In order to understand the mechanism and regularity of the groundwater contamination from mine water of abandoned mines, experiments were conducted on an abandoned coal mine in Fuxin, a representative city with lots o...In order to understand the mechanism and regularity of the groundwater contamination from mine water of abandoned mines, experiments were conducted on an abandoned coal mine in Fuxin, a representative city with lots of mine water in northeast China. The groundwater pollution from different contaminants of coal-mining voids （total hardness, SO4^2-, CI^- and total Fe） and pollution factors transportation situation in the coal rock were simulated by soil column experiment under the conditions of mine water leaching and main water leaching （similar to rainwater leaching）, and the water-rock interaction mechanism was discussed during mine water infiltration through saturated coal rock by application of principle of mass conservation, based on physical properties of coal rock, as well as monitored chemical composition. The results show that, compared with the clear water leaching process, trends of change in pollutant concentrations presented different characteristics in the mine water leaching process. Groundwater is contaminated by the water rock interactions such as migration ＆ accumulation, adsorption ＆ transformation, dissolution ＆ desorption and ion exchange during the mine water permeation. The experiments also suggest that at first dissolution rate of some kinds of dissoluble salts is high, but it decreases with leaching time, even to zero during both the mine water leaching and main water leaching.展开更多
The behaviour of timber columns subjected to freeze-thaw cycles under axial compression is presented in this paper.A total of forty specimens,including twenty circular timber columns and twenty square timber columns,w...The behaviour of timber columns subjected to freeze-thaw cycles under axial compression is presented in this paper.A total of forty specimens,including twenty circular timber columns and twenty square timber columns,were tested under axial compression.The failure modes,ultimate bearing capacity,ductility coefficient,load-displacement curves and load-strain curves were obtained and analyzed.The number of freeze-thaw cycles(from 0 to 80)and the specimens’height(from 225 mm to 360 mm)were considered as the main parameters.After freeze-thaw cycles,there was no obvious change on the surface of the timber columns.The test results showed that freeze-thaw cycles could reduce the ultimate bearing capacity of the timber columns,and the average reduction of the ultimate bearing capacity of the specimen reached 28%.The ductility coefficient of the square specimens subjected to freeze-thaw cycles almost remains constant compared with that of the square timber columns left untreated.While the ductility coefficient of the circular timber columns increases after freeze-thaw cycles.In addition,based on the extensive experimental analysis,a regression formula is derived to predict the ultimate bearing capacity of the timber columns after being subjected to freeze-thaw cycles,which is proved to be reasonable accurate.展开更多
Fine particle flotation has been one of the main problems in many mineral processing plants.The bubble particle collision rate is very low for fine particles,which reduces flotation efficiency.Also,the existence of sl...Fine particle flotation has been one of the main problems in many mineral processing plants.The bubble particle collision rate is very low for fine particles,which reduces flotation efficiency.Also,the existence of slimes is,generally,detrimental to the flotation process,affecting the selectivity and the quality of the concentrates.Besides,it causes an increase in reagents consumption.Hence,in most of processing plants,some of these particles are transmitted to the tailing ponds to reduce the effects of these problems and increase the selectivity of the process.Esfordi phosphate plant in Iran loses more than 30%of its capacity as particles with d 80 finer than 30μm.These fine particles with 15.9%P_(2)O_(5)content are transferred to tailing dam.Processing of fine particles is very important for phosphate industry from economic and environmental aspects.This study addressed the processing of fine tailings(slimes)from a phosphate ore concentrator via flotation,despite the traditional view that ultrafine particles do not float.Phosphate flotation performances in the presence and absence of nanobubbles(NBs)in both mechanical and column cells were compared according to the metallurgical results of the process.NBs(generated by hydrodynamic cavitation)have interesting and exclusive properties such as high stability,durability and high surface area per volume,leading to increase of their utilization in mining-metallurgy and environmental areas.The results of this study revealed that,in the absence of NBs,a concentrate containing 26.9%P_(2)O_(5)with a recovery of 29.13%was obtained using mechanical cells in comparison to 31.6%P_(2)O_(5)with a recovery of 32.74%obtained using column flotation.In the presence of NBs,the recoveries of the concentrate of the mechanical and column flotation increased to 40.49%and 41.26%with 28.47%and 30.43%P_(2)O_(5)contents,respectively.Comparative study showed that the column flotation was almost more efficient for processing the phosphate ore in the presence of the NBs,and had thicker froth layer compared to the mechanical flotation.展开更多
