The Experts below are selected from a list of 2226 Experts worldwide ranked by ideXlab platform
S P E Forsmo - One of the best experts on this subject based on the ideXlab platform.
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mechanisms in oxidation and sintering of magnetite iron ore Green Pellets
Powder Technology, 2008Co-Authors: S P E Forsmo, Perolof Samskog, Seija Forsmo, Bo BjorkmanAbstract:Abstract Thermal volume changes and oxidation mechanisms in magnetite iron ore Green Pellets balled with 0.5% bentonite binder, as a function of raw material fineness and Pellet porosity, are shown. When a Pellet starts to oxidize, a shell of hematite is formed around the Pellet while the core still is magnetite. Dilatation curves were measured under non-oxidizing and oxidizing atmospheres to separately describe thermal volume changes in these two phases. Dilatation measurements showed contraction during oxidation between 330 and 900 °C by 0.5%. The extent of contraction was not influenced by the raw material fineness or the original porosity in Pellets. Sintering started earlier in the magnetite phase (950 °C) compared to the hematite phase (1100 °C). The sintering rate increased with increasing fineness in the magnetite concentrate. A finer grind in the raw material would, therefore, promote the formation of duplex structures with a more heavily sintered core pulling away from the less sintered outer shell. At constant porosity in Green Pellets, the oxidation time became longer as the magnetite concentrate became finer, because of the enhanced sintering. In practical balling, however, the increase in fineness would necessitate the use of more water in balling, which results in an increase in Green Pellet porosity. These two opposite effects levelled out and the oxidation time became constant when Green Pellets were balled at constant plasticity. Combining the results from the oxidation and dilatation studies revealed new information on the rate limiting factors in oxidation of iron ore Pellets. At 1100 °C, the diffusion rate of oxygen was limited by sintering in the magnetite core, taking place before oxidation rather than by the diffusion rate of oxygen through the oxidized hematite shell, as has been claimed in earlier literature. The oxidation rate was at maximum at around 1100 °C. At 1200 °C, the rate of oxidation substantially decreased because both the hematite shell and the magnetite core show heavy sintering at this temperature. Dilatometer measurements showed large thermal volume changes in the presence of olivine, at temperatures above 1200 °C. This is explained by the dissociation of hematite back to magnetite. Dissociation leads to an increase in the volume of the oxidized shell, while sintering of the magnetite core is further enhanced by the olivine additive.
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studies on the influence of a flotation collector reagent on iron ore Green Pellet properties
Powder Technology, 2008Co-Authors: S P E Forsmo, Bo Bjorkman, Perolof SamskogAbstract:Abstract The properties of iron ore Green Pellets with varying additions of a surface-active flotation collector reagent (Atrac) were studied by small-scale balling. The compression strength and plasticity were measured with a semi-automatic measuring device and the pressure curves were saved and subjected to further mathematical treatment. The Green Pellet breakage was also filmed with a high-speed camera. Adding Atrac to the Pellet feed seriously damaged the quality of Green Pellets, even in small dosages. This is because an increasing amount of air bubbles became so strongly attached on the particle surfaces that they could not be removed during compaction by balling. The adsorption of air in Green Pellets was seen as an increase in porosity and a decrease in the filling degree (proportion of pores filled with water). Both the wet and dry compression strength decreased. The air bubbles behaved in wet Green Pellets like large, plastic particles and the plasticity increased beyond an acceptable level. Breakage started inside the Green Pellets, along the air bubbles, and generated multi-breakage patterns in wet as well as dry Green Pellets. Green Pellet breakage to crumbs instead of a few distinct segments, promotes the generation of dust and fines and leads to lower bed permeability in the Pelletizing machine. The results show that the decrease in iron ore Green Pellet wet strength in the presence of surface-active agents is not fully described by the so called Rumpf equation, where surface tension and contact angle are used as variables to describe the capillary forces. The Green Pellet breakage in the presence of air bubbles took place by crack propagation along pore structures rather than through the loss of the capillary forces.
