ELECTROEXTRACTION OF TIN FROM METHANESULFONATE SOLUTIONS

Abstract

An important applied problem is the selective extraction of tin, copper and other valuable components from alloys obtained during the processing of used electronic and computer equipment. The amount of such waste is rapidly increasing due to the extremely accelerated pace of development of information technologies and materials science, which lead to the formation of a need for constant updating of electronic devices. Recycling of non-ferrous metals is economically, environmentally and socially expedient and already more than 30% of tin is obtained from electrical scrap. An energy-saving method of separating metals from the specified waste is their hydrometallurgical processing. Multicomponent alloys are dissolved in acidic or alkaline leaching solutions and are subsequently subjected to selective component-by-component separation. The most selective and controllable method of isolating pure tin is electroextraction. Obtaining compact precipitates of high purity tin is possible during its cathodic separation from acidic solutions in the presence of organic surfactants. Traditional acidic media for tin leaching from electrical scrap alloys are chloride, sulfate and nitrate solutions. Given the high solubility of salts of many metals and low partial vapor pressure, methanesulfonic acid has significant prospects for use as a leachant. Therefore, an important task is to establish the regularities of tin separation from methanesulfonate solutions by electroextraction. In this work, the kinetics of tin electrodeposition in the presence of oxyethylated b-naphthols, which differ in the structure of the hydrophilic group, was studied. It was found that the studied surfactants inhibit tin separation. The maximum effect of reducing the limiting adsorption current is manifested at a concentration of the studied additives of about 1 mmol/l. The least foaming and the highest cloud point, which is 85 ° C, correspond to a solution of nonionic oxyethylated b-naphthol. This is important for the high-speed electroextraction process, which is carried out at elevated temperatures. It has been shown that the use of non-ionic oxyethylated b-naphthol in the methanesulfonate electroextraction solution allows obtaining compact fine-crystalline tin precipitates in a wide range of current densities.