The theoretical study of KCl direct flotation shows that NaCl should not be floated during the KCl flotation by octadecylamine,but NaCl still shows a floating phenomenon in practical production,which reduces the quality of KCl product.Aiming at the problem of simultaneous floating of NaCl with KCl,the influence of NaCl on KCl direct flotation was investigated respectively from the aspects of Na⁺ in flotation mother liquor,NaCl particles in raw materials,bubble entrainment in flotation process and adhesion between salt particles on the flotation process.The results showed that KCl flotation yield cannot change significantly whether Na⁺ existed in mother liquor or or not;however,the yield of KCl obviously decreased during the process of mixed flotation of NaCl and KCl particles;the yield of NaCl was improved with the increase of the air flow rate,which made the quality of KCl product decline;according to the analysis of SEM and EDS,both KCl and NaCl particles were found in the concentrate obtained by hydrolysis and flotation of carnallite.Comprehensively,the effect of Na⁺ in the flotation mother liquor on KCl flotation was negligible,but the NaCl particles can interfere with the direct floatation of KCl by hindering the contact of the collector with KCl particles and adhesion to KCl crystal particles.When the amount of air flow was large in flotation,the entrainment of bubbles on NaCl particles was also a factor that causes NaCl to float.The results of these experiments explained the reason for the abnormal floating of NaCl during the direct flotation of KCl from the perspective of raw material status and flotation process.These conclusions provided a good reference for process optimization of actual potassium positive flotation production .