硫酸铵焙烧法浸出镍磁黄铁矿中有价金属

Leaching of valuable metals from nickel pyrrhotite by ammonium sulfate roasting method

将镍磁黄铁矿与(NH4)2SO4混合后在高温下焙烧,考察(NH4)2SO4用量、浸出温度、浸出时间和稀硫酸浸出液的pH值对焙烧产物中金属元素浸出率的影响,并在氨水-(NH4)2SO4混合溶液中浸出焙烧产物。结果表明:在不同情况下,Ni和Cu的浸出率较高,Mg和Fe的浸出率较低;氨性溶液有利于Ni和Cu的浸出,总氨浓度为7 mol/L时,Ni和Cu的浸出率分别为89.56%和79.35%;低pH值的稀硫酸溶液有利于Mg和Fe的浸出,pH值为0.5时,Mg和Fe的浸出率分别为61.39%和62.56%。由扫描电镜-能谱分析和XRD分析可知,矿样中Ni和Cu大部分被浸出;由于焙烧产物中部分Mg和Fe以铁酸钙和硅酸镁等形态存在,Mg和Fe的浸出率较低。

Nickel pyrrhotite blended with ammonium sulfate was roasted at elevated temperature. The effects of amount of ammonium sulfate, leaching temperature, leaching time and pH value of sulfuric acid leaching solution on leaching rates of metal elements in roasted products were investigated. The roasted products were also leached with a mixed solution containing ammonia and ammonium sulfate. The results show that the leaching rates of Ni and Cu are higher, and the leaching rates of Mg and Fe are lower under different conditions. The ammonia solution is beneficial to leaching Ni and Cu. When the total ammonia concentration is 7 mol/L, the leaching rates of Ni and Cu are 89.56% and 79.35%, respectively. The sulfuric acid solution with low pH value is beneficial to leaching Mg and Fe. When the pH value is 0.5, the leaching rates of Mg and Fe are 61.39% and 62.56%, respectively. The SEM-EDS and XRD analysis shows that most of Ni and Cu are leached out. The leaching rates of Mg and Fe are lower because of undissolved magnesium silicate and calcium ferrite in the roasted products.