Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigate...Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron（DRI） by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery（εFe） by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε（Fe） in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.展开更多
In the present work,cyclic voltammetry(CV),square wave voltammetry(SWV)and chronopotentiometry(CP)were used to investigate the electrochemical coreduction behaviors of La(Ⅲ)and Mg(Ⅱ)as well as La(Ⅲ),Mg(Ⅱ)and Mn(Ⅱ...In the present work,cyclic voltammetry(CV),square wave voltammetry(SWV)and chronopotentiometry(CP)were used to investigate the electrochemical coreduction behaviors of La(Ⅲ)and Mg(Ⅱ)as well as La(Ⅲ),Mg(Ⅱ)and Mn(Ⅱ)on Mo electrode in LiCl+KCl molten salts.CV and SWV results exhibit that the coreduction mechanism of La(Ⅲ)and Mg(Ⅱ)on Mo electrode is that La(Ⅲ)is reduced and Mg-La intermetallic compound is formed,leading to the deposition potential of La(Ⅲ)shifting to more positive one.The electrochemical signals pertaining to the formation of metallic La,Mg and Mn as well as Mg-La intermetallic compound are also observed by coreduction of La(Ⅲ),Mg(Ⅱ),and Mn(Ⅱ)in LiCl+KCl molten salt on the inert Mo electrode.However,the electrochemical signals associated with the formation of La-Mn and Mg-Mn alloys are not observed,which means that the depolarization effect of La(Ⅲ)and Mg(Ⅱ)does not occur on pre-deposited Mn electrode.The Mg-La-Mn alloys were formed by co-deposition of La(Ⅲ),Mg(Ⅱ),and Mn(Ⅱ)on Mo electrode at various concentration ratios of La(Ⅲ)and Mg(Ⅱ).The results of scanning electron microscopy equipped with energy dispersive spectroscopy and X-ray diffraction displays that the Mg-La-Mn alloys are comprised of La-Mg compound Mg_(17)La_(2),Mg and Mn phases.The concentration ratio of La(Ⅲ)and Mn(Ⅱ)has few effects on the alloy composition.展开更多
基金Funded by National Natural Science Foundation of China(No.51134002)
文摘Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron（DRI） by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery（εFe） by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε（Fe） in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.
基金Project supported by the National Natural Science Foundation of China(21790373,21876034,11875116,11675044,11575047)。
文摘In the present work,cyclic voltammetry(CV),square wave voltammetry(SWV)and chronopotentiometry(CP)were used to investigate the electrochemical coreduction behaviors of La(Ⅲ)and Mg(Ⅱ)as well as La(Ⅲ),Mg(Ⅱ)and Mn(Ⅱ)on Mo electrode in LiCl+KCl molten salts.CV and SWV results exhibit that the coreduction mechanism of La(Ⅲ)and Mg(Ⅱ)on Mo electrode is that La(Ⅲ)is reduced and Mg-La intermetallic compound is formed,leading to the deposition potential of La(Ⅲ)shifting to more positive one.The electrochemical signals pertaining to the formation of metallic La,Mg and Mn as well as Mg-La intermetallic compound are also observed by coreduction of La(Ⅲ),Mg(Ⅱ),and Mn(Ⅱ)in LiCl+KCl molten salt on the inert Mo electrode.However,the electrochemical signals associated with the formation of La-Mn and Mg-Mn alloys are not observed,which means that the depolarization effect of La(Ⅲ)and Mg(Ⅱ)does not occur on pre-deposited Mn electrode.The Mg-La-Mn alloys were formed by co-deposition of La(Ⅲ),Mg(Ⅱ),and Mn(Ⅱ)on Mo electrode at various concentration ratios of La(Ⅲ)and Mg(Ⅱ).The results of scanning electron microscopy equipped with energy dispersive spectroscopy and X-ray diffraction displays that the Mg-La-Mn alloys are comprised of La-Mg compound Mg_(17)La_(2),Mg and Mn phases.The concentration ratio of La(Ⅲ)and Mn(Ⅱ)has few effects on the alloy composition.
