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By K. L. Paciorek

The aim of this program was to develop a reliable and meaning-ful basts for assessing certain safety aspects, namely fire and, in particular, toxicity hazards of articles employed in underground coal mining operations. This investigation was centered on the thermal oxidative degradation of "pure" ingredients used specifically in the formulation of conveyor beltings. To achieve this goal all products formed on thermal oxidative degradation of the materials studied were analyzed, identified I and the amount of each individual species present was determined quantitatively on a weight of product per weight of material basis. The weight/weight data thus obtained can then be factorized to reflect the relative toxicity of each individual species present, using for example the Threshold Limit Values adopted by the American Conference of Governmental and Industrial Hygienists, whereby an overall "toxicity index" can be arrived at which makes it possible to compare the different potential formulation components in a quantitative manner insofar as their "toxicity" is concerned. Furthermore, knowing the off-gassing characteristics of the commonly used additives I their contribution to the product mix obtained from actual belting can be postulated. Conversely, from the species obtained on thermal oxidative degradation of conveyor belts the type and to a degree the content of additives can be deduced. Based on the se data meaningful regulations governing the material selection for underground use can be developed. For these studies a quiescent system at 370°C was employed. Thermogravimetric and differential thermal analyses were performed to supplement and extend the sealed system investigations and to provide information regarding thermal oxidative behavior under dynamic conditions.

Jan 1, 1975

By José E. Rondoña

El presente trabajo desarrolla un estudio comparativo de la producción de dos tipos de hornos usados en la fundición de cátodos de zinc en la planta de La Oroya, para asi determinar cúal es el equipo más idóneo para futuras expansiones del proyecto. De los puntos comparativos se encontró que el horno SICE desarrolla más productividad de personal en operaciones, así como en el rendimiento de la energía eléctrica. Mientras que respecto de las consecuencias de las filtraciones del metal, se encontró que el horno Ajax es el más adecuado, dado que la producción de barras se afecta solo en la producción que el horno afectado representa en la instalación total. Por ende, es conveniente el uso de dos hornos SICE tamaño mediano dada la capacidad y productividad de esta.

Nov 20, 1967

By Eugene H. Skinner

The U.S. Bureau of Mines conducted experiments on the use of lightweight concrete in the density range of 100 Ib/ft3 for liners in underground mines. Three test sections were completed: a monolithic, portal-type structure with integral walls and arch constructed aboveground; an underground test section constructed in a mine drift using plywood forms; and a second section constructed in a drift using an air-supported formwork. The lightweight concrete in the two underground test sections was placed using piston pumps and a slickline. Fiber reinforcement was added to the concrete in the mine sections without any apparent problems with either pumping or placement of the concrete. In another experiment, the Bureau and Hecla Mining Co., Mullan, rD, used lightweight concrete in the density range of 25 Iblfe to replace timber blocking in a raise preparation structure. Other experiments are described in which low-density, lightweight concrete blocks were produced for mine ventilation doors, stoppings, and barricades. Other mine uses reviewed include pillars and collapsing beams. An advantage of low-density concrete is that it will display up to 50% deformation at a constant yield stress. These hlllovative concepts in deformable concrete lining systems will aid mine operators by decreasing capital and maintenance costs, increasing the available space in underground haulageways, and providing productivity gains and improved resource recovery in the soft, caving, squeezing, or bursting grollnu conditions often found in deep mines.

Jan 1, 1989

By Y. Guglielmi, C. Gout, P. Henry, P. Dick

The key questions about fault reactivation in shales concern the potential enhanced fluid displacement through a previously low-permeability aseismic shale formation. Here we selected a critically-stressed fault cross-cutting the underground research facility of Tournemire (France) which is located in Toarcian shales. Several inclined boreholes were drilled across the 8.5 m thick fault zone characterized by a fractured damage zone (FDZ) and a central 2.4 m thick complex core (FC) made of multiple shear bands with gouge intercalated with highly fractured lenses. The fault was pressurized using a straddle packer system defining a 2.4m long injection chamber normal to the fault surface. Three fault zone intervals were tested, two in the fault damage zone and one in the fault core. A three-dimensional displacement sensor set in the chamber allowed continuous synchronous coupled monitoring of fault movements, injection pressure and flow rate. An anticlockwise 0.22-to-0.05 mm fault slip was captured associated with a 10-to-100 hydraulic aperture increase of the fault. Preliminary analyses of the experiments show that leakage in the fault zone is controlled by strength and stress magnitude contrasts between the fault core and the fault damage zone. Fault damage zone discontinuities display a much higher peak static friction angle than the fault core shear zones, respectively of 34 and 22° that could be related to complex interactions between healing and sealing processes. Fault core leakage is much more dependent on strain than on effective stress variations. Discontinuous, pulse-like leakage, develops following complex failure processes that may simultaneously take place in the gouge zones and along the large pre-existing discontinuities. Such results may be of importance in evaluating fault seal integrity in oil and gas exploration, production or CO2 storage or underground excavations monitoring.

