Physicochemical properties and leaching behaviors of two typical arsenic-bearing lime?ferrate sludges(ABLFS),waste acid residue(WAR)and calcium arsenate residue(CAR),are comprehensively described.The chemical composit...Physicochemical properties and leaching behaviors of two typical arsenic-bearing lime?ferrate sludges(ABLFS),waste acid residue(WAR)and calcium arsenate residue(CAR),are comprehensively described.The chemical composition,morphological features,phase composition and arsenic occurrence state of WAR and CAR are analyzed by ICP?AES,SEM?EDS,XRD,XPS and chemical phase analysis.The toxicity leaching test and three-stage BCR sequential extraction procedure are utilized to investigate arsenic leaching behaviors.The results show that the contents of arsenic in WAR and CAR are2.5%and21.2%and mainly present in the phases of arsenate and arsenic oxides dispersed uniformly or agglomerated in amorphous particles.The leaching concentrations of arsenic excess119and1063times of TCLP standard regulatory level with leaching rates of47.66%and50.15%for WAR and CAR,respectively.About90%of extracted arsenic is in the form of acid soluble and reducible,which is the reason of high arsenic leaching toxicity and environmental activity of ABLFS.This research provides comprehensive information on harmless disposal of ABLFS from industrial wastewater treatment of lime?ferrate process.展开更多
The usage of plastic-impregnated waste derived solid fuel in conventional combustor is hindered by many technical factors, especially its organic chlorine content. In this paper, experimental study of hydrothermal tre...The usage of plastic-impregnated waste derived solid fuel in conventional combustor is hindered by many technical factors, especially its organic chlorine content. In this paper, experimental study of hydrothermal treatment on mixed plastic waste using the mixture of polypropylene, polystyrene, polyethylene and polyvinyl chloride （PVC） has been performed to observe the dechlorination effect of hydrothermal treatment on the waste. The system was generally applying saturated steam at around 2.4 MPa in a stirring reactor for about 90 minutes. After undergoing the process, the organic chlorine in treated plastic waste was reduced to 1,700 ppm level while the inorganic chlorine content was increased, suggesting an organic chlorine conversion phenomenon to inorganic chlorine, accompanied with low pH due to dehydrochlorination process. Additional limestone （Ca（OH）2） in subsequent experiment showed that the similar phenomenon was occurred but with higher pH and lower chlorine content in the condensed water, suggesting the production of inorganic salt rather than hydrochloric acid. Laboratory scale experiment was also performed to confirm the dechlorination phenomena especially for PVC, and the result showed that the main parameter which affected the dechlorination phenomena was the amount of water in hydrothermal process rather than limestone addition. It is suggested that a combination ofhydrothermal process and alkali addition would produce a low-chlorine solid product from plastic waste, promoting its usage as alternative solid fuel.展开更多
The present work focused on the recycle of the sulfate and the metal ions from acidic wastewater dis charged by nonferrous metallurgical industry. The effects of the temperature, the reactant concentration, the stirri...The present work focused on the recycle of the sulfate and the metal ions from acidic wastewater dis charged by nonferrous metallurgical industry. The effects of the temperature, the reactant concentration, the stirring speed and the metal ions on the reactive crystallization process of calcium sulfate between sulfuric acid and lime were systematically investigated. The morphology of the precipitated crystals evolved from plateletlike and nee dlelike shape to rodlike shape when the temperature was increased from 25 to 70 ℃. An increase in the agglom.展开更多
The lime-depressed pyrite from Cu differential flotation tailings with acid mine drainage(AMD)as a natural activator was recovered.The effect of AMD on lime-depressed pyrite flotation was investigated by a series of l...The lime-depressed pyrite from Cu differential flotation tailings with acid mine drainage(AMD)as a natural activator was recovered.The effect of AMD on lime-depressed pyrite flotation was investigated by a series of laboratory flotation tests and surface analytical techniques.Flotation test results indicated that AMD could effectively activate the pyrite flotation with a sodium butyl xanthate(SBX)collector,and a high-quality sulfur concentrate was obtained.Pulp ion concentration analysis results indicated that AMD facilitated desorption of Ca~(2+)and adsorption of Cu~(2+)on the depressed-pyrite surface.Adsorption measurements and contact angle analysis results confirmed that adding AMD improved the adsorption amount of SBX collector on the pyrite surface and increased the contact angle by 31°.Results of Raman spectroscopy and X-ray photoelectron spectroscopy analysis indicated that AMD treatment promoted the formation of hydrophobic species(S~0 hydrophobic entity and copper sulfides)and the removal of hydrophilic calcium and iron species on the pyrite surface,which reinforced the adsorption of collector.The findings of the present research provide important theoretical basis and technical support for a cleaner production of copper sulfide ores.展开更多
