The need for more efficient blast furnaces is even greater now that there are stricter environmental regulations on greenhouse gas (GHG) emissions. Coke within the blast furnace not only supports the furnace bed and allows gas flow, it also carburises liquid iron. The carburisation of iron is one of the most important reactions and must be better understood if the ironmaking process in the blast furnace is to be made more sustainable. By understanding what coke properties influence the rate at which coke dissolves in iron we can predict a coke?s performance and use it to determine its quality. As carbon dissolution rates have only been determined for a few cokes, a systematic and comprehensive study was conducted on the dissolution of carbon from nine Australian cokes into liquid iron. The kinetics of carbon dissolution from Cokes A to I was measured and a range of experimental techniques were used to elucidate the dominant rate influencing factors. The role of coke structure, coke inorganic matter composition and yield and temperature were investigated. Furthermore, the influence of interfacial products and dynamic wettability studies were also conducted. The carburiser cover method was used to measure carbon pick-up as a function of time over the temperature range of 1450-1550 ??C. Fundamental data on the apparent carbon dissolution rate constant (K) in molten iron at 1550 ??C for Cokes A to I were obtained and ranged from K (x 103 s-1) = 0.47 to K (x 103 s-1) = 14.7. The wide variation in K showed that not all cokes dissolve at similar rates. In fact one of the nine cokes in this investigation dissolved at a rate comparable to graphite dissolution rates. The apparent carbon dissolution activation energy, Ea, for two of the nine cokes plus synthetic graphite (SG) was also determined. The Ea obtained for SG (Ea = 54 kJ / mol) was in agreement with literature values and was consistent with a diffusion controlled mechanism. The observed Ea values for Cokes D and F (313 kJ / mol and 479 kJ / mol respectively) are an order of magnitude larger than the Ea obtained for SG. The difference in Ea between cokes and SG does not appear to be solely due to differences in the structure of the carbon source. The difference in Ea between the cokes was attributed to differences in their inorganic matter composition. The interfacial contact area is a function of inorganic matter yield and composition, which in turn is a function of temperature. Therefore, as temperature decreases the slag / ash layer produced at the carbon / iron interface can increase in area and viscosity and thus hinder carbon dissolution and transfer, and increasing the apparent activation energy for carbon dissolution. Thus, the differences in viscosity and melting temperature of the interfacial product play a key role. Wettability experiments were carried out using the sessile drop technique. The wettability of Cokes D, F and G with liquid iron at 1550 ??C was measured as a function of time. All three coke samples showed non-wetting behaviour with contact angles ranging between 123-129?? in the initial stages and between 109-114?? after two hours of contact. The differences in the wettability of the three coke samples could not explain the large differences in dissolution rates observed between these cokes. Thus, the wettability of these coke samples was not considered a dominant factor in influencing the rate of carbon dissolution. The sessile drop technique was also used to study the interfacial products formed at the coke / iron interface. The interfacial products formed on the underside of the iron droplet after contact with Cokes F and G were initially different in regards to the morphology and chemical composition. The interfacial product formed with Coke G had a network or mesh like structure that seemed to wet the iron droplet much better than the interfacial product formed with Coke F. In contrast, Fe globules and discrete interfacial products were observed in Coke F. It was suggested that this was due to differences in inorganic matter content, especially in calcium (Ca) and sulfur (S) content in the coke. Formation of interfacial products containing sulfides, such as calcium sulfide (CaS) and manganese sulfide (MnS), were observed on the iron side of the interface of both Cokes F and G. As a result, the interfacial products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution and decreasing the rate of carbon dissolution. The presence of MnS may act to lower the liquidus temperature of the interfacial product, which in turn can affect the overall viscosity of the interfacial layer. Thus, the deposition of reaction products at the interfacial region can have a significant effect on carbon dissolution rates. The mineral pyrrhotite was also identified as a significant factor in influencing the rate of carbon dissolution. Electron dispersive X-ray analyses of Coke F identified iron to be in close association with sulfur. These Fe / S species have atomic ratio similar to pyrrhotite (Fe1-xS) or troilite (FeS). Pyrrhotite in coke can decompose to release gaseous sulfur and metallic iron, which can be carburised by carbon in the surrounding area to form Fe-C particles. Thus, carburisation of liquid iron can occur via Fe-C particles. There was little difference in structure between the nine coke samples and therefore the high dissolution rates of Coke F, cannot be explained on the basis of crystallite size or anisotropic carbon content. Inorganic matter yield and composition were identified as the dominant rate influencing factors on carbon dissolution. More specifically: - High content of iron phases, such as iron oxides and pyrrhotite, can lead to an increase in carbon dissolution rates. This maybe due to increased amounts of Fe-C particles that are formed upon the reduction of magnetite and decomposition of pyrrhotite, and carried through the slag layer to carburise the bulk liquid iron. - High aluminium oxide content can lead to a decrease in carbon dissolution rates. This maybe due to higher ash fusion / melting temperature or decrease in wettability, both of which lead to a decrease in carbon / iron contact area. - Formation of interfacial products, such as CaS and MnS, can lead to a decrease in carbon dissolution rates. Such products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution. However, the presence of MnS may act to lower the liquidus temperature of the interfacial product. - An increase in temperature increases the rate of carbon dissolution. This dependence is predominantly due to the composition of the inorganic matter present in cokes, which influences the viscosity and melting point of the interfacial product formed and hence contact area between coke and iron.

