The chlorination-volatilization process has been adopted to make full use of gold-bearing and iron-rich pyrite cinder. However, problems of low recovery rate, pulverization of pellets, and ring formation have been enc...The chlorination-volatilization process has been adopted to make full use of gold-bearing and iron-rich pyrite cinder. However, problems of low recovery rate, pulverization of pellets, and ring formation have been encountered during the industrialization of this process. The effects of various parameters on the volatilization rates of valuable metals and on the compressive strength of roasted pellets were investigated in this paper. The parameters include the CaCl_2 dosage, heating temperature, and holding time. The results show that heating temperature is the most important parameter for the recovery of target metals. More CaCl_2 was needed for the recovery of zinc than for the recovery of gold, silver, and lead. CaCl_2 started to react with sulfides/SO_2/SiO_2 at temperatures below the melting point of CaCl_2 to generate Cl_2/HCl. Gaseous CaCl_2 was formed at higher temperatures and could react with any of the components. The compressive strength of roasted CaCl_2-bearing pellets first decreased slowly with increasing temperature at temperatures lower than 873 K, which could result in the pulverization of pellets during heating. Their compressive strength increased dramatically with increasing temperature at temperatures greater than 1273 K. Certain quantities of CaCl_2 and Fe(Ⅱ) could improve the compressive strength of the roasted pellets; however, the addition of excessive CaCl_2 decreased the compressive strength of pellets.展开更多
Comprehensive utilization of pyrite cinders is increasingly important because of their huge annual outputs and potential valuable metals recovery to cope with the gradual depletion of high-grade mineral resources. In ...Comprehensive utilization of pyrite cinders is increasingly important because of their huge annual outputs and potential valuable metals recovery to cope with the gradual depletion of high-grade mineral resources. In this work, a new process, i.e., a high-temperature chlorination–magnetizing roasting–magnetic separation process, was proposed for recovering Fe and removing Zn, Pb from a low-grade pyrite cinder containing 49.90 wt% Fe, 1.23 wt% Zn, and 0.29 wt% Pb. Various parameters, including the chlorinating conditions(dosage of Ca Cl2, temperature, and time) and the magnetization roasting conditions(amount of coal, temperature, and time) were investigated. The results indicate that the proposed process is effective for Fe recovery and Zn, Pb removal from the pyrite cinder. Through this process, 97.06% Zn, 96.82% Pb, and approximately 90% S can be removed, and 89.74% Fe is recovered as magnetite into the final product under optimal conditions. A purified magnetite concentrate containing 63.07 wt% Fe, 0.16 wt% P, 0.26 wt% S, and trace amounts of nonferrous metals(0.005 wt% Cu, 0.013 wt% Pb, and 0.051 wt% Zn) was obtained. The concentrate can be potentially used as a high-quality feed material for producing oxidized pellets by blending with other high-grade iron ore concentrates.展开更多
The role of CaCl2 during the high temperature chloridizing-reduction roasting process was investigated, aiming at acquiring high strength blast furnace burden with high iron grade and low nonferrous metals content. Th...The role of CaCl2 during the high temperature chloridizing-reduction roasting process was investigated, aiming at acquiring high strength blast furnace burden with high iron grade and low nonferrous metals content. The effects of CaCl2 dosage on pelletizing, preheating and reduction were investigated. The results show that CaCl2 can improve the wet drop strength but reduces the thermostability of pyrite cinder green balls. When the dosage of CaCl2 exceeds 1%, the compressive strength of preheated pellets decreases while the growth of iron oxide particles is improved. Furthermore, the compressive strength of pre-reduced pellets increases but the metallization degree of pre-reduced pellets decreases with CaCl2 additive. The removal tests indicate that Zn can be removed completely without CaCl2 additive, Cu is removed only under the condition with CaCl2 additive and part of Pb must be removed by CaCl2 additive.展开更多
The determination of CaO content in columbite and steel cinder with flame atomic absorption spectrometry is studied. EDTA+TEA is used to eliminate the interferences, in HCI media,with La as releaser. The methods of sa...The determination of CaO content in columbite and steel cinder with flame atomic absorption spectrometry is studied. EDTA+TEA is used to eliminate the interferences, in HCI media,with La as releaser. The methods of sample treatment and the CaO in remainder undissolved in acids have been conducted. The result of the determination and recovery of CaO shows that the rate of recovery is 100% ～ 102 %, R. S.D<2 %.展开更多