Jan 1, 2015

By James Herbert Bartlett

The MANUFACTURE of Iron in the PROVINCE of Quebec. The St. Maurice Forges.—The deposits of iron-ore in the St. Maurice district, in the rear of Three Rivers, were probably known to the Indians and .Jesuits, but it is not till 1667 that any discovery is reported. The affairs of the colony were then in the control of the " West India Company," who amongst other monopolies had a right to all mines and minerals." Specimens of the iron-ore were examined in Quebec. in 1668 by the Sieur la Potardière, who reported unfavorably on them. In 1671, Louis de Buade, Comte de Frontenac, was appointed governor of La Nouvelle France ; and in the original manuscripts relating to his administration some allusion is occasionally found to the St. Maurice iron mines.? In a letter to the Imperial Government, dated 2d November, 1672, he says: "The iron mine of which I have already spoken is of great consequence. I have visited it myself, in order that I may be enabled to give a more accurate account of its nature. I am gratified to learn that another mine has been discovered in Champlain, which is much richer than the Cap de la Madelaine mine, and the ore is in greater

Jan 1, 1886

By Marcelo Rebellato, Leonardo Silvestre, Zhang Yongqing, Felipe Bastos, Zhang Weiqiang

This work reviews the new version of GB1499.2-2018 Chinese national standard and specification, which governs the production of high-strength reinforcing hot rolled ribbed bars in China. In addition, it discusses the main concerns from Chinese rebar makers that might affect production and application of Nb-bearing rebars, like reheating temperature required to dissolve given niobium additions, the promotion of bainite microstructure and continuous yielding, as well as Nb strengthening effects. Through extensive investigation involving both thermomechanical laboratory simulations and industrial trial, the existing state and effects of Niobium along the reheating, rolling and cooling are illustrated. At the end, optimum processing conditions have been established to produce high strength rebars for the specified requirements. The adoption of new process conditions reflected in an amount of about 20.0 million tons of Nb-bearing rebar being produced in China in 2018 with required tensile properties and microstructure, and helped rebar makers to reduce production costs considerably. Based on production data, Niobium demonstrated positive strengthening effect for high strength rebars, in particular for small diameter rebars with earthquake resistant performance. What is more, the results of the research enrich the knowledge of the application of Niobium in steels when TMCP rolling is not used.

Oct 1, 2019

By S. S. Clarke

This paper on methods and costs of mining at the Westside mine, in the Tri-State zinc-and lead-mining district (Missouri-Kansas-Oklahoma), is one of a series being prepared by the Bureau of Mines on mining practices, methods, and costs in various mining districts of the United States. Methods and equipment used in drilling, loading, and underground transportation have changed radically since the latest Bureau of Mines publications2/ on mining methods in the district were published more than 20 years ago. More efficient methods and machines have been developed in order to maintain low operating costs in the face of rising labor and supply costs and lower grade ore. The rate of conversion to mine mechanization was disappointing at times; local conditions required the development of special equipment, and available rock-moving machines had to be remodeled and strengthened.

