Search Documents

By G. M. Potter

During the investigation of the occurrence of manganese deposits in the western United States, examining engineers of the Bureau of Mines collected samples from four properties in Siskiyou and Mendocino Counties northern California. As the ores were too low-grade to be acceptable to manufacturers of ferromanganese, beneficiation studies were made between 1941 and 1945 to determine the amenability of the ores to concentration. The Johnson and Reynolds properties are near Fort Jones Siskiyou County. The ore occurs in a number of small lenses in that area. Samples were taken for testing for amenability to treatment in a small custom-gravity plant, tentatively planned. by the Waiter Johnson interests of San Francisco. A 2-ton representative sample was obtained from numerous exposed portions of an outcrop on the property of the Mayland Mining Co. The Mayland mine is about 8 miles from Sawyers Bar in Siskiyou County. The ore body consists of stringers and irregular masses of oxide, and. silicate ore scattered through quartz, which these minerals have replaced.

Jan 1, 1952

By R. V. Ramani, S. Shankar

"A convective dispersion model has been utilized to calculate the real-time airborne dust concentration in mine airways using re-entrainment as the only source term for airborne dust. It incorporates two important sources of re-entrainment in mines -- air velocity and movement of objects. The model has a sink term accounting for the deposition of particles along the airway. The model is solved using a finite difference scheme which is coded for computer. The computer model outputs airborne respirable and total dust concentrations along the airway as a function of time. The real-time and average gravimetric concentrations from several in-mine experiments were compared with the results from the simulation of the experimental conditions. This model can be used for estimating airborne dust entrainment due to air velocity, equipment movement, and persons walking. INTRODUCTIONEdwards and Ford (1988) developed a model for coal dust explosion suppression and utilized a predetermined value of threshold velocity for flowing air to pick up dust from floor. Depending on the strength of the removal forces, re-entrainment can increase the airborne dust concentration in mine airways. The most prevalent forces causing re-entrainment in mine airways are the drag and lift forces due to flowing air, and removal forces due to the movement of persons and vehicles. Shankar and Ramani (1991) have investigated the unique characteristics of the re-entrainment phenomenon in mine airways. Experiments on re-entrainment of coal dust particles were conducted in mine airways, and in a wind tunnel (Shankar and Ramani, 1994a, and 1994b). The results from the two experimental studies were found to compare well (Shankar and Ramani, 1995). There is no reported model to determine the airborne dust concentrations due to airflow or persons walking under conditions existing in mines. The present study is a part of a continuing research project in the Generic Mineral Technology Center for Respirable Dust on the spatial and temporal behavior of airborne dust in mine airways (Ramani, 1983)."

Dec 1, 1996

New Copper Deposit in Chile. - The recent copper discovery in Chile, made jointly by U.S.-owned Empresa Minera Utah de Chile, Inc., and Getty Mining Chile), Inc., awaits the passage of Chilean legislation which is expected to govern the terms of new foreign investment in the country's mining sector. Named La Escondida, the discovery is reported to have the potential for producing 100,000 tons of refined copper per year. This compares with Chile's total refined primary copper production in 1980 of 811,000 metric tons, and to U.S. refined primary production in 1980 of 1,122,000 metric tons derived from domestic material, and 89,000 metric tons from foreign material. U.S. Firms Buy Chilean Properties. - A bid of $18.1 million, made jointly by Chevron and St. Joe Minerals Corp., won over competing bids for the purchase of the Libra and Mena gold-silver-copper deposits in northern Chile. Chevron is the lead partner and owns 70% of the venture. The two properties purchased have not been developed to any significant extent. They are located near St. Joe's El Indio gold-silver-copper mine. The venture is also looking at the possible purchase of two other mines in the area.

