Structural Characterization of Carbon in Blast Furnace Flue Dust and Its Reactivity in Combustion

Abstract

As an environmentally hazardous waste, blast furnace (BF) flue dust had a potential to reduce CO2 emission if recycled as fuels or reducing agents due to the high carbon content. The structure of carbon was a principal factor to the reactivity of carbon conversion and therefore was highly relevant to efficient utilization. In this work, the characteristics and chemical structures of carbonaceous materials in BF flue dust were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman analysis. The results showed that the aromatic structure of crystalline carbon was dominant in carbonaceous materials. Polymeric aromatic carbon and oxygen-containing groups (epoxide and esters carbon) existed on the surface. The stacking height (L c ), the in-plane crystallite sizes (L a ), and the interlayer spacing (d 002) of the aromatic structure layer were 2.45, 3.31, and 0.347 nm, respectively. The mass ratios of chars and cokes to carbonaceous matter were estimated to be 90.56% and 9.44%, respectively, by Raman spectroscopy. Then, the combustion reactivity was studied by thermogravimetric analysis using the Kissinger–Akahira–Sunose kinetics method. The activation energy as a function of conversion degree was determined. The results thus provided fundamental information for the utilization of BF flue dust for thermochemical conversion.

Linking the Defective Structure of Boron-Doped Carbon Nano-Onions with Their Catalytic Properties: Experimental and Theoretical Studies

“…The band at 1200 cm –1 arises in very disordered carbon materials, such as soot and coal chars. 40 , 43 Its origin is still controversial. In some cases, it was attributed to the presence of polyene-like structures or sp 3 –sp 2 mixed sites at the periphery of crystallites, which may also be responsible for the reactivity of materials.…”

“… 40 The 2D1 band was broadened and shifted to lower wavenumbers and even disappeared when the CNs became less ordered. 43 , 46 The intensities (band area) of the G and 2D1 bands in the Raman spectra were attributed to the structural disorder of the CNs. 43 …”

“… 43 , 46 The intensities (band area) of the G and 2D1 bands in the Raman spectra were attributed to the structural disorder of the CNs. 43 …”

“…A higher value of ( A D3+D4 )/ A G and a lower value of A G / A all may be attributed to the superior carbon combustion reactivity. 41 , 43 The carbon oxidative reactivity is exactly related to the amount of edge sites from A D1 / A G and amorphous carbon from A D3 . 48 The Raman parameters are summarized in Table 4 .…”

Effects of microstructural evolutions of pyrolysis char and pulverized coal on kinetic parameters during combustion

“…It effectively prevents the errors and deficiencies of conventional mechanism analysis methods and can more accurately describe the actual combustion mechanism process [17,18]. Combustion kinetic parameters are more significantly influenced by the structure of coal/char, such as their carbon chemical structure and microscopic pore structure [19,20]. However, during the combustion process, the particle structure of the fuel changes dynamically, which also affect the kinetic parameters.…”