Frothers facilitate the reduction of bubbles size by preventing bubbles coalescence and produce more stable froths.The collision probability of the bubbles and particles substantially increases by decreasing bubble si...Frothers facilitate the reduction of bubbles size by preventing bubbles coalescence and produce more stable froths.The collision probability of the bubbles and particles substantially increases by decreasing bubble size.For the same volume system,fewer bubbles result from a distribution of large-sized bubbles,and more bubbles result from a distribution of small-sized bubbles.In this research,fundamental two-phase frother characterization parameters were aimed to link with three-phase coal and talc flotation behavior.For this purpose,the effect of single and dual frother systems on inhibiting bubble coalescence was investigated with methyl isobutyl carbinol(MIBC),isooctanol(2 ethyl hexanol),pine oil,and Dowfroth 250.Based on the results of single frothers,isooctanol at the lowest critical coalescence concentration(CCC)value of 6×10^(−6) achieved the smallest bubbles with Sauter mean diameter of 0.80 mm.By blending Dowfroth 250 and pine oil,the bubbles size decreased significantly,reaching 0.45 mm.While the highest recoveries in coal flotation were obtained in single and frother blends where the bubbles size was measured as the smallest in two-phase system,and such a relationship was not found for talc flotation.展开更多
Despite the abundant water resources available in Lebanon, it still faces a water shortage. Pollution is one of the main stresses on Lebanon’s water resources. This study was carried out in Nabaa El Tasseh Spring, th...Despite the abundant water resources available in Lebanon, it still faces a water shortage. Pollution is one of the main stresses on Lebanon’s water resources. This study was carried out in Nabaa El Tasseh Spring, the main water supply source in the Nabatiyeh Region. The aim of this study is to assess water quality of the spring of Nabaa El Tasseh during winter and spring seasons to determine the Water Quality Index (WQI). At the Environmental Laboratory of Lebanese University, Faculty of Agronomy, water was tested physiochemical parameters including temperature, hydrogen potential (pH), electrical conductivity (EC), total dissolved solids (TDS), anions (NO3−, Cl−, SO42−), and cations (Mg2+, Ca2+, Na+, K+ and Fe2+). The majority of the physical and chemical parameters under investigation fell below the international and Lebanese norms, including WHO recommendations. Additionally, fecal Streptococcus, total coliforms, and fecal coliforms were determined using microbiological testing. Due to its proximity to agricultural activities, the Nabaa El Tasseh Spring water was contaminated by total coliforms. Fecal Coliforms and Fecal Streptococcus, on the other hand, are a sign of animal or human sewage contamination in groundwater. WQI was calculated using the Weighted Arithmetic Index approach. This study has shown that water quality in Nabaa El Tasseh Spring was not acceptable for consumption without treatment in February 2019 with WQI values equal to 88.608, but it became 31.51 acceptable during April and 18.22 in December 2022. An index is a useful tool for conveying water quality information to the public and legislative decision-makers. Although the WQI is excellent in the spring, there is microbiological pollution, thus water treatment is required. The results indicated that Principal Component Analysis (PCA) could clearly explain the pollution trends in the spring over several months. The study’s findings indicate that before the water of Nabaa El Tasseh Spring can be used for drinking or residential purposes, it must first undergo extensive treatment.展开更多
Gold concentration usually consists of gravity separation, flotation, cyanidation, or the combination of these processes. The choice among these processes depends on the mineralogical characterization and gold content...Gold concentration usually consists of gravity separation, flotation, cyanidation, or the combination of these processes. The choice among these processes depends on the mineralogical characterization and gold content of the ore. Recently, the recovery of gold using gravity methods has gained attention because of low cost and environmentally friendly operations. In this study, gold pre-concentrates were produced by the stepwise gravity separation and flotation techniques. The Knelson concentrator and conventional flotation were employed for the recovery of gold. Gold bearing ore samples were taken from Gümüshane Region, northern east part of Turkey. As a result of stepwise Knelson concentration experiments, a gold concentrate assaying around 620 g/t is produced with 41.4wt% recovery. On the other hand, a gold concentrate about 82 g/t is obtained with 89.9wt% recovery from a gold ore assaying 6 g/t Au by direct flotation.展开更多
