Study Of The Differences Of Typical Copper And Nickel Sulfide Ore Bioleaching

The leacing rate of different valuable metallic elements are different while low-grade copper and nickel sulfide ore bioleaching. Under the same bioleaching time, the leaching rate of Ni is the highest, that of Co is the second and the leaching rate of Cu is the lowest, the concentration of valuable metal ions in the bioleaching liquid is very different. Moreover, bioleaching of impure minerals will let the component of the leaching liquid complex, what will result in the dispose of the leching liquid difficult and the economic effectiveness reduce.Aims at the problems above, the differences of three typical sulfide minerals chalcopyrite, pyrite, pentlandite bioleaching under the same conditions were studied, to provide theoretical basis of low-grade copper and nickel sulfide ore bioleachingThe experimental results indicate that the leaching efficiency is difference between these minerals. At the same bioleaching time, the leaching ratio of chalcopyrite was the lowest (14.5%) and its leaching rate decreases with time. The leaching ratio of pentlandite was the highest (28.33%), that of pyrite (21.06%) was somewhere in between. The leaching rate of pyrite and pentlandite was more or less steady.There’s a difference of bacteria community succession of these minerals bioleaching process, Leptospirillumferriphilum move from advantage bacteria (98.6%) to disadvantage bacteria (38.5%) in chalcopyrite bioleaching process and in pyrite bioleaching process Leptospirillum ferriphilwn always be the dominant bacteria (90%). In pentlandite bioleaching process Sulfobacillus thermosulfidooxidans was dominant bacteria (60%), Leptospirillumferriphilum was the inferior organisms, but its proportion was rising as time progresses.Jarosite generated at the bioleaching process of all of these minerals. Most of the jarosite are microgranular, some can cover all or part of the surface of these minerals.What give rise to the differences of the bioleaching process of these minerals is the differences between these mineral’s crystal structure. Chalcopyrite crystal structure is stabilitiest, so it’s the most difficult mineral to be bioleached. The stability of pentlandite’s crystal structure is the worst and it can be resolved under the attack of H+, so it’s the easiest mineral to be bioleched.At the end of the bioleaching process, the microbes give different influence to these minerals. The acceleration of microbes to chalcopyrite bioleaching process is the worest, to pyrite is the second, to pentlandite is the best. This led to the differences of the leaching rate of these minerals at the end of the bioleaching process. Futhermore, there is a interaction relationship between mineral and microorganism in the bioleaching process. The presence of microbial can promote the leaching ratio of mineral, but generally speaking microbial metabolism behavior are greatly influenced by the properties of mineral.What give rise to the differences of strains succession between these minerals is not the pH of the leaching liquid, but the Fe2+ supply difference caused by the different leaching mechanism decide by the different crystal structure of different mineral.The determinant factor cause the oxidation rate difference of these minerals is not the produce of jarosite at the end of leaching.