Removal of lead from cathode ray tube funnel glass by generating the sodium silicate

Abstract

In the disposal of electronic waste, cathode ray tube (CRT) funnel glass is an environmental problem of old television sets. Removal of the lead from CRT funnel glass can prevent its release into the environment and allow its reuse. In this research, we reference the dry progress productive technology of sodium silicate, the waste CRT glass was dealt with sodium silicate frit melted and sodium silicate frit dissolved. Adding a certain amount of Na2CO3 to the waste CRT glass bases on the material composition and content of it, then the specific modulus of sodium silicate frit is obtained by melting progress. The silicon, potassium and sodium compounds of the sodium silicate frit are dissolved under the conditions of high temperature and pressure by using water as solvent, which shows the tendency that different temperature, pressure, liquid-solid ratio and dissolving time have effect on the result of dissolving. At 175°C(0.75MPa), liquid-solid ratio is 1.5:1, the dissolving time is 1h, the dissolution rate of sodium silicate frit is 44.725%. By using sodium sulfide to separate hydrolysis solution and to collect lead compounds in the solution, the recovery rate of lead in dissolving reached 100% and we can get clean sodium silicate and high purity of lead compounds. The method presented in this research can recycle not only the lead but also the sodium, potassium and other inorganic minerals in CRT glass and can obtain the comprehensive utilization of leaded glass.Implications:Waste cathode ray tube (CRT) funnel glass has become a serious environmental problem throughout the world. However, some techniques in the processing of CRT waste have disadvantages such as low lead recovery, low level of comprehensive utilization, technical constraint, economic costs, and other factors, so the actual practical application is still not possible. Therefore, in order to solve lead pollution existing in the waste CRT glass and to solve resource utilization problems, it is necessary to develop a waste CRT process technology that is friendly to environment, cost-saving, and feasible.