基金Project(201509050)supported by Special Program on Environmental Protection for Public Welfare,ChinaProjects(51474247,51634010)supported by the National Natural Science Foundation of ChinaProject(2015CX001)supported by Grants from the Project of Innovation-driven Plan in Central South University,China
文摘Physicochemical properties and leaching behaviors of two typical arsenic-bearing lime?ferrate sludges(ABLFS),waste acid residue(WAR)and calcium arsenate residue(CAR),are comprehensively described.The chemical composition,morphological features,phase composition and arsenic occurrence state of WAR and CAR are analyzed by ICP?AES,SEM?EDS,XRD,XPS and chemical phase analysis.The toxicity leaching test and three-stage BCR sequential extraction procedure are utilized to investigate arsenic leaching behaviors.The results show that the contents of arsenic in WAR and CAR are2.5%and21.2%and mainly present in the phases of arsenate and arsenic oxides dispersed uniformly or agglomerated in amorphous particles.The leaching concentrations of arsenic excess119and1063times of TCLP standard regulatory level with leaching rates of47.66%and50.15%for WAR and CAR,respectively.About90%of extracted arsenic is in the form of acid soluble and reducible,which is the reason of high arsenic leaching toxicity and environmental activity of ABLFS.This research provides comprehensive information on harmless disposal of ABLFS from industrial wastewater treatment of lime?ferrate process.
文摘The usage of plastic-impregnated waste derived solid fuel in conventional combustor is hindered by many technical factors, especially its organic chlorine content. In this paper, experimental study of hydrothermal treatment on mixed plastic waste using the mixture of polypropylene, polystyrene, polyethylene and polyvinyl chloride （PVC） has been performed to observe the dechlorination effect of hydrothermal treatment on the waste. The system was generally applying saturated steam at around 2.4 MPa in a stirring reactor for about 90 minutes. After undergoing the process, the organic chlorine in treated plastic waste was reduced to 1,700 ppm level while the inorganic chlorine content was increased, suggesting an organic chlorine conversion phenomenon to inorganic chlorine, accompanied with low pH due to dehydrochlorination process. Additional limestone （Ca（OH）2） in subsequent experiment showed that the similar phenomenon was occurred but with higher pH and lower chlorine content in the condensed water, suggesting the production of inorganic salt rather than hydrochloric acid. Laboratory scale experiment was also performed to confirm the dechlorination phenomena especially for PVC, and the result showed that the main parameter which affected the dechlorination phenomena was the amount of water in hydrothermal process rather than limestone addition. It is suggested that a combination ofhydrothermal process and alkali addition would produce a low-chlorine solid product from plastic waste, promoting its usage as alternative solid fuel.
基金Supported by the National High Technology Research and Development Program of China(2011AA060701)the National Water Pollution Control and Management Science Program of China(2009ZX07529-005)
文摘The present work focused on the recycle of the sulfate and the metal ions from acidic wastewater dis charged by nonferrous metallurgical industry. The effects of the temperature, the reactant concentration, the stirring speed and the metal ions on the reactive crystallization process of calcium sulfate between sulfuric acid and lime were systematically investigated. The morphology of the precipitated crystals evolved from plateletlike and nee dlelike shape to rodlike shape when the temperature was increased from 25 to 70 ℃. An increase in the agglom.
基金financially supported from the National Natural Science Foundation of China(No.52164021)the Natural Science Foundation of Yunnan Province,China(No.2019FB078)。
文摘The lime-depressed pyrite from Cu differential flotation tailings with acid mine drainage(AMD)as a natural activator was recovered.The effect of AMD on lime-depressed pyrite flotation was investigated by a series of laboratory flotation tests and surface analytical techniques.Flotation test results indicated that AMD could effectively activate the pyrite flotation with a sodium butyl xanthate(SBX)collector,and a high-quality sulfur concentrate was obtained.Pulp ion concentration analysis results indicated that AMD facilitated desorption of Ca~(2+)and adsorption of Cu~(2+)on the depressed-pyrite surface.Adsorption measurements and contact angle analysis results confirmed that adding AMD improved the adsorption amount of SBX collector on the pyrite surface and increased the contact angle by 31°.Results of Raman spectroscopy and X-ray photoelectron spectroscopy analysis indicated that AMD treatment promoted the formation of hydrophobic species(S~0 hydrophobic entity and copper sulfides)and the removal of hydrophilic calcium and iron species on the pyrite surface,which reinforced the adsorption of collector.The findings of the present research provide important theoretical basis and technical support for a cleaner production of copper sulfide ores.
