No abstract

Although many studies have been conducted on the morphological variations and its effects on flotation recoveries of a single mineral system, a systematic study for the flotation behavior of mixtures of minerals has not dwelled much. In this study, th flotation behavior of chromite and serpentine minerals was investigated to distinguish and isolate the contribution of morphology in single and binary systems. For this purpose, the shape analyses for the minerals ground as single and mixture were performed, and their flotation behaviors determined with the micro-flotation experiments. Additionally, the zeta potential measurements were carried out in the presence of sodium oleate as a collector. The shape analysis of the ground samples showed that while the roundness values of chromite and serpentine (gangue) minerals as single were quite different, the particle shape of chromite favored serpentine in the mixture system which in turn suggested that the mineral with the high hardness value dominates the shape characteristics in binary grinding conditions. Accordingly, while the flotation characteristics of chromite in the mixture followed the same trend with the flotation of a single chromite system as a function of particle shape, almost a reverse trend was obtained for the shape and flotation of serpentine in the mixture compared to a single serpentine system. Thus, at roundness values of chromite particles from 0.797 to 0.732, the flotation recoveries of chromite in the mixture increased from 51.0% to 75.4%. On the other hand, likewise chromite, the flotation recoveries of serpentine increased from 20.0% to 37.3% proportional to the roundness range of 0.757 and 0.709. These findings in turn showed that the grinding conditions dictate the soft component to be monitored by the harder and denser component which dominates the angularity and floatability of the mixture.

In this study, the flotation and aggregation characteristics of muscovite mineral particles were determined as a function of dodecyl amine hydrochloride (DAH) concentration and correlated with the theoretically calculated "particle-particle" and "particle-bubble" interactions using extended DLVO theory. In this series of tests, the flotation and aggregation characteristics of the muscovite mineral were determined with micro-flotation and turbidity measurements, respectively. In addition to these analyses, surface tension measurements were carried out as a function of pH. Also, the zeta potential and contact angle measurements were also performed as a function of DAH concentration prior to the flotation and aggregation tests. The experimental studies showed that while almost minimum and maximum points of flotation and turbidity values were obtained up to a critical concentration of DAH as 6.10 -6 mol/dm 3, a significant increment was obtained following that concentration. Accordingly, while repulsive forces dominated the interactions up to that concentration, the attractive forces became more effective at further concentrations such as 2.10 -5 , 4.10 -5 , 8.10 -5 , and 1.10 -4 mol/dm 3 DAH concentrations for both "particle-particle" and "particle-bubble" interactions. This in turn suggested that the determination of energy barrier heights between "particle-particle" and "particle bubble" may provide important insights into both flotation and aggregation characteristics of particles.