Mineralogical and metallurgical examination of fluorosilicate mineral floatation in the Ok Tedi circuit

The Ok Tedi copper orebody consists of porphyry and skarn orebodies. The skarn orebodies, identified by different mineralogy, are the source of high intermittent fluorine levels in the mill concentrates. This paper discusses the results of the work undertaken to characterize the various fluorine-bearing minerals in samples of final copper concentrates and the distribution of fluorine amongst the minerals. Quantification of each mineral in mill feed and various flotation streams at Ok Tedi enables an understanding of the quantitative response of fluorine-bearing minerals to flotation. The metallurgical behavior of fluorine in the flotation process is also discussed

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell. Part 4: Effect of bubble surface area flux on flotation performance

The metallurgical performance of a 2.8m 3 portable industrial scale flotation cell was measured when treating zinc cleaner feed at Hellyer concentrator in Tasmania, Australia. The cell was fitted in turn with four different impeller-stator systems and operated over a wide range of air flow rates and impeller speeds. Bubble size, gas holdup and superficial gas velocity were measured at each of 64 different operating conditions along with the metallurgical performance of the cell. When metallurgical performance was expressed in terms of a kinetic constant, it was found that neither bubble size nor gas holdup nor superficial gas velocity could be related to flotation rate individually; but when taken together, they determine the bubble surface area flux in the cell, which could be related to flotation rate extremely well. A linear relationship between flotation rate and bubble surface area flux was found for all four impellers investigated: the slope of the line was independent of the type of impeller used. The linear relationship was verified for different size fractions of the ore: the slope of the straight line was different for different size fractions, values being greater for the smaller size particles. The relationship was also independently confirmed at another zinc cleaner operation. This finding has potential practical application in flotation plant modelling, design and optimisation

Particle collection within the Jameson cell downcomer

Since the invention of the Jameson cell in 1986 various mechanisms have been postulated for particle collection within the cell's downcomer. Possible mechanisms include thin film migration, instantaneous collection, mixing zone collection, residence time dependence and bubble surface area flux. The limited amount of investigation to date has not provided sufficient evidence to allow one mechanism to be supported over the others. A summary of the postulated mechanisms is presented along with the background to their formulation. They are assessed on the basis of available knowledge and categorized according to specific operating parameters within the Jameson cell downcomer. In addition, relationships between operating variables and various hydrodynamic zones within the downcomer are discussed. A review of how these mechanisms relate to flotation operations is conducted for coal flotation, base-metal ore flotation and the removal of organic matter from solution

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell - Part 1: Effect on bubble size distribution

Bubble size distributions were measured at different locations in a 2.8 m portable industrial scale sub-aeration flotation cell, treating zinc cleaner feed in the Hellyer Concentrator in Tasmania, Australia. The cell was fitted in turn with four different impeller-stator systems, and operated over a range of air flow rates and impeller speeds. The mean bubble size was found to increase with increase in air flow rate at different locations in the cell, for all four impellers, and to decrease with increase in impeller speed. The mean bubble size was largest close to the impeller shaft and smallest at the impeller discharge point, for all the impellers. The shape of the bubble size distribution also changed with location in the cell. The "global mean" bubble size calculated by simple arithmetic average of the values at six locations in the cell coincided remarkably well with the mean bubble size measured halfway between the impeller shaft and the side of the cell, at the top of the pulp. In general, the impellers produced "global mean" values of 1.0 mm or less at the manufacturer's recommended impeller speed

Flotation process response of Ok Tedi fluorine bearing minerals

Orebodies at Ok Tedi contain a number of different fluorine bearing minerals. Some of these minerals report to concentrate and are responsible for the presence of the penalty element, fluorine, within the concentrate. Previous analytical work has tended to examine geological samples for content, rather than determine the metallurgical behaviour of the different mineralogical species. This investigation utilised X-Ray Diffraction combined with Scanning Electron Microscope/Electron Microprobe to identify the fluorine bearing minerals in flotation test products. Seven fluorine bearing minerals were identified, viz., talc, phlogopite, amphibole (tremolite and actinolite), sphene, apatite, biotite and clay. Talc was found exclusively in the skarn ore type. Phlogopite and amphiboles (tremolite and actinolite) were found to occur in both skarn and porphyry ores, while sphene, apatite, biotite and clay were found only in the porphyry ores. Of the fluorine bearing minerals observed, only talc exhibited natural hydrophobicity to any significant degree. Phlogopite and the amphibole minerals were found to be hydrophillic, whilst the remaining minerals occurred in insufficient quantities to determine the flotation behaviour. Ok Tedi copper concentrate fluorine content prior to skarn ore treatment in the mill (typically 350ppm) was previously identified as deriving from phlogopite, while talc was believed to be the source of intermittent high concentrate fluorine contents when skarn ores were treated. This paper provides supporting evidence for this belief, and reports the nature of fluorine bearing mineral flotation behaviour