In order to study pillar and overburden response to retreat mining, a ground control program was conducted at a Central Appalachian Mine. The program consisted of several monitoring methods including a seismic monitor...In order to study pillar and overburden response to retreat mining, a ground control program was conducted at a Central Appalachian Mine. The program consisted of several monitoring methods including a seismic monitoring system, borehole pressure cells in the pillars, and time-lapse photogrammetry of the pillar ribs. Two parallel geophone arrays were installed, one on each side of the panel with the sensors mounted 3 m into the roof. A total of fourteen geophones recorded more than 5000 events during the panel retreat. A MIDAS datalogger was used to record pressure from borehole pressure cells(BPCs)located in two adjacent pillars that were not mined during retreat. A series of photographs were taken of the pillars that had the BPCs as the face approached so that deformation of the entire rib could be monitored using photogrammetry. Results showed that pillar stability and cave development were as expected. The BPCs showed an increase in loading when the face was 115 m inby and a clear onset of the forward abutment at 30 m. The photogrammetry results displayed pillar deformation corresponding to the increased loading. The microseismic monitoring results showed the overburden caving inby the face, again as expected. The significance of these results lies in two points,(1) we can quantify the safe manner in which this mine is conducting retreating operations, and(2) we can use volumetric technologies(photogrammetry and microseismic) to monitor entire volumes of the mine in addition to the traditional point-location geotechnical measurements(BPCs).展开更多
Misreported pyrite into copper concentrates dramatically declines copper grade and recovery. Copper flotation can be also more complicated if flotation feed comes from an elevated-pyritic copper ore. In this investiga...Misreported pyrite into copper concentrates dramatically declines copper grade and recovery. Copper flotation can be also more complicated if flotation feed comes from an elevated-pyritic copper ore. In this investigation, the effect of two different ore types(high pyritic and low pyritic feeds) was studied on rougher stage of industrial copper flotation circuit. Samples were taken from different streams and the structure of chalcopyrite within the pyrite and non-sulfide gangue minerals was examined in various size fractions for mentioned ore types. Results indicated that 72% and 56% of the total floated pyrite was transferred to concentrate in first four cells in the low and high pyritic feeds, respectively. Whereas, this proportion for floated SiO_2 in last ten cells was detected as 72% and 71%, respectively. A detailed interpretation of the effect of locked particles in different size fractions on rougher flotation cells is studied from industrial point of view.展开更多
The distribution of the various organic and inorganic constituents and their influences on the combustion of coal has been comprehensively studied.However,the combustion characteristics of pulverized coal depend not o...The distribution of the various organic and inorganic constituents and their influences on the combustion of coal has been comprehensively studied.However,the combustion characteristics of pulverized coal depend not only on rank but also on the composition,distribution,and combination of the macerals.Unlike the proximate and ultimate analyses,determining the macerals in coal involves the use of sophisticated microscopic instrumentation and expertise.In this study,an attempt was made to predict the amount of macerals(vitrinite,inertinite,and liptinite)and total mineral matter from the Witbank Coalfields samples using the multiple input single output white-box artificial neural network(MISOWB-ANN),gene expression programming(GEP),multiple linear regression(MLR),and multiple nonlinear regression(MNLR).The predictive models obtained from the multiple soft computing models adopted are contrasted with one another using difference,efficiency,and composite statistical indicators to examine the appropriateness of the models.The MISOWB-ANN provides a more reliable predictive model than the other three models with the lowest difference and highest efficiency and composite statistical indicators.展开更多
In this paper,the effect of various electrochemical environments in the galena flotation is investigated.The electrochemical environments consisted of a ball mill for grinding of galena ore and a Denver flotation cell...In this paper,the effect of various electrochemical environments in the galena flotation is investigated.The electrochemical environments consisted of a ball mill for grinding of galena ore and a Denver flotation cell for flotation of galena in the laboratory scale.In order to achieve the maximum recovery with sodium hyposulfite,the concentrations of 0.06 and 0.12 M of air and nitrogen gases have been used to control the pulp potential in the Denver flotation cell.The galena sample was from the ''Era mine'' which is located in the Kiyasar area,north of Iran.This mine contains:Galena(PbS) at least 22%,Fluorite(CaF 2) 73.37%,Quartz(SiO 2) 2.54% and other minerals such as Cerussite(PbCO 3) and Kaolinite(Al 2 Si 2 O 5(OH) 4).Flotation of Galena was conducted in a 0.12 M of sodium hyposulfite solution.It was found that the amount of recovery by this process was 85% and 63% in the presence and absence of potassium amyl xanthate(KAX) and at an estimated potential of 280 to 350 mV respectively while the recovery was 70% and 52% at an approximate potential of 175 to 210 mV in water in the presence and absence of collector(KAX).展开更多
