Song Mao

Effect of dispersants on dispersion stability of collophane and quartz fines in aqueous suspensions

ABSTRACT A stable dispersion of fine mineral particles in an aqueous system facilitated by dispersants is an essential prerequisite for their successful separation. We investigated the dispersion stability and mechanism of suspensions of aqueous collophane and quartz fines (10u2009µm) in the presence of sodium hexametaphosphate (SHMP), sodium silicate or sodium carbonate using the sedimentation balance method, zeta potential measurements, contact angle measurements, micro-flotation tests and theoretical calculation of Extended-DLVO (Derjaguin-Landau-Verwey-Overbeek). The results showed that three dispersants significantly enhanced the dispersion stability of collophane in the following descending order SHMPu2009>u2009sodium silicateu2009>u2009sodium carbonate. This is because they increased the zeta potential of collophane in the same order; meanwhile, the SHMP made the collophane more hydrophilic compared to two other dispersants. These results illustrated that the dispersion stability was attributed to electrostatic repulsion and hydration repulsion and that the hydration repulsion had a greater influence on the stability than electrostatic repulsion based on the calculation of Extended-DLVO. However, the quartz suspension always maintained a stable dispersion in the absence or presence of dispersants, since there was a higher zeta potential and stronger hydrophilicity for natural quartz. These provide a theoretical direction for the dispersion of fine-disseminated siliceous phosphorites and phosphate slimes in separations. GRAPHICAL ABSTRACT

The Effect of Ca2+, Mg2+, SO42- and PO43- on Phosphate Ore Flotation

In the process of recycling phosphate ore processing wastewater, the accumulation of inorganic ions and the flotation reagents have a great influence on the flotation performance when they reach to a certain concentration. This paper studied the effect of Ca2+, Mg2+, SO42- and PO43- on the reverse flotation of phosphate ore through the single factor experiment. The experimental results show that Ca2+, Mg2+ and PO43- have less effect on the flotation performance, and that a certain amount of PO43- in the ore pulp can reduce the dosage of acid and improve the flotation result. SO42- has a significant effect on the reverse flotation of phosphate ore and the concentration of SO42- should be controlled under 1 g/L in the backwater utilization.