Characterization of Petroleum Coke as an Additive in Metallurgical Cokemaking. Modification of Thermoplastic Properties of Coal

Abstract

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.

Relation between texture and reactivity in metallurgical cokes obtained from coal using petroleum coke as additive

“…As was expected, addition of petroleum coke produces a decrease in the plastic characteristics of the mixtures. Furthermore, for the same mount of PC added, the differences in the plastic properties between the two PCs can be attributed to differences in their degree of 'chemical activity', as has been reported in previous works [4,6]. This reduction in rheological properties contributes to a higher densification of the resultant metallurgical cokes (i.e.…”

“…This reduction in rheological properties contributes to a higher densification of the resultant metallurgical cokes (i.e. a smaller pore volume) [6]. In fact, results in Table 1 show a decrease in the pore volume with increasing petroleum coke addition.…”

Coke–pitch interactions during anode preparation

“…5 shows the FT-IR spectra of the three calcined petroleum cokes. The calcined petroleum coke has very low transmission characteristics to baseline levels [10]. The assignment of the bands was done (Table 3) based on the literature FT-IR data for a green coke system because no FT-IR study of calcined coke is documented in the literature.…”

“…Petroleum coke is also utilized in coal blends that are commonly used in steel plants. The chemical functionality often has an effect on petroleum coke [10].…”

“…No significant literature is found on the utilization of FT-IR on calcined coke as the calcined coke has lower absorption characteristics with respect to baseline levels [10].…”