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By A. L. Murray, C. A. Allen

"In the Spring of 1919, the Industrial Commission of Utah undertook the assembling of safety orders covering metal mining operations Just at that time there appeared several articles in the mining papers advocating the licensing of hoisting engineers, so this subject was given careful consideration,The licensing of hoisting engineers means that they must pass an examination covering the mechanical features of hoists and boilers, and must have a certain amount of experience. This undoubtedly serves to get a class of hoisting engineers that are better informed about the mechanical operation and theoretical considerations in hoisting and the only room for argument against it is that it is difficult to give an examination that will determine whether or not a man is a competent hoisting engineer.A man might pass an excellent examination yet be absolutely unqualified to operate a hoist and the judgment of the mine super- intelligent would have to be depended upon to choose the right man from among those who were licensed. This difficulty of properly determining, by ordinary examination, a man's qualifications to run a hoist caused the idea of licensing' in the ordinary sense of the word to be abandoned; but, as there was no question that a hoisting engineer should be physically fit, it was decided to require a medical examination, and at the same time to require the hoist engineer to state his experience, so the State would better knowledge of his general qualifications.The orders covering the question were therefore issued as follows;"

Jan 1, 1920

By David E. Siskind

The Bureau of Mines has studied the fracturing produced in the vicinity of large-diameter blastholes in Lithonia granite. Cores were taken from the vicinity of AN-FO production blasts and examined using a total of seven laboratory and field measurement techniques to delineate zones of damage and evaluate the effectiveness of the seven diagnostic tests for fracture-state determination. Laboratory measurements of acoustic pulse velocity, porosity, permeability, compressive strength, and Young's modulus indicated the extent of fracturing with the acoustic techniques providing the best means of distinguishing between fractured and unfractured core. A severely fractured zone was found to extend approximately 25 inches (64 cm) from the center of the 6-l/2-inch blastholes, equivalent to 8 blast-hole radii. A second zone, characterized by a lesser degree of fracturing extended from 25 to 45 inches (64 to 114 cm) or 8-to l4-blasthole radii. Beyond 45 inches (114 cm) the rock was undamaged.

Jan 1, 1974

By J. Davitt McAteer

Dear Mine Operator, Training for new employees, refresher training for new employees, refresher training, and new task training can mean the difference between life and death for workers. Part 46 spells out how you can develop a training program to protect workers for on-the-job hazards. Together, labor, industry, and the U.S. Department of Labor reached a milestone with the development and publication of Part 46. We want to continue working together toward the next milestone, October 2000, when the regulations take effect. We want to make sure you have all the information you need about these new training requirements. Throughout the next 12 months, MSHA personnel will be holding regional meetings across the country, delivering information and sample training plans to your operation, and offering you help to develop your plan. If you are among the many operators who are already providing training to your workers, keep up the good work. The rule will tell you exactly what is expected. If you currently have no training program, we can help you develop one. A brochure is being distributed, which highlights the main provisions of the rule. It is designed to introduce the rule to you. More detailed materials will be delivered to you. If you want information right away, simply call us, or e-mail us. We also welcome your comments, suggestions, and success stories. Part 46 will be successful and beneficial to miners through our combined efforts. Together, we can make our mines safe and healthier for everyone. Sincerely, J. Davitt McAteer, Assistant Secretary of Labor Mine Safety and Health Administration

Jan 1, 1999

By V. R. Spironello

One of the primary objectives of the Bureau of Mines solid waste utilization program is the recycling of the magnetic fraction of municipal solid waste called raw refuse scrap. In this investigation, several types of scrap of differing quality, including refuse and turnings, were melted in a 1-ton electric-arc furnace in various combinations to produce steel in noncritical (construction) grades. In-formation on furnace operation and on the behavior of tramp and alloying elements was obtained. The research showed that it is possible to produce acceptable steel from a variety of steel scrap. Although some scrap is routinely used in steelmaking, it was found that up to 50 to 55 pct of the scrap charge can be ref-use, provided it is combined with higher quality scrap. The chemistry of the steels was generally acceptable, and all of them were rolled without difficulty. The specification (ASTM 615) for the steels produced was grade 40 or grade 60, containing 0.30 or 0.40 pct C, with mini-mum yield strengths of 40,000 or 60,000-psi, respectively. Most of the steels met the specification requirements. In-formation on typical microstructures of some of the steels is included. The composition of some furnace dusts showed high levels of Sn, Pb, and Zn.

