Recycling Indium And Tin From Electronic Waste Water

Main application fields of indium tin oxide(ITO)is to produce liquid crystal displays,and the main component of ITO,indium,is very rare in the crust.Indium belongs to scare metal.With the development of the electronics industry as well as the over exploitation of native indium resources,and a further increase in demand for indium.Many countries list it as a strategic resource,therefore,the development of indium secondary resources becomes particularly important.In the production process of a liquid crystal display,in order to etch a pattern on the ITO glass substrate,it will generate a lot of etching waste water.The waste water has the characteristics of high acid content and high recovery value of metal ions.If the etching waste water is discharged by us directly,it will not only cause environmental pollution but also waste the valuable resources.As the indium resource is going to increasingly short,recycling indium and tin from the ITO etching will have a great significance.With the ITO etching waste water as studying object,the recycling technology from the etching waste water has been studied in the dissertation.First,dealing with ITO etching waste water by means of precipitation method,introducing the advantages and disadvantages of precipitation and describing the experimental phenomena.The experimental results showed that the recovery rate of dealing with ITO etching waste water by means of precipitation was very high,which the recovery rate of indium ions was 99.9% and the recovery rate of tin ions was96.6%.Secondly,dealing with ITO etching waste water by means of extraction method,introducing the advantages and disadvantages of the extraction method.Selecting three common extraction agents,which used in the extraction of indium and tin,namely,P204,P507 and TBP.And picking out the suitable extraction agent for ITO etching waste water was P204 by the qualitative point of view,and the reverse extraction experiment of P204 had been made,too.The experimental results showed that,the single factor experiment and orthogonal experiments of P204 pointed out the optimum process of dealing with ITO etching waste water by means of extraction method was that the extraction agent / diluent was 3/7;mixing time was 5 minutes;oil-water ratio(A / O)was 7/1,temperature was 30?.At the optimum conditions,the extraction efficiency of indium ions was 99.14%,the extraction efficiency of tin ionswas 76.68%.However,as the efficiency of reextraction was low,the total recovery of indium was about 85% and the recovery rate of tin was only about 15% through estimate.Finally,dealing with ITO etching waste water by means of chelating resin,introducing the advantages and disadvantages of chelating resin.By comparison of the three types of chelating resin,which used for adsorbing metal ions,and picked out of a suitable chelating resin for indium ions and tin ions.The experimental results showed that the recovery rate of dealing with ITO etching waste water by means of chelating resin was very high,which the recovery rate of indium ions was 99.5% and the recovery rate of tin ions was also 96.2%.Through the desorption,which the indium and tin could be recycled from the waste,and the desorption efficiency was very high,the total recovery of indium and tin was more than 95%.In addition,there would be less waste and less follow-up treatment cost through this method.