The residue from a second-stage dry sinter plant off-gas cleaning process contains both the fine dust from the sinter plant and the sorbent used. Recycling of the material that is usually handled by landfills to the s...The residue from a second-stage dry sinter plant off-gas cleaning process contains both the fine dust from the sinter plant and the sorbent used. Recycling of the material that is usually handled by landfills to the sinter plant feed is not possible because of its chloride con- tent. Leaching of the chlorides allow the recycling of remaining solids. The saline leachate produced contains some heavy metals and must be treated before it is discharged into the sea. In laboratory experiments, leaching tests with the subsequent treatment of the leachate were con- ducted. After the process was optimized, all heavy-metal concentrations were below the permissible values. The optimum treatment condi- tions for heavy-metal precipitation were observed to be the filtration of the suspended solids followed by the dosing of liquid with lime milk (pH 10) and the subsequent precipitation using sodium sulfide.展开更多
Based on the thermodynamic calculation, the mole ratio of CaO to SiO 2, temperature and A/S of bauxite have a profound influence on the mole ratio of 2CaO·SiO 2 to CaO·SiO 2 in sinter. CaO·SiO 2 and β ...Based on the thermodynamic calculation, the mole ratio of CaO to SiO 2, temperature and A/S of bauxite have a profound influence on the mole ratio of 2CaO·SiO 2 to CaO·SiO 2 in sinter. CaO·SiO 2 and β -2CaO·SiO 2 appear stable in caustic solution but unstable in soda solution, and CaO·SiO 2 is more stable than β -2CaO·SiO 2 under the same leaching condition. Compared with the conventional sinter, the rate of alumina extraction of the new sinter is large and the secondary reaction is restricted in the leaching, which might be mainly due to the more content of CaO·SiO 2 in sinter and better stability of CaO·SiO 2 in leaching.展开更多
A1203-Si composite specimens were prepared using fused corundum, ultra-fine α-A1203 and Si powder as starting materials and resin as binder. Effects of sintering atmospheres on properties, phase composition and micro...A1203-Si composite specimens were prepared using fused corundum, ultra-fine α-A1203 and Si powder as starting materials and resin as binder. Effects of sintering atmospheres on properties, phase composition and microstructure of specimens after firing at 1 500 ℃ were investigated. The results show that: ( 1 ) after .firing in oxidizing or weak oxidizing atmosphere, there is some Si in the specimens and some glass phases containing mullite form on specimen surface, the density and strength at room temperature are relatively high, but hot modulus of rupture and thermal shock resistance are relatively poor; (2) after firing in, weak reducing or reducing atmosphere, Si reacts completely with CO or N2forming whisk-phere, Si reacts completely with CO or N2forming whisk-er-like SiC, granular Si2N20 or 0'-SiAION, and the er-like SiC, granular Si2N20 or O'-SiMON, and the thermo-mechanical properties of specimens are enhanced;(3) after firing in nitrogen atmosphere, Si reacts completely with N2, CO or G forming wbisker-like SiC and columnar β-SiA10N crystals, the hot modulus of rupture and thermal shock resistance of specimens are enhanced noticeably.展开更多
Three different kinds of corundum aggregates-tabular sintered alumina, dense sintered alumina, and fused dense corundum-were introduced into the silica fume .free or silica fume containing Al2O3 -SiC - C iron runner c...Three different kinds of corundum aggregates-tabular sintered alumina, dense sintered alumina, and fused dense corundum-were introduced into the silica fume .free or silica fume containing Al2O3 -SiC - C iron runner castables to investigate their influences on the flow ability, linear change on heating, bulk density, apparent porosity, cold strength, hot modulus of rupture, therm, al shock resistance, slag resistance, oxidation resistance as well as wear resistance of Al2O3 - SiC - C iron runner castables. The results show that ( 1 ) compared with the specimens with fused dense corundum, the specimens with dense sintered alumina have equivalent installation property, slag resistance and oxidation resistance, equivalent or even higher cold modulus of rupture, cold crushing strength and hot modulus of rupture, exhibiting