SisN4 and SiC phase stability via gas phase reactions among SiO, CO/CO2 and N2 has been calculated based on thermochemical equilibrium. The influences of carbon activity (αC), and the partial pressure of SiO (PSiO), ...SisN4 and SiC phase stability via gas phase reactions among SiO, CO/CO2 and N2 has been calculated based on thermochemical equilibrium. The influences of carbon activity (αC), and the partial pressure of SiO (PSiO), CO (PCO) and N2 (PN2) on the Si3N4-SiC stability have been studied and the related phase diagrams have been constructed. Result shows that the lowering αC and PCO/PSiO ratio and the increasing PN2 greatly elevate the Si3N4-SiC equilibrium temperature. Some previously observed experimental results related to Si3N4 and SiC formation at different temperature from the gas phase reactions have been discussed and some guides for sintering and synthesis Of the Si3N4 materials have been proposed展开更多
The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals（Pb, Zn, Cr, Cu, Mn and Ni） during sludge incineration were investigated using a simulated laborato...The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals（Pb, Zn, Cr, Cu, Mn and Ni） during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the Fact Sage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb 〉 Zn 〉 Cr 〉 Cu 〉 Mn 〉 Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni.With increasing combustion temperature, the presence of organic-Cl（PVC） and inorganic-Cl（NaCl） improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However,the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed Pb SiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb（ClO4）2and Pb Cl2O4.展开更多
Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth'...Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth's surface environments.The results reveal that,in comparison to aqueous H_4SiO_4,heavy Si isotopes will be significantly enriched in secondary silicate minerals.On the contrary,quadra-coordinated organosilicon complexes are enriched in light silicon isotope relative to the solution.The extent of ^(28)Si-enrichment in hyper-coordinated organosilicon complexes was found to be the largest.In addition,the large kinetic isotope effect associated with the polymerization of monosilicic acid and dimer was calculated,and the results support the previous statement that highly ^(28)Sienrichment in the formation of amorphous quartz precursor contributes to the discrepancy between theoretical calculations and field observations.With the equilibrium Si isotope fractionation factors provided here,Si isotope distributions in many of Earth's surface systems can be explained.For example,the change of bulk soil δ^(30)Si can be predicted as a concave pattern with respect to the weathering degree,with the minimum value where allophane completely dissolves and the total amount of sesquioxides and poorly crystalline minerals reaches their maximum.When,under equilibrium conditions,the well-crystallized clays start to precipitate from the pore solutions,the bulk soil δ^(30)Si will increase again and reach a constant value.Similarly,the precipitation of crystalline smectite and the dissolution of poorly crystalline kaolinite may explain the δ^(30)Si variations in the ground water profile.The equilibrium Si isotope fractionations among the quadracoordinated organosilicon complexes and the H_4SiO_4solution may also shed light on the Si isotope distributions in the Si-accumulating plants.展开更多
Throught fusion of the mechanism modeling and the neural networks modeling,a compo- nent content soft-sensor,which is composed of the equilibrium calculation model for multi-component rare earth extraction and the err...Throught fusion of the mechanism modeling and the neural networks modeling,a compo- nent content soft-sensor,which is composed of the equilibrium calculation model for multi-component rare earth extraction and the error compensation model of fuzzy system,is proposed to solve the prob- lem that the component content in countercurrent rare-earth extraction process is hardly measured on-line.An industry experiment in the extraction Y process by HAB using this hybrid soft-sensor proves its effectiveness.展开更多
