Search Documents

By K. Woodward, Y. Potvin, B. McFadyen, M. Grenon

Open stoping has become a popular mining method in hard rock mines, not only due to the safety of the method as a non-entry approach, but also because of the high extraction rate and low costs. At mine sites, stope performance is evaluated by calculating stope overbreak using the stability chart. However, limitations of the stability chart regarding the precision of the predictions, nonconsideration of factors such as the influence of blasting, and the exclusion of underbreak have led to non-optimal designs. The capabilities of today's computers have increased the amount of data being collected and the power of models being built. This article presents a step towards a new stope design approach where stope overbreak and underbreak are measured and georeferenced using octrees at an approximately cubic metre resolution and predicted using multivariate statistical models (partial least square, linear discriminant analysis, and random forest). Results show that overbreak and underbreak location along the design surface and their magnitude are predicted with good precision using a random forest model. These predictions are used to build the expected geometry of the open stope. The resolution of the data and the use of multivariate analysis has enabled the prediction of variation in stope performance along the design surface, going well beyond the simple qualitative per stope face prediction provided by a traditional stability chart approach.

Jun 5, 2023

By R Brake

The Enterprise Mine (EM) is located at Mount Isa and is wholly owned by Mount Isa Mines Limited (MIM). This high-grade copper mine extends from about 1000 m below surface to almost 2000 m below surface. A recent $400 million upgrade has taken the operation from a production rate of 1.3 Mtpa to a capacity of 3.5 Mtpa. The effects of high surface ambient temperatures in summer, combined with the depth of the mine and high virgin rock temperatures results in heat stress in the working place that, without intervention, would exceed the levels that human physiology can withstand. It would also result in significant decreases in productivity and high accident rates even where work is possible. Moreover, with a very hot and deep mine, the needs of æegressÆ and entrapment of workers during a mine emergency must be carefully considered. Enterprise Mine has taken a æsystems approachÆ to the issue of working productively, healthily and safely in heat. This involves setting limits of thermal stress for workers, understanding productivity decrements when working in heat, establishing productive and healthy environmental targets, developing engineering solutions to meet these targets, creating a well-educated workforce with respect to working in heat and then developing health protocols to ensure workersÆ health is protected. Refrigeration must be added to the mine to provide acceptable and productive conditions underground. By the time the mine is commissioned in 2000, Enterprise mine will have an installed refrigeration capacity of in excess of 40 MW(R). The ventilation engineering principles proven over many years at the other Isa underground mines are tailored to æfloodingÆ the mine with air to remove the heat, which is the main contaminant. This principle will not work at the Enterprise Mine, for reasons discussed below. With the underlying ventilation principle no longer satisfactory, a complete review of the entire ventilation principles and engineering solutions was required for the Enterprise Mine.

Jan 1, 2000

By D. Sprott, P. A. Kirsch, J. Harris, D. Cliff

This paper details the work of RISKGATE, the largest Australian Coal Association Research Program (ACARP) occupational health and safety initiative to date. The program is an interactive online risk management system developed to maximize health and safety performance in the coal mining industry by implementing continuous improvement in managing major unwanted events. The comprehensive knowledge base covers tires, collisions, fires, isolation, strata control underground, ground control open cut, explosions, explosives, manual tasks, and slips/trips/falls. All major Australian coal mining companies contributed topic experts to this broad industry initiative: nine coal mining companies, more than 80 experts, and more than 400 days of individual time for knowledge-capture workshops.

Jan 1, 2014

By P. L. Woolf, N. Bernstein, M. M. Fine

Continuous experimentation utilizing a 3- by 36 - foot rotary kiln was conducted to demonstrate the feasibility of simultaneous induration and reduction of magnetic taconite concentrate . Lignite , or lignite - anthracite mixtures , and green magnetite pellets (64.2 percent Fe , dry basis ) were heated in a rotary kiln to about 2,100 ° F. After separation from excess reductant , the product pellets were found to be highly reduced and acceptably hard . A total of 140 tons of prereduced pellets with an average Fe content of 79.0 percent was produced at Minneapolis and smelted in the Bureau's experimental blast furnace at Bruceton , Pa . Two additional supplies of prereduced pellets were obtained from The Steel Company of Canada , Ltd. , Hamilton , Ontario , which contained 83.8 and 91.3 percent Fe , respectively . Smelting of prereduced pellets was compared with that of unreduced pellets obtained from The Hilton Mines , Shawville , Quebec , and from the Erie Mining Co. , Hoyt Lakes , Minn . Blast furnace tests established that a substantial decrease in coke rates and higher production result from the use of prereduced pellets .

