Investigation of collector desorption behavior on the coal surface during flotation conditioning

Abstract

Mechanical stirring during the flotation conditioning process is a commonly employed and efficient method to enhance the effectiveness of slurry conditioning. However, excessive stirring intensity can lead to the desorption of collectors from the surface of coal slurry particles, compromising the conditioning efficacy. Thus, determining the optimal range of stirring intensity to enhance conditioning performance is necessary. The influence of stirring speed on the adsorption rate of coal oil and the desorption behavior of coal oil on the surface of coal slurry was investigated. Adsorption rates were measured and calculated using a UV spectrophotometer. An in-house desorption test apparatus and a high-speed motion capture system were employed to study the contact angle, adsorption area, deformation degree, and the forces acting on the adsorbed oil droplets under stirring conditions. Results indicated that the stirring speed significantly impacted the adsorption rate of the coal slurry. On increasing the stirring speed, the adsorption rate exhibited three distinct phases, that is, an increase, decrease, and stabilization. A maximum adsorption rate of 78.37% was observed at a stirrer rotation speed of 800 r/min, highlighting the crucial role of optimal stirring speed during conditioning. Both excessively high and low speeds were found to be detrimental to the conditioning process. As the stirring speed increased, the contact angle and contact area of the adsorbed oil droplets also increased, leading to an enhanced adsorption effect. Furthermore, the degree of deformation of the oil droplets increased with rising speed, accompanied by a reduction in stability.