More than 1 billion tires are discarded around the world every year. Disposal of waste tires is a challenging task because tires have a long life and are non-biodegradable. The traditional method of tire waste management is stockpiling or illegally dumping or landfilling, all of which are short-term solution.
Crumb rubber is a term used for recycled rubber from automotive and truck scrap tires. The two major technologies for producing crumb rubber are ambient mechanical grinding and cryogenic grinding. Of the two processes, cryogenic process is more expensive but it produces smoother and smaller crumbs.
Ambient Mechanical Grinding
In ambient mechanical grinding process, the breaking up of a scrap tire happens at or above normal room temperature. Ambient grinding is a multi-step technology and uses whole or pre-treated car or truck tires in the form of shred or chips, or sidewalls or treads. The rubbers, metals and textiles are sequentially separated out. Tires are passed through a shredder, which breaks the tires into chips.
The chips are fed into a granulator that breaks them into small pieces while removing steel and fiber in the process. Any remaining steel is removed magnetically and fiber through a combination of shaking screens and wind sifters. Finer rubber particles can be obtained through further grinding in secondary granulators and high-speed rotary mills.
Ambient grinding is the production process used by the majority of crumb producers. The machines most commonly used for fine grinding in ambient plants are:
- Secondary granulators
- High speed rotary mills
- Extruders or screw presses
- Cracker mills
Cryogenic grinding refers to the grinding of scrap tires at temperatures near minus 80oC using liquid nitrogen or commercial refrigerants. Cryogenic processing generally uses pre-treated car or truck tires as feedstock, most often in the form of chips or ambiently produced granulate.
Processing of scrap tires takes place at very low temperature using liquid nitrogen or commercial refrigerants to embrittle the rubber. It can be a four-phase system which includes initial size reduction, cooling, separation, and milling. The material enters a freezing chamber where liquid nitrogen is used to cool it from –80 to –120 °C, below the point where rubber ceases to behave as a flexible material and can be easily crushed and broken.
Because of its brittle state, fibres and metal are easily separated out in a hammer mill. The granulate then passes through a series of magnetic screens and sifting stations to remove the last vestiges of impurities. This process requires less energy than others and produces rubber crumb of much finer quality.
Uses of Crumb Rubber
Both ambient and cryogenic processing can be repeated to produce finer particles. Increasingly, the two with their attendant technologies, are combined into one continuous system in order to benefit from the advantages and characteristics of each and to reduce overall costs.
The ambient system is generally used for the initial size reduction phases. The cryogenic system is used to further reduce the material in size and then to remove the metals and textiles. The outputs from either or both systems can be used directly or as feedstock for further processing.
Rubber crumb is sold as feedstock for chemical devulcanization or pyrolysis processes, added to asphalt for highway paving and pavement sealers, or used for the production of a large number of recycled rubber-containing products.
Some of the major applications of crumb rubber are as follows:
1. Sport Surfaces
- Kindergarten Playgrounds and Recreation Areas
- School Sports Areas
- Athletic Tracks
- Tennis and Basketball Courts
2. Automotive Industry
- Splash Guards and Fenders
- Floor Mats for Cars and Trucks
- Floor Liners for Trucks and Vans
- Hospital, Industrial, and Bathroom Flooring
- Floor Tile
- Foundation Waterproofing
- Dam, Silo, and Roof Liners
4. Geotechnical/Asphalt Applications
- Rubberized Asphalt for Roads and Driveways
- Drainage Pipes
- Soil Conditioner
- Porous Irrigation Pipes
- Road Building and Repair
5. Adhesives and Sealants
- Adhesives and Sealing Compounds
- Textured and Non-Slip Paints
- Roof Coating and Waterproofing
6. Shock Absorption and Safety Products
- Shock Absorbing Pads for Rails and Machinery
- Sound Barriers for Highways
- Abrasion Lining in Mining Equipment
7. Rubber and Plastic Products
- Pipe Insulation and Lining
- Garbage Cans
- Shoe Soles and Heels
- Wire and Cable Insulation
This is interesting. Recycling tires can be an out-come of other products. We have parkes here in UAE that is used recycled tires for walking paths. Its brillilant yet healthy and very safe for the kids and prevent small plants growing other than the normal paths 🙂
Good one studied and written Salman
Recycling is an important element of waste treatment.
Waste Disposal in M.E is not primarily considered in aappropriate manner, thus
the disposal of waste contributes to environment hazards.
Recycling is one of proper waste dosposal method and it needs encouragement with
Waste rubber recycling is very appropriate in the mordan world because it takes care of the environment also complements raw materiels and not only that but creates employment.
can anyone pls mail its project report on email@example.com. I`ll be very thankful.
this is a very informative blog.Can anyone please send a project report on crumb rubber to firstname.lastname@example.org . I’ll really be very thankful.
I would be most greatfull for any information on tyre recycling please reply to email@example.com
I would be very great-full for any information of a project on tyre recycling in Middle East, specially in Saudi Arabia please send me by firstname.lastname@example.org
Very interesting. Rather than burning used tyres to melt asphalt/range in the barrel and polute the environment, it creates a business opportunity and reduce unemployment specially in the developing countries.
I would be grateful if someone send me the process & project report of rubber mat for car, truck and floor mat. We are already in recycling of rubber industries.
Can anybody have project report , ppt or procees reports.
pls suggest me on email@example.com
Please give me project full details
I will be very pleased if anyone can send me a project of ideas on potential uses/products of rubber crumb.
Salman Zatar, Interesting comments. Unfortunately you lead people to believe that hammer mills and granulators can create crumb rubber. They can only create a feedstock for further size reduction using the ambient process. Also SEM pictures show the great disadvantages of cryogenically produced crumb.Much less surface area for compounding chemicals to bond with.
Thanks for your enlightening comments. You have definitely more knowledge about the subject.
this is a very informative blog.Can anyone please send a project report on crumb rubber to “firstname.lastname@example.org” . I’ll really be very thankful.
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We are looking for buyers of rubber crumbs from bahrain
Very attractive price
Dear Salman Zafar,
Congratulations on your article on Production and Applications of Crumb Rubber.
We have a London-based company that provides architectural and engineering consultancy on sports facilities, including small and large stadiums with an Athletics running track and artificial turf Football pitches.
We have received many invitations to do projects in some countries in Africa and the Middle East.
Some of our projects received rubber granules (SBR) from European and Chinese suppliers, but we would be very happy if it were possible to create supply opportunities for manufacturers located in Africa (except Morocco, which already has a warehouse for a Spanish manufacturer) and in Middle East.
Could you please give us the contact name and address of manufacturers of rubber granules (mechanical or cryogenic) for infill artificial turf in these two regions, or even in India?
Please write to our office in Lisbon, which serves these markets.
Best regards and our wishes for greater professional successes.
DEAR MR. SALMAN, I AM INTERESTED IN SETTING-UP PLANT USING WASTE TYRES AND PRODUCE RUBBER. IF POSSIBLE PLEASE GET IN TOUCH WITH ME VIA EMAIL SHABBIR.BHATIA@GMAIL.COM
Dear Mr Salman
Thankyou for a very interesting article. I work for a company in Australia (WA) and we crumb used conveyor belt rubber.
We are looking to find a market overseas that would buy the crumbed rubber and I would appreciate any information or points of contact you might be able to provide to help find us a buyer.
Thank you Salman Zatar for your information on crumb rubber. We appreciate your efforts to help people be more aware about this incredible product and its uses.
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