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By J. C. Franklin

The Bureau of Mines substantially reduced shale degradation in a coal mine by two spray coat applications of a water-base epoxy sealant. More than 12,700 square feet of passageways were treated, and in 18 months only one failure occurred. This failure was due to improper spray application, Material costs averaged 13 cents per square foot, and labor costs were 7 cents per square foot. Labor included moving all materials into the mine, the setup time for each of the areas coated, and application of coatings.

Jan 1, 1977

This dictionary is published by the Bureau of Mines as a contribution to the mining and mineral literature in the belief that it will fill a recognized need. Several attempts have been made over the years to revise Albert Fay's Glossary of the Mining and Mineral Industry which first appeared in December of 1918. Frank L. Hess of the Bureau of Mines worked on a revision, but his untimely death prevented its completion. Subsequently, the writer was employed to compile and edit this dictionary in cooperation with the technical staff of the Bureau of Mines. Fay's glossary contained about 18,000 terms with 27,000 definitions; the present compilation contains about 55,000 terms with approximately 150,000 definitions. These terms are of both a technical and local nature, and they apply to metal mining, coal mining, quarrying, geology, metallurgy, ceramics and clays, glassmaking, minerals and mineralogy, and general terminology. Petroleum, natural gas, and legal mining terminology, unless of a general nature, has been excluded, as has been foreign terminology where there is an English equivalent. Several thousand Spanish-American mining terms that appeared in Fay's compilation have been removed to make way for the thousands of new English terms that have evolved over the years. Those Spanish-American and Mexican terms still used in the Southwestern United States have been retained.

Jan 1, 1968

By J. J. Hoeppner

Lignite samples were collected so as to be widely representative of the extensive deposits in the western north-central area. These were carbonized at temperatures ranging from 450° to 550° C., according, to a standardized procedure. In general, product yields varied; extremes obtained on selected samples show char recoveries on the moisture- and ash-free basis as 56.7 percent for slack lignite or "leonardite" to 80.8 percent for a concentrate of the fusain component from a typical face sample; normal lignite samples averaged approximately 70 percent. Tar-plus-light-oil yields ranged from 3.3 percent for the fusain concentrate to 11.0 percent for a normal sample, averaging approximately 8 percent; gas recoveries varied more widely both in yield and in composition, ranging, from 10.0 percent to 27.7 percent, the latter being from leonardite and quite high in carbon dioxide. Sampling was conducted with the view of representing, as nearly as possible, all beds delineated by Brant (2);4/ many are necessarily missing since collection was confined largely to worked deposits. Data presented in this report indicate a general uniformity of North-Central lignite in respect to low-temperature carbonization, with a few possible exceptions of a local nature. When processed according to the indicated conditions, maximum tar yield may be realized with minimum loss of recoverable heating value of the original coal. Natural weathering of lignite, however, does affect tar yield adversely and should be held to a practical minimum in any commercial operation.

Jan 1, 1956

By O. C. Blade

"INTRODUCTION This report on the properties of aviation gasolines and aviation jet fuels produced in the United States during 1952 was mode under a co¬operative agreement between the American Petroleum Institute and the Bureau of Mines of the United States Department of the Interior.Analytical data are presented for 94 samples of aviation gasoline which include for the first time in this series of reports, data on five samples of grade 108/135 aviation fuel. Data also are given for 34 samples of aviation jet fuel. The analyses were made on samples typical of the manufacturers' production in their laboratories and the results sub¬mitted to the Bureau of Mines for compilation. The products of 20 manufacturers of aviation gasolines and of 16 producers of aviation jet fuels are represented.SUMMARYA comparison of certain properties of the commercial aviation gasolines produced in the United States during 1950, 1951, and 1952 is presented in table 1, the 1952 data being average values from tables 3 through 7 of the present report. Trends in certain characteristics of these fuels may be seen in figures 1 through 5 which also indicate the minimum and maximum values. As may be observed, the properties of commercial aviation gasolines have not varied greatly during recent years. A list of aviation-fuel survey reports published by the Bureau of Mines is given on page 7.Table 2 presents a summary of data from table 8 and compares properties of aviation jet fuels of 1952 with summarized data on jet fuels of October 1951."

