Development of deep underground mining projects is crucial for optimum extraction of mineral deposits.The main challenges at great depth are high rock stress levels,seismic events,large-scale deformation,sudden failur...Development of deep underground mining projects is crucial for optimum extraction of mineral deposits.The main challenges at great depth are high rock stress levels,seismic events,large-scale deformation,sudden failures and high temperatures that may cause abrupt and unpredictable instability and collapse over a large scale.In this paper,a ground control and management strategy was presented corresponding to the three stages of projects:strategic design,tactical design and operational design.Strategic design is results in preparing a broad plan and primary design for mining excavations.The tactical design is to provide detail design such as stabilisation methods.Operational design stage is related to monitoring and updating design parameters.The most effective ground control strategies in this stage are maintenance,rehabilitation,monitoring and contingency plan.Additionally,a new procedure for design of ground support systems for deep and hard rock was proposed.The main principles are:static and/or dynamic loading types,determination of loading sources,characterisation of geological conditions and the effects of orientation of major structures with openings,estimation of ground loading factor,identification of potential primary and secondary failures,utilisation of appropriate design analysis methods,estimation of depth failure,calculation of the static and/or dynamic demand ground support capacity,and selection of surface and reinforcement elements.Gravitational force is the dominant loading force in low-level stresses.In high stress level failure mechanism becomes more complex in rock mass structures.In this condition,a variety of factors such as release of stored energy due to seismic events,stress concentration,and major structures influence on ground behaviour and judgement are very complicated.The key rock engineering schemes to minimise the risk of failures in high-stress levels at great depth involve depressurisation and quality control of materials.Microseismic and blast monitoring throughout the mining operations are required to control sudden failures.Proper excavation sequences in underground stopes based on top-down,bottom-up,centre-out and abutment-centre were discussed.Also,the performance of a ground support system was examined by field observation monitoring systems for controlling and modifying ground support elements.The important outcome of the research is that the proposed procedure of selecting ground support systems for static and dynamic situations was applied in several deep underground mines in Western Australia.Ground behaviour modes and failure mechanism were identified and assessed.Ground demand for static and dynamic conditions was estimated and an appropriate ground support system was selected and evaluated in site-specific conditions according to proposed method for ground support design at great depth.The stability of rock masses was confirmed,and the reliability of the design methodology for great depth and hard rock conditions was also justified.展开更多
The increasing use of diesel-powered equipment in confined spaces(underground mines) has the potential to over expose underground miners under the threat of diesel particulate matter(DPM). Miners in underground mines ...The increasing use of diesel-powered equipment in confined spaces(underground mines) has the potential to over expose underground miners under the threat of diesel particulate matter(DPM). Miners in underground mines can be exposed to DPM concentrations far more than works in other industries. A great number of animal and epidemiological studies have shown that both short-term and long-term DPM exposure have adverse health effect. Based on reviews of related studies, especially some recent evidence, this paper investigated the long and short-term health effects based on animal studies and epidemiological studies. The exposure-response relationship studies were also explored and compared to the current DPM regulation or standards in some countries. This paper found that the DPM health effect studies specifically for miners are not sufficient to draw solid conclusions, and a recommendation limit of DPM concentration can be put in place for better protection of miners from DPM health risk. Current animal studies lack the use of species that have similar lung functions as human for understanding the cancer mode of action in human. And finally, the DPM health hazard will continue to be a challenging topic before the mode of action and reliable exposure-response relationship are established.展开更多
The identification of stratigraphic'sweet-spot'interval is significant in oil and gas formation evaluation.However,formation evaluation in macroscopic-scale merely provides low resolution and limited infor-mat...The identification of stratigraphic'sweet-spot'interval is significant in oil and gas formation evaluation.However,formation evaluation in macroscopic-scale merely provides low resolution and limited infor-mation,thus may lead to uncertainties in resource estimation.To accurately identify the'sweet-spot'intervals amongst heterogeneous lithofacies,we conducted a very high-resolution and quantitative analysis from in-situ macroscopic scale to laboratory microscopic scale on the Goldwyer formation of Canning Basin,Western Australia.The comprehensive advanced well logging and slim-compact micro imager(SCMI)technologies were synthetically applied in couple with the laboratory nanoscaled ex-periments.The results unveiled an extraordinarily large lithofacies heterogeneity between different rock intervals,with distinguished features shown in Goldwyer Ⅰ,Ⅱ,and Ⅲ members.The most favorable lithofacies is recognized as the laminated argillaceous thermally-matured organic matter(OM)-rich mudstone,which is widely developed in Goldwyer Ⅲ as the major attributor to'sweet-spot'intervals.Goldwyer Ⅱ is exclusively characterized by thick mudstone intervals(94.4%),interbedded with thin calcareous mudstones(5.5%),corresponding to a depositional environment of low-energy distal section of the outer ramp settings.Microscopically,the most favorable lithofacies in'sweet-spot'intervals develop numerous OM-/mineral nanopores for hydrocarbon storage.Illite-rich lithofacies develops abundant inter-particle pores from 2 to 17 nm that mainly contribute to pore volume for free gas storage capacity.OM-rich lithofacies with higher maturity have OM-pores with good connectivity,bearing large specific surface area that is beneficial for adsorbed gas capacity.展开更多
One of the most serious conundrum facing the stope production in underground metalliferous mining is uneven break （UB： unplanned dilution and ore-loss）. Although the UB has a huge economic fallout to the entire min...One of the most serious conundrum facing the stope production in underground metalliferous mining is uneven break （UB： unplanned dilution and ore-loss）. Although the UB has a huge economic fallout to the entire mining process, it is practically unavoidable due to the complex causing mechanism. In this study, the contribution of ten major UB causative parameters ha,; been scrutinised based on a published UB predicting artificial neuron network （ANN） model to put UB under the engineering management. Two typical ANN sensitivity analysis methods, i.e., connection weight algorithm （CWA） and profile method （PM） have been applied. As a result of CWA and PM applications, adjusted Qrate （AQ） revealed as the most influential parameter to UB with contribution of 22,40% in CWA and 20,48% in PM respectively. The findings of this study can be used as an important reference in stope design, production, and reconciliation stages on underground stoping mine.展开更多
Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablati...Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablation and secondary ionization mass spectrometry） has allowed for large amounts of data to be generated in a relatively short amount of time and such large volume datasets offer the ability to address a range of geological questions that would otherwise remain intractable （e.g. detrital zircons as a sedi- ment fingerprinting method）. The ease of acquisition, while bringing benefit to the Earth science com- munity, has also led to diverse interpretations of geochronological data. In this work we seek to refocus U -Pb zircon geochronology toward best practice by providing a robust statistically coherent workflow. We discuss a range of data filtering approaches and their inherent limitations （e.g. discordance and the reduced chi-squared; MSWD）. We evaluate appropriate mechanisms to calculate the most geologically appropriate age from both 238U/206pb and 207pb/206pb ratios and demonstrate the cross over position when chronometric power swaps between these ratios. As our in situ analytical techniques become progressively more precise, appropriate statistical handing of U-Pb datasets will become increasingly pertinent.展开更多
Rock bolts are subjected to different loading conditions along their lengths such as axial,bending,and/or shear forces,which can cause failure at lower loads than those considered for design purposes.The common existi...Rock bolts are subjected to different loading conditions along their lengths such as axial,bending,and/or shear forces,which can cause failure at lower loads than those considered for design purposes.The common existing methodologies do not consider the actual loading of the rock bolts and assume it is only pure axial or pure shear.This study was conducted to investigate the un-grouted rock bolt performance under combined load conditions.Two loading regimes were evaluated:the effect of initial shear displacement on axial load capacity and displacement,and the effect of axial displacement on the shear load capacity.The first regime was also conducted for shear with a gap,when there is a spacing between the shear interfaces.The results of this study showed that the rock bolt can resist higher axial loads than shear under pure or combined load conditions.Under combined load conditions,the rock bolt capacity decreased significantly for both regimes.However,when applying the shear load with a gap,the rock bolt load capacity was not affected significantly.Also,the total bar deformation was improved for shear and axial.The findings of this study show the need to improve the rock bolt design considering the complex loading conditions in situ with/without a gap.展开更多
Change in mechanical properties of rocks under static loading has been widely studied and documented.However, the response of rocks to cyclic loads is still a much-debated topic. Fatigue is the phenomenon when rocks u...Change in mechanical properties of rocks under static loading has been widely studied and documented.However, the response of rocks to cyclic loads is still a much-debated topic. Fatigue is the phenomenon when rocks under cyclic loading fail at much lower strength as compared to those subjected to the monotonic loading conditions. A few selected cored granodiorite and sandstone specimens have been subjected to uniaxial cyclic compression tests to obtain the unconfined fatigue strength and life. This study seeks to examine the effects of cyclic loading conditions, loading amplitude and applied stress level on the fatigue life of sandstone, as a soft rock, and granodiorite, as a hard rock, under uniaxial compression test. One aim of this study is to determine which of the loading conditions has a stronger effect on rock fatigue response. The fatigue response of hard rocks and soft rocks is also compared. It is shown that the loading amplitude is the most important factor affecting the cyclic response of the tested rocks. The more the loading amplitude, the shorter the fatigue life, and the greater the strength degradation. The granodiorite specimens showed more strength degradation compared to the sandstone specimens when subjected to cyclic loading. It is shown that failure modes of specimens under cyclic loadings are different from those under static loadings. More local cracks were observed under cyclic loadings especially for granodiorite rock specimens.展开更多
Analyzing the mineral composition, mechanical properties and ground stress testing in surrounding rock,the study investigated the failure mechanism of deep soft rock roadway with high stress. The boltgrouting combined...Analyzing the mineral composition, mechanical properties and ground stress testing in surrounding rock,the study investigated the failure mechanism of deep soft rock roadway with high stress. The boltgrouting combined support system was proposed to prevent such failures. By means of FLAC3D numerical simulation and similar material simulation, the feasibility of the support design and the effectiveness of support parameters were discussed. According to the monitoring the surface and deep displacement in surrounding rock as well as bolt axial load, this paper analyzed the deformation of surrounding rock and the stress condition of the support structure. The monitor results were used to optimize the proposed support scheme. The results of field monitors demonstrate that the bolt-grouting combined support technology could improve the surround rock strength and bearing capacity of support structure, which controlled the great deformation failure and rheological property effectively in deep soft rock roadway with high stress. As a result, the long term stability and safety are guaranteed.展开更多
An automated underground mine monitoring and communication system based on the integration of new technologies is introduced to promote safety and health,operational management and cost-effectiveness.The proposed syst...An automated underground mine monitoring and communication system based on the integration of new technologies is introduced to promote safety and health,operational management and cost-effectiveness.The proposed system integration considering Wireless Sensor Network(WSN) assisted Geographic Information System(GIS) enables to monitor and control underground mining applications from surface office.Based on the capabilities of WSNs,ZigBee network is adapted for near real-time monitoring,ventilation system control and emergency communication in underground mine.ZigBee nodes were developed to sense environmental attributes such as temperature,humidity and gases concentration;switching ON and OFF ventilation fans;and texting emergency messages.A trigger action plan for monitored attributes above normal and threshold value limits is programmed in the surface GIS management server.It is designed to turn the auxiliary fans on remotely or automatically in orange condition and sending evacuation messages for underground miners in unsafe(red) condition.Multi-users operation and 3D visualisations are other successful achievements of the proposed system for the underground monitoring and communication.展开更多
As hydraulic fracturing was forbidden in some countries due to possible negative environmental impacts and enhanced coalbed methane(ECBM)was restricted by in-situ conditions,microwave heating was proposed to enhance c...As hydraulic fracturing was forbidden in some countries due to possible negative environmental impacts and enhanced coalbed methane(ECBM)was restricted by in-situ conditions,microwave heating was proposed to enhance coalbed permeability.One of the mechanisms of improving coal permeability with microwave irradiation is that thermal expansion caused by microwave heating.To study the influence of microwave’s heating effect of coal samples,the simulations were conducted using a coupled electromagnetic,thermal and mechanical model in this paper.The temperature,Von-Mises stress and strain distribution of coal sample are recorded every 10 s.The permeability distribution is also obtained based on the relationship between strain and permeability from articles.It was found that volume average temperature,stress,strain and permeability increase almost linearly with time.The average permeability increased from 1.65 10×16 m^2 to 3.63 10×16 m^2 under 2.45 GHz and 500Wmicrowave radiation after 300 s.The significant increase proved microwave to be effective in coal seam permeability enhancement.展开更多
