The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The resu...The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The results show that sulfur phases in high sulfur-containing bauxites exist in the main form of sulfide sulfur （pyrite） or sulfate sulfur,and the main sulfur forms of bauxites from different regions are not the same.Through a combination of an X-ray diffraction analysis and a chemistry quantitative analysis,the sulfur phases of high sulfur-containing bauxite could be accurately investigated.Deciding the main sulfur form of high sulfur-containing bauxite could provide theoretical instruction for choosing methods for the removal of sulfur from bauxite,and an oxidizing-roasting process is an effective way to remove sulfide sulfur from high sulfur-containing bauxite,the content of S^2-in crude ore in the digestion liquor is above 1.7 g/L,but in the roasted ore digestion liquor,it is below 0.18 g/L.Using the sodium carbonate solution washing technology to wash bauxite can effectively remove sulfate sulfur,the content of the total sulfur in ore is lowered to below 0.2% and can meet the production requirements for the sulfur content.展开更多
To lower the cost of bauxite electrolysis desulfurization using NaOH solution as the supporting electrolyte, effects of electrolyte recycling on bauxite electrolysis desulfurization were investigated. The results in...To lower the cost of bauxite electrolysis desulfurization using NaOH solution as the supporting electrolyte, effects of electrolyte recycling on bauxite electrolysis desulfurization were investigated. The results indicate that electrode corrosion, cell voltage, the desulfurization rate and the pH value of the electrolyte have no obvious changes with the increase of cycle times. Additionally, there were some transitive valence S-containing ions in electrolyte after the electrolysis, such as SO3^2-,S2O3^2- . However, most of the sulfur in bauxite was eventually oxidized into SO4^2- into the electrolyte, and these S-containing ions did not affect the recycling utilization for electrolyte.展开更多
Bauxite is the main raw material of the alumina industry.However,high-sulfur bauxite constitutes a relatively large proportion of bauxite resource in China.Excessive sulfur impurities in bauxite have significant impac...Bauxite is the main raw material of the alumina industry.However,high-sulfur bauxite constitutes a relatively large proportion of bauxite resource in China.Excessive sulfur impurities in bauxite have significant impact on the Bayer process,such as corrosion of equipment and pipelines,increased consumption of alkali,and difficulties in sedimentation of red mud particles after digestion.As the mainstreams of bauxite desulfurization technologies,the bauxite pre-desulfurization(roasting,electrochemistry,biology,flotation,etc)and Bayer process desulfurization(oxidation and precipitation)need to be fully understood for the further improvement of desulfurization performance.Here,an in-depth review on their mechanisms and advantages/disadvantages is presented.展开更多
To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication pro...To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication process in Na OH solution under atmospheric pressure. The desulfurization and desilication properties and mineralogical evolution were studied by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and FactSage methods. The results demonstrate that the suspension calcination method is efficient for sulfur removal: 84.21% of S was removed after calcination at 1000°C for 2 min. During the calcination process, diaspore and pyrite were transferred to α-Al2O3, magnetite, and hematite. The phase transformation of pyrite follows the order FeS2 → Fe3O4 → Fe2O3, and the iron oxides and silica were converted into iron silicate. In the alkali-soluble desilication process, the optimum condition was an alkali solution concentration of 110 g/L, a reaction time of 20 min, and a reaction temperature of 95°C. The corresponding desilication ratio and alumina loss ratio were 44.9% and 2.4%, respectively, and the alumina-to-silica mass ratio of the concentrate was 7.9. The Al2O3·2SiO2, SiO2, and Al2O3 formed during the calcination process could react with Na OH solution, and their activity decreased in the order of Al2O3·2 SiO2, SiO2, and Al2O3.展开更多
Pyrite inside bauxite could be oxidized into soluble S-containing ions by electrolysis, and thus achieving bauxite desulfurization by using filtration. However, S-containing ions in electrolyte had some corrosion effe...Pyrite inside bauxite could be oxidized into soluble S-containing ions by electrolysis, and thus achieving bauxite desulfurization by using filtration. However, S-containing ions in electrolyte had some corrosion effects on electrode, especially for anode. In this work, six kinds of traditional materials were selected as anode, and their corrosion behaviors were examined by using electrochemistry characterization. Tafel and CV curves from simulating electrolyte suggested that their corrosion potentials were in the following order: Ni﹥C﹥SS﹥Fe﹥Cu﹥Pb–Ag. As expected, the desulfurization ratio and cell voltage from bauxite electrolysis were in the following order respectively: Cu﹥Ni﹥Fe﹥SS﹥C﹥Pb–Ag and Ni﹥Fe﹥SS﹥Cu﹥C﹥Pb–Ag. Finally, Ni was proposed a kind of excellent electrode material for bauxite desulfurization from electrolysis.展开更多
基金Project(20971041) supported by the National Natural Science Foundation of ChinaProject(09B032) supported by Scientific Research Fund of Hunan Provincial Education Department,China
文摘The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The results show that sulfur phases in high sulfur-containing bauxites exist in the main form of sulfide sulfur （pyrite） or sulfate sulfur,and the main sulfur forms of bauxites from different regions are not the same.Through a combination of an X-ray diffraction analysis and a chemistry quantitative analysis,the sulfur phases of high sulfur-containing bauxite could be accurately investigated.Deciding the main sulfur form of high sulfur-containing bauxite could provide theoretical instruction for choosing methods for the removal of sulfur from bauxite,and an oxidizing-roasting process is an effective way to remove sulfide sulfur from high sulfur-containing bauxite,the content of S^2-in crude ore in the digestion liquor is above 1.7 g/L,but in the roasted ore digestion liquor,it is below 0.18 g/L.Using the sodium carbonate solution washing technology to wash bauxite can effectively remove sulfate sulfur,the content of the total sulfur in ore is lowered to below 0.2% and can meet the production requirements for the sulfur content.