May 1, 1953

By W. W. Adams

Coal mining in the United States established a good safety record in 1939. The death and injury rates per man-hour of exposure to risk were favorable compared with most previous years, and the number of persons killed or injured in proportion to the quantity of coal mined was also lower than in any other year for which figures are available. Moreover, productivity per man-hour was higher than ever before. The number of man-hours of work performed increased 9 percent over 1938, but there was a slight decrease in the number of men employed. Reports from operating companies showed 539,375 men employed during the year, and the period of operation averaged 179 workdays per man. Man-hours of work numbered more than 678 million. Accidents to the workers resulted in 1,078 fatalities and 54,015 nonfatal disabling injuries, causing disability of the employee for more than the remainder of the clay on which the accident occurred. For each million man-hours of exposure of the employees to mining hazards the fatality rate was 1.59 compared with 1.78 for 1938, and the injury rate was 79.65 compared with 82.61 for 1938. Production of coal averaged 0.661 ton per man-hour compared with 0.637 ton in 1938. The weighted average length of the workday was 7.03 hours or virtually the same as the previous year's average of 7.04 hours. Measured in man-hours, the average period of employment per man was 1,257 hours in 1939 and 1,147 hours in 1938.

Jan 1, 1942

By F. Sillers, R. T. C. Rasmussen

"INTRODUCTION This is the fourth report of investigations dealing with the cooperative tests between the Bureau of Mines and industry on the use of electrolytic manganese in steelmaking. The first report dealt with the use of electrolytic manganese in the manufacture of stainless steel 3/ the second with its use in acid electric steel practice, 4/ and the third with its use in low-carbon basic open-hearth steelmaking. 2/ A résumé of those investigations E7 appeared in the magazine STEEL. 5/ The present report deals with the use of electrolytic manganese in the manufacture of four types of stainless steel and the new Timken 16-25-6 alloy. The Bureau of Mines supplied The Timken Roller Bearing Co. with 62,000 pounds of electrolytic manganese for use in the tests.The electrolytic manganese was produced at the Bureau of Mines pilot plant, Boulder City, Nev., by the process developed by the Bureau and described in Bulletin 463, Operation of Electrolytic Manganese Pilot Plant, Boulder City, Nev., by J. H. Jacobs. J. W. Hunter, W. H. Yarroll, P. E. Churchward, R. G. Knickerbocker, R. W. Lewis, H.A. Heller, and J. H. Linck. The workcarried out under the direction of R. S. Dean, formerly assistant director, Bureau of Mines, and R. G. Knickerbocker, formerly chief, metallurgical branch, as part of a long-range program involving the development, manufacture, and use of manganese from domestic ores. Preliminary arrangements for the plant tests were made by the late A. A. Dow. 7/"

Jun 1, 1947

By C. Thomas Hillman

The practical concern of economic minability of large, high-grade manganese nodule deposits in the northeast Pacific Ocean is addressed in this Bureau of Mines report. Principal objectives are to (1) estimate tonnage and grade of deposits with significant potential and (2) describe and estimate profitability of operations designed to mine and process deposits with greatest apparent potential. Analysis of data from over 800 ship stations identified three areas for detailed study. Average metal contents of these areas range from 1.30 to 1.45 wt pet nickel, 1.00 to 1.24 wt pct copper, 0.21 to 0.26 wt pct cobalt, and 26.8 to 27.8 wt pct manganese. Estimated recoverable nodule resources are 67.0, 66.9, and 148.8 million dry metric tons (t). A system to mine, transport, and process nodules from the three sites is described and costed. Although hypothetical, the system utilizes hydraulic mining and Cuprion (Kennecott) processing, which have been successfully tested at pilot scale. Nickel, copper, and cobalt are the three primary products, but ferromanganese is a considered option. Estimated capital requirements are approximately $1.5 to $1.7 billion for three-metal production. If ferromanganese were recovered, an additional investment of about $130 million would be required. Operating costs range from $71 to $83 per dry metric ton of nodules without manganese, and from $103 to $123 per dry metric ton with ferromanganese. Discounted cash flow analyses predict low returns, ranging from 2.7 to 5.2 pct with ferromanganese and from 4.1 to 6.0 pct without.

