Abstract:As calcium-magnesium (Ca-Mg) crystallization seriously affect the operation of hydrometallurgical zinc extraction systems, a lot of attempts have been made to solve this issue. The article provides an overview of the practices and R&D in the industry for Ca-Mg removal. These practices include concentrate acidic washing, solvent extraction, fluoridation for precipitation, and cooling for crystallization, solution bleeding. The article analyzes the working mechanisms, strengths and weaknesses, and the prospects of application of these practices respectively.