含铜电镀污泥熔炼过程中主要元素的迁移转化行为研究

Study on migration and transformation behaviors of main elements during smelting process of copper-bearing electroplating sludge

为了明确含铜电镀污泥熔炼过程中主要元素的迁移转化规律,利用FactSage 8.0软件进行了热力学计算,提出“氧化脱硫-还原熔炼”的含铜污泥回收工艺,考察各因素对脱硫率和铜回收率的影响。研究结果表明:直接对含铜电镀污泥进行还原熔炼,大部分的铜会与硫结合形成铜锍。通过氧化熔炼能有效脱除污泥中的硫并最终生成品位较高的低硫铜产品,而铁硅系氧化物的存在能够显著降低脱硫所需的温度。在氧化脱硫温度为1450℃、氧化脱硫时间为30 min、还原熔炼温度为1300℃、还原熔炼时间为90 min、Na_(2)CO_(3)添加量为5%、CaO与SiO_(2)质量比为0.5、Fe与SiO_(2)质量比为0.6、还原剂添加量(即C与Cu物质的量比)为1.2的条件下,脱硫率达到99.41%,铜回收率为96.89%,熔渣中铜的质量分数<0.50%,铜产品品位为90.08%。

To clarify the transformation behaviors of the main elements during the smelting process of copperbearing electroplating sludge(CBES),thermodynamic calculations were carried out by FactSage 8.0.An oxidative desulfurization-reduction smelting process for recycling copper-bearing sludge was proposed,and the influence of various factors on sulfur removal rate and copper recovery were discussed.The results show that most of the copper combines with sulfur to form matte when CBES is directly subjected to reduction smelting.Through oxidative smelting,the sulfur in the sludge can be effectively removed,and high-grade copper products with lowsulfur content can be produced.The presence of iron oxides and silicon oxides can significantly reduce the temperature requirement for desulfurization.The following are the optimum conditions:desulfurization temperature of 1450℃,desulfurization time of 30 min,reduction temperature of 1300℃,reduction time of 90 min,Na_(2)CO_(3)addition amount of 5%,mass ratio of CaO to SiO_(2)of 0.5,mass ratio of Fe to SiO_(2)of 0.6,and reductant addition(i.e.,amount of substance ratio of C to Cu)of 1.2.Under these conditions,the sulfur removal rate is 99.41%,the copper recovery rate is 96.89%,the copper content in the residue is less than 0.50%,and the copper grade of the product is 90.08%.