Resumen
The study reports results of experimental studies into processing highly concentrated metal-containing wastes (HCMW) from galvanic production with obtaining precipitates of the predefined chemical composition, specified physical-and-chemical properties and with copper ions content. We defined the following precipitate properties in the study of copper-iron containing sludges obtained by coprecipitation of copper and iron-containing spent technological solutions (STS): humidity ? 89.7 %, density ? 1.17 kg/dm3, specific precipitate resistance ? 15?16·1011 m2/kg. It is easy to filter such precipitate. Therefore, it reduces consumption of reagents, increases purification efficiency, and makes it possible to obtain the precipitate, which is ready for transportation. Therefore, it is advisable to obtain copper-containing precipitates (sludges) with iron content for easier separation and avoiding of the conditioning operation. A technological scheme was developed for processing and subsequent disposal of copper-containing HCMW. It included transformation of copper- and iron-containing precipitate into a solution by addition of sulfuric acid; precipitation of iron ions with 25 % ammonia solution; separation of the obtained precipitate of iron hydroxide (???) by filtration for disposal; sending the obtained copper-containing filtrate for electrochemical removal of copper in the form of a metal precipitate or for disposal by the reagent method. We established in the processing of copper-containing HCMW in a diaphragm electrolyzer to extract copper in the form of a metal precipitate that the current consumption decreases with an increase in the initial metal concentration. Therefore, it is possible to ensure the degree of transformation of a=0.9 with current efficiency >80 % at the concentration of copper ions >0.1 mol/dm3. For reagent copper precipitation, it is optimal to use KOH and ?2??3 mixtures ??=9.5?10 as reagents to obtain a hydroxocarbonate precipitate. Precipitates obtained in this way are suitable for further disposal by processing or they can be raw materials for production of ready-to-use products, which may be a final stage of galvanic production