Total concentration of heavy metals(Cd, Cr, Cu, Fe, Pb, Ni, Mn and Zn) was estimated in the redeveloping soil of mine spoil under 5 yr old plantations of four woody species namely: Albizia lebbeck, Albizia procera, Te...Total concentration of heavy metals(Cd, Cr, Cu, Fe, Pb, Ni, Mn and Zn) was estimated in the redeveloping soil of mine spoil under 5 yr old plantations of four woody species namely: Albizia lebbeck, Albizia procera, Tectona grandis and Dendrocalamus strictus. The data recorded in the present study were compared with other unplanted coal mine spoil colliery, which was around to the study site and adjoining area of dry tropical forest. Among all the heavy metals, the maximum concentration was found for Fe and minimum for Cd. However, among all four species, total concentrations of these heavy metals were recorded maximally in the plantation plots of T. grandis except for Fe, while minimally in A. lebbeck except for Zn, whereas, the maximum concentration of Fe and Zn was in the plantation plots of D. strictus and A. procera. Statistical analysis revealed significant differences due to species for all the heavy metals except Cu. Among four species, A. lebbeck, A. procera and D. strictus showed more efficient for reducing heavy metal concentrations whereas T. grandis was not more effective to reduce heavy metal concentrations in redeveloping soil of mine spoil.展开更多
A study was conducted on high-density young plantations of three native trees （Albizia lebbeck, Albizia. procera and Tectona grandis） and one native woody grass species （Dendrocalamus strictus） to examine their in...A study was conducted on high-density young plantations of three native trees （Albizia lebbeck, Albizia. procera and Tectona grandis） and one native woody grass species （Dendrocalamus strictus） to examine their influence on total nutrient concentrations of coal mine spoil during early phase of plantation establishment. Soil samples were analyzed for total organic carbon （SOC）, Kjeldahl nitrogen （TKN） and phosphorus （TP） at spoil depths of 0-10 and 10-20 cm under 4- and 5-year-old plantations of all species. A significant effect on concentrations of total SOC, TKN and TP were observed due to plantation age, species and soil depth. However, corresponding con- centrations （SOC, TKN and TP） were substantially lower at spoil profile of 10-20 cm. In comparison, plantation ofA. lebbeck showed greater SOC and nutrient concentrations followed by D. strictus, A. procera and T. grandis, respectively. Therefore, present study clearly indicates attributing qualities of plantation towards improving redeveloping soil of mine spoil varied with species.展开更多
An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer bi...An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer binder concentrations(≤500g/m3) could enhance the air permeability and moisture-retaining capacity of the engineering spoil;however,adding more polymer binder made the hardness of the engineering spoil increase and then decline.With the increase of polymer binder concentrations,the surface(0-5cm) permeability of the engineering spoil decreased but the permeability of the lower layers(5-10cm) increased.Polymer binders might reduce runoff and sediment,but the effect becomes weaker with the increase of rainfall.The results of this study have significance for engineering practices.Further experiments are needed to study the effects of binders under other conditions,such as natural rainfall,different slopes,different rock types,different degrees and spoil weathering and different added material,and the chemical interaction between soil and polymer binders.展开更多
Large spoil tips from reconstruction works as a result of the Wenchuan Earthquake in China are new debris flow hazards to the human society.However,there is a lack of detailed comparative study on debris flow initiati...Large spoil tips from reconstruction works as a result of the Wenchuan Earthquake in China are new debris flow hazards to the human society.However,there is a lack of detailed comparative study on debris flow initiation in different spoil materials.This paper describes a series of tests and analyses on debris flow characteristics(initiation,scale and mechanism) at six sites with limestone and sandstone materials near the Dujiangyan area.Research shows the limestone spoil contains debris flow prone clay content with high concentration of montmorillonite(highly expandable).In addition,limestone spoil is of such a low permeability that water mainly concentrates in the upper surface layer.Those factors make it easy for the increase of pore water pressure,decline of internal friction and conhesion force,leading to the occurence of large debris flows.In contrast,the sandstone spoil is less problematic and causes no major debris flow threats.Based on our research on the mechanism,the"stereometric drainage"method is sucessfully applied to control limestone spoil debris flows.展开更多
