Bioleaching is the extraction of metals from their ores by using living organisms. This is much cleaner than the traditional heap leaching using cyanide. Bioleaching is one of several applications within biohydrometallurgy and several methods are used to recover copper, zinc, lead, arsenic, antimony, nickel, molybdenum, gold, silver, and cobalt.
Bioleaching involves using certain types of bacteria that can produce a solution called a leachate. By leaving these bacteria with a low-grade metal ore, they can produce leachates that contain a compound of that metal. Because this is in a solution it can be used in electrolysis to make the pure metal, but this only produces small amounts each time and would have to be repeated to make it economically viable.