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By Clarence O. Babcock

ROCK BEHAVIOR has proved of national interest in a variety of fields. The behavior of rock consequent to a nuclear blast was used to detect such blasts, as criteria for the design of underground military defense installations that would resist nuclear blasts, and for judging the feasibility for peaceful uses of nuclear explosives. An obvious peaceful application of nuclear explosives would be for large-scale rock excavation, and plans were presented during the year to improve the present Panama Canal or create a new canal by this method. These plans were based largely on earlier crater tests that demonstrated rock behavior when subjected to a buried nuclear blast. A knowledge of rock behavior under impact was used to evaluate the materials of the moon by means of the geometric configurations visible in the close-up pictures of the moon surface taken by the U.S. rocket Ranger 7. The composition of the moon must be considered in devising methods for taking samples of the surface layers or in designing underground shelters as bases for future explorations of the moon.

Jan 1, 1965

Develop a method for control of groundwater inflow to chronically "wet" sections of underground coal mines, in order to reduce groundwater interference with mining activity and to minimize acid mine drainage. Approach In eastern coal regions, groundwater stored in fracture zones in the rock mass can create a significant water problem for underground mining operations. Fracture stored inflow to mine workings impedes mine productivity since storage water sources usually release at the active face, creating the poor mining conditions typical of a "wet" section. Fracture water can also contribute to AMD problems when the water subsequently contacts sulfide minerals in the coal, The Bureau of Mines has developed a mine-dewatering method that eliminates many of the problems associated with mine water inflow by draining these fracture zones before the water can reach the developing face and interfere with mining activity. How it Works The dewatering method removes large volumes of the stored groundwater through high-capacity pumping from a minimal number of wells placed strategically on fracture traces (the surface expressions of fractured rock zones). These fracture traces are located through low-level aerial photographic and geologic investigation. As shown on the map, dewatering wells are sited precisely on fracture trace intersections in order to take advantage of the increased pumping capacity gained from these zones of high permeability. Once well drawdown indicates that the stored water is depleted,

Jan 1, 1983

By T. L. Joseph

"In the January 3 issue of Iron Trade Review, Sweetser2, in referring to the problem of coke combustibility, points out that, ""Someone should formulate a rule for the rate of flow of coke through the zone of coke combustion that now appears to be confined to a comparatively restricted volume in front of the tuyeres,"" In formulating such a rule it is necessary to distinguish clearly between combustibility, a property of the fuel, and rate of combustion, which is determined by the rate at which air is supplied to the fuel bed. The rate of carbon gasified at the tuyeres of a blast furnace is independent of coke combusti-bility. A fast-burning coke will burn in a more restricted volume than a slow-burning coke, but both types of fuel will be consumed at rates determined by the supply of oxygen,A number of the definitions of combustibility that have appeared in technical literature relate more closely to rate of combustion than to combustibility. Perrott and Kinney) have correctly defined it as follows: ""Combustibility of coke from the standpoint of its use in, the blast furnace is inversely proportional to the mean rate of gasification per unit volume of the combustion zone, assuming other factors remain constant,"" Combustibility of coke refers therefore to those properties that determine the size or extent of the combustion zone. Relative differences in these properties can be measured by the depth of the fuel bed required to convert oxygen from the air into carbon monoxide."

May 1, 1924

By T. A. Sullivan

Research undertaken by the Bureau of Mines in 1938 has resulted in the development of titanium from a laboratory curiosity to a commercial metal. Along with processes for producing the metal, it was necessary for the Bureau to develop methods for analyzing the metal, raw materials, and intermediate products. Some of the methods developed have been published.3 4 5/ General Services Administration (GSA) was responsible for purchasing titanium metal under Defense Production Act contracts with commercial producers. GSA designated the Federal Bureau of Mines to analyze this metal and establish its compliance with Government specifications. A substantial quantity of tin was found in some of the samples analyzed, and in July 1957 tin was added to the list of impurity elements to be determined. The specifications limited the amount of tin in titanium sponge to a maximum of 0.10 percent. A program was immediately initiated to investigate methods and techniques for determining tin in the range of 0 to 1.0 percent. A method accurate at the 0.10 percent level was necessary, as this level was the critical range for acceptance or rejection of the metal.

