Characterization of Petroleum Coke as an Additive in Metallurgical Cokemaking. Influence on Metallurgical Coke Quality

Abstract

The relevance of petroleum coke activity during the plastic stage in cocarbonization with a low-volatile bituminous coal was assessed by establishing differences in lowering of Gieseler maximum fluidity of the blend (bituminous coal and petroleum coke) and in metallurgical coke quality. Differences in fluidity of the blend were well correlated with parameters used in petroleum coke characterization such as hydrogen donor ability, the volatile matter released between 400 and 500 °C, and the ratio of methyl and methylene groups in aromatic clusters. The metallurgical cokes were produced in a laboratory oven from blends of petroleum coke−bituminous coal and, then, characterized in terms of abrasion strength and reactivity to CO2. There is a clear relation between the chemical activity of petroleum coke in cocarbonization systems with coal and improvements in metallurgical coke quality. The ability of petroleum coke to interact with coal during the plastic stage contributes to good bonding between components as evidenced by the quantitative study of interfaces by optical microscopy.

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.…”

“…Coal/PC blends were carbonized in a laboratory oven of 400 g capacity. The main characteristics of this oven as well as carbonization conditions are given elsewhere [4]. Pore volume distribution of pores with a radius of between 3.7 nm and 7500 nm was evaluated by mercury porosimetry.…”

“…However, it should be pointed out that, while in the case of macro-and mesopore volume there are some fluctuations, the micropore volume decreases systematically as the amount of PC added increases, independently of the technique used in its assessment and although the two techniques evaluate micropores of different size. At the same time, petroleum coke addition produces a decrease in the reactivity of the metallurgical cokes [4,6]. This decrease can not be attributed to the dilution of some of the catalytic oxides of the ashes existing in the metallurgical coke [7], because even with a 20 wt% addition of PC this potential catalytic effect should remain the same.…”

Influence of charcoal fines on the thermoplastic properties of coking coals and the optical properties of the semicoke

“…Several reasons justified the selection of the Gieseler semicokes: i) The coal composition is a key factor in the development of optical texture and porous structure of coal-based carbons and therefore the optical textures of semicoke and coke are closely related to the nature of the parent coal; ii) most of the characteristics of high-temperature coke are established in the temperature range 350-500°C, and after the resolidification process, the organization of carbon arrangements in the semicoke is preserved under the usual conditions of coke oven operation (Loison et al, 1989); iii) Gieseler plastometry is a useful technique and widely used in research and industry when deciding which coal or additive to use in a blend for coke production and to predict coke quality; iv) semicokes produced in dynamic and isothermal conditions in a Gieseler plastometer or in laboratory-scale ovens have provided valuable information on the development of optical texture as a function of coal properties (Hower and Lloyd, 1999) as well as on the mechanisms involved in the development of coal rheological properties with carbon-bearing additives (Grint et al, 1985;van Krevelen, 1993;Clemens and Matheson, 1995;Menendez et al, 1996Menendez et al, , 1997Sakurovs, 2000).…”

Partial briquetting vs direct addition of biomass in coking blends

“…The use of additives is a common practice in cokemaking in the search for alternative materials with which to make low-cost coking blends and to improve the coking characteristics of a specific coal blend [4][5][6][7][8]. With these considerations in mind the inclusion of biomass in coking blends has been the subject of a number of recent studies [9][10][11][12].…”