Abstract

The aim of this study was to investigate the viability of light and aeration (oxygen) in cyanide attenuation of gold tailings material in a tropical environment. It was established that under aeration conditions free cyanide (CN_F) concentration reduced from 200 mg/dm³ to below 0.03 mg/dm³ in 60 h weak acid dissociable cyanide (WAD_CN) concentration reduced from 200 mg/dm³ to 6 mg/dm³ after 60 h. Under non-aeration conditions CN_F concentrations reduced from 200 mg/dm³ to 60 mg/dm³ within 108 h, the pH reduced from 10.80 to 9.41. WAD_CN concentration decreased from 200 mg/dm³ to 73 mg/dm³ within 48 h. It then increased to 150 mg/dm³ after 60 h and then gradually decreased to 100 mg/dm³ after 144 h. It was inferred that volatilisation of HCN was the dominant mechanism accounting for degradation of CN_F Degradation of complex cyanide species and this was enhanced by sunlight and aeration. It was concluded that natural cyanide attenuation is possible but the rate of degradation particularly for WAD_CN is not as fast as free cyanide. Hence it is not a suitable process for cyanide degradation in tropical environment.

Keywords:

Aeration, attenuation, cyanide, natural, sunlight, tailings dam,

References

Competing interests

The authors have no competing interests.

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The authors have no competing interests.