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To prevent injury to miners caused by violent whipping of mining machine trailing cables. Approach: The hydraulic cable controls are adjusted to reduce whip by visual reference of the cable sag to the height of the cable guide. How It Works: The cable sag is adjusted by visually estimating its height above the ground, at a specific reference distance behind the machine. This reference distance is measured horizontally back from the point where the cable leaves the cable guide. The Reference distance is 2H where H equals the height of the cable guide above the floor. See Figure 1. Cable sag should be less during rewinding than during unwinding. During cable unwinding, the cable height (at the refer¬ence distance) should equal 1/31-1. During rewinding, the cable height should equal ½ H. Field tests were made on several manufacturers' equipment after adjusting cable sag as above. Cable whip was greatly reduced for all, and whip was almost eliminated on a shuttle car equipped with a Joy Manufacturing Company 500108-104 cable reef and the newer (nonporous) shuttle valve. The following directions are for adjusting cable sag on a shuttle car equipped with a Joy Manufacturing Company 500108-104 Cable Reel equipped with the newer shuttle valve. Cable sag can be adjusted on machines equipped with other cable reels and valves by referring to the manufacturer's manual and making the appropriate cable valve adjustments.

Jan 1, 1976

By Jack C. White

The Bureau of Mines, in its efforts to insure the continued viability of the domestic minerals economy, has been engaged for several years in research on the extraction of alumina from domestic, nonbauxitic resources. Hydrochloric acid leaching of kaolin is one of the more promising technologies being studied for recovering alumina for feedstock to existing aluminum smelting capacity; 93 pct of this feedstock is currently imported either as bauxite or alumina. Organics contamination of pregnant leach liquor, originating during solvent extraction for removal of iron from aluminum chloride solution formed during hydrochloric acid leaching, causes rapid deterioration of the semihard rubber lining of process equipment. These organics were removed by a skimming tank-coalescer-activated carbon adsorption system. Organic levels of less than 10 ppm from the coalescer and less than 0.5 ppm from carbon adsorption were achieved. Analytical methods employing CC14 extraction and infrared spectrophotometry were developed to determine the organic content of both the liquor and the carbon. Mass transfer zones delineated in the carbon columns provide adsorption data for the design of larger systems.

Jan 1, 1981

By R. T. Stull, L. E. Geyer

"Previous Work:As outlined in previous papers* ond clays for graphite crucibles have been tested at the plants of the Detroit Lubricator Co., and the Detroit Copper and Brass Rolling Mills, Detroit, Mich.These tests indicated that there were two American clays (Missouri pot clay and Illinois kaolin) that tested better than the Klingenberg (German) clay. Dorset (English) ball clay was tenth in the list.Making the Crucibles:After it had been determined that American clays can be used successfully in graphite crucible manufacture and service, the next step in the investigation was to determine the value of American graphites as compared to the foreign, These final tests were carried out at the plant of the Detroit Lubricator Co., through the courtesy of Mr. G. B. Duffield. The crucibles, as previously. were made at the plant of the Vesuvius Crucible Co., Swissvale, Penna., from a formula compiled by the Bureau of Mines and under the supervision of Bureau engineers.The graphites to be tested were given an initial to indicate their source. The number of crucibles made and shipped are set forth in Table 1."

Nov 1, 1923

By Dennis Dolinar, Christopher Mark, Gregory M. Molinda

In 1999, 2,087 unplanned roof falls were reported from 841 mines. Nearly 55% of all mines reported at least one roof fall, and nearly 17% of the mines reported five or more falls. In order to investigate the variables that contribute to roof falls, the National Institute for Occupational Safety and Health (NIOSH) compiled a national database of roof performance from 37 coal mines. Geotechnical factors and their effect on roof fall rates were compiled from over 1,500 miles of drivage. The factor that is the best predictor of roof fall rate is the Coal Mine Roof Rating (CMRR). For a low CMRR (#30), almost all cases have high roof fall rates. Conversely, high roof fall rates are rare for strong roof rocks (CMRR $ 60). Roof fall rates were also higher in deeper mines, probably because of greater stresses. Intersections were much more likely to fall than roadways, and four-way intersections were more prone to fall than three-way intersections. In a controlled comparison of the effect of increasing bolt length on roof fall rates, it was found that longer bolts reduced the roof fall rates in 11 of 13 cases. A relationship between the roof fall rate, the intersection span, and the CMRR was also found. Finally, a systematic method for tracking roof performance and geotechnical variables was demonstrated.

