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Two industrial coal blends used in cokemaking were subjected to tests in order to assess the influence of waste sawdust (SC2 from chestnut and SP1 from pine) on the quality of the coke produced. The biomass was added in quantities of up to 5 wt.%. It was observed that biomass produced a substantial decrease in the plastic properties of the industrial coal blend, with reductions in Gieseler maximum fluidity of around 50 % for 3 wt.% additions of the two different sawdusts. Carbonizations with sawdust additions ranging from 0.75 to 5 wt.% were carried out in a movable wall oven of 17 kg capacity. The bulk density of the charge was observed to decrease with increasing amounts of sawdust with negative consequences on the quality of the cokes produced. Mechanical strength was determined by means of the JIS test. Coke reactivity and post-reaction strength (CRI/CSR indices) were also assessed. The amount of sawdust added was low to prevent any deterioration in coke quality. The advantage of using biomass in coking blends should be seen as a possible way to reduce costs and CO 2 emissions and to incorporate alternative raw materials in coke production.

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It is often assumed that green petroleum coke behaves as an inert material in cocarbonization with coking coal blends and has no active behavior on the important thermoplastic properties of the coal blend. This paper investigates that assumption. The objective of this study is to clarify effects arising when different petroleum cokes are added to a single coal or an industrial blend. The effects studied include changes during the pyrolysis stages of the cocarbonization, using a bituminous coal. This was done to study if petroleum coke is totally inert at the plastic stage of a given coal or there is an influence at the plastic stage. A further aim is to show how conventional and nonconventional techniques for petroleum coke characterization relate to its activity with the plastic stage of coal. A range of six petroleum cokes was used. The petroleum cokes were studied in terms of (a) optical texture, (b) FTIR spectroscopy, (c) hydrogen donor ability, (d) thermogravimetric analysis of the pyrolysis stage, (e) free-swelling index, and (f) thermoplastic properties of blends made up of a bituminous coal and petroleum coke. Evidence for a significant activity of some petroleum cokes was assessed using the above techniques, which can be considered as nonconventional in petroleum coke characterization. A good correlation among the parameters obtained from the above techniques/methods was found, indicating that the presence of unreacted and partially carbonized material, the hydrogen donor ability, the relative proportion of methyl and methylene groups, the amount of volatile matter released at a temperature range between 400 and 500 °C, the temperature of maximum volatile matter evolution and, finally, the agglomeration degree of petroleum cokes can be considered as important factors in the plastic properties of cocarbonization systems with coking coals.

Three different sawdusts obtained as wastes from the furniture and flooring industry were selected to study their influence on coal thermoplastic properties. A bituminous coal with a high volatile matter content was chosen as base coal. To investigate the effect of reducing the oxygen content of the sawdusts upon the coal's properties, the sawdusts were heat treated to 250 °C. Blends of the coal with the three as-received and then heat-treated sawdusts were tested. In order to gain a better insight into the subject, the sawdusts were pyrolyzed at 400 °C to determine the effect of the resulting char and bio-oil upon the plastic properties of the base coal. The Gieseler curves corresponding to the coal-sawdust blends were calculated from the curves corresponding to the coal-char and coal-bio-oil blends. The errors obtained were in all six cases lower than the repeatability allowed by the ASTM standard for the Gieseler test. Considering that the effect of the additives is the sum of both chemical and physical effects, it was possible to evaluate the contribution of each of these to the reduction of coal fluidity. In all cases it was found that the physical effects were more important. The textural properties of the chars obtained at 400 °C from the biomass were found to be important for determining the influence of biomass on the coal fluidity.

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