(1. 中南大學(xué) 冶金與環(huán)境學(xué)院，長(zhǎng)沙 410083；
2. 湖南城市學(xué)院 材料與化學(xué)工程學(xué)院，益陽(yáng) 413000)
摘 要: 采用復(fù)合鹽沉淀法處理含砷廢水，研究了鈣砷比、銅砷比、鐵砷比、鋅砷比對(duì)砷脫除率的影響，并以硫酸濃度、液固比、浸出時(shí)間、浸出溫度為考察因素，對(duì)含砷沉淀渣進(jìn)行浸出，從浸出液中回收三氧化二砷，同時(shí)回用脫砷后母液。結(jié)果表明：在n(Ca)/n(As)=1.05、n(Cu)/n(As)=0.45、n(Fe)/n(As)=1.20、n(Zn)/n(As)=1.20的復(fù)合鹽配比下，處理初始As(Ⅲ)濃度為0.05~9.76 g/L含砷廢水時(shí)，砷殘留濃度均低于14 mg/L，通過(guò)增加復(fù)合鹽用量進(jìn)行二次脫砷沉淀，濾液中銅、鋅、砷濃度在《污水綜合排放標(biāo)準(zhǔn)》(GB 8978—1996)范圍內(nèi)。在液固比(mL:g)為3:1、浸出時(shí)間為0.5 h、浸出溫度為25 ℃、硫酸濃度0.87 mol/L條件下對(duì)含砷渣進(jìn)行浸出，并回收三氧化二砷，可使砷回收率達(dá)到72.38%。將回收后母液回用處理初始As(Ⅲ)濃度為50 mg/L的含砷廢水，可使砷脫除率達(dá)83.65%，復(fù)合鹽利用率可達(dá)80%以上，具有生態(tài)與經(jīng)濟(jì)雙重效益。
關(guān)鍵字: 復(fù)合鹽；二次脫砷；浸出；含砷廢水；循環(huán)利用
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. School of Chemistry and Environmental Engineering, Hunan City University, Yiyang 413000, China）
Abstract:Arsenic-containing wastewater was treated by compound salt precipitation method. The effects of calcium-arsenic ratio, copper-arsenic ratio, iron-arsenic ratio and zinc-arsenic ratio on arsenic removal rate were studied. Taking sulfuric acid concentration, liquid-solid ratio, leaching time and leaching temperature as factors to investigate, the arsenic-containing precipitated slag was leached, and arsenic trioxide was recovered from the leaching solution, and the mother liquor after arsenic removal was reused. The results show that, under the optimal compound salt ratio conditions of n(Ca)/n(As)=1.05, n(Cu)/n(As)=0.45, n(Fe)/n(As)=1.20 and n(Zn)/n(As)=1.20, the arsenic residual concentration is lower than 14 mg/L when the arsenic-containing wastewater with ρ(As)=0.05-9.7 g/L is treated, the concentrations of Ca, Fe, Cu, Zn and As in the filtrate are less than Integrated Wastewater Discharge Standard (GB 8978—1996) after the second arsenic removal by increasing the amount of compound salt. Under the conditions of liquid-solid ratio of 3:1, leaching time of 0.5 h, leaching temperature of 25 ℃ and sulfuric acid concentration of 0.87 mol/L, the arsenic recovery rate reaches 72.38% when arsenic-containing slag is leached and arsenic trioxide is recovered. The mother liquor after arsenic recovery is used to treat the arsenic-containing wastewater with ρ(As)=50 mg/L, and the arsenic removal rate can reach 83.65% and the compound salt utilization rate can reach over 80%, which has both ecological and economic benefits.
Key words: compound salt; secondary arsenic removal; leaching; arsenic-containing wastewater; recycling
