Waste Battery Recycling
Waste battery recycling refers to the recovery and reuse of used batteries. Most industrial batteries in China are lead-acid batteries. Lead accounts for more than 50% of the total battery cost.
Recycling primarily uses pyrometallurgical processes, hydrometallurgical processes, and solid-phase electrolysis technology. The outer casing is made of plastic, which can be regenerated, and there is basically no secondary pollution.
Waste Battery Materials
Small secondary batteries use nickel-cadmium, nickel-metal hydride, and lithium-ion battery chemistries. Cadmium in nickel-cadmium batteries is one of the heavy metal elements controlled for environmental protection. Organic electrolytes in lithium-ion batteries, as well as the substrates and auxiliary materials used in battery manufacturing, can all cause environmental pollution.
The total number of small secondary batteries is only in the tens of millions, and most are small in size. Waste batteries have low value and are used dispersedly. Most are treated as household waste, creating cost and management issues. Regenerative use also presents certain technical challenges.
Waste Battery Hazards
(1) Zinc-Manganese Batteries
The main hazard comes from mercury and acid/alkaline electrolytes contained in the batteries. Heavy metal mercury can cause central nervous system diseases and was the cause of Japan’s “Minamata disease”.
(2) Button Batteries
Zinc-silver button batteries are widely used in electronic clocks, calculators, hearing aids, and similar devices. The hazard of such batteries is mainly caused by mercury, cadmium, and silver. According to relevant data, one button battery can contaminate 600,000 liters of water.
(3) Lithium Batteries
These contain lithium in the electrochemical system (including metallic lithium, lithium alloy, lithium-ion, and lithium polymer types). They include both primary and secondary batteries.
Due to advantages such as good cost performance, long storage life, and wide operating temperature range, they are used in watches, cameras, calculators, backup power supplies, cardiac pacemakers, security alarms, and more. Such batteries are relatively less hazardous, and recycling mainly recovers the valuable component: lithium metal.
(4) Alkaline Batteries
This series includes zinc-silver, cadmium-nickel, iron-nickel, nickel-metal hydride, and others. Cadmium-nickel batteries are the most widely used series and a major focus for environmental pollution control.
Cadmium is toxic and carcinogenic; nickel is also carcinogenic and significantly hazardous to aquatic organisms. According to US EPA surveys, cadmium from cadmium-nickel batteries accounts for 75% of total cadmium in urban solid waste.
(5) Lead-Acid Batteries
These are the most produced and widely used batteries globally, accounting for over 30% of global battery sales. China’s annual output of lead-acid batteries is nearly 30 million kWh.
The pollution from such batteries mainly comes from heavy metal lead and the electrolyte solution. Lead can cause neurasthenia, hand and foot tremors, digestive system disorders, blood poisoning, and kidney damage.
Environmental Impact Summary
When waste batteries are discarded in the environment, acidic and alkaline electrolytes can affect the pH of soil and water systems. Heavy metals such as mercury and cadmium are absorbed by living organisms and enter the human food chain through various pathways, accumulating in the body, causing deformities or diseases, and even death.
One button battery can contaminate 600,000 liters of water, equivalent to a person’s lifetime drinking water supply. One battery rotting in the ground can render one square meter of land unusable.
Waste Battery Pollution
Civilian dry batteries are the most widely used and most dispersed battery products, with 8 billion consumed annually in China. They mainly include zinc-manganese and alkaline zinc-manganese series, with small amounts of zinc-silver, lithium batteries, and other varieties.
Zinc-manganese batteries, basic zinc-manganese batteries, and zinc-silver batteries typically use mercury or mercury compounds as corrosion inhibitors. Mercury and mercury compounds are highly toxic substances.
When waste batteries are incinerated as household waste, mercury is discharged into the atmosphere at high temperatures, causing secondary pollution, with residue remaining in the ash.
Waste Battery Recycling and Treatment Methods
Overview
Internationally, waste battery recycling treatment methods generally fall into three categories: solidification with deep burial, storage in abandoned mines, and recycling.
Solidification with Deep Burial
Waste batteries are typically shipped to specialized toxic and hazardous waste landfills. However, this method is not only costly but also wasteful, as many useful materials are discarded.
Waste Battery Recycling and Reuse Technologies
(1) Heat Treatment
Switzerland has two specialized waste battery processing plants. The method involves shredding old batteries and feeding them into a furnace. Volatile mercury is extracted at lower temperatures. At higher temperatures, zinc also evaporates and is recovered as a valuable metal. Iron and manganese remain and form a manganese-iron alloy suitable for steelmaking.
