rubber recovery and reuse

Rubber – Recovery and reuse

Luis Tormento – February/2017

Considerations

The safe disposal and reuse of waste rubbers from industrial or post-consumer is a serious challenge to the environment and to public health. Rubber goods are chemically crosslinked rubbers; Are the most difficult materials to recycle, since they can not be dissolved or melted. Generally, rubber recycling can be done through the following techniques:

Recycling

• Reuse

• Size reduction and powder production;

• Devulcanization and regeneration;

• Chemicals recovering and energy

What is rubber?

• The natural rubber is extracted from the South America tree of the species Hevea Brasiliensis.

• Currently, about 90% of all natural rubber comes from plantations in Indonesia, the Malay Peninsula and Sri Lanka.

What is rubber?

• The rubber is extracted from the trees in the form of latex. The tree is "bled" by diagonal cuts, where the latex flows, and is collected in small containers.

• The average annual production is 2.5 kg per tree or 450 kg per hectare; Some special trees can produce 3000 kg per hectare.

What is rubber?

Hevea Brasiliensis

What is rubber?

• The extracted latex is mixed, diluted in water and coagulated by means of acids.

• It is pressed between rollers to form thin sheets.

• It is air dried or smoked and sent for consumption.

Synthetic Rubber

• There are several types of synthetic rubbers. They are produced in a similar process like plastics, by a chemical process known as polymerization.

• We include here: CR, SBR, NBR, BR, IIR, etc.• Many rubbers have been developed for

specific applications, such as butyl rubber which, because of its low permeability, is used inside tires.

Rubbers

Rubber type Use

Natural Rubber Commercial vehicles such as cars, buses and trailers

SBR and BR Cars, motorcycles and bicycles

Butyl rubber (IIR) Tubes and tubeless tires

Rubber Good Production

• Modern rubber manufacturing processes involve a sophisticated series of processes, such as:– Mastication– Mixture– Lamination– Pre-forming– Molding– Vulcanization

Rubbers Compounds

• The raw materials that enter in a rubber artifact still comprise:– Polymers– Activators– Fillers (carbon black or minerals)– Antidegradants– Plasticizers– Vulcanization Accelerators– Vulcanization agents– Flame Retardants– Dyes or pigments– Softeners

Rubber Compounds

• Besides that, are used:– Fibers– Metals– Textiles– Etc...

• After the vulcanization we will have a unique piece, where all the components are intertwined and sometimes so united that they difficult the separation.

Vulcanization

• To understand the vulcanization process:– We must know that rubber has many polymer chains,

long and flexible. Vulcanization joins these chains to prevent their displacement and ensure their elastic characteristics.

– The vulcanization process occurs by heating this rubber in the presence of sulfur. Selenium and tellurium do the same function, but sulfur is the most common.

Vulcanization

• Rubber molecule with sulfur

Vulcanization

• The most commonly used vulcanization processes are two:– Vulcanization under pressure - this process

involves heating the rubber with sulfur, under pressure @150°C. Many articles are vulcanized in molds that are compressed by hydraulic presses.

Vulcanization

– Free vulcanization - this process is used when vulcanization under pressure is not possible, such as continuous vulcanization, and extruded products. It occurs by the application of steam or hot air.

Why regenerate or recycle rubber?

• Rubber recovery involves difficult and complicated processes. There are many reasons for the need to regenerate or reuse rubber:– Recovered rubber can cost half the price of natural or synthetic

rubber.– The recovered rubber has some properties that are better than

the rubber in the virgin state.– The production of rubber from regenerates requires less energy

in the total production process than the virgin material.– It is an excellent way to recover flash or defective parts.– It retains non-renewable petroleum products, which are used to

produce synthetic rubbers.

Why regenerate or recycle rubber?

– The regeneration activity can generate jobs.– Many useful products are derived from reuse

of tires and other rubber products.– Incineration provides energy. Burning the

rubber can generate a very high amount of energy. Some cement plants use waste tires as a source of energy.