Jan 1, 1983

By R. Blickensderfer

Test equipment that simulated frictional impacts between coal-cutter bits and mineral inclusions at a coal face during operation of a continuous coal mining machine was used by the Bureau of Mines in the laboratory to study the incendivity of impacts between various rocks, metals, and hard-metal alloys in an explosive mixture of air-7 pct natural gas. Quartzitic sandstone was found to be the most incendive of several rocks tested. Limestone concretions from a coal seam, known locally as "sulfur balls," sparked furiously but were not incendive. Among the metals tested, the type of steel used in commercial coal-cutter tools was the most incendive material tested. A l7-4PH stainless steel was less incendive and appears to be the most promising high-strength steel alloy, reasonably economical, for use in coal-cutter bits. Some hard-metal alloys, primarily titanium and zirconium diboride composites, were also evaluated as possible replacements for the conventional cobalt-bonded tungsten carbide used in the tip of coal-cutter bits. The metal-bonded diborides were generally less inc endive but more brittle than the conventional tungsten carbide. Carbonitride coatings on tool bits were also tested but found to have no advantage. The source of ignition during frictional impact between metal and rock was studied. Immediately after impact, a yellow flash was observed and a smear of metal near its melting point occurred on the rock. This hotspot on the rock, rather than the yellow flash or sparks or metal fragments, was observed to be the cause of the ignition.

Jan 1, 1974

By W. S. Wright, A. W. Tolonen

"INTRODUCTION The Mount Andrew iron deposit on Kasaan Peninsula, Prince of Wales Island, Southeastern Alaska, was examined in August 1942 by an engineer 4/ of the Bureau of Mines accompanied by geologists 5/ of the Federal Geological Survey. From October 20 to 27, 1942, two engineers 6/ of the Bureau of Mines made a further preliminary examination and took three large samples of magnetite and magnetite-copper ore for metallurgical testing. During the stunner of 1942 an investigation of the Mount Andrew-Stevenson-Mamie area, including topographic and geologic mapping and a magnetic survey, was made by geologist 7/ the Federal Geologically Survey. On May 31 and June 2, 1943, two Bureau of Mines engineers 8/ conducted a preliminary examination in which special attention was directed to trails, camp, and drill sites. They were accompanied on May 31 by L. A. Warner of the Geological Survey.During the period from September 1943 through September 1944 Bureau of Mines engineers 9/ completed a thorough investigation which included trenching, core drilling, and sampling. A Federal Geological Survey representative 10/ examined all trenches and cores for geological data.LOCATION AND ACCESSIBILITYThe deposit is situated at latitude 55º 31' N. and longitude 132º 18' W. on the north side of Kasaan Bay on Prince of Wales Island, Southeastern Alaska. The general location is shown on figures 1 and 2. The deposit is 5 miles southwest of the village of Kasaan and by water, 27 miles northwest of Ketchikan; the main tunnel portal is 7/8 mile north of the Mount Andrew landing on Kassan Bay."

Nov 1, 1947

By Jerry J. Gray

Transportation charges for mineral commodity movements in western Oregon and western Washington were determined mainly by a stratified random sample canvass of producers. Total 1965 mineral production value for this area was $53.3 million; the cost or charge to move this production from the mine to the consumer or to the point of consumption was determined to be an additional $38.7 million. Thirty seven companies were contacted as a sample out of a total population of 349; the statistically expanded sample production value deviated 3.6 percent from that obtained by the Bureau's annual canvass. The agreement between the sample results and the canvass totals demonstrated the effectiveness of the sampling method for obtaining data with a predesigned level of accuracy. For comparison, the north-central Idaho and western Montana area was studied, A random sample experiment was designed, but because of the dominance of a few major companies, a random sample technique would have required more visits to producers than if only the larger firms were contacted. Eighty-four percent of the 1966 mineral value ($198.6 million) was accounted for by interviewing 27 firms out of a total population of 199. Total transportation costs or charges for the area were $26.7 million. The significant difference observed between the relationship of minerals production value and transport charges between the two areas investigated can be attributed to the difference in the minerals produced. The western Oregon and western Washington region is a nonmetals-producing area as opposed to the predominance of metals production in the Idaho-Montana region.

