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By S. M. Shelton, A. L. Engel

"This report presents the results of investigations of ore-testing projects assigned to the Ore-Dressing Section, Metallurgical Division, Bureau of Mines, at the Mississippi Valley Experiment Station, Rolla Mo. During the fiscal year ended June 30, 1941.The manner of approving ore-testing projects has been explained in a previous reports. 4/ The testing procedures likewise have been described. 5/The treatment methods described are based upon laboratory experiments with small amounts of sample and naturally are subject to the inherent, normal, limiting conditions of such procedure. It is not intended to describe treatments in detail, but rather to indicate applicable methods. Local operating conditions, when the laboratory results are applied to plant operations, may require further study. Large-scale pilot-plant tests should be made before commercial operations are begun, so that translation from the experimental stage will yield satisfactory results."

Mar 1, 1942

By Frank H. Madison

The percentage depletion deduction on Federal Income Tax Returns under the provisions of the 1939 Internal Revenue Code and of Sections 611 to Section 615, inclusive, of the revenue act of 1954, have created innumerable administrative difficulties, and a new interpretation of "gross income from the property" in that the Courts have expanded the ideas of what constitutes "gross income from the property" to a degree unheard of and unthought of prior to the enactment of these two codes. Originally, under the Revenue Acts of 1917, 1918, and 1920 depletion was allowable, based upon mine valuations as of March 1, 1913; if the mine was owned prior to March 1, 1913; upon cost, as of the date of acquisition if purchased subsequent to March 1, 1913; and upon a "discovery" basis if the mine was discovered after March 1, 1913, The "jab" for mine valuations as of March 1, 1913 and for discovery valuations and depletion was not as bad as it has been made out to be. Thousands of valuations and estimates of reserves were made and agreed upon between taxpayers and Internal Revenue Service engineers and as the years went on the answers have been found to be "reasonable." However, human nature being what it is each case was a battle of wits - of a sort - and many resulted in severe differences of opinion and litigation. As tax rates increased the situation was not bettered. I could talk for several hours on this phase of depletion but it is all past now andwould not give any real service or better understanding of the matter.

Jan 1, 1958

THOSE MARKED THUS * ARE MEMBERS, MARKED THUS ?ARE ASSOCIATES. THESE SIGNS DOUBLED INDICATE LIFE MEMBERS AND ASSOCIATES RESPECTIVELY. THE FIGURES AT THE END OF THE ADDRESS INDICATE THE YEAR OF ELECTION. HEAVY-FACED TYPE SIGNIFIES HONORARY MEMBERSHIP. *AARONS, J. BOYD, Vivian Gold Mining Co., Ltd., Harris, West. Australia. '05 *ABADIE, EMILE R., Cons. and Min. Engr., 214 Union Savings Bank Bldg., Oakland, Cal. '76 ?ABBÉ, MAX F., Prest., Abbé Engineering Co, 220 Broadway, New York, N.Y. '07 ? ABBÉ, PAULO., Secy.,Abbé Engineering Co., 220 Broadway, New York, N.Y. '07 *ABBOTT, CHARLES W., Min. Engr. Pioche, Nev. ?08 *ABBOTT, CLARENCE Chief EDgr., Iron Mines, Dic Tennessee Caol, Iron & R. R. Co., Bessemer, Ala. '04 *ABBOTT, JAMES W., Min. Engr: Ploche, Lincoln Co., Nev. '94

Jan 1, 1917

By Javier Illanes, Maurice Moore, Felipe Moroni, Rafael Acosta

Any organization that subjects its activities to a continuous improvement process must be able to adequately measure the results of the implemented changes in order to pursue better results over time. This is no different for mining companies. When it comes to blasting, an accurate fragmentation analysis can correlate blast design and rock mass parameters to particle size distribution, enabling us to further analyze the correspondence of specific design patterns, applied to specific rock mass properties and the result in measured fragmentation indicators, such as P80 and fines percentage.