The need for more efficient blast furnaces is even greater now that there are stricter environmental regulations on greenhouse gas (GHG) emissions. Coke within the blast furnace not only supports the furnace bed and allows gas flow, it also carburises liquid iron. The carburisation of iron is one of the most important reactions and must be better understood if the ironmaking process in the blast furnace is to be made more sustainable. By understanding what coke properties influence the rate at which coke dissolves in iron we can predict a coke?s performance and use it to determine its quality. As carbon dissolution rates have only been determined for a few cokes, a systematic and comprehensive study was conducted on the dissolution of carbon from nine Australian cokes into liquid iron. The kinetics of carbon dissolution from Cokes A to I was measured and a range of experimental techniques were used to elucidate the dominant rate influencing factors. The role of coke structure, coke inorganic matter composition and yield and temperature were investigated. Furthermore, the influence of interfacial products and dynamic wettability studies were also conducted. The carburiser cover method was used to measure carbon pick-up as a function of time over the temperature range of 1450-1550 ??C. Fundamental data on the apparent carbon dissolution rate constant (K) in molten iron at 1550 ??C for Cokes A to I were obtained and ranged from K (x 103 s-1) = 0.47 to K (x 103 s-1) = 14.7. The wide variation in K showed that not all cokes dissolve at similar rates. In fact one of the nine cokes in this investigation dissolved at a rate comparable to graphite dissolution rates. The apparent carbon dissolution activation energy, Ea, for two of the nine cokes plus synthetic graphite (SG) was also determined. The Ea obtained for SG (Ea = 54 kJ / mol) was in agreement with literature values and was consistent with a diffusion controlled mechanism. The observed Ea values for Cokes D and F (313 kJ / mol and 479 kJ / mol respectively) are an order of magnitude larger than the Ea obtained for SG. The difference in Ea between cokes and SG does not appear to be solely due to differences in the structure of the carbon source. The difference in Ea between the cokes was attributed to differences in their inorganic matter composition. The interfacial contact area is a function of inorganic matter yield and composition, which in turn is a function of temperature. Therefore, as temperature decreases the slag / ash layer produced at the carbon / iron interface can increase in area and viscosity and thus hinder carbon dissolution and transfer, and increasing the apparent activation energy for carbon dissolution. Thus, the differences in viscosity and melting temperature of the interfacial product play a key role. Wettability experiments were carried out using the sessile drop technique. The wettability of Cokes D, F and G with liquid iron at 1550 ??C was measured as a function of time. All three coke samples showed non-wetting behaviour with contact angles ranging between 123-129?? in the initial stages and between 109-114?? after two hours of contact. The differences in the wettability of the three coke samples could not explain the large differences in dissolution rates observed between these cokes. Thus, the wettability of these coke samples was not considered a dominant factor in influencing the rate of carbon dissolution. The sessile drop technique was also used to study the interfacial products formed at the coke / iron interface. The interfacial products formed on the underside of the iron droplet after contact with Cokes F and G were initially different in regards to the morphology and chemical composition. The interfacial product formed with Coke G had a network or mesh like structure that seemed to wet the iron droplet much better than the interfacial product formed with Coke F. In contrast, Fe globules and discrete interfacial products were observed in Coke F. It was suggested that this was due to differences in inorganic matter content, especially in calcium (Ca) and sulfur (S) content in the coke. Formation of interfacial products containing sulfides, such as calcium sulfide (CaS) and manganese sulfide (MnS), were observed on the iron side of the interface of both Cokes F and G. As a result, the interfacial products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution and decreasing the rate of carbon dissolution. The presence of MnS may act to lower the liquidus temperature of the interfacial product, which in turn can affect the overall viscosity of the interfacial layer. Thus, the deposition of reaction products at the interfacial region can have a significant effect on carbon dissolution rates. The mineral pyrrhotite was also identified as a significant factor in influencing the rate of carbon dissolution. Electron dispersive X-ray analyses of Coke F identified iron to be in close association with sulfur. These Fe / S species have atomic ratio similar to pyrrhotite (Fe1-xS) or troilite (FeS). Pyrrhotite in