, the latter is mixed with water in a
pulper that grinds it into a pulp. This pulp is
then slowly purified by removing impurities
(metals, plastics, etc.) depending on how
thick the finished paper should be. Then,
the cleaned and purified pulp is ground
more and put in a mixer with fillers,
pigments and more water. The mixture is
Guideline of possible application of slurries in industries Page 30
very thin (with water making up to
approximately 60 %) and poured into a net,
on which the paper begins to be produced
(which basically involves removing all
excess water). Part of the water is removed
by gravity as it filters out of the net, while
other parts are removed by suction boxes.
Later on, the net is passed through various
presses, which remove more water, while
the last drying operation involves passing it
through hot cylinders which dry out the
paper with steam. Then, the dry product
passes through a polishing device which
presses it before rolling it up: the paper is
now ready to be converted into different
types of paper: glossy paper in particular is
a special type of paper that takes ink well
and must have an even and compact
surface. Calcium carbonate is added to the
mixture at the very beginning along with
fillers and pigments, and is added again
during the polishing stage, when the paper
must become suitable to take ink.
Depending on the type of paper, the
percentage of calcium carbonate added as
filler ranges between 4 % and 10 %, and
similar amounts are added during the
polishing operation. It must be noted that
kaolin and talc can also be used as fillers,
but calcium carbonate has become
increasingly important recently, since
kaolin (which used to be commonly used as
a pigment) is much more expensive to
extract and transport than calcium
carbonate. Paper products using calcium
carbonate as a pigment are: paper and
cardboard for graphic applications, paper
rolls for newspapers, writing and printing
paper, white cardboard and board (except
kraft paper), white packaging paper and
cardboard. Please note, however, that
calcium carbonate somehow wears out the
paper nets (depending on its
rhombohedral crystallisation) even if not
all carbonates are equally abrasive. To
reduce abrasion, the CaCO3 should have 60
% of its particles under 2 microns, resulting
in 50 % to 90 % of the particles used being
under 2 microns. The product is usually
supplied as a watery suspension or slurry,
stabilised by polyacrylic dispersants. In
addition, the filler should contain low
amounts of silica, aluminium silicate, iron
oxide, iron sulphur, etc. since such particles
damage the net and alter the colour
(white) of the finished products.
Paper Industry - Sludge compatibility
The use of the calcareous marble sludge
involves a preliminary selection of the
colour, particle size and purity of the
sludge. They should therefore be ground
beforehand to produce particle sizes that
are 100 % smaller than 50 microns and at
least 60-90 % smaller than 2 microns. In
addition, they should contain high amounts
of CaCO3 (at least 95 %), low amounts of
silica, and they should be evenly white and
contain no metal dust or impurities that
could alter the colour of the finished paper.
Humidity should not be a problem since
the finished product is sold as slurry. In
conclusion, white marble sludge seems
perfectly suitable for the purpose, once
they have been adequately ground and
sifted.
Fillers and pigments for the
manufacture of water paints
Calcium carbonate is used in the
formulation of paints both as filler and as
pigment. Fillers are mixed with resins and
Guideline of possible application of slurries in industries Page 31
pigments, and then finely dispersed in a
number of successive emulsions. In
particular, CaCO3 is used as an amorphous
material to make water paints, and as a
crystalline material to make primers (such
as anti-rusting agents). In water paints,
that make up approximately 90 % of
CaCO3-based paints, the calcium carbonate
fillers depends on the type of finished
product, ranging between 10 % and 50 %
for interior applications. Talc or kaolin are
generally preferred for exterior
applications.
The particle size of the limestone is
carefully checked since particles larger
than 60 microns would cause great
problems when mixed: at least 50 % of the
limestone used usually has a particle size of
less than 2 microns. Even if the
composition of the filler is usually 98%
calcium carbonate, 1% humidity and 1 %
impurities, such as silicates and other
minerals, an extender containing more
than 90 % CaCO3 is considered acceptable
provided iron, lead and other ore contents
are low enough not to alter the white
colour of the product, which is essential for
water paints. Limestone is generally used
in the form of dust: solvent paints cannot
contain more than 1-2% humidity, while
water paints contain about 40 % water, so
products having a humidity of 25 % to 30 %
would not be a problem.