Numerical solution of yield viscoplastic fluid flow is hindered by the singularity inherent to the Herschel-Bulkley model. A finite difference method over the boundary-fitted orthogonal coordinate system is util- ized...Numerical solution of yield viscoplastic fluid flow is hindered by the singularity inherent to the Herschel-Bulkley model. A finite difference method over the boundary-fitted orthogonal coordinate system is util- ized to investigate numerically the fully developed steady flow of non-Newtonian yield viscoplastic fluid through concentric and eccentric annuli. The fluid rheology is described with the Herschel-Bulkley model. The numerical simulation based on a continuous viscoplastic approach to the Herschel-Bulkley model is found in poor accordance with the experimental data on volumetric flow rate of a bentonite suspension. A strict mathematical model for Herschel-Bulkley fluid flow is established and the corresponding numerical procedures are proposed. However, only the case of flow of a Herschel-Bulkley fluid in a concentric annulus is resolved based on the presumed flow stnicture by using the common optimization technique. Possible flow structures in an eccentric afinulus are presumed, and further challenges in numerical simulation of the Herschel-Bulkley fluid flow are suggested.展开更多
The Kuvasali landslide disaster in Malava, Western Kenya, which caused harmful geo-environmental hazards to the villagers in August 2007, formed the premise of this paper. The existing landslide vulnerability occurren...The Kuvasali landslide disaster in Malava, Western Kenya, which caused harmful geo-environmental hazards to the villagers in August 2007, formed the premise of this paper. The existing landslide vulnerability occurrence ratings have been identified and documented using participatory approaches to ascertain the adoptive indigenous methods, which helped mitigation against the negative impacts by determining the slope steepness using Abney level. The geological set up, settlement and climatic factors, relating to landslides, revealed that the affected homesteads were on a steep slope of approximately 70%, with underlying metamorphosed basement rocks comprising ofgneisses, schists and granite intrusions. The steep escarpment overlying these rocks, where the landslide occurred, consists of volcanic rocks and black cotton clayey soils. The slope has scattered vegetation cover due to farming, while the low-lying area is planted with sugar cane and maize plantations. The landslide disaster led to loss of lives, injuries and damage to property. Natural resources, including water points, suffered siltation. Mitigation measures such as geo-hazard mapping and zoning, awareness training and campaigns for the local people focusing on hazard-prone areas resulting from poor land use practices have been recommended.展开更多
The indiscriminate disposal of plastic waste poses significant environmental and economic threats,necessitating innovative recycling strategies that align with circular economy principles.The primary objective was to ...The indiscriminate disposal of plastic waste poses significant environmental and economic threats,necessitating innovative recycling strategies that align with circular economy principles.The primary objective was to assess the im-pact of varying plastic-to-sand ratios on the compressive strength of these com posite pavement blocks,optimising resource utilisation.These objectives were achieved through research investigating the feasibility of utilising four com-mon post-consumer thermoplastics-HDPE,PP,PET,and PS,as binding agents in pavement block production.This directly addresses the circular economy imperative by transforming waste into a valuable construction resource,mini-mising landfill burden,and creating a closed-loop system.Compared with con-ventional concrete pavers,these plastic-sand blocks offer the potential for a reduced carbon footprint by valorising waste materials and potentially decreas-ing reliance on energy-intensive cement production.The methodology in-volved melting each plastic type individually and combining it with sand at five different ratios:3:7,4:6,5:5,6:4,and 7:3(plastic:sand).The resulting mixtures were moulded into pavement blocks and subjected to compressive strength test-ing.One-way ANOVA revealed varying optimal plastic-to-sand ratios for HDPE,PP,PET,and PS pavement