wastes: excellent raw materials - universidade de coimbra · 2012-12-13 · wastes: excellent raw...

Wastes:

Excellent raw

materials 12/12/12

Teresa Vieira

Introduction

Recycling → Raw material

Environment

protection

Social

development

Economic

growth

Inorganic industrial wastes

Ceramic

1. Slate wastes such as for flooring (award of Innovation – Tecktonica 2001);

2. Slate wastes as additive

3. Sludge from aluminium surface treatment

a. explosive compaction such as

b. Extrusion as additive

Metallic

4. Metallic chip from machining processes

Introduction 3

1. Slate

Industry of extraction of natural resources (Portugal)

Thousands of tons of clay are

extracted per day The inefficient use leads to the depletion

Extraction of slate generated

about nine tons of powder per day In the most cases there are deposited in

landfills

Recycling slate wastes through the incorporation in clay

Technical behavior

Technical performance

Economic sustainability

Impact on the environment

1. Slate

To understand the role of the slate wastes in the

properties of the final product

To obtain a new product with better properties than

those resulting from traditional raw materials

Study the effect of slate wastes by incorporation in two different

types of clay

using two different particle sizes of slate

1. Slate

Density (kg/m3) d50 (µm) Phases

Unusable 2.74 7.6

Q – Quartz

M – Muscovite

K - Kaolinite

Conventional 2.60 25.5

Q – Quartz

M – Muscovite

C - Chlorite

7.4 Q – Quartz

M – Muscovite

K – Kaolinite

S - Smectites

B 65.0

1. Slate

Mixing and

homogenization

Extrusion

Drying

Sintering

1. Slate

Processing properties

Parameters Material Unusual Clay Conventional Clay

Additive Slate A* Slate B* Slate A Slate B

% 0 5 10 5 10 0 5 10 5 10

Shrinkage % 4.4 4.3 4.4 4.2 3.7 7.6 7.1 6.8 6.8 6.5

Total water % 27.1 26.8 27.8 27.8 24.3 23.5 23.1 23.7 22.8 23.6

Weigth loss % 4.5 4.5 4.5 4.6 4.8 6.3 5.6 5.3 4.7 4.5

conventional clay presents the highest values of shrinkage

unusable clay needs more water content to be processed than

the traditional one

weight loss remains almost constant to the unusable clay;

when slate is incorporated conventional clay has a slight

decrease of weight

*Slate A – low size distribution

*Slate B – high size distribution

Physical properties

1. Slate

Parameters Material Unusable Clay Conventional Clay

Additive Slate A Slate B Slate A Slate B

% 0 5 10 5 10 0 5 10 5 10

density g/cm3 1.7 1.7 1.6 1.7 7 1.9 1.9 1.9 1.9 1.9

porosity % 39.6 39.0 40.7 39.0 38.9 27.7 26.9 28.5 27.8 27.5

absorption % 20.1 20.0 20.8 19.9 19.0 14.1 13.3 13.9 13.6 13.7

the addition of slate not change the bulk density

the unusable clay has higher porosity than the conventional

insignificant variations of water absorption was observed by

the presence of slate waste

Thermal conductivity

% 0 5 10 5 10 0 5 10 5 10

Thermal

Conductivity W/(m2.˚C) 0.31 0.32 0.32 0.31 0.36 0.61 0.63 0.62 0.61 0.63

Unusable clay shows much thermal resistance than

conventional clay

In both type of clays the thermal resistance is not affected by

the incorporation of slate, whatever the content

10 1. Slate

1. Slate

Compressive strength

% 0 5 10 5 10 0 5 10 5 10

Compressive

Strength MPa 11.7 14.2 12.5 14.9 13.8 28.9 33.7 35.4 31.2 31.8

Standard

desviation 0,84 1,02 1,11 0,98 1,14 0,81 0,82 1,07 1,09 1,04

After consolidation as expected the unusable clay has lower

mechanical strength than conventional clay submitted to the

same firing cycle

In unusual clay 5 % of slate addition improves slightly the

mechanical strength

In conventional clay the addition of slate also induces an

improvement of mechanical strength

The incorporation of slate wastes in clays can

improve the mechanical resistance without

affecting negatively the thermal conductivity…

… but, it will be possible to improve

these to parameters simultaneously???