In order to improve our understanding of rock fracture and fault instability driven by high-pressure fluid sources, the authors carried out rock fracture tests using granite under a confining pressure of 80 MPa with f...In order to improve our understanding of rock fracture and fault instability driven by high-pressure fluid sources, the authors carried out rock fracture tests using granite under a confining pressure of 80 MPa with fluid injection in the laboratory. Furthermore, we tested a number of numerical models using the FLAC;modeling software to find the best model to represent the experimental results. The high-speed multichannel acoustic emission（AE） waveform recording system used in this study made it possible to examine the total fracture process through detailed monitoring of AE hypocenters and seismic velocity.The experimental results show that injecting high-pressure oil into the rock sample can induce AE activity at very low stress levels and can dramatically reduce the strength of the rock. The results of the numerical simulations show that major experimental results, including the strength, the temporal and spatial patterns of the AE events, and the role of the fluid can be represented fairly well by a model involving（1） randomly distributed defect elements to model pre-existing cracks,（2） random modification of rock properties to represent inhomogeneity introduced by different mineral grains, and（3）macroscopic inhomogeneity. Our study, which incorporates laboratory experiments and numerical simulations, indicates that such an approach is helpful in finding a better model not only for simulating experimental results but also for upscaling purposes.展开更多
Detrital zircon U-Pb geochronology has become the gold standard in evaluating source to sink relationships in sedimentary basins. However, the physical and chemical robustness of zircon, which make it such a useful mi...Detrital zircon U-Pb geochronology has become the gold standard in evaluating source to sink relationships in sedimentary basins. However, the physical and chemical robustness of zircon, which make it such a useful mineral for provenance studies, is also a hindrance as zircon can be recycled through numerous sedimentary basins, thus obscuring the first cycle source to sink relationship. An elegant approach to addressing this potential issue is to compare the Pb isotope composition of detrital K-feldspar, a mineral which is unlikely to survive more than one erosion-transport-deposition cycle, with that of magmatic K-feldspar from potential basement source terranes. Here we present new in situ Pb isotope data on detrital K-feldspar from two Proterozoic arkosic sandstones from Western Australia, and magmatic K-feldspar grains from potential igneous source rocks, as inferred by the age and Hf isotope composition of detrital zircon grains. The data indicate that the detrital zircon and K-feldspar grains could not have been liberated from the same source rocks, and that the zircon has most likely been recycled through older sedimentary basins. These results provide a more complete understanding of apparently simple source to sink relationships in this part of Proterozoic Western Australia.展开更多
Circumferential yielding lining is able to tolerate controlled displacements without failure,which has been proven to be an effective solution to large deformation problem in squeezing tunnels.However,up to now,there ...Circumferential yielding lining is able to tolerate controlled displacements without failure,which has been proven to be an effective solution to large deformation problem in squeezing tunnels.However,up to now,there has not been a well-established design method for it.This paper aims to present a detailed analytical computation of support characteristic curve(SCC)for circumferential yielding lining,which is a significant aspect of the implementation of convergence-confinement method(CCM)in tunnel support design.Circumferential yielding lining consists of segmental shotcrete linings and highly deformable elements,and its superior performance mainly depends on the mechanical characteristic of highly deformable element.The deformation behavior of highly deformable element is firstly investigated.Its whole deforming process can be divided into three stages including elastic,yielding and compaction stages.Especially in the compaction stage of highly deformable element,a nonlinear stress-strain relationship can be observed.For mathematical convenience,the stress-strain curve in this period is processed as several linear sub-curves.Then,the reasons for closure of circumferential yielding lining in different stages are explained,and the corresponding accurate equations required for constructing the SCC are provided.Furthermore,this paper carries out two case studies illustrating the application of all equations needed to construct the SCC for circumferential yielding lining,where the reliability and feasibility of theoretical derivation are also well verified.Finally,this paper discusses the sensitivity of sub-division in element compaction stage and the influence of element length on SCC.The outcome of this paper could be used in the design of proper circumferential yielding lining.展开更多
Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces.Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used...Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces.Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility,cost effectiveness and easy practicability.Reinforcement elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity,knowing that the former is more important.In other words,achieving early stiff behaviour along with large deformation capacity in rockbolts are the goals for new development in rock reinforcement.Yielding rockbolts are expensive while some of them have large deformation capability with low ultimate load capacity.In this paper,modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic conditions.Applying a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground,improves the deformation capacity of the bolt.Additionally,leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of rockbolt.Therefore the dynamic performance of the bolt is improved by these easily applicable modifications.The behaviour and performance of encapsulated rockbolts have been discussed first,then the effects of modifications are illustrated.The proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones.展开更多
The residue drying area(RDA)is the major source of fugitive red sand(RS)dust emissions in the bauxite mining industry and causes serious environmental and safety detriments.Polymer stabilizer(PS)is one of the promisin...The residue drying area(RDA)is the major source of fugitive red sand(RS)dust emissions in the bauxite mining industry and causes serious environmental and safety detriments.Polymer stabilizer(PS)is one of the promising non-traditional stabilizers to mitigate such issues.This research investigated the unconfined compressive strength(UCS)of RS using synthetic polymer stabilizer(SPS)and natural polymer stabilizer(NPS),and to determine the optimum application concentration and mixing ratio of the PAM and Guar gum mixture.Results illustrated that PAM apparently outperform Guar gum in stabilizing sand particles.The mixture of PAM and Guar gum is more effective than individual use.The optimum polymer concentration and the mixing ratio are 0.94 wt.%and 0.6(PAM:total(PAM+Guar gum)),respectively.A rigorous regression model was developed to predict the UCS value based on application concentration and mixing ratio for the purpose of cost and time efficiency.展开更多
High stress concentrations around underground excavations can result in significant damage to deep hard-rock mines.These conditions can be the result of stopping activities,blasting,seismicity,or other mining activiti...High stress concentrations around underground excavations can result in significant damage to deep hard-rock mines.These conditions can be the result of stopping activities,blasting,seismicity,or other mining activities.Large anisotropic deformation and excavation closure,especially under high-stress conditions,are expected if the excavation is located in a foliated or thin-bedded rock mass.In this research,the behaviour of excavations under deep and high-stress conditions was investigated and categorised.The main purpose was to enhance the existing knowledge of managing large anisotropic deformations and to help prepare suitable measures for handling such contingencies.Numerical simulations using the distinct element method(DEM)and model calibration were performed to reproduce the anisotropic deformation of an ore drive based on the collected field data.Then,the roles of key factors(i.e.stress ratio,slenderness ratio,foliation orientation,and foliation considering excavation orientation)on the large deformation and damage depth of the excavations were investigated.This study found that increasing both the stress ratio and slenderness ratio induced linear increases in wall closure and damage depth,whereas increasing the foliation angle first increases the deformation and damage depth and then reduces them both before and after 45.The wall closure and damage thickness decreased with increasing orientation intercept.The deformation and damage levels were classified based on these factors.展开更多
