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By Albert E. Long

This paper presents a description of the operational mechanics involved in block-caving a granodiorite-capped, limestone deposit. This method was used for 24 years at the Crestmore mine, near Riverside, Calif., which was operated by the Riverside Cement Co. as a source of raw material used to manufacture a portland cement. The Crestmore mine is the only place where a block-cave method has been used to mine a limestone deposit. Structurally, limestone is relatively strong, and it is not usually considered to be a substance amenable to mining by block caving. It is therefore a credit to the engineering department of the Crestmore mine that it developed a satisfactory, relatively efficient method of block-caving a structurally stable rock. In the discussion, covering the methods applied to produce about 7.9 million tons of limestone and granitic rock materials by block caving, particular emphasis has been placed on an assessment of (1) physical properties of the deposit, (2) ground pressure and support, (3) methods used to induce fragmentation and maintain cave action, (4) surface and subsurface subsidence, (5) secondary blasting of oversize, (6) production rate, (7) safety, and (8) the advantages and disadvantages of the cave method as applied to this specific limestone deposit.

Jan 1, 1958

By Joseph Cervik

Gas occurs in coalbeds in an adsorbed and a free gas state, Adsorbed gas is stored in the micropore structure and its transport is governed by Fick's law. The free gas occurs in the. fracture system and flows according to Darcy's law. These two modes of mass transport are interdependent. Production decline curves of coal-gas wells are of the constant percentage decline type and, thus, show no indications of flow characteristics peculiar to coal-gas reservoirs. The effectiveness of surface boreholes as a degasification scheme depends upon both good fracture permeability and a high fracture density. Conventional methods of reservoir engineering analysis are not applicable to coalbeds.

Jan 1, 1969

By Jan M. Mutmansky

"When, in 1973, a limit was placed on the amount of dust in the coal mine atmosphere, restricting the average exposure of a coal miner to 2 milligrams of dust per cubic meter of air (mg/m'), skeptics in the United States and abroad Said the standard could never be achieved. They cited much more lenient standards already established in other countries and refused to believe that the United States could meet the world's most stringent requirements in mines where dust had never before been regulated. Yet 10 years later the goal had largely been achieved and miners were working underground in a cleaner atmosphere than ever before. It was a major achievement and a big stride in what had become a war on coal workers' pneumoconiosis (CWP), the black lung disease prevalent among miners in underground coal mines.Although the health hazards caused by working in a dust-filled mine atmosphere have long been recognized, the problem became particularly acute in this century with the mechanization and increased productivity of underground coal mining. The United States was much slower than some other countries to address the problem of respirable diseases among miners. While dust levels in South African gold mines were first regulated in 1912, in the United States it was only when 476 workers died of silicosis while blasting a tunnel through a mountain near Gauley Bridge, West Virginia in the 1930s that widespread public attention became focused on the plight of workers in dust-filled environments. Another 30 years passed before regulation of dust finally became law in the Coal Mine Health and Safety Act of 1969.With a stringent new standard imposed in all underground coal mines, the industry was faced With the daunting problem of reducing levels of airborne dust from perhaps 6.5 mg/m' to 2 mg/m', in an inherently dusty operation carried out in the close confines of underground passageways. Most of the coal dust is made by the cutting operation in which the continuous miner or longwall machine can produce several thousand milligrams of respirable dust for each ton of coal mined. Other dusty operations such as drilling holes for roofbolts, loading and unloading coal on shuttle cars, and the operation of conveyor belts contribute to the overall problem.Since the institution of the new dust control standards, a number of strategies have been adopted for reducing the coal dust in the mine atmosphere. These strategies involve engineering and design improvements that help lo prevent the generation of particles, keep particles of dust from becoming airborne, carry dust away from the working area, and isolate the dust from the workers in the mining operation. These procedures have been pursued vigorously by the Bureau of Mines, and many successful methods have been developed to reduce the mass concentration to which the workers are subjected. The mining companies were reluctant at first to confront the problems but after a period of trials and gradual improvement, they joined with others in the fight to reduce the dust concentrations in the working place."

Jan 1, 1990

By H. R. Shell

The systems MgO-MgFa-SiO2, at 2 and 4 weight-percent Li2O and at 3.8 and 7.7 weight-percent Na2O were investigated by solid state reaction at 1,200° C. The results are summarized in four ternary diagrams. Besides the expected humites and simpler silicates or fluorides, proto-amphibole and water-swelling fluormicas or fluormontmorillonoids were found in the systems containing lithium and monoclinic fluoramphiboles, water-swelling fluormicas or fluormont-morillonoids, and nonwater-swelling fluormicas were found in the systems containing sodium. These latter compounds were not in the base system MgO-MgF2-SiO2.

