Objective Authigenic pyrite often develops extensively in marine sediments,which is an important product of sulfate reduction in an anoxic environment.It has a specific appearance and complicated sulfur isotopic prope...Objective Authigenic pyrite often develops extensively in marine sediments,which is an important product of sulfate reduction in an anoxic environment.It has a specific appearance and complicated sulfur isotopic properties,and acts as important evidence of methane seep in marine sediments.Strong AOM（anaerobic oxidation of methane）activity has developed in the Okinawa Trough.展开更多
One of the contaminants in coal is sulphur. The adverse impact of sulfur on coal, such as environmental pollution, degradation of steel quality, and reduction of coal’s thermal value, has led to the attention of sulf...One of the contaminants in coal is sulphur. The adverse impact of sulfur on coal, such as environmental pollution, degradation of steel quality, and reduction of coal’s thermal value, has led to the attention of sulfur separation methods in recent decades. Leaching (chemical dissolution) is one of the best methods for desulfurising coal, reducing sulfur in coal. In this study, hydrogen peroxide as an oxidising agent on sulfuric acid yield in reducing sulfur types of coal and chemical structure and the organic texture of high sulfur coal was investigated. The experiments were designed using a three-level response surface methodology with four duplicate points and 27 experiments. The independent variables studied were temperature, time, stirring speed and ratio of sulfuric acid to hydrogen peroxide. Dependent variables included reduction percentage of total, pyritic and organic sulfur. This study showed that 99.99% of total sulfur, 30.11% of pyritic sulfur and 69.08% of organic sulfur were reduced. These values were obtained at a temperature of 60°C, time 120 min, stirring speed 200 rpm and 3:1 ratio of sulfuric acid to hydrogen peroxide. Significant changes were observed by infrared spectroscopy (FTIR) of the coal structure before and after desulphurisation. On the other hand, the studies showed no specific changes in the bonds related to the organic coal matrix. The results showed that this method could be used as a secure process for removing inorganic and organic sulfur without destroying the organic coal matrix.展开更多
High-sulfur and low-grade pyrite cinders are the waste products of sulfuric acid manufacturing plants.Many valuable components,such as iron oxide,are contained in pyrite cinders and difficult to be separated and purif...High-sulfur and low-grade pyrite cinders are the waste products of sulfuric acid manufacturing plants.Many valuable components,such as iron oxide,are contained in pyrite cinders and difficult to be separated and purified just via the high temperature roasting process.Considering this,an innovative method including water-washing,aqua regia leaching,hydrothermal alkali activation and acid-washing was developed.And the effects of different parameters on recovery efficiency of iron oxide were systematically investigated.The optimum parameters were proposed as follows：water rinse-leaching at room temperature for 5-20 min,and melting at 160 ℃ for 2.0h with NaOH（concentration of 30mass%）,followed by leaching with aqua regia solution（3.0vol.%）for 1.0h.After the treatment,the content of iron oxides increased from 54.3to 96.0mass% with the recovery rate exceeding 85%.Meanwhile,calcium sulphate was recovered as the high value-added products by alkali extraction liquid.Furthermore,the phase transformation and microstructure of the samples in the process were studied by physicochemical methods to reveal the separation mechanisms of different components in the pyrite cinders.展开更多
基金supported by the National Natural Science Foundation of China (grants No.41306062 and 41474119)the Key Laboratory of Gas Hydrate Foundation (grant No.SHW[2014]-DX-04)
文摘Objective Authigenic pyrite often develops extensively in marine sediments,which is an important product of sulfate reduction in an anoxic environment.It has a specific appearance and complicated sulfur isotopic properties,and acts as important evidence of methane seep in marine sediments.Strong AOM（anaerobic oxidation of methane）activity has developed in the Okinawa Trough.
文摘One of the contaminants in coal is sulphur. The adverse impact of sulfur on coal, such as environmental pollution, degradation of steel quality, and reduction of coal’s thermal value, has led to the attention of sulfur separation methods in recent decades. Leaching (chemical dissolution) is one of the best methods for desulfurising coal, reducing sulfur in coal. In this study, hydrogen peroxide as an oxidising agent on sulfuric acid yield in reducing sulfur types of coal and chemical structure and the organic texture of high sulfur coal was investigated. The experiments were designed using a three-level response surface methodology with four duplicate points and 27 experiments. The independent variables studied were temperature, time, stirring speed and ratio of sulfuric acid to hydrogen peroxide. Dependent variables included reduction percentage of total, pyritic and organic sulfur. This study showed that 99.99% of total sulfur, 30.11% of pyritic sulfur and 69.08% of organic sulfur were reduced. These values were obtained at a temperature of 60°C, time 120 min, stirring speed 200 rpm and 3:1 ratio of sulfuric acid to hydrogen peroxide. Significant changes were observed by infrared spectroscopy (FTIR) of the coal structure before and after desulphurisation. On the other hand, the studies showed no specific changes in the bonds related to the organic coal matrix. The results showed that this method could be used as a secure process for removing inorganic and organic sulfur without destroying the organic coal matrix.
基金Item Sponsored by National Natural Science Foundation of China(50904054)
文摘High-sulfur and low-grade pyrite cinders are the waste products of sulfuric acid manufacturing plants.Many valuable components,such as iron oxide,are contained in pyrite cinders and difficult to be separated and purified just via the high temperature roasting process.Considering this,an innovative method including water-washing,aqua regia leaching,hydrothermal alkali activation and acid-washing was developed.And the effects of different parameters on recovery efficiency of iron oxide were systematically investigated.The optimum parameters were proposed as follows：water rinse-leaching at room temperature for 5-20 min,and melting at 160 ℃ for 2.0h with NaOH（concentration of 30mass%）,followed by leaching with aqua regia solution（3.0vol.%）for 1.0h.After the treatment,the content of iron oxides increased from 54.3to 96.0mass% with the recovery rate exceeding 85%.Meanwhile,calcium sulphate was recovered as the high value-added products by alkali extraction liquid.Furthermore,the phase transformation and microstructure of the samples in the process were studied by physicochemical methods to reveal the separation mechanisms of different components in the pyrite cinders.
