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Jan 1, 1996

By J. Koster

[In lQ jG thc E'lcct,ro:~(: L7.l :~u..-ic:ll S;%cti ?n of t?c :I. tcIl~tr,-;lcal 3:vi cioa, ?U~CE~U of lv!irtos, bc,~m an 9.ct iv.t In-:?*t ik7;5i GI of r.:ct.l-;c?;is for rccovcrin,; niclrel, cop?ir, an2 ?? cciou:; ~ot-1 c 1;-on or; :; of tile 3unl~crvi~.l~~ tiistrict in C1ni.k Coult:r, !Icl.r. ]

Jan 1, 1939

By Z. Sun, H. A. Davies

"Current understanding of the mechanisms by which glassy and crystalline thin ribbons are formed in high speed continuous casting processes is considered. A computer model of the combined heat and momentum transfer during melt spinning has been developed. The influence of roll velocity and of heat transfer coefficient (between the melt and the roll) on the temperature and velocity distributions within the melt puddle is analysed and the thickness of the extracted ribbon computed. The relative importance of heat and momentum transfer under different conditions is assessed and differences between the casting of crystalline and amorphous strip highlighted.IntroductionHigh speed continuous casting of thin metallic ribbon and strip is currently of considerable interest both to metal processers and to those studying process mechanisms. The practical interest arises both from the potential economic benefits to be gained from a shorter and more energy-efficient production route and from the ability to obtain extended and uniform thin strip having a metastable microcrystalline or amorphous structure with enhanced or unique properties. The latter arise from the rapid solidification associated with the cooling of very thin sections of melt brought into intimate thermal contact with one or two rapidly moving heat sinks.The principal processes for casting thin strip include free jet, chill-block melt-spinning (GBMS) (1), melt drag (MD) (2), planar flow casting (PFG) (3) and twin-roll casting (TRG) (4). For the first three of these, all essentially variants of melt-spinning, melt flows through a nozzle onto the circumferential surface of a rapidly rotating roll, whereas for TRG the melt passes into the nip between two contra-rotating rolls. We shall be concerned in this paper with the single-roll melt spinning processes only. For these, a puddle is established where the melt contacts the roll surface and the length of this puddle l is a function of the process conditions, notably the circumferential velocity of the roll Us and the volumetric flow rate of the melt Q. The contact time between any point on the roll surface and this puddle, or residence time eR(= l /Us) determines the thickness of ribbon t extracted from the puddle. This thickness, in turn, partly governs the cooling rate T and the amount of undercooling in the melt and thus the microstructure of the solidified ribbon."

Jan 1, 1986

By Briggs H.

The illustrated device uses the principle that the lamp can burn with a smaller inlet passage if the air is rich in O2 and that the size of the inlet can be made a measure of O2 percentage. The appliance consists of an adjustable cut-off applied to the inlet of a safety lamp of the improved Gray pattern. Precision is assessed from tables of calibration tests in air contaminated with blackdamp of CO2:N2 composiiton 1:5.67 at temperatures of 40-70 degrees F. Results are presented of tests at St. Germain's colliery, of tests in air contaminated with pure CO2 and of air contaminated with both blackdamp and inflammable gas; published ranges in mine-air blackdamp compositions are tabulated as ranging from 90.06% N2 to 43.90% CO2. When firedamp is present at 1.25-2.5%, its content must first be estimated by means of the cap and a fifth of its value then deducted from the lamp reading for O2

Dec 1, 1916

By J. Koster

[In 1178 thn S-00n of thr !~Viluralcal Divicion, pur--'11 cf Mines, bcran an o. 't iv in': n-t!Y_Vnn of vothod; for recoverin'-1, Achol, copp~r, nK precioun notnin Zycn o;. -z of tic Bunkcrvillo KOH& in Clark County, Tcv. Tho Bunkcrvillo ran arc of t,-j)(,e of -iincrilization similar to that of 02 SWbury, Ontario, CannO, nichvl dc-?o?-:.t,. At prcoont, only n anall tonnes? p of ore has loan cxDr)scd in t*ic' :hui:er7ilIp rc: inn, ann. there is decided nce! for orjn: izod OrospectiAg ina drvclo-nnnt "crk there. It wann believod, howevar, t4it the dc,cuits varo 3ilficUntly siSnIficant to warrant an investigation iito their]

