Recovery Of Lead From Waste Lead-acid Batteries By Desulfurization And Crystallization After Acid Leaching

Lead-acid batteries,as a kind of energy storage equipment with a long history and mature technology,have played an indispensable role in daily life.Lead mineral resources are increasingly scarce,and waste lead-acid batteries contain a large amount of lead,so it is extremely urgent to recover lead from waste lead-acid batteries.At the same time,the unreasonable disposal of waste lead-acid batteries will cause environmental pollution and endanger human health.Realizing reasonable and efficient harmless recycling of waste lead-acid batteries has environmental significance and economic value.Taking the waste lead paste in the waste lead-acid as research object,this thesis used the method of desulfurization and crystallization after acid leaching to recycle the lead-acid batteries in the form of Pb O.In this research,first of all,the lead-acid batteries were disassembled manually,the positive and negative lead paste materials were preprocessed and analyzed respectively,so that the main components of lead paste can be clearly understood.The positive and negative lead paste was recycled by classified acid leaching to explore the optimal acid leaching concentration of the negative lead paste.The optimal hot acid leaching temperature condition of the positive lead paste was calculated by the thermodynamic activation energy,and the optimal sulfuric acid concentration of hot acid leaching was further explored by experiments.Then the waste lead-acid battery was recycled in the form of Pb O through the method of desulfurization and crystallization.In this research,the energy consumption and the amount of acid leaching waste liquid can be reduced by classifying acid leaching method.At the same time,recycling lead in the form of Pb O can shorten the process and providenew ideas and theoretical basis for hydrometallurgical recycling processes.The main conclusions of this thesis are as follows:1.There was a large difference in the content of PbO₂ that was difficult to recycle in the positive and negative lead paste of the waste lead-acid battery.Using the method of positive and negative lead paste classification and acid leaching can more effectively save energy and recycle the waste lead paste,and the use of sulfuric acid can be also reduced.2.The negative lead paste can convert lead element and lead oxides into lead sulfate at room temperature（25℃） through sulfuric acid with a mass fraction of 85%,and the conversion rate is 91.34%;the positive acid lead paste at 65℃ can be used to convert lead element and lead oxides into lead sulfate.The sulfuric acid concentration was selected as the mass fraction of 85%and the conversion rate was 95.69%.And some impurities in lead paste can be removed by acid leaching.3.During the desulfurization and crystallization process,the solid-liquid ratio,the residual liquor and the Na OH concentration all had a significant effect on the recovery efficiency of Pb O,but had little effect on the recovery purity.Through optimization experiments,the optimal conditions for desulfurization and crystallization were 90 g?L^-1 of solid-liquid ratio,42 ml of the residual liquor,and 8.24 mol?L^-1of NaOH concentration.The recovery rate under this condition was 95.72%,and the recovery purity under this condition was 95.31%.4.The kinetics of the crystallization process was studied,and the induction period was 20.77 min.The minimum nucleation particle size of PbO was 1.75nm and the rate was 0.41 g/min.During the crystallization process,every 80 g of PbSO₄ can be generated Mass is 59.06 g5.During the crystallization process,with different Na OH concentrations,the form of Pb O recycled was different,and the color is changed from light yellow to orange to red.With the increase of Na OH concentration,β-Pb O is gradually converted toα-Pb O.α-Pb O is more stable thanβ-Pb O under the condition of strong base.