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By J. Duncan Keppie

"Auriferous quartz veins occupy zones of dilation. Foldgenerated dilation zones are systematically distributed and are dependent upon the folding mechanism. Comparison of natural and theoretical folds indicates that different mechanisms operated in the Halifax and Goldenville formations.In the slates of the Halifax Formation, the folds are of similar type and internal strain is most intense in the limbs. This internal strain is probably accommodated with little or no dilation.In the meta-sandstone and slates of the Goldenville Formation, a combined flexural and tangential longitudinal strain mechanism, modified by pure strain, produced the folds. Tension fissures produced by this mechanism are: (a) saddle 1'eef veins in slate horizons, (b) veins normal to bedding in meta-sandstone layers in the fold hinges,(c) veins along faults in the cores of tight fold hinges and (d) zones of en- échelon veins in slate honzons in the limbs of folds. Because veins in fold hinges (a, b and c above) account for most of the gold production in the Meguma Group, other factors controlling the distribution and size of these veins are summarized below.1. The size of saddle reef veins is controlled by the curvature of the fold hinge. Thus, a Curvature Index greater than 600 degrees indicates a promising prospect, where"

Jan 1, 1976

By AIME AIME

HOWARD H. PRESTON, professor of economics and business at the University of Washington, presented a paper before the North Pacific Section, A.I.M.E., on Jan. 23, on the "Economic Aspects of Gold and Silver." He carefully reviewed recent governmental actions that have affected those metals and gave an interpretation of their effects. A brief excerpt from his address; follows: Including the proclamation of March 6, 1933, the principal steps of the present Administration which have carried the United States off the gold standard and led up to the present program have been: (1) The Presidential proclamation of March 6 controlling gold. (2) The monetary sections of the Emergency Banking Act of March 9. (3) Mobilization of gold under Executive orders issued March 10 and April 5. (4) The gold embargo by Executive order, April 20. (5) The controlled inflation bill, May 12. (6) The joint resolution abrogating the gold clauses, June 5. (7) The Executive orders on newly mined gold, Aug. 28. (8) The President's radio address of Oct. 22 and the R.F.C. gold-buying program. (9) New anti-hoarding order calling in small holdings of gold, Dec. 28, 1933 and Jan. 15, 1934. (10) Nationalization and revaluation of gold' (Message to Congress, Jan. 15).

Jan 1, 1934

By M. Ataee-pour, S. E. Jalali

So far, a large number of algorithms have been developed for the optimization of pit limits, most of which follow deterministic rules. In this paper, a new algorithm is introduced, which follows a probabilistic logic using the Markov chain process. The algorithm is implemented on a transition matrix that corresponds to the 2D conventional economic block model of the mining area. The probability of mining a block is proportional to the desirability it may provide. Applying this algorithm, the probability of mining each block is obtained, and finally, the optimum pit limits are defined as the pit, which provides the highest probability of mining. In order to validate the proposed model, a numerical example is given and the results of the algorithm are compared to those of a dynamic programming algorithm. A 2D analysis of the problem is discussed in this paper. Although dealing with 3D problems requires larger size matrices, the optimization method is the same and the algorithm does not need any smoothing.

Jan 1, 2006

By Stanley A. Feitler

This Bureau of Mines report deals principally with the resources and economic aspects of feldspar in the United States east of the Mississippi River. Although in a strict sense, all phases of the feldspar industry affect its economic structure, emphasis in this study is on supply, demand, and marketing. Although feldspar was originally mined for use in the manufacture of pottery and other ceramics, the glass industry, which began to use feldspar in the mid-1920's, now consumes more than half of the annual output. Most mining is open cut, and the methods used are similar to those used in mining crushed b stone. Excess plant capacity has been chronic, and production is usually about 30 percent of capacity fur the industry as a whole. Since 1947, feldspar consumption has grown more slowly than the average for all U.S. industry. This has fostered intense competition, especially for the glass market. Prices have not kept pace with inflation, and profits are small. The trend of consumption through 1970 for glass feldspar is expected to be upward; less rapid in consumption of ceramic feldspar is anticipated.

