Extraction of Copper, Nickel and Cobalt from Indian Ocean Polymetallic Nodules

Abstract

303I n recent years, there has been considerable interest in the potential use of deep-sea manganese nodules for the recovery of copper, nickel, cobalt and manganese, by those countries which have no domestic production of these metals. To meet their industrial and military requirements, these countries depend entirely on foreign nations for the supply of these metals and thus are vulnerable to supply disruptions. Some countries, which have partial production of these metals, meet their needs by importing them. Nickel and cobalt are critical components in alloy steel used for jet engine parts, high strength tools, heat and corrosion resistant alloys, magnets, catalysts, drying additives in paints and other chemicals. Cobalt metal is generally used either as a powder, solid metal, or one of its salts. In recognition of the strategic importance of these metals, research has been directed for their extraction from deep-sea manganese nodules as a major source. In spite of the development of suitable technologies in the United States and Japan for the recovery of these metals, it has been observed (Jordan, 1988) that research on these resources should be limited to approaches that promise to cut the total processing costs by at least 50%. The economics of recovery are not favourable as it is $17/lb and the rate of return of investment is only 4% to 6%. However, at least a 30% rate of return on investment is required to attract the necessary venture capital for sea nodule production.In present work, an effective chemical process has been developed for the extraction of copper, nickel, cobalt and recovery of manganese as manganese carbonate. Manganese nodules from the Indian Ocean basin are abundant in water depths of around 2000 to 5000 meters. They are rough surfaced, contain todorokite as the dominant mineral phase, have a thicker oxide layer and are rich in Mn/Fe and Cu/Ni ratio. They range from 0.625 to 7.25 cm in size and are composed of MnO 2 and Fe 2 O 3 or hydroxides (40% to 70%) as the main component associated with relatively minor amounts (0.1% to 1.0 %) of copper, nickel and cobalt. The mineralogy is basically fine-grained oxides mixed with layers of silicious gangue minerals (Parekh et al., 1988). Haynes et al. (1983) gave comprehensive flow sheets for the processing of the nodules in 1983. Five of the most promising techniques for metal extraction are: gas reduction and ammoniacal leach, cuprion ammoniacal leach, high-temperature and high pressure H 2 SO 4 leach, reduction and HCl leach and smelting and H 2 SO 4 leach. On reviewing the details of these methods, it is evident that the cuprion ammoniacal leach process is not appropriate for cobalt extraction, and the other four methods are complex, expensive and hazardous to the environment. Mn-nodules contain up to 30% water even when drying in air (Mizola et al., 1989). Thus hydrometallurgical processes will be superior and economical to the pyrometallurgical ones due to saving of energy. Some of the extractive metallurgical details have been described in...

Toxicity Analysis of Effluent Released During Recovery of Metals from Polymetallic Sea Nodules Using Fish Haematological Parameters

“…For metal extraction purpose nodules are dried at 110 0 C, grounded and treated with reducing agents, followed by ammonia leaching. Separation of metals is done by the process of solvent extraction and electrowining (Jana et al, 1990;Kumar et al, 1990;Agarwal & Goodrich, 2008;Biswas et al, 2009). During the process of metal recovery highly contaminated effluent is generated that still retains substantial amount of metals (Vaseem & Banerjee, 2011a).…”

X‐ray fluorescence determination of major elements in ferromanganese nodules

“…Today, the depletion of continental deposits and increasing consumption of metals demand the creation of modern equipment for the extraction of ferromanganese nodules from the oceanic bottom as well as effective techniques of their processing. [1,2] Valuable ore elements contents determination is necessary for the estimation of deposit industrial significance, whereas the data of other major elements contents are important for geochemical investigations. Wet chemistry is traditionally used for ferromanganese nodules analysis, but it includes a long stage of sample decomposition.…”

Efficacy of phytoremediation technology in decontaminating the toxic effluent released during recovery of metals from polymetallic sea nodules

“…For the metal extraction purpose the nodules are processed through many metallurgical methods including reduction, ammonia leaching, solvent extraction, electro winning and smelting (Kumar et al 1990;Jana et al 1999;Agarwal and Goodrich 2008;Biswas et al 2009). Such metallurgical processes also generate large amount of toxic effluent (PMN effluent).…”