(中南大學 冶金與環(huán)境學院，長沙 410083)
摘 要: 根據(jù)物料平衡和電荷平衡原理，對Pb(Ⅱ)-Ac--H+-H2O體系進行熱力學分析，分析結(jié)果表明在接近于實際浸出液的pH值范圍內(nèi)，溶液中PbAc+平衡濃度最高。以濕法煉鋅產(chǎn)出的硫酸鉛渣為原料，采用單因素實驗法優(yōu)化“乙酸鹽配位浸出-隔膜電積提取鉛”的主要工藝條件，采用單因素試驗法優(yōu)化乙酸鉛溶液隔膜電積工藝條件，采用線性掃描、循環(huán)伏安等電化學測試手段研究Pb(Ⅱ)-Ac--H2O體系鉛電積過程中陰極電化學行為。結(jié)果表明：在反應(yīng)時間1 h、浸出溫度70 ℃、乙酸銨濃度4 mol/L、液固比4:1的優(yōu)化條件下浸出硫酸鉛渣，鉛浸出率93.28%。在電積溫度30 ℃、Pb2+濃度50 g/L、電流密度100 A/m2的條件下陰極電流效率98%左右，每噸Pb直流電耗約700 kW？h。在此條件下以硫酸鉛渣浸出液直接作為電積液隔膜電積8 h在陰極可以獲得純度99.2%較為致密平整的電鉛，陰極電流效率96.16%。鉛的還原沉積過程是一個不可逆過程，鉛在電沉積初期遵循三維連續(xù)成核與顆粒長大機制，升高溫度和提高陰極液Pb2+濃度可以促進溶液離子擴散，提高電流效率。
關(guān)鍵字: 硫酸鉛渣；乙酸鹽體系；配位浸出；隔膜電沉積；電化學機理
（School of Metallurgy and Environmental, Central South University, Changsha 410083, China）
Abstract:According to the theory of material balance and charge balance, the thermodynamic analysis of Pb(Ⅱ)-Ac--H+-H2O system was carried out. The conclusion is that the equilibrium concentration of PbAc+ in solution is the highest in the range of pH value close to the real leach solution. Using lead sulfate residue as raw material, the optimum conditions of this process were obtained by single factor experiment. The optimum conditions and experimental results of leaching are finally determined as follows: temperature of 70 ℃, reaction time of 1 h, ammonium acetate concentration of 4 mol/L, the ratio of liquid to solid of 4:1. The leaching efficiency of lead is 93.28%. The optimum conditions and experimental results of membrane electrodeposition are finally determined as follows: temperature of 30 ℃, Pb2+ concentration of 50 g/L, current density of 100 A/m2. The cathode current efficiency could reach 98%, the DC power consumption is 700 kW？h per ton Pb. When electrowinning with selective leaching solution under the optimal process conditions, and a relatively compact and flat lead can be obtained at the cathode with a purity of 99.2%, and the current efficiency of the cathode is 96.16%. The electrochemical behavior of lead electrodeposition was investigated. It is an irreversible reaction of lead membrane electrodeposition; the initial process of lead electrodeposition follows the diffusion controlled three-dimensional nucleation and grain growth mechanism; ion diffusion rate and current efficiency are improved by the increase of temperature and concentration of Pb2+.
Key words: lead sulfate residual; coordination leaching; membrane electrodeposition; acetate system; electrochemical mechanism