Barapukuria Coal Mine situated in the district Dinajpur. Bangladesh is playing an important role in the economy of this country by the mining of top quality coal. With coal mining, mine waste is also generated called ...Barapukuria Coal Mine situated in the district Dinajpur. Bangladesh is playing an important role in the economy of this country by the mining of top quality coal. With coal mining, mine waste is also generated called coal spoil. Coal spoil can impose environmental threat if not treated carefully. In contrast, it can also be converted to value added product. In the present work, coal spoils collected from Barapukuria coal mine drainage water were investigated to determine the quality of the samples by physico-chemical analysis (proximate and ultimate analysis) as well as by heating value determination. 50% of carbon was detected in the samples after elemental analysis, with sulfur content less than 0.4%. Calorific value around 9300 btu/lb was obtained for the coal spoil. Moreover, moisture content, ash, volatile matter content and fixed carbon also provided fruitful information regarding the quality and economic prospect of the samples in comparison to the quality of Barapukuria coal.展开更多
The aim of the experiment is to analyze and view the distribution of gangue withdifferent particle sizes in mine spoil pile cross section.According to the Dimensionalmethod,'Pi'theorem was employed first to ab...The aim of the experiment is to analyze and view the distribution of gangue withdifferent particle sizes in mine spoil pile cross section.According to the Dimensionalmethod,'Pi'theorem was employed first to abbreviate ten physical and mechanical parametersto three dimensionless groups, and then the similarity criterion and coefficient ofthe experiment were determined and calculated based on particle size distribution curve.The similarity model was designed and constructed to represent the process of the minespoil pile.The profile of the final model shows that the small sized particles mainly composethe upper zone of the mine spoil pile, while the bottom of the pile is dominated bybigger sized particles, and the intermediate section presents a zigzag stripe cross-beddingstructure which is composed by small-medium scale particles and medium-large scaleparticles.Each stripe has two critical angles: one is the angle in which gangue particlescan maintain their stability condition, with approximate range from 24° to 26°; and theother is the angle in which particles can stop gliding downwards, approximately varyingfrom 34° to 36°.展开更多
Reclamation and revegetation of a coal mine spoils with various revegetation models utilizing the mycorrhizal technology were studied. The models with different combination of plant species were designed to test the h...Reclamation and revegetation of a coal mine spoils with various revegetation models utilizing the mycorrhizal technology were studied. The models with different combination of plant species were designed to test the hypothesis of speedy revegetation. Root colonization and spore density of arbuscular mycorrhizae (AM) were lowest in plants seeded directly on slopes of the overburden (coal mine dump). At flat surfaces, the mycorrhizal colonization in plant species was higher than that observed at slopes. In other revegetation models, i.e., tree monoculture, tree monoculture + crop species (agroforestry), and two strata plantations (combination of different plant species), maximum AM colonization was recorded for tree species grown along with crop species. This was followed by two strata plantations and tree monoculture. In two strata plantations three categories of AM associations were recognized: 1) every plant in the combination, possessed high mycorrhizal association, 2) only one plant in the combination possessed high mycorrhizal association, and 3) none of the plants in the combination possessed high mycorrhizal association. Azadirachta indica, Pongamia pinnata, Leucaena leucocephala and Acacia catechu were most effective in catching mycorrhizae, and can be used as the effective tool in rehabilitation of the degraded ecosystems.展开更多
In current society where most parents praise children, a father who claims that frequent criticisms and beatings help make his children suc- cessful, has captured the public＇s attention. Xiao Baiyou, a 47-year-old Ho...In current society where most parents praise children, a father who claims that frequent criticisms and beatings help make his children suc- cessful, has captured the public＇s attention. Xiao Baiyou, a 47-year-old Hong Kong businessman, explains his parenting approach in his book That＇s Why They Go to Peking University, which has stirred controversy over his parenting methods since its publication release in June.展开更多
Aiming at the deformation control problem of the tunnel entrance crossing the spoil heap at the Xialao junction,this paper adopts the micropile combined with the coupling beams method to treat the spoiled layers.The r...Aiming at the deformation control problem of the tunnel entrance crossing the spoil heap at the Xialao junction,this paper adopts the micropile combined with the coupling beams method to treat the spoiled layers.The results show that the excavation of the tunnel after the construction of the micropile and coupling beam will cause vertical deformation of the tunnel and the slope surface.The main reason is that the soil layer structure is loose,and the tunnel excavation causes the whole displacement of the loose body.In addition,the buried depth of the tunnel is shallow,so it cannot form an effective soil arch.The stability process after the construction of the micropile method is the process of stress redistribution,and the rock and soil are gradually compressed and compacted.That is,the construction by the micropile method changes the surrounding rock level of the tunnel and reduces the height of the soil arch.Therefore,it is suggested that the tunnel excavation should be carried out when the micropile is constructed after the soil layers are consolidated completely.The micropile method treats the loose spoiled soil at the tunnel entrance,which saves 73%of the total cost compared with the scheme of directly digging out the accumulation,and the economic benefit is very obvious.展开更多
