Effects of acid treatment on physicochemical properties and gasification reactivity of fine slag from Texaco gasifier

Abstract Fine slag (FS), which is a by-product from coal gasification, is composed of inorganic minerals and residual carbon. Acid treatment has high efficiency to separate the residual carbon in FS but the changes of properties of FS treated by acid remain unclear. To have a deep understanding of effects of acid treatment on physicochemical properties and gasification activity of FS, FS was subjected to different acid treatment, and then were characterized using Nitrogen adsorption technique, Raman spectroscopy and thermo-gravimetric analyzer. The results showed that the combined treatment with hydrochloric acid and hydrofluoric acid can remove the almost all mineral matters. Acid treatments did not modify the continuous and complete pores structure of FS. While, hydrochloric acid has a major influence on carbon structure, which produces the highest carbon actives and amorphous carbon. Nitric acid has positive influence on carbon structure transformation to crystalline structure. Notably, the gasification time can be shortened by the reduction of ash content. The carbon active sites in samples governed the initial reactivity while at the late stage of gasification the amount of inorganic elements controlled the gasification rate.