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By L. W. Kelly

The purpose of this paper is to describe several methods that have been employed in successfully recovering roof bolts in Indiana, Illinois, and western Kentucky coal mines, the States where successful roof-bolt recovery was started. As far as is known, the first bolts were recovered in a mine in western Kentucky in January or February 1951. In April 1951 a meeting was held at that mine to discuss the recovery of roof bolts. The meeting was attended by A. D. Sisk, former Chief, Kentucky Department of Mines and Minerals; and L. W. Kelly, Federal Bureau of Mines; and officials of the coal company. Inasmuch as roof bolting was in its infancy, the thinking regarding roof bolts at that time was on the problem of getting them in, not getting them out; consequently, the thought of recovering them was revolutionary. The subject was discussed at length from all angles, and it was finally agreed that, if certain safeguards were taken, no agency represented at the meeting would oppose the practice. That this decision was sound has been proved, as thou-sands of bolts have been recovered in the Middle West without a lost-time accident. Recovering roof bolts is a simple operation; consequently, no complicated equipment had to be designed or built for this purpose. However, about 5 years ago, officials of the Traux-Traer Coal Co. conceived the idea and constructed a mechanical device for recovering bolts that has been very successful and has been copied widely in this area. This device will be discussed in detail in part II of this paper.

Jan 1, 1958

By E. D. Gardner, Edmund Stein

"IntroductionMassive sulphides occurring in metal mines are inflammable and furnish the fuel for many mine fires. Actual sampling has shown that dangerous amounts of sulphur dioxide and hydrogen sulphide may occur in mine atmospheres after blasting in massive sulphides. Probably some .of the finer sulphide in the material being blasted burns while it is in contact with the flame from the explosion. It’s also possible that oxygen of the explosive enters into the reaction.That sulphide dusts are explosive under some conditions has long been suspected, but the theory has not been generally accepted as having been proved. Evidence now at hand appears to be conclusive that such explosions do occasionally occur in mine workings in massive sulphides. Information from several mines working in heavy sulphides shows that occasionally, sulphur dioxide in larger amounts than could be expected from the blasting alone are occasionally thrown out into the mine atmosphere during blasting. Accidents have occurred and lives have been lost by men being caught in such gases. Also it appears in a few cases that damage done to timber in stopes by concussions has been greater than could 112.ve been expected from the regular blasts. In most of these cases the unusually large amounts of Sulphur dioxide could only be accounted for by an explosion or by an ignition of sulphide dusts. When this occurs it is probable that the settled dust is stirred up by the first shot of a round, then the dust cloud is ignited by this or a succeeding shot.In one instance, the senior author, while wearing breathing apparatus, returned to a station to take a gas sample immediately after a raise round had been blasted, and encountered a heavy white fume or smoke that was corrosive to the skin and which forced a retreat. The sample, which was taken farther back in a greatly diluted atmosphere, showed a high percentage (0.18) of sulphur dioxide. The station and the raise which was just being started were very dry and the walls and floor of the station contained settled sulphide dust which apparently was ignited by the blast."

Mar 1, 1928

By L. C. IlsLey

Permissible blasting units are approved with the understanding that if actively marketed they will be listed as permissible so that all interested in such safety equipment may know what is available. The last detailed lint of permissible units was published as Technical Paper 4294/. All of the blasting units of that list have become obsolete or have boon modified as covered by extensions of the original approvals.

Jan 1, 1941

By Robert L. Rough

This report presents the results of an investigation by Federal Bureau of Mines engineers of water-injection projects in the northwestern Pennsylvania and southwestern New York area, where oil-producing wells have been converted from pumping to flowing. Data from 24 leases converted to flowing were collected and examined. Only 10 leases had information of significant scope for inclusion in the final analysis. The projects were classified in one of two categories. Group I consisted of leases operated to permit an evaluation of operational changes in terms of existing pressure differentials between injection and producing wells. Group II included remaining properties, for which enough information was available to justify an economic analysis but which did not have sufficient production data to support an engineering study because of radical changes in operational techniques. Variations in production and costs resulting from conversion to flowing were examined for production methods, well-spacing and completion techniques, and reservoir characteristics. Where water-injection rates were constant, oil production usually decreased rapidly at the time of conversion; production then increased slightly for 6 to 8 months before resuming a normal decline rate considerably below the estimated pumping rate. The abrupt decrease in production after conversion is indicative of lower pressure differentials between injection and producing wells, caused by the increased hydrostatic head in the producing wells.

