Gold and silver are usually extracted from low-grade ores using which process?

The cyanide process, also known as cyanidation, is a method commonly used for extracting gold and silver from low-grade ores. This technique involves the use of cyanide solutions to leach precious metals from their ores. The reason this method is particularly effective for low-grade ores is that cyanide is capable of selectively dissolving gold and silver from the surrounding materials, even at low concentrations.

Once the metal is dissolved in the cyanide solution, further processes can be employed to recover the metals, such as precipitation or electrolysis. The effectiveness of cyanide in dissolving these metals has made it a standard method in the mining industry, especially when dealing with ores that do not contain sufficient quantities of gold or silver to be recovered through more traditional methods.

Other methods like electrolysis, froth flotation, and amalgamation are used for different purposes or types of ores. For instance, froth flotation is effective for separating valuable minerals from gangue materials based on their wetting properties, but it is not suitable for direct extraction of gold and silver from low-grade ores. Similarly, amalgamation involves the use of mercury to form alloys with gold and silver, which is less efficient and poses environmental risks.