Chemical looping combustion(CLC)is a clean and efficient flame-free combustion technology,which combust the fuels by lattice oxygen from a solid oxygen carrier with inherent CO_(2)capture.The development of oxygen car...Chemical looping combustion(CLC)is a clean and efficient flame-free combustion technology,which combust the fuels by lattice oxygen from a solid oxygen carrier with inherent CO_(2)capture.The development of oxygen carriers with low cost and high redox performance is crucial to the whole efficiency of CLC process.As the solid by-product from the sulfuric acid production,pyrite cinder presented excellent redox performance as an oxygen carrier in CLC process.The main components in pyrite cinder are Fe_(2)O_(3),CaSO_(4),Al_(2)O_(3)and SiO_(2)in which Fe_(2)O_(3)is the active component to provide lattice oxygen.In order to systematic investigate the functions of supports(CaSO_4,Al_(2)O_(3)and SiO_(2))in pyrite cinder,three oxygen carriers(Fe_(2)O_(3)-CaSO_(4),Fe_(2)O_(3)-Al_(2)O_(3)and Fe_(2)O_(3)-SiO_(2))were prepared and evaluated in this study.The results showed that Fe_(2)O_(3)-CaSO_(4) displayed high redox activity and cycling stability in the multiple redox cycles.However,both Fe_(2)O_(3)-Al_(2)O_(3)and Fe_(2)O_(3)-SiO_(2)experienced serious deactivation during redox reactions.It indicated that the inert Fe-Si solid solution(Fe_(2)SiO_(4))was formed in the spent Fe_(2)O_(3)-SiO_(2)sample,which decreased the oxygen carrying capacity of this sample.The XPS results showed that the oxygen species on the surface of Fe_(2)O_(3)-CaSO_(4) could be fully recovered after the 20 redox cycles.It can be concluded that CaSO_(4) is the key to the high redox activity and cycling stability of pyrite cinder.展开更多
As an industrial solid waste,pyrite cinder exhibited excellent reactivity and cycle stability in chemical looping combustion.Prior to the experiment,oxygen carriers often experienced a high temperature calcination pro...As an industrial solid waste,pyrite cinder exhibited excellent reactivity and cycle stability in chemical looping combustion.Prior to the experiment,oxygen carriers often experienced a high temperature calcination process to stabilize the physico-chemical properties,which presented significant influence on the redox performance of oxygen carriers.However,the effect of calcination temperature on the cyclic reaction performance of pyrite cinder has not been studied in detail.In this work,the effect of calcination temperature on the redox activity and attrition characteristic of pyrite cinder were studied in a fluidizedbed reactor using CH_(4) as fuel.A series of pyrite cinder samples were prepared by controlling the calcination temperature.The redox activity and attrition rate of the obtained pyrite cinder samples were investigated deeply.The results showed that calcination temperature displayed significant impact on the redox performance of pyrite cinder.Considering CH_(4) conversion(80%–85%)and attrition resistance,the pyrite cinder calcined at 1050℃ presented excellent redox properties.In the whole experiment process,the CO_(2) selectivity of the pyrite cinder samples were not affected by the calcination temperature and were still close to 100%.The results can provide reference for optimizing the calcination temperature of pyrite cinder during chemical looping process.展开更多
[Objective]The research was designed to explore the effect of long-term stacking of solid waste produced in the coal-burning process of central heating enterprises on physical and chemical properties of soil.[Method]T...[Objective]The research was designed to explore the effect of long-term stacking of solid waste produced in the coal-burning process of central heating enterprises on physical and chemical properties of soil.[Method]This study took the heating enterprises in Shenyang City as the research object.The morphological structure and element composition of coal cinder were determined by continuously collecting coal and cinder samples in different periods.At the same time,the original soil and cinder soil of the stacking site were collected to determine the changes of soil morphological structure,element composition and physical and chemical properties,so as to provide reference for the resource utilization of local cinder waste and the potential pollution risk of the stacking site.