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By J. R. Thoenen

In the summer of 1937 the authors began a series of time studies of the various processes employed in' the production of crashed stone. These studies, made at quarries situated in the eastern and southeastern parts of the United States, have not been completed, but to make results available to the industry as early as possible, it was decided to publish summarizes of the studies made to January 1, 1939, as a series of progress reports. The first of these dealt with power-shovel loading and was issued as Report of Investigations 3461 in September 1939. The second, issued in September 1939 as Report of Investigations 3467, dealt with quarry haulage. The present report discusses analyses of time studies of primary drilling a t the same group of quarries. OBJECT OF STUDY Pressure of business problems frequently requires the entire attention of quarry management, and in consequence internal plant economies often are neglected. Also, operating officials absorbed in their local problems are prone to overlook possible economies that would attract attention immediately were they critically examining another plant. The authors felt that technical studies at a number of plants, made by impartial engineers, might disclose opportunities to reduce costs or improve efficiency in internal plant processes.

Jan 1, 1940

By D. J. Dollhopf

An overburden handling dragline operation was conducted at a strip mine near Colstrip, Montana. The objective of the demonstration was to determine the degree a dragline could mix overburden inhibitory zones during the spoiling process. In order to quantify the mixing process the overburden was: 1) scatter spoiled; 2) dump spoiled; and 3) spoiled in a normal manner. This demonstration was part of an effort to investigate means of reestablishing non-polluted hydrological systems in areas where surface mining directly impacts shallow ground-water resources. When inhibitory material constituted < 5% of the total overburden volume, such material was essentially not detectable in the resultant spoil pile. When inhibitory material exceeded 15% of the overburden volume it was always found in the resultant spoil pile, generally with a smaller extent, indicating partial dilution. Inhibitory overburden zones often reappeared at the base or top of spoil piles in the potential aquifer and root zones suggesting the need for selective placement procedures. Scatter spoiling did not appear to be significantly more effective than normal spoiling, however clump spoiling seemed to produce less mixing of inimical zones. Mining activity has reduced ground-water levels within 1600 m of the active pit. The aquifer which is developing in spoils appears to have similar confinement characteristics as those that existed in the premined aquifer. To date no definite trends have been observed concerning changes in surface or ground-water chemistry associated with mining.

Jan 1, 1978

By M. A. Trevits, A. Ozmet, A. C. Smith, J. B. Walsh, T. P. Mucho

Improvements in remote fire fighting technology are needed to reduce miner exposure to the dangers of fires and possibly save the lives of those who may become trapped. The National Institute for Occupational Safety and Health, in cooperation with U.S. Foam Technologies, Inc1., conducted a series of experiments at the NIOSH Lake Lynn Experimental Mine to study the stability, transport, control and fire extinguishing effectiveness of nitrogen-enhanced foam technology. This paper presents a description of the mine test configurations and experimental results

By Pamplinm J. W.

"INTRODUCTION For the past six years the United States Bureau of Mines in cooperation with the University of Alabama, Tuscaloosa, Ala., the Missouri School of Mines and Metallurgy, Rolla, Mo., and certain operating companies of the Florida land-pebble phosphate district have conducted an investigation to determine the amenability of phosphatic sands to concentration. 4 This paper discusses briefly an investigation of the concentration of fine phosphatic sanads of the land-pebble district of Florida. The process used - namely, the tabling of material previously given a selective oiling treatment - is new in its application to the phosphate industry, although old in principle.The feed to the standard phospidate washery is a hydraulically wined mixture of phosphate pebbles, quartz sand, and clay in which the quartz sand grains are segregated in the fine sizes. Me standard method of concentrating (washing) consists of wet-screening. at about 20 mesh to recover the plus 20-mesh material. 5 Lately some of the washeries have introduced hydraulic classifiers for sizing of the screen undersize to recover the coarser spigot products, but even this additional treatment allows much of the fine phosphate to be wasted."

Dec 1, 1932

By M. Beus, S. Inverson, B. Stewart

Abstract Recent ore pass failures have underlined the need for improved designs, standards, structural mon¬itoring methods and better hang-up prevention and removal tech¬niques. Researchers at the Spokane Research Laboratory of the Na¬tional Institute for Occupational Safety and Health (NIOSH) are investigating methods to improve safety during the transport of ore in ore passes. Design criteria and hang-up prevention and remedia¬tion strategies involve studies of the effects of static and dynamic ore and waste-rock loads on chutes, walls, gates and support structures. Particle flow analysis methods were used to simulate the response of various ore pass designs to a wide range of ore loading condi¬tions. A full-scale mockup of ac¬tual ore pass and chute assemblies was duplicated and tested for load response. Data from a particle flow code and the mock-ups were com¬pared Loads on an active ore pass chute were measured.