Sep 30, 2022

By T. Abu Leil

A new class of ternary Mg-Sn-Ca alloys is being developed to address the dual demands of corrosion and creep resistance at service temperatures. While tin has proven to enhance the corrosion resistance, calcium is expected to significantly increase their creep resistance of binary magnesium alloys. Their effects in ternary magnesium alloys are not yet known. The series of alloys studied has Sn and Ca in the ranges 3-6% and 1¬2%, respectively. The results indicate that these alloys have two-phase structures with CaMgSn phase dispersed in a matrix that is predominantly a solid solution of magnesium. The corrosion behavior of these alloys has been investigated by means of salt spray tests and potentio-dynamic measurements. Creep behavior of these alloys was measured at a temperature of 135 C under an applied compressive stress of 85 MPa. Scanning Electron Microscopy with Energy Dispersive X-ray facility and X-ray Diffraction techniques were used to characterize the microstructures. The results indicate the prospect of designing alloys that can provide optimum combinations of corrosion and creep resistance by adjusting the relative compositions of Sn and Ca in the system.

Jan 1, 2006

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

By O`Donnell. P. J.

THE modern coal cutter is a highly developed, and to a certain extent a somewhat complicated, machine. The requisite power to cope with conditions as found must be generated by the motor with due regard to limitations in the matter of dimensions and weight. This imposes the necessity of relatively high speeds of rotation. Any factor external to the machine proper which tends to reduce the load on the motor and gearing is most important. Experience has proved that close attention to the question of cutter-chain details undoubtedly results, in practically every coal-cutting operation, in increased efficiency and reduction of power and maintenance costs. The chain is the unit of the coal cutter which most greatly affects the economical operation of the machine, and only by due consideration of conditions and by the proper selection of the right chain can best results be expected; also, intelligent care of the chain while in operation is essential if it is to give its best service. The chain is the part of the machine that carries the pick boxes or blocks, which are connected to each other by a pair of chain links. The power to drive the chain is trans-mitted by a sprocket. The chain runs in guides supported by a rigid member called a 'jib'. Figure 1 shows the various parts mentioned. The first requirement of a chain is that it cut the coal as fast as possible. The second is that it do so economically. Economy of cutting can conveniently be divided as follows: (1) Economy in power used. (2) Economy in pick life. (3) Economy ' in chain life. ( 4) Economy in jib life. (5) Economy in labour for maintenance.

Jan 1, 1936

By M. J. Beus

The Bureau of Mines, under a cooperative agreement with Hecla Mining Co., is conducting a rock mechanics study of the 6,200-ft-deep circu-lar, concrete-lined Silver Shaft in northern Idaho. The objective of the project was to instrument and evaluate lining behavior and rock de-formation when a deep shaft is constructed in a high in situ stress field and anisotropic rock mass. Rock mass displacements were moni-tored with multiple-position borehole extensometers. Liner stress and strain were measured with concrete pressure cells and embedment strain gauges. Field data from the 5,955-ft test level show that rock displacement is controlled by rock mass anisotropy. Liner stress and strain levels reflect the high in situ stress field as well as nearby station and raise construction. Maximum stresses measured in the lining, as a result of shaft excavation, are about one-third of its compressive strength. Subsequent loading pocket excavation resulted in signifi-cantly increased stress and strain levels in the liner. Continued monitoring and preliminary analysis of the data indicate that concrete-lined, circular shafts are stable for the high, unequal horizontal stress fields and rock anisotropy encountered in deep-level mining. Adjacent development work can be expected to significantly alter the initial stress and displacement conditions.