[Result]The contents of C,H,O,N,and S non-metallic elements in coal cinder decreased by 69.5%,71.2%,76.0%,74.5%,and 34.6%,respectively when compared with raw coal;while the content of Si increased significantly by 95.7%.The contents of Al,K,and Fe in cinder decreased by 4.3%,60.2%,and 33.3%,respectively,while the contents of Mg and Na increased by 36.1%and 130.9%,respectively.Compared with the original soil,the contents of C,H,and O in shallow cinder soil and deep cinder soil increased by 126.5%,67.9%,80.93%,and 21.3%,25.0%and 42.3%,respectively.The residual carbon existed in the form of activated carbon.The contents of Mg,Al,K,Na,Ca,and Fe in shallow cinder soil and deep cinder soil increased by 61.6%,5.4%,46.1%,35.8%,32.5%,6.3%and 22.3%,12.3%,12.2%,15.6%,5.8%and 2.8%,respectively compared with the original soil.The content of heavy metal elements in coal cinder did not reach the detection limit.Under the scanning electron microscope,the raw coal is mainly block structure,while the cinder is honeycombed and porous and dust.[Conclusion]Cinder stacking can significantly improve the content of organic matter and available K in shallow cinder soil,and improve the porosity and permeability of soil.In addition,cinder waste has high pH and pore structure,which can be used as acid soil conditioner,seedling flower matrix and compound fertilizer filler to take full advantage of cinder waste,improve soil structure and supply nutrients.展开更多
The speciation of heavy metals such as thallium,cadmium and lead existing in pyrite and pyrite cinder was analyzed by ICP-MS with a sequential extraction procedure.The distribution patterns of these metals including e...The speciation of heavy metals such as thallium,cadmium and lead existing in pyrite and pyrite cinder was analyzed by ICP-MS with a sequential extraction procedure.The distribution patterns of these metals including exchangeable,reducible,oxidizable and residual fractions were obtained.Tl,Cd and Pb in pyrite and pyrite cinder samples from each extraction step were determined by inductively coupled plasma mass spectrometry(ICP-MS).Under the optimized instrumental conditions,detection limits of Tl,Cd and Pb in different matrices were within the range of 0.006-0.07 μg/L,and the relative standard deviations ranged from 0.8% to 1.2%.The accuracy of Tl,Cd and Pb determination was checked by analyzing two certified reference materials.The results demonstrate that trace Tl,Cd and Pb in the samples can be accurately determined.The sequential extraction results revealed that the percent contents of Tl,Cd and Pb in exchangeable,reducible and oxidizable fractions in pyrite cinder are different from those in pyrite and in pyrite cinder.Tl,Cd and Pb mostly are distributed in residual fraction.Therefore,the mobility of metals in pyrite is higher than that in pyrite cinder.Although distributions of Tl,Cd and Pb in the non-residual fraction are not dominant in pyrite cinder,the total concentrations of them could not be ignored.Consequently,attention must be paid to the risk of potential pollution by pyrite cinder.展开更多
Acid leaching solution was obtained after mixing pyrite cinders with H 2SO 4, then heating the mixture of pyrite cinders and H 2SO 4 at 200300 ℃, leaching the heated mixture with water and filtrating. Polyferric sulf...Acid leaching solution was obtained after mixing pyrite cinders with H 2SO 4, then heating the mixture of pyrite cinders and H 2SO 4 at 200300 ℃, leaching the heated mixture with water and filtrating. Polyferric sulfate (PFS) solution was produced by adding suitable amounts of FeSO 4·7H 2O and NaClO 3 into acid leaching solution. By concentrating and drying PFS solution, solid PFS with alkali degree of 6.40%22.4% was prepared. Fe 4.67 (SO 4) 6(OH) 2·20H 2O in the solid PFS was discovered by XRD analysis. FT IR spectroscopy shows that the absorption peaks at 3 400 cm -1 and 1 635 cm -1 arise from OH and absorption peaks at 998 cm -1 and 669 cm -1 come from Fe-OH in the solid PFS.展开更多
Well-crystallized hexagonal hematite (α-Fe2O3) platelets were synthesized by hydrothermal process,using a highly concentrated ferric hydroxide as precursor.The precursor was prepared by adding ammonia to the ferric s...Well-crystallized hexagonal hematite (α-Fe2O3) platelets were synthesized by hydrothermal process,using a highly concentrated ferric hydroxide as precursor.The precursor was prepared by adding ammonia to the ferric sulfate solution which was obtained by leaching pyrite cinders with sulfuric acid.Structure and morphology of the synthesized products were investigated by X-ray diffraction,scanning electron microscope,transmission electron microscope and selected area electron diffraction.The results reveal that the reaction temperature has significant effects on the structure,size and shape of the synthesized hematite particles.Typical hexagonal hematite platelets,about 0.4?0.6 μm in diameter and 0.1 μm in thickness,were prepared at 230 °C for 0.5 h.Al3+,contained in the sulfuric acid leaching solution as an impurity,plays an extremely important role in the formation of hexagonal hematite.In addition,a possible mechanism about the formation of hexagonal hematite platelets was proposed.展开更多
