A greenness evaluation index and system of microwave-assisted leaching method were established.The effects of the life cycle assessment variables,such as the resource consumption,environment impact,cost,time and quali...A greenness evaluation index and system of microwave-assisted leaching method were established.The effects of the life cycle assessment variables,such as the resource consumption,environment impact,cost,time and quality,were investigated,and the concept of green degree was applied in the production of synthetic rutile.An analytic hierarchy process was utilized to assess matrix of greenness evaluation.The Gauss-Seidel iterative matrix method was employed to solve the assessment matrix and obtain the weights and membership functions of all evaluation indexes.A fuzzy decision-making method was applied to build the greenness evaluation model,and then the scores of green degree in microwave-assisted leaching process was obtained.The greenness evaluation model was applied to the life cycle assessment of the microwave-assisted leaching process.The results show that the microwave-assisted leaching process has advantages over the conventional ones,with respect to energy-consumption,processing time and environmental protection.展开更多
Microwave absorbing properties of high titanium slag were investigated by using microwave cavity perturbation technique. High titanium slag containing more than 90% TiO2 was prepared by carbothermal reduction of ilmen...Microwave absorbing properties of high titanium slag were investigated by using microwave cavity perturbation technique. High titanium slag containing more than 90% TiO2 was prepared by carbothermal reduction of ilmenite. The temperature rise curve of high titanium slag in microwave heating process was obtained. Crystalline compounds of high titanium slag before and after microwave irradiation were obtained and characterized by X-ray diffractometry (XRD). Effects of particle size of high titanium slag and mixtures of high titanium slag with different mass fractions of V2O5 on microwave absorbing properties were investigated systematically. The results show that high titanium slag has good microwave absorption property; untreated high titanium slag mainly consists of crystalline compounds of anatase and iron titanium oxide, while the microwave-irradiation treated one is mainly composed of crystalline compounds of rutile and iron titanium oxide. Synthetic anatase is transformed completely into rutile at about 1 050 ℃ for 20 min under microwave irradiation. High frequency shift and low amplitude of voltage make high titanium slag an ideal microwave absorbent. 180 μm of particle size and 10% mass fraction of V2O5 are found to be the optimum conditions for microwave absorption.展开更多
This work investigates durability of cement-free mortars with a binder comprised of ground granulated blast furnace slag (GGBFS) activated by high-calcium fly ash (HCFA) and sodium carbonate (Na<sub>2</sub>...This work investigates durability of cement-free mortars with a binder comprised of ground granulated blast furnace slag (GGBFS) activated by high-calcium fly ash (HCFA) and sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>): the soundness, sulfate resistance, alkali-silica reactivity and efflorescence factors are considered. Results of tests show that such mortars are resistant to alkali-silica expansion. Mortars are also sulfate-resistant when the amount of HCFA in the complex binder is within a limit of 10 wt%. The fineness of fly ash determines its’ ability to activate GGBFS hydration, and influence soundness of the binder, early strength development, sulfate resistance and efflorescence behavior. The present article is a continuation of authors’ work, previously published in MSA, Vol. 14, 240-254.展开更多
By means of energy-dispersive X-ray spectroscopy(EDX) and scanning electron microscope(SEM)analysis,the phase structure characteristics of high titanium slag were analyzed.Through the single factor and the orthogonal ...By means of energy-dispersive X-ray spectroscopy(EDX) and scanning electron microscope(SEM)analysis,the phase structure characteristics of high titanium slag were analyzed.Through the single factor and the orthogonal experiment methods,the effects of material particle size,mass ratio of acid to ore,roasting temperature,and roasting time on the acidolysis ratio of TiO_2during the process of roasting high titanium slag with concentrated sulfuric acid were systematically investigated.The results show that the sequence of each factor affecting the acidolysis ratio of TiO_2 is:mass ratio of acid to ore,roasting time,and roasting temperature.The optimum technological conditions are obtained as mass ratio of acid to ore of 2.1,roasting temperature of 310 ℃,roasting time of 75 min,and material particle size of 45-53 μm.The acidolysis ratio of TiO_2 is over 96%under the optimum conditions.The roasting process is proved to be significant in the exploitation and utilization of high titanium slag.The advantages of the proposed roasting process are of high efficiency,low power consumption,and minimum pollution.展开更多
