Search Documents

By A. J. Goodman

Introduction The position of Turner Valley in the foothills of Alberta, some thirty-five miles southwest of Calgary, is too well known to need further description. This attempt to interpret in detail the nature of the structure, and its relationship to neighbouring structures, together with general observations on the foothills belt, is based on work carried out in the office of the Supervisory Mining Engineer, at Calgary. The object in view was the correlation of the mass of evidence which had accumulated from the detailed examination of drill cuttings, and to discover, if possible, its structural significance. Unfortunately it is not possible to publish most of this detail owing to its confidential nature, and in consequence the reader is asked to accept certain statements, which under other circumstances would not be made without supporting evidence. The main argument for the general structural interpretation rests on evidence which has already been made public, and it is possible to proceed to logical conclusions on the main points. The evolution of ideas concerning the structure of Turner Valley is somewhat difficult to follow, as, compared with all that has been said on the subject, there is not a great deal on record.

Jan 1, 1930

By Stephen C. Tadolini, Anthony T. Iannacchione

"Coal burst represented a major hazard for some U.S. mining operations. This paper provides an historical review of the coal burst hazards, identifies the fundamental geological factors associated with these events, and discusses mechanisms that can be used to avoid their occurrences. Coal burst are not common in most underground mines. Their occurrence almost always has such dramatic consequences to a mining operation that changes in practice are required. Fundamental factors influencing coal burst events include strong strata, abnormal strata caving, elevated stresses, critical size pillars and the lack of sufficiently sized barrier pillars during extraction. These factors interact to produce excessive stress, seismic shock and loss of confinement mechanisms. Over the 90 years of dealing with these hazards, many novel prevention controls have been developed including novel mine designs and extraction sequences, most of which are site specific in their application. Without an accurate assessment of the fundamental factors that influence coal burst and knowledge of their mechanisms of occurrence, control techniques may be misapplied and risk inadequately mitigated. INTRODUCTIONCoal burst1are violent failures of ribs, roof or floor in underground mines. They are known to occur in complex ways and often under unique sets of conditions. This has made them extremely difficult to anticipate and control. Assessing coal burst risk requires engineers, managers, and safety professionals to recognize the fundamental factors responsible for these events. This helps practitioners recognize the hazard potential and understand the context in which various controls and barriers should be used. Only then can coal burst events be anticipated andappropriate mitigation techniques deployed.Over the last 90 years, a few coal burst events have been anticipated but most have eluded prediction. The authors examined the historical record (Appendix A) and determined that an inadequate understanding of the initiating geologic factors and their associated mechanisms of occurrence have contributed to the poor predictive capability. The historic record also indicates that control techniques have typically been site specific in their application."

Jan 1, 2015

By P B. Hills

Increasingly over the past couple of decades, the importance of understanding the in situ stress regime in underground hard rock mines has become accepted by all. Providers have responded to this requirement and various techniques for undertaking the measurements have been honed while others have slipped from use. It is a simple, though not inexpensive task to engage a provider to undertake the require measurements, and a comprehensive report will ensue. So, what has actually been obtained? What should the geotechnical engineer do next? What tools are necessary to do so? Regardless of the method of measurement, the report will describe the location of the measurement site and describe the basis of the methodology used in undertaking the measurements and a log of the measurement program. Finally, it will include the results, which should incorporate the normal and shear stress components of the full stress tensor. Ground control management plans (GCMP’s) and stress summary reports and spreadsheets prepared by site geotechnical engineers always include the magnitude, trend and plunge of the principal stresses. Remarkably few site-based summaries include the full stress tensor. This is a significant gap as the full stress tensor is vital for any further data manipulation. However, without the algebraic tools to undertake those manipulations, their value is diminished. This paper seeks to provide a checklist of ideas to be considered. It provides commentary on the options available to dissect the stress measurement report and ensure that the maximum possible value is derived from it. The manipulation and presentation of component stress data is also discussed. The various methods of stress measurement are not the focus of the paper but some of the strengths and weaknesses of them over which the site geotechnical engineer has some control, are highlighted.