Jan 1, 1964

By Manoj Khandelwal, Jian Zhou, Yingui Qiu, Peixi Yang, Pingan Peng

Rockburst prediction is crucial in deep hard rock mines and tunnels to make safer working conditions. Due to the complex interaction of many factors involved in rockburst prediction, such as multi-variable and multi-interference factors, three hybrid support vector machine (SVM) models optimized by particle swarm optimization (PSO), Harris hawk optimization (HHO), and moth flame optimization (MFO) are proposed to predict rockburst hazard level (RHL). The RHL is determined according to four kinds of microseismic characteristic parameters including angular frequency ratio, total energy, apparent stress, and convexity radius. Then, six types of microseismic characteristic parameters are taken as input variables in 343 sets of data, including angular frequency ratio and total energy, etc.. And the RHL is taken as the output target of rockburst prediction. The classification performance of PSO-SVM, HHO-SVM, and MFO-SVM hybrid models is evaluated by accuracy (ACC), precision (PRE), and kappa coefficient. Findings reveal that the MFO-SVM model performs best in terms of accuracy, with ACC, PRE, and kappa coefficients reaching 0.9559, 0.9063, and 0.9094 respectively, while PSO-SVM and HHO-SVM have similar performances. However, the PSO-SVM, HHO-SVM, and MFO-SVM all perform better than the unoptimized SVM model. This confirms that the three optimization algorithms significantly enhance the rockburst prediction capacity of the SVM model to help mine practitioners apply machine learning methods to rockburst prediction problems appropriately.

Feb 3, 2023

By J. C. N. Ashukem, F. Agyemang

One understudied area of environmental law is the socio-ecological impact of ownerless mines. This impact is particularly pronounced in resource-dependent regions like South Africa and Western Australia, creating significant rehabilitation challenges. This article hypothesises that effectively managed financial provision could be valuable for rehabilitating legacy mines. Using a qualitative, comparative methodology, the article analyses the financial provisions for mine rehabilitation in South Africa and Western Australia, focusing on statutory provisions, funding mechanisms, and rehabilitation outcomes. Key themes, such as context, measures, and outcomes, are explored to assess the effectiveness of each financial model. Purposive sampling is used to select case studies from both regions, and thematic analysis is applied to interpret the data. The analysis highlights the financial rehabilitation measures in both regions, providing a structured framework for ownerless mine rehabilitation. South Africa's approach, guided by the Mineral and Petroleum Resources Development Act (MPRDA) of 2002, depends on state budget allocations, leading to funding inconsistencies and slow rehabilitation progress. In contrast, Western Australia’s Mine Rehabilitation Fund Act (MRFA) of 2012 uses a levy-based system, ensuring continuous financial support for mine rehabilitation. South Africa's state-dependent model has led to delays in rehabilitating derelict and ownerless mines, while Western Australia’s funding model has facilitated steady progress. The article recommends that South Africa adopt a levy-based financial mechanism, strengthen legislative enforcement, improve financial oversight, and integrate proactive mine closure strategies to accelerate rehabilitation, reduce environmental hazards, and promote sustainable development in mining-affected communities.

Dec 15, 2025

This publication contains four papers presented at a seminar on mine subsidence control held in Pittsburgh, PA, on September 19, 1985. The seminar was designed to keep the mineral industry informed of new technology developed by the Bureau of Mines that permits reliable and accurate prediction of mine subsidence. The papers describe actual field studies undertaken by the Bureau to monitor surface subsidence over longwall panels. Topics discussed include the efects of subsidence on water table levels, the development of subsidence pre calculation methodology suitable for use with the specific lithological conditions of the Pittsburgh coalbed, an engineering comparison of technologies used in surveying for longwall mine subsidence, and a comparison of the process of subsidence over two different longwall panels.

Jan 1, 1985

By Susumu Uchiyama

This machine was manufactured for excavation of the Roppongi station of the Tokyo Metro Line 12. This machine can excavate both the platform and the rail track at the same time in locations where the traffic is congested and has following features: A multi-centered TBM of the size of 7.06(H) x 13.18(W) m The world first H&V TBM, with right and left machine parts articulated vertically and separately for position control A large erector for simultaneous erection of column and central segments of special shape to construct a highly reliable tunnel This paper reports the design concept, construction, and work record.

Jan 1, 1999

By Robert H. Peters

This U.S. Bureau of Mines report identifies the types of serious accidents that occur most frequently at small underground coal mines and describes the strategies that could help prevent these accidents. A wide variety of methods for improving safety are suggested, including improvements in the design of equipment, work procedures, work schedules, safety programs, and emergency response plans, as well as techniques for diagnosing the potential hazards associated with new technologies and work procedures. Some of the papers in this volume focus on preventing specific types of mining accidents--ones associated with materials handling (primarily back injuries), equipment maintenance, improper machine guarding, and ground failure during retreat mining. Although the recommendations in this volume are heavily influenced by research performed at underground coal mines in the Appalachian coalfields, most of the papers contain advice that is equally pertinent to almost any type of mine.

