On September 14, the scientific observer of CentralAsia.news, well-known Turkmen scientist, Doctor of Technical Sciences and expert Allaberdy Ilyasov commented on the economic benefits of waste tyre recycling in his new article.
Economic preferences are better than harm to nature
Road transport is one of the main segments of the global economy, since it is the crucial link in the chain of industrial production and the comfortable life of people. However, it is the major source of global environmental pollution.
When operated, vehicles generate large amounts of waste, among which worn tyres are a huge danger, which are difficult to collect and dispose.
The problem of ensuring environmental safety when using and disposing tyres is directly related to environmental issues. Today, it is therefore necessary to talk not only about protection of nature of Earth, but also about economic preferences for reusing old tyres.
Environmental pollution is an acute and urgent problem in the modern world. Hard-to-recycle industrial waste poses a significant threat. Currently, car tyres are one of the most common types of polymer waste.
More than 10 million tonnes of tyres are worn out every year globally. In different countries, this amount varies within different ranges. However, waste tyres will increase in numbers with the growth of freight and road transport. Sales of passenger and light commercial vehicles totalled 1.4 million units in 2016, 1.5 million units in 2017 and will increase to 2 million units by 2020.
According to experts, global sales of automobiles will continue to grow. The annual growth rate is estimated at 3-7 percent. As a result, the number of waste tyres will increase.
In many developed countries, most of old tyres are recycled. For example, 88.5 percent of water tyres are recycled in the United States. In Russia, only 17 percent is recycled at specialized enterprises.
Various technologies are used to recycle waste rubber and car tyres in the world. These processes involve the disposal of whole or shredded tyres and the use of them for various purposes – to produce energy or rubber crumb and powder. Waste tyres have a high thermal potential and can be used as fuel, since they consist mainly of petroleum products.
The second birth of a tyre
Entrepreneurial people have always been able to utilise scientific ideas. Therefore, the use of old tyres for various purposes has not escaped the attention. For example, they are used as a casing for drainage systems and decorative fences. Tyres crushed into crumb rubber can be used to build playgrounds and road surfaces.
In recent years, this method has been widely used. This is because the production is less energy intensive than pyrolysis and less dangerous than burning. Moreover, the use of crumb rubber not only as an additive in rubber compounds, but also as a major material for building and technical products makes it possible to utilise the valuable properties of polymeric materials.
The most effective waste rubber processing method is tyre pyrolysis. Pyrolysis is one of the promising processing methods, designed to extract hydrocarbons of various compositions and other reusable components. This processing method is the most promising, since pyrolysis products are compounds with a rich-in-energy potential. The pyrolysis products are gas, liquid fuel and coal.
Hundreds of thousands of tonnes of savings
The most important aspect of the recycling of rubber products, in the first place, such massive and rubber-intensive products as tyres, is the production of regenerative rubber by thermo-mechanical treatment of rubber waste. A regenerative product is a plastic material that can be processed and vulcanized by the introduction of vulcanizing agents.
Such products as rugs, household paths, semi-solid insulating tubes and garden sleeves, among others are mainly made from one regenerative product. A regenerative product is also added to rubber to produce tyres, gaskets, battery tanks and shoes. It saves hundreds of thousands of tonnes of oil. Regeneration is a multi-stage and time-consuming process. First, rubber products to be recycled are sorted by categories, types and rubber content, then metals and other materials are removed and rubber is crushed into particles of a certain size.
After grinding, crumb rubber, freed from the bulk of textile materials and inclusions, is devulcanized – the process in which waste vulcanized rubber is converted by using mechanical, thermal and chemical energy so that it can be mixed, processed and vulcanized again.
However, the situation with rubber recycling is not very successful, and in fact global tyre manufacturing exceeds aluminium production. In addition, tyres make 90 percent of polymer waste. These polymer products are accumulated on our planet up to hundreds of millions. Today, a wide range of technologies are used globally to recycle rubber waste and waste tyres. However, humanity has found a way to extend the life of old tyres.
In the USA, Australia, Japan, New Zealand and a number of other countries, hundreds of artificial spawning grounds have been made from old tyres to increase the biological productivity of the sea. An essential advantage of such spawning grounds is that sea water is not polluted and they are very durable.
According to some reports, tyres keep their longevity in sea water for 150-200 years. Breakwaters and cutwaters are also made from worn tyres. However, they have a number of significant drawbacks: they are not effective to protect against strong waves, and they are difficult to care for.
Worn tyres are used to build roads on soft peat soil.
Old tyres can be used to build bridges across small rivers, streams and ravines, culverts under highway and railway embankments and filter embankments. These structures are durable, their construction costs are much lower than those of reinforced concrete structures. The demand for whole worn tyres used in various engineering structures in some countries can range from several thousand to several tens of thousands of tonnes per year, depending on the size and economic development level of the country.
The storage and disposal of waste tyres in landfills have an adverse environmental impact. By 2030, around 1.2 billion tyres will be recycled worldwide annually. Therefore, rubber recycling is a very bold engineering solution, for example, for the production of such a building material as concrete, and will boost its quality. These facts are confirmed by the research conducted by specialists from the Royal Melbourne Institute in Australia.
Scientists from the Royal Melbourne Institute of Technology University have been studying the benefits of old tyres for concrete production for many years. According to Australian researchers, worn car tyres will no longer have to end up in landfills in the near future, as they will increasingly become a major component in concrete production.
Many years of experiments have proven that the long-term restriction on the use of large amounts of thick rubber particles in concrete can now be lifted. Indeed, until now, rubber was a small part of the mixture, which also contained gravel, granite or limestone. Researchers have now succeeded in replacing 100 percent of conventional coarse aggregates in concrete with recycled tyres. They made crushed rubber granules with the help of a special device. Water, Portland cement and river sand helped the mixture solidify. It should be noted that such concrete fully meets construction requirements.
In recent years, the rapid development of the polymer industry has contributed to the continuous increase in polymer waste generation. In this regard, worn tyres are the most massive type of such waste. For example, approximately 1 million tonnes of used car tyres are produced every year in the CIS countries.
The economic benefit of the recycling and use of waste tyres is that they contain large amounts of valuable polymeric and reinforcing materials, which to a large extent retained their original properties. The environmental aspect of the problem is that worn tyres accumulated in the places of their use or taken to landfills pollute the environment due to their high resistance to external factors (sunlight, oxygen, ozone, moisture).
This results in land degradation and soil and water pollution. A huge risk comes from the chemical composition of old tyres. The various raw materials used to produce tyres have adverse effects on the environment and human health.
Worn tyres are classified as chemical waste and combustible solids. The major materials used in polymer rubber production, such as butadiene and styrene, and many polymer additives can cause systemic toxic effects. Toxins released from tyre decomposition, burning or accidental fires greatly pollute water, air and soil, producing catastrophic environmental impacts.
Benefits for the world
The environmental hazard of tyres is due, on the one hand, to the toxic properties of the materials they are made from and the impurities they contain. On the other hand, due to the properties of more than a hundred types of chemicals released into the air and water when tyres are used, maintained, repaired and stored. Environmental problems are becoming more acute.
It is therefore important that everyone develops the consciousness and understanding of a careful attitude towards himself, and hence to the world. The recycling and reuse of old tyres offer a huge environmental and economic benefit to the world.
The mechanical processing of waste tyres makes it possible to produce such valuable raw materials as crumb rubber, textile cord and metal, which are used in various areas of production. The recycling of old tyres will make an invaluable contribution to solving one of the environmental problems. It will give a chance for a second life, but of new things and products.