Effects of HyperCoal Addition on Coke Strength and Thermoplasticity of Coal Blends

Abstract

Ashless coal, also known as HyperCoal (HPC), was produced by thermal extraction of three coals of different ranks (Gregory caking coal, Warkworth steam coal, and Pasir subbituminous coal) with 1-methylnaphthalene (1-MN) at 360, 380, and 400 °C. The effects of blending these HPCs into standard coal blends were investigated. Blending HPCs as 5−10% of a standard blend (Kouryusho:Goonyella:K9) enhanced the thermoplasticity over a wide temperature range. For blends made with the Pasir-HPC, produced from a noncaking coal, increasing the extraction temperature from 360 to 400 °C increased the thermoplasticity significantly. Blends containing Warkworth-HPC, produced from a slightly caking coal, had a higher tensile strength than the standard blend in semicoke strength tests. The addition of 10% Pasir-HPC, extracted at 400 °C, increased the tensile strength of the semicokes to the same degree as those made with Gregory-HPC. Furthermore, all HPC blends had a higher tensile strength and smaller weight loss during carbonization. These results suggest that the HPC became integrated into the coke matrix, interacting strongly with the other raw coals.