分步沉淀法处理酸性矿山废水

Treatment of acid mine drainage by fractional precipitation process

采用分步沉淀工艺处理酸性矿山废水,考察了工艺条件对废水中有价金属元素回收效果的影响。实验结果表明:Ca(OH)_2为适宜的废水pH调节剂;调节废水pH至4.00左右并投加0.05 mL/L的H_2O_2,可首先去除Fe^(2+)及Fe^(3+),得到富Fe渣(w(Fe)=51.00%);调节废水pH至6.00~6.50,先投加50 mg/L的Na_2S,去除废水中的Cu^(2+),获得富Cu渣(w(Cu)=10.89%),再将Na_2S的投加量增至100 mg/L,去除废水中的Zn与Mn,获得富Zn-Mn渣(w(Cu)=2.37%,w(Mn)=6.79%,w(Pb)=1.61%);进一步调节废水pH至8.40,可去除剩余的Zn、Mn及其他重金属。分步沉淀工艺处理后的废水可达标排放,产生的富Fe渣、富Cu渣及富Zn-Mn渣可直接出售或具有利用价值。分步沉淀工艺可实现有价金属元素的高效回收,大幅度降低废水处理的实际成本,值得工程应用与推广。

The acidmine drainage （AMD ） was treated by fractional precipitation process. Theeffects ofthe process conditions on recover of valuable metals from AMD were studied. The experimental results show that： Ca （OH） 2 is the suitable agent for pH adjustment; When the wastewater pH is adjusted to about 4.00 and 0.05 mL/L ofH202 is added, Fe2＋ and Fe3＋ are firstly removed from the wastewater and the iron-rich sludge with 51.00% ofw （Fe） is obtained; Then the wastewater pH is adjusted to 6.00-6.50, with the addition of 50 mg/L Na2S, CuE2＋ is removed from the wastewater and the copper-rich sludge with 10.89% ofw （Cu） is obtained, and with the addition of 100 mg/L Na2S, Zn and Mn are removed from the wastewater and the zinc-manganese-rich sludge with 2.37% ofw （Cu）, 6.79% ofw （Mn）, 1.61% ofw （Pb）is obtained; Finally, when the wastewater pH is adjusted to 8.40, the rest Zn, Mn and other heavy metals are removed. After treated by fractional precipitation process, the effluent quality can meet the national discharged standard, and the iron-rich sludge, copper-rich sludge and zinc- manganese-rich sludge can be sold directly or reused. The popularization and application of the fractional precipitation process is worthily because that the cost of AMD treatment could be reduced significantly with the recovery of valuable metals.