阳极泥中铜的常压氧化预脱除及动力学分析

Pre-removal and kinetic analysis of copper from anode slime by oxidation at atmospheric pressure

铜阳极泥富含金、银、铂、钯等贵金属和硒、碲等稀散金属,是稀贵金属提取的重要原料。然而,由于某铜阳极泥中铜含量大于10%,过多的铜会增加后续贵金属回收时浸出剂的消耗量,并严重影响金银的收得率,需预先脱除。本文在热力学分析及XRD、SEM-EDS等表征手段基础上,常压下于H_(2)SO_(4)介质中以MnO_(2)为氧化剂,对阳极泥进行预脱铜研究。分别考察了H_(2)SO_(4)浓度、MnO_(2)加入量、浸出时间、液固比、反应温度等因素对阳极泥中铜浸出率的影响,同时采用收缩未反应核模型对铜浸出过程进行动力学分析。结果表明:铜浸出过程的反应速率受扩散控制,其表观活化能为4.1kJ/mol,在初始H_(2)SO_(4)体积浓度为100g/L,MnO_(2)质量浓度为10g/L,浸出时间为120min,液固比为4∶1(单位:mL/g,下同),反应温度为80℃的条件下,铜的浸出率可达92.19%;同一条件下,部分砷、硒也被浸出,其浸出率分别维持在28%和13%左右。

Copper anode slime,rich in precious metals(gold,silver,platinum and palladium)and rare metals(selenium and tellurium),is an important raw material for the extraction of rare precious metals.However,a certain anode slime contains more than 10%of Cu,and the excessive copper may increase the consumption of leaching agents in the subsequent precious metal recovery and thus seriously affect the recovery ratio of gold and silver,which needs to be removed in advance.Based on thermodynamic analysis,XRD,SEM-EDS and other characterization methods,pre-removal of copper from anode slime was carried out at normal pressure in a sulfuric acid medium with MnO_(2) as the oxidant.The effects of H_(2)SO_(4) concentration,MnO_(2) addition,leaching time,liquid-solid ratio,reaction temperature and other factors on the copper leaching ratio of anode slime were investigated,respectively.Furthermore,the kinetics of the copper leaching process were analyzed according to shrinking unreacted core model.The results show that the reaction rate of copper leaching process is controlled by diffusion,with an apparent activation energy of 4.1 kJ/mol.Under the conditions of initial H_(2)SO_(4) concentration of 100 g/L,MnO_(2) concentration of 10 g/L,leaching time of 120 min,liquid-solid ratio of 4:1,reaction temperature of 80°C,the leaching ratio of Cu can reach 92.19%.Under the same conditions,part of arsenic and selenium are also leached,and the leaching ratios are maintained at about 28%and 13%,respectively.