Jan 1, 1981

By Nick Derick

The continued growth of steel production in the Western States is contingent upon the development of new iron ore sources. Recent development of economical techniques for concentrating and agglomerating taconites has focused attention on the low-grade magnetite deposits near Atlantic City, Wyo., as potentially important sources of iron ore for blast furnace smelting. Therefore, the Federal Bureau of Mines has made comparative evaluations of blast furnace burdens that incorporate pellets produced from Atlantic City concentrates. The Bureau also has evaluated the relative effect of Utah coke on blast furnace performance, using a high-quality Eastern coke as a basis for comparison. This work was done in the Bureau's experimental blast furnace at Bruceton, Pa. Tests determined the maximum wind rate that could be used while a continuous stock movement was maintained in the furnace. The furnace was operated at wind rates ranging from 800 to 1,400 std. c.f.m., them maximum limit of the blowers for the 1.75 in.-diameter tuyeres used. Using a normal Utah ore burden and Utah coke, the furnace went into a tight hanging condition with a wind rate above 950 std, c.f.m. Using the experimental pellet burden again with Utah coke, the wind rate could be increased to 1,000 std, c.f.m. and probably to 1,050 std. c.f.m, before tight hanging occurs. This represents an increase of 5 to 10 pct. in the wind rate. The experimental results indicate an accompanying increase of iron production, as much as 8 pct.

Jan 1, 1961

By Blade O. C.

This report is one of a series made by the Bureau of Mines under a cooperative agreement with the Coordinating Fuel and Equipment Research Committee of the Coordinating Research Council, Inc., on the characteristics of commercial aviation gasolines. The series of surveys is a continuation of like work conducted from 1940 to 1946 by the National Bureau of Standards under a similar cooperative agreement. A list of reports of previous surveys is given at the end of this paper.

Jan 1, 1950

After more than 20 years dependence on bituminous coal as a primary fuel for generating electricity, the Pennsylvania Power and Light Company initiated a one-year study on the economics of building an electric generating station using anthracite as a fuel. The study will be completed in December 1976. If the feasibility study so indicates, PP&L will consider installing four 400,000 kilowatt generating units for scheduled commercial operation in 1985. Each unit would consume up to one million tons of anthracite annually. Anthracite generally is more difficult and expensive to extract than bituminous coal, but it has a significantly lower sulfur content than the bituminous coal currently being used by PP&L, thereby eliminating the costs of installing sulfur emission controls at generating stations. Moreover, significant reductions in transportation costs may be realized because the utility's operating territory is situated in the center of the anthracite region in northeastern Pennsylvania. These advantages may indicate that the use of anthracite is more economical than bituminous coal to PP&L. ASBESTOS -Asbestos production in the U.S. dropped again in 1975 until it was just two-thirds of that in 1973. This was in spite of the very strong demand caused by the Quebec strike. The 7-month strike of the asbestos miners in Thetford Mines, Quebec cut off 55 percent of the normal supply of U.S. consumers. Apparent domestic consumption was less than 75 percent of that in 1974. The wage settlement will probably result in a 20 percent increase in asbestos prices.

Jan 1, 1975

By W. D. Musgrove, B. W. Gandrud, A. C. Richardson

"INTRODUCTION The Cahaba coal field is the second largest coal—producing area in Alabama. This field underlies parts of Shelby, Jefferson, St. Clair, and Bibb Counties and has an area of about 270 square miles. The Cahaba formations contain a number of coal beds, about 8 of which are mined at present. Although the area contains many folds and faults, samples from various mines and beds indicate that, except for the variation in ash content, the coal from this field is very uniform in character and quality. It is a high-volatile bituminous coal used chiefly for steam-raising purposes and domestic fuel. The coal as mined usually contains too high a percentage of impurities to be marketed without some preparation. The majority of the mines have washing plants in which jigs are the favorite type of equipment, although at some mines tables are used for cleaning the slack sizes. The washing characteristics of the coal from the Cahaba field are very uniform and differ from those of the near-by Warrior field, in that the coarser sizes contain a much lower percentage of bony material than the finer sizes. In general, the bone increases with decrease in size. It breaks into thin flakes, making difficult its elimination in the cleaning process, and gives rise to what is known among the washery operators of the Cahaba field as the ""rash problem.""A previous publication 5 referred to rash from the standpoint of jig operation and suggested some means of handling it with jigs. This report presents the results of table tests on two samples of fine coal from the Thompson and Woodstock beds, respectively, of the Cahaba field to determine the influence of rash on table efficiency.This investigation has been made in connection with the study of coal-washing problems now being conducted by the U.S. Bureau of Mines and the University of Alabama, with the cooperation of the different coal operators of Alabama."

