Study On Wet Separation Process Of Lead From Waste CRTs Cone Glass Assisted By Mechanical Activation Strengthening Chelating Agent

With the rapid development of imaging technology,cathode ray tubes(CRTs)are gradually being replaced by thinner and lighter flat panel displays,such as liquid crystal displays,plasma displays,and light emitting diode displays.Waste CRTs contain a variety of toxic and hazardous substances,especially lead,whose content is as high as about 20%.if they are not properly treated,they will pose a serious threat to the environment and human health.This paper firstly discusses the latest research progress in the treatment and disposal of waste CRTs at home and abroad,and proposes a green leaching process route for the separation of lead from waste CRTs glass with the aid of mechanically activated reinforced chelating agent,i.e.,adding different proportions of chelating agent to mechanically activate the pretreatment of waste CRTs cone glass and cooperating with organic acid wet leaching or wet spherical leaching.Mill leaching of lead in the glass;the leaching characteristics,patterns and leaching reaction mechanism of lead in waste CRTs cone glass were discussed and analyzed in depth.It provides a feasible technical route and data support for solving the environmental risk and resource recycling of waste CRTs glass.In this study,firstly,the composition analysis,morphology and crystal structure were observed and analyzed for the sample system of waste CRTs cone glass,and the experiments were carried out by using environmentally friendly organic acids(citric acid,tartaric acid,acetic acid)and chelating agents(NTA,Na2EDTA,GLDA)for the wet leaching of organic acids and wet ball milling for the leaching of lead in acidic and alkaline environments of waste CRTs cone glass.The effects of mechanically activated chelating agent addition ratio,organic acid type and concentration,liquid-solid ratio,leaching time,chelator/calcium carbonate to cone glass sample mass ratio,wet ball milling time,ball material ratio,and ball mill rotation speed on the leaching effect of lead from waste CRTs cone glass were studied and investigated.The main results were as follows.1.In organic acid wet leaching experiment,50%NTA mechanical activation for 12h was added to the waste CRTs conical glass as experimental sample,0.5mol/l citric acid as leaching agent,liquid-solid ratio 30:1(L/Kg),spherical material ratio 30:1(g/g),rotating speed 450(r/min),leaching for 12h,the leaching rate of lead reached 47.64%.2.In the experiment of separating waste CRTs cone glass lead in wet ball milling under acidic environment,50%NTA mechanical activation of 12h waste CRTs cone glass was added as experimental sample,m(NTA:CRTs)=1:1(g/g),L/S=30:1(L/Kg),ball material ratio is 30:1(g/g),ball mill speed 400(r/min),wet ball milling for 12h.The leaching rate of lead was 87.41%.3.Wet ball mill in alkaline environment to separate waste CRTs cone glass lead experiment,add 50%NTA mechanical activation of 12h waste CRTs cone glass as experimental samples,m(CaCO3:CRTs)=1:2(g/g),L/S=30:1(L/Kg),ball material ratio of 30:1(g/g),ball mill speed 400(r/min),wet ball mill.For 12 h,the leaching rate of lead reached 43.13%.The experimental data show that both dry and wet ball milling of materials can effectively improve the leaching of lead from waste CRTs conical glass,the improvement of lead leaching rate mainly depends on the disintegration of the glass grid in waste CRTs conical glass,as well as the chelating effect of chelating agent,wet ball milling process,adding the same ratio of chelating agent,the effect of lead leaching:NTA>Na2EDTA>GLDA,and the secondary mechanical activation of wet ball milling.Enhances the leaching of lead by the leaching agent.