Cost-effective and Non-toxic Substance Helps in the Extraction of Noble Metals

10:48, May 15, 2023

Scientists figure out how to use industrial waste to recycle ore

Scientists of the Ural Federal University have found a "solvent" (surfactant), lignosulfonate, which facilitates the transfer of noble metals into solution. Lignosulfonate is a waste product of pulp and paper industry, which is cheap and non-toxic. The scientists have effectively solved two serious problems at once: using a waste product along with processing ores and concentrates. The researchers published a description of the solvent's mechanism of action in the scientific journal "Langmuir." The work was supported by the Russian Science Foundation (Project № 22-79-10290).

"We investigated the mechanism of action of a very complex surfactant that is at the same time a humectant, dispersant and stabilizer in terms of the surface of the ore concentrate. Lignosulfonate has been used in autoclave metal extraction technologies since the 1970s. However, its efficiency has not been sufficiently studied and the mechanism of action has not been subjectively investigated. Taking into account the fact that today different types of ores are processed, the use of lignosulfonate for processing becomes even more important," says Tatyana Lugovitskaya, co-author of the research, Assistant Professor Researcher of the UrFU Department of Non-Ferrous Metallurgy.

Scientists have studied all stages of surfactant action during concentrate leaching under autoclave conditions. On the one hand, it will help to control the process of extraction of valuable metals - zinc, copper, lead and others. On the other hand, to regulate the efficiency of their action and expand its nomenclature.

"The technology of extracting noble metals from ores is multi-stage. Different processes take place at different stages of processing. Sometimes a surfactant is effective and sometimes is not, so we have to increase its dosage, which has a negative impact on the final commercial product. In addition, elemental sulfur is released during leaching, which slows down the process and forms diffusion foils. We have managed to find out why this surfactant behaves differently at different stages. This allows us to regulate the process of extracting metals in solution, making it more efficient and cheaper. In addition, knowledge of the mechanism opens new possibilities for developing more complex compositions of several solvents, which will make it possible to further increase the efficiency of metal extraction," - explains Tatyana Lugovitskaya.

Today, technologies are being developed around the world to extract nonferrous metals from complex ores. In the past, metal-rich ores were mined, but now their reserves are exhausted. Industrial enterprises are faced with the problem of ore processing. One of the approaches being developed around the world is the use of various surfactants. For example, in Canada, China, and South Africa, leaching technologies are being actively developed. In Russia this field is still at the beginning of development. The Urals technology for processing mineral raw materials using this surfactant will help to process ores from Russia, Kazakhstan, Mongolia, and Uzbekistan with a high degree of extraction of non-ferrous, noble, and rare metals.

Reference

Lignin is a complex polymeric compound found in all types of land plants. Lignosulfonate is a derivative of lignin, a product of technological processing of plant wood raw materials in the pulp and paper industry. Lignosulphonate is non-toxic, without irritant and allergic effect. According to the Russian classification, this substance belongs to the lowest class of danger.

Surfactants are chemical compounds that are adsorbed to the phase interface and form a highly concentrated layer on it (adsorption layer). Surfactants are used or present in almost all areas of industrial activity and consumption. There are thousands of trade names and brands of industrial surfactants and compositions based on them. For example, synthetic surfactants are the main active ingredient in detergents, shampoos and cosmetics. Food surfactants are used to improve the consumer properties of confectionery, bakery and dairy products.

The news article was translated by UrFU International Marketing Office. 
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