May 1, 1934

By C. E. Augustine, P. Nicholls

"INTRODUCTION A layer of soot on the heating surface of a boiler decreases efficiency because it increases resistance to the flow of heat, with the result that the heat transfer to the water is lower and the temperature of the flue higher than they would be if the surface remained clean. The percentage of reduction in heat transfer depends on the position and area of the sooted. The percentage of reduction in heat transfer depends on the position and area of the sooted surfaces, the thickness of the most, until the percentage of the total heat absorbed by those surfaces when clean; thus it will vary with the type of boiler and in particular with the ratio of the area of the convection heating surface to the total area. Medium-size and large boilers usually are equipped with soot blowers, and tests have been published giving the increase in efficiency resulting from removal of the soot. Fuel savings up to,8 percent have been reported, but 4 to 5 percent is probably more conservatives. However, these savings may not be due wholly to a reduction the thermal resistance of the surfaces but may be due partly to improvement in the combustion because of better draft or more uniform flow of the gases. In addition, the deposits on the surface of boilers include as a clinker, and as the size of the boiler and the rate of burning increase very little or none will be soot.There are no corresponding test data on small boilers operated at low rates of burning. In stall boilers, deposits are much thicker, and it might be expected that the reduction in efficiency would be greater; in fact, statements have appeared suggesting that the decrease may be as high as 50 percent. This investigation was undertaken because the Bureau frequently receives requests for authoritative information on the effect of soot in small and other heating boilers."

Feb 1, 1935

By H. S. Auvil

[The shrinkage of coke after formation is one of the variables that affects the net expansion of the change in both industrial and test ovens. Various test results have been interpreted as indicating that cokes from certain coals shrink to a marked extent and that other cokes show very little shrinkage; out no comprehensive experimental study of the shrinkage of coke after its formation and of the factors influencing this shrinkage has come to the attention of the authors. While investigating the reactivity of cokes made by the BM-AGA method,6/ Reynolds7/ found that granular low-temperature cokes shrink considerably then reheated to higher temperatures. This shrinkage was large enough to influence the behavior of the charge (net expansion or contraction) in a coke oven to a marked extent. Since that time the Bureau of nines has investigated the shrinkage of coke different methods, all of thick had one common objective - the elimination of the effect of other factors, such as swelling in the plastic range, which could either partly or completely mask the shrinkage of the coke. Only parts of these studies have been published8/9/ in abbreviated form in]

Jan 1, 1940

By H. S. Auvil

[The shrinkage of coke after formation is one of the variables that effects the net expansion of the change in both industrial and test ovens. Various test results5/ have been interpreted as indicating that cokes from certain coals shrink to a marked extent and that other cokes show very little shrinkage; but no comprehensive experimental study of the shrinkage of coke after its formation and of the factors influencing this shrinkage has come to the attention of the authors.]

Jan 1, 1940

USBM Contract H0133045 consists of the design, build and test of 50 waveform generators. The waveform generator is a small ULF transmitter operating in the 1 to 3 KHz frequency range for the purpose of locating trapped miners during a mine disaster. This contract provided for the design, test, and building of 50 waveform generators using a discrete component construction with an option of using hybrid construction techniques within 105 days after the effective date of the contract. Because of large quantity economic considerations, this option was not initiated. Two engineering models were designed, constructed and tested and 50 final production units were fabricated using discrete construction. Complete documentation is supplied under a separate package which includes final schematics, parts list, layout information, equipment specification, production test procedures and qualification test procedures. Ten units have been delivered to the USBM. The remaining 40 units are being retained for packaging under contract H0242010 Transmitter Package and Receivers.

