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Direct strain evaluation method for laboratory-based pillar performance

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第4期11卷 860-866页

作者： K.V.Jessu A.J.S.Spearing wa school of mines Curtin University

Pillar stability is one of important aspects for underground ***,the stability of the pillars is evaluated empirically based on case studies and site-specific rock mass conditions in *** the empirical approach applicability can sometimes be *** numerical-based approaches are potentially more useful as parametric studies can be undertaken and,if calibrated,can be more *** empirical and numerical approaches are dependent on the strength evaluation of the pillars while the strain developing in the pillars is seldom taken into *** this paper,gypsum and sandstone samples were tested in laboratory with different width-to-height ratios (W/H) to adapt the strain evaluation method to the laboratory-based pillars.A correlation was then developed between the strain and the width-to-height ratio for pillar monitoring *** on the results,a flowchart was created to conduct back analysis for the existing pillars to evaluate their stability and design new pillars,considering the strain analysis of the existing pillars with the W/H ratios modelled.

关键词： Failure strain Critical strain Pillars Width-to-height ratio Stability

Froth flotation of refuse coal fines and process optimization using 2D surface plots

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Journal of Central South University 2016年第10期23卷 2520-2525页

作者： Shravan Kumar Veomesh Rawat department of Fuel and Mineral Engineering Indian School of Mines

Refuse coal fines of size <500 μm was collected from a metallurgical coal preparation plant located in the eastern coalfield region of India. The coal was beneficiated using froth flotation technique to recover clean... 详细信息

Refuse coal fines of size was collected from a metallurgical coal preparation plant located in the eastern coalfield region of India. The coal was beneficiated using froth flotation technique to recover clean coal with ash content of about 20% with the highest possible yield. Diesel oil as collector and pine oil as frother were used. Box-Behnken statistical design was followed for analyzing the performance at varying pulp density, collector and frother dosage. Results were discussed using 2D surface plots. Response function predictions determined by the regression analysis show coefficient of correlation(R^2) for yield and the ash content as 0.72 and 0.86, respectively. The highest yield of 45.79% is obtained at pulp density 10%, collector dose 2 kg/t and frother dose 1.5 kg/t. The lowest ash content of 18.9% is obtained at pulp density 10%, collector dose 1 kg/t and frother dose 1 kg/t.

关键词： refuse coal froth flotation Box-Behnken 2D RSM

Development of a drill energy utilization index for aiding selection of drill machines in surface mines

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International Journal of Mining Science and Technology 2017年第3期27卷 393-399页

作者： Kumar Suraj Rahul Talreja Murthy V.M.S.R. department of Mining Engineering Indian School of Mines Dhanbad India

Drill machines used in surface mines, particularly in coal, is characterized by a very poor utilization （around 40%） and low availability （around 60%）. The main purpose of this study is to develop a drill selec- tion methodology and simultaneously a performance evaluation technique based on drill cuttings produced and drilling rate achieved. In all 28 blast drilled through were investigated. The drilling was accomplished by 5 different drill machines of Ingersoll-Rand and Revathi working in coal mines of Sonepur Bazari （SECL） and Block-II （BCCL）. The drills are Rotary and Rotary Percussive type using tri- cone rock roller bits. Drill cuttings were collected and sieve analysis was done in the laboratory. Using Rosin Ramler Diagram, coarseness index （CI）, mean chip size （d）, specific-st trace area （SSA） and charac- teristic particle size distribution curves for all the holes drilled were plotted. The predictor equation for drill penetration rate established through multiple regressions was found to have a very good correlation with an index of determination of 0.85. A comparative analysis of particle size distribution curves was used to evaluate the drill efficiency. The suggested approach utilises the area under the curve, after the point of trend reversal and brittleness ratio of the respective bench to arrive at drill energy utilization index （DEUI）, for mapping of drill machine to bench, The developed DEU1 can aid in selecting or mapping a right machine to right bench for achieving higher penetration rate and utilizations.