The slag composition corresponding to different coals varies significantly,which directly affects the operation of industrial entrained-flow gasifier and the service life of refractory bricks.In this study,the corrosi...The slag composition corresponding to different coals varies significantly,which directly affects the operation of industrial entrained-flow gasifier and the service life of refractory bricks.In this study,the corrosion resistance of several typical coal slags for gasification on high chromia refractory bricks was comparatively investigated by static laboratory crucible tests and thermodynamic simulations.The results demonstrated that the corrosion degree of high chromia refractory bricks by different coal slags was high-Ca/Na slag>high-Fe slag>high-Si/Al slag.The surface structure of the refractory was relatively flat after corrosion by high-Si/Al slag,and the primary corrosion reaction was the partial dissolution of the matrix by the slag.High-Fe slag was prone to the precipitation of iron phases as well as the formation of(Mg,Fe)(Al,Cr)_(2)O_(4)composite spinel layer at the slag/refractory interface.The high-Ca/Na slag was susceptible to react with the refractory to yield a low melting point phase,which led to the destruction of the matrix structure of the refractory and an isolated distribution of particles.In addition,the monoclinic ZrO_(2) in the refractory reacted with CaO in the slag to formed calcium zirconate,which loosened its phase toughening effect,was the primary factor that aggravated the refractory corrosion.展开更多
The present work investigates copper slag as a substitute for river sand in high-strength concrete.The concrete mixtures were manufactured with 10%,30%,50%,70%,and 100%of copper slag to evaluate the mechanical and dur...The present work investigates copper slag as a substitute for river sand in high-strength concrete.The concrete mixtures were manufactured with 10%,30%,50%,70%,and 100%of copper slag to evaluate the mechanical and durability properties.The experimental results indicate that replacing copper slag above 50%affects the performance characteristics of the concrete due to its high angularity and lower water absorption characteristics.The strength of concrete with 50%copper slag is improved by 5.6%,whereas the strength of concrete with 100%copper slag is reduced by 2.75%at 28 days.However,increased curing to 90days improves the strength of the former by 7.16%and reduces the latter by only 0.23%.The water absorption,porosity,and rapid chloride penetration of the concrete mixtures with 100%copper slag are increased by 10.44%,13.20%,and 19.56%compared to control concrete.Micro-structural investigations through SEM infer higher replacement of copper results in higher void formation due to its reduced water absorption.展开更多
The problem of low disposal and utilization rate of bulk industrial solid waste needs to be solved.In this paper,a high-activity admixture composed of steel slag-phosphate slag-limestone powder was proposed for most o...The problem of low disposal and utilization rate of bulk industrial solid waste needs to be solved.In this paper,a high-activity admixture composed of steel slag-phosphate slag-limestone powder was proposed for most of the solid waste with low activity and a negative impact on concrete workability,combining the characteristics of each solid waste.The paper demonstrates the feasibility and explains the principle of the composite system in terms of water requirement of standard consistency,setting time,workability,and mechanical properties,combined with the composition of the phases,hydration temperature,and microscopic morphology.The results showed that the steel slag:phosphate slag:limestone=5:2:3 gave the highest activity of the composite system,over 92%.Besides,the composite system had no significant effect on water demand and setting time compared to cement,and it could significantly increase the 7 and 28 d activity of the system.The composite system delayed the exothermic hydration of the cement and reduced the exothermic heat but had no effect on the hydration products.Therefore,the research in this paper dramatically improved the solid waste dissipation in concrete,reduced the amount of cement in concrete and positively responded to the national slogan of carbon neutral and peaking.展开更多
High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace sla...High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace slag (GGBFS). Substitution of 10% - 30% of GGBFS by HCFA and premixing of 1% - 3% Na2CO3 to this dry binary binder was discovered to give mortar compression strength of 10 - 30 to 30 - 45 MPa at 7 and 28 days when moist cured at ambient temperature. High-calcium fly ash produced from low-temperature combustion of fuel, like in circulating fluidized bed technology, reacts with water readily and is itself a good hardening activator for GGBFS, so introduction of Na<sub>2</sub>CO<sub>3</sub> into such mix has no noticeable effect on the mortar strength. However, low-temperature HCFA has higher water demand, and the strength of mortar is compromised by this factor. As of today, our research is still ongoing, and we expect to publish more data on different aspects of durability of proposed GGBFS-HCFA binder later.展开更多
