Neutral leach residue of zinc calcine （NLRZC） was mechanically activated by a stirring ball mill. Subsequently, the changes in physicochemical properties and dissolution kinetics in sulphuric acid were studied. The ...Neutral leach residue of zinc calcine （NLRZC） was mechanically activated by a stirring ball mill. Subsequently, the changes in physicochemical properties and dissolution kinetics in sulphuric acid were studied. The crystalline structure, morphology, particle size and specific surface area of the non-activated and mechanically activated NLRZC were characterized by X-ray diffraction, scanning electron microscope, particle size analyzer and volumetric adsorption analyzer, respectively. The characterization results indicate that mechanical activation （MA） induced remarkable changes in the physicochemical properties of NLRZC. The leaching experiments show that MA significantly enhances the leaching reactivity of NLRZC using the zinc extraction as evaluating index. After NLRZC is mechanically activated for 30 min and 60 min, the activation energy decreases from 56.6 kJ/mol of non-activated NLRZC to 36.1 kJ/mol and 29.9 kJ/mol, respectively. The reaction orders of the non-activated, 30 and 60 min activated NLRZC dissolution with respect to H2SO4 concentration were found to be 0.34, 0.30, and 0.29, respectively.展开更多
FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated...FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated.The results show that the optimum conditions are FeS2/Fe molar ratio of 5:5,milling time of 2 h,ball-to-material mass ratio of 15:1 and milling with stainless steel ball.Then,the composites were characterized by XRD,SEM,FTIR,etc.The physicochemical properties of FeS2/Fe mixture change dramatically,which is responsible for its excellent performance.Finally,the stabilization process of FAS was optimized.When the FAS is mixed with composites at mass ratio of 4:1 and milled for 30 min,the As leaching concentration of FAS can be reduced from 639.15 to 4.74 mg/L with the stabilization ratio of 99.2%.展开更多
A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes) is described. Industrial tests have proved that by using this technology not only can waste be re-us...A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes) is described. Industrial tests have proved that by using this technology not only can waste be re-used but also coal resources can be exploited with a higher recovery rate without removing buildings located over the working faces. Two special devices, a hydraulic support and a scraper conveyor, run side-by-side on the same working face to simultaneously realize mining and filling. These are described in detail. The tests allow analysis of rock pressure and ground subsidence when backfilling techniques are employed. These values are compared to those from mining without using backfilling techniques, under the same geological conditions. The concept of equivalent mining height is proposed based on theoretical analysis of rock pressure and ground subsidence. The upper limits of the rock pressure and ground subsidence can be estimated in backfilling mining using this concept along with traditional engineering formulae.展开更多
Goethite is a metals-rich residue that occurs during zinc production. The feasibility of metal recovery from goethite has been demonstrated, but is not economically viable on an industrial scale. Therefore, goethite i...Goethite is a metals-rich residue that occurs during zinc production. The feasibility of metal recovery from goethite has been demonstrated, but is not economically viable on an industrial scale. Therefore, goethite is landfilled with considerable economic costs and environmental risks. The goal of this study is to evaluate the environmental performance of a new valorization strategy for goethite residues from zinc production, with the aims of： ① recovering the valuable zinc contained in the goethite and ② avoiding the landfilling of goethite by producing a clean byproduct. The presented goethite valoriza- tion strategy consists of a sequence of two processes： ① plasma fuming and ② inorganic polymerization of the fumed slag. Plasma fuming recovers the valuable metals by fuming the goethite. The metals-flee fumed slag undergoes a process of inorganic polymerization to form inorganic polymers, that can be used as a novel building material, as an alternative to ordinary Portland cement （OPC）-based concrete. Life- cycle assessment （LCA） is used to compare the environmental performance of the inorganic polymer with the environmental performances of equivalent OPC-based concrete. The LCA results show the tradeoff between the environmental burdens of the fuming process and inorganic polymerization versus the environmental benefits of metal recovery, OPC concrete substitution, and the avoidance of goethite land- filling. The goethite-based inorganic polymers production shows better performances in several environ- mental impact categories, thanks to the avoided landfilling of goethite. However, in other environmental impact categories, such as global warming, the goethite valorization is strongly affected by the high-energy requirements of the plasma-fuming process, which represent the environmental hotspots of the proposed goethite recycling scheme. The key elements toward the sustainability of goethite valorization have been identified, and include the use of a clean electric mix, more effective control of the fumed gas emissions, and a reduced use of fumed slag through increased efficiency of the inorganic polymerization process.展开更多