Wellbore stability is a key to have a successful drilling operation.Induced stresses are the main factors affecting wellbore instability and associated problems in drilling operations.These stresses are significantly ...Wellbore stability is a key to have a successful drilling operation.Induced stresses are the main factors affecting wellbore instability and associated problems in drilling operations.These stresses are significantly impacted by pore pressure variation and thermal stresses in the field.In order to address wellbore instability problems,it is important to investigate the mechanisms of rockefluid interaction with respect to thermal and mechanical aspects.In order to understand the induced stresses,different mathematical models have been developed.In this study,the field equations governing the problem have been derived based on the thermo-poroelastic theory and solved analytically in Laplace domain.The results are transferred to time domain using Fourier inverse method.Finite difference method is also utilized to validate the results.Pore pressure and temperature distributions around the wellbore have been focused and simulated.Next,induced radial and tangential stresses for different cases of cooling and heating of formation are compared.In addition,the differences between thermo-poroelastic and poroelastic models in situation of permeable and impermeable wellbores are described.It is observed that cooling and pore pressure distribution reinforce the induced radial stress.Whereas cooling can be a tool to control and reduce tangential stress induced due to invasion of drilling fluid.In the next step,safe mud window is obtained using Mohr-Coulomb,Mogi-Coulomb,and modified Lade failure criteria for different inclinations.Temperature and pore pressure distributions do not change the minimum allowable wellbore pressure significantly.However,upper limit of mud window is sensitive to induced stresses and it seems vital to consider changes in temperature and pore pressure to avoid any failures.The widest and narrowest mud windows are proposed by modified Lade and Mohr-Coulomb failure criteria,respectively.展开更多
Recently,many regression models have been presented for prediction of mechanical parameters of rocks regarding to rock index properties.Although statistical analysis is a common method for developing regression models...Recently,many regression models have been presented for prediction of mechanical parameters of rocks regarding to rock index properties.Although statistical analysis is a common method for developing regression models,but still selection of suitable transformation of the independent variables in a regression model is diffcult.In this paper,a genetic algorithm(GA)has been employed as a heuristic search method for selection of best transformation of the independent variables(some index properties of rocks)in regression models for prediction of uniaxial compressive strength(UCS)and modulus of elasticity(E).Firstly,multiple linear regression(MLR)analysis was performed on a data set to establish predictive models.Then,two GA models were developed in which root mean squared error(RMSE)was defned as ftness function.Results have shown that GA models are more precise than MLR models and are able to explain the relation between the intrinsic strength/elasticity properties and index properties of rocks by simple formulation and accepted accuracy.展开更多
We report new petrological data and geochronological measurements of granulites from Vesleknausen in the highest-grade section of the L＆#252;tzow-Holm Complex, part of the Gondwana-assembling collisional orogen in Ea...We report new petrological data and geochronological measurements of granulites from Vesleknausen in the highest-grade section of the L＆#252;tzow-Holm Complex, part of the Gondwana-assembling collisional orogen in East Antarctica. The locality is dominated by felsic to intermediate orthogneiss （charnockite and minor biotite gneiss）, mafic orthogneiss, and hornblende-pyroxene granulite, with deformed and undeformed dykes of metagranite and felsic pegmatite. Pseudosection analysis of charnockite in the system NCKFMASHTO, supported by geothermometry of mafic orthogneiss, was used to infer peak metamorphic temperatures of 750e850 ？C, approximately 150 ？C lower than those estimated for met-asedimentary gneisses from Rundv？gshetta, 6 km to the northeast. SHRIMP U-Pb analysis of zircons from feldspar-pyroxene gneiss, which corresponds to a partially molten patch around mafic orthogneiss, yielded a Concordia upper intercept ages of 2507.9 ？ 7.4 Ma, corresponding to the time of formation of the magmatic protolith to the orthogneiss. Partial melting during peak metamorphism probably took place between 591 and 548 Ma, as recorded in rims overgrew around magmatic zircon. Our results suggest that Rundv？gshetta-Vesleknausen-Strandnibba region in southwestern L＆#252;tzow-Holm Bay, where orthogneisses are dominant, consists of a single crustal block, possibly formed by ca. 2.5 Ga arc mag-matism. The Neoarchean magmatic terrane was tectonically mingled with other fragments （such as metasedimentary units in northern L＆#252;tzow-Holm Bay） by subduction/collision events during the as-sembly of Gondwana supercontinent, and subsequently underwent w850 ？C granulite-facies meta-morphosed during Neoproterozoic to Cambrian final collisional event.展开更多
Coal flotation is widely used to separate commercially valuable coal from the fine ore slurry, and is an industrial process with nonlinear, multivariable, time-varying and long time-delay characteristics. The online d...Coal flotation is widely used to separate commercially valuable coal from the fine ore slurry, and is an industrial process with nonlinear, multivariable, time-varying and long time-delay characteristics. The online detection of ash content of products as the operation performance evaluation in the flotation system is extraordinarily difficult because of the low solid content and numerous micro-bubbles in the slurry. Moreover, it is time-consuming by manual analysis. Consequently, the optimal separation is not usually maintained. A novel technique, called the neuro-immune algorithm (NIA) inspired by the biological nervous and immune systems, is presented in this paper for predicting the ash content of clean coal and performing the optimizing control to the coal flotation system. The proposed algorithm integrates the deeply-studied artificial neural network (ANN) and the developing artificial immune system (AIS). A two-layer back-propagation network was constructed offline based on the historical process data under the best system situation, using five parameters: the flow and the density of raw slurry, the input flows of water, the kerosene and the GF oil, as the inputs and the ash content of clean coal as the output. The immune cell of AIS is made up of six parameters above as the antigen. The cytokine based clone selection algorithm is used to produce the relative antibody. The detailed computation procedures about the hybrid neuro-immune algorithm are minutely discussed. The ash content of clean coal was predicted by NIA using the practical process data s: (308.6 174.7 146.1 43.6 4.0 9.4), and the absolute difference between the actual and computed ash content values was 0.0967%. The optimizing control on NIA was simulated considering two different situations where the ash content of clean coal was controlled downward from 10.00% or upward from 9.20% predicted by ANN to the target value 9.50%. The results indicate that the target ash content and the value of controlling parameters are obtained after several control cycles.展开更多
基金supported by Curtin International Postgraduate Scholarship(CIPRS)/Department of Mining and Metallurgy Scholarshippartly supported by National Natural Science Foundation of China the 111 Project under grant Nos.51839003 and B17009.
