CHROMIUM

Chromium is a transition metal in Group VI of the periodic table. It is a very hard, crystalline steel-gray metal with an atomic number of 24 and a molecular weight of 528 g/cm3. Commercial chromite deposits are found mainly in two forms: stratiform and podiform. Zimbabwe is the only country with notable chromite reserves in stratiform and podiform deposits. (a) Chromite reserves by country (Source: ICDA, 2021). (b) Top five chromium producing countries (updated 2024) (Source: Investingnews.com). (c) Stainless-steel production by country. Production, consumption, import/export The production of chrome ore has seen an increasing trend. The world’s total chromium reserves amounted to 560 Mt as of 2023. The leading chromium producing country in 2023 was South Africa, which has the largest reserves globally. Globally, chromium mine production was 41 Mt, a significant increase from the 2010 production volume of 23.7 Mt. Turkey, Kazakhstan and India were among the other leading producers worldwide. The value of chromium consumption was estimated to be $830 million in 2023 (as measured by the value of net imports, excluding stainless steel), a 44 percent decrease from $1.5 billion in 2022. U.S. consumption was estimated to be about 4 percent of the world chromite ore production with a net import reliance of 74 percent. The major importers or consumers were China, Indonesia and Sweden. China is the leading producer of ferrochromium, followed by South Africa, Kazakhstan and India. Other producing countries include Albania, Brazil, Finland, Germany, Indonesia, Japan, Oman Sultanate, Russia, Sweden, Turkey and Zimbabwe. Reserves of chromite deposits South Africa is home to the world’s largest chromite resources, situated in the Bushveld Complex, the largest layered intrusion in the world. Geologists estimate the complex represents more than 80 percent of global chromite reserves, covering an area of more than 65,000 km² with thickness of 7 to 9 km. It contains dunites, pyroxenites, anorthosites and oxides (chromite and magnetite), and displays a well-marked horizontal layering, with layers a few millimeters to 100 m thick and exceptional lateral continuity. South Africa also supplies chrome ore as UG2 (Upper Group 2 reef) during the production of platinum group metals (PGMs). The supply of UG2, in addition to traditionally mined chrome ore, has changed the structure of the ferrochrome industry. The United States has about 630 kt of chromium reserves (less than 1 percent of the world reserves), primarily found in the Stillwater complex in Montana. Marketing, price, economics and transportation Global chromite ore mine production was estimated to have decreased slightly in 2023 compared with 2022. Production in South Africa, the world’s leading producer of chromite, decreased by an estimated 6 percent compared with 2022, owing to disruptions to the supply of electricity and problems with the transportation of ore via rail. In the last year, the average chromite ore price was $290/t, the highest in the past few years. China was the leading ferrochromium and stainless-steel producing country and the leading chromium consuming country. Industry news and issues Depletion of high-grade reserves will create a serious problem for the future of the chromite industry. Ferrochrome production is an energyintensive process. There is a need to investigate alternate renewable energy sources, such as hydro and wind, for sustainability. Further, a consistent supply of chrome ore at the right price, a steady power supply, reductants such as ultralow-phosphorus and lowphosphorus metallurgical coke, and favorable market conditions are needed. Novel agglomeration processes such as composite briquettes (stiff vacuum extruded briquettes) for utilization of ore fines, coke fines, and so on, need to be implemented. Further innovations are needed in process technology, process control, and plant simulations and equipment design, such as the development of novel ways for the effective utilization of wastes such as slag or sludge generated from ferrochrome plants. Compliance with stringent pollution control norms will be an increasing issue in the industry. Uses and new applications The use of chromium in the metallurgical (about 50 percent), chemical (about 15 percent) and refractory (about 35 percent) industries is well known. It is an essential element in the production of a wide variety of stainless steels, alloy steels, nickel-chromium heating elements and plating metals. Chromium has critical applications in the aerospace, military, agricultural and engineering industries. Alloy 625 is used in seawater heat exchangers in oil refineries and offshore topside applications. Chrome-nickel alloys (namely, Alloy 28, Alloy 825 and G3) are also used in oil country tubular goods (OCTG) seamless tubes. Alloy 28, which accounts for more than two-thirds of these tubes, contains between 26 and 28 percent chromium. Alloy 825‘s chromium content makes it resistant to a variety of oxidizing substances, such as nitric acid, nitrates and oxidizing salt. Another major application for chrome-nickel alloys is in scrubbers used in the marine industry to reduce sulfur oxide (SOx) emissions. Chemical-grade chrome ore represents 3 to 5 percent of the global chrome ore output used by the chrome chemical industry. Globally, around 80 percent of all leather is chrome-tanned. The chromite mineral is widely used in furnace linings as refractory. Trends and outlook The continued demand for stainless steel in construction, automotive and other industries is expected to be a key driver for future chrome consumption. Chrome ore production has seen an increasing trend globally due to high prices and higher demand from China, whereas Europe and the Middle East region experienced improved demand for local smelters, which also led to an increase in the ore demand. Despite power/energy supply issues in South African countries and slower market demands, ferrochrome production is picking up. Environment, regulatory and reclamation issues Chromium has three common oxidation states: Cr (II) and Cr (III), which are basic, and Cr(VI), which is acidic. Chromium in nature comes directly from mining and indirectly from tannery, chrome plating industries, chemical industries, and others. At the trace level, the trivalent form is considered an essential nutrient; however, the hexavalent form of chromium is toxic, carcinogenic and mutagenic in nature. Considering its toxicity and carcinogenic nature, the maximum levels permitted in the United States for trivalent chromium in wastewater is 5 mg/L and for hexavalent chromium is 0.05 mg/L. Numerous treatment technologies are available for chromium remediation, but the suitability/ applicability of each method or technique depends on the nature and extent of contamination. Most of these methods suffer from technical and/or economic shortcomings, such as high capital and/or operational costs and/or the problems associated with the disposal of the residual metal-containing sludge. Longterm sustainable methods like bioremediation and phytoremediation are processes that can be adopted instead of disposal in tailing ponds. The tailings (or waste) from chrome ore processing plants (COPP) are disposed of through suitable systems, and the water is recovered back into the system for reuse. Water purification and disposal are expensive operations and are usually influential factors in the location and design of processing plants. All the technologies are well established in other areas of mineral processing; in the mineral industries, particularly in India, effective environmental controls and processing must be established on the plant scale. References ICDA icdacr.com Investingnews.com, 2024, Top 5 Chromium-producing Countries (Updated 2024) KPMG commodity insights bulletin—chromite 2018 U.S. Geological Survey, Mineral Commodity Summaries, January 2024 Indian Minerals Yearbook 2020 (Part III : Mineral Reviews) 59th Ed.—Chromite. Chromite as on 08.02.2022. pmd (ibm.gov.in) Chrome ore beneficiation challenges & opportunities – A review. Minerals Engineering, Y. Rama Murthy, Sunil Kumar Tripathy, C.

CHROMIUM

Authored by:
Y. Rama Murthy

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To view the past issues of the UCA magazine you must be a member of SME/UCA.

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