Transformation of Coke Carbon Textures and Minerals during Gasification Investigated by SEM/EDS

Abstract

The carbon textures, minerals, and their interactions of a metallurgical coke during gasification reaction were investigated using scanning electron microscopy/energy dispersive spectroscopy by analyzing exactly the same sites of coke surfaces before and after reaction. The results indicate that most inert maceral-derived component (IMDC) had a greater propensity to react with CO 2 than the reactive maceral-derived component (RMDC). A portion of the carbon in mineralcarrying IMDC was removed as a result of the reaction with CO 2 , leaving minerals, primarily alumino-silicates, more pronounced. However, the reactivity of IMDC was found to be similar to that of RMDC in some cases. The physical features of the aluminosilicates in the coke were barely altered but bound with alkalis during the reaction. The Fe-containing phases were highly active and had strong interactions with the carbon matrix. Voids were formed in the carbon matrix associated with the Fe-containing phases as a result of the catalytic carbon−gas reactions. Iron played a major role in the reactions. The Mg-and Ca-containing phases reacted with the surrounding alumino-silicates and transformed into slag globules. Metallic iron dispersed in the voids or attached on the slag globules was formed as a result of the reduction of iron sulfate or sulfide.

The Future of CO2 Geological Sequestration: An Overview of Mineralization in Aqueous and Supercritical States

“…In studying the micromechanism of CO 2 mineralization, researchers utilizing scanning electron microscopy 162 (SEM) and transmission electron microscopy 74 (TEM) have identified passivation layers as a common occurrence in silicate mineralization processes. Notably, silica layers appear to be denser when formed under wet scCO 2 conditions.…”

Untitled

“…Samples taken from the tuyere area of the blast furnace show that carbonaceous matter graphitization occurs at temperatures above 1900˚C. Zhang's [8] research shows that the aluminosilicate in coke hardly changes in physical properties in the process of coke gasification in a blast furnace, but it combines with alkali materials. The iron-bearing phase has a high activity and strong interaction with the carbon matrix.…”