During the highway construction,a large number of spoil areas will be generated while a large amount of waste slag and soil could not be rationally utilized.Besides,the vegetation recovery is slow in the spoil areas d...During the highway construction,a large number of spoil areas will be generated while a large amount of waste slag and soil could not be rationally utilized.Besides,the vegetation recovery is slow in the spoil areas due to the soil depletion.Aiming at recycling the solid waste,the sieved engineering waste slag with local red clay and corn straw biochar was supplied to solve the problem of insufficient nutrients in engineering waste slag and soil.In addition,planting experiments of alfalfa(Medicago sativa L.)and Amorpha fruticosa L.combined with physical and chemical experiments were carried out to prove the feasibility of the novel improved substrate for the reclamation of spoil areas.The results show that the substrate's improvement effect is mainly affected by the soil to slag ratio and the biochar content.The improvement effect of soil matrix in highway spoil area decreases with the increase of the waste slag content,especially when the soil-slag ratio is less than 3,and the promotion of plants is limited.On the contrary,the improvement effect is proportional to the biochar content(3%-8%).But it is noted that the Cu and Pb in the soil will exceed the clean limit corresponding to the Nemero soil pollution index level when the biochar content is 8%.Therefore,it is recommended that the soil-slag ratio should be≥3,and the biochar content should reach 3%-5%.This research provides experimental basis and technical support for utilizing solid waste resources in the reclamation of highway spoil areas.展开更多
The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanx...The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanxi Province, China. X-ray diffraction（XRD） was used to analyze the mineral composition of the coal spoils. The minerals of the coal-spoil samples are mainly kaolinite and quartz, with a minor proportion of pyrite. The batch and column tests were employed to simulate the leaching behavior of trace elements from coal spoils. Elements V, Cr, Zn, As, Pb, and Cd are highly enriched in all coal spoils. The coal spoils also have elevated levels of Ga, Ge, Se, Sn, Hf, and Th. The leachate of coal spoils, fried coal spoils and CSFGM（coal spoils fire gas mineral） samples are acidic, with the p H values ranging between 3.0 and 6.6. The released elements with high concentrations（over 100 μg/L） include Fe, Mn, Co, Ni and Zn, while moderately-released elements are Cu, Se, Mo and As. A high content of heavy metals in batch-test leachate with CSFGM indicates an increased mobility of heavy metals in coal spoil combustion byproduct. Within the first hour washing with the electrolyte solution, a rapid rise of common cations, trace elements, and REEs content, as well as a drop of p H value, in effluent was observed. An increased leaching velocity favors the release of trace elements from coal spoils. In addition, the pulse input of precipitation led to more elements to be released than continuous leaching.展开更多
文摘Total concentration of heavy metals(Cd, Cr, Cu, Fe, Pb, Ni, Mn and Zn) was estimated in the redeveloping soil of mine spoil under 5 yr old plantations of four woody species namely: Albizia lebbeck, Albizia procera, Tectona grandis and Dendrocalamus strictus. The data recorded in the present study were compared with other unplanted coal mine spoil colliery, which was around to the study site and adjoining area of dry tropical forest. Among all the heavy metals, the maximum concentration was found for Fe and minimum for Cd. However, among all four species, total concentrations of these heavy metals were recorded maximally in the plantation plots of T. grandis except for Fe, while minimally in A. lebbeck except for Zn, whereas, the maximum concentration of Fe and Zn was in the plantation plots of D. strictus and A. procera. Statistical analysis revealed significant differences due to species for all the heavy metals except Cu. Among four species, A. lebbeck, A. procera and D. strictus showed more efficient for reducing heavy metal concentrations whereas T. grandis was not more effective to reduce heavy metal concentrations in redeveloping soil of mine spoil.
文摘A study was conducted on high-density young plantations of three native trees （Albizia lebbeck, Albizia. procera and Tectona grandis） and one native woody grass species （Dendrocalamus strictus） to examine their influence on total nutrient concentrations of coal mine spoil during early phase of plantation establishment. Soil samples were analyzed for total organic carbon （SOC）, Kjeldahl nitrogen （TKN） and phosphorus （TP） at spoil depths of 0-10 and 10-20 cm under 4- and 5-year-old plantations of all species. A significant effect on concentrations of total SOC, TKN and TP were observed due to plantation age, species and soil depth. However, corresponding con- centrations （SOC, TKN and TP） were substantially lower at spoil profile of 10-20 cm. In comparison, plantation ofA. lebbeck showed greater SOC and nutrient concentrations followed by D. strictus, A. procera and T. grandis, respectively. Therefore, present study clearly indicates attributing qualities of plantation towards improving redeveloping soil of mine spoil varied with species.