Jan 1, 1974

By Frank J. Wiebelt

Under a general program to extend the resources of mineral deposits, the Bureau of Mines examined the Quien Sabe antimony mine in October 1948. The preliminary evaluation demonstrated that a diamond-drill program was warranted co establish the tenor and persistence of the veins and permit an estimation of antimony reserves. The Bureau of Mines conducted a diamond-drilling program on the property from December 1949 to May 1950. Ten holes aggregating 2,483 feet were drilled. Nine of the holes encountered antimony-bearing vein material.

Jan 1, 1956

By R. T. Artz

Disposal of sewage is an important part of mine sanitation. Improper... handling and.disposing of sewagerare conducive to the spread of disease and often add foul and nauseating odors to the mine air. The diseases spread by unsafe methods of disposing of waste in mines are typhoid fever, cholera, amebic dysentery, hookworm, and other intestinal diseases due to parasites. Sanitary toilet facilities, with a good sewage-disposal system, each maintained in good order at all times, should help to prevent the spread of diseases transmitted by intestinal body wastos. The metal and nonmetal-mining industries have recognized the impor-dma tance and need for disposing sewage properly; accordingly, facilities of some sort are installed and need today in most large mines. The coal-mining industry has given little thought to the disposal of sewage underground; however, in most mines of the anthracite industry, the inflow of large vol- unes of highly acid mine water and the extensive drainage system required to remove this water provide a natural means for disposing of sewage.

Dec 1, 1946

By R. W. Van Dolah

A premature detonation of an explosive charge occurred on January 30, 1961, at a face being prepared for blasting in the underground Jefferson Island Salt Mine, Diamond Crystal Salt Co., Jefferson Island, Iberia Parish, La. The accidental blast injured the powderman fatally; his helper was injured also, but recovered. The accident represents the first fatality reported to the Bureau of Mines in connection with the use of ammonium nitrate-fuel oil (AN-FO) blasting agents in underground mining in the United States. Representatives of the Bureau of Mines Explosives Research Laboratory, Pittsburgh, Pa., and field representatives of the Bureau's Health and Safety Activity conducted the investigation, upon request of the manufacturer of the ammonium nitrate being used and with concurrence by the mine management.

Jan 1, 1962

By Lloyd Williams

1. The investigation shows that the Poplar Creek and Big Mary beds contain the largest known recoverable reserves of coal in Morgan County, Tenn. The Poplar Creek bed has been the most productive. 2. Known measured and indicated reserves of coal, based on a minimum bed thickness of 14 inches and on 1,800 short tons per acre-foot of coal in place, are estimated to be 96 million tons, as of January 1, 1954. Of this total, 59 million tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics were too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1956

By George Markon

The rapid growth and development of the Soviet coal industry rank the U. S. S. R. with the United States among the leading coal-producing countries. The coal resources of the Soviet Union are among the largest in the world, although coal development has been hindered by the disadvantageous location of the coal deposits with respect to the major consuming centers. Although coal production in the U. S. S. R. reached a record high, the total energy output of mineral fuels in 1957 was still far below that of the United States because a significant part of Soviet coal output was lignites or lower rank coals. Although the Soviet coal industry soon may exceed that of the United States in tons produced, the energy equivalent of Soviet output will be considerably less because of the inclusion of a high percentage of lower rank coals. Energy sources in the United States also involve large quantities of oil and natural gas, whereas coal supplies most primary energy in the Soviet Union.

