In a hard-rock mine,blasting is an important rock-breakage process that impacts energy consumption both in downstream comminution processes and mine productivity.Optimizing the blast fragmentation to improve rock-brea...In a hard-rock mine,blasting is an important rock-breakage process that impacts energy consumption both in downstream comminution processes and mine productivity.Optimizing the blast fragmentation to improve rock-breakage efficiencies during crushing and grinding is key to mine-to-mill(MTM)optimization.This study explores the use of monitoring while drilling(MWD)data to achieve this goal.Representative penetration rates(PRs)were extracted from blastholes to estimate intact rock properties and predict the breakage efficiencies that directly affect comminution energy consumption.Two intact rock properties,tensile strength(TS)and Bond work index(BWI),were correlated with the PR data to predict these efficiencies in crushing and grinding,respectively.Because of the complexity of the raw MWD data and effects of various disturbances,the MWD data was preprocessed and normalized to achieve a representative PR value at each blasthole.This preprocessing entailed defining valid PR ranges from the MWD data that could eliminate the noise related to discontinuity features in the rock mass structure as well as errors in operator behaviors.The PR data was also normalized using the adjusted penetration rate(APR)to minimize the effects of mechanical factors such as drill feed force,torque,and rotational speed.To correlate the representative APR value with intact rock properties,TS and BWI,various laboratory experiments were conducted:drilling tests using a high-precision coring machine,Brazilian disc tests,and Bond grindability tests.Based on the results of these experiments,models were developed to predict rock-breakage efficiencies during crushing and grinding based on APR.The result of this study can be used to obtain blast energy designs that consider comminution energy consumption and efficiency in the downstream rock-breakage processes.展开更多
Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and space industry applications. This paper highlights the work being undertaken in the Geomechanics Laboratory of Mc Gill U...Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and space industry applications. This paper highlights the work being undertaken in the Geomechanics Laboratory of Mc Gill University to make a real application of microwave-assisted mechanical rock breakage to fullface tunneling machines and drilling. Comprehensive laboratory tests investigated the effect of microwave radiation on temperature profiles and strength reduction in hard rocks(norite, granite, and basalt)for a range of exposure times and microwave power levels. The heating rate on the surface of the rock specimens linearly decreased with distance between the sample and the microwave antenna, regardless of microwave power level and exposure time. Tensile and uniaxial compressive strengths were reduced with increasing exposure time and power level. Scanning electron micrographs(SEMs) highlighted fracture development in treated basalt. It was concluded that the microwave power level has a strong positive influence on the amount of heat damage induced to the rock surface. Numerical simulations of electric field intensity and wave propagation conducted with COMSOL Multiphysics~ software generated temperature profiles that were in close agreement with experimental results.展开更多
采用SPH-FEM(smoothed particle hydrodynamics with finite element method)模拟了后混合磨料水射流在喷嘴中的混合过程,并研究了射流速度、磨料浓度以及岩石围压等因素对后混合磨料水射流破岩效果的影响规律。研究结果表明:在柱塞推动...采用SPH-FEM(smoothed particle hydrodynamics with finite element method)模拟了后混合磨料水射流在喷嘴中的混合过程,并研究了射流速度、磨料浓度以及岩石围压等因素对后混合磨料水射流破岩效果的影响规律。研究结果表明:在柱塞推动下,水与磨料在喷嘴的混合段、收敛段与直线段分别获得加速,最终磨料的速度可增加至纯水速度的80%;岩石破碎深度随射流速度呈近似线性增加,而破碎宽度随射流速度变化不大;磨料射流较纯水射流的破岩损伤更加明显,岩石的损伤随磨料浓度呈先增大后减小的趋势;岩石的破碎深度随着围压的增加呈近似线性减小的趋势。数值模拟结果与破岩实验现象基本吻合,该研究结果可为磨料水射流破岩的应用提供一定的理论支撑。展开更多
文摘In a hard-rock mine,blasting is an important rock-breakage process that impacts energy consumption both in downstream comminution processes and mine productivity.Optimizing the blast fragmentation to improve rock-breakage efficiencies during crushing and grinding is key to mine-to-mill(MTM)optimization.This study explores the use of monitoring while drilling(MWD)data to achieve this goal.Representative penetration rates(PRs)were extracted from blastholes to estimate intact rock properties and predict the breakage efficiencies that directly affect comminution energy consumption.Two intact rock properties,tensile strength(TS)and Bond work index(BWI),were correlated with the PR data to predict these efficiencies in crushing and grinding,respectively.Because of the complexity of the raw MWD data and effects of various disturbances,the MWD data was preprocessed and normalized to achieve a representative PR value at each blasthole.This preprocessing entailed defining valid PR ranges from the MWD data that could eliminate the noise related to discontinuity features in the rock mass structure as well as errors in operator behaviors.The PR data was also normalized using the adjusted penetration rate(APR)to minimize the effects of mechanical factors such as drill feed force,torque,and rotational speed.To correlate the representative APR value with intact rock properties,TS and BWI,various laboratory experiments were conducted:drilling tests using a high-precision coring machine,Brazilian disc tests,and Bond grindability tests.Based on the results of these experiments,models were developed to predict rock-breakage efficiencies during crushing and grinding based on APR.The result of this study can be used to obtain blast energy designs that consider comminution energy consumption and efficiency in the downstream rock-breakage processes.
基金the Natural Sciences and Engineering Research Council of Canada(NSERC)with the collaboration of IAMGold,Glencore,and Vale Canada,who generously contributed financially to this research project
文摘Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and space industry applications. This paper highlights the work being undertaken in the Geomechanics Laboratory of Mc Gill University to make a real application of microwave-assisted mechanical rock breakage to fullface tunneling machines and drilling. Comprehensive laboratory tests investigated the effect of microwave radiation on temperature profiles and strength reduction in hard rocks(norite, granite, and basalt)for a range of exposure times and microwave power levels. The heating rate on the surface of the rock specimens linearly decreased with distance between the sample and the microwave antenna, regardless of microwave power level and exposure time. Tensile and uniaxial compressive strengths were reduced with increasing exposure time and power level. Scanning electron micrographs(SEMs) highlighted fracture development in treated basalt. It was concluded that the microwave power level has a strong positive influence on the amount of heat damage induced to the rock surface. Numerical simulations of electric field intensity and wave propagation conducted with COMSOL Multiphysics~ software generated temperature profiles that were in close agreement with experimental results.
文摘采用SPH-FEM(smoothed particle hydrodynamics with finite element method)模拟了后混合磨料水射流在喷嘴中的混合过程,并研究了射流速度、磨料浓度以及岩石围压等因素对后混合磨料水射流破岩效果的影响规律。研究结果表明:在柱塞推动下,水与磨料在喷嘴的混合段、收敛段与直线段分别获得加速,最终磨料的速度可增加至纯水速度的80%;岩石破碎深度随射流速度呈近似线性增加,而破碎宽度随射流速度变化不大;磨料射流较纯水射流的破岩损伤更加明显,岩石的损伤随磨料浓度呈先增大后减小的趋势;岩石的破碎深度随着围压的增加呈近似线性减小的趋势。数值模拟结果与破岩实验现象基本吻合,该研究结果可为磨料水射流破岩的应用提供一定的理论支撑。