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a study on plasticity and compression strength in wet iron ore Green Pellets related to real process variations in raw material fineness
Powder Technology, 2008Co-Authors: S P E Forsmo, Perolof Samskog, Bo BjorkmanAbstract:Abstract The main binding force in wet iron ore Green Pellets has been found to be the cohesive force of the viscous binder. The wet compression strength (wet-CS) in Green Pellets is, however, also influenced by the Green Pellet plasticity. A certain degree of plasticity is needed to sustain the Green Pellet growth rate. Too much plasticity results in decreased bed permeability and production problems. As the plasticity increases, wet-CS decreases. The amount of moisture needed to create a given degree of plasticity depends on particle properties and on the particle size distribution. Therefore, it was of interest to study how wet-CS would be influenced by variations in raw material fineness, if the Green Pellet plasticity was kept constant, i.e. the Green Pellet properties would be compared under relevant industrial balling conditions. For this purpose, magnetite concentrates of different particle size distributions were balled in a laboratory drum and the moisture content for constant plasticity was determined for each of the materials. No difference in Green Pellet wet-CS as a function of the raw material fineness was found when the bentonite binder was used and the plasticity was adjusted to a constant level. Green Pellets prepared of raw materials with narrow size distributions were just as strong as those with broader ones. This is because the main binding force is the cohesive force of the viscous binder. In Green Pellets balled without the bentonite binder, wet-CS increased with increasing specific surface area in the raw material, in a similar manner as has been shown in earlier agglomeration literature. In this case, the capillary forces prevail. Comparison of wet-CS at constant moisture, instead of constant plasticity, would lead to erroneous conclusions. Fineness, or rather the slope of the particle size distribution curve, had a major impact on the moisture content needed for constant plasticity. If the slope increases, more water is needed to keep the plasticity on a constant level. Implications of these results in control of industrial iron ore balling circuits are discussed.
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Influence of Green Pellet properties on Pelletizing of magnetite iron ore
2007Co-Authors: S P E ForsmoAbstract:Magnetite iron ore Green Pellets are produced by balling moist concentrates to Green Pellets, which are then dried, oxidized to hematite, sintered, cooled and transported to steelmaking plants. The ...
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binding mechanisms in wet iron ore Green Pellets with a bentonite binder
Powder Technology, 2006Co-Authors: S P E Forsmo, Bo Bjorkman, Perolof Samskog, A J ApelqvistAbstract:Abstract Fundamental research during the past decade has been focussed on understanding the role of viscous forces on agglomerate deformability and strength. Much of this work has been done on glass spheres using Newtonian liquids as a binder. In this work, we show the variations in plasticity and strength of magnetite iron ore Green Pellets with varying liquid saturations and binder dosages (viscosities). For this purpose, a new measuring instrument was built to analyze the Green Pellet wet compression strength, plastic deformation and breakage pattern. Industrial iron ore Green Pellets are over-saturated and a supporting “network” of viscous liquid is formed on the Green Pellet surface. At least half, probably more, of the total binding force appeared to be due to the cohesive force of the network. The other half (or less) of the total compression strength can be explained by the capillary force. Due to irregularities on Green Pellet surfaces, both fully developed concave pore openings and saturated areas are expected to be found at the same time. Wet Green Pellets started showing plastic behaviour as they became over-saturated. In over-saturated Green Pellets, an explosive increase in plasticity with increasing moisture content was seen, due to the contemporary increase in porosity. Plasticity is an important Green Pellet property in balling and should gain the status of a standard method in Green Pellet characterization. It is suggested that the control strategy for the balling circuits be based on plastic deformation and compression strength of Green Pellets instead of the rather inaccurate drop number. The results also point out the importance of knowing whether the balling process should be controlled by adjusting the moisture content (plasticity) or by adjusting the bentonite dosage (viscosity). These two operations are not interchangeable—even if they would compensate in growth rate, the Green Pellet properties would differ. A new Green Pellet growth mechanism is suggested, based on the measured over-saturation. Firstly, Green Pellet plasticity needs to exceed a minimum level to enable growth. This limiting plasticity defines the material-specific moisture content needed in balling. Secondly, it is suggested that the growth rate be controlled by the viscosity of the superficial water layer rather than by the mobility of the pore water.