Jan 1, 1957

On the following pages are abstracts of papers published by the Institute during the year 1935 as TECHNICAL PUBLICATIONS and CONTRIBUTIONS, papers in bound volumes appearing for the first time, and papers in MINING AND METALLURGY. For abstracts of papers that appeared in bound volumes in 1935 but that were published as TECHNICAL PUBLICATIONS in 1934, see the YEAR BOOS dated January, 1935.. Many of the TECHNICAL PUBLICATIONS have been reprinted in bound volumes. Information regarding this disposition, and number of pages in each paper, may be found in the list beginning on page 64. Volume numbers are given as listed at the beginning of the index, page 71. The abstracts are grouped as follows: [Page Metal Mining 17 Uses of Metals 23 Milling and Concentration 23 Iron and Steel Division 26 Nonferrous Metallurgy (Reduction of Ores)...: 34 Institute of Metals Division (Founding and Metallography of Nonferrous Alloys) 36 Page Coal Division 43 Petroleum Division 50 Industrial Minerals Division (Nonmetallics) 57 Mining Geology 60 Mineral Industry Education Division 62 Geophysical Prospecting 62]

Jan 1, 1936

By Joël Kapusta

La pyrométallurgie du cuivre est essentiellement une chaîne de trois étapes successives d’oxydation préférentielle du fer et du soufre et des impuretés moins nobles que le cuivre qui sont contenues dans le concentré de cuivre issu de l’usine de concentration du minerai, aussi appelée concentrateur. La Figure 1 illustre la chaîne complète d’élaboration du cuivre depuis la mine jusqu’au cuivre pur. La voie hydrométallurgique traite le concentré par lixiviation, c.à.d. par dissolution en phase aqueuse à température typiquement inférieure à 100 ou 150⁰C, alors que la voie pyrométallurgique traite le concentré par fusion à température de l’ordre de 1200 à 1300⁰C.

May 2, 2024

By R. Addison

This is the story of the Carlton Mill. But first-a little geography. For those who do not know where the Carlton Mill is, or, perhaps, have only a vague idea, its location is indicated in Figure 1. The plant is situated on the road between the two old mining towns of Cripple Creek and Victor, 10 the west of Colorado Springs. From Denver, it's about 110 miles by road. The story of the Carlton Mill began with the discovery of gold at Cripple Creek in 1890. This discovery set off a major boom such that, by the turn of the century, there were 450 separate operating mines in the district. Gold production boomed early and declined rather rapidly as indicated by the graph in Figure 2. Significant factors affecting production are shown on the graph-the raising of the gold price in 1934 from $20.67 to $35.00 per ounce and the government executive order L-208 in 1942 requiring the closure of all gold mines.

Jan 1, 1983

By Charles H. Dowding

INTRODUCTION "On many projects, the tendency is to drop interest and support of the geological service as soon as it seems safe. That . . . is a short-sighted policy . . . It would be of further service perhaps to learn whether predictions were reasonably true to life." --C.P. Berkey, 1938 (3) This paper quantitatively compares predicted and encountered shear zone size and location and rock type for tunnels in the Colorado Mineral Belt. The Colarado Mineral Belt is composed of igneous formations with associated metamorphic rocks and faulting. As such, it represents the most complex of provinces for at-grade predictions (27). Shear zone and rock type data are assumed to be statistically homogeneous because of the common geology of the seven tunnels. It is often felt by geologists and engineers that the amount of information from which a geological model is created is so low that any statistical inferences are unstable. In other words, the addition of new data may drastically alter the means and variances suggested by the model. Therefore, predictions are rarely couched in quantitative statistical terms but modified with "probably," "most likely" or "possibly." Comparison of predicted and encountered data from past geological models will permit the "probably's" to be quantified and distilled from the art of geological prediction. To date, two other studies of the validity of predictions have been made (26 and 16). Together, these two studies indicate that

Jan 1, 1976

By Michael J. Cruickshank

A workshop to examine recovery systems for selected strategic and critical materials in the U.S. National Seabeds for the National Defense Stockpile in the 21st Century was held in Hawaii September 26-28, 1991, sponsored by the National Science Foundation and the Marine Mineral s Technology Center. The National Defense Stockpile of critical and strategic mineral commodities is presently in a deficit position of more than 7.5 billion dollars. Current domestic reserves of some commodities are limited or nonexistent. As defined by the U.S. Bureau of Mines, "Reserves are select resources . . . which at the time of classification, can be mined at a profit." Occurrences of these minerals have been discovered offshore within U.S. jurisdiction. If the technology could be developed to convert these resources into usable ore reserves, our dependence on foreign ores could be greatly reduced. Preliminary estimates indicate that a ten-year program of ore reserves definition, with appropriate technical developments to demonstrate a recovery system, could cost less than half the amount authorized for stockpile acquisition in FY 1989 alone.

