Deadly chemicals can be a gold mine

Nov. 20 2020

Even the word cyanide conjures up fear and images of toxic chemical seeps for the majority of us who fortunately have never even come in contact with it. It derives its fearsome reputation from the fact that it is a rapidly acting, and potentially deadly chemical.

In the mining industry it has been an important component of the gold (and precious metal) extraction process since the late 1800s. Sodium cyanide (NaCN) is used in the milling of high grade ores and also for extracting gold from low-grade ore by converting the gold to a water-soluble complex. Production of reagents for the mining sector accounts for approximately 13% of cyanide consumption globally.

Gold will dissolve in an aqueous solution of cyanide, allowing it to be separated from the ore it is found in. Once in solution, the gold can then be recovered from the cyanide solution through a process that typically involves activated carbon. The gold cyanide complex is adsorbed onto the carbon creating a particle large enough that it can be separated using wire mesh.

Once the gold is removed, the cyanide that remains in the tailings from the milling process, or any seepage from heap leach facilities, is potentially hazardous. The majority of mining companies globally have adopted the International Cyanide Management Code which defines strict protocols for how cyanide is used and managed, including the detoxification of cyanide in waste streams. This step lowers the concentrations of cyanide compounds, using a process that oxidizes cyanide to cyanate. As a result of the various oxidation and reduction processes employed by gold mines and their use of cyanide, it is important that as a premier analytical services provider to this sector, that we can provide a broad range of testing.

Read about cyanide chemistry