The deactivation cause of lead-zinc double oxide for synthesis of diphenyl carbonate （DPC） by transesterification of dimethyl carbonate （DMC） with phenol has been investigated. X-ray diffraction （XRD）, X-ray pho...The deactivation cause of lead-zinc double oxide for synthesis of diphenyl carbonate （DPC） by transesterification of dimethyl carbonate （DMC） with phenol has been investigated. X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, infrared spectroscopy （IR）, thermogravimetry analysis （TG）, atomic absorption spectroscopy and elementary analysis are employed for the catalyst characterization. The results show that, the formation of Pb4O（OC6H5）6 through the reaction of phenol and lead species in the catalyst leads to the crystal phase change of active component and serious leaching of lead, which is the cause of the catalyst deactivation. In addition, the composition of the leached lead is ascertained to be a mixture of Pb4O（OC6H5）6 and PbO with the weight percentage of 62.7% and 37.3%, respectively.展开更多
The thermal dissolved sulfuration technology is brought forward and performed based on the characteristic of low grade lead-zinc oxide ore in lanpin. Using sulfur as the sulphidizing agent in the experiment, the oxide...The thermal dissolved sulfuration technology is brought forward and performed based on the characteristic of low grade lead-zinc oxide ore in lanpin. Using sulfur as the sulphidizing agent in the experiment, the oxides in the sandstone and ignimbrite are changed into sulfides. The disproportionation reaction of sulfur in a solution is confirmed as 4S＋3H2O=2S^2-＋S2O3^2--＋6H^＋. The dynamics process is studied and the first-order reaction rate equation -1n（1-a）=ktt is obtained. The effects of the reactive products, stirring speed, dosage of sulfuration agent, value of pH and sulphidizing temperature on the sulfuration of oxide ore are investigated. The results indicate that the reactive apparent activation energy is 100.8 kJ/mol and the sulfuration ratio of lead-zinc oxide ore reaches 60% under the conditions of pH 5.9-7.5, the sulfuration temperature of 130 ℃, sulfuration time of 180 min and the stirring speed of 800 r/min.展开更多
X-ray powder diffraction,scanning electron microscopy,energy dispersive spectroscopy,thermogravimetry,differential scanning calorimetry,and mass spectrometry have been used to study the products of nickel-containing p...X-ray powder diffraction,scanning electron microscopy,energy dispersive spectroscopy,thermogravimetry,differential scanning calorimetry,and mass spectrometry have been used to study the products of nickel-containing pyrrhotite tailings oxidation by oxygen in the air.The kinetic triplets of oxidation,namely,activation energy(E_(a)),pre-exponential factor(A),and reaction model(f(α))being a function of the conversion degree(α),were adjusted by regression analysis.In case of a two-stage process representation,the first step proceeds under autocatalysis control and ends atα=0.42.The kinetic triplet in the first step is E_(a)=262.2 kJ/mol,lg A=14.53 s^(−1),and f(α)=(1-α)^(4.11)(1+1.51×10^(-4)α).For the second step,the process is controlled by the two-dimensional diffusion of the reactants in the layer of oxidation products.The kinetic triplet in the second step isЕa=215.0 kJ/mol,lg A=10.28 s^(−1),and f(α)=(-ln(1-α))^(-1).The obtained empirical formulae for the rate of pyrrhotite tailings oxidation reliably describe the macro-mechanism of the process and can be used to design automatization systems for roast-ing these materials.展开更多
Mining activities have created great wealth, but they have also discharged large quantities of tailings. As an important source of heavy metal contamination, sulfide tailings are usually disposed of in open-air impoun...Mining activities have created great wealth, but they have also discharged large quantities of tailings. As an important source of heavy metal contamination, sulfide tailings are usually disposed of in open-air impoundments and thus are exposed to microbial oxidation. Microbial activities greatly enhance sulfide oxidation and result in the release of heavy metals and the precipitation of iron (oxy) hydroxides and sulfates. These secondary minerals in turn influence the mobility of dissolved metals and play important roles in the natural attenuation of heavy metals. Elucidating the microbe–mineral interactions in tailings will improve our understanding of the environmental consequence of mining activities.展开更多
