Study on Low-Temperature Vacuum Carbothermal Reduction of High-arsenic Copper Dust in Copper Fire Refining Furnace for Arsenic Removal
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摘要: 以铜火法精炼炉高砷铜烟尘为原料,采用低温真空碳热还原法对烟尘中As进行脱除处理。通过TGA-DSC对原料进行差热分析,借助于XRD、ICP、SEM等分析手段分别对烟尘和蒸发残渣的物相、化学成分和形貌等进行了分析,在热力学分析的基础上,研究了蒸发温度、残压、还原剂量、蒸发时间等对As及其他有价金属脱除率的影响。结果表明,当蒸发温度为350℃、残压为100 Pa、还原剂量为25%和蒸发时间为50 min时,在保证其他金属基本上不蒸发的同时,As的去除率可达81.63%,实现了As及其他有价金属的选择性分离。蒸发物为纯度较高的As2O3,可以作为初级As2O3产品使用。有价金属在蒸发残渣中得到富集,便于后续的废酸浸出工艺回收。Abstract: Using the high arsenic copper dust from the copper fire refining furnace as the raw material, the low-temperature vacuum carbothermic reduction method is used to remove As from the dust. Differential thermal analysis of the raw materials was carried out by TGA-DSC, and the phase, chemical composition and morphology of the dust and evaporation residue were analyzed by XRD, ICP, SEM and other analytical methods. On the basis of thermodynamic analysis, the effect of evaporation temperature, residual pressure, reducing dose, evaporation time, etc. on the removal rate of As and other valuable metals. The results show that when the evaporation temperature is 350℃, the residual pressure is 100 Pa, the reducing amount is 25%, and the evaporation time is 50 min, the removal rate of As can reach 81.63% while ensuring that other metals do not evaporate basically, realizing As Selective separation of other valuable metals. The evaporate is As2O3 with higher purity, which can be used as primary As2O3 product. Valuable metals are enriched in the evaporation residue, which is convenient for the subsequent recovery of the waste acid leaching process.
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表 1 铜火法精炼炉高砷铜烟尘ICP成分分析/%
Table 1. ICP composition analysis of the high arsenic copper dust from the copper fire refining furnace
Cu As Zn Pb S Sn Sb Se K Fe Ca Ni Zr Cr 19.80 14.41 8.84 9.50 2.28 1.22 0.94 0.77 0.42 0.32 0.04 0.04 0.04 0.34 表 2 还原过程可能发生的反应
Table 2. Possible reactions during the reducing experiment
反应类型 反应式 编号 直接还原反应 C+O2(g)=CO2(g) (1) C+CO2(g)=2CO(g) (2) 1/4ZnSO4+C=CO(g)+1/4ZnS (3) 1/4PbSO4+C=CO(g)+1/4PbS (4) CuO+C=CO(g)+Cu(s) (5) 2CuO+C=CO(g)+ Cu2O(s) (6) Cu2O+C=CO(g)+2Cu(s) (7) As2O5+2C=As2O3(g)+2CO (8) As2O3+3C=2As(s.g)+3CO (9) 间接还原反应 1/4PbSO4+CO(g)=CO2(g)+1/4PbS (10) 1/4ZnSO4+CO(g)=CO2(g)+1/4 ZnS (11) CuO+CO(g)=CO2(g)+Cu(s) (12) Cu2O+CO(g)=CO2(g)+2Cu(s) (13) As2O3(s.g)+3CO=2As+3CO2(g) (14) As2O5+2CO(g)=As2O3(s.g)+2CO2 (15) 其他反应 4As(s)=As4(g) (16) 4As(g)=As4(g) (17) As2O5=As2O3(s.g)+O2 (18) 2ZnSO4=O2+2ZnO+2SO2(g) (19) 2PbSO4=O2+2PbO+2SO2(g) (20) 表 3 蒸发物As2O3与蒸发残渣的化学成分/%
Table 3. Chemical composition of As2O3 and residue
名称 As Cu Pb Zn 蒸发物 72.78 0.013 - 0.0216 蒸发残渣 3.29 25.06 11.41 10.78 -
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