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mixingtank

On the hydrodynamic of flotation machines

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A new Flotation Machine of the reactor-separator type has been designed based on the creation of compatible hydrodynamic conditions for control of the main stages of the flotation process in spatially separated zones of the machine. The dependence of the efficiency of the flotation process on the time of residence of the pulp in the reactor is shown to be of an extreme nature and is determined by the ratio of the rates of formation and destruction of flotation complexes and the rate of coalescence of the bubbles. The manner in which the zones in reactor-separators are organized and connected to one another for the selective flotation of mineral particles should be significantly different than for the treatment of waste water. The application of external vibrations (ultrasound) to mineralized air bubbles in the reactor zone makes it possible to independently regulate the process of particle separation and enhances selectivity in the division of copper sulfides from nickel sulfides.

Flotation is realized under highly turbulent flow conditions, so that turbulence may be process-determining, too. Because the principles of turbulent multi-phase flow have still not been fully worked out, one needs integral quantities to characterize the state of turbulence indirectly.

The radioactive tracer technique was used to measure the Residence Time Distribution (RTD) of the liquid and solid in a rougher flotation bank consisting of seven cells of a volume of 130 m³. Thus, a pneumatic system of high reliability was used in order to introduce a small amount of radioactive tracer (around 100 mL of liquid or pulp) at the feed pulp entrance. Then, the time response of the radioactive tracer was measured online along the flotation bank using noninvasive sensors located in the discharge pipe of each cell. An advantage of using the radioactive tracer technique is the direct testing of the actual solid particles (similar physical and chemical properties, shape, etc.). From a hydrodynamic point of view, single mechanical flotation cells of large size can deviate significantly from perfect mixing.

From its beginnings in the first decade of this century, flotation has gradually moved to a predominant role in mineral separation. Alain Kabemba, flotation process specialist at Delkor notes the major trend to treating lower- grade and more finely disseminated ores and lately the re-treatment of tailings. He also points to the broad applicability of size to below 10 μm.Real systems do not fulfill ideal conditions, mainly because of feed variation or disturbances. "Before considering disturbances to flotation specifically," Kabemba says. "It is important to emphasise the interlock between grinding and flotation, not only with respect to particle size effects, but equally to flotation feed rate variations. The grinding circuit is usually designed to produce the optimum size distribution established in testing and given in the design criteria. When the product size alters from this optimum, control requires either changing feed tonnage to the circuit or changing product volume, with either causing changes in flotation feed rates.

"While grindability changes due to the variation in ore properties are disturbances to the grinding circuit, they generate feed rate changes as disturbances to the flotation circuit. The variations in ore properties which affect flotation from those assumed in the design criteria must therefore necessarily include grindability changes."This reflects important differences in flotation machine characteristics between the two processes. Grinding circuits are built and designed with fixed total mill volumes and energy input, so the grinding intensity is not a controllable variable, instead grinding retention time is changed by variation of feed rates. In contrast, the flotation circuit is provided both with adjustable froth and pulp volume for variation of flotation intensity by aeration rate or hydrodynamic adjustment. Reagent levels and dosages provide a further means for intensity control."The Metplant ’13 conference started on July 14, with the GD Delprat Distinguished Lecture on Flotation given by Prof Graeme Jameson, Laureate Professor at the University of Newcastle, Australia, and one of the nominees to the International Mining Technology Hall of Fame. His lecture ‘Size matters- coarse and quick flotation can reduce costs’ discussed the everpresent need to reduce the costs of mining and milling operations. The greatest cost in ore concentration is the energy consumed in size reduction, particularly in grinding.Some progress has been made in reducing energy consumption in grinding, through better use of existing technologies, and the introduction of grinding methods such as HPGR. However, most attention is usually given to the grinding operation itself, with little reference to downstream separation processes beyond a target grind size. Since flotation is widely used to separate the values from the gangue, the particle size distribution of the particles leaving the grinding circuit is generally determined by the known capabilities of conventional flotation machines.Existing flotation equipment work very well for sizes typically in the range of 50 to 150 μm. If the upper size limit for flotation could be increased, by innovations in machine design, there would be dramatic reductions in grinding energy, which would lead to savings of great consequence for the running costs of the whole operation.In his talk, the effect of the final grind size from the grinding circuit on the energy costs for a typical base metal concentrator were discussed, with reference to a simple grind/float/re-grind/float circuit. Potential savings will arise not only from the reduction in energy costs, but also in the media costs that are of the same order. The talk finished with considerations of the way in which the flotation process could be improved, to increase the recovery of coarse particles, using new and innovative technology, such as fluidised bed flotation.

“Honesty, Innovation, High quality and efficiency, Users satisfied” is our business philosophy. Learn more, click flotation machine http://www.goldenmachine.net/product/flotation-equipment/

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Just fuck off dickhead 🤬

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