Study On The Direct Preparation Of Zinc And Manganese Oxide By Co-extraction From Galena And Pyrolusite

The preparation of electrode active material lead-sulfate and mangano-anganic-oxide from galena concentrate and pyrolusite using two-ores method was investigated.There are four main components in this research:the recover of lead and manganese, the purification of leaching solution, the preparation of the lead sulfate and the mangano-manganic oxide, and some discussions on the reaction mechanism by XRD, SEM, XPS, the electrochemistry test and complexing coordinate computation. More details are described as follows.Some factors which have effects on the lead recovery and the leaching reaction rate were explored and optimized. The reaction mechanism was studied by electrochemistry test, the complexing computation and microscopic examination. The results show that the formation of production S0membrane and the insolvent production lead-chloride membrane prevent the reaction between the galena and pyrolusite. Adding sodium-chloride at the very beginning of the reaction and adding hydrochloric acid twice during reaction will remarkably increase the recovery of lead and manganese.The iron in the leaching solution can be removed by the goethite method. The most appropriate pulp pH value was found out by the experiment. The concentration of the iron-ion, the lead-ion, the manganese-ion, the zinc-ion at the different pulp pH values were calculated by thermodynamics method, the computed results are consistent with the experimental conclusion.The influence of diluting the leaching solution with distilled water on the lead separating from the solution was researched. The complexing computation shows that the lead ion dissolves in the solution with different complex compound shapes at different temperatures and concentration of Cl-[Cl-]=1mol/L is the appropriate value of separating the lead chloride from the sodium-chloride solution. The atmospherics pressure vulcanization was used to remove heavy metal ions from the solution. The influence of the factors of vulcanization on the removing rate of the heavy metal ion was studied, and the most appropriate factors of vulcanization were found out. The analysis on the thermodynamics shows that the concentration of sulfur-ion is the key factors affecting the removing rate of the heavy metal ion at certain pulp pH value.The conditions of preparing the lead sulfate were studied. The experimental results show that the reaction time and the pulp pH value are the key factors affecting the purity and the average grain diameter of product. The XRD and SEM analyses on the composition and the appearance of product show that the purity of product is99.83%, the average grain diameter of product is250nm.The mangano-manganic oxide was prepared from the purified manganese chloride solution. The preparing conditions were researched by the single factor method and the orthogonal factor method, the most appropriate factors of preparing the mangano-manganic oxide were found out. The E-pH curves of Mn-O-H2O at60℃was drawn up by the thermo-dynamicsis calculation. In addition, the condition of the mangano-manganic-oxide stable existence was discussed based on the E-pH curves. Both the theoretical calculation and the experimental result show that the pulp pH value is the determining factor preparing the mangano-manganic-oxide pure phase. Also the pulp pH is the key factor increasing the produce rate. The XRD and XPS analyses on the product further show that the production is the pure phase mangano-manganic-oxide.