Jan 1, 1960

By H. Robert Ensminger

The Belizean economy had an estimated annual growth of about 3.4% over that of 1986. Economic growth during the 2 previous years was slower and was characterized by a negative trade balance. The gross domestic product (GDP) was an estimated $200 millioni2 in current dollars. Limited natural resources and scarce finances continued to make the Government's task a difficult one. Belize and China signed an economic cooperation agreement in April under which the Chinese Government is to provide technical assistance, a cash grant of $60.000, and a long-term, interest-free loan of approximately $1.5 million. In May, it was reported that gold was discovered in a remote area of the Maya Mountains in western Belize. An estimated unassayed value of $400 million has been placed on the deposit by one of its discoverers. However, the government in Belmopan has played down the discovery. Two U.S. oil companies. Seahawk Oil International of California and Alston Oil Co. of Texas, were granted licenses to explore for oil. Seahawk Oil will explore a large area of the Orange and Corozal Districts, while Alston Oil will prospect a 90,000-acre area of the western Cayo District. Another U.S. oil company, Pecten Oil Co., recently completed seismic studies off-shore of Belize City. Pecten Oil has made plans to start drilling in 1988.

Jan 1, 1989

To develop a reliable, remotely-controlled, mobile roof support to eliminate the need to set posts, cribs, or props while extracting coal pillars. Approach The primary danger during pillar extraction is premature caving of the mine roof. The roof must cave predictably and dependably to ensure the safety of miners. Support during retreat mining is usually obtained by setting posts, cribs, props, roof bolts, or a combination of these devices. These are set manually by miners in the working area. To help minimize the danger to mine workers and to equipment posed by premature falls, the Bureau of Mines developed the mobile roof support (MRS) system to secure the roof during pillar extraction. How It Works The Mobile Roof Support (MRS) is eight-feet-wide, ten-feet-long and five-feet-high, with twelve inches of ground clearance. It is ruggedly built and exerts less than 20 psi ground pressure. The MRS is powered by a 40-hp, 460-v AC permissible motor. The reversible, variable tram speed is 80 ft/min on a 20-percent grade. It is tire-mounted, has a trailing cable, and is remotely controlled either by a radio or a tether communication cable. The machine carries four 50-ton jacks which serve as props for working heights from seven to fifteen feet. Two jacks are chassis-mounted and two are on swing arms. Each jack has a cap which distributes the roof load to three paints. The swing jacks form a breaker row to stop falling roof and prevent caving Into the work area. One jack has a visual load indicator and a second is wired to the machine lighting system. Blinking lights indicate when the preset loading is being exceeded. In the case of excessive loads, an ability to remotely jettison either or both swing jacks has been incorporated into the system to permit removal of the MRS while the roof is still supported.

Jan 1, 1985

Investigate and demonstrate the possible use of low-density (45-lb/ft3) foam concrete for sealing abandoned mine openings. Although foam concrete has been used in the construction and geotechnical industries for some decades, it has not previously been used in abandoned mint shaft reclamation. Approach A structurally engineered permanent mine seal for an abandoned coal mine shaft, using low-density foam concrete and other appropriate structural materials, was designed by the Bureau and installed at a field site, the No. 22 Shall in Logan County, West Virginia. The field work was conducted by a private contractor under the supervision of the West Virginia AML Section (WV AML). The No. 22 Shaft is situated immediately adjacent to a frequently traveled county road. A few feet away from the shaft is a branch of Pine Creek. On the other side of the road is a railroad line that serves an active mining operation located several miles away. The shaft measures 9.5 by 9 feet in cross section and is about 300 feet deep. It was used at one time as a dewatering shaft and still contains two large-diameter dewatering pipes with steel drive shafts inside them. Before the beginning of the reclamation, the shaft included a concrete cap a few inches thick, with a 4 - by 5-foot access opening covered by a steel grate. The interior of the shaft was quite humid, and considerable flow of water at the bottom of the shaft could clearly be heard from the surface. Methane tests were conducted that showed the shaft to be clear of this gas.

