To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag sys...To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag systems were used to conduct electroslag remelting experiments on 304L austenitic stainless steel,and the macrostructure of electroslag ingots was analyzed.The results indicate that the depth of the metal pool decreases with the reduction of remelting frequency in the low frequency power supply mode.The effects of different power supply modes,such as low-frequency,direct current straight polarity(DCSP),and direct current reverse polarity(DCRP),on reducing the depth of the metal pool increase in that order.By reducing the remelting current strength in the same power supply mode,the depth of metal pool is reduced.When compared to the binary slag system of 70%CaF2+30%Al2O3,the ternary slag system of 60%CaF2+20%Al2O3+20%CaO is more effective in reducing the depth of the metal pool during remelting.Utilizing the 60%CaF2+20%Al2O3+20%CaO ternary slag system results in a shallower and flatter metal pool,with columnar crystal growth occurring closer to the axial crystal.This effect is observed for both low frequency and direct current(DC)power supply modes.展开更多
The reduction of phosphogypsum(PG)to lime slag and SO_(2)using coke can effectively alleviate the environmental problems caused by PG.However,the PG decomposition temperature remains high and the product yield remains...The reduction of phosphogypsum(PG)to lime slag and SO_(2)using coke can effectively alleviate the environmental problems caused by PG.However,the PG decomposition temperature remains high and the product yield remains poor.By adding additives,the decomposition temperature can be further reduced and PG decomposition rate and product yield can be improved.However,the use of current additives such as Fe_(2)O_(3)and SiO_(2)brings the problem of increasing economic cost.Therefore,it is proposed to use solid waste copper slag(CS)as a new additive to reduce PG to prepare SO2,which can reduce the cost and meet the environmental benefits at the same time.The effects of proportion,temperature and thermostatic time on PG decomposition are investigated by experimental and kinetic analysis combined with FactSage thermodynamic calculations to optimize the roasting conditions.Finally,the reaction mechanism is proposed.It is found that adding CS to the coke and PG system can increase the rate of PG decomposition and SO_(2)yield while lowering the PG decomposition temperature.For example,when the CS/PG mass ratio increases from 0 to 1,PG decomposition rate increases from 83.38%to 99.35%,SO_(2)yield increases from 78.62%to 96.81%,and PG decomposition temperature decreases from 992.4℃to 949.6℃.The optimal reaction parameters are CS/PG mass ratio of 1,Coke/PG mass ratio of 0.06 at 1100℃for 20 min with 99.35%PG decomposition rate and 96.81%SO_(2) yield.The process proceeds according to the following reactions:2CaSO_(4)+ 0.7C + 0.8Fe_(2)SiO_(4)→0.8Ca_(2)SiO_(4)+ 0.2Ca_(2)Fe_(2)O_(5)+ 0.4Fe_(3)O_(4)+2SO_(2)+ 0.7CO_(2)Finally,a process for decomposing PG with coke and CS is proposed.展开更多
The precise measurement of Al, Mg, Ca, and Zn composition in copper slag is crucial for effective process control of copper pyrometallurgy. In this study, a remote laser-induced breakdown spectroscopy(LIBS) system was...The precise measurement of Al, Mg, Ca, and Zn composition in copper slag is crucial for effective process control of copper pyrometallurgy. In this study, a remote laser-induced breakdown spectroscopy(LIBS) system was utilized for the spectral analysis of copper slag samples at a distance of 2.5 m. The composition of copper slag was then analyzed using both the calibration curve(CC) method and the partial least squares regression(PLSR) analysis method based on the characteristic spectral intensity ratio. The performance of the two analysis methods was gauged through the determination coefficient(R^(2)), average relative error(ARE), root mean square error of calibration(RMSEC), and root mean square error of prediction(RMSEP). The results demonstrate that the PLSR method significantly improved both R^(2) for the calibration and test sets while reducing ARE, RMSEC, and RMSEP by 50% compared to the CC method. The results suggest that the combination of LIBS and PLSR is a viable approach for effectively detecting the elemental concentration in copper slag and holds potential for online detection of the elemental composition of high-temperature molten copper slag.展开更多
To realize the resource utilization of the valuable metals in the titanium-containing blast furnace slag,the process route of “hydrochloric acid leaching-electrolysis-carbonization and carbon dioxide capture-preparat...To realize the resource utilization of the valuable metals in the titanium-containing blast furnace slag,the process route of “hydrochloric acid leaching-electrolysis-carbonization and carbon dioxide capture-preparation of calcium carbonate” was proposed.In this study,the influences of process conditions on the leaching rates of calcium,magnesium,aluminum,and iron and the phases of the leaching residue were investigated for the leaching process.The experimental results show that the HCl solution could selectively leach the elements from the titanium-containing blast furnace slag.The better leaching conditions are the HCl solution concentration of 4 mol/L,the leaching time of 30 min,the ratio of liquid volume to solid gas of 10 mL/g,and the stirring paddle speed of 300 r/min.Under the conditions,the leaching rates of calcium,magnesium,aluminum,and iron can reach 85.87%,73.41%,81.35%,and 59.08%,and the leaching rate of titanium is 10.71%.The iron and the aluminum are removed from the leachate to obtain iron-aluminum water purification agents,and the magnesium is removed from the leachate to obtain magnesium hydroxide.The leaching residue phase is dominated by perovskite,followed by magnesium silicate and tricalcium aluminate,and the titaniumrich material could be obtained from the leaching residue by desiliconization.展开更多
Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimen...Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimental environmental issues.To prevent chromium pollution,the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work.The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4.Spinels were found to be mainly distrib-uted at the top and bottom of slag.The amount of spinel phase at the bottom decreased with the increasing FeO content,while that at the top increased.The average particle size of spinel in the slag with 18wt%FeO content was 12.8μm.Meanwhile,no notable structural changes were observed with a further increase in FeO content.In other words,the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt%to 18wt%.Finally,less spinel was found at the bottom of slag with a FeO content of 23wt%.展开更多
The effects of different contents of a MgO expansive agent and phosphorus slag on the mechanical properties,shrinkage behavior,and the heat of hydration of concrete were studied.The slump flow,setting time,dry shrinka...The effects of different contents of a MgO expansive agent and phosphorus slag on the mechanical properties,shrinkage behavior,and the heat of hydration of concrete were studied.The slump flow,setting time,dry shrinkage,and hydration heat were used as sensitive parameters to assess the response of the considered specimens.As shown by the results,in general,with an increase in the phosphorus slag content,the hydration heat of concrete decreases for all ages,but the early strength displays a downward trend and the dry shrinkage rate increases.The 90-d strength and dry shrinkage of concrete could be improved with a phosphorus residue content between 0%-20%,with the best performances in terms of mechanical properties and shrinkage characteristics being achieved for a content of 20 kg/m3.On the basis of these results,it can be concluded that appropriate amounts of phosphorus slag and MgO expansive agent can be used to improve the compressive strength of concrete in the later stage by reducing the hydration heat and dry shrinkage rate,respectively.展开更多
Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementi...Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementitious material(CNCM)was synthesized by using different chemical activation methods to enhance its hydration reactivity and CO_(2) mineralization capacity.Different water curing ages and carbonation conditions were explored related to their carbonation and mechanical properties development.Meanwhile,thermogravimetry differential scanning calorimetry and X-ray diffraction methods were applied to evaluate the CO_(2) adsorption amount and carbonation products of CNCM.Microstructure development of carbonated CNCM blocks was examined by backscattered electron imaging(BSE)with energy-dispersive X-ray spectrometry.Results showed that among the studied samples,the CNCM sample that was subjected to water curing for 3 d exhibited the highest CO_(2) sequestration amount of 8.51wt%at 80℃and 72 h while presenting the compressive strength of 39.07 MPa.This result indicated that 1 t of this CNCM can sequester 85.1 kg of CO_(2) and exhibit high compressive strength.Although the addition of citric acid did not improve strength development,it was beneficial to increase the CO_(2) diffusion and adsorption amount under the same carbonation conditions from BSE results.This work provides guidance for synthesizing CO_(2)-mineralized cementitious materials using large amounts of metallurgical slags containing olivine minerals.展开更多
Dredged marine soils(DMS)have poor engineering properties,which limit their usage in construction projects.This research examines the application of reactive magnesia(rMgO)containing supplementary cementitious materia...Dredged marine soils(DMS)have poor engineering properties,which limit their usage in construction projects.This research examines the application of reactive magnesia(rMgO)containing supplementary cementitious materials(SCMs)to stabilize DMS under ambient and carbon dioxide(CO_(2))curing conditions.Several proprietary experimental tests were conducted to investigate the stabilized DMS.Furthermore,the carbonation-induced mineralogical,thermal,and microstructural properties change of the samples were explored.The findings show that the compressive strength of the stabilized DMS fulfilled the 7-d requirement(0.7-2.1 MPa)for pavement and building foundations.Replacing rMgO with SCMs such as biochar or ground granulated blast-furnace slag(GGBS)altered the engineering properties and particle packing of the stabilized soils,thus influencing their performances.Biochar increased the porosity of the samples,facilitating higher CO_(2) uptake and improved ductility,while GGBS decreased porosity and increased the dry density of the samples,resulting in higher strength.The addition of SCMs also enhanced the water retention capacity and modified the pH of the samples.Microstructural analysis revealed that the hydrated magnesium carbonates precipitated in the carbonated samples provided better cementation effects than brucite formed during rMgO hydration.Moreover,incorporating SCMs reduced the overall global warming potential and energy demand of the rMgO-based systems.The biochar mixes demonstrated lower toxicity and energy consumption.Ultimately,the rMgO and biochar blend can serve as an environmentally friendly additive for soft soil stabilization and permanent fixation of significant amounts of CO_(2) in soils through mineral carbonation,potentially reducing environmental pollution while meeting urbanization needs.展开更多
Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery a...Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery and the high-value utilization of residual carbon(RC)in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits.The structural properties,such as pore,surface functional group,and microcrystalline structures,of RC in FS(FS-RC)not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC.In this paper,the characteristics of FS-RC in terms of pore structure,surface functional groups,and microcrystalline structure are sorted out in accordance with gasification type and FS particle size.The reasons for the formation of the special structural properties of FS-RC are analyzed,and their influence on the flotation separation and high-value utilization of FS-RC is summarized.Separation methods based on the pore structural characterist-ics of FS-RC,such as ultrasonic pretreatment-pore-blocking flotation and pore breaking-flocculation flotation,are proposed to be the key development technologies for improving FS-RC recovery in the future.The design of low-cost,low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future.The high-value utilization of FS should be based on the physicochemical structural proper-ties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to es-tablish an environmentally friendly utilization method.This review is of great theoretical importance for the comprehensive understand-ing of the unique structural properties of FS-RC,the breakthrough of the technological bottleneck in the efficient flotation separation of FS,and the expansion of the field of the high value-added utilization of FS-RC.展开更多
