碳酸钠碱熔处理褐铁型红土镍矿的热力学分析与实验研究

Thermodynamic Analysis and Experimental Study on Alkali-roasting Treatment of Limonitic Laterite Ore with Sodium Carbonate

对Na2CO3碱熔处理褐铁型红土镍矿过程进行了热力学分析和实验研究.热力学分析表明,在500～1500K,针铁矿和三水铝石的分解趋势明显,铬铁矿FeOCr2O3在高温下分解.焙烧过程可生成Na2CrO4,并呈FeOCr2O3>Cr2O3的顺序,且温度升高,铬的浸出率增大.NaAlO2和硅酸钠的生成反应在高温下自发进行,在1123～1273K,温度升高,铝、硅的浸出率均呈现增大趋势.但温度继续升高,已生成的NaAlO2易与SiO2发生反应生成铝硅酸钠相,导致可溶性铝、硅和钠的损失.实验得出在1273K,2h及碱矿质量比0.6的条件下,铬、铝和硅的浸出率分别为99.7%,82.8%和40.4%.

Thermodynamic analysis and experimental study on the treatment of limonitic laterite ore by sodium carbonate roasting have been performed.Thermodynamic analysis results show that in the range of 500～1500 K,the decomposition of goethite and gibbsite can take place easily whereas chromite is decomposed spontaneously at high temperature.The formation reaction of sodium chromate during the alkali-roasting treatment process is feasible,and the thermodynamic trend FeO·Cr2O3Cr2O3.Increasing the roasting temperature increases the leaching rate of Cr.And high temperature favors the production of sodium aluminate and sodium silicate,and increasing the roasting temperature improves the leaching rates of Al and Si in 1123～1273 K.However,with the further increase of temperature,the preferential generation of sodium alumino-silicate precipitates by the reaction between sodium aluminate and silicon dioxide can result in loss of soluble Al,Si,and Na.Experimental results show that the leaching rates of Cr,Al,and Si are 99.7%,82.8%,and 40.4%,respectively,under the roasting temperature of 1273 K,roasting time of 2 h,and mass ratio of Na2CO3 t ore of 0.6.