Jan 1, 1960

By Robert H. Merrill

Measurement of the deformation of a borehole in rock subjected to a change in applied stress can be used to calculate the magnitude and direction of the applied stress, provided a satisfactory deformation-applied stress relationship exists , In this investigation by the Bureau of Mines the deformation of a bore- hole in a rock model subjected to a known applied stress was compared with the theoretical deformation of a hole in an elastic, isotropic plate and was found to be in good agreement. Hence, this relationship can be used to calculate the applied stress on a borehole from borehole deformation measurements.

Jan 1, 1961

By T. H. Jeffers

The U.S. Bureau of Mines has developed porous beads containing immobilized biological materials such as sphagnum peat moss for extracting metal contaminants from waste waters. The beads, designated as BIO-FIX beads, have removed toxic metals from over 100 waters in laboratory tests. These waters include acid mine drainage (AMD) water from mining sites, metallurgical and chemical industry waste water, and contaminated ground water. Following the laboratory studies, cooperative field tests were conducted to evaluate the metal adsorption properties of the beads in column and low-maintenance circuits, determine bead stability in varied climatic situations, and demonstrate the beads' potential as a viable waste water treatment technique. Field results indicated that BIO-FIX beads readily adsorbed cadmium, lead, and other toxic metals from dilute waters; effluents frequently met drinking water standards and other discharge criteria. The beads exhibited excellent handling characteristics in both column and low-maintenance circuits, and continued to extract metal ions after repeated loading-elution cycles. Based on laboratory and field data, cost evaluations for using BIO-FIX technology to treat two AMD waters were prepared. Operating costs for BIO-FIX treatment, which ranged from $1.40 to $2.30 per 1,000 gal of water treated, were comparable with chemical precipitation costs.

Jan 1, 2010

By Michael J. Friedel

The permeability and flow capacity in unsaturated media are investigated by the U.S. Bureau of Mines for application to in situ copper leach mining. Moisture retention properties are derived and combined with scanning electron microprobe data to characterize the mineralogy, texture, pore size, distribution, and permeability of the host rock. Finite-element modeling is used to derive a saturated permeability, ambient degree of saturation, and assess various injection-recovery schemes. Recommended design modifications for optimization of solution distribution and maximum recovery from the rock matrix requires either (1) the injection pressures on the order of 1,500 psi and recovery wells operating in a suction mode, or (2) performing permeability enhancement, through in situ rubbling. Injection pressures can be reduced to 500 psi with improved recovery and containment of solutions.

Jan 1, 2010

By Barry Beith

This report details a study which was designed to assess the effect of retroreflective material on detection and form recognition of workers in the mining environment. Further, the study attempted to determine an optimal configuration of retroreflective material with respect to amount and placement on the body to facilitate detection and form recognition. The study involved a one-fifth scale simulation of the perceptual task found in the underground low seam coal mine. Four different configurations of reflective material were presented in various body positions, common to low coal miners, at three different locations in the visual field, i.e., 10, 25, and 45 degrees from focal line-of-sight. All reflective configurations significantly improve detection and form recognition over configuration (cap only) worn by miners. As the amount of reflective material increased, accuracy also tended to increase. Based on the configurations investigated by this study, the Armband configuration (i.e., refectorized armbands, belt, self-rescuer and battery pack) was determined to be optimum. It is recommended that an actual field evaluation be made using the Armband configuration to establish if simulator results are generalizable to the underground mining environment.

