What Is Chromium and Where Do I Use It?
- Chromium is the most abundant of the Group 6 of metallic elements, which is extracted from chromite (chrome ore). With nearly 400 parts per million in the earth’s crust as various minerals, it is the 13th most common element.
- It is silvery-white, corrosion-resistant, hard metal that is an essential component of stainless steel and other alloy steels, where it is used as ferrochromium.
- Metallurgical industry: Chromium used in steel alloys has a strengthening effect through forming stable metal carbides at the grain boundaries. Furthermore, it increases corrosion resistance of steel.
- Refractories and foundries: Chromite is used for manufacturing bricks and other devices in the refractory industry
- Other chemicals: Chromium containing chemicals are used for leather tanning, drilling muds, cosmetics, catalysts or wood preservatives
- About 90% of all leather is tanned using chrome. However, the waste effluent is toxic so alternatives are being investigated.
- Chromium compounds are used as industrial catalysts and pigments (in bright green, yellow, red and orange colours). Rubies get their red colour from chromium, and glass treated with chromium has an emerald green colour.
Where is Chromium Produced?
- The major chromite deposites are located in South Africa, Kazakstan, Zimbabwe, Kazakstan, India and Turkey. There are also significant deposites located in Brazil, Cuba and Albania.
- The Bushveld Complex in South Africa covers more than 60,000 km2 and includes at least 14 chromitite horizons of economic or potentially economic importance.
- Several countries have restrictions concerning trade with chromium. According to the OECD´s inventory on export restrictions, export taxes on chromium waste and scrap are used by Russia (6.5%) and Pakistan (25%).
- Licensing agreements exist in India for chromium ores and concentrates. In South Africa these agreements extend to chromium and articles thereof, waste and scrap, unwrought chromium and powders. Company concentration is also a concern for chromium.
- Most chromium resources in South Africa are located in the Bushveld Igneous Complex; which is estimated to contain nearly 70% of world reserves.
- Environmental and health concerns have been raised over some chromium compounds; Hexavalent [Cr(VI)] compounds are especially toxic to humans and thus the EC regulates the usage and content of hexavalent chromium.d This leads to declining usage of chromium in some applications. There are concerns that it could drive aeronautics construction out of the European Union.
- There is currently no substitute available to replace the use of hexavalent chromium to protect aluminium parts from corrosion.