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1

The influence of plastic properties of coal blends on evolution of reflectance indicating surface (RIS) parameters of cokes

Smędowski Ł.

Contemporary Trends in Geoscience

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2012

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Vol. 1, iss. 1

67--70

EN

The aim of this work was to characterize cokes optical texture influence of plastic properties of coal blends on degree of cokes optical texture ordering. Three samples of coal blend characterized by different composition and properties were pyrolysed in Karbotest furnace (laboratory scale). To characterize plastic properties of the blends studied, temperatures at the beginning, maximum and at the end of plasticity (t1, tmax and t3, respectively) were determined as well as maximum fluidity Fmax. Texture of resultant cokes was determined by means of optical microscopy. As the result of these studies a set of optical parameters that describe reflectance indicating surface such as maximum, intermediate and minimum reflectance (RMAX, RINT, RMIN respectively) as well as values of Killby’ transformates (Rst, Ram, Rev) were determined for each sample. The optical texture parameters of the cokes were discussed in relationship to plastic properties of coals blends. Correlation between cokes anisotropy and fluidity of initial blends was detected.

PL

Celem niniejszej pracy było scharakteryzowanie tekstury optycznej koksów oraz wpływu właściwości plastycznych wyjściowych mieszanek na parametry opisujące teksturę. Trzy mieszanki węglowe o zróżnicowanym składzie i właściwościach plastycznych zostały skoksowane w instalacji Karbotest. Właściwości plastyczne określono wartościami temperatur: początku, maksimum i końca plastyczności (odpowiednio: t1, tmax and t3) oraz wskaźnikiem maksymalnej plastyczności Fmax. Tekstura tak otrzymanych koksów została zbadana z zastosowaniem mikroskopii optycznej. W wyniku badań określono wartości maksymalnej, pośredniej i minimalnej refleksyjności (odpowiednio: RMAX, RINT, RMIN) oraz wartości parametrów transformacji Killby’ego (Rst, Ram, Rev). Parametry optyczne charakteryzujące teksturę zostały skorelowane z parametrami określającymi właściwości plastyczne. Stwierdzono występowanie zależności pomiędzy anizotropią koksu i maksymalną plastycznością mieszanki wejściowej.

2

Modification of the properties and carbonization behaviour of coal tar pitches on progressive air-blowing

Machnikowski J., Gerus-Piasecka J., Kubica K., Machnikowska H.

Polish Journal of Chemical Technology

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2001

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Vol. 3, nr 1

7-14

EN

Pitches with softening points of about 140°C, 175°C and 210°C were prepared by progressive air-blowing at 300°C of coal-tar pitches from different commercial coke-oven tars. The modification induced by the mild oxidation was monitored using solvent fractionation, elemental analysis and contact angle measurement. The kinetics and mechanism of mesophase formation on isothermal treatment at 450°C and the optical texture of resultant cokes were studied by polarized-light optical microscopy. The air-blowing increases gradually the coking yield and toluene insoluble content of pitch with very little changes in quinoline insoluble content and elemental composition. The modified pitches preserve characteristic structural features of parent materials. Air-blowing accelerates the formation of mesophase on carbonization and modifies to a different extent the mechanism of the transformation. QI particles tend to form large aggregates in the early stage of the transformation and mesophase growth occurs in the practically Ql-free pitch, leading to two-phase optical texture of resultant cokes.

3

High softening point pitches produced by air-blowing of Qi-free coal-tar derived precursors

Machnikowski J., Gerus-Piasecka I., Kubica K., Machnikowska H.

Polish Journal of Chemical Technology

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2001

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Vol. 3, nr 2

11-16

EN

Modified pitches with the softening point of about 220°C were prepared by air-blowing at 300°C of Qi-free pitches from commercial "light" and "heavy" coke-oven tars. The effect of parent tar nature and Qi-free tar distillation conditions on air-blowing behaviour was studied using solvent and extrographic fractionation, elemental analysis, 1H NMR, and contact angle measurement. The kinetics and the mechanism of the mesophase formation on isothermal treatment at 450°C and the optical texture of semi-cokes were studied by polarized-light optical microscopy. Under these conditions totally isotropic pitches of considerably enhanced coking yield and TI content with very little change in elemental composition produced. The air-blowing accelerated the formation of mesophase on carbonization without marked affecting the mesophase units growth and the flow type optical texture of semicoke. The pitch from Qi-free "heavy" tar distilled under the reduced pressure was selected as most suitable potential precursor for isotropic carbon fibers.