Perolof Samskog - One of the best experts on this subject based on the ideXlab platform.
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mechanisms in oxidation and sintering of magnetite iron ore Green Pellets
Powder Technology, 2008Co-Authors: S P E Forsmo, Perolof Samskog, Seija Forsmo, Bo BjorkmanAbstract:Abstract Thermal volume changes and oxidation mechanisms in magnetite iron ore Green Pellets balled with 0.5% bentonite binder, as a function of raw material fineness and Pellet porosity, are shown. When a Pellet starts to oxidize, a shell of hematite is formed around the Pellet while the core still is magnetite. Dilatation curves were measured under non-oxidizing and oxidizing atmospheres to separately describe thermal volume changes in these two phases. Dilatation measurements showed contraction during oxidation between 330 and 900 °C by 0.5%. The extent of contraction was not influenced by the raw material fineness or the original porosity in Pellets. Sintering started earlier in the magnetite phase (950 °C) compared to the hematite phase (1100 °C). The sintering rate increased with increasing fineness in the magnetite concentrate. A finer grind in the raw material would, therefore, promote the formation of duplex structures with a more heavily sintered core pulling away from the less sintered outer shell. At constant porosity in Green Pellets, the oxidation time became longer as the magnetite concentrate became finer, because of the enhanced sintering. In practical balling, however, the increase in fineness would necessitate the use of more water in balling, which results in an increase in Green Pellet porosity. These two opposite effects levelled out and the oxidation time became constant when Green Pellets were balled at constant plasticity. Combining the results from the oxidation and dilatation studies revealed new information on the rate limiting factors in oxidation of iron ore Pellets. At 1100 °C, the diffusion rate of oxygen was limited by sintering in the magnetite core, taking place before oxidation rather than by the diffusion rate of oxygen through the oxidized hematite shell, as has been claimed in earlier literature. The oxidation rate was at maximum at around 1100 °C. At 1200 °C, the rate of oxidation substantially decreased because both the hematite shell and the magnetite core show heavy sintering at this temperature. Dilatometer measurements showed large thermal volume changes in the presence of olivine, at temperatures above 1200 °C. This is explained by the dissociation of hematite back to magnetite. Dissociation leads to an increase in the volume of the oxidized shell, while sintering of the magnetite core is further enhanced by the olivine additive.
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studies on the influence of a flotation collector reagent on iron ore Green Pellet properties
Powder Technology, 2008Co-Authors: S P E Forsmo, Bo Bjorkman, Perolof SamskogAbstract:Abstract The properties of iron ore Green Pellets with varying additions of a surface-active flotation collector reagent (Atrac) were studied by small-scale balling. The compression strength and plasticity were measured with a semi-automatic measuring device and the pressure curves were saved and subjected to further mathematical treatment. The Green Pellet breakage was also filmed with a high-speed camera. Adding Atrac to the Pellet feed seriously damaged the quality of Green Pellets, even in small dosages. This is because an increasing amount of air bubbles became so strongly attached on the particle surfaces that they could not be removed during compaction by balling. The adsorption of air in Green Pellets was seen as an increase in porosity and a decrease in the filling degree (proportion of pores filled with water). Both the wet and dry compression strength decreased. The air bubbles behaved in wet Green Pellets like large, plastic particles and the plasticity increased beyond an acceptable level. Breakage started inside the Green Pellets, along the air bubbles, and generated multi-breakage patterns in wet as well as dry Green Pellets. Green Pellet breakage to crumbs instead of a few distinct segments, promotes the generation of dust and fines and leads to lower bed permeability in the Pelletizing machine. The results show that the decrease in iron ore Green Pellet wet strength in the presence of surface-active agents is not fully described by the so called Rumpf equation, where surface tension and contact angle are used as variables to describe the capillary forces. The Green Pellet breakage in the presence of air bubbles took place by crack propagation along pore structures rather than through the loss of the capillary forces.