Fillers for pigments - Sludge compatibility
The use of calcareous sludge could be
compatible with the production of water
paints, in which the humidity level of the
raw material is not important. Restrictions
on the calcium carbonate content (which
must exceed 90 %), whiteness degree and
metal contents that could alter the colour
can be solved, provided the sludge is
adequately selected. However, problems
remain with the particle size, so the sludge
should be ground and selected
beforehand. Consumption could be really
high, since water paints are largely used in
the building industry.
Plastic fillers (for PP and PVC)
Polypropylene (PP)
Polypropylene is a thermoplastic material
with a high softening temperature and
good elasticity and mechanical resistance.
During production, PP is mixed with varying
amounts of inert fillers, normally of
mineral origin, each one affecting the
resistance of the finished product. In
particular, it is the shape of the particles of
the fillers that determines the mechanical
resistance of the PP: spheroid calcium
carbonate provides poor resistance; flake-
shaped talc provides a higher resistance
than calcium carbonate. For instance, the
PP used in the car component industry is
almost all made of talc, since this type of
PP is subject to strict EU regulations on
impact strength (resilience) and must not
break into splinters (natural or synthetic
rubber is also added to make the product
more elastic).
Calcium carbonate is used as filler only for
rigid and less resistant materials, such as
interior decoration, packaging films, crates
(for fish, fruits, mineral water, etc.).
The properties and calcium carbonate
content used in PP with a comparatively
low mechanical resistance depend on the
finished product for which they are
intended.
Guideline of possible application of slurries in industries Page 32
The CaCO3 used to produce packaging films
must have a very small particle size (less
than 2 microns) and a filler percentage of
30-40 %, while that used to produce
packages can have slightly larger particles
(under 10 microns) and a filler percentage
up to about 60 %.
Polyvinyl chloride (PVC)
Polyvinyl chloride is a very common
thermoplastic resin used mainly in two
forms: rigid or flexible. Rigid PVC is used in
hydraulics (pipes, downspouts, autoclaves,
etc.), electrical engineering and electro-
mechanic applications (pump rotors, fans,
pipes and control boards for electric units,
etc.). Flexible PVC is used to make sheets
and rolls for sheaths and waterproofing
cloths or insulating sheaths for cables.
CaCO3 is largely used as a filler to produce
PVC, not to provide the filled material with
any special property, but just to save on
the cost of the raw materials and because
it has a better tolerance to impurities than
PP. Once again, the particle size depends
on the finished product, although its upper
limit remains 40 microns. Particle sizes of
less than 2 microns must be 20 % for belt
or strip PVC and between 50 % and 90 %
for wire insulators.
Plastic fillers (for PP) - Sludge compatibility
Calcareous sludge could be used in this
sector provided that their properties are
adjusted to decrease humidity to no more
than 0.1 % of their weight (very dry
sludge). Magnesium would cause no
problems, while the iron content should be
very low to avoid oxidative catalytic
processes, especially in the PP used to
produce packaging films or when
appearance is of concern (white), but it
would be less important in the production
of rougher materials (crates).
In any case, particle size may be a problem
since it could be reduced by grinding and
sifting.
Plastic fillers (for PVC) - Sludge
compatibility
Sludge made of marble alone seems to
have the right formulation, while its
particle size must be reduced to optimum
values just like its humidity content that
must not exceed approximately 0.1 %.
Special treatments are therefore required,
such as grinding and forced drying.
Remarkable amounts can be used, since
PVC can be filled with remarkable amounts
of inert materials (as much as 60 %).
Neutralization of acidic farmlands
Calcium by-products (calcium carbonate
CaCO3, quick lime CaO, slaked lime or
calcium hydroxide Ca(OH)2 ) are largely
used to correct the acidity of excessively
acidic farmlands. In particular, acidic soils
have a pH of 3-3.5, while alkaline ones
have a pH of 9-10. Acidity depends on the
presence of peat soils (formed in
previously marshy or swampy areas) rich in
humus acids or on the rainwater leaching
the soil for a long time. Normally,
correction involves soils with an acidity
level equal to a pH of 4.5 since lower pH
values would require different crops. For
instance, potatoes, tomatoes, corn, etc.
grow well in poorly acidic soils while other
crops, for instance alfalfa etc., need poorly
alkaline soils.
