砷在金属矿山中的赋存形态及迁移机制

金属矿山在采矿、选矿、冶炼的过程中经常会产生环境污染的问题, 其中矿山酸性废水(acid mine drainage, 简称AMD)所带来的砷污染是最为严重的重金属污染问题之一。总结了砷在金属矿山中的赋存形态及其在不同矿物中活化、迁移的化学过程和形态转化规律, 认为: ①黄铁矿和毒砂是金属矿山中最普遍的含砷矿物; ②砷随着原生矿物的氧化溶解活化出来, 在AMD中主要以砷酸盐和亚砷酸盐的形态存在, 其中亚砷酸盐的迁移性更强; ③AMD中次生矿物(如黄钾铁钒、针铁矿、臭葱石等)吸附沉淀可以减缓砷的迁移速率、减少砷的迁移量但不能阻止砷的迁移。含砷矿物的次生氧化过程和次生矿物中砷的稳定能力研究可以对砷在矿山环境中迁移机制的深入理解和砷污染治理方案的制定提供新的思路和研究方向。 

Occurrence state and migration mechanism of arsenic in metal mines

Environmental pollution often occurs in the process of mining, beneficiation and smelting of metal mines.Arsenic pollution caused by acid mine drainage (AMD) is one of the most serious pollution problems of heavy metals. At present, the understanding of the evolution process of secondary minerals is insufficient. This paper summarizes the occurrence form of arsenic in metal sulfide.The specific chemical process of activation and migration in different minerals are discussed.Three rules of form transformation are concluded. ①Pyrite and arsenopyrite are the most common arsenic-bearing minerals in metal sulfide mines; ②Arsenic is activated by the oxidation and dissolution of primary minerals, existing mainly in the form of arsenate and arsenite in AMD of which arsenite is more migratory. ③Adsorptive precipitation of secondary minerals in AMD (such as ferro-vanadium, goethite, scallion, etc.) can slow the migration rate and reduce the migration amount of arsenic but cannot prevent the migration process. The migration mechanism of arsenic in the mine environment is reviewed, and new treatment schemes and research directions are proposed.