Jan 1, 1959

By R. R. Sayers

"Health hazards in the mining industry may be attributed to (1) abnormal conditions of the air, (2) improper sewage disposal, (3) bad drinking water, (4) bad illumination, and (5) local mechanical irritation.Abnormal conditions of the air may be due either to physical or chemical changes. The physical changes are (1) abnormal temperature, (2) abnormal humidity, (3) air movement, and (4) presence of dusts. Dusts may be either poisonous, as salts of lead, arsenic, zinc, or mercury; or nonpoisonous, as dust from coal, silica or quartz, limestone, gypsum, or silicates. Chemical changes may be due to changes in the normal constituents, as lowered oxygen or increased carbon dioxide; or to the addition of abnormal constituents, as carbon monoxide (white damp), hydrogen sulphide (stink damp), sulphur dioxide, methane (marsh gas, fire damp), hydrogen, and nitrogen.Effects of High Temperatures and Humidities The effects of various temperatures and relative humidities have been studied in mines in many countries. Harrington and myself studied them in the metal mines of this country and, in a report written recently, they have been summarized as follows:A. Remaining at rest in saturated air at 91 1/2° F, for one hour, With no air movement caused -1. An increase in body temperature;2. A moderate increase in pulse rate;3. Profuse sweating;4. After effects of dizziness and weakness with air movement caused ¬1. Slight or no increase in body temperature"

Dec 1, 1924

By Alla D. Mah

Combustion energies of barium and strontium were measured by means of the combustion bomb calorimeter. The heats of formation obtained for the oxides were ?H298.15 = -139,060 ± 700 cal/mole of barium oxide (BaO) and ?H298.15 = -144,440 ± 400 cal/mole of strontium oxide (SrO). Tables containing heats and free energies of formation from 298.15° to 2,000° K were prepared.

Jan 1, 1963

By M. E. Volin

The Smuggler is one of the mines in the Aspen district, located the central part of Pitkin County, Colo. It was first examined in July 1943 by C. R. Wilfloy, former mining engineer of the Bureau of Mines at Salt Lake City, Utah, in, company with the lessees, R. D. Rohlfing of Aspen and J. W. Vanderwilt of Denver. The purpose of this examination was to sample a mineralized breccia zone that appeared continuous along the contact between the Leadville and Weber formations. These preliminary samples showed that the zone contains low but significant amounts of lead and zinc and that the minerals are partly oxidized and thus not easily concentrated. The mine was examined again in May 1946 by the senior author and William Herron, one of the present lessees of the property. This examination reviewed the previous sampling and recommended investigations by the Bureau of Mines. Sampling and drilling investigations were conducted by the Bureau from October 1946 to February 1947 and again from August 1947 to April 1948. Aspen is the center of a famous mining district that produced over $102,000,000 in silver and lead ores from 1880 to 1918, when a dispute closed down the mines (fig. 1). All of the workings below the Cowenhoven tunnel in Smuggler Mountain and the lower Durant tunnel in Aspen Mountain have been flooded since that time. The Cowenhoven portal now is caved, and Smuggler Nos. 1 and 2 tunnels are the only accessible workings in Smuggler Mountain. The only operating mine is the Midnight, situated 4 miles south of town at an altitude of 9,700 feet.

Jan 1, 1950

By Roger J. Morrell

Bureau of Mines laboratory experiments with reduced scale cutter and cutter forces were performed to (1) define the fundamental relationships governing disk cutter performance and (2) to develop a method of predicting disk cutter performance in soft, medium, and hard rocks. The rock cutting experiments were performed in four igneous and metamorphic rocks that ranged in compressive strength from 38,000 to 67,000 psi. A special testing machine called a linear cutter apparatus (LCA) was used to load and traverse a free rolling disk cutter across a smooth rock surface. Each pass of the disk produced a single crater, and runs were spaced to avoid breakage between craters. During each run the normal and tangential cutter forces were measured and recorded. The soft and medium rock data were obtained from previous Bureau experiments with disk cutters. Crater depth, tangential cutter force, crater volume, specific energy versus normal cutter force, and crater width versus depth are defined within this study. With the use of standard physical properties, performance prediction equations were developed using stepwise linear regression analysis techniques. A method of using these prediction equations to calculate the boring rate, the cutter spacing, and the torque and energy requirements of a full-scale boring machine was also developed.

Jan 1, 1974