Jan 1, 1984

By J. P. Zannaras

If we assume that testing of the model started at time t1, that time t2 was the instant at which the elastic limit of the material was passed at the points of the maximum stress, and that at time t3 the failure of the model was completed as shown in the typical photograph (Fig. I), then actually the photograph shows the final results of what took place between time t2 and t3. By the principle of similitude all conclusions drawn from the behavior of the model were applicable and valid for actual mine roofs up to the time t2 after time t2 motions and friction came into play during the destruction of the model. The events between t2 and t3 and the photograph itself are not representative of the events expected in an actual mine roof unless corrections imposed by the principle of similitude are made. It can therefore be stated that all conclusions and observations of the author from the photographs are applicable only to his small-scale experiments and not to actual mine roofs. Without investigation of the true stresses or the combined maximum stress induced in the beds it has been assumed by the author that failure occurred solely due to bending stress caused by loading of the beds. (The author states that D was taken to be the theoretical strain given by elementary beam theory.) Fig. 1 shows that the beds were clamped together. This clamping was necessary to prevent slipping of the beds due to the horizontal shear. However, this clamping caused an uncontrolled and undertermined com-pressive stress S at the end of the beds, and this com-pressive stress caused a true tensile stress ?S (? PoiS-son ratio). This true tensile stress combined with the tensile stress produced at the end of the beds due to loading (fixed beam uniformly loaded), and the horizontal shear which is maximum at the end appears to be the most probable maximum stress produced in the beds. It is therefore evident that the author in performing this experiment has introduced stresses in the model not existing or dissimilar to actual mine roofs, and therefore his conclusions may be applicable to his small-scale experiments but inapplicable to actual mine roofs. Louis A. Panek (author's reply)—The discusser's difficulty is related to mechanics of materials rather than similitude. The effect of time did not enter into the tests in any way, being simply excluded from consideration in this study, because all quantitative results entering into the design equations are based on measured (between time t1 and time t2) bending strains that are well below the breaking strain (i.e., in the elastic range) for the model material. Time does not become a significant factor until the rock stress reaches 80 to 90 pct of the breaking stress." The objective of this investigation was not to predict that bolted roof will fail after time t, but was instead to develop a safe roof, that is, roof in which the bending strain is much less than (say less than 50 pct of) the breaking strain. The models tested to failure had no direct bearing on the design equations. Although for some rocks time may influence the magnitude of stress or strain at which fracture occurs, breaking stress or breaking strain values were not employed for any purpose in this investigation. Tests to failure were made only to obtain additional evidence regarding the behavior of the bolted laminae' as evinced by the locations of the cracks. As stated in the last paragraph of the paper, if one wishes to predict the time or stress conditions for which the roof will fail, additional information is required. The reason for clamping the laminae is to make them behave liked clamped beams, which closely approximate the clamped-plate condition of the actual mine roof beds (Ref. 5, p. 1; Ref. 6). The writer has previously demonstrated that the bending stresses induced by centrifugal loading in a clamped model beam are in agreement with those predicted by theory;' hence clamping has no significant effect on the bending ,trains measured during a test. Moreover, actual ,in, roof beds are likewise subject to a clamping effect due to weight of superincumbent strata carried by the pillars or ribs on each side of the opening. It is emphasized that this study was restricted to evaluating only the reinforcing effect produced by the bolts. Procedures employed in the experiments and in the data analysis were such as to deliberately exclude the effects of other factors. The objections offered are therefore invalid,

Jan 1, 1957

By Bill Tucker, Mike Black

"PROJECT OVERVIEW Crossrail, Europe’s largest construction project, will increase London’s transportation capacity by 10% when it opens in 2018. The Crossrail scheme is a combination of surface and underground railway that stretches 118km east-west through central London from Reading, Berkshire and Heathrow airport in the west to Shenfield, Essex and Abbey Wood in the London Boroughs of Greenwich and Bexley in the east. Crossrail will serve 40 stations, ten of which are new, and bring 1.5 million people within 45 minutes commuting distance of London’s key central business districts. 21km of the Crossrail route comprises twin-tunnels beneath the heart of central London. It is the central section of the route, and the challenges that had to be overcome to construct its tunnels under the historic capital that forms the subject of this paper. The route of the Crossrail tunnels can be seen in Figure 1. These tunnels weave their way through the city’s underground landscape, linking eight new underground stations which connect to the existing London Underground network, providing interchanges with nine existing lines as well as the National Rail and Docklands Light Railway networks.Crossrail began construction of enabling works in May 2009 and launched the first of eight tunnel boring machines (TBMs) in May 2012. 42km of major tunneling work was completed in May 2015, and included 11km of sprayed concrete lined tunnels at the five mined stations (Bond Street, Tottenham Court Road, Farringdon, Liverpool Street and Whitechapel) in addition to the bored tunnel sections. The remaining three sub-surface stations at Paddington, Canary Wharf and Woolwich were constructed as large open boxes prior to the TBMs passing through. Crossrail, Ltd. is a special purpose company formed by the project’s joint sponsors, Transport for London and the Department for Transport, to manage design, construction and commissioning of the project. In 2009, Crossrail engaged Bechtel Ltd. as its delivery partner and a joint venture, Transcend (comprised of CH2M, AECOM and the Nichols Group), as its programme partner. The project is being managed by an integrated programme management team which is staffed by Crossrail and its partners. The railway, when opened, will be operated by Rail for London. With tunneling completed in accordance with the project’s master control schedule, the new railway is scheduled to commence dynamic testing in late 2017, with a phased opening of the tunneled sections and stations through Central London in 2018."

