Aeration

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The process of supplying or impregnating soils or liquids with air. Air contains oxygen and carbon dioxide, both important reagents in bioleaching.

Aeration of heaps

In many cases air is actively blown into the heap by perforated piping connected to fans installed near the bottom. Air is also passively drawn into the reactor as a result of the liquid flow. Oxygen is often a limiting reagent in the heap bioleaching processes and therefore aeration may increase leaching rates but is a way to control the temperature in the heap as the leaching reactions are either endo- or exothermic.

"Initially heap/dump plants relied on natural advection but this was found to be inadequate.

In recent years plants have moved to air injection. As the heaps/dumps are usually very big this has to be done in as economical a way as possible. The general solution has been to blow low pressure (typically 1-3 psi) air through corrugated HDPE pipes buried in the ore or in inert overliner material under the ore. In a typical industrial application the pipes are long, upwards of 500 m in big plants, and have air holes every 1-4 m along the length of the pipes in order to distribute air in the heaps/dumps. The air holes are usually small (1-4 mm) and the experience of the applicant is that the holes tend to become blocked very quickly. Blocking of air holes is caused by fine solids and precipitates/crystals which are carried to the air pipes by the leach solutions percolating through the heap/dump. "

Source: [1]

References

  1. http://www.freepatentsonline.com/7314066.html
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