The plant can process 2,000 tons of waste batteries annually, obtaining 780 tons of manganese-iron alloy, 400 tons of zinc alloy, and 3 tons of mercury. Another plant directly extracts metals from batteries, producing metal mixtures such as manganese oxide, zinc oxide, copper oxide, and nickel oxide, sold directly as metal waste.
However, heat treatment is expensive, and Switzerland charges a small fee for each battery purchased.
(2) Hydrometallurgical Treatment
In the suburbs of Magdeburg, Germany, a “wet treatment” facility is in operation. Except for lead-acid batteries, all types of batteries are dissolved in sulfuric acid, and various metals are then extracted from the solution using ion exchange resins.
The raw material purity obtained by this method is higher than that of heat treatment, making it more competitive in the market. It can extract 95% of the various substances contained in batteries.
Hydrometallurgical treatment can save the sorting step (since manual sorting increases costs). The Magdeburg facility can process 7,500 tons annually. Although the cost is slightly higher than landfilling, valuable raw materials are not discarded, and the environment is not polluted.
(3) Vacuum Heat Treatment Method
The vacuum heat treatment method was developed by Alte, Germany. It first requires sorting nickel-cadmium batteries from general waste battery streams. The waste cells are then heated in a vacuum, where mercury evaporates quickly and can be recovered.
The remaining raw materials are ground, metal iron is extracted with magnets, and then nickel and manganese are extracted from the remaining powder. The cost per ton of waste batteries processed is less than 1,500 marks (approximately 6,345 yuan).
Waste Battery Recycling Processing Technology
Due to “lead pollution incidents,” the lead battery industry has been urged to eliminate backward production capacity, leading to a slowdown in the lead battery industry and a period of development lag.
On one hand, the cause of “lead pollution incidents” is that some in the lead industry neglected pollution control, allowing lead pollutants to be generated during production and causing serious lead contamination. On the other hand, a large number of waste lead batteries lack complete, environmentally friendly, pollution-free treatment, easily causing lead-acid contamination and severe environmental pollution during processing.
New Pollution-Free Lead-Acid Battery Technology
A new pollution-free lead-acid battery technology for vehicles is likely to change this situation. This lead-acid battery technology, developed by Polish scientists, combines hydrometallurgy and pyrometallurgy, allowing sulfuric acid in lead-acid batteries to be processed into detergent raw materials.
During the process, lead metal and battery plaster can be melted in a rotary furnace and converted to powder. Polypropylene battery casings can be processed into pellets for reuse. The entire production process causes no secondary pollution.
This technology not only greatly alleviates environmental pollution but also turns waste into treasure. Its products provide important raw materials for other industries. This technology won a gold award at the 2011 Innovation Research and New Technology Exhibition in Brussels and is currently being promoted in Poland.
The pollution problem of waste batteries is gradually becoming a global concern. Waste battery recycling is a systematic project. People have been seeking technically feasible and economically viable scientific treatment methods. Harmless treatment and comprehensive utilization of waste batteries are of great significance for environmental protection and resource conservation.
Waste Battery Recycling Process
After waste batteries are collected, the treatment process includes the following steps:
1. Classification and Crushing
Recovered waste batteries can be crushed. The zinc shell, battery base iron, copper cap, and graphite rod are removed. The remaining black material is a mixture of manganese dioxide and ammonium chloride (the battery core). After collecting the above substances and processing them, useful materials can be obtained. The graphite rod, after washing and drying, can be used as an electrode.
2. Zinc Particle Recovery
The stripped zinc shells are washed and placed in a cast iron pan, heated for 2 hours, and floating impurities are skimmed off. The material is poured out to cool, then dropped onto an iron plate, yielding zinc particles after solidification.
3. Recycled Copper Sheet
The copper caps are washed with hot water, treated with 10% sulfuric acid for 30 minutes to remove the oxide layer, then removed and dried to obtain copper sheets.
4. Recovery of Ammonium Chloride
The black material is placed in a cylinder, and warm water at 60°C is added while stirring for one hour, causing all ammonium chloride to dissolve in water. After standing, filtration, and washing the slag twice, the mother liquor is collected.
5. Recycling Manganese Dioxide
After filtration, the filter cake is washed three times and then steamed to remove a small amount of carbon and other organic matter. It is then stirred in water for 30 minutes, filtered again, and the filter cake is dried at 100–110°C to obtain manganese dioxide.
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