EJMP&EP





A case study of CIP tails slurry treatment: comparison of cyanide recovery to cyanide destruction

G.P. Demopoulos* and T.C. Cheng

Department of Mining, Metals and Materials Engineering, McGill University, 3610 University Street, Montreal, QC, H3A 2B2 Canada


Received 28 September 2002; accepted 10 April 2004




ABSTRACT

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.


Keywords: Cyanide; Gold; CIP tails; Effluent treatment



* Corresponding author
   E-mail : george.demopoulos@mcgill.ca