Mineral Processing
Sasan Mirshekari; Mehdi iranajad; Hossein Kamran Haghighi
Abstract
In recent years, the use of microorganisms in the flotation of sulfide minerals has gained significant attention, particularly in processes requiring reduced chemical consumption and the utilization of saline water. The targeted application of microorganisms can improve flotation process conditions. ...
Read More
In recent years, the use of microorganisms in the flotation of sulfide minerals has gained significant attention, particularly in processes requiring reduced chemical consumption and the utilization of saline water. The targeted application of microorganisms can improve flotation process conditions. Halophilic bacteria, as salt tolerant species, can be beneficial in selectively depressing pyrite during flotation. This study aimed to investigate the effect of the halophilic bacterium Bacillus mojavensis on enhancing the separation of chalcopyrite from pyrite in froth flotation using seawater. Experiments were conducted at five pH levels, and changes in recovery, flotation kinetics, and contact angle were evaluated. The results showed that the presence of the bacterium improved process selectivity and enhanced chalcopyrite flotation behavior at pH values between 6 and 10, while bacterial performance decreased at pH 4 and pH 12. The maximum recovery improvement was observed at pH 8, where chalcopyrite recovery increased from 55.11% to 62.04%, and the kinetic constant K was higher than that of the bacteria free sample. Contact angle measurements indicated that the bacterium significantly reduced pyrite hydrophobicity (from 73.73° to 46.7°) without causing noticeable changes in chalcopyrite (~75.8°); this behavior was attributed to the selective adsorption of EPS and bacterial cells on the pyrite surface, leading to its surface deactivation. The findings suggest that Bacillus mojavensis, due to its salt tolerance and stability in neutral to alkaline pH ranges, is a suitable candidate for use in seawater-based flotation circuits and low chemical consumption processes involving pH regulators.
Mineral Processing
Hossna Darabi; Faraz Soltani
Abstract
The main characteristic of mechanical flotation cells is to have an impeller, which is responsible for creating particle suspension, gas dispersion, and producing turbulence necessary to create effective bubble-particle interactions. For this purpose, in this paper, the conditions for complete gas dispersion ...
Read More
The main characteristic of mechanical flotation cells is to have an impeller, which is responsible for creating particle suspension, gas dispersion, and producing turbulence necessary to create effective bubble-particle interactions. For this purpose, in this paper, the conditions for complete gas dispersion in a Denver laboratory flotation cell have been investigated. Then, the critical impeller speed has been investigated for quartz particles with different size fractions. The effect of complete dispersion of introduced gas and critical impeller speed on the flotation rate constant (k) of particles was investigated. The results showed that k was the minimum value at an impeller speed of 700 rpm in the superficial gas velocity of 0.041- 0.125 cm/s for all size fractions. The impeller speed of 700 rpm was sufficient to keep -106µm quartz particles suspended, but at all superficial gas velocities, the minimum impeller speed required for complete gas dispersion was 850 rpm. Therefore, it can be stated that the reason for the low k value at a stirring speed of 700 rpm is the incomplete distribution of bubbles and particles (+106µm), resulting in a reduced probability of air bubbles colliding with solid particles. By increasing the impeller speed to values greater than 700 rpm, the k value increased, which is due to the complete distribution of particles and air bubbles in the flotation cell (increased probability of bubble-particle collision). Therefore, it is necessary to provide suitable operating conditions for the complete dispersion of air bubbles and also to keep solid particles suspended.
M. Kor; E. Abkhoshk; Kh. Gharibie; S. Z. Shafaei
Abstract
An attempt has been made in this paper to investigate the effect of particle size distribution on coal flotation kinetics. The effect of particle size (Ps) on kinetics constant (k) and maximum theoretical flotation recovery (RI) was investigated while other operational parameters were kept constant. ...
Read More
An attempt has been made in this paper to investigate the effect of particle size distribution on coal flotation kinetics. The effect of particle size (Ps) on kinetics constant (k) and maximum theoretical flotation recovery (RI) was investigated while other operational parameters were kept constant. The relationship between flotation kinetics constant and theoretical flotation recovery with particle size was estimated with nonlinear equations. Analysis of variance showed that the effect of particle size on the kinetics constant was statistically significant at 95% confidence level. However, it was not significant on maximum theoretical flotation recovery (RI). Different regression methods were conducted in order to model the effect of coal particle size on flotation kinetics. Results indicated that the quadric regression method gave better prediction of the cumulative recovery for different particle size fractions. The correlation coefficient (R2) values of this model were 0.99, 0.996, 0.98, 0.98 and 0.97 for average of particle sizes of 37.5 µm, 112.5 µm, 225 µm, 400 µm and 625 µm respectively.
