NOVELTY - Wastewater-free method of potash salt processing into potash fertilizers, comprises e.g. separating the components of potassium chloride, kieserite and rock salt, suspending rock salt component of potash salt, further processing potash component of the crude salt to chloridic and/or chloride-free potash fertilizers, further processing the kieserite component of the crude salt to magnesium sulfate products, magnesium sulfate potassium chloride-blended fertilizers and/or potassium sulfate, extracting salts from the potash salt processing.    USE - The method is useful for wastewater-free potash salt processing into potash fertilizers.    DETAILED DESCRIPTION - Wastewater-free method of potash salt processing into potash fertilizers, comprises separating the components of potassium chloride, kieserite and rock salt, suspending rock salt component of potash salt, further processing potash component of the crude salt to chloridic and/or chloride-free potash fertilizers, further processing the kieserite component of the crude salt to magnesium sulfate products, magnesium sulfate potassium chloride-blended fertilizers and/or potassium sulfate, extracting salts from the potash salt processing, re-suspending resulting residue potassium chloride-magnesium sulfate-sodium chloride-containing solutions, e.g. factory waste liquors of hard salt processing and potassium sulfate production process, the kieserite detergent waters from the kieserite cleaning and heap leaching of tailings by multi-stage evaporation in vacuum, and separating different potassium chloride, sodium chloride and magnesium sulfate containing intermediate products and their cleaning and further processing into potash fertilizers and first pumpable and then curable backfilling material mixture made of magnesium chloride, sodium chloride and alkaline additives.    The method comprises:    (i) mixing the partial streams of kieserite detergent water, suspending bases and factory waste liquors to a mixed solution;    (ii) carrying out multi-stage evaporation process in a direct current evaporation plant until the end of pure natural chlorine-crystallization;    (iii) further evaporating at a lower temperature in vacuum until close to the solubility limit of the carnallite in crystallization of a salt mixture of potassium-magnesium salts (kainite) and brine (sodium chloride) in connection with a kainite-stirring step;    (iv) extractive stirring from kainite at 4 hours of stirring time;    (v) removing the potassium chloride-sodium chloride mixture and flotatively removing sodium chloride;    (vi) further evaporating mother liquor separated from the potassium chloride kainite-crystals (310 g/l magnesium chloride to less than 450 g/l magnesium chloride, and obtaining sodium chloride-containing carnallite which is separated and integrated into the upstream salt production process to obtain potassium chloride;    (vii) producing potassium sulfate from the purified and optionally corrected potassium chloride kainite-mixture in the molar ratio potassium to sulfate by double decomposition over schoenite (potassium sulfate-magnesium sulfate hexahydrate) as an intermediate step during the simultaneous recovery of valuable materials from potassium chloride and magnesium sulfate from the potassium sulfate reaction solution by evaporation to 310 g/l magnesium chloride and obtaining potassium chloride-kainite crystals and recycling in the schoenite production and the magnesium chloride-containing evaporated solution in concentration step (vi); and    (viii) solidifing the magnesium chloride- magnesium sulfate containing end liquor by lime hydrate addition with pure sodium chloride crystals and flotation foam from steps (v) and (ii).    DESCRIPTION OF DRAWING(S) - The figure shows a schematic process flow of the method (Drawing includes non-English language text).