Jan 1, 1981

By Eugene T. Sheridan

This report presents data on individual plants of the fuel-briquet and packaged-fuel industries that were circularized by the Bureau of Mines, United States Department of the Interior, in its annual survey for 1958. Only plants that processed fuels of mineral origin were included; specifically, plants that manufactured briquets from charcoal were excluded. Fuel briquets and packaged fuel are manufactured by mixing fine-sized fuels with binders and compressing into small individual shapes. Both are used mainly for residential heating in the United States, but they differ considerably in appearance and physical characteristics. Briquets usually are produced as small, pillow-shaped forms, 2 to 4 inches in length, weighing from 2 to 4 ounces. Pack-aged fuel consists of 3-to 4-inch cubes, 6 or 8 of which are wrapped in heavy kraft paper to form a package weighing 10 to 15 pounds. Briquets are made with a water-insoluble binder and are designed for rough handling and outdoor storage, whereas packaged fuel generally is made with a water-soluble binder and must be stored indoors to prevent deterioration. Briquet plants are relatively large and usually are at mines or in dock areas where large quantities of fine-sized fuels accumulate. Packaged-fuel plants are smaller and are used chiefly by retail dealers to convert locally available coal and coke fines into a product that can be burned efficiently in residential beating equipment.

Jan 1, 1959

By J. S. Malesky

"INTRODUCTION The Airdox method of breaking coal utilizes compressed air under high pressure and was developed to replace explosives. It is used in Illinois and Indiana mines to a large extent and also has been introduced in mines in a few other States.ACKNOWLEDGMENTThe author gratefully acknowledges the information and photographs furnished by the Cardox Corp.HISTORYIn the early 1920's, with the adoption of mechanical mining in States where on-shift shooting was prohibited, it became desirable to develop some means of breaking coal from the face without the use of explosives. At that time it was thought that a pressure of 20,000 pounds per square inch would be necessary to break the seal. It was impossible to obtain a compressor that would develop this pressure therefore, the 'patentees developed and applied the Cardox method, which utilizes liquid carbon dioxide as the blasting medium."

Aug 1, 1948

By James J. Olson

The Bureau of Mines recorded both particle accelerations and velocities from one-stick and production blasts at Eagle-Picher Industries' Shullsburg mine, Shullsburg, Wis., to test the effectiveness of square root scaling in grouping underground blast vibrations and to determine the effects of rock type and mine geometry on blast vibrations. Although the charge weights of subsequent delay periods sometimes exceeded the charge weight of the zero-delay period, both acceleration and velocity records showed that the zero-delay portion of the Shullsburg production blasts produced the highest vibration amplitudes. Because of the restricted range of charge weights in the Shullsburg experiments, no statistical determination of an appropriate scaling factor could be made. However, the square root scaled peak particle velocity data from the Shullsburg production blasts grouped well within the approximate band-width of vibration data obtained by the Bureau from quarry blasts in many different rock types. This indicates that scaling by some factor, perhaps the square root or cube root of the charge weight, may be an effective way to group and study vibration data from underground blasts. Further research is needed to determine which scaling factor is best for underground blasting.

Jan 1, 1970

By L. C. IlsLey

The service given by a flame safety lame is twofold: It provides a safe light and it gives evidence of the condition of the mine atmosphere relative to the presence of methane and the deficiency of oxygen. Since the development of portable electric mine lamps, flame safety lamps are little used for lighting,but their use as detectors is as extensive and important as ever. A flame safety lamp in the hands of a trained user will definitely how methane concentrations as low as 1 percent, which in well below the lower explosive limit of methane and air. However, this does not always suffice, especially when making studies of mine ventilation, where it may be desireable to detect concentrations below 1/2 of 1 percent.

