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EN
In nickel sulfide processing, magnesium silicates (serpentines) can easily form slime coatings or hetero-aggregation on pentlandite surfaces, and hence decrease the pentlandite flotation rate and recovery. In this work, magnetic separation of pentlandite from serpentine using selective magnetic coating through adding magnetite fines as magnetic seeds was investigated. Interactions of magnetite-pentlandite and magnetite-serpentine were calculated by the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. The results show that the interaction of magnetite-pentlandite was obviously stronger than that of magnetite-serpentine with an external weak magnetic field (4776 A/m-1). Therefore, fine magnetite fractions selectively adhered to the pentlandite surfaces and enhanced its magnetism, resulting in being separated from serpentine by magnetic separation, which was further verified by magnetic coating-magnetic separation and SEM observations.
EN
In this work, a role of sodium hexametaphosphate (SHMP) in the flotation performance of a nickel ore was studied and mechanism was discussed in detail. The results showed that the presence of lizardite interferes with the flotation performance of pentlandite. The adsorption of SHMP at the lizardite/solution interface and the removal of magnesium ions from lizardite surface overcompensated the positive charge on the lizardite particle, and made its zeta potential negative. The interaction between lizardite and pentlandite changed from attractive to repulsive in the presence of SHMP. Thus, the addition of SHMP made the mixed sample of pentlandite and lizardite more dispersed, and significantly reduced the adverse effect of lizardite on the flotation of pentlandite. However, when the content of lizardite in the mixed ore was increased, the effect of SHMP weakened. Therefore, in flotation of a nickel ore containing a large amount of lizardite (46% w/w), SHMP usage is not suitable at the roughing stage due to the fact that lizardite in the pulp will consume most of the SHMP, and hence the removal of lizardite slimes from pentlandite surface become impossible. Based upon the results, SHMP usage is found to be suitable at the cleaning stage to improve the grade of concentrate.
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