coke can decompose to release gaseous sulfur and metallic iron, which can be carburised by carbon in the surrounding area to form Fe-C particles. Thus, carburisation of liquid iron can occur via Fe-C particles. There was little difference in structure between the nine coke samples and therefore the high dissolution rates of Coke F, cannot be explained on the basis of crystallite size or anisotropic carbon content. Inorganic matter yield and composition were identified as the dominant rate influencing factors on carbon dissolution. More specifically: - High content of iron phases, such as iron oxides and pyrrhotite, can lead to an increase in carbon dissolution rates. This maybe due to increased amounts of Fe-C particles that are formed upon the reduction of magnetite and decomposition of pyrrhotite, and carried through the slag layer to carburise the bulk liquid iron. - High aluminium oxide content can lead to a decrease in carbon dissolution rates. This maybe due to higher ash fusion / melting temperature or decrease in wettability, both of which lead to a decrease in carbon / iron contact area. - Formation of interfacial products, such as CaS and MnS, can lead to a decrease in carbon dissolution rates. Such products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution. However, the presence of MnS may act to lower the liquidus temperature of the interfacial product. - An increase in temperature increases the rate of carbon dissolution. This dependence is predominantly due to the composition of the inorganic matter present in cokes, which influences the viscosity and melting point of the interfacial product formed and hence contact area between coke and iron.

The need for more efficient blast furnaces is even greater now that there are stricter environmental regulations on greenhouse gas (GHG) emissions. Coke within the blast furnace not only supports the furnace bed and allows gas flow, it also carburises liquid iron. The carburisation of iron is one of the most important reactions and must be better understood if the ironmaking process in the blast furnace is to be made more sustainable. By understanding what coke properties influence the rate at which coke dissolves in iron we can predict a coke?s performance and use it to determine its quality. As carbon dissolution rates have only been determined for a few cokes, a systematic and comprehensive study was conducted on the dissolution of carbon from nine Australian cokes into liquid iron. The kinetics of carbon dissolution from Cokes A to I was measured and a range of experimental techniques were used to elucidate the dominant rate influencing factors. The role of coke structure, coke inorganic matter composition and yield and temperature were investigated. Furthermore, the influence of interfacial products and dynamic wettability studies were also conducted. The carburiser cover method was used to measure carbon pick-up as a function of time over the temperature range of 1450-1550 ??C. Fundamental data on the apparent carbon dissolution rate constant (K) in molten iron at 1550 ??C for Cokes A to I were obtained and ranged from K (x 103 s-1) = 0.47 to K (x 103 s-1) = 14.7. The wide variation in K showed that not all cokes dissolve at similar rates. In fact one of the nine cokes in this investigation dissolved at a rate comparable to graphite dissolution rates. The apparent carbon dissolution activation energy, Ea, for two of the nine cokes plus synthetic graphite (SG) was also determined. The Ea obtained for SG (Ea = 54 kJ / mol) was in agreement with literature values and was consistent with a diffusion controlled mechanism. The observed Ea values for Cokes D and F (313 kJ / mol and 479 kJ / mol respectively) are an order of magnitude larger than the Ea obtained for SG. The difference in Ea between cokes and SG does not appear to be solely due to differences in the structure of the carbon source. The difference in Ea between the cokes was attributed to differences in their inorganic matter composition. The interfacial contact area is a function of inorganic matter yield and composition, which in turn is a function of temperature. Therefore, as temperature decreases the slag / ash layer produced at the carbon / iron interface can increase in area and viscosity and thus hinder carbon dissolution and transfer, and increasing the apparent activation energy for carbon dissolution. Thus, the differences in viscosity and melting temperature of the interfacial product play a key role. Wettability experiments were carried out using the sessile drop technique. The wettability of Cokes D, F and G with liquid iron at 1550 ??C was measured as a function of time. All three coke samples showed non-wetting behaviour with contact angles ranging between 123-129?? in the initial stages and between 109-114?? after two hours of contact. The differences in the wettability of the three coke samples could not explain the large differences in dissolution rates observed between these cokes. Thus, the wettability of these coke samples was not considered a