Each tire contains about 4 pounds of carbon black, a petrochemical composed of petroleum or natural gas residue. Most countries have curtailed rubber burning to reduce air pollution. Rubber plants can recycle and reprocess used rubber for use when a premium-grade is unnecessary. Shredded rubber can be reused, or reformed and molded in a process called re-vulcanization. Different recycling machines and processes are available.
Crumb Rubber Granulator uses a dry ambient system to create a rubber crumb that remains unmodified chemically. According to the company’s website, crumb rubber results from granulating or grinding scrap tires or other forms of rubber into uniform pieces with cleaned wire, fiber fluff, fine bits of metal, rock and glass dust.
The company claims the Crumb Rubber Granulator produces more than 67 pounds per minute. In a sample run of nearly 11.5 hours, the unit used 2,550 KWH of electricity and produced a mixture which varied from 80 mesh to 0.375 inch. It operates at less than 250 degrees Fahrenheit or 120 Celsius. The machine was granted a U.S. patent in January 2007.
A recycling plant includes several pieces of specialized equipment for cutting, crushing, separating and sorting.
The Guangzhou 3E Machinery Co. Wire Bead Pulling Machine, according to the company, operates under ambient temperatures. It removes the two pieces of thick steel wires located around the tire bead to protect shredder and crusher blades.
Guangzhou’s GL Two-Shaft Shredder tears whole tires into scraps appropriately sized for the LGF Wire Separator. The separator crushes the rubber block produced by the shredder into granules that are between 8 millimeters and 15 millimeters while separating the wire. A magnetic separation machine separates the steel wire from the mixture. Located under the separators, the vibrator is connected to the machines and separates some fiber parts. The Rubber Crusher reduces the granules produced by the wire separator to between 2 millimeters and 4 millimeters.
The Zig-Zag Classifier separates the rubber by density. As the mixture of fiber and rubber feeds into the classifier, it enters a chamber where wind pressure sorts it. Since the fiber is lighter, the wind forces it into a collector while the rubber passes on.
Producing 40 to 80 mesh rubber powder, the economic miller uses low amounts of power and is clean even during production.
Although this system is lightweight, Tire Recycling Consultants claims it can recycle most passenger car and light truck tires, including steel-belted and bias-ply treads.
Weighing only 200 pounds, the portable BR1000 Bead Remover can cut six tire sidewalls per minute or about 180 tires each hour. It uses 110 volts of power and requires 100 PSI of air pressure.
The TC1000 Tread Cutter weighs 250 pounds and, according to the Tire Recycling Consultants website, uses hardened cutting discs. The machine cuts the tread into three pieces and about 150 treads can be processed in an hour.
An average of 150 tires an hour can be processed through the SW1000 Tire Sidewall Remover. The machine weighs 250 pounds and requires 110 volt, single phase AC power.
According to the Tire Recycling Consultants website, each machine’s “low-cost blades can be replaced quickly.”
The computerized CryoVortex uses nitrogen in its single-pass method which, according to the website, enables you to skip the shredding and chipping stages while reducing odor, damage and scorching. Whole tires are processed into fiber- and steel-free crumb with two sizes of mesh in the single pass. Additionally, the website states, the crumb rubber may be processed to your specific material size and surface.
According to Scrap Tire Recycling, CryoVortex’s manufacturer, freezing rubber leaves it undamaged and it returns to normal once thawed.
CryoVortex can operate for six continuous days or 24 days monthly, according to the company’s website, producing an average of up to 200 tires an hour.
Shari Caudill began writing professionally in 1985 with the "Portsmouth Daily Times." Her work has also been published in the "Community Common" and "Cleveland Plain Dealer." Caudill has a writing certificate from the Institute of Children's Literature and a photography certificate from the New York Institute of Photography.