基金NSFC (National natural science foundation of China) for funding(Grant No. 30870467) this paper
文摘An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer binder concentrations(≤500g/m3) could enhance the air permeability and moisture-retaining capacity of the engineering spoil;however,adding more polymer binder made the hardness of the engineering spoil increase and then decline.With the increase of polymer binder concentrations,the surface(0-5cm) permeability of the engineering spoil decreased but the permeability of the lower layers(5-10cm) increased.Polymer binders might reduce runoff and sediment,but the effect becomes weaker with the increase of rainfall.The results of this study have significance for engineering practices.Further experiments are needed to study the effects of binders under other conditions,such as natural rainfall,different slopes,different rock types,different degrees and spoil weathering and different added material,and the chemical interaction between soil and polymer binders.
基金funded by the Ministry of Science and Technology of the People’s Republic of China (Grant No.2011BAK12B02)the Science and Technology Department of Sichuan Province(Grant No.2011SZ0190)
文摘Large spoil tips from reconstruction works as a result of the Wenchuan Earthquake in China are new debris flow hazards to the human society.However,there is a lack of detailed comparative study on debris flow initiation in different spoil materials.This paper describes a series of tests and analyses on debris flow characteristics(initiation,scale and mechanism) at six sites with limestone and sandstone materials near the Dujiangyan area.Research shows the limestone spoil contains debris flow prone clay content with high concentration of montmorillonite(highly expandable).In addition,limestone spoil is of such a low permeability that water mainly concentrates in the upper surface layer.Those factors make it easy for the increase of pore water pressure,decline of internal friction and conhesion force,leading to the occurence of large debris flows.In contrast,the sandstone spoil is less problematic and causes no major debris flow threats.Based on our research on the mechanism,the"stereometric drainage"method is sucessfully applied to control limestone spoil debris flows.
文摘Barapukuria Coal Mine situated in the district Dinajpur. Bangladesh is playing an important role in the economy of this country by the mining of top quality coal. With coal mining, mine waste is also generated called coal spoil. Coal spoil can impose environmental threat if not treated carefully. In contrast, it can also be converted to value added product. In the present work, coal spoils collected from Barapukuria coal mine drainage water were investigated to determine the quality of the samples by physico-chemical analysis (proximate and ultimate analysis) as well as by heating value determination. 50% of carbon was detected in the samples after elemental analysis, with sulfur content less than 0.4%. Calorific value around 9300 btu/lb was obtained for the coal spoil. Moreover, moisture content, ash, volatile matter content and fixed carbon also provided fruitful information regarding the quality and economic prospect of the samples in comparison to the quality of Barapukuria coal.
基金Supported by the National Natural Science Foundation of China(50874102,50974070)
文摘The aim of the experiment is to analyze and view the distribution of gangue withdifferent particle sizes in mine spoil pile cross section.According to the Dimensionalmethod,'Pi'theorem was employed first to abbreviate ten physical and mechanical parametersto three dimensionless groups, and then the similarity criterion and coefficient ofthe experiment were determined and calculated based on particle size distribution curve.The similarity model was designed and constructed to represent the process of the minespoil pile.The profile of the final model shows that the small sized particles mainly composethe upper zone of the mine spoil pile, while the bottom of the pile is dominated bybigger sized particles, and the intermediate section presents a zigzag stripe cross-beddingstructure which is composed by small-medium scale particles and medium-large scaleparticles.Each stripe has two critical angles: one is the angle in which gangue particlescan maintain their stability condition, with approximate range from 24° to 26°; and theother is the angle in which particles can stop gliding downwards, approximately varyingfrom 34° to 36°.
文摘Reclamation and revegetation of a coal mine spoils with various revegetation models utilizing the mycorrhizal technology were studied. The models with different combination of plant species were designed to test the hypothesis of speedy revegetation. Root colonization and spore density of arbuscular mycorrhizae (AM) were lowest in plants seeded directly on slopes of the overburden (coal mine dump). At flat surfaces, the mycorrhizal colonization in plant species was higher than that observed at slopes. In other revegetation models, i.e., tree monoculture, tree monoculture + crop species (agroforestry), and two strata plantations (combination of different plant species), maximum AM colonization was recorded for tree species grown along with crop species. This was followed by two strata plantations and tree monoculture. In two strata plantations three categories of AM associations were recognized: 1) every plant in the combination, possessed high mycorrhizal association, 2) only one plant in the combination possessed high mycorrhizal association, and 3) none of the plants in the combination possessed high mycorrhizal association. Azadirachta indica, Pongamia pinnata, Leucaena leucocephala and Acacia catechu were most effective in catching mycorrhizae, and can be used as the effective tool in rehabilitation of the degraded ecosystems.