The paper analyzes the influence of lead toxicity by anaerobic granule sludge inhibition and recovering experiments. The result shows that there are different inhibition types at differ-ent lead contents. Higher lead ...The paper analyzes the influence of lead toxicity by anaerobic granule sludge inhibition and recovering experiments. The result shows that there are different inhibition types at differ-ent lead contents. Higher lead content leads to more inhibition granular sludge, and at the same time, the time of gas recovery is different. Lower lead content per microorganism results in sooner sludge recovery. Microorganisms have a good ability to resist lead toxicity.展开更多
The hydration and mechanical properties of Portland cement blended with low-CaO steel slag were studied and reported. The steel slag was used to replace cement up to 30% and then blended cement powder, paste and morta...The hydration and mechanical properties of Portland cement blended with low-CaO steel slag were studied and reported. The steel slag was used to replace cement up to 30% and then blended cement powder, paste and mortar samples prepared for the experiment. The quantitative analysis of XRD shows that ettringite formation is greatly reduced by incorporation of steel slag but there was a relatively low reduction of portlandite. Thermal analysis by TG shows that slag injection reduced portlandite content in the cement by at least 50%. Generally, the slag cement pastes required less water to form a workable paste compared to the reference cement, reducing as the slag content was increased. However, the setting times were higher than the reference. The permeability of the blended cement samples were lower than the control. The incorporation of 5% slag could not have an effect on the compressive strength of the concrete. The results confirmed that whilst cements with up to 15% slag content satisfied the strength requirements of class 42.5 N and those containing 20%-30% produce Class 32.5R cement.展开更多
A methodology for kinetic modeling of conversion processes is presented.The proposed approach allows to overcome the lack of molecular detail of the petroleum fractions and to simulate the reactions of the process by ...A methodology for kinetic modeling of conversion processes is presented.The proposed approach allows to overcome the lack of molecular detail of the petroleum fractions and to simulate the reactions of the process by means of a two-step procedure.In the first step,a synthetic mixture of molecules representing the feedstock is generated via a molecular reconstruction method,termed SR-REM molecular reconstruction.In the second step,a kinetic Monte Carlo method,termed stochastic simulation algorithm(SSA),is used to simulate the effect of the conversion reactions on the mixture of molecules.The resulting methodology is applied to the Athabasca vacuum residue hydrocracking.An adequate molecular representation of the vacuum residue is obtained using the SR-REM algorithm.The reaction simulations present a good agreement with the laboratory data for Athabasca vacuum residue conversion.In addition,the proposed methodology provides the molecular detail of the vacuum residue conversion throughout the reactions simulations.展开更多
基金Project(51064002)supported by the National Natural Science Foundation of ChinaProject(0728238)supported by the Natural Science Foundation of Guangxi Province,China
文摘Neutral leach residue of zinc calcine （NLRZC） was mechanically activated by a stirring ball mill. Subsequently, the changes in physicochemical properties and dissolution kinetics in sulphuric acid were studied. The crystalline structure, morphology, particle size and specific surface area of the non-activated and mechanically activated NLRZC were characterized by X-ray diffraction, scanning electron microscope, particle size analyzer and volumetric adsorption analyzer, respectively. The characterization results indicate that mechanical activation （MA） induced remarkable changes in the physicochemical properties of NLRZC. The leaching experiments show that MA significantly enhances the leaching reactivity of NLRZC using the zinc extraction as evaluating index. After NLRZC is mechanically activated for 30 min and 60 min, the activation energy decreases from 56.6 kJ/mol of non-activated NLRZC to 36.1 kJ/mol and 29.9 kJ/mol, respectively. The reaction orders of the non-activated, 30 and 60 min activated NLRZC dissolution with respect to H2SO4 concentration were found to be 0.34, 0.30, and 0.29, respectively.
基金Projects(2018YFC1900305,2018YFC1903301)supported by the National Key R&D Program of ChinaProject(51825403)supported by the National Natural Science Foundation for Distinguished Young Scholars of China+1 种基金Project(51634010)supported by the National Natural Science Foundation of ChinaProject(2017RS3010)supported by the Science and Technology Program of Hunan Province,China
文摘FeS2/Fe composites were mechanochemically prepared with iron powder and pyrite for the stabilization of ferrite arsenate sludge(FAS).The effects of preparation parameters on stabilization performance were investigated.The results show that the optimum conditions are FeS2/Fe molar ratio of 5:5,milling time of 2 h,ball-to-material mass ratio of 15:1 and milling with stainless steel ball.Then,the composites were characterized by XRD,SEM,FTIR,etc.The physicochemical properties of FeS2/Fe mixture change dramatically,which is responsible for its excellent performance.Finally,the stabilization process of FAS was optimized.When the FAS is mixed with composites at mass ratio of 4:1 and milled for 30 min,the As leaching concentration of FAS can be reduced from 639.15 to 4.74 mg/L with the stabilization ratio of 99.2%.