基金Projects(51004090,51474198)supported by the National Natural Science Foundation of ChinaProject(KF13-03)supported by State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingProject(2015036)supported by Youth Innovation Promotion Association,Chinese Academy of Sciences
文摘To lower the cost of bauxite electrolysis desulfurization using NaOH solution as the supporting electrolyte, effects of electrolyte recycling on bauxite electrolysis desulfurization were investigated. The results indicate that electrode corrosion, cell voltage, the desulfurization rate and the pH value of the electrolyte have no obvious changes with the increase of cycle times. Additionally, there were some transitive valence S-containing ions in electrolyte after the electrolysis, such as SO3^2-,S2O3^2- . However, most of the sulfur in bauxite was eventually oxidized into SO4^2- into the electrolyte, and these S-containing ions did not affect the recycling utilization for electrolyte.
基金supported by the Henan Polytechnic University Science Fund for Distinguished Young Scholars,China (No. J2021-1)Foundation for University Key Teacher by Henan Province,China (No. 2020GGJS051)+2 种基金Key Project of Science and Technology Research of Education Department of Henan Province,China (No. 20A440004)Foundation for University Key Teacher by Henan Polytechnic University,China (No. 2017XQG-12)Henan Key Laboratory of Coal Green Conversion,Henan Polytechnic University,China (No. CGCF202009)
文摘Bauxite is the main raw material of the alumina industry.However,high-sulfur bauxite constitutes a relatively large proportion of bauxite resource in China.Excessive sulfur impurities in bauxite have significant impact on the Bayer process,such as corrosion of equipment and pipelines,increased consumption of alkali,and difficulties in sedimentation of red mud particles after digestion.As the mainstreams of bauxite desulfurization technologies,the bauxite pre-desulfurization(roasting,electrochemistry,biology,flotation,etc)and Bayer process desulfurization(oxidation and precipitation)need to be fully understood for the further improvement of desulfurization performance.Here,an in-depth review on their mechanisms and advantages/disadvantages is presented.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.U1812402,51664005,and 51774102)Talents of Guizhou Science and Technology Cooperation Platform(Talent Team Giant[2015]4005,Platform Talent[2017]5788,[2017]5626,and KY(2015)334).
文摘To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication process in Na OH solution under atmospheric pressure. The desulfurization and desilication properties and mineralogical evolution were studied by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and FactSage methods. The results demonstrate that the suspension calcination method is efficient for sulfur removal: 84.21% of S was removed after calcination at 1000°C for 2 min. During the calcination process, diaspore and pyrite were transferred to α-Al2O3, magnetite, and hematite. The phase transformation of pyrite follows the order FeS2 → Fe3O4 → Fe2O3, and the iron oxides and silica were converted into iron silicate. In the alkali-soluble desilication process, the optimum condition was an alkali solution concentration of 110 g/L, a reaction time of 20 min, and a reaction temperature of 95°C. The corresponding desilication ratio and alumina loss ratio were 44.9% and 2.4%, respectively, and the alumina-to-silica mass ratio of the concentrate was 7.9. The Al2O3·2SiO2, SiO2, and Al2O3 formed during the calcination process could react with Na OH solution, and their activity decreased in the order of Al2O3·2 SiO2, SiO2, and Al2O3.
基金Supported by the Natural Science Foundation of China(51474198,51422405)
文摘Pyrite inside bauxite could be oxidized into soluble S-containing ions by electrolysis, and thus achieving bauxite desulfurization by using filtration. However, S-containing ions in electrolyte had some corrosion effects on electrode, especially for anode. In this work, six kinds of traditional materials were selected as anode, and their corrosion behaviors were examined by using electrochemistry characterization. Tafel and CV curves from simulating electrolyte suggested that their corrosion potentials were in the following order: Ni﹥C﹥SS﹥Fe﹥Cu﹥Pb–Ag. As expected, the desulfurization ratio and cell voltage from bauxite electrolysis were in the following order respectively: Cu﹥Ni﹥Fe﹥SS﹥C﹥Pb–Ag and Ni﹥Fe﹥SS﹥Cu﹥C﹥Pb–Ag. Finally, Ni was proposed a kind of excellent electrode material for bauxite desulfurization from electrolysis.