Guideline of possible application of slurries in industries Page 33
One can easily argue that calcium
carbonate is much slower in reducing
acidity than other correcting agents (CaO,
Ca(OH)2 ). The amounts to be used depend
on the acidity level and on the crop, but
the mean value can be estimated in
approximately 5 tons CaCO3 per hectare at
regular intervals (about once every 4-5
years) since the soil tends to return to its
initial pH.
Neutralization of acidic soils - Sludge
compatibility
When using marble sludge, coloured
sludge can also be used and the particle
size of such sludge seems to be fit for the
process. There are restrictions, of course,
on the content of heavy metals, which
must be equal to or lower than that
allowed for farming fertilisers. Sludge could
therefore be directly used without having
to be filter pressed or ground into chips.
Sludge could perhaps also be used as “a
slurry” (i.e. containing high amounts of
water) and directly poured onto the soil,
having been carefully raked beforehand.
There are problems, however, with the
competition of other correcting agents
(which have a quicker reaction time) and
with transport since there are not many
acidic soils in Italy and shipping these
agents to other countries (especially
subtropical countries, where acidic soils are
widespread) would be simply too
expensive.
Production of fertilisers
Calcium nitrate Ca(NO3)2 is commonly used
as a fertiliser (Davini, 1998) in farming as a
source of calcium and nitrogen and is
usually made by direct reaction between a
solution of nitric acid and solid calcium
carbonate, as follows:
CaCO3 + 2HNO3 = Ca(NO3)2 + CO2 + H2O
To speed up this heterogeneous reaction,
the contact between the reagents should
be facilitated, so the calcium carbonate
(which is generally made of adequately
ground quarry limestone) should have a
fairly low, particle size. It could therefore
be profitably replaced with marble sludge.
Fertilisers - Sludge compatibility
The particle size of these sludge seems to
be fine enough (under 300 microns) for the
intended use, and the humidity content of
filter pressed materials should not cause
any problem since the above reaction takes
place in the aqueous state (but the use of
thinner materials is not recommended, not
to dilute the nitric acid solution too much).
The usual problem remains, i.e. the high
metal content that should not exceed the
limits imposed on fertilisers, and transport.
The latter seems to be the more restrictive
one.
Desulphurisation of fumes from
thermoelectric plants
Modern society needs more and more
energy to keep developing. This is largely
produced by the combustion of fossil fuels
(coal, fuel oil, etc.) in high-power
thermoelectric plants. However, such
combustion processes also produce high
amounts of sulphur oxides (SOx) which
tend to be quite quickly transformed by
oxidation into SO3 and therefore into
sulphuric acid H2SO4. Sulphuric acid is very
harmful both to our health and to our
Guideline of possible application of slurries in industries Page 34
environment. It causes remarkable
environmental damage even from a
distance, for example "acid rain", which
damages the crops and forests and causes
irreparable damage to city monuments and
urban structures. We should consider that,
in the open air, all marble work (statues,
friezes, bas-reliefs, etc.) is transformed
from calcium carbonate into calcium
sulphate which crumbles easily and hence
destroys the work over time.
To control these problems, strict law
regulations have been enforced, limiting
the amount of SOx that can be let out
during combustion. Such pollutants are
reduced by using fuels with a low sulphur
content but it is economically unfeasible to
reduce such content to less than a given
percentage, so the waste gases produced
by combustion are adequately submitted
to the so-called fume desulphurisation
process. The "desulphuriser" used in this
case is pure CaCO3 or CaCO3 transformed
into CaO or calcined and then hydrated
into Ca(OH)2. The SOx reducing processes
can then be either “dry” or “wet”.