Iron oxides and lead-zinc deposits in host rocks located in ten drainage basins in the coastal plain of the Red Sea,Egypt,have been subjected to important mining activities.The drainage basins were analyzed to estimat...Iron oxides and lead-zinc deposits in host rocks located in ten drainage basins in the coastal plain of the Red Sea,Egypt,have been subjected to important mining activities.The drainage basins were analyzed to estimate the transportations of these minerals. Fourteen soil samples and fifteen plant samples were collected from sites located in the basin and also in neighboring area and chemically analyzed.In展开更多
Using variety of modern testing methods, the processing mineralogical characteristics for a lead and zinc oxide ore in Sichuan were studied systematically. The chemical analysis result shows that the lead and zinc oxi...Using variety of modern testing methods, the processing mineralogical characteristics for a lead and zinc oxide ore in Sichuan were studied systematically. The chemical analysis result shows that the lead and zinc oxide content exceeding the minimum industrial grade and iron ore, total iron content reaches a minimum industrial grade and associated with gold and silver; The mineralogical analysis result shows that lead and zinc mineral composition and configuration are very complexity. The zinc minerals and zinciferous minerals are sphalerite, hemimorphite, Smithsonite, Hydrozincite, zinc chlorite, limonite, zinc dolomite and zincocalcite; lead minerals and plumbiferous minerals are mainly galena, cerussite, anglesite, limonite and Coronadite; The minerals disseminated grain size are very fine and mineral dissemination characteristics are very complex ; expected theoretical recoveries for lead and zinc were 72% and 67% respectively. The results of this study provide basic data and theoretical basis for ore dressing.展开更多
Diesel engines have been widely used due to their high thermal efficiency, good environmental adaptability, wide power adjustment range, convenient maintenance and long service life. However, the application of diesel...Diesel engines have been widely used due to their high thermal efficiency, good environmental adaptability, wide power adjustment range, convenient maintenance and long service life. However, the application of diesel engines is also facing a serious problem;that is, the emission of nitrogen oxides and particulate matter is serious. For marine diesel engine emission requirements, MARPOL Convention Annex VI imposes strict restrictions on the emission of atmospheric pollutants. The limit emission of nitrogen oxides in the Tier III emission standards mandated by IMO is 3.4 g/kWh. Therefore, in order to meet the requirements of international conventions and countries and regions, it is necessary to control the emissions of diesel engines. The NOx in the exhaust gas is mostly a thermal type of nitrogen oxide which is produced under high temperature and high pressure conditions formed during compression and combustion strokes. The diesel engine relies on the compression energy of the mixture to ignite, and the good injection atomization effect is not achieved. The distribution of the detonation point is not uniform, and local high temperature points are generated in some areas, which increases the NOx formation. The main means of reducing NOx emissions are organic internal control and post-treatment. However, the use of internal control technology to reduce the internal temperature of the machine will deteriorate the fuel combustion conditions, so that the fuel cannot be completely burned, and the emissions of incomplete combustion products such as PM and CO increase. It is difficult to achieve NOx reduction by simply relying on the internal control technology, so it is necessary to use post-processing technology. The combined