化学氧化法脱氰处理超细黄金氰渣

Cyanide removal for ultrafine gold cyanide residues by chemical oxidation methods

黄金氰渣中含有大量高毒性氰化物,为保护环境必须对其进行脱氰处理。首先对氰渣的工艺矿物学进行研究,然后使用三种化学氧化法进行脱氰处理。研究发现,该氰渣中主要含有元素Si,S和Fe。黄铁矿是渣中主要的金属矿物,其产生的铁络合氰化物给脱氰过程造成困难。氰渣中矿物粒度超细,单体解离度高。在H_(2)O_(2)氧化过程中,自分解和副反应导致H_(2)O_(2)大量消耗。在Na_(2)S_(2)O_(5)-空气氧化过程中,由于Na_(2)S_(2)O_(5)与O_(2)发生反应,因此整个脱氰过程耗时较长。Na_(2)SO_(3)氧化法是一种无充气装置的脱氰新方法。当pH为9.0,Na_(2)SO_(3)添加量为2.0 g/L,反应90 min后尾渣中氰化物含量降至国家标准水平。

Because of the highly toxic cyanide in the gold cyanide residues,cyanide must be removed for environmental protection.The process mineralogy of residues was studied firstly,and then cyanide removal was carried out by three chemical methods.The results showed that the residue mainly contained Si,S and Fe.Pyrite was the main metallic mineral,and the iron-complex cyanides make cyanide removal difficult.The minerals in residues were in ultrafine particle size with high monomer dissociation degrees.In H_(2)O_(2)oxidation process,the self-decomposition and side reactions resulted in high consumption of H_(2)O_(2).In Na_(2)S_(2)O_(5)-air oxidation process,the time for complete process was long because of the reactions between Na_(2)S_(2)O_(5)and O_(2).Na_(2)SO_(3)oxidation method was found to be a new method for cyanide removal without air inflation device.The cyanide content was reduced to the national standard level in 90 min at pH 9.0 with optimum Na_(2)SO_(3)dose of 2.0 g/L.