A study on the melting and viscosity properties of the chromium-containing high-titanium melting slag(CaO–SiO2–MgO–Al2O3–TiO2–Cr2O3) with TiO2 contents ranging from 38.63 wt% to 42.63 wt% was conducted. The melti...A study on the melting and viscosity properties of the chromium-containing high-titanium melting slag(CaO–SiO2–MgO–Al2O3–TiO2–Cr2O3) with TiO2 contents ranging from 38.63 wt% to 42.63 wt% was conducted. The melting properties were investigated with a meltingpoint apparatus, and viscosity was measured using the rotating cylinder method. The FactSage 7.1 software and X-ray diffraction, in combination with scanning electron microscopy–energy-dispersive spectroscopy(SEM–EDS), were used to characterize the phase equilibrium and microstructure of chromium-containing high-titanium melting slags. The results indicated that an increase in the TiO2 content led to a decrease in the viscosity of the chromium-containing high-titanium melting slag. In addition, the softening temperature, hemispheric temperature, and flowing temperature decreased with increasing TiO2 content. The amount of crystallized anosovite and sphene phases gradually increased with increasing TiO2 content, whereas the amount of perovskite phase decreased. SEM observations revealed that the distribution of the anosovite phase was dominantly influenced by TiO2.展开更多
Laboratory and industrial studies were carried out to investigate non-metallic inclusions in high strength alloy steel refined by high basicity and high Al2O3 slag.It was found that the steel/slag reaction time largel...Laboratory and industrial studies were carried out to investigate non-metallic inclusions in high strength alloy steel refined by high basicity and high Al2O3 slag.It was found that the steel/slag reaction time largely affected non-metallic inclusions.With the reaction time increased from 30 min to 90 min in laboratory study,MgO-Al2O3 spinels were gradually changed into CaO-MgO-Al2O3 system inclusions surrounded by softer CaO-Al2O3 surface layers.By using high basicity slag which contained as much as 41%Al2O3 in the laboratory study,ratio of low melting temperature CaO-MgO-Al2O3 system inclusions was remarkably increased to above 80%.In the industrial experiment,during the secondary refining,the inclusions changed in order of 'Al2O3→MgO-Al2O3→CaO-MgO-Al2O3'.Through the LF and RH refining,most inclusions could be transferred to lower melting temperature CaO-Al2O3 and CaO-MgO-Al2O3 system inclusions.展开更多
In this study,a route for simultaneous mineralization of CO2 and production of titanium dioxide and ammonium alum,and microporous silicon dioxide from titanium-bearing blast furnace slag(TBBF slag)was proposed,which i...In this study,a route for simultaneous mineralization of CO2 and production of titanium dioxide and ammonium alum,and microporous silicon dioxide from titanium-bearing blast furnace slag(TBBF slag)was proposed,which is comprised of(NH4)2 S04 roasting,acid leaching,ammonium alum crystallization,silicic acid flocculation and Ti hydrolysis.The effects of relevant process parameters were systematically investigated.The re sults showed that under the optimal roasting and leaching conditions about 85%of titanium and 84.6%of aluminum could be extracted while only 30%of silicon entered the leachate.84%of Al^3+was crystallized from the leachate in the form of ammonium aluminum sulfate dodecahydrate with a purity up to 99.5 wt%.About 85%of the soluble silicic acid was flocculated with the aid of secondary alcohol polyoxyethylene ether 9(AEO-9)to yield a microporous SiO2 material(97.4 wt%)from the crystallized mother liquor.The Al-and Si-depleted solution was then hydrolyzed to generate a titanium dioxide(99.1 wt%)with uniform particle size distribution.It was figured out that approximately 146 kg TiO2 could be produced from 1000 kg of TBBF slag.Therefore,the improved process is a promising method for industrial application.展开更多
Titanium-bearing blast furnace slag(BFS)has valuable compositions and potential environmental hazardousness.Thus,developing efficient and green approaches to utilize BFS is highly desired for resource economization an...Titanium-bearing blast furnace slag(BFS)has valuable compositions and potential environmental hazardousness.Thus,developing efficient and green approaches to utilize BFS is highly desired for resource economization and environmental protection.In the past decades,many attempts have been adopted to reuse BFS efficiently,and significant advances in understanding the fundamental features and the development of efficient approaches have been achieved.This review provides a comprehensive overview of the latest progress on the efficient utilization of BFS and discusses the mechanism and characteristics of various approaches,along with their application prospects.In particular,the extraction and enrichment of titanium-bearing phases from BFS are highlighted because of the high availability of titanium resources.This systemic and comprehensive review may benefit the design of new and green utilization routes with high efficiency and low cost.展开更多
The smelting of titaniferous magnetitein blast fuynace in China is unique in the natureof problems and their solutions. Fundamentalsof this successful technology will be discussed.Topics to be covered are: （1） the c...The smelting of titaniferous magnetitein blast fuynace in China is unique in the natureof problems and their solutions. Fundamentalsof this successful technology will be discussed.Topics to be covered are: （1） the characteristicsof high content TiO<sub>2</sub> in blast furnace slag;（2） influence of various factors on Ti transferprocess; （3） raising oxygen potential for adequatefluidity of the slag with TiO<sub>2</sub> in the rangeof 25-30 wt-% and stability of TiC and TiN inslag.展开更多