Rapid online analysis of liquid slag is essential for optimizing the quality and energy efficiency of steel production. To investigate the key factors that affect the online measurement of refined slag using laser-ind...Rapid online analysis of liquid slag is essential for optimizing the quality and energy efficiency of steel production. To investigate the key factors that affect the online measurement of refined slag using laser-induced breakdown spectroscopy(LIBS), this study examined the effects of slag composition and temperature on the intensity and stability of the LIBS spectra. The experimental temperature was controlled at three levels: 1350℃, 1400℃, and 1450℃. The results showed that slag composition and temperature significantly affected the intensity and stability of the LIBS spectra. Increasing the Fe content and temperature in the slag reduces its viscosity, resulting in an enhanced intensity and stability of the LIBS spectra. Additionally, 42 refined slag samples were quantitatively analyzed for Fe, Si, Ca, Mg, Al, and Mn at 1350℃, 1400℃, and 1450℃.The normalized full spectrum combined with partial least squares(PLS) quantification modeling was used, using the Ca Ⅱ 317.91 nm spectral line as an internal standard. The results show that using the internal standard normalization method can significantly reduce the influence of spectral fluctuations. Meanwhile, a temperature of 1450℃ has been found to yield superior results compared to both 1350℃ and 1400℃, and it is advantageous to conduct a quantitative analysis of the slag when it is in a “water-like” state with low viscosity.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
The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO...The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO ratios prepared on the basis of the range of oxide contents of Zhundong coal ash were investigated in this study. The results show that with the MgO/CaO ratio increase, the initial crystallization temperature increases, and the main temperature range of crystallization ratio growth moves to higher temperature range gradually which causes Tp25(Tp25is the temperature corresponding to the viscosity of 25 Pa·s)to increase. Mg-rich crystals are formed preferentially than Ca-rich crystals when adding the same amount of MgO and CaO during cooling. The effective slagging operating temperature range decrease from 217 ℃ for the slag with a 0:4 MgO/CaO ratio to 44 ℃ for the slag with a 4:0 MgO/CaO ratio with the MgO/CaO ratio increase. The slags with 2:2 and 1:3 MgO/CaO ratios show similar effective slagging operating temperature range, Tp25and the temperature corresponding to the viscosity of 2 Pa·s.However, compared with the slag with a 1:3 MgO/CaO ratio, the crystallization ratio and rate of slag with a 2:2 MgO/CaO ratio are lower within lower temperature range(1300–1200 ℃), causing its lower critical viscosity temperature and wider actual operating temperature range. Of the five slags, the widest effective slagging operating temperature range and the lowest Tp25of the slag with a 0:4 MgO/CaO ratio due to its low crystallization ratio, and wider actual operating temperature range of the slag with a 2:2 MgO/CaO ratio make the two slags suitable for slag discharge of EFB gasifier.展开更多
The dissolution kinetics of Al_(2)O_(3) in CaO-Al_(2)O_(3) SiOslags was studied using a high-temperature confocal scanning laser microscope at 1773 to 1873 K.The results show that the controlling step during the Al_(2...The dissolution kinetics of Al_(2)O_(3) in CaO-Al_(2)O_(3) SiOslags was studied using a high-temperature confocal scanning laser microscope at 1773 to 1873 K.The results show that the controlling step during the Al_(2)O_(3) dissolution was the diffusionin molten slag.It was found that the dissolution curves of Al_(2)O_(3) particles were hardly agreed with the traditional boundary layer diffusion model with the increase of the CaO/Al_(2)O_(3) ratio of slag.A modified diffusion equation considering slag viscosity was developed to study the dissolution mechanism of Al_(2)O_(3) in slag.Diffusion coefficients of Al_(2)O_(3) in slag were calculated as 2.8×10to 4.1×10m~2/s at the temperature of 1773-1873 K.The dissolution rate of Al_(2)O_(3) increased with higher temperature,CaO/Al_(2)O_(3),and particle size.A new model was shown to be v_(Al_(2)O_(3))=0.16×r_(0)^(1.58)×x^(3.52)×(T-T_(mp))^(1.11)to predict the dissolution rate and the total dissolution time of Al_(2)O_(3) inclusions with various sizes,where vAl_(2)O_(3) is the dissolution rate of Al_(2)O_(3) in volume,μm^(3)/s;x is the value of CaO/Al_(2)O_(3) mass ratio;R_(0) is the initial radius of Al_(2)O_(3),μm;T is the temperature,K;T_(mp) is the melting point of slag,K.展开更多
The metallurgical properties of the CaO–SiO_(2)–Al_(2)O_(3)–4.6wt%Mg O–Fe_(2)O_(3)slag system,formed by the co-treatment process of spent automotive catalyst(SAC)and copper-bearing electroplating sludge(CBES),were...The metallurgical properties of the CaO–SiO_(2)–Al_(2)O_(3)–4.6wt%Mg O–Fe_(2)O_(3)slag system,formed by the co-treatment process of spent automotive catalyst(SAC)and copper-bearing electroplating sludge(CBES),were studied systematically in this paper.The slag structure,melting temperature,and viscous characteristics were investigated by Fourier transform infrared(FTIR)spectroscopy,Raman spectroscopy,Fact Sage calculation,and viscosity measurements.Experimental results show that the increase of Fe_(2)O_(3)content(3.8wt%–16.6wt%),the mass ratio of CaO/SiO_(2)(m(CaO)/m(SiO_(2)),0.5–1.3),and the mass ratio of SiO_(2)/Al_(2)O_(3)(m(SiO_(2))/m(Al_(2)O_(3)),1.0–5.0)can promote the depolymerization of silicate network,and the presence of a large amount of Fe_(2)O_(3)in form of tetrahedral and octahedral units ensures the charge compensation of Al^(3+)ions and makes Al_(2)O_(3)only behave as an acid oxide.Thermodynamic calculation and viscosity measurements show that with the increase of Fe_(2)O_(3)content,m(Ca O)/m(SiO_(2)),and m(SiO_(2))/m(Al_(2)O_(3)),the depolymerization of silicate network structure and low-melting-point phase transformation first occur within the slag,leading to the decrease in melting point and viscosity of the slag,while further increase causes the formation of high-melting-point phase and a resultant re-increase in viscosity and melting point.Based on experimental analysis,the preferred slag composition with low polymerization degree,viscosity,and melting point is as follows:Fe_(2)O_(3)content of 10.2wt%–13.4wt%,m(CaO)/m(SiO_(2))of 0.7–0.9 and m(SiO_(2))/m(Al_(2)O_(3))of 3.0–4.0.This work provides a theoretical support for slag design in co-smelting process of SAC and CBES.展开更多