Jan 1, 2016

By L. M. Demers, D. C. Kuhn, N. El-Ayouby, C. F. Stanley

"Oxygenated metabolites of arachidonic acid (MJ are produced by the alveolar macrophage (AM) and have been shown to mediate inflammatory reactions. We therefore assessed the production of eicosanoids by AM harvested from the lungs of rats ex· posed to a bituminous coal dust for 2 wk in an inhalation chamber in order to determine if AA metabolism was altered in a manner that may promote an inflammatory response in the lung. Exposure to coal dust resulted in a 66% increase in the number of AM harvested, an increase in thromboxane A2 (TxA;i) and leukotriene 84 (LTB,j) production to 222% and 181% of control values, respectively, and a decrease in prostaglandin E2 (PGE:i) production to '62% of control values. In AM harvested from rats allowed to breath clean air for 2 wk following coal dust exposure, PGE2 production returned to control levels but TxA2 and LTB4 production remained elevated. The TxA2 synthesis inhibitor UK 38,485 reduced TxA2 production in dust-exposed AM both immediately and 2 wk following exposure. Thus, exposure of rats to coal dust significantly alters the metabolism of AA in AM, with potentially important aspects of AA metabolism remaining altered even after a 2-wk recovery period. Based on the established role of eicosanoids in inflammatory and fibrotic processes, these results suggest that the alteration of AM eicosanoid production as a result of the inhalation of coal mine dust may be an important factor in the pathophysiology of coal workers' pneumoconiosis.The authors are grateful to Joan Greenwood and Barbara Scheetz for their excellent technical assistance and to Brenda Pavone for the preparation of the manuscript. This research was supported by the U.S. Department of The Interior's Mineral Institute Program administered through the Generic Mineral Technology Center for Respirable Dust under grant 1135142.Request for reprints should be sent to Douglas C. Kuhn, Ph.D., Department of Pathology, The M.S. Hershey Medical Center, Hershey, PA 17033.INTRODUCTIONPulmonary alveolar macrophages (AM) are activated by foreign particles and microorganisms that enter the small airways (Kass et al., 1966; Herscowitz, 1985). This defensive reaction involves phagocytosis, lysosomal enzyme release, and the generation of reactive oxygen species by the AM (Snella, 1986; Rich et al., 1987). A number of agents, including phorbol esters, zymosan, adenosine diphosphate, organic hydroperoxides, and calcium ionophore, have been shown to activate the AM in vitro (Badger, 1986; Marshall and Lands, 1986; Snella, 1986). The AM response to these activators appears to be mediated in part by the oxygenated metabolites of arachidonic acid (AA) (Bertram et al., 1988; Demers et al., 1987; Mcleish et al., 1987).The AM may metabolize AA through cyclooxygenase- and lipoxygenase- catalyzed pathways to produce a variety of eicosanoids including prostaglandin (PG) E2, thromboxane (Tx) A2, leukotriene (LT) B4, LTC4, LTD4, and several hydroxyeicosatetraenoic acid derivatives (HETEs) (Willis, 1970; Camp et al., 1983; Poubelle et al., 1986). The production of these eicosanoids may enhance the. defensive ability of the challenged lung since they stimulate chemotactic cell recruitment to the site of invasion, enhance extravasation of circulating immune cells, and promote local vasodilatation. However, continued stimulation of the AM population, with the consequent production of proinflammatory eicosanoids, may ultimately enhance the disease process by contributing to chronic bronchoconstriction, fibrosis, and the persistent release of toxic oxygen species."

Jan 1, 1990

Willet G. Miller, Toronto, Canada (communication to the Secretary): In his interesting paper Mr. Lindgren says: " As to ultimate results, it would seem as if we should be justified in concluding, with Prof. Suess, that the gold-supply of the world will gradually decrease if no further important improvements are made in the processes for the extraction of this metal; but regarding events so far distant no predictions may safely be made." It seems to the writer that no very important improvements require to be made in order at least to keep up the present production for many years to come. In many parts of the world there are large deposits of auriferous material which can be worked if present conditions are slightly changed. In the territory occupied by the Archean protaxis of the Province of

Jan 1, 1903

By Rajat Gangrade, Haotian Zheng, Jarrett Smith, Daniele Nebbia, Mike Mooney

The application of artificial intelligence (AI) to improve tunnel boring machine (TBM) operations requires a significant amount of information to train robust performance prediction models, e.g., for tunneling-induced settlement, productivity, tool wear, etc. This paper presents the AI framework applied to the North-East Boundary Tunnel (NEBT), the largest component of the Clean Rivers Project in Washington, DC. The paper focuses on required elements for real-time AI use to estimate tunneling-induced ground and building deformation and cutter tool wear. Keys to the framework include defining the necessary quantities of data required as well as the process of windowed training, validation and model testing. To date, the models developed for ground deformation and tool wear show satisfactory performance when compared to observed field observations during tunneling.