Jan 1, 1967

By S. Burks

This paper develops the themes explored by the authors at the Fourth International Platinum Conference,. Optimization techniques can be used to significantly increase the value of mining businesses by enabling better long-term planning decisions. Open pit and underground mine design, mine scheduling, cut-off grade and blending, stockpiling, and the linking of these to flexible elements of the metallurgical recovery processes are all evaluated together. Transport or sale of intermediate products and the requirements of the product metal markets can also be considered. Experience shows that net present value (NPV) can potentially be increased by 5-35 per cent or more, usually even before the expenditure of significant amounts of project capital. The case studies presented include: > An existing operation with multiple open pits and PGM concentrators linked to offsite downstream processing facilities, and with infrastructure constraints for which the scheduling of current operations and the potential for expansion were investigated > An existing operation with an integrated portfolio of mines, concentrators, smelter, and refinery, for which the various possible sources of ore for processing were prioritized to match the downstream process plant constraints and the product markets > An underground operation in Zimbabwe for which the optimum mining width was calculated and expansion plans were evaluated > An underground mine with many separate mining sections, for which a revised schedule was developed aiming to keep the shaft system and processing plant at capacity with the highest net value material available at any time throughout the life of mine. In the concluding section of the paper, a few brief notes are included suggesting how the strategic recommendations from enterprise optimization studies may be implemented by the owner's team.

Jan 1, 2013

On April 5, the potlines at Consolidated Aluminum Corp.'s 35,000 ton-per-year primary aluminum smelter at Lake Charles, La., were frozen when natural gas lines were accidently cut by a dredge. Full production is expected to resume in 3 to 4 months. Three primary aluminum producers announced plans to restore much of the idled capacity in the Pacific Northwest as a result of a special power allocation by the Bonneville Power Administration. Reynolds Metals Co. planned to bring a total of 40,800 tons per year of capacity back onstream at Troutdale, Oreg., and Longview, Wash. The Aluminum Company of America (Alcoa) will restart half of a 23,500 ton-per-year potline at Vancouver, Wash. Kaiser Aluminum & Chemical Corp. planned to restart a 27,500 ton-per-year potline at Mead, Wash., and to bring an additional 10,000 to 20,000 tons per year back onstream at Mead and Tacoma, Wash.

Jan 1, 1980

By S. L. Windes

This report presents a tabulation of the physical and petrographic properties of Over 100 rock types from operating mines or mineral-investigation projects. The physical properties include the following: Apparent specific gravity Apparent porosity Compressive strength Flexural strength, (modulus of, rupture) Impact toughness Abrasive hardness Scleroscope hardness Modulus of elasticity (Young's modulus) Modulus of rigidity Specific damping capacity Longitudinal bar velocity

Jan 1, 1949

By Stanley A. Feitler

This Bureau of Mines report deals principally with the resources and economic aspects of feldspar in the United States east of the Mississippi River. Although in a strict sense, all phases of the feldspar industry affect its economic structure, emphasis in this study is on supply, demand, and marketing. Although feldspar was originally mined for use in the manufacture of pottery and other ceramics, the glass industry, which began to use feldspar in the mid-1920's, now consumes more than half of the annual output. Most mining is open cut, and the methods used are similar to those used in mining crushed stone. Excess plant capacity has been chronic, and production is usually about 50 percent of capacity fur the industry as a whole. Since 1947, feldspar consumption has grown more slowly than the average for all U.S. industry. This has fostered intense competition, especially for the glass market. Prices have not kept pace with inflation, and profits are small. The trend of consumption through 1.970 for glass feldspar is expected to be upward; less rapid growth in consumption of ceramic feldspar is anticipated.

Jan 1, 1967

By Kenneth Wardell

Those flat lying, bedded or replacement, non-fossil fuel deposits which exist within the U.S.A., and which are amenable to longwall mining, are identified by reference to three principal factors associated with their physical/geological environments. These are their depth, extent and structural continuity. Technical feasibility is assessed in relation to the likely cutting speeds which can be achieved in the identified minerals with existing longwall shearer machines. Economic comparisons are made between traditional mining operations in those deposits for which technical feasibility is demonstrable. Continents are made concerning those technical deficiencies which appear to preclude the application of existing longwall equipment to the identified deposits and suggestions are made regarding the lines of research aimed at improving longwall technology.