Jan 1, 1939

By J. H. East, D. Harrington

"INTRODUCTION Considerable interest has been shown in the prospective use of Diesel-powered haulage equipment in both coal and non-coal mines. Foreign technical magazines have devoted considerable space to discussions of the use of Diesel locomotives in European mines and some mention of it has been made in technical papers in the United States. The Bureau of Mines has extensively tested the gases produced in the exhaust of the Diesel engine under various atmospheres and conditions of use; it has established a schedule of tests for permissibility of Diesel engines for use in underground coal mines, including, gassy or dusty mines.This publication provides information as to the successful use of Diesel-powered equipment underground workings in the United States and Europe, briefly discusses the characteristics of some of the toxic gases found in the exhaust of Diesel engines, and points out that Diesel-powered equipment can be used with reasonable safety in underground minus if necessary and entirely feasible precautions are taken."

Apr 1, 1947

By Bruce Pinkston

This report presents a description of the Prototype Demonstration Vehicle and Safety Guidelines developed under U.S. Bureau of Mines Contract No. JO 366003, ?Improving Man Transit Safety. This vehicle was constructed to assess the feasibility of a set of equipment related guidelines which were drafted in Phase I of the same contract. State-of-the-Art improvements are embodied in such areas as collision survivability, occupant comfort, and multiple mode (on and off rail) operation. The electric battery powered vehicle carries a twelve man section crew at speeds up to 12 mph. The description of the demonstration vehicle Is presented In Volume I. Safety Guidelines are presented in Volume II.

Jan 1, 1981

By Albaharna O. T., Argyropoulos S. A.

"This paper describes the development and the implementation of process control in a variety of instruments used in metallurgical laboratories. These instruments are used for different research projects in extractive metallurgy. Hardware and software aspects for this implementation are described and analyzed. Extractive metallurgy applications where process control was .used are presented. IntroductionMicroprocessors are invading almost every area of our lives and are turning up in unexpected applications. A great deal of new equipment which is coming into the market have built- in microprocessor systems. Nevertheless, the area of upgrading existing processes has been slow to develop. There are a variety of reasons for this, and many of these are economic. One of the principal reasons, however, is the general reluctance on the part of many organizations to commit a strong effort to put this new technology into their existing processes.Microprocessor systems developed ""in lab"" are capable of not only measuring thermophysical events which are taking place in metallurgical furnaces, but simultaneously controlling these furnaces. In this paper software and hardware aspects in the implementation of microprocessor control for resistance and for induction furnaces are presented. In addition to this, metallurgical results are given from experiments where this furnace control was applied."

Jan 1, 1989

By Robert J. Timko

This U.S. Bureau of Mines study examined spontaneous heating episodes in coal mine pillars in an active underground coal mine. The information obtained from these incidents was then analyzed to learn which sampling methods provided the earliest indication of pillar heating. The objective of this study was to discover if the location of future events of pillar spontaneous heating could be inferred from the available information. The spontaneous heating-prone area in this evaluation involved pillars located just inby the mine portals. Several detection methods were used to determine gas levels outside as well as inside the affected pillars. It was hoped that, by incorporating external and internal sampling methods into an organized pro-gram, locations undergoing spontaneous heating could be determined more readily. This study found that by drilling small-diameter boreholes into the pillars, then obtaining gas samples from the affected pillars, the ability to locate early spontaneous heating episodes was improved. However, the ability to accurately predict future spontaneous heating events remains in question.

Jan 1, 2010

By John F. Wiss

A series of controlled experiments was conducted at four surface coal mines to study the effects of certain blast parameters upon the ground and air vibration. Preliminary scale-model blasts were conducted at a quarry to provide basic data. It was found that the amplitudes of the ground and air vibration were controlled by the maximum explosive weight per delay. Either cube root or square root scaling could be used for the seismic amplitudes, and cube root scaling could be used for the overpressure amplitudes. Both amplitudes were not significantly affected by the total charge weight per blast, the attitude of the boreholes, or the charge length or diameter. The overpressure amplitudes were affected by the charge depth, the use of cover over surface detonating cord, and the use of adequate stemming. The length of the delay intervals and the spacing of holes were important in determining' the potential fur reinforcement of the amplitudes in certain directions from the blasts. In downwind directions from the blast, the attenuation of the overpressure with distance decreases. Surface terrain did not significantly affect the overpressure amplitudes within the range investigated. The type of overburden affects the generation of both amplitudes and the propagation of the seismic amplitudes. Spectral analysis of the ground and air vibration is reported. A bibliography of pertinent literature is included as an appendix. A scaled distance of 300 ft/lb1/3 should produce a peak particle velocity of less than 1 ips and an overpressure of less than 128 dB linear peak. For square root scaling, a scaled distance of 75 ft/lbl/2 should limit the ground vibration to less than 1 ips.

