Mineral Processing
Faraz Soltani; Hadi Naghavi; Hossna Darabi; Arsalan Parvaneh; Mobin Chagh Siah
Abstract
The main objective of the present study is to evaluate the feasibility of using gravity separation methods, including heavy bromoform liquid, spiral, and shaking table, for the primary concentration of gold from low-grade Siah Jangal ore (Sistan and Baluchistan Province, Iran). Characterization studies ...
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The main objective of the present study is to evaluate the feasibility of using gravity separation methods, including heavy bromoform liquid, spiral, and shaking table, for the primary concentration of gold from low-grade Siah Jangal ore (Sistan and Baluchistan Province, Iran). Characterization studies indicated that gold is mainly present as inclusions or within the lattice of pyrite and siderite minerals. For this reason, the potential of gravity separation methods using bromoform heavy liquid with a density of 2.89 g/cm³ was initially investigated in three size fractions: +1180, -1180+500, and -500 µm, where the maximum grade of 2.78 g/t with a recovery of 76.7% was obtained. The results showed that in coarser size ranges, both the grade and recovery of gold decreased. In spiral tests, the highest grade and recovery of gold were 2.33 g/t and 62.58%, respectively. The results of the shaking table experiments showed that, given a concentrate-to-feed weight ratio of 12%, a grade of 2.54 g/t could be achieved with a recovery of 73.81%, which, by eliminating a significant amount of tailings (about 88% of the feed), significantly reduces the operating expenses of subsequent processes (including flotation, oxidation, and leaching). It can be concluded that gravity methods, especially the shaking table, can serve as low-risk, low-cost, and environmentally friendly approaches for concentrating low-grade gold ores.
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 ...
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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.
