Cyanide removal and recovery of gold mine tailings

Cyanide is a hazardous chemical used in gold mining to dissolve gold and form a solution that can be easily extracted. However, the use of cyanide poses a significant threat to the environment and human health, especially when it is not properly managed. To reduce the impact of cyanide on the environment, many gold mines implement cyanide removal and recovery techniques.

The process of removing cyanide from gold mine tailings involves several steps, including detoxification, degradation, and precipitation. One common method of detoxification is to use hydrogen peroxide, which reacts with cyanide to form less toxic compounds. Another method is to use sodium metabisulfite, which converts cyanide to cyanate, a less toxic compound. The degraded cyanide can then be further treated by various oxidation processes or biodegradation to reduce its toxicity.

Cyanide recovery is also an important process in gold mine tailings management. Recovering cyanide from the tailings not only reduces the amount of cyanide released into the environment but also reduces the cost of reagent procurement. One commonly used method for cyanide recovery is the carbon adsorption process, which involves the adsorption of cyanide onto activated carbon. The loaded carbon is then sent to a stripping process where the cyanide is desorbed from the carbon and recovered as a concentrated solution.

Other methods of cyanide recovery include the Merrill-Crowe process, which involves the precipitation of gold and silver from the cyanide solution using zinc, and the resin-in-pulp (RIP) process, which involves the adsorption of cyanide onto a resin followed by desorption with a concentrated sodium hydroxide solution.

In conclusion, cyanide removal and recovery techniques are essential in gold mine tailings management to reduce the environmental impact of cyanide and to recover valuable reagents. The selection of a suitable cyanide removal and recovery method depends on factors such as the concentration of cyanide in the tailings, the desired level of detoxification or recovery, and the cost-effectiveness of the method. Proper implementation and management of these techniques can ensure a safer and more sustainable gold mining industry.