The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied.The results indicate that the fraction of retained austenite and...The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied.The results indicate that the fraction of retained austenite and the manganese distribution in as-cast alloys are controlled by manganese content.The manganese distribution in as-cast alloys is not homogeneous.The manganese content in carbide is higher than that in matrix.Whether the secondary hardening occurs or not and the peak hardness of secondary hardening is controlled by manganese content in retained austenite in as-cast structure.Higher manganese content can cause more retained austenite.The secondary hardening occurs in sub-critical treating process if the fraction of retained austenite is high.展开更多
The characteristic of groundwater belongs to low iron but high manganese in Shenyang Hunnan New Developed Area.The first stage engineering of The WTP of Shenyang Hunnan industry Area were designed according the techno...The characteristic of groundwater belongs to low iron but high manganese in Shenyang Hunnan New Developed Area.The first stage engineering of The WTP of Shenyang Hunnan industry Area were designed according the technology of aerated-contact oxidation,and the water quality couldn’t reach to the standard after the WTP putted into production,1996.展开更多
The kinetics of pressure leaching high iron sphalerite concentrate was studied.The effects of agitation rate,temperature, oxygen partial pressure,initial acid concentration,particle size,iron content in the concentrat...The kinetics of pressure leaching high iron sphalerite concentrate was studied.The effects of agitation rate,temperature, oxygen partial pressure,initial acid concentration,particle size,iron content in the concentrate and concentration of Fe2 +added into the solution on the leaching rate of zinc were examined.The experiment results indicate that if the agitation rate is greater than 600 r/min,its influence on Zn leaching rate is not substantial.A suitable rise in temperature can facilitate the leaching reaction,and the temperature should be controlled at 140-150℃.The increase trend of Zn leaching rate becomes slow when pressure is greater than 1.2 MPa,so the pressure is controlled at 1.2-1.4 MPa.Under the conditions of this study,Zn leaching rate decreases with a rise in the initial sulfuric acid concentration;and Zn leaching rate increases with a rise of iron content in the concentrate and Fe 2+ concentration in the solution.Moreover,the experiment demonstrates that the leaching process follows the surface chemical reaction control kinetic law of“shrinking of unreacted core”.The activation energy for pressure leaching high iron sphalerite concentrate is calculated,and a mathematical model for this pressure leaching is obtained.The model is promising to guide the practical operation of pressure leaching high iron sphalerite concentrate.展开更多
The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied. The results indicate that the fraction of retained austenite an...The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied. The results indicate that the fraction of retained austenite and the manganese distribution in as-cast alloys are controlled by manganese content. The manganese distribution in as-cast alloys is not homogeneous. The manganese content in carbide is higher than that in matrix. Whether the secondary hardening occurs or not and the peak hardness of secondary hardening is controlled by manganese content in retained austenite in as-cast structure. Higher manganese content can cause more retained austenite. The secondary hardening occurs in sub-critical treating process if the fraction of retained austenite is high.展开更多
Ultrafine iron powder is widely used due to its excellent performance. Hydrogen reduction of fine-grained high-purity iron concentrate to prepare ultrafine iron powder has the advantages of low energy consumption, pol...Ultrafine iron powder is widely used due to its excellent performance. Hydrogen reduction of fine-grained high-purity iron concentrate to prepare ultrafine iron powder has the advantages of low energy consumption, pollution-free, and low cost. The hydrogen reduction of high-purity iron concentrates, characterized by the maximum particle size of 6.43 μm when the cumulative distribution is 50% and the maximum particle size of 11.85 μm when the cumulative distribution is 90% while the total iron content of 72.10%, was performed. The hydrogen reduction could be completed at 425 ℃, and the purity of ultrafine iron powders was more than 99 wt.% in the range of 425–650 ℃. Subsequently, the effect of reduction temperature on various properties of ultrafine iron powder was investigated, including particle morphology, particle size, specific surface area, lattice parameters, bulk density, and reaction activity. It was found that the reaction activity of the iron powders prepared by hydrogen reduction was much higher than that of the products of carbonyl and liquid phase synthesis. Below 500 ℃, the reduced iron powders were nearly unbound, with a small particle size and a low bulk density. The particles had a porous surface, with a specific surface area as high as 11.31 m^(2) g^(−1). The crystallization of reduced iron powders was imperfect at this time, the amorphization degree was prominent, and the interior contained a high mechanical storage energy, which had shown high reaction reactivity. It was suitable for catalysts, metal fuels, and other functionalized applications.展开更多
