The transformation behavior of ferrous sulfate was examined during hematite precipitation for iron removal in hydrometallurgical zinc.Specifically,the effects of the method used for oxygen supply(pre-crystallization o...The transformation behavior of ferrous sulfate was examined during hematite precipitation for iron removal in hydrometallurgical zinc.Specifically,the effects of the method used for oxygen supply(pre-crystallization or pre-oxidation of ferrous sulfate)and temperature(170–190℃)on the redissolution and oxidation–hydrolysis of ferrous sulfate were studied.The precipitation characteristics and phase characterization of the hematite product were investigated.The results showed that the solubility of ferrous sulfate was considerably lower at elevated temperatures.The dissolution behavior of ferrous sulfate crystals was influenced by both the concentrations of free acid and zinc sulfate and the oxydrolysis of ferrous ions.Rapid oxydrolysis of ferrous ions may serve as the dissolution driving force.Hematite precipitation proceeded via the following sequential steps:crystallization,redissolution,oxidation,and precipitation of ferrous sulfate.The dissolution of ferrous sulfate was slow,which helped to maintain a low supersaturation environment,thereby affording the production of high-grade hematite.展开更多
The synthesis of Nd3＋,Y3＋：CaF2 nanopowder was conducted by azeotropic distillation method,which effectively dehydrated hydrous CaF2 and prevented forming hard agglomerates.X-ray diffraction（XRD）,scanning electron...The synthesis of Nd3＋,Y3＋：CaF2 nanopowder was conducted by azeotropic distillation method,which effectively dehydrated hydrous CaF2 and prevented forming hard agglomerates.X-ray diffraction（XRD）,scanning electron microscopy（SEM）,scanning calorimetries-thermalgravimetry（DSC-TG）,Fourier transform infrared spectroscopy（FT-IR） and absorption spectroscopy were performed to characterize the powder properties.The experimental results showed that products obtained by azeotropic distillation were single phased,rather monodispersed,successfully prevented the hard agglomerate formation and effectively removed the residual water inside the as-prepared precipitate than that of the direct drying.The absorption spectra showed a wider and stronger absorption bands around 792 nm,which should be profitable for LD pumping.展开更多
基金Projects(51804146,51964029,51664030,51564030)supported by the National Natural Science Foundation of ChinaProject(2018YFC1900402)supported by the National Key Research and Development Program of ChinaProject supported by the Analysis and Testing Center of Kunming University of Science and Technology,China
文摘The transformation behavior of ferrous sulfate was examined during hematite precipitation for iron removal in hydrometallurgical zinc.Specifically,the effects of the method used for oxygen supply(pre-crystallization or pre-oxidation of ferrous sulfate)and temperature(170–190℃)on the redissolution and oxidation–hydrolysis of ferrous sulfate were studied.The precipitation characteristics and phase characterization of the hematite product were investigated.The results showed that the solubility of ferrous sulfate was considerably lower at elevated temperatures.The dissolution behavior of ferrous sulfate crystals was influenced by both the concentrations of free acid and zinc sulfate and the oxydrolysis of ferrous ions.Rapid oxydrolysis of ferrous ions may serve as the dissolution driving force.Hematite precipitation proceeded via the following sequential steps:crystallization,redissolution,oxidation,and precipitation of ferrous sulfate.The dissolution of ferrous sulfate was slow,which helped to maintain a low supersaturation environment,thereby affording the production of high-grade hematite.
基金Funded by the National Natural Science Foundation of China(No.51072144)the State Key Program of National Science Foundation of China(No.51432007)the Project for Science and Technology Plan of Wuhan City(No.201210231092)
文摘The synthesis of Nd3＋,Y3＋：CaF2 nanopowder was conducted by azeotropic distillation method,which effectively dehydrated hydrous CaF2 and prevented forming hard agglomerates.X-ray diffraction（XRD）,scanning electron microscopy（SEM）,scanning calorimetries-thermalgravimetry（DSC-TG）,Fourier transform infrared spectroscopy（FT-IR） and absorption spectroscopy were performed to characterize the powder properties.The experimental results showed that products obtained by azeotropic distillation were single phased,rather monodispersed,successfully prevented the hard agglomerate formation and effectively removed the residual water inside the as-prepared precipitate than that of the direct drying.The absorption spectra showed a wider and stronger absorption bands around 792 nm,which should be profitable for LD pumping.
