不同稳定剂对Zn、Cd复合污染废渣的稳定化效果

Stabilizing effect of different stabilizers on waste slag polluted by zinc and cadmium

针对含重金属废渣污染程度高且难处理问题,采用典型硫化物、磷酸盐、CaO、MgO以及配伍药剂对锌(Zn)、镉(Cd)复合污染强酸性废渣进行稳定化,利用水浸提法(HJ 557-2010)评估稳定化效果,以GB 8978-1996最高允许排放浓度为达标限值,达到安全处置的目的。结果表明,单一磷酸盐和硫化物中,同摩尔添加比条件下,Na3PO4·12H2O对Zn和Cd的稳定效果最好,Na2S·9H2O对砷(As)稳定效果最好,Zn、Cd、As和铜(Cu)4种金属元素同时达标时的综合稳定效应(η)依次为Na2S·9H2O(96.36%)>(NH4)2HPO4(87.42%)>Na3PO4·12H2O(82.26%)。单一MgO或CaO与组合剂的综合稳定效应顺序依次为0.4%MgO>0.4%CaO>(0.4%CaO+0.61%Na2S·9H2O)>(0.4%CaO+0.32%(NH4)2HPO4)>1.2%(Na2S·9H2O∶(NH4)2HPO4∶Na3PO4·12H2O=2∶1∶3)。MgO、 Na3PO4·12H2O、硫钙组合为优选稳定剂。研究结果可为国内含重金属废渣的高效稳定化处理提供参考。

The heavy metal concentrations in waste slag are high and difficult to deal with. In order to solve the problem, typical sulfides, phosphates, CaO, MgO and composite reagents were used to stabilize the highly acidic waste slag polluted by zinc and cadmium. The stabilization effect was evaluated by the water extraction method(HJ 557-2010). The maximum allowable discharge concentration in the standard GB 8978-1996 was taken as the standard requirement. Waste slag can be disposed safely after stabilization. The results demonstrate that among the addition of single reagent such as phosphate and sulphide at the same molar ratio, Na3 PO4·12 H2 O showed the best stabilization effect on Zn and Cd, Na2 S·9 H2 O showed the best stabilization effect on As, and the comprehensive stabilizing effect(η) when Zn, Cd, As and Cu elements simultaneously met the standard followed the order: Na2 S·9 H2O(η=96.36%)>(NH4)2 HPO4(η=87.42%)>Na3 PO4·12 H2 O(η=82.26%). The comprehensive stabilizing effect(η) of single MgO, CaO and composite reagents followed the order: 0.4% MgO>0.4% CaO>(0.4%CaO+0.61% Na2 S·9 H2 O)>(0.4% CaO+0.32%(NH4)2 HPO4)>1.2%(Na2 S·9 H2 O∶(NH4)2 HPO4∶Na3 PO4·12 H2 O=2∶1∶3). The combination of MgO, Na3 PO4·12 H2 O and calcium-sulfide was the optimized stabilizer. These results can provide solid data for the treatment of heavy metal contaminated waste slag with high efficiency in China.