Jan 1, 1936

By L. C. IlsLey

[The service given by a flame safety lame is twofold: It provides a safe light and it gives evidence of the condition of the mine atmosphere relative to the presence of methane and the deficiency of oxygen. Since the development of portable electric mine lamps, flame safety lamps are little used for lighting but their use as detectors is as extensive and important as ever. A flame safety lamp in the hands of a trained user will definitely show methane concentrations as low as 1 percent, which in well below the lower explosive limit of methane and air. However, this does not always suffice, especially when making studies of mine ventilation, where it may be desireable to detect concentrations below 1/2 of 1 percent.]

Jan 1, 1936

By G. S. Rice

The recommendations of the Bureau of Mines on rock dusting practices are embodied, except in a few details, in the Recommended American Practice for Rock-Dusting Coal Mines to Prevent Coal-Dust Explosions, approved by the American Engineering Standards Committee. December 30, 1925. It is specified that the dust to be used is of a elm that all will pass through a sieve having 20 meshes per linear inch and that 50 per cent or more will pass through a sieve having 200 meshes per linear inch. Thus the coarsest size of dust and the minimum proportion of fine dust are specified, but the specification does not indicate whether a larger proportion of fine dust would be desirable. There have been advocates of the use of that size of rock dust of which the particles would all approach 200-mesh in fineness. Explosion tests were made in the Experimental mine in the earlier period of testing which indicated that the finer rock dust is somewhat more effective under test conditions, but not sufficiently so to Justify the cost of finer grinding of the dust; also there are some disadvantages of finer dust described hereafter.

Jan 1, 1930

By M. M. Tilman

The Bureau of Mines investigated the precipitation strengthening of lead¬-base alloys containing 0.5 through 4 weight-percent combined Cd plus Sb. The Cd and Sb were alloyed in a 1-to-1 atomic ratio which maintained compositions along the quasi-binary section Pb-CdSb. Tensile properties, creep rates, and stress-rupture values were obtained on alloys in the aged condition. The highest tensile strength was observed in an alloy of Pb-3 CdSb, After aging for 6 months at 90°±3° F, this alloy had a mean tensile strength of 8,950 psi with 15-percent elongation. An aged alloy of Pb-1 CdSb exhibited a steady state creep rate of 1.2 X 10-3 percent per day at a stress of 500 psi and a temperature of 90°±3° F. Times to rupture at stresses up to 4,000 psi and at a temperature of 90°±3° F were obtained for some compositions.

Jan 1, 1970

Improve the field-of-view into the front-right blind spot for drivers of large haulage trucks, thereby reducing the growing collision hazard in surface mines. Approach Reduce the glare problem found in the first generation fresnel lens blind area viewer design by eliminating the upward-looking section of the fresnel lens and adding a rear hood to reduce backlighting. How It Works The first generation blind area viewer was developed and in-mine tested as an aid to improved visibility for large haulage trucks. Other aids were improved left-and right-hand mirrors. Evaluations showed that a blind area viewer mounted on the right-front of the radiator deck was effective and was readily accepted by drivers. Nevertheless, because glare was a problem under certain conditions, a low-profile viewer was developed. Glare control louvers from the earlier design were kept and a backlighting glare control hood was added. The height of the hardware was reduced by eliminating the top three inches of the fresnel lens. This portion of the lens contained an upward-looking segment which originally was thought to be needed so the driver could see the horizon when he looked through the viewer and be better

Jan 1, 1982

By A. B. Hooker, L. C. IlsLey

"Field inspections and data relative to the use of rubber—sheathed trailing cables in mines show that much cable is ruined or its probable life shortened by being overheated in service.The length of cable required to make connection from a source of supply to a machine at the face workings may be 100 to 500 feet. As a rule, the cable is carried on a reel and unreeled as required; and thus in most cases some of the cable is not removed from the reel. The overheating generally occurs in that part of the cable which is left on the reel.Factors that determine the heating of trailing cables are:1. The size of the conductors in the cable.2. The maximum energy to be supplied through the cable, based upon the horsepower of the motor and the degree to which the motor is loaded.3. The voltage of the supply and the variation of the voltage at the receiving4. The time length of current flow and whether continuous or intermittent.5. The kind of current (direct or alternating).6. The amount of cable left on the reel.7. The type of cable used.8. The kind of reel used.In connection with an investigation of the general performance of rubber—sheathed trailing cables, the Bureau of Mines has made a limited study of some of these factors, including the following points:"

