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By W. M. Myers

[The principle of the application of electrolytes for deflocculation of fine materials in order that impurities may settle out, and the subsequent flocculation of the suspended particles by a different reagent, is well known and has been applied successfully to clays. Flocculation is also applied with success to ore slimes. Thus certain electrolytes, particularly alkalies added to a suspension of colloidal particles cause deflocculation so that, suspension may be-maintained indefinitely. The addition of bother electrolytes particularly acids, on the contrary produce's flocculation and the articles produce's are rapidly precipitated from suspension leaving a clear liquid above: the precipitated mass. Salts of trivalent elements such as aluminum act similarly. Due to its cheapness the double sulphate of aluminum and potassium, ordinary alum, has been used extensively for treating clays. These properties of electrolytes. and. their utilization in the commercial: preparation of clays have been described in publications of the Bureau of Mines.2]

Jan 1, 1927

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

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

Jan 1, 1990

By W. P. Diamond

It is estimated that more than 1 trillion cubic feet of methane is contained within the coals of the Mary Lee group in Jefferson, eastern Tuscaloosa, and southern Walker Counties, Ala. Most of this methane will be encountered by mining. Coals of the Mary Lee group are presently being mined at depths exceeding 1,000 feet and will in the near future be mined at even greater depths, where the problem of methane gas affecting the mining operations will be acute. It is calculated that approximately 90 pct of the methane is at depths greater than 1,000 feet, and over half of the gas is contained within only 12 pct of the study area which is under more than 1,500 feet of over-burden. Degasification in advance of mining will increase mine safety, reduce ventilation expenditures, increase productivity, provide an additional energy source, and make it possible to mine parts of deep coalbeds that probably could not otherwise be mined.

Jan 1, 1976

By H. F. Weaver

The 18th National First-Aid and Mine Rescue Contest was held in the Memorial Auditorium, Buffalo, New Vork, October 5, 6, and 7, 1959. The meet was sponsored by the Federal Bureau of Mines and the Joseph A. Holmes Safety Association, in cooperation with State mine inspection agencies, management and labor of the mineral extractive industries, and other safety minded groups. The Arrangements Committee, as authorized by the General Committee, made a11 the necessary arrangements for conducting the 1959 contest. Members of the Arrangements Committee were: Harry Gandy, Jr. (chairman), National Coal Association; James B. Benson, Southern Coal Producers' Association; Charles Ferguson, United Mine Workers of America; George C. Trevorrow, Bituminous Coal Operators' Association; and James Westfield, Federal Bureau of Mines.

Jan 1, 1960

By A. Wahab Khair, N. P. Reddy

"Abstract. This paper attempts to characterize coal breakage due to the action of a continuous miner. Coal blocks with an approximate dimension of 45.7 cm x 38.1 cm x 15.2 cm (18 in. x 15 in. x 6 in.) were first subjected to confining pressures equivalent to in-situ conditions. Then the blocks were cut along the face/butt cleat direction by the cutting head of a specially designed unique automated rotary coal cutting simulator (ARCCS), simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-sit and operating parameters a number of other para¬meters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted by using a sonic technique. At the end of each experiment, the coal fragments were collected in bags using a vacuum cleaner. These fragments were then sieved for size distribution analysis.INTRODUCTIONThe Federal Coal Mine Health and Safety Act of 1969 was enacted to emphasize to coal operators that the airborne respirable dust should not exceed 2 mg/m3, thus reducing the incidence of coal workers pneumoconiosis.Dust control techniques such as conventional water sprays and dust collectors are only partially effective and require additional equipment expenditures. A more authentic approach would be to reduce respirable dust at the source the continuous mining machine cutting head, where the fragmentation process occurs. Improving the fragmentation process by characterizing the coal breakage will not only reduce respirable dust at the face, but it will also decrease the amount of respirable dust that is liberated during the secondary handling.Fragmentation of coal can be expressed as a function of three major groups of parameters; namely, 1) coal properties, 2) in-situ conditions and 3) operating parameters. This paper deals with the characterization of coal breakage along both face/butt cleat direction as a function of machine operating parameters such as rate of advance, angle of attack, bit configuration, bit lacing (spacing and pattern) and bit speed at various equivalent in-situ pressures."

