Mechanism and control of scorodite formation for arsenic stabilization

铜是重要的贱金属之一。另一方面，由于自然资源的减少，矿石中杂质的浓度也在增加。特别是砷成为了问题。为了安全、经济地储存砷，需要分离后的固定技术。本研究的目的是阐明一种稳定的砷化合物——铁榴石的形成机理。结果表明，在不同条件下，无定形的砷酸铁在水溶液中一度在种子晶上形成，但随着保留时间的延长而结晶。还发现，即使在气体环境中，无定形的结晶也会发生。

Copper is one of important base metals. On the other hand, the concentrations of impurities in ores are increasing due to the decrease in the natural resources. In particular, arsenic becomes the problem. The technology to immobilize the arsenic after separation is required to store the arsenic safely and economically. The purpose of this study was to elucidate the formation mechanism of the scorodite which was an stable arsenic compound. It was made clear that, depending on conditions, amorphous ferric arsenate was once formed on a seed crystal in water solutions but crystallized with progress of the retention time. It was also found that crystallization of the amorphous into scorodite occurs even in gas atmospheres.