Cement,phosphorous slag(PS),and steel slag(SS)were used to prepare low-carbon cementitious materials,and triisopropanolamine(TIPA)was used to improve the mechanical properties by controlling the hydration process.The ...Cement,phosphorous slag(PS),and steel slag(SS)were used to prepare low-carbon cementitious materials,and triisopropanolamine(TIPA)was used to improve the mechanical properties by controlling the hydration process.The experimental results show that,by using 0.06%TIPA,the compressive strength of cement containing 60%PS or 60%SS could be enhanced by 12%or 18%at 28 d.The presence of TIPA significantly affected the hydration process of PS and SS in cement.In the early stage,TIPA accelerated the dissolution of Al in PS,and the formation of carboaluminate hydrate was facilitated,which could induce the hydration;TIPA promoted the dissolution of Fe in SS,and the formation of Fe-monocarbonate,which was precipitated on the surface of SS,resulting in the postponement of hydration,especially for the high SS content.In the later stage,under the continuous solubilization effect of TIPA,the hydration of PS and SS could refine the pore structure.It was noted that compared with portland cement,the carbon emissions of cement-PS-TIPA and cement-SS-TIPA was reduced by 52%and 49%,respectively.展开更多
Energy shortage and the emission of greenhouse gases have become a global problem of urgent concern.Therefore,there is an urgent need to develop a low carbon building material.Geopolymers have become a hot topic due t...Energy shortage and the emission of greenhouse gases have become a global problem of urgent concern.Therefore,there is an urgent need to develop a low carbon building material.Geopolymers have become a hot topic due to their environmental sustainability and the feasibility of immobilizing industrial waste.In this paper,steel slag(SS)fines were investigated as auxiliary materials of blast furnace slag(BFS)based geopolymer.The hydration heat properties,flowability,compressive strength,sorptivity coefficient,X-ray diffraction(XRD),and scanning electron microscopy(SEM)of the geopolymer pastes were determined.The results showed that the incorporation of SS weakened the reactivity of the BFS-based geopolymer paste and improved the flow values of the paste.The compressive strength of the geopolymer with 20%SS content reached 117 MPa at 28 d.The geopolymer specimens with high compressive strength showed a low sorptivity coefficient.The microscopic results showed that the addition of the appropriate amount of SS reduced the cracks,improved the density of the geopolymer,and produced a geopolymer composite with excellent mechanical properties.展开更多
Steel slag is characterized by high strength,good wear resistance and micro-expansion.This study aims at exploring the potential of steel slag in cement stabilized aggregates,mainly including mechanical properties,shr...Steel slag is characterized by high strength,good wear resistance and micro-expansion.This study aims at exploring the potential of steel slag in cement stabilized aggregates,mainly including mechanical properties,shrinkage and compensation mechanisms.For this purpose,the compressive strength and compressive resilient modulus of cement stabilized aggregates with different steel slag contents(CSMS)were initially investigated.Subsequently,the effects of steel slag and cement on dry shrinkage,temperature shrinkage,and total shrinkage were analyzed through a series of shrinkage test designs.Additionally,in combination with X-ray diffraction(XRD)and Scanning electron microscope(SEM),the characteristic peaks and microscopic images of cement,steel slag and cement-steel slag at different hydration ages were analyzed to identify the chemical substances causing the expansion volume of steel slag and reveal the compensation mechanism of CSMS.The results show that the introduction of 20%steel slag improved the mechanical properties of CSMS by 16.7%,reduced dry shrinkage by 21%,increased temperature shrinkage by 5.8%and reduced its total shrinkage by 19.2%.Compared with the hydration reaction of cement alone,the composite hydration reaction of steel slag with cement does not produce new hydrates.Furthermore,it is noteworthy that the volume expansion of the f-CaO hydration reaction in steel slag can compensate for the volume shrinkage of cement-stabilized macadam.This research can provide a solid theoretical basis for the application and promotion of steel slag in cement-stabilized macadam and reduce the possibility of shrinkage cracking.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
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52074002,52174289)Natural Science Foundation of Anhui Province(Grant No.2208085J37)。
文摘To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag systems were used to conduct electroslag remelting experiments on 304L austenitic stainless steel,and the macrostructure of electroslag ingots was analyzed.The results indicate that the depth of the metal pool decreases with the reduction of remelting frequency in the low frequency power supply mode.The effects of different power supply modes,such as low-frequency,direct current straight polarity(DCSP),and direct current reverse polarity(DCRP),on reducing the depth of the metal pool increase in that order.By reducing the remelting current strength in the same power supply mode,the depth of metal pool is reduced.When compared to the binary slag system of 70%CaF2+30%Al2O3,the ternary slag system of 60%CaF2+20%Al2O3+20%CaO is more effective in reducing the depth of the metal pool during remelting.Utilizing the 60%CaF2+20%Al2O3+20%CaO ternary slag system results in a shallower and flatter metal pool,with columnar crystal growth occurring closer to the axial crystal.This effect is observed for both low frequency and direct current(DC)power supply modes.