Jan 1, 1978

By R. M. Santmyers

The pigments, whose colors are due primarily to iron exides and iron hydroxides, comprise a variety of yellow, brown, red, and sometimes black paint-coloring agents, both natural and artificially prepared. The natural pigments in this group include ocher, umber, sienna, mineral paints, paint rock, and mortar colors. When the natural color or tinting power--either in the raw state or after treatment--is too weak, these pigments may be "forti- fied" or strengthened. Ocher, umber, and sienna, rhile often described as "iron oxide pigments," are also known as "earthy" rigments. Inasmuch as the iron content of these pigments is, in general, somewhat lower than that of other iron oxide pigments, the ochers, umbers, siennes, and other brown earth pigments are not discussed in the present paper. In addition to a discussion of natural or artificial pigments whose color is due to the presence of iron oxide in some form, this paper contains data on mortar colors, which are medium or low grade pigments used for tinting mortar, cement, and concrete. A great variety of materials are used for theso purposes, including "blue billy" (residue left from roast- ing pyrite), ground slate and shale, and even culm from coal washeries. Dur- ing the past three years, there has been a definite trend among the producers of iron oxide pigments to push the sales of the better grades of colors for tinting mortars. Due to the amount of low-grade coloring matter that is re- quired to impart a strong color to concrete (in soro cases as high as 15 per cent of pigment is necessary) the strength of the cement may be materially impaired. The addition of some 2 per cent of the higher grades of iron oxide to the concrete mix imparts a brighter and stronger colcr, does not weaken the material, and in the end is not as expensive as the low-grade pigments formerly used. Iron oxide pigments occur in nature in various shades and colors, but the red pigments are the most important and account for the larger part of the total red pigments used.3/ The nomenclature of these red pigments is involved and the names given to them are descriptive of the shade rather than of origin, method of produc- tion or chemical composition. In most cases the red pigments under this class may occur naturally or may be produced by heating hydrous iron oxide pigments such as yellow ocher to a sufficiently high temperature to drive off the water of composition. They may also be prepared by fortifying naturally-occurring pigments with stronger natural or synthetic oxides or with coal-tar dyes (e.g. alizarine lake), Most of the mineral reds derive their color from the presence of ferric oxide (Fe2O3), the mineral hematite. This may be present in relatively small percentages, as in the red slates and shales, or it may constitute as much as 90 per cent or more of the material, as in Spanish red. The principal iron oxide pigments used in the manufacture of paint are discussed in the following pages.

May 1, 1932

By P. Nicholls

THOUGH the burning of fuels extends far back into antiquity, and though fuel beds are the most common and widely distributed example of chemical actions and engineering practice, there has been little attempt to group fuel beds by types or to define the principles associated with them. This paper does not profess to cover completely the subject of fuel beds. It suggests some of the over-all principles of the two more com-mon types. No new investigational data are included, but the deduc-tions are largely based on a recent publication of the U.S. Bureau of Mines1. DEFINITION OF TYPES There are three primary types of fuel beds: (1) Underfeed, in which the fuel and the air move in the same direction; (2) overfeed, in which the fuel and the air move in opposite directions; (3) crossfeed, in .which the fuel and the air move at right angles to each other. The principle that fixes the type is the relation between directions of the flow of fuel and of air. Fig. 1 shows the three types diagrammatically. All other types are compounded of these three in a simple or more or less complex manner. It does not follow that these three type designations are limited to the methods used in representing them in Fig. 1; they may be turned in any direction, and as long as the relative directions of the fuel and air are the same the type is not changed. For example, A as shown resembles a pot-type stoker, but the air and fuel can move downward as in the so-called smokeless heating boiler furnace. Also, C can be placed hori-zontal, as in chain-grate stokers. For this reason, the terms used to designate the three types are not all that could be desired; more logical ones could be coined, but those used probably are satisfactory until the discussion of fuel-bed types becomes more common.

Jan 1, 1935

By Zay Jeffries

AN acute current shortage of copper, with the prospect that conditions may become worse, indicated by Office of Production Management information. Present estimates of copper requirement for defense indicate that nearly all the available metal will be required in the future for this purpose. Severe dislocations are, expected, but the objective is to distribute the copper available for civilian use in such a manner as to minimize these dislocations. The advisory committee on metals and minerals has been asked for a suggestions which may be helpful in meeting this situation.\