Recuperação da borracha

• Alternativas de recuperação– Existem muitas maneiras pelas quais os

pneus e câmaras podem ser reutilizados e regenerados. A regra de gerenciamento de resíduos sugere a seguinte hierarquia: reuso, reciclagem e geração de energia, como opções superiores ao gerenciamento de resíduos e disposição

Recovery of rubberType of Recovery Process of Recovery

Reuse of the product Repair • Retreading• Regrooving

Physical reuse • Use as weight• Use as form• Volume use• Use of its properties

Reuse of material Physical • Cut out• Granules reuse

Chemical • Regeneration

Thermal • Pyrolisis• Combustion

Reuse of energy • Incineration

Reuse of Product

• Damaged tires are frequently repaired:– Tubes can be repaired and tires can be

repaired by several methods.– Regrooving is a practice that occurs in many

countries, where road speeds are lower. It is often done manually and requires a lot of manpower.

Product Reuse

• Regrooving

Product Reuse

• Retreading

Product retreading

• Retreading save energy and resources.– A new tire uses the equivalent of 23 liters of

crude oil in raw material and 9 liters in process energy.

– A retreaded tire uses 7 and 2 liters, respectively.

Product Reuse

– Passenger car tires can usually be retreated once, whereas truck tires can be retreated up to 6 times.

– About 70% of truck tires are suitable for retreading.– About 15-20% of car tires are suitable for retreading.– The picking technique is well established and safe.

The process involves the removal of the remaining tread and the placement and vulcanization of a new tread.

– The prices of retreaded tires are about 20% lower compared to a new tire.

Product Reuse• There are three known methods of retread.• Cold Retreading

– A new preformed tread is “bond" to the carcass. The new tread may be a strip or a "ring" that is stretched over the carcass.

• Hot Retreading– A new tread is remolded of the carcass. The tread is

heated under pressure and vulcanized, adhering to the casing.

• Remoulding– It is similar to hot retreading but involves the complete

modification of the surface, including the sides.

Product Reuse

• The secondary reuse of the whole tire is the second stage of waste management. Tires are often used for their size, weight, shape or volume. Some examples are:

Product Reuse

– Erosion control– Protection of trees– Artificial Reefs– Fences– Garden decoration– Shock Absorbers on Docks.– Collision protectors.– Water containers.– Swimming pool assistants

Product Reuse

• Protection

Material Reuse

• The next step in our hierarchy involves reuse for the production of a new product.

• Tire-derived reuse rubber is as easy to process as leather, and in fact has replaced it in many applications.

Reuso do material

• As ferramentas utilizadas nesta recuperação são simples: tesouras, facas, alicates, martelos, etc..., e muitas outras improvisadas para o uso.

• Os produtos mais representativos são:

Material Reuse

• Soles and sandals

Material Reuse

• Decoration

Mirror Breakfast Table

Mats Toys

Material Reuse

• Decoration

Vase Clock

Material Reuse

• Handicraft– Belts

Material Reuse

• Handicraft– Woman purse

Reuso do material

• Artesanato– Bolsas

Reuso do material

• Artesanato– Pastas

Material Reuse

• Another form of physical use of rubber waste resides in its granulation and subsequent use.

• It is a process of greater investment in equipment and distribution network.

• Rubber wastes from retreading processes and process leftovers can be used in this application.

Material Reuse

• Granulating Equipment

Material Reuse

• Granulated

Material Reuse

• The granulates tend to be used in products of low cost and quality, such as:– Car Mats– Shoe soles– Wheels for cart and wheelbarrow– Added to the asphalt, where it improves some

characteristics of the roads.

Material Reuse• Uso of granulated material

– Roads and pavements

Roads Playgrounds

Public tours - Walmart Public tours – Universal Studios

Material Reuse

• Use of granulated materials– Roads

• The potential market for the use of granulated rubber on roads is in the order of thousands of tons, which literally exceeds the availability of scrap. The barriers to its use are:

– As an aggregate, rubber competes with fragmented rock, of lower cost;

– Roads that used rubber in the asphalt, had their useful life extended, but the cost was doubled;

– There is an increase in the emission of pollutants during the re-seizing of roads made with rubber;

Material Reuse

• Use of Granulated Material– Moulded products

• The potential market for the use of granulated rubber in molded products is significant. The barriers to its use are:

– The granulate competes with other lower cost fillers;– The market demands consistency of quality and security

of supply.

Material Reuse

• Use of granulated material– Paving

• The potential market for the use of granulated rubber in paving of athletics tracks and equestrian arenas has grown. The barriers to its use are:

– Availability of a product of constant quality and competitive cost;

– Competition with existing products.

