铅阳极泥碱性加压氧化浸出脱砷过程中As−N−Na−H2O系的φ−pH图

摘要

为阐明砷在铅阳极泥碱性加压氧化浸出过程(NaNO3为氧化剂;NaOH为碱性试剂)中的热力学特性,通过热力学计算绘制体系离子质量浓度为0.1 mol/kg,温度为298、373、423和473 K条件下的As?Na?H2O、N?H2O和As?N?Na?H2O系的φ?pH图.结果表明,砷的存在形态与pH值有关.当pH值较低时,砷主要以H3AsO4、24H AsO?、24HAsO?、22H AsO?及As2O3的形式存在;当pH>11.14时,砷主要以34AsO?形式存在,高碱浓度及高温对砷浸出有利.碱性加压氧化浸出实验表明,砷浸出率变化趋势与As?N?Na?H2O系φ?pH图的热力学分析结果一致,在453 K时砷的最佳浸出率为95.85%.%In order to illustrate the thermodynamic characteristics of arsenic during alkaline pressure oxidation leaching process of lead anode slime (NaNO3as oxidant; NaOHas alkaline reagent), theφ?pH diagrams of As?Na?H2O, N?H2O, As?N?Na?H2O systems at ionic mass concentration of 0.1 mol/kg and temperatures of 298, 373, 423 and 473 K were established according to thermodynamic calculation. The results show that the existence forms of arsenic are associated with pH value, which mainly exists in the forms of H3AsO4,24HAsO?,24HAsO?,22HAsO? and As2O3 in lower pH region, while it mainly exists in the form of34AsO? when pH>11.14. High alkali concentration and high temperature are advantageous to the arsenic leaching. The alkaline pressure oxidation leaching experiments display that the tendency of arsenic leaching rate confirms the thermodynamic analysis results obtained from theφ?pH diagrams of As?N?Na?H2O system, and the highest leaching rate of arsenic reaches 95.85% at 453 K.