Due to the dispersed distribution of the titanium component in various mineral phases and very fine grain size, it is difficult to recover the titanium component from the slag. In order to utilize titanium resources, ...Due to the dispersed distribution of the titanium component in various mineral phases and very fine grain size, it is difficult to recover the titanium component from the slag. In order to utilize titanium resources, selective enriching and selective growing of the titanium component from the molten slag is expected. In this paper, the selection of the best tita- nium enrichment phase and the effect of oxidization on the enrichment of titanium by blowing air into the molten slag were studied. The results showed that through oxidizing the slag, the content of the perovskite phase increases while that of the other titanium-bearing mineral phases decreases until they disappear. Most titania resources were enriched into the perovskite phase and increase in size. The process of enrichment and growth is easily carried out.展开更多
The novel sulfonated polybenzimidazole(sPBI)/amine functionalized titanium dioxide(AFT) composite membrane is devised and studied for its capability of the application of high temperature proton exchange membrane fuel...The novel sulfonated polybenzimidazole(sPBI)/amine functionalized titanium dioxide(AFT) composite membrane is devised and studied for its capability of the application of high temperature proton exchange membrane fuel cells(HT-PEMFCs),unlike the prior low temperature AFT endeavors.The high temperature compatibility was actualized because of the filling of free volumes in the rigid aromatic matrix of the composite with AFT nanoparticles which inhibited segmental motions of the chains and improved its thermal stability.Besides,amine functionalization of TiO2 enhanced their dispersion character in the sPBI matrix and shortened the interparticle separation gap which finally improved the proton transfer after establishing interconnected pathways and breeding more phosphoric acid(PA) doping.In addition,the appeared assembled clusters of AFT flourished a superior mechanical stability.Thus,the optimized sPBI/AFT(10 wt%) showed 65.3 MPa tensile strength;0.084 S·cm^-1 proton conductivity(at 160℃;in anhydrous conditions),28.6% water uptake and PA doping level of 23 mol per sPBI repeat unit.The maximum power density peak for sPBI/AFT-10 met the figure of0.42 W·cm^-2 at 160℃(in dry conditions) under atmospheric pressure with 1.5 and 2.5 stoichiometric flow rates of H2/air.These results affirmed the probable fitting of sPBI/AFT composite for HT-PEMFC applications.展开更多
The kinetics of the decomposition of acid dissolved titanium slag with a sodium hydroxide system under atmospheric pressure was studied. The effect of reaction temperature, particle size and NaOH-to-slag mass ratio on...The kinetics of the decomposition of acid dissolved titanium slag with a sodium hydroxide system under atmospheric pressure was studied. The effect of reaction temperature, particle size and NaOH-to-slag mass ratio on titanium extraction was investigated. The results show that temperature and particle size have significant influence on titanium extraction. The experimental data of titanium extraction show that the shrinking core model with chemical reaction controlled process is most applicable for the decomposition of slag, with an apparent activation energy of 62.4 kJ·mol-1. Approximately 85 wt.%-90 wt.% of the titanium can be extracted from the slag under the optimal conditions. In addition, the purity of titanium dioxide obtained in the product is up to 98.5 wt.%.展开更多
The blast furnace slag bearing TiO2 in Panzhihua, China, is an important resource to be utilized. In the present paper, the effects of the ratio of slag to H2SO4, the reaction temperature, the particle size of the sla...The blast furnace slag bearing TiO2 in Panzhihua, China, is an important resource to be utilized. In the present paper, the effects of the ratio of slag to H2SO4, the reaction temperature, the particle size of the slag, and the concentration of H2SO4 on the reaction rate and the acidolysis ratio of Ti were studied. The results indicated that the maximum acidolysis ratio reached 98%, which can serve as an experimental basis for the production of titania from the slag.展开更多
Preparing titanium dioxide from titania-rich slag(TiO2 73wt%) by molten NaOH method has been developed.The effects of tem-perature and reaction time on the titanium conversion were investigated.The results showed that...Preparing titanium dioxide from titania-rich slag(TiO2 73wt%) by molten NaOH method has been developed.The effects of tem-perature and reaction time on the titanium conversion were investigated.The results showed that temperature had significant influence on the titanium conversion as well as the structure of the product.About 92% of titanium in the titania-rich slag could be converted after reacting with NaOH at 500℃ for 1 h.Metatitanic acid was formed through the steps of washing treatment,acid dissolution,and hydrolysis.Well-dispersed spherical titanium dioxide particles with an average size of 0.1-0.4 μm can be obtained by calcination of metatitanic acid.In addition,the content of titanium dioxide in the product is up to 98.6wt%,which can be used as pigments after further treatment of coating and crushing.展开更多