Jan 1, 1941

By Hazel Lyman Nickel

Daring to try where others had failed, Herbert and Lou Henry Hoover translated from the Latin the principal (and first) textbook on the mining and metallurgical profession, De Re Metallica, 1556, which had been in use for two centuries and then had lain dormant for 350 years in a language unreadable except by a chosen few. Thus the Hoovers enriched the English tongue with a vitally important contribution to history in the fields of mining, metallurgy, and chemistry. To them it was a joint hobby, because they were actively interested in the beginnings of the mining profession in which they had both been trained. Illuminating the years of toil to perfect this translation shone their ideal of service to humanity, since, in the Preface, they refer to their task as "a labour of love", which had to find the moments for its execution in night hours, weekends, and holidays, extending over a period of about five years. And they add: "If the work serves to strengthen the traditions of one of the most important and least recognized of the world's professions, we shall be amply repaid". While a student at Stanford University, during the years of 1891-95, Herbert Hoover had become familiar with a copy of this Latin mineralogy classic, De Re Metallica, a rare book in the private library of Dr. John C. Branner, at that time head of the department of geology and mining. Another Stanford student in geology was also examining and studying the ponderous volume of twelve 'books'. She was Miss Lou Henry, of Monterey, who graduated in 1898, and the following year became Mrs. Herbert Hoover. Interwoven through the tapestry of their life experiences gleamed the silver thread of their interest in this mediaeval Latin textbook. Just nine years lacer, the Hoovers had commenced their translation, while they were in temporary residence in London after the seething years in China under the shadow of the Boxer rebellion.

Jan 1, 1949

By Brian M. Harney

The technique of remote sensing, used for many years by earth scientists, is being applied to the detection and monitoring of air pollution. Instrumentation being developed is of a very diverse nature and is effective, Fn varying degrees, at ranges from 1,000 meters to the altitude of a space satellite. This paper describes a number of the recent developments in this new field. Instruments based on spectroscopic, laser, and photographic systems are discussed. Sensors are being developed which utilize correlation spectrometry, interferometry, Raman scattering, Mie scattering, laser line absorption, and simple photographic detection.

Jan 1, 1973

By Alicia O&apos, Overbeck, Reardon

DIFFIDENTLY, because don'ts are rarely greeted with cheers; humbly, because I, myself, have never lined up with the irreproachables, I venture on the subject of manners for the mining camp matron. Mining camps can be divided roughly into two types-the large, opulent settlement that blooms like the rose about a strong mine in full operation; and the puny group of adobe huts, or calamina shacks, or even canvas tents flung down in the wilderness to shelter the gay pioneers of a shining prospect or the shattered survivors of a lost hope. Of the first, I know nothing; but in the second, I have spent some of my best years, and from its curious code of morals and manners, its comic hates and its unreasoning loves, its high impatience and its engulfing kindness, I have charted the narrow .and pitted path which must be trod by the woman who would success¬fully live therein.

Jan 1, 1936

By Edward E. Johnson

The U.S. economy made significant progress in 1984. The current-dollar gross national product (GNP), the market value of the Nation's output of goods and services, increased almost 11 percent over that of 1983 to slightly more than $3.66 trillion (table 1), and the real gross national product increased almost 7 percent.2/ Such rapid growth in real GNP has not occurred since the early 1950's. Real final sales increased only 5 percent during 1984, and real business inventories increased $24.8 billion ($57.9 billion in current dollars). Total employment of 106.7 million was an all-time record, and the unemployment rate declined from 9.5 percent in 1983 to 7.4 percent in 1984. During 1984 the U.S. dollar showed great strength on international markets, contributing to large current-dollar negative net exports of goods and services (-$62.5 billion) and even larger negative net exports of merchandise (-$107.6 billion). The strong dollar and the substantial increase in net imports of goods and services helped reduce U.S. inflationary pressures and provided a major source of loanable funds for financing domestic private investment.