better thermal shock resistance and cold wear resistance ; (2) adopting bimodal alumina micropowder LISAL22RABL as well as water reducers ZX2 and ZD2 can well reduce the water requirement of silica fume free castables, solving the problem of deteriorated flow ability resulted from the lack of silica fume; since the lack of silica fume avoids the formation of low melting point liquid, the hot modulus of rupture and the thermal shock resistance of the silica fume free castables are both better than those of the silica fume containing castables ; (3) the density of the castable specimens with dense sintered alumina is 4% -6% lower than that of the castable specimens with Jhsed dense corundum so the refractories consumption of one iron runner reduces by 5% by using the tastable with dense sintered alumina, which obviously reduces the cost of refractories.展开更多
Poly(1,1,2,2- tetrahydroperfluorodecyl acrylate) (poly (TA-N)) was synthesized in laboratory. The resulting morphology of rapid expansion of supercritical solution (RESS) sprays of poly(TA - N) was investigated. At ap...Poly(1,1,2,2- tetrahydroperfluorodecyl acrylate) (poly (TA-N)) was synthesized in laboratory. The resulting morphology of rapid expansion of supercritical solution (RESS) sprays of poly(TA - N) was investigated. At apre - expansion temperature of 45℃), amorphous polymer was formed. At temperature around 60 ℃ to 80 ℃ , fibers were formed. Increase of temperature increasesparticle size slightly. At temperature of 105℃ , most of particles are spheres. The RESS is an attractive process. To apply the polymers desired for coating applications in an organic solvent - free process that is economically viable , and it will have implications for pollution prevention during polymer film展开更多
The article deals the structure of the CaO -Al2O3 - TiO2 -SiO2 system as a basis for obtaining advanced ce- ramics with a complex of high-operational characteris- tics. As a result o['investigations the phase charctc...The article deals the structure of the CaO -Al2O3 - TiO2 -SiO2 system as a basis for obtaining advanced ce- ramics with a complex of high-operational characteris- tics. As a result o['investigations the phase charctcteristics are represented trod the graph of the relationship of the elementaory tetrahedra has been plotted. The most techno- logical system area ,for the production of heat resistant advanced ceramics has been determined. The batches for producing heat and chemical resistant dense advanced ceramics made of natural, technical and technogenic raw materials have been developed.展开更多
Synthesis of a m m oniu m alu min u m carbonate hydroxide ( A A C H) w as investigated usinga m m oniu m alu min u m sulfate and a m moniu m hydro carbonate as the starting m aterials . Itw as found that A A C Hca...Synthesis of a m m oniu m alu min u m carbonate hydroxide ( A A C H) w as investigated usinga m m oniu m alu min u m sulfate and a m moniu m hydro carbonate as the starting m aterials . Itw as found that A A C Hcan be synthesized by adding a m m oniu m alu m inu m sulfate solution torapidly stirred a m moniu m hydro - carbonate solution at a tem perature of 30 ℃. A A C Hcantransfor m to α Al2 O3 co m pletely by calcining at 1100 ℃ for 1 hour , and the obtained po w ders , with a particle size of 100 n m , can be sintered to 98 99 % relative density at 1500 ℃for 2 hours .展开更多
Cd-bearing solid wastes are considered to be a serious threat to the environment,and effective strategies for their treatment are urgently needed.Ceramic sintering has been considered as a promising method for efficie...Cd-bearing solid wastes are considered to be a serious threat to the environment,and effective strategies for their treatment are urgently needed.Ceramic sintering has been considered as a promising method for efficiently incorporating heavy metal-containing solid wastes into various ceramic products.Mineral-rich dredged river sediment,especially Al and Si-containing oxides,can be treated as alternative ceramic precursors rather than being disposed of as solid wastes.To examine the feasibility of using waste sediment for Cd stabilization and the phase transition mechanisms,this study conducted a sintering scheme for the mixtures of CdO and dredged river sediment with different(Al+Si):Cd mole ratios.Detailed investigations have been performed on phases transformation,Cd