Jan 1, 1968

By David K. Denton

There are no active mines in the Mt. Eddy RARE II area. Chromite, gold, and stone prospects were examined. The RARE II area contains no identified mineral resources; however, a sample of a 260 ton occurrence contained 38.1 percent chromium oxide (Cr203) at the Ratero Prospect (fig. 1, no. 3), which has low potential for chromium resources. The Johnson Mine (fig. 1, no. 6) produced a small unrecorded amount of chromite during World War IT, but only a low potential exists for chromium resources. A low potential exists for gold resources at the Half Century Prospect (fig. 1, no. 2). At a borrow pit northwest of the study area (fig. 1, no. 1), sheared serpentinite is quarried for road metal; similar rock occurs in the RARE II area, but better material is more readily available elsewhere. Sand and gravel occurrences are too inaccessible and distant from markets to be considered resources. Mineral fuels and geothermal resources were not evaluated during this Bureau of Mines study. There currently are three unpatented lode mining claims in the study area. INTRODUCTION The Mt. Eddy RARE II area is 7 air-mi west of Mt. Shasta City, California, and straddles the Siskiyou-Trinity county line. The roadless area includes 7,200 acres of rugged, glacially carved, ridges and drainages which comprise Mt. Eddy. Elevations vary from 6,000 ft along the North Fork Sacramento River to 9,025 ft at the summit of Mt. Eddy. The area is covered with conifer forest below 8,000 ft elevation.

Jan 1, 1983

By Carlton E. Brown

Impinger dust-counting methods are used by industrial hygienists for determining the number concentration of unhygienic siliceous dusts in industrial atmospheres. Various statements have been made regarding the size of the smallest particles revealed by the microscopic employed in such determinations. Published data on the subject are quite limited. This report presents information on the size of the smallest particles revealed by light-field and dark-field techniques applied to impinger and electric precipitator samples collected from experimentally established aerosols of silica dust and bituminous-coal dust. Size distribution and number concentration of particles of the various sizes in the aerosols were determined from samples collected by thermal precipitation simultaneously with the impinger and electric precipitator samples. The size of the smallest silica and bituminous-coal dust particles determined in the light-field counting method used was about 1./1, . There was relatively little variation in the values from 8 impinger and 33 A.-C. precipitator samples of silica dust and 13 impinger and 13 A.-C. precipitator samples of coal dust. The coefficients of variation of the values from the four sets of determinations were low, ranging from ± 7.7 to t 10 percent. This size of 1,14 is close to the limit of resolution of the microscopic method used and to various previously suggested values. The size of the particles determined in the dark-field counting method used was smaller than the size (about 0.28A ) of the smallest particles determined in the light-field, oil-immersion method used for the thermal precipitator samples.

Jan 1, 1951

By Charles L. Kimbell

In 1990, the aggregate value of world international export trade in mineral commodities was estimated at more than $64 billion in current (1990) dollars, about 8.4% higher than that in 1989, but still 8.7% below the record high set in 1980. Table 8 provides a data series for the estimated value of world export trade in all mineral commodities from 1979 through 1990, as well as a breakdown of this total into fuel and nonfuel commodities. It is noteworthy that for this 1990 edition, trade data for the year of review were available in time for inclusion, whereas in previous editions, the latest available global trade data were for the year prior to the year of review. Hence, as regards trade, this edition of Minerals in the World Economy updates the 1989 edition by 2 years rather than by only 1. For this reason, it is appropriate to note that the 1989 global total value for inter-national export trade in mineral commodities was almost $596 billion, 11.1 % above the revised 1988 level of more than $536 billion, both figures expressed in current dollars for the appropriate year. Despite the considerable increase in the dollar value of mineral commodity exports, their share of total export merchandise trade declined to 19.1 % in 1990 from 19.7% in 1989. At 19.1%, this share was very near the recent year record low of 19.0% reached in 1988. The year 1990 was the fourth in a row in which the total value of world mineral commodity export trade increased.

