The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt%but distinctly different mineralogical and liberation characteristics were studied.Their performances in terms...The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt%but distinctly different mineralogical and liberation characteristics were studied.Their performances in terms of the iron grade and recovery as obtained from statistically designed microwave(MW)roasting followed by low-intensity magnetic separation(LIMS)experiments were compared.At respective optimum conditions,the titano-magnetite ore(O1)could yield an iron concentrate of 62.57%Fe grade and 60.01%Fe recovery,while the goethitic ore(O2)could be upgraded to a concentrate of 64.4%Fe grade and 33.3%Fe recovery.Compared with the goethitic ore,the titanomagnetite ore responded better to MW heating.The characterization studies of the feed and roasted products obtained at different power and time conditions using X-ray diffraction,optical microscopy,vibrating-sample magnetometry,and electron-probe microanalysis explain the sequential reduction in the iron oxide phases.Finally,taking advantage of the MW absorbing character of the titano-magnetite ore,a blend of the same with the goethite-rich ore at a weight ratio of 60:40(O2:O1)was subjected to MW roasting that resulted in a concentrate of 61.57%Fe grade with a Fe recovery of 64.47%.展开更多
The removal of iron from an Indian diaspore sample was studied using magnetic separation and leaching techniques aided by an in-depth mineralogical characterization study involving quantitative mineralogical evaluatio...The removal of iron from an Indian diaspore sample was studied using magnetic separation and leaching techniques aided by an in-depth mineralogical characterization study involving quantitative mineralogical evaluation by scanning electron microscope（QEMSCAN）, electron probe micro-analyzer（EPMA） and X-ray diffraction（XRD）. The characterization studies indicate that extremely fine-sized hematite grains are associated with several other mineral phases in a complex manner with around 60% of the hematite not liberated even below the size of 38 μm limiting the scope of physical separation processes to remove the iron. Wet high intensity magnetic separation（WHIMS） studies reveal that only 49% of iron can be removed. Further, leaching studies using oxalic acid suggest that around 76% of the iron can be removed under conditions such as a solid to liquid ratio of 0.05：1, a temperature of 90 ℃ a time period of 120 min and an acid concentration of 1 mol/L. The dissolution of iron in oxalic acid is found to be controlled by chemical reaction and the activation energy is calculated as 35.15 k J/mol.展开更多
With gradually diminishing Fe grade in tandem with the ever-increasing demand for high-grade iron ores,iron ore industries are now focusing on the beneficiation of low-grade iron ore fines,mainly considered waste.Besi...With gradually diminishing Fe grade in tandem with the ever-increasing demand for high-grade iron ores,iron ore industries are now focusing on the beneficiation of low-grade iron ore fines,mainly considered waste.Besides,the scarcity of water at many of the mines’sites and the new water conservation policies of the governments have necessitated research on suitable dry beneficiation routes.In this context,an effort has been made to evaluate the efficacy of a dry classification unit,such as the VSK separator,in upgrading the iron values of two low-grade Indian iron ore fines,named Sample 1 and Sample 2.The mineralogical studies,involving scanning electron microscopy and X-ray diffraction,suggest that Sample 1 is a low-grade blue dust sample(51.2wt%Fe)containing hematite and quartz as the major minerals,while Sample 2(53.3wt%Fe)shows the presence of goethite in addition to hematite and quartz.The experiments,carried out using Box-Benkhen statistical design,indicate that blower speed,followed by feed rate,is the most influencing operating parameter in obtaining a good product in the VSK separator.At optimum levels of the operating factors,a fines product with~55wt%Fe at a yield of~40%can be obtained from Sample 1,while Sample 2 can be upgraded to~56wt%Fe at a yield of~85%.The results suggest that the VSK separator can be employed as an efficient intermediate unit operation in a processing circuit to upgrade the iron contents of iron ore fines.展开更多
基金The authors are thankful to the Director,CSIR-IMMT,Bhubaneswar for his permission to publish this paper and the Ministry of Steel,Government of India,for their financial support(F.No.11(12)/GBS/2014-TW).
文摘The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt%but distinctly different mineralogical and liberation characteristics were studied.Their performances in terms of the iron grade and recovery as obtained from statistically designed microwave(MW)roasting followed by low-intensity magnetic separation(LIMS)experiments were compared.At respective optimum conditions,the titano-magnetite ore(O1)could yield an iron concentrate of 62.57%Fe grade and 60.01%Fe recovery,while the goethitic ore(O2)could be upgraded to a concentrate of 64.4%Fe grade and 33.3%Fe recovery.Compared with the goethitic ore,the titanomagnetite ore responded better to MW heating.The characterization studies of the feed and roasted products obtained at different power and time conditions using X-ray diffraction,optical microscopy,vibrating-sample magnetometry,and electron-probe microanalysis explain the sequential reduction in the iron oxide phases.Finally,taking advantage of the MW absorbing character of the titano-magnetite ore,a blend of the same with the goethite-rich ore at a weight ratio of 60:40(O2:O1)was subjected to MW roasting that resulted in a concentrate of 61.57%Fe grade with a Fe recovery of 64.47%.
文摘The removal of iron from an Indian diaspore sample was studied using magnetic separation and leaching techniques aided by an in-depth mineralogical characterization study involving quantitative mineralogical evaluation by scanning electron microscope（QEMSCAN）, electron probe micro-analyzer（EPMA） and X-ray diffraction（XRD）. The characterization studies indicate that extremely fine-sized hematite grains are associated with several other mineral phases in a complex manner with around 60% of the hematite not liberated even below the size of 38 μm limiting the scope of physical separation processes to remove the iron. Wet high intensity magnetic separation（WHIMS） studies reveal that only 49% of iron can be removed. Further, leaching studies using oxalic acid suggest that around 76% of the iron can be removed under conditions such as a solid to liquid ratio of 0.05：1, a temperature of 90 ℃ a time period of 120 min and an acid concentration of 1 mol/L. The dissolution of iron in oxalic acid is found to be controlled by chemical reaction and the activation energy is calculated as 35.15 k J/mol.
基金the National Mineral Development Corporation Limited,Hyderabad for sponsoring the research。
文摘With gradually diminishing Fe grade in tandem with the ever-increasing demand for high-grade iron ores,iron ore industries are now focusing on the beneficiation of low-grade iron ore fines,mainly considered waste.Besides,the scarcity of water at many of the mines’sites and the new water conservation policies of the governments have necessitated research on suitable dry beneficiation routes.In this context,an effort has been made to evaluate the efficacy of a dry classification unit,such as the VSK separator,in upgrading the iron values of two low-grade Indian iron ore fines,named Sample 1 and Sample 2.The mineralogical studies,involving scanning electron microscopy and X-ray diffraction,suggest that Sample 1 is a low-grade blue dust sample(51.2wt%Fe)containing hematite and quartz as the major minerals,while Sample 2(53.3wt%Fe)shows the presence of goethite in addition to hematite and quartz.The experiments,carried out using Box-Benkhen statistical design,indicate that blower speed,followed by feed rate,is the most influencing operating parameter in obtaining a good product in the VSK separator.At optimum levels of the operating factors,a fines product with~55wt%Fe at a yield of~40%can be obtained from Sample 1,while Sample 2 can be upgraded to~56wt%Fe at a yield of~85%.The results suggest that the VSK separator can be employed as an efficient intermediate unit operation in a processing circuit to upgrade the iron contents of iron ore fines.