Nov 29, 2022

By Panshi Xie, Yan Chen, Shaogang Wu, Yang Hang

In order to realize the intelligent mining of coal seam with large dip Angle, this paper adopts the methods of large proportion variable Angle loading threedimensional physical simulation experiment, numerical simulation and field measurement with digital twin technology. The hydraulic support with large dip Angle and large mining height is used as the prototype to design the physical entity model of 1:5 hydraulic support, combined with modeling and graphics rendering technology. Angle, displacement and load sensors were selected and placed to realize the data channel between the lower machine and the upper computer of the digital twin system, so that the position and load data of the physical entity model and the twin model of the laboratory hydraulic support could be shared in real time. Moreover, the multi-dimensional dynamic and static load transfer law and the position evolution characteristics of the support and surrounding rock under different inclination angles were analyzed. The results show that: with the increase of the Angle of the working face, first, the initial support force required by the support decreases, and the damage degree of the roof increases; When the roof is soft, the lifting operation can avoid the instability of the support to a certain extent. Second, under the action of positive pressure, the load of the top beam under different angles is balanced; Under the backpushing action, the load in the upper inclined area of the shield beam increases gradually, while the load in the lower inclined area decreases gradually. Under the lateral push, the load changes periodically, and the load in each cycle is increased compared with that in the previous cycle. Third, the numerical simulation analysis shows that the load on the lower bracket is less than that on the upper bracket, and the load on the bottom of all the columns is greater than that on the middle and upper brackets. In order to reduce the impact of the columns on the bottom plate or the base, it is necessary to improve the anti-subsidence ability of the base. Finally, according to the research results, the improvement and optimization measures of the support are put forward, and the field test shows that these measures effectively solve the problems of sinking, sliding and tipping of the support in the working face with large inclination Angle, and obtain good application results.

Feb 1, 2024

By E. L. Gillenwater

Coal mine planning has three distinct decision levels: (1) decisions made at the upper level of management that determine production requirements for specific mines, (2) decisions made at the middle management level, the mine level, that determine how the mine satisfies its production requirements, and (3) decisions made at the operating level of management, the sectional level, that determine the sequencing of machine movements at the face. In this paper, the underground production scheduling problem is formulated in multi-stages using the Hierarchical Production Planning (HPP) approach. Two linear programming HPP models for accomplishing decisions at the first two levels are developed. Both models address the aggregate production planning process. The Mine Production Scheduling (MPS) model permits determination of monthly production and inventory levels. The Section Production Scheduling (SPS) model incorporates a quality blending requirement into the determination of weekly sectional production and inventory levels.

Jan 1, 1995

By R. W. Van Dolah

An investigation was made of the distances over which sympathetic detonation of ammonium nitrate (AN) and ammonium nitrate-fuel oil (AN-FO) might be expected. Large-scale gap tests used two types of AN-FO donor charges in three sizes with AN, both at ambient and elevated temperatures, and AN-FO acceptor charges. Donor sizes were varied to test the validity of a scaling law commonly used in quantity distance tables. The up-and-down experimental design was chosen to determine the 50-percent initiation point efficiently. The acceptor charges were instrumented to indicate initiation and to determine detonation velocity. Other electronic techniques for measuring the rate of growth, stability of detonation, and detonation pressures were employed. Air shock and fragment velocities between charges were measured by electronic and photographic methods, and determination of side-on air-blast pressures and impulse duration were made for about half the shots. Separation distances between donor and acceptor were found to be larger than anticipated both for the AN and the AN-FO. With AN-FO acceptors and a 16-gage steel faced donor, one initiation occurred at a separation of 53 feet or nearly 16-charge diameters; with AN, initiation occurred at 4 to 5-1/2- charge diameters.

