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As a major consumer of automobiles, the mainland has maintained a rapid growth in tire production, while the number of waste tires is also increasing at a rate of 8%~10% per year, with more than 300 million tires scrapped every year, and more than 1.5 billion tires scrapped in the world every year.
As a result, the disposal of waste tires has become a big problem, and disasters caused by improper disposal of waste tires are not uncommon all over the world. The mainland has hardly heard of an accident, so do we have any secret to dealing with waste tires?
The hazards of scrap tires
Waste tires are a typical source of black pollution, and as industrial hazardous solid waste, traditional garbage disposal methods such as combustion, landfill and other methods are not applicable.
Because waste tires are hard-to-decompose polymer materials, waste tires are easy to age under light, heat and other conditions, releasing irritating harmful gases and particles, which may lead to human allergies, respiratory infections and even cancer.
If it is landfilled, it will be difficult to degrade for hundreds of years, but it will affect the ecological environment. Combustion, the production of a large amount of smoke and exhaust gas causes serious pollution to the environment, endangering human health.
A large number of waste tires are piled up in the open air for a long time, and under the action of sunlight and rain for many years, the heavy metals on their surface will seep into the ground, resulting in soil and water pollution.
It is easy to breed mosquitoes and spread diseases, and at the same time, it is easy to cause fires because it is difficult to dissipate heat. In recent years, there have been frequent reports of fires in waste tire dumps, such as Sulaibia, Kuwait in 2021, Ludhiana, India in 2021, Madrid, Spain in 2016, etc., which release a large number of toxic and harmful substances, which pose a great threat to human health and the natural environment.
In 2000, in Stanislaus County, Northern California, the yard where 7 million scrap tires were piled up spontaneously ignited and caught fire, melting 302,83200 liters of pollutant into a nearby pond, and black rain fell when the wind was blowing in the nearby city, and the black smoke even fell to San Francisco, 100 kilometers away.
By 2024, global tire production is expected to exceed 22 million tons, or about 2.4 billion tires. According to the National Bureau of Statistics of the mainland, the output of rubber tire tires in the mainland reached 888 million in 2021, a year-on-year increase of 10.8%.
Globally, around 1.5 billion tires are scrapped every year, or about 17 million tons. Continental produces about 350 million scrap tires per year, and this number will continue to grow at a rate of 8% to 10% per year. For such a large amount of waste tires can not be simply piled up and stored, they must be recycled, reprocessed, and recycled.
How are waste tires disposed of abroad?
At present, the treatment of waste tires mainly includes the production of reclaimed rubber, retreading of old tires, direct incineration and pyrolysis. Among them, retreading has high requirements for the quality of old tires, which is only suitable for natural rubber-based tires such as trucks and buses, and the number of retreading is limited, and the safety of retreaded tires is also reduced.
The production of reclaimed rubber is only suitable for waste tires with high original quality, and the production process of this technology has high energy consumption, serious environmental pollution and poor economy. Waste tires have high calorific value, and they are directly crushed and mixed with other industrial wastes for incineration for power generation, which is the main utilization method in developed countries such as Europe, America and Japan, but there are problems such as low utilization rate and environmental pollution.
The popular research direction of the industry is pyrolysis, that is, under the condition of air isolation, the waste tire rubber block is heated at high temperature to decompose fuel gas, oil, carbon black and steel wire, etc., and 550 kg of fuel oil and 350 kg of carbon black are separated from 1 t waste tire, and the whole process is clean and environmentally friendly, and will not produce secondary pollutants.
However, there are problems of large investment, high production cost and immature technology, so it still takes time for large-scale and industrialization to be actively explored and improved.
In Europe, the recycling rate of waste tires has been above 90% and has remained stable, with a total of 3.574 million tons of waste tires generated in Europe in 2018, of which 3.265 million tons were recycled, with a recycling rate of 91%.
Among them, about 40% of waste tires are burned for energy use, about 38% are used for raw materials, about 9% are used for tire retreading, and about 9% are used for export; Among them, the waste tires used as raw materials are mainly used to produce rubber particles and powders, and a small amount of recycled rubber.
