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Simple parameters, capable of easy observation on-site under operating conditions without interruption to production, are outlined for the operational assessment of underground conveyor systems. Recording techniques, methods of analysis and deduction of operational characteristics are discussed for batch inputs to several points of a multiple belt conveyor system with limited inter-belt storage capacity. Particular attention is given to input and output load- time distributions, utilisation of inter-belt storage capability and system shutdown behaviour. Actual data, observed for a transfer feeder located between two trunk conveyor belts in an underground coal mine, is used to illustrate the operational assessment of an underground system. Load sensitive feedback systems-are briefly considered.

Jan 1, 1982

By Paul Headland

The Washington Suburban Sanitary Commission (WSSC) has recently completed design for the Bi-County Water Tunnel Project. The project will include a 10-foot diameter, 5.3-mile long hard rock tunnel located within the Piedmont Physiographic Province in Montgomery County, Maryland. The rock formations present along the alignment are comprised of igneous and metamorphic lithologies. This paper presents the steps taken to characterize the complex geology along the tunnel alignment into a single ?Engineering Unit? based upon the intact rock and rock mass properties. The Rock Mass Rating (RMR) system is planned to be used as the basis for dividing the ground into three ?Excavation and Support? classes. This RMR approach was selected to establish contractual baselines as presented in the Geotechnical Baseline Report (GBR) and is intended to facilitate management of the ground support characterization during construction.

Jan 1, 2008

By Alfred W. G. Wilson

THE state of development of its iron and steel industries serves as a 1eading index to the general condition of a nation's business affairs. In this paper, the authors present an economic study of the progress of this group of industries in Canada for the decade 1927-1936. The statistical data and most of the tables which accompany this article have been com-piled by John Casey, Statistician, Bureau of Mines; the text and some of the computations have been prepared by the seni0r author. The principal source of statistical information has been the publications of the Dominion Bureau of Statistics; where other sources have been consulted, they are noted in the text. All weights are given in short tons. Records for the years 1913 and 1918 are also presented in the group of tables dealing with iron ore and pig iron; they will serve as a basis for comparison with nearly normal years in the two decades prior to 1927-36, which included the abnorma1 years of the Great War. GENERAL REVIEW At the beginning of the decade under review, this group of industries had returned to almost normal production, as determined by pre-war conditions. Iron ore consumption showed a steady increase between 1927 and 1930; a marked decline began in 1930 and reached its culmination in 1932, when the recorded consumption of ore was 293,353 to11s, about 16 per cent of the average consumption during the first four years of the decade; the last four years of the decade show a gradual increase in consumption; the amount of ore used in 1936 was still slightly below the amount used ten years before, in 1927 (see Table 1, top).

Jan 1, 1938

By V. F. Parry

The major industrial uses of char or semicoke produced by low-temperature carbonization of coal4/ are as fuel for generating electric power, for blending with metallurgical coking coal as a substitute for low-volatile coals, and for gasification to produce synthesis gas for chemical purposes. This paper discusses various methods for carbonizing coal, emphasizing processing of the noncoking coals to produce char for thermal power-plant fuel and for blending with metallurgical coking coals and tar for chemical use. Low-temperature carbonization is a relatively simple processing step involving heating coal to about 900° to 1,200° F. to decompose the coal into 4 main products: (1) Semicoke or char; (2) complex, partly oxygenated liquid hydrocarbons or tar; (3) fixed gases; and (4) water. If the coal is heated rapidly under conditions that prevent decomposition of the primary products, 68 to 87 percent of the net heat in the raw coal is left in the char and 10 to 23 percent of the potential heat appears in the primary tar. Fixed gases represent approximately 7 percent of the heat and approximately 2 percent is lost or dissipated in the reactions of decomposition. Considering the different ranks of coal in the United States, the yield of tar will vary from about 9 to 44 gallons per ton, therefore it is important that each coal be carefully considered if it is to be carbonized for industrial use.

Jan 1, 1955

By Khaled Morsy

Cementitious seals are made of foamed cements with strength ranging from 100 to 600 psi. These cementitious seals are usually used at locations where the seal will be subjected to some convergence, assuming that this material can absorb entry closure without compromising the structural integrity of the seal. Prior to 2006, Lake Lynn Experimental Mine (LLEM) conducted full-scale tests on various cementitious seals designed to meet or exceed the 20-psi horizontal static load requirements of the old 30 CFR1 75.335. Both hydrostatic and dynamic loading tests were conducted. The structural response (pressure and displacement readings) obtained from these tests were recorded. The stability of the cementitious seal is based on balancing the load applied to the face of the seal from the explosion against the shearing resistance at the seal/rock interface. Therefore, the properties of the seal/rock interface, such as stiffness, cohesion, friction, etc. are critical to determine the stability of a cementitious seal. These properties are usually assumed by the researchers in their models. This paper emphasizes the importance of having the correct properties of seal/rock interface in the numerical modeling. FLAC 3D models were developed to simulate Celuseal2 cementitious seals subjected to both hydrostatic and dynamic loadings. Using the hydrostatic and dynamic loading test data conducted at LLEM, the static and dynamic properties of the seal/rock interface were back calculated. The FLAC 3D models showed good agreement with the test results.

