Preparation Of Ultrafine Lead Powder By Using Cyanide Lead Slag From A Silver Mining Enterprise

In this study,the lead-containing tailings from the cyanide chemical section of a silver mine in northwestern Hubei Province is used as raw material,and the lead chloride was leached in the hydrochloric acid-sodium chloride system with manganese dioxide as the oxidant,and the ammonium bicarbonate was used as the precipitant in the later stage.The ultrafine lead powder(PbO)was prepared by precipitation conversion method.The experimental conclusions are as follows:1.Through XRD analysis of lead slag,the main components of lead slag are galena(PbS),sphalerite(ZnS),pyrite(FeS2),quartz(SiO2),etc.,using nitric acid-hydrofluoric acid-Total lead content was determined by wet digestion of perchloric acid,and the total lead content in the lead tailings was 157.9 mg/g.2.Using the two-mine method to recover lead chloride and explore the different solid-liquid ratio,manganese dioxide dosage,reaction time and reaction temperature on the lead leaching rate.The optimal reaction conditions are:reaction solid-liquid ratio 1:10,manganese dioxide dosage m ??:m????=5:1.6,reaction time 60 min,reaction temperature 80?.3.Orthogonal experiment to determine the order of influence of various factors on lead leaching rate:solid-liquid temperature>ratio>time,the best combination shown is:temperature 80?,solid-liquid ratio 1:10,ratio of manganese dioxide dosage For m ??:m????=5:1.5g,the optimal reaction process leaching rate is 97.1%.Through the time-temperature curve,the leaching process of lead-containing tailings is consistent with the shrinking kernel model.The lgk at different temperatures is plotted against T-1,and the lgk is roughly linear with respect to T-1.The data can be obtained by linear regression.The straight line,from the slope of the straight line f=-0.4525,according to the Arrhenius equation(?),it can be seen that F?=-2.303Rf=8.66kJ/mol.5.Using the above lead chloride to prepare ultrafine lead oxide powder,the effects of initial pH,ammonia bicarbonate dosage,reaction time and reaction temperature on the dechlorination rate of the precipitate were investigated.The optimal reaction conditions were as follows:initial pH=10,ammonium bicarbonate dosage 1.5 times,reaction time 60 min,reaction temperature 50?,and lead chloride dechlorination rate up to 95.8%.The particle size optimization experiment showed that the best feeding method was four feedings.When adding PEG200 with a mass fraction of 4%,a red lead oxide product with an average particle size of 0.1?10?m could be obtained.