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By Kenneth C. Ko

An engineering investigation was carried out on the technical and economic feasibility of implementing flexible liner/backpacking support systems In an advancing tailgate longwall mine. The system for a model mine consists of a circular tube constructed of liner plates and flyash backpacking. Flyash is pneumatically stowed into the tailgate. Small amounts of cement may be mixed to improve the support capability of the fill In difficult local ground conditions. Water is added inside the nozzle immediately prior to spraying. Results of theoretical analyses and a field test show that the designed system is technically feasible, can be cost-competitive, provides more stable ground conditions, and can Increase productivity and coal recovery, when compared with existing retreat longwall systems. In certain mine layouts, the new system can reduce the direct mining costs by a significant amount. The system would be particularly applicable to deeper coal beds with bad ground conditions.

Jan 1, 1980

By C. D. Messelt

The Bureau of Mines investigated the application of a diffusion model to sintering rate data developed for lithium titanium ferrite. The data were obtained by sintering pressed pellets under identical conditions for various times up to 11 hours. Stereological measurements were made on polished sections, and sintering rates were calculated. A model for intermediate stage sintering was fitted to the stereological data. This procedure produced a method by which these type data could be used to study the relative importance of volume and grain-boundary diffusion under a variety of sintering conditions.

Jan 1, 1979

By Scott W. Hazen

METHODS of determining the grade and tonnage in a mineral deposit have not kept pace with scientific developments in certain other fields. The most commonly used methods of computing ore reserves and grade based on diamond-core-drill sampling are the cross section, the polygon, and the triangle. Tonnage and grade may be determined by these methods with acceptable accuracy, providing a sufficient number of samples is obtained; however, there is no means of determining when an adequate number has been taken or conversely if the deposit has been sampled excessively. It is demonstrated that, by using the techniques of statistical analysis, a mining engineer will be able to determine when a sufficient number of samples has been taken to determine the grade of a mineral deposit within a specified degree of confidence. Using statistical analysis to compute the estimated average grade of the ore makes it possible to compute a fiducial interval, when a distribution of the sample means is normally distributed, so that there is 95-percent confidence in the statement that the true average grade of the deposit is covered by the interval. This report utilizes data obtained from the Maggie Canyon manganese deposit, Artillery Mountains region, Mohave County, Ariz. Four separate exploration projects were conducted at Maggie Canyon between 1936 and 1950. Present economic conditions have made it desirable to determine the amount of 5-percent manganese ore developed by these projects.

Jan 1, 1957

By M. Troyer

A coal shuttle car equipped with a pulsed laser optical ranging system to provide guidance for an automatic steering system was tested in production coal mining. Test results are presented for the two mines where testing took place, and some operator's reactions are included. Automatic steering control keeps the car cantered in an entry, and automatic turns are made at intersections as signaled by the operator. All other controls-tram, conveyor, brake, etc, remain manual and require operator control. Complete override of steering while in the automatic mode is retained by the operator, who may grab the steering wheel at any time and turn in opposition to the automatic signal by applying about 10 foot-pounds of torque.

Jan 1, 1976

By Kenneth Trelewicz

This report describes the total effort that went into developing environmental test criteria for general mine instrumentation. The project was a two-phase effort. Phase I consisted of research and mine visits to develop an environmental profile for mine instrumentation. The profile was translated into general requirements and then into test requirements. A review of existing government and commercial specifications was performed to determine if they matched mine instrumentation test requirements. Finally, a set of environmental test procedures was developed for the testing of mine instrumentation. Phase II consisted of selecting and purchasing sample mine instrumentation and subjecting them to the previously developed tests. The purpose was twofold: (1) to evaluate the criteria developed for use as an instrumentation test document and (2) to determine the effects of the various criteria on a representative sample of both proven and newly developed instrumentation. The test criteria were then modified, based on the results of the testing, and are listed therein.