Jan 10, 2000

By H. Robert Ensminger

As a result of the new mining law implemented in August 1985 and the programs conducted by the Institute Ecustoriano de Mineria (INEMIN), which was created by this legislation, there was considerably greater activity in the nonfuels mineral sector during 1986. Over the next 2 years, INEMIN will be developing a national mining plan that will guide Ecuadorean mineral development for the balance of this century. As stage one of INEMIN's mineral study, historical records were reviewed and 300 abandoned mines and 1,200 unexplored mineral deposits were available for further investigation. In 1986, INEMIN established 5 branch offices and negotiated 250 new mining contracts with foreign companies valued at $16 million. Despite all this activity, INEMIN officials estimate that 100,000 square kilometers remain available for claim staking. Technical assistance contracts were signed with Belgium, the Federal Republic of Germany, Italy, Spain, and the United Kingdom, to assist in a variety of assignments ranging from helping prepare the national minion plan to the development of industrial mineral deposits.

Jan 1, 1988

By L. B. Berger, W. P. Yant, R. R. Sayers

"At the request of the Chesapeake & Ohio Railroad Co. a number of tests were made to determine the temperature, humidity, and composition of the atmosphere in certain tunnels of that railroad between Clifton Forge, Va., and Hinton, W. Va. The purpose of these tests was to determine conditions in the cabs of freight locomotives while pulling trains through these tunnels. Tests were made of two types of locomotives, classified by the railroad company as the H-6 and H-7. Both are of the Mallet type, but the H-6 class has one pair of cylinders operating at boiler pressure and the other pair compound, whereas the H-7 operates all four cylinders at boiler pressure, thereby exhausting steam at a higher temperature than the H-6. It was desired to determine the relation between conditions on the H-6 and H-7 engines under comparable conditions of operation. This information supplements previous tests by the Bureau of Mines, discussed in its Reports of Investigations Serial No. 2624, entitled, ""Temperatures in Cabs of Freight Locomotives Passing Through Tunnels of Chesapeake & Ohio Railroad, 11 by s. H. Katz and E. G. Meiter, July, 1924. Three incidental tests of passenger engines were also made."

Feb 1, 1928

By Harry E. Tuff

"This paper is based data obtained by the Bureau of Mines from some of the principal mine operators in Pennsylvania, in the course of a study conducted in cooperation with the U. S. Forest Service, with regard to economies that might be effected in the selection storage, and preparations of timber particularly treatment with preservative to prolong its life.The Pennsylvania anthracite region, considered as a single mining district is by far the largest user of mine timber of any mining district, either coal or metal, in the United States, and the bituminous districts of Pennsylvania rank second. The present annual consumption of mine timber by the coal-mining industry of Pennsylvania probably exceeds 100,000,000 cubic feet annually.In 1919, Pennsylvania produced, in round figures, 145,300,000 tons of bituminous coal, 86,200,000 tons of anthracite, and 5,400,000 tons of iron ores. If it be assumed that the bituminous coal mines required 0.33 cubic feet, anthracite mines 0.7, and iron mines 0.9 cubic feet per ton mined the timber requirements were bituminous. 47,950,000; anthracite, 60,340,000; iron mines, 4,860,000 or a total of over 113,000,000 cubic feet.The average cost of round mine timber in the anthracite region in 1905, was, according to the U. S. Forest Service, 6.6 cents per cubic foot, and $15.00 per 1000 board feet for sawed timber. The present cost Las advanced to 27.5 cents per cubic foot for round timber, delivered to the mine, of which cost 57.4, represents freight charges."

