To study the effect of inorganic electrolyte solution on graphite flotation, 19 kinds of inorganic electrolytes, including nitrate, chloride and sulfate were selected as experimental electrolytes. The flotation experiment was carried out on graphite and the contact angle and surface potential of the interaction between inorganic electrolyte solution and graphite were studied. The results show that flotation effect and flotation rate of the three ion valence inorganic electrolytes follow the order: nitrate < chloride < sulfate and univalent < bivalent < trivalent (except Ba(NO3)2 and Pb(NO3)2). When the ion valence are the same, the larger the ion atomic number, the better effect on graphite flotation. Cations in inorganic electrolyte solutions are the main factors affecting mineral flotation. When the cationic type and concentration are the same, different flotation effects are attributed to different anions. For low ion valence inorganic electrolyte solution with weak foaming effect, a certain dose of frother can be added appropriately to improve the flotation effect of graphite. The high ion valence inorganic electrolyte solution has strong foaming effect, and it is not necessary to add a frother. The principle of inorganic electrolyte solution promoting graphite flotation is analyzed from the aspects of liquid phase property, gas–liquid interface property, contact angle and surface potential. It is proved that inorganic electrolyte solution as flotation medium can promote the effective flotation of graphite.

Experimental study on flotation of graphite with inorganic electrolytes solution
    Abstract
    1 Introduction
    2 Experimental
        2.1 Samples
        2.2 Inorganic electrolyte reagents
        2.3 Flotation tests of inorganic electrolyte solutions
        2.4 Flotation rate tests of inorganic electrolyte solutions
        2.5 Flotation tests of inorganic electrolyte solutions with frothers
        2.6 Measurement of contact angle between inorganic electrolyte solution and graphite
        2.7 Measurement of surface potential of the interaction between inorganic electrolyte solutions and graphite
    3 Results and discussion
        3.1 Flotation test results of different types of inorganic electrolyte solutions
            3.1.1 Flotation test results of chloride solution
            3.1.2 Flotation test results of sulfate solution
            3.1.3 Flotation test results of nitrate solution
        3.2 Comparison of flotation test results of different types of inorganic electrolyte solutions
        3.3 Flotation rate tests of different types of inorganic electrolytes
            3.3.1 Flotation rate tests of inorganic electrolytes with same cations and different anions
            3.3.2 Flotation rate tests of inorganic electrolytes with the same anions and different valence cations
        3.4 Flotation test results of inorganic electrolyte solutions with frothers
        3.5 Discussion on the influence of the properties of inorganic electrolyte solution on graphite flotation
            3.5.1 The influence of liquid phase properties of inorganic electrolyte solution on graphite flotation
            3.5.2 The influence of ions in inorganic electrolyte solution on the surface zeta potential of graphite
            3.5.3 The influence of gas–liquid interface property of inorganic electrolyte solution on graphite flotation
    4 Conclusions
    References

• Wenze Kang(Institute of Mining Engineering, Heilongjiang University of Science and Technology, Harbin 150022, Heilongjiang, China)
• Shufang Ding(Institute of Mining Engineering, Heilongjiang University of Science and Technology, Harbin 150022, Heilongjiang, China)
• Huijian Li(Institute of Mining Engineering, Heilongjiang University of Science and Technology, Harbin 150022, Heilongjiang, China)
• Hong Zhao(Institute of Mining Engineering, Heilongjiang University of Science and Technology, Harbin 150022, Heilongjiang, China)