文摘In current society where most parents praise children, a father who claims that frequent criticisms and beatings help make his children suc- cessful, has captured the public＇s attention. Xiao Baiyou, a 47-year-old Hong Kong businessman, explains his parenting approach in his book That＇s Why They Go to Peking University, which has stirred controversy over his parenting methods since its publication release in June.
基金support from the Ministry of Transport of the People's Republic of China(Grant no.2021-ZD1-014)Key Research and Development Program of Guangxi(Grant no.2021AB22117).
文摘Aiming at the deformation control problem of the tunnel entrance crossing the spoil heap at the Xialao junction,this paper adopts the micropile combined with the coupling beams method to treat the spoiled layers.The results show that the excavation of the tunnel after the construction of the micropile and coupling beam will cause vertical deformation of the tunnel and the slope surface.The main reason is that the soil layer structure is loose,and the tunnel excavation causes the whole displacement of the loose body.In addition,the buried depth of the tunnel is shallow,so it cannot form an effective soil arch.The stability process after the construction of the micropile method is the process of stress redistribution,and the rock and soil are gradually compressed and compacted.That is,the construction by the micropile method changes the surrounding rock level of the tunnel and reduces the height of the soil arch.Therefore,it is suggested that the tunnel excavation should be carried out when the micropile is constructed after the soil layers are consolidated completely.The micropile method treats the loose spoiled soil at the tunnel entrance,which saves 73%of the total cost compared with the scheme of directly digging out the accumulation,and the economic benefit is very obvious.
基金supported by the National Natural Science Foundation of China(Grant No.52078034).
文摘During the highway construction,a large number of spoil areas will be generated while a large amount of waste slag and soil could not be rationally utilized.Besides,the vegetation recovery is slow in the spoil areas due to the soil depletion.Aiming at recycling the solid waste,the sieved engineering waste slag with local red clay and corn straw biochar was supplied to solve the problem of insufficient nutrients in engineering waste slag and soil.In addition,planting experiments of alfalfa(Medicago sativa L.)and Amorpha fruticosa L.combined with physical and chemical experiments were carried out to prove the feasibility of the novel improved substrate for the reclamation of spoil areas.The results show that the substrate's improvement effect is mainly affected by the soil to slag ratio and the biochar content.The improvement effect of soil matrix in highway spoil area decreases with the increase of the waste slag content,especially when the soil-slag ratio is less than 3,and the promotion of plants is limited.On the contrary,the improvement effect is proportional to the biochar content(3%-8%).But it is noted that the Cu and Pb in the soil will exceed the clean limit corresponding to the Nemero soil pollution index level when the biochar content is 8%.Therefore,it is recommended that the soil-slag ratio should be≥3,and the biochar content should reach 3%-5%.This research provides experimental basis and technical support for utilizing solid waste resources in the reclamation of highway spoil areas.
基金financially supported by the National Natural Science Foundation of China(Nos.41120124003 and 41372251)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20130145120014)+1 种基金the Natural Science Foundation of Hubei Province,China(No.2013CFB41)the Opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(No.SKLGP2012K022)
文摘The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanxi Province, China. X-ray diffraction（XRD） was used to analyze the mineral composition of the coal spoils. The minerals of the coal-spoil samples are mainly kaolinite and quartz, with a minor proportion of pyrite. The batch and column tests were employed to simulate the leaching behavior of trace elements from coal spoils. Elements V, Cr, Zn, As, Pb, and Cd are highly enriched in all coal spoils. The coal spoils also have elevated levels of Ga, Ge, Se, Sn, Hf, and Th. The leachate of coal spoils, fried coal spoils and CSFGM（coal spoils fire gas mineral） samples are acidic, with the p H values ranging between 3.0 and 6.6. The released elements with high concentrations（over 100 μg/L） include Fe, Mn, Co, Ni and Zn, while moderately-released elements are Cu, Se, Mo and As. A high content of heavy metals in batch-test leachate with CSFGM indicates an increased mobility of heavy metals in coal spoil combustion byproduct. Within the first hour washing with the electrolyte solution, a rapid rise of common cations, trace elements, and REEs content, as well as a drop of p H value, in effluent was observed. An increased leaching velocity favors the release of trace elements from coal spoils. In addition, the pulse input of precipitation led to more elements to be released than continuous leaching.