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a study on plasticity and compression strength in wet iron ore Green Pellets related to real process variations in raw material fineness
Powder Technology, 2008Co-Authors: S P E Forsmo, Perolof Samskog, Bo BjorkmanAbstract:Abstract The main binding force in wet iron ore Green Pellets has been found to be the cohesive force of the viscous binder. The wet compression strength (wet-CS) in Green Pellets is, however, also influenced by the Green Pellet plasticity. A certain degree of plasticity is needed to sustain the Green Pellet growth rate. Too much plasticity results in decreased bed permeability and production problems. As the plasticity increases, wet-CS decreases. The amount of moisture needed to create a given degree of plasticity depends on particle properties and on the particle size distribution. Therefore, it was of interest to study how wet-CS would be influenced by variations in raw material fineness, if the Green Pellet plasticity was kept constant, i.e. the Green Pellet properties would be compared under relevant industrial balling conditions. For this purpose, magnetite concentrates of different particle size distributions were balled in a laboratory drum and the moisture content for constant plasticity was determined for each of the materials. No difference in Green Pellet wet-CS as a function of the raw material fineness was found when the bentonite binder was used and the plasticity was adjusted to a constant level. Green Pellets prepared of raw materials with narrow size distributions were just as strong as those with broader ones. This is because the main binding force is the cohesive force of the viscous binder. In Green Pellets balled without the bentonite binder, wet-CS increased with increasing specific surface area in the raw material, in a similar manner as has been shown in earlier agglomeration literature. In this case, the capillary forces prevail. Comparison of wet-CS at constant moisture, instead of constant plasticity, would lead to erroneous conclusions. Fineness, or rather the slope of the particle size distribution curve, had a major impact on the moisture content needed for constant plasticity. If the slope increases, more water is needed to keep the plasticity on a constant level. Implications of these results in control of industrial iron ore balling circuits are discussed.
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binding mechanisms in wet iron ore Green Pellets with a bentonite binder
Powder Technology, 2006Co-Authors: S P E Forsmo, Bo Bjorkman, Perolof Samskog, A J ApelqvistAbstract:Abstract Fundamental research during the past decade has been focussed on understanding the role of viscous forces on agglomerate deformability and strength. Much of this work has been done on glass spheres using Newtonian liquids as a binder. In this work, we show the variations in plasticity and strength of magnetite iron ore Green Pellets with varying liquid saturations and binder dosages (viscosities). For this purpose, a new measuring instrument was built to analyze the Green Pellet wet compression strength, plastic deformation and breakage pattern. Industrial iron ore Green Pellets are over-saturated and a supporting “network” of viscous liquid is formed on the Green Pellet surface. At least half, probably more, of the total binding force appeared to be due to the cohesive force of the network. The other half (or less) of the total compression strength can be explained by the capillary force. Due to irregularities on Green Pellet surfaces, both fully developed concave pore openings and saturated areas are expected to be found at the same time. Wet Green Pellets started showing plastic behaviour as they became over-saturated. In over-saturated Green Pellets, an explosive increase in plasticity with increasing moisture content was seen, due to the contemporary increase in porosity. Plasticity is an important Green Pellet property in balling and should gain the status of a standard method in Green Pellet characterization. It is suggested that the control strategy for the balling circuits be based on plastic deformation and compression strength of Green Pellets instead of the rather inaccurate drop number. The results also point out the importance of knowing whether the balling process should be controlled by adjusting the moisture content (plasticity) or by adjusting the bentonite dosage (viscosity). These two operations are not interchangeable—even if they would compensate in growth rate, the Green Pellet properties would differ. A new Green Pellet growth mechanism is suggested, based on the measured over-saturation. Firstly, Green Pellet plasticity needs to exceed a minimum level to enable growth. This limiting plasticity defines the material-specific moisture content needed in balling. Secondly, it is suggested that the growth rate be controlled by the viscosity of the superficial water layer rather than by the mobility of the pore water.