Jun 13, 2021

By K. Kalgraf

The motion and stability of the metal/electrolyte interface is determined by Navier-Stokes equation. The equation may be decomposed into two independent equations by taking the divergence and curl of Navier-Stokes equation. The divergence determines the motion and stability of magneto-gravitational waves. The curl of Navier-Stokes equation gives an equation containing only velocity and magnetic field, and states that the magnetic field is driving a circulation pattern in the cell, and this magneto-flow has its own stability conditions. The waves are called Alfven waves, and their stability properties are related only to magnetic field and geometry.

Jan 1, 2001

By S. K. Schwartz

"This paper describes the general layout of the environmental monitoring scheme at Devco 's No. 26 Colliery, including wall face ventilation, fan performance and methane drainage, and then goes on to discuss the sensors, the outstation layout, the surf ace control room and the protection of the system.IntroductionCape Breton coal mines have been pioneers in the use of the latest technology in mining coal on this continent. To mention just one example, continuous methane monitoring at the coal face was started in 1976 and the idea of automatically stopping the face conveyor during high gas levels using the face signalling system was conceived and developed by CBDC engineers.With the introduction of remote environmental monitoring, No. 26 Colliery will be the first underground coal mine in Canada and possibly in North America to have computer-based comprehensive environmental monitoring.Traditionally, surveillance of the mine environment has been based mainly on periodic checks by portable or hand-held monitors. Although this method proved adequate, it has some limitations, namely:1) restricted 'number of observations and samples;2) relatively long time between taking measurements and availability of results for assessment.With remote monitoring, the above limitations are overcome because (a) monitoring is continuous and (b) monitored data are updated quickly (typically 5-7 sec.). Remote monitoring also provides a centralized 'information center' at the surface from where the entire mine environment can be monitored. Details of modes in which data can be displayed and features available at the location will be discussed later in the paper."

Jan 1, 1982

By George F. Becker

A Nere record of Emmons's professional career would very inadequately represent the man. That he was eminent mc know, and our successors will realize in due time; but they must depend upon us for knowledge of a singularly ~vholesome, modest, unselfish personality, and of a character that did honor to a profession in which trustworthiness is indispensable. Those members of the Institute who met Emmons are his friends, and I never knew .one of these who was not the better for that friendship. Emmons was born in Boston, Mar. 29, 1841, the son of Xathaniel H. and Elizabeth (Wales) Emmons, and was named Samuel Frankliri after an ancestor who was of the sarne family as Benjamin Franklin. He took the degrcc of Bachelor of Arts at Harvard in 1861, and soon afterwards went abroad to complete his education. From 1862 to 1864 he attended the courses at the fieole Impkriale des Mines at Paris, Elie de Beaumont arid Daubrke being among his professors. The year 1864-1865 he spent at Freiberg under Cotta and other famous teachers; after which he spent another year in traveling through Europe. Like many other renowned geologists, he approached his ultimate profession from its economic side, and was thus from the first imbued with a sense of high responsibility in the promulgation of scientific opinions or conclusions. With hypotheses which were interesting merely because they were ingenious or even plausible, he would have nothing to do. In 1867 he joined the Geological Exploration of the Fortieth Parallel at its organization under Clarence King, serving at first as a volunteer, but soon receiving a regular appointment. This expedition was the first one of purely geological character sent out by the United States government. As Emmons has shown in his admirable presidential address on " The Geology of Government Explorations," its work was founded on a com-