Jan 1, 1991

By J E. Wheeler, S B. Valine, L G. Albuquerque

It has long been known that closed circuit grinding with a classifier improves grinding efficiency, reduces unit specific power consumption, and reduces over grinding. The classification device removes material from the circuit that has reached the desired size and returns coarse material back to the mill for further grinding. The efficiency of the classifier is an important factor in the overall performance of a grinding circuit. The classifier affects the capacity of the grinding circuit and the metallurgical performance of downstream operations. A review of historical research and modern case studies is used to demonstrate the benefits of high frequency screens for classification in grinding circuits.CITATION:Valine, S B, Wheeler, J E and Albuquerque, L G, 2012. Applications of fine screens in grinding circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 389-394 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Knut H. Hubert

The GRATE-KILN System plant at Svappavaara, Sweden, was constructed for LKAB by Allis-Chalmers under a turnkey contract and commissioned in 1969. The plant was designed to produce iron ore pellets from magnetite concentrate at 6100 mtpd using imported fuel oil. It represented the state of the art for plants of its type at the time. Fuel rated capacity was attained within one week of start-up. Product quality, power usage, fuel consumption and machine wear were within warranty limits during sustained production thereafter. As operator skills improved and gas handling system reserve capability was utilized, the plant frequently produced acceptable product at up to 115% of design capacity. During the period 1969 to 1976, market demands increased for high-quality pellets while energy costs rose steadily. At the same time, important advances in the design of GRATE-KILN Systems were being made in other plants constructed by Allis-Chalmers.

Jan 1, 1980

By M. L. Jeremic

Altered and unaltered coal from the Star-Key Mine near Edmonton, Alberta has been tested under compression and under tension. The test results showed that altered coal samples have an appreciably lower strength than unaltered coal. Altered coal samples do not give a linear load-displacement curve, peak strengths are poorly defined and yielding is observed over a range of loads, so the material can be regarded as relatively plastic. However, unaltered coal samples produce a linear loading curve with a high tangential modulus and an easily distinguished peak strength at which there is a sudden brittle failure. These findings lead to important differences in the theoretical design of ribs and pillars in underground mines in the two coal types. The substantial differences in the strength properties and behaviour of the two types of coal are governed by a higher intensity of cracks in the weathered coal. Two causes of the additional cracking can be suggested-subaerial weathering and subterranean weathering of the coal.

Jan 1, 1979

By W. D. Hausel

Archean supracrustal rocks of the South Pass greenstone belt of western Wyoming have been the State's most prolific source of gold and iron ore. Actual gold production statistics are incomplete, but as much as 400 to 500 thousand ounces may have been mined with some silver and tungsten as a by-product. Iron ore was also mined from the greenstone belt for 22 years, and production totaled more than 90 million tons. Immediately south of the exposed greenstone belt in the Oregon Buttes area, Tertiary boulder conglomerate, which has been eroded from the granite-greenstone terrain, may contain a gold resource of 28.5 million ounces (Love and others, 1978). The amount of gold placered from stream alluvium derived from these Tertiary conglomerates is unknown.

Jan 1, 1986

By Morgan M. Sears, lhsan B. Tulu, Ted M. Klemetti

"Why do some room and pillar retreat panels encounter abnormal conditions? What factors deserve the most consideration during the planning and execution phases of mining and what can be done to mitigate those abnormal conditions when they are encountered? To help answer these questions, and to determine some of the relevant factors influencing the conditions of room and pillar (R&P) retreat mining entries, four consecutive R&P retreat panels were evaluated. This evaluation was intended to reinforce the influence of topographic changes, depth of cover, multiple-seam interactions, geological conditions, and mining geometry.This paper details observations made in four consecutive R&P retreat panels and the data collected from an instrumentation site during retreat mining. The primary focus was on the differences observed among the four panels and within the panels themselves. The instrumentation study was initially planned to evaluate the interactions between primary and secondary support, but produced rather interesting results relating to the loading encountered under the current mining conditions. In addition to the observation and instrumentation, numerical modeling was performed to evaluate the stress conditions. Both the LaModel 3.0 and Rocscience Phase2 programs were used to evaluate these four panels. The results of both models indicated a drastic reduction in the vertical stresses experienced in these panels due to the full extraction mining in overlying seams when compared to the full overburden load. Both models showed a higher level of stress associated with the outside entries of the panels. These results agree quite well with the observations and instrumentation studies performed at the mine.These efforts provided two overarching conclusions concerning R&P retreat mine planning and execution. The first was that there are four areas that should not be overlooked during R&P retreat mining: topographic relief, multiple-seam stress relief, stress concentrations near the gob edge, and geologic changes in the immediate roof. The second is that in order to successfully retreat an R&P panel, a three-phased approach to the design and analysis of the panel should be conducted: the planning phase, evaluation phase, and monitoring phase."