Pyrite cinder is a kind of solid waste of sulfuric acid industry. After mixing pyrite cinders with sulfuric acid, ferric sulfate was obtained by heating, maturing, dissolving and filtrating. Suitable amounts of FeSO 4...Pyrite cinder is a kind of solid waste of sulfuric acid industry. After mixing pyrite cinders with sulfuric acid, ferric sulfate was obtained by heating, maturing, dissolving and filtrating. Suitable amounts of FeSO 4·7H 2O and NaClO 3 were added into ferric sulfate solution and polyferric sulfate(PFS) solution was produced. Solid PFS was made by concentrating and drying PFS solution. Time-dependent complex colorimetric tests were done while ferron agent reacted with Fe 3+ in the solution. The results show that the proportion of transitional low polymeric species and high polymeric species are increased after PFS solution is transferred into solid PFS. It was discovered by jar tests that solid PFS has very good coagulation effects relevant to the increase of transitional lower polymeric species.展开更多
Micaceous iron oxide(MIO) with a hexagonal flaky shape was prepared by hydrothermal method.The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia sol...Micaceous iron oxide(MIO) with a hexagonal flaky shape was prepared by hydrothermal method.The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia solution.The optimal experimental conditions for preparing micaceous iron oxide were investigated by orthogonal experiments.Micaceous iron oxide can be successfully prepared when optimal parameters of total iron concentration of 2.0 mol/L,pH value of 8,n(Fe2+)/n(Fe3+) of 0.1,mass of seed crystal of 1 g,reaction temperature of 260 °C and reaction time of 30 min are applied.X-ray diffractometry(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and selected area electron diffractometry(SAEM) were adopted to characterize the hydrothermal products prepared under optimal conditions.The results indicate that highly crystallized α-Fe2O3 hexagonal flakes,about 1.0-1.5 μm in diameter and 0.1 μm in thickness,are prepared.Furthermore,the quality of micaceous iron oxide prepared can meet the required characteristics of micaceous iron oxide pigments for paints(ISO10601-2007).展开更多
We investigated the photocatalytic degradation of dye wastewater by using titanium dioxide (TiO2) coated on a coal cinder. The coal cinder was used as the carrier, with a thin film of TiO2 coated on it by using the so...We investigated the photocatalytic degradation of dye wastewater by using titanium dioxide (TiO2) coated on a coal cinder. The coal cinder was used as the carrier, with a thin film of TiO2 coated on it by using the sol-gel method. Using the Congo red as the model pollutant for dye wastewater, we studied the decolorization efficiency, and effects of TiO2 film thickness and roasting temperature on the efficiency. We also evaluated the recycling and regeneration of the immobilized TiO2 (TiO2/cinder). Results show that the decolorization rate of Congo red solution was more than 98% after 2 h treatment when we used TiO2/cinder calcined at 500 °C for 2 h and coated four times as the photocatalyst. At the same time, the TiO2/cinder remained high catalytic activity after being reused and regenerated for many times.展开更多
Cr(Ⅵ) is a common heavy metal ion, which will seriously harm human body and environment.Therefore, the removal of Cr(Ⅵ) has become an attractive topic.In this work, cinder was used as a raw material to synthesize a ...Cr(Ⅵ) is a common heavy metal ion, which will seriously harm human body and environment.Therefore, the removal of Cr(Ⅵ) has become an attractive topic.In this work, cinder was used as a raw material to synthesize a nanoneedle material: γ-(AlOOH@FeOOH)(γ-Al@Fe).The physicochemical properties of γ-Al@Fe were thoroughly characterized, and its effectiveness as a catalyst for photocatalytic reduction of Cr(Ⅵ) was evaluated.The results showed that Cr(Ⅵ) could be efficiently reduced by γ-Al@Fe in the presence of tartaric acid(TA) under visible light.The variable factors on the reaction were investigated in detail, and the results showed that under optimal conditions(γ-Al@Fe 0.4 g/L, TA 0.6 g/L, pH 2), Cr(Ⅵ)was completely reduced within 7 min.Besides, scavenger experiments and EPR proved that O_(2)^(·-) and CO_(2)^(·-) played a significant role in the photocatalytic reduction of Cr(Ⅵ).TA acts as a sacrificial agent to trap the holes and generate strong reducing free radicals: CO_(2)^(·-).Dissolving O_(2) could react with electrons to generate O_(2)^(·-).This work discussed the performance and mechanism of photocatalytic reduction of Cr(Ⅵ) in detail, which provided a new idea for the resource utilization of solid waste and the treatment of heavy metal sewage.展开更多
