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A case study of CIP tails slurry treatment:
comparison of cyanide recovery to cyanide destruction In
this paper two cyanide recovery/destruction technologies, namely the Cyanisorb process and
the INCO SO2/Air process, are evaluated for the treatment of waste cyanide
effluents from a gold mill of 12,000 tonnes of ore per day capacity. The comparison is
made for CIP tails slurry of variable concentrations of free and weakly-complexed cyanide.
Both direct treatment of the slurry prior to its discharge to the tailings pond, and
treatment of the tailings pond discharge water are considered. After a brief description
of the two technologies, order-of-magnitude capital and operating cost estimates are
presented for several treatment options. It is concluded that: (i) the treatment of the
tailings pond discharge water (by cyanide destruction) is the most economical of all
options; (ii) the capital cost of cyanide recovery is relatively high, thus for this
technology to be economically competitive, the level of recoverable cyanide in the CIP
tails must be high (at least 200ppm); (iii) cyanide recovery alone cannot meet the
environmental standards of less than 1ppm CNT. Secondary treatment of the effluent by one
of the cyanide destruction technologies most likely will be required following cyanide
recovery; and finally (iv) concerns over cyanide use and management in certain parts of
the world are expected to render cyanide recovery increasingly more attractive. |
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