Jan 1, 1912

By L. W. Saperstein, Y. J. Wang

The development of computer programs to solve complex ventilation networks has reached a point of refinement where these programs become a necessary tool of the ventilating engineer. Such a program is presented. This program has an increased efficiency over its predecessors; it also includes the important facility of fixed quantity branches. This is in addition to the earlier capabilities of free-splitting, internal or external fans, and natural ventilation pressures. The program is written in Fortran IV with double-precision arithmetic and is listed here. Sample problems with input and output are also given. The recent, and presumably continuing, official interest in mine safety is bound to result in more stringent control requirements for ventilation. Anticipating this requirement, the Dept. of Mining, The Pennsylvania State University, has developed a computer program for the solution of complex mine ventilation networks. It is the opinion of this department that the program has sufficient merit to warrant its use in normal industrial operating conditions. Although the undergraduate mining engineering students of this department are routinely trained to use the program, it was felt that this training did not present a fast enough means of dissemination; consequently, this paper was written. The conception of the program is not new;1; however, the present version incorporates features that changes it from a scientific endeavor to a useful operating tool. These features include those of earlier programs, such as free-splitting, external or internal fans, and natural ventilation processes plus the important ability of handling fixed quantity branches, and of increased efficiency giving reduced cost. The facility for fixed quantities will be discussed in more detail. The solution of any network depends upon satisfying Kirchchoff's laws. These state that the sum of flow at any junction is zero, and that the sum of the pressure drop in branches totals the pressure drop in the mesh constituted by those branches, that is that the pressure drop around any mesh is zero. The terminology is derived from Synge," and is, in fact, that used by Topologists. A branch is any airway of uniform characteristics; a junction is where two or more airways meet (the minimum number of two airways is useful for describing the point where a low resistance airway changes into a high resistance one due to some physical constriction); a mesh is a path, along some branches, that returns on to itself, but does not need to traverse the same branch twice in order to do so; and a tree describes all those branches in a network which, while connected through all the junctions, do not form any meshes. Obviously the branches-in-tree are open-ended and can be shown to be one less than the number of junction (J-1). The branches-out-of-tree, also called basic branches, are equal to the number of basic meshes and are M = N — J + 1, where M is the number of meshes and N is the number of branches. The major difference between this network and an electrical one is that the law attributed to Atkinson for pressure drop is utilized rather than Ohm's law. Atkinson stated that the pressure drop (potential) is equal to a resistance factor multiplied by the quantity squared. This is written H = RlQlQ where H is the head loss. Q? is written in this factored fashion so that H will always have the same sign as Q. A negative sign is used to indicate that flow in a branch is opposite to that of its containing mesh. A mesh takes the direction of its basic branch. Utilizing Atkinson's law in Kirchchoff's second law and bearing in mind that the first law must remain satisfied, the program will determine all quantities, or head losses as they are related, for the branches of the network. The program uses a Geuss-Seidel form of in-teration, starting from an arbitrary Q and using a correction factor of the type first suggested by Professor Hardy Cross' that will handle the nonlinear equation of Atkinson's law. A fuller description of the interative process is included in Wang and Hartman.' Iteration continues until the correction factor is less than or equal to a preset error (E) or until a maximum number of iterations (MAXIT) have been reached. Utilizing an E of 50 cfm, sample problems have had rapid solutions. Rapidity of solution is also ensured by the method of selecting meshes and basic branches. This is done by the computer, which chooses the highest resistance branches, fixed quantity branches, and those containing fans, as basic branches. Natural ventilation pressures are handled as fans of constant pressure and may be assigned to any branch. The computer will generate a fan characteristic by polynominal fitting if a few operating points from the desired fan are input. A fan may be placed in any branch of the network, except those with fixed quantities. The strength of the present program over its earlier versions is its ability to handle fixed quantity branches. This means that certain branches can have their quantity determined, or preset, by the ventilating engineer. Operating under this constraint, the program will analyze the network and output the pressure change necessary to achieve this desired quantity. A call for positive head loss would require an auxiliary fan; negative head loss would require a regulator. This represents a powerful tool for the ventilating engineer who must insure that certain quantities of air pass across the operating faces or through working stopes. McPherson6 suggested that a ventilation program would be useful for determining in advance which branches were receiving inadequate air, and that subsequent calculations would then indicate the necessary corrections. The present program makes these corrections. Thus the mine manager can know immediately the consequences of changes to his system;