incorporation mechanisms,elemental distribution,and leaching behaviors of the sintered products.Results showed that Cd incorporation and transformation in the sintered products were influenced by the mole ratio of(Al+Si):Cd.Among the high-Cd series((Al+Si):Cd=6:1),CdSiO_(3),Cd_(2)SiO_(4),CdAl_(2)(SiO_(4))_(2) and Cd_(2)Al_(2)Si_(2)O_(9) were predominant Cd-containing product phases,while Cd2Al2Si2O9 was replaced by CdAl_(4)O_(7) when the mole ratio of(Al+Si):Cd was 12:1(low-Cd series).Cd was efficiently stabilized in both reaction series after being sintered at≥900℃,with<5%leached ratio even after a prolonged leaching time,indicating excellent long-term Cd stabilization.This study demonstrated that both Cd-containing phases and the amorphous Al-/Si-containing matrices all played critical roles in Cd stabilization.A promising strategy can be proposed to simultaneously reuse the solid waste as ceramic precursors and stabilize heavy metals in the ceramic products.展开更多
The bastnaesite used in hydrometallurgy usually contains 7%-11% fluorine,and the conversion of fluorine into high-value products is the key to achieving green production of rare earths and improving the comprehensive ...The bastnaesite used in hydrometallurgy usually contains 7%-11% fluorine,and the conversion of fluorine into high-value products is the key to achieving green production of rare earths and improving the comprehensive utilization of bastnaesite.In order to recover fluorine from bastnaesite in the form of KBF4,the mechanism of F^(-)conversion to BF^(4-)in sulphuric acid leaching solution of roasted bastnaesite was studied by using Eh-pH diagram and simulation experiment.It shows that the formation of BF^(4-)is affected by pH in the absence of rare earths.BF^(4-)is hydrolyzed to BF3 OH-and F-when the pH is greater than 3.9,and part of F-exists as HF^(2-)when pH is lower than 2.In the presence of La^(3+),the formation of BF^(4-)is mainly affected by LaF_(3) when pH is greater than 0,and in the case that the pH is lower than 2,it is mainly affected by HF^(2-).When Ce4+is present in solution,CeF_(2)^(2+) can exist stably in sulphuric acid solution.Bringing down the pH can reduce the stability of CeF_(2)^(2+) and increase the BF^(4-)conversion rate.Based on these results,KBF4 was prepared in the alkaline solution of bastnaesite,and the conversion of BF^(4-)is 84.31%.This provides a theoretical basis for the recovery of fluorine from bastnaesite in the form of KBF_(4).展开更多
基金financially supported by the research program of K1-METfinancially supported within the Austrian competence centre program COMET by the Federal Ministry of Economy,Family and Youth+3 种基金by the Federal Ministry for Transport,Innovation and Technologyby the federal states of Upper Austria,Styria,and Tyrolby the Styrian Business Promotion Agencyby the Tiroler Zukunftsstiftung
文摘The residue from a second-stage dry sinter plant off-gas cleaning process contains both the fine dust from the sinter plant and the sorbent used. Recycling of the material that is usually handled by landfills to the sinter plant feed is not possible because of its chloride con- tent. Leaching of the chlorides allow the recycling of remaining solids. The saline leachate produced contains some heavy metals and must be treated before it is discharged into the sea. In laboratory experiments, leaching tests with the subsequent treatment of the leachate were con- ducted. After the process was optimized, all heavy-metal concentrations were below the permissible values. The optimum treatment condi- tions for heavy-metal precipitation were observed to be the filtration of the suspended solids followed by the dosing of liquid with lime milk (pH 10) and the subsequent precipitation using sodium sulfide.
文摘Based on the thermodynamic calculation, the mole ratio of CaO to SiO 2, temperature and A/S of bauxite have a profound influence on the mole ratio of 2CaO·SiO 2 to CaO·SiO 2 in sinter. CaO·SiO 2 and β -2CaO·SiO 2 appear stable in caustic solution but unstable in soda solution, and CaO·SiO 2 is more stable than β -2CaO·SiO 2 under the same leaching condition. Compared with the conventional sinter, the rate of alumina extraction of the new sinter is large and the secondary reaction is restricted in the leaching, which might be mainly due to the more content of CaO·SiO 2 in sinter and better stability of CaO·SiO 2 in leaching.