blocks,as determined by compressive strength anal-ysis.For HDPE,while ratios of 30:70,50:50,60:40,and 70:30 showed compara-ble performance,and the 40:60 combination exhibited the highest compressive strength.In contrast,PP mixtures demonstrated optimal strength at a 60:40 ratio,with the 40:60,50:50,and 70:30 ratios showing similar behaviour that could be substituted.PET mixtures achieved peak strength at a 30:70 ratio,and only the 40:60 and 70:30 ratio combinations could be substituted without impacting the compressive strength.Similarly,PS mixtures exhibited optimal performance at a 50:50 ratio,with some substitution potential observed at 30:70,40:60,60:40,and 70:30 ratios.These findings demonstrate that specific plastic types have unique optimal mixing ratios with sand to achieve maximal compressive strength,thereby transforming plastic waste into durable pavement blocks that support a circular economy.展开更多
A microseismic monitoring system was installed in an underground room and pillar coal mine in the Eastern United States to analyze the occurrence and characteristics of induced seismicity during the retreat of two pan...A microseismic monitoring system was installed in an underground room and pillar coal mine in the Eastern United States to analyze the occurrence and characteristics of induced seismicity during the retreat of two panels in the mine.This study is the first microseismic monitoring effort at an underground coal mine in nearly 30 years.During the retreat of the first panel,an array of eight uniaxial geophones,installed 10 ft.into the roof,recorded events and their magnitudes.The second panel was monitored using an array of twelve uniaxial geophones and two triaxial geophones,also installed 10 ft.into the roof.Comparing the results of these studies,it has been found that the magnitude of seismic events is minimally affected by immediate roof geology or depth of cover.However,it was observed in both studies that the rate at which seismic events occurred did vary with changing roof geology and depth of cover.Using the seismic data from the second panel retreat,focal mechanism solutions were generated for 50 hand-picked events in order to determine if the failure was in compression,tension,or shear.Results of the focal mechanism solutions show that stress relief resulting in dilational events occurs at significant depths,150-200 m in this case,beneath the active mining face.展开更多
In estimating emissions reductions brought about by renewables in China, much of existing research assumes that renewables displace coal power. In this paper, this assumption is challenged and the potential environmen...In estimating emissions reductions brought about by renewables in China, much of existing research assumes that renewables displace coal power. In this paper, this assumption is challenged and the potential environmental effects of photovoltaic （PV） power in North-west China are reevaluated when the marginal generator actually being displaced is taken into account. The annual PV power generation in the North-west Grid is estimated, in this paper, to be as high as 17900GW.h in 2015, roughly equaling to the output of 1.5 nuclear power plants in the US today. The total associated emission reduction in 2015 will at most be 0.36 percent of SO2 and 0.25 percent of NOx emissions from their 2010 levels in China. Further, PV power may render no emissions reduction at all if it displaces hydropower, which is often used to meet peak demand in the North-west Grid in China. These results imply that a more cost-effective area of focus in the short- term may be on desulfurization and denitrification technologies for coal plants.展开更多
基金Project(ID42787)supported by the Istanbul Technical University,BAP(Scientific Research Project)Department,Turkey。
文摘Frothers facilitate the reduction of bubbles size by preventing bubbles coalescence and produce more stable froths.The collision probability of the bubbles and particles substantially increases by decreasing bubble size.For the same volume system,fewer bubbles result from a distribution of large-sized bubbles,and more bubbles result from a distribution of small-sized bubbles.In this research,fundamental two-phase frother characterization parameters were aimed to link with three-phase coal and talc flotation behavior.For this purpose,the effect of single and dual frother systems on inhibiting bubble coalescence was investigated with methyl isobutyl carbinol(MIBC),isooctanol(2 ethyl hexanol),pine oil,and Dowfroth 250.Based on the results of single frothers,isooctanol at the lowest critical coalescence concentration(CCC)value of 6×10^(−6) achieved the smallest bubbles with Sauter mean diameter of 0.80 mm.By blending Dowfroth 250 and pine oil,the bubbles size decreased significantly,reaching 0.45 mm.While the highest recoveries in coal flotation were obtained in single and frother blends where the bubbles size was measured as the smallest in two-phase system,and such a relationship was not found for talc flotation.