基金financially supported by the National NaturalScience Foundation of China (No. 51202249)the National High-Tech Research and Development Program of China (No. 2011AA06A104)the Projects in the National Science & Technology Pillar Program during the 12th Five-year Plan Period (No. 2012BAB08B04)
文摘The chlorination-volatilization process has been adopted to make full use of gold-bearing and iron-rich pyrite cinder. However, problems of low recovery rate, pulverization of pellets, and ring formation have been encountered during the industrialization of this process. The effects of various parameters on the volatilization rates of valuable metals and on the compressive strength of roasted pellets were investigated in this paper. The parameters include the CaCl_2 dosage, heating temperature, and holding time. The results show that heating temperature is the most important parameter for the recovery of target metals. More CaCl_2 was needed for the recovery of zinc than for the recovery of gold, silver, and lead. CaCl_2 started to react with sulfides/SO_2/SiO_2 at temperatures below the melting point of CaCl_2 to generate Cl_2/HCl. Gaseous CaCl_2 was formed at higher temperatures and could react with any of the components. The compressive strength of roasted CaCl_2-bearing pellets first decreased slowly with increasing temperature at temperatures lower than 873 K, which could result in the pulverization of pellets during heating. Their compressive strength increased dramatically with increasing temperature at temperatures greater than 1273 K. Certain quantities of CaCl_2 and Fe(Ⅱ) could improve the compressive strength of the roasted pellets; however, the addition of excessive CaCl_2 decreased the compressive strength of pellets.
基金financially supported by the National Natural Science Foundation of China(No.51574281)the National Torch Program of China(No.2011GH561685)the Hunan Provincial Co-innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources
文摘Comprehensive utilization of pyrite cinders is increasingly important because of their huge annual outputs and potential valuable metals recovery to cope with the gradual depletion of high-grade mineral resources. In this work, a new process, i.e., a high-temperature chlorination–magnetizing roasting–magnetic separation process, was proposed for recovering Fe and removing Zn, Pb from a low-grade pyrite cinder containing 49.90 wt% Fe, 1.23 wt% Zn, and 0.29 wt% Pb. Various parameters, including the chlorinating conditions(dosage of Ca Cl2, temperature, and time) and the magnetization roasting conditions(amount of coal, temperature, and time) were investigated. The results indicate that the proposed process is effective for Fe recovery and Zn, Pb removal from the pyrite cinder. Through this process, 97.06% Zn, 96.82% Pb, and approximately 90% S can be removed, and 89.74% Fe is recovered as magnetite into the final product under optimal conditions. A purified magnetite concentrate containing 63.07 wt% Fe, 0.16 wt% P, 0.26 wt% S, and trace amounts of nonferrous metals(0.005 wt% Cu, 0.013 wt% Pb, and 0.051 wt% Zn) was obtained. The concentrate can be potentially used as a high-quality feed material for producing oxidized pellets by blending with other high-grade iron ore concentrates.
基金Project(51504155)supported by the National Natural Science Foundation of ChinaProject(BK20140337)supported by the Basic Research Program of Jiangsu Province+2 种基金ChinaProject(SDY2013A13)supported by the Young Teacher Natural Science Fund of Soochow UniversityChina
文摘The role of CaCl2 during the high temperature chloridizing-reduction roasting process was investigated, aiming at acquiring high strength blast furnace burden with high iron grade and low nonferrous metals content. The effects of CaCl2 dosage on pelletizing, preheating and reduction were investigated. The results show that CaCl2 can improve the wet drop strength but reduces the thermostability of pyrite cinder green balls. When the dosage of CaCl2 exceeds 1%, the compressive strength of preheated pellets decreases while the growth of iron oxide particles is improved. Furthermore, the compressive strength of pre-reduced pellets increases but the metallization degree of pre-reduced pellets decreases with CaCl2 additive. The removal tests indicate that Zn can be removed completely without CaCl2 additive, Cu is removed only under the condition with CaCl2 additive and part of Pb must be removed by CaCl2 additive.