Mar 1, 1989

By J. P. Coughlin

The U.S. Bureau of Mines has developed a monitoring system that acquires and analyzes data for use in determining the conditions that may precede mountain bumps in coal mines. Based on a UNIX workstation linked to an array of geophones in a working longwall operation, the system captures complete waveforms of microseismic events and simultaneously obtains continuous samples of the voltage levels of each geophone. Event rates and locations are calculated and displayed in real time on the UNIX workstation, which is situated in an underground instrumentation room. These results also are transmitted from the workstation to a display computer near the longwall face. The system runs continuously and has the capability to acquire, analyze, display, and archive microseismic (transient) data and single point data, such as closure and pressure changes, simultaneously.

Jan 1, 1993

By John C. Machisak

Statistical data on injuries in the metal and nonmetal industry of the United States first became available to the Bureau of Mines by collecting reports from the operators for the calendar year 1911. Since then reports have been collected annually. The present bulletin, covering the calendar year 1954, is the 31st publication (1933-34 was published as Bulletin 398) containing statistical data on injuries at metal and nonmetal mines and related plants, and it 1s the first such bulletin to be published since 1942. The last publication was Bulletin 461, Metal and Nonmetal-Mine Accidents in the United States, 1942. The unpublished statistics for 1943-53 may be found in the Appendix of this bulletin. The Bureau of Mines is authorized to collect data on injuries and related employment at metal and nonmetal mines, but there is no Federal law that compels operators to submit such information. Therefore, all materials submitted are voluntary responses to the Bureau's requests for information. The figures presented herein may not be complete for the entire industry, nevertheless, every effort has been made to make them so, and the data given are believed to be representative of the hazards to which metal and nonmetal workers are exposed. Moreover, the figures are comparable as between States-which is significant in view of the lack of uniformity among the States as regards classes of plants covered by State laws, classes of injuries covered by State reports, and other factors that tend to make it impracticable or impossible to compare the injury experience of one State with that of another or comprehend the relative importance of the various causes of injuries in the industry as a whole.

Jan 1, 1957

By R. C. Anderberg, F. J. Caervenyak, F. J. Frattali, H. J. Kandiner, R. A. Brown

"INTRODUCTION Considerable interest was shown .prior to and during World War II in the winning of metallurgical-grade alumina from anorthosite, kaolin, siliceous bauxites, diasporic clays, and other aluminum-bearing ores. Laboratory and pilot-plant investigations were made on many of these ores by the Bureau of Mines, and a series of reports on them is being prepared. This report covers the tests made on the application of the lime-soda-sinter process to anorthosite, which is a mixture of albite, NaAlS1308, and anorthite, CaAl2Si208. Extensive deposits of anorthosite occur in the Laramie Range in Wyoming and extend into Colorado; other deposits are found in New York, with outcroppings appearing in Vermont, Maine, and Labrador.Anorthosito can not be treated by the Bayer process for the production of metallurgical-grade alumina, because excessive losses of soda and alumina occur from the formation of sodium-aluminum silicate due to the large amount (50 percent) of silica in the ore.RESULTS OF INVESTIGATIONSSmall-scale laboratory tests supplemented by pilot-plant runs have demonstrated that the alunina and soda occurring in the Wyoming anorthosite from the Laramie Range can be extracted and recovered satisfactorily by the lime-soda process. It has been shown that liquors containing approximately 95 gram of A1203 per liter can be consistently produced at Na20:A1203 ratios from 1.75 to 2.27, and that these liquors can readily be desilicated and carbonated to yield high-grade alumina trihydrate of quality comparable to that essential for cell-grade alumina. The optimum results were obtained with Na20:A1203 mol ratio of 1.03 and Ca0:Si02 ratio of 2.14 in the sinter when calcined at an average temperature of 2,444ºF. for 25 minutes."