关键词： Drill cutting parameter Coarseness index Mean chip size Specific surface area Particle size distribution curves Drill energy ptilization index

Strategies towards statistically robust interpretations of in situ U-Pb zircon geochronology

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Geoscience Frontiers 2016年第4期7卷 581-589页

作者： Christopher J.Spencer Christopher L.Kirkland Richard J.M.Taylor The Institute of Geoscience Research(TIGeR) Department of Applied GeologyWestern Australian School of MinesCurtin UniversityWA 6102Australia Centre for Exploration Targeting-Curtin Node Department of Applied GeologyWestern Australian School of MinesCurtin UniversityWA 6102Australia Australian Research Council Centre of Excellence for Core to Crust Fluid SystemsPerthWA 6102Australia

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.

关键词： Zircon Geochronology U-Pb Geostatistics MSWD

Predictors of work injury in underground mines—an application of a logistic regression model

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Mining Science and Technology 2009年第3期19卷 282-289页

作者： P. S. Paul department of Mining Engineering Indian School of Mines University

Mine accidents and injuries are complex and generally characterized by several factors starting from personal to technical, and technical to social *** this study, an attempt has been made to identify the various factors responsible for work related injuries in mines and to estimate the risk of work injury to mine *** prediction of work injury in mines was done by a step-by-step multivariate logistic regression modeling with an application to case study mines in *** total, 18 variables were considered in this *** of the variables are not directly *** were developed to quantify them through a questionnaire type *** mine workers were randomly selected for the *** from 300 participants were used for the *** variables, age, negative affectivity, job dissatisfaction, and physical hazards, bear significant discriminating power for risk of injury to the workers, comparing between cases and controls in a multivariate situation while controlling all the personal and socio-technical *** analysis reveals that negatively affected workers are 2.54 times more prone to injuries than the less negatively affected workers and this factor is a more important risk factor for the case-study *** term planning through identification of the negative individuals, proper counseling regarding the adverse effects of negative behaviors and special training is urgently *** should be taken for the aged and experienced workers in terms of their job responsibility and training *** should provide a friendly atmosphere during work to increase the confidence of the injury prone miners.

关键词： mine safety logistic model case control study occupational injury

Dielectric and impedance properties of sintered magnesium aluminum silicate glass-ceramic

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Journal of Advanced Ceramics 2013年第1期2卷 71-78页

作者： Abhijit PRASAD Amitabha BASU department of Applied Physics Indian School of MinesDhanbad 826004India

Magnesium aluminum silicate(MgO-Al_(2)O_(3)-SiO_(2),MAS)glass-ceramic was prepared via sintering route.X-ray diffraction(XRD)analysis indicates the formation of multiphase compound with magnesium silicate fluoride and cordierite as major *** studies of the compound shows a strong frequency dispersion of permittivity in the low frequency region followed by a nearly frequency-independent behavior in the high frequency *** presence of alkali ions(K+)in MAS glass-ceramic results in higher dielectric constant and higher *** loss(tanδ)seems to be reduced at higher frequencies after reaching the instrumental saturation at 1 *** properties of the material have been studied using a complex impedance spectroscopy(CIS)technique in a wide temperature(30-500℃)and frequency(100 Hz-5 MHz)*** complex impedance plots reveal the contribution of bulk as well as grain boundary effects in *** bulk resistance,evaluated from complex impedance spectrum,has been observed to decrease with the rise in temperature,showing a typical negative temperature coefficient of resistance(NTCR)*** smaller activation energy(Ea)of the compound within moderate temperature range suggests the presence of ions(K^(+)and F^(-))and singly ionized oxygen vacancies in the conduction *** nature of variation of the electrical conductivity,and the values of activation energy of different temperature regions,suggest that the conduction process is of mixed type.

