Coarse grinding can save grinding costs and reduce expenses. In flotation plants processing unevenly distributed ores, there is a tendency to increase the fineness of coarse grinding while ensuring the recovery rate of roughing. However, because coarse particles are relatively heavy, they are not easy to suspend in the flotation machine, and the chance of collision with bubbles is reduced. In addition, after coarse particles adhere to bubbles, they are easy to detach from the bubbles due to their large shedding force. Therefore, the flotation effect of coarse particles is poor under general process conditions. In order to improve the flotation effect of coarse particles, the following technological measures can be taken:
(1) Use a collector with strong collecting power, and add auxiliary collectors such as kerosene and diesel oil to enhance the collection of coarse particles, increase the adhesion and fixation strength between the mineral particles and bubbles, and reduce detachment.
(2) Appropriately increase the pulp concentration to increase the buoyancy of the pulp. Under the premise of ensuring the stability of the froth layer, appropriate stirring can promote the suspension of coarse particles and increase the chance of adhesion with bubbles. (3) Appropriately increase the aeration volume of the flotation machine to create larger bubbles and form “flocs” composed of large and small bubbles. These “flocs” have greater buoyancy and can carry coarse particles to the surface.
(4) Use a shallow-cell flotation machine to shorten the path of the mineralized bubbles and reduce the loss of mineral particles from the bubbles. Alternatively, use a specialized flotation machine suitable for coarse particle flotation, such as a ring-jet flotation machine or a Skenaer flotation machine.
(5) Use a rapid and stable froth scraping device to promptly scrape off the floating mineralized froth, thereby reducing the re-falling of mineral particles.