Jan 1, 1993

By D. E. Shanks

The Bureau of Mines investigated the effects of HCI concentration and solution temperature on the solubility and crystal form of the chlorides of Co, Mn, and Ni when sparged with HCI gas at temperatures of 20°, 40°, and 60° C. Increasing HCI concentration in solution caused the chlo-rides of Co, Mn, and Ni to crystallize (salt out) because of the common ion effect. The salting-out crystallization was most effective for NiCI2, which had a solubility of 0.7 pct at 20° C and maximum HCI concentration. COCl2 salted out to a minimum solubility of 9.4 pct at 20° C and 22 pct HCI concentration and increased in solubility at greater HCI concentrations because of the formation of chloride complexes. MnCl2 was intermediate in behavior. The effect of temperature on solubility was greatest for CoCl2 and least for NiCI2, 15 and 7 pct change, respectively, over the temperature range of 20° to 60° C. The salted-out chlorides of cobalt and nickel formed the hexahydrates and those of manganese formed the tetrahydrate in saturated metal chlo-ride solutions at 20° C and low concentrations of HCI. Increasing the temperature or the HCI concentration caused a 108s in waters of hydra-tion. At 60° C, the salted-out crystals of NiCl2 formed the tetrahydrate in HCI concentrations up to 18 pct and the dihydrate at higher concentrations, while cobalt and manganese chlorides formed the dihydrates, even in water.

Jan 1, 1985

By John E. Shelton

Flotation tests were conducted on two samples of copper-nickel-bearing ore from the Harriman area near Rockport, Maine. The samples were taken by Roland F. Beers, Inc., for tests in cooperation with the Federal Bureau of Mines. One sample, analyzing 0.38 percent copper and 0.71 percent nickel, was essentially a disseminated pyrrhotite in hypersthene. Pentlandite, chalcopyrite, pyrite, and millerite were intimately associated with the pyrrhotite. Locked series flotation tests on this sample showed that 87.4 and 73.4 percent of the copper and nickel, respectively, could be recovered in a bulk concentrate that analyzed 3.47 percent copper and 5.34 percent nickel. The copper-and nickel-bearing minerals were collected with sulfhydric collectors in an alkaline circuit. Cleaning the concentrate three times with the addition of pH regulators was sufficient to attain the previously stated grades. The second sample had analyses of 0.31 percent copper and 0.85 percent nickel; talc and hypersthene were the main gangue minerals. Bulk sulfide flotation, made while depressing the talc, resulted in a concentrate that analyzed 2.33 percent copper and 4.70 percent nickel at recoveries of 70.0 and 54.4 percent, respectively. Flotation of the talc followed by bulk sulfide flotation resulted in a nickel content greater than 5 percent. A locked-series test showed that 60.7 percent of the copper and 73.7 percent of the nickel could be recovered at grades of 1.29 and 4.85 percent, respectively.

Jan 1, 1961

By Oliver C. Ralston, Foster Fraas

The electrostatic separation of solids utilizes the forces exerted when electrically charged particles of the solids are present in an electric field . The charges may be acquired by various means (5) , and when the acquisition or loss of charge depends on the property of the particle , separation can be obtained between particles having different properties . A property commonly utilized in present - day separators in conductance . Charging also may be accomplished by bringing the particles into intimate contact with various surfaces . This is sometimes described as a " frictional electrical effect. The charge , or specifically the polarity of the charge , in this latter case evidently depends on the property known as the contact potential , as has been explained in the discussion of a paper (7) and in several other papers (10) . Separation by this method is accomplished in two steps - a charging step , in which the particles are brought into intimate contact with an electrification surface , and a separation step , in which the charged particles are separated in an intense electric field . Descriptions of such methods may be found in the literature (2) , (7) , ( 8) . Even as early as 1909 , Blake and Morscher (2) described the charging of particles by intimate contact followed by separation in an electric field . They also state that the polarity of the electrical charge acquired by the particles depends on their composition . O'Brien ( 8) presented several designs of apparatus . He obtained electrification by means of a wiping action , either on inclined plates or in rotating cups , in which a centrifugal force was imparted to the particles .

