采用控制氧化焙烧过滤法从铜精矿中提取砷

Arsenic extraction from copper concentrate using controlled oxidative roasting and filtration process

为了更高效处理含砷铜精矿,砷可以通过高温过滤尘土和低温分离冷凝氧化砷2个步骤进行提取。焙烧环境中的氧含量对精矿中的残余砷含量有重要影响。当氧含量较高时,形成的砷酸盐残留在精矿中。当氧含量较低时,形成的硫化砷会堵塞滤饼残。在700℃、氧含量为4%(体积分数)的条件下焙烧,得到精矿的残余砷含量最低,由11.8%降低到0.34%(质量分数)。在中试实验中,可通过控制进料速度间接控制氧含量,能将残余砷含量降低到0.48%(质量分数),同时,回收的As_(2)O_(3)纯度可以达到99.17%(质量分数)。基于砷在不同氧含量下形态变化的机理,提出控氧焙烧与两次过滤的新工艺,并且成功运用于中试,使铜精矿中的残余砷含量低于中国精矿矿物含砷量标准(0.5%(质量分数))。

For more efficient treatment of arsenic-bearing copper concentrates,arsenic can be extracted in two steps:high-temperature filtration of dust and low-temperature separation of condensed arsenic oxide.The oxygen content in the roasting environment has an important effect on the residual arsenic content in the concentrate.When the oxygen content is high,the arsenate formed remains in the concentrate.When the oxygen content is low,the formation of arsenic sulphide can clog the filter cake residue.Roasting at 700°C with an oxygen content of 4 vol.%results in the lowest residual arsenic content in the concentrate,from 11.8 to 0.34 wt.%.In the pilot experiment,the oxygen content was indirectly controlled by controlling the feed rate.The residual arsenic content is reduced to 0.48 wt.%and the purity of the recovered As_(2)O_(3)reaches 99.17 wt.%.Based on the study of the mechanism of arsenic change with different oxygen contents,a new process of oxygen-controlled roasting is proposed and successfully applied in the pilot test,so that the residual arsenic content in copper concentrates is lower than the standard of arsenic content in imported minerals from China(0.5 wt.%).