A flotation study was performed for the soluble salts KNO3 and NH4Cl using oleic acid as the collector agent and various pH modifiers. Flotation was performed in one- and two-stage processes. The results of this study show that, as a collector agent, oleic acid enables flotation of NH4Cl and thus makes separation of these soluble salts possible. The best results, moreover, have been found at pH = 8 with gas ammonium as a regulator where three-stage flotation was performed with reflotation of concentrate and tailing obtaining 93% recovery of KNO3 in the tailing with a content of 98%. The influence of crystallization time on the size of the crystals in the soluble salts prior to flotation has also been examined. The most favourable particle size was found between 4 and 6 hours.