Nov 1, 1923

By L. W. Brandt

As part of its objective to expand the body of mineral information as a basis for new technology, the Bureau of Mines conducted research on the fundamental behavior exhibited by phosphate clay waste in settling ponds. A semiempirical equation used to describe the compaction of ceramic powders in a single-acting die was applied to aqueous phosphatic clay waste and attapulgite slurries. This equation, [*V = a1 e ?k1/P + a2e ? k2/P] was found to describe the compaction of an attapulgite gel and a phosphate slime gel by a moving screen. [*V] is the ratio of the compaction achieved at a given pressure, P, to the compaction achieved at a pres-sure sufficient to remove all space between particles. The constant al represents the fraction of compaction achieved at low pressure by rearrangement of floes to higher packing density, and a2 represents the fraction of compaction achieved at higher pressure resulting from removal of voids within floes. K1 and K2 are constants determined from the experimental data. Both the low-pressure and high-pressure compaction mechanisms were observed in the compaction of the clays. These two compaction mechanisms offer an explanation for the observation that impounded slimes initially dewater rapidly and then dewater at a much slower rate.

Jan 1, 1982

Determine safe practices for surface mine blasting near pressurized gas, oil, and water transmission pipelines. Background Surface mine blasters regularly have to address the issue of how blasting affects transmission pipelines that run near and sometimes through their permit areas. Regulatory approaches to blasting have ranged from no regulation at all to strict limits intended to prevent cosmetic cracks in plaster interior walls of homes, but they have not directly addressed the impact of blasting on nearby pipelines. Concerned with both productivity and safety, the mining industry and its regulators have requested guidance on safe practices for mining near pipelines. The Pipeline Research Group of the American Gas Association has sponsored studies of the effects of small close-in blasts because of vibration concerns related to the installation of new pipes into existing pipeline right-of-ways. By contrast, the recent study in which the U.S. Bureau of Mines (USBM) took part is the first addressing large-scale mining blasts.

Jan 1, 1995

Reduce costs of surface mine reclamation by improving bulldozer operating efficiency. Approach A draft power indicating system helps bulldozer operators adjust blade height and other controls for maximum load movement, by continuously indicating the rate at which work is being done. How It Works This system continuously measures both the push of the blade against the overburden, and the true ground velocity of the bulldozer. It multiplies those quantities to determine the real work rate of the machine. The system consists of a velocity sensor, a blade load sensor, processing circuits, and a work-rate indicator. The processing circuits include an analog multiplier which has an output signal representing the draft power (velocity x load = power). The draft power, or pushing power is a measurement of the work rate at that moment.

Jan 1, 1979

By W. S. Sanner

A High Splint coal was carbonized in a low-temperature, fluidized-bed sys-tem to study the effects of thermal cracking on the products of decomposition. The coal was fluidized in recycle gas at 485° to 600° C, and the products were cracked at 600°, 700°, and 800° C in a bed of fluidized coke. Yields of tar, pitch, paraffins, and olefins decreased as carbonization temperature increased. Thermal cracking of the tar vapors produced the highest tar yields at 600° C, and light oil yield increased at cracking temperatures up to 700° C. At an 800° C cracking temperature, the yield of light oil decreased.

Jan 1, 1969

Increase the recycling of critical and strategic materials by simplifying the indentification and segregation of scrap. Background Because the United States is dl-most totally dependent on imports of such critical metals as chromium, cobalt and nickel, Bureau of Mines research has been directed towards conserving these metals by increasing the recycling of the complex scrap materials that contain them. Experienced scrap sorters, using the traditional techniques of object recognition, spark tests, chemical spot tests, color, apparent density, and magnetic properties, can adequately sort a wide variety of alloy groups. However, the complex nature of new materials entering the scrap market has made sorting both more difficult and more important. Some new alloys contain so many components that separation by discrete alloys becomes a prerequisite for effective recycling. The Bureau has completed Investigations on two methods for rapidly sorting complex scrap mixtures. One method uses a combination of two low-cost instruments. The other uses a single sorting instrument. Both approaches are reported.

