• Manganese: resource distribution and production

• Resource distribution

• Manganese is the 12th most abundant element in the earth’s crust. According to the data released by USGS (United States Geological Survey) in 2014, global manganese reserves are about 570 million tonnes (metal content) with land-based manganese resources distributing irregularly.
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• According to USGS, manganese resources are mainly distributed in South Africa (150 million tonnes), Ukraine (140 million tonnes), Australia (97 million tonnes), Brazil (54 million tonnes), India (49 million tonnes), China (44 million tonnes), Gabon (24 million tonnes) and Mexico (5 million tonnes).

• Manganese resources in the ocean -- manganese nodules

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• Nodules lie on the seabed sediment, often partly or completely buried. The total amount of manganese nodules on the sea floor is estimated to be over 3 trillion tons. The highest concentrations of manganese nodules have been found on vast abyssal plains in the deep ocean between 4,000 and 6,000 meters (13,000 and 20,000 ft). Manganese nodules were discovered in 1868 in the Kara Sea, in the Arctic Ocean off Siberia. During the scientific expeditions of HMS Challenger (1872–1876), they were found to occur in most oceans of the world.
• Nodules of economic interest have been found in three areas: the north central Pacific Ocean, Peru Basin in the southeast Pacific, and the center of the north Indian Ocean. The most promising of these deposits in terms of nodule abundance and metal concentration occurs in the Clipperton Fracture Zone of the eastern equatorial Pacific between Hawaii and Central America.
• Classification of manganese nodules
• Depending on the major ore elements (manganese, iron and base metals) the nodules contain, they can be classified into three major types:
• (1) hydrogenous: formed due to slow deposition of metals out of sea water and characterized by a high concentration of base metals and varying Mn/Fe ratios (from 0.5-5).
• (2) hydrothermal: rich in iron and depleted of other metals, which turns out to have an extremely wide range of Mn/Fe ratios.
• (3) diagenetic: characterized by high Mn/Fe ratios and a relatively low concentration of base metals.
• Manganese nodules mining
• Interest in the potential exploitation of manganese nodules generated a great deal of activity among prospective mining consortia in the 1960s and 1970s. Almost half a billion dollars was invested in identifying potential deposits and in research and development of technology for mining and processing nodules. These initial undertakings were carried out primarily by four multinational consortia composed of companies from the United States, Canada, the United Kingdom, the Federal Republic of Germany, Belgium, the Netherlands, Italy, Japan and two groups of private companies and agencies from France and Japan. There were also three publicly sponsored entities from the Soviet Union, India and China.
• In the mid-seventies, a $70-million international joint venture succeeded in collecting multi-tonne quantities of manganese nodules from the abyssal plains (18,000 feet, 5.5 km + depth) of the eastern equatorial Pacific Ocean. Significant quantities of nickel (the primary target), as well as copper and cobalt, were subsequently extracted from this “ore” using both pyrometallurgical and hydrometallurgical methods. In the course of this eight-year project, a number of ancillary developments evolved, including the use of near-bottom towed side-scan sonar arrays to assay the nodule population density on the abyssal silt whilst simultaneously performing a sub-bottom profile with a derived, vertically oriented, low-frequency acoustic beam.
• The technology and experience developed during the course of this project were never commercialized because the last two decades of the 20th century saw an excess of nickel production. The estimated $3.5billion (1978 US dollars) investment to implement commercialization was an additional factor. Sumitomo Metal Mining continues to maintain a small (place-keeping) organization in this field.
• In 2013, extensive iron-manganese deposits were discovered by the manned submersible during a dive conducted in the South China Sea, and eight samples were taken from the deposits, marking a great step in the exploration of manganese nodules.
• Legal developments
• The promise of nodule exploitation was one of the main factors that led developing nations to propose that the deep seabed remain beyond the limits of national jurisdictions and should be treated as a “common heritage of mankind”, with proceeds to be shared between those who developed this resource and the rest of the international community. This initiative eventually resulted in the adoption (1982) of the United Nations Convention on the Law of the Sea and the establishment (1994) of the International Seabed Authority, with responsibility for controlling all deep-sea mining in international areas. The first legislative achievement of this intergovernmental organization was the adoption (2000) of regulations for prospecting and exploration for polymetallic nodules, with special provisions to protect the marine environment from any adverse effects. The Authority followed this up (2001-2002) by signing 15-year contracts with seven private and public entities, giving them exclusive rights to explore for nodules in specified tracts of the seabed, each 75,000 square kilometers in size. The United States, whose companies were among the key actors in the earlier period of exploration, remains outside this compact as a non-party to the Law of the Sea Convention. In May 2010, the International Seabed Authority enacted rules covering exploration for polymetallic sulphides in international waters.

• Production

• Pure manganese is usually produced by hydrometallurgical and electrolytic processes. According to USGS, world manganese mine production was estimated to be 17 million tonnes in 2013, an increase of 7.6% compared with 15.8 million tonnes in 2012. South Africa was the largest producer in 2013, followed by China and Australia. The top three countries accounted for 41% of the total production in 2013. Other major producing countries include Gabon, Brazil, Indian, Kazakhstan, Ukraine, Malaysia, Mexico and Burma.
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• (Source: Roskill)
• According to IMnI (International Manganese Institute), Mn ore (wet) production in 2011 reached 55 million mt. This amounted to 17.2 million mt in Mn units. China was the largest producer of Mn ore (4.1 million mt in Mn units), followed by South Africa (3.6 mln mt), Australia (3 mln mt), Gabon (1.9 mln mt), Brazil (1.2 mln mt), India (895K mt), the Ukraine (516K mt) and Ghana (484K mt). Other countries produced 1.5 mln mt.
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