In “dry processes”, the calcareous dust
comes into contact with the SOx through
injection into the fume manifold at a high
temperature [7,8]. In these conditions, the
CaCO3 is effective against SO3 (of which
there are generally small amounts) and
much less effective against SO2 (of which
there are much higher amounts). To
remove satisfactory amounts of both SO2
and SO3, CaO (or better Ca(OH)2) should be
injected, which, under the effect of heat,
turn into a variant of CaO showing a large
surface area and is therefore highly
reactive. Overall, the reaction is as follows:
CaO + SO2 + ½ O2 = CaSO4
and is made quicker by traces of metal
oxides (such as Fe2O3, etc.). This
technology has some shortcomings, since:
a) the short contact time can prevent the
complete removal of SOx, b) the heat
exchangers could become soiled, thereby
reducing the overall performance of the
plant, and c) there may be problems with
the removal of the solid particulate of the
fumes.
If a solid fuel such as coal is used, the
desulphurisation of waste gases simply
starts in the combustion chamber where
coal is burnt in fluid bed systems after
having being mixed with limestone. In this
process, CaCO3 is calcined into CaO which
then reacts with SO2 and O2, thus forming
calcium sulphate (as described above) with
a reduction of more than 90% with coal
containing approximately 1 % sulphur.
In “wet processes”, combustion fumes
come into contact, in special absorption
towers, with an aqueous suspension of
lime or limestone. Such processes have a
high efficiency, removing over 95 % SOx
and using a high amount of reagents, but
they cause problems with the cooling of
the gases (to approximately 55°C) and with
the load losses caused by the “scrubbing”
process. In addition, other problems are
related to the production of high amounts
of calcium sulphate sludge (plus
combustion ashes). In particular, a number
of “wet” plants have been built that use
suspensions of calcareous materials (that,
for the sake of brevity, we will not describe
in detail), but in any case the disposal of
large amounts of calcium sulphate, which,
because of the low cost of the pure
Guideline of possible application of slurries in industries Page 35
material, cannot always be sold as
gypseous material, is something of a
problem.
Wet processes” utilise a CaCO3 suspension,
and so the humidity level of the sludge is
not a problem. But they must contain high
amounts of CaCO3 (90-95 %). Impurities are
not a problem, but iron by-products can act
as catalysts in the subsequent oxidation of
sulphite into sulphate. Their particle size
should however be checked to obtain
stable suspensions of calcareous materials.
The consumption of calcareous sludge that
could be used in this industry seems
promising in terms of amounts and
because no selection is required between
pure white marble and slightly coloured
marble.
Production of animal food
Calcium carbonate is one of the most
essential components of animal food, of
which it makes up 7 to 10 %. Of course, it
must contain no heavy metals, have a
suitable particle size and an adequate
humidity content. In particular, it can be
used as a “ventilated product” when the
grain size is smaller than 0.35 mm or as
“pellets” when the grain size is smaller
than 1-2 mm. When producing animal
feed, the “ventilated product” and the
“pellets” are often used with a mean ratio
of 1:2. In addition, the calcium content
must be at least 38% and it must not
contain any toxic substance, and for the
pneumatic batching and handling
equipment to work properly its humidity
should be very low. At present, the
limestone used by foodstuff factories
comes from quarries of white minerals
ground to the required grain size.
Animal food - Sludge compatibility
Sludge made of selected white marble
could partly replace quarry products. This
would involve, however, the production of
dry materials, checking them for purity and
low metal pollutants and perhaps also
overcoming the mistrust of end-users who
would not look favourably upon using
industrial waste to feed animals intended
for human consumption (especially after
the recent events associated with BSE).
Recovery of lead from flat batteries
The recovery of lead from car batteries
involves the use of Solvay soda (sodium
carbonate) as a flux. However, soda can be
replaced with marble dust (calcium
carbonate) resulting from the cutting
process, and the benefits here are basically
two - the reduction of production costs and
the use of scraps in a new production cycle
(Davini, 1998, Belardi, 1998). Due to the
presence of calcium carbonate mixed with
other fillers (silica sand, iron shavings, coal
and lead compounds from the batteries
(basically, lead sulphate and lead oxides),
lead can be recovered while producing
scraps that contain calcium oxide, silicates,
iron oxides and metallic iron, and
approximately 2-3 % lead. When sodium
carbonate was used, the scraps contained
soda and so were unusable and had to be
disposed of in dumping grounds for toxic
and hazardous waste. However, now that
calcium carbonate is used, the scraps
contain lime, which does not prevent its
chemical inactivation by the addition of
Portland cement, sand and a special
additive that prevents surface rust forming
Guideline of possible application of slurries in industries Page 36
on products made with a vibrating press. In
this way, a toxic product is turned into a
finished product fit for the electric
appliance industry since blocks can be
produced that (containing approximately
50 % iron) have a high specific gravity and
can therefore be used to produce padding
for stabilising the racks of washing
machines.
