Two sizes of anthracite and petroleum coke particles were conveyed in a high-pressure experimental setup using nitrogen. Shear tests were conducted on the experimental materials to study their flowability. Comparisons between the conveying characteristics of anthracite and petroleum coke in the pneumatic conveying system were carried out by evaluating the effects of the fluidizing gas flow rate and total differential pressure on the conveying capacity and conveying stability. The influence of the operating parameters and material properties on the resistance properties were evaluated in both straight pipes (including horizontal, vertical, and inclined pipes) and bended pipes conveying anthracite and petroleum coke. The results show that the resistance properties of the experimental materials are different for straight pipes and bends. For conveying in an inclined pipe, the pressure drop increases with an increase in inclination angle ranging from 30 to 60°. Three individual empirical correlations were proposed for predicting pressure drops through horizontal, vertical, and 45° inclined pipes conveying petroleum coke. A comprehensive correlation for pressure drop prediction in inclined pipes conveying anthracite was developed. The correlation combines the material properties, solid–gas ratio μ, Froude number Fr, and inclination angle θ, and has good agreement with the experimental data. The existence of a critical inclination angle was deduced from the correlation.