By William E. Young

There are many large rhodonite-bearing veins containing manganese in the Eureka-Animas Forks area of the San Juan Mountains in Colorado. The Sunnyside vein is the largest known vein in the area. As observed on the surface, the vein is mineralized over 8,000 feet and attains a maximum width of 200 feet. The average width of the vein and its branches and ramifications is 58 feet in the area that was mapped in detail. The weighted-average analysis of surface and underground samples from the northeastern extension of the Sunnyside vein is 8 percent manganese. Most other known veins in the area have a similar manganese content. The Hidden Treasure vein lies southeast of the Sunnyside-No Name-Mastadon vein. The weighted average of the analyses of surface and underground samples from this vein is 13 percent manganese. Exposures of the Scotia-Silver Chord vein are visible over a strike length of 4,000 feet on Treasure Mountain. Diamond-drill holes show that the vein contains 10 percent or more manganese to a depth of 400 feet. The vein has an average width of 28 feet. The Independence vein is exposed on the surface for a distance of 600 feet and has an average width of 6 feet. Three cut samples taken across the vein had an average content of 20.7 percent manganese. Sampling of the outcrops of eight veins in the Placer Gulch area also indicates manganese. Numerous other veins cropping out in the surrounding area are similar to the outcrop of the Sunnyside vein system mineralogically and are worth investigating.

Jan 1, 1966

By Peter W. Kauffman

This Bureau of Mines publication is designed primarily to provide mine engineers and production-level mine managers with the following: 1. Information to assist them in making the decision to retreat mine and in selecting the best retreat mining technique for specific mining conditions. 2. Information on mine planning that will enable them to design mine layouts for safe and efficient retreat mining. 3. Information that will enable them to develop a section foreman&apos;s handbook. The manual has been organized to gradually increase in level of detail as the reader progresses from beginning to end. Individuals interested in an overview of retreat mining can confine themselves to the first few chapters. Those interested in mine planning, should read the middle chapters as well. Those interested in the development of a foreman&apos;s handbook should read the entire manual.

Jan 1, 1981

By Clarke E. Schuetze

This project had as its objective the experimental investigation of water capsule production utilizing the Southwest Research Institute&apos;s submerged nozzle encapsulation apparatus (U.S. Patent 3,389,194). Initial efforts on this project involved nozzle configuration and shell formulation optimization. The shell formulation developed on a prior program was modified during the course of the project to obtain the best balance of capsule breakage resistance and water retention. Subsequent effort centered on determining operating conditions which would produce the best quality capsules for each candidate shell formulation as determined by laboratory tests. Some preliminary work was done to increase the production capacity of the encapsulation equipment. The program was extended with major emphasis concerned with scale-up studies of capsule production capacity and the treatment of problems associated with grouting cartridge fabrication. During the course of the program, water-containing capsules were produced which have good long-term water retention, block resistance and adequate strength. Using a single-nozzle design, a production capacity of 15.9kg (35 pounds) per hour was demonstrated to give acceptable capsules based on initial results.

Jan 1, 1978

By Theodore L. Turner

This Bureau of Mines report describes calcination of kaolinitic clay in a direct-fired 2-1/2- by 24-ft rotary kiln at 750° and 775° C. Methods for preparing kaolin feed materials and characterization of calcined products are discussed. Approximately 99 pct of the alumina in a typical eastern Georgia kaolin was soluble in HC1 after calcination at either 750° or 775° C.

Jan 1, 1982

By E. D. Calvert

Molybdenum has been successfully cast into static and rotating molds in conventional equipment used for casting titanium and zirconium. Melting was accomplished by using an arc potential of 36 to 40 volts with a current of 10,000 amperes. Pouring efficiency, after a skull had been formed in the crucible, averaged 70 percent. Techniques are described by which four successful castings were made. Tensile properties on specimens cut from one centrifugally cast tube averaged: Tensile strength, 39,800 p.s.i.; yield strength (0.1 pct. offset), 35,300 p.s.i.; elongation, nil; reduction in area, nil; impact strength, 2 ft.-lb.; hardness DPH (diamond pyramid hardness) 180. Mold reaction was not evident in shapes cast in machined graphite. This was not true, however, for rammed graphitic-base molds.