Jan 1, 1981

By K. Kohli

A case study involving a historic structure undermined by longwall mining is presented in this paper. The location of this study is in South Western-Pennsylvania; USA. The structure is 150-years old and subsided 4.5 feet. This paper discusses the mitigation measures taken to reduce the subsidence damage and its effectiveness.

Jan 1, 2002

By Melvin I. Esrig

Lime Cement column stabilization of soft clay and sand in Salt Lake City, Utah and in San Francisco California is described and discussed. Stabilization permitted the construction, in a single stage, of a 14 m MSE wall on "medium" clay in Salt Lake City. It was used to mitigate the potential for liquefaction in San Francisco and to stabilize the Young Bay Mud beneath the BART extension to San Francisco Airport. These applications are described and the field measurements of performance are reported.

Jan 1, 2000

By G. M. J. van Heerden

Paper written on project work carried out in partial fulfilment of B. Eng (Mining Engineering) degree The Union Section of Anglo Platinum is situated ±18 km west of the town of Northam on the north-western rim of the Bushveld Igneous Complex. Both the Merensky and UG2 reefs are mined. Support of the Merensky stoping areas with rock bolts is specifically problematic due to the stoping width restrictions varying around 90 cm. The installation equipment of in-stope rock bolts and the effectiveness thereof in the Merensky stoping areas was critically evaluated. In order to do this a background research on the need for better on-the-face support had to be conducted. The need for improving the rock bolt drilling and the equipment had to be investigated and the financial implications and justifications for the improved equipment examined. To conduct the search an overall study was done on the rockfalls and safety aspects throughout the platinum industry in South Africa and specifically Union Section. It was found that most of the rock falls in the Merensky stoping areas of which ± 70% are less than 1.2 m in thickness generally occurs within 4 m from the face and causes ± 60% of the in-stope injuries. Serious shortcomings had been identified with respect to the airleg, rock drill machine and the drill steels used in the drilling of the rock bolt holes. Through experimentation, using a testing frame built for this purpose on surface and with the co-operation of mine staff and suppliers, a number of possible modifications were identified and tested. This resulted in the final product with which it was possible to drill a 1.2 m hole in the hangingwall of the stopes ranging with an angle to the hanging from 90° for a 90 cm stoping width and 67° for a 80 cm stoping width. It is confidently concluded that this system will effectively improve the total face support and result in a substantial reduction of rock falls and consequently the occurrence of injuries and fatalities in the Merensky stoping areas. The installation of rock bolts on the face with the modified drilling equipment will increase the direct support, but the system has a potential of a substantial reduction in the profile stick support density and an increase in productivity in the stoping areas due to fewer occurrences of rock falls. It was finally concluded that effective modifications to the drilling equipment for rock bolt in-hole drilling could be made and the installation thereof in the stope face is adequately justified.

Jan 1, 2002

By Gene F. ] [Faufaul

This contract was concerned with the design, development, fabrication and testing of an improved tamper-proof filter cassette assembly for use in the, collection and evaluation of dust particulates, primarily in mining areas. This report presents the design effort, fabrication and tenting of five- prototypre unit$ as well as the design and production of 1000 filter cassettes with sampling heads. This new improved filter cassette has been tested and approved by NIOSH as meeting the requirements specified in the contract.

Jan 1, 1978

By Alan H. Goode

Glass wool meeting requirements for commercial use was made from glassy fractions of urban solid wastes by the Bureau of Mines. This research was a part of the Bureau's program to develop building products and other usable materials from reclaimed urban waste materials. Mixes of molten glass were fiberized into glass wool during laboratory studies by impingement of a jet of compressed air on a stream of the molten glass. The principal test variable studied was composition of the melt; this was varied by adding dolomite and alumina to obtain molten glass with the handling characteristics required for producing final wool products of the desired composition and physical characteristics. When no charge is made for the waste glass and approximately $75 per ton can be obtained for the wool product, an interest rate of return on investment after taxes of about 12 percent can be obtained. If a charge of $5 per ton is required for the waste glass, a selling price of about $78 per ton would be necessary to obtain a l2-percent-interest rate of return on investment after taxes.