Jan 1, 1985

By George Hope, Brigitte Lacouture

"The Red Dog Mine has increased mill throughput for most years since startup. Although flotation equipment has been added over the last 10 years, the Red Dog metallurgical performance has been restricted by a lack of adequate flotation capacity. Two reduced tonnage trials conducted in 1997 as well as numerous SAG relines have consistently indicated the potential to significantly increase both zinc concentrate recovery and grade with additional flotation capacity. Late in 1999, a new circuit was designed with increased flotation capacity while simplifylng the current circuit, providing for three stages of dilution cleaning, and creating a retreat section. The purpose of the retreat section is to target the more complex particles and allow the chemical environment to be fine tuned for improved iron depression. In total, twentyone (21) Outokumpu OK50 mechanical flotation cells and four (4) 3.66m dia. column cells will be added to the current flotation circuit. The VIP (Value Improvement Program) Mill Optimization project is also addressing thickening, water treatment and power issues and has a total budget of $US105 M. Startup of equipment will be phased in to minimize the impact on current operations and is expected to be complete by the end of Q3-2001.INTRODUCTIONRed Dog Operations started production in November 1989. The mine is located above the arctic circle in northwest Alaska. It is linked by an 80 km road to a port-site facility where the concentrate is stored. Concentrate is shipped to markets throughout the world during the one hundred (100) days of open seas. Typical of sedimentary exhalative deposits, the metallurgy proved to be challenging and coupled with many mechanical shortcomings, the initial few years were very difficult. The start-up issues were slowly resolved and in 1998, a major grinding expansion, the PRI (Production Rate Increase) project, was completed. The project was designed to allow a 40% increase over the 1995 throughput. In 2000 mill throughput was 3,050,000 tonnes to produce a total of 960,000 and 140,000 dry tonnes of zinc and lead concentrates respectively, making Red Dog the largest zinc concentrate producer in the world. To address a shortage of flotation capacity remaining from the PRI grinding expansion, a project designated as the VIP (Value Improvement Program) Mill Optimization project was initiated. The mill optimization project is targeted to produce 1,100,000 tonnes of zinc concentrate at 56% zinc grade and 87% zinc recovery. The project will add twenty-one (21) Outokumpu OK50 (50m3) flotation cells, four (4) 3.66mO column cells and address water treatment, thickening and power generation capacities."

Jan 1, 2002

By HARRINCTON EMERSON

UNEMPLOYMENT is the most ominous shadow ahead of the industrial nations today. Only two great industrial countries are free from unemployment, France and the Soviet Commonwealth. In France the social unit is the family, not the individual. This has saved France. In the Soviet Commonwealth, development is proceeding so rapidly from agricultural to industrial that there is still a dearth of muscle workers in the non-agricultural enterprises. In the other industrial countries unemployment results both from acute temporary recession in industrial activities and from the rapidly increasing substitution of the machine for the man. Temporary recessions can be mitigated, alleviated by makeshifts, often ill considered. Secular recessions due to a fundamental change in the way of accomplishing physical, chemical results cannot be cured by any makeshift. There must be a period of transition. There is therefore before us the three- fold problem, immediate, prosimate and ultimate.

Jan 1, 1930

By W. J. Atkinson

The first recorded discovery of diamonds in Australia was in 1851 in New South Wales. Subsequent prospecting has shown alluvial occurrences of diamond to be widespread through much of the Tasman fold belts of Eastern Australia. Production is estimated to be some 500,000 carats from several small alluvial fields. Despite extensive exploration, though, no primary rock source carrying significant diamond content has ever been confirmed in Eastern Australia. Conversely, diamond exploration of the older Western and Central Cratons of Australia during the past 30 years has discovered 12 fields containing 360 kimberlites, lamproites and lamprophyric volcanic pipes, dykes and other intrusives. Of those, 180 have been confirmed to be diamondiferous. Only one pipe, however, the 1200 Ma high-grade Argyle lamproite and associated nearby alluvials, has proved to be economically exploitable. Its current annual production is 40 million carats valued at about US$400 million. Production from the open pit will be sustainable until at least 2003.

Jan 1, 1995

By E Mare

Recent highly publicised incidences of disastrous containment failures, none more pertinent than the 2019 iron ore tailings dam failure in Brumadinho, have focused the world’s attention squarely on the often-challenging subject of tailings storage. Unwanted ultrafines, that are deemed to be unworthy of further treatment or not to have further saleable value, are therefore a significant issue for mine owners looking to reduce risks and perceptions associated with long-term storage of tailings. In this context, there are strong drivers to identify safer approaches to ultrafine tailings management, especially if it can also lead to increased revenue, together with better water stewardship and environmental outcomes. The better management of tailings needs to be considered from both containment challenge and processing opportunity perspectives. This paper focuses on the latter, reviewing from a technical and economic perspective, the feasibility of more extensive processing and/or reprocessing of specifically iron ore tailings, in a bid to reduce the overall volume for management in long-term storage. Herein the opportunity lies in recovery processing, as much as enhanced thickening and/or mechanical dewatering, and therefore the paper discusses both issues as equally important sides of the same coin. Recent interest in iron ore ultrafines processing and reprocessing studies suggests that the enhanced processing of iron ore tailings offers multiple perceived advantages. Apart from a potential reduction in tailings volume, associated with safer containment, lower environmental impact and improved water management, the prospect of increased revenue from additional Fe recovery presents supplementary motivation for iron ore players to embrace this approach, as further elaborated in this paper.

Nov 8, 2021