Effect Of Phosphates On The Dispersing Of Serpentine

In the flotation of copper-nickel ore, electrostatic condensation between serpentine and sulfide ore due to the positive zeta potential of serpentine not only worsens the flotation of sulfide ores, but makes magnesium reduction in concentrate more difficult. Beginning with the regulation and control of serpentine surface potential, trisodium phosphate, sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate and sodium trimetaphosphate were studied in this paper. And their effect on the serpentine surface potential and mechanism were researched. Through investigating the influence of the five phosphates on the homophase dispersion between serpentines and the heterophase dispersion between serpentine and pyrite systematically, how phosphates influence the separation of serpentine and pyrite was confirmed. Major research results are as follows.The high IEP pH of serpentine is caused mainly by magnesium on its surface. When magnesium on serpentine surface is removed by acid dissolving, the IEP pH of serpentine drops from 11.8 to 6.1, and the dispersion and separation between serpentine and pyrite become much easier. However, provided that the dissolved magnesium ions exist in pulp, they will form magnesium hydroxide, which will exert adverse effect on the adjustment of serpentine surface potential, dipersion and inhibition of serpentine.By adsorbing on serpentine surface, dissolving the magnesium on serpentine surface and complexing the magnesium ions in pulp, phosphates reduces serpentine IEP and transforms the surface zeta potential of serpentine from positive to negative, thus weakening the electrostatic condensation between serpentine and pyrite and improving the flotation separation selectivity of serpentine and pyrite. The separation results of artificial mixed serpentine and pyrite (1:1) demonstrates that sodium hexametaphosphate, sodium pyrophosphate and sodium tripolyphosphate can enhance the separation selectivity of serpentine and pyrite remarkably and obtain concentrate with high recovery and low content MgO. The effect of sodium trimetaphosphate is weaker than the three phosphates and the effect of trisodium phosphate is most feeble. This order agrees with that of their adjustment of serpentine surface potential and dispersion between particles, i.e. chain polyphosphate>ring metaphosphate> orthophosphate.By adjusting the magnesium status on serpentine surface and in pulp, thus changing serpentine surface potential to regulate and control electrostatic condensation between serpentine and pyrite, the selective separation of serpentine and pyrite can be achieved effectively.