Chromium
Chromium (Cr) is a steel grey, brittle, hard, lustrous metal that can be highly polished, it also resists tarnishing and is tasteless and odourless.
Chromium oxide was used by the Chinese more that 2,000 years ago to coat weapons found among the Terra Cotta Warriors and Horses sculptures in the Lintong district, Xian, in 1974. It was recognised as an element in the Western World in the red crystalline mineral, crocoite, in 1971 and was first used as a pigment. Chromium metal was isolated in 1979 by Frenchman, Louis Nicolas Vauquelin. Since that time small amounts for free chromium have been found in rare minerals. Commercial chromium is obtained from chromite ore which is actually iron chromium oxide. Its name is derived from the Greek word for colour because of its compounds having intense colours.
Chromium Metal is Highly Valued
Chromium metal is highly valued because of its hardness and resistance to corrosion. It is also able to make steel resistant to dis-colourisation and corrosion by mixing it with steel during its manufacturing process to produce what is commonly known as stainless steel. This use of chromium, along with electroplating, makes up for 85 percent of its commercial use in today\'s market. Chromium compounds make up the remaining 15 percent. In large amounts it can be toxic to the human body.
Remarkable Magnetic Characteristics
Chromium has remarkable magnetic characteristics and it is the only elemental solid that displays anti-ferromagnetic ordering at room temperature. and above 38 degrees Celsius it transforms itself into a paramagnetic state (when certain materials are attracted by an outside magnetic field).
Chromium Forms its own Protection When Exposed to air
When chromium metal is exposed to air it forms a thin protective oxide surface only a few atoms thick. This protective layer is quite dense but prevents the oxygen in the air getting through to the underlying material. Without this protection oxygen can get into plain carbon steel and iron and cause rusting. The protective oxide layer on chromium can be removed with a strong reducing agent. When this occurs the chromium metal can be dissolved in weak acids.
Uses of Chromium
Australian Mines that produce Bauxite
Gove (NT)
Up to 600 workers employed at the Gove bauxite refinery in the Northern Territory face an uncertain future as Pacific Aluminium suspends alumina production.
Ely (QLD)
The Ely Alcan Queensland Pty Ltd agreement at the Weipa bauxite mine is due to expire in 2041 but an option will give it a further 21 years extension.
Skardon River (QLD)
Gulf Alumina acquired 100 percent of the Skardon River tenement in 2011 from its koalin mining joint partner to develop the mining of bauxite at the site
Weipa (QLD)
The Weipa bauxite mine on the western side of the Cape York Peninsula in northern Queensland is both owned and operated by Rio Tinto Alcan.
Huntly (WA)
The Huntly mine in Western Australia is the largest bauxite mine in the world currently producing about 23 million tonnes of bauxite annually.
Willowdale (WA)
The Willowdale bauxite mine that commenced production in 1984 still processes 10 million tonnes of bauxite a year at the nearby Wagerup Refinery.
Worsley (WA)
The Worsley bauxite mine and alumina refinery in South West Western Australia employs more than 1,800 people and produces 4.6 million tonnes of alumina annually.
South Aurukun (QLD)
The South Aurukun bauxite tenements on the Cape York Peninsula in Far North Queensland are held by Gulf Alumina.
Marchinbar Island (NSW)
The Marchinbar Island bauxite deposit in far north Northern Territory could be mined to satisfy a growing demand from China in the near future.
Kwinana Refinery (WA)
The Kwinana refinery in WA employs around 1,000 direct employees with 60 percent living in the nearby towns of Rockingham, Cockburn and Kwinana.
Wagerup Refinery (WA)
The Alcoa owned Wagerup alumina refinery in W.A. has received governmental approval to lift alumina production from 2.6 to 2.65 million tonnes annually.
Pinjarra Alumina Refinery (WA)
The Pinjarra alumina refinery, near Mandurah south of Perth, is an important part of Alcoa's three refinery system in Western Australia.
Portland Aluminium Smelter (VIC)
The Portland Aluminium smelter in western Victoria, a joint venture operation between Alcoa, CITIC and Marubeni, caters solely to the Asian market.
Felicitas (WA)
The Felicitas bauxite project in Western Australia contains a bauxite resource of 220 million tonnes that will give it a life of mine of 25 years
South Of Embley (QLD)
Despite Rio Tinto placing its South of Embley bauxite project in Cape York, Queensland, on hold for 18 months it still considers it a 'good project.'
Bauxite Hills (QLD)
The Bauxite Hills Project on the Cape York Peninsula in Queensland is hoping to take advantage of an expected increase in the demand for Alumina.
Bald Hill (TAS)
Australian Bauxite Limited's Bald Hill mine, in Tasmania, is to start production in December, 2014. It is the first new bauxite mine in Australia, for over 35 years.
Urquhart Point (QLD)
The Urquhart Point Heavy Mineral Sands Project in Cape York in Far North Queensland is expected to begin production in mid-2015.
Amrun (QLD)
The Amrun bauxite project in far north Queensland, that was previously known as the 'South of Embley' project has been approved for development and expected to be in production by 2019.