文摘Development of deep underground mining projects is crucial for optimum extraction of mineral deposits.The main challenges at great depth are high rock stress levels,seismic events,large-scale deformation,sudden failures and high temperatures that may cause abrupt and unpredictable instability and collapse over a large scale.In this paper,a ground control and management strategy was presented corresponding to the three stages of projects:strategic design,tactical design and operational design.Strategic design is results in preparing a broad plan and primary design for mining excavations.The tactical design is to provide detail design such as stabilisation methods.Operational design stage is related to monitoring and updating design parameters.The most effective ground control strategies in this stage are maintenance,rehabilitation,monitoring and contingency plan.Additionally,a new procedure for design of ground support systems for deep and hard rock was proposed.The main principles are:static and/or dynamic loading types,determination of loading sources,characterisation of geological conditions and the effects of orientation of major structures with openings,estimation of ground loading factor,identification of potential primary and secondary failures,utilisation of appropriate design analysis methods,estimation of depth failure,calculation of the static and/or dynamic demand ground support capacity,and selection of surface and reinforcement elements.Gravitational force is the dominant loading force in low-level stresses.In high stress level failure mechanism becomes more complex in rock mass structures.In this condition,a variety of factors such as release of stored energy due to seismic events,stress concentration,and major structures influence on ground behaviour and judgement are very complicated.The key rock engineering schemes to minimise the risk of failures in high-stress levels at great depth involve depressurisation and quality control of materials.Microseismic and blast monitoring throughout the mining operations are required to control sudden failures.Proper excavation sequences in underground stopes based on top-down,bottom-up,centre-out and abutment-centre were discussed.Also,the performance of a ground support system was examined by field observation monitoring systems for controlling and modifying ground support elements.The important outcome of the research is that the proposed procedure of selecting ground support systems for static and dynamic situations was applied in several deep underground mines in Western Australia.Ground behaviour modes and failure mechanism were identified and assessed.Ground demand for static and dynamic conditions was estimated and an appropriate ground support system was selected and evaluated in site-specific conditions according to proposed method for ground support design at great depth.The stability of rock masses was confirmed,and the reliability of the design methodology for great depth and hard rock conditions was also justified.
文摘The increasing use of diesel-powered equipment in confined spaces(underground mines) has the potential to over expose underground miners under the threat of diesel particulate matter(DPM). Miners in underground mines can be exposed to DPM concentrations far more than works in other industries. A great number of animal and epidemiological studies have shown that both short-term and long-term DPM exposure have adverse health effect. Based on reviews of related studies, especially some recent evidence, this paper investigated the long and short-term health effects based on animal studies and epidemiological studies. The exposure-response relationship studies were also explored and compared to the current DPM regulation or standards in some countries. This paper found that the DPM health effect studies specifically for miners are not sufficient to draw solid conclusions, and a recommendation limit of DPM concentration can be put in place for better protection of miners from DPM health risk. Current animal studies lack the use of species that have similar lung functions as human for understanding the cancer mode of action in human. And finally, the DPM health hazard will continue to be a challenging topic before the mode of action and reliable exposure-response relationship are established.
基金Fundamental Research Programme of Yunnan Province(202201AU070041)the funding of Yunnan University Young Talent Programme(CZ21623201)+2 种基金the funding of State Key Laboratory of Coal Mine Disaster Dynamics and Control in Chongqing University(2011DA105287-FW202106)the funding from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,under the Institute of Geology in Chinese Academy of Geological Sciences,Beijing(J1901)Much gratitudes for the Department of Mines,Industry Regulation and Safety under the Government of Western Australia for granting us the core samples under Approval Nos.G32825&N00413。
文摘The identification of stratigraphic'sweet-spot'interval is significant in oil and gas formation evaluation.However,formation evaluation in macroscopic-scale merely provides low resolution and limited infor-mation,thus may lead to uncertainties in resource estimation.To accurately identify the'sweet-spot'intervals amongst heterogeneous lithofacies,we conducted a very high-resolution and quantitative analysis from in-situ macroscopic scale to laboratory microscopic scale on the Goldwyer formation of Canning Basin,Western Australia.The comprehensive advanced well logging and slim-compact micro imager(SCMI)technologies were synthetically applied in couple with the laboratory nanoscaled ex-periments.The results unveiled an extraordinarily large lithofacies heterogeneity between different rock intervals,with distinguished features shown in Goldwyer Ⅰ,Ⅱ,and Ⅲ members.The most favorable lithofacies is recognized as the laminated argillaceous thermally-matured organic matter(OM)-rich mudstone,which is widely developed in Goldwyer Ⅲ as the major attributor to'sweet-spot'intervals.Goldwyer Ⅱ is exclusively characterized by thick mudstone intervals(94.4%),interbedded with thin calcareous mudstones(5.5%),corresponding to a depositional environment of low-energy distal section of the outer ramp settings.Microscopically,the most favorable lithofacies in'sweet-spot'intervals develop numerous OM-/mineral nanopores for hydrocarbon storage.Illite-rich lithofacies develops abundant inter-particle pores from 2 to 17 nm that mainly contribute to pore volume for free gas storage capacity.OM-rich lithofacies with higher maturity have OM-pores with good connectivity,bearing large specific surface area that is beneficial for adsorbed gas capacity.
文摘One of the most serious conundrum facing the stope production in underground metalliferous mining is uneven break （UB： unplanned dilution and ore-loss）. Although the UB has a huge economic fallout to the entire mining process, it is practically unavoidable due to the complex causing mechanism. In this study, the contribution of ten major UB causative parameters ha,; been scrutinised based on a published UB predicting artificial neuron network （ANN） model to put UB under the engineering management. Two typical ANN sensitivity analysis methods, i.e., connection weight algorithm （CWA） and profile method （PM） have been applied. As a result of CWA and PM applications, adjusted Qrate （AQ） revealed as the most influential parameter to UB with contribution of 22,40% in CWA and 20,48% in PM respectively. The findings of this study can be used as an important reference in stope design, production, and reconciliation stages on underground stoping mine.