Nano-sized aluminum(Nano-Al)powders hold promise in enhancing the total energy of explosives and the metal acceleration ability at the same time.However,the near-detonation zone effects of reaction between Nano-Al wit...Nano-sized aluminum(Nano-Al)powders hold promise in enhancing the total energy of explosives and the metal acceleration ability at the same time.However,the near-detonation zone effects of reaction between Nano-Al with detonation products remain unclear.In this study,the overall reaction process of 170 nm Al with RDX explosive and its effect on detonation characteristics,detonation reaction zone,and the metal acceleration ability were comprehensively investigated through a variety of experiments such as the detonation velocity test,detonation pressure test,explosive/window interface velocity test and confined plate push test using high-resolution laser interferometry.Lithium fluoride(LiF),which has an inert behavior during the explosion,was used as a control to compare the contribution of the reaction of aluminum.A thermochemical approach that took into account the reactivity of aluminum and ensuing detonation products was adopted to calculate the additional energy release by afterburn.Combining the numerical simulations based on the calculated afterburn energy and experimental results,the parameters in the detonation equation of state describing the Nano-Al reaction characteristics were calibrated.This study found that when the 170 nm Al content is from 0%to 15%,every 5%increase of aluminum resulted in about a 1.3%decrease in detonation velocity.Manganin pressure gauge measurement showed no significant enhancement in detonation pressure.The detonation reaction time and reaction zone length of RDX/Al/wax/80/15/5 explosive is 64 ns and 0.47 mm,which is respectively 14%and 8%higher than that of RDX/wax/95/5 explosive(57 ns and 0.39 mm).Explosive/window interface velocity curves show that 170 nm Al mainly reacted with the RDX detonation products after the detonation front.For the recording time of about 10 ms throughout the plate push test duration,the maximum plate velocity and plate acceleration time accelerated by RDX/Al/wax/80/15/5 explosive is 12%and 2.9 ms higher than that of RDX/LiF/wax/80/15/5,respectively,indicating that the aluminum reaction energy significantly increased the metal acceleration time and ability of the explosive.Numerical simulations with JWLM explosive equation of state show that when the detonation products expanded to 2 times the initial volume,over 80%of the aluminum had reacted,implying very high reactivity.These results are significant in attaining a clear understanding of the reaction mechanism of Nano-Al in the development of aluminized explosives.展开更多
In consideration of the online measurement of the component content in rare earth countercurrent extraction separation process, the soft sensor method based on hybrid modeling was proposed to measure the rare earth co...In consideration of the online measurement of the component content in rare earth countercurrent extraction separation process, the soft sensor method based on hybrid modeling was proposed to measure the rare earth component content. The hybrid models were composed of the extraction equilibrium calculation model and the Radial Basis Function (RBF) Neural Network (NN) error compensation model; the parameters of compensation model were optimized by the hierarchical genetic algorithms (HGA). In addition, application experiment research of this proposed method was carried out in the rare earth separation production process of a corporation. The result shows that this method is effective and can realize online measurement for the component content of rare earth in the countercurrent extraction.展开更多
Combustion of biomass or coal is known to yield aerosols and condensed alkali minerals that affect boiler heat transfer performance.In this work,alkali behavior in the pressurized oxyfuel co-combustion of coal and bio...Combustion of biomass or coal is known to yield aerosols and condensed alkali minerals that affect boiler heat transfer performance.In this work,alkali behavior in the pressurized oxyfuel co-combustion of coal and biomass is predicted by thermodynamic and chemical kinetic calculations.Existence of solid minerals is evaluated by X-ray diffraction(XRD)analysis of ashes from pressure thermogravimetric combustion.Results indicate that a rise in pressure affects solid alkali minerals negligibly,but increases their contents in the liquid phase and decreases them in the gas phase,especially below 900℃.Thus,less KCl will condense on the boiler heat transfer surfaces leading to reduced corrosion.Increasing the blend ratio of biomass to coal will raise the content of potassium-based minerals but reduce the sodium-based ones.The alkali-associated slagging in the boiler can be minimized by the synergistic effect of co-combustion of sulphur-rich coal and potassium-rich biomass,forming stable solid K2SO4 at typical fluidized bed combustion temperatures.Kinetics modelling based on reaction mechanisms shows that oxidation of SO2 to SO3 plays a major role in K2SO4 formation but that the contribution of this oxidation decreases with increase in pressure.展开更多