1. Slate

Sludge from anodizing and lacquering industry

1. Slate

Incorporation of slate + anodizing sludge

shrinkage Plasticity

density

porosity

absorption

Thermal

Conductivity

Compressive

Strength

% % % g/cm3 % % W/m2.˚C MPa

Clay 7.6 23.5 6.3 1.9 27.7 14.1 0.61 28.9

Clay bi-added

(slate and sludge) 6.5 26.2 7.5 1.7 33.6 19.3 0.50 34.6

This new formulation shows that the addition of sludge

slightly increases the porosity and water absorption, but yet

lower than the values of standards for clay products

The values of the thermal conductivity are improved (18 %)

The presence of slate continues to contribute to an increase

of mechanical strength (20 %)

1. Slate

It is possible to produce a new “composite” for efficient

building (matrice = clay; a mechanical reinforcement = micro slate and a

thermal reinforcement = nanocrystalline aluminium sludge), with high

mechanical performance and thermal resistance, allowing

the recycling of two industrial by-product

The use of smaller particle size, without any

previous treatment, leads to the best properties

The addition of anodizing sludge into the

mixture improves the thermal conductivity

without affecting the former enhanced

mechanical resistance

Production of -alumina (1650 ºC)

Induces an agglomeration of the particles and reduction of specific

surface area

Reduction their sinterability.

Explosive compaction: distort the crystal lattice, activate the particle

surface, particle fragmentation

Promoting the sintering process

After explosive compaction and sintering: density and hardness similar

to commercial -alumina

These results make this strategy to recover aluminium sludge

impossible due to high energy costs

2b. Sludge - explosion

Decrease the environmental impact of the heat treatments

(calcination and sintering)

Study the explosive compaction of sludge calcinated at low

temperature (800 ºC) and subsequent sintering

The sludge as-received had aluminium hydroxide and water

After heating at 800ºC the main phase was -alumina

Density: 2850 kg/m3

Mean size of particles: 31 m

In both cases the nanometric character of the crystallite size is evident.

20 40 60 80 100

T=800oC

As received

nsity [

2 mm 2 mm

Before explosion

After explosion

Sulphur quantity

4.5% (w/w)

0.04% (w/w)

20 40 60 80 100

Before explosion

After explosion

nsity [

Phase Density

-alumina 2850 kg/m3

-alumina 3930 kg/m3

Explosion

Patm →T>1200 ºC Patm →T>800 ºC

Explosion

Process Explosion

Explosion and sintering

1 h at 1200 ºC 1 h at 1650 ºC

Hardness [GPa] 4.91.0 8.61.4 15.60.8

Process of Compaction

Hardness *[GPa]

1h at 1650ºC 4h at 1650ºC

Sludge at 160ºC

Explosive 7,9±1,3 8,5±1.4

Explosive 12,0±1,5 15,0±1.6

CommerciaAlumina

Uniaxial 11,2±1,3 13,0±0.9

Explosive 17,4±1,3 20,2±2.1

Explosive 17,9±1,5 17,9±0.8

*A.R. Farinha, J.B., Ribeiro, R. Mendes, M.T. Vieira, Sock activation of α-alumina from calcinated Al-rich

sludge, Ceram. Int., 35 (2009) 1897-1904.

From sludge calcinated at 800 °C (-alumina and sulphates), by

explosive compaction it is possible to produce -alumina with low

sulphur content.

The sintering after explosive compaction leads to parts with

hardness values close to those of alumina produced by conventional

techniques.

Possibility of recovering this type of sludge to produce parts of -

alumina

Future work

Optimization of sintering at low temperatures and the possibility of

using sludge calcinated at temperatures below 800 °C to minimize

the environmental impact.

ANODIZING AND LACQUERING

INDUSTRY

Officially recognized as a highly polluting industry: 1000 tons of residual sludge each year ;

Cost of sludge management:55€/ton;

Location:

Viana do Castelo, Portugal

Sludge characteristics

Nano cristallyne

Non toxic (List of waste 19 02 06)

Odorless

Water content (77%)

Is this a waste… or a raw

material?

2a. Sludge - extrusion

To develop a thermal resistant brick by adding aluminium sludge in bricks

production (recycling):

using all the sludge;

avoiding the landfill disposal

developing one product (brick) without significant costs

KEY-POINTS OF THE RECYCLING

PROCESS

Cost of the sludge transport: 15€/ton;

Previous treatments required;

Use of the real parameters of the plants operations;

Recycling the waste to produce a product with added-value.

Transport provided by transporting lines of the bricks that already exists;

Disagglomeration of the sludge

Clay and production cycle of Preceram;

Addition of sludge to produce a brick with thermal comfort properties.

