Development of Ordered Structures in the High-Temperature (HT) Cokes from Binary and Ternary Coal Blends Studied by Means of X-ray Diffraction and Raman Spectroscopy

Abstract

The aim of this work was to characterize ordered structures within cokes produced from single bituminous coals and from their blends. Three Polish coals of varying rank and caking ability were collected from the Krupiński, Szczygłowice, and Zofiówka mines, respectively. These coals were used for preparation of 19 blends: single (trivial blends), binary, and ternary ones. Cokes were manufactured in a laboratory scale using an apparatus with a Jenkner’s retort with a charge of 1000 g and heat-treatment temperature of 1000 °C. The X-ray diffraction (XRD) and Raman spectroscopy were used for the study. To determine the kind and size of ordered structures, the following parameters were discussed: interlayer spacing, d 002, crystallite stack height, L c, obtained from the XRD studies as well as the fractional contribution of ordered elements to all kinds of structures, and ratio of the amount of graphite structures (G type) to the amount of D2-type structures (less ordered than graphite), determined with Raman spectroscopy. The cokes produced from blends were treated as a compound system dependent upon properties of its components, single coal cokes. Additivity of the structural parameters of the cokes from blends was verified by the series model. Well-ordered structures, including the graphite-like ones, were found in all cokes studied. The highest degree of ordering was found in the single coke from very good caking Zofiówka coal. A similar structure was found in the cokes from binary and ternary blends of medium content of this coal of about 30–50 wt %. The preparation of cokes with well-ordered structures from blends of considerable lower concentration of the Zofiówka coal is promising, because the cost of these coke productions is lower than that of single coke from the Zofiówka coal. Discrepancy between the experimental data and those obtained from the series model confirmed mutual interactions between coals in a blend that affects forming of well-ordered structures in the cokes. This interaction was found to be the strongest in the blends with the content of the Zofiówka coal equal to 30–50 wt %.

Reprint of “The original concept of description of the coke optical texture”

“…The higher value of bireflectance, the higher degree of anisotropy (Duber and Rouzaud, 1999;Duber et al, 2000). The influence of the coal properties and technology conditions on the microtexture have been already studied (Patrick et al, 1973;Piechaczek et al, 2010;Pis et al, 2002;Pusz et al, 2003Pusz et al, , 2009Pusz et al, , 2010Singh et al, 2007;Smędowski et al, 2011).…”

Evaluation of the possibilities of applying fractal analysis for the characterization of molecular arrangement of carbon deposits in comparison to conventional instrumental methods

“…Hence, the trends of changes of both L c and d 002 vs. D F are characterized by similar trends for mean reflectance values. It should be considered that the values of both XRD parameters indicate that the crystallites forming carbon deposit structure are better organized than those found in the HT cokes (Smędowski and Krzesińska, 2013;Smędowski et al, 2011). The typical two bands, the G band (graphite band) and D band (disorder band), were detected in the first-order region for all the samples studied.…”

Structural characterization of carbonized briquette obtained from anthracite powder

“…Unfortunately, the sources of these coals are being depleted, which significantly increases their price [1]. Low ash and low sulfur anthracite are used at low efficiency for burning.…”

“…The structural characterization of coal and coal-derived products utilizes many different methods, such as SEM [13], FTIR [14][15][16], XPS [17,18] and Raman spectroscopy [1,13,19] etc. SEM and N 2 adsorption techniques are often used to describe the morphological characteristics and physical structure of coal-based material.…”

“…Jawhari et al [25] deconvoluted Raman spectra to investigate the structure of carbon blacks that had a low crystalline degree of graphitic carbons. Smȩdowski et al [1] obtained many parameters calculated from Raman spectra to characterize the ordered structures within cokes. These tools have the ability to assess more information about the chemical structure and physical characteristics of CAB.…”