Improper handling of heavy metal-containing solid waste poses significant environmental risks.However,developing an effective heavy metal elimination method is still a challenge.Our study introduces a novel method of ...Improper handling of heavy metal-containing solid waste poses significant environmental risks.However,developing an effective heavy metal elimination method is still a challenge.Our study introduces a novel method of staggered chlorination roasting.The volatilization and removal effects of two chlorinating agents,NH_(4)Cl and CaCl_(2),on typical key heavy metals,Zn and Cu,were investigated.Compared with the use of a single chlorinating agent,this method,which uses NH_(4)Cl for low-temperature decomposition and CaCl_(2)for high-temperature reactions,significantly extends the chlorination reaction time,overtly enhancing the chlorination volatilization effect.This study elucidated the influence of the chlorinating agent content,temperature,and time on the elimination of heavy metal oxides.The results demonstrated that when the two chlorinating agents were added at a ratio of 2:3,roasting at 1100℃for 60 min resulted in the highest volatilization rates of Zn(99.9%)and Cu(98.7%).Thermodynamic equilibrium and equilibrium phase composition calculations were conducted to explore the effects of the chlorinating agents and mineral components(SiO_(2),Al_(2)O_(3),Fe_(2)O_(3),and CaO)on chlorination roasting.In the staggered chlorination mode,the chlorine-containing gases generated effectively mitigate the influence of mineral components,thereby suppressing interactions between oxidized heavy metals and mineral constituents.This suppression enhances the chlorination and volatilization of heavy metals.This study proposes a novel staggered chlorination roasting method based on composite chlorinating agents,offering a new approach for the collaborative and efficient removal of multiple heavy metals from solid waste.展开更多
In this paper,refuse derived fuel(RDF)and bituminous coal were co-fired to investigate the particulate matter(PM)yields and the interaction between the inherit minerals in a lab-scale drop tube furnace(DTF).The PM1-10...In this paper,refuse derived fuel(RDF)and bituminous coal were co-fired to investigate the particulate matter(PM)yields and the interaction between the inherit minerals in a lab-scale drop tube furnace(DTF).The PM1-10 yields during the co-firing of coal and RDF dramatically decreased by 16.29%~28.5%of the combustion of coal alone.In addition,methane auxiliary combustion inhibited the PM_(1) yields by 7.95%at air atmosphere.The Si-rich minerals in coal interreacted with the organic alkali(earth)metals in RDF,massively generating sticky particles with high liquid amount of K-Al-Si and Ca-Al-Si,promoting the transformation of fine grains into coarser mode.Moreover,it was proved that both methane auxiliary combustion and co-firing can reduce the emission of fine particles.The additional heat accelerated the burn of the char at the early stage of combustion,providing adequate time for the interaction between the inorganic species.Through thermodynamic equilibrium calculations of 1500~3000 fly ash grains,it was found that co-firing increased the formation of sticky particles by 64.8%~70.3%,resulting in a significant enhancement in capturing fine particles and Na,K vapor.Therefore,the co-firing of coal with RDF offers a promising approach to realize the harmless and resourceful treatment of municipal solid waste(MSW),and inhibit land resource losses caused by landfill.展开更多
文摘SisN4 and SiC phase stability via gas phase reactions among SiO, CO/CO2 and N2 has been calculated based on thermochemical equilibrium. The influences of carbon activity (αC), and the partial pressure of SiO (PSiO), CO (PCO) and N2 (PN2) on the Si3N4-SiC stability have been studied and the related phase diagrams have been constructed. Result shows that the lowering αC and PCO/PSiO ratio and the increasing PN2 greatly elevate the Si3N4-SiC equilibrium temperature. Some previously observed experimental results related to Si3N4 and SiC formation at different temperature from the gas phase reactions have been discussed and some guides for sintering and synthesis Of the Si3N4 materials have been proposed
基金spported by the National Natural Science Foundation of China (No. 5130813)the Scientific and Technological Planning Project of Guangzhou, China (No. 201510010033)+1 种基金the natural Science Foundation of Guangdong Province (No. S2013040013022)the Excellent Youth Development Project of Universities in Guangdong Province (No. 2015-261532111)
文摘The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals（Pb, Zn, Cr, Cu, Mn and Ni） during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the Fact Sage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb 〉 Zn 〉 Cr 〉 Cu 〉 Mn 〉 Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni.With increasing combustion temperature, the presence of organic-Cl（PVC） and inorganic-Cl（NaCl） improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However,the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed Pb SiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb（ClO4）2and Pb Cl2O4.
