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Biohydrometallurgy is an application in mining.

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Introduction

Biohydrometallurgy "Biohydrometallurgy is an application in mining. In its natural state a metal such as copper is found combined with other elements in the mineral chalcopyrite. A bacterium is then used to form the compound copper sulphate (CuSO4), which in turn can be treated chemically to obtain pure copper. This microbiological mining process is used only with low-grade ores and currently accounts for 10% of copper production world-wide." Copper can be extracted from its ores by using bacteria. This is done by, firstly the low-grade copper ore and also the tailings (left from an earlier traditional mine) are stacked up where the ground has been made impermeable. The ground is then sprayed with the acidic leaching solution (T. ferro oxidans and T. Thio-oxidans). This solution is used because the bacteria used, thrive in acidic conditions and they also don't need any organic material on which to feed. The bacteria require Fe ions, or S ions, oxygen and carbon dioxide. The bacterium may also need bacterial nutrients containing nitrogen and phosphorus. ...read more.

Middle

Cyanidation of the final and resulting extract led to a breakthrough, in which the gold recovered increased from 10% to 100%. More research was carried out, as funding became available. A student called Ali Nobar introduced a mixed culture of moderately thermophillic bacteria from certain samples. This culture became effective over a wide range of conditions such as temperatures, pH, water salinity and arsenic concentration. Research found out That the bacteria worked best at 46 degrees c (if the temperature is to high the bacteria cell will became denatured due to a higher temperature) and in solutions with a pH of between 0.5 and 1.5. These greatly enhanced the percentage of gold extraction A graph to show the enhancement of gold recovery using bacteria Key Cyanidation alone Bacterial oxidation followed by cyanidation This new process has many advantages and disadvantages. One of the main advantages of this process is that it cost much less than the traditional method. Mining copper by the traditional method can cost between $130 and $200 per tonne. ...read more.

Conclusion

Also when using the traditional method when extracting copper, more copper can be obtained from the ore. The bacterial process of extracting gold is used as a primary process (secondary process is the traditional method) because the research and technology has been developed fast. More economic because more gold is produced so more money to be made. There is also a low cost of running the plants. Also the whole process is more feasible and economically competitive with the conventional process. For a new process for bacterial leaching to become commercial the government and political powers must approve and also regulate a new process and may need to provide funding. A Political power may need to hold an enquiry into the effects of this new technology to check if it is mandatory and safe. Thus granting permission for the new technology to go ahead. Summary This type of bacterial chemistry in order to obtain metal from its ore is a new technology but the industry is still yet to recognise it. Its main advantage is it cheap and mostly environmentally friendly compared to traditional methods. This type of process will lead us into the future. ...read more.

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