Jan 1, 1960

By Kermit G. Davis, Sean Gallagher, William S. Marras, Kimberly Kovacs

This study evaluated spinal loads associated with lifting and hanging heavy mining cable in a variety of postures. This electrical cable can weigh up to 10 kg per metre and is often lifted in restricted spaces in underground coal mines. Seven male subjects performed eight cable lifting and hanging tasks, while trunk kinematic data and trunk muscle electromyograms (EMGs) were obtained. The eight tasks were combinations of four postures (standing, stooping kneeling on one knee, or kneeling on both knees) and two levels of cable load (0 N or 100 N load added to the existing cable weight). An EMG-assisted model was used to calculate forces and moments acting on the lumbar spine. A two-way split-plot ANOVA showed that increased load (p<0.05) and changes in lifting posture (p<0.05) independently affected trunk muscle recruitment and spinal loading. The increase in cable load resulted in higher EMG activity of all trunk muscles and increased axial and lateral bending moments on the spine (p < 0.05). Changes in posture caused more selective adjustments in muscle recruitment and affected the sagittal plane moment (p < 0.05). Despite the more selective nature of trunk EMG changes due to posture, the magnitude of changes in spinal loading was often quite dramatic. However, average compression values exceeded 3400 N for all cable lifting tasks.

By Raja V. Ramani

The potential usefulnuss of reclaimed surface-mined land has received much attention in recent times. This attention is partially due to the establishment of federal environmental reclamation standards but concern for achieving better land uses has also been shown by interested members of the mining industry. In an effort to develop a procedure for evaluating postmining land use potentials, specific mines in various regions of the U. S. were studied to determine the extent of current mined-land planning and to discover characteristics that are regional in nature. As part of this investigation, a 430-acre surface mine in Clear-field County, Pennsylvania has been studied. Established site planning principles have been applied to the case study site including formation of a data base, development of alternate land use plans, and evaluation of the economic, environmental, and social impacts of the land use alternatives. Key factors affecting site realization have been identified along with positive suggestions for applying land use planning processes to mined-land planning.

Jan 1, 1983

By Gerald V. Gibbs

Quadratic functions, Q(hkl), are given to six places in increments of 0.01° for 2? from 0° to 90° for CuKa and from 25° to 180° for CuKa1. The wavelengths used for Cu in the computation are those agreed upon by the Editorial Commission of the International Tables for X-ray Crystallography (1950): CuKal 1.54051 A.; CuKa2 1.54433 A. INTRODUCTION At the Federal Bureau of Mines laboratory, Norris, Tenn., X-ray diffraction crystallography using tubes with copper targets revealed a need for a handy reference for the quadratic functions of copper radiation. The tables presented here were prepared to satisfy that need. The quadratic form Q(hkl) may be expressed in terms of the Bragg diffraction angle 2? and of the wavelength ? as

Jan 1, 1961

By R. D. Berkenkotter

Titanium and iron assays obtained from cores of three diamond-drill holes from the Cebolla Creek titaniferous iron deposit were evaluated by statistical techniques to obtain information concerning the mineral characteristics of the deposit and to make a preliminary determination of sampling requirements for the deposit. A range of sample volumes representing sizes from one-sixth NX core 2 feet in length through full NX core 10 feet in length were prepared by split-ting the NX core with a diamond saw and combining pulverized splits. Results indicate the existence of at least two statistical populations having different average grades of iron and titanium. Each has an assay frequency distribution that is not normal but is highly peaked (leptokurtic). Frequency distributions of assays from specific altered zones of the drill holes appear to be normally distributed. Increasing the cross-sectional area of the sample unit to change assay volume did not result in significant changes either in assay values or the resulting frequency distributions of assays. However, when assay volume is increased by increasing sample interval, the shape of the assay frequency distribution changes, and a normal distribution of assays is approached. Positive correlation exists between titanium and iron assays. The degree of correlation, although very significant, is too low to use for prediction purposes. Although the amount of data from three widely separated drill holes is not sufficient to establish an average grade for this large deposit, it indicates a range of expected assay values and provides some information for determining requirements of future sampling for evaluation purposes.

Jan 1, 1963

By Thomas M. Barczak, Joe Bower, Jinsheng Chen

Pumpable roof supports provide an alternative longwall tailgate roof support and have grown in usage during the past few years. Heintzmann Corporation has been installing pumpable roof supports at the RAG Resources Emerald Mine in western PA since 1998, where they have provided effective roof control in their longwall tailgates. Despite the success of these supports in this application, questions remain regarding critical design issues for optimizing the use of this support technology. The support loading profile is characterized by a high initial stiffness with peak loading occurring at less than one inch of convergence, followed by significant load shedding with a post failure capacity comparable to that of wood cribbing. Therefore, the key to optimizing the support utilization is to provide sufficient load density to prevent convergence from occurring beyond the peak loading capacity. This requires an understanding of how the supports interact with the ground conditions, hence measurement of the ground reaction curve. In order to obtain this information, pumpable roof supports were instrumented to measure support loading. Roof deformation and roof-to-floor convergence measurements in the vicinity of the instrumented supports were also made. The experimental parameters for the installation were the support spacing and water-to-solids ratio of the grout, which controls the grout strength and ultimately the maximum capacity of the support. The study clearly shows that at this mine a 24-inch diameter support is fully capable of providing adequate ground control under depths of cover of 750 ft as only 50 pct of the available support capacity was utilized outby the longwall face. It was also shown that the 2.00 to 1 water-solids ratio, despite providing a slightly softer support response, is sufficient for maintaining the same degree of roof control provided by the traditional 1.75 to 1 grout mix. The 10-ft spacing of the supports did not cause any ground control problems outby the face. However, inby the face the performance of the support is degraded once the peak capacity of the supports is exceeded. It appears that the large load shedding behavior, which is characteristic of this support following peak loading, allows the immediate roof to separate. When this happens, the support is unable to regain control of the roof in time to prevent failure of the immediate roof beam.

