熔盐法活化处理含铬红土镍矿浸出液的铬铝分离及碱液循环

Separation of Chromium and Aluminum and Alkali Recirculation in Treatment of Laterite Nickel Ore Containing Chromium with NaOH Solution

基于Na_2CO_3,Na_2CrO_4,NaAlO_2在NaOH溶液中的溶解度及NaAlO_2的性质,采用蒸发结晶、碳化沉铝、苛化等方法对浸出液中铬、铝进行了分离,并实现了碱液循环.结果表明,采用分步结晶,一次蒸发排盐终点控制碱液浓度在40%(ω),结晶相中为大量NaAlO_2和少量Na_2CrO_4;二次蒸发碱液浓度控制在50%(ω),结晶相中为大量Na_2CrO_4和少量Na_2CO_3.一次排盐结晶相溶解后通过碳化方式将铝分离,深度碳酸化后NaAlO_2分解率达90.8%;二次排盐结晶相溶解后在90℃、苛化1h、加钙量为理论量的1.2倍时,苛化率达79.2%,苛化液蒸发后过滤得到较纯的Na_2CrO_4晶体.

The leaching solution of laterite nickel ore containing chromium treated with NaOH contains sodium hydroxide,sodium aluminate,sodium chromate,and sodium carbonate.In order to separate Cr and Al from the leaching solution,the separation behavior was investigated through evaporation crystallization,carbonization and causticization.The results show that there are most of sodium aluminum and a little sodium chromate in the crystal phase when the alkali concentration of the first evaporation crystallization is around 40%（ω）.The pure aluminum oxide can be obtained by carbonization,and the decomposition percentage is 90.8%.While most of sodium chromate and a little sodium carbonate are contained in the crystal phase over the secondary evaporation crystallization with the alkali concentration of 50%（ω）.Pure chromate oxide can be obtained through causticizing at 90 ℃ for 1 h,the mass ratio of calcium to theoretical amount is 1.2：1,the causticizing percentage can be up to 79.2%.