Jul 1, 1931

By John C. Ferm

This report contains a summary of Phase I and complete results of Phase II portions of a study of geologic factors associated with roof falls in mines on the Pocahontas #3 coal seam in southern West Virginia and southwestern Virginia. Principal objectives of Phase I was the selection of five mines that best portrayed the spectrum of roof and mining conditions and Phase II consisted of a measurement and documentation program for each of the five mines. The documentation measurement program included reconnaissance mapping, detailed mapping, joint measurements and coring roof rock. 1.2 PHASE I RESULTS The results of Phase I consisted of the selection of the following five mines for detailed study: Virginia Pocahontas #3 (Island Creek Coal Company), Bishop (Consolidation Coal Company), Shannon Branch (Allied Chemical Company), Keystone II (Eastern Associated Coal Company) and Macalpine-East Gulf (Westmorelenad Coal Company). In addition, Phase I results, which were based on questionnaire data, indicated that the kind of rock in the roof --gray sandstone, crystallized sandstone, laminated sandstone and shale, grey shale, slickensided shale, and rider seams could be associated with good and bad top areas. Also presence of vertical separations, bolt length, entry and cross-cut width, length and torque on bolts and depth of overburden seemed to be related factors. These data provided a focus for the Phase II measurement program.

Jan 1, 1975

Determine whether the total delay time in blasting may be safely increased beyond the currently permitted 0.5 s, without igniting a methane or methane-coal dust atmosphere and determine the minimum borehole spacing to avoid misfires. Approach At present, regulations limit the delay time used in short-delay blasting to a total of 0.5 s. Many in industry and government would like to see this total delay time increased to 1 5 to permit an increase in the number of different delays available for short delay blasting and an increase in the time between delay periods. The Bureau of Mines conducted research to determine whether the total elapsed delay time for blasting coal in underground mines could be safely expanded, with resulting improvements in productivity. The research was conducted at a surface mine in St. Clairsville, Ohio. Experimental shots were conducted in several pits, each of which had a 5-foot-high coal seam (Pitts-burg No.8) in a 50-foot highwall. The coal seam and a mobile gallery provided a good simulation of an underground coal face. The Bureau also examined the relationship between borehole spacing and misfires, to check on reports over the past few years that permissible explosives frequently misfire. These reports were not well documented, but were numerous enough to warrant investigation. Misfires of permissible explosives in an underground coal mine can be very hazardous; a burning cartridge of explosive may be ejected from a borehole and ignite the gas or dust in the mine, or a misfired cartridge in the muck pile may detonate during drilling and mucking operations, causing serious injuries.

Jan 1, 1986

By J. F. Shaw

MINE fires are usually extinguished by constructing seals in the approaches to the areas to exclude air from the fire areas, which smothers the fires in an oxygen-depleted atmosphere. Seals should be substantially constructed and made as nearly airtight as possible and should be provided with a sampling pipe so that samples of the atmospheres behind the seals may be collected at regular intervals. Methods of constructing seals and of sampling and analysing mine atmospheres are fully described in Bureau of Mines publications. (1, 2). Information obtained on the composition of atmospheres behind fire seals is helpful in determining if a fire has been extinguished or if there is any danger of an explosion when a fire area is being sealed or unsealed. The progress of a mine fire can best be determined by studying percentages of carbon dioxide, carbon monoxide, and hydrogen in the atmosphere behind the seals. Hydrogen will be formed in a bituminous- or subbituminous-coal mine when the temperature exceeds 480° F. and in an anthracite mine when the temperature exceeds 660° F. (3). Carbon monoxide and carbon dioxide are both products of combustion of coal, wood, or other organic compounds. The presence of carbon monoxide has long been accepted as an indication of a mine fire. A sealed fire area should not be reopened until the carbon monoxide has disappeared. Trends in the percentage of carbon dioxide are also useful in determining the status of a mine fire. Carbon dioxide is sometimes liberated by rock strata. In this case, carbon dioxide in the atmosphere behind a seal will be from two sources-the rock strata and the fire. When the, fire is extinguished, carbon dioxide will be liberated from only I source, the rock strata, and when the percentages of carbon dioxide are plotted, the slope of the curve will not be as steep as when this gas was being liberated from 2 sources. If the only source is the fire, the percentages of carbon dioxide will gradually decrease after the fire has been extinguished. By studying analyses of a mine-fire atmosphere, it is possible to determine if the atmosphere is explosive; if the mixture is capable of becoming explosive when mixed with air; and if the mixture can be made nonexplosive or be prevented from becoming explosive by being mixed with an inert gas. These factors can be computed mathematically or determined graphically. The mathematical calculations advanced by Ash and Felegy (7) are discussed, and graphical solutions of their equations are presented. It is believed that the graphical solution will be extremely helpful in determining the characteristics of a mine-fire atmosphere when fighting a fire, because the results can be obtained in a matter of minutes, and there is less likelihood of an error being made under the stress incident to control efforts. The experimental and theoretical work upon which the formulas are based have been adequately described and are not discussed at this time (5) (6).

