Lead Brass Removal Mechanism And Process Research

Due to its hot and cold processing and excellent cutting performance,good selflubrication,meeting finishing of various shapes materials,lead brass is widely used in all areas of life.But the lead in brass lead easily deposited in the form of solid or gaseous entering into the environment and constantly enriched,which seriously pollute the environment and endanger human health.Therefore,countries have enacted restriction on the use of lead-containing copper alloy.Japan and the United States issued a decree:After 2006,the amount of lead leaching in water pipes decreased from 0.05mg/L to 0.01mg/L.China has also introduced the relevant regulations to strictly limit the use of lead and other hazardous substances.Given the use of lead-containing copper alloys restrictions.A large number of discarded leaded brass in China every year need to removal lead and impurities for environmental recycling.Therefore,it is of great significance that carrying out the lead removal mechanism and process study on leaded brass to promote green recycling of waste leaded brass.Leaded brass is the research object in this experiment.Using metallurgical thermodynam-ics and dynamics theory explored the lead removal mechanism and feasibility about leaded brass;adopting the thermodynamics calculation of Factage simulation and experimental studied lead removal process and the effect on leaded brass.By using optical microscopy(OM),scanning electron microscopy(SEM),energy spectrum analysis(EDS)and X-ray diffraction(XRD)or other testing methods,we analyze the detection results.Comparing simulation analysis and experimental result,he following conclusions are obtained.The main research contents and results are as follows:(1)After the theory thermodynamic and dynamics analysis of lead removal mechanism about leaded brass,we made a persuasive study on the feasibility of lead removal test in the theory.(2)In the case of fully reaction,the Gibbs free energy of 1mol of Ca and Pb?Cu?Zn?Mg in lead brass was calculated through Fact Sage thermodynamic simulation.Simulation results show that Ca and Pb hold the lowest Gibbs free energy,add Cu-Ca?Mg-Ca alloy can form Ca-Pb compound with high melting point,low density and Pb,floating in the adsorption of Na F,achieve the purpose through the slag removing lead.in Cu-Ca system,when the addition of Ca increased to 2.5Wt.%,the lead removal rate has reached 99.7%.In Mg –Ca system,when the amount of Ca reached 3.2Wt.%,the lead removal rate reached 99.8%.(3)The experiment studied on lead removal process in Brass and the effect of Ca elements on lead removal.With the increase of addition amount of Ca,Pb removal rate in leaded brass was increased at first and then changed gently,in Cu-Ca system,good effects of removing lead are founded when added 2.5Wt.%Ca,Pb removal rate of the best.There are best effect of lead removal when the addition of Ca in the Mg-Ca system is 3.2Wt.%,and the ? phase increased,? phase decreased with the increase of the content of Mg.The ? phase structure of the alloy shows the change of being thin first and being enlarged and being thin again.(4)The factors that the influence of test results are optimized by orthogonal test to determine the optimal level of each factor.Orthogonal optimization test results showed that the best of lead removing rate reached 86%,holding temperature of the error mean square is less than the error column of error mean square,so the holding temperature can be classified as a list of errors.By the means of scanning electron microscopy,energy spectrum analysis and XRD analysis,the residual lead in brass(0.45 Wt.%)is formed into stable compounds in Ca-Pb alloy and Reduce the harm of Pb.