Jan 1, 1992

By Allen D. Look, Stanley M. Walker, Van Fleet. Leonard A.

"INTRODUCTION The hazards to be encountered in temporarily or permanently abandoned underground mines, quarries, and open pits are numerous, and hardly a year goes by without several reported cases of fatal or serious injuries occurring to unwary people who enter these old mines. Persons visiting mining areas for the first time, tourists, and young people, especially, proceeding in the spirit of adventure common to youth or to the venturesome have suffered many such accidents during exploration trips. The possibility of salvaging salable or usable equipment prompts men and boys to go into old mines, some through ignorance of the attendant hazards, but some jeopardize their lives hopeful of gain (in some cases pitifully small), thinking the hazards are not dangerous and that they can ""get away with it.""Persons fall into unprotected holes, some seek shelter from storms under high banks, and quarries and open pits are often chosen as places for recreation, picnics, swimming, etc; all such uses of these places are likely to be hazardous and to lead to accidents, frequently fatal.These hazards are known to men in the mining profession, and the danger to the public is realized by most of them. A solution to the problem has been sought at many mining meetings, and it is recognized that complete prevention of entry into old mine workings and surface mining areas is the ideal solution, but this, unfortunately, is not always practical; better education of the public, particularly children, should help to reduce the number of such accidents and will be effective in direct proportion to the extent and vividness of such education."

Aug 1, 1948

To evaluate the potential for dust reduction, during blasthole drilling, of water or foam applied directly into the drill hole. Approach The Bureau of Mines tested a through-the-drill-steel water and foam injection technique in two noncoal mines to evaluate the method's potential for greater dust reduction. The tests were performed by drilling a series of blastholes for an entire face (a 90 minute time-period). For the first 45 minutes of drilling, foam or water was applied through the drill steel. Blowing ventilation was supplied to the entry about 50 feet from the face. The dust concentration measurements were made by a Real-Time Aerosol Monitor (RAM-I), and the data were read out on a strip chart recorder. The evaluation test results showed that the water or foam injection technique, when used on localized dust sources, can be an extremely effective dust control method. Small amounts of water used in this method have also allowed it flexibility to be used in water-soluble ores such as salt, gypsum, anhydrite, and trona. How The System Works Water or foam is mixed with compressed air (approximately 100-120 psi) with suitable metering systems and forced through the drill steel into the blast hole at the point of dust generation. Because the water or foam is applied at the source, minimal quantities of liquid are needed (0.2 to 0.6 gpm). These low flowrates are sufficient to just moisten the dust emerging from the blast hole, thus eliminating a major source of airborne dust. The wet drilling procedure also eliminates a second source of dust. With dry drilling, the dust from the blast hole falls to the floor. Since this can be a 15-ft drop or more, the impact can send the dust billowing up from the floor, adding to the airborne dust. With wet drilling, the moistened dust merely dribbles down the face.

Jan 1, 1982

Reduce the airborne dust generated in a longwall coal face. Approach Reduce the rotational speed and increase the depth-of-cut of the longwall shearer. How It Works An Anderson-Mavor AM500 double-ended ranging drum shearer was fitted with drums specially designed to accept the large picks required for this testing program. Change gears In the shearer allowed rotational speeds of the drums to be set at 35, 45, 55, or 70 rpm. As deep cutting removes larger coal fragments, the specific energy requirements of the operation are reduced and less surface area results. Dust generation and shearer power consumption are also reduced. The lower rotational speed minimizes the fanning action of the cutterheads and thus reduces the amount of coal fines that become airborne.