基金financial support from the school-enterprise cooperation projects(2019-KYY-508101-0078).
文摘The reduction of phosphogypsum(PG)to lime slag and SO_(2)using coke can effectively alleviate the environmental problems caused by PG.However,the PG decomposition temperature remains high and the product yield remains poor.By adding additives,the decomposition temperature can be further reduced and PG decomposition rate and product yield can be improved.However,the use of current additives such as Fe_(2)O_(3)and SiO_(2)brings the problem of increasing economic cost.Therefore,it is proposed to use solid waste copper slag(CS)as a new additive to reduce PG to prepare SO2,which can reduce the cost and meet the environmental benefits at the same time.The effects of proportion,temperature and thermostatic time on PG decomposition are investigated by experimental and kinetic analysis combined with FactSage thermodynamic calculations to optimize the roasting conditions.Finally,the reaction mechanism is proposed.It is found that adding CS to the coke and PG system can increase the rate of PG decomposition and SO_(2)yield while lowering the PG decomposition temperature.For example,when the CS/PG mass ratio increases from 0 to 1,PG decomposition rate increases from 83.38%to 99.35%,SO_(2)yield increases from 78.62%to 96.81%,and PG decomposition temperature decreases from 992.4℃to 949.6℃.The optimal reaction parameters are CS/PG mass ratio of 1,Coke/PG mass ratio of 0.06 at 1100℃for 20 min with 99.35%PG decomposition rate and 96.81%SO_(2) yield.The process proceeds according to the following reactions:2CaSO_(4)+ 0.7C + 0.8Fe_(2)SiO_(4)→0.8Ca_(2)SiO_(4)+ 0.2Ca_(2)Fe_(2)O_(5)+ 0.4Fe_(3)O_(4)+2SO_(2)+ 0.7CO_(2)Finally,a process for decomposing PG with coke and CS is proposed.
基金supported by funding for research activities of postdoctoral researchers in Anhui Provincespecial funds for developing Anhui Province’s industrial “three highs” and high-tech industries。
文摘The precise measurement of Al, Mg, Ca, and Zn composition in copper slag is crucial for effective process control of copper pyrometallurgy. In this study, a remote laser-induced breakdown spectroscopy(LIBS) system was utilized for the spectral analysis of copper slag samples at a distance of 2.5 m. The composition of copper slag was then analyzed using both the calibration curve(CC) method and the partial least squares regression(PLSR) analysis method based on the characteristic spectral intensity ratio. The performance of the two analysis methods was gauged through the determination coefficient(R^(2)), average relative error(ARE), root mean square error of calibration(RMSEC), and root mean square error of prediction(RMSEP). The results demonstrate that the PLSR method significantly improved both R^(2) for the calibration and test sets while reducing ARE, RMSEC, and RMSEP by 50% compared to the CC method. The results suggest that the combination of LIBS and PLSR is a viable approach for effectively detecting the elemental concentration in copper slag and holds potential for online detection of the elemental composition of high-temperature molten copper slag.
基金Funded by the National Natural Science Foundation of China Youth Fund(No.52204419)the Liaoning Provincial Natural Science Foundation(No.2022-BS-076)the Guangxi Science and Technology Major Project(No.2021AA12013)。
文摘To realize the resource utilization of the valuable metals in the titanium-containing blast furnace slag,the process route of “hydrochloric acid leaching-electrolysis-carbonization and carbon dioxide capture-preparation of calcium carbonate” was proposed.In this study,the influences of process conditions on the leaching rates of calcium,magnesium,aluminum,and iron and the phases of the leaching residue were investigated for the leaching process.The experimental results show that the HCl solution could selectively leach the elements from the titanium-containing blast furnace slag.The better leaching conditions are the HCl solution concentration of 4 mol/L,the leaching time of 30 min,the ratio of liquid volume to solid gas of 10 mL/g,and the stirring paddle speed of 300 r/min.Under the conditions,the leaching rates of calcium,magnesium,aluminum,and iron can reach 85.87%,73.41%,81.35%,and 59.08%,and the leaching rate of titanium is 10.71%.The iron and the aluminum are removed from the leachate to obtain iron-aluminum water purification agents,and the magnesium is removed from the leachate to obtain magnesium hydroxide.The leaching residue phase is dominated by perovskite,followed by magnesium silicate and tricalcium aluminate,and the titaniumrich material could be obtained from the leaching residue by desiliconization.
基金the National Natural Science Foundation of China(Nos.52074078 and 52374327)the Applied Fundamental Research Program of Liaoning Province(No.2023JH2/101600002)+2 种基金the Shenyang Young Middle-Aged Scientific and Technological Innovation Talent Support Program(No.RC220491)the Liaoning Province Steel Industry-University-Research Innovation Alliance Cooperation Project of Bensteel Group(No.KJBLM202202)the Fundamental Research Funds for the Central Universities(Nos.N2201023 and N2325009).
文摘Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimental environmental issues.To prevent chromium pollution,the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work.The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4.Spinels were found to be mainly distrib-uted at the top and bottom of slag.The amount of spinel phase at the bottom decreased with the increasing FeO content,while that at the top increased.The average particle size of spinel in the slag with 18wt%FeO content was 12.8μm.Meanwhile,no notable structural changes were observed with a further increase in FeO content.In other words,the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt%to 18wt%.Finally,less spinel was found at the bottom of slag with a FeO content of 23wt%.
