Combined microflotation of fine quartz

Abstract

It is already well established that the flotation efficiency of fine minerals can be significantly improved by adding a relatively small amount of microbubbles ( < 50 μm) to conventional coarse bubbles (>1 mm) normally used in flotation cells. To establish quantitative characteristics of this effect, the dependence of the flotation rate constant and recovery on microbubbles dosage was studied using fine quartz ( < 25 μm) samples in laboratory pneumomechanical and column flotation cells. It was found that, for pulp concentration in the range of 20–30 g L− 1, the flotation rate constant of the pneumomechanical flotation process is directly proportional to the microbubbles dosage. It was also found that the introduction of 0.25 L kg− 1 of microbubbles into the pulp before it is fed into the column flotation cell resulted in the recovery increasing from 77 to 89% for quartz concentration of 34 g L− 1 and from 66 to 87% for the quartz concentration of 68 g L− 1.

Combined microflotation of fine minerals: theory and experiment

“…The results are given in Fig. 3 which shows that at small values of parameter А, and therefore at small initial concentrations of fine particles (n b0 ), the rate of combined microflotation is practically linearly dependent on the initial dosage of fine bubbles, a fact that was discovered in the experiments on fine quartz flotation by Rulyov et al (2015).…”

“…Figure 4 presents the experimental data for the combined microflotation of fine quartz (<21 µm, 80%, <7 µm, 50%) at various initial concentrations of fine bubbles (w b0 ) in the range 0-0.042 reported by Rulyov et al (2015). The figure also shows the theoretical curves of recovery calculated using equation (13) taking K pB , K bB and K pb0 as the adjustable parameters.…”

“…Substituting for the above parameters data from the experimental runs (Rulyov et al 2015), specifically d = 6 cm, l = 12 cm and n = 1500 min −1 in equation (17) we obtain G = 4712 min −1 , whence it follows that E pb = 32.1 × 10 −3 . Hence, the capture efficiency of particles by fine bubbles is roughly 15 times higher compared to that of the coarse bubbles and this effect, therefore, provides for the significant acceleration of the flotation process even at the relatively small amount of fine bubbles.…”

“…Considering that in all experiments the superficial air velocity was 10.4 cm min −1 , and assuming, for example, that a coarse bubble size is 0.1 cm, then on the basis of formula (14) we obtain E pB = 2.2 × 10 −3 . Given that according to Rulyov (1978), the capture efficiency of both particles and fine bubbles by coarse bubbles to a first approximation is proportional to the square of their diameters and that in the experiments described by Rulyov et al (2015) the average size of fine bubbles 4 Combined microflotation of fine quartz. Experimental points are taken from Rulyov et al (2015); curves calculated using equation (13) 3 Dependence of the maximum recovery rate (R ′ t ) max on parameter A exceeded the size of particles roughly by 2.3 times, then it may be concluded that E bB = (2.3) 2 ·E pB = 11.6 × 10 −3 and K bB = 2.4 min −1 .…”

“…Given that according to Rulyov (1978), the capture efficiency of both particles and fine bubbles by coarse bubbles to a first approximation is proportional to the square of their diameters and that in the experiments described by Rulyov et al (2015) the average size of fine bubbles 4 Combined microflotation of fine quartz. Experimental points are taken from Rulyov et al (2015); curves calculated using equation (13) 3 Dependence of the maximum recovery rate (R ′ t ) max on parameter A exceeded the size of particles roughly by 2.3 times, then it may be concluded that E bB = (2.3) 2 ·E pB = 11.6 × 10 −3 and K bB = 2.4 min −1 . Substituting the obtained values for K pB and K bB in equation (13) by way of adjusting the curves to the available experimental points for w b0 = 0.007, 0.014, 0.021 and 0.042, the value K pb0 = 64.3·w b0 min −1 is calculated for the rate constant of hetero-aggregation of particles and fine bubbles.…”