化学沉淀法预处理稀土精矿分解废水

Pretreatment of Rare Earth Concentrate Decomposition Wastewater by Chemical Precipitation Process

采用化学沉淀法对稀土精矿分解废水进行预处理,实验结果表明,当pH9.0、n(M g2+)∶n(NH+4)∶n(PO34-)=3.5∶1∶1.5时,废水中NH3-N的质量浓度由8 370m g/L降为1 420m g/L,去除率为83%。为了不增加出水中PO34-污染物的浓度,向上层清液中加入相应量的CaC l2.2H2O。当n(Ca2+)∶n(PO34-)=9∶1时,完成沉淀反应,再调整上层清液的pH为10,搅拌后,上层清液中PO34-的质量浓度降为0.18m g/L。

The rare earth concentrate decomposition wastewater was pretreated by chemical precipitation process. The experimental results show that when pH is 9.0 and n（Mg^2＋ ） ： n（ NH4^＋ ） ： n（PO4^3- ） is 3.5 ： 1 ： 1.5, the mass concentration of ammonia nitrogen in the wastewater is reduced from 8 370 mg/L to 1 420 mg/L with removal rate 83%. Furthermore, in order to limit the concentration of PO4^3- in the effluent, it is necessary to add some CaCl2 · 2H2O into the supernatant fluid of treated wastewater. When n （ Ca^2＋ ） ： n （ PO4^3- ） is 9 ： 1 and the precipitation reaction is finished,the supernatant fluid pH is adjusted to 10,the mass concentration of PO4^3- in the supernatant fluid is 0.18 mg/L after stirring.