How To Recycle Automotive Shredder Residues?
ASR (Automotive Shredder Residues) is a complex mixture produced during the scrapping of vehicles. The composition of ASR varies, including plastics, rubber, glass, trace metals, as well as wood, fiber and canvas, and the proportion of ingredients varies depending on the model.
The ASR generation process is as follows:
(1) Disassembly of reusable and remanufactured parts (e.g. wheels, bumpers, windshields, seats, door panels, gearboxes and engines).
(2) Disassemble the battery and airbags, and collect lubricating oil, gasoline, antifreeze and brake fluid.
(3) Vehicle body crushing.
(4) Use a magnetic separator to separate the ferrous metal iron.
(5) Use eddy current separator to separate non-ferrous metals.
The remaining part is ASR.
There are currently multiple methods for ASR processing:
1. Landfill:
Traditionally, ASR is often sent to landfills for disposal. However, the potentially harmful chemicals added to plastics, such as stabilizers, colorants, and plasticizers, have aroused public concerns about soil and groundwater contamination, which has led to a gradual decline in the acceptance of landfill.
2. Mechanical recycling:
Through magnetic separation, eddy current separation and air separation, mechanical recycling can effectively separate ASR into iron-rich components, non-ferrous metal components and polymer components. Among them, the polymer component contains different proportions of wood and rubber. If these resources are properly utilized, they will have significant circular economic value.
3. Combustion treatment:
ASR has attracted much attention due to its high calorific value, and combustion can effectively reduce its volume and weight. However, the toxic gases released during the combustion process, such as dioxins and hydrogen chloride, and the residual heavy metals, pose a serious threat to the environment. In addition, the high cost of building and maintaining high-temperature incinerators limits the widespread application of this method.
4. Pyrolysis:
In an oxygen-deficient environment, the organic matter in ASR can be decomposed into oil, mixed gas and coke at high temperature. Although this technology has great potential, the poor thermal conductivity of plastics leads to a long decomposition time and easy coke adhesion, which affects the progress of its industrial application.
5. Gasification:
As an advanced thermochemical process, gasification can convert ASR into gaseous fuel (such as a mixture of carbon monoxide, hydrogen, and carbon dioxide) and light hydrocarbons. By precisely controlling the reaction conditions and equipment parameters, gasification not only improves the resource utilization rate of ASR, but also reduces the risk of environmental pollution. Common types of gasification include moving bed, fluidized bed, and entrained bed.