Jan 1, 1980

By R. Hogg, T. F. Dumm, L. G. Austin, M. Yekeler

"Dedicated to Professor Kurt Leschonski on the occasion of his 60th birthdayAbstractThe kinetics of batch grinding quartz from a feed of 600 by 425 Jim to a product of 80% less than 10 µm have been determined using screening and laser diffractometer sizing for size analysis. The specific rates of breakage decreased by a factor of about three when the material became less than about 100 µm in size, but the primary breakage distribution function also changed to give proponionately more fine material, so that the grinding efficiency expressed as the development of surface area (B.E:T.) per unit of energy input did not decrease. Analysis of the shape of the particles in the 2S x 38 µm size range showed that particles of this size produced by roll crushing or by 8 minutes of grinding of a 42S x 600 µm feed were not different but at long grinding times the particles were rounded. This suggests that the breakage mechanism changes to give more chipping and abrasion and less disintegrative fracture. As the material approached the ultrafine size range it adhered to the mill case and there was no further size reduction. However, a technique for striking the mill case to dislodge the particles was successful in allowing further grinding to 400Jo by weight less than 2 µm.1 IntroductionIt has long been known that it is difficult to accomplish ultrafme grinding in a tumbling ball mill. It has been reported [12, 13] that there is no further size reduction after some hours of grinding cement clinker in laboratory ball mills. Austin and Bagga (1] and Shah and Austin [16] have given an analysis of the kinetics of dry grinding in a laboratory ball mill, introducing the concept of a slowing-down factor K, which is the ratio of the specific rates of breakage at some long time of grinding to the normal specific rates of breakage. They showed that this factor decreased as fine material accumulated in the mill charge. Cottaar and co-workers [8-10] showed that the movement of solid in a dry laboratory ball mill was influenced by the fineness of the solid and by the presence of air, and that evacuation of air from the mill caused particle sedimentation and low rates of breakage.The concept of the slowing-down factor has also been used in wet grinding [17, 18]. At very .high slurry concentrations it appears to be correlated with a steady decrease of mill power caused by the build up of a layer of deposit sticking to the mill case. This reduces the effective mill diameter and, eventually, the balls start to adhere in the layer and centrifuge. A decrease of mill power always indicates less lifting and tumbling of the media and, hence, less breakage. However, slowing-down of breakage rates was also observed at lower slurry concentrations where there was no change in mill power."

Jan 1, 1990

By Mark R. Pettitt

After a long series of laboratory and in-mine tests, a cost- effective, mineworthy, reduced-noise auger miner cutting head was de signed, fabricated, and field-tested by Wyle Laboratories under contract to the Bureau of Mines. Compared with standard auger cutting heads, the new heads reduced noise by 10 dBA at the jacksetter's position and by 6 dBA at the operator's position. This report contains detailed fabrication instructions, including engineering drawings, that show how a standard auger cutting head can be modified to produce a reduced-noise auger.

Jan 1, 1984

By John Furness Park

This paper, which describes the mining methods and practices at the Jarbidge mines of the Elkoro Mines Co., is one of a series of papers being issued by the United States Bureau of Mines on mining methods and costs in various districts throughout the United States. LOCATION AND HISTORY The Elkoro Mines Co.'s property is located at Jarbidge in the northeast corner of the State of Nevada (fig. 1). The camp is 9 miles south of the Idaho line; the nearest railroad point is 70 miles to the northeast at Rogerson, Idaho. A road leading to the south and connecting with Deeth, Nev., is passable during the summer months; the heavy snowfall which generally takes place early in the winter usually closes the road until the first of July.

Jan 1, 1931

By B. K. Cantrell, K. L. Rubow

"Quantifying exposure to diesel exhaust aerosol in an underground coal mine depends on the ability to measure this component of respirable mine aerosol separately from coal dust. Such measurement is complicated by the carbonaceous nature of both the diesel and coal dust particulate that make up the respirable aerosol. Hence, special sampling and analytical techniques must be used to distinguish between these two aerosol components.As part of a continuing study of diesel exhaust aerosol characteristics, the U.S. Bureau of Mines has applied size selective sampling together with gravimetric analysis to separate and measure respirable diesel exhaust and coal dust aerosol concentrations in diesel-equipped underground coal mines. This technique is based on the premise that the diesel portion of the aerosol is predominantly submicrometer and the mineral dust portion is mostly greater than 1 µm in size. In the study, chemical mass balance (CMB) modeling, based on the distribution of chemical elements in aerosol and aerosol source material samples, is used to referee the analysis of diesel exhaust and mineral dust aerosol concentrations from the size selective sampling results.Based on the results of the study, the Bureau, in cooperation with the University of Minnesota and the U.S. Mine Safety and Health Administration (MSHA), have developed a prototype personal diesel exhaust aerosol sampler for underground coal mines. The sampler has three stages: a preclassifier stage to select for respirable aerosol, an inertial impaction stage with an aerodynamic diameter(d) size cut at 0.8 µm to separate diesel aerosol from mineral dust and collect the mineral dust, and a final filtration stage to collect the diesel fraction of the sample. The sampler has been evaluated in both laboratory and field experiments conducted by the Bureau, MSHA, and the Generic Minerals Technology Center for Respirable Dust (GMTC-RD)."

