Separation And Recovery Of Lead Compounds From Dissolved Residue After Waste CRT Glass Generating Sodium Silicate

With the upgrading of electronic display technology, a large number of cathode ray tube(CRT) has been eliminated, CRT glass contains large amounts of metallic lead, if not handled properly, it will cause great harm to the environment and human health. Lead in CRT glass also has a great recovery value at the same time, therefore, how to correctly handle and disposal of waste cathode ray tube has become a pressing environmental problems. In this paper, we based on process route of using waste CRT leaded glass melting into sodium silicate frit and sodium silicate frit dissolution, then get the dissolved residue in sodium silicate frit dissolution step. Separation and recovery lead compounds by optimizing condition of dissolution and floating separation of residue.For better realize the separation of lead compounds in dissolution residue, in the process of optimizating dissolved conditions, dissolution temperature(system self-built pressure) 、holding time and dissolving methods exert on dissolution effect were studied. Through electronic scanning electron microscopy(SEM) and element analysis, we have already got: when adding Na2S?9H2O dissolved, the dissolution temperature was 250℃, the system self-built pressure was 4.0MPa, holding time was 2h, the effect of dissolved sodium silicate frit was best. From microstructure of dissolved residue, we can see the tiny group particles and tiny stick crystals, the silicate and lead compounds have obvious separation.Using flotation method to separation and recovery the lead compounds in dissolved residue, we have researched the five single factors(density of pulp, p H of pulp, addition of sodium ethylxanthate, additive quantity of terpenic oil and flotation time) influence on the flotation recovery. Through analysis and calculate of the experimental data, the experimental results showed that the optimum conditions were: pulp density was 35%, p H value was 8, ethylxanthate dosing was 0.45 g/L, additive quantity of terpenic oil was 1.5 ml/L, flotation time was 10 min, the lead compound flotation recovery can reach 47.44%.We have researched three different collectors influence on the flotation effect. When the dosing quantity of sodium ethylxanthate, sodium butylxanthate, and aniline aerofloat were 0.45 g/L, 0.60 g/L, 0.75 g/L, the highest of flotation recovery rate were 44.72%, 37.78% and 34.21% and the optimum p H value were 8, 9, 10, respectively. We chose orthogonal experiment to research the relationship between dosing quantity of three collector and p H value, we have already got: when the ethylxanthate at the condition of the p H value was 8, dosing quantity was 0.45 g/L, the flotation recovery rate was 46.02%; when the butylxanthate at the condition of the p H value was 9, dosing quantity was 0.60 g/L, the flotation recovery rate was 44.89%; when the aniline aerofloat at the condition of the p H value was 10, dosing quantity was 0.75 g/L, the flotation recovery was 42.36%.Using the S-4800 scanning electron microscopy(SEM) and X-ray diffraction(XRD) to determined the lead compounds from the flotation, we can get the lead content was 65.80% in the lead compounds from flotation, the microstructure has the typical characteristics of galena crystal, EDX and XRD analysis shown that the lead compounds from flotation was Pb S. The chemical composition(Pb S) of recycled waste CRT glass meets the standard of level four or above of lead concentrate in YS/T319-2013, it can be returned to lead metallurgy, and realized the lead source recycling.