废铁屑还原软锰矿制备高纯硫酸锰工艺研究

Preparation of High Purity Manganese Sulfate from the Reduction of Pyrolusite Using Scrap Iron as the Reductant

研究了采用废铁屑作为还原剂,在稀硫酸介质中湿法还原软锰矿制备硫酸锰的工艺过程。通过单因素实验确定最佳工艺参数,结果表明：当Fe/MnO2的摩尔比为0.78∶1,H2SO4/MnO2的摩尔比为2.1∶1,反应温度50℃,反应时间80 min时,锰的浸出率在95%以上。加入碳酸钙中和调节溶液pH值至5~6,使溶液中的铁、铝等杂质离子水解为氢氧化铁、氢氧化铝等沉淀除去,加入硫化钡使浸出溶液中的重金属离子以硫化物沉淀除去,减压过滤得到硫酸锰粗滤液,向粗滤液中加入二氟化锰使溶液中的Ca2＋、Mg2＋等离子生成氟化物沉淀,然后溶液经过静置过滤得到硫酸锰净化液,滤液经浓缩、结晶制备硫酸锰产品。经检测产品纯度在99%以上,杂质含量低于国家标准。

In this paper, the leaching of manganese sulfate from pyrolusite with scrap iron as a reductant in dilute sulfuric acid solution was studied. Optimal parameters that affect the leaching efficiency of manganese sulfate were determined by the single factor method. The results shows that the leaching rate of manganese can reach more than 95% under the condition of Fe to M nO2 molar ratio of 0.78, H2SO4 to MnO2 molar ratio of 2.1, reaction temperature 50℃, reaction time 80min. Calcium carbonate was added to the leaching solution to adjust pH 5 6 so that iron,aluminum and other impurities were removed by becoming iron hydroxide,aluminum hydroxide and other precipitations. Heavy metal ions were removed by adding barium sulfide to the leaching solution to form sulfide precipitations. After being filtrated, manganese difluoride was added to the filtrate to precipitate Ca^2＋ , M g^2＋ and other impurities. After standing, the solution was then filtrated and high purity manganese sulfate solution was obtained. Crystallized manganese sulfate was obtained after being concentrated. Manganese sulfate purity can reach more than 99% and impurity contents were lower than those what the national standard claims.