Bo Bjorkman - One of the best experts on this subject based on the ideXlab platform.
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mechanisms in oxidation and sintering of magnetite iron ore Green Pellets
Powder Technology, 2008Co-Authors: S P E Forsmo, Perolof Samskog, Seija Forsmo, Bo BjorkmanAbstract:Abstract Thermal volume changes and oxidation mechanisms in magnetite iron ore Green Pellets balled with 0.5% bentonite binder, as a function of raw material fineness and Pellet porosity, are shown. When a Pellet starts to oxidize, a shell of hematite is formed around the Pellet while the core still is magnetite. Dilatation curves were measured under non-oxidizing and oxidizing atmospheres to separately describe thermal volume changes in these two phases. Dilatation measurements showed contraction during oxidation between 330 and 900 °C by 0.5%. The extent of contraction was not influenced by the raw material fineness or the original porosity in Pellets. Sintering started earlier in the magnetite phase (950 °C) compared to the hematite phase (1100 °C). The sintering rate increased with increasing fineness in the magnetite concentrate. A finer grind in the raw material would, therefore, promote the formation of duplex structures with a more heavily sintered core pulling away from the less sintered outer shell. At constant porosity in Green Pellets, the oxidation time became longer as the magnetite concentrate became finer, because of the enhanced sintering. In practical balling, however, the increase in fineness would necessitate the use of more water in balling, which results in an increase in Green Pellet porosity. These two opposite effects levelled out and the oxidation time became constant when Green Pellets were balled at constant plasticity. Combining the results from the oxidation and dilatation studies revealed new information on the rate limiting factors in oxidation of iron ore Pellets. At 1100 °C, the diffusion rate of oxygen was limited by sintering in the magnetite core, taking place before oxidation rather than by the diffusion rate of oxygen through the oxidized hematite shell, as has been claimed in earlier literature. The oxidation rate was at maximum at around 1100 °C. At 1200 °C, the rate of oxidation substantially decreased because both the hematite shell and the magnetite core show heavy sintering at this temperature. Dilatometer measurements showed large thermal volume changes in the presence of olivine, at temperatures above 1200 °C. This is explained by the dissociation of hematite back to magnetite. Dissociation leads to an increase in the volume of the oxidized shell, while sintering of the magnetite core is further enhanced by the olivine additive.
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studies on the influence of a flotation collector reagent on iron ore Green Pellet properties
Powder Technology, 2008Co-Authors: S P E Forsmo, Bo Bjorkman, Perolof SamskogAbstract:Abstract The properties of iron ore Green Pellets with varying additions of a surface-active flotation collector reagent (Atrac) were studied by small-scale balling. The compression strength and plasticity were measured with a semi-automatic measuring device and the pressure curves were saved and subjected to further mathematical treatment. The Green Pellet breakage was also filmed with a high-speed camera. Adding Atrac to the Pellet feed seriously damaged the quality of Green Pellets, even in small dosages. This is because an increasing amount of air bubbles became so strongly attached on the particle surfaces that they could not be removed during compaction by balling. The adsorption of air in Green Pellets was seen as an increase in porosity and a decrease in the filling degree (proportion of pores filled with water). Both the wet and dry compression strength decreased. The air bubbles behaved in wet Green Pellets like large, plastic particles and the plasticity increased beyond an acceptable level. Breakage started inside the Green Pellets, along the air bubbles, and generated multi-breakage patterns in wet as well as dry Green Pellets. Green Pellet breakage to crumbs instead of a few distinct segments, promotes the generation of dust and fines and leads to lower bed permeability in the Pelletizing machine. The results show that the decrease in iron ore Green Pellet wet strength in the presence of surface-active agents is not fully described by the so called Rumpf equation, where surface tension and contact angle are used as variables to describe the capillary forces. The Green Pellet breakage in the presence of air bubbles took place by crack propagation along pore structures rather than through the loss of the capillary forces.
