Accelerating the Transformation of Scrap Rubber Comprehensive Utilization

By Qi Xuezhi, China Rubber Industry Association

Recycling scrap rubber shows remarkable environmental value

Major sources of scrap rubber include discarded rubber products – discarded auto tires, cart tires, rubber hoses, rubber belts, rubber shoes and industrial sundries – as well as leftovers and rejects of rubber processors. Around 65% of all of China’s rubber consumption is green rubber stock used in making tires. Seventy percent of all scrap rubber comes from discarded motor vehicle tires.
In 2016 in China, discarded tires alone amounted to 350 million pieces, with a total weight of 12.7 million tons. The output of reclaimed rubber was 4.6 million tons, an increase of 5.02% over the previous year. The output of rubber powder was 650 kt, an increase of 8.33%.
Major uses of scrap rubber in China today include tire retreading, reclaimed rubber, rubber powder and thermal cracking. Reclaimed rubber has already become the third major source of rubber (after natural rubber and synthetic rubbers), indispensable in the rubber industry. The direct use of rubber powder is regarded by the international community to be an environment-friendly and resource-based use of discarded tires. Making a full use of scrap rubber to produce reclaimed rubber is an important approach for preventing environmental pollution of scrap rubber refuse, while solving the shortage of domestic rubber sources in China.
There are more than 620 producers of reclaimed rubber in China. They are concentrated mainly in Hebei (97), Henan (64), Zhejiang (56) and Shandong (55). The number of vulcanized rubber powder enterprises with capacity exceeding 5.0 kt/a is over 300.

Comprehensive utilization of scrap rubber faces prominent problems

(1) Problems with scrap rubber treatment get bigger
The treatment and utilization of scrap rubber is basically focused on discarded tires of big motor vehicles. No large-scale effective treatment is yet made to discarded tires of smaller vehicles (e.g. scooters). The amount of discarded tires is increasing. By the end of 2016 the total number of motor vehicles in China had reached 290 million; 194 million were automobiles. With the standard of living rising constantly, the demand for new automobiles will remain brisk, and the amount of discarded tires will still increase year-on-year.
(2) Pressure for sweeping “green” transformation is intense
Due to rising pressure to protect our environment, enterprises face urgent problems in upgrading and renovating technology. On July 8, 2016 the Ministry of Industry and Information Technology and the Ministry of Finance jointly issued the “Action Plan for Reducing VOCs in Key Industries”. Regarding projects renovating process technology for comprehensive utilization of scrap rubber, the document urges the reclaimed rubber sector to promote the continuous desulfurization production process in a full-fledged way, thoroughly eliminate dynamic desulfurization tanks and use green additives to replace toxic and hazardous additives such as coal tar.
Quite a few enterprises making machines for rubber powder production have developed and manufactured biaxial crushers, but due to the cost and the service life of the internal cutting blades, such crushers have not become popular. For desulfurization, dynamic desulfurization tanks are still widely used in the sector.

Transformation of scrap rubber comprehensive utilization will be accelerated

(1) The national government has started to pay attention to the sound development of the sector
To promote sound and sustained development of the sector and solve the problem of black pollution caused by an increasing “supply” of scrap rubber and discarded tires, scrap rubber is included among the major fields in the “Guiding Views on Accelerating the Development of the Reclaimed Resources Industry”, issued by the Ministry of Industry and Information Technology, the Ministry of Commerce and the Ministry of Science and Technology at the end of last year, which mentions that green, smart and continuous complete equipment for reclaiming rubber should be developed, research on continuous whole-tire thermal cracking technology and equipment should be launched, technologies such as continuous closed reclaimed rubber production and negative pressure thermal cracking should be promoted, application dissemination of modified asphalt, high-strength reclaimed rubber and high-quality carbon black should be conducted and around 10 demonstrative enterprises for scrap rubber clean high-valued utilization should be created.
(2) Technical innovation has become more remarkable
Complete atmospheric continuous desulfurization equipment is gradually penetrating the sector. In addition to the two demonstration production lines constructed in Jiangyin High-Tech Development Area, where Jiangsu Zhonghong Environment Technology Co., Ltd. is located, the “10 kt/a reclaimed rubber production line using green smart equipment” developed by the company was exported to Qatar in 2016, and close cooperation has been established with production enterprises in Fujian and Anhui.
A “multi-step screw 5 000 t/a continuous green desulfurization production line” developed by Beijing University of Chemical Technology has been pilot tested in Nanjing Lujinren Rubber & Plastics Co., Ltd. and is already in operation in Chongqing Jiulong Rubber Product Manufacture Co., Ltd., Hengshui Huarui Engineering Rubber Co., Ltd. and BESG Xingyu (Tangshan) Rubber & Plastics Eco-Technology Co., Ltd. Recently, contracts have been signed with Zhongce Rubber Group Co., Ltd. and the Czech Republic.
Two production lines using the “green integrated single-screw desulfurization technology” developed by the Polymer Machinery Research and Development Center of Qingdao Institute of Chemical Technology passed acceptance by American clients in Jiading of Shanghai and were delivered at the end of 2016. A plant in Guangxi using the technology and equipment is basically constructed.
On the basis of atmospheric continuous desulfurization equipment introduced from abroad, Tiantai Kunrong Rubber Co., Ltd. has successfully used the pre-processing program on traditional equipment, steadily improving the quality of products.