With the rapid industrialization and urbanization,the demand for air quality management is more and more urgent.High temperature dust filtration is one important environmental management technology.Porous ceramics are...With the rapid industrialization and urbanization,the demand for air quality management is more and more urgent.High temperature dust filtration is one important environmental management technology.Porous ceramics are used as filter materials in the field of high-temperature dust filtration because of their unique advantages such as high filtration efficiency,as well as high temperature stability,particle loss resistance,corrosion resistance and durability.This paper mainly introduced several common preparation techniques of porous ceramics,including the traditional organic foam impregnation method,foaming method,in-situ combustion method,pore-forming method and other new methods such as the template method,gel injection molding method,freeze-drying method,multi-component co-precipitation method and hydrogel method.The principle,advantages and disadvantages of these preparation technologies and their research status were described.The application of these technologies in the field of high temperature dust filtration was briefly reviewed.Finally,the application prospect of the porous ceramics in the field of high temperature dust filtration was prospected.展开更多
Arsenic is selectively extracted from high-arsenic dust by NaOH-Na2S alkaline leaching process. In the leaching arsenic process, the effects of alkali-to-dust ratio, sodium sulfide addition, leaching temperature, leac...Arsenic is selectively extracted from high-arsenic dust by NaOH-Na2S alkaline leaching process. In the leaching arsenic process, the effects of alkali-to-dust ratio, sodium sulfide addition, leaching temperature, leaching time and liquid-to-solid ratio on metals leaching efficiencies were investigated. The results show that the arsenic can be effectively separated from other metals under the optimum conditions of alkali/dust mass ratio of 0.5, sodium sulfide addition of 0.25 g/g, leaching temperature of 90 ℃, leaching time of 2 h, and liquid-to-solid ratio of 5：1 （mL/g）. Under these conditions, the average leaching efficiencies of arsenic, antimony, lead, tin and zinc are 92.75%, 11.68%, 0.31%, 29.75% and 36.85%, respectively. The NaOH-Na2S alkaline leaching process provides a simple and highly efficient way to remove arsenic from high-arsenic dust, leaving residue as a suitable lead resource.展开更多
To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensive...To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensively studied in theory by virtue of related theories of hydromechanics and aerosol.According to actual measurements of flow coefficients and atomization angles of X-type swirl nozzle,computational formula was derived for atomized particle sizes of such a nozzle in conjunction with relevant empirical equation. Moreover, a mathematical model for applying high pressure atomization to dust removal in underground coal mine was also established to deduce theoretical computation formula of fractional efficiency. Then, Matlab was adopted to portray the relation curve between fractional efficiency and influence factors. In addition, a theoretical formula was also set up for removal efficiency of respirable dust and total coal dust based on dust size and frequency distribution equations. In the end,impacts of dust characteristic parameters on various dust removal efficiencies were analyzed.展开更多
To research the possibility of steel-making dust as a kind of mineral filler in asphalt mixture, two steel-making dusts and one ordinary mineral filler were adopted. The specific density, specific surface area, finene...To research the possibility of steel-making dust as a kind of mineral filler in asphalt mixture, two steel-making dusts and one ordinary mineral filler were adopted. The specific density, specific surface area, fineness modulus and mineralogy component of the dusts were tested. Scanning electron microscopy(SEM) was carried out to research the microstructure of the dusts; dynamic shear rheological(DSR) test and time sweep test were used to research the high temperature and fatigue performance of asphalt mortars containing steel-making dust. The experimental results indicate that, compared with ordinary mineral filler, steel-making dusts have more active ingredients, difference surface characteristics and micro-structure. Furthermore, the high temperature and fatigue performance of steel-making dusts corresponding asphalt mortars are superior to those of reference group. Therefore, the steel-making dust would be an alternative to the ordinary mineral filler to improve the performance of asphalt mortars and reduce the harm of the dusts to the environment at the same time.展开更多
A dust collector is an important equipment in a thermal power plant,and reasonable selection of a dust collector is important for environmental protection in the power plant. Huaneng Xining Power Plant is located at a...A dust collector is an important equipment in a thermal power plant,and reasonable selection of a dust collector is important for environmental protection in the power plant. Huaneng Xining Power Plant is located at an elevation of 2 360 m. Based on the characteristics of the high altitude area and their special requirements for dust collectors,the selection of dust collectors for the thermal power unit in the high altitude area was studied,and then two types of dust collectors( a rotary electrode electrostatic precipitator and electric-bag composite precipitator) for the thermal power unit were compared from the aspects of technological and economical feasibility. Finally,a proposal to select a suitable dust collector for the thermal power plant was put forward.展开更多
Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigate...Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron（DRI） by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery（εFe） by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε（Fe） in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.展开更多
