Study On Coal-particle Detachment Of Pulp- Froth Interface

The conventional flotation system consists of a pulp zone and a froth zone.Due to the difference in the properties of the two phases,the mineralized bubbles are detached at the pulp-froth interface when passing through the pulp-froth interface.This paper takes the detachment of coal particles in pulp-froth interface as the research object,and the macroscopic desorption law of pulp-froth interface coal particles under different flotation operation parameters.The mechanism of the influence of the physicochemical properties of coal particles and the merger process of bubbles on the detachment of coal particles in the pulp-froth interface is described,which provides a new perspective for the regulation of flotation process.The main findings are as follows:Within a certain range,increasing the amount of foaming agent and collector,and reducing the height of the froth layer can reduce the desorption of coal particles in the pulp-froth interface,but the mechanism of reducing the detachment of coal particles in the pulp-froth interface is not the same.The frothing agent can effectively reduce the merger of the bubbles and the oscillating strength of the merged bubbles.The collector improves the surface properties of the coal particles and increases the adhesion strength of the bubbles and coal particles.The third-order flotation process mass balance model shows that reducing the height of the froth layer effectively reduces the additional feed to the pulp-froth interface.Detachment of pulp-froth interface coal particles is a flotation internal circulation system.This continuous internal circulation system reduces the yield of clean coal and improves the grade of clean coal.The physical and chemical properties of coal particles such as particle size,density,hydrophobicity,induction time and adhesion angle affect their selective detachment at the pulp-froth interface.The particle size and density of coal particles determine the magnitude of their inertial force(detachment force),which affects the detachment of coal particles at the pulp-froth interface.The surface properties of the coal particles determine the expansion dynamics of the three-phase contact line on the surface of the coal particles and the adhesion strength of the bubble-particle aggregates,which in turn affects the detachment of the coal particles at the pulp-froth interface.Due to the action of gravity,the coal particles are generally located at the bottom end of the pulp-froth interface,and under the action of buoyancy,the pressure of the bubbles in the vertical direction is greater,the discharge speed is faster,and the bubbles are easily merged in the vertical direction.Therefore,the breaking point of the merged bubble and the coal particles are located at the upper and lower ends of the bubble,respectively.The axial radius R,the transverse radius R,and the projected area in the vertical direction of the capillary merging bubble conform to the classical damped harmonic oscillation model.The axial radius R,the lateral radius R,and the projected area in the vertical direction of the merged bubble at the gas-liquid interface are only a simple expansion and contraction process.The evolution of the behavioral process of bubble merger indicates that the gas-liquid interface at different sites of the merged bubble has different motion laws,and the particles have different detachment probability at different sites of the merged bubble.