During flotation, excessively coarse particles (greater than 0.1 mm) and extremely fine particles (less than 0.006 mm) float poorly, resulting in low recovery rates. When flotating coarse particles, the greater gravity increases the force at which the particles detach. Therefore, it is necessary to: (1) use a sufficient amount of the most effective collector; (2) increase the aeration of the pulp to form larger bubbles and increase the amount of microbubbles precipitated in the water; (3) maintain appropriate pulp stirring intensity; (4) appropriately increase the pulp concentration; and (5) scrape bubbles quickly and smoothly. When flotating extremely fine particles (usually referring to slime smaller than 5-10 μm), (1) the slime has a very small mass and easily adheres to the surface of coarse particles, reducing the floatability of coarse particles and worsening the selectivity; (2) due to the large specific surface area of ​​slime, it will adsorb a large amount of flotation reagents in the pulp, reducing the reagent concentration in the pulp, disrupting the normal flotation process, and reducing the flotation index; (3) due to the fineness and large surface area of ​​slime, the surface activity increases, making it easy to react with various reagents, difficult to separate, and highly hydrated, resulting in excessively stable foam, which will cause difficulties in fine selection, reduce the quality of concentrate, and reduce the fluidity and concentration efficiency of foam products.