砷的管理和稳定化

Arsenic management and stabilization

砷是一种化合物,没有显著的市场价值,但由于环保和工艺技术的原因,需要从矿石、精矿和其它工艺溶液中脱除砷。奥图泰(Outotec)最初开发了一种部分焙烧高砷硫化物精矿的脱砷工艺。在该工艺中,砷在气相中得到挥发,并从固体产物(焙砂)中分离出来。若采用湿法回收砷,需要对工艺烟气进行骤冷处理,废水处理工厂需要对砷进行稳定化处理。奥图泰(Outotec)开发了砷酸铁沉淀工艺,从湿式气体净化系统的废水中产出稳定的砷残渣。如果生产合理,产出的铁基沉淀物能够满足通常的填埋要求。采用不同的浸出方法研究了沉淀渣中砷的溶解行为特点,讨论了奥图泰(Outotec~)砷酸铁工艺的典型流程,结果表明,合理的工艺控制和次序对产生能够满足填埋处置要求的含砷废物很重要。

Arsenic is a compound that has no significant market value,but that needs to be removed from ores,concentrates and other process streams because of environmental or process technical reasons.One example of a removal process is partial roasting of high-As sulfide concentrates,originally developed by Outotec.In this process the arsenic is volatilized in the gas phase and thus separated from the solid material,i.e.the calcine.If the arsenic is recovered by wet methods the process gas is quenched and all arsenic needs to be stabilized in the effluent treatment plant.Outotec has developed ferric arsenate precipitation as a method to produce stabile arsenic residues from wet gas cleaning effluents.Iron based precipitates,when correctly produced,can meet typical landfill criteria measured with different types of leaching methods meant for characterizing the arsenic dissolution behavior from the precipitates.A typical flow sheet of Outotec~ Ferric arsenate process is discussed with results showing the importance of correct process control and sequence on producing arsenic containing waste that can meet the landfill disposal requirements.