Modern Uses of Gold
Of all the minerals mined from the earth, there is none with more practical uses than gold. Its usefulness is derived from a combination of truly unique properties. One such example of its exceptional flexibility comes from the fact that it is the most malleable and ductile of all metals. Imagine, a single ounce can be mechanically stretched into a sheet 300 square feet!
Gold is far too valuable to use by chance, instead it is selected only when less expensive or effective alternatives cannot be found. It’s really only in the last two or three decades that modern science techniques have discovered how truly important this precious ‘substrate’ is in helping solve age-old and future challenges. The following is a list of gold’s most popular modern-day applications.
In the Production of Jewellery
It is estimated that approximately six thousand years ago gold was used in the production of ornamental objects. While expert opinion varies on this point, many believe that this was probably the first use of gold. Today, most of the newly mined or recycled gold, about 78%, is used in the manufacture of jewellery.
Its special properties make gold make perfect for manufacturing jewellery. Specifically, it is a combination of the following attributes or qualities that give it its elevated status among other precious metals:
• very high luster;
• desirable (yellow) color;
• resistance to tarnishing;
• ability to be manipulated into wires, hammered into sheets or cast into shapes.
These are all properties of an attractive metal that can be easily worked into beautiful and highly desirable objects.
The most important industrial use of gold is in the manufacture of electronics. Did you know a standard touchtone telephone typically contains 33 gold-plated contacts? Contacts are electroplated with a very thin film of gold. This ‘touch’ of gold on the contact serves a dual purpose. First, it ensures rapid dispersion of heat while protecting it against detrimental tarnishing that typically occurs over the life of the device. Gold is the highly efficient conductor that can carry tiny currents and remain free of corrosion – ensuring a high level of reliability.
A small amount of gold is used in almost every sophisticated electronic device. This includes: cell phones, calculators, personal digital assistants, global positioning system units and other small electronic devices. Most large electronic appliances such as television sets also contain gold.
One challenge with the use of gold in very small quantities in very small devices is loss of the metal from society. Nearly one billion cell phones are produced each year and most of them contain about fifty cents worth of gold. Their average lifetime is under two years and very few are currently being recycled. Although the amount of gold is small in each device, their enormous numbers translate into a lot of un-recycled gold that might otherwise be put to better use.
As with other electronic devices, gold is used in many places in the standard desktop or laptop computer. Its ability to rapidly and accurately transmit digital information through the computer and from one component to another requires an efficient and reliable conductor and gold meets these requirements better than any other metal. The importance of high quality and reliable performance justifies its higher cost.
Edge connectors used to mount microprocessor and memory chips onto the motherboard and the plug-and-socket connectors used to attach cables all contain gold. The gold in these components is generally electroplated onto other metals and alloyed with small amounts of nickel or cobalt to increase durability.
Financial Applications: Coinage, Currency and Bullion
Because gold is so highly valued in our society and in such limited supply, it has long been used as a means of exchange or currency. Some estimates put the original transactions dating back as far as 6000 years using pieces of gold or silver. Gold was considered ideally suited for this purpose because its high value, durability, portability and easily divisible into smaller measures.
The metal was considered so valued that some early printings of paper money were backed by gold held in safe keeping for every unit of money that was placed in circulation – referred to as the “gold standard”.
The gold used as a financial backing for currency was most often held in the form of gold bars, also known as “gold bullion”. The use of gold bars kept manufacturing costs down and allowed for convenient handling and storage. Today many governments, individuals and institutions still hold investments of gold in the form of bullion.
As a matter of historical perspective, the first gold coins were minted under the order of King Croesus of Lydia (a region of present-day Turkey) in about 560 BC. Commonly used in all sorts of transactions, gold coins were the principal currency up through the early 1900’s when paper currency became a more common form of exchange. Gold coins were issued in two types of units. At that time, gold coins were denominated in dollar units of currency, while others were issued in standard weights, such as ounces or grams.
Times have changed though, today, gold coins are no longer in wide use for financial transactions. However, gold coins issued in specific weights are still considered popular ways for people to purchase and own small volumes of gold for investment.
Space & Aeronautics
Spending billions of dollars on a vehicle that will travel on a voyage where maintenance and repair will be nearly impossible means having to rely on dependable materials. Gold is central to safe space travel, for example, more than 40.8 kilograms of gold were used in the US Columbia space shuttle. Without gold, humans would have never landed on the moon. Gold sheets, approximately 0.15mm thick, are used by NASA as a radiation shield to deflect the burning heat of the sun. Without this coating, darker colored parts of the spacecraft would absorb significant amounts of heat and threaten missions and the people aboard them.
