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采用在熔融碱中焙烧-水浸-碳酸化分解-浓缩结晶工艺从铝热法生产金属铬所得炉渣中回收氧化铝和铬酸钠,探讨了铬渣粒度、碱渣比、焙烧时间以及温度等因素对铬和铝浸出率的影响。研究表明,铬和铝的浸出率随碱渣比、焙烧时间以及焙烧温度增加而增加,随铬渣粒度减少而增加。通过四因素三水平正交实验确定焙烧最佳浸出工艺条件为:焙烧温度700℃,焙烧时间4 h,粒度0.045 mm和碱矿比6∶1。所得铬盐(以重铬酸钠计)和氧化铝的纯度分别为88.5%和95.4%,总回收率分别达到85.6%和96.4%,钠以碳酸钠和碳酸氢钠的形式得到回收。
Alumina and sodium chromate were recovered from the slag produced by the aluminothermy process by calcination - flooding - carbonation decomposition - concentration crystallization process in the molten alkali, and the effects of chromium slag size, ratio of alkali to slag, calcination time and temperature were discussed Effect of Factors on Leaching Rate of Chromium and Aluminum. The results show that the leaching rate of chromium and aluminum increases with the ratio of soda to slag, calcination time and calcination temperature, and increases with the decrease of chromium slag size. The orthogonal experiment of four factors and three levels determined that the optimum conditions of roasting were as follows: roasting temperature 700 ℃, roasting time 4 h, particle size 0.045 mm and ratio of alkali to ore 6:1. The purity of the obtained chromium salt (based on sodium dichromate) and aluminum oxide were 88.5% and 95.4%, respectively. The total recoveries reached 85.6% and 96.4%, respectively. Sodium was recovered as sodium carbonate and sodium bicarbonate.