Experimental Study Of Preparing High Purity Lead By Recycling Lead Paste In Wet Process

With the economic and social development, the number of discarded lead-acid batteries is increasing day by day. Waste lead-acid batteries are hazardous waste, needed to be properly handled.At present, there are two directions in the treatment of waste lead acid battery, which are fire method and wet method. Technology research focus on the lead sulfate and lead dioxide due to its high content in lead paste. In this paper, This article presents paste lead dioxide conversion-lead paste desulfurization-precipitation-roastingprocess wet processing technology, in order to obtain high purity lead oxide. In this paper, the technological process and the related theory of experimental research had been studied.First of all, this paper studiedthe characterization and chemical analysis of lead paste which has been preliminary treated.The main composition and content in lead pasteinclude:PbSO4(50%?60%),PbO2(20%?30%),PbO(11%?13%),Pb(3%?5%). In addition, impurities such as Fe, Sb, slender fibers and pieces of plastic also contains in lead paste.Secondly, this paper uses several kinds of conversion agent of PbO2 to do the conversion experiment. Determine the influence ofthe conversion agent dosage, reaction time and reaction temperature. The results show that in several conversion agent, hydrogen peroxide and sodium bisulfite has higher conversion efficiency in the conversion efficiency of PbO2 experiments.Temperature to room temperature, add lead paste 10g, (1+1)acetic acid lOmL, deionized water 50mL, than using 30% hydrogen peroxide solution 9mL to deal with PbO2, the conversion rate can reach more than 98%; Using sodium hydrogen sulfite 3g, the conversion rate can reach more than92%, When the temperature increased to 80?, the conversion rate can reach more than96%.Using sodium bisulfite as converting agent, the product transformation is PbSO4 and Na2SO4. PbSO4 can be used for subsequent lead paste desulfurization process, Na2SO4 can react with Ca (HSO3)2 to regenerate the conversion agent. Ca (HSO3)2can be got by using Ca(OH)2absorb SO2. Through the analysis of the theoretical calculation of Ca(HSO3)2 preparation process, that the process of absorption and reaction need to control the pH=3-5, SO2 concentration in 681ppm.Then, this paper explore the sodium acetate, potassium acetate and lead acetate, the three desulfurization agent's desulphurization effect on PbSO4 paste, mainly studiesseveral factors which are the concentration of desulfurization agent, reaction time, reaction temperature and stirring speed, their effect on desulfurization efficiency influence. The results of experiment show that the desulfurization efficiency with the increase of the concentration of desulfurizer increases when the desulfurizer is a saturated solution of reach, optimal reaction time was 60min, the optimal reaction temperature for 60 to 80 DEG C, optimal mixing speed 700rpm.Finally, the text of the lead oxide and lead oxide precursor were characterized.Through X-ray diffraction and TG-DSC curve shows, reaction product is basic lead carbonate, lead carbonate and lead carbonate when the desulfurizer is weakly alkaline. Lead oxide precursor product obtained for lead carbonate when the desulfurization agent is neutral. Roasting the lead oxide precursor can get the lead contain none impurities.