Effects of emulsified asphalt on the mechanical properties of granulation of calcium fluoride sludge

To reduce the landfill volume of waste CaF2 sludge, artificial fluorite bulk (AFB) is granulated by blending CaF2 sludge and emulsified asphalt (EA) for the use of flux in this study. Results showed that high stability of micron-sized EA can be successfully prepared and used to granulate CaF2 powders to form AFB. EA has high-dispersivity with the particle size being measured in the range of 1–8 μm by optical microscope examination from an optimal emulsifiers ratio (CTAB (cetrimonium bromide)/OP-10 (commercial surfactant mixtures) = 75/25), and a high rotational speed in the homogenizer (20,000 rpm). Moreover, with the optimal addition of 12.5% asphalt, the prepared AFB pellets present the highest mechanical strength, reaching 9.88 kgf/cm2 and 4.06 kgf/cm2 for the uniaxial compressive strength and flexural strength, respectively. The optimal 12.5% addition also satisfies the requirement of the steelmaking process by passing the tumble-test quality examination. The analyses also infer that the cohesiveness of AFB is mainly combined through physical combination forces, including Van der Waals force, bridging action, and mechanical mosaic force. This occurs without triggering new chemical bonding.