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a study on plasticity and compression strength in wet iron ore Green Pellets related to real process variations in raw material fineness
Powder Technology, 2008Co-Authors: S P E Forsmo, Perolof Samskog, Bo BjorkmanAbstract:Abstract The main binding force in wet iron ore Green Pellets has been found to be the cohesive force of the viscous binder. The wet compression strength (wet-CS) in Green Pellets is, however, also influenced by the Green Pellet plasticity. A certain degree of plasticity is needed to sustain the Green Pellet growth rate. Too much plasticity results in decreased bed permeability and production problems. As the plasticity increases, wet-CS decreases. The amount of moisture needed to create a given degree of plasticity depends on particle properties and on the particle size distribution. Therefore, it was of interest to study how wet-CS would be influenced by variations in raw material fineness, if the Green Pellet plasticity was kept constant, i.e. the Green Pellet properties would be compared under relevant industrial balling conditions. For this purpose, magnetite concentrates of different particle size distributions were balled in a laboratory drum and the moisture content for constant plasticity was determined for each of the materials. No difference in Green Pellet wet-CS as a function of the raw material fineness was found when the bentonite binder was used and the plasticity was adjusted to a constant level. Green Pellets prepared of raw materials with narrow size distributions were just as strong as those with broader ones. This is because the main binding force is the cohesive force of the viscous binder. In Green Pellets balled without the bentonite binder, wet-CS increased with increasing specific surface area in the raw material, in a similar manner as has been shown in earlier agglomeration literature. In this case, the capillary forces prevail. Comparison of wet-CS at constant moisture, instead of constant plasticity, would lead to erroneous conclusions. Fineness, or rather the slope of the particle size distribution curve, had a major impact on the moisture content needed for constant plasticity. If the slope increases, more water is needed to keep the plasticity on a constant level. Implications of these results in control of industrial iron ore balling circuits are discussed.
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binding mechanisms in wet iron ore Green Pellets with a bentonite binder
Powder Technology, 2006Co-Authors: S P E Forsmo, Bo Bjorkman, Perolof Samskog, A J ApelqvistAbstract:Abstract Fundamental research during the past decade has been focussed on understanding the role of viscous forces on agglomerate deformability and strength. Much of this work has been done on glass spheres using Newtonian liquids as a binder. In this work, we show the variations in plasticity and strength of magnetite iron ore Green Pellets with varying liquid saturations and binder dosages (viscosities). For this purpose, a new measuring instrument was built to analyze the Green Pellet wet compression strength, plastic deformation and breakage pattern. Industrial iron ore Green Pellets are over-saturated and a supporting “network” of viscous liquid is formed on the Green Pellet surface. At least half, probably more, of the total binding force appeared to be due to the cohesive force of the network. The other half (or less) of the total compression strength can be explained by the capillary force. Due to irregularities on Green Pellet surfaces, both fully developed concave pore openings and saturated areas are expected to be found at the same time. Wet Green Pellets started showing plastic behaviour as they became over-saturated. In over-saturated Green Pellets, an explosive increase in plasticity with increasing moisture content was seen, due to the contemporary increase in porosity. Plasticity is an important Green Pellet property in balling and should gain the status of a standard method in Green Pellet characterization. It is suggested that the control strategy for the balling circuits be based on plastic deformation and compression strength of Green Pellets instead of the rather inaccurate drop number. The results also point out the importance of knowing whether the balling process should be controlled by adjusting the moisture content (plasticity) or by adjusting the bentonite dosage (viscosity). These two operations are not interchangeable—even if they would compensate in growth rate, the Green Pellet properties would differ. A new Green Pellet growth mechanism is suggested, based on the measured over-saturation. Firstly, Green Pellet plasticity needs to exceed a minimum level to enable growth. This limiting plasticity defines the material-specific moisture content needed in balling. Secondly, it is suggested that the growth rate be controlled by the viscosity of the superficial water layer rather than by the mobility of the pore water.