Recovery of lead from flat batteries -
Sludge compatibility
Marble sludge is suitable for this
application. The only problem is that the
heat treatments required by the
manufacturing process need higher
temperatures, which involve therefore
higher energy consumption.
Production of Solvay soda
In this process, calcium carbonate is the
basic reagent. It is calcined at
approximately 1000 °C, thereby
dissociating as follows:
CaCO3 = CaO + CO2.
Then, CO2 with water, NH3 and NaCl causes
sodium bicarbonate NaHCO3 to precipitate
and, by heating at approximately 200 °C, to
produce sodium carbonate as follows:
2NaHCO3 = Na2CO3 + CO2 + H2O
which is the end-product. The initial
calcium oxide CaO is slaked through its
reaction with water and restores the
ammonia by producing calcium chloride
CaCl2 (used as an anti-ice salt, to be poured
on roads in winter). Overall, the reaction
obtained from all the intermediate steps
can be summarised as follows:
CaCO3 + 2NaCl = Na2CO3 + CaCl2.
Production of Solvay soda - Sludge
compatibility
In theory, the use of white marble sludge is
viable since its formulation is similar to that
of usual materials: CaCO3 % = 90-99 %;
MgCO3 % = 0-6 %, Fe2O3-SiO2-Al2O3 % = 0-3
%. But the formulation should be constant
over time to avoid problems with the
plants. The only real problem is the fact
that calcined limestone is usually 10-15 cm
in diameter, and so the sludge should be
compressed first (maybe into pellets or
briquettes). Humidity could be removed by
these operations or during calcination.
Heavy dimensional treatments are
however required but the usable amounts
would be very high.
Iron and steel manufacture
Iron and steel materials are manufactured
in two steps: a) production of cast iron in a
blast furnace, b) refining or conversion of
the resulting cast iron.
In the blast furnace, iron minerals
(generally iron oxides) are heated along
with a reducing agent (metallurgic coke) at
a high temperature to transform iron
oxides into metallic iron (cast iron). In
addition, flux (limestone) is added for an
easier smelting of the gangue and
combustion ashes, thereby forming scraps
or slag. In the converter, the resulting cast
iron is converted into steel by hot
decarbonisation, a process in which
suitable gas mixtures are blown in to
remove part of the carbon. Once again,
fluxes, i.e. limestone, are added to remove
other unwanted components in the form
of scraps (lead, silica, sulphur, etc.).
Guideline of possible application of slurries in industries Page 37
Iron and steel manufacture - Sludge
compatibility
The chemical composition of marble sludge
is compatible with that of the flux, while its
particle size and humidity content (which
should be low) are not suitable. Calcareous
sludge should be submitted to adequate
treatments.
6. Case Studies
Pigments and fillers used in the paper
industry
Only white marble sludge is used in the
paper industry because of the very specific
requirements of paper. For these
applications, sludge is first collected by
specialist companies (for instance Cages,
based in Massa, Italy) that store them on
large yards and select them by type and
colour with mechanical shovels. If they do
not meet the required standards, they are
set aside for other applications.
Later on, the sludge that meets the
whiteness requirements is conveyed to a
processing centre, where they are
adequately ground by ceramic balls into
the required particle size. The product thus
ground is then sifted, and the particles (60
%-90 % of the particles must be smaller
than 2 microns and 100 % absolutely
smaller than 50 microns) are mixed with
anionic polyacrylic dispersants, thus
obtaining fairly stable suspensions that are
stored in large silos from which they are
sent to the paper mills.
