针对含砷硫酸烧渣酸浸液的铁盐沉淀固砷

Arsenic fixation in acid leaching solution obtained from arsenic-containing pyrite cinder by iron salt precipitation

为考察含砷硫酸烧渣中酸浸脱砷效果和铁盐沉淀固砷行为,采用常温常压酸浸法脱除硫酸烧渣中的砷,并对进入浸出液中的砷以铁盐沉淀的形式脱除,进而对沉淀渣的浸出毒性进行研究。同时,研究了磨矿细度、酸浓度、固液比、浸出时间对硫酸烧渣中砷脱除效率的影响。结果表明,通过控制浸出参数可以将硫酸烧渣中砷的质量分数降低到0.2%以下,通过调节浸出液的pH和Fe/As摩尔比将其中的砷以沉淀的形式脱除。当Fe/As> 2、pH=4～6时,溶液中砷浓度降到了0.5 mg·L^(-1)以下。沉淀砷渣主要是以非晶态的形式存在,提高铁砷比有利于提高砷渣稳定性,从而降低浸出毒性。在Fe/As=3、pH=6.04～6.22的条件下,得到的沉淀渣的浸出毒性为0.711 mg·L^(-1)。因此,通过酸浸脱除硫酸烧渣中的砷,进而采用铁盐沉淀的方法能够实现硫酸烧渣中砷的安全处置。

In order to investigate the effect of arsenic removal from arsenic-containing pyrite cinder using acidleaching method and the behavior of arsenic fixation by conventional iron salt precipitation, the arseniccontaining in the cinder was removed by acid leaching at room temperature and atmospheric pressure, and thearsenic in leaching solution was removed by iron salt precipitation, then the leaching toxicity of precipitates wasstudied. The effects of grinding fineness, acid concentration, solid-liquid ratio and leaching time on arsenicremoval efficiency were investigated. The results show that the arsenic content of the pyrite cinder could bereduced to less than 0.2% by controlling leaching parameters. The arsenic in the leaching solution could beremoved as precipitates by adjusting the pH and Fe/As molar ratio. The arsenic concentration in the leachingsolution could decrease below 0.5 mg·L-1when the Fe/As ratio was greater than 2 and the pH was between 4 and 6. The results demonstrate that the precipitates mainly exist in an amorphous form, and increasing the Fe/Asratio could improve the stability and reduce the leaching toxicity of the precipitates. The leaching toxicity of theprecipitates was reduced to 0.711 mg·L-1under the condition of Fe/As = 3, pH = 6.04~6.22. Therefore, the safedisposal of arsenic can be realized by acid leaching to remove arsenic from pyrite cinder and then iron salt precipitation.