Importance of Biomass and Binder Selection for Coking Briquette Preparation. Their Effect on Coal Thermoplastic Properties

Abstract

Blends consisting of a high volatile bituminous coal, biomass and binder that were used in the preparation of briquettes were analyzed in order to select the best components from the viewpoint of their influence on the coal's thermoplastic properties. The raw materials were studied by means of thermogravimetry, high-temperature rheometry, hightemperature proton nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared (FTIR) spectroscopy. In addition, the fluidity of the blends was determined with the standard Gieseler plastometer test method (ASTM D 2639-74). Various parameters derived from these different techniques were used to explain the effects of biomass and binder on the fluidity of the blends with coal. It was found that the deleterious effect of biomass was mainly related to its physical properties, whereas the effect of the binder was controlled by its chemical composition. Coal tar, coal tar sludge, pine sawdust and a bio-coal derived from hydrothermally treated waste biomass obtained from pruning were the best materials for the preparation of briquettes for cokemaking.

Mechanical strength of bio-coke from briquettes

“…To acquire a deeper understanding of the effect of the binders, four briquettes were prepared with just the coal and binders. A more detailed description of the procedure applied to prepare the briquettes and of the materials used can be found elsewhere [15]. The nomenclature used for the briquettes is as follows i.e.…”

“…On the other hand, it has been shown that biomass fluidity as determined by hightemperature rheometry does not affect blend fluidity since at the temperatures of coal plastic stage, biomass is already present as a char [15]. The influence of biomass on fluidity is related to the porosity and yield of the char from the biomass [15,28].…”

“…On the other hand, it has been shown that biomass fluidity as determined by hightemperature rheometry does not affect blend fluidity since at the temperatures of coal plastic stage, biomass is already present as a char [15]. The influence of biomass on fluidity is related to the porosity and yield of the char from the biomass [15,28]. Pine sawdust is the biomass which causes the least impairment of coal fluidity, whereas lignin produces a drastic reduction in fluidity but also coke with the highest strength (Table 3).…”

“…The C/H ratio is normally used to indicate the degree of aromaticity, but in the present case paraffin has a higher value than the molasses of this ratio, although it is less aromatic. Paraffin does not have any aromatic structures whereas molasses has some aromatic structures that are typical of lignocellulosic biomass [15].…”

Reactivity of biomass containing briquettes for metallurgical coke production

“…The addition of biomass to a coking blend also decreases the coking pressure during the carbonization process [9]. On the other hand, the direct addition of biomass has a deleterious effect on coke quality [9,10] and on the thermoplastic properties of coal [11]. In recent years however, it has been suggested that the use of briquettes would allow biomass to be added to coking blends without impairing the strength of the resulting bio-coke [12].…”