Ural Federal University: New Technology Can Efficiently Extract Non-Ferrous Metal from Batteries

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Scientists at Ural Federal University have developed a technology for extracting non-ferrous metals from spent zinc-manganese batteries. The zinc and manganese extracted in this way can be used in metallurgy and sent to production as raw materials. The technology is a closed cycle and can be easily implemented at existing metallurgical plants. A description of the technology and experimental results are presented in the Russian Journal of Non-Ferrous Metals.

Zinc-manganese batteries, specifically salt and alkaline batteries, are ubiquitous in everyday life, such as in remote controls, wireless computer mice, keyboards, clocks, and other devices. Recycling of such batteries is topical for obtaining zinc and especially manganese, since the latter is not produced in metallic form in Russia. The recovered zinc can be used as a reducing agent for gold in the process of its deep cleaning from impurities. Manganese can be used in steel production as an alloying element or a deoxidizer, in other words for removing dissolved oxygen from the metal.

“In Russia about 1 billion zinc-manganese batteries are accumulated as waste, and no more than 3% of them are recycled. The accumulation of batteries in landfills is dangerous because they can spontaneously ignite. Burning batteries release dioxins into the atmosphere as toxic substances that have mutagenic, immunosuppressant and carcinogenic effects. Thus, our team solves two problems: caring for the environment and people’s health, as well as the possibility of useful use of metals,” says Elvira Kolmachikhina, Associate Professor of the Department of Non-Ferrous Metallurgy at Ural Federal University.

Metals are extracted from pre-crushed batteries at different stages of the process. Zinc is obtained through leaching by selective dissolution in sodium or potassium hydroxide (strong alkalis). After that, dissolved zinc is selectively extracted from the solution by electroextraction (electrochemical method of metal extraction from the solution) in the form of a powder. Smelting of the remaining insoluble metal residue yields metallic manganese. The alkaline solution after zinc extraction is reused at the leaching stage.

The researchers determined the optimum conditions necessary for high rates of the process of obtaining metals: the concentration of alkali, the temperature, the ratio of solids in the liquid. The set regime allows the maximum amount of metals to be obtained from batteries. The process will last about an hour.

“Extraction of metals from the material is complicated by the presence of heterolite and hydroheterolite in its composition. These are strong compounds of zinc and manganese oxides, which are formed during the operation of batteries and are not soluble in alkaline solutions. Because of them we were extracting about 20% of zinc, and it is possible to increase the percentage only by repeated leaching. That’s why we are working to improve the technology and to achieve destruction of zinc-manganese oxides in order to increase the recoverable percentage of non-ferrous metals,” adds Dana Bludova, co-author of the publication and Assistant of the Department of Non-Ferrous Metallurgy at UrFU.

The new battery recycling technology does not require the construction of separate recycling plants. It can be implemented at existing metallurgical plants, which already have such equipment as vibrating screens, reactors with mechanical agitation, filters, electrolysis baths, induction and drying furnaces. It is sufficient to install an additional small line with a shredder and a magnetic separator to open and remove the steel shells of the batteries in pre-treatment.

The research was conducted within the framework of the state assignment of the Russian Federation under grant No. 075-03-2021-051/5 (FEUZ-2021-0017). Scientists note that such technology may be suitable for the extraction of other metals, such as lead.

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