Jan 1, 1994

By A. Brown

This report details work performed and results obtained in a study of the water management aspects of oil shale mining and retorting in the Piceance Creek Basin. Three specific sites were investigated, and optimal water management systems for both conventional and in-situ extraction processes were generated. Water-related legal and environmental constraints on development were identified and the water management schemes were developed in compliance with these regulations. Limitations on shale oil production implied by limited water supplies were evaluated. Potential Basin-wide effects of development were evaluated using a computer model, and mitigation strategies were developed. Recommendations for additional investigation and analyses were presented.

Jan 1, 1977

By W. R. Marks

Computer-aided torsional analysis of grinding mill drives is defined and related to the mill design process. Equations of torsional dynamics are developed for general mechanical drives. Consideration is given three solution types - specifically the determination of undamped natural frequencies, the calculation of steady vibration amplitudes, and the prediction of transient torques during starting. Following a summary of the methods of calculating drive motor performance, the problem in making practical application of this theory are discussed. Experiences in both calculating and measuring the torsional loads on a large ball mill with dual synchronous motors are reviewed. Conclusions are drawn on the effectiveness of computer-aided torsional analysis for improving mill drive reliability.

Jan 1, 1984

Jan 1, 2002

By W. -C. Huang

In this paper, a methodology for the reliability assessment of geogrid-reinforced unpaved roadways is presented, by taking into account the variability of the subgrade?s undrained shear strength. Analyses are performed using the Point Estimate Method and the Monte Carlo simulations technique. The undrained shear strength is represented by its correlation with the California Bearing Ratio and it is modeled as a random variable following a long-normal distribution. Analyses are performed for different types of reinforcement. The study provides a quantitative assessment of the variation of the system?s probability of failure with this parameter. Overall, the approach suggested in this study may be considered as a complementary approach on the traditional concepts of global or partial safety factors.

Jan 1, 2008

By Michael R. Walsh, John H. Wright, Eivind B. Jensen

A tunnel boring machine (TBM) was designed and built at the Cold Regions Research and Engineering Laboratory in 1992 for use in Antarctica. The TBM system was tested at the South Pole where a 120-m long tunnel was bored to prove the concept. Modifications were made to the system resulting from this work. In 1999,boring of a 600-mutilidor began as part of the new South Pole Station. Tunneler hydraulics reliability problems prevented the completion of the tunnel before the end of the short construction season. This paper discusses the design and operation of the TBM, proposed solutions to the problems encountered, and current operations of the system.

Jan 1, 2001

By Fang-tu Wei

The purpose of developing this system is to monitor the operating status of the fully mechanized mining system in order to raise it's reliability. The completely mechanized coal mining system is a complex dynamic system, involving many sub-systems. It is the key of the mining process as well as a connected system composed of each working procedure. Any hitch in breaking, loading or transporting will interrupt the mining process. The analyses of the operating data has proved that the reasons causing the interruption of the extracting processes mainly come from the inner of coal face. Hence, after the installation of the MINOS system in England, the delays of belt conveyor sub-system were reduced. But the production increment was not as much as expected.

Jan 1, 1986

Coal exploration and mine planning now use all the modem techniques to indicate geological hazards to a new or developing coal mine. Drilling, seismic and other sophisticated geophysical methods aim to increase the reliability of prediction of features which will inhibit mine development. But do they?. During the past 40 years, geological investigations for coal mines in New South Wales have ranged from the general observations of Eric Rudd, in the Southern Coalfield in the late 1940s to the very detailed examinations of roof strata by John Shepherd and others in the 1980s. Then, the large scale regional relationships between sedimentary and structural features often were ignored as the minute examination of seam roof strata became fashionable.

Jan 1, 1991

By LaMar G. Evans

The rapid determination of uranium in ores by radiometric means was investigated by the Bureau of Mines. Among the various procedures and schemes tested, two showed most promise. They were the ratio scheme developed in the Bureau's Tucson, Ariz., laboratory and the equilibrium method developed by the Canadian Department of Mines and Technical Surveys. The ratio method is a simple, empirical procedure for classifying the state of equilibrium in ores by measuring their radioactivity by means of a Geiger-Muller counter under three different conditions, using filters. The principal merit of the method is in providing a clue as to the reliability of equivalent uranium determinations.

