• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Method of extracting copper and gold by bacterial leaching.

Extracts from this document...


Method of extracting copper and gold by bacterial leaching The methods of extracting gold and copper have significant differences and therefore require separate attention. Prior to leaching occurring, either a tailings pile must be built up upon a base of impermeable rock or a series of holes drilled into the ore, to provide access for the bacteria?. At process one the bacteria thiobacillus ferro-oxidans and thiobacillus thio-oxidans, naturally occurring bacteria that obtain the energy that they need to survive by oxidising Fe2+ and S2- ions?, are added to the copper ore. The bacteria in the acidic leaching solution then convert the insoluble sulphide minerals into a solution containing Cu2+, Fe2+, Fe3+ and SO42- ions. The acidic solution provides the optimum pH for the bacteria to work at. Following the bacterial action, the solution is drained off of the impermeable rock or pumped out of the ground through the remaining holes and the remaining solution prepared for concentration and extraction of the Cu2+ ions. Extraction and stripping then occur, here the copper ions are selectively removed from the leaching solution by the "ligand exchange solvent extraction? ...read more.


and the gold atoms dissolve in the cyanide and the oxygen then causes the formation of sodium cyanoaurite and sodium hydroxide? which are solids and then separated from them through absorption by carbon. The extraction process for gold is different, initially froth floatation occurs to separate the tailings from the tailings and bioleaching is then carried out on the slurry of concentrate. Also the bacteria used to break down the mineral matrix surrounding the gold particles? can be different, for example sulpholobus acidocalderius was used during research by King's College Advantages and disadvantages of using bacterial leaching over traditional methods There are many advantages of using bacterial leaching which are associated with both gold and copper, for instance tailings from traditional methods and very low grade ore can be used which increases the mining company's profit and decreases the detrimental effects of mining on environmental appearance. Environmental advantages also include that the bacteria used can be recycled for reuse, decreasing expenditure. In some cases the use of bacterial leaching means that excavation need not occur because the bacteria can be pumped into holes in the ground, left to oxidise the ores and then pumped out through other holes. ...read more.


Additionally, even with no gold recovered, other metals that are recovered such as copper, nickel, cobalt and zinc produce an economically competitive mine?. Bacterial leaching is also effective over a wide range of temperatures and pHs?, meaning that it can be used throughout the world, this also applies to the financial ease of production. There are no specific disadvantages of using bioleaching to extract gold. I suggest that the reason that bioleaching is the primary extraction method of gold and only a secondary method for copper is that copper mining companies are reluctant to take into account the long production time and gold mining companies are attracted by the significantly increased recovery. Developmental stages of new mining processes prior to commercial use In order for a new mining process to become commercial, funding must be found for essential research to ensure that the process is economical for the company?. Pilot plants must be tested in locations where the mine is likely to be placed and a thorough environmental impact assessment carried out to ensure that the processes do not cause undue environmental damage?. Finally governmental permission must be obtained before commercial activity can take place?. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Living Things in their Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Living Things in their Environment essays

  1. Marked by a teacher

    Research question - Is using dogs for work ethical?

    5 star(s)

    This test was more about keeping it valid. I could have improved my experiment by making it more valid. A way I could improve it is by questioning the same amount of people with dogs as the people without dogs.

  2. Marked by a teacher

    The effects of disinfectants and antibacterial soap on bacterial growth

    5 star(s)

    Several bacterial lawns would be grown, and disinfectants sprayed directly on to the bacteria. As in real life, the cleaners would be given only a few minutes to take effect. The bacteria from those plate would then be transferred aseptically and streaked on to new sterile agar plates, and allowed

  1. Marked by a teacher

    Bacterial Leaching of Copper and Gold

    3 star(s)

    they reduce Fe3+ to Fe2+ to continue the cycle. The gold is now seperated from the ore and its solution. The process for copper is very similar. The mineral chalcopyrite CuFeS2 (pictured) follows the two stages of being dissolved and then further oxidised, with Cu2+ ions being left.

  2. Investigation - Examination of bacterial sensitivity on antibiotics.

    Antibiotics. 1st diameter (mm) 2nd diameter (mm) 3rd diameter (mm) 4th diameter (mm) Average. (mm) CD 0.8 1.6 0 0 0.6 PG 0 0 0 0 0 GM 0 2.4 0 0 0.6 T 1 0 0 0 0.25 TM 0 0 0 0 0 E 1.6 0 0

  1. The comparison of bacterial content in a range of milks.

    The use of these microorganisms with skimmed milk produces cultured buttermilk, and when cream is used, sour cream is the result. Lactobacilli carry out either a Homolactic fermentation using the Embden-Meyerhof pathway or a Heterolactic fermentation with the pentose phosphate pathway.

  2. 'The Call of the Wild' by Jack London - review

    he must do in order to survive in the freezing environment he has been sent to. He experiences his first loss when one of his fellow sled dogs is brutally murdered by the rest of the dog team. This probably symbolizes the remorselessness of some humans who kill just because someone is a bit different from themselves.

  1. Prokaryotes and Man - Bioleaching

    These bacteria are preyed upon by other, larger micro-organisms and these in turn, by invertebrates, and fish. It is the only ecosystem on earth that does not take sunlight as its primary source of energy. The earliest record of the practice of leaching is from Spain in AD 50.

  2. Copper Extraction

    mixing the copper/solvent complex with a small amount of acid. This reversible reaction depends on the concentration of H+ ions. If it is wrong, the reaction will not take place. (Ref 1) Extraction of Gold Bacterial Oxidation is the process used to extract gold.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work