文摘Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablation and secondary ionization mass spectrometry） has allowed for large amounts of data to be generated in a relatively short amount of time and such large volume datasets offer the ability to address a range of geological questions that would otherwise remain intractable （e.g. detrital zircons as a sedi- ment fingerprinting method）. The ease of acquisition, while bringing benefit to the Earth science com- munity, has also led to diverse interpretations of geochronological data. In this work we seek to refocus U -Pb zircon geochronology toward best practice by providing a robust statistically coherent workflow. We discuss a range of data filtering approaches and their inherent limitations （e.g. discordance and the reduced chi-squared; MSWD）. We evaluate appropriate mechanisms to calculate the most geologically appropriate age from both 238U/206pb and 207pb/206pb ratios and demonstrate the cross over position when chronometric power swaps between these ratios. As our in situ analytical techniques become progressively more precise, appropriate statistical handing of U-Pb datasets will become increasingly pertinent.
基金The authors would like to thank Mining3,Minerals Research Institute of Western Australia,Curtin University and Peabody Energy for funding this research project.They also wish to thank Minova Global and its personnel who assisted in completing all the tests conducted at their facility in Nowra,NSW and for providing the rock bolts for testing.
文摘Rock bolts are subjected to different loading conditions along their lengths such as axial,bending,and/or shear forces,which can cause failure at lower loads than those considered for design purposes.The common existing methodologies do not consider the actual loading of the rock bolts and assume it is only pure axial or pure shear.This study was conducted to investigate the un-grouted rock bolt performance under combined load conditions.Two loading regimes were evaluated:the effect of initial shear displacement on axial load capacity and displacement,and the effect of axial displacement on the shear load capacity.The first regime was also conducted for shear with a gap,when there is a spacing between the shear interfaces.The results of this study showed that the rock bolt can resist higher axial loads than shear under pure or combined load conditions.Under combined load conditions,the rock bolt capacity decreased significantly for both regimes.However,when applying the shear load with a gap,the rock bolt load capacity was not affected significantly.Also,the total bar deformation was improved for shear and axial.The findings of this study show the need to improve the rock bolt design considering the complex loading conditions in situ with/without a gap.
基金Mining Research Institute of Western Australia (MRIWA) for the financial support
文摘Change in mechanical properties of rocks under static loading has been widely studied and documented.However, the response of rocks to cyclic loads is still a much-debated topic. Fatigue is the phenomenon when rocks under cyclic loading fail at much lower strength as compared to those subjected to the monotonic loading conditions. A few selected cored granodiorite and sandstone specimens have been subjected to uniaxial cyclic compression tests to obtain the unconfined fatigue strength and life. This study seeks to examine the effects of cyclic loading conditions, loading amplitude and applied stress level on the fatigue life of sandstone, as a soft rock, and granodiorite, as a hard rock, under uniaxial compression test. One aim of this study is to determine which of the loading conditions has a stronger effect on rock fatigue response. The fatigue response of hard rocks and soft rocks is also compared. It is shown that the loading amplitude is the most important factor affecting the cyclic response of the tested rocks. The more the loading amplitude, the shorter the fatigue life, and the greater the strength degradation. The granodiorite specimens showed more strength degradation compared to the sandstone specimens when subjected to cyclic loading. It is shown that failure modes of specimens under cyclic loadings are different from those under static loadings. More local cracks were observed under cyclic loadings especially for granodiorite rock specimens.
基金financial assistance provided by the National Natural Science Foundation of China (No. 51404262)the Natural Science Foundation of Jiangsu Province of China (No. BK20140213)the Basal Research Fund of China Central College (No. 2015QNA60)
文摘Analyzing the mineral composition, mechanical properties and ground stress testing in surrounding rock,the study investigated the failure mechanism of deep soft rock roadway with high stress. The boltgrouting combined support system was proposed to prevent such failures. By means of FLAC3D numerical simulation and similar material simulation, the feasibility of the support design and the effectiveness of support parameters were discussed. According to the monitoring the surface and deep displacement in surrounding rock as well as bolt axial load, this paper analyzed the deformation of surrounding rock and the stress condition of the support structure. The monitor results were used to optimize the proposed support scheme. The results of field monitors demonstrate that the bolt-grouting combined support technology could improve the surround rock strength and bearing capacity of support structure, which controlled the great deformation failure and rheological property effectively in deep soft rock roadway with high stress. As a result, the long term stability and safety are guaranteed.
文摘An automated underground mine monitoring and communication system based on the integration of new technologies is introduced to promote safety and health,operational management and cost-effectiveness.The proposed system integration considering Wireless Sensor Network(WSN) assisted Geographic Information System(GIS) enables to monitor and control underground mining applications from surface office.Based on the capabilities of WSNs,ZigBee network is adapted for near real-time monitoring,ventilation system control and emergency communication in underground mine.ZigBee nodes were developed to sense environmental attributes such as temperature,humidity and gases concentration;switching ON and OFF ventilation fans;and texting emergency messages.A trigger action plan for monitored attributes above normal and threshold value limits is programmed in the surface GIS management server.It is designed to turn the auxiliary fans on remotely or automatically in orange condition and sending evacuation messages for underground miners in unsafe(red) condition.Multi-users operation and 3D visualisations are other successful achievements of the proposed system for the underground monitoring and communication.
文摘As hydraulic fracturing was forbidden in some countries due to possible negative environmental impacts and enhanced coalbed methane(ECBM)was restricted by in-situ conditions,microwave heating was proposed to enhance coalbed permeability.One of the mechanisms of improving coal permeability with microwave irradiation is that thermal expansion caused by microwave heating.To study the influence of microwave’s heating effect of coal samples,the simulations were conducted using a coupled electromagnetic,thermal and mechanical model in this paper.The temperature,Von-Mises stress and strain distribution of coal sample are recorded every 10 s.The permeability distribution is also obtained based on the relationship between strain and permeability from articles.It was found that volume average temperature,stress,strain and permeability increase almost linearly with time.The average permeability increased from 1.65 10×16 m^2 to 3.63 10×16 m^2 under 2.45 GHz and 500Wmicrowave radiation after 300 s.The significant increase proved microwave to be effective in coal seam permeability enhancement.
