Agglomeration and bonding mechanism of typical metallurgical solid wastes

The agglomeration of solid wastes is a key factor for subsequent utilization, while the difficulty in agglomeration and high cost have become common problems in the recycling process. The disk pelletizing process was adopted, based on the optimization method by liquid binder addition, and the influence mechanism of the ratio of typical solid wastes as blast furnace dust (BFD) and sludge generated by oxygen converter gas recovery (OGS) was explored. Meanwhile, the effect of binder solution concentration on the quality of green pellets was studied. Derived from the contact angle detection and infrared spectrum analysis, the liquid bridge model was established to study the bonding mechanism. The results showed that OGS had stronger adsorption effect with binder, and the hydrophilicity of BFD was better. When the concentration of binder was higher than 0.2 wt.%, the contact angle between the binder and BFD was bigger than that with OGS, while the capillary force between particles reduced with larger contact angle. The increment in the binder concentration increased the viscous force between particles and the maximum separation distance. The ultimate drop strength and compressive strength were related to the type of viscous force, and the compressive strength reflected the strength of the force between particles intuitively, while the drop strength represented the comprehensive forces of green pellets. Reasonable combination of BFD and OGS was available for pelletizing process, while the ratio of BFD should not exceed 32.0%, and binder C was added in the form of solution with the addition amount of 0.4 wt.%, which can reduce the cost of binder by 20–30 ¥/t.