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

Mining with Microbes.

Extracts from this document...

Introduction

Mining with Microbes A new method of extracting metals from their ores is being developed that is more, than others before. This alternative technique uses Thiobacillus ferro-oxidan and Thiobacillus thio-oxidan bacteria to leach metal elements from their ores. These bacteria live by oxidising ions found in insoluble minerals of copper. When the bacteria oxidise the S2- ions in the copper mineral, the valuable metal ions are left in solution, from which they can be removed. The microbes work best in acidic conditions (pH 2-3) and in a warm temperature (20-55oC). Firstly, the tailings of ore from previous copper mining are laid on an impermeable. The bacteria are then sprayed onto the piles of ore, in an acidic solution, and left to work. The Thiobacillus ferro-oxidan and Thiobacillus thio-oxidan (T. ferro- and T.thio-oxidan) microbes oxidise S2- and Fe2+ ions thus releasing the copper into solution. The equations for the reactions the bacteria use to live are summarised below: Fe2+ � Fe3+ + e- and S2- + 4H2O � SO42- + 8H+ + 8e- This results in the release of Cu2+ ions into solution: ...read more.

Middle

arsenates, iron oxohydroxdide and gypsum to form a gelatinous precipitate. 397 The gold is then extracted from this mixture using a process called cyanidation. In cyanidation, metallic gold is oxidized and dissolved. The oxidant employed is atmospheric oxygen, which causes the dissolution of gold and the formation of sodium cyanoaurite and sodium hydroxide. The reaction involved with this process is as follows: 4Au + 8NaCN + 2H2O + O2 � 4NaAu(CN)2 + 4NaOH When gold dissolution is complete, the gold-bearing solution is separated from the solids and the gold can be removed by electrolysis. The main advantage of using bacteria to oxidise insoluble ions and release metal ions into solution is the benefit to the environment. During traditional copper extraction, the ore is smelted at very high temperatures, the sulphur in it is converted into sulphur dioxide. This waste gas is the main contributor to acid rain, which in the past before sulphur dioxide emissions were strictly regulated caused major damage to lakes, forests and buildings. ...read more.

Conclusion

It is possible that that acidic rain or river water may slowly dissolve arsenic(V) and release into the water. However, it is unlikely that the concentrations will reach hazardous levels. One reason why microbes are used as a primary extraction process for gold and not copper is the speed at which the microbes work. Companies are hesitant adopt the technology as they will not see the benefits for a long time. Gold however, is much more valuable, so profit can be made although the process takes more time. A new mining process like bacterial leaching must go through several stages before it can operate commercially. Firstly the technology has to be developed on a laboratory scale. Then plans to apply it to field locations have to be produced as well as larger scale prototypes. When the process is well refined (i.e. what works best at what temperatures, pH, pressure e.t.c) the technology has to be applied full scale. Then the necessary adjustments made to previous plants, or new plants constructed. Only when the new process is working effectively and making a profit will the adapted 999 or new plants be operating commercially. 1 Gareth Johns ...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)

    1.Yes- they are honest 2.Yes 3.Yes 4.Yes 5.Yes Examples of dogs having human characteristics & behaviours: 1. A dog once died a few weeks after its owner died 2. Paris Hilton dresses up her Dog to look like her- and they have a conscience 3.

  2. Marked by a teacher

    What is Biotechnology? Discuss the use of genetically modified microbes to make new ...

    4 star(s)

    Obviously organisms that we consume are used, e.g. cattle, but biotechnology would be an extremely limited science if it were not for microbes. Microbes include organisms such as Fungi, Bacteria and Viruses. They not only provide the foundation for much of the basic research involved in biotechnology, they help to

  1. Investigation - Examination of bacterial sensitivity on antibiotics.

    grown under optimum conditions in nutrient media in fermentation tanks holding several thousand gallons. The mold is strained out of the fermentation broth, and then the antibiotic is removed from the broth by filtration, precipitation, and other separation methods. In some cases new antibiotics are laboratory synthesized, while many antibiotics

  2. Investigating the effect of four antibiotic agents on gram positive and gram negative bacteria.

    * Discard the empty flask and the plug into disinfectant. * Leave the plates for approximately 15 minutes to solidify. Method 2- Inoculating the agar plates with bacteria * Sterilise the bench with Virkon solution and wash hands. * Set up a Bunsen burner with a roaring flame and place the petri dishes upside down on the bench.

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

    The raw milk will have the higher amount of bacteria present at all times. Null hypothesis There will be no difference between the amounts of bacteria in the whole, semi-skimmed, and UHT milks, and equally no difference between their spoiling rates.

  2. Rain forests.

    An individual tree in a South American rain forest may support more than 40 species of ants. Scientists have counted about 1,200 species of beetles living in only 19 tree crowns from Panama. Plants and animals in the rain forest depend on one another for survival.

  1. An Investigation into the water quality of the River Banwell in

    Even small amounts of pesticides can be lethal as they accumulate in body fat deposits. This is dangerous as these move up the food chain, when these deposits are used they are released inside the body. As these pesticides go up the food chain they become more concentrated causing more harm than at the lower trophic levels.

  2. Method of extracting copper and gold by bacterial leaching.

    Economical disadvantages include that the process is lengthy in comparison to traditional methods, causing cash flow problems in new plants. Some specific advantages and disadvantages apply, for example the greatest advantage of using bacterial leaching to extract copper over smelting is that no sulphur dioxide is released into the atmosphere,

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