STAGES OF THE RECYCLING PROJECT

1. Laboratory tests and Pilot line: feasability assessment

2. Full scale test: industrial viability assessment

Preparation Shaping Drying Firing New product

Characterization

1. Laboratory tests and Pilot line: feasability assessment

Characterization of raw materials;

Technological behavior of the mixtures;

Technical properties of the ceramic material;

Nano crystalline character of sludge: using synthetic gamma alumina

nanoparticles (nano crystalline)

d50 wt. % additive

Clay m 15.56 0

Synthetic γ-alumina

nanoparticles nm 50 5

Agglomerated sludge m 4.87 5

NEW CERAMIC

TECHNOLOGICAL BEHAVIOR

Physical properties of new ceramic material

Formulation Clay Clay +

5% γ-alumina

Clay +

5% Sludge

Total water* (%) 18,4 29,7 24,8

Total shrinkage (%) 5,0 9,3 5,8

Weight loss (%) 3,1 6,7 5,3

The presence of additives increases the needs of water, which is

responsible for the less technological behavior;

Range values of water content for extrusion: 15-25%;

*To be extruded

Pore diameter distribution

5% γ-alumina

Clay +

5% Sludge

Bulk density (g/cm3) 2,0 1,8 1,7

Real density (g/cm3) 2,5 2,7 2,6

Total porosity (%) 28,0 33,6 35,9

Water absorption (%) 13,7 18,6 18,9

NEW CERAMIC

PROPERTIES OF THE MATERIAL AFTER FIRING

The presence of additives increases the

porosity;

Nanoalumina produces a bimodal curve:

submicrometer and nanometer porosity;

Maximum value of water absorption: 20 wt.%.

NEW CERAMIC

TECHNICAL BEHAVIOR OF THE MATERIAL

5% γ-alumina

Clay +

5% Sludge

Compressive strength (MPa) 22,0 14,3 13

Thermal conductivity coefficient

K ( W/mºC) 0,70 0,42 0,52

Mechanical test and fracture observed

in the samples

Decrease of mechanical strength, according

to the tipical value of tradicional bricks;

Decreasing of Thermal conductivity : 25%

I. Laboratory tests and Pilot line: feasibility assessment

Remarks

Content of water to extrude and its effects

Water absorption and mechanical strength: technical standards and market

requirements

The nanometric character is important: the presence of nanoparticles induces

better values of thermal isolation; BUT the cost of disagglomeration is too

hight to this particular case

The addition of agglomerated sludge (without significant cost of

disagglomation) produce similar effects, due to the nanocrystalline character

of the agglomerates

It seems to be feasible to recycle the aluminium sludge in bricks production

1. Full scale test

Technological behavior of the mixtures;

Technical behavior of the new brick: in agreement to technical

standards and market requirements.

TECHNOLOGICAL BEHAVIOR

Formulation Clay Sludge

Total water (%) 16-18 19,7

Industrial trial observations:

The extrusion occured without significant variations in the production parameters, but is

was needed a slight increase of water content

Good homogenization of the mixture

No visible defects during extrusion, drying or after the firing

TECHNICAL PROPERTIES OF THE NEW BRICK

Brick New brick

Net dry density (kg/m3) 2030 1920

Water absorption (%) 9,5 12,5

Porosity (%) 56 60

TECHNICAL PROPERTIES OF THE NEW BRICK

Brick New brick

Compressive strength (MPa) 7,3 6,3

Thermal conductivity coefficient

k ( W/mºC) 0,53 0,34

Transmission coefficient

U numerical method (W/m2ºC) 0,82 0,65

Aluminium sludge can be recycled as an additive for clay bricks:

enhancing the thermal behavior of bricks up to 36%, without increasing the

brick production cost;

the physical-mechanical properties still are in according to the standards

(water absorption and compression strength);

Finally, it can be stated that the sludge nanoparticles should lead to better

properties, but it is too expensive to disagglomerate for applications like bricks.

CONCLUSIONS

A new thermal brick is coming soon, in a

wall close to you!

High speed

machining

Chip Plastic deformation

Micrometric or nanometric

grain size

Processing

Improve of mechanic properties

3. Metallic Chips

Conventional chips

RECYCLING

Chips of High speed

machining

Product with high value

3. Metallic Chips

Explosive: ANFO

Detonation velocity: 2.7 mm/µs

Al_5_3A >1mm

Al_5_3B <1mm • Without defects;

• Some porosity;

• Deformation;

• Grain not well defined.

3. Metallic Chips

Aluminium alloy 5083

FWHM Integral breadth

Crystallite size(nm)

Sherrer Equation

Chip <1mm 32 29

Al_5_2B 39 30

Al_5_3B 40 31

Chip >1mm 37 28

Al_5_3A 39 30

Pressed chip :

Crystallite nanometric

After dynamic consolidation:

Crystallite nanometric

Sherrer equation

3. Metallic Chips

Al alloy 5083

0 2000 4000 6000 8000

Distance to periphery (µm)

Al_5_2B

Periphery Centre .00

0 2000 4000 6000 8000

Al_5_3A

Al_5_3B

Periphery Centre

Macrohardness commercial: 0.91-1.4 GPa

“in accordance”

3. Metallic Chips

Explosive emulsion 15 & 5% MEOV

Detonation velocity: 3.7 & 4.8 mm/µs

Al_6_4B < 1mm

Al_6_6B >1mm Grain size

micrometric

• Without defects;

• Low porosity;

• Grain not well defined in some regions.