基金supported by State Key Laboratory of Earthquake Dynamics,China
文摘In order to improve our understanding of rock fracture and fault instability driven by high-pressure fluid sources, the authors carried out rock fracture tests using granite under a confining pressure of 80 MPa with fluid injection in the laboratory. Furthermore, we tested a number of numerical models using the FLAC;modeling software to find the best model to represent the experimental results. The high-speed multichannel acoustic emission（AE） waveform recording system used in this study made it possible to examine the total fracture process through detailed monitoring of AE hypocenters and seismic velocity.The experimental results show that injecting high-pressure oil into the rock sample can induce AE activity at very low stress levels and can dramatically reduce the strength of the rock. The results of the numerical simulations show that major experimental results, including the strength, the temporal and spatial patterns of the AE events, and the role of the fluid can be represented fairly well by a model involving（1） randomly distributed defect elements to model pre-existing cracks,（2） random modification of rock properties to represent inhomogeneity introduced by different mineral grains, and（3）macroscopic inhomogeneity. Our study, which incorporates laboratory experiments and numerical simulations, indicates that such an approach is helpful in finding a better model not only for simulating experimental results but also for upscaling purposes.
基金funded via an Australian Geophysical Observing System grant provided to Au Scope Pty Ltd.the AQ44 Australian Education Investment Fund programpartly funded by the Western Australian Exploration Incentive Scheme
文摘Detrital zircon U-Pb geochronology has become the gold standard in evaluating source to sink relationships in sedimentary basins. However, the physical and chemical robustness of zircon, which make it such a useful mineral for provenance studies, is also a hindrance as zircon can be recycled through numerous sedimentary basins, thus obscuring the first cycle source to sink relationship. An elegant approach to addressing this potential issue is to compare the Pb isotope composition of detrital K-feldspar, a mineral which is unlikely to survive more than one erosion-transport-deposition cycle, with that of magmatic K-feldspar from potential basement source terranes. Here we present new in situ Pb isotope data on detrital K-feldspar from two Proterozoic arkosic sandstones from Western Australia, and magmatic K-feldspar grains from potential igneous source rocks, as inferred by the age and Hf isotope composition of detrital zircon grains. The data indicate that the detrital zircon and K-feldspar grains could not have been liberated from the same source rocks, and that the zircon has most likely been recycled through older sedimentary basins. These results provide a more complete understanding of apparently simple source to sink relationships in this part of Proterozoic Western Australia.
基金supported by National Natural Science Foundation of China(Grant Nos.11872287 and 51908431)Fund of Shaanxi Key Research and Development Program(Grant No.2019ZDLGY01-10)。
文摘Circumferential yielding lining is able to tolerate controlled displacements without failure,which has been proven to be an effective solution to large deformation problem in squeezing tunnels.However,up to now,there has not been a well-established design method for it.This paper aims to present a detailed analytical computation of support characteristic curve(SCC)for circumferential yielding lining,which is a significant aspect of the implementation of convergence-confinement method(CCM)in tunnel support design.Circumferential yielding lining consists of segmental shotcrete linings and highly deformable elements,and its superior performance mainly depends on the mechanical characteristic of highly deformable element.The deformation behavior of highly deformable element is firstly investigated.Its whole deforming process can be divided into three stages including elastic,yielding and compaction stages.Especially in the compaction stage of highly deformable element,a nonlinear stress-strain relationship can be observed.For mathematical convenience,the stress-strain curve in this period is processed as several linear sub-curves.Then,the reasons for closure of circumferential yielding lining in different stages are explained,and the corresponding accurate equations required for constructing the SCC are provided.Furthermore,this paper carries out two case studies illustrating the application of all equations needed to construct the SCC for circumferential yielding lining,where the reliability and feasibility of theoretical derivation are also well verified.Finally,this paper discusses the sensitivity of sub-division in element compaction stage and the influence of element length on SCC.The outcome of this paper could be used in the design of proper circumferential yielding lining.
基金funding organisations, Curtin International Postgraduate Scholarship (CIPRS)/Department of Mining and Metallurgy Scholarship, and the Mining Education Australia (MEA), Collaborative Research Grant Scheme [grant number RS-59041]
文摘Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces.Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility,cost effectiveness and easy practicability.Reinforcement elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity,knowing that the former is more important.In other words,achieving early stiff behaviour along with large deformation capacity in rockbolts are the goals for new development in rock reinforcement.Yielding rockbolts are expensive while some of them have large deformation capability with low ultimate load capacity.In this paper,modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic conditions.Applying a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground,improves the deformation capacity of the bolt.Additionally,leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of rockbolt.Therefore the dynamic performance of the bolt is improved by these easily applicable modifications.The behaviour and performance of encapsulated rockbolts have been discussed first,then the effects of modifications are illustrated.The proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones.
基金Project(2016YFC0501103)supported by the National Key Research and Development Program of ChinaProject(51574222)supported by the General Program of National Science Foundation of China+1 种基金Project(SKLCRSM15KF01)supported by Independent Research Projects of State Key Laboratory of Coal Resources and Safe Mining,CUMT,ChinaProject(2015)supported by the Mining Education Australia Collaborative Research Grant Scheme
文摘The residue drying area(RDA)is the major source of fugitive red sand(RS)dust emissions in the bauxite mining industry and causes serious environmental and safety detriments.Polymer stabilizer(PS)is one of the promising non-traditional stabilizers to mitigate such issues.This research investigated the unconfined compressive strength(UCS)of RS using synthetic polymer stabilizer(SPS)and natural polymer stabilizer(NPS),and to determine the optimum application concentration and mixing ratio of the PAM and Guar gum mixture.Results illustrated that PAM apparently outperform Guar gum in stabilizing sand particles.The mixture of PAM and Guar gum is more effective than individual use.The optimum polymer concentration and the mixing ratio are 0.94 wt.%and 0.6(PAM:total(PAM+Guar gum)),respectively.A rigorous regression model was developed to predict the UCS value based on application concentration and mixing ratio for the purpose of cost and time efficiency.
基金This work was supported by the National Natural Science Foundation of China(No.5183900341801053),the Science and Technology Research Project of Chongqing Education Commission(KJQN201800724)+2 种基金the Natural Science Foundation of Chongqing(No.CSTC2019JCYJ-MSXMX0835),the Fund(Nos.SKLFSE201903 and SKLBT-19-003)the China Postdoctoral Science Foundation(No.2020M683710XB)the Key Scientific Research Project of Inner Mongolia Universities(No.NJZZ20300).