文摘Despite the abundant water resources available in Lebanon, it still faces a water shortage. Pollution is one of the main stresses on Lebanon’s water resources. This study was carried out in Nabaa El Tasseh Spring, the main water supply source in the Nabatiyeh Region. The aim of this study is to assess water quality of the spring of Nabaa El Tasseh during winter and spring seasons to determine the Water Quality Index (WQI). At the Environmental Laboratory of Lebanese University, Faculty of Agronomy, water was tested physiochemical parameters including temperature, hydrogen potential (pH), electrical conductivity (EC), total dissolved solids (TDS), anions (NO3−, Cl−, SO42−), and cations (Mg2+, Ca2+, Na+, K+ and Fe2+). The majority of the physical and chemical parameters under investigation fell below the international and Lebanese norms, including WHO recommendations. Additionally, fecal Streptococcus, total coliforms, and fecal coliforms were determined using microbiological testing. Due to its proximity to agricultural activities, the Nabaa El Tasseh Spring water was contaminated by total coliforms. Fecal Coliforms and Fecal Streptococcus, on the other hand, are a sign of animal or human sewage contamination in groundwater. WQI was calculated using the Weighted Arithmetic Index approach. This study has shown that water quality in Nabaa El Tasseh Spring was not acceptable for consumption without treatment in February 2019 with WQI values equal to 88.608, but it became 31.51 acceptable during April and 18.22 in December 2022. An index is a useful tool for conveying water quality information to the public and legislative decision-makers. Although the WQI is excellent in the spring, there is microbiological pollution, thus water treatment is required. The results indicated that Principal Component Analysis (PCA) could clearly explain the pollution trends in the spring over several months. The study’s findings indicate that before the water of Nabaa El Tasseh Spring can be used for drinking or residential purposes, it must first undergo extensive treatment.
文摘Gold concentration usually consists of gravity separation, flotation, cyanidation, or the combination of these processes. The choice among these processes depends on the mineralogical characterization and gold content of the ore. Recently, the recovery of gold using gravity methods has gained attention because of low cost and environmentally friendly operations. In this study, gold pre-concentrates were produced by the stepwise gravity separation and flotation techniques. The Knelson concentrator and conventional flotation were employed for the recovery of gold. Gold bearing ore samples were taken from Gümüshane Region, northern east part of Turkey. As a result of stepwise Knelson concentration experiments, a gold concentrate assaying around 620 g/t is produced with 41.4wt% recovery. On the other hand, a gold concentrate about 82 g/t is obtained with 89.9wt% recovery from a gold ore assaying 6 g/t Au by direct flotation.
基金supported by a NIOSH Ground Control Capacity Building grant
文摘In order to study pillar and overburden response to retreat mining, a ground control program was conducted at a Central Appalachian Mine. The program consisted of several monitoring methods including a seismic monitoring system, borehole pressure cells in the pillars, and time-lapse photogrammetry of the pillar ribs. Two parallel geophone arrays were installed, one on each side of the panel with the sensors mounted 3 m into the roof. A total of fourteen geophones recorded more than 5000 events during the panel retreat. A MIDAS datalogger was used to record pressure from borehole pressure cells(BPCs)located in two adjacent pillars that were not mined during retreat. A series of photographs were taken of the pillars that had the BPCs as the face approached so that deformation of the entire rib could be monitored using photogrammetry. Results showed that pillar stability and cave development were as expected. The BPCs showed an increase in loading when the face was 115 m inby and a clear onset of the forward abutment at 30 m. The photogrammetry results displayed pillar deformation corresponding to the increased loading. The microseismic monitoring results showed the overburden caving inby the face, again as expected. The significance of these results lies in two points,(1) we can quantify the safe manner in which this mine is conducting retreating operations, and(2) we can use volumetric technologies(photogrammetry and microseismic) to monitor entire volumes of the mine in addition to the traditional point-location geotechnical measurements(BPCs).
基金the financial support of National Iranian Copper Industries Company (N.I.C.I.Co.)
文摘Misreported pyrite into copper concentrates dramatically declines copper grade and recovery. Copper flotation can be also more complicated if flotation feed comes from an elevated-pyritic copper ore. In this investigation, the effect of two different ore types(high pyritic and low pyritic feeds) was studied on rougher stage of industrial copper flotation circuit. Samples were taken from different streams and the structure of chalcopyrite within the pyrite and non-sulfide gangue minerals was examined in various size fractions for mentioned ore types. Results indicated that 72% and 56% of the total floated pyrite was transferred to concentrate in first four cells in the low and high pyritic feeds, respectively. Whereas, this proportion for floated SiO_2 in last ten cells was detected as 72% and 71%, respectively. A detailed interpretation of the effect of locked particles in different size fractions on rougher flotation cells is studied from industrial point of view.