High pressure roll grinding（HPRG）and ball milling were compared to investigate the influence of mechanical activation on the acid leaching dephosphorization of a high-phosphorus iron ore concentrate,which was manufa...High pressure roll grinding（HPRG）and ball milling were compared to investigate the influence of mechanical activation on the acid leaching dephosphorization of a high-phosphorus iron ore concentrate,which was manufactured through magnetizing roasting-magnetic separation of high-phosphorus oolitic iron ores.The results indicated that when high-phosphorus iron ore concentrates containing 54.92 mass% iron and 0.76 mass% phosphorus were directly processed through acid leaching,iron ore concentrates containing 55.74mass%iron and 0.33mass%phosphorus with an iron recovery of 84.64%and dephosphorization of 63.79% were obtained.When high-phosphorus iron ore concentrates activated by ball milling were processed by acid leaching,iron ore concentrates containing56.03mass%iron and 0.21mass% phosphorus with an iron recovery of 85.65% and dephosphorization of 77.49%were obtained.Meanwhile,when high-phosphorus iron ore concentrates activated by HPRG were processed by acid leaching,iron ore concentrates containing 58.02mass%iron and 0.10mass% phosphorus were obtained,with the iron recovery reaching 88.42% and the dephosphorization rate reaching 88.99%.Mechanistic studies demonstrated that ball milling can reduce the particle size,demonstrating aprominent reunion phenomenon.In contrast,HPRG pretreatment contributes to the formation of more cracks within the particles and selective dissociation of iron and P bearing minerals,which can provide the favorable kinetic conditions to accelerate the solid-liquid reaction rate.As such,the crystal structure is destroyed and the surface energy of mineral particles is strengthened by mechanical activation,further strengthening the dephosphorization.展开更多
文摘The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied.The results indicate that the fraction of retained austenite and the manganese distribution in as-cast alloys are controlled by manganese content.The manganese distribution in as-cast alloys is not homogeneous.The manganese content in carbide is higher than that in matrix.Whether the secondary hardening occurs or not and the peak hardness of secondary hardening is controlled by manganese content in retained austenite in as-cast structure.Higher manganese content can cause more retained austenite.The secondary hardening occurs in sub-critical treating process if the fraction of retained austenite is high.
文摘The characteristic of groundwater belongs to low iron but high manganese in Shenyang Hunnan New Developed Area.The first stage engineering of The WTP of Shenyang Hunnan industry Area were designed according the technology of aerated-contact oxidation,and the water quality couldn’t reach to the standard after the WTP putted into production,1996.
基金Project(2002GG01)supported by Yunnan Metallurgical General Company,China
文摘The kinetics of pressure leaching high iron sphalerite concentrate was studied.The effects of agitation rate,temperature, oxygen partial pressure,initial acid concentration,particle size,iron content in the concentrate and concentration of Fe2 +added into the solution on the leaching rate of zinc were examined.The experiment results indicate that if the agitation rate is greater than 600 r/min,its influence on Zn leaching rate is not substantial.A suitable rise in temperature can facilitate the leaching reaction,and the temperature should be controlled at 140-150℃.The increase trend of Zn leaching rate becomes slow when pressure is greater than 1.2 MPa,so the pressure is controlled at 1.2-1.4 MPa.Under the conditions of this study,Zn leaching rate decreases with a rise in the initial sulfuric acid concentration;and Zn leaching rate increases with a rise of iron content in the concentrate and Fe 2+ concentration in the solution.Moreover,the experiment demonstrates that the leaching process follows the surface chemical reaction control kinetic law of“shrinking of unreacted core”.The activation energy for pressure leaching high iron sphalerite concentrate is calculated,and a mathematical model for this pressure leaching is obtained.The model is promising to guide the practical operation of pressure leaching high iron sphalerite concentrate.