For instance, Ti.Elle company, based in
Massa (Italy), uses (with its own patented
technology) approximately 50,000
tons/year of white marble dust from
Carrara (containing approximately 22 %
humidity) to be used in the paper industry,
of which approximately 10,000 tons (60 %
smaller than 2 microns and the rest smaller
than 50 microns) to be used as fillers,
approximately 25,000 tons (75 % smaller
than 2 microns and the rest smaller than
50 microns) to be used as pre-coating
agents and approximately 15,000 tons (90
% smaller than 2 microns and the rest
smaller than 50 microns) to be used as
coating agents proper. Usually, the
suspension has approximately 70 % dry
contents.
The quality of the products manufactured
by such technology seems so high and
competitive that the demand largely
exceeds the supply of white sludge from
the Apuan-Versilian area.
Neutralisation of acidic by-products
Calcareous sludge that is not perfectly
white (because they come from the
processing of veined marble or because
they have not been perfectly selected by
the marble processing shops) is loaded on
big covered trucks and sent to Scarlino
(Grosseto), where it is used to neutralise
the sulphuric acid by-products produced by
Societa’ Tioxide in its plants, that produce
titanium dioxide. The reaction produces
CaSO4, a gypseous material (also called
‘chemical gypsum’), by precipitation, as
follows:
CaCO3 + H2SO4 = CaSO4 + CO2 + H2O
Which is reused in the building industry.
Guideline of possible application of slurries in industries Page 38
The amounts used for the purpose are very
high: over 200,000 tons/year of calcareous
sludge, and once again the demand often
exceeds the supply (especially when, at the
peak of summer, marble processing is
reduced).
There is however the problem of having to
handle and transport the sludge to their
destination and the fact that the trucks
usually come back empty, which heavily
increases costs.
Desulphurisation of waste gas
Calcareous sludge that cannot be reused
even to neutralise acidic by-products can
be used for instance to desulphurise the
fumes produced by high-power
thermoelectric plants. Approximately 3,000
tons have recently been shipped to a 600
MW coal-fed thermoelectric plant owned
by ENEL and situated at La Spezia
(approximately 20 kilometres from
Carrara), to be used in the desulphurisation
of combustion fumes by scrubbing at
approximately 55 °C. The consumption of
sludge with a dry content of about 15 %
depends on the sulphur content of the fuel
(nominally below 1% but in fact between
0.6 % and 0.8 %). The calcium sulphate
produced by scrubbing is filtered to
produce a product with 6-7 % humidity,
which is sold to cement factories,
plasterboard factories, etc.
The preliminary findings look very
promising and encouraging, so much so
that it has been planned to extend this
treatment to more thermoelectric plants,
such as the one in Vado Ligure, in the
province of Savona, much farther from
Carrara (over 160 kilometres).
Recovery of lead from car batteries
There have been similar experiences in the
past. A company based near La Spezia used
to collect and use calcareous sludge for the
purpose (for a detailed description of the
process, see above), to produce lead and
high-density blocks for stabilising the racks
of washing machines. It is said that, by
recycling approximately 800 tons/month of
battery lead, approximately 150 tons of
marble dust were consumed, thus
producing approximately 2,000 self-locking
blocks a day. Unfortunately, the company
is closed down and so there is no other
such consumption or information.
A new technology of marble slurry
waste utilization in roads
Marble slurry dust (MSD, a waste of marble
industry, finds bulk utilization potential in
roads. This study indicates that besides
embankment construction with this waste,
20-30% of soil can be replaced by MSD for
sub-grade preparation. Technology has
been validated by taking full scale trials in
the field.
Recycling of Natural Stone Wastes
Enriched in Calcium and Lithium for
the Manufacture of New Glass
Ceramics and Glazes
Recycling of mine and natural stone wastes
is a demonstrated necessity for protection
of environment (Lottermoser, 2011), as
well as the recovering of quarries. A
natural stone from the cutting and
machining of spanish marble factory has
been used for obtaining new composition
of glasses and glassceramics. After total
physico- chemical characterization of this
Guideline of possible application of slurries in industries Page 39
enriched calcium waste and evaluation of
its production it is proposed the recycling
in the ceramics and glass ceramics
industries. Thus, for compositional and
processing design of these new vitreous
materials it has been used a lepidolite
powder from the exploitation of a
pegmatite in the Portuguese- Spanish
boundary geological region. The original
vitreous material was full characterized by:
XRF analysis, SEM /EDS analysis including
the microstructure observation, thermal
transformations by DTA/ TG and thermal
behavior under HSM (hot stage
microscopy). The nucleation and crystal
growth mechanisms in these glasses has
been evaluated from bulk and powdered
compositions and final mechanical
properties determined by indentation
methods. The capability for producing
glaze covering for porcelainized stoneware
and conventional fast firing tiles has been
also evaluated. Finally, initial
microstructure by SEM and some initial
results on mechanical properties have
been carried out for knowing the relative
glass ceramic nature of selected obtained
materials from Portuguese and Spanish
lepidolites from pegmatite exploitations
and dolomite/calcite natural rocks.
