铬渣资源化处理的零排放工艺

Zero Discharge Process for Comprehensive Utilization of Chromium Slag

采用氧化—还原法对某钢厂的粗铬渣进行提纯回收,对各项工艺参数进行了优化,探讨了铬渣零排放处理工艺的可行性。实验结果表明:在氧化温度80℃、氧化时间1.5 h、双氧水加入量2.35 mL/g(以铬渣计),还原时间15 min、还原pH 1.5、NaHSO3加入量0.445 g/g(以铬渣计),沉淀pH 8.0,煅烧温度1 050℃、煅烧时间1 h的条件下,所得废渣的w(Cr)为1.29%,回收铬绿产品的w(Cr2O3)为97.20%,铬回收率为94.40%;处理后废水的ρ(总铬)约为0.06 mg/L,低于GB 13456—2012《钢铁工业水污染物排放标准》中规定的1.50 mg/L,既可作为循环用水,也可排放;处理后废渣中含大量硅元素,可作为生产水泥发泡节能砖或砌块的原料;整个回收过程清洁无污染,零排放,且具备一定的盈利空间。

Rude chromium slag from a steel plant was refined and recovered by the oxidation-reduction process.The process parameters were optimized and the feasibility of the zero discharge process for chromium slag treatment was discussed.The experimental results show that：Under the conditions of oxidation temperature 80 ℃,oxidation time 1.5 h,H202 dosage 2.35 mL/g,reduction time 15 min,reduction pH 1.5,NaHSO3 dosage 0.445 g/g,precipitation pH 8.0,calcination temperature 1 050 ℃ and calcination time 1 h,the w（Cr） of the residue is 1.29％,the w（Cr2O3） of the product chrome green is 97.20％,and the recovery rate of chromium is 94.40 ％; The ρ（total chrome） of the wastewater is about 0.06 mg/L,which is lower than the national wastewater discharge standard of GB 13456-2012（1.50 mg/ L）,so that the wastewater can be either recycled or discharged; The large amount of silicon in the residue can be used to produce foamed cement brick or building block; In addition,the process is clean and economically feasible.