Jan 1, 1958

To improve communication among Government, industry, and academic researchers in the field of thermodynamics, the Federal Bureau of Mines sponsored a Workshop on Techniques for Measurement of Thermodynamic Properties in August 1979. Participants at the workshop presented 33 papers on the subjects of temperature measurement and control, general calorimetric techniques, low-temperature calorimetry, high-temperature calorimetry, galvanic cells, ionic solutions, and heterogeneous phase equilibria. A special invited lecture was presented by E. F. Westrum, Jr., on the resolution of lattice heat capacity. This Information Circular comprises the proceedings of the workshop and includes the texts of papers presented and discussion by attendees.

Jan 1, 1981

By Henry Kreisinger, WALTER T. RAY

This preliminary bulletin was written as the first of a series of several on the significance of drafts in steam-boiler practice, the succeeding bulletins to be along the same lines but of a more advanced character. The conclusions arrived at are tentative, and are the result of a study of one of the many problems growing out of a general plan of the United States Government to increase the efficiency with which the coals of the country are being used. Greater efficiency requires better boiler and furnace design. The experimental study of drafts on which the conclusions presented in this bulletin are based formed part of the fuel-testing investigations that were carried on by the technologic branch of the United States Geological Survey and have been transferred to the Bureau of Mines. The experiments made seem to indicate that it is possible to double or treble the capacity of a plant without making any radical changes the furnaces and boilers. These increases require about double and treble the quantities of air to be put through the fuel beds and boilers. It also seems probable that rebafHing the boilers will often permit the capacity to be doubled or trebled, while still getting more steam than formerly per pound of coal for uses outside the boiler room. These experiments were undertaken with the object of clarifying ideas concerning the passage of air through fuel beds and boilers. Measured weights of air were passed through two beds of lead shot, series, one of which remained always the same and represented a boiler; the other being varied as to size of shot and depth of bed, and representing a fuel bed. Careful observations were made of the weight of air passing through the beds per minute. All data were plotted in many charts, so as to permit the study of them from several points of view. A number of laws were deduced bearing on the relative amounts of power required to force air through fuel beds of various thicknesses, composed of various sizes of coal, and through boilers of various lengths and areas of gas passages. An important part of the discussion relates to an increase in the capacity of boilers by increasing the amount of power applied to pressure and exhausting fans and thus forcing several times as much air through the fuel beds and boilers. may be possible, as a result of these investigations, to raise the rate of working the boiler heating surface to three or even four times its present value. Such an increase would undoubtedly mean new designs of grates, stokers, furnaces, and boilers, especially fitted for high rates of working. Fan equipments designed to supply three or four times as much air under several times the pressure would be provided with more efficient engines, thus giving an additional factor favoring high-capacity working. It must be borne in mind, as stated above, that the results are tentative. It will cost money to force gases at high speeds through fuel beds and boilers, and there will soon be pressing need of such quantitative data as will enable the largest possible part of the energy imparted by the fans to be advantageously utilized. We desire, to thank our superiors, especially Messrs. L. P. Breckenridge and D. T. Randall, for their helpful criticism and suggestions.

Jan 1, 1911

By F. B. TOUCH

This bulletin deals with a topic that is exceedingly wide, and will doubtl~ be under consideration and discussion so long as there are enough known deposits of oil and gas remaining in the earth to make their revelopment profitable. The Bureau of Mines has repeatedly called attention to the importance of protecting oil or gas sands from the encroachment of water, and the purpose of this paper is to summarize existing knowledge of methods and devices. Water may gain access to an oil-bearing formation from several sources-from water sands above or below those. containing the oil, or by encroaching through the oil sands as the oil is withdrawn. In short, it may enter a well from the "top, bottom, or side." Such ingress of water is a most serious detriment to the recovery of oil from the ground. As the art of drilling and developing oil properties has progressed, increasing thought, labor, and money have been expended on various methods, devices, and equipment for arresting the migration of water from its normal subsurface position into the porous strata containing valuable oil or gas accumulations. At an early stage in the oil-field development of California, it became evident that considerable modification of accepted drilling practices was necessary in order to meet the conditions imposed by the poorly consolidated shale, clay, sand, and bowlder beds penetrated, as well as the hard layers of sandstone and calcareous shale, which vary greatly in thickness, hardness, and frequency. These hard streaks are commonly called " shell," and are so reported in the well logs. As deeper and deeper territory was prospected, drillers from the older fields of the Ea,st, as well as from Texas and Louisiana fields, took part in the operations. Xhe practice evolved was thus based on the wide experience of a most cosmopolitan group of men who, considered as a group, were not hampered by being limited to the knowledge of the practice at any one locality.

Jan 1, 1918