Jan 1, 1962

By W. W. Graff

This paper describing the mining practice at Mine No. 5 of the Marquette range, Michigan, is one of a series being prepared by the Bureau of Mines on mining practices, methods, tend costs in the various mining districts of the United States. The top-slicing system of mining, has been used ever since the present operating company took control of the property in 1903, the main level and sublevel layout being chanced only as local conditions required and the use of mechanical equipment increased.

Jan 1, 1930

By John M. Gomes

In the repetitive electrowinning of tungsten from scheelite, the calcium impurity buildup in the molten electrolyte results in decreased metal purity, metal recovery, and current efficiency. Periodic addition of B2O3, which reacts with the lime liberated from the scheelite, more than tripled the life of the electrolyte in winning 99.9-percent-pure tungsten and also reduced the number of units of electrolyte required per unit of tungsten recovered from six to four.

Jan 1, 1966

By J. D. Hadden

The Bureau of Mines conducted drilling studies in the Pocahontas No. 3, the Pittsburgh, and a western coalbed to establish the gas migration characteristics for each. Gas pressures in the Pittsburgh coalbed were about 260 lb/in2 and in excess of 550 lb/in2 in the Pocahontas No. 3. Caving in drill holes prevented pressure measurements in the western coalbed. The Pittsburgh coalbed contained intersecting "clay veins" which formed gas pressure cells. Although these geological features hamper mining, they can be used to control the flow of methane into a mine working. Methane control techniques are proposed for the Pittsburgh and Pocahontas No. 3 coalbeds.

Jan 1, 1969

By B. W. Madsen

Bureau of Mines research to recover arsenic from mining industry waste material and process streams is reported. Batch and column approaches were investigated for adsorbing arsenic from acid leach solutions and ion-exchange eluate solutions with hydrated titanium dioxide granules. A method for producing hydrated titanium dioxide granules was devised to provide material suitable for use in a packed adsorption tower. Selective adsorption of arsenic from acidic leach solutions was achieved. The loading capacity of arsenic on the granules was 14 wt-pct when synthetic solutions were used, but lower when actual leach solutions were used. Other elements in the leach solution were Zn, Cd, and In. The granules were used in an attempt to lower the arsenic content in a solution containing 0.95 g/l W and 0.027 g/l As from a process devised by the Bureau of Mines to treat Searles Lake brine. The arsenic content was lowered to less than 0.001 g/l, but unacceptable amounts of tungsten also were adsorbed by the granules. Adsorbed tungsten was partially stripped with pH 11.5 NaOH, and both tungsten and arsenic were completely stripped with 5M NaOH solution. Repeated loading and stripping of the granules had no effect on the loading capacity for arsenic.

Jan 1, 1983

By M. Townsend, E. L. Petsonk, B. Fedders, M. Niggemeyer, H. Abrons, E. Daniloff, J. Griffin, K. Kinsley

In certain populations, nonspecific airway hyperreactivity (HR) is associated with increased respiratory symptoms and decreased lung function. We analyzed standardized pulmonary symptom questionnaires and pre-shift spirometry with methacholine inhalation challenge (Chatham, M. et al, Chest 82: 15) on 228 control workers (C) with no known exposure to occupational hazards, and 200 underground bituminous coal miners (M). M and c were similar in age, height, sex, and smoking status. HR (defined as >15% fall in FEVI after up to 5 vital capacity breaths of 25mg% methacholine) was found in 25% of M and 28% of C (NS). M showed higher% predicted FEVI (%PFEV) than c (M 107%, C 104%*). 28% of current smokers showed HR versus 22% of never smokers (NS). Current smokers showed reduced %PFEV but were not different from lifelong non-smokers regarding prevalence of HR. Subjects with HR showed reduced %PFEV, (HR 101%, not HR 107%*) but M and c with HR showed similar reductions. M had more dyspnea and chronic cough than c*. Hyperreactivity was associated with increased symptoms in controls but not miners. In our study, the prevalence of HR in coal miners was similar to nonminers, and did not explain miners' respiratory symptoms. * P < 0.05

Jan 1, 1989

By Albert J. Forney

A process for the manufacture of high-Btu gas from coal has been developed by the Bureau of Mines. The process consists of fluid-bed gasification of the coal, followed by the gas treatment steps of gas purification and methanation. Advantages of the system are that caking coals can be used directly, and more than half of the ultimate methane is made in the gasifier.