Nov 1, 1942

By V. F. Parry, J. B. Goodman, W. S. Landers

"This investigation was conducted: under the direction of A.C. Fieldner, chief, Fuel and Explosives Branch, Bureau of Mines, Washington, D. C. The following members of a Technical .advisory Committee were helpful in advancing the investigation: L. C. Harrington, dean, College of Engineering, University of North Dakota; D. F. Pane, president, Sheridan-Wyoming Coal Co.; Carson W. Smith, president, Consolidated goal & Coke Co.; Durbin van Law, consulting, engineer, Denver & Rio Grande Western Railroad; and C. B. Carpenter, professor of metallurgy, Colorado School of Mines. Coal samples from the Northern Colorado field used in the stoker during 3 years of service were supplied through the cooperation of N. C. Brooks, secretary, Northern Colorado Coals, Inc.This report describes the development and practical tests made on a small stoker-fired system for heating service water automatically. The system was designed to take advantage of the favorable reactivity of low-rank fuels, and the objective was to devise a combination of stoker, heat-receiving, and hot-water storage system Which would be automatic for at least 30 days without attention, while heating service water at minimum cost. The system was developed to a point where coal consumption was less than 10 pounds (or less than 100,000 B.t.u.) per day. The total operating cost of hot water for an average-family-was about $1.00 per month, with coal retailing at $6.00 per ton and electric power at 4 cents a kilowatt-hour. The heating system was designed for the utilization of low-rank fuels, but the general features of the double-tank system can be 'employed fuels, either gas or liquid fuels.The Subbituminous Coal and Lignite Section of the Bureau of Mines began investigations on the utilization of low-rank fuels in domestic appliances during 1939. Tests were made on various devices to find out if they were suitable for the low-rank fuels. Most of the available appliances for burning coal have been designed for the higher-rank fuels, and they are not well-suited for burning the lower-rank coals at maximum efficiency, because subbituminous coals and lignite have high bed moisture ranging between 20 and 40 percent by weight, which lowers heating value to the range of 10,000 to 6,500 B.t.u. per pound. They are noncoking, and the ash content ranges between 4 and 6 percent, with a fusion temperature of about 2,0000 F."

Jun 1, 1946

By C. J. Mains

The gas -flow oil-shale retort is a continuous, crass flow, gas -to -broken solid heat-exchange system in which heat is transferred by convection from the gas to the solide.2/ This type of heat transfer presents a problem of analysis that cannot be solved by methods in common use. Solution of this problem is necessary for design, operation analysis, and predict ion wherever that type of heat exchanger is used. This report embodies a method for calculation of heat transfer coefficient and temperature histories of gas and solid in the gas- flow retort operating at equilibrium conditions. Detailed calculations are presented to show the application of the method explained in this report to conditions of an actual run made in the gas-flow retort. Although used here for a specific case, the method is applicable to all heat exchangers that are characterized by continuous, crossflow, gas -to-broken solid heat transfer. INTRODUCTION In any direct, gas -to -broken solid heat -transfer system, it is difficult to measure the temperatures of the gas and solid inside the heat exchanger. The driving force for heat transfer between the two media in the bed there- fore usually is unknown. The major resistance to heat transfer is in the gas film surrounding the solid particles, and the thickness of this gas film is neither uniform nor can it be determined readily. It is well to point out also that determination of the surface area of the particles is of poor accuracy. Since the driving force, the major resistance, and the surface area in the heat-transfer system are such uncertain quantities, It is not feasible to calculate the heat transfer by usual methods. All of the fore- going statements are true of the gas-flow retort; as a result, efforts were made to determine apparent heat-transfer coefficients and temperature histories of gas and solid in the heat -exchange bed by calculation using those data that were available. The heat -transfer coefficient calculated has the following dimensions: B .t .u. per second, °F., cubic foot of bed volume, where heat - transfer coefficients normally have the units; B .t .u . per hour, square foot, °F. Only the Schumann-Furnas formulas may be used to determine the heat- transfer coefficient and temperature histories in this type of heat exchanger.

