Oscillation Method To Improve The Mechanism Of Action Of The Flotation Effect

For improving the selectivity of fine coal flotation cell and the flotation performance. an analysis is made of mechanism of the contamination of flotation concentrate. It points out that the contamination is due mainly to mechanical entrainment. For enhancing flotation performance and selectivity ,it is proposed to add a high-selectivity oscillator-separator in the cell. The optimum combination of oscillation parameters is determined through experimental design by using orthogonal method and variance analysis. Experimental result shows that the oscillation effect can result in a noticeably improved flotation performance, and the flotation result of the particles in different sizes is superior to that of conventional flotation process. Under experimental conditions, the ash of the flotation concentrate is reduced by 0.85 percent, with an increase of flotation perfection by 4.34 percent. At a similar ash content of flotation concentrate, the oscillation-assisted flotation process can produce a better flotation perfection and higher concentration yield, as compared with a flotation column operating without spraying water. The mechanism of oscillation flotation is described as follows: When passing through the oscillation layer, the air-bubble aggregate will break up into individual small rising bubbles or flocs, under the effect of mechanical vibration of screen wires. This leads to the elimination of mechanically entrained hydrophilic particles caused by the action of leaching flocs, as much particles entrained by the air-bubble aggregate under the filtration effect of the pulp will lose the support during rising in the pulp and fall into the pulp. Moreover, the air bubbles will undergo deformation under oscillation, and during the deformation process, energy is released, providing the power for the particles attached onto air bubbles through quasi-steady and non-selective adhesion to become detached. And there appears in the cell a horizontal high-frequency oscillating pulp layer. Due to its great horizontal alternating velocity, the aforementioned layer serves as a shield against the uprising current, reducing consequently the amount of fine clay entrained by the uprising current. The study proves to be a valuable attempt for the improvement of selectivity and flotation performance, and provides both theoretical and scientific basis for the design of high-selectivity flotation cells, as well as a new approach for the development of the clean coal technology.