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

bacterial leaching

Extracts from this document...

Introduction

CHEMISTRY OPEN BOOK Bacterial leaching is used to extract certain metals from its ores via bacteria. The old fashion way of doing this was by smelting and roasting which is quite expensive, and requires an adequate amount of concentration in its ore. The low concentration doesn't prove to be a problem for bacteria as the micro-organisms gains energy from breaking down minerals into there constituent elements. Process of extracting gold and copper using bacterial leaching: iron and sulphur oxidising - acidophilic bacteria are able to oxidise certain sulphidic ores containing encapsulated particles of gold, making it easily accessible. The process is shown below. The process of extracting of gold happens in a two stage process. The bacteria catalyse the break down of the mineral arsenopyrite FeAsS by oxidising the sulphur and metal arsenic to higher oxidation states, which simply means that the sulphur and arsenic (loose electrons thus making them positive ions), whilst reducing oxygen (this is the gain of electrons by an atom) ...read more.

Middle

Extraction from the Mixture using bacterial leaching Copper (Cu2+) ions are removed from the solution by ligand exchange solvent extraction which leaves other ions in the solution. Ligand - is an atom, ion or functional group that is bonded to one or more central atoms or ions, usually metals generally through co-ordinate covalent bond. A lot of such ligands around a centre are termed a complex. The copper is removed by bonding to a ligand, which is a large molecule consisting of a number of smaller groups each possessing a lone pair. The ligand is dissolved in an organic solvent such as kerosene and shaken with the solution producing this reaction: Cu2+(aq) + 2LH(organic) -> CuL2(organic) + 2H+(aq) The ligand donates electrons to the copper, producing a complex - a central metal atom (copper) bonded to 2 molecules of the ligand. Because this complex has no charge, it is no longer attracted to polar water molecules and dissolves in the kerosene, which is then easily separated from the solution. ...read more.

Conclusion

Environmental advantages also include that the bacteria used can be recycled for reuse, decreasing expenditure. Some environmental disadvantages are associated with bacterial leaching including that heavy ions such as iron, zinc and arsenic, can leak out of the mine during draining, forming an ionic precipitate when diluted by fresh water. Bacterial leaching requires little labour so it's profitable compared to the Traditional methods. Sulphur dioxide is not released in bacterial leaching and doesn't need high temperatures to run Development stages of new mining process Bacterial leaching is used a secondary for copper as it is extracted too slow and the companies can't profit at all-because the metal recovery may take decades. Bacterial leaching is used as primary extraction for gold: the arsenic produces is non toxic and greater % of gold is extracted by bacterial leaching. A lot of research has gone into to find to find best bacterial culture and conditions. A lot of funding has gone into developing the pilot stages. 'Research at BacTech quickly progressed from 450 dm3 laboratory plant then to a 32m3 transportable pilot plant. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Inorganic Chemistry 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 AS and A Level Inorganic Chemistry essays

  1. Peer reviewed

    Determining the concentration of acid in a given solution

    5 star(s)

    Concentration (mol dm-3) = Moles / Volume (dm3) Concentration of sulfuric acid: 0.00253 / (24.6/1000) = 0.10285 mol dm-3 I will round the concentration of sulfuric acid down to 0.103 mol dm-3 (3 sig figs) Evaluation 7, 8 Procedural Uncertainties There are lots of possible errors that could have occurred whilst I was doing the experiment.

  2. Peer reviewed

    Analysis of sulphur dioxide content in wine.doc

    4 star(s)

    Besides wine, sulphur dioxide and its salts are widely used to preserve dehydrated fruits and vegetables, fruit juices and syrups. Sulphur dioxide is a poisonous gas with pungent smell. When ingested, sulphur dioxide and its salts attack the respiratory system and make the individuals who suffer from bronchitis and asthma get worse.

  1. effects Concentration and Temperature on the Rate of Reaction

    Numbness. Convulsion. Collapse. Coma. Death. Protective gloves. Protective clothing. Remove contaminated clothes. Rinse skin with plenty of water or shower. To remove substance use polyethylene glycol 300 or vegetable oil. Refer for medical attention. Wear protective gloves when administering first aid. Contact with eyes Pain. Redness. Permanent loss of vision.

  2. Chemistry notes - Chemistry of Natural Resources, Elements from the Sea, Ions ...

    Chlorine also cannot be stored to its high toxicity, and so it is transported by rail or road as a liquid. Bromine is transported in lead-lined steel tanks, through a planned route to minimise accidents. Electron Structure Electrons exist in shells, and are designated in increasing energy levels.

  1. Aim To study the effect of concentration of iodide ion ...

    After weighing, the weighted mass of KI solute was diluted with distilled water to produce 500 cm3 of standard KI 1.0 mol dm-3 solution. 2. A dilution was then performed using the standard KI solution as stock solution. For concentration 0.8 mol dm-3, 80 cm3 of stock solution was transferred into a 100 cm3 container using a burette.

  2. Winning a Metal from it's Ore

    When the color change is complete, allow the crucible to cool to room temperature and re-mass. Record the mass of the CuO product and crucible in your data table. Part 2 1. While the contents are cooling, measure out 0.50 gram of carbon black.

  1. Aluminium and its Extraction

    The transformer generates a current from 220kA to 340kA, with a voltage of 1-2kV from 110kV; this shows how strong the bonds are between the aluminium and oxygen ions, as a large amount of electrical energy is used. The solid aluminium that is formed is denser than the molten cryolite (at 1000oC)

  2. The preparation, analysis, and reactions of an ethanedioate complex of iron

    The interaction of aqueous solution of iron(III) chloride and the complex with the above added reagents was compared. Results: Mass of ammonium iron(II) sulphate used= 10.53g Mass of diluted sulphuric acid used=5.08g Mass of potassium oxalate monohydrate used = 7.49g Mass of oxalic acid dihydrate used= 2.503g Mass of

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