Jan 1, 1970

By A. F. Colombo

The differences in starch demands that occur between ore types subjected to the anionic flotation of calcium-activated gangue and the range of residual starch contents expected to give the best metallurgical response were evaluated on a batch and pilot plant basis. A phenol-sulfuric acid procedure was used to determine the residual starch contents in the iron ore slurries. Three pilot plant campaigns on samples from a group of orebodies located on the Marquette Range, Michigan, showed that in the rougher flotation pulp, a residual carbohydrate range of 25 to 100 ppm, which is equivalent to a 0.5 lb/short ton spread, yielded optimum results. Concentrates assaying at least 65 percent Fe and less than 6.0 percent Si02 and containing more than 80 per-cent of the recoverable iron were obtained. Both batch and continuous research indicated that starch adsorption is calcium modulated and relatively unaffected by the fatty acid additions employed. Residual starch level is not a critical control factor, but the addition must be adjusted to about 25 to 50 ppm residual starch and kept in this range for most effective utilization of the added tapioca flour.

Jan 1, 1972

By W. L. Cornell

The Missouri Pb ores are the only domestic Co resource being mined and processed for other metals; therefore, they present a viable short-term opportunity for Co production. Lead, zinc, and copper concentrates are produced from the ore. The Cu concentrate can contain up to 30 pct Co and the Pb concentrate up to 15 pct Co. Since Co is detrimental to the processing of the Zn concentrate; the remainder of the Co is rejected to the tailings. The tailings can contain as much as 50 pet Co originally present in the mined ore. Researchers at the U.S. Bureau of Mines have successfully tested on a continuous basis a process that recovers a bulk sulfide concentrate from mill tailings. The concentrate contains up to one-half of the Co and from 50 to 90 pct of the Pb, Zn, and Cu. Concentrate weight represents 10 pet or less of the total tailings.

Jan 1, 1989

By H. Tomlinson

The development of the Sevier Valley Coal Co.&apos;s mine marks the opening of the Salina Canon coal district in Utah. The mine is favorably located with respect, to the existing markets of the West, and if the present estimates of the amount of workable coal in it are accurate it has many Important advantages in favor of its development. This mine is situated 18 miles east of the town of Salina, Sevier County, Utah, which at present is the nearest shipping point oh the Marysvale branch of the Denver & Rio Grande Western Railroad, and is about 152 miles south of Salt Lake City, which is the distributing center for much of the coal from the Carbon - Emery coal field and is the place from which nearly all Utah coal shipped to San Francisco and points on the northern Pacific coast has a common haul.

Jan 1, 1930

It is suggested in chapter 1 that emergency activities (including escape) are not individualistic. They tend to be group responses. If escapes from mine fires are group activities, then preparation for such events must take group behavior into account. This chapter explores the hypothesis that the miners who escaped from the three mines under study did so as members of groups. For development of this chapter, the database was examined for evidence of the existence of escape groups and for instances when individualistic behavior was paramount. Illustrations of group and/or individualistic behavior were analyzed and representative examples are provided in the following discussion. The nature of groups was discussed in chapter 3 and the following working definition was offered: "We mean by a group a number of persons who communicate with one another often over a span of time, and who are few enough so that each person is able to communicate with all the others, not at second-hand, through other people, but face-to-face" [Homans 1950]. To determine whether or not groups existed during the fire evacuations, it is important that the concept of group be clearly defined. Therefore, the discussion started in chapter 3 will be elaborated here. The defining characteristics of group given in chapter 3 were taken from Homans [1950]. They include size, person-to-person com¬munication, feelings that members have for each other, explicit and implicit rules for behavior, and common activities. An additional characteristic that is sometimes used to define groups is cohesiveness. Kiesler and Kiesler [1970] state, "Cohesiveness would include not only the attraction that the group holds for its members but also any other force operating on the individual to stay in the group." Variables said to contribute to cohesiveness include "(1) the attractiveness of a group for its members," and "(2) the coordination of the efforts of the members" [Keisler 1970]. One source of the attraction to a group occurs when "the goals or exterior tasks confronting the group are consistent with those of the individual person, and can best be handled by group action" [Cartwright and Zander 1968, in Davis 1969]. In other words, a common goal and a coordinated effort mounted to achieve that goal contributes toward the creation of a cohesive group. As discussed in the earlier review of research (chapter 1), groups have frequently been studied in laboratory or simulation settings. These methods allowed control over variables of interest. Kiesler and Kiesler [1970] state, however, that they "find group variables conceptually imprecise and experimentally difficult to work with." Experimental control, in other words, is difficult to achieve in the study of groups. The richness of the naturalistic mine fire data may provide an opportunity for an examination of groups that cannot be found in laboratories or simulations because this environment was not

Jan 1, 2000

By Fredrick L. Johnson

No mineral resources were delineated during our investigation of the Antelope Wilderness Study Area (WSA). Only a few claims have been located in the area and only four workings were found. There has been, however, considerable exploration and mining activity in and near the south end of the study area. The Morey mining district, just southeast of the WSA, produced silver, and lesser amounts of gold and lead, sporadically from the mid-1860&apos;s through the mid-1960&apos;s. Long Lac Mineral Exploration (Texas), Inc. is actively exploring a large block of claims for hot-spring type, low-grade, large-tonnage gold deposits. Their claim block extends into the study area. The WSA, located midway between Tonopah and Eureka, encompasses approximately 87,400 acres. It is underlain by Tertiary rhyolitic and latitic volcanic rocks and by Paleozoic sedimentary rocks. At least three areas in the Paleozoic rocks have many of the favorable criterion for hot-spring type gold deposits; they have been faulted, silicified, brecciated, and hydrothermally altered, and have anomalous concentrations of precious metals and pathfinder elements. With additional exploration in the south part of the Antelope WSA, gold resources may be discovered.