Jan 1, 1966

By Jr. Langhans, J. S. McPartland

"The presence of zinc in cyanide solutions is generally thought to not have an adverse effect on precious metal recovery or recovery rate by heap leach processing. However, analytical interferences of zinc in solution can cause problems in accurately determining and controlling cyanide concentration in the leach solution, leading to increased cyanide consumption. Analytical methods and the chemistry of cyanide in the presence of zinc are reviewed. The effects of solution pH and zinc concentration on the free cyanide determination were evaluated in detail. Use of the standard silver nitrate titration and a modified titration method for controlling cyanide concentration during heap leaching were investigated experimentally. The practical implications of cyanide heap leaching in the presence of cyanide soluble zinc minerals are discussed.IntroductionThe presence of zinc in precious metal cyanidation circuits is not uncommon. Zinc can be introduced into cyanide leach solutions through dissolution of various zinc minerals1>, or through the use of a Merrill Crowe (zinc precipitation) circuit. Zinc minerals typically occur infrequently and in low concentration in gold ores, but are more abundant in silver ores. Merrill Crowe systems are most commonly employed for recovery of precious metals from solution for relatively high silver ores. It is desirable to control the amount of dissolved zinc in a cyanidation circuit for several reasons. Excessive zinc build-up in cyanide leach solution can, under certain circumstances, inhibit precious metal dissolution and adversely affect solution recovery systems. Additionally, high zinc concentrations can lead to excessive in-process cyanide inventories and potentially, to higher cyanide consumption"

Jan 1, 1999

By M. E. Tyrrell, J. Koster

This work was undertaken to determine the feasibility of making mixed diborides of two metals directly from the metal oxides , boron carbide and carbon . The diborides (Ti , V ) , B₂ , (Ti , Cb) B₂ , and ( Ti , Ta ) B₂ were prepared in a crucible resistance furnace at 2,100 ° C , and X- ray- diffraction analyses showed each was a homogeneous solid solution containing approximately equal molar contents of the given diborides . The diboride powders were cold - pressed ; sintered to 2,300 ° C , and evaluated for mechanical strength , rate of oxidation , and resistance to molten metals . The diboride ( Ti , Ta ) B₂ exhibited the best mechanical properties ; the diboride ( Ti , Cb ) B₂ , the lowest cumulative rate of oxidation . The mixtures were stable in the presence of molten aluminum and copper but were attacked by molten Ti , Zr , and Cr .

Jan 1, 1964

By Paul B. Queneau

Formulation and commercial utilization of solid-waste incinerator slag by-product is the focus of this paper. Particular attention is given to iron aluminosilicate melts having compositions similar to that of nature's basalt The earth?s crust can be viewed as an environmental laboratory for predicting stability of various silicates; small-scale laboratory experiments are necessary to confirm findings there from. An ideal slag consumes flux additives at acceptable cost, is compatible with furnace refractory, flows readily from the furnace, and has physical properties suitable for its commercial utilization -all within the critical constraint that the slag is environmentally stable. Examples of successful solid waste slagging practice, including tonnage, utilization and pricing, are provided from metallurgical and waste treatment operations of North America. Western Europe and Japan.

Jan 1, 1991

By Gaby Steinbach

A novel synthesis is described for the preparation of supported gold catalysts for low-temperature CO oxidation. The novel route is a variation of the inverse co-precipitation method and requires amphoteric metal hydroxides, with zinc and aluminium hydroxides chosen. Catalysts were prepared by inverse co-precipitation (ICPa) and by the novel route (ICPb) and tested for CO oxidation at 60ºC. Preliminary results showed the novel route to be superior to ICPa; the catalysts prepared by ICPb showed higher catalytic activities. The effect on catalytic activity of parameters such as pH, calcination temperature, washing of precursor and calcined catalysts and ageing was investigated. A preparation pH of 9 and a Zn to Al mass ratio of 3 proved to be optimal. It was possible to remove residual chloride by washing thereby enhancing catalyst performance. Ageing and Mg citrate addition were also shown to improve catalyst performance. Characterization of the catalysts revealed that better activities were obtained when the support was more crystalline and had a higher surface area. The presence of carbonate-containing species in the support decreased catalytic activity. 197Au Mössbauer Spectroscopy revealed the presence of Au3+ when catalysts were heat-treated at temperatures of 200ºC and below. Catalysts calcined at 400º had 75% of the gold present as Au0, with the remaining gold present as Au3+.