By W. E. Schroeder

Two underground installations of the sprayfan system are described and evaluated. The spray fan proves capable of reducing by 1300 percent downtime due to high methane. Spray fan face ventilation at 20 ft brattice setback is shown to give improved methane control over conventional sprays at 10 ft setback. In addition, this report describes: ? A simple method for determining the most economical application of ventilation for face methane control ? The effect of place variables (primary ventilation, auxiliary ventilation, seam height, etc.) on methane concentrations ? The correlation of methane concentrations with brattice setback. These results are utilized to suggest a safer and more economical approach to face methane control.

Jan 1, 1981

By Felix du Breuil

Contract H0177044 included three objectives; (1) consolidate, maintain, and distribute information on STE approved lighting systems; (2) develop and present one-day seminars on underground mine lighting; (3) determine direct labor and hardware costs associated with the installation of mine illumination systems. All objectives were completed with results as follows: Task I - A file containing 1350 Statements of Test and Evaluation (STE) for all types of underground equipment was developed and publicized throughout the coal fields, A total of 40 requests for STE information was received and processed. Task II and III - A series of 50 seminars was scheduled and presented to 942 attendees throughout the coal fields. The seminars were well received and attendees indicated the information presented would be helpful in bringing their equipment into compliance. Holding a series of seminars in the coal fields, instead of a few in population centers, was favored by attendees. Task IV - Installation cost data obtained on 415 lighting systems indicate that the factors which most affect installation costs are higher hardware cost for DC powered systems and slightly higher manpower requirements for systems installed underground. Based on these data, the total cost to industry of retrofitting existing underground equipment could range up to $50 million.

Jan 1, 1979

By Virgil J. Stachura

The Bureau of Mines has investigated techniques and instrumentation that measure accurately the airblast overpressures from surface mine blasting. The results include equivalencies between broadband research instrumentation and commercially available impulse precision sound levels meters measuring: root-mean-square, peak, fast, slow, impulse, A and C weighting, C-weighted sound exposure level (CSEL), and "linear" (flat) response. These values were obtained from field measurements and broadband FM tape recordings of production blasts at area and contour coal mines, limestones quarries, and iron mines. Frequency response was determined for 14 commercial systems.

Jan 1, 1981

By R. K. Linn

The New Idria Mining and Chemical Co. owns and operates the New Idria mine in southern San Benito County, Calif. During 1957-59, the New Idria mine was the largest producer of mercury in the United States and its alltime production of over a half-million flasks was exceeded only by one mine. It is one of the oldest and most consistent producers in California. With the exception of 1921-22, the mine has an annual production of mercury dating back to 1854. This paper by the Federal Bureau of Mines describes the exploration, development, mining, and furnacing of mercury ore at the New Idria mine. Figure 1 is a view of the furnace plant of the New Idria mine. The purpose of this report is to promote the development and conservation of our mineral resources by dissemination of technological information on mining and processing procedures, and related practices at operating mines.

Jan 1, 1961

By Forrest T. Moyer

Injury experience at coal mines and mechanical-cleaning plants (excluding officeworkers ) in 1967 was 222 fatal and 10,115 nonfatal disabling work injuries during an exposure time of 241.8 million man-hours. These injuries occurred at a frequency rate of 42-75 per million man-hours worked; the severity rate was 7,699 days lost or charged per million man-hours. Each of these general measures of injury experience was lower than similar data recorded for 1966. Employment at 6,885 coal mines and 569 mechanical-cleaning plants, excluding officeworkers, averaged 139,312 men in 1967. The average number of days worked was 220. Coal production totaled 560.8 million short tons, at rates of 2.32 tons per man-hour and 18.32 tons per man-day. A total of 2,779 onsite officeworkers at coal mines and mechanical- cleaning plants worked 5.2 million man-hours in 1967 without a disabling work injury.

Jan 1, 1972