Massive amounts of limestone waste are produced by the stone processing industry worldwide. Generally, it is believed that 60% to 70% of the stone is wasted in processing in the form of fragments, powder and slurry ou...Massive amounts of limestone waste are produced by the stone processing industry worldwide. Generally, it is believed that 60% to 70% of the stone is wasted in processing in the form of fragments, powder and slurry out of which around 30% is in the form of fine powder [1]. This waste has no beneficial usage and poses environmental hazards. Use of this waste product in the construction industry can largely reduce the amount of waste to be disposed off by the local municipalities in addition to reducing large burden on the environment. Some basic research on use of limestone dust as cement/ concrete filler?has?been carried out in the recent past but high strength/ high performance concretes have not been investigated yet [2] [3]. The concrete industry is among the largest consumer of raw materials worldwide and has been investigated for use of various types of waste materials like crushed brick, rice husk and straw ash as either aggregates for concrete or as partial cement substitutes. Use of limestone dust as filler material in concrete can consume a huge amount of this waste material which has to be disposed off otherwise, creating large burden on the environment. This experimental study aimed at evaluating the properties of high performance concretes made from Portland cement, natural aggregates and sand. Limestone dust was added by replacing sand in the percentages of 10% and 20%. Wide ranging investigations covering most aspects of mechanical behavior and permeability were carried out for various mixes for compressive strengths of 60?N/mm2, 80?N/mm2 and 100?N/mm2. Compressive strengths of concrete specimen with partial replacement of sand with 10% and 20% limestone dust as filler material for 60?N/mm2, 80N/mm2 and 100?N/mm2 were observed to be higher by about 4% to 12% than the control specimen. Flexural strengths were also observed to be higher by 12%?-?13%. Higher elastic moduli and reduced permeability were observed along with better sulphate and acid resistance. Better strengths and improved durability of such high-performance concretes make it a more acceptable material for major construction projects.展开更多
This research evaluated the suitability of stone dust in the design and production of High Perfor-mance Concrete (HPC). HPC mix was designed, tested, costed and a comparison of concrete classes used in the market (Cla...This research evaluated the suitability of stone dust in the design and production of High Perfor-mance Concrete (HPC). HPC mix was designed, tested, costed and a comparison of concrete classes used in the market (Class 25, 30 and 35) done using Cost Benefit Analysis (CBA). The cost benefit was analyzed using Internal Rate of Return (IRR) and Net Present Value (NPV). Laboratory tests established the properties concrete obtained from the design mix. Compressive strength, slump, and modulus of elasticity were tested and analyzed. Structural analysis using BS 8110 was done for a 10 storey office building to establish the structural member sizes. Members obtained from concrete Classes 25, 30, 35 and the new compressive strengths from HPC (Class 80) were obtained and compared. Analysis was done for structural members’ sizes and area freed as a result of de-signing with HPC as well as the steel reinforcement used. To justify the initial cost of HPC if ado- pted, the Cost Benefit Analysis (CBA) was used to estimate increased costs versus income resulting from increased let table space created. The minimum class of concrete used in design was limited to Class 25 N/mm2. The research shows that it is possible to manufacture high strength concrete using locally available stone dust. The stone dust sampled from Mlolongo quarries achieved a characteristic strength of 86.7 N/mm2 at a water cement ratio of 0.32. With the results structural analysis of a 10 storey office structures with columns spaced at 8 meters center to center was de-signed using the four classes and results compared. There was a reduction of columns from 1.2 m wide to 0.65 m wide (over 45%) when concrete class changes from Class 25 to Class 80 creating over 3% of the total space area per floor. Cost benefit analysis using Net Present Value (NPV) and Internal Rate of Return (IRR) presented business case for the use of HPC. With Class 80, the IRR was at 3% and NPV being 8% of the total initial investment. The steel reinforcement increased by 8.64% using Class 30, 11.68% using Class 35 and reduced by 8.37% at Class 80. Further analysis needs to be done to understand the trend of steel reinforcement keeping all the member sizes the same. In this study the member sizes were optimized based on the steel reinforcement and serviceability. This paper provides useful information to design Engineers and Architects and inform future design of multi storey structures.展开更多
文摘With the rapid industrialization and urbanization,the demand for air quality management is more and more urgent.High temperature dust filtration is one important environmental management technology.Porous ceramics are used as filter materials in the field of high-temperature dust filtration because of their unique advantages such as high filtration efficiency,as well as high temperature stability,particle loss resistance,corrosion resistance and durability.This paper mainly introduced several common preparation techniques of porous ceramics,including the traditional organic foam impregnation method,foaming method,in-situ combustion method,pore-forming method and other new methods such as the template method,gel injection molding method,freeze-drying method,multi-component co-precipitation method and hydrogel method.The principle,advantages and disadvantages of these preparation technologies and their research status were described.The application of these technologies in the field of high temperature dust filtration was briefly reviewed.Finally,the application prospect of the porous ceramics in the field of high temperature dust filtration was prospected.