Mar 1, 1992

By J. W. Paul

This circular is one of a series of papers4 on coal-mining methods and costs which are being prepared through the sponsorship of the U. S. Bureau of Mines for the purpose of presenting information on present mining methods and certain features which govern costs, safety, and conservation. The methods employed are influenced by natural local conditions with respect to the thickness, character, and dip of the coal bed, the nature of the roof and thickness of the overbearing strata, and the means employed for roof support and its control.

Jan 1, 1929

By John J. Sammarco

Illumination plays a critical role in an underground miner?s safety because miners depend most heavily on visual cues to recognize hazards. Mobile mining machinery, located in the miner?s peripheral field-of-view (±10° to about ±60° off-axis), may pose potential pinning and striking hazards. The main objective of this research was to determine if there were peripheral visual performance improvements for the detection of moving objects when using cool-white light-emitting diode (LED) cap lamps as compared to incandescent (INC) light bulbs commonly used in miner cap lamps. The cap lamp variable of interest is the spectral power distribution (SPD); the illuminances were normalized by a diffusion filter. The second objective was to determine if age is a factor for peripheral visual performance. This is important because the workforce is aging ? the average miner age is about 43 years old. Thirty subjects participated in the study; ten subjects each in the age groups of younger (18 to 25 years), middle (40 to 50 years), and older (50+ years). Visual performance was quantified by the subjects? speed and accuracy of response to detect the rotation of high-contrast (white) circular targets located 3.83 meters (m) away at -20°, 40°, and 50° off-axis. The speed of detection and the number of missed target rotations (accuracy) were measured. The prototype LED cap lamp results were best with a 11% to 15% improvement compared to the INC and LED cap lamps respectively. Age does appear to be a significant factor. For the middle and older age groups?, target movement detection time increased 75% and 60% and the number of missed targets increased 500% and 450% respectively in comparison to the youngest age group. The results also suggest that target location is a significant factor. The subjects? target movement detection time for the 40° and 50° target movements increased 16% and 69% respectively as compared to the -20° target.

Jan 1, 2008

By Charles F. Weber

Premature blasts of charges of explosives have caused many deaths in anthracite mines, and the causes of many of the blasts were not determined satisfactorily. Investigators often found fairly high potential differences between such metallic objects as rails, pipes, conveyor lines, or sheet-iron chutes in the working place where an accident had occurred. At one mine where a premature blast occurred in a rock tunnel, one workman was killed and two others were injured, and several days later a potential difference large enough to explode an electric squib was detected between the compressed-air pipe and the track rail; the voltage fluctuated and appeared to change with the movement of a locomotive. At another mine, a. workman was killed when a primed cartridge that he was about to load in a blast hole exploded in his hand. During the investigation, a potential difference was found between the conveyor line and the sheet-iron chute. During a 5-year Period, 61 fatalities and 771 nonfatal injuries were caused by explosives accidents in anthracite mines, and one of the chief causes of these accidents was premature blasts.

Jan 1, 1950

By A. E. Back

A method has been developed in the laboratory for successfully treating titaniferous magnetite ore from the deposit at Iron Mountain, Wyo. The ore is roasted with 15 percent sodium carbonate to convert the vanadium to a water-soluble form and fix the soda for the subsequent electric-smelting step. Approximately 90 percent of the vanadium is recoverable in a product assaying 80 percent V2O5. The leached calcine is briquetted and smelted in a graphite-lined electric-arc furnace. Substantially all of the titanium is recovered in a soda slag, assaying 60 percent TiO2 and 2 percent Fe, which can be upgraded to 75 to 80 percent TiO2 by leaching with dilute sulfuric acid. The upgraded slag could be utilized for the production of titanium dioxide pigments or titanium tetrachloride. About 90 percent of the iron is recovered as pig iron, containing only minor amounts of vanadium, titanium, and sulfur. The high TiO2 slag compares favorably with slag containing about 70 percent TiO2 being produced by the Quebec Iron & Titanium Corp. at Sorel, Quebec. The data obtained from this investigation indicate that a feasible process has been developed for treating Iron Mountain ore, and larger-scale testing is warranted to develop engineering data for the ultimate utilization of this deposit as a source of titanium, iron, and vanadium. There are adequate supplies of basic raw materials, electric power, water, sodium carbonate, coal, and petroleum products within fairly short distances of Cheyenne and Laramie, Wyo., the nearest cities and probable plant- and labor-supply points.