基金Project(2007CB613606)supported by the National Basic Research Program of ChinaProjects(50734007,50974067)supported by the National Natural Science Foundation of China
文摘A greenness evaluation index and system of microwave-assisted leaching method were established.The effects of the life cycle assessment variables,such as the resource consumption,environment impact,cost,time and quality,were investigated,and the concept of green degree was applied in the production of synthetic rutile.An analytic hierarchy process was utilized to assess matrix of greenness evaluation.The Gauss-Seidel iterative matrix method was employed to solve the assessment matrix and obtain the weights and membership functions of all evaluation indexes.A fuzzy decision-making method was applied to build the greenness evaluation model,and then the scores of green degree in microwave-assisted leaching process was obtained.The greenness evaluation model was applied to the life cycle assessment of the microwave-assisted leaching process.The results show that the microwave-assisted leaching process has advantages over the conventional ones,with respect to energy-consumption,processing time and environmental protection.
基金Project(2007CB613606) supported by the Major State Basic Research and Development Program of ChinaProject(50734007) supported by the National Natural Science Foundation of China
文摘Microwave absorbing properties of high titanium slag were investigated by using microwave cavity perturbation technique. High titanium slag containing more than 90% TiO2 was prepared by carbothermal reduction of ilmenite. The temperature rise curve of high titanium slag in microwave heating process was obtained. Crystalline compounds of high titanium slag before and after microwave irradiation were obtained and characterized by X-ray diffractometry (XRD). Effects of particle size of high titanium slag and mixtures of high titanium slag with different mass fractions of V2O5 on microwave absorbing properties were investigated systematically. The results show that high titanium slag has good microwave absorption property; untreated high titanium slag mainly consists of crystalline compounds of anatase and iron titanium oxide, while the microwave-irradiation treated one is mainly composed of crystalline compounds of rutile and iron titanium oxide. Synthetic anatase is transformed completely into rutile at about 1 050 ℃ for 20 min under microwave irradiation. High frequency shift and low amplitude of voltage make high titanium slag an ideal microwave absorbent. 180 μm of particle size and 10% mass fraction of V2O5 are found to be the optimum conditions for microwave absorption.
文摘This work investigates durability of cement-free mortars with a binder comprised of ground granulated blast furnace slag (GGBFS) activated by high-calcium fly ash (HCFA) and sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>): the soundness, sulfate resistance, alkali-silica reactivity and efflorescence factors are considered. Results of tests show that such mortars are resistant to alkali-silica expansion. Mortars are also sulfate-resistant when the amount of HCFA in the complex binder is within a limit of 10 wt%. The fineness of fly ash determines its’ ability to activate GGBFS hydration, and influence soundness of the binder, early strength development, sulfate resistance and efflorescence behavior. The present article is a continuation of authors’ work, previously published in MSA, Vol. 14, 240-254.
基金financially supported by the National Natural Science Foundation of China(Nos.61372195 and61304069)the National Basic Research Program of China(No.2007CB613603)
文摘By means of energy-dispersive X-ray spectroscopy(EDX) and scanning electron microscope(SEM)analysis,the phase structure characteristics of high titanium slag were analyzed.Through the single factor and the orthogonal experiment methods,the effects of material particle size,mass ratio of acid to ore,roasting temperature,and roasting time on the acidolysis ratio of TiO_2during the process of roasting high titanium slag with concentrated sulfuric acid were systematically investigated.The results show that the sequence of each factor affecting the acidolysis ratio of TiO_2 is:mass ratio of acid to ore,roasting time,and roasting temperature.The optimum technological conditions are obtained as mass ratio of acid to ore of 2.1,roasting temperature of 310 ℃,roasting time of 75 min,and material particle size of 45-53 μm.The acidolysis ratio of TiO_2 is over 96%under the optimum conditions.The roasting process is proved to be significant in the exploitation and utilization of high titanium slag.The advantages of the proposed roasting process are of high efficiency,low power consumption,and minimum pollution.
基金financial support from the Joint Funds of the National Natural Science Foundation of China(U21A20318).
