Effect of impeller rotational speed on the size dependent flotation rate of galena in full scale plant cells
ABSTRACT The first three rougher cells in the lead circuit of the Elura concentrator (formerly Pasminco Australia Limited) were selected as the plant cells for investigation. Metallurgical surveys were performed and various hydrodynamic measurements taken, allowing the galena flotation rate constant and the bubble surface area flux (Sb) in these cells to be calculated over a wide range of gas flow rates, and at two impeller rotational speeds. It was determined that altering the impeller rotational speed did not significantly change the rate constant dependency on Sb when flotation was considered on an unsized basis.The analysis was further extended to examine the same cells parameters on a size-by-size basis. The results obtained have been used to identify differences in the flotation behaviour of the various particle size fractions, independently of surface hydrophobicity. It is shown that the physical conditions for effective flotation of fine (<9 μm) and coarse (>53 μm) particle size fractions differ substantially, suggesting that a specific hydrodynamic environment will favour a high flotation rate for fine galena, which may be detrimental to the recovery of coarse galena, and vice versa. These observations are in accord with metallurgical practice that suggest that it is difficult to improve fine particle flotation without also compromising coarse particle stability efficiency simply by modifying the cell hydrodynamics alone. A fundamental flotation model was applied to quantify differences in the flotation rate of the various particle size fractions with impeller rotational speed.
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ABSTRACT: In the current work, we investigated a methodology to assess the potential energy savings when a fluidised-bed separator (i.e., the HydroFloat) is incorporated into a conventional flotation flowsheet for flotation of coarse sulphide minerals (chalcopyrite). Overall metallurgical performance of the new flotation set-up is compared to a single stage conventional flotation flowsheet. In the modified flowsheet, coarser particle sizes (+ 150 μm) from a coarse grind (d80 = 500 μm) were floated in the fluidised-bed separator whereas the finer particles (− 150 μm) were channelled to a conventional, agitated flotation cell. The coarser and high grade concentrate from the fluidised-bed separator was then reground and floated again using a mechanically agitated flotation cell. The energy used in grinding and regrinding was calculated using the bond work index formula and compared with the energy consumed when the total mass of sample was ground fine (d80 = 150 μm) and floated in the mechanically agitated flotation cell only. Observations made from the results indicate that the floatability of the coarse chalcopyrite particles in the fluidised-bed separator depended mostly on their liberation classes. The remaining unrecovered copper was either completely or mostly encapsulated by gangue minerals. Though the metallurgical performance of the conventional flowsheet was superior in terms of copper recovery, the modified flowsheet showed promise in terms of energy efficiency. The methodology developed herein may be used for assessing coarse flotation strategies as a function of ore mineralogy type.Powder Technology 05/2015; 275. DOI:10.1016/j.powtec.2015.01.065 · 2.27 Impact Factor
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ABSTRACT: Coarse particles require distinctly different conditions to their fine and intermediate counterparts for successful flotation and recovery to the concentrate launder. These range from simple operational requirements such as shallow froth depth, reduced impeller speed and higher collector dosage to those that must be optimised specifically for the coarser size fractions such as air addition rate and bubble size, as well as the chemical environment (pH). This paper is the first of a series of publications on the topic of flash flotation and reviews many of the factors that affect coarse particle flotation with a view to how they impact the flash flotation process. A review of the current state of knowledge of the flash flotation process is presented and raises a number of issues in regard to both current operational knowledge and modelling practices.Minerals Engineering 07/2012; 34:1-10. DOI:10.1016/j.mineng.2012.03.023 · 1.71 Impact Factor
Powder Technology 11/2014; 267:61–67. DOI:10.1016/j.powtec.2014.06.026 · 2.27 Impact Factor