硫化水素を用いたCu，Zn，Ni混合めっき廃水の選択的硫化による金属硫化物の分離

抄録

Experiments were conducted to investigate selective sulfuration of copper, zinc and nickel contained in a simulated plating wastewater using H₂S as a sulfurating agent. The sulfuration of single solutions of copper, zinc and nickel, and mixed solutions of these metals with H₂S was conducted in a bubble column reactor.
As a result, it was found that heavy metals can be selectively precipitated from the mixed-metal plating wastewater at a pH value of 1.5 for copper, 4.5 for zinc and 6.7±0.2 for nickel. The purities of precipitates based on total amount of metal contained were 95.5%, 87.4% and 94.7% in the case of copper, zinc and nickel, respectively. When the results were compared with those obtained for the selective precipitation with Na₂S, it was found that higher purities of metal sulfides were achieved with H₂S. It was considered that local increases of pH resulting from an addition of alkaline sulfurating agent of Na₂S were avoided in the case of H₂S. Consequently, an undesirable co-precipitation of zinc and nickel sulfides at a pH value of 1.5 corresponding to copper selective precipitation was reduced. Similarly, the precipitation of nickel sulfide was partially avoided during the precipitation of zinc sulfide at a pH value of 4.5.