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采用湿法炼锌产出的铅银渣作为实验原料,首次提出利用真空碳热还原法处理铅银渣以回收其中的金属铅。系统研究了冷凝产物的物相随还原温度、配碳比及还原剂的种类的变化而变化的基本规律。通过对碳热还原铅银渣的热力学计算可以得出,常压条件下用C直接还原PbSO_4生成金属铅,氧化铅和硫化铅的理论开始反应温度分别为737,829和532K。当系统压力下降至10Pa时,其理论开始反应温度分别下降至504,562和370K。通过实验分别研究不同还原温度,不同配碳比,不同种类还原剂对冷凝产物的影响。实验结果表明:当以石墨作为还原剂,还原温度为700℃,真空度为10Pa,配碳比C/Pb=2,反应时间为30min的条件下,能够获得相对较纯的铅粉。
The lead-silver slag produced by hydrometallurgy was used as experimental material, and the lead-silver slag was treated by vacuum carbothermal reduction for the first time to recover the metallic lead. The basic law of the change of the phase of the condensed product with the reduction temperature, with the carbon ratio and the type of reducing agent is systematically studied. Through the thermodynamic calculation of the carbon-thermal reduction of lead-silver slag, it can be concluded that the theoretical starting reaction temperature of lead, lead oxide and lead sulfide generated by direct reduction of PbSO_4 with C under atmospheric pressure is 737, 829 and 532 K, respectively. When the system pressure drops to 10Pa, its theoretical reaction temperature starts to decrease to 504, 562 and 370K respectively. Experiments were conducted to study the effects of different reduction temperatures, different carbon ratios, and different types of reducing agents on the condensation products. The experimental results show that relatively pure lead powder can be obtained under the conditions of graphite as reductant, reduction temperature of 700 ℃, degree of vacuum of 10Pa, C / Pb ratio of 2 and reaction time of 30min.