Jan 1, 1972

By Clark F. Grain

These investigations were undertaken as part of the Bureau of Mines program for the development and evaluation of high temperature nonmetallic materials. This report consists of thermal expansion and phase inversion measurements by high-temperature X-ray diffractometry on the principal oxides of beryllium (BeO), calcium (CaO), titanium (TiO2 ), zirconium (ZrO2 ), hafnium (HfO2), and thorium (ThO2); all were high-purity commercially available oxides. Thermal expansion values were calculated from unit cell dimensions measured at selected temperatures. Expansion was determined parallel to each major crystallographic axis for the anisotropic oxides: BeO, TOi2, ZrC2, and HfO2. Combined random and systematic errors in the thermal expansion values are considered to be less than 3 percent of the total expansion at 500° C. and approximately 2 percent at 1,000° C. No hysteresis in the expansion curves was noted between heating and cooling cycles. The Bureau's values were compared with published expansion measurements obtained by X-ray diffraction, dilatometric, interferometric, and telemicroscopic techniques. For anisotropic oxides, average linear expansion values were calculated from the volume expansion.

Jan 1, 1962

By A. S. Macfarlane

Mineral resource management (MRM) practice has developed in South Africa over the course of the last ten years, with the purpose of integrating previously isolated technical functions into a value chain aligned, process organization, responsible for mine planning and optimization. The implementation of MRM within various companies has met with varying degrees of success, often resulting in incremental improvements in the planning process and, conversely, often becoming the scapegoat for poor delivery on plans and projects. The reason for this has been, amongst others, a lack of a suitable metric to define the success rate of MRM in the business at hand, in terms of its contribution to the bottom line. This paper is the result of extensive research by the author into this subject, which has resulted in the conclusion that economic value added is an appropriate measure that will lead to real optimization and value creation in mining companies, if applied within a new, holistic model

Jan 1, 2006

By F. S. Kendorski

This report presents the results of a program to improve, using existing and proven technology, unstable highwall conditions through better blasting practices in Appalachian strip coal mines. Better borehole blasting agent distribution and optimization of burden, spacing, and delay periods allowing satisfactory breakage with minimal backbreak were the objectives. At a selected field site, geologic conditions were closely examined with regard to joint orientation and spacing, and resulting slope stability considerations. A test series of eight blasts was completed and the resultant highwall monitored by repetitive photography. The study of drilling and blasting economics along with equipment performance led to an economic model of blast parameters and the identification of blast design cost benefits. The work demonstrated that small strip mining companies' are able to achieve a more stable highwall excavation utilizing presently available technology, equipment, and explosive products at improved operational cost and safety.

Jan 1, 1981

By G. Bartolacci, G. Couture, Levasseur. B., A. Lockhart, D. Nathan

"Pulp and froth zone characterization in a flotation circuit to improve transport of valuable minerals remains a challenge. Even though some significant breakthroughs have been made in the development of collectors in terms of selectivity, the control of gangue drainage is still the main bottleneck to achieve the production of a clean concentrate.Over the last decade, COREM’s team has been working on technologies to improve the selectivity of flotation circuits by tuning their hydrodynamic conditions using online instruments such as the bubble viewer, Jg sensor and gas hold-up. As part of its research program, COREM also developed the half-life column that establishes the relationship between the collection zone (bubble-particle attachment) and the cleaning zone (foam) of a flotation machine. In recent years, COREM has continued the development of the prototypes to make them more robust and improve the accuracy of their measurements.Recently, these hydrodynamic instruments were installed in an industrial process at Raglan Mine in order to diagnose and control the impact of hydrodynamic parameters versus the recovery and the quality of the Ni concentrate produced. Sampling campaigns of hydrodynamic parameters demonstrated that froth height could be optimized in order to increase recovery and quality of the concentrate at the same time. The specific effect of the froth height impacts both the pulp and the froth zones. Along with the impact on the drainage of the concentrate, it was observed that froth height also contributes to enhance the collection of particles in the pulp leading to an increase in metallic units.IntroductionOnce the particles of the minerals of interest are attached to the air bubbles injected in the pulp, the flotation process is driven by air dispersion parameters and froth properties. The pulp is usually responsible for the collision between air bubbles and hydrophobic particles of interest while the froth zone aims to upgrade the selectivity of the particles floated through drainage of the unwanted hydrophilic particles. Over the last four decades, flotation hydrodynamics has been extensively studied. Superficial gas velocity (Jg), gas hold-up (eg), Sauter mean bubble diameter measurements (d32) and bubble surface area flux (Sb) are among the most assessed parameters in flotation plants worldwide either to quantify the gas dispersion parameters or to optimize them (Fournier et al., 2015). McGill University has developed several sensors able to measure these parameters at industrial scale (Tavera et al., 1996; Finch et al., 1999; Chen et al. 2001)."