Jan 1, 1986

Provide an operator cab to assure protection, comfortable use of controls, and good visibility. Approach A cab which raises and lowers by pivoting about d horizontal axis was Installed on two S&S cleanup tractors and tested in two underground working mines. How It Works Hydraulic cylinders actuated by a lever inside the cab cause the cab to pivot about a horizontal axis. This action raises or lowers the cab height. The total cab excursion is 14 inches. A release valve in the hydraulic system allows the cab to lower automatically if struck by a roof load or overhead obstruction. The pivoting action of the cab is engineered so that the operator maintains comfortable use of all controls at all cab heights. The movement is such that the angular relationship of the operator's ankles With the tram and brake foot controls IS consistently within 90 to 100 degrees. Figure 1 outlines the approximate position of the operator at three cab elevations.

Jan 1, 1977

By J. F. Barkley

"In trying various coals at one of the Government power plants, comparison was made of the ash softening temperature of each coal, with the clinkering tendencies of the coal when burned in the furnace. The proximate analyses, ash softening temperature and plant reports as to clinkering were tabulated. It was desired to bring out any correlation that might appear between the ash softening temperature found in the laboratory, and the clinkering of the ash as found in the boiler furnace.Each coal used was sampled and analyzed, and the standard ash fusion test made. The clinkerring of the coal in the furnace was observed by the furnace operator. The furnace equipment consisted of the ""V"" or Murphy type of stoker with the ordinary fire-brick arch roof. With such arrangement very high furnace temperatures are apt to be produced at the ratings carried at this plant.The softening temperature of ash is defined as the temperature at which small cone of the ash, as tested in the laboratory furnace, has fused down to a spherical lump, The softening interval is the difference between the softening temperature and the temperature at which the first rounding, or bending, of the apex of the cone takes piece. The flowing interval is the difference between the softening temperature and the temperature at which the ash has reached a fluid condition as shown by spreading out over the base in a flat layer.While the analyses of the different samples of the some coal did not vary appreciably, the ash softening temperatures were not always so consistent. It will be noted from the following examples that the ash softening temperatures of different samples of the same coal differ as much as 290° F, Hence, in order to judge this property of a coal, many samples ore desirable, taken from many different shipment."

Aug 1, 1924

By Matthew J. DeMarco, Anthony T. Iannacchione

Coal bumps have presented serious mining problems in the U.S. throughout the 20th Century. Fatalities and injuries have resulted when these destructive events occur at the working face. Persistent bump problems can result in abandonment of large reserves or lead to premature mine closure. Through the years, alternative techniques such as artificial supports, extraction sequencing, destressing, pillar design changes and specific pillar retreat practices have been successfully implemented to mitigate coal mine bumps. Several techniques have evolved for room-and-pillar operations that control the way the roof rock breaks, regulating the manner in which stresses are redistributed in the mined section. Special mine layouts employed in longwall mines have also proved to be successful in safely redistributing or containing excessive loadings. However, with ever increasing production rates, greater overburdens and new mining systems, the need to evolve even more effective bump control designs will continue to challenge the U. S. coal mine industry.

By S. P. Howell, M. W. Von Bernewitz

"Introduction. The first short—flame explosives were made in the United States during the year 1902, then the mount was 11,300 pounds. In 1902 they were designated ""permissible explosives"", and were required to meet specific tests. By 1912 the total consumption thereof had increased to 24,630,000 pounds, equal to 5 per cent of the total quantity of all kinds of explosives produced in this country; while in 1922 the total was 43,429,000 Pounds, or 10 per cent of the production, and 18 per cent of the explosives used for the mining of coal.Each year the Bureau compiles statistics of explosives, one important object of this being to show the extent to which permissible explosives are replacing other classes of explosives in coal—mining operations, and the influence of such replacement in reducing the number of accidents caused by explosives in this class of mines. The consumption of permissible since 1916 has considerably exceeded the quantity of high explosives (dynamites, etc.) used in coal mines. While the increase in use of permissible is good, the replacement of other explosives therewith is not nearly as good as with be, considering the known general efficacy and safety of permissibles."

