David Killick wrote: Heap leaching requires huge amounts of acid, and I
have been wondering where
it comes from now that sulphide smelting is very much out of fashion.
Low grade and tailings dumps have been treated to extract copper by heap
leaching using the organism 'thiobacillus ferro oxidans' as a catalyst to
promote aerial oxidation. I think the process has been improved in a
number of ways to include better exposure of the heap to air and to recover
copper from solution. Originally, scrap iron was used to cement out
copper following a process which has been used from the C19th or before.
In the 1960s, solvent extraction using various chelating agents has been
developed. The latter have also been used in connection with
roast/leach/electrowin processes where the acid was derived directly from
the ore.
Regards
Richard
Richard Smith
3M UK Bracknell, B2-3N,
Environment, Safety and Security [log in to unmask]
Tel: 01344-858154 (Trim. 8-230-2154)
Fax: 01344-858367 (Trim. 8-230-2367)
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