电解锰生产系统中Mg²⁺循环累积已成为该行业的共性技术难题，研发经济实用的除镁方法，符合双碳目标背景下的技术发展方向。研究了一种复盐结晶法来控制电解锰系统中Mg²⁺浓度。在硫酸锰溶液中加入Al₂（SO₄）₃·18H₂O生成无定形态氢氧化铝，利用无定形态氢氧化铝的特殊性质，结合传统的复盐结晶技术，将硫酸锰溶液中Mg²⁺的质量浓度控制在20 g/L以下，并获得有一定附加值的锰镁铝氧化物的前驱体。利用XRD、EDS、ICP-MS等检测手段，通过单因素和正交实验得到以下结论：当以铝镁物质的量比为0.3加入铝盐、反应温度为80 ℃、反应pH为6、反应时间为1 h时，Mg²⁺分配系数为0.43、Mn²⁺损失率为31.51%，溶液中Mg²⁺质量浓度为17.525 g/L、Al³⁺质量浓度为0.205×10^-3 g/L，达到预期目标，可保证电解锰生产系统的健康运行。

The cyclic accumulation of Mg²⁺ in electrolytic manganese production system has become a common technical problem in the industry.Developing economical and practical magnesium removal method is in line with the technical development direction under the background of dual-carbon target.A complex salt crystallization method was studied to control the concentration of Mg²⁺ in electrolytic manganese system.Al₂（SO₄）₃∙18H₂O was added into the manganese sulfate solution to generate amorphous Al（OH）₃.Based on the special properties of amorphous Al（OH）₃ and the traditional double salt crystallization technology，the concentration of Mg²⁺ in the manganese sulfate solution was controlled below 20 g/L.And the precursor of Mn-Mg-Al oxide with certain added value was obtained.By means of XRD，EDS and ICP-MS，the following conclusions were obtained by single factor and orthogonal experiment：when aluminum salt was added with aluminum magnesium molar ratio of 0.3，the reaction temperature was 80 ℃，the reaction pH was 6 and the reaction time was 1 h，the Mg²⁺ distribution coefficient was 0.43，the Mn²⁺ loss rate was 31.51%，the Mg²⁺ concentration in the solution was 17.525 g/L，and the Al³⁺ concentration was 0.205×10^-3 g/L，which reached the expected goal and ensured the healthy operation of the electrolytic manganese production system.