The use of ion exchange resins for the treatment of cyanidation tailings. Part 2--pilot plant testing

This article reports the results of a pilot plant test on the use of ion exchange resins for the treatment of cyanide contaminated liquors arising from gold cyanidation. The tests were conducted on 14,000 m3 of contaminated liquor, leftover from a previous operation in a gold mine in Australia. Prior to treatment, the liquor contained 45-65 mg/l CNTOT (total cyanide). Purolite A500 strong base ion exchange resin was used to adsorb cyanide species from the liquor. After adsorption, an oxidative acid eluent containing H2O2 and H2SO4 was used to regenerate the resin. The treatment reduced the cyanide contamination in the liquor to less than 2.5 mg/l CNTOT. Precious metals in the liquor were recovered and the revenue from precious metals contributed to offset the cost of cyanide detoxification. Base metals in the contaminated liquor were concentrated in the spent eluent stream. Resin deterioration, marked by a gradual reduction of the loading capacity of the resin was observed, most likely due to the precipitation of copper-iron cyanide on the resin. The deterioration of resin is drawback of this process and could hinder commercialisation of it. Hence further work should be undertaken to determine techniques to minimise the deterioration of resin.