文摘The determination of CaO content in columbite and steel cinder with flame atomic absorption spectrometry is studied. EDTA+TEA is used to eliminate the interferences, in HCI media,with La as releaser. The methods of sample treatment and the CaO in remainder undissolved in acids have been conducted. The result of the determination and recovery of CaO shows that the rate of recovery is 100% ～ 102 %, R. S.D<2 %.
基金supported by the Program for High-Level Entrepreneurial and Innovative Talents Introduction of Jiangsu ProvinceFoundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2021-K56)+1 种基金Foundation of Key Laboratory of Energy Thermal Conversion and Control of Ministry of EducationSenior Talent Foundation of Jiangsu University(20JDG40)。
文摘Chemical looping combustion(CLC)is a clean and efficient flame-free combustion technology,which combust the fuels by lattice oxygen from a solid oxygen carrier with inherent CO_(2)capture.The development of oxygen carriers with low cost and high redox performance is crucial to the whole efficiency of CLC process.As the solid by-product from the sulfuric acid production,pyrite cinder presented excellent redox performance as an oxygen carrier in CLC process.The main components in pyrite cinder are Fe_(2)O_(3),CaSO_(4),Al_(2)O_(3)and SiO_(2)in which Fe_(2)O_(3)is the active component to provide lattice oxygen.In order to systematic investigate the functions of supports(CaSO_4,Al_(2)O_(3)and SiO_(2))in pyrite cinder,three oxygen carriers(Fe_(2)O_(3)-CaSO_(4),Fe_(2)O_(3)-Al_(2)O_(3)and Fe_(2)O_(3)-SiO_(2))were prepared and evaluated in this study.The results showed that Fe_(2)O_(3)-CaSO_(4) displayed high redox activity and cycling stability in the multiple redox cycles.However,both Fe_(2)O_(3)-Al_(2)O_(3)and Fe_(2)O_(3)-SiO_(2)experienced serious deactivation during redox reactions.It indicated that the inert Fe-Si solid solution(Fe_(2)SiO_(4))was formed in the spent Fe_(2)O_(3)-SiO_(2)sample,which decreased the oxygen carrying capacity of this sample.The XPS results showed that the oxygen species on the surface of Fe_(2)O_(3)-CaSO_(4) could be fully recovered after the 20 redox cycles.It can be concluded that CaSO_(4) is the key to the high redox activity and cycling stability of pyrite cinder.
基金supported by the China Postdoctoral Science Foundation(2020M681503)Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2021-K56).
文摘As an industrial solid waste,pyrite cinder exhibited excellent reactivity and cycle stability in chemical looping combustion.Prior to the experiment,oxygen carriers often experienced a high temperature calcination process to stabilize the physico-chemical properties,which presented significant influence on the redox performance of oxygen carriers.However,the effect of calcination temperature on the cyclic reaction performance of pyrite cinder has not been studied in detail.In this work,the effect of calcination temperature on the redox activity and attrition characteristic of pyrite cinder were studied in a fluidizedbed reactor using CH_(4) as fuel.A series of pyrite cinder samples were prepared by controlling the calcination temperature.The redox activity and attrition rate of the obtained pyrite cinder samples were investigated deeply.The results showed that calcination temperature displayed significant impact on the redox performance of pyrite cinder.Considering CH_(4) conversion(80%–85%)and attrition resistance,the pyrite cinder calcined at 1050℃ presented excellent redox properties.In the whole experiment process,the CO_(2) selectivity of the pyrite cinder samples were not affected by the calcination temperature and were still close to 100%.The results can provide reference for optimizing the calcination temperature of pyrite cinder during chemical looping process.