Oct 1, 2003

By Walter Greaves

THIS paper describes a series of tests performed at the Hollinger mill during the past four years, in which both metal and rubber-lined pumps were used for pumping sand and slime. While conditions will not be the same at other mills, it is felt that the information gained from the tests should be of value to other operators and of assistance to them in selecting the most efficient size of pump and kind of lining for economical operation. For the successful operation of pumps with rubber linings there are certain conditions, which, if recognized at the outset, will save the operator a good deal of work and trouble. First is the necessity of keeping sharp pieces of steel, or anything that might cut the lining, out of the pumps. This can be effected by placing screens in the proper locations. Second is to recognize the fact that the rubber lining of the shell, and the rubber cover of the impeller, are subjected to very different conditions. The shell lining, :being at rest and well supported by the metal case, has a relatively easy job compared ? with the impeller covering, which is subjected to centrifugal force and has a tendency to tear itself away from the metal core. Also, the pulp travels through and past the impeller at a high velocity. These two factors, centrifugal force and velocity of the pulp, would appear to set a limit to the speed at which, for a given set of conditions, it is economical to run a rubber-covered impeller. Therefore, a pump should be large enough for the work to be done. To get the best mechanical efficiency, it must be operated somewhere near the limit of its capacity, but this may not give the best overall cost, because the saving in power, due to the high efficiency, may easily be lost through excessive wear on the lining. It would appear that this condition is more critical in a rubber-lined pump than in one lined with metal.

Jan 1, 1939

By S. Utili

"The optimal profile of a rock slope under given geometry constraint is investigated by means of the upper bound method of limit analysis. The optimal condition corresponds to maximizing stability factor. It is assumed that rock failure condition is suitably described by the Hoek-Brown criterion. Genetic algorithm is applied for locating the optimal profile. The optimal profiles turn out to be concave profiles but there are heaps around the toes of the slopes. Compared with plane profiles, the percentage of increase in stability factor can reach up to nearly 50%. The key geometry parameters of the optimal profiles are provided for practical use. The new upper bound formulation is capable of computing the stability factors of slopes of any shape, thus the stability status of a slope under man-made excavation can be monitored during the whole construction period.INTRODUCTIONIn mining industry, man-made slopes are excavated to create working surfaces. It is important to optimize the slope profile in order to maximize slope stability under certain geometry constraint. For instance, when the height and width of an excavation are assigned, a plane profile AC (see in Fig. 1) is widely applied in engineering practice, but it has been proved not the best one in terms of safety (Utili & Nova, 2007; Cala, 2007). A vertical profile ABC is the one with least stability. Thus, it can be deduced that there is a profile within the domain of the rectangle ABCD providing the highest stability. Cala (2007) compared the difference of convex and concave profiles in stability using strength reduction technique. According to Cala (2007), circular concave slopes can increase the maximum slope inclination under given factor of safety. Besides, based on upper bound theory of limit analysis, Utili & Nova (2007) assumed a logarithmic spiral profile to prove it is more stable than a plane profile in terms of the stability factor. Although the above studies attempted to seek the best circular or logarithmic spiral profiles, none of them considered the arbitrary shape of the optimal profile and its contribution to enhance slope stability."

Jan 1, 2015

By John C. Machisak

INJURY DATA and experience at, coal mines in the United States for 1953 and 1954 are presented in this publication with a minimum of interpretation and comment because of the numerous tables required to afford detailed comparisons between the 2 years. Corresponding tables for 1953 and 1954 follow in consecutive order under the following general sections: (A) General injury experience: Tables 1 to 11: Contain current data on number of fatal and nonfatal injuries, frequency and severity rates, and average severity and time-loss rates. (B) Selected injury data: Tables 12 to 85: Contain current data on causes of injuries, distribution of injuries by part of body injured, days of disability, extent of hand and machine loading, experience by employment and production groups, and various other operating factors and physical conditions related to the occurrence of injuries at the Nation's coal mines.

