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Metallurgical coke is a key component in the blast furnace ironmaking process. It is a complex composite material containing different forms of carbonaceous materials, mineral components and a pore structure. It also has significant heterogeneity in its mineralogy (type and particle size), carbon forms and phase dispersion. This complexity and heterogeneity increases the uncertainty in any testing of the coke and makes it difficult to quantitatively evaluate specific factors that influence coke gasification in CO2 gas. The mineralogy metallurgical of coke is a key parameter that affects coke gasification. Further, it is also known that Ca-containing minerals increase the gasification rate. A better understanding of their effect on coke is of particular interest to coke producers and users. In this study, the effects of Ca-containing minerals on coke analogue gasification are evaluated. The use of the coke analogue is to overcome/address uncertainty issues associated with coke complexity and heterogeneity. The primary aims of this thesis are: 1. To establish how representative the coke analogue is of metallurgical coke. 2. To test whether the analogue has similar rate controlling kinetics to that of industrial coke. 3. To test the effects of the Ca containing minerals on coke analogue gasification in CO2. 4. To test whether the Random Pore Model can be used to predict coke analogue gasification.

All rights reserved. A coke analogue with a simplified carbon structure, mineral particle size and distribution was used for the study of coke reactivity to address experimental uncertainty issues introduced by coke's complexity and heterogeneity. The main focus was to assess the effects of CaO (lime) on the analogue's reaction kinetics. In this study coke gasification in CO2 over the temperature range of 1023-1623 K is investigated using the coke analogue. The analogue's reactivity in CO2 was found to be increased, relative to the coke analogue with no minerals. This agrees with the effect of CaO in general coke studies. It was observed that the behaviour of the Ca in the analogue was not typically found for other minerals studied, as CaO appeared to go into solution within the analogue carbon matrix. In this paper, some analysis for this dissolution effect and its influence on rapid reaction rate of Ca doped coke analogue are presented.

Coke plays vital roles in the ironmaking blast furnace process. It is the furnace fuel for the high temperature process and the primary source of CO gas for the reduction of iron oxide to metal. It is also an important material in maintaining the furnace permeability required for the high production rates1. The behavior of coke in the blast furnace is related to its hot strength and reactivity2. Therefore, to understand the coke behavior in the blast furnace, coke reactivity in the blast furnace should be well understood.

The coke analogue is a new research tool that has been developed to quantify and characterize the effect minerals in coke have on coke reactivity. The analogue material is made from a number of different carbon or carbon containing materials and minerals to in part replicate real industrial coke's reactivity behavior. Elucidation of the effects of minerals on coke reactivity has proved difficult due to the complex and heterogeneous nature of industrial coke and the potential non-additive effects of minerals on coke reactivity. The coke analogue addresses this complexity and heterogeneity through control of its mineralogy, mineral size and mineral dispersion through the analogue, porosity and carbon structures. Initial studies using the analogue were focused on coke dissolution kinetics in liquid iron but recent work has focused in characterization of its porosity, carbon structure and rate of reaction.

In this study the suitability of a laboratory analogue for coke for studying the reactivity of coke was evaluated. Coke reactivity and strength are closely related, as such, an improved understanding of the kinetics of blast furnace coke reactions can be used to enhance blast furnace performance. However, coke is a complex composite material, with an inherent heterogeneity with respect to oxide phase composition and phase dispersion. The complexity and heterogeneity of coke makes it difficult to isolate the effects of a specific component on coke reactivity. The coke analogue has been developed to address these issues and was used for controlled testing of specific mineral, and to some degree maceral, effects on reactivity. The reaction of coke analogue with CO2 was studied using thermogravimetric analysis to measure the kinetics at temperatures from 850 to 1350°C. The reaction rate behaviour of the analogue is similar to that reported for industrial coke. The gasification rate increased with increasing temperature and three reaction zones corresponding to different kinetic control regimes, as found in industrial coke, have been identified. These findings show that the coke analogue demonstrates similar reaction kinetics to industrial coke indicating its suitability for use in coke kinetic studies.

A coke analogue has been developed to evaluate mineral effects on coke reactivity. Elucidation of the effects of minerals on coke reactivity has proved difficult due to the complex and heterogeneous nature of industrial coke and the potential non-additive effects of minerals on coke reactivity. The coke analogue addresses this complexity and heterogeneity through control of its mineralogy, porosity and carbon structures. Recent studies have shown the analogue is capable of discriminating individual mineral effects on coke reactivity. In this paper the reaction mechanism of the analogues reactivity in CO2 is assessed and compared with that of industrial coke.