基金Supported by Open Fund Project of the Key Laboratory of Waste Fertilizer Utilization of the Ministry of Agriculture and Rural Areas (KLFAW201901)
文摘[Objective]The research was designed to explore the effect of long-term stacking of solid waste produced in the coal-burning process of central heating enterprises on physical and chemical properties of soil.[Method]This study took the heating enterprises in Shenyang City as the research object.The morphological structure and element composition of coal cinder were determined by continuously collecting coal and cinder samples in different periods.At the same time,the original soil and cinder soil of the stacking site were collected to determine the changes of soil morphological structure,element composition and physical and chemical properties,so as to provide reference for the resource utilization of local cinder waste and the potential pollution risk of the stacking site.[Result]The contents of C,H,O,N,and S non-metallic elements in coal cinder decreased by 69.5%,71.2%,76.0%,74.5%,and 34.6%,respectively when compared with raw coal;while the content of Si increased significantly by 95.7%.The contents of Al,K,and Fe in cinder decreased by 4.3%,60.2%,and 33.3%,respectively,while the contents of Mg and Na increased by 36.1%and 130.9%,respectively.Compared with the original soil,the contents of C,H,and O in shallow cinder soil and deep cinder soil increased by 126.5%,67.9%,80.93%,and 21.3%,25.0%and 42.3%,respectively.The residual carbon existed in the form of activated carbon.The contents of Mg,Al,K,Na,Ca,and Fe in shallow cinder soil and deep cinder soil increased by 61.6%,5.4%,46.1%,35.8%,32.5%,6.3%and 22.3%,12.3%,12.2%,15.6%,5.8%and 2.8%,respectively compared with the original soil.The content of heavy metal elements in coal cinder did not reach the detection limit.Under the scanning electron microscope,the raw coal is mainly block structure,while the cinder is honeycombed and porous and dust.[Conclusion]Cinder stacking can significantly improve the content of organic matter and available K in shallow cinder soil,and improve the porosity and permeability of soil.In addition,cinder waste has high pH and pore structure,which can be used as acid soil conditioner,seedling flower matrix and compound fertilizer filler to take full advantage of cinder waste,improve soil structure and supply nutrients.
基金supported by the Union Foundation of NSFC-Guangdong Province (Grant No. U0633001)
文摘The speciation of heavy metals such as thallium,cadmium and lead existing in pyrite and pyrite cinder was analyzed by ICP-MS with a sequential extraction procedure.The distribution patterns of these metals including exchangeable,reducible,oxidizable and residual fractions were obtained.Tl,Cd and Pb in pyrite and pyrite cinder samples from each extraction step were determined by inductively coupled plasma mass spectrometry(ICP-MS).Under the optimized instrumental conditions,detection limits of Tl,Cd and Pb in different matrices were within the range of 0.006-0.07 μg/L,and the relative standard deviations ranged from 0.8% to 1.2%.The accuracy of Tl,Cd and Pb determination was checked by analyzing two certified reference materials.The results demonstrate that trace Tl,Cd and Pb in the samples can be accurately determined.The sequential extraction results revealed that the percent contents of Tl,Cd and Pb in exchangeable,reducible and oxidizable fractions in pyrite cinder are different from those in pyrite and in pyrite cinder.Tl,Cd and Pb mostly are distributed in residual fraction.Therefore,the mobility of metals in pyrite is higher than that in pyrite cinder.Although distributions of Tl,Cd and Pb in the non-residual fraction are not dominant in pyrite cinder,the total concentrations of them could not be ignored.Consequently,attention must be paid to the risk of potential pollution by pyrite cinder.
文摘Acid leaching solution was obtained after mixing pyrite cinders with H 2SO 4, then heating the mixture of pyrite cinders and H 2SO 4 at 200300 ℃, leaching the heated mixture with water and filtrating. Polyferric sulfate (PFS) solution was produced by adding suitable amounts of FeSO 4·7H 2O and NaClO 3 into acid leaching solution. By concentrating and drying PFS solution, solid PFS with alkali degree of 6.40%22.4% was prepared. Fe 4.67 (SO 4) 6(OH) 2·20H 2O in the solid PFS was discovered by XRD analysis. FT IR spectroscopy shows that the absorption peaks at 3 400 cm -1 and 1 635 cm -1 arise from OH and absorption peaks at 998 cm -1 and 669 cm -1 come from Fe-OH in the solid PFS.
基金Project(2008A090300016) supported by the Key Science and Technology Item of Guangdong Province,ChinaProject(ZKJ2010022) supported by the Precious Apparatus Opening Center Foundation of Central South University,China
文摘Well-crystallized hexagonal hematite (α-Fe2O3) platelets were synthesized by hydrothermal process,using a highly concentrated ferric hydroxide as precursor.The precursor was prepared by adding ammonia to the ferric sulfate solution which was obtained by leaching pyrite cinders with sulfuric acid.Structure and morphology of the synthesized products were investigated by X-ray diffraction,scanning electron microscope,transmission electron microscope and selected area electron diffraction.The results reveal that the reaction temperature has significant effects on the structure,size and shape of the synthesized hematite particles.Typical hexagonal hematite platelets,about 0.4?0.6 μm in diameter and 0.1 μm in thickness,were prepared at 230 °C for 0.5 h.Al3+,contained in the sulfuric acid leaching solution as an impurity,plays an extremely important role in the formation of hexagonal hematite.In addition,a possible mechanism about the formation of hexagonal hematite platelets was proposed.