use of different emission reduction technologies is also a hot topic in emissions control research. The post-treatment methods for NOx emission reduction include direct catalytic decomposition, selective non-catalytic reduction, selective catalytic reduction, lean-burn adsorption catalytic reduction, and low-temperature plasma assisted technology. The current research and application schemes in the industry are SCR selectivity. Catalytic reduction and LNT lean combustion adsorption reduction. In this paper, the partial replacement of Ce by La is carried out to modify the Ce/Zr composite oxide. The mass fraction of La2O3 in the prepared La/Ce/Zr composite oxide was 5%, and the physicochemical properties of La/Ce/Zr composite oxide powder were analyzed by ICP, OSC, SEM and TPR techniques. The experiment found that: 1) La can refine the grain and inhibit the grain growth, so that the powder obtains a higher specific surface area and a smaller particle size distribution. 2) The addition of La reduces the sintering of cerium-zirconium and improves the heat aging resistance of the catalyst under the inhibition of high temperature. 3) After doping La, it enhances the migration of surface lattice oxygen and enhances the oxygen storage capacity;the addition of La enhances the NO adsorption capacity of cerium-zirconium and improves the catalytic activity of the catalyst. The light-off temperature and the highest activity temperature of PM decrease, and the reduction rate of No is 19.2%.展开更多
The aim of this study was to investigate the synthesis of iron oxide pigments from IOT. The sample of IOT was obtained through mining activity of the Quadrilátero Ferrífero in the state of Minas Gerais, Braz...The aim of this study was to investigate the synthesis of iron oxide pigments from IOT. The sample of IOT was obtained through mining activity of the Quadrilátero Ferrífero in the state of Minas Gerais, Brazil. The procedure was carried out by hot acid leaching with hydrochloric acid (HCl) which allowed the recovery of about 95% of the iron in a liquor. The iron-based pigments—red (IBP_R), black (IBP_B), and yellow (IBP_Y)—were synthetised from the liquor by selective precipitation, crystallisation, and thermal procedures. The pigments were characterised by particle size distribution, mineral and chemical compositions, as well as colourimetric properties. The process of synthesis was successful and the procedure was shown to maximise the utilisation of mineral resources and minimise the environmental, social, and economic impacts associated with IOT disposal.展开更多
氧化石墨烯(Graphene Oxide,GO)可以改善水泥基材料力学性能的良好特性可用来改性固废(铁尾矿砂、再生粗骨料)混凝土。研究对再生粗骨料取代率、铁尾矿砂取代率和GO掺量3个因素设计了正交试验。引入考虑固废利用率的权重指标对GO改性固...氧化石墨烯(Graphene Oxide,GO)可以改善水泥基材料力学性能的良好特性可用来改性固废(铁尾矿砂、再生粗骨料)混凝土。研究对再生粗骨料取代率、铁尾矿砂取代率和GO掺量3个因素设计了正交试验。引入考虑固废利用率的权重指标对GO改性固废混凝土的强度指标进行修正并得出加权评价指标,通过极差分析得到GO改性固废混凝土的较佳配合比,研究较佳配合比下GO改性固废混凝土的抗压强度与抗折强度、坍落度与吸水率和微观形貌。结果显示:当再生粗骨料取代率为100%、铁尾矿砂取代率为50%、GO质量分数为0.05%时,为GO改性固废混凝土的较佳配合比,对GO改性固废混凝土的评价指标影响显著性从大到小依次为再生粗骨料取代率、氧化石墨烯掺量、铁尾矿砂取代率。通过扫描电子显微镜(Scanning Electron Microscope,SEM)微观形貌分析发现,GO能优化水化产物堆叠形态,在尺度上细化水化产物,能够填充改性固废混凝土的孔隙结构,有效改善其致密度;较优配合比下的GO改性固废混凝土的力学性能优于普通混凝土的力学性能,验证了GO改性固废混凝土替代普通混凝土的可行性。展开更多
基金This work was supported by National Natural Science Foundation of China (No.20636030 No.20176008)Natural Science Foundation of Tianjin(No.07 JCZDJC00100)
文摘The deactivation cause of lead-zinc double oxide for synthesis of diphenyl carbonate （DPC） by transesterification of dimethyl carbonate （DMC） with phenol has been investigated. X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, infrared spectroscopy （IR）, thermogravimetry analysis （TG）, atomic absorption spectroscopy and elementary analysis are employed for the catalyst characterization. The results show that, the formation of Pb4O（OC6H5）6 through the reaction of phenol and lead species in the catalyst leads to the crystal phase change of active component and serious leaching of lead, which is the cause of the catalyst deactivation. In addition, the composition of the leached lead is ascertained to be a mixture of Pb4O（OC6H5）6 and PbO with the weight percentage of 62.7% and 37.3%, respectively.
