Predictive method for caking property of blended weakly caking or non-caking coal based on coal petrography and structural detection

Abstract

Accurate evaluation of the caking property of non-coking coals, which generally exhibit limited metaplast-generation capacity during carbonisation compared with coking coals, is crucial for unlocking their utilisation potential in both cost reduction and efficiency improvement. Herein, an improved caking test was developed to distinguish weakly/non-caking coals under practical blending conditions. Structural characteristics of coals and macerals were quantified by Fourier Transform Infrared Spectroscopy with peak deconvolution, forming an integrated ‘petrology + structure’ framework for establishing quantitative correlations with caking indices. Results indicate that lean coal possesses superior blending potential compared to long-flame coal. Despite similarly limited metaplast-generation capability, lean coal forms a stronger carbon skeleton due to its higher degree of aromatisation and structural condensation. In contrast, long-flame coal exhibits more extensive aliphatic branching, higher thermal reactivity and a looser structural configuration, resulting in weaker cohesion and insufficient skeletal support. The generation potential of hydrocarbon (P) was identified as the most reliable predictor of caking behaviour owing to its consistent trends in both raw coals and their macerals. Accordingly, the theoretical P-value of blended coal ( $P_{B.T}$ ) was correlated with the caking index (G_R.I) through the relationship lgG_R.I = a $P_{B.T}$ ² + b $P_{B.T}$ +c, enabling accurate prediction of the caking behaviour of blends containing non-coking constituents. This approach reduces testing costs by about 98% and eliminates pyrolysis-related emissions, offering substantial economic and environmental benefits.