基金Project(2012AA04022)supported by the Scientific Research and Technology Development Project of Guangxi,China
文摘Arsenic is selectively extracted from high-arsenic dust by NaOH-Na2S alkaline leaching process. In the leaching arsenic process, the effects of alkali-to-dust ratio, sodium sulfide addition, leaching temperature, leaching time and liquid-to-solid ratio on metals leaching efficiencies were investigated. The results show that the arsenic can be effectively separated from other metals under the optimum conditions of alkali/dust mass ratio of 0.5, sodium sulfide addition of 0.25 g/g, leaching temperature of 90 ℃, leaching time of 2 h, and liquid-to-solid ratio of 5：1 （mL/g）. Under these conditions, the average leaching efficiencies of arsenic, antimony, lead, tin and zinc are 92.75%, 11.68%, 0.31%, 29.75% and 36.85%, respectively. The NaOH-Na2S alkaline leaching process provides a simple and highly efficient way to remove arsenic from high-arsenic dust, leaving residue as a suitable lead resource.
基金Financial provided by the National Natural Science Foundation of China (Nos. 51574123 and U1361118)the China Postdoctoral Science Foundation (No. 2015M 582118)
文摘To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensively studied in theory by virtue of related theories of hydromechanics and aerosol.According to actual measurements of flow coefficients and atomization angles of X-type swirl nozzle,computational formula was derived for atomized particle sizes of such a nozzle in conjunction with relevant empirical equation. Moreover, a mathematical model for applying high pressure atomization to dust removal in underground coal mine was also established to deduce theoretical computation formula of fractional efficiency. Then, Matlab was adopted to portray the relation curve between fractional efficiency and influence factors. In addition, a theoretical formula was also set up for removal efficiency of respirable dust and total coal dust based on dust size and frequency distribution equations. In the end,impacts of dust characteristic parameters on various dust removal efficiencies were analyzed.
基金Funded by the National Natural Science Foundation of China(51778482)
文摘To research the possibility of steel-making dust as a kind of mineral filler in asphalt mixture, two steel-making dusts and one ordinary mineral filler were adopted. The specific density, specific surface area, fineness modulus and mineralogy component of the dusts were tested. Scanning electron microscopy(SEM) was carried out to research the microstructure of the dusts; dynamic shear rheological(DSR) test and time sweep test were used to research the high temperature and fatigue performance of asphalt mortars containing steel-making dust. The experimental results indicate that, compared with ordinary mineral filler, steel-making dusts have more active ingredients, difference surface characteristics and micro-structure. Furthermore, the high temperature and fatigue performance of steel-making dusts corresponding asphalt mortars are superior to those of reference group. Therefore, the steel-making dust would be an alternative to the ordinary mineral filler to improve the performance of asphalt mortars and reduce the harm of the dusts to the environment at the same time.
