Effect of Surface Chemistry and Structure of Sludge Particles on Their Co-slurrying Ability with Petroleum Coke

Abstract

Abstract Gasification and combustion performance of petroleum coke–water slurry (PCWS) can be enhanced by the addition of sludge. In this study, we have mixed three types of sludge with petroleum coke to form petroleum coke–sludge slurry (PCSS) and analyzed the effects of surface chemistry and structure of the sludge samples on the rheological properties of PCSS. Results show that the surface of petroleum coke particles is strongly hydrophobic, while the surface of sludge particles is hydrophilic. The sludge particles primarily consist of oxide and mineral salts, while petroleum coke particles mainly consist of organic carbon. Modification of the sludge changes the distribution of mineral components on the surface of sludge. In addition, the surface area, pore structure, and size of sludge tend to increase after modification. Sludge shows strong shear-thinning behavior, while the rheological properties of PCWS change from shear-thickening to shear-thinning behavior with excessive addition of sludge more than 6 wt.%. The suitable mass concentration for industrial application of PCSS is determined to be 62–64 wt.% for the sludge addition of 10–15 wt.%. Increasing the amount of sludge may enhance the yield stress and improve the static stability of PCSS, and sludge might be the most effective stabilizer used in PCWS.