Nov 1, 1947

By Oliver Bowles

The conservation of fuel became a critical problem during the recent war, particularly in the East. Fuel-oil supplies were short, the demands for coal increased, and householders were called upon to reduce the temper- atures in their homes. Home owners were urged to employ every means avail- able to reduce fuel consumption, the most important of which was to insulate their dwellings. The Bureau of Mines, United States Department of the In- terior, took steps to promote the conservation of fuel by issuing a report3/ on home insulation which has been widely circulated. The American populace responded patriotically to the requests of various Government agencies for voluntary conservation of fuels; they accepted cheerfully the restrictions imposed, the crisis was weathered, and with termination of hostilities the unhappy situation was relieved. Fuel conservation, however, is not merely a war emergency problem; it is a continuous, ever present issue. Coal and petroleum resources are ir- replaceable assets, and when fuel is burned it is exhausted - there is no scrap recovery. Fortunately, the United States has been richly endowed with mineral fuels; but population is growing, industrial demands for fuel are increasing, and mines and oil wells are becoming deeper and more costly to operate. For the sake of generations to come all national resources, particularly irreplaceable fuels, should be conserved. A long step in the direction of fuel conservation is the general rec- ognition that insulation is an essential element of dwelling construction. Fortunately, when the home owner takes measures to conserve fuel, he is not called upon to make purely unselfish (altruistic) sacrifices to advance the general welfare; he has the added incentives of saving money and promoting more comfortable living in his own home.

Oct 1, 1946

By H. P. LeVan

Research was conducted to examine the feasibility of extracting manganese from Georgia umber ore by a three-stage continuous sulfuric acid-ferrous sulfate pickle liquor leaching process. A continuous cyclic process for treating the umber was operated successfully, using a synthetic solution simulating a ferrous sulfate fortified anolyte solution discharged from a manganese electrolytic cell as the leaching medium. Leaching efficiency based on removal of the manganese from the ore ranged from 83 to 89 percent for all systems tested.

Jan 1, 1965

By J. E. Tiffany, Z. C. Gaugler

In presenting this list of permissible explosives and blasting devices , the Bureau of Mines desires to call attention to pages 16 and 23 , outlining the conditions in use under which , and only under which , the explosive or blasting device is permissible . In view of publications recounting trade practice favoring the use of a blasting device without stemming , particular emphasis is placed upon condition 4 on page lt and condition 2 on page 23 .. An explosive or a blasting device enumerated in the permissible lists of this Bureau is not permissible in use unless it is properly confined with clay or other incombustible stemming .

Dec 1, 1943

By John C. Gagliardi

The size and complexity of modern surface haulage trucks has resulted in an increased reliance upon sensors and electronic-based instrumentation for safe and efficient operation. Design engineers need accurate information about the equipment vibration environment to efficiently and effectively build components for installation on mobile mining equipment capable of withstanding the mine environment. Examples of such components include backup alarms, communication equipment, microprocessor-based controllers, and a wide variety of sensors. Unfortunately, this information is not available to the majority of both original equipment and aftermarket equipment manufacturers. To address this problem, the U.S. Bureau of Mines performed field vibration measurements on a variety of surface mining haulage trucks. The vibration measurements were then analyzed and test specifications were developed in the form of envelopes. In conjunction with test specifications, recommendations to aid manufacturers in implementing a vibration environment test program have been included with an illustrative example.

