Abstract: With the shortage of freshwater resources， mineral processing backwater is gradually used for flotation of chalcopyrite. The impurity ions in the backwater will affect the flotation index of chalcopyrite. Therefore， taking Na⁺，Ca²⁺，Al³⁺ as examples， the effects of impurity ions with different valences on the flotation of chalcopyrite and their mechanism were studied. The test results show that NaCl had an obviously positive effect on chalcopyrite flotability， high concentration of CaCl₂ significantly inhibited floatability of chalcopyrite， AlCl₃ has a certain inhibitory effect on floatability of chalcopyrite， but the effect is not significant. Surface contact angle， Zeta potential and phase diagram of chalcopyrite show that high concentration of NaCl hinders bubble merger， increases pulp foaming， compresses electric double layeron mineral surface， reduces energy barrier of bubble reaching mineral surface， promotes bubble-particle adhesion， and improve the floatibility of chalcopyrite; CaCl2 inhibits chalcopyrite flotation by forming hydrophilic Ca²⁺ hydroxyl complex （Ca（OH）⁺） in solution， adsorbing on the surface of chalcopyrite through strong affinity， reducing the negative Zeta potential of chalcopyrite， thereby reducing its surface hydrophobicity and inhibiting chalcopyrite flotation. The inhibition effect of AlCl3 on chalcopyrite flotation is mainly due to the hydrophilic precipitation of aluminium hydroxide formed on the surface of chalcopyrite， which results in the weakening of the hydrophobicity of the surface of chalcopyrite. However， due to the low sedimentation concentration， it has limited effect on chalcopyrite surface potential and flotation.

Key words: Chalcopyrite, Flotation, Metal ions, Adsorption