Study On Extraction Technology Of Complex Platinum And Palladium Concentrate

Sulfide ore of Platinum palladium in Jinbaoshan in Yunnan is a typical poly-metallic symbiotic sulfide ore, which is poor, miscellaneous and hard-to-filter. It contains many serpentine silicate minerals, besides, it has low content of magnesium but copper, nickel and iron of high content making conventional fire-based process useless. Whereas amount of the metals in the minerals existed in a form of sulfide or sulfur compounds, leaching the platinum palladium directly requires large amounts of oxidants and the grade of platinum palladium in leaching solution is low, recovering is thus hard to reach. It has become an important part of the development of sulfide ore of platinum palladium in Jinbaoshan that improving the leaching efficiencyThis paper reviews the physical and chemical properties of platinum palladium metals, traditional smelting process of platinum palladium, mineral desulfurization method, leaching method of precious metals, reduction process of metals leaching solution of platinum group. In addition, we introduce the characteristics and applications rules of different processes. By researching on the desulfurization, leaching, and reduction process of flotation concentrate, we proposed a apposite process to develop Jinbaoshan platinum and palladium mine.The results show that the main component of the flotation concentrate is chalcopyrite, pyrite, sulfur and platinum palladium. The platinum and palladium metal are wrapped by sulphides. Experiments on flotation concentrate like roasting desulfurization, sodium carbonate roasting desulfurization, sodium hydroxide direct leaching desulfurization, sodium hydroxide oxygen pressure leaching desulfurization and acid-alkali joint leaching desulfurization indicated that the last desulfurization process has the best effect. At the same time, the best desulfurization process conditions is established as follow:the concentration of sulfuric acid in leaching process is 2.5mol/L, and the liquid to solid ratio is 4:1, the oxygen partial pressure is 0.7Mpa, rotation speed is 400r/min, temperature 150℃, keeping it for six hours. In alkaline leaching process, liquid to solid ratio is 4:1, temperature is 100℃,alkali concentration is 2mol/L, keeping for 3 hours. Under this condition, the removal rate of sulfur, silicon can reach 84.87% and 47.03%, respectively,leaching rate of copper, nickel, iron in flotation concentrate can reach 65.69%,67.00% and 82.82%, respectively. The grade of platinum palladium can be 3.13 times more and platinum palladium dissolution rate is less than 10%.In desulfurization concentrate,sulfur content is 8.83%, platinum content is 343.7g/t, palladium content is 425.5g/t, copper, nickel, iron contents is 4.66%,3.78%, 7.98%.after researching on chloride leaching process, the optimum chloride leaching is established, which include concentrate25g, hydrochloric acid concentration 4mol/L, and the liquid to solid ratio is 4:1,dropping the chlorite solution for 80mL at speed 12mL/h, keep it at 95℃ for 9h. Under this condition, the leaching rate of platinum is 92.83%, palladium leaching is 99.7%.In leaching solution, the content of platinum is 0.02g/L, palladium 0.03g/L, copper, nickel, iron was 3.96g/L,3.30g/L,4.80g/L. The effects of acidity on the adsorption of platinum-palladium in the iron-depositing process is studied. The result shows that, with the amount of sodium hydroxide increasing, the content of platinum-palladium in deposited iron slag increase first and then reduce while the deposit ratio of platinum-palladium go up continuously. The impact of amount of copper and the replacement temperature on the leaching solution with deposited iron are studied. The result shows that the higher temperature is good to replacement reaction, and it cost less copper in the reaction in higher temperature, while the reduction rate is very low.We studied the reduction process of platinum and palladium in tailing flotation, using zinc and iron, the content of platinum and palladium in heap leaching solution is 1.4mg/L and 4.6mg/L, solution pH is 0.35. The results show that:if the oxidants is zinc powder, and at a room temperature,8g sodium hydroxide dissolved into 500mL leaching solution, the stirring speed is 300r/min, add 5g zinc into the solution, after a 15min-reaction, the pH is 3, the reduction rate of platinum and palladium reach 100%; if the oxidants is iron powder, at room temperature, add 4g of iron powder into 250mL tailings leaching solution and stir it at a speed 300r/min,45min later, the leaching rate of platinum, palladium are 100%, but there is a lot ferric hydroxide precipitate in reducing slag.