The aim of this study is to enhance the value and utilization of red mud generated in the Bayer process by preparing composite cement mortars.The effects of two different types of Bayer red mud with varying physical a...The aim of this study is to enhance the value and utilization of red mud generated in the Bayer process by preparing composite cement mortars.The effects of two different types of Bayer red mud with varying physical and chemical characteristics on the fluidity,mechanical strength,mineral composition,and microstructure of the composite cement mortar were systematically evaluated.The results showed that the optimal addition of red mud A was 10 wt%,while it was 20 wt% for red mud B.The mechanical properties of the composite cement mortar met the standards for P·O42.5 cement.Furthermore,the composite mortar with the addition of red mud B showed higher flexural and compressive strengths compared to the composite mortar with red mud A.This improvement is attributed to the smaller particle size of red mud B,which filled the micro-pores and increased the compactness of the cement stone,as well as its higher content of Na_(2)O,K_(2)O,and other free alkalis,which resulted in more obvious alkali activation,accelerating the hydration of the active minerals in the slurry.展开更多
The absorbent composing of Bayer red mud and water was prepared and applied to removing SO2 from flue gas.Effects of the ratio of liquid to solid(L/S),the absorption temperature,the inlet SO2 concentration,the O2 conc...The absorbent composing of Bayer red mud and water was prepared and applied to removing SO2 from flue gas.Effects of the ratio of liquid to solid(L/S),the absorption temperature,the inlet SO2 concentration,the O2 concentration,SO4^2-and other different components of Bayer red mud on desulfurization were conducted.The mechanism of flue gas desulfurization was also established.The results indicated that L/S was the prominent factor,followed by the inlet SO2 concentration and the temperature was the least among them.The optimum condition was as follows:L/S,the temperature and the SO2 concentration were 20:1,25℃and 1000 mg/m^3,respectively,under the gas flow of 1.5 L/min.The desulfurization efficiency was not significantly influenced when O2 concentration was above 7%.The accumulation of SO4^2-inhibited the desulfurization efficiency.The alkali absorption and metal ions liquid catalytic oxidation were involved in the process,which accounted for 98.61%.展开更多
Bayer red mud(BRM)is a kind of industrial solid waste characterized by huge volume and high alkalinity.Its disposal generates serious environmental pollution and occupies a large number of farmland.The utilization and...Bayer red mud(BRM)is a kind of industrial solid waste characterized by huge volume and high alkalinity.Its disposal generates serious environmental pollution and occupies a large number of farmland.The utilization and recycling of BRM is currently a crucial issue and needs to be addressed as soon as possible.The chemical composition of BRM is similar to cement clinker.In this study,the feasibility of preparing Belite-ferroaluminate clinker(BFAC)with different BRM was explored.The physical properties,mechanics performance,radioactivity levels and trace harmful metals leaching were measured.XRD,BEI and EDS were used to characterize the mineral formation,and SEM is used to reveal the solidified mechanism of trace harmful metal.The results show that the preparation of BFAC using a certain amount of BRM was feasible.The formed phases in clinkers mainly included C_(4)A_(3)Š,C_(2)S and C_(4)AF.The flexural strength and compressive strength of BFAC at 3 days increased whereas 28 and 90 days decreased with the increase of BRM due to the formation of higher C_(4)AF and lower C_(2)S.The formation of large amounts of Al_(2)O_(3)·3H_(2)O gel and Fe_(2)O_(3)·3H_(2)O gel in hydration products enhanced the adsorption capability to heavy metals and other ions.The trace harmful metal concentration in the leaching solution was much less than the upper limits.The radioactivity level of leaching solution was close to natural radioactive background.BRM is safe as raw material of BFAC.展开更多
The reductive Bayer digestion by using iron powder as reductant is proposed to convert hematite to magnetite and further to dissociate iron minerals from sodium aluminosilicate hydrate(desilication product,DSP)based o...The reductive Bayer digestion by using iron powder as reductant is proposed to convert hematite to magnetite and further to dissociate iron minerals from sodium aluminosilicate hydrate(desilication product,DSP)based on the differences of their surface properties.The results show that the differences of surface properties between magnetite and DSP in zeta potential,wettability and solvation trend facilitate magnetite to agglomerate,grow up and thus to dissociate from DSP.The increments of reductant amount and alkali concentration favor the transformation of hematite in digestion with the relative alumina recovery of98.91%.Processing the resultant red mud can obtain qualified iron concentrate with iron grade of approximate60%and recovery of about86%through magnetic separation,resulting in reduction of red mud emission higher than70%.The results are potential to develop a novel technology for processing high iron diasporic bauxite efficiently and provide references for comprehensive utilization of high iron red mud.展开更多
基金the Guangxi Science and Technology Program(Guike AD21220052,AD22035126 and AB22035064)National Natural Science Foundation of China(52062009)Guangxi Key Laboratory of New Energy and Building Energy Saving(Guikeneng 22-J-21-19).
