Effect of the addition of waste sawdust on thermoplastic properties of a coal

Abstract

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.

Effect of briquette composition and size on the quality of the resulting coke

“…It can be seen that an addition of 2 wt.% of sawdust produces a reduction of between 40-45 % in the fluidity of the coal blend, which is slightly higher in the case of pine sawdust. The drastic reduction in coal fluidity due to biomass has already been reported in the case of individual coals and blends [6,16,17]. The reduction observed when adding to a high volatile and highly fluid coal was slightly greater [16] than for the coal blends [6].…”

“…The drastic reduction in coal fluidity due to biomass has already been reported in the case of individual coals and blends [6,16,17]. The reduction observed when adding to a high volatile and highly fluid coal was slightly greater [16] than for the coal blends [6]. The effect is lower for coal blends probably due to a compensatory effect coming from the number of coals of different rank and origin.…”

“…The inclusion of sawdust in coal blends for cokemaking has clear advantages such as its low sulphur and ash content and its zero contribution to CO 2 emissions but it also has a number of disadvantages including its low char yield, deleterious effect on coal fluidity [16,17] and low bulk density [18]. A possible way to increase the bulk density of the biomass is to prepare briquettes.…”

“…However both sawdust and non-coking coal have a deleterious effect on the development of coal fluidity [16,17] making pitch and coal tar preferable binders considering that both of these produce an increase in coal fluidity [20,21]. Coal-tar pitch has already been successfully used as a binder [22].…”

Preparation of Coke from Hydrothermally Treated Biomass in Sequence of Hot Briquetting and Carbonization

“…3,4) The present authors 5,6) proposed sequences of hot briquetting and carbonization 5) or hydrothermal treatment, hot briquetting and carbonization 6) for production of coke from lignite. The briquetting of pulverized lignite at 100-200°C causes its thermomechanical plasticization while macromolecular relaxation occurs due to breakage of non-covalent bonds such as hydrogen ones.…”