湿法解毒还原工艺对铬渣中Cr(Ⅵ)的治理特性

以治理铬渣中的Cr(Ⅵ)污染为目的,提出了硫酸浸出-硫酸亚铁还原的铬渣湿法解毒工艺,在对铬渣处理前后的表面形貌进行表征的基础上,探究了不同处理条件下铬渣中Cr(Ⅵ)的处理效果及其修复机理。结果表明:铬渣湿法球磨时间为20 min时,铬渣颗粒98. 68%过200目筛,水溶性Cr(Ⅵ)的浸出率可达40. 96%;铬渣硫酸添加量为60%,液固比为4∶1,酸溶时间为2. 5 h时,Cr(Ⅵ)浸出趋于饱和,此时浸出终点p H为5. 8,水溶性和酸溶性Cr(Ⅵ)总浸出率为95. 38%;硫酸亚铁添加量为40%时,铬渣中Cr(Ⅵ)含量下降为1. 38 mg/kg。铬渣中Cr(Ⅵ)的去除主要与硫酸对含Cr(Ⅵ)矿物的溶解、SO₄^2-和CrO₄^2-的离子交换以及Fe(Ⅱ)对溶液中Cr(Ⅵ)的还原作用有关。

RESEARCH ON WET DETOXIFICATION TECHNOLOGY OF CHROMITE ORE PROCESSING RESIDUE

Aiming at the treatment of Cr(Ⅵ) pollution in chromite ore processing residue (COPR), a wet detoxification process of COPR with sulfuric acid leaching and ferrous sulfate reduction was proposed in this paper. Based on the characterization of the surface morphologies of COPR before and after remediation, the treatment effect and remediation mechanism of Cr(Ⅵ) under different treatment conditions were investigated. The results showed that when the wet ball milling time of COPR was 20 min, 98.68% of the chromium slag particles passed through a 200 mesh sieve, and the leaching rate of water soluble Cr(Ⅵ) reached 40.96%. When the slag sulfuric acid was added at 60%, the liquid-solid ratio was 4∶1, and the acid dissolution time was 2.5 h, the leaching of Cr(Ⅵ) tended to be saturated. At this time, the pH of endpoint was 5.8, and the total leaching rate of Cr(Ⅵ) was 95.38%. When the ferrous sulfate was added at 40%, the content of Cr(Ⅵ) decreased to 1.38 mg/kg. The removal of Cr (Ⅵ) in COPR was mainly related to the dissolution of Cr(Ⅵ)-containing minerals by sulfuric acid, the ion exchange of SO₄2- and CrO₄2-, and the reduction of Cr(Ⅵ) in solution by Fe(Ⅱ).