Images of stockpiled tires scattered around the countryside or in vacant lots are familiar to most people. Based on the Rubber Manufacturer’s Association (RMA) Report of November 2006, there are 300 million scrap tires generated annually in the United States (one per person per year). With an average scrap tire weight of 22.5 pounds, this represents well over 6 billion pounds of predominantly hydrocarbon based materials generated annually that are largely underutilized.
Constructive use of scrap tires has accelerated over the last ten years and significantly alleviated historic tire dump issues (which create fire and disease hazards). The RMA reports 52% of scrap tires are burned for fuel, 12% are used in “crumb” rubber products (such as door mats), 16% is used for civil engineering applications, but at least 14% is ground and sent to landfills. The fuel and crumb rubber applications are constructive uses of scrap tires, but have technical limitations and marginally attractive economics.
Now, an economically attractive technology has been developed that successfully recovers materials from used rubber products while making significant positive environmental reductions in solid waste and air emissions. This process accepts any rubber product and recovers three distinct product streams with no unusable by-products.
The Carbolytic Materials Company Process
Carbolytic Materials Company (CMC) uses a process that melts scrap rubber and subsequently catalytically “cracks” the polymeric materials back to oil and gas. The remaining solid materials consist principally of the original carbon black materials, which are recovered in a manner that retains their reactivity and usefulness in rubber products. Subsequent finishing steps assure the production of an effective black reinforcing and tinting material that is available commercially today (ApexCM™).
CMC processes chipped scrap tires in a controlled environment that generates no odors or emissions, collecting gas (vapor), oil and solid streams as finished products. This is all accomplished in enclosed vessels and operated responsibly under strict industrial protocols to satisfy all regulatory standards.
Two of the product streams are usable as fuels – the oil and gas. The gas has high thermal value and is used as a local boiler fuel or to generate electricity, depending on the site of operation. Also, for each tire processed, in excess of one gallon of oil is generated, with properties similar to a diesel fuel. This oil is sold as a bunker fuel oil, or refined to a transportation grade fuel.
The consequence of this process is to return all materials to their original state: oil, gas and reinforcing carbon, achieving the ultimate goal of the recycle of end-of-life rubber materials.
The Environmental Impact Is Impressive:
- Reduced landfill of scrap tires
- Reduced oil use to generate carbon black
- Reduction of CO2 emissions
CMC estimates the potential use of recycled reinforcing materials to exceed 600 million pounds in the USA. With that assumption, approximately 40% of annual scrap tire generation would be consumed, upgrading the current utilization of scrap tires to higher economic value and virtually eliminating the need for landfill. Further, it would encourage remediation of existing tire dumps and the “mining” of scrap tire mono-fill landfills.
Reduced Oil Use
There are two distinct ways that US dependence on foreign oil would be reduced.
1. The de-polymerization of the rubber polymers to oil generates over one gallon per tire that is recycled through the CMC process. Using the assumption that up to 40% of annual scrap tire generation could ultimately be processed in this manner, at least 120 million gallons of oil would be reintroduced annually to the marketplace through this recovery effort.
2. The current carbon black products used in rubber products are predominantly produced by the incomplete combustion of fuel oil to create carbon black (analogous to the production of “lamp soot”). Based on US Census Bureau data, It is estimated that 0.18 gallons of oil is used to produce one pound of carbon black. Based on this estimate, approximately 108 million gallons of oil would be saved by using ApexCM™ reinforcing black to avoid production of new carbon black.
Reduction of Carbon Dioxide (CO2) Emissions
The production of new carbon black using fuel oils is estimated to generate a total of 2.18 pounds of CO2 per pound of carbon black produced. In contrast, the recovery of carbon black using the CMC process is estimated to generate a total of 0.25 pounds of CO2 per pound ApexCM™ produced, a remarkable net reduction of 1.93 pounds CO2 per pound of carbon black. Again using the ultimate utilization estimates, a net annual reduction of over 500 thousand tons of CO2 generation would be achieved in the United States alone.
The recovery of raw materials from recycled rubber products using the CMC process would have a major impact on the US environment.
- Beneficial consumption of 40% of annual US scrap tire generation, resulting in the virtual elimination of scrap tire landfill.
- Reduction of oil use in the US of 228 million gallons per year
- Reduction of 500 thousand tons of CO2 generation annually in the US.
Restating these environmental gains on the basis of the production and use of 1000 pounds of ApexCM™:
- Approximately 190 scrap tires would be consumed
- The import and use of 380 gallons of oil would be avoided
- 1930 pounds of CO2 emissions would be avoided