基金supports for this work provided by Na-tional basic research program of China (No. 2007CB209400)the National Natural Science Foundation of China (No. 50834004)+1 种基金the National Natural Science Foundation of China (No. 50574090) SR Foundation of China University of Mining & Technology (No. 50634050)
文摘A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes) is described. Industrial tests have proved that by using this technology not only can waste be re-used but also coal resources can be exploited with a higher recovery rate without removing buildings located over the working faces. Two special devices, a hydraulic support and a scraper conveyor, run side-by-side on the same working face to simultaneously realize mining and filling. These are described in detail. The tests allow analysis of rock pressure and ground subsidence when backfilling techniques are employed. These values are compared to those from mining without using backfilling techniques, under the same geological conditions. The concept of equivalent mining height is proposed based on theoretical analysis of rock pressure and ground subsidence. The upper limits of the rock pressure and ground subsidence can be estimated in backfilling mining using this concept along with traditional engineering formulae.
文摘Goethite is a metals-rich residue that occurs during zinc production. The feasibility of metal recovery from goethite has been demonstrated, but is not economically viable on an industrial scale. Therefore, goethite is landfilled with considerable economic costs and environmental risks. The goal of this study is to evaluate the environmental performance of a new valorization strategy for goethite residues from zinc production, with the aims of： ① recovering the valuable zinc contained in the goethite and ② avoiding the landfilling of goethite by producing a clean byproduct. The presented goethite valoriza- tion strategy consists of a sequence of two processes： ① plasma fuming and ② inorganic polymerization of the fumed slag. Plasma fuming recovers the valuable metals by fuming the goethite. The metals-flee fumed slag undergoes a process of inorganic polymerization to form inorganic polymers, that can be used as a novel building material, as an alternative to ordinary Portland cement （OPC）-based concrete. Life- cycle assessment （LCA） is used to compare the environmental performance of the inorganic polymer with the environmental performances of equivalent OPC-based concrete. The LCA results show the tradeoff between the environmental burdens of the fuming process and inorganic polymerization versus the environmental benefits of metal recovery, OPC concrete substitution, and the avoidance of goethite land- filling. The goethite-based inorganic polymers production shows better performances in several environ- mental impact categories, thanks to the avoided landfilling of goethite. However, in other environmental impact categories, such as global warming, the goethite valorization is strongly affected by the high-energy requirements of the plasma-fuming process, which represent the environmental hotspots of the proposed goethite recycling scheme. The key elements toward the sustainability of goethite valorization have been identified, and include the use of a clean electric mix, more effective control of the fumed gas emissions, and a reduced use of fumed slag through increased efficiency of the inorganic polymerization process.
基金Supported by The national natural Science Foundation of China (Grant No.50172009).
文摘The paper analyzes the influence of lead toxicity by anaerobic granule sludge inhibition and recovering experiments. The result shows that there are different inhibition types at differ-ent lead contents. Higher lead content leads to more inhibition granular sludge, and at the same time, the time of gas recovery is different. Lower lead content per microorganism results in sooner sludge recovery. Microorganisms have a good ability to resist lead toxicity.
文摘The hydration and mechanical properties of Portland cement blended with low-CaO steel slag were studied and reported. The steel slag was used to replace cement up to 30% and then blended cement powder, paste and mortar samples prepared for the experiment. The quantitative analysis of XRD shows that ettringite formation is greatly reduced by incorporation of steel slag but there was a relatively low reduction of portlandite. Thermal analysis by TG shows that slag injection reduced portlandite content in the cement by at least 50%. Generally, the slag cement pastes required less water to form a workable paste compared to the reference cement, reducing as the slag content was increased. However, the setting times were higher than the reference. The permeability of the blended cement samples were lower than the control. The incorporation of 5% slag could not have an effect on the compressive strength of the concrete. The results confirmed that whilst cements with up to 15% slag content satisfied the strength requirements of class 42.5 N and those containing 20%-30% produce Class 32.5R cement.
文摘A methodology for kinetic modeling of conversion processes is presented.The proposed approach allows to overcome the lack of molecular detail of the petroleum fractions and to simulate the reactions of the process by means of a two-step procedure.In the first step,a synthetic mixture of molecules representing the feedstock is generated via a molecular reconstruction method,termed SR-REM molecular reconstruction.In the second step,a kinetic Monte Carlo method,termed stochastic simulation algorithm(SSA),is used to simulate the effect of the conversion reactions on the mixture of molecules.The resulting methodology is applied to the Athabasca vacuum residue hydrocracking.An adequate molecular representation of the vacuum residue is obtained using the SR-REM algorithm.The reaction simulations present a good agreement with the laboratory data for Athabasca vacuum residue conversion.In addition,the proposed methodology provides the molecular detail of the vacuum residue conversion throughout the reactions simulations.
