Study On Leaching Property Of Lead Mud In Waste Lead-acid Batteries And Its Leaching Condition By Chloride Leaching

The lead is one of metals commonly used by human,its use is very widespread.At present,the raw materials of lead production mainly from lead ore in China,but alot of information shows that our resources are decreasing day by day.Comprehensive utilization and converting into resources of lead in waste is widlyconcerned.At the same time,with the development of the national economy,thelead-acid batteries are widly used in all kinds of business,as a result of that,the waste lead-acid batteries which has become the main source of secondary lead is foucsed on by people.The lead mud regarded as the most complex constituent in the waste lead-acid batteries is listed as the hazardous wastes by "National Hazardous WastesList".If it is dumped randomly,it will cause tremendous harm to the environment,soit is necessary to seek appropriate treatment.The paper takes the lead mud from a dismantling factory as research object,and simulated three different environmental terms with three different extraction solventsto analyze extaction toxicity in them.It studied the leaching kinetics property of lead mud in the system of HCl-NaCl-CaCl₂,and also studied the leaching condition oflead mud in the systerm by the single factor and orthogonal experiment.The experiment results of extaction toxicity showed that the lead mud was typically hazardous waste and had strong extaction toxicity.The strongest extaction toxicity behaved by using the acetic acid method,the next was by using thenitrate-sulfate mixed acid method,the smallest was by using the ionized watermethod.The leaching process of lead mud was liquid to solid chemical reaction in the systerm of HCl-NaCl-CaCl₂.The leaching process was controlled by internaldiffusion,and also accorded to the kinetics model about shrinking the core which was 1-2/3α-(1-α)^2/3=Kt.The apparent activation energy of the leaching process was13.73 KJ/mol.In the system of HCl-NaCl-CaCl₂,the longer the leaching time was,the higherthe leaching rate was;the higher the initial density of NaCl was,the higher the leaching rate was;the higher the ratio of liquid to solid was,the higher the leachingrate was;the higher the leaching temperature was,the higher the leaching rate was;the higher the initial density of the hydrochloric acid was,the higher the leaching ratewas.When the amout of CaCl₂ in the theory range,the leaching rate would increasewith its incease,but the influence was small if the amout of CaCl₂ further increase.When the leaching time and the stirring speed and the size of the particulatematter were fixed in the the system of HCl-NaCl-CaCl₂,the primary and secondaryorder that was influenced by every factors on leaching rate was:[NaCl]⁰>L/S>T>[HCl]⁰>the amout of CaCl₂.