Effect of the blending of bituminous coal with lignite coal and leaching lignite coal on the reactivity with CO2

Abstract

The purpose of this study is to compare and reduce the CO2 reactivity of single coking coal, mixed coking coal, and mixed coal that has undergone leaching. The coal under study is a commercial brand imported from Australia and used in commercial plants. We set up 3 cases in which 7 types of low-grade and high-quality coal and 2 types of coking coal are mixed. And 3 cases were prepared for mixing coking coal by leaching treatment. Thermo gravimetric analysis (TGA) was used for the gasification of char. In addition, we measured the ash content of coal and the porosity of char, and used various equipment to analyze the experimental results such as microscopic observation through SEM. The coal particle size used in the experiment was ~3mm or less. The sample weight of the thermos gravimetric analyzer was 0.1 g. The acidic solution of the coal ash leaching was hydrochloric acid. The leaching proceeded for 72 hours in a 3M acidic solution of the leaching solution. The prepared coal was converted to char at a heating rate of 5 ℃ / min from room temperature to 1,000 ℃. Next, measurements of the CO2 gasification of coals made from single coking coal and mixed coking coal were performed using thermo gravimetric analysis (TGA) at various temperatures (1,100, 1,150, 1,200 °C) to calculate CO2 gasification. To evaluate the measured reactivity, the ratio of the reduced mass to the initial sample mass was evaluated first. In addition, the average reactivity (R0.5) at 50% reaction was evaluated as an indicator of the CO2 reactivity of coal at high temperature, and comparative analysis was conducted based on two indicators. Based on the change in reactivity due to mixing of coal and the change in reactivity due to leaching treatment, several factors that determine the reactivity among coal components were investigated. Finally, it is expected that CSR (Coke Strength after Reaction) of low-grade coking coal can be improved by introducing the results of this study into a commercial coke process. This is because CSR is inversely related to CO2 reactivity at high temperatures (CRI).