基金financially supported by Henan Scientific and Technological Research Projects (112102210095 )Science Fund for Distinguished Young Scholars of Henan Province ( No.124100510019) the Education Department of Henan Province Foundation (14A430030)
文摘A1203-Si composite specimens were prepared using fused corundum, ultra-fine α-A1203 and Si powder as starting materials and resin as binder. Effects of sintering atmospheres on properties, phase composition and microstructure of specimens after firing at 1 500 ℃ were investigated. The results show that: ( 1 ) after .firing in oxidizing or weak oxidizing atmosphere, there is some Si in the specimens and some glass phases containing mullite form on specimen surface, the density and strength at room temperature are relatively high, but hot modulus of rupture and thermal shock resistance are relatively poor; (2) after firing in, weak reducing or reducing atmosphere, Si reacts completely with CO or N2forming whisk-phere, Si reacts completely with CO or N2forming whisk-er-like SiC, granular Si2N20 or 0'-SiAION, and the er-like SiC, granular Si2N20 or O'-SiMON, and the thermo-mechanical properties of specimens are enhanced;(3) after firing in nitrogen atmosphere, Si reacts completely with N2, CO or G forming wbisker-like SiC and columnar β-SiA10N crystals, the hot modulus of rupture and thermal shock resistance of specimens are enhanced noticeably.
文摘Three different kinds of corundum aggregates-tabular sintered alumina, dense sintered alumina, and fused dense corundum-were introduced into the silica fume .free or silica fume containing Al2O3 -SiC - C iron runner castables to investigate their influences on the flow ability, linear change on heating, bulk density, apparent porosity, cold strength, hot modulus of rupture, therm, al shock resistance, slag resistance, oxidation resistance as well as wear resistance of Al2O3 - SiC - C iron runner castables. The results show that ( 1 ) compared with the specimens with fused dense corundum, the specimens with dense sintered alumina have equivalent installation property, slag resistance and oxidation resistance, equivalent or even higher cold modulus of rupture, cold crushing strength and hot modulus of rupture, exhibiting better thermal shock resistance and cold wear resistance ; (2) adopting bimodal alumina micropowder LISAL22RABL as well as water reducers ZX2 and ZD2 can well reduce the water requirement of silica fume free castables, solving the problem of deteriorated flow ability resulted from the lack of silica fume; since the lack of silica fume avoids the formation of low melting point liquid, the hot modulus of rupture and the thermal shock resistance of the silica fume free castables are both better than those of the silica fume containing castables ; (3) the density of the castable specimens with dense sintered alumina is 4% -6% lower than that of the castable specimens with Jhsed dense corundum so the refractories consumption of one iron runner reduces by 5% by using the tastable with dense sintered alumina, which obviously reduces the cost of refractories.
文摘Poly(1,1,2,2- tetrahydroperfluorodecyl acrylate) (poly (TA-N)) was synthesized in laboratory. The resulting morphology of rapid expansion of supercritical solution (RESS) sprays of poly(TA - N) was investigated. At apre - expansion temperature of 45℃), amorphous polymer was formed. At temperature around 60 ℃ to 80 ℃ , fibers were formed. Increase of temperature increasesparticle size slightly. At temperature of 105℃ , most of particles are spheres. The RESS is an attractive process. To apply the polymers desired for coating applications in an organic solvent - free process that is economically viable , and it will have implications for pollution prevention during polymer film
文摘The article deals the structure of the CaO -Al2O3 - TiO2 -SiO2 system as a basis for obtaining advanced ce- ramics with a complex of high-operational characteris- tics. As a result o['investigations the phase charctcteristics are represented trod the graph of the relationship of the elementaory tetrahedra has been plotted. The most techno- logical system area ,for the production of heat resistant advanced ceramics has been determined. The batches for producing heat and chemical resistant dense advanced ceramics made of natural, technical and technogenic raw materials have been developed.