文摘High stress concentrations around underground excavations can result in significant damage to deep hard-rock mines.These conditions can be the result of stopping activities,blasting,seismicity,or other mining activities.Large anisotropic deformation and excavation closure,especially under high-stress conditions,are expected if the excavation is located in a foliated or thin-bedded rock mass.In this research,the behaviour of excavations under deep and high-stress conditions was investigated and categorised.The main purpose was to enhance the existing knowledge of managing large anisotropic deformations and to help prepare suitable measures for handling such contingencies.Numerical simulations using the distinct element method(DEM)and model calibration were performed to reproduce the anisotropic deformation of an ore drive based on the collected field data.Then,the roles of key factors(i.e.stress ratio,slenderness ratio,foliation orientation,and foliation considering excavation orientation)on the large deformation and damage depth of the excavations were investigated.This study found that increasing both the stress ratio and slenderness ratio induced linear increases in wall closure and damage depth,whereas increasing the foliation angle first increases the deformation and damage depth and then reduces them both before and after 45.The wall closure and damage thickness decreased with increasing orientation intercept.The deformation and damage levels were classified based on these factors.
文摘Wellbore stability is a key to have a successful drilling operation.Induced stresses are the main factors affecting wellbore instability and associated problems in drilling operations.These stresses are significantly impacted by pore pressure variation and thermal stresses in the field.In order to address wellbore instability problems,it is important to investigate the mechanisms of rockefluid interaction with respect to thermal and mechanical aspects.In order to understand the induced stresses,different mathematical models have been developed.In this study,the field equations governing the problem have been derived based on the thermo-poroelastic theory and solved analytically in Laplace domain.The results are transferred to time domain using Fourier inverse method.Finite difference method is also utilized to validate the results.Pore pressure and temperature distributions around the wellbore have been focused and simulated.Next,induced radial and tangential stresses for different cases of cooling and heating of formation are compared.In addition,the differences between thermo-poroelastic and poroelastic models in situation of permeable and impermeable wellbores are described.It is observed that cooling and pore pressure distribution reinforce the induced radial stress.Whereas cooling can be a tool to control and reduce tangential stress induced due to invasion of drilling fluid.In the next step,safe mud window is obtained using Mohr-Coulomb,Mogi-Coulomb,and modified Lade failure criteria for different inclinations.Temperature and pore pressure distributions do not change the minimum allowable wellbore pressure significantly.However,upper limit of mud window is sensitive to induced stresses and it seems vital to consider changes in temperature and pore pressure to avoid any failures.The widest and narrowest mud windows are proposed by modified Lade and Mohr-Coulomb failure criteria,respectively.
文摘Recently,many regression models have been presented for prediction of mechanical parameters of rocks regarding to rock index properties.Although statistical analysis is a common method for developing regression models,but still selection of suitable transformation of the independent variables in a regression model is diffcult.In this paper,a genetic algorithm(GA)has been employed as a heuristic search method for selection of best transformation of the independent variables(some index properties of rocks)in regression models for prediction of uniaxial compressive strength(UCS)and modulus of elasticity(E).Firstly,multiple linear regression(MLR)analysis was performed on a data set to establish predictive models.Then,two GA models were developed in which root mean squared error(RMSE)was defned as ftness function.Results have shown that GA models are more precise than MLR models and are able to explain the relation between the intrinsic strength/elasticity properties and index properties of rocks by simple formulation and accepted accuracy.
基金partly supported by a Grant-in-Aid for Scientific Research (B) from Japan Society for the Promotion of Science (JSPS) to Tsunogae (Nos. 20340148, 22403017)
文摘We report new petrological data and geochronological measurements of granulites from Vesleknausen in the highest-grade section of the L＆#252;tzow-Holm Complex, part of the Gondwana-assembling collisional orogen in East Antarctica. The locality is dominated by felsic to intermediate orthogneiss （charnockite and minor biotite gneiss）, mafic orthogneiss, and hornblende-pyroxene granulite, with deformed and undeformed dykes of metagranite and felsic pegmatite. Pseudosection analysis of charnockite in the system NCKFMASHTO, supported by geothermometry of mafic orthogneiss, was used to infer peak metamorphic temperatures of 750e850 ？C, approximately 150 ？C lower than those estimated for met-asedimentary gneisses from Rundv？gshetta, 6 km to the northeast. SHRIMP U-Pb analysis of zircons from feldspar-pyroxene gneiss, which corresponds to a partially molten patch around mafic orthogneiss, yielded a Concordia upper intercept ages of 2507.9 ？ 7.4 Ma, corresponding to the time of formation of the magmatic protolith to the orthogneiss. Partial melting during peak metamorphism probably took place between 591 and 548 Ma, as recorded in rims overgrew around magmatic zircon. Our results suggest that Rundv？gshetta-Vesleknausen-Strandnibba region in southwestern L＆#252;tzow-Holm Bay, where orthogneisses are dominant, consists of a single crustal block, possibly formed by ca. 2.5 Ga arc mag-matism. The Neoarchean magmatic terrane was tectonically mingled with other fragments （such as metasedimentary units in northern L＆#252;tzow-Holm Bay） by subduction/collision events during the as-sembly of Gondwana supercontinent, and subsequently underwent w850 ？C granulite-facies meta-morphosed during Neoproterozoic to Cambrian final collisional event.
基金the financial support from the Fundamental Research Funds for the Central universities of China (No. 2009KH07)
文摘Coal flotation is widely used to separate commercially valuable coal from the fine ore slurry, and is an industrial process with nonlinear, multivariable, time-varying and long time-delay characteristics. The online detection of ash content of products as the operation performance evaluation in the flotation system is extraordinarily difficult because of the low solid content and numerous micro-bubbles in the slurry. Moreover, it is time-consuming by manual analysis. Consequently, the optimal separation is not usually maintained. A novel technique, called the neuro-immune algorithm (NIA) inspired by the biological nervous and immune systems, is presented in this paper for predicting the ash content of clean coal and performing the optimizing control to the coal flotation system. The proposed algorithm integrates the deeply-studied artificial neural network (ANN) and the developing artificial immune system (AIS). A two-layer back-propagation network was constructed offline based on the historical process data under the best system situation, using five parameters: the flow and the density of raw slurry, the input flows of water, the kerosene and the GF oil, as the inputs and the ash content of clean coal as the output. The immune cell of AIS is made up of six parameters above as the antigen. The cytokine based clone selection algorithm is used to produce the relative antibody. The detailed computation procedures about the hybrid neuro-immune algorithm are minutely discussed. The ash content of clean coal was predicted by NIA using the practical process data s: (308.6 174.7 146.1 43.6 4.0 9.4), and the absolute difference between the actual and computed ash content values was 0.0967%. The optimizing control on NIA was simulated considering two different situations where the ash content of clean coal was controlled downward from 10.00% or upward from 9.20% predicted by ANN to the target value 9.50%. The results indicate that the target ash content and the value of controlling parameters are obtained after several control cycles.
