铜萃余液两段中和中试试验

Pilot Test of Low Copper Raffinate Two-steps Neutralization by Limestone and Lime

为避免湿法炼铜系统的酸和铁富集,紫金山金铜矿现开路部分低铜萃余液采用石灰一段中和达标外排处理。该工艺药剂成本高,占废水处理总成本的60%以上。为此,该矿开展低铜萃余液两段中和中试试验,结果表明:Ⅰ段采用石灰石中和至pH值为3.0左右时,废水的自由酸和总铁的去除率达97%以上,Ⅱ段采用石灰中和至pH值为7.0左右时,上清液总铜、总锌和总砷等污染物含量均能达到《污水综合排放标准》(GB 8978-1996)一级排放标准要求,且两段中和药剂成本较一段石灰中和的药剂成本降低了25.57%,两段中和的渣率也较一段石灰中和的渣率降低了6.58%。两段中和工艺的经济指标明显优于现采用的一段石灰中和工艺。

To avoid the accumulation of acid and iron in the wet copper smelting system,part of the low copper raffinate is used lime to neutralizedin Zijinshan Copper Mine.The reagent cost of the process highly accounted for over 60%of the total cost of the wastewater treatment.For this reason,the mine carried out two-steps and pilot-scale tests of low-copper raffinate solution.The pilot test results show that,the first step is to use limestone to neutralize the pH around 3.0,the removal rate of free acid and total iron in wastewater was more than 97%.The secend step is to use lime to neutralize the pH around 7.0,the content of pollutants such as total copper,total zinc and total arsenic in the supernatant can meet the primary standard Integrated wastewater discharge standard(GB 8978-1996).The reagent cost of two-steps neutralization pilot test was significantly reduced by 25.57%compared with that of lime neutralization,and the slag rate is decreased 6.58%.The economic indicators of two-steps neutralization process is obviously better than that of lime neutralization process used in Zijinshan Copper Mine.