Mar 1, 1924

Provide mine operators with a quick means of identifying the effect of cutting system changes on relative dustiness at the mine face, by developing an interactive computer program for drum-type coal mining machines. Approach A program which simultaneously evaluates machine parameters, coal seam parameters and mine operator-controlled parameters for their effects on relative dustiness has been developed for use on any minicomputer using BASIC computer language. How it works The interactive computer program allows mine operators to make one or more changes at a time to their cutting system to determine how these changes affect relative dustiness of the face. Using this program, mine operators can find the optimum cutting system configuration to minimize dust using their seam conditions and their equipment specifications. The mining machine variables include: number of vane bits, number of gage bits, number of starts, vane wrap, number of end ring lines, rpm, advance rate, ton/min, percentage of time spent cutting per shift, and airflow.

Jan 1, 1986

Develop a safer, more effective, and more efficient method to control fires in abandoned coal mines and waste banks. Maintain the costs of this new method at less than or comparable to conventional AMI fire control methods. How It Works Cryogenic extinguishment of subsurface fires is a method of heat transfer. Bureau-designed injection equipment produces a pumpable slurry of liquid nitrogen and solid particles of carbon dioxide. Liquid or gaseous carbon dioxide from a pressurized tank flows to a bell-shaped nozzle where the change in pressure causes the carbon dioxide to form a granular snow. The solid carbon dioxide is mixed with liquid nitrogen. A jet pump is used to move the slurry through the delivery lines and into a simple injection probe. At injection, the nitrogen vaporizes and the carbon dioxide sublimes. This phase change produces a cold gas (-180° C) that, as it expands and moves in all directions, removes heat and also displaces oxygen. This combined process inhibits the combustion process and lowers the temperature below the reignition point. When the liquid nitrogen and solid carbon dioxide are converted to gases, the expanding gas acts like a piston, forcing warm air out of the porous bed, Although smoke and hot gases arc forced from the burning coal, generally there is no significant increase in the odor associated with burning coal.

Jan 1, 1992

By Jeffery L. Kohler, Eric R. Bauer

Prolonged exposure to noise over a period of years generally causes permanent damage to the auditory nerve and/or its sensory components. This irreversible damage, known as noise-induced hearing loss (NIHL), is the most common occupational disease in the United States today. Workers suffering from NIHL have difficulty understanding human speech and hearing other workplace cues. Despite the use of regulations and efforts by government and industry to reduce NIHL, the problem today is as prevalent as it was more - than two decades ago. Recently, the Mine Safety and Health Administration (MSHA) promulgated a new regulation that is designed to reduce NIHL in the mining industry. One of the more significant provisions is the elimination of MSHA's past practice of giving "credit" for the use of personal hearing protection, thereby reestablishing the primacy of engineering and administrative controls. However, there is a knowledge gap that is impeding the development and implementation of engineering and administrative controls. Although significant data exist on the exposure to noise by occupational code, little is known about the noise sources that contribute the most to the worker's dose. This is problematic in a workplace with multiple noise sources and workers who travel among noise sources. Yet without this knowledge, it is difficult to focus control efforts in any practical manner. Thus, it is important to characterize noise sources sufficiently well so that the sources most hazardous to hearing are identified and those conditions of exposure that are most amenable to engineering controls are pinpointed as well. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) is conducting a cross-sectional survey of noise sources and worker noise exposures in the mining industry to address this deficiency. The initial effort, conducted at a coal preparation plant and results are described in this paper. Preliminary analyses indicate that the noise levels on all floors exceeds 90 dBA in most areas, and that levels as high as 115 dBA were recorded. In addition, the one worker whose responsibility is to monitor the equipment and "house clean" the plant is slightly overexposed, even though he spends only half the shift in the plant. General information on the hearing loss problem in mining, a review of hearing protection use and noise regulations in mining, and other background materials are also presented.

By James M. Spear

The U.S. Bureau of Mines and the U.S. Geological Survey conducted a mineral survey of the Black Butte RARE (I area during the summer of 1981. The study area encompasses 17,800 acres [27.8 sq mi (7,233 ha)] along the course of the Black Butte River, 13 mi (22 km) southeast of Covello, California. No mineral deposits were identified by the U.S. Bureau of Mines during this survey. Assay results of samples taken in this area indicate only trace amounts of manganese, chromium, and nickel. No radioactive or fluorescent minerals were detected. No oil and gas, coal, or geothermal leases have been recorded for the study area.

Jan 1, 1982