Material Reuse

• Use of granulated material– Adhesives

• Adhesives is one of the largest markets for the use of granulated rubber, currently supplied with granular tires.

– This is an already existing market and it is not clear how it will grow with the expansion of granulated rubber offer.

Material Reuse

• Use of granulated material– Loose granulated material

• Currently its greatest use is in playgrounds, but it is possible to use in absorption, explosives and drainage. The barrier to its use is:

– Availability of suitable granulates and application knowledge.

Chemical and thermal recovery

• This type of recovery is not only low in the waste management hierarchy, but also involves sophisticated, high-tech equipment.

• Chemical recovery consists of heating the rubber residue, treating it with chemicals and then processing the rubber mechanically.


– Recuperação ácida – Utiliza ácido sulfúrico quente para destruir o tecidos incorporados ao artefato, além de conferir ao composto de borracha plasticidade suficiente para permitir seu uso como carga na borracha crua.

– Recuperação alcalina – A borracha é regenerada através do tratamento com álcali aquecido de 12 a 30 horas; esta borracha regenerada pode ser utilizada com borracha crua para reduzir o preço do artefato final. A quantidade a ser utilizada dependerá da qualidade do reciclado e das especificações do artefato.


– Devulcanization - reported as a process that uses large amounts of energy and chemicals that can be hazardous to the environment.

– CSIRO process - a technique developed to treat the surface of the granulate, modifying it to be compatible with any substance. It is a process in development stage and beginning of commercialization.

– Recycling with latex - The process involves the coating of the granules with latex, which improves its adhesion to other substrates.

– Gaseous phase halogenation - The process halogens the granulate, oxidizing its surface and allowing its compatibility with other substrates.


• Pyrolysis is the most common form of use in thermal recovery. It involves heating the waste in the absence of oxygen, which causes its decomposition in gases and other components.


• Thermal decomposition of tires produces:– Carbon Black (22%);– Oil (30%);– Gas (28%);– Steel (10%); and– Small amount of inorganic ash 5%)


• Use of products resulting from pyrolysis– Carbon Black - Used in a wide variety of

applications in the rubber industry - Tires use about 20% carbon black.

• The value of carbon is determined by purity and VOC content. The limiting factors are the achievement of the required quality standard and a competitive price.


– Oil - The pyrolysis oil is similar to diesel and can be used as fuel. Due to its high content of aromatics it is valuable to the chemical industry.

– Steel - Steel recovered from pyrolysis tires contains numerous metallic impurities, which affect its quality and limit its sale value.

Energy Recovery

• Incineration to generate energy in various processes.– Cement kilns - Tires are used as fuel instead

of coal and natural gas. Between 5 and 7 GJ of energy are used in the kiln for each ton of cement produced. Tires can replace 15% of this fuel.

Energy Recovery

– Co-incineração – é um processo de combustão onde os pneus são utilizados em conjunto com outros combustíveis para gerar energia. As razões desta co-incineração são:

• Poluição• Dificuldade de manuseio

– Combustão direta – Processo de combustão para geração de energia em substituição ao carvão

Landfill

• Sanitary landfill

Landfill

• Landfill is the final step in the waste management hierarchy.

• Properly managed landfill is not an environmental problem. However, pressures to conserve resources and energy have generated strong opposition to its use.

• The improperly managed landfill can be a cause of serious health problems, with the proliferation of parasites and high risk of fire, due to the high content of hydrocarbons present in these artifacts.

Landfill

• Fire - Typical environmental management problem

Landfill

• Proliferation of pests

Recommend Sites

• www.itra.com/corporate/recycling/trrac.htm

• www.wrf.org.uk

• www.rapra.net

• www.usrubber.com

Recommended Sites

• ECOsurfaces - http://www.floortec.net/ECOsurfaces.htm

• Enviro-mat - http://www.geocities.com/enviromat2002/ • Recycled Rubber Bags - http://www.englishretreads.com • Recycled Rubber Flooring - http://www.diamond-

safety.com/Rubber%20Flooring.html • Tire Swings - http://www.ponyswings.com

• Used Rubber USA - http://www.usedrubberusa.com

Contact

LT Quimicos

Av. Pedro Severino Jr., 366 Cjto 35

04310-060 – São Paulo – SP – Brasil

Luis Tormento

NPD Director

[email protected]

Tel: +55 (11) 5581-0708

rubber recovery and reuse

Engineering