硝酸加压浸出红土镍矿的中试研究

Pilot Plant Study on Pressure Leaching of Nickel Laterite in Nitric Acid Medium

对红土镍矿硝酸加压浸出工艺进行了中试研究.首先通过单因素实验考察了反应温度、初始酸度、保温时间、液固比和浸出压力对浸出结果的影响,得到优化浸出工艺条件为:反应温度185℃,初始酸度200g/L,保温时间45min,液固比2m3/t,浸出压力1.8MPa.此时,镍、钴浸出率分别为84.50%和83.92%,而铁浸出率低至1.08%,实现了镍(钴)与铁之间的高效分离,且工艺稳定性良好.此外,还对浸出液提纯、浸出剂再生进行了研究,结果表明,镍(钴)可与铝、镁、钙等金属有效分离,所得镍钴渣含镍高至25.40%,便于进一步加工处理;硝酸再生率可达85%.

A pressure leaching process of nickel laterite in nitric acid medium was studied in a pilot plant scale. The effects of reaction temperature, initial acidity, holding time, liquid-to-solid ratio and leaching pressure were examined through single-factor experiments. And the optimum leaching conditions were determined to be： reaction temperature 185 ℃, initial acidity 200 g/L, holding time 45 rain, liquid-to-solid ratio 2 m3/t and leaching pressure 1.8 MPa. Under these conditions, the leaching rates of nickel, cobalt and iron were 84.50%, 83.92% and 1.08% respectively, which separated these three valuable metals, and had good stability. On this basis, leaching liquor purification and leaching agent recovery were also studied. The experimental results showed that nickel （cobalt） could be separated from aluminum, magnesium and calcium, meanwhile, the content of nickel in the nickel-cobalt containing residue could reach 25.40%, convenient for further processing, and the recovery rate of nitric acid could be 85%.