Jan 1, 2010

By B. W. Gandrud, G. T. Bator

The recent introduction of small coal jigs in Alabama to meet the needs of truck - mine operators for cheap and economical cleaning equipment marks another step in Alabama's pioneering record in the mechanical cleaning and preparation of coal . During the past 4 or 5 years a number of these small jigs , with capacity of 5 to 10 tons per hour , have been installed at Alabama truck mines and at a few truck mines in Illinois , Tennessee , and Pennsylvania . Most of the installations have been at mines that specialize in the production of domestic , stoker coal . This report describes three models of small jigs and includes performance data obtained recently on one of the models by the Bureau of Mines, United States Department of the Interior , in cooperation with the University of Alabama, Tuscaloosa , Ala . , for the purpose of comparing it with fullsize jigs on a performance basis . With literally hundreds of truck mines now in operation throughout the country , it has been assumed in preparing this report that there is widespread interest in the availability of small - scale inexpensive preparation equipment for use at such mines in the production of steam and domestic coal and in some instances coal for manufacture of coke . Practically none of the coal from Alabama truck mines is scld to coke - oven plants ; but in some sections of the country truck mines supply a considerable amount of coking coal, and the use of small, inexpensive washers at some of them might be very advantageous during the present war emergency from the standpoint of increasing pig - iron production through improvements in coke quality .

Aug 1, 1943

By W. E. Lamont, R. E. Perry, I. L. Feld

The Bureau of Mines conducted research to determine the conditions required to sinter a pyrrhotite calcine into a product suitable for iron blast furnace feed . The calcine , a fine - grained iron oxide produced by roasting sulfide flotation concentrate , analyzed about 60 percent iron and 1 percent sulfur . Sintering of the calcine without prior pelletization was not successful whereas firing of preformed calcine charges yielded acceptable sinter products . Batch tests were made to study the effect of the following variables on the sinter quality : Size of green pellets in the charge , quantity and type of internal carbonaceous fuel used , depth of sinter bed , moisture content of the charge , flux additions , and binder additions . The batch and continuous sinter tests showed that minus 1 / 4 - inch pellets prepared from a mixture of the calcine , coke , dolomite , and water gave sinter cakes analyzing 57 to 61 percent iron and 0.05 to 0.02 percent sulfur .

Dec 1, 1963

By Robert A. Jankowski

"Following passage of the Coal Mine Health and Safety Act of 1969 (Public Law 911173), the Bureau of Mines initiated a research program aimed at controlling respirable dust exposures of coal mine workers. Respirable dust is the dust that gets into, and interacts with, the lungs of those who inhale it. It has long been recognized as a severe health hazard to mine workers. This program has been implemented by a team effort consisting of the Bureau's in-house capabilities, the Generic Center for Respirable Dust, and contractors, as necessary. Over the years, Bureau research has addressed principally three areas:o Compliance with the Federal 2.0 mg/m3 dust standard (1970-76).o Dust control for longwall mining (1976-1983).o More stringent respirable dust standards due to quartz dust (1983-1987).In addition, fundamental studies have been conducted by the Generic Center for Respirable Dust, with emphasis on penetration of dust into the lung. Accomplishments have been significant, but problems remain, as noted later.The Coal Mine Health and Safety Act of 1969, established a 2.0 mg/m3 dust standard for all coal mining operations, underground as well as surface. At the time of enactment of this legislation, the industry was averaging approximately 4.0 mg/m3. The Bureau of Mines respirable dust research program played a significant role in identifying and developing effective technology to allow better compliance with this new standard, thanks to industry implementation and Federal enforcement."

Nov 1, 1988

By Joseph Cervik

This Bureau of Mines report deals with water infusion of coalbeds, which can control methane emission at face areas during developmental mining and which may sometimes suppress dust. Studies show that water infused into the coalbed flows through the fracture system and displaces the methane in the fractures and prevents migration from the solid coal. Displaced gas migrates away from the face area that has been water infused and enters the return ventilation airways. A gradual decrease in methane emission is observed from the start of infusion until the infused zone is mined through. Depending on the permeability of the coalbed, infusion pressures ranged from 300 to 2,200 lb/in2. Face emissions in the Upper Kittanning coalbed were reduced by 89 pet; reductions of 38 to 79 pet were measured in the Pittsburgh coalbed depending on the relationship between the face cleat direction and mining direction. Respirable dust levels were reduced by about 75 pct on a longwall section in the Pocahontas No.3 coalbed and by about 50 pct on a development section in the Upper Kittanning coalbed, but no statistically reliable reduction was found in the respirable dust levels in the Pittsburgh coalbed.