Jan 1, 1978

By Terry J. Close

At the request of the Idaho Congressional Delegation, the U.S. Bureau of Mines Western Field Operations Center investigated the mineral resources of the 140,000-acre Red Mountain roadless area, located northeast of Lowman, in central Idaho. The area includes U.S. Forest Service Red Mountain RARE II area (4-063). The highly mineralized road less area is underlain mainly by granitic rocks which are transected by a northeast-trending fault system. Associated with the granitic rocks and fault system are gold and black sand mineral resources. At least 1,395 ounces of gold and 858 ounces of silver have been recovered from six lode and placer mines within the roadless area. A total of 525 tons of columbium-tantalum, 2,049 tons of euxenite, 83.5 tons of columbite, and 54,862 tons of ilmenite concentrates have been produced from a nearby black sand mineral placer. Mine workings and facilities in the roadless area consist of two dismantled mills, 15 open and caved underground excavations totaling about 2,900 ft of workings, seven large pits and quarries, over 166 smaller dozer-and hand-dug prospect pits and trenches, and in excess of 66 drill holes. The mineralized sites in the roadless area are covered by about 690 current (1992) mining claims. About 130 individuals are holding the claims. Also within the roadless area are four patented lode mining claims. Twenty-five of the 54 mineralized sites identified during the study of the roadless area have, or likely have, mineral resources. One has gold and three have black sand mineral resources that are marginal or subeconomic. There also are two hot springs with thermal water resources, some veins that could be sources of decorative quartz, and dimension stone which was quarried in the past and could be again.

Jan 1, 1993

By B. P. Watson

The first crush pillars on the Bushveld platinum mines were introduced at Union Section in 1978. Before the introduction of crush pillars, serious problems were experienced when stoping advanced to a point 30 m to 40 m on both sides of the centre gully. At least three to four stopes were collapsing per month. The introduction of the pillars stopped the stope collapses in the mining area where they were introduced. The residual stresses of these pillars were never measured; however, the successful elimination of the ?back-break? problem suggests that the original pillars had a residual strength of at least 8 MPa. Apart from back analyses, very little work has been done to determine the residual strength of crush pillars and only very recently have any measurements been made. The lack of knowledge in this field has resulted in pillars being designed based on experience. Concerns about stope collapses, similar to the Coalbrook disaster, have led to larger pillars being cut in more recent times. If such pillars were cut in brittle quartzites they would always fail violently but the ductile nature of the Merensky Reef generally allows large pillars to fail without bursting. Occasionally, however, one would burst in a working area. Increased incidence of bursting has been reported on some mines at deeper levels but most of these bursts occur in the back areas. Nevertheless, the incidence of bursting increases the risk of falls of ground in already dangerous areas, and the larger pillars decrease the extraction ratio. This paper describes the evaluation of stress measurements conducted in two boreholes over a crush pillar with dimensions 2.5 m x4.0 m, and a height of 1.2 m. Boussinesq equations for vertical and shear stress were used to analyse the original measurements and provide a stress profile across the pillar as well as the residual strength of the pillar. The results showed an unexpectedly high peak stress of 280 MPa at the centre of the pillar and a residual strength of 48 MPa. The reason for the high residual strength is suspected to be the result of the stiff environment under which the pillar failed and the small height of the siding on the up-dip edge of the pillar. More measurements should be conducted on several mines to establish a range of residual strengths for narrow crush pillars.

