The process of restoration when the mining activities stop in a particular area depends on how much affected the area is. Before the exploitation of the soil, there are nutrients that species like microorganisms, as bacteria, use to carry on their metabolic functions. As a result of these processes, there is a particular disponibility of other resources plants take through their roots to also develop their own biological functions.
Having this clear, the removal of these particular nutrients, that goes away with the extracted minerals, causes several impacts too difficult for restoration processes to reverse. This is why, almost in terms of a human lifetime, the recovery of the original conditions of that particular area wouldn't have been reached. Only with the pass of hundred or thousands of years, and with the action of microorganisms and intensively ecologic work, that area would be recovered.