Reduction in coal fines and extended coke production through the addition of carbonisation tar : environmentally clean process technology

Abstract

Production of coal fines in coke making has lately become a problem worth addressing due to its negative impact on ecosystems. The use of coal fines is becoming an issue due to high Quinoline Insoluble formation during the carbonisation process as well as carry over or enhancement of carbon deposition in the upper parts of the coke ovens. In this study, the effect of carbonisation tar addition over a range of 2.0 – 8.0 wt.% was evaluated as a probable partial substitute for expensive coking coals by assessing coal fines reduction, coal blend cost analysis, extended coke production and coke quality. At the optimum condition of adding 6.0 wt.% carbonisation tar, key coke qualities were improved. This occurred even when lower quality coking coal of up to 35% was included in the coal blend. Coke quality results obtained in this study were comparable to international benchmarks. Furthermore, a 56.8 wt.% reduction in coal fines (powder) was observed. By reducing coal fines, there is a considerable reduction in coal dust that personnel are exposed to and a reduction in acid mine drainage as well as a decreased likelihood of spontaneous combustion. Savings of up to USD 1.7 million per year were postulated and supported by mathematical models used to calculate the cost-effectiveness of such a project.