文摘The slag composition corresponding to different coals varies significantly,which directly affects the operation of industrial entrained-flow gasifier and the service life of refractory bricks.In this study,the corrosion resistance of several typical coal slags for gasification on high chromia refractory bricks was comparatively investigated by static laboratory crucible tests and thermodynamic simulations.The results demonstrated that the corrosion degree of high chromia refractory bricks by different coal slags was high-Ca/Na slag>high-Fe slag>high-Si/Al slag.The surface structure of the refractory was relatively flat after corrosion by high-Si/Al slag,and the primary corrosion reaction was the partial dissolution of the matrix by the slag.High-Fe slag was prone to the precipitation of iron phases as well as the formation of(Mg,Fe)(Al,Cr)_(2)O_(4)composite spinel layer at the slag/refractory interface.The high-Ca/Na slag was susceptible to react with the refractory to yield a low melting point phase,which led to the destruction of the matrix structure of the refractory and an isolated distribution of particles.In addition,the monoclinic ZrO_(2) in the refractory reacted with CaO in the slag to formed calcium zirconate,which loosened its phase toughening effect,was the primary factor that aggravated the refractory corrosion.
基金Part by a Grant from Sona College of TechnologySalem。
文摘The present work investigates copper slag as a substitute for river sand in high-strength concrete.The concrete mixtures were manufactured with 10%,30%,50%,70%,and 100%of copper slag to evaluate the mechanical and durability properties.The experimental results indicate that replacing copper slag above 50%affects the performance characteristics of the concrete due to its high angularity and lower water absorption characteristics.The strength of concrete with 50%copper slag is improved by 5.6%,whereas the strength of concrete with 100%copper slag is reduced by 2.75%at 28 days.However,increased curing to 90days improves the strength of the former by 7.16%and reduces the latter by only 0.23%.The water absorption,porosity,and rapid chloride penetration of the concrete mixtures with 100%copper slag are increased by 10.44%,13.20%,and 19.56%compared to control concrete.Micro-structural investigations through SEM infer higher replacement of copper results in higher void formation due to its reduced water absorption.
基金Key Research and Development Plan of Shaanxi Province(2019TSLGY05-04).
文摘The problem of low disposal and utilization rate of bulk industrial solid waste needs to be solved.In this paper,a high-activity admixture composed of steel slag-phosphate slag-limestone powder was proposed for most of the solid waste with low activity and a negative impact on concrete workability,combining the characteristics of each solid waste.The paper demonstrates the feasibility and explains the principle of the composite system in terms of water requirement of standard consistency,setting time,workability,and mechanical properties,combined with the composition of the phases,hydration temperature,and microscopic morphology.The results showed that the steel slag:phosphate slag:limestone=5:2:3 gave the highest activity of the composite system,over 92%.Besides,the composite system had no significant effect on water demand and setting time compared to cement,and it could significantly increase the 7 and 28 d activity of the system.The composite system delayed the exothermic hydration of the cement and reduced the exothermic heat but had no effect on the hydration products.Therefore,the research in this paper dramatically improved the solid waste dissipation in concrete,reduced the amount of cement in concrete and positively responded to the national slogan of carbon neutral and peaking.
文摘High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace slag (GGBFS). Substitution of 10% - 30% of GGBFS by HCFA and premixing of 1% - 3% Na2CO3 to this dry binary binder was discovered to give mortar compression strength of 10 - 30 to 30 - 45 MPa at 7 and 28 days when moist cured at ambient temperature. High-calcium fly ash produced from low-temperature combustion of fuel, like in circulating fluidized bed technology, reacts with water readily and is itself a good hardening activator for GGBFS, so introduction of Na<sub>2</sub>CO<sub>3</sub> into such mix has no noticeable effect on the mortar strength. However, low-temperature HCFA has higher water demand, and the strength of mortar is compromised by this factor. As of today, our research is still ongoing, and we expect to publish more data on different aspects of durability of proposed GGBFS-HCFA binder later.
