Sodium hexametaphosphate(SHMP) is often used to inhibit carbonates such as calcite and limestone in the flotation process, and can also be used as an inhibitor of gangue minerals such as quartz and silicate. For example, in the flotation of iron ore, tall oil is used as collector, and sodium hexametaphosphate and aluminum silicate are used as inhibitors of quartz and silicate to separate iron-containing minerals from quartz and silicate.

Sodium hexametaphosphate competes with the collector sodium oleate for adsorption on the surface of diaspore and kaolinite minerals. Because the adsorption capacity of sodium oleate on the surface of diaspore is stronger than that on the surface of kaolinite. Therefore, sodium hexametaphosphate(SHMP) has a greater influence on the adsorption capacity of sodium oleate on the surface of kaolinite than the adsorption capacity on the surface of diaspore, which is beneficial to the separation of diaspore and kaolinite. However, when the concentration of sodium oleate is relatively low, sodium hexametaphosphate can significantly inhibit the floating of diaspore.

Therefore, choosing an appropriate concentration of sodium hexametaphosphate(SHMP) is one of the conditions for better separation of minerals. As the concentration of sodium hexametaphosphate changes, it is beneficial to the flotation of bauxite, inhibits silica-containing gangue minerals and disperses the sludge.

Sodium hexametaphosphate and the collector sodium oleate have competitive adsorption on the surface of minerals. The presence of sodium hexametaphosphate affects the surface adsorption of sodium oleate minerals. When the concentration of sodium oleate increases, its adsorption capacity on the surface of diaspore minerals will increase, which can eliminate the influence of the concentration of sodium hexametaphosphate on the floatability of diaspore to a certain extent. Kaolinite has not changed much, which provides a basis for the separation of minerals.

The concentration of sodium hexametaphosphate(SHMP) can reduce the dynamic potential of the mineral surface, increase the electrostatic repulsion on the mineral surface, facilitate the dispersion of the sludge, and enhance the selectivity of separation.