Recovery Of Lead In Sintering Dust From Ferreous Metallurgical Process And Prepartion Of Lead Oxide

As one of the iron and steel solid waste, the EAF dust(hereinafter referred to as sintering ashes) is derived from the flue gas collection of electrostatic precipitator in the technological process of sintering in iron and steel production. Sintering ashes have complex chemical compositions, except iron, some of which contain harmful elements such as potassium, copper, zinc and lead. In this paper, based on the analysis in physical and chemical properties of sintered ash, development of hydrochloric acid- sodium chloride and acetic acid- sodium acetate extraction of lead ash sintering process route.Basic research on physical and chemical properties of sintered ash showed that,lead in the dust exist mainly in the form of PbHCl O and PbO, and the average content of lead is 4.77%. Particle size analysis of sintered ash showed that, the median diameter of 1#, 2#, 3# sintered ash were 39.84 μm, 23.84 μm and 18.34 μm. The specific surface area of 1#, 2#, 3# sintered ash were 19.6 m2/g, 15 m2/g and 17.5 m2/g.Combined with the previous related research, decided to recovering lead by leaching process after water washing and magnetic iron separation.Through the magnetic separation, the content of lead in lead rich mud for9%~12%, using HCl-NaCl mixed solution leaching of lead sintering dust,the results showed that, under the optimum conditions for the leaching process with the leaching temperature range of 85~90 ℃, NaCl concentration of 250 g/L in the leaching system,the amount of industrial hydrochloric acid of 25 mL per 100 g sintering EAF dust, the solid-liquid ratio of the dust to HCl-NaCl solution of 1.0: 3.0 and the leaching time of30 min, the leaching efficiency of Pb from the dust was over 99.50%. With 2 cycles of the crystalled mother liquor, the total recovery of lead could reach to 95.08%. In the conversion of PbCl2 to PbO, the amount of sodium carbonate was 0.90 to 1.0 times of its theoretical amount, at the condition the precipitate yield of lead was 99.90%. By calcining the precipitate at 650 ℃ for 5 h, the lead oxide product was obtained with a purity of 99.50%, which reached the requirement of the first class index in the national standard HG/T 2325-2004, the lead recycling rate was 64.77% of the whole technological process.The lead content of 9%~12% lead rich tail slime of chloride impurity removal,get rich lead mud after chlorination, where Cu、Zn has been basically removed, thecontent of Ca 、Mg is less than 0.2% does not affect the subsequent experiments, lead content remained basically unchanged.Using HAc-NaAc mixed solution leaching of lead sintering dust, the results showed that, under the optimum conditions for the leaching process with the leaching temperature range of room temperature(25 ℃),NaAc concentration of 2 mol/L in the leaching system, the industrial acetic acid concentration of 0.5 mol/L in the leaching system, the solid-liquid ratio of the dust to HAc-NaAc solution of 1.0: 2.0,the leaching time of 30 min and The stirring rate is300r/min, the leaching efficiency of Pb from the dust was over 99.80%.In the conversion of PbCl2 to PbO, the amount of sodium carbonate was 0.90 times of its theoretical amount, at the condition the precipitate yield of lead was 99.90%. By calcining the precipitate at 650 ℃ for 5 h, the lead oxide product was obtained with a purity of 99.60%, which reached the requirement of the first class index in the national standard HG/T 2325-2004.With 5 cycles of the crystalled mother liquor, the total recovery of lead could reach to 99.80%, the lead recycling rate was 67.33% of the whole technological process.According to preliminary estimates, the annual output value of the hydrochloric acid- sodium chloride process could achieve 1.168 million, the annual output value of the sodium acetate process could achieve 2.021 million, which is indicate the highly economic benefits of the two process.