3. Metallic Chips

Al_6_5B

Al_6_6B

Consolidation

3. Metallic Chips

0 2000 4000 6000 8000 10000 12000

Al_6_5C

Al_6_5B

Periphery Periphery

Central region

0 2000 4000 6000 8000 10000 12000

Al_6_6B

Periphery Periphery Central region

3. Metallic Chips

Al alloy 6061

Macrohardness commercial: 0.751-1.39 GPa

“in accordance”

Al_7_9B >1mm Al_7_9B >1mm

3. Metallic Chips

Explosive emulsion 5% MEOV

Detonation velocity: 5 mm/µs

• Insignificant defects;

• Low porosity;

• Grain with elongated shape.

Al_7_9B Al_7_9B

Consolidation between two chips

3. Metallic Chips

0 2000 4000 6000 8000 10000 12000

Al_7_9B

Perifphery Periferia Central region

Different behavior in

the periphery

3. Metallic Chips

Al alloy 7022

Macrohardness commercial: 1.27 GPa

“in accordance”

Grain size

micrometric

Cu_8B <1mm

3. Metallic Chips

Copper

Explosive emulsion 5% MEOV

Detonation velocity: 5 mm/µs

• Without defects;

• Low porosity;

• Possibility of nanometric

grain in the periphery.

dendritic

structure

Example bond between

3 chips

Cu_8B Cu_8B

3. Metallic Chips

Copper

0 2000 4000 6000 8000 10000 12000

Periphery Central region Periphery

Centre

Less hardness

Higher grain size

Periphery

High hardness

Possibility of

nanometric

grain in the

periphery

3. Metallic Chips

“Hardening”

Emulsão explosiva - 5% MEOV

Velocidade de detonação: 5,0 mm/µs

H13_7B < 1mm

H13_7B <1mm

3. Metallic Chips

Steel H13

Grain size

micrometric

• Low porosity

H13_7B H13_7B

Z1-vanadium carbide

Z2-molybdenum carbide

Z3-chromium carbide

Consolidation very

efficient

3. Metallic Chips

0 2000 4000 6000 8000 10000 12000

H13_7B

Periphery Periphery Central region

Dissolution

of primary

carbides

Martensite

3. Metallic Chips

Steel H13

“Hardening”

Al alloy 5083 • ANFO (2.7 mm / ms) efficient in compaction but not in the consolidation;

• Without macrodefeitos, porosity;

• Grain size submicrometric or nanometric;

• Hardness low for the grain size.

Al alloy 6061 • Emulsion + 15% or 5% hollow glass microspheres Consolidation

• Without macrodefeitos, low porosity;

• Grain size micrometer;

• Regions with efficient bond between chips;

• Hardness in accordance with the commercial values .

Al alloy 7022

• Defects in the central;

• Consolidation between efficient chips;

• Some non-symmetrical hardening.

3. Metallic Chips

Copper

• Without macrodefects;

• Low porosity;

• Central zone with grain size of micrometer;

• Dendritic structures (melting);

• Different states consolidation;

• Hardening symmetrical in the periphery.

Steel H13

• Overheating in the central zone;

• Central zone with micrometric grain size but high hardness (enriched in carbon

martensite);

• Efficient consolidation.

Promising technique for the production of nanocrystalline metallic

materials and sub micrometer, but needs optimization in particular the

shock wave

3. Metallic Chips

•Challenge of minimizing weight and costs is increasingly assertive and requires the use of

new materials and new manufacturing solutions.

• Among the many advantages of starting with powders, the excellence of the resulting

properties should be highlighted. Indeed, it has been widely demonstrated that metallic

materials with grain size below 100 nm.

• Task has not proved easy to perform, especially when applied to nanosized metallic powders,

not only due to handling difficulties, but mainly due to their high chemical reactivity and high

grain growth kinetic.

Innovation Industrial Project

• Tool steels chips

• Bimodal grain size (micro and nanocrystalline)

• Hybrid materials

Future work

Teresa Vieira (teresa.vieira@dem.uc.pt)

Ana Rita Farinha

Cecília Lavrador

Ivânia Marques

Sílvia Godinho

Vanessa Neto

Thank you

wastes: excellent raw materials - universidade de coimbra · 2012-12-13 · wastes: excellent raw...

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