基金the funding support from the 973 Program(2014CB440904)CAS/SAFEA International Partnership Program for Creative Research Teams(Intraplate Mineralization Research Team,KZZD-EW-TZ-20)Chinese NSF projects(41173023,41225012,41490635,41530210)
文摘Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth's surface environments.The results reveal that,in comparison to aqueous H_4SiO_4,heavy Si isotopes will be significantly enriched in secondary silicate minerals.On the contrary,quadra-coordinated organosilicon complexes are enriched in light silicon isotope relative to the solution.The extent of ^(28)Si-enrichment in hyper-coordinated organosilicon complexes was found to be the largest.In addition,the large kinetic isotope effect associated with the polymerization of monosilicic acid and dimer was calculated,and the results support the previous statement that highly ^(28)Sienrichment in the formation of amorphous quartz precursor contributes to the discrepancy between theoretical calculations and field observations.With the equilibrium Si isotope fractionation factors provided here,Si isotope distributions in many of Earth's surface systems can be explained.For example,the change of bulk soil δ^(30)Si can be predicted as a concave pattern with respect to the weathering degree,with the minimum value where allophane completely dissolves and the total amount of sesquioxides and poorly crystalline minerals reaches their maximum.When,under equilibrium conditions,the well-crystallized clays start to precipitate from the pore solutions,the bulk soil δ^(30)Si will increase again and reach a constant value.Similarly,the precipitation of crystalline smectite and the dissolution of poorly crystalline kaolinite may explain the δ^(30)Si variations in the ground water profile.The equilibrium Si isotope fractionations among the quadracoordinated organosilicon complexes and the H_4SiO_4solution may also shed light on the Si isotope distributions in the Si-accumulating plants.
基金Supported by National Natural Science Foundation of P.R.China(50474020,60534010,60504006)
文摘Throught fusion of the mechanism modeling and the neural networks modeling,a compo- nent content soft-sensor,which is composed of the equilibrium calculation model for multi-component rare earth extraction and the error compensation model of fuzzy system,is proposed to solve the prob- lem that the component content in countercurrent rare-earth extraction process is hardly measured on-line.An industry experiment in the extraction Y process by HAB using this hybrid soft-sensor proves its effectiveness.
基金The authors would like to acknowledge National Natural Science Foundation of China(Grant No.11832006)Open Project of State Key Laboratory of Explosion Science and Technology in Beijing Institute of Technology(Grant No.KFJJ20-04 M)to provide fund for conducting experiments.
文摘Nano-sized aluminum(Nano-Al)powders hold promise in enhancing the total energy of explosives and the metal acceleration ability at the same time.However,the near-detonation zone effects of reaction between Nano-Al with detonation products remain unclear.In this study,the overall reaction process of 170 nm Al with RDX explosive and its effect on detonation characteristics,detonation reaction zone,and the metal acceleration ability were comprehensively investigated through a variety of experiments such as the detonation velocity test,detonation pressure test,explosive/window interface velocity test and confined plate push test using high-resolution laser interferometry.Lithium fluoride(LiF),which has an inert behavior during the explosion,was used as a control to compare the contribution of the reaction of aluminum.A thermochemical approach that took into account the reactivity of aluminum and ensuing detonation products was adopted to calculate the additional energy release by afterburn.Combining the numerical simulations based on the calculated afterburn energy and experimental results,the parameters in the detonation equation of state describing the Nano-Al reaction characteristics were calibrated.This study found that when the 170 nm Al content is from 0%to 15%,every 5%increase of aluminum resulted in about a 1.3%decrease in detonation velocity.Manganin pressure gauge measurement showed no significant enhancement in detonation pressure.The detonation reaction time and reaction zone length of RDX/Al/wax/80/15/5 explosive is 64 ns and 0.47 mm,which is respectively 14%and 8%higher than that of RDX/wax/95/5 explosive(57 ns and 0.39 mm).Explosive/window interface velocity curves show that 170 nm Al mainly reacted with the RDX detonation products after the detonation front.For the recording time of about 10 ms throughout the plate push test duration,the maximum plate velocity and plate acceleration time accelerated by RDX/Al/wax/80/15/5 explosive is 12%and 2.9 ms higher than that of RDX/LiF/wax/80/15/5,respectively,indicating that the aluminum reaction energy significantly increased the metal acceleration time and ability of the explosive.Numerical simulations with JWLM explosive equation of state show that when the detonation products expanded to 2 times the initial volume,over 80%of the aluminum had reacted,implying very high reactivity.These results are significant in attaining a clear understanding of the reaction mechanism of Nano-Al in the development of aluminized explosives.
文摘In consideration of the online measurement of the component content in rare earth countercurrent extraction separation process, the soft sensor method based on hybrid modeling was proposed to measure the rare earth component content. The hybrid models were composed of the extraction equilibrium calculation model and the Radial Basis Function (RBF) Neural Network (NN) error compensation model; the parameters of compensation model were optimized by the hierarchical genetic algorithms (HGA). In addition, application experiment research of this proposed method was carried out in the rare earth separation production process of a corporation. The result shows that this method is effective and can realize online measurement for the component content of rare earth in the countercurrent extraction.