Jan 1, 1953

By R. V. Ramani, J. Qin

"In this paper, the results of a research study on airborne dust transport in a full scale simulated longwall face are presented. The simulated longwall face was set up in the Lake Lynn Laboratory mine of the U.S. Bureau of Mines to conduct experiments under controlled conditions. The controlled parameters in the experiments were the dust dispersion rate, dust size distribution, density of the dust, air velocity, and the rate of travel of the dust generating source. The analyses of the experimental results on mass concentrations, particle size distributions, and real-time respirable dust concentrations are discussed. There are definite spatio-temporal trends between the location of the shearer, the concentration at any location in the face, and the dust generation rates. The size-consist and density characteristics of the source dust, the air velocity in the face, and the air leakage into the gobs all affect the concentration. INTRODUCTIONA detailed experimental study on the characteristics of longwall dust cloud in operating longwall faces has been reported by Ramani, Qin, and Jankowski (1991). The study indicated that there are several important factors whose effects on dust transport in longwall faces need to be further investigated. In an operating longwall face, the effect of these parameters could not be easily isolated as control over the affecting parameters is not readily possible. In a simulated longwall face, however, these parameters can be controlled. Therefore, as a follow-up to the field study, a series of controlled experiments were conducted in a full scale simulated longwall face in the Lake Lynn Laboratory mine of the U.S. Bureau of Mines [Qin, 1992]. Specific aspects which were addressed during the experimental design phase included determining the types of samples to be collected, selecting proper instruments to collect these samples, and developing detailed sampling and time-study plans to correlate the dust concentrations with face activities. Two types of dust--anthracite and bituminous--were used. Dust dispersion rate into the air as well as the source dust particle size distribution were documented. Control was exercised over both air velocity at the face and air leakage along the longwall face. During experiments, the dust source was moved to simulate the shearer movement at operating longwall faces. Detailed descriptions of the design of experiments, experimental results, and data analyses follow in the subsequent sections."

Dec 1, 1996

By J. R. Soule

"The fluorspar deposits in the Gallinas Mining District, Lincoln County, New Mexico, were examined early in February and again in April 1943 by the Bureau of Mines because of the possible importance of newly discovered deposits and of old mine workings showing fluorite-bearing material. There &re many of these deposits spread over a considerable area, and it appeared that exploration might indicate sufficient reserves to support a local mill that could contribute to the supply of fluorspar needed for war purposes. Accordingly, the Bureau initiated an exploratory program in June 1943, which was completed in August 1944.H. E. Rothrock, Roy Earhart, R. G. Smalley, and V. C. Kelly, geologists of the Federal Geological Survey, began mapping and studying the district in May 1943 and continued this work throughout the Bureau's exploration.David J. Stauffer, district ranger, U. S. Forest Service, and several claim owners assisted in the examinations and subsequent exploration.The fluorspar deposits in the Gallinas Mountains are reached by an unpaved forest road, which, leaves U. S. Highway 54 half a mile south of Gallinas station. The road runs due west for 3 miles, then turns due north just beyond the first cattleguard. This north branch is followed for 2 miles to a second cattleguard. There a left branch extends northwest up Red Cloud Canyon to the Red Cloud, and. All. American deposits; the right branch continues north for 2.miles past the Wade Porter ranch, to another left branch, which goes almost 2 miles west to the Hoosier Group deposits. The remaining deposits are reached by trail from either the Hoosier Group or, more easily, from the Red Cloud claim (fig. 1).The Hoosier Group is in sec. l9,, T.. 1S.,1 R. 12 E.; all of the other known ore occurrences are in secs. 13, 14, and 23 to 27, inclusive, T. IS., R. 11 E. All of the deposits are in the Lincoln National Forest and within the limits of a State game refuge. The nearest railroad loading point is Gallinas, Station on the Southern Pacific Railroad. Corona, the next station north of Gallinas, is a Mile or two farther from the deposits.Minor supplied, telegraph, telephone, freight, and express service, and limited living accommodations, Are, obtainable at Corona, 10 to 15 miles from the deposits of Carrizozo, N. Mex., 50 miles south."

Apr 1, 1946