Jan 1, 1971

By B Clements, G Lane

The operations and project environments are very different, but overlap in many areas. The development of mineral processing projects is goal oriented, is schedule focused and is a contractual environment. The operating environment for a mineral processing plant is oriented around longer-term commitments, focused on delivery against budget expectations, and an environment heavily influenced by long-term personal relationships, community relationships, and people issues.Further contrast is evident in the way expenditure is managed. Projects commit large amounts of money quickly to meet schedule-based objectives. Operations manage expenditure to minimise operating costs and are able to, or are forced to delay decisions on large expenditures. However, these two environments need to come together in many ways, ranging from greenfields plant handover to a new operations and maintenance crew, to day to day interaction and management of brownfields projects, often in close proximity.This paper considers the different perspectives people bring to projects and early operations, including the advantages and disadvantages of æoperationsÆ input to a project and models for managing value adding during project development, implementation and debottlenecking.CITATION:Lane, G and Clements, B, 2012. Operations versus projects - How do people think and what are the implications?, in Proceedings 11th AusIMM Mill OperatorsÆ Conference , pp 11-16 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By T. L. Joseph

The size and accessibility of the Minnesota manganiferous iron ore deposits make them attractive as a potential source of erromanganese, which is essential in the production of steel. For several years the Bureau of Mines has been conducting experiments to determine the feasibility of producing ferromanganese from these ores by a three-step process which involves (1) the smelting of the ores in the blast furnaoe to produce a high-phosphorus spiegel; (2) the treatment of the spiegel produced from step 1 in an electric or open-hearth furnace to separate the manganese from the phosphorus and the iron; and 3) the smelting of the high-manganese slag from step 2 to produce forromanganese. The details of the first two steps of the process and the results of tests with the experimental furnaces Lave been given in previous reports.5 The m$ or part of the experimental work on the second step has been conducted in a half-ton open-hearth furnace. Some preliminary tests showed, however, that the electric furnace has some distinct advantages over the open hearth for producing, from high-phosphorus spiegel, a slag containing from 45 to 55 per cent manganese and phosphorus and iron in amounts required for ferro-grade ore. The electric furnace tests described in this paper were made to get more information as to the possibilities of the electric furnace in connection with this problem and to study the fluxing effect of alumina on high-manganese slags. Herty, Conley, and Royer have reported' results of laboratory tests which showed that slags containing from 60 to 75 per cent MnO, from 8 to 10 per cent S102, and small amounts of CaO MgO, and FeO, were sufficiently fluid at 1,450° to 1,550° C. to pour readily if 12 to 14 per cent alumina was present. With a normal A1203 content resulting from the A1203 in the

Jan 1, 1931

By J. G. M. Mukoya, B. Adebayo

"This work was carried out to determine the influence of rock properties and drilling machine parameters on the penetration rate at the SJ pit of Rössing Uranium Mine, Namibia. Rock properties (uniaxial compressive strength, tensile strength, and modulus of elasticity) of samples collected were determined in the laboratory. Drilling experiments were conducted in which feed pressure, air pressure, rotary speed, weight on the bit, and torque were varied to measure their effect on the penetration rate. The uniaxial compressive strength varied from 90–180 MPa for layered marble-quartzite and banded gneiss. Increases in feed pressure, weight on the bit, and rotary speed beyond the optimum level led to a decrease in penetration rate and caused the drill bit to ‘stall’. Results of the study revealed that penetration rate increases with an increase in the feed pressure and air pressure. After reaching a maximum value, the penetration rate begins to decrease despite increasing feed pressure. A very high torque causes the drill bit to stall, since the feed pressure is too high and the air pressure is not sufficient to remove the cuttings from blast-hole at maxium bailing velocities. The average penetration rate varied from 19 to 45 m/h for phase 2 of the pit, and from 17 to 68 m/h for phase 3. The optimum drilling machine parameters obtained in phase 2 and phase 3 were slightly lower than those currently being used at the mine. The trials of the optimum machine parameters will assist in reducing the cost of drilling, which varied from N$29.48 to N$36.31 per metre for the tricone bit. IntroductionDrilling and blasting contribute most to the operational cost in opencast mining and have the potential to influence the cost of downstream operations (Aipanda, 2011). The drillability of rocks depends not only on the rock properties, but also on the drilling tools and operational variables. In rotary drilling, rotational speed, thrust, and flushing are the operational variables, and are known as the controllable parameters. Rock properties and geological conditions are the uncontrollable parameters. Although, many attempts have been made to correlate drillability with rock properties, the rock characteristics affecting rotary drilling have not been entirely defined (Hartman, 1962; Kahraman, Bilgin, and Feridunoglu, 2003). The drill bit is forced into a rock surface from the rotary power head, hence creating stresses and cracks at the bit-rock interface. The performance of a particular bit in any formation i"

May 1, 2019