dominant factor in influencing the rate of carbon dissolution. The sessile drop technique was also used to study the interfacial products formed at the coke / iron interface. The interfacial products formed on the underside of the iron droplet after contact with Cokes F and G were initially different in regards to the morphology and chemical composition. The interfacial product formed with Coke G had a network or mesh like structure that seemed to wet the iron droplet much better than the interfacial product formed with Coke F. In contrast, Fe globules and discrete interfacial products were observed in Coke F. It was suggested that this was due to differences in inorganic matter content, especially in calcium (Ca) and sulfur (S) content in the coke. Formation of interfacial products containing sulfides, such as calcium sulfide (CaS) and manganese sulfide (MnS), were observed on the iron side of the interface of both Cokes F and G. As a result, the interfacial products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution and decreasing the rate of carbon dissolution. The presence of MnS may act to lower the liquidus temperature of the interfacial product, which in turn can affect the overall viscosity of the interfacial layer. Thus, the deposition of reaction products at the interfacial region can have a significant effect on carbon dissolution rates. The mineral pyrrhotite was also identified as a significant factor in influencing the rate of carbon dissolution. Electron dispersive X-ray analyses of Coke F identified iron to be in close association with sulfur. These Fe / S species have atomic ratio similar to pyrrhotite (Fe1-xS) or troilite (FeS). Pyrrhotite in coke can decompose to release gaseous sulfur and metallic iron, which can be carburised by carbon in the surrounding area to form Fe-C particles. Thus, carburisation of liquid iron can occur via Fe-C particles. There was little difference in structure between the nine coke samples and therefore the high dissolution rates of Coke F, cannot be explained on the basis of crystallite size or anisotropic carbon content. Inorganic matter yield and composition were identified as the dominant rate influencing factors on carbon dissolution. More specifically: - High content of iron phases, such as iron oxides and pyrrhotite, can lead to an increase in carbon dissolution rates. This maybe due to increased amounts of Fe-C particles that are formed upon the reduction of magnetite and decomposition of pyrrhotite, and carried through the slag layer to carburise the bulk liquid iron. - High aluminium oxide content can lead to a decrease in carbon dissolution rates. This maybe due to higher ash fusion / melting temperature or decrease in wettability, both of which lead to a decrease in carbon / iron contact area. - Formation of interfacial products, such as CaS and MnS, can lead to a decrease in carbon dissolution rates. Such products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution. However, the presence of MnS may act to lower the liquidus temperature of the interfacial product. - An increase in temperature increases the rate of carbon dissolution. This dependence is predominantly due to the composition of the inorganic matter present in cokes, which influences the viscosity and melting point of the interfacial product formed and hence contact area between coke and iron.

The need for more efficient blast furnaces is even greater now that there are stricter environmental regulations on greenhouse gas (GHG) emissions. Coke within the blast furnace not only supports the furnace bed and allows gas flow, it also carburises liquid iron. The carburisation of iron is one of the most important reactions and must be better understood if the ironmaking process in the blast furnace is to be made more sustainable. By understanding what coke properties influence the rate at which coke dissolves in iron we can predict a coke?s performance and use it to determine its quality. As carbon dissolution rates have only been determined for a few cokes, a systematic and comprehensive study was conducted on the dissolution of carbon from nine Australian cokes into liquid iron. The kinetics of carbon dissolution from Cokes A to I was measured and a range of experimental techniques were used to elucidate the dominant rate influencing factors. The role of coke structure, coke inorganic matter composition and yield and temperature were investigated. Furthermore, the influence of interfacial products and dynamic wettability studies were also conducted. The carburiser cover method was used to measure carbon pick-up as a function of time over the temperature range of 1450-1550 ??C. Fundamental data on the apparent carbon dissolution rate constant (K) in molten iron at 1550 ??C for Cokes A to I were obtained and ranged from K (x 103 s-1) = 0.47 to K (x 103 s-1) = 14.7. The wide variation in K showed that not all cokes dissolve at similar rates. In fact one of the nine cokes in this investigation dissolved at a rate comparable to graphite dissolution rates. The