Chromic residue obtained from preparation of metal chromium by aluminothermic reaction, was used to recover alumina and sodium chromate by adopting a combined process consisting of roasting with molten alkali, leaching with water, carbonation decomposition, concentration and crystallization. Effects of particle size of chromic residue, alkali/residue ratio, roasting time and temperature on the recovery rate were explored. Results showed that the leaching rates of chromium and aluminum increased with an increase in the alkali/residue ratio, roasting time and temperature, as well as a decrease in the particle size of the residue. The optimal technological conditions were obtained through orthogonal experiment L9(34), including roasting at a temperature of 700 ℃ for 4 h, with particle size of residue at 0�045 mm and alkali/residue ratio of 6∶1. Consequently, the chromate salt ( calculated in terms of sodium bichromate) and alumina were obtained with purity of 88.5% and 95.4%, at total recovery of 85.6% and 96.4%, respectively, and sodium was recovered in the form of sodium carbonate and sodium bicarbonate.%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。
展开▼
