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

The use of Micro-organisms to extract metals from their ores.

Extracts from this document...


The use of Micro-organisms to extract metals from their ores In 1752, a stream of blue-green liquid running from excavated rock at the Rio Tinto mine, was noticed, which when passing over old iron implements, left a brown film. On scraping this film off, it was pure copper. Initially, they thought, the copper ions were being leached from the ore-crushing waste by inorganic chemical reactions, such as those used to extract metals from their ores. In 1947, microbiologists discovered that this transformation was due to micro-organisms. Thiobacillus thio-oxidans obtain their energy through oxidising S2- ions. They are present in insoluble minerals of copper, zinc and lead. Their oxidation by bacteria releases metal ions into solution. Humans require an expensive, high temperature smelting process to achieve similar results. In the 1980s, the exhaustion of high-grade ores and the decreasing copper prices caused the failing of the copper industry. They turned to cost effective and less polluting technologies. ...read more.


An acidic leaching solution, containing bacteria is pumped down the central hole. Pumped from the other holes is the resulting solution, rich in copper ions. The miners are reluctant to use biological processes due to their slowness. They have finally been applied to low-grade ores where traditional methods aren't cost-effective. If metals could be extracted from lower grade ores, tailings sites could be transformed into sources of raw materials instead of pollution. Research on biological techniques of metal extraction is rare, but experts see environmental regulations as key to encouraging research. This is rejected by the mining industry, arguing that it has always been advancing research barriers, searching for new techniques e.g. they funded the biohydrometallurgy research. If society wants the mining industry to protect the environment, they must accept higher prices. Gold mining is risky, after finding deposits, the gold's extraction is also difficult. Roughly 30% of the world's gold reserves occur as microscopic particles of gold encapsulated in a mineral matrix. ...read more.


Equation 3 2nd stage: separate oxidation reactions: Fe(II) Fe(III) Equation 4 As(III) As(V) Equation 5 Wastewater is treated with limestone, neutralising the sulphuric(VI) acid, causing the precipitation of iron(III) arsenates, FeO(OH) and CaSO4.2H2O. Possibly, the precipitated material and dissolve arsenic(V) into water, but the highest concentration in such rivers doesn't reach the US limit. They couldn't progress beyond the 1dm3 reaction vessel before the technology was sold to BacTech, who progressed to a 450 dm3 laboratory plant, then to a 32 m3 transportable plant which was used for test runs around the world, giving excellent results under varied conditions. 11 years later, the first full-scale plant using this process was commissioned. The mine operated as an open-cut until 1992, when accessible oxide layers became uneconomic. In 1993, underground mining allowed access to the deeper layers. The mining process can be seen in diagram 4. The cost of running this plant is low because they use locally Quarried calcrete to neutralise effluent and the oxidised concentrate. Other reagents are bacterial nutrients, mainly in the form of ammonium phosphate. Recent work shows that bacterial recovery of base metals is feasible and economically competitive. Diagram 2 ...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)

    The question was a yes or no question, so there had to be one answer. The 4 out of the 5 people who said that it was appropriate probably knew that cosmetics (something that doesn't improve the human health) were also tested on animals, but said 'yes' because animal testing had done more good than bad.

  2. Marked by a teacher

    Taxonomy is the branch of biology that deals with the identification and naming of ...

    5 star(s)

    Bacteria are classified by their physical form and shape. For example spherical shaped bacteria are known as cocci, rod-shaped bacteria are known as bacilli, spiral shaped bacteria are know as spirillum and comma shaped bacteria are known as vibrio. Even though bacteria are unicellular, they may not always appear as single cells.

  1. Should cannabis be legalised in the UK?

    The purpose for which it chiefly established itself, however, was as a sedative and hypnotic, in which role its superiority to the opiates was established to the satisfaction of many physicians, notably Suckling(18) and Mattison(21). According to Suckling: With a wish for speedy effect, it is so easy to use that modern mischief-maker, hypodermic morphia, that they (young physicians)

  2. Early Humans?

    posteriorly located sagittal crest and a large nuchal crest; large mastoid process; relatively small incisors; upper canines longer mesiodistally than buccolingualy; no diastema; and the enamel thickness of the cheek teeth intermediate between Pan and Australopithecus (Brunet et. al., 2002).

  1. Mining for Gold and Copper using Biohydrometallurgy.

    Then a mixed culture of moderately thermophillic bacteria from certain samples was introduced. This culture became effective over a wide range of conditions such as temperatures, pH, water salinity and arsenic concentration. Researchers found out that the bacteria worked best at 46 oC (if the temperature is to high, enzymes

  2. Natural Defence Barriers.

    Physical Defences - The skin provides the ultimate all over protection. This physically stops the entry of bacteria. The skin is a combination of dead and living cells. The dead skin cells sit on top of new skin cells protecting it.

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

    * Exponential or log phase-population increases rapidly. Eventually the carrying capacity is reached-maximum population than an environment can hold * Stationary phase-bacterial cells dying more or less at the same rate as they were produced. The population encounters limiting factors in the form of nutrient depletion-fall of pH as CO2 etc accumulates.

  2. Investigation - Examination of bacterial sensitivity on antibiotics.

    (viii) Forceps (ix) Bunsen burner. (x) Sticky tape. (xi) Eye protection. (g) Method: (i) Take three petridishes and using the marker pen, mark each dish with your name, time and date, and the type of bacteria. (ii) Take one bottle of the samples of bacteria you want to inoculate e.g.

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