文摘Pyrite cinder is a kind of solid waste of sulfuric acid industry. After mixing pyrite cinders with sulfuric acid, ferric sulfate was obtained by heating, maturing, dissolving and filtrating. Suitable amounts of FeSO 4·7H 2O and NaClO 3 were added into ferric sulfate solution and polyferric sulfate(PFS) solution was produced. Solid PFS was made by concentrating and drying PFS solution. Time-dependent complex colorimetric tests were done while ferron agent reacted with Fe 3+ in the solution. The results show that the proportion of transitional low polymeric species and high polymeric species are increased after PFS solution is transferred into solid PFS. It was discovered by jar tests that solid PFS has very good coagulation effects relevant to the increase of transitional lower polymeric species.
基金Project(2008A090300016) supported by Major Science & Technology Special Program of Guangdong Province,China
文摘Micaceous iron oxide(MIO) with a hexagonal flaky shape was prepared by hydrothermal method.The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia solution.The optimal experimental conditions for preparing micaceous iron oxide were investigated by orthogonal experiments.Micaceous iron oxide can be successfully prepared when optimal parameters of total iron concentration of 2.0 mol/L,pH value of 8,n(Fe2+)/n(Fe3+) of 0.1,mass of seed crystal of 1 g,reaction temperature of 260 °C and reaction time of 30 min are applied.X-ray diffractometry(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and selected area electron diffractometry(SAEM) were adopted to characterize the hydrothermal products prepared under optimal conditions.The results indicate that highly crystallized α-Fe2O3 hexagonal flakes,about 1.0-1.5 μm in diameter and 0.1 μm in thickness,are prepared.Furthermore,the quality of micaceous iron oxide prepared can meet the required characteristics of micaceous iron oxide pigments for paints(ISO10601-2007).
基金Funded by the Youth Fund Project of Yibin University (No. QJ05-28)
文摘We investigated the photocatalytic degradation of dye wastewater by using titanium dioxide (TiO2) coated on a coal cinder. The coal cinder was used as the carrier, with a thin film of TiO2 coated on it by using the sol-gel method. Using the Congo red as the model pollutant for dye wastewater, we studied the decolorization efficiency, and effects of TiO2 film thickness and roasting temperature on the efficiency. We also evaluated the recycling and regeneration of the immobilized TiO2 (TiO2/cinder). Results show that the decolorization rate of Congo red solution was more than 98% after 2 h treatment when we used TiO2/cinder calcined at 500 °C for 2 h and coated four times as the photocatalyst. At the same time, the TiO2/cinder remained high catalytic activity after being reused and regenerated for many times.
基金supported by the National Natural Science Foundation of China (Nos.51672077, 51872089)。
文摘Cr(Ⅵ) is a common heavy metal ion, which will seriously harm human body and environment.Therefore, the removal of Cr(Ⅵ) has become an attractive topic.In this work, cinder was used as a raw material to synthesize a nanoneedle material: γ-(AlOOH@FeOOH)(γ-Al@Fe).The physicochemical properties of γ-Al@Fe were thoroughly characterized, and its effectiveness as a catalyst for photocatalytic reduction of Cr(Ⅵ) was evaluated.The results showed that Cr(Ⅵ) could be efficiently reduced by γ-Al@Fe in the presence of tartaric acid(TA) under visible light.The variable factors on the reaction were investigated in detail, and the results showed that under optimal conditions(γ-Al@Fe 0.4 g/L, TA 0.6 g/L, pH 2), Cr(Ⅵ)was completely reduced within 7 min.Besides, scavenger experiments and EPR proved that O_(2)^(·-) and CO_(2)^(·-) played a significant role in the photocatalytic reduction of Cr(Ⅵ).TA acts as a sacrificial agent to trap the holes and generate strong reducing free radicals: CO_(2)^(·-).Dissolving O_(2) could react with electrons to generate O_(2)^(·-).This work discussed the performance and mechanism of photocatalytic reduction of Cr(Ⅵ) in detail, which provided a new idea for the resource utilization of solid waste and the treatment of heavy metal sewage.