Jan 1, 2016

By John C. Hartley

Large areas of the anthracite beds in the Wilkes-Barre, Pa., region have been first-mined in such a manner that over half of the original coal has been left underground as pillars to support the overburden. To recover the maximum amount of this remaining coal, improved devices to support the roof while pillars are being extracted are needed. Also needed are suitable backfilling systems that will stabilize the strata during the mining and effectively limit the inevitable subsidence after pillars are removed. Accordingly, the Federal Bureau of Mines furnished 400 yielding steel props that had been purchased abroad, where this type of prop had been used successfully. The cooperating company arranged for concurrent tests with a mechanical stower designed and built by an American manufacturer. In the area in which the experiments were conducted, pillar removal, using conventional timbering, was most difficult because the roof fractured badly, the installation of timbers consumed a substantial part of the work effort, and some coal nearly always was lost. With the application of the yielding props, the time needed for securing the roof was reduced 33.9 percent; production per man-shift was in¬creased over 33 percent; coal recovery was improved more than 9 percent; and the convergence between roof and floor, during mining and backfilling, amounted to as much as 8.03 inches without any break in the roof. However, in September 1953 some roof rock fell in pillar 10 owing to insufficient props in a small area where the ends of three top holes drilled in the coal face extended up into the roof rock.

Jan 1, 1956

By Joseph B. Cummings

"Occurrences of fluorite on the Packard property were first examined by an engineer3/ of the Bureau of Mines in July 1943 as the result of receipt of an application for an access road. In August of the same year the showings were examined by a geologist4/ of the Federal Geological Survey. The property was again examined by an engineer5/ of the Bureau of Mines in March 1944. This last examination resulted in a proposal that access be gained by construction of a truck trail and that the Bureau of Mines undertake to explore the fluorite showings.The truck trail was constructed by the Public Roads Administration, which began the work on February 17, 1945, and completed it 8 days later.The Bureau of Mines exploratory program was completed on May 16, 1945. It consisted of stripping overburden, trenching, test pitting, tunneling, sampling, and topographic mapping.In addition to being described in some detail, the extent of the work as well as results are shown in accompanying tables and figures.Mrs. Rhoda A. Packard, Mrs. Nora 1. Cline, and C. B. Pettingill, all of Tonto Basin, Ariz., own the property, which comprises four contiguous, unpatented lode mining claims recorded at Globe, Ariz., as the Walnut and the Bluebird 2, 3, and 4. The claims are situated in T. 6 N., R. 11 E., Gila County. David L. Roscoe of Tombstone, Ariz., holds a lease and option to purchase.Access to the property is by Highway 88 from Globe, 34 miles to Roosevelt, thence 24 miles by a graded county road along the west side of Roosevelt Lake to Tonto Basin. Here the Greenback Ranch road, constructed by the Forest Service and maintained by the county, crosses Tonto Creek and continues easterly to the foothills. The truck trail leaves the road 8.5 miles east of Tonto Basin and runs 2.5 miles in a southerly direction to the property. (Fig. 1.)The fluorite deposits lie in and along a small canyon in a rough, rocky area at an altitude of about 3,400 feet, Vegetation is scant and of the usual desert variety. The summer climate is dry and hot and the winter climate moderate. Rainfall at the Forest Service Station in Tonto Basin was 11.4 inches from May 1944 through March 1945."

May 1, 1946

By John P. Savage

This paper is one of a series being prepared by the United States Bureau of Mines on tunneling methods. The tunneling methods described are those used at the Ojuela unit of the Compania Minera de Penoles, S. A., the Mexican subsidiary of the American Metal Co., Ltd., of New York. The Ojuela unit is situated some 4 miles southeast of Mapimi, Durango. Mexico, the latter place being connected by a 15-mile narrow-gage railway with the standard gage railroad at Bermejillo, some 40 miles to the north of Torreon, the location of one of the company's smelters.

Jan 1, 1931