Pooyan Rahimi - One of the best experts on this subject based on the ideXlab platform.
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an industrial image processing based approach for estimation of iron ore Green Pellet size distribution
Powder Technology, 2016Co-Authors: Mahdi Heydari, Rassoul Amirfattahi, Behzad Nazari, Pooyan RahimiAbstract:Abstract Green Pellets are spherical objects mainly made from crushed iron and water in rotating Pelletizing disk. Pellets play an important role in the process of direct reduction steel manufacturing. For high quality steel production, Pellets should be of an appropriate size. Oversized Pellets cannot be properly cooked in furnace and undersized Pellets may pass through metal grid of the furnace, which affects the performance of the process. In most of the steel manufacturing companies, operators use sequential sampling and traditional methods to measure size of Pellets, however, limited number of tested Pellets, low speed of the quality control and human errors are the most common drawbacks of this method. A solution to these shortcomings is continuous monitoring and accurate measurement through a fully-automatic approach. In this paper, a method using image processing technique is proposed and verified for estimating size distribution of iron-ore Green Pellets. For segmentation of single and multiple Pellets in images captured from live video, we have utilized morphological methods, watershed algorithm, and linear searching. Then, a Support Vector Machine (SVM) is employed for classification of segmented Pellets. The proposed method has already been implemented in Mobarakeh Steel Complex, where the method was tested on about 1000 sample Pellets. Results show that the accuracy of method is 95.1% in detection of single Pellet elements.
A J Apelqvist - One of the best experts on this subject based on the ideXlab platform.
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binding mechanisms in wet iron ore Green Pellets with a bentonite binder
Powder Technology, 2006Co-Authors: S P E Forsmo, Bo Bjorkman, Perolof Samskog, A J ApelqvistAbstract:Abstract Fundamental research during the past decade has been focussed on understanding the role of viscous forces on agglomerate deformability and strength. Much of this work has been done on glass spheres using Newtonian liquids as a binder. In this work, we show the variations in plasticity and strength of magnetite iron ore Green Pellets with varying liquid saturations and binder dosages (viscosities). For this purpose, a new measuring instrument was built to analyze the Green Pellet wet compression strength, plastic deformation and breakage pattern. Industrial iron ore Green Pellets are over-saturated and a supporting “network” of viscous liquid is formed on the Green Pellet surface. At least half, probably more, of the total binding force appeared to be due to the cohesive force of the network. The other half (or less) of the total compression strength can be explained by the capillary force. Due to irregularities on Green Pellet surfaces, both fully developed concave pore openings and saturated areas are expected to be found at the same time. Wet Green Pellets started showing plastic behaviour as they became over-saturated. In over-saturated Green Pellets, an explosive increase in plasticity with increasing moisture content was seen, due to the contemporary increase in porosity. Plasticity is an important Green Pellet property in balling and should gain the status of a standard method in Green Pellet characterization. It is suggested that the control strategy for the balling circuits be based on plastic deformation and compression strength of Green Pellets instead of the rather inaccurate drop number. The results also point out the importance of knowing whether the balling process should be controlled by adjusting the moisture content (plasticity) or by adjusting the bentonite dosage (viscosity). These two operations are not interchangeable—even if they would compensate in growth rate, the Green Pellet properties would differ. A new Green Pellet growth mechanism is suggested, based on the measured over-saturation. Firstly, Green Pellet plasticity needs to exceed a minimum level to enable growth. This limiting plasticity defines the material-specific moisture content needed in balling. Secondly, it is suggested that the growth rate be controlled by the viscosity of the superficial water layer rather than by the mobility of the pore water.