Utilization of Marble Powder Residue
in Paper Industry
The marble has been commonly used as a
building material since ancient times.
Disposal of the marble powder material the
marble industry, consisting of very fine
powder, is one of the environmental
problems worldwide today but rich in
calcium and magnesium carbonates. In this
study, recovery of carbonate from residue
of marble by flotation was studied,
because concentrated calcium carbonate is
utilized in the paper industry as coatings
but SiO2 and Fe2O3 tenors should be
inferior to 1%. A carbonate concentrate in
residue containing 10.5% SiO2 and 8.7%
Fe2O3 was obtained from a feed
containing 0.49% SiO2 and 0.81% Fe2O3
with an overall recovery of 96% by weight.
7. Discussion and Conclusions
The analysis of the potential uses for the
slurries as raw materials for secondary
industries has shown that those products,
after processes of characterization and
valorisation (in same cases), could be
suitable for substituting the conventional
micronized carbonates, which are
nowadays used in the industry. Many
applications have been detected and
analysis considering the advantages and
the compatibility showing that these
residues could be a potential raw material
eliminating the current problems of
pouring and storage in dumps.
Due to the strict restriction for some
applications, as for example the pharmacy
industry, as well as the expected
demanded volumes, it was concluded that
the most suitable applications are those
where the requirements for the raw
material are not so strict and the
demanded volume could be very important
such as cement and concrete industry,
structural ceramics, agglomerated stone
and other added value applications (paints
and papers industries). It will be also
Guideline of possible application of slurries in industries Page 40
intended to perform tests for the
production of limes and Precipitated
Calcium Carbonate.
Guideline of possible application of slurries in industries Page 41
8. References and
bibliography related to the
recycling of slurries
This deliverable has been done considering
all the previous works and studies
performed by researchers in this topic.
Some of those works are general studies to
find solutions for the recycling whereas
other studies are very concrete studies
where some tests at laboratory scale have
been performed to determinate the
feasibility of the incorporation of slurries as
raw materials to be used in other
applications. The following table shows the
most relevant works in the treated topics
during last decades.
Guideline of possible application of slurries in industries Page 42
Author (s) Year Title Book/Journal/Proceedings
- (2011)
IL RICICLO DI TERRE DA SCAVO DIM GROUP BREVETTATA UNA TECNOLOGIA INNOVATIVA PER IL RECUPERO E LA STABILIZZAZIONE CON MISCELE DI LEGANTI MEDIANTE UN’APPOSITA MACCHINA Ambiente, Anno XXII, n° 6, luglio-agosto 2011, pag. 39-41
BRGM (2010)
MANAGEMENT OF MINING, QUARRYING AND ORE-PROCESSING WASTE IN THE EUROPEAN UNION - STUDY MADE FOR DG ENVIRONMENT, EUROPEAN COMMISSION
Regione Emilia Romagna (2004)
GESTIONE DELLE RISORSE NATURALI E DEI RIFIUTI – ATTIVITÀ ESTRATTIVE
Relazione sullo stato dell’Ambiente – Emilia Romagna, 2004
-
ALTA FORMAZIONE E RICERCA IN TEMA DI UTILIZZO DEGLI SCARTI DELL’INDUSTRIA LAPIDEA
