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.

Abstract: An electrodialytic method and device for the simultaneous production of acids and bases of high purity and higher concentration operates by splitting corresponding salts in aqueous solution using an electrolysis cell. The electrolysis cell includes a cathode chamber in which an alkali is formed, a salt chamber for supplying a salt to be split, an acid chamber in which the acid is formed, and an anode chamber through which a mineral acid flows as a proton carrier. The anode is a hydrogen-consuming electrode. The method and device are preferably used in the production of hydrochloric acid and sodium hydroxide solution.

Abstract: COS, CS.sub.2, mercaptan, SH.sub.2, SOX and/or NOX are removed from a host gas by scrubbing using a solution of a salt of Scandium, Yttrium, an element of the Lanthanide or Actinium groups or blends thereof in water or in organic solvent.