apparent carbon dissolution activation energy, Ea, for two of the nine cokes plus synthetic graphite (SG) was also determined. The Ea obtained for SG (Ea = 54 kJ / mol) was in agreement with literature values and was consistent with a diffusion controlled mechanism. The observed Ea values for Cokes D and F (313 kJ / mol and 479 kJ / mol respectively) are an order of magnitude larger than the Ea obtained for SG. The difference in Ea between cokes and SG does not appear to be solely due to differences in the structure of the carbon source. The difference in Ea between the cokes was attributed to differences in their inorganic matter composition. The interfacial contact area is a function of inorganic matter yield and composition, which in turn is a function of temperature. Therefore, as temperature decreases the slag / ash layer produced at the carbon / iron interface can increase in area and viscosity and thus hinder carbon dissolution and transfer, and increasing the apparent activation energy for carbon dissolution. Thus, the differences in viscosity and melting temperature of the interfacial product play a key role. Wettability experiments were carried out using the sessile drop technique. The wettability of Cokes D, F and G with liquid iron at 1550 ??C was measured as a function of time. All three coke samples showed non-wetting behaviour with contact angles ranging between 123-129?? in the initial stages and between 109-114?? after two hours of contact. The differences in the wettability of the three coke samples could not explain the large differences in dissolution rates observed between these cokes. Thus, the wettability of these coke samples was not considered a dominant factor in influencing the rate of carbon dissolution. The sessile drop technique was also used to study the interfacial products formed at the coke / iron interface. The interfacial products formed on the underside of the iron droplet after contact with Cokes F and G were initially different in regards to the morphology and chemical composition. The interfacial product formed with Coke G had a network or mesh like structure that seemed to wet the iron droplet much better than the interfacial product formed with Coke F. In contrast, Fe globules and discrete interfacial products were observed in Coke F. It was suggested that this was due to differences in inorganic matter content, especially in calcium (Ca) and sulfur (S) content in the coke. Formation of interfacial products containing sulfides, such as calcium sulfide (CaS) and manganese sulfide (MnS), were observed on the iron side of the interface of both Cokes F and G. As a result, the interfacial products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution and decreasing the rate of carbon dissolution. The presence of MnS may act to lower the liquidus temperature of the interfacial product, which in turn can affect the overall viscosity of the interfacial layer. Thus, the deposition of reaction products at the interfacial region can have a significant effect on carbon dissolution rates. The mineral pyrrhotite was also identified as a significant factor in influencing the rate of carbon dissolution. Electron dispersive X-ray analyses of Coke F identified iron to be in close association with sulfur. These Fe / S species have atomic ratio similar to pyrrhotite (Fe1-xS) or troilite (FeS). Pyrrhotite in coke can decompose to release gaseous sulfur and metallic iron, which can be carburised by carbon in the surrounding area to form Fe-C particles. Thus, carburisation of liquid iron can occur via Fe-C particles. There was little difference in structure between the nine coke samples and therefore the high dissolution rates of Coke F, cannot be explained on the basis of crystallite size or anisotropic carbon content. Inorganic matter yield and composition were identified as the dominant rate influencing factors on carbon dissolution. More specifically: - High content of iron phases, such as iron oxides and pyrrhotite, can lead to an increase in carbon dissolution rates. This maybe due to increased amounts of Fe-C particles that are formed upon the reduction of magnetite and decomposition of pyrrhotite, and carried through the slag layer to carburise the bulk liquid iron. - High aluminium oxide content can lead to a decrease in carbon dissolution rates. This maybe due to higher ash fusion / melting temperature or decrease in wettability, both of which lead to a decrease in carbon / iron contact area. - Formation of interfacial products, such as CaS and MnS, can lead to a decrease in carbon dissolution rates. Such products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution. However, the presence of MnS may act to lower the liquidus temperature of the interfacial product. - An increase in temperature increases the rate of carbon dissolution. This dependence is predominantly due to the composition of the inorganic matter present in cokes, which influences the viscosity and melting point of the interfacial product formed and hence contact area between coke and iron.