Università degli Studi di Napoli Federico II / Dipartimento di Scienze della Terra, AIMM (Associazione Italiana Marmomacchine), ISIM (Istituto Internazionale del Marmo), Universidade Federal de Rio grande do Sul e Universidade Estadual de Feira de Santana
Boda E. (2004)
SUSTAINABLE DEVELOPMENT LNDICATORS FOR THE EU NON-ENERGY EXTRACTIVE INDUSTRY
Consiglio Nazionale delle Ricerche, Iinternational organizing committee of world mining congress, 2004
- (2000)
PROMUOVERE LO SVILUPPO SOSTENIBILE NELL'INDUSTRIA ESTRATTIVA NON ENERGETICA DELL'UE Comunicazione della commissione UE, 2000
- (2006) RIFIUTI DELLE INDUSTRIE ESTRATTIVE Ambiente - 18-01-2006
Directorate-General for Enterprise, European Commission (2004)
SUSTAINABLE DEVELOPMENT INDICATORS FOR THE EU NON-ENERGY EXTRACTIVE INDUSTRY IN 2001
Colombo A, Tunesi A., Barberini V., Galimberti L. (2005)
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L’ESSICAMENTO ALTERNATIVO. TRE I METODI POSSIBILI, TRA CUI L’USO DI BIOMASSE COME COMBUSTIBILE, INCLUSE LE STESSE MELME ESSICATE Ambiente, Anno XXII, n° 8, ottobre 2011, pag. 22-23
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L'ESSICAMENTO ALTERNATIVO. TRE METODI POSSIBILI, TRA CUI L'USO DI BIOMASSE COME COMBUSTIBILE, INCLUSE LE STESSE MELME ESSICATE Hi-tec Ambiente, n. 8, ottobre 2011, pagg. 22 -23
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L'ECO-PRODUZIONE DEL CEMENTO. UN'INDUSTRIA CERTAMENTE ENERGIVORE MA CHE PUÒ USARE DIVERSE TIPOLOGIE DI COMBUSTIBILI, DAI RIFIUTI FINO AI FANGHI DI DEPURAZIONE Hi-tec Ambiente, n. 6/7, luglio-agosto 2011, pagg. 39 -40
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RICERCA PER LA VALORIZZAZIONE DELL'IMPIEGO DEGLI SCARTI DELLA LAVORAZIONE DEL MARMO NELLA FORMAZIONE DI PRODOTTI VERNICIANTI
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A NEW TECHNOLOGY OF MARBLE SLURRY WASTE UTILISATION IN ROAD
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BINDER MADE FROM MARBLE SLURRY: A SOLUTION TO THE PROBLEM
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UTILIZATION OF MARBLE AND GRANITE WASTE IN CONCRETE BRICKS
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EFFECT OF USING STONE CUTTING WASTE ON THE COMPRESSION STRENGTH AND SLUMP CHARACTERISTICS OF CONCRETE
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RECOVERY AND REUSE OF MARBLE POWDER BY-PRODUCT Global Stone Congress 2010
Husrev Yildiz A. , Karaşahin Mustafa, Kiliç Mehmet , Yazici Hüseyin (2011)
ASSESSMENT OF SHORT-TERM LEACH BEHAVIOR OF WASTE NATURAL STONE SLURRIES MIXED INTO SOILS IN ROAD AND EARTH CONSTRUCTION
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Fakher J. Aukour , Mohammed I. Al-Qinna (2008)
MARBLE PRODUCTION AND ENVIRONMENTAL CONSTRAINS: CASE STUDY FROM ZARQA GOVERNORATE, JORDAN
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PROPERTIES OF GREEN CONCRETE CONTAINING QUARRY ROCK DUST AND MARBLE SLUDGE POWDER AS FINE AGGREGATE
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RECOVERY AND VALUATION OF ULTRAFINE MARBLE DUST CONTAINED IN WASTE SLURRIES DERIVING FROM CARBONATIC NATURAL STONES PROCESSING PLANTS
Ph.D. Thesis on GEOENGINEERING AND ENVIRONMENTAL TECHNOLOGIES, Università degli Studi di Cagliari
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Author (s) Year Title Book/Journal/Proceedings
- 1999
DEVELOPMENT AND IMPLEMENTATION OF A PILOT UNIT TO RECOVER SOLID WASTES AND SLUDGES FROM THE MARBLE INDUSTRY Technical report
- 1999 BEST AVAILABLE TECHNIQUES FOR CEMENT INDUSTRY CEMBUREAU report