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

Biohydro-metallurgy is a new field, which combines metallurgy and biotechnology.

Extracts from this document...


Chemistry Open Book Paper Biohydro-metallurgy is a new field, which combines metallurgy and biotechnology. It is used in the extraction of metals from their ores using bacteria. The method used, referred to as bacterial leaching/ bacterial oxidation, can be used to extract copper and gold from their ores. In the extraction of copper, the bacteria Thiobacillus ferro-oxidans and Thiobacillus thio-oxidans are used. These bacteria live by obtaining energy from the oxidation of Fe2+ ions and S2- ions, as seen below: Fe2+ ? Fe3+ + e- S2- + 4H2O ? SO42- + 8H+ + 8e- (equations from Chemical Storylines) This is useful when extracting copper, as S2- ions are present in insoluble minerals of copper. When the bacteria oxidise the S2- ions, copper ions are released into the solution. They can then be extracted from the solution. When applied to copper production, a simple method is followed. The rocks to be leached (usually low grade ore and tailings) are piled up over an area with impermeable ground- in order that the solution formed may easily be drained. ...read more.


The copper ions are then extracted from the solution by an 'electro-winning' process. An electric current is passed through the solution and the copper is collected on the negative electrodes. The process can be seen in the diagram shown below (from Article 1): The bacterial leaching process has proved better than the original method of smelting the ores in many ways. Smelting 1 tonne of copper ore produces 2 tonnes of sulphur dioxide. Bacterial leaching does not form any polluting waste. This is not only beneficial to the environment, but it also means that firms will not have to pay due to restrictions on sulphur dioxide emissions. It is also a much cheaper process. Biohydro-metallurgy costs less than �70 per tonne, whereas smelting copper ore costs �130-�200 per tonne. Also, biohydro-metallurgy enables even low-grade ore and tailings to be used, and therefore cuts down on this polluting factor. It also provides a method of underground mining, without environmental damage. Unfortunately this process is extremely slow and therefore is not profitable. ...read more.


oxide, both of which are polluting and have unwanted economic implications. However this method produces no gases and the waste water produced can be treated to remove the impurities as precipitates and can be neutralised by crushed limestone. There is the possibility that acid rain or river water may react with the waste water and dissolve the arsenic(V). However, 'the highest concentration of arsenic in such waters does not reach the US Environmental Protection Agency limit of 2 ppm'- (Article3, Box1) and can therefore be seen as safe. The factor most in favour of the new method is the fact that the cost of running the plant is roughly only $30 per tonne of concentrate. This includes power, chemicals, maintenance and labour. Here is where a problem may arise. Only one person is needed per shift. This means that many people will lose jobs. Another advantage of the bacterial method is that other base metals are recovered during gold extraction. This alone 'is feasible and economically competitive with conventional process'- (Article3) ...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. Investigating the effect of four antibiotic agents on gram positive and gram negative bacteria.

    * Replace the base of the petri dish. * Flame the wire loop to get rid of any remaining bacteria. * Label the petri dish with name, date and the name and batch of the bacteria used. DIAGRAM OF FULL LAWN Method 3- Transferring the antibiotic agents to the inoculated agar plates.

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

    Due to the school timetable this will prove difficult. 4. The human factor in this experiment is also a main variable as it is the human eye that observes when the end-point is detected. Having the same person observing the end-point each time eliminates some of the inaccuracy.

  1. Science Chemistry Casestudy

    contaminated by pesticides, animals can also be exposed to pesticides by breathing pesticide spray, or absorbing pesticides through their skin. Eating other animals that have been exposed to pesticides can poison predators such as hawks and owls. [5] * What health problems are associated with exposure to pesticides?

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

    Also because of the high temperatures, aerobic organisms use the oxygen at a more rapid rate leading to more species dying due to competition for oxygen. Pesticides are used by farmers to protect crops from pests. Just with fertilisers they also run off into the river.

  1. Chemistry Open Book Paper - Biohydro-metallurgy.

    and arsenic (III) are oxidised. A prime example of biohydro-metallurgy is the extraction of copper, often used as a recovery technique, extracting the metal from low-grade ores that are the waste product of any conventional mining. The ore is piled up in an area where the ground has been made

  2. Mining for Gold and Copper using Biohydrometallurgy.

    These ions are present in copper minerals and when they are oxidised, the copper ions are released into a solution. After it is drained, the next stage is when copper (Cu2+) ions are removed from the solution by ligand exchange solvent extraction which leaves other ions in the solution.

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

    traditionally 2 tonnes of gas are produced for every tonne of copper?. Another advantage is that ligands allow concentration of the copper ions before electro-winning?, decreasing the volume of waste solution at the end of the process. The major disadvantage of using this method is that it can take decades

  2. Copper Extraction

    As gold is found within minerals and in very small amounts, the mineral reduces the yield of gold. So, bacterial oxidation is used to remove the mineral matrix by oxidation. Once the gold is in residue, it can be recovered by cyanidation.

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