The cyanide mining process could be replaced by the use of chloride. There’s a new way to extract more gold, with greener technology.
Gold may be a feast for the eyes, but it’s far less so for the environment. The precious material, almost instinctively associated with luxury – check out this gold version of PS5, for example – is not only used to create jewelry and trimmings – and this since ancient times, for thousands of years – but has applications in the field of electronics and even space exploration. The reason lies in some intrinsic properties, which give gold a good degree of malleability, conductivity and non-corrosiveness.
The other side of the coin is called cyanide. What does it have to do with gold and why have some researchers tried to eliminate it? Let’s start at the beginning.
How gold is mined and why cyanide, a polluting material, is critical in the process
Cyanide plays a key role in the gold mining process. The minerals extracted from the ground are not “pure,” so they must first be reduced to a powder and then passed through some tanks: this process is called leaching. The leached solution is made to interact with cyanide, which separates the gold from the ore.
The problem is that cyanide is highly polluting, to the point that many countries have banned its use. How do we get out of it? Do we give up gold to save the environment? Perhaps the answer is no. An alternative solution has been developed by researchers at Aalto University in Finland. The findings were published in a study in the journal Chemical Engineering.
A sustainable alternative to cyanide, which also allows more gold to be extracted
“So far no one had developed an efficient method to recover small amounts of gold from industrial chloride solutions,” said Ivan Korolev, one of the researchers involved in the study. “Thanks to our process,” he continued, “the amount of gold we were able to recover using chloride reaches 84%. In comparison, using the standard cyanide process produces only 64% gold.”
The new method is called electrodeposition-redox replacement (EDRR). It is a low-energy process that best combines electrolysis and cementing, two methods currently used in leached gold extraction. “Although it’s really very new, our method has great potential,” explain the researchers, who are confident that they will make it “a successful alternative to the traditional industrial process.”
Another way to get gold, as incredible as it sounds, is NASA’s treasure hunt to a very rich asteroid.
Giuseppe Giordano