EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

The renewable biomass can be applied in the steel industry mainly by means of injection, gasification and mixing or embedding into raw materials, and contribute in such a way to the CO2 emission mitigation. Previous studies on the biomass usage in cokemaking concluded that a maximum amount of raw biomass in coal blend is limited to some 1.5 – 2.0 % due to deterioration of coke quality. To investigate the possibility to shift the biomass limit to higher values, recently different types of pre-treated biomass, i.e. woody pellets and biomass residues, were mixed with coal and coked in a laboratory muffle furnace, Pre-treatment was done under inert atmosphere in a temperature range between 300 °C and 1200 °C. This study focuses on the investigation of the influence of pre-treated biomass on the microstructure of metallurgical coke and the connectivity between coal and biomass particles during the cokemaking process. It seems to be a crucial mechanism responsible for coke strength. Pre-treated biomass and coal were put in layers one on top of the other beneath a burden for 24 hours at a temperature of 1050 °C to simulate the industrial cokemaking process. After that the boundary layer of both biomass and coal in the produced coke have been examined by microstructural analysis using an optical microscope combined with imaging analysis software to investigate the connectivity and the porosity of coal- and biomass-originated coke structure. Based on the results, conclusions are given on an optimal usage of biomass in cokemaking.