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Bioremediation of Cr(VI)-Contaminated Soil using Bacteria
Published in Maulin P. Shah, Removal of Refractory Pollutants from Wastewater Treatment Plants, 2021
In the total production of chrome ore, 90% is used in the metallurgical industry for steel, alloy, and non-ferrous alloy production; 5% is used in the refractory industry for iron and steel, cement, glass, ceramics, and machinery; and 5% is used in the chemical industry for leather tanning, plating, wood preservation, and pigments (see Figure 11.1). Cr(VI) is widely distributed in sediments and surface waters, and is more soluble, mobile, and bioavailable than Cr(III) and other types of chromium. Chromium is resistant to ordinary corrosive agents at room temperature, responsible for its use in electroplating for protective coating. These steels have a wide range of mechanical properties, besides being corrosion and oxidation resistant. Cast iron contains chromium at 0.5–30%, provides hardness and toughness, as well as resistance to corrosion and wear. Chromium is also used in non-ferrous alloys combined with nickel, iron-nickel, cobalt, aluminum, titanium, and copper (Bielicka et al., 2005). Other applications include leather tanning, metal corrosion inhibition, drilling mud, textile dyes, catalysts, wood, and water treatment. Chromite is used in the refractory industry to make bricks, mortar, and ramming and gunning mixes. Chromite increases their volume stability, strength, and resistance to thermal shock and slag.
Minerals of base metals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Chromite (FeCr2O4) [289] is the main source of chromium which is a steely-grey, lustrous, hard and brittle metal resistant to corrosion with a high melting point. Chromite ores are geographically concentrated in southern Africa [290] where about two-fifths of the world’s concentrates are produced in South Africa and Zimbabwe.
Mining Methods Vary Widely
Published in Karlheinz Spitz, John Trudinger, Mining and the Environment, 2019
Karlheinz Spitz, John Trudinger
Iron, the main ferrous metal, is the most important industrial metal, since its alloy with carbon is steel. Iron bearing minerals are found practically everywhere, and a profitable discovery of iron ore is likely to be one of very large size. Manganese is an essential ingredient in the manufacture of carbon steel. Curiously, manganese metal has no use of its own as a metal, but as a metallurgical material, it has no substitute. Apart from manganese, nickel is the most important ferroalloy, being an essential ingredient in stainless steel. Sulphide nickel ore often contains chromium, platinum, and cobalt. Serpentine and lateritic nickel deposits are derived from weathering of ultrabasic rocks and are found in New Caledonia, Cuba, Australia, Papua New Guinea, the Philippines, and Indonesia. Chromium, like manganese, is found mostly in non-industrial countries which have little use for it. Chromium mineralogy is simple: one mineral, chromite, is the only ore (Pearl 1974). Cobalt and vanadium are commonly produced as by-products of mining for other metals (uranium in case of vanadium; nickel, silver, or copper in the case of cobalt).
Performance and efficiency services for the removal of hexavalent chromium from water by common macrophytes
Published in International Journal of Phytoremediation, 2021
Madhumita Das, P. S. Bramhanand, K. Laxminarayana
Chromite is the principal ore of Cr, available in large capacity in Sukinda, in the Jajpur district of Odisha (India) and contains ≅97% reserves in the country. Open cast mining is the general practice in the area, which generates excessive material that subsequently result in leaching of Cr(VI) salt into the water table (Mishra and Sahu 2013). In addition, seepage through mines, which are situated upstream of a major waterway (Dhamsal Nala), contains heavy metals, including hexavalent chromium (Dubey et al.2001; IBM 2013). The area is included in one of the thirty most-polluted areas in the world (www.blacksmithinstitute.org2007). Several studies/reports have indicated that most wells and watercourses in the Sukinda Valley contain Cr(VI) ranging from 0.6 to 3.4 mg/L and 0.095 to 2.14 mg/L, much higher than the threshold limit of 0.1 mg/L for irrigation water (Pratt 1972; Mohanty and Patra 2011; Mishra and Sahu 2013; IIWM Annual report 2017–2018).
Integrated feed management of mineral processing plants with application to chromite processing
Published in Canadian Metallurgical Quarterly, 2021
F. A. Peña-Graf, T. Grammatikopoulos, A. Kabemba, A. Navarra
Chromium is an essential metal in modern industry; it is used in the manufacture of stainless steel, and in refractories and chemicals depending on its physical and chemical properties [1,2]. Approximately 90% of mined chromite is processed by the metallurgical industry for stainless and alloyed steel, and nonferrous alloys [2]. Over 90% of the world’s known chromium reserves and resources are in Southern Africa [2,3], although other sources are under development notably including Ontario’s Ring of Fire [3,4]. Chromite deposits are varied, and the beneficiation process is notably inefficient for fine/ultrafine chromite [5], with a tendency to have tailings with a considerable amount of valuable minerals that could not be properly recovered [6,7]. The geological variation and its impact on the beneficiation process may nonetheless be managed by alternating between modes of operation that balance process mineralogy with strategic Key Performance Indicators (KPI) [8].
Microwave reduction of Black Thor chromite ore
Published in Canadian Metallurgical Quarterly, 2018
Chromite ore is the primary source of chromium, which is a strategic metal and it is widely used as an alloy addition in steels, in particular, stainless steels. Since chromite ore contains both iron and chromium, mainly as iron chromite (FeCr2O4), then during carbothermic reduction, a ferrochromium alloy is obtained. It is commercially produced by carbothermic reduction in a submerged arc furnace [1]. The reduction behaviour of chromite ores has been studied extensively [2–4]. Chromite ore consists of a series of spinels of chromium (III) oxide with magnesium oxide (MgO), aluminium oxide (Al2O3), and/or iron (II) oxide (FeO). The reduction temperature required depends on the stabilities of these spinels. Iron chromite is usually the major spinel and is the least stable. At temperatures around 1150°C, iron chromite reacts with carbon as follows: [3]