Basic Study On Leaching Manganese From Polymetallic Nodules In The Organic/Inorganic Composite System

The ocean polymetallic nodule is a deep-sea strategic reserve resource for future industrial development. Its commercial mining technology reserves are facing the problems of far offshore mining platform and high transportation cost. Manganese nodules in situ processing, due to obvious cost advantages, is regarded as a new trend of deep-sea manganese nodule processing technology development. Marine mining platform operation and ship operations personnel need a lot of fresh water by dilutting a lot of salt water. The biocides introduced in the desalination process are prone to form toxic trichlorophenol by natural action. The direct discharge does not meet the requirements of the International Convention on the Law of the Sea. The reductive triclorophenol as a leaching agent, works together with pyrite reduction leaching of ocean nodules while seawater desalination wastewater becomes resource utilization. The trichlorophenol residual in the leaching solution, combined microbial fuel cell method for deep purification to reach the wastewater discharge standards. Therefore, it is practical significance to improve the leaching technology of oceanic nodule and the utilization of waste water in organic/inorganic compound added with trichlorophenol.The effects of sulfuric acid concentration, pyrite content, liquid-solid mass ratio, leaching temperature, leaching time, and pH value of the system were studied on the leaching ratio of manganese, elemental sulfur residue and iron conversion in this system. The leaching ratio of manganese was 90.2% under the conditions of pyrite content 12.8%, leaching temperature 80 ?, sulfuric acid concentration of 1.5 mol/L and liquid to solid ratio 6:1. The conversions of pyrite in the leaching reaction of inorganic system were FeS2-S0-SO42- and FeS2-Fe2+-Fe3+. The effects of 2,4,6-TCP concentration, oceanic nodules dosage and pyrite dosage on the leaching ratio of manganese and the retention of residual leachate were explored. The manganese leaching ratio was 5.8% when the initial concentration of 2,4,6-trichlorophenol was 300 mg/L and the concentration of oceanic nodules was 166.7 g/L.2,4,6-TCP can reduce leaching of oceanic nodules and degrade 2,4,6-TCP, but not the pyrite.When the initial concentration of 2,4,6-TCP of 300 mg/L and pyrite of 12.8%, manganese leaching was 97.6%, and the residual concentration of 2,4,6-TCP was 50.1 mg/L.2,4,6-TCP direct reduction of oceanic nodules, which aggravates the crystal lattice destruction of oceanic nodule minerals, make the metal cations such as Cu2+,Co2+ and Ni2+ released in the leaching solution, meanwhile, redox reaction potential increased improving the system of chemical reactivity. When the initial concentration of 2,4,6-TCP was 50 mg/L, the removal ratio of 2,4,6-TCP reached 97.4%, and it was found that the concentration of 2,4,6-TCP in the leaching solution of organic/inorganic composite system was degraded by microbial fuel cell.2,4,6-TCP degradation pathway was firstly degraded into 2,4-dichlorophenol (2,4-DCP) after being catalyzed by bacteria.