A New Way to Remove Impurities from Metals During Scrap Metal Recycling

Researchers of Siberian Federal University, as part of an international team of scientists, have created a method for refining liquid metals, which allows effective purification of metals from impurities at lower energy costs. This was announced by Andrey Yasinsky, Assistant Professor of the Department of Metallurgy of Non-Ferrous Metals of the School of Non-Ferrous Metals and Materials Science of Siberian Federal University.

A share of secondary metal production is growing today, increasing the need for new highly efficient methods of recycling scrap metal. Cleaning of metals is necessary for ensuring the useful properties of new products and manufacturing alloys. One of the promising areas is electrolytic refining, in which the raw material is purified from impurities in high-temperature reactors containing liquid components for the reaction (metal, a mixture of salts and a special alloy). The authors of the work were able to select the composition of the material that acts as an electrolyte so that the technological process requires less electricity with the same degree of purification.

“Electrochemical technologies require significant energy consumption, while an electrolyte layer (molten salt), which is usually 5–10 centimetres, has got the lowest electrical conductivity. We managed to reduce the thickness of the electrolyte to 0.1 centimetre, which leads to a significant reduction in the cost of refining. Specific power consumption can be reduced by 60–70 %,” said Andrey Yasinsky.

The research also involved specialists from the Institute of High-Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences (Yekaterinburg) and the School of Materials Science and Metallurgy of the Northeastern University (Shenyang, China).

The research results showed high productivity of the purification method of metal (in that case aluminium). In particular, this was confirmed by high values of current density.

“All indicators witnessed that a mixture of alkali metal chlorides with aluminium fluoride has advantages over potassium cryolite melt,” added the scholar.

The research was carried out with the support of the Russian Science Foundation (project number 19-79-00004). You can also read the article about the research in ТASS Science(in Russian).