基金supported by Cooperated Project of Academy and College Yunnan province(2003CBALA02P023)
文摘The thermal dissolved sulfuration technology is brought forward and performed based on the characteristic of low grade lead-zinc oxide ore in lanpin. Using sulfur as the sulphidizing agent in the experiment, the oxides in the sandstone and ignimbrite are changed into sulfides. The disproportionation reaction of sulfur in a solution is confirmed as 4S＋3H2O=2S^2-＋S2O3^2--＋6H^＋. The dynamics process is studied and the first-order reaction rate equation -1n（1-a）=ktt is obtained. The effects of the reactive products, stirring speed, dosage of sulfuration agent, value of pH and sulphidizing temperature on the sulfuration of oxide ore are investigated. The results indicate that the reactive apparent activation energy is 100.8 kJ/mol and the sulfuration ratio of lead-zinc oxide ore reaches 60% under the conditions of pH 5.9-7.5, the sulfuration temperature of 130 ℃, sulfuration time of 180 min and the stirring speed of 800 r/min.
文摘X-ray powder diffraction,scanning electron microscopy,energy dispersive spectroscopy,thermogravimetry,differential scanning calorimetry,and mass spectrometry have been used to study the products of nickel-containing pyrrhotite tailings oxidation by oxygen in the air.The kinetic triplets of oxidation,namely,activation energy(E_(a)),pre-exponential factor(A),and reaction model(f(α))being a function of the conversion degree(α),were adjusted by regression analysis.In case of a two-stage process representation,the first step proceeds under autocatalysis control and ends atα=0.42.The kinetic triplet in the first step is E_(a)=262.2 kJ/mol,lg A=14.53 s^(−1),and f(α)=(1-α)^(4.11)(1+1.51×10^(-4)α).For the second step,the process is controlled by the two-dimensional diffusion of the reactants in the layer of oxidation products.The kinetic triplet in the second step isЕa=215.0 kJ/mol,lg A=10.28 s^(−1),and f(α)=(-ln(1-α))^(-1).The obtained empirical formulae for the rate of pyrrhotite tailings oxidation reliably describe the macro-mechanism of the process and can be used to design automatization systems for roast-ing these materials.
文摘Mining activities have created great wealth, but they have also discharged large quantities of tailings. As an important source of heavy metal contamination, sulfide tailings are usually disposed of in open-air impoundments and thus are exposed to microbial oxidation. Microbial activities greatly enhance sulfide oxidation and result in the release of heavy metals and the precipitation of iron (oxy) hydroxides and sulfates. These secondary minerals in turn influence the mobility of dissolved metals and play important roles in the natural attenuation of heavy metals. Elucidating the microbe–mineral interactions in tailings will improve our understanding of the environmental consequence of mining activities.
文摘Iron oxides and lead-zinc deposits in host rocks located in ten drainage basins in the coastal plain of the Red Sea,Egypt,have been subjected to important mining activities.The drainage basins were analyzed to estimate the transportations of these minerals. Fourteen soil samples and fifteen plant samples were collected from sites located in the basin and also in neighboring area and chemically analyzed.In
文摘Using variety of modern testing methods, the processing mineralogical characteristics for a lead and zinc oxide ore in Sichuan were studied systematically. The chemical analysis result shows that the lead and zinc oxide content exceeding the minimum industrial grade and iron ore, total iron content reaches a minimum industrial grade and associated with gold and silver; The mineralogical analysis result shows that lead and zinc mineral composition and configuration are very complexity. The zinc minerals and zinciferous minerals are sphalerite, hemimorphite, Smithsonite, Hydrozincite, zinc chlorite, limonite, zinc dolomite and zincocalcite; lead minerals and plumbiferous minerals are mainly galena, cerussite, anglesite, limonite and Coronadite; The minerals disseminated grain size are very fine and mineral dissemination characteristics are very complex ; expected theoretical recoveries for lead and zinc were 72% and 67% respectively. The results of this study provide basic data and theoretical basis for ore dressing.