Jan 1, 2017

This report includes a short history of uranium and its uses, mineralogy of common uranium minerals, and information on the use of electronic prospecting equipment and tests for detecting the presence of uranium. Details are given on geologically favorable areas and formations and practical methods of prospecting. Some information is given on the staking of claims, what lands are open to prospecting, and methods of securing mining rights. A forecast of the economic outlook for uranium is included. Appendixes give sources of additional information and a list of libraries where unclassified Atomic Energy Commission reports may be consulted. Because the increasing use of uranium by industry has revived interest in prospecting and exploration for this element, the Bureau of Mines has issued this report, which brings up to date and expands the subject matter of a hand- book on uranium exploration and production published in 1956.l

Jan 1, 1968

By L. Yuan

To reduce fire hazards from spontaneous combustion of coal in longwall gob areas, a series of computational fluid dynamics (CFD) simulations were conducted by National Institute for Occupational Safety and Health (NIOSH) to model the spontaneous heating of coal in longwall gob areas. The previous modeling results demonstrate that spontaneous heating of coal usually occurred behind the longwall shields and along the face with a bleeder ventilation system. Assuming a stationary longwall face, the spontaneous heating could turn to a spontaneous fire in several days for the most reactive coal under favorable conditions. When the longwall face advances, the spontaneous heating process will be significantly affected. In this study, the effect of longwall face advance on the spontaneous heating in the gob area is investigated using the CFD model developed in previous studies. One longwall panel with a bleeder ventilation system is simulated. The width of the panel is 300 m, while the length of the panel is changed between 1,000 to 2,000 m. The same permeability and porosity profiles are used for gobs with different lengths. The spontaneous heating first develops in the gob when the longwall face is stationary. Then, the face advances at a certain rate. The face advance is simulated as a series of discrete movements, and the effect of the face advance on the maximum temperature developed during the face stoppage is examined. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Jan 1, 2009

By F. S. Crawford

Although it may be impracticable to adopt standard methods of safe working in all branches of mining, and although it may be impossible to establish a standard for each class of work at each mine, some of the iron-mining companies in the Lake Superior district have found that by adopting certain standard ways of performing certain of their operations they insure both more efficient and safer working conditions. Many companies have adopted the idea that the safe way of doing things is also the most efficient and economical way, and, through the medium of their safety conferences they are trying to find the safest way, and the most efficient way, of performing practically every operation about the mines. This activity will, undoubtedly, be continued at every operation which uses this method of doing safety work, because in the advance of industry changes must be made in the results required from time to time. A review of the safety standards and safety suggestions which have been arrived at by some of the companies in this the greatest iron-mining district in the world, will be of value to companies who are interested in improving the safety of their working conditions. So that attention may be directed to the methods in use, rather than to individual companies, all names have been omitted and companies are referred to only by letter.

