Study On High Chlorine Rhodochrosite Pretreatment And Dechlorination From Leaching Solution

Manganese is an important industrial raw material and widely used in various areas of national production, and the manganese ore is the main raw material for the production of electrolytic manganese metal. In recent years, with the rapid development of China’s iron and steel industry, the consumption of manganese ore has increased year by year, resulting in resource depletion of domestic high quality manganese ore with lower impurities. Therefore, from the perspective of sustainable development, solving the problem of effective use of manganese ore associated impurities is important.In this thesis, the high chlorine rhodochrosite was from Xinjiang province. At first, a variety of analytical tools were used to a preliminary analysis for its basic properties, and then the selection of dechlorination reagent, the experimental conditions and dechlorination mechanism were explored and studied in the process of pretreatment dechlorination and leaching solution dechlorination. The conclusions were following:As used herein, manganese ore sample is a black brown powder with small particles, its chemical composition is complex, its main chemical compositions are Mn, Si, Mg, Ca, Al, Fe, O, Cl, S and so on. Its manganese percentage was 39.7%, and with variety and high levels of metals. The content of non-metallic impurity elements S, P and Cl are relatively high, especially the chlorine percentage has reached 2%, and this is far beyond the requirement of electrolytic manganese industry. Manganese carbonate(Mn CO3) is the main form of Mn and manganese chloride hydroxyl [Mn2(OH)3Cl] and chlorine manganese phosphate(Mn2Cl PO4) are the main forms of Cl in this manganese ore.The selection of alkaline additives and the different experimental conditions on dechlorination were explored in pretreatment dechlorination process, the results showed that sodium carbonate was identified as antichlor and the optimum process parameters were researched. Optimal conditions were 0.45mol·L-1 sodium carbonate concentration, 1:5(g·m L-1) solid–liquid ratio, 1h reaction time, and 25℃. Chlorine removal ratio was over 95%, and ore grade was increased by 2.7%. The additives had no adverse effects on the composition and the main crystalline substance of the ore.The selection of dechlorination reagents and the different experimental conditions were explored in leaching solution dechlorination process, the results showed that bismuth oxide was identified as antichlor and the optimum process parameters were researched. Optimal conditions were 12g·L-1 bismuth oxide concentration, 1h reaction time and the end point p H was 1, chlorine removal ratio was over 86%. Bismuth oxychloride can be regenerated to bismuth oxide by alkaline agent, so it is a recyclable dechlorination agent with better dechlorination effect.