基金supported by CSCEC Technology Research and Development Plan(CSCEC-2020-Z-39).
文摘The effects of different contents of a MgO expansive agent and phosphorus slag on the mechanical properties,shrinkage behavior,and the heat of hydration of concrete were studied.The slump flow,setting time,dry shrinkage,and hydration heat were used as sensitive parameters to assess the response of the considered specimens.As shown by the results,in general,with an increase in the phosphorus slag content,the hydration heat of concrete decreases for all ages,but the early strength displays a downward trend and the dry shrinkage rate increases.The 90-d strength and dry shrinkage of concrete could be improved with a phosphorus residue content between 0%-20%,with the best performances in terms of mechanical properties and shrinkage characteristics being achieved for a content of 20 kg/m3.On the basis of these results,it can be concluded that appropriate amounts of phosphorus slag and MgO expansive agent can be used to improve the compressive strength of concrete in the later stage by reducing the hydration heat and dry shrinkage rate,respectively.
基金supported by the Intergovernmental International Science and Technology Innovation Cooperation Key Project of the National Key Research and Development Program of China (No.2022YFE0135100)the National Natural Science Foundation of China (No.52072171)+1 种基金the Beijing Nova Program (No.20220484057)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
文摘Water-quenched copper-nickel metallurgical slag enriched with olivine minerals exhibits promising potential for the production of CO_(2)-mineralized cementitious materials.In this work,copper-nickel slag-based cementitious material(CNCM)was synthesized by using different chemical activation methods to enhance its hydration reactivity and CO_(2) mineralization capacity.Different water curing ages and carbonation conditions were explored related to their carbonation and mechanical properties development.Meanwhile,thermogravimetry differential scanning calorimetry and X-ray diffraction methods were applied to evaluate the CO_(2) adsorption amount and carbonation products of CNCM.Microstructure development of carbonated CNCM blocks was examined by backscattered electron imaging(BSE)with energy-dispersive X-ray spectrometry.Results showed that among the studied samples,the CNCM sample that was subjected to water curing for 3 d exhibited the highest CO_(2) sequestration amount of 8.51wt%at 80℃and 72 h while presenting the compressive strength of 39.07 MPa.This result indicated that 1 t of this CNCM can sequester 85.1 kg of CO_(2) and exhibit high compressive strength.Although the addition of citric acid did not improve strength development,it was beneficial to increase the CO_(2) diffusion and adsorption amount under the same carbonation conditions from BSE results.This work provides guidance for synthesizing CO_(2)-mineralized cementitious materials using large amounts of metallurgical slags containing olivine minerals.
基金This work was supported by the Creative Groups of Natural Science Foundation of Hubei Province(Grant No.2021CFA030).Onyekwena Chikezie Chimere is an awardee for the ANSO Scholarship 2020-PhD.Ishrat Hameed Alvi is a recipient of the 2021 PhD ANSO Scholarship.
文摘Dredged marine soils(DMS)have poor engineering properties,which limit their usage in construction projects.This research examines the application of reactive magnesia(rMgO)containing supplementary cementitious materials(SCMs)to stabilize DMS under ambient and carbon dioxide(CO_(2))curing conditions.Several proprietary experimental tests were conducted to investigate the stabilized DMS.Furthermore,the carbonation-induced mineralogical,thermal,and microstructural properties change of the samples were explored.The findings show that the compressive strength of the stabilized DMS fulfilled the 7-d requirement(0.7-2.1 MPa)for pavement and building foundations.Replacing rMgO with SCMs such as biochar or ground granulated blast-furnace slag(GGBS)altered the engineering properties and particle packing of the stabilized soils,thus influencing their performances.Biochar increased the porosity of the samples,facilitating higher CO_(2) uptake and improved ductility,while GGBS decreased porosity and increased the dry density of the samples,resulting in higher strength.The addition of SCMs also enhanced the water retention capacity and modified the pH of the samples.Microstructural analysis revealed that the hydrated magnesium carbonates precipitated in the carbonated samples provided better cementation effects than brucite formed during rMgO hydration.Moreover,incorporating SCMs reduced the overall global warming potential and energy demand of the rMgO-based systems.The biochar mixes demonstrated lower toxicity and energy consumption.Ultimately,the rMgO and biochar blend can serve as an environmentally friendly additive for soft soil stabilization and permanent fixation of significant amounts of CO_(2) in soils through mineral carbonation,potentially reducing environmental pollution while meeting urbanization needs.
基金the National Natural Science Foundation of China(No.52374279)the Natural Science Foundation of Shaanxi Province(No.2023-YBGY-055).
文摘Coal gasification fine slag(FS)is a typical solid waste generated in coal gasification.Its current disposal methods of stockpil-ing and landfilling have caused serious soil and ecological hazards.Separation recovery and the high-value utilization of residual carbon(RC)in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits.The structural properties,such as pore,surface functional group,and microcrystalline structures,of RC in FS(FS-RC)not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC.In this paper,the characteristics of FS-RC in terms of pore structure,surface functional groups,and microcrystalline structure are sorted out in accordance with gasification type and FS particle size.The reasons for the formation of the special structural properties of FS-RC are analyzed,and their influence on the flotation separation and high-value utilization of FS-RC is summarized.Separation methods based on the pore structural characterist-ics of FS-RC,such as ultrasonic pretreatment-pore-blocking flotation and pore breaking-flocculation flotation,are proposed to be the key development technologies for improving FS-RC recovery in the future.The design of low-cost,low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future.The high-value utilization of FS should be based on the physicochemical structural proper-ties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to es-tablish an environmentally friendly utilization method.This review is of great theoretical importance for the comprehensive understand-ing of the unique structural properties of FS-RC,the breakthrough of the technological bottleneck in the efficient flotation separation of FS,and the expansion of the field of the high value-added utilization of FS-RC.
