铬铁矿无钙焙烧渣盐酸浸出

铬渣是铬铁矿生产铬盐剩下的尾矿，因含有大量铬铁铝镁元素，也是一种二次资源。采用湿法冶金工艺回收铬渣中铬、铁、铝、镁，以浓盐酸作为浸提剂，考察了液固比、浸出温度以及时间对铬、铁、铝、镁浸出效果的影响。结果表明，最佳浸出条件为：盐酸浓度12 mol·L^-1，液固比5.6 ml·g^-1，浸出温度110℃，时间6 h，该条件下铬浸出率为67.76%，同时铁铝镁浸出率分别达到89.89%、93.99%和95.21%。铬、铁、铝、镁在铬渣中存在物相不同造成了其浸出率之间的差异。此外，铬、铁、铝、镁浸出过程均符合未反应缩核模型，且主要受界面化学反应控制，其表观活化能分别为102.31、78.10、66.44和81.66 kJ·mol^-1。

Leaching of chromite ore processing residue from non-calcium roasting with hydrochloric acid

Chromite ore precessing residue is the remaining tailings of chromite produced by chromite. It is also a secondary resource because it contains a lot of ferrum, chromium, aluminum and magnesium. In this work, a hydrometallurgy process was introduced to recover chromium, ferrum, aluminum and magnesium by using hydrochloride acid as a lixiviant and three variables were studied namely, liquid-solid ratio, leaching temperature and period. The results indicated that chromium, ferrum, aluminum and magnesium can successfully be recovered from COPR and the optimum leaching conditions were at the liquid-solid ratio of 5.6 with 110℃ and 6 h period. Simultaneously, the leaching efficiencies of chromium, ferrum, aluminum and magnesium reached 67.76%, 89.89%, 93.99% and 95.21%, respectively. A shrinking core model with the surface chemical reaction control can be used to describe the leaching kinetics of chromium, ferrum, aluminum and magnesium from COPR in the concentrated hydrochloride acid solution at 90—110℃, where the apparent activation energy are 102.31, 78.10, 66.44 and 81.66 kJ·mol^-1, respectively. The analysis of particle size distribution also showed a reduction in particle size, indicating the dissolution of the solid particles. The application of Toxic Leaching Characteristic Procedure (TLCP) showed nearly no Cr⁶⁺ in the effluent, indicating that the residue will not contaminate the environment through leaching, and can be used for load bearing or backfill material.