Aug 1, 1931

Since the comprehensive review of the Persian fields presented by Sir John Cadman last year, operations have proceeded normally. No developments of especial importance fall to be recorded and it remains only to bring up to date the full information given at the beginning of 1933. Controlled production from the Masjid-i-Sulaiman and Haft Kel fields has been maintained at slightly higher rates than during 1932. The figures for the past five years are as follows: These represent crude oil and products piped to the coast but exclude products reinjected into the reservoir, a process that has been in continuous operation at Masjid-i-Sulaiman during the period under review. The systematic delimitation of the Haft Kel field has been continued during the past year and results have been sufficiently encouraging to justify the inception of a wider scheme for distribution of production. Drilling has been resumed recently in the Persian sector of the Naft Khaneh field, and preliminary survey work is in progress for the selection of a site for a refinery at Kermanshah arid the construction of a connecting pipe line. Investigations in connection with the scientific control of reservoir were dealt with in considerable detail in last year's review. This work has been steadily pursued during 1933 and certain of the investigations have been the subject of papers presented to the World Petroleum Congress held in London in July of last year.

Jan 1, 1934

By L. T. Stanley

A method is described whereby the behavior of the front is approximated when gas is injected into a thick reservoir having reasonably homogeneous properties. The method is applied to the Abqaiq field of Saudi Arabia. The producing member is the Arab-D, a high-permeability calcarenite which has no continuous betlding planes. Field performance indicates the injected gas to be partially miscible with the reservoir oil because gas volume factors experienced are lower than those predicted by the gas law. Eqlrilibril~m calculations confirnz ihis and also show that the volume factor may vary appreciably, depending on the relative quantities of oil and gas in contact in the reservoir; consequently, volutnetric balances are made for the purpose of determining the behavior of the gas volume factor during injection history. The effect of gravity segregation on position and shape of the gas front is approximated by dividing the producing section into three zones vertically and tracing the movement of the average interface in each zone, with counterflow of oil and gas taking place betweell zones behind the front. This results in a gas front that advances more rapidly along the top of [he formation than along the base, producing an "umbrella" effect in cross section that becomes more pronounced as the front progresses. The calculations cover the gas-injection period of Abqaiq field history through 1958, and the position of the gas front is plotted at one-year intervals. Finally, some comparisotls between the calcrlated fronial position and the gas-oil contact as Measured by neutron logs are made. INTRODUCTION Fig. 1 is a structure contour map of the Abqaiq field. For analytical purpcses, the field has been divided into two areas designated A and B, as shown on the map. Gas injection into Area A was begun in early 1954 into two wells located near the crest of the structure on the north-south axis of the anticline. During the period covered by this paper, the average injection rate has been 122 MMscf/D with a maximum sustained rate of 160 MMscf/D. The reservoir pressure has been maintained at 2,450 psig since start of gas injection. The reservoir originally was undersaturated but, prior to pressure maintenance, the pressure was drawn below the bubble point in most of the Area A section, creating an in-place free-gas saturation of 8 per cent at the crest of the structure. The average critical gas saturation is 13 per cent established by laboratcry core tests. That the entire reservoir remained below critical gas saturation prior to gas injection is borne out by the fact that none of the crestal wells have exhibited high gas-oil ratios during production history. The Area A reservoir is a carbonate section about 200-ft thick having average porosity and permeability of the order of 22 per cent and 500 md, respectively. The productive horizon is the Arab-D member of Jurassic age and is encountered at an average depth of

By M. van Schoor

The bulk of the world?s platinum production originates from the Merensky and UG2 reefs within the Bushveld Complex, South Africa. Both the Merensky and UG2 reefs are disrupted by faults, dykes, potholes and iron-rich ultramafic pegmatite bodies (IRUPs)?features that impact negatively on production, planning and safety. It is therefore advantageous to know of their presence and geometry ahead of mining. To date, no geophysical technique has been successfully applied to the routine mapping of mine-scale potholes and IRUPs. These disruptive features may vary from a few metres to several tens of metres in diameter. In this paper the applicability of in-mine electrical resistance tomography (ERT) to map potholes and other disruptions to the continuity of the Merensky and UG2 reefs ahead of mining is demonstrated using two case studies.

Jan 1, 2005