关键词： glass-ceramic conductivity dielectric properties electrical properties

Investigation of the role of personal factors on work injury in underground mines using structural equation modeling

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International Journal of Mining Science and Technology 2013年第6期23卷 815-819页

作者： P.S.Paul department of Mining Engineering Indian School of Mines

Work injuries in mines are complex and generally characterized by several factors starting from personal to technical and technical to social *** this paper,investigation was made through the application of structural equation modeling to study the nature of relationships between the influencing/associating personal factors and work injury and their sequential relationships leading towards work injury occurrences in underground coal *** variables namely,rebelliousness,negative affectivity,job boredom,job dissatisfaction and work injury were considered in this *** were developed to quantify them through a questionnaire *** mine workers were randomly selected for the *** from 300 participants were used for the *** structural model of LISREL was used to estimate the interrelationships amongst the *** case study results show that negative affectivity and job boredom induce more job dissatisfaction to the workers whereas risk taking attitude of the individual is positively influenced by job dissatisfaction as well as by rebelliousness characteristics of the ***,risk taking and job dissatisfaction are having positive significant direct relationship with work *** findings of this study clearly reveal that rebelliousness,negative affectivity and job boredom are the three key personal factors influencing work related injuries in mines that need to be addressed properly through effective safety programs.

关键词： Structural equation modeling Mine safety Occupational health and safety Work injury

Modified scaled distance regression analysis approach for prediction of blast-induced ground vibration in multi-hole blasting

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第1期11卷 202-207页

作者： Hemant Agrawal A.K.Mishra department of Mining Engineering Indian Institute of Technology (Indian School of Mines)

The blast-induced ground vibration prediction using scaled distance regression analysis is one of the most popular methods employed by engineers for many decades. It uses the maximum charge per delay and distance of monitoring as the major factors for predicting the peak particle velocity(PPV). It is established that the PPV is caused by the maximum charge per delay which varies with the distance of monitoring and site geology. While conducting a production blasting, the waves induced by blasting of different holes interfere destructively with each other, which may result in higher PPV than the predicted value with scaled distance regression analysis. This phenomenon of interference/superimposition of waves is not considered while using scaled distance regression analysis. In this paper, an attempt has been made to compare the predicted values of blast-induced ground vibration using multi-hole trial blasting with single-hole blasting in an opencast coal mine under the same geological condition. Further,the modified prediction equation for the multi-hole trial blasting was obtained using single-hole regression analysis. The error between predicted and actual values of multi-hole blast-induced ground vibration was found to be reduced by 8.5%.

关键词： Peak particle velocity(PPV) Blast-induced ground vibration Scaled distance regression analysis wave superimposition Single-hole blasting

Understanding roof deformation mechanics and parametric sensitivities of coal mine entries using the discrete element method

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International Journal of Mining Science and Technology 2020年第1期30卷 123-129页

作者： Rami Abousleiman Gabriel walton Sankhaneel Sinha department of Geology and Geological Engineering Colorado School of MinesGoldenCO 80218USA

Although conventional coal mine designs are conservative regarding pillar strength,local failures such as roof-falls and pillar bursts still affect mine safety and *** studies have identified that discontinuous,layered roof materials have some self-supporting *** research is a preliminary step towards understanding these mechanics in coal-measure *** others have considered broad conceptual models and simplified analogs for mine roof behavior,this study presents a unique numerical model that more completely represents in-situ roof *** discrete element method(DEM)is utilized to conduct a parametric analysis considering a range of in-situ stress ratios,material properties,and joint networks to determine the parameters controlling the stability of single-entries modeled in *** results are compared to empirical observations of roof-support effectiveness(ARBS)in the context of the coal mine roof rating(CMRR)*** such as immediate roof displacement,overall stability,and statistical relationships between model parameters and outcomes are presented *** practical applications of this line of research include:(1)roof-support optimization for a range of coal-measure rocks,(2)establishment of a relationship between roof stability and pillar stress,and(3)determination of which parameters are most critical to roof stability and therefore require concentrated evaluation.

关键词： Numerical modeling Discrete element method Coal mine roof rating analysis of roof bolt systems Sensitivity analysis Strain softening ubiquitous joints Discrete fracture network