Jan 1, 1981

By Robert L. Chufo, H. Kenneth Sacks

Medium-frequency (MF) waves can propagate in a coal seam, bounded above and below by conducting rock, in an approximate transverse electro-magnetic (TEM) transmission-line mode with the electric field vertical and the magnetic field horizontal. The theory of this coal seam mode is applied to recent MF data for a number of mines in order to classify the propagation characteristic of the mines in a simple way. When conductors such as rails, trolleylines, or power cables are present in the vicinity of the measurement path, it is found that the magnetic field versus range plots have two distinct regions with very different slopes. This effect is attributed to coupling of the cylindrically spreading coal seam mode to a low-attenuation conductor guided mode. As a result, voice communications range between mobile transmitters can extend several thousand meters. The use of MF for mine communications is discussed.

By T. J. Ballard

The Track Rock corundum mine was among the numerous corundum deposits investigated during the war by the Bureau of Mines in an effort to develop domestic reserves of that critical mineral. In the investigation of this property 562 feet of trenches were excavated and a l25-foot adit was reopened for the purpose of locating veins to of corundum which had been previously reported to occur in that locality. Only very minor amounts of corundum were disclosed in both the surface workings and the adit. The project was begun in May 1943 and completed in November 1943.

Jan 1, 1948

Native asphalt was produced in 1977 by six companies in four States. Leading States were Texas and Utah. Output declined 39% to 1,237,000 tons valued at $18,874,000. Bituminous limestone was produced by Whites Uvalde Mines and by Uvalde Rock Asphalt Co. in Uvalde County, Tex.; by Southern Stone Co. in Colbert. Ala.; and by Barton County Rock Asphalt Co. in Barton County, Mo. Gilsonite was produced by American Gilsanite Co. in Uinta County. Utah, and by Ziegler Chemical and Mineral Corp. in Weber County. Utah. The asphalt was used for streets and roads, and for other purposes.

Jan 1, 1980

Eliminate the occurrence of false fire detection alarms caused by the operation of diesel-powered vehicles in underground coal mines. Approach Fire detection systems used in underground mines are based on measurements of airborne combustion products such as carbon monoxide or smoke particles. The effectiveness and credibility of these systems can be reduced by the occurrence of false alarms that result from the operation of diesel-powered equipment, which produces the same combustion products. False alarms end up being very costly to the mine operation in terms of downtime and labor needed for verification. To improve upon current fire detection systems used in the presence of internal combustion engine products, the U.S. Bureau of Mines developed a fire detector that can discriminate between the occurrence of real mine fires and the presence of engine smoke.

Jan 1, 1989

Investigate the use and placement of lightweight concrete to improve ground control technology in deep mines where deformation occurs under heavy ground conditions and where there is danger of rock bursts. Approach Investigations of lightweight concrete properties and placement methods were conducted in the laboratory and in the field. Three test sections were completed: a monolithic, portal-type structure with integral walls and arch constructed aboveground; an underground test section constructed in a mine drift using plywood forms; and a test section constructed in a mine drift using an air-supported formwork. In the two underground test sections, the light-weight concrete was placed using a piston pump with concrete discharge line. A cooperating mine also used lightweight concrete, in the density range of 25 lb/ft3, to replace timber blocking in a raise preparation structure (the enlarged area across a vein where chutes and manway access arc placed). Other experiments included the use of precast lightweight concrete blocks in situations where ground support was needed, such as fur mine, ventilation doors, stoppings, and barricades.

Jan 1, 1990

By E. Morrice

Techniques developed by the Bureau of Mines for the preparation of high-purity rare-earth metals and their alloys by electrolysis of the oxides in fluoride media are summarized. Cerium, lanthanum, neodymium, praseodymium, dysprosium, gadolinium, and yttrium metals, the mixture didymium, and specific alloys of these metals and samarium with iron, nickel, chromium, and cobalt were prepared. Individual metals were electrodeposited in the liquid state on tungsten or molybdenum cathodes. Alloys were prepared by electrodepositing the rare-earth metal on a consumable cathode, at a temperature above the melting point of the eutectic formed between the rare-earth element and the cathode material. Cells were designed for electrowinning metal products in gram and pound quantities, and methods for continuous electrowinning of cerium and lanthanum were developed.