文摘Diesel engines have been widely used due to their high thermal efficiency, good environmental adaptability, wide power adjustment range, convenient maintenance and long service life. However, the application of diesel engines is also facing a serious problem;that is, the emission of nitrogen oxides and particulate matter is serious. For marine diesel engine emission requirements, MARPOL Convention Annex VI imposes strict restrictions on the emission of atmospheric pollutants. The limit emission of nitrogen oxides in the Tier III emission standards mandated by IMO is 3.4 g/kWh. Therefore, in order to meet the requirements of international conventions and countries and regions, it is necessary to control the emissions of diesel engines. The NOx in the exhaust gas is mostly a thermal type of nitrogen oxide which is produced under high temperature and high pressure conditions formed during compression and combustion strokes. The diesel engine relies on the compression energy of the mixture to ignite, and the good injection atomization effect is not achieved. The distribution of the detonation point is not uniform, and local high temperature points are generated in some areas, which increases the NOx formation. The main means of reducing NOx emissions are organic internal control and post-treatment. However, the use of internal control technology to reduce the internal temperature of the machine will deteriorate the fuel combustion conditions, so that the fuel cannot be completely burned, and the emissions of incomplete combustion products such as PM and CO increase. It is difficult to achieve NOx reduction by simply relying on the internal control technology, so it is necessary to use post-processing technology. The combined use of different emission reduction technologies is also a hot topic in emissions control research. The post-treatment methods for NOx emission reduction include direct catalytic decomposition, selective non-catalytic reduction, selective catalytic reduction, lean-burn adsorption catalytic reduction, and low-temperature plasma assisted technology. The current research and application schemes in the industry are SCR selectivity. Catalytic reduction and LNT lean combustion adsorption reduction. In this paper, the partial replacement of Ce by La is carried out to modify the Ce/Zr composite oxide. The mass fraction of La2O3 in the prepared La/Ce/Zr composite oxide was 5%, and the physicochemical properties of La/Ce/Zr composite oxide powder were analyzed by ICP, OSC, SEM and TPR techniques. The experiment found that: 1) La can refine the grain and inhibit the grain growth, so that the powder obtains a higher specific surface area and a smaller particle size distribution. 2) The addition of La reduces the sintering of cerium-zirconium and improves the heat aging resistance of the catalyst under the inhibition of high temperature. 3) After doping La, it enhances the migration of surface lattice oxygen and enhances the oxygen storage capacity;the addition of La enhances the NO adsorption capacity of cerium-zirconium and improves the catalytic activity of the catalyst. The light-off temperature and the highest activity temperature of PM decrease, and the reduction rate of No is 19.2%.
文摘The aim of this study was to investigate the synthesis of iron oxide pigments from IOT. The sample of IOT was obtained through mining activity of the Quadrilátero Ferrífero in the state of Minas Gerais, Brazil. The procedure was carried out by hot acid leaching with hydrochloric acid (HCl) which allowed the recovery of about 95% of the iron in a liquor. The iron-based pigments—red (IBP_R), black (IBP_B), and yellow (IBP_Y)—were synthetised from the liquor by selective precipitation, crystallisation, and thermal procedures. The pigments were characterised by particle size distribution, mineral and chemical compositions, as well as colourimetric properties. The process of synthesis was successful and the procedure was shown to maximise the utilisation of mineral resources and minimise the environmental, social, and economic impacts associated with IOT disposal.
文摘氧化石墨烯(Graphene Oxide,GO)可以改善水泥基材料力学性能的良好特性可用来改性固废(铁尾矿砂、再生粗骨料)混凝土。研究对再生粗骨料取代率、铁尾矿砂取代率和GO掺量3个因素设计了正交试验。引入考虑固废利用率的权重指标对GO改性固废混凝土的强度指标进行修正并得出加权评价指标,通过极差分析得到GO改性固废混凝土的较佳配合比,研究较佳配合比下GO改性固废混凝土的抗压强度与抗折强度、坍落度与吸水率和微观形貌。结果显示:当再生粗骨料取代率为100%、铁尾矿砂取代率为50%、GO质量分数为0.05%时,为GO改性固废混凝土的较佳配合比,对GO改性固废混凝土的评价指标影响显著性从大到小依次为再生粗骨料取代率、氧化石墨烯掺量、铁尾矿砂取代率。通过扫描电子显微镜(Scanning Electron Microscope,SEM)微观形貌分析发现,GO能优化水化产物堆叠形态,在尺度上细化水化产物,能够填充改性固废混凝土的孔隙结构,有效改善其致密度;较优配合比下的GO改性固废混凝土的力学性能优于普通混凝土的力学性能,验证了GO改性固废混凝土替代普通混凝土的可行性。