基金financially supported by the National Natural Science Foundation of China(No.51904066)the Fundamental Research Funds for the Central Universities,China(No.N182503032)+1 种基金the Postdoctoral Foundation of Northeastern University,China(No.20190201)the Postdoctoral International Exchange Program,China(Dispatch Project,20190075)
文摘A study on the melting and viscosity properties of the chromium-containing high-titanium melting slag(CaO–SiO2–MgO–Al2O3–TiO2–Cr2O3) with TiO2 contents ranging from 38.63 wt% to 42.63 wt% was conducted. The melting properties were investigated with a meltingpoint apparatus, and viscosity was measured using the rotating cylinder method. The FactSage 7.1 software and X-ray diffraction, in combination with scanning electron microscopy–energy-dispersive spectroscopy(SEM–EDS), were used to characterize the phase equilibrium and microstructure of chromium-containing high-titanium melting slags. The results indicated that an increase in the TiO2 content led to a decrease in the viscosity of the chromium-containing high-titanium melting slag. In addition, the softening temperature, hemispheric temperature, and flowing temperature decreased with increasing TiO2 content. The amount of crystallized anosovite and sphene phases gradually increased with increasing TiO2 content, whereas the amount of perovskite phase decreased. SEM observations revealed that the distribution of the anosovite phase was dominantly influenced by TiO2.
文摘Laboratory and industrial studies were carried out to investigate non-metallic inclusions in high strength alloy steel refined by high basicity and high Al2O3 slag.It was found that the steel/slag reaction time largely affected non-metallic inclusions.With the reaction time increased from 30 min to 90 min in laboratory study,MgO-Al2O3 spinels were gradually changed into CaO-MgO-Al2O3 system inclusions surrounded by softer CaO-Al2O3 surface layers.By using high basicity slag which contained as much as 41%Al2O3 in the laboratory study,ratio of low melting temperature CaO-MgO-Al2O3 system inclusions was remarkably increased to above 80%.In the industrial experiment,during the secondary refining,the inclusions changed in order of 'Al2O3→MgO-Al2O3→CaO-MgO-Al2O3'.Through the LF and RH refining,most inclusions could be transferred to lower melting temperature CaO-Al2O3 and CaO-MgO-Al2O3 system inclusions.
基金financial support of the National Key Projects for Fundamental Research and Development of China(2016YFB0600904)Sichuan University Postdoctoral Research and Development Fund(2017SCU12017)+1 种基金Project of State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization(18H0083)Sichuan Science and Technology Department Project(2019YJ0111)。
文摘In this study,a route for simultaneous mineralization of CO2 and production of titanium dioxide and ammonium alum,and microporous silicon dioxide from titanium-bearing blast furnace slag(TBBF slag)was proposed,which is comprised of(NH4)2 S04 roasting,acid leaching,ammonium alum crystallization,silicic acid flocculation and Ti hydrolysis.The effects of relevant process parameters were systematically investigated.The re sults showed that under the optimal roasting and leaching conditions about 85%of titanium and 84.6%of aluminum could be extracted while only 30%of silicon entered the leachate.84%of Al^3+was crystallized from the leachate in the form of ammonium aluminum sulfate dodecahydrate with a purity up to 99.5 wt%.About 85%of the soluble silicic acid was flocculated with the aid of secondary alcohol polyoxyethylene ether 9(AEO-9)to yield a microporous SiO2 material(97.4 wt%)from the crystallized mother liquor.The Al-and Si-depleted solution was then hydrolyzed to generate a titanium dioxide(99.1 wt%)with uniform particle size distribution.It was figured out that approximately 146 kg TiO2 could be produced from 1000 kg of TBBF slag.Therefore,the improved process is a promising method for industrial application.
基金This work was financially supported by the National Nat-ural Science Foundation of China(No.51974011)the Key R&D Program of Ningxia Hui Autonomous Region,China(No.2019BFG02032).
文摘Titanium-bearing blast furnace slag(BFS)has valuable compositions and potential environmental hazardousness.Thus,developing efficient and green approaches to utilize BFS is highly desired for resource economization and environmental protection.In the past decades,many attempts have been adopted to reuse BFS efficiently,and significant advances in understanding the fundamental features and the development of efficient approaches have been achieved.This review provides a comprehensive overview of the latest progress on the efficient utilization of BFS and discusses the mechanism and characteristics of various approaches,along with their application prospects.In particular,the extraction and enrichment of titanium-bearing phases from BFS are highlighted because of the high availability of titanium resources.This systemic and comprehensive review may benefit the design of new and green utilization routes with high efficiency and low cost.
文摘The smelting of titaniferous magnetitein blast fuynace in China is unique in the natureof problems and their solutions. Fundamentalsof this successful technology will be discussed.Topics to be covered are: （1） the characteristicsof high content TiO<sub>2</sub> in blast furnace slag;（2） influence of various factors on Ti transferprocess; （3） raising oxygen potential for adequatefluidity of the slag with TiO<sub>2</sub> in the rangeof 25-30 wt-% and stability of TiC and TiN inslag.
