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Views: 28 Author: Site Editor Publish Time: 2025-08-08 Origin: Site
With the booming automotive industry and the continued rise in vehicle ownership, brake pads, a key component of automotive braking systems, face increasing replacement frequency. Semi-metallic brake pads, due to their excellent heat resistance, high thermal conductivity, and excellent braking performance, are widely used in disc brake systems for cars and heavy-duty vehicles. However, the large amount of discarded semi-metallic brake pads poses severe environmental challenges and resource waste. The efficient recycling of semi-metallic brake pads has become a critical issue that needs to be addressed.
Semi-metallic brake pads are brake components made from a composite of multiple materials.
In terms of metal content, semi-metallic brake pads typically contain 20%-60% metal. Steel fiber is the primary reinforcement, representing a significant proportion. It significantly enhances the pad's structural strength and wear resistance, ensuring it resists deformation and wear during long-term braking. Copper powder or copper fiber is also a key component, generally comprising 5%-20%. Copper has excellent thermal conductivity and anti-friction properties, helping the pad dissipate heat quickly during braking and reducing braking noise and vibration. Additionally, it may contain small amounts of metal powder or fiber, such as iron, aluminum, and zinc. These metal components work together to impart excellent braking performance to the pad.
Organic components also contribute to the composition of semi-metallic brake pads, primarily including binders and friction modifiers. Binders, typically thermosetting resins such as phenolic resin, account for approximately 10%-20% and securely bond the various materials together to form a cohesive structure. Friction modifiers include rubber powder, graphite, and coke. They adjust the brake pad's coefficient of friction, improving braking stability and wear resistance, and typically comprise 10%-30%.
In addition to metal and organic components, semi-metallic brake pads may also contain small amounts of inorganic fillers, such as barium sulfate and calcium carbonate. These fillers are primarily used to adjust the pad's physical properties, such as density and hardness, and typically account for around 5%-15%.
Brake pad waste primarily consists of metallic materials, organic materials, and adsorbent materials. The handling and disposal of these materials can cause environmental pollution and health threats. For example, the combustion of organic materials releases large amounts of harmful gases and fumes, while the disposal of metallic materials can pollute soil and water sources. Therefore, the discharge of brake pad waste must be strictly controlled.
The materials used are complex and diverse, making them difficult to separate.
Recycling costs are high, making large-scale recycling difficult.
The recycling process may generate dust, wastewater, or exhaust gas.
There is a lack of standardized sorting and storage procedures.
Semi-metallic brake pad recycling generally involves five core steps: collection and classification, pretreatment, material separation, purification and processing, and resource utilization. Discarded brake pads are first collected by repair shops and other terminals and stored by model and specification. After preliminary cleaning to remove oil and impurities, they are broken down into granular materials using crushing equipment. Mechanical screening, chemical leaching, or low-temperature pyrolysis techniques are then used to separate metals (steel fibers, copper powder, etc.) from organic components. The separated metal materials are purified to remove impurities and improve purity, while organic residues are treated harmlessly. Finally, the recovered metal can be used to remanufacture brake pads or building material reinforcements, while the organic components are converted into fuel or fillers, completing a resource recycling cycle.
Combined Mechanical-Chemical Separation Technology
This process utilizes a combined "crushing-screening-selective dissolution" process: A jaw crusher is first used to crush the brake pads into 5-10mm particles, which are then separated by a vibrating screen to remove coarse particles such as steel fibers. The fine powder is then selectively leached with a low-concentration acid solution to dissolve metals such as copper and aluminum. After precipitation and filtration, a high-purity metal powder is obtained. This technology improves recovery rates by over 20% compared to traditional mechanical methods, achieving metal purity of up to 95%.
Low-Temperature Pyrolysis-Bioleaving Technology
The brake pads are subjected to low-temperature pyrolysis at 300-400°C in an inert atmosphere, breaking down the organic binder into recyclable small organic molecules and preventing the release of harmful substances. The metal components in the pyrolysis residue are then bioleached, utilizing the metabolic activity of microorganisms such as Thiobacillus ferrooxidans to dissolve the metals. The reaction conditions are mild and there is no secondary pollution, resulting in a metal recovery rate exceeding 90%.
Establish a standardized recycling network.
Automakers should incorporate recycling design into product lifecycle management, labeling brake pads with material composition and recycling labels during production to facilitate subsequent sorting and processing. Auto repair shops should establish dedicated collection points to perform preliminary cleaning and sorting of discarded brake pads, and sign targeted recycling agreements with reputable recyclers. The government can incentivize the development of recycling networks through subsidies, promoting the "repair shop collection + recycling company centralized processing" model.
Improve recycling standards and regulatory mechanisms.
Establish industry standards for the recycling and processing of semi-metallic brake pads, clarifying indicators such as material separation purity and pollutant emissions, and standardizing the recycling process. Environmental protection departments should strengthen the qualification review and process supervision of recycling companies, crack down on illegal dumping and incineration, and ensure the environmental and safety of the recycling process.
High-Value Utilization of Metal Materials
Recycled steel fibers, after surface treatment, can be reused in brake pad production or incorporated into concrete as a reinforcement to enhance building structural strength. Purified copper powder can be used in the manufacture of wires, cables, and electronic components, resulting in a 15%-20% increase in economic benefits per ton of recycled copper compared to virgin copper.
Resource Conversion of Organic Components
The organic gases produced by pyrolysis can be purified and used as fuel. The solid residues are modified to produce rubber fillers for use in tires, seals, and other products, effectively turning waste into valuable resources.
Individuals handling discarded semi-metallic brake pads must adhere to the principles of "safe storage, standardized disposal, and refusal of illegal disposal." After a brief cleaning, they should be stored separately in a dry, ventilated container, labeled, and kept away from water, fire, and children. Disposal should be completed within 1-2 weeks. Avoid illegal disposal when disposing of them. Contact a participating auto repair shop, find authorized recycling locations through the local environmental protection department's website, or participate in community recycling programs. Individuals are strictly prohibited from crushing, incinerating, or treating with acid or alkaline solutions. They should also proactively understand relevant policies and promptly report any illegal disposal. When replacing brake pads, prioritize easily recyclable products and pay attention to the repair shop's recycling procedures to promote a green and virtuous cycle.
Of course, it is also important to choose a brake pad made of safe materials. If you want to buy a suitable and durable brake pad, you are welcome to visit our website:https://www.evfriction.com. or contact us by +86-13363216781 .