基金the National Natural Science Foundation of China(50434020,50374042)Science & Technology Found of Liaoning Province(20022155)Specialized Research Fund for the Doctoral Program of Higher Education(20040147003)
文摘In order to understand the mechanism and regularity of the groundwater contamination from mine water of abandoned mines, experiments were conducted on an abandoned coal mine in Fuxin, a representative city with lots of mine water in northeast China. The groundwater pollution from different contaminants of coal-mining voids （total hardness, SO4^2-, CI^- and total Fe） and pollution factors transportation situation in the coal rock were simulated by soil column experiment under the conditions of mine water leaching and main water leaching （similar to rainwater leaching）, and the water-rock interaction mechanism was discussed during mine water infiltration through saturated coal rock by application of principle of mass conservation, based on physical properties of coal rock, as well as monitored chemical composition. The results show that, compared with the clear water leaching process, trends of change in pollutant concentrations presented different characteristics in the mine water leaching process. Groundwater is contaminated by the water rock interactions such as migration ＆ accumulation, adsorption ＆ transformation, dissolution ＆ desorption and ion exchange during the mine water permeation. The experiments also suggest that at first dissolution rate of some kinds of dissoluble salts is high, but it decreases with leaching time, even to zero during both the mine water leaching and main water leaching.
基金supported by the National Natural Science Foundation of China(No.51778066).
文摘The behaviour of timber columns subjected to freeze-thaw cycles under axial compression is presented in this paper.A total of forty specimens,including twenty circular timber columns and twenty square timber columns,were tested under axial compression.The failure modes,ultimate bearing capacity,ductility coefficient,load-displacement curves and load-strain curves were obtained and analyzed.The number of freeze-thaw cycles(from 0 to 80)and the specimens’height(from 225 mm to 360 mm)were considered as the main parameters.After freeze-thaw cycles,there was no obvious change on the surface of the timber columns.The test results showed that freeze-thaw cycles could reduce the ultimate bearing capacity of the timber columns,and the average reduction of the ultimate bearing capacity of the specimen reached 28%.The ductility coefficient of the square specimens subjected to freeze-thaw cycles almost remains constant compared with that of the square timber columns left untreated.While the ductility coefficient of the circular timber columns increases after freeze-thaw cycles.In addition,based on the extensive experimental analysis,a regression formula is derived to predict the ultimate bearing capacity of the timber columns after being subjected to freeze-thaw cycles,which is proved to be reasonable accurate.
基金Project supported by Iran Mineral Processing Research Center(IMPRC)。
文摘Fine particle flotation has been one of the main problems in many mineral processing plants.The bubble particle collision rate is very low for fine particles,which reduces flotation efficiency.Also,the existence of slimes is,generally,detrimental to the flotation process,affecting the selectivity and the quality of the concentrates.Besides,it causes an increase in reagents consumption.Hence,in most of processing plants,some of these particles are transmitted to the tailing ponds to reduce the effects of these problems and increase the selectivity of the process.Esfordi phosphate plant in Iran loses more than 30%of its capacity as particles with d 80 finer than 30μm.These fine particles with 15.9%P_(2)O_(5)content are transferred to tailing dam.Processing of fine particles is very important for phosphate industry from economic and environmental aspects.This study addressed the processing of fine tailings(slimes)from a phosphate ore concentrator via flotation,despite the traditional view that ultrafine particles do not float.Phosphate flotation performances in the presence and absence of nanobubbles(NBs)in both mechanical and column cells were compared according to the metallurgical results of the process.NBs(generated by hydrodynamic cavitation)have interesting and exclusive properties such as high stability,durability and high surface area per volume,leading to increase of their utilization in mining-metallurgy and environmental areas.The results of this study revealed that,in the absence of NBs,a concentrate containing 26.9%P_(2)O_(5)with a recovery of 29.13%was obtained using mechanical cells in comparison to 31.6%P_(2)O_(5)with a recovery of 32.74%obtained using column flotation.In the presence of NBs,the recoveries of the concentrate of the mechanical and column flotation increased to 40.49%and 41.26%with 28.47%and 30.43%P_(2)O_(5)contents,respectively.Comparative study showed that the column flotation was almost more efficient for processing the phosphate ore in the presence of the NBs,and had thicker froth layer compared to the mechanical flotation.
