鉛バッテリースライムの湿式処理プロセス

抄録

The feasibility of a new hydrometallurgical treatment process of battery slime was investigated. The process is composed of stages of the selective dissolution of PbSO₄, the recovery of PbCO₃ and the reductive leaching of PbO₂. In this study, the process is discussed from a thermodynamic and a kinetic aspect based on the experimental results obtained on the leaching rates, the stoichiometry of the reactions and the X-ray diffraction analysis of the reaction products.
The main results are summarized as follows:
(1) The dissolution rate of PbSO₄ in the solutions of DETA and CH₃COONH₄ is fast at the initial stage of the leaching, after which the rate decreases with increasing time. The solubility of PbSO₄ increases with increasing concentration of leachants, and the solubility in DETA solution is about 10 times as large as that of CH₃COONH₄ solution. However, PbO₂ is not reactive in the solutions of DETA and CH₃COONH₄, and thus a hydrometallurgical treatment based on the selective leaching of PbSO₄ from the battery mud is possible.
(2) The precipitation rate of PbCO₃ with Na₂CO₃ from the solutions of DETA and CH₃COONH₄ containing lead ions is very fast at the initial stage of the reaction, and then the rate decreases with increasing time. The precipitation rate of PbCO₃ increases with increasing molar ratio of PbSO₄/Na₂CO₃. Under the optimum conditions, PbCO₃ recovery of 94% can be obtained in less than 1.8 ks at ambient room temperature.
(3) The conversion rate of PbO₂ to PbSO₄ with SO₂ gas under the acidic condition increases with increasing partial pressure of SO₂ gas and with increasing temperature of the solution, and the rate is very fast. From the experimental studies and thermodynamic consideration, it is concluded that the hydrometallurgical treatment of lead battery slime is possible.