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Flow diagram showing how gold is processed

Interesting fact

Another method that is used to process gold is called the 'carbon-in-pulp' (CIP) method. This method makes use of the high affinity that activated carbon has for gold, and there are three stages to the process. The first stage involves the absorption of gold in the cyanide solution to carbon. In the elution stage, gold is removed from the carbon into an alkaline cyanide solution. In the final stage, electro-winning is used to remove gold from the solution through a process of electrolysis. Gold that has been removed is deposited on steel wool electrodes. The carbon is then treated so that it can be re-used.

Characteristics and uses of gold

Gold has a number of uses because of its varied and unique characteristics. Below is a list of some of these characteristics that have made gold such a valuable metal:

  • Shiny Gold's beautiful appearance has made it one of the favourite metals for use in jewelery.
  • Durable Gold does not tarnish or corrode easily, and therefore does not deteriorate in quality. It is sometimes used in dentistry to make the crowns for teeth.
  • Malleable and ductile Since gold can be bent and twisted into shape, as well as being flattened into very thin sheets, it is very useful in fine wires and to produce sheets of gold.
  • Good conductor Gold is a good conductor of electricity and is therefore used in transistors, computer circuits and telephone exchanges.
  • Heat ray reflector Because gold reflects heat very effectively, it is used in space suits and in vehicles. It is also used in the protective outer coating of artificial satellites. One of the more unusual applications of gold is its use in firefighting, where a thin layer of gold is placed in the masks of the firefighters to protect them from the heat.

Case study : dropping like a gold balloon

Read the article below, which has been adapted from one that appeared in the Financial Mail on 15th April 2005 and then answer the questions that follow.

As recently as 1980, South Africa accounted for over 70% of world gold production. In 2004, that figure was a dismal 14%. Chamber of Mines figures showed that SA's annual gold production last year slipped to its lowest level since 1931.

Chamber economist Roger Baxter says the 'precipitous' fall in production was caused by the dual impact of the fall in the rand gold price due to the strong rand, and the continued upward rise in costs. Many of these costs, laments Baxter, are 'costs we do not have control over'. These include water, transport, steel and labour costs, which rose by 13% on average in 2004.

He provides a breakdown of the cost components faced by mines:

  • Water prices have risen by 10% per year for the past 3 years
  • Steel prices have increased by double-digit rates for each of the past 3 years
  • Spoornet's tariffs rose 35% in 2003 and 16.5% in 2004
  • Labour costs, which make up 50% of production costs, rose above inflation in 2003 and 2004

At these costs, and at current rand gold prices, about 10 mines, employing 90 000 people, are marginal or loss-making, says Baxter.

Questions & Answers

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Newton's first law of motion
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Source:  OpenStax, Siyavula textbooks: grade 11 physical science. OpenStax CNX. Jul 29, 2011 Download for free at http://cnx.org/content/col11241/1.2
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