湿法冶金

铜冶炼行业镁法脱硫工艺产生的废水中含高浓度的Cu²⁺、Mg²⁺等重金属离子，采用传统的“中和—絮凝”工艺存在处理成本高、重金属资源浪费、环境污染风险大等问题。针对上述问题，研究了采用“硫化除杂—氢氧化钠沉淀”两步沉淀法从脱硫废水中回收铜和镁。首先通过精准投放硫氢化钠(理论量1.1倍)优先沉淀Cu²⁺,形成CuS;其次，采用氢氧化钠调节pH,促进Mg²⁺高效生成氢氧化镁。考察了铜和氢氧化镁沉淀过程中的pH、NaHS加入量、反应温度、反应时间、搅拌速度对回收铜和氢氧化镁的影响。结果表明：在最佳工艺条件下，铜和氢氧化镁回收率均可达95%以上。该工艺技术方法可行，不但减少了重金属排放，所形成的CuS还可作为铜冶炼生产原料、氢氧化镁可回用于脱硫系统，构建了一种“污染物治理—资源再生—工艺闭环”的循环经济模式，可为冶金行业废水资源化提供技术参考。

Magnesium desulphurization wastewater in copper smelting industry contains high concentration of heavy metal ions such as Cu²⁺ and Mg²⁺.The traditional "neutralization—flocculation" process has problems, such as high treatment costs, waste of heavy metal resources and great risk of environmental pollution.In view of the above problems, the two-step precipitation method of "sulfurization and impurity removal—sodium hydroxide precipitation" was studied to recover copper and magnesium from desulfurization wastewater.Firstly, Cu²⁺ was preferentially precipitated by precise placement of sodium hydrosulfide(1.1 times the theoretical amount) to form CuS.Secondly, sodium hydroxide is used to adjust pH and promote Mg²⁺ to produce magnesium hydroxide efficiently.The effects of pH,NaHS dosage, reaction temperature, reaction time and stirring speed on the recovery of copper and magnesium hydroxide were investigated.The results show that the recoveries of copper and magnesium hydroxide can reach over 95% under the optimal conditions.The process technology is feasible, not only reduces the discharge of heavy metals, but also the CuS formed can be used as raw materials for copper smelting production, and magnesium hydroxide can be reused in desulfurization system.A circular economy model of "pollutant treatment—resource regeneration—process closed loop" is constructed, which can provide technical reference for the recycling of wastewater in metallurgical industry.