Study On Leaching And Purification Of Low-grade Manganese Carbonate Ore

Within the rapid development of national economy, the demanding to manganese resources is expanding constantly, and the price of manganese products is on the upsurge. However, the manganese resources are gradually decreasing, especially the amount of rich ores with directly utilization value. To make good use of poor ores combined rich ores or even completely poor ores is imperative due to the incessant scarcity and the issue of a relative legislation from the authorities. And economically, the continually rising price of manganese products made the exploitation and utilization possible.Sulfuric acid leaching of low grade rhodochrosite from Chengkou of Chongqing was investigated and the effects of leaching conditions on the extraction of manganese were studied. A reducing process of wet-method as well as a microwave-assisted processs was applied to improve the extraction of maganese. The experiment conditions for impurity removal, such as phosphorus, ferro and heavy metal ions, were studied. With pyrolusite as oxidant, the oxidation-neutralization method for the remove of ferro in leaching solution was studied. It was found that with the addition of manganes oxide, by adjusting the pH value to 1-2 later in the leaching process, Fe2+ was oxided to ferric ion and then removed in the form of Fe(OH)3 by adding ammonia aqueous solution. The efficiency of the removal rate for heavy metal ions in leaching solution was studied by experiment which used (NH4)2S as a suifidizing agent during the pH value from 4 to 5 within the stirring time of 2 hours at 50℃.The leaching condition of manganese and phosphorus in GaoYan's rhodochrosite was studied by traditional method of acid leaching. When pH value of the leaching system was adjusted to 6, the removal ratio of phosphorus was up to 90%. The optimal leaching conditions in saulfuric acid system were 60℃, pulp density of 40g/L, stirring rate of 100r/min and reaction time of 45 min-60 min. The dynamic behavior of leaching procedures of rhodochrosite was discussed based on the"shrinking core model"and the kinetic equation was deduced by this study. It is found that the leaching process of rhodochrosite was controlled by chemical reaction and the inner diffusion rate of leaching agent.Rhodochrosite of XiuQi's mining district which contains more high-valent manganese was researched by wet-method reduced leaching technique. Glucose, hydrogen peroxide and sawdust were evaluated as reduction additives. The experimental results were gained as follows: the leaching ratio of manganese in ores was up to 95% on the conditions of a lower-acidity at 40℃when every 4 g of rhodochrosite was treated by 0.3 g glucose and 1mL hydrogen peroxide. Otherwise, the leaching ratio of manganese in ores was only about 90% when 0.7g sawdust was used as a reduction additive on the conditions of sulfuric acid concentration of 4.5mol/L at the temperature of 80℃. The feasibility of microwave-assisted leaching process was studied. The microwave mode, microwave power and reaction time which influenced the leaching ratio were also studied. The optimal conditions were 600 W of microwave power, 20 min of leaching time.The removal of magnesium in wasted electrolyte was studied. The optimal condition was attained as follows: n(F^-):n(Mg²⁺)=1.6:1-2:1 was chosen as adding ration during the pH value from 3 to 5 at 50℃. The crystallization of MgF2 was studied in this experiment, the MgF₂ crystallization with a better filtering property was gained in the experiment.