Jan 1, 2009

By Marcos Paulo Kohler Caldas

A recuperação de metais presentes em equipamentos eletroeletrônicos tem atraído interesse em virtude de novas e diferentes tecnologias que visam a reutilização desses elementos químicos em novos processos produtivos. A recuperação de metais das placas de circuito impresso tem atraído o interesse das empresas, pois, ao mesmo tempo que produz bons resultados do ponto de vista econômico, também se pratica o desenvolvimento sustentável, reduzindo a extração de metais da natureza. Este trabalho tem como objetivo caracterizar as placas de circuito impressos (PCI’s) de memória de computadores, através de imagens de microscopia eletrônica de varredura com espectroscopia por dispersão de energia (MEV/EDS), a fim de verificar a presença de metais, visando a sua recuperação.

Aug 17, 2017

By T. W. Smelser

This Bureau of Mines report presents a review of underground testing, test results, and design guidelines of steel-fiber-reinforced concrete (SFC) mine support (cribbing) developed at the Spokane Research Center. The objective of the work was to verify, in field applications, the performance, economics, and acceptance by the mining industry of the SFC supports and establish design guidelines for their use underground. Results indicate superior performance, favorable economics, and enthusiastic acceptance by the mining industry.

Jan 1, 1983

By Philip D. Wilson

SPEED is essentiaI in this war program and it is hard to keep up with developments. When the title of this paper was chosen, the contemplated magnesium production for which plants were then under construction was some 200,000 tons of metal per year or sixty times the 3350-ton production in prewar 1939. A few- days later an analysis of the President's 185,000-plane pro-gram, incendiary bomb schedules, and the additional requirements of the Army. Navy and Maritime Commission made it apparent that a much greater amount of magnesium must be provided in 1943. The new figures are huge but the censor will not per-mit their disclosure.

Jan 1, 1942

By MAURICE SUNKPAL, Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Despite numerous empirical, numerical, and hybrid studies conducted on the subject of coal rib failure, mine fatalities related to rib failures continue to occur at around 1.5 per year between 2009 and 2021. To date, a standard methodology for the design of coal rib supports that can accommodate the wide range of unique conditions found in coal mines in the USA has not been developed, forcing mine operators to rely on the trial-and-error process or industrial legacy practices for the design of coal rib support patterns. In this study, to better understand the support systems’ effectiveness, various rib bolting scenarios were investigated. A coal mass constitutive model is implemented to a distinct element method (DEM) code, and rib factor-of-safety (RibFOS) analyses were performed by applying strength-reduction for the coal matrix and explicitly modeled face cleats. Ribs with various overburden depths and mining heights composed of solid Banded-Bright coal (BBC) were considered in this study. Different scenarios such as rib bolt length and the number of bolts were studied to quantify the effect of primary rib support density on rib stability. As a result of the unsupported coal rib analyses, a decaying exponential relationship is proposed between the mining height-overburden depth and the RibFOS. The developed coal rib models clearly show the coal-rib bolt interaction and illustrate how the addition of rib bolts restricts the movement of the coal rib. The results reveal that the strength reduction method in DEM code with the coal-mass model can aid in the development of practical primary support charts, which can help in the rib support design process. In addition, an unsupported RibFOS cutoff is proposed, beyond which the addition of primary support cannot stabilize the failed rib structure.

Aug 5, 2023

By H. P. Stüwe

HE recent papers of Aust and Rutter112 have again brought to mind the importance of certain "special" orientation relationships between the lattices of two fcc crystals on the mobility of the grain boundary separating them. No theoretical treatment of this problem has been offered till now. The only principle published so far that has given an indication why certain orientation relationships should be "special" is the counting of "coincidence sites" according to the suggestions by Kronberg and Wilson.3 The "coincidence plots" published by these authors show, for instance, that two fcc lattices rotated by 38 deg around a common (111)-axis have 1/7 of their lattice sites in common. Such an orientation relationship is also characteristic for high boundary mobility. The accuracy of the orientation relationship needed for high mobility is not too rigid. Deviations up to 10 deg from the ideal orientation seem to be tolerable as can be gathered from the experimental data.'j4 The auestion arises, then. how the density of coincidence sites will be affected by a deviatioi from mathematical accuracy. This can be checked by a simple model. Two sieves are prepared, the arrangement of the holes corresponding to lattice sites on a (111)-plane in a fcc crystal. They are placed upon each other, Fig. 1. One is kept fixed, the other is rotated around an axis pushed through one hole in common to both. The light falling through holes of both sieves is then a measure for the density of coincidence sites. If the diameter of the holes is very small, light intensity is contributed only by holes the centers of which coincide "exactly." If the diameter of the holes is rather large, some intensity will be contributed by