基金financially supported by the National Key R&D Program Projects of China (No.2021YFB3202402)National Natural Science Foundation of China (No.62173321)。
文摘Rapid online analysis of liquid slag is essential for optimizing the quality and energy efficiency of steel production. To investigate the key factors that affect the online measurement of refined slag using laser-induced breakdown spectroscopy(LIBS), this study examined the effects of slag composition and temperature on the intensity and stability of the LIBS spectra. The experimental temperature was controlled at three levels: 1350℃, 1400℃, and 1450℃. The results showed that slag composition and temperature significantly affected the intensity and stability of the LIBS spectra. Increasing the Fe content and temperature in the slag reduces its viscosity, resulting in an enhanced intensity and stability of the LIBS spectra. Additionally, 42 refined slag samples were quantitatively analyzed for Fe, Si, Ca, Mg, Al, and Mn at 1350℃, 1400℃, and 1450℃.The normalized full spectrum combined with partial least squares(PLS) quantification modeling was used, using the Ca Ⅱ 317.91 nm spectral line as an internal standard. The results show that using the internal standard normalization method can significantly reduce the influence of spectral fluctuations. Meanwhile, a temperature of 1450℃ has been found to yield superior results compared to both 1350℃ and 1400℃, and it is advantageous to conduct a quantitative analysis of the slag when it is in a “water-like” state with low viscosity.
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supported by the National Natural Science Foundation of China(21878082).
文摘The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO ratios prepared on the basis of the range of oxide contents of Zhundong coal ash were investigated in this study. The results show that with the MgO/CaO ratio increase, the initial crystallization temperature increases, and the main temperature range of crystallization ratio growth moves to higher temperature range gradually which causes Tp25(Tp25is the temperature corresponding to the viscosity of 25 Pa·s)to increase. Mg-rich crystals are formed preferentially than Ca-rich crystals when adding the same amount of MgO and CaO during cooling. The effective slagging operating temperature range decrease from 217 ℃ for the slag with a 0:4 MgO/CaO ratio to 44 ℃ for the slag with a 4:0 MgO/CaO ratio with the MgO/CaO ratio increase. The slags with 2:2 and 1:3 MgO/CaO ratios show similar effective slagging operating temperature range, Tp25and the temperature corresponding to the viscosity of 2 Pa·s.However, compared with the slag with a 1:3 MgO/CaO ratio, the crystallization ratio and rate of slag with a 2:2 MgO/CaO ratio are lower within lower temperature range(1300–1200 ℃), causing its lower critical viscosity temperature and wider actual operating temperature range. Of the five slags, the widest effective slagging operating temperature range and the lowest Tp25of the slag with a 0:4 MgO/CaO ratio due to its low crystallization ratio, and wider actual operating temperature range of the slag with a 2:2 MgO/CaO ratio make the two slags suitable for slag discharge of EFB gasifier.
基金financially supported by the National Nature Science Foundation of China(Nos.U1860206,51725402)the Science and Technology Program of Hebei,China(Nos.20311006D,20591001D)。
文摘The dissolution kinetics of Al_(2)O_(3) in CaO-Al_(2)O_(3) SiOslags was studied using a high-temperature confocal scanning laser microscope at 1773 to 1873 K.The results show that the controlling step during the Al_(2)O_(3) dissolution was the diffusionin molten slag.It was found that the dissolution curves of Al_(2)O_(3) particles were hardly agreed with the traditional boundary layer diffusion model with the increase of the CaO/Al_(2)O_(3) ratio of slag.A modified diffusion equation considering slag viscosity was developed to study the dissolution mechanism of Al_(2)O_(3) in slag.Diffusion coefficients of Al_(2)O_(3) in slag were calculated as 2.8×10to 4.1×10m~2/s at the temperature of 1773-1873 K.The dissolution rate of Al_(2)O_(3) increased with higher temperature,CaO/Al_(2)O_(3),and particle size.A new model was shown to be v_(Al_(2)O_(3))=0.16×r_(0)^(1.58)×x^(3.52)×(T-T_(mp))^(1.11)to predict the dissolution rate and the total dissolution time of Al_(2)O_(3) inclusions with various sizes,where vAl_(2)O_(3) is the dissolution rate of Al_(2)O_(3) in volume,μm^(3)/s;x is the value of CaO/Al_(2)O_(3) mass ratio;R_(0) is the initial radius of Al_(2)O_(3),μm;T is the temperature,K;T_(mp) is the melting point of slag,K.