文摘The distribution of the various organic and inorganic constituents and their influences on the combustion of coal has been comprehensively studied.However,the combustion characteristics of pulverized coal depend not only on rank but also on the composition,distribution,and combination of the macerals.Unlike the proximate and ultimate analyses,determining the macerals in coal involves the use of sophisticated microscopic instrumentation and expertise.In this study,an attempt was made to predict the amount of macerals(vitrinite,inertinite,and liptinite)and total mineral matter from the Witbank Coalfields samples using the multiple input single output white-box artificial neural network(MISOWB-ANN),gene expression programming(GEP),multiple linear regression(MLR),and multiple nonlinear regression(MNLR).The predictive models obtained from the multiple soft computing models adopted are contrasted with one another using difference,efficiency,and composite statistical indicators to examine the appropriateness of the models.The MISOWB-ANN provides a more reliable predictive model than the other three models with the lowest difference and highest efficiency and composite statistical indicators.
基金supported by the Islamic Azad University,Savadkooh Branch
文摘In this paper,the effect of various electrochemical environments in the galena flotation is investigated.The electrochemical environments consisted of a ball mill for grinding of galena ore and a Denver flotation cell for flotation of galena in the laboratory scale.In order to achieve the maximum recovery with sodium hyposulfite,the concentrations of 0.06 and 0.12 M of air and nitrogen gases have been used to control the pulp potential in the Denver flotation cell.The galena sample was from the ''Era mine'' which is located in the Kiyasar area,north of Iran.This mine contains:Galena(PbS) at least 22%,Fluorite(CaF 2) 73.37%,Quartz(SiO 2) 2.54% and other minerals such as Cerussite(PbCO 3) and Kaolinite(Al 2 Si 2 O 5(OH) 4).Flotation of Galena was conducted in a 0.12 M of sodium hyposulfite solution.It was found that the amount of recovery by this process was 85% and 63% in the presence and absence of potassium amyl xanthate(KAX) and at an estimated potential of 280 to 350 mV respectively while the recovery was 70% and 52% at an approximate potential of 175 to 210 mV in water in the presence and absence of collector(KAX).
基金Supported by the State Key Development Program for Basic Research of China (2009CB623406)the National Natural Science Foundation of China (20990224,11172299)the National Science Fund for Distinguished Young Scholars (21025627)
文摘Numerical solution of yield viscoplastic fluid flow is hindered by the singularity inherent to the Herschel-Bulkley model. A finite difference method over the boundary-fitted orthogonal coordinate system is util- ized to investigate numerically the fully developed steady flow of non-Newtonian yield viscoplastic fluid through concentric and eccentric annuli. The fluid rheology is described with the Herschel-Bulkley model. The numerical simulation based on a continuous viscoplastic approach to the Herschel-Bulkley model is found in poor accordance with the experimental data on volumetric flow rate of a bentonite suspension. A strict mathematical model for Herschel-Bulkley fluid flow is established and the corresponding numerical procedures are proposed. However, only the case of flow of a Herschel-Bulkley fluid in a concentric annulus is resolved based on the presumed flow stnicture by using the common optimization technique. Possible flow structures in an eccentric afinulus are presumed, and further challenges in numerical simulation of the Herschel-Bulkley fluid flow are suggested.
文摘The Kuvasali landslide disaster in Malava, Western Kenya, which caused harmful geo-environmental hazards to the villagers in August 2007, formed the premise of this paper. The existing landslide vulnerability occurrence ratings have been identified and documented using participatory approaches to ascertain the adoptive indigenous methods, which helped mitigation against the negative impacts by determining the slope steepness using Abney level. The geological set up, settlement and climatic factors, relating to landslides, revealed that the affected homesteads were on a steep slope of approximately 70%, with underlying metamorphosed basement rocks comprising ofgneisses, schists and granite intrusions. The steep escarpment overlying these rocks, where the landslide occurred, consists of volcanic rocks and black cotton clayey soils. The slope has scattered vegetation cover due to farming, while the low-lying area is planted with sugar cane and maize plantations. The landslide disaster led to loss of lives, injuries and damage to property. Natural resources, including water points, suffered siltation. Mitigation measures such as geo-hazard mapping and zoning, awareness training and campaigns for the local people focusing on hazard-prone areas resulting from poor land use practices have been recommended.