Jan 1, 1962

By Gustavo Nucci Franco

A indústria do aço passa por seu pior período no Brasil e as empresas vêm buscando soluções para minimizar custos e garantir as operações com menos recursos. Ponto importante nessa busca de ganhos potenciais, a Logística vem, assim, merecendo uma atenção especial. Este trabalho apresenta esforços da AM Juiz de Fora, em parceria com a Franco Arbeit Engenharia, para reduzir o tempo de permanência de veículos em sua unidade e, com isso, evitar custos com o pagamento dos novos valores de permanência. Para isso, foram utilizadas modernas ferramentas de Simulação em Computador para que as soluções mais adequadas pudessem ser implementadas com sucesso.

Aug 17, 2017

By R. E. Tate, L. J. Herman

We have had occasion to produce wire of Np-237 in small diameters for use in some chemical experiments. Since the mechanical metallurgy of neptunium has not been investigated extensively, it seems desirable to report our successful extrusion technique. Because of the neptunium activity and its attendant health hazard the experimental work was done in glove boxes and related equipment also used for Pu-239. At room temperature a phase neptunium' is a hard (Dph -355) orthorhombic metal of high density (p = 20.45 g per cu cm). a neptunium transforms2 to tetragonal ß neptunium at about 280°C and this in turn transforms to bcc y neptunium at about 577°C. The y phase melts at about 637°C. A temperature of 340° to 345°C was selected for the extrusion, this temperature being a compromise be- tween a possible advantage of working with the presumably more plastic cubic y phase above 577°C and the risk of having the neptunium react with the alloy steel die to form the low-melting Fe-Np eutectic. A 0.75-in.-long, 0.26-in.-diameter ingot of good-purity* Np-237 was extruded by the direct *C = 230 ppm, Pu = 200 ppm, thirty-five metallic elements below limit of detection by spectrographic methods. process through flat-face orifices to form several sizes of wire ranging from 0.010 to 0.030 in. in diameter. Molybdenum disulfide was used as the die lubricant. The extrusion was done in a vacuum of about 10-4 torr to reduce reaction of the neptunium with atmospheric gases. British workers3 at Harwell have extruded neptunium under similar conditions. The force required to extrude 0.010-in.-diameter wire at the rate of 4 in. per min was 6000 lb, as measured with an electrical load cell. Wire 0.020 in. in diameter was extruded with a force of 4700 lb at a rate of 2 in. per min, and wire 0.030 in. in diameter was extruded with a force of 4000 lb at a rate of 1.3 in. per min. An extrusion constant, c, can be computed from the measured forces, P, for the equation4 P = c log-A/a where A/a is the extrusion ratio or the ratio of the cross-sectional areas of the container and the

Jan 1, 1965

By C. F. Winquist

The Bureau of Mines is engaged in research to evaluate the effects of cutter bit wear at coal mine faces. This paper addresses one element of conical bit wear, bit rotation. A discussion on mounting configura-tion and bit forces and their effects on rotation is presented. The effects on rotation and bit forces of bit attack angle, cutting depth, and skew are determined for two types of conical bits during linear cutting of sandstone-inclusive rock. The results indicate that a 10° negative skew angle and 35° attack angle produce the maximum rotation of 17.5° for each foot of cutting. Data on bit rotation and bit forces are presented in an appendix.

Jan 1, 1985

By S. Gallagher, A. G. Mayton

Back injuries account for a high proportion of lost workdays in the mining industry and are a leading cause of disability in mine workers. Two risk factors for low back injuries are manual lifting and whole-body vibration exposure when operating mobile equipment. Recent research has shed light on possible mechanisms through which low back injuries may occur, and the results of these studies can be used to improve the design of lifting tasks and seats to decrease injury risk. This article discusses recent research results and how this knowledge can be leveraged to reduce the risk of low back pain.