文摘Synthesis of a m m oniu m alu min u m carbonate hydroxide ( A A C H) w as investigated usinga m m oniu m alu min u m sulfate and a m moniu m hydro carbonate as the starting m aterials . Itw as found that A A C Hcan be synthesized by adding a m m oniu m alu m inu m sulfate solution torapidly stirred a m moniu m hydro - carbonate solution at a tem perature of 30 ℃. A A C Hcantransfor m to α Al2 O3 co m pletely by calcining at 1100 ℃ for 1 hour , and the obtained po w ders , with a particle size of 100 n m , can be sintered to 98 99 % relative density at 1500 ℃for 2 hours .
基金financially supported by the National Key R&D Program of China(No.2018YFC1902904)the National Natural Science Foundation of China(Nos.21707063 and 41977329)+2 种基金the Research Grants Council of Hong Kong(China)(Project T21-771/16R)Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control(China)(No.2017B030301012)The authors are sincerely grateful for the assistance of SUSTech Core Research Facilities(China).
文摘Cd-bearing solid wastes are considered to be a serious threat to the environment,and effective strategies for their treatment are urgently needed.Ceramic sintering has been considered as a promising method for efficiently incorporating heavy metal-containing solid wastes into various ceramic products.Mineral-rich dredged river sediment,especially Al and Si-containing oxides,can be treated as alternative ceramic precursors rather than being disposed of as solid wastes.To examine the feasibility of using waste sediment for Cd stabilization and the phase transition mechanisms,this study conducted a sintering scheme for the mixtures of CdO and dredged river sediment with different(Al+Si):Cd mole ratios.Detailed investigations have been performed on phases transformation,Cd incorporation mechanisms,elemental distribution,and leaching behaviors of the sintered products.Results showed that Cd incorporation and transformation in the sintered products were influenced by the mole ratio of(Al+Si):Cd.Among the high-Cd series((Al+Si):Cd=6:1),CdSiO_(3),Cd_(2)SiO_(4),CdAl_(2)(SiO_(4))_(2) and Cd_(2)Al_(2)Si_(2)O_(9) were predominant Cd-containing product phases,while Cd2Al2Si2O9 was replaced by CdAl_(4)O_(7) when the mole ratio of(Al+Si):Cd was 12:1(low-Cd series).Cd was efficiently stabilized in both reaction series after being sintered at≥900℃,with<5%leached ratio even after a prolonged leaching time,indicating excellent long-term Cd stabilization.This study demonstrated that both Cd-containing phases and the amorphous Al-/Si-containing matrices all played critical roles in Cd stabilization.A promising strategy can be proposed to simultaneously reuse the solid waste as ceramic precursors and stabilize heavy metals in the ceramic products.
基金the National Natural Science Foundation of China(51176122,41641010)the Science and Technology Support Project of Sichuan Province(2016SZ0071,20GJHZ0042)。
文摘The bastnaesite used in hydrometallurgy usually contains 7%-11% fluorine,and the conversion of fluorine into high-value products is the key to achieving green production of rare earths and improving the comprehensive utilization of bastnaesite.In order to recover fluorine from bastnaesite in the form of KBF4,the mechanism of F^(-)conversion to BF^(4-)in sulphuric acid leaching solution of roasted bastnaesite was studied by using Eh-pH diagram and simulation experiment.It shows that the formation of BF^(4-)is affected by pH in the absence of rare earths.BF^(4-)is hydrolyzed to BF3 OH-and F-when the pH is greater than 3.9,and part of F-exists as HF^(2-)when pH is lower than 2.In the presence of La^(3+),the formation of BF^(4-)is mainly affected by LaF_(3) when pH is greater than 0,and in the case that the pH is lower than 2,it is mainly affected by HF^(2-).When Ce4+is present in solution,CeF_(2)^(2+) can exist stably in sulphuric acid solution.Bringing down the pH can reduce the stability of CeF_(2)^(2+) and increase the BF^(4-)conversion rate.Based on these results,KBF4 was prepared in the alkaline solution of bastnaesite,and the conversion of BF^(4-)is 84.31%.This provides a theoretical basis for the recovery of fluorine from bastnaesite in the form of KBF_(4).