基金financially supported by the Guangzhou Basic and Applied Basic Research Project,China(No.202102020623)the Guangdong Academy of Sciences’Project of Science and Technology Development,China(No.2020 GDASYL-20200103101)+1 种基金the National Key Research and Development Program of China(No.2020YFC1908902)the Natural Science Foundation of Guangdong Province Project,China(No.2020A1515010729)。
文摘The metallurgical properties of the CaO–SiO_(2)–Al_(2)O_(3)–4.6wt%Mg O–Fe_(2)O_(3)slag system,formed by the co-treatment process of spent automotive catalyst(SAC)and copper-bearing electroplating sludge(CBES),were studied systematically in this paper.The slag structure,melting temperature,and viscous characteristics were investigated by Fourier transform infrared(FTIR)spectroscopy,Raman spectroscopy,Fact Sage calculation,and viscosity measurements.Experimental results show that the increase of Fe_(2)O_(3)content(3.8wt%–16.6wt%),the mass ratio of CaO/SiO_(2)(m(CaO)/m(SiO_(2)),0.5–1.3),and the mass ratio of SiO_(2)/Al_(2)O_(3)(m(SiO_(2))/m(Al_(2)O_(3)),1.0–5.0)can promote the depolymerization of silicate network,and the presence of a large amount of Fe_(2)O_(3)in form of tetrahedral and octahedral units ensures the charge compensation of Al^(3+)ions and makes Al_(2)O_(3)only behave as an acid oxide.Thermodynamic calculation and viscosity measurements show that with the increase of Fe_(2)O_(3)content,m(Ca O)/m(SiO_(2)),and m(SiO_(2))/m(Al_(2)O_(3)),the depolymerization of silicate network structure and low-melting-point phase transformation first occur within the slag,leading to the decrease in melting point and viscosity of the slag,while further increase causes the formation of high-melting-point phase and a resultant re-increase in viscosity and melting point.Based on experimental analysis,the preferred slag composition with low polymerization degree,viscosity,and melting point is as follows:Fe_(2)O_(3)content of 10.2wt%–13.4wt%,m(CaO)/m(SiO_(2))of 0.7–0.9 and m(SiO_(2))/m(Al_(2)O_(3))of 3.0–4.0.This work provides a theoretical support for slag design in co-smelting process of SAC and CBES.
基金Funded by the Key Public Welfare Special Project of Henan Province(No.201300311000)the Major Technical Innovation Project in Hubei Province of China(No.2020BED025)。
文摘Cement,phosphorous slag(PS),and steel slag(SS)were used to prepare low-carbon cementitious materials,and triisopropanolamine(TIPA)was used to improve the mechanical properties by controlling the hydration process.The experimental results show that,by using 0.06%TIPA,the compressive strength of cement containing 60%PS or 60%SS could be enhanced by 12%or 18%at 28 d.The presence of TIPA significantly affected the hydration process of PS and SS in cement.In the early stage,TIPA accelerated the dissolution of Al in PS,and the formation of carboaluminate hydrate was facilitated,which could induce the hydration;TIPA promoted the dissolution of Fe in SS,and the formation of Fe-monocarbonate,which was precipitated on the surface of SS,resulting in the postponement of hydration,especially for the high SS content.In the later stage,under the continuous solubilization effect of TIPA,the hydration of PS and SS could refine the pore structure.It was noted that compared with portland cement,the carbon emissions of cement-PS-TIPA and cement-SS-TIPA was reduced by 52%and 49%,respectively.
基金Funding Statement:This work was supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Energy shortage and the emission of greenhouse gases have become a global problem of urgent concern.Therefore,there is an urgent need to develop a low carbon building material.Geopolymers have become a hot topic due to their environmental sustainability and the feasibility of immobilizing industrial waste.In this paper,steel slag(SS)fines were investigated as auxiliary materials of blast furnace slag(BFS)based geopolymer.The hydration heat properties,flowability,compressive strength,sorptivity coefficient,X-ray diffraction(XRD),and scanning electron microscopy(SEM)of the geopolymer pastes were determined.The results showed that the incorporation of SS weakened the reactivity of the BFS-based geopolymer paste and improved the flow values of the paste.The compressive strength of the geopolymer with 20%SS content reached 117 MPa at 28 d.The geopolymer specimens with high compressive strength showed a low sorptivity coefficient.The microscopic results showed that the addition of the appropriate amount of SS reduced the cracks,improved the density of the geopolymer,and produced a geopolymer composite with excellent mechanical properties.
基金National Natural Science Foundation of China(Grant No.52078051)Fundamental Research Funds for the Central Universities(Grant No.310821163502)+1 种基金Technology Innovation Project of Shandong Department of Industry and Information(Grant No.Lugongxinji 2020-8)the Transportation Department of Shandong Province(Grant No.Lujiaokeji 2017-28).
文摘Steel slag is characterized by high strength,good wear resistance and micro-expansion.This study aims at exploring the potential of steel slag in cement stabilized aggregates,mainly including mechanical properties,shrinkage and compensation mechanisms.For this purpose,the compressive strength and compressive resilient modulus of cement stabilized aggregates with different steel slag contents(CSMS)were initially investigated.Subsequently,the effects of steel slag and cement on dry shrinkage,temperature shrinkage,and total shrinkage were analyzed through a series of shrinkage test designs.Additionally,in combination with X-ray diffraction(XRD)and Scanning electron microscope(SEM),the characteristic peaks and microscopic images of cement,steel slag and cement-steel slag at different hydration ages were analyzed to identify the chemical substances causing the expansion volume of steel slag and reveal the compensation mechanism of CSMS.The results show that the introduction of 20%steel slag improved the mechanical properties of CSMS by 16.7%,reduced dry shrinkage by 21%,increased temperature shrinkage by 5.8%and reduced its total shrinkage by 19.2%.Compared with the hydration reaction of cement alone,the composite hydration reaction of steel slag with cement does not produce new hydrates.Furthermore,it is noteworthy that the volume expansion of the f-CaO hydration reaction in steel slag can compensate for the volume shrinkage of cement-stabilized macadam.This research can provide a solid theoretical basis for the application and promotion of steel slag in cement-stabilized macadam and reduce the possibility of shrinkage cracking.
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.
