Centrifugal extractors are used in hydrometallurgy for copper processing

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Hydrometallurgy is a science and technology that uses leaching agents to dissolve the valuable metal components in ores, concentrates, roasted ores, and other materials in solution or to precipitate them as new solid phases, thereby enabling the separation, enrichment, and extraction of metals. Since this type of metallurgical process is mostly carried out in aqueous solutions, it is called hydrometallurgy. The processes in hydrometallurgy are relatively complex; this article mainly introduces the application of centrifugal extractors in the copper extraction process within hydrometallurgy. The history of hydrometallurgy dates back to 200 BC; records of using chalcanthite to extract copper can be found from the Western Han Dynasty in China. However, the modern development of hydrometallurgy is inseparable from the success of hydrometallurgical zinc processing, the invention of the Bayer process for alumina production, the development of the uranium industry, and the invention in the 1960s of hydroxamate extractants and their application in hydrometallurgical copper processing. Hydrometallurgical Processes and Current Status: As ore grades decline and environmental protection requirements become stricter, hydrometallurgy plays an increasingly important role in the production of non-ferrous metals. Hydrometallurgy mainly includes unit operations such as leaching, solid-liquid separation, solution purification, metal extraction from solutions, and wastewater treatment. Application of the wet copper smelting process: Copper ore or concentrate is leached using solvents, and then copper is extracted from the leachate. The main processes include leaching (see extraction), purification, extraction, and other steps. Currently, the output of wet copper smelting worldwide accounts for about 12% of the total production. Since the 1960s, many studies have been conducted on the wet-process smelting of copper sulfide ores to eliminate SO2 pollution, but due to economic factors that are not as favorable as those of the pyrometallurgical process, most wet-process technologies remain at the experimental and small-scale production stage. Wet copper smelting is currently mainly used to process copper oxide ores. There are methods such as direct acid leaching and ammonia leaching of copper oxide ore (or ammonia leaching after reduction roasting) ； Acid leaching is widely used, while ammonia leaching is limited to the treatment of cohesive oxidic ores with high calcium and magnesium contents. The treatment of sulfide ores commonly involves sulfurization roasting-leaching or direct leaching with ammonia or chloride solutions. ①The sulfation roasting-leaching method converts the copper in the concentrate into soluble copper sulfate for leaching ； ②The ammonia leaching method involves converting copper into copper-ammonia complexes for leaching; the leachate is then reduced with hydrogen in a high-pressure reactor to produce copper powder, or copper can be obtained through solvent extraction-electrodeposition ； The chloride leaching method involves converting copper into copper-chloride complexes that enter the solution, after which diaphragm electrolysis is used to obtain metallic copper. The solvent extraction process using centrifugal extractors in hydrometallurgy takes advantage of the difference in the distribution ratios of certain metals between organic solvents and aqueous solutions. When the organic phase and the aqueous phase are in full contact, certain metals in the aqueous phase will selectively transfer to the organic phase; this process of metal transfer is known as extraction. In hydrometallurgy, it is commonly used for extracting valuable metals from aqueous solutions or as a method for purifying solutions. Since both the aqueous solution and the organic solution in contact are liquid phases, solvent extraction is often referred to as liquid-liquid extraction. Compared with other separation methods such as precipitation and ion exchange, solvent extraction offers advantages including high efficiency in extraction and separation, elimination of the need for filtration, low reagent consumption, high recovery rates, large production capacity, and ease of automation and continuous operation. In recent years, it has been widely used in fields such as hydrometallurgy, petroleum, chemicals, and environmental protection. An extraction system usually consists of an immiscible organic phase and an aqueous phase. The organic phase consists of an extractant and a diluent, while the aqueous phase usually contains one or more metal ions to be extracted or separated. The process of transferring the extracted substance from the organic phase to the aqueous solution is called back-extraction. It is divided into liquid-phase extraction and slurry extraction depending on whether the aqueous phase contains solid suspensions. When more than two extractants are used according to the extraction process, it is referred to as synergistic extraction or antisynergistic extraction.