文摘The effect of manganese on the as-cast structure and hardening behavior of high chromium white cast iron subjected to sub-critical treatment was studied. The results indicate that the fraction of retained austenite and the manganese distribution in as-cast alloys are controlled by manganese content. The manganese distribution in as-cast alloys is not homogeneous. The manganese content in carbide is higher than that in matrix. Whether the secondary hardening occurs or not and the peak hardness of secondary hardening is controlled by manganese content in retained austenite in as-cast structure. Higher manganese content can cause more retained austenite. The secondary hardening occurs in sub-critical treating process if the fraction of retained austenite is high.
基金support of the National Natural Science Foundation of China(52174330).
文摘Ultrafine iron powder is widely used due to its excellent performance. Hydrogen reduction of fine-grained high-purity iron concentrate to prepare ultrafine iron powder has the advantages of low energy consumption, pollution-free, and low cost. The hydrogen reduction of high-purity iron concentrates, characterized by the maximum particle size of 6.43 μm when the cumulative distribution is 50% and the maximum particle size of 11.85 μm when the cumulative distribution is 90% while the total iron content of 72.10%, was performed. The hydrogen reduction could be completed at 425 ℃, and the purity of ultrafine iron powders was more than 99 wt.% in the range of 425–650 ℃. Subsequently, the effect of reduction temperature on various properties of ultrafine iron powder was investigated, including particle morphology, particle size, specific surface area, lattice parameters, bulk density, and reaction activity. It was found that the reaction activity of the iron powders prepared by hydrogen reduction was much higher than that of the products of carbonyl and liquid phase synthesis. Below 500 ℃, the reduced iron powders were nearly unbound, with a small particle size and a low bulk density. The particles had a porous surface, with a specific surface area as high as 11.31 m^(2) g^(−1). The crystallization of reduced iron powders was imperfect at this time, the amorphization degree was prominent, and the interior contained a high mechanical storage energy, which had shown high reaction reactivity. It was suitable for catalysts, metal fuels, and other functionalized applications.
基金Item Sponsored by National Torch Program Project of China(2011GH561685)
文摘High pressure roll grinding（HPRG）and ball milling were compared to investigate the influence of mechanical activation on the acid leaching dephosphorization of a high-phosphorus iron ore concentrate,which was manufactured through magnetizing roasting-magnetic separation of high-phosphorus oolitic iron ores.The results indicated that when high-phosphorus iron ore concentrates containing 54.92 mass% iron and 0.76 mass% phosphorus were directly processed through acid leaching,iron ore concentrates containing 55.74mass%iron and 0.33mass%phosphorus with an iron recovery of 84.64%and dephosphorization of 63.79% were obtained.When high-phosphorus iron ore concentrates activated by ball milling were processed by acid leaching,iron ore concentrates containing56.03mass%iron and 0.21mass% phosphorus with an iron recovery of 85.65% and dephosphorization of 77.49%were obtained.Meanwhile,when high-phosphorus iron ore concentrates activated by HPRG were processed by acid leaching,iron ore concentrates containing 58.02mass%iron and 0.10mass% phosphorus were obtained,with the iron recovery reaching 88.42% and the dephosphorization rate reaching 88.99%.Mechanistic studies demonstrated that ball milling can reduce the particle size,demonstrating aprominent reunion phenomenon.In contrast,HPRG pretreatment contributes to the formation of more cracks within the particles and selective dissociation of iron and P bearing minerals,which can provide the favorable kinetic conditions to accelerate the solid-liquid reaction rate.As such,the crystal structure is destroyed and the surface energy of mineral particles is strengthened by mechanical activation,further strengthening the dephosphorization.