The need for more efficient blast furnaces is even greater now that there are stricter environmental regulations on greenhouse gas (GHG) emissions. Coke within the blast furnace not only supports the furnace bed and allows gas flow, it also carburises liquid iron. The carburisation of iron is one of the most important reactions and must be better understood if the ironmaking process in the blast furnace is to be made more sustainable. By understanding what coke properties influence the rate at which coke dissolves in iron we can predict a coke?s performance and use it to determine its quality. As carbon dissolution rates have only been determined for a few cokes, a systematic and comprehensive study was conducted on the dissolution of carbon from nine Australian cokes into liquid iron. The kinetics of carbon dissolution from Cokes A to I was measured and a range of experimental techniques were used to elucidate the dominant rate influencing factors. The role of coke structure, coke inorganic matter composition and yield and temperature were investigated. Furthermore, the influence of interfacial products and dynamic wettability studies were also conducted. The carburiser cover method was used to measure carbon pick-up as a function of time over the temperature range of 1450-1550 ??C. Fundamental data on the apparent carbon dissolution rate constant (K) in molten iron at 1550 ??C for Cokes A to I were obtained and ranged from K (x 103 s-1) = 0.47 to K (x 103 s-1) = 14.7. The wide variation in K showed that not all cokes dissolve at similar rates. In fact one of the nine cokes in this investigation dissolved at a rate comparable to graphite dissolution rates. The apparent carbon dissolution activation energy, Ea, for two of the nine cokes plus synthetic graphite (SG) was also determined. The Ea obtained for SG (Ea = 54 kJ / mol) was in agreement with literature values and was consistent with a diffusion controlled mechanism. The observed Ea values for Cokes D and F (313 kJ / mol and 479 kJ / mol respectively) are an order of magnitude larger than the Ea obtained for SG. The difference in Ea between cokes and SG does not appear to be solely due to differences in the structure of the carbon source. The difference in Ea between the cokes was attributed to differences in their inorganic matter composition. The interfacial contact area is a function of inorganic matter yield and composition, which in turn is a function of temperature. Therefore, as temperature decreases the slag / ash layer produced at the carbon / iron interface can increase in area and viscosity and thus hinder carbon dissolution and transfer, and increasing the apparent activation energy for carbon dissolution. Thus, the differences in viscosity and melting temperature of the interfacial product play a key role. Wettability experiments were carried out using the sessile drop technique. The wettability of Cokes D, F and G with liquid iron at 1550 ??C was measured as a function of time. All three coke samples showed non-wetting behaviour with contact angles ranging between 123-129?? in the initial stages and between 109-114?? after two hours of contact. The differences in the wettability of the three coke samples could not explain the large differences in dissolution rates observed between these cokes. Thus, the wettability of these coke samples was not considered a dominant factor in influencing the rate of carbon dissolution. The sessile drop technique was also used to study the interfacial products formed at the coke / iron interface. The interfacial products formed on the underside of the iron droplet after contact with Cokes F and G were initially different in regards to the morphology and chemical composition. The interfacial product formed with Coke G had a network or mesh like structure that seemed to wet the iron droplet much better than the interfacial product formed with Coke F. In contrast, Fe globules and discrete interfacial products were observed in Coke F. It was suggested that this was due to differences in inorganic matter content, especially in calcium (Ca) and sulfur (S) content in the coke. Formation of interfacial products containing sulfides, such as calcium sulfide (CaS) and manganese sulfide (MnS), were observed on the iron side of the interface of both Cokes F and G. As a result, the interfacial products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution and decreasing the rate of carbon dissolution. The presence of MnS may act to lower the liquidus temperature of the interfacial product, which in turn can affect the overall viscosity of the interfacial layer. Thus, the deposition of reaction products at the interfacial region can have a significant effect on carbon dissolution rates. The mineral pyrrhotite was also identified as a significant factor in influencing the rate of carbon dissolution. Electron dispersive X-ray analyses of Coke F identified iron to be in close association with sulfur. These Fe / S species have atomic ratio similar to pyrrhotite (Fe1-xS) or troilite (FeS). Pyrrhotite in coke can decompose to release gaseous sulfur and metallic iron, which can be carburised by carbon in the surrounding area to form Fe-C particles. Thus, carburisation of liquid iron can occur via Fe-C particles. There was little difference in structure between the nine coke samples and therefore the high dissolution rates of Coke F, cannot be explained on the basis of crystallite size or anisotropic carbon content. Inorganic matter yield and composition were identified as the dominant rate influencing factors on carbon dissolution. More specifically: - High content of iron phases, such as iron oxides and pyrrhotite, can lead to an increase in carbon dissolution rates. This maybe due to increased amounts of Fe-C particles that are formed upon the reduction of magnetite and decomposition of pyrrhotite, and carried through the slag layer to carburise the bulk liquid iron. - High aluminium oxide content can lead to a decrease in carbon dissolution rates. This maybe due to higher ash fusion / melting temperature or decrease in wettability, both of which lead to a decrease in carbon / iron contact area. - Formation of interfacial products, such as CaS and MnS, can lead to a decrease in carbon dissolution rates. Such products can act as a physical barrier blocking iron and coke contact, thus reducing the contact area for carbon dissolution. However, the presence of MnS may act to lower the liquidus temperature of the interfacial product. - An increase in temperature increases the rate of carbon dissolution. This dependence is predominantly due to the composition of the inorganic matter present in cokes, which influences the viscosity and melting point of the interfacial product formed and hence contact area between coke and iron.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains ix, 193 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 150-156).