Jan 1, 1977

By William C. Larson

This Bureau of Mines report discusses uranium in situ leach mining in the United States to acquaint the public with an overview of this emerging mining technology. This report is not intended to be a technical discussion of the subject matter, but rather should be used as a reference source for information on in situ leaching. A list of in situ leaching publications is included as well as engineering data tables for almost all of the active pilot-scale and commercial uranium in situ leaching operators. These tables represent a first attempt at consolidating operational data in one source, on a regional basis. Additional information is given that discusses the current Bureau of Mines uranium in situ leaching research program. Also included is a listing of various State and Federal permitting agencies, and a summary of the current uranium in situ leaching operators. Finally, a glossary of terms has been added, listing some of the more common terms used in uranium in situ leach mining.

Jan 1, 1978

By Jeffrey Shawn Peterson

Among underground coal miners, hearing loss remains one of the most common occupational illnesses. In response, the National Institute for Occupational Safety and Health (NIOSH) conducts research to reduce the noise emission of various underground coal mining equipment, an example of which is a roof bolting machine (RBM). After the removal of coal or rock, the remaining strata may be subject to fall, either from overhead (the roof) or from the side (the rib). One method used in underground coal-mines to prevent failures requires the installation of roof bolts. The roof bolting machine operator trams the machine to the required location, drills a hole into the strata, and then installs a roof bolt, supporting the roof or the rib, as the case may be. Field studies support the premise that, on average, drilling noise is the loudest noise that a roof bolting machine operator would be exposed to and contributes significantly to the operators? noise exposure. NIOSH has determined that the drill steel radiates a significant amount of noise during drilling. NIOSH is developing bit and chuck isolators to reduce vibration, and thus noise radiation of the drill steel, with the longer-term goal of reducing roof bolting machine operator noise exposure. Laboratory testing has shown that operator ear sound pressure levels may be reduced by 3 to 7 dB(A), depending upon the test configuration and drilling media.

Jan 1, 2009

By Charles Sabine

The 27,960-acre Newberry Mountains Wilderness Study Area (WSA) is located in the Mojave Desert, 17 miles east-southeast of Barstow. In 1983, the U.S. Bureau of Mines, in conjunction with the U.S. Geological Survey, investigated mineral resources of the area as part of the wilderness review process. The Newberry Mountains are underlain by Paleozoic metamorphic rocks, Mesozoic plutonic rocks, and Tertiary volcanic rocks. Eleven mines and prospects were examined. Of the seven sites within the WSA, only the Northrup Prospect is mineralized. Only a few tons of manganese-bearing rock, containing 49% manganese oxide (MnO), are exposed, but exploration may disclose larger deposits. The Azucar Mine, a past producer of gold, is the only site examined outside the area that appears mineralized. Sample data from quartz veins exposed at the surface do not indicate that resources are present; however, the occurrence could not be fully evaluated because underground workings were not accessible. Sand, gravel, and stone are plentiful in the WSA, but alternate sources outside the WSA are available.

Jan 1, 1985

By D. J. Parker

Owing to its flexibility, convenience, economy, ands availability, electric power is peculiarly adapted to the needs of the coal -mining industry. Because of such obvious advantages, the application of electricity has in recent years become more and more extensive and is now a most important factor in the Nation's coal prediction. With the introduction of this type of power into coal mines certain new, specific, and well-recognized hazards resulted. The question arises, therefore: Has the industry met these hazards squarely and. effectively? With respect to some individual companies, the answer happily is in the affirmative; with respect to the industry as a whole, there is much room for improvement.

Jan 1, 1933