Jan 1, 2008

Ground and air vibrations induced by large surface blasts have been monitored. These field results, as well as a large number of published results, have been used to assess the performance of existing predictors and for the development of improved prediction methods. Field monitoring has been performed, with four seismographs giving complete wave records, at limestone quarries, coal strip mines and an open pit copper mine. Conventional analysis includes least square fitting of peak particle velocities and peak air overpressures with scaled distance formulations. Frequency content has been analyzed, and correlated with blast design (detonation sequence). Two new methods have been developed for predicting ground vibrations induced by blasting. The proposed analytical predictor accounts explicitly for inelastic attenuation and geometrical spreading, and calculates the peak particle velocity as a function of charge weight and distance. Statistical analysis of case studies confirms the consistent improvement over conventional scaled distance predictors. The second new predictor is a computer program simulating blasts, including blast geometry, charge distribution and detonation sequence, and simulating propagation of individual pulses to any point of interest, where effects are summed. A complete blast vibration results, allowing prediction of frequency content and duration as well as peak velocities.

Jan 1, 1983

By F. Maciosek, D. Denton, J. Johnson

Researchers from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health and personnel from Coeur Silver Valley, Wallace, ID, conducted tests using rock strain strips and Split-Set rock bolts instrumented with strain gauges to monitor wall rock strain at the Galena Mine, Osburn, ID. The objective of the test was to identify whether strain on the rock bolts increased prior to a rock burst. Although results were inconclusive, researchers learned that the Split-Set rock bolts yielded in stick-slip fashion in the highly jointed walls of the stope. The bolts were also bent as stress was redistributed following blasting and subsequent movement along joints in the wall rocks.

Jan 1, 2004

By Paul G. Swanson

This manual of practice is to be used in combination with the final reports for the study of spoil stability in the Eastern Coal Province. The manual applies the predictive matrices developed in the parent study for use in evaluating the stability of typical mine spoil slopes. The values of internal friction and pore pressure coefficient are derived for many varied slope conditions. The results can be used in conventional stability analysis equations to assist the mine operator or regulatory personnel in evaluating spoil stability from very limited information.

Jan 1, 1983

By L. B. McConville

The general term "tar sand" has been used to describe sand containing varying amounts of dense, viscous petroleum. Deposits of tar sands have been found throughout the world, often in the same geographical area as conventional petroleum. The largest one by far is known as the Athabasca Tar Sands, and is located in the province of Alberta, Canada. Actually a group of three deposits, these particular sands underlie an aggregate area of more than 12,000 square miles. Current estimates place the contained raw petroleum at about 700 billion barrels, from which as much as 300 billion barrels of synthetic oil may be recoverable under presently developed technology. For comparison, this latter quantity is roughly equivalent to five times the combined total of U.S. and Canadian crude oil reserves. With the ever-widening gap between energy supply and demand, attention is being directed to all possible energy sources - both developed and underdeveloped - and certainly the Athabasca Tar Sand deposit is one of the more important ones to merit such attention. This paper will review some of the more significant developments and attempt to place in perspective the role that this source of energy could possibly be expected to play in the foreseeable future.

Jan 1, 1974

By James R. Wait

The present final report constitutes the total productivity of a series of contracts from the U.S. Bureau of Mines and the Institute for Telecommunication Sciences over the period 1971-1979. The emphasis on the research has been analytical. In this "executive summary" we give a succinct description of each phase of the investigation. In the first phase of the investigation that was stimulated by the National Academy of Engineering, we concentrated on the analytical studies of techniques relevant to mine rescue. Several specific procedures for locating a buried source were analyzed. In the next, but overlapping phase of the investigation, we dealt with the fundemental character of how electromagnetic waves propagate in mine tunnels. At the outset we allowed for the finite conductivity of the tunnel walls and the presence of axial conductors such as cables, pipes, and tracks. The third phase of the investigation was devoted to the analyses of various specific geophysical engineering problems. The related fourth phase dealt with the general subject of non-destructive testing of wire ropes such as used for mine hoists.