Jan 1, 1986

By Robert H. Dickson

This paper describing the mining practices at the Verde Central mine at Jerome, Ariz., is one of a series being prepared by the United States Bureau of Mines on mining practices, methods and costs in various mining districts of the United States. ACKNOWLEDMENTS The costs contained in this paper were prepared by R. J, Huddleston, chief clerk, Verde Central Mines, Inc.

Jan 1, 1931

By Harold C. Pierce

"INTRODUCTION During the years 1941 to 1945, the United States produced less than one-half of one percent of all primary nickel, whereas the nation's consumption of the metal amounted to nearly three-fourths of the world's supply. Although postwar nickel consumption probably will be less than wartime consumption, trade- estimates for the next 10 years are well above the average established during the 1930-1940 decade. The greatest consumption is expected in nickel alloys, particularly nickel-alloy steels. 3/ The greater use of nickel cast irons and nickel-clad metals also signifies an expanding nickel market. In anticipation of the postwar demand for nickel, and realizing the seriousness of the ""have not"" position of the United States with respect to this metal, the Bureau of Mines, sent an engineer 4/ into the lower Copper River region of Alaska during the summer of 1944 to investigate the nickel deposits near the head of Canyon Creek. Samples from the Spirit Mountain nickel prospect were sufficiently encouraging to justify more intensive exploration. As a result, a program of surface trenching, systematic sampling, and detailed mapping of the property was adopted and directed by a Bureau of Mines engineer 5/ in the summer of 1945."

Aug 1, 1946

By N. A. C. Smith

During the past, six, years, the Bureau of Mines has made and. published several hundred analyses of typical crude oils and &apos;has developed a system of interpreting the analyses and of classifying crudes. This system is presented here with. It is apparently equate for classifying crude oils into four main groups and has also been found very convenient in studying the geological relationships between crude oils, and the probable refinery yields of valuable products from them. Crude petroleum is morn to be a very complex substance. An analytical statement of its properties must, therefore, consist of two distinct parts, - first, the report of the results of the determinations made by the analyst in the laboratory, - second, the proper arrangement, classification and interpretation of these results so that the analysis, as a mole, will indicate the meaning- and the relative- importance of the essential characteristics of the oil.

Jan 1, 1927

By J. B. Gayle

Numerous investigators have studied the addition of inert4 substances to coking blends. Generally, the results have yielded trends applicable only to the particular coals and inerts studied. Recently, somewhat more general results were obtained for cokes produced from blends containing added inerts, using the sole-heated oven. The present investigation represents an extension of this work to include a wider range of inerts and to determine the applicability of the various conclusions to cokes produced with the Tuscaloosa oven. The results indicated that an increase in dry-coal charge density of 1 pound per cubic foot (p.c.f.) caused a corresponding change in the hardness (1/4-inch tumbler index) of Tuscaloosa oven cokes of 0.9 percentage points. This value compares favorably with the value of 0.7 determined previously for the sole-heated oven and Bureau of Mines-American Gas Association (BM-AGA) retort.

Jan 1, 1961

By T. N. McVay

The Bureau of Mines has developed a field test for detecting the presence of columbium in a variety of minerals containing the clement. The test consists of fusing the mineral or rock powder with potassium pyrosulfate in a porcelain crucible, digesting the melt with hot dilute hydrochloric acid to release the columbium oxide (Cb205), and subsequently reducing the columbium oxide to a lower oxide by adding tin, which gives a blue color to the contents of the crucible. The method will detect 1 percent of contained columbium oxide (Cb205) in a mineral sample provided no tungsten is present. If a mineral containing appreciable titanium is test,-!d in the same manner, the solution in the crucible becomes violet. In the presence of columbium, titanium at first causes a violet coloration of the solution, which after a few minutes is masked by the stronger blue of the reduced columbium oxide. Although tantalum oxide (Ta205) does not interfere with the columbium test, tungsten gives a blue color that is indistinguishable from the color obtained with columbium. A simple method is available to detect the presence of columbium in the absence of tungsten, but when the presence of tungsten is suspected, the sample must be subjected to somewhat more elaborate chemical tests to determine the presence or absence of columbium. Although these latter tests can be made in the field, several steps are involved that arc best performed in the laboratory with simple equipment.

Jan 1, 1962