Separation And Recovery Of Yttrium In Waste CRT Phosphors

With the national focus on sustainable exploitation of resources,the recycling and utilization of resources has gradually become one of the important topics of researchers.In the electronic products represented by the CRT?Cathode Ray Tube?,CRT displays have been replaced by a large number of new products as the electronic technology continues to advance.The following problems have arisen:?1?Random stacking and disintegration cause serious environmental pollution;?2?There are many metal resources in the accessories that are discarded and wasted.Especially the rare earth metal-yttrium?Y?contained in waste CRT phosphors.Therefore,this work has been studied for the separation and recovery of Y from waste CRT phosphors.The recovery effect of Y in waste CRT phosphors was studied by the process of acid leaching-precipitation;Preparation of adsorbed silica gel,evaluate its adsorption performance for Y³⁺and apply it to the recovery of Y in waste CRT phosphors.Details are as follows:?1?Literature review:From the research status and development of CRT,the classification and composition of CRT phosphors,research background and recovery methods of waste CRT phosphors,including fluorescent lamp phosphors and other methods of leaching and separation of phosphors were compared and reviewed.?2?The acid leaching-precipitation method was used to investigate the recovery of ruthenium in waste CRT phosphors.That is,the yttrium oxide is obtained by the acid leaching-purification-precipitation-calcination process.First,optimized by acid leaching conditions?acid concentration,time,temperature?,with 5 mol·L^-11 HCl as the extract,the solid/liquid ratio was 1:50?m/v,g/mL?,and the mixture was stirred at 100°C for 6 h,and the leaching rate was 91.8%.Then,the Zn²⁺in the acid leaching solution was removed by 1,10-Phenanthroline,and the process was completed with 1:1.2?m/m,g/g?.After the impurity is removed,the rare earth oxalate is formed by precipitation with oxalic acid,and calcined to form yttrium oxide.By precipitation and calcination conditions were optimized,and reports according to various factors,choose an excess of 10%?based on the amount of rare earth element?oxalate precipitate. Yttrium oxide was formed by calcining at 900?for 2 h.Finally,the purity of yttrium was 92.6%?0.35%zinc?and the recovery was 79.8%.?3?According to the principle of hydrazine-based olefins,preparation of two carboxyl group-containing silica with 3-Mercaptopropionic acid?3-MP?/DL-Mercaptosuccinic acid?DMSA?as ligand?3-MP-silica/DMSA-silica?.Characterization by Fourier Transform Infrared Spectrometer?FT-IR?and X-ray photoelectron spectroscopy?XPS?confirmed that 3-MP/DMSA was successfully bonded to the surface of silica.In3-MP-silica/DMSA-silica adsorbent as a weak cationic,and the carboxyl silica is used as an adsorbent for waste CRT phosphor recovery.At the same time,Inductive Coupled Plasma Emission Spectrometer was used to quantitatively analyze the changes of all metal ions in the experiment.In the experiment,the adsorption properties of adsorbent on Y³⁺and Zn²⁺were investigated by using standard Y³⁺and Zn²⁺,and the adsorption parameters were optimized,including pH,time,saturated adsorption and elution conditions.The adsorbent Y³⁺and Zn²⁺,of the maximum adsorption capacity was30.30?g·mg^-1,3.683?g·mg^-1,respectively.Then applied to the actual waste CRT phosphor,the adsorption rate of Y³⁺and Zn²⁺in the acid leaching solution was 75.0%,17.1%.