By G. Lindkvist

Roasting of concentrates with high impurity levels is normally done in multiple- hearth furnaces where the concentrates are heated with oilfired burners in order to remove As, Sb and Bi before the final sulfide oxidation. Although it is a countercurrent heat exchange process it uses a lot of oil. In order to develop an energy saving, and from a working environmental point of view a less harmful process than the multiplehearth process, pilot-plant tests have been done in a two-stage fluidized bed for partial roasting. The test materials have been As-rich concentrates with 8-25 % As some 5b and Bi. The Cu-content was 0-28 %. The tests have been successful with <0.3 % As,in the calcine and with an elimination of 5b between 80 and 90 %. In order to achieve the proper conditions for good impurity removal, 1.e. right temperature,residence time and sulphur potential, the tests were performed in a special designed roaster. The roaster consists of two beds with the facilities for recirculation of calcine, preheating of the blast, and possibility to use oxygen enrichment. The construction makes it easy to control the reactions that generate the heat in the bed and reduce the amount of dust that passes through the cyclones. As two roasting steps are used, the possibility to obtain optimal conditions for impurity removal is improved and the calcine can either be smelted to a normal matte, or after being dead-roasted in the second stage, be leached in the normal way for gold extraction. The calcine was smelted with slag. The matte and the slag obtained had low quantities of impurities in the matte and a favourable distribution of impurities to the slag.

Jan 1, 1983

By A. J. Kraemer

The twenty-fourth of a series of semiannual surveys pertaining to motor gasoline marketed in the United States was made by the Bureau of Mines in August, 1931. The first part of a report giving the results of that survey as they pertain to specification data is given in this paper. A companion report, Part II, is in preparation and will discuss the results of other determinations made on the samples, including octane number ratings on the individual samples (to be made by the Bureau of Standards) and results of the determination of gravity, color, doctor test, and "gum" content by the copper dish method and the Bureau of Mines steam-oven method. The retail price and the tax at the time each sample was taken will also be reported.

Jan 1, 1932

By Northcutt Ely

This volume- summarizes mining and petroleum legislation in 18 European jurisdictions. Within these jurisdictions, primary attention is given to requirements that must be met in each country for acquisition of rights to permit development of mineral resources. Coverage includes: First, identitication of the controlling laws or statutes governing minerals acquisition and reference to the administrative authority; second, analysis; of the laws governing mines and quarries and their products; third, analysis of laws applicable to natural gas, petroleum, and related materials; and fourth, mention of laws regulating offshore operations. Where pertinent, sections dealing with historical background or administration have been added in countries where minerals are subject to control of States or Provinces, those areas are considered separately from the central government.

Jan 1, 1974

By A. Vorster

The objective with mine planning is to consistently deliver production conforming to quality and quantity requirements throughout the life of the mine. The complexity of the operational context of the modern mine extends far beyond the actual production actions and there is a need to find ways of analysing and managing this extended environment. A well-established approach to handling complex situations rely on the creation of representative models that use classification and visualization strategies. An example of the use of a classification scheme is the periodic table of the elements. All physical matter can be expressed as combinations of basic elements. Not only is the periodic table useful in classifying and identifying matter but it can also be used for the prediction of the properties of unknown matter and compositions of elements.

Jan 1, 2001

By Alexander E. Morrow

Oxygen breathing apparatus for use in mines was introduced to the United States in 1907. Despite their intended purpose of safeguarding lives, the apparatus led to the deaths of many men because of inherent or developed defects in the equipment, lack of training,, physical shortcomings of wearers, and improper procedures. The Bureau of Mines pioneered in research and training to curb logs of life among users of such apparatus and promoted development of safer equipment and procedures. As a consequence, deaths have been far less frequent. In 1944 the Bureau issued Information Circular 7279, Loss of Life Among Wearers of Oxygen Breathing Apparatus. That publication listed the case histories of 26 deaths that had occurred since the introduction of such equipment to American mining. The author, the late G. W. Grove,3/ asserted that further loss of life could be avoided if good equipment were used, teams were properly trained, and the basic principles of safe procedure were followed. This publication is a sequel to I.C. 7279 and contains information on eight deaths among wearers of oxygen breathing apparatus that were overlooked in the original compilation. It also describes the single death that occurred since I.C. 7279 was published.

Jan 1, 1959

By Martin Berman

Tables of 28 positions for all the transitions for nine common analyzing crystals for first, second, and third order reflections were compiled by the Bureau of Mines to facilitate elemental X-ray fluorescence analysis on multi-element systems. The tables are based on a compatible set of wavelengths for 2,346 observed X-ray transitions of the elements lithium to americium. The results are tabulated in order of increasing wavelength as well as by increasing wavelength for each element.

Jan 1, 1969