Economical Viability Of Pyrolysis Tires

Scrap tires are hard to dispose because of their durability property. They are not biodegradable, and pose a serious problem to the environment. It is estimated that America produces 280 million tires annually, thus dumping these tires in landfills is no longer a viable solution. Nevertheless, it is estimated that 2 billion tires are stockpiled in different places in USA, promoting illegal dumping. Disposal of tires in a landfill presents serious environmental and health problems. Tires take up a lot of space in the landfill, create suitable breeding grounds for rodents and mosquitoes, and can cause health and fire hazards. For example, a huge fire erupted in Canada when a pile of tires caught fire. This fire resulted in serious air pollution due to the gases, smoke and oils generated by the burning and decomposing rubber. The fire was hard to contain, and went on for days since rubber is highly flammable.
To combat the challenges presented by disposal of tires, several methods of recycling have been invented. One such method is pyrolysis, which involves heating shredded or whole tires in a reactor vessel that has a heat source,in an oxygen free environment. The rubber is softened inside the reactor, as the polymers break down due to the heat. This leads to the formation of smaller molecules that vaporize and leave the reactor. High temperatures ranging from 250° – 500°C are needed to break down the chemical bonds of the rubber, resulting in vaporization and decomposition of the organics. These vapors generated during the process can be utilized in two ways. Firstly, burning these vapors directly can generate energy. Secondly, these vapors can be condensed and cooled into a liquid and utilized as fuel. The molecules that cannot be condensed into a liquid are maintained as gas, which can also be used as fuel.
The minerals that make up almost 40 percent of the tires weight are left as solids during the process. These solid chars that are derived from the process are cooled and the fibers removed. Using magnetic separation, magnetic materials are separated from the char. The char is then washed and re-sized, to produce carbon black. Pyrolysis is a clean process that does not produce any waste or emissions, if it is well executed. Apart from that, the process does not make use of any chemicals, thus it is environmental friendly. It also creates products that are economically valuable from waste tires.
Due to the technical feasibility of pyrolysis, many projects have been constructed and licensed during this decade. However, although the process is environmental friendly, it is hardly economically viable. This is because; it requires high capital investments and the tipping fees charged is exorbitant. Tipping fees have kept on rising over time, and there is no hope that this trend will change any time. Also, the final products derived from the process fetch very low prices. Poor yields are attributed to the low market prices of pyrolysis fuel, and the poor quality of the carbon black or char that is derived during the process. The only way the process can be made more economically viable is if value added products such as benzene, high quality carbon black or Xylene are derived during the process, and the tipping fees is reduced.
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