STUDIES ON BLEND DESIGN FOR ENHANCING COKEABILITY OF LAMZA COAL

Abstract

The bituminous prime coking coal with plastic properties suitable for metallurgical cokemaking constitutes only about 5% of the world's known coal reserve. In Nigeria, Lafia coal with intolerable ash and sulphur content of 25.60% and 2.30% respectively, is the only medium coking coal known before now. Further exploration efforts to find a higher grade local coal led to the location of Lamza coal in Adamawa state. In this work, proximate analysis, Gieseler fluidity, and Ruhr dilatation tests were conducted on Lamza coal and its blends with Ondo bitumen. From the results obtained, theoretical blend formulations to obtain cokeable coal blends was carried out between Lamza coal, Ondo bitumen and some prime coking foreign coals. The results obtained showed that addition of 15% bitumen upgraded Lamza coal from the weakly caking International Standards Organization (ISO) grade 811 to the medium coking ISO grade 812, with G-value of 0.971. Additionally, the Ruhr dilatation was raised by 18% and the Gieseler fluidity by 223 ddpm. Blend design calculations also showed that up to 44.44% of Lamza coal can produce a cokeable blend with 11.53% Lafia coal and 44.03% prime coking Canadian coal; translating to a saving of about NS.53 billion on Ajaokuta Steel Plant 1.3 million tons proposed annual import of coking coal. When the results obtained are upgraded on pilot scale, the critical problem of producing affordable blast furnace coke for sustainable iron and steelmaking when Ajaokuta Steel Plant starts operation would have been solved.