(1. 中南大学 化学化工学院，长沙 410083；
2. 中南大学 冶金与环境学院，长沙 410083)
摘 要: 砷碱渣中含有剧毒可溶性砷化合物，若不妥善处置，易造成水体污染和生物中毒。本研究目的是将砷碱渣中的砷转化为大颗粒晶型臭葱石以利于安全储存。在制备臭葱石晶体的反应中，考察了初始pH值、Fe/As摩尔比和反应温度对沉砷率及臭葱石形成的影响，并探究了不同条件下得到的沉淀的浸出毒性。结果表明：当初始pH值为1.0~2.0、Fe/As摩尔比为0.5~3.0及反应温度为105~175 ℃时，沉砷率可达80%以上，所得臭葱石晶体的As浸出浓度低于5 mg/L。在初始pH值为1.5、Fe/As摩尔比为1.0及反应温度为150 ℃的优化条件下，得到的臭葱石晶体呈八面体形状，颗粒尺寸可达20 μm，且As浸出浓度低至0.08 mg/L，适于稳定化处理砷并长期安全储存。
关键字: 砷碱渣；砷；臭葱石；沉砷率；浸出毒性
（1. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China;
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:Arsenic alkali residue contains highly toxic soluble arsenic compounds, if not properly disposed, easy to cause water pollution and biological poisoning. The purpose of this study was to convert arsenic from arsenic alkali residue into large-sized crystalline scorodite for safe storage. The effects of initial pH, Fe/As molar ratio and reaction temperature on the As precipitation rate and formation of scorodite, as well as on the leaching toxicity of the precipitates were investigated. The results show that, under the conditions of initial pH of 1.0-2.0, Fe/As molar ratio of 0.5-3.0 and reaction temperature of 105-175 ℃, the As precipitation rate can reach more than 80%, and the As leaching concentration of the obtained scorodite is less than 5 mg/L. Well crystallized octahedral scorodite with particles size up to 20 μm can be obtained under the optimal conditions of initial pH of 1.5, Fe/As molar ratio of 1.0 and 150 ℃, and the As leaching concentration is as low as 0.08 mg/L, suggesting the crystalline scorodite has sufficient stability and is suitable for arsenic stabilization and long-term storage.
Key words: arsenic alkali residue; arsenic; scorodite; As precipitation rate; leaching toxicity
