In a gypsum removal process, a solution which is saturated with calcium is cooled to lower temperature with solution cooling towers to precipitate calcium as gypsum (CaSO_4 ? 2H_2O) and remove it before the next process step. In zinc refineries, gypsum removal is part of the solution purification step before electrowinning. Gypsum removal after leaching is important to control the maintenance load of the downstream equipment. Outotec gypsum removal plant was started in 2018 as a part of the zinc Direct Leaching plant in Torreon, Mexico. The plant utilizes Outotec cooling towers for solution cooling and Outotec high rate thickener for solid particle separation from the solution flow. First operation results are showing efficient gypsum removal from the solution flow. In this paper is presented the Outotec gypsum removal process and shows results from operation and discusses the importance of efficient operation and low emissions from the solution cooling.
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