基金This work was financially supported by the National Natural Science Foundation of China (No.50234040)
文摘Due to the dispersed distribution of the titanium component in various mineral phases and very fine grain size, it is difficult to recover the titanium component from the slag. In order to utilize titanium resources, selective enriching and selective growing of the titanium component from the molten slag is expected. In this paper, the selection of the best tita- nium enrichment phase and the effect of oxidization on the enrichment of titanium by blowing air into the molten slag were studied. The results showed that through oxidizing the slag, the content of the perovskite phase increases while that of the other titanium-bearing mineral phases decreases until they disappear. Most titania resources were enriched into the perovskite phase and increase in size. The process of enrichment and growth is easily carried out.
基金supported by the National Natural Science Foundation of China(Nos.21776034,21476044 and 21406031)Joint Funds of the National Natural Science Foundation of China(U1663223)+1 种基金National Key Research and Development Program of China(2016YFB0101203)Changjiang Scholars Program(T2012049)。
文摘The novel sulfonated polybenzimidazole(sPBI)/amine functionalized titanium dioxide(AFT) composite membrane is devised and studied for its capability of the application of high temperature proton exchange membrane fuel cells(HT-PEMFCs),unlike the prior low temperature AFT endeavors.The high temperature compatibility was actualized because of the filling of free volumes in the rigid aromatic matrix of the composite with AFT nanoparticles which inhibited segmental motions of the chains and improved its thermal stability.Besides,amine functionalization of TiO2 enhanced their dispersion character in the sPBI matrix and shortened the interparticle separation gap which finally improved the proton transfer after establishing interconnected pathways and breeding more phosphoric acid(PA) doping.In addition,the appeared assembled clusters of AFT flourished a superior mechanical stability.Thus,the optimized sPBI/AFT(10 wt%) showed 65.3 MPa tensile strength;0.084 S·cm^-1 proton conductivity(at 160℃;in anhydrous conditions),28.6% water uptake and PA doping level of 23 mol per sPBI repeat unit.The maximum power density peak for sPBI/AFT-10 met the figure of0.42 W·cm^-2 at 160℃(in dry conditions) under atmospheric pressure with 1.5 and 2.5 stoichiometric flow rates of H2/air.These results affirmed the probable fitting of sPBI/AFT composite for HT-PEMFC applications.
基金supported by the National Natural Science Foundation of China (No.50574084)the National Key Technologies R&D Program in the 11th Five-Year Plan Period of China (No.2006BAC02A05)the National Basic Research Program of China (No.2007CB613501)
文摘The kinetics of the decomposition of acid dissolved titanium slag with a sodium hydroxide system under atmospheric pressure was studied. The effect of reaction temperature, particle size and NaOH-to-slag mass ratio on titanium extraction was investigated. The results show that temperature and particle size have significant influence on titanium extraction. The experimental data of titanium extraction show that the shrinking core model with chemical reaction controlled process is most applicable for the decomposition of slag, with an apparent activation energy of 62.4 kJ·mol-1. Approximately 85 wt.%-90 wt.% of the titanium can be extracted from the slag under the optimal conditions. In addition, the purity of titanium dioxide obtained in the product is up to 98.5 wt.%.
文摘The blast furnace slag bearing TiO2 in Panzhihua, China, is an important resource to be utilized. In the present paper, the effects of the ratio of slag to H2SO4, the reaction temperature, the particle size of the slag, and the concentration of H2SO4 on the reaction rate and the acidolysis ratio of Ti were studied. The results indicated that the maximum acidolysis ratio reached 98%, which can serve as an experimental basis for the production of titania from the slag.
基金financially supported by the National Key Technologies R & D Program of China (No.2006BAC02A05)the National Basic Research Program of China (No. 2007CB613501)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KGCX2-YW-214)the Special Funds of "Mountain Tai Scholar" Construction Project
文摘Preparing titanium dioxide from titania-rich slag(TiO2 73wt%) by molten NaOH method has been developed.The effects of tem-perature and reaction time on the titanium conversion were investigated.The results showed that temperature had significant influence on the titanium conversion as well as the structure of the product.About 92% of titanium in the titania-rich slag could be converted after reacting with NaOH at 500℃ for 1 h.Metatitanic acid was formed through the steps of washing treatment,acid dissolution,and hydrolysis.Well-dispersed spherical titanium dioxide particles with an average size of 0.1-0.4 μm can be obtained by calcination of metatitanic acid.In addition,the content of titanium dioxide in the product is up to 98.6wt%,which can be used as pigments after further treatment of coating and crushing.