This work is divided into two main parts, investigational and theoretical. The first part deals with the investigation of deposition values around integrated iron and steel works, and coke works, in South Wales, and with the changes in such values which arise as a result of modifications to process control or to arrestment equipment. A method of evaluation of such changes, based on the cumulative sum technique, is developed, which m1n1m1ses the effect of seasonal variations in the deposition values. It is demonstrated that there are two significant sources of particulate emission, from coke oven discharges, and from coke quenching. These are shown to have different spatial distributions, emissions from quench towers being very widespread, whereas emissions from oven discharges deposit relatively closer to the source. Methods to reduce both of these sources are described: It is shown that the use of arrestors in quench towers leads to enhanced emission of dissolved solids, but that the increase can be controlled by the use of additional sprays above the arrestors. The second part considers some theoretical aspects of quench tower operation. It is shown that the installation of arrestors leads to changes in gas temperature and gas composition in a quench tower, which cause increases in terminal settling velocity. The same changes lead to reduced condensation within the quench tower, and hence greater emission of steam, which gives a more buoyant emission, with more widespread dispersion than from open quench towers, as well as enhanced emissions of dissolved solids. Calculations are included which confirm the extent of the dispersion from towers fitted with arrestment devices.

De nos jours, le seul procédé industriellement applicable pour la production de l’aluminium est connu sous le nom du procédé de Hall-Héroult. Le procédé utilise essentiellement des matériaux à base de carbone comme électrodes (anode et cathode). La productivité et l’efficacité énergétique du procédé sont étroitement liées à la qualité de l’anode (uniformité et stabilité des propriétés requises). Dans ce projet, nous avons étudié différents paramètres pouvant influencer l’uniformité des propriétés finales des anodes lors de leur cuisson principalement par la détermination de la résistivité électrique. Le processus de cuisson est la dernière étape du procédé de fabrication des anodes. Il s’agit d’une étape très critique, car c’est ici que les anodes subissent les plus importantes transformations microstructurales leur conférant les propriétés requises à leur utilisation dans le procédé de Hall-Héroult. Pendant la cuisson, les anodes sont empilées dans un four et cuites suivant des profils de température prédéfinis. Cela entraine la génération de contraintes mécaniques dans les anodes, causées par l’empilement, combinées aux transformations thermochimiques, causées par le processus de cuisson. La conséquence de ce phénomène peut mener à une anisotropie au niveau des propriétés des anodes. L’hypothèse est que lors de la cuisson, les anodes supérieures peuvent générer des pressions externes sur les anodes inférieures, provoquant ainsi le réarrangement des particules de coke dans la structure interne de l’anode. Ce changement pourrait mener à la réduction de la distance entre les particules affectant possiblement la résistivité électrique. Dans ce travail, la variation de la résistivité électrique d’une série d'anodes industrielles en fonction de leur position dans les fours de cuisson a été examinée dans un premier temps. Ensuite, à travers des travaux expérimentaux, menés en laboratoire, des échantillons d'anodes ont été fabriqués et cuits sous différentes pressions externes. Enfin, leur résistivité électrique a été déterminée afin d’établir une relation entre la force mécanique appliquée et la résistivité électrique. / Nowadays, the only industrially applicable process to produce aluminum is known as the Hall-Héroult process. The process essentially uses carbon-based materials as electrodes (anodes and cathodes). The productivity and energy efficiency of the process is closely linked to the quality of the anodes (uniformity and properties variations). In this project, we studied different parameters that could influence the uniformity of the anode final properties by mainly determining their electrical resistivity. The baking process is the last step in the anode manufacturing process. This is a very critical step while the anodes undergo the most significant microstructural transformations giving them the properties required for their use in the Hall-Héroult process. During baking, the anodes are stacked in the furnace and baked according to predefined temperature profiles leading to the generation of mechanical stresses, due to stacking, combined with thermochemical transformations, due to the baking process. The consequence of this phenomena can lead to anisotropy in terms of anode internal properties. The hypothesis is that during baking, the upper anodes can exert an external pressure on the lower anodes, thus causing the rearrangement of the coke particles in the internal structure of the anode. This change could lead to a reduction in the distance between particles, possibly affecting the electrical resistivity. In this work, the variations in the electrical resistivity of a series of industrial anodes as a function of their position in the baking furnace were first examined. Then, through experimental work carried out in the laboratory, anode samples were fabricated and baked under different external pressures. Finally, their electrical resistivity was determined to establish a relationship between the applied mechanical force and the electrical resistivity.