基金Project supported by the National Science Foundation Cooperation of China and USA(NSFC-NSF)(No.51661125012)Project of the State Key Laboratory of Clean Energy Utilization,Zhejiang University,China。
文摘Combustion of biomass or coal is known to yield aerosols and condensed alkali minerals that affect boiler heat transfer performance.In this work,alkali behavior in the pressurized oxyfuel co-combustion of coal and biomass is predicted by thermodynamic and chemical kinetic calculations.Existence of solid minerals is evaluated by X-ray diffraction(XRD)analysis of ashes from pressure thermogravimetric combustion.Results indicate that a rise in pressure affects solid alkali minerals negligibly,but increases their contents in the liquid phase and decreases them in the gas phase,especially below 900℃.Thus,less KCl will condense on the boiler heat transfer surfaces leading to reduced corrosion.Increasing the blend ratio of biomass to coal will raise the content of potassium-based minerals but reduce the sodium-based ones.The alkali-associated slagging in the boiler can be minimized by the synergistic effect of co-combustion of sulphur-rich coal and potassium-rich biomass,forming stable solid K2SO4 at typical fluidized bed combustion temperatures.Kinetics modelling based on reaction mechanisms shows that oxidation of SO2 to SO3 plays a major role in K2SO4 formation but that the contribution of this oxidation decreases with increase in pressure.
基金supported by the projects of Key Program of the National Natural Science Foundation of China(Grant No.52236008)the Natural Science Foundation of Zhejiang Province(Nos.LY23E060006 and LZ23E060004).
文摘Improper handling of heavy metal-containing solid waste poses significant environmental risks.However,developing an effective heavy metal elimination method is still a challenge.Our study introduces a novel method of staggered chlorination roasting.The volatilization and removal effects of two chlorinating agents,NH_(4)Cl and CaCl_(2),on typical key heavy metals,Zn and Cu,were investigated.Compared with the use of a single chlorinating agent,this method,which uses NH_(4)Cl for low-temperature decomposition and CaCl_(2)for high-temperature reactions,significantly extends the chlorination reaction time,overtly enhancing the chlorination volatilization effect.This study elucidated the influence of the chlorinating agent content,temperature,and time on the elimination of heavy metal oxides.The results demonstrated that when the two chlorinating agents were added at a ratio of 2:3,roasting at 1100℃for 60 min resulted in the highest volatilization rates of Zn(99.9%)and Cu(98.7%).Thermodynamic equilibrium and equilibrium phase composition calculations were conducted to explore the effects of the chlorinating agents and mineral components(SiO_(2),Al_(2)O_(3),Fe_(2)O_(3),and CaO)on chlorination roasting.In the staggered chlorination mode,the chlorine-containing gases generated effectively mitigate the influence of mineral components,thereby suppressing interactions between oxidized heavy metals and mineral constituents.This suppression enhances the chlorination and volatilization of heavy metals.This study proposes a novel staggered chlorination roasting method based on composite chlorinating agents,offering a new approach for the collaborative and efficient removal of multiple heavy metals from solid waste.
基金supported by Major Program of National Natural Science Foundation of China(5217060506)Shanghai Pujiang Program(22PJ1405900).
文摘In this paper,refuse derived fuel(RDF)and bituminous coal were co-fired to investigate the particulate matter(PM)yields and the interaction between the inherit minerals in a lab-scale drop tube furnace(DTF).The PM1-10 yields during the co-firing of coal and RDF dramatically decreased by 16.29%~28.5%of the combustion of coal alone.In addition,methane auxiliary combustion inhibited the PM_(1) yields by 7.95%at air atmosphere.The Si-rich minerals in coal interreacted with the organic alkali(earth)metals in RDF,massively generating sticky particles with high liquid amount of K-Al-Si and Ca-Al-Si,promoting the transformation of fine grains into coarser mode.Moreover,it was proved that both methane auxiliary combustion and co-firing can reduce the emission of fine particles.The additional heat accelerated the burn of the char at the early stage of combustion,providing adequate time for the interaction between the inorganic species.Through thermodynamic equilibrium calculations of 1500~3000 fly ash grains,it was found that co-firing increased the formation of sticky particles by 64.8%~70.3%,resulting in a significant enhancement in capturing fine particles and Na,K vapor.Therefore,the co-firing of coal with RDF offers a promising approach to realize the harmless and resourceful treatment of municipal solid waste(MSW),and inhibit land resource losses caused by landfill.
