(昆明理工大學(xué) 冶金與能源工程學(xué)院，昆明 650093)
摘 要: 針對低溶液過飽和度是常壓臭蔥石合成過程的關(guān)鍵要素這一問題，本文在As(Ⅴ)-Fe(Ⅱ)體系下，通過Fe2+緩慢氧化來控制溶液過飽和度，研究了pH對Fe2+氧化速率的影響、Fe2+氧化速率與過飽和度的關(guān)系和過飽和度對砷鐵沉淀率、臭蔥石組分含量、顆粒粒徑、形貌及其穩(wěn)定性的影響。結(jié)果表明，F(xiàn)e2+的氧化速率隨初始pH值的降低而降低，而溶液過飽和度隨Fe2+氧化速率的降低而降低。較低的初始過飽和度不利于砷鐵的沉淀，對渣中砷鐵含量影響不顯著，但對渣中硫含量影響較大。初始過飽和度從7.86升至78.86時，砷、鐵沉淀率分別從77.05%、53.9%升至88.66%、61.79%，渣中砷、鐵和硫含量分別為30.74%、24.14%和0.58%~0.17%。臭蔥石顆粒粒徑隨初始過飽和度的增加而先增加后減小，初始過飽和度值為11.7時，顆粒尺寸達(dá)到最大87.5 μm。初始過飽和度為7.86~24時，形成類球型臭蔥石顆粒；初始過飽和度值為24~78.86時，形成無規(guī)則型臭蔥石顆粒。通過控制初始過飽和度在7.86~78.86下，合成的臭蔥石穩(wěn)定性高，其浸出毒性均小于1 mg/L。
關(guān)鍵字: 臭蔥石；過飽和度；顆粒尺寸；浸出毒性
（Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China）
Abstract:According to the problem that low solution supersaturation was the key factor in the process of scorodite synthesis under atmospheric pressure, the effect of pH on the oxidation rate of ferrous iron, the relationship between the oxidation rate of ferrous iron and supersaturation, and the effect of supersaturation on the precipitation percent of arsenic and iron, the content of scorodite components, particle size, morphology and stability were investigated in an As(Ⅴ)-Fe(Ⅱ) system by slow oxidation of ferrous ions. The results show that the oxidation rate of ferrous ions decreases with the decrease of initial pH value, while the supersaturation of solution decreases with the decrease of oxidation rate of ferrous ions. Lower initial supersaturation is not conducive to the precipitation of As and Fe, and has no significant influence on the content of arsenic and iron in the synthesized scorodite but has a greater impact on the sulfur content in synthesized scorodite. The initial supersaturation increases from 7.86 to 78.86, and the arsenic iron precipitation percent increases from 77.05% and 53.9% to 88.66% and 61.79%, respectively, and the contents of arsenic, iron and sulfur in the scorodite are 30.74%, 24.14% and 0.58%-0.17%, respectively. The particle size of scorodite first increases and then decreases with an increase of initial supersaturation. When the initial supersaturation is 11.7, the particle size reaches a maximum of 87.5μm. The initial supersaturation is in the range from 7.86 to 24, the spheroidoid particles are synthesized. The initial supersaturation is in the range from 24 to 78.86, it is irregular scorodite particles. By controlling the initial supersaturation in the range of 7.86-78.86, the stability of the synthesized scorodite is high, and its leaching toxicity is less than 1 mg/L.
Key words: scorodite; supersaturation; particle size; leaching toxicity