文摘The indiscriminate disposal of plastic waste poses significant environmental and economic threats,necessitating innovative recycling strategies that align with circular economy principles.The primary objective was to assess the im-pact of varying plastic-to-sand ratios on the compressive strength of these com posite pavement blocks,optimising resource utilisation.These objectives were achieved through research investigating the feasibility of utilising four com-mon post-consumer thermoplastics-HDPE,PP,PET,and PS,as binding agents in pavement block production.This directly addresses the circular economy imperative by transforming waste into a valuable construction resource,mini-mising landfill burden,and creating a closed-loop system.Compared with con-ventional concrete pavers,these plastic-sand blocks offer the potential for a reduced carbon footprint by valorising waste materials and potentially decreas-ing reliance on energy-intensive cement production.The methodology in-volved melting each plastic type individually and combining it with sand at five different ratios:3:7,4:6,5:5,6:4,and 7:3(plastic:sand).The resulting mixtures were moulded into pavement blocks and subjected to compressive strength test-ing.One-way ANOVA revealed varying optimal plastic-to-sand ratios for HDPE,PP,PET,and PS pavement blocks,as determined by compressive strength anal-ysis.For HDPE,while ratios of 30:70,50:50,60:40,and 70:30 showed compara-ble performance,and the 40:60 combination exhibited the highest compressive strength.In contrast,PP mixtures demonstrated optimal strength at a 60:40 ratio,with the 40:60,50:50,and 70:30 ratios showing similar behaviour that could be substituted.PET mixtures achieved peak strength at a 30:70 ratio,and only the 40:60 and 70:30 ratio combinations could be substituted without impacting the compressive strength.Similarly,PS mixtures exhibited optimal performance at a 50:50 ratio,with some substitution potential observed at 30:70,40:60,60:40,and 70:30 ratios.These findings demonstrate that specific plastic types have unique optimal mixing ratios with sand to achieve maximal compressive strength,thereby transforming plastic waste into durable pavement blocks that support a circular economy.
基金This research is funded by NIOSH capacity-building contract 200-2011-40313 through the OMSHR Ground Control Mining Program Area.
文摘A microseismic monitoring system was installed in an underground room and pillar coal mine in the Eastern United States to analyze the occurrence and characteristics of induced seismicity during the retreat of two panels in the mine.This study is the first microseismic monitoring effort at an underground coal mine in nearly 30 years.During the retreat of the first panel,an array of eight uniaxial geophones,installed 10 ft.into the roof,recorded events and their magnitudes.The second panel was monitored using an array of twelve uniaxial geophones and two triaxial geophones,also installed 10 ft.into the roof.Comparing the results of these studies,it has been found that the magnitude of seismic events is minimally affected by immediate roof geology or depth of cover.However,it was observed in both studies that the rate at which seismic events occurred did vary with changing roof geology and depth of cover.Using the seismic data from the second panel retreat,focal mechanism solutions were generated for 50 hand-picked events in order to determine if the failure was in compression,tension,or shear.Results of the focal mechanism solutions show that stress relief resulting in dilational events occurs at significant depths,150-200 m in this case,beneath the active mining face.
文摘In estimating emissions reductions brought about by renewables in China, much of existing research assumes that renewables displace coal power. In this paper, this assumption is challenged and the potential environmental effects of photovoltaic （PV） power in North-west China are reevaluated when the marginal generator actually being displaced is taken into account. The annual PV power generation in the North-west Grid is estimated, in this paper, to be as high as 17900GW.h in 2015, roughly equaling to the output of 1.5 nuclear power plants in the US today. The total associated emission reduction in 2015 will at most be 0.36 percent of SO2 and 0.25 percent of NOx emissions from their 2010 levels in China. Further, PV power may render no emissions reduction at all if it displaces hydropower, which is often used to meet peak demand in the North-west Grid in China. These results imply that a more cost-effective area of focus in the short- term may be on desulfurization and denitrification technologies for coal plants.
