| Lead-acid battery is widely used in the field of traffic and communication because of its stable voltage,large discharge,long life and high cost performance.A large number of waste lead-acid batteries are produced after the lead-acid battery is discarded.The main components of the lead-acid battery are harmful to the environment and affect human health.And the production of lead and primary lead-mine is shrinking.Lead-acid batteries account for the largest proportion of lead in various lead products.Therefore,it is imperative to recycle waste lead paste from waste lead-acid batteries.In this study,the main components and contents of the waste lead paste and its discharge mechanism are studied through the detection and analysis.Then the best condition of leaching is explored by leaching the lead in the waste lead paste by NaOH solution,and the kinetic analysis of the leaching process is carried out.Then the amount of current density,temperature,additives and additives in the electrolysis process is explored by electrolysis recovery of lead.The effects of lead recovery,lead purity,current efficiency,energy consumption and physical properties of lead were studied.The results show that NaOH leaching-electrolysis system can recover lead with high purity and high quality from waste lead paste,and the physical properties of lead products can be improved by adding appropriate additives in the process of electrolysis.The main results are as follows:The main components of the positive and negative pole of the waste lead paste are PbSO4,PbO,PbO2 and Pb.The main components of the waste lead paste after full discharge are PbO4 and PbO2.The specific gravity of total lead and impurity in waste lead paste decreased after discharge,which is due to the transformation of lead and its oxides into lead sulfate during the discharge of sulfuric acid,and the removal of some impurities at the same time.The optimum leaching conditions for leaching of waste lead paste with NaOH solution were as follows:the leaching time was 33 minutes,the temperature was 75 ?,the concentration of NaOH was 7 mol·L-1,the solid-liquid ratio was 43 g·L-1,and the lead leaching efficiency was 56.35%and the leaching concentration was 17.33 g L-1.The main composition of the residual solids after leaching under the optimum conditions was PbO2,which can be further purified and directly utilized.Based on the basic kinetic analysis of the main reaction time,the main leaching process of lead paste in NaOH solution is diffusion control.The recovery of lead was the highest when the electrolytic current density was 40 mA cm-2.The recovery efficiency of lead increases with the increase of electrolysis time,but the increasing speed gradually slows down.The lead purity obtained under different current density was close to the 100%.Current efficiency decreases with the increase of current density and time.The specific energy consumption increases with the increase of current density,and increases with time.The larger the current density,the thinner and more dispersed the lead crystal is,and the more uniform the size is.The recovery of lead is increased with the increase of temperature when the electrolytic temperature was 15?45 ?.At 15 ?,the purity of lead was 98.28%.And the lead purity was close to the 100%,when the temperature was 30 ? and 45 ?.The current efficiency as the temperature rises,and the the specific energy consumption decreases with the increase of temperature.The physical properties of lead crystals obtained at 30 ? were the best.The addition of ammonium sulfonate and sodium alkyl sulfate can improve the physical properties of lead,and obtain more detailed lead.When ammonium sulfonate is added to 0.125 g·L-1,the surface of lead precipitated by electrolysis was smooth,the size of lead crystal was equalized and dispersed,and the lead crystal was ideal.When the content of lead crystal increases gradually,the surface of lead crystal becomes rough and porosity is formed. |
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