Heap Leaching
 A
process used when gold and silver mineralised crushed ore is placed on an
open air pad in a heap.
The
cyanide leaching solution is sprayed down onto the heap of crushed
ore
which then trickles/percolates down through the ore, dissolving the precious
metals. The cyanide solution becomes a
www.rpi.edu/.../ Biotech-Environ/LEACH/heap.htm
'pregnant' solution which is
collected in a pond, or pregnant pond. The precious metals are then
recovered from the pregnant solution and the
cyanide
is recycled and re-used again in the heap leaching process, which can take
several weeks.
The heap leaching technique has been very successful since the 1970's,
allowing economical
extraction from low
grade
deposits, however the recovery rate for this process is only around 60%.
see
also
Biological leaching
Diagram (above) illustrating the heap leaching process where
gold is recovered using the
carbon-in-pulp
method.
Diagram (above) of a similar process for copper extraction.
electrochem.cwru.edu/ ed/encycl/art-m02-metals.htm
 back
to top |