In 2021, the U.S. produced approximately 270 million scrap tires, or about 5.031 million tons, of which about 71% were recycled and the rest were disposed of or untreated. Among them, 52.8% of the thermal energy is used as fuel in steelmaking, cement production, papermaking, power generation and other fields, 16.8% is used as raw materials for sports facilities, 11.9% is used in municipal projects such as roads, and 18.5% is used in other applications.
In Japan, nearly 90% of waste tires are recycled, of which 48% are used as fuel, 21% are used for retreading, 19% are used for recycled rubber and rubber powder, and 12% are disposed of in landfills.
In addition, foreign developed countries will give preferential policies and subsidies to enterprises for the comprehensive utilization of waste tires, encourage enterprises to actively recycle waste tires, and vigorously develop the waste tire market.
Waste tire disposal method in mainland China
According to the industry report released by the Ministry of Commerce of the People's Republic of China, the recycling of waste tires in 2019 was only 200 million, about 6.55 million tons, and the recycling rate was only 51%. At present, there are mainly the following types of waste tire recycling in mainland China.
The simplest is direct utilization, which does not require too much technology, and the waste tires are processed into valuable items by cutting, bundling, punching, etc., such as wave dams, road signs, marine aquaculture fishing reefs, winter trees to keep warm, etc. It can even be exported to Africa.
Many African countries live in difficult conditions and cannot afford to develop manufacturing at all, and the waste tires imported from China can be cut directly to make local popular slippers, which are of high quality and low price, and even foreigners are amazed that we are too smart and business-minded, but their use is small, less than 1% of the total amount of waste tires.
It can also be used for tire retreading, waste tires can be retreaded many times, each retreading can improve the life of tires by 60%~90%, reduce the use of raw materials, greatly reduce production costs, and reduce the import of rubber resources.
However, mainland retreaded tires are mainly based on truck tires, and the development potential is limited, mainly because most users do not have enough awareness of tire maintenance, trucks are seriously overloaded and replaced infrequently, and many recycled tires are worn excessively and cannot be retread; Secondly, the majority of tire users and even the government are worried about the quality of tire retreading and restrict its use.
There is also the crushing processing of waste tires, in the processing process, the metal and fiber separation method in the rubber particles should be removed, which has the characteristics of high energy consumption, large wear, low work efficiency and high production cost.
There are also waste tires used as fuel, and the utilization rate in the rotary kiln of the cement plant reaches more than 21%. In terms of ironmaking, carbon black is the reducing agent, the iron can be recycled, and the ash is reused, so the utilization rate is as high as 45%.
Different from European and American countries, the utilization of waste tires in mainland China is mainly based on the production of reclaimed rubber and rubber powder, of which the processing of reclaimed rubber accounts for 71.3% of the total utilization of waste rubber. Reclaimed rubber can replace part of the production of rubber products, can reduce the import of rubber resources, the price is much lower than natural rubber, the mainland is a large rubber consumer, so reclaimed rubber is the main direction of development.
In 2023, the total output of reclaimed rubber products in China reached 8.5 million tons, an increase of 20.1% year-on-year. The output of reclaimed rubber in mainland China ranks first in the world, and 100,000-ton reclaimed rubber production bases have been built in Hebei, Jiangsu and other places, reaching the world's leading level in terms of scale, process and quality.
Rubber powder is also an important part of the utilization of waste tire resources, rubber powder is widely used, involving various industries, and plays an important role in auto parts, anti-static floor tiles, soil conditioners, etc.
Epilogue:
Although the utilization rate of tires in the mainland is still lower than the world average, but under the vigorous promotion of the government, waste tire resources have received more and more attention, and the mainland has formed a diversified recycling method, covering all aspects from old tire retreading to waste tire pyrolysis, and the market prospect is broad.
It is believed that with the further development of the market and the further improvement of recycling technology, waste tires will be turned into treasure and become a new cash cow.
Bibliography:
The United States actively promotes the recycling of waste tires
Continental tire recycling industry forges ahead_Pang Shuhua
Introduction of foreign tire recycling and pyrolysis related technologies_Robert Weibold
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