Influence of Additive Amount and Heating Conditions on the Strength of Coke Prepared from Non-Caking Coal

Abstract

In the present study, we prepare several types of specimens from non-caking coal — including specimens in which noncovalent bonds between O-functional groups in coal are cleaved by pyridine and HPC-derived thermoplastic components are introduced into the pores produced by swelling, as well as specimens consisting of physical blends with HPC — and examine the influence of heating conditions and types of caking agents on the production of high-strength coke using a SUS tube. We also investigate the influence of heating conditions and types of caking agents on the strength of coke from pelleted specimens and determine the optimal conditions for producing high-strength coke from non-caking coal. HPC with a wide range of thermoplastic properties is more effective as caking agents than additives containing only low- molecular-weight or high-molecular-weight components. In addition, the strength of the produced coke depends on the amount of the additive, and optimal values of the additive amount are present. It was found that the following heating schedule is effective for producing high-strength coke from non-caking coal with added caking agents: First, high-speed heating (20°C/min) to an intermediate temperature in the range 400–600°C, recognized as the thermoplastic temperature range for typical caking coal; then, low-speed heating (3°C/min) to the temperature range of 900–1000°C. Moreover, we demonstrate that, by increasing the rate of heating in the thermoplastic temperature range, it is possible to reduce the amount of caking agent added.