AbstractThe effect of heat-dispersing on sticky substances in a deinking pulping line was studied under different conditions including varying temperature, disc clearance, and pulp consistency. Sticky substances were quantitatively investigated before and after the heat-dispersing, and categorized into macro-, mini-, and micro-stickies as well as dissolved and colloidal substances. Meanwhile, their extents of removal in post-flotation were evaluated. The results showed that raising temperature, reducing disc clearance, or increasing pulp consistency significantly improved the dispersion of sticky particles, an effect that will be beneficial to their removal in the subsequent flotation process. Under temperature of 100 °C, disc clearance of 0.3 mm, and pulp consistency of 30%, macro- and mini-stickies decreased by 92% and 83%, respectively. Due to being dispersed to smaller sizes, removals of mini- and micro-stickies were enhanced in post-flotation to 25-26% and 68-70%, respectively. Only a small amount of dissolved and colloidal substances was removed in flotation.