Abstract: In a process for mine waters, a hardness-free, alkaline reagent is first added at least once to the mine water that is to be worked up, whereby metals are sedimented or precipitated out as hydroxides from the mine water that is to be worked up. The precipitated metal hydroxides are separated off and the remaining mine water is further treated by adding a hardness-forming precipitation reagent, whereby gypsum, in particular in the form of gypsum mud, is precipitated out from the then metal-free mine water that is to be worked up. Thus a sequential separation of the metals and the sulphate from the mine water that is to be worked up proceed via corresponding precipitation using respectively corresponding precipitation chemicals, wherein, in the gypsum precipitation following the metal precipitation, a metal-free gypsum mud is produced that is safe to landfill.