Thesis (MBA)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: It was found that the hot metal cost of ISCOR Newcastle's single blast furnace can significantly be reduced by the correct use of an integrated model to predict reductant cost based mainly on coal blend. The model uses coal ash chemistry, fluiidity, vitrinite rank and volatile matter to predict coke strength after reaction (CSR), coke ash and coking yield. CSR is used to predict maximum allowable coke nut- and pea consumption in the furnace as well as hot blast temperature. Pitch injection levels are predicted using CSR and blast furnace production rates. Coke ash, pitch injection and hot blast temperature is used to predict the coke rate. The above is used with imported Chinese coke cost to accurately predict reductant cost. It was found that the current optimum blends should include Australian en Nieu Zeeland coals because of price and quality conciderations. Because of its low cost of production and low quality the optimum percentage of Grootegeluk in the blend is determined largely by its transfer price. / AFRIKAANSE OPSOMMING: Die vloeiyster koste van ISCOR Newcastle se enigste hoogoond kan drasties verlaag word deur die korrekte gebruik van 'n geïntegreerde model wat reduktant koste voorspel op grond van steenkoolmengsel. Die model gebruik die chemiese samestelling van steenkool-as, fluiiditeit, vitriniet rang en vlugstof om kooks warmsterkte (SNR), kooks-as en verkooksingsopbrengs te voorspel. SNR is gebruik om die maksimum kooksneute- en -erteverbruik in die hoogoond sowel as blaastemperatuur te voorspel. Pikinspuiting is bereken met SNR en hoogoond produksietempo's. Pikinspuiting en blaastemperatuur word saam met kooks-as gebruik om kookskoers te voorspel. Bogenoemde is saam met die koste van ingevoerde Chinese kooks gebruik om reduktant koste akkuraat te voorspel. Daar was bevind dat die huidige optimum mengsels Australiese en Nieu Zeelandse steenkool moet bevat as gevolg van huidige prys- en kwaliteitsoorwegings. As gevolg van sy lae produksiekoste en lae kwaliteit word die optimum hoeveelheid Grootegeluk bepaal deur sy oordragprys.

Cette étude concerne la formation d'hydrogène par le procédé de vaporeformage et la production de gaz de synthèse par le procédé de reformage à sec, au moyen de catalyseurs tout en augmentant la résistance à la formation de coke. Sept oxydes mixtes NiₓMg₆₋ₓAl₂ 800 (0 ≤ x ≤ 6) ont été obtenus, en passant par la voie hydrotalcite suivie d'une calcination à 800°C. L'espèce active dans les deux réactions étudiées est le nickel métallique. Une partie de ces oxydes a été imprégnée par 0,5 % en masse de ruthénium et recalcinée à 800°C, puisque le ruthénium améliore la réductibilité des espèces oxydes de nickel. Dans le procédé de vaporeformage et en abscence de ruthénium, le prétraitement réducteur est une étape nécessaire pour activer le catalyseur. L'ajout du ruthénium améliore l'activité catalytique, la sélectivité et la résistance à la formation de coke des oxydes étudiés et ceci en abscence de prétraitement réducteur avant test. Une interaction ruthénium-nickel serait à l'origine de ces bonnes performances catalytiques. Le catalyseur Ru/Ni₆Al₂ 800 800 présente les meilleures performances catalytiques, parmi les systèmes étudiés, puisqu'il assure une meilleure interaction Ru-Ni. / This study is related to the formation of hydrogen by the steam reforming process and the production of synthesis gas by the dry reforming process, using catalysts, leading to increased resistance to coke formation. Seven mixed oxides NiₓMg₆₋ₓAl₂ 800 (0 ≤ x ≤ 6) were obtained, by hydrotalcite route followed by calcination at 800°C. Metallic nickel is the active species in both studied reactions. Some of these oxides have been impregnated with 0.5 wt % of ruthenium and recalcined at 800°C. In steam reforming test and in absence of ruthenium, the reducing pretreatment step is necessary to activate the catalyst. Ruthenium addition improves the catalytic activity, selectivity and the resistance to coke formation, with no reducing step prior to the test. An interaction between nickel and ruthenium is in origin of these good catalytic performances since ruthenium improves the reductibility of nickel species. The catalyst Ru/Ni₆Al₂ 800 800 presents the best catalytic performances among the studied systems, because it presents a better Ru-Ni interaction.