文摘A dust collector is an important equipment in a thermal power plant,and reasonable selection of a dust collector is important for environmental protection in the power plant. Huaneng Xining Power Plant is located at an elevation of 2 360 m. Based on the characteristics of the high altitude area and their special requirements for dust collectors,the selection of dust collectors for the thermal power unit in the high altitude area was studied,and then two types of dust collectors( a rotary electrode electrostatic precipitator and electric-bag composite precipitator) for the thermal power unit were compared from the aspects of technological and economical feasibility. Finally,a proposal to select a suitable dust collector for the thermal power plant was put forward.
基金Funded by National Natural Science Foundation of China(No.51134002)
文摘Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron（DRI） by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery（εFe） by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε（Fe） in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.
文摘Massive amounts of limestone waste are produced by the stone processing industry worldwide. Generally, it is believed that 60% to 70% of the stone is wasted in processing in the form of fragments, powder and slurry out of which around 30% is in the form of fine powder [1]. This waste has no beneficial usage and poses environmental hazards. Use of this waste product in the construction industry can largely reduce the amount of waste to be disposed off by the local municipalities in addition to reducing large burden on the environment. Some basic research on use of limestone dust as cement/ concrete filler?has?been carried out in the recent past but high strength/ high performance concretes have not been investigated yet [2] [3]. The concrete industry is among the largest consumer of raw materials worldwide and has been investigated for use of various types of waste materials like crushed brick, rice husk and straw ash as either aggregates for concrete or as partial cement substitutes. Use of limestone dust as filler material in concrete can consume a huge amount of this waste material which has to be disposed off otherwise, creating large burden on the environment. This experimental study aimed at evaluating the properties of high performance concretes made from Portland cement, natural aggregates and sand. Limestone dust was added by replacing sand in the percentages of 10% and 20%. Wide ranging investigations covering most aspects of mechanical behavior and permeability were carried out for various mixes for compressive strengths of 60?N/mm2, 80?N/mm2 and 100?N/mm2. Compressive strengths of concrete specimen with partial replacement of sand with 10% and 20% limestone dust as filler material for 60?N/mm2, 80N/mm2 and 100?N/mm2 were observed to be higher by about 4% to 12% than the control specimen. Flexural strengths were also observed to be higher by 12%?-?13%. Higher elastic moduli and reduced permeability were observed along with better sulphate and acid resistance. Better strengths and improved durability of such high-performance concretes make it a more acceptable material for major construction projects.
文摘This research evaluated the suitability of stone dust in the design and production of High Perfor-mance Concrete (HPC). HPC mix was designed, tested, costed and a comparison of concrete classes used in the market (Class 25, 30 and 35) done using Cost Benefit Analysis (CBA). The cost benefit was analyzed using Internal Rate of Return (IRR) and Net Present Value (NPV). Laboratory tests established the properties concrete obtained from the design mix. Compressive strength, slump, and modulus of elasticity were tested and analyzed. Structural analysis using BS 8110 was done for a 10 storey office building to establish the structural member sizes. Members obtained from concrete Classes 25, 30, 35 and the new compressive strengths from HPC (Class 80) were obtained and compared. Analysis was done for structural members’ sizes and area freed as a result of de-signing with HPC as well as the steel reinforcement used. To justify the initial cost of HPC if ado- pted, the Cost Benefit Analysis (CBA) was used to estimate increased costs versus income resulting from increased let table space created. The minimum class of concrete used in design was limited to Class 25 N/mm2. The research shows that it is possible to manufacture high strength concrete using locally available stone dust. The stone dust sampled from Mlolongo quarries achieved a characteristic strength of 86.7 N/mm2 at a water cement ratio of 0.32. With the results structural analysis of a 10 storey office structures with columns spaced at 8 meters center to center was de-signed using the four classes and results compared. There was a reduction of columns from 1.2 m wide to 0.65 m wide (over 45%) when concrete class changes from Class 25 to Class 80 creating over 3% of the total space area per floor. Cost benefit analysis using Net Present Value (NPV) and Internal Rate of Return (IRR) presented business case for the use of HPC. With Class 80, the IRR was at 3% and NPV being 8% of the total initial investment. The steel reinforcement increased by 8.64% using Class 30, 11.68% using Class 35 and reduced by 8.37% at Class 80. Further analysis needs to be done to understand the trend of steel reinforcement keeping all the member sizes the same. In this study the member sizes were optimized based on the steel reinforcement and serviceability. This paper provides useful information to design Engineers and Architects and inform future design of multi storey structures.
