Bioleaching reaction

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The overall summary reaction is as follows:
The overall summary reaction is as follows:
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4FeS<sub>2</sub> + 15 O<sub>2</sub> + 14 H<sub>2</sub>0 → 4Fe(OH)<sub>3</sub> + 8 H<sub>2</sub>SO<sub>4</sub>
+
4FeS<sub>2</sub> + 15O<sub>2</sub> + 2H<sub>2</sub>0 → 2Fe<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + 2H<sub>2</sub>SO<sub>4</sub>
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Pyrite + Oxygen + Water → Ferric Hydroxide + Sulphuric Acid
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Pyrite + Oxygen + Water → Ferric Sulphate + Sulphuric Acid

Revision as of 10:17, 19 June 2007

The overall summary reaction is as follows:

4FeS2 + 15O2 + 2H20 → 2Fe2(SO4)3 + 2H2SO4

Pyrite + Oxygen + Water → Ferric Sulphate + Sulphuric Acid


Leaching mechanisms
Leaching mechanisms
Some of the stages of RISC oxidation can be catalysed by MO:s.
Some of the stages of RISC oxidation can be catalysed by MO:s.
The leaching of sulfides would stop after a while if the leaching-chemical ferric iron was only consumed. Without ferric iron the thiosulfate or poly-sulfide mechanisms can't proceed.
The leaching of sulfides would stop after a while if the leaching-chemical ferric iron was only consumed. Without ferric iron the thiosulfate or poly-sulfide mechanisms can't proceed.
To recycle ferric iron from ferrous iron, a very powerful oxidising agent will be needed, even more powerful than ferric iron itself. Oxygen is the only electron acceptor able to spontaneously oxidise ferrous iron. This spontaneous reaction is very slow at low pH. But at a pH below 4 prokaryotic MO:s can use the oxygen to speed up the regeneration of ferric iron out of ferrous iron.
To recycle ferric iron from ferrous iron, a very powerful oxidising agent will be needed, even more powerful than ferric iron itself. Oxygen is the only electron acceptor able to spontaneously oxidise ferrous iron. This spontaneous reaction is very slow at low pH. But at a pH below 4 prokaryotic MO:s can use the oxygen to speed up the regeneration of ferric iron out of ferrous iron.
Then, since ferric iron is regenerated, the leaching of metal sulfide can continue leaching of metal sulfide can continue. This reaction is considered to be rate-limiting for oxidative dissolution of pyrite by ferric iron.(Singer & Stumm 1970, Moses & Herman 1991).
Then, since ferric iron is regenerated, the leaching of metal sulfide can continue leaching of metal sulfide can continue. This reaction is considered to be rate-limiting for oxidative dissolution of pyrite by ferric iron.(Singer & Stumm 1970, Moses & Herman 1991).
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