铬渣资源化处理的零排放工艺

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。

Zero Discharge Process for Comprehensive Utilization of Chromium Slag

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,H₂O₂ 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.