Jan 1, 1958

By S. M. Runke

The pegmatite investigations at the Rapid City, S. Dak., Experiment Station during; the pact 3 years have been primarily a study of recovering beryl from nonlithium-bearing pegmatite rock by continuous-testing methods. Beryl concentrates containing 25 to 88 percent beryl were produced from rock that ranged in beryl content from 0.1 to 2.5 percent. The beryl recovery ranged upward from 70 percent but averaged better than 80 percent. Although promising results have been obtained with flotation methods for upgrading these concentrates to standard specifications, additional work is needed to improve and simplify the procedure. In addition, it was demonstrated that several potentially useful coproducts could also be recovered from pegmatite rock. The principal coproducts were mica, feldspar, and quartz. A heavy-mineral product also was made from pegmatites containing tin, tantalum, and columbium. The recovery if these minerals in products meeting the specifications of the commercial users has been reserved for future study. The investigations also included studies on extraction of beryllium from both high-grade beryl and flotation concentrates of medium beryllium content. The procedure investigated consisted of sintering beryl or beryl flotation concentrates with limestone, acid curing the resulting sinter with sulfuric acid to dissolve the beryllium, and water leaching to extract the beryllium. Over 90 percent of the beryllium was extracted by this procedure. Most of the optimum conditions and quantities of reagents were determined for dissolving the beryllium. As aluminum and iron also were taken into solution by the acid, further research is needed on methods of recovering high-grade beryllium salts from the solutions containing these elements.

Jan 1, 1957

By AIME AIME

AN unusually interesting meeting devoted to the discussion of the ways and means of improving coal mining practice, through the larger use of machinery underground, was held in the Auditorium of the Engineering Societies Building on March 11. The meeting was organized by the Materials Handling Division of the A. S. M. E. and held under the auspices of the Metropolitan Section of that Society and the National Coal Association. The New York Section of the A. I. M. E., which had been invited to participate, found itself unable to do so formally because of a conflicting date for its March meeting but informally did its part to aasure the success of the meeting. As a result of the discussion at and preceding the meeting, the National Coal Association, through Walter Barnum, chairman of its research committee, has asked the A. S. M. E. and A. I. M. E. to join the Association in a study of the present problems of the bituminous coal industry. Messrs. Harry L. Gandy, Calvin W. Rice and H. Foster Bain have been selected to act as a committee which shall develop plans for a joint program.

Jan 1, 1926

By D. H. Carlson, J. H. Johnson

"The U.S. Bureau of Mines and Michigan Technological University (MTU) are collaborating to develop an apparatus for measuring diesel tailpipe emissions in underground mines. A tailpipe emissions measurement apparatus (EMA) is described that dilutes diesel exhaust and measures the concentrations of diesel particulate matter (DPM), CO, CO2, NO, and NO2 at known dilution ratios.The EMA was evaluated by side-by-side comparison of its measurements with those by laboratory grade instruments. Concentrations of CO and C02 measured by the EMA were usually within ± 14 pct of concentrations measured by laboratory-grade instruments for CO and ±20 pct for C02• EMA measured DPM concentrations were, on average, 29 pct lower than those measured by laboratory-grade instruments, with the differences being fairly consistent. The CO and C02 differences are related to the method of calculating the EMA's dilution ratio, and the difference in DPM concentrations is attributed to thermophoretic and/or condensation losses related to the EMA's unheated sample probe. Preliminary analysis of data obtained with a heated sampling probe and modifications in the sampling procedures have indicated reduced variability in DPM and in the calculated dilution ratios."

Mar 1, 1992

By Robert H. Ridgway

This circular outlines salient facts regarding the pyrites industry of the United States and the world. It is founded chiefly upon published information available in the literature of the subject. The United States Bureau of Mines has in its files additional and more detailed data upon many of the subjects presented very briefly here, and will endeavor to assist the mineral industries and the public by giving further information in response to individual inquiries. The bureau will welcome comments, criticisms, and contribu- tions of data that may assist in making later editions of this circular of information more accurate, or may aid in developing more fully the files pertaining to pyrites.