文摘The aim of this study is to enhance the value and utilization of red mud generated in the Bayer process by preparing composite cement mortars.The effects of two different types of Bayer red mud with varying physical and chemical characteristics on the fluidity,mechanical strength,mineral composition,and microstructure of the composite cement mortar were systematically evaluated.The results showed that the optimal addition of red mud A was 10 wt%,while it was 20 wt% for red mud B.The mechanical properties of the composite cement mortar met the standards for P·O42.5 cement.Furthermore,the composite mortar with the addition of red mud B showed higher flexural and compressive strengths compared to the composite mortar with red mud A.This improvement is attributed to the smaller particle size of red mud B,which filled the micro-pores and increased the compactness of the cement stone,as well as its higher content of Na_(2)O,K_(2)O,and other free alkalis,which resulted in more obvious alkali activation,accelerating the hydration of the active minerals in the slurry.
基金Project(2017YFC0210500)supported by the National Key Technology R&D Program of ChinaProject(2017ACA092)supported by the Major Projects of Technical Innovation in Hubei Province,China
文摘The absorbent composing of Bayer red mud and water was prepared and applied to removing SO2 from flue gas.Effects of the ratio of liquid to solid(L/S),the absorption temperature,the inlet SO2 concentration,the O2 concentration,SO4^2-and other different components of Bayer red mud on desulfurization were conducted.The mechanism of flue gas desulfurization was also established.The results indicated that L/S was the prominent factor,followed by the inlet SO2 concentration and the temperature was the least among them.The optimum condition was as follows:L/S,the temperature and the SO2 concentration were 20:1,25℃and 1000 mg/m^3,respectively,under the gas flow of 1.5 L/min.The desulfurization efficiency was not significantly influenced when O2 concentration was above 7%.The accumulation of SO4^2-inhibited the desulfurization efficiency.The alkali absorption and metal ions liquid catalytic oxidation were involved in the process,which accounted for 98.61%.
基金This study was financially supported by the Guangxi Science and Technology Plan project of China(Grant No.2018GXNSFBA138053,No.2018AA23004)Guangxi Young and Middleaged Teachers Basic Ability Promotion Project(Grant No.2017KY0250)+1 种基金Key Laboratory of New Processing Technology for Nonferrous Metal&Materials,Ministry of Education(Grant No.19AA-13)Guangxi Key Laboratory of New Energy and Building Energy Saving(Grant No.19-J-21-24).
文摘Bayer red mud(BRM)is a kind of industrial solid waste characterized by huge volume and high alkalinity.Its disposal generates serious environmental pollution and occupies a large number of farmland.The utilization and recycling of BRM is currently a crucial issue and needs to be addressed as soon as possible.The chemical composition of BRM is similar to cement clinker.In this study,the feasibility of preparing Belite-ferroaluminate clinker(BFAC)with different BRM was explored.The physical properties,mechanics performance,radioactivity levels and trace harmful metals leaching were measured.XRD,BEI and EDS were used to characterize the mineral formation,and SEM is used to reveal the solidified mechanism of trace harmful metal.The results show that the preparation of BFAC using a certain amount of BRM was feasible.The formed phases in clinkers mainly included C_(4)A_(3)Š,C_(2)S and C_(4)AF.The flexural strength and compressive strength of BFAC at 3 days increased whereas 28 and 90 days decreased with the increase of BRM due to the formation of higher C_(4)AF and lower C_(2)S.The formation of large amounts of Al_(2)O_(3)·3H_(2)O gel and Fe_(2)O_(3)·3H_(2)O gel in hydration products enhanced the adsorption capability to heavy metals and other ions.The trace harmful metal concentration in the leaching solution was much less than the upper limits.The radioactivity level of leaching solution was close to natural radioactive background.BRM is safe as raw material of BFAC.
基金Project(51374239)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by Environmental Protection’s Special Scientific Research for Chinese Public Welfare IndustryProject(2015CX001)supported by the Innovation-driven Plan in Central South University,China
文摘The reductive Bayer digestion by using iron powder as reductant is proposed to convert hematite to magnetite and further to dissociate iron minerals from sodium aluminosilicate hydrate(desilication product,DSP)based on the differences of their surface properties.The results show that the differences of surface properties between magnetite and DSP in zeta potential,wettability and solvation trend facilitate magnetite to agglomerate,grow up and thus to dissociate from DSP.The increments of reductant amount and alkali concentration favor the transformation of hematite in digestion with the relative alumina recovery of98.91%.Processing the resultant red mud can obtain qualified iron concentrate with iron grade of approximate60%and recovery of about86%through magnetic separation,resulting in reduction of red mud emission higher than70%.The results are potential to develop a novel technology for processing high iron diasporic bauxite efficiently and provide references for comprehensive utilization of high iron red mud.