Gold is also used as a lubricant between mechanical parts. In the vacuum of space, organic lubricants would volatilize and break down due to the intense radiation. Gold has a very low shear strength so applying thin films between critical moving parts serves as an unexpected lubricant. The gold molecules slip past one another under the forces of friction to provide exceptional lubricant action.
Due to its unique chemical and metallurgical properties, gold has a vital role to play in future technologies including water purification, reducing pollution, energy consumption, and diesel emission control.
Chlorinated hydrocarbons are major pollutants of groundwater. Recent research at Rice University’s Centre for Biological and Environmental Nanotechnology revealed that bimetallic gold-palladium nanoparticles provide an active catalyst to break down trichlorethene (TCE), one of the most common and poisonous groundwater pollutants. TCE has been linked to liver damage, impaired pregnancy and cancer. This nanomaterial opens up tremendous opportunities in groundwater clean-up. In other work, researchers from the Indian Institute of Technology, have proven that gold nanoparticles, incorporated into a point-of-use water purification device, can be effective in the capture and removal of halocarbon-based pesticides from drinking water.
The US is relying increasingly on the use of coal to produce electrical power and significant levels of mercury occur in the effluent from these power plants. Control of mercury, which has been linked to Alzheimer’s disease and autism, is expected to be achieved in the US by imposed limits on mercury emissions from coal-fired boilers in the utilities industry. One method to increase mercury removal is to introduce a catalyst to enhance the oxidation of mercury and gold catalysts are proving to be very promising. Full scale trials are currently underway.
Diesel Emission Control
The recent announcement by U.S. company Nanostellar that they have developed an automotive pollution control catalyst for diesel engines that contains gold, as well as the traditional platinum and palladium ingredients, is a major step-forward in cost effective emission control.
Green chemistry, also called sustainable chemistry, is a chemical philosophy encouraging the design of industrial chemicals and processes that reduce or eliminate the use and generation of hazardous substances. The use of gold as a catalyst has a major role to play in green chemistry.
Most industrial oxidation processes tend to use chlorine or organic peroxides.
Fuel cells using hydrogen fuel are a promising clean energy source for automobiles, homes, and mobile devices. At present, platinum is generally used as a catalyst in the fuel cell. However, platinum is an extremely expensive precious metal, therefore, an important R & D theme in the fuel cell industry is reduction of material cost by minimizing use of platinum. In 2008, leading Japanese manufacturer Hitachi Maxell announced development of a new catalyst based on gold-platinum nanoparticles – see http://www.maxell.co.jp/e/release/20080327.html for more information. This success represents a large step closer to the practical use of fuel cells for applications requiring large current, such as power sources for automobiles and homes.
In Modern Medicine
Gold is used in medicine to treat rheumatoid arthritis, liver, eye and ear diseases, as well as depression. It is used in a group of drugs used to slow down rheumatoid arthritis known as DMARDs. Also, in the last few decades the properties of gold compounds have been of interest as potential cancer treatments. Particles of a radioactive gold isotope are implanted in tissues to serve as a radiation source in the treatment of certain cancers.
Radioactive gold is also used in many surgical instruments, electronic equipment and life-support devices. Gold is nonreactive in the instruments and is highly reliable in the electronic equipment and life-support devices.
Gold’s malleability, resistance to corrosion and non allergenic properties make it perfect for dental use, although its softness means that it needs to be alloyed to reduce wearing. The most common companion metals are platinum, silver and copper.
Gold is known to have been used in dentistry as early as 700 B.C. Etruscan “dentists” used gold wire to fasten replacement teeth into the mouths of their patients. Gold was probably used to fill cavities in ancient times as well, however there is no documentation or archaeological evidence for this use of gold until a little over a thousand years ago.
Gold was much more generously used in dentistry up until the late 1970’s. Its sharp price escalation motivated the search for and development of substitute materials. However, the amount of gold used in dentistry is starting to rise again stemming from the concerns that less inert metals might have an adverse effect on long-term health.
The Bottom Line and the Future of Gold
As our society requires more sophisticated and reliable materials, our uses for gold will inevitably increase. This combination of growing demand, few suitable substitutes and limited supply will cause the role and importance of gold to expand steadily over time. From its diverse and increasing number of applications like the treatment of cancer and the exploration of space – gold is truly a metal of the future.
A significant portion of the total world demand can be met through recycled material, bringing us one step closer to a greener planet without compromising on the benefits humankind stands to reap from the application of gold in technology, space, medicine, etc… There has never been a better time to consider recycling gold. It’s time we Rethink Recycle.
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