Zircon
Zircon (ZrSi04) contains zirconium, an extremely hard metal that is resistant to corrosion. It is found useful in chemical plants and nuclear reactors.
The name Zircon is derived from the Arabic word 'Zargun,' zar meaning gold and gun meaning colour. However, this is not completely accurate as zircon can be found in many colours ranging from colourless to; green, blue, light red, purplish red, yellowish brown, yellow, orange or white. Some zircon crystals can actually be of gemstone quality and much of the mineral is sought after for this purpose. Its hardness also makes it valuable as an abrasive. Besides zircon being used in chemical processing plants and nuclear reactors, it is also used for the following purposes:
- In steel making blast furnaces because of it having a melting point above 2,500 degrees Celsius
- In the ceramic, spacecraft, electronic and engine parts industries because of its resistance to heat and corrosion
- In computer disc drives
- The providing of protection and warmth in clothing because of its light weight
- In the manufacturing of wear resistant knives and ball point pens
Zircon is contained in most mineral sands deposits and Australia is the world's foremost producer as it provides up to 45 percent of the worlds zircon requirements. One of the major problems with the production of zircon has been the presence of thorium and uranium that makes it radioactive. However, this only becomes a worry when the radioactive levels are above 500 parts per million (ppm). The increasing availability of zircon with low-level radioactivity is leading to greater prices being charged for the product. Victoria is known to have considerable zircon deposits of fine particle dimensions but exploitation is held back because its high radioactive levels make it unattractive to commercial developers.
In an effort to overcome the radioactivity problem associated with otherwise commercial grade zircon deposits, the CSIRO (Commonwealth Scientific Industrial Research Organisation) has come up with a process that is able to reduce radiation levels while at the same time remove other impurities. This development will make these previously untouchable deposits commercially viable.
The CSIRO process reduces the radiation levels of zircon with the use of heat that is followed up with leaching to remove the radio nuclides. This involves the following:
- Grinding of the zircon to a particle size of 15 to 20 um
- Calcining the ground zircon particles by means of a borate mineral at 1,200 degrees Celsius over a period of four hours
- Leaching of the calcine with a dilute acid solution
CSIRO laboratory testing has proven the low cost process is successful for the following reasons:
- It protects zircon crystal integrity
- No new impurities are introduced
- Removes existing impurities such as uranium, thorium, titanium, aluminium and iron
- Particle size is maintained
- Radioactive levels are lowered
The Pure Zircon Process developed by the CSIRO will also be able to be applied to the commercial synthesis of zirconia. Zirconia is a mineral that naturally occurs in nature that can also be synthesised from zircon. It is used in combination with minerals such as iron and cobalt in order to produce colour pigment used in refractors. However, zirconia, made from zircon by fuming, does contain increased levels of radiation when compared to zircon itself. When the zircon has previously been processed through the CSIRO's Pure Zircon Process, the end product, zirconia, will have an acceptable radiation level also and be commercially viable.
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.
