• 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...

Introduction

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.

Middle

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.

Conclusion

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)

    that took my questionnaire also believed that. They sometimes show human behaviours because they have similar instinctive behaviour (reproducing & wanting freedom), and they also have the same emotions. Dogs can cry just like humans when they are sad. All/both of the people who had a dog said that they cried.

  2. Marked by a teacher

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

    5 star(s)

    The slide should then be rinsed with alcohol and counterstained with a pink dye called safranine. The cell walls of gram-negative bacteria have a very low affinity for the violet stain, which is rinsed out by the alcohol. Once counterstained with safranine, however, the gram-negative bacteria appear bright pink to red.

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

    A machine heats the milk to over 71?c for at least 15seconds, then quickly cools it to below 10?c. If not treated, the natural bacteria in milk will turn sour, especially in warmth and light. Pasteurized milk is safe to drink and should 'keep' for several days if kept cool;

  2. 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

  1. 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.

  2. Investigation - Examination of bacterial sensitivity on antibiotics.

    (iii) Any scratched or cracked glass wear like boiling or test tubes should be disposed. This is because this might lead to you cutting yourself and and therefore microorganisms penetrating your body. (iv) Alcohol is highly flammable and therefore use it in small quantities and away from the naked flame. (v)

  1. Copper Extraction

    As emission limits were being established by environmental agencies, bacterial leaching becomes desirable due to its very low polluting effect. It can turn piles of tailings from previous mining into valuable sources of copper. It is possible to mine like this without actually mining huge networks of tunnels, as the leaching solution can be pumped underground.

  2. The extraction of metals from their ores using micro-organisms.

    The rest of the leaching solution has Thiobacillus ferro-oxidans added to it to catalyse the oxidation of Fe2+ ions into Fe3+ ions, this solution can then be reused, and so the process starts again. In the mean time the solution containing the Cu2+ ions are added to a ligand, this

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