Sep 1, 1931

By K. D. Luxbacher, J. T. Davis

"A wind tunnel was designed to examine air flow, heat transfer and layering near an active fire at a working face. This tunnel simulates an active entry in an underground coal mine including an attached cross-cut of similar dimensions. A steel rectangular duct 1 ft. (0.305 m) tall, 3 ft. (0.914 m) wide and 10 ft. (3.05 m) long composes the main body of the tunnel and represents a mine entry. Air flow is generated by an exhausting centrifugal fan attached to one end of the crosscut. This fan was sized to supply air velocities based on Froude scaling. A 6 in. (15.25 cm) propane burner is used to simulate fires of various heat release rates at the working face. Thermocouples are used to map heat layering in the tunnel. Ports are installed for the introduction of tracer gases into and from sampling the system. Barometric, differential pressure, and temperature sensors are also included to monitor environmental conditions. Details about the design and testing of the system are presented including an overview of how the tunnel was scaled to accurately represent fire and flow phenomena. Finally, the proposed use of the tunnel for better understanding of mine fire phenomena and prevention is given. INTRODUCTION Fires in underground mines have been a concern since the dawn of mining. While technological advancements, regulations and best practices have improved both fire detection and firefighting techniques, mine fires continue to represent high risk events. From 2006 through 2015, fires accounted for 1.06% of fatalities in underground coal mines and 0.85 percent of fatalities in all underground mines in the United States (U.S. Department of Labor, 2006 to 2015). In addition to the risk of loss of life, mine fires can cause millions of dollars in equipment damages and lost production revenue. Extensive research has been conducted on how fires occur and spread in underground mines. In addition to testing conducted by government agencies such as the Mine Safety and Health Administration (MSHA) and the National Institute for Safety and Health (NIOSH) (e.g.(Liming, 2006), researchers like Verakis and Dalzell (Verakis, 1988) and Lowndes, et. al. (Lowndes, 2004) have furthered this field by studying ignitions and propagation of conveyor belt fires. While the studies of belt fires in mines are extensive, studies focused on fires at the working face are few in number. The particularly confined space and limited access to a working face, coupled with less robust, temporary ventilation controls create a unique environment that warrants special attention. Separate from studies on mine fires, the use of tracer gases to characterize flow patterns in normal mining ventilation is well established. In 1982, Timko and Thimons (Timko, 1982) outlined current and future applications of sulfur hexafluoride (SF6). However, little experimentation has been conducted to study specifically how tracer gases might be used to evaluate active mine fires and the fires’ effect on the surrounding mine environment (e.g.(Lindsay, 2014). In order to better understand the dynamics of smoke layering from a fire in an enclosed space, a small-scale apparatus was designed to map smoke layering and to examine other aspects of fire behavior at a working face. In addition to studying smoke flow around an active fire, experiments will be conducted using tracer gases in order to determine how they might be used to evaluate an underground fire."

Jan 1, 2017

By D. A. Reynolds, J. D. Davis

"This work was begun in l928, with the cooperation of the American, Gas Association, and the Association contributed financial aid for that year and for the 4 years following. In 1933 financial aid was discontinued, but the Advisory Committee, under the able, Chairmanship of J. S. Haug, has continued to function through the years to the present date. Mr. Haug's annual reports have been published in the Proceedings of the American Gas Association. The purpose of this paper is to bring the index of coals tested by the Bureau of Mines-American Gas Association (EM-AGA) method up to date, to discuss development of auxiliary tests, and to outiline the uses to which the methods have been put in promoting the war effort.COALS TESTEDThe test methods developed with the advice of the Advisory Committee had been applied to 66 coals up to 1942, and an index giving the serial number, origin, and analyses of these coals was published as Bureau of Mines Technical Paper 637. Since this paper was published, 20 additional coals have been tested; the source and analyses of these coals are given in table 1. The table also refers to publications that have been issued. Complete series of tests at high, medium, and low temperatures,have been made on most of these coals, and blending tests with 20 and 30 30 percent of low-volatile coals have also been made at 900°C.; however a few low- and medium-volatile coals (60, 70, 74, 79, and 80) were bested,at high temperatures only. Those coals were mined in eastern Oklahoma and western Arkansas. The test work included low- and high-temperature assay tests, petrorraphic analyses, and plasticity tests since its inception; and for the last 20 coals of the series, expansion and oxidation tests have been made where applicable."

Jun 1, 1944

Senior staff representatives of the Bureau of Mines and the National Institute for Occupational Safety and Health (NIOSH) met in Washington on September 6, 1972, to review and evaluate their cooperative accomplishments to date and to consider the planning and conduct of future coordinated activities. The six presentations given at this joint staff seminar are published here for the benefit of those concerned with the problems of coal mine health, and especially those with responsibilities in administering the Coal Mine Health and Safety Act of 1969.

Jan 1, 1972