Jan 1, 1980

By Mehmet Guney

At the Armatcuk mine in Turkey, various modifications of sublevel methods have been tried during the last decade in an effort to eliminate gob fires, dangers from roof falls, and surface subsidence, and also to increase extraction efficiency. From the experience thus gained, it was decided that the most likely system to give maximum benefits, considering the existing geological conditions and coa1-seam characteristics, was hydraulic stowing. This paper examines trends in the working techniques of hydraulic stowing and discusses the favorable results and technical problems that the method produced at Armutcuk. The Armutcuk mine, a subsidiary of Eregli Coal Mines (EKI), produces 1300 tons of run-of-mine coal daily from thick (about 10-90 ft) and highly dipping (about 50-90°) coal seams. The coal is highly volatile with good coking properties that make it highly suitable for industrial use. Most of this coal is used in the iron and steel industry at Eregli on the Black Sea coast. Complete recovery of the coal is of vital importance to industrial development and progress. Initial coal extraction was carried out by means of a sublevel mining system modified to accommodate local geological conditions and coal seam characteristics. This method is similar to that employed in metalliferous mines. Several problems arose from the application of the method, one of them being the prevalence of gob fires which caused periodic shutdowns in some sections. To achieve maximum coal extraction with minimum dilution, to eliminate gob fires and surface subsidence, and to reduce fatal accident rates, a decision was taken to change from this method to a hydraulic stowing system. The pres- ence of large deposits of conglomerate and sandstone on the surface contributed to the decision to employ this new method. Although hydraulic stowing practices have been carried out in America and Germany, Upper Silesia may, so far as coal is concerned, be considered the birthplace of the method. Here the process was adapted to thick coal seams on a large scale to reduce dangers from gob fires and damage from surface subsidence. Today, the mining system is not only widely used in the coal mines of France, the Saar, India and Poland, but has also been successfully applied to the iron ore and potassium salt mines in Russia and Germany. LOCATION AND HISTORY The Kandilli-Armutcuk coal field, the most western outcrop of the North Anatolian coal basin, extends for five miles along the Black Sea coast (Fig. 1). The Armutcuk Mine is situated on the southern boundary of the coal field about 40 miles from Zonguldak and about 12 miles from Eregli. The history of coal mining in the North Anatolian coal basin goes back more than a century. Mining commenced on a small scale in the Kandilli-Armutcuk coal field in the late 1880's, and from this time until nationalization in 1940 the mines were operated by private Turkish and foreign interests. In 1940, Eregli Coal Mines was established to takeover the management of these enterprises. The Armutcuk Mine was developed for the first time in the mid-1940's. Since then it has been in continuous production and it now produces an annual 440,000-ton run-of-mine output from which 320.000 tons of salable coal is obtained. MINE GEOLOGY The carboniferous inlier of the Kandilli-Armutcuk coal field crops out over an area about three miles long and one mile wide. The major part of the inlier consists of the Namurian formation with only a relatively small area of Westfalian-A visible on the surface (Fig. 2). The Namurian formation, which has no exploitable coal seams in the Armutcuk Mine, consists mostly of arkose sandstones and black shales often having

Jan 1, 1969

By Mark S. Sanders

This report discusses the development and testing of prototype gloves for underground mining work. An analysis of HSAC hand-finger injuries revealed three high-risk jobs: laborer, mechanic, and roof bolter. Laboratory tests of dexterity and protection were performed using six off-the-shelf gloves. Two prototype gloves were developed. Both were Kevlar-cotton blend knit gloves. One had polyvinyl "Ks" screened on the palm and fingers, and a hand pad sewn into the palm. The other prototype had the palm and fingers coated with a sol id layer of polyvinyl and had no hand pad. Field tests revealed that the solid-coated gloves were preferred by workers, but that the polyvinyl melted when working with hot drill steels.

Jan 1, 1985

By Lloyd Williams

1. The investigation shows that the Coal Creek has been the most productive, bed in Campbell County and contains the largest recoverable reserves of coal. The Pewee, Red Ash, and Jullico have been relatively productive beds and contain appreciable recoverable reserves of coal. The Blue Gem also has been productive in the past, but available information indicates that most of the remaining coal is Less than 28 inches thick. The Big Mary has relatively large reserves over 28 inches thick, but the coal is high in ash and sulfur. Thick partings in the Windrock bed have discouraged mining in that bed. The Poplar Creek and Rex beds generally are below drainage, and large areas have been excluded from the reserve estimate, Reserves in the Walnut Mountain bed will be difficult to mine due to the irregu¬lar thickness and lack of continuity of the bed. Estimated coal reserves are- small in the remaining five beds. 2. Known measured and indicated reserves of coal, based on a minimum bed thickness of 14 inches and on 1,800 short tons per acre-Foot of coal in place, are estimated to be 398 million tons as of January 1, 1953, o? this total, 267 million tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, these should be added to the total estimated reserves.

Jan 1, 1956