Jan 1, 1955

By H. C. Loesche

The problem of signaling to the hoisting engineer from the cage in a shaft mine has been given considerable thought and attention by engineers and mine operators seeking to Increase the safety and efficiency of hoisting. HISTORY R. L. Rutherford,3/ an employee of the Magma Copper Co., Superior Ariz., realizing the need for a simple and practical moving-cage signaling system, began a serious of experiments early in 1937, Available electrical moving-cage signal in operation at this date required that signal wires be installed in the shaft to make a simple, positive signal without wires, the first experiments used the pipe lines in the shaft for carrying the signal current, but these experiments were not successful.

Jan 1, 1945

By V. E. Homme

This report describes methods of using sodium for reducing titanic chloride, developed as part of Bureau of Mines activities at Boulder City, Nev., to improve the extractive metallurgy of titanium. Theoretical indications pertaining to the major chemical reactions and possible side reactions of the process are compared with experimental observations. Low-temperature reduction equipment is described, in which titanic chloride was reduced with sodium at temperatures between 97.5° C., the melting point of sodium, and 200° C. Techniques employed in making reductions in ball-mill and high-surface sodium reactors are given.

Jan 1, 1958

By A. J. Barry

A method was developed for testing the anchorages obtained with 3/4-inch, expansion-type, headed bolt and shell assemblies. The apparatus is a modification of that used in testing -inch-diameter, slotted-type bolts. Four makes of expansion-type shells were used in 64 tests made in sandstone and shale roof. The results show that for 3 makes of shells the anchorage effectiveness is independent of the installed land, and for the fourth make of shell a better anchorage is obtained when instilled at a load of 8,000 pounds. The results also show that deformation of the expansion plug influences the majority of the anchorages obtained with two makes of shells. This deformation causes a larger increase in displacement for a given added increment of load. The data from 48 of the 64 tests were combined to establish a relationship between average displacement and increase in bolt load (above the installed load). This relationship can be used to evaluate the anchorage effectiveness of any 3/4-inch-diameter, expansion-type, headed bolt and shell assembly tested in the field.

Jan 1, 1956

By Frank E. Cash, Max S. Petersen

"INTRODUCTION Explosives have been used in ever—increasing amounts since gunpowder was invented. For hundreds of years only low explosives of the deflagrating type were used, and they were fired by means of a flame or hot object. Ben¬jamin Franklin first ignited gunpowder from a distance in 1751 by means of an electrostatic spark. Further efforts to develop a satisfactory electrical method to ignite explosives from greater distances were overshadowed by the invention of safety fuse in 1831, as this offered a relatively simple and inexpensive means of firing explosives.The discovery and introduction of high explosives of the detonating type and the invention of the fulmitate of mercury blasting cap about the middle of the nineteenth century provided the needed impetus for inventors to develop means of firing the cap by electricity. The original high-tension igniter, following Benjamin Franklin's experiment in which the detonating compound was ignited by a spark, was discarded in favor of a low-tension igniter, in which the detonating compound was ignited by a heated wire. The past 2 decades have seen considerable improvement in the design and construction of electric detonators to make them safer and more efficient, yet in spite of the improvement it is estimated that less than 50 percent of the explosives used in industry today are ignited or detonated electrically. The trend, however, is toward the use of electric methods. In recent years numerous-mining companies have introduced electric blasting exclusively at their mines as a means of improving safety and efficiency."

Sep 1, 1946