Jan 1, 1968

By Richard A. Thomas, Charles D. Litton, Kenneth E. Mura, Harry C. Verakis

Experiments were undertaken to evaluate the flammability of typical noise abatement materials used to line the cab interior of mobile mining equipment. The experiments were conducted using three different experimental configurations: 1. A ventilated tunnel test. 2. A full-size cab test where the interior surfaces were lined with the sample material and then ignited near the floor using a methane-air burner. 3. Standard ASTM E-162 tests using a radiant panel test apparatus. This paper describes the tests and presents the results obtained for 15 to 20 different materials of various chemical compositions and thickness. With one exception, materials that did not exhibit flame spread in the tunnel test also performed well in the full-scale cab test. All materials that had passed only a small-scale flammability test, such as SAE J369, failed dramatically in all three of the above test configurations. With one exception, all materials that performed well in the full-scale cab test had flame spread indices < 25, based upon the ASTM E-162 results. The lone exception had an ASTM E-162 flame spread index of 68. With regard to samples that failed the full-scale cab test, the carbon monoxide levels within the cab reached lethal concentrations in the range of 1.8% to 3.8% within 2 minutes from ignition of the sample—dramatically illustrating the severe fire environment that can result within the cab space.

By R. F. Abernethy

A chemical method of determining microgram quantities of arsenic in coal was investigated by the Bureau of Mines to supplement a semiquantitative spectrographic method of determining arsenic in coal ash. In accordance with a method recommended by the International Organization for Standardization, 1-gram samples of coal are decomposed by wet oxidation with boiling sulfuric acid (H2S04) and nitric acid (HN03) to remove the organic matter. After heating to fumes of SO3 to remove HN03, the arsenic is separated as arsine by the action of zinc in H2S04 solution. The arsine is absorbed in dilute iodine solution in which the arsenic is determined colorimetrically by the molybdenum-blue reaction. Two modifications of the method for obtaining the arsenic in solution, in addition to the wet oxidation method, give satisfactory results. The modifications are (1) furnace ashing with MgO added to the coal, followed by treatment with H2S04, and (2) extraction of arsenic from the coal by dilute HNO3 without ashing. Float-and sink-tests show that arsenic is associated mainly with mineral matter in the three coals examined. High-temperature ashing tests show that very little arsenic is volatilized from coal ash below 1,000° C, but it is virtually all removed from the ash at 1,300° C.

Jan 1, 1968

By Isaac A. Zlochower, Kenneth L. Cashdollar

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) conducted a study of the explosibility of various metals and other elemental dusts, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafnium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties-from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly "refractory" elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechnic ignitors. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from "-1550K for tin and tungsten powders to "-2800K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures.

To develop a simple device for rapidly determining the shearing strength and angle of Internal friction of coal and rock in situ. Approach Use a portable, permissible, hydraulically operated device in boreholes as deep as 100 feet into the rib, floor, or roof of the mine. How it Works The device, called a Borehole Shear Strength Tester (BST), is inserted Into a 3-inch-diameter borehole to the desired depth, locked Into position, and activated to shear the rock or coal in the borehole walls. The normal and shear pressures exerted by the BST, which are recorded during the test, are used to calculate the shearing strength and the angle of internal friction. The BST consists of 3 main components and several minor components. Main components are: ? A shear head with 2 shear plates that bite into the rock when normal pressure is applied. ? A hollow hydraulic jack with RW drill rods that pull the shear head when shear pressure is applied. ? A console with a hand pump and two hydraulic gages to activate the device and to indicate the pressures that apply the normal and shear faces to the shearing plates.

Jan 1, 1981