In metallurgical processes tank leaching is a hydrometallurgical method of extracting valuable material (usually metals) from ore.
The solution drains from the tank, and is either recycled back into the vat or is pumped to the next step of the recovery process.
The vats are usually run sequentially to maximize the contact time between the ore and the reagent.
In such a series the leachate collected from one container is added to another vat with fresher ore As mentioned previously tanks are equipped with agitators to keep the solids in suspension in the vats and improve the solid to liquid to gas contact.
[1] Agitation is further assisted by the use of tank baffles to increase the efficiency of agitation and prevent centrifuging of slurries in circular tanks... Aside from chemical requirements several key factors influence extraction efficiency: The tank leaching method is commonly used to extract gold and silver from ore, such as with the Sepro Leach Reactor.