Jan 1, 1952

By D. J. MacDonald

This U.S. Bureau of Mines report reviews published information on synthetic berlinite (AlP04) and suggests experimental conditions requisite for its production. Berlinite is a piezoelectric material with potential use as a substitute for quartz in the crystal oscillators, which are components of electronic and electroacoustic equipment. Information gathered here (mostly from published sources) includes historical background, physical properties, end-use applications, criteria of quality, and physio-chemical factors involved in berlinite crystal growth. It is concluded that growing large high-quality berlinite crystal would require high-purity starting materials in an autoclave equipped with a noncorrodible liner and operated with temperature control of ±O.OO5 ac over a range of 250 to 350 ac.

Jan 1, 1995

By Adam K. Smith

Over-exposure to noise remains a widespread, serious health hazard in the U.S. mining industry despite 25 years of regulation. Most other categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. In order to reduce cases of Noise Induced Hearing Loss (NIHL) in the mining industry, retrofit acoustic treatments and controls are being developed to subdue noise at the source. The Mine Safety and Health Administration (MSHA) coal noise sample data collected from 2000 to 2005 has determined that continuous mining machines rank first among all mining equipment whose operators exceed 100% noise dosage. The continuous mining machine conveyor, used to move coal from the cutting face to the rear of the machine, has been identified as a dominant noise source. A dual sprocket conveyor chain was tested as a potential solution. Sound power level measurements conducted at the Pittsburgh Research Laboratory (PRL) accredited reverberation chamber showed a 3 dB reduction in the A-weighted sound power level when the dual sprocket chain was implemented. Underground results show an 8-hour Time Weighted Average (TWA8 hrs) reduction a 3 dB for continuous mining machine operators. Utilizing this newly developed noise control, along with previously proven controls, provides continuous mining machine operators an opportunity to be within the MSHA-Permissible Exposure Limit (MSHA-PEL).

Jan 1, 2009

By Hylton R. Brown

Although extensive research has been carried on to determine the factors affecting the explosibility of carbonaceous dusts, as much has been published on coal-dust and grain-dust explosions recent reports of loss of life and property in explosions if metal dusts emphasize the lack of information on the extent of the dust-explosion hazard in plants manufacturing or handling; aluminum, magnesium, or zinc powder, as well as other metal or mineral dusts. Early investigators believed that only the carbonaceous dusts formed explosive mixtures with air, and it was not until near the beginning of the present century that the explosibility of certain metal and mineral dusts was recognized generally. In his book, entitled "Fire and Explosion Risks," published in 1904, Von Schwartz called attention to such hazards. Many vague references to metallic-dust explosions are found in the literature, such as "a severe explosion of aluminum dust occurred in the Middle West several years ago," but very little information seems to be available on the extent of the hazard, the number of explosions, or the amount of loss caused by explosions in pants handling metallic or mineral dusts or powders other than those of a carbonaceous nature. A search of the records of insurance companies, rating bureaus, fire underwriters,and fire-protection associations as well as the files and records of Government agencies has been made to obtain authentic data on explosion losses. To indicate the extent of the hazard a summary of laboratory tests covering the explosibility of certain metal dusts, with brief reference to their uses and Methods of manufacture, and the data compiled from the information available on losses are presented in this publication.

Jan 1, 1941

By Bill M. Stewart, Phil W. Patton, Curtis C. Clark

Back injuries from handling materials in underground mines continue to be a major safety problem. In spite of the ingenuity of many people and the development of numerous mechanized aids, the number of materials-handling injuries remains second only to the number of roof fall injuries in underground coalmines. Relocation and repositioning of electrical cable, conveyor belt parts, and roof bolt sup-plies in particular are the sources of significant numbers of back injuries. To help reduce such injuries, researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are examining Mine Safety and Health Administration accident data to determine correlations between materials-handling tasks and the number of back injuries. Also being investigated are new technologies used in underground mines in the United States. Equipment is being developed or modified that would replace the necessity of doing lifting tasks manually. A Coleman manipulator was tested, and modifications were made to make it more suitable for underground mine use. To reduce or eliminate the need to manually clean off materials that commonly plug grizzly openings, a track-guided pincher arm device was developed. Oversized rock can be broken with the pincher arms in the up position, and the arms can be lowered to grab and remove debris. The arm can also be used in a sweeping action to remove cohesive fines that may bridge grizzly openings.