Gold glitters in industrial uses...

Gold glitters in industrial uses
http://www.miningweekly.com/article.php?a_id=126422


Published on 22nd February 2008
The virtues and unique characteristics of gold, such as ductility, reflectivity, resistance to corrosion, and the ability to be used as a thermal and electrical conductor, make it an ideal candidate for use in a variety of industrial applications, consuming close to 300 t/y.

The question arises whether it is still viable to use gold for industrial purposes with the rising gold price and a reduction in gold production in South Africa. Mineral and metallurgy researcher Mintek’s advanced development and material manager Dr Elma van der Lingen says, “Gold has unique properties, such as excellent conductivity, oxidation resistance, catalytic properties, etc, that make it the material of choice for various industrial uses, and the influence of price increases becomes secondary.”

She adds that although gold production in South Africa has decreased significantly during the past few years, South Africa is still the second-largest world producer, and gold remains one of South Africa’s most strategic metals.

Van der Lingen says that Mintek and the three biggest gold-mining houses in South Africa (AngloGold Ashanti, GoldFields and Harmony Gold) have initiated Project AuTEK, which investigates new industrial uses for gold. The three main focus areas include catalysis, nanotechnology, and biomedical applications for gold, which will remain the focus for research and development (R&D) in 2008.

Development of industrial uses of gold

The first industrial gold conference (Gold2001) took place in 2001 in Cape Town, South Africa, and the 30 papers presented focused only on the use of gold in catalysis.

Considerable growth in activity has been seen at the Gold2003 and Gold2006 conferences, and R&D focus has been broadened to novel materials, nanotechnology and new chemistry, including biomedical applications.

“The remarkable growth in new industrial uses of gold is again expected to be showcased at the Gold2009 conference, to be held in Heidelberg, Germany, next year,” says Van der Lingen.
Van der Lingen explains that gold catalysts are already used commercially in the production of vinyl acetate monomers. Commercial use of gold catalysts is further envisaged in the conversion of glucose to gluconic acid, environmental applications, removal of pollutants from water and in diesel exhaust emission control. Project AuTEK, in collaboration with the World Gold Council, is actively marketing a range of gold catalysts for new applications. AuTEK can, at present, produce 15-kg batches of catalysts, which will be increased to a 65-kg batch production by June this year, owing to a remarkable growth in interest and demand to test these catalysts in new applications.
South Africa launched its first two nanotechnology innovation centres in November 2007.

Nanotechnology has taken the world of science by storm, and potentially holds the key to new materials with extraordinary properties. Such materials could lead to the development of new technologies that could revolutionise the quality of life of the citizens of South Africa.

Some areas where nanotechnology can be used are to improve accurate and sensitive medical diagnostic devices, new ways of disease therapy, and the monitoring and remediating of basic water supplies.

Department of Science and Technology Minister Mosibudi Mangena launched South Africa’s first two national nanotechnology innovation centres at the Council for Scientific and Industrial Research (CSIR), in Pretoria.

The current focus of the research at the CSIR is the fabrication of selected novel nanostructured materials for application in solar cells, printed electronic devices, bio-sensors and nanopolymers.

Nanotechnology in use
US company Nanostellar has overcome barriers such as the durability of gold over a period, and developed a catalyst for diesel engines. The gold is used in combination with platinum and palladium ingredients. The main advantage of incorporating gold into the design is cost effectiveness. The company claims that when compared to platinum-palladium catalysts, the gold-containing catalyst can increase hydrocarbon oxidation activity, which breaks down one of the exhaust pollutants, by 15% to 20%.

Other industrial trials currently in progress using the gold catalysts, include the control of mercury emissions from coal-fired power stations, applications in ‘green’ chemical production and in the clean-up of polluted water.

Gold nanotechnology is also being used in the liquid crystal market.

Electronics

The World Gold Council states that gold is used in the rocket engines of the American space shuttles. The shuttles are lined with gold-brazing alloys to reflect heat. Also, the lunar modules of the Apollo programme use gold foil to act as a radiation shield.

The simple touch telephone typically contains 33 gold-plated contacts. The plating of contacts in switches, relays and connectors is the main application of gold in electronics.

New technology has enabled the plating thickness of gold to be pared down to less than one-thousandth of a millimeter of gold. In spite of this, gold consumption has been maintained because of the many new electronic applications.

Japan is the largest fabricator of electronic products, accounting for over 45% of gold consumption in the electronics field, followed by the US, at 30%.

Dental Works

The second important sector that uses gold for industrial purposes is the dental sector. Gold has been used in dentistry for almost 3 000 years.

Gold’s malleability and resistance to corrosion render it suitable for dental use, although its softness means it must be alloyed for water. Platinum, silver and copper are the most common companion metals for gold dental work.

Gold alloys have also suffered competition from new techniques in dentistry, such as ceramic dental crowns. The Council states that these contributing factors have resulted in a sharp fall in gold use by the dental sector.

Other uses

Other applications for gold includes plating. The plating of items such as watches, spectacles, pens and bathroom fittings uses about 90 t of gold a year.

Gold is also used for decorative purposes on buildings. The reflective ability can cut heating and cooling costs by up to 40%.

The industrial uses of gold represent a stable fraction of gold demand, requiring more than the equivalent of all Australian gold production annually, as stated by the Council.