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By H. Copur

Experimental studies for quantification of force and brittleness indices relevant to rock cutting performance are presented. A simple interpretation method is developed, which quantifies the force-penetration response obtained from indentation tests. Basic parameters of the quantification are force increment and decrementrates, force increment and decrement periods, and number of increment and decrement data points. Blocks of eleven different rock samples were collected from different operating mines in Turkey and subjected to indentation tests to calculate the indices. The samples included harzburgite, serpentinite, trona, limestone, claystone, two different sandstone samples, siltstone and three different chromite ore samples. The concept was validated by a set of full-scale linear cutting tests using a conical cutter for measuring the cutting performance in relieved and unrelieved conditions, i.e. cutter forces, specific energy, size distribution of rock cuttings. The rock cuttings were sieved to determine coarseness index, indicates coarse chip generation characteristics, and size distribution. The force index is moderately correlated with the cutting performance and mechanical properties of the rocks, and poorly correlated with the coarseness index and size distribution of cuttings. A general and moderate trend is observed between the brittleness index and the coarseness index, cutting performance for unrelieved cutting conditions and mechanical properties of the rocks. However, additional data is required to fill the data gaps and to potentially establish relationship between the brittleness index and all other parameters.

Jan 1, 2003

By Paikowsky, Samuel G.

"Due to the way drilled deep foundations are being constructed, their structural integrity and geotechnical capacity are highly variable. Drop weight systems are increasingly being used to dynamically test the capacity and integrity of drilled deep foundations. Conventional pile driving hammers are often either inadequate or not economical to test these foundations and drop weight systems have therefore been developed to allow for dynamic testing.The advantages of the tests include high mobility, short testing time, low cost relative to static load tests (allowing multiple tests at a single site), and integrity/construction quality evaluation concurrent with capacity determination. The dynamic testing method for drilled deep foundations encounter several difficulties including: the need for a pre-testing analysis for matching pile, soil and testing system, adequate mass and drop height to reflect the mobilized capacity without structural damage, test interpretations for irregularly shaped and/or non-uniform piles, need for reliable dynamic measurements depending on the impact and the distance between the impact and the measuring point, and limited knowledge about the accuracy of the predictions.The principles of the tests are presented using simplified models and demonstrated via a case history. Drop weight systems are reviewed. Dynamic measurement principles are explained and the construction and testing quality effects are outlined and demonstrated via numerical modeling and case histories. A comparison of dynamic and static tests is presented via a database, case histories and finally a short review of relevant codes is provided.1 IntroductionTraditional static axial load test is performed by a slow application of a force produced against independent reaction, imitating structural loading. It is the most reliable method to determine the pile’s performance as commonly required under typical service conditions. The major limitations of this testing are: (i) high cost associated with set-up, test duration, interpretation and construction delays, and (ii) inability to obtain information about the pile-soil interaction along the pile without additional testing means (e.g. tell tales, strain gauges, etc.). These limitations are acute when high capacity foundations are involved."

Jan 1, 2015

By F. Stober, D. Wanblad, J. Ndlovu, L. R. Nelson, L. P. S. de Villiers

The single six-in-line furnace of the Polokwane Smelter is the largest installed high-intensity furnace for platinum group metals (PGM) base metals sulphide smelting in the world. The furnace employs state-of-the art technology to deliver a planned throughput of 650 000 t/a dry concentrate at a design 68 MW power input. This furnace, at double the capacity of previously existing PGM furnaces, offers low unit operating and capital cost through the resulting economies of scale. Key features of the design include:

Jan 1, 2005

By David Brown, Dirk van Dyk

Horizontal rotating mills are being used all over the world associated with different mineral and power generation industries. David Brown South Africa, with over 140 years of experience in gear manufacture and design, has been supplying these industries with innovative designs at exceptional quality. The gearing systems associated with these industries are challenged daily with operating conditions with are not always fully understood. Failures are therefore experienced, over time in the industry, which can therefore not always be fully explained. David Brown South Africa has developed a gear monitoring system, the Intelligent Gearing System, in association with Transmission Dynamics (UK), in order to monitor and analyze these operating conditions in real time. The system has been designed on the principles of Six Sigma, incorporating Design for Six Sigma. The purpose with this system design is to monitor the operating conditions on the pinion, record the information and analyze the data in relation to the rate of fatigue damage to the girth gear and pinion. This is done in real time and unattended. The output from the Intelligent Gearing System can be fed back into the operating system of the mill user, in order to display an alarm for operating conditions exceeding the design criteria as well as information on the rate of fatigue damage due to these operating conditions. When the mill operating conditions are better understood, and the effect on the fatigue life of the mill gearing components, mill users can forecast critical spare holding levels with an increased accuracy. The Intelligent Gearing System also allows early actions to remove reasons for system overloads.

Jan 1, 2007

More than 400 academic, Government, and industry representatives attended the third symposium on ash utilization and technology held in Pittsburgh, Pa., March 13-14, 1973. Sponsored by the American Public Power Association, Edison Electric Institute, National Coal Association, National Ash Association, and Bureau of Mines, the symposium Featured 26 formal presentations by leading experts from Europe and the United States on all major phases of ash production, utilization, and research. Abstracts of all the papers are grouped right after this introduction, and the full symposium proceedings follow. Sponsoring organizations and their chief representatives were the National Coal Association, James R. Garvey, Bituminous Coal Research, Inc.; Edison Electric Institute, C. E. Brackett, Southern Electric Generating Co.; American Public Power Association, Herbert Blinder, Columbus (Ohio) Electricity Division; National Ash Association, Inc., James N. Covey, Rochester Gas and Electric Corp.; and the United States Department of the Interior, Bureau of Mines, William L. Crentz.

Jan 1, 1974

By Rita D. Sylvester

"This compilation lists and summarizes publications by Bureau authors published in the regular Bureau of Mines series, in scientific, technical, or trade journals, or in other media; those available from the Bureau of Mines are indicated. Patents issued to Bureau personnel are also listed, and instructions are given on how to apply for permission to use them. One of the outstanding features of this Special Publication is an exhausive subject and author index. IntroductionThe Bureau of Mines was established in the public interest to conduct inquiries and scientific and technologic investigations concerning mining and the preparation, treatment and utilization of mineral substances; to promote health and safety in the mineral industries; to conserve material resources and present their waste; to further economic development; to increase efficiency in the mining, metallurgical, quarrying, and other mineral industries; and to inquire into the economic conditions affecting those industries, The organic act of the Bureau, as amended by Congress and approved February 25, 1913, made it the province and duty of the Bureau to ""disseminate information concerning these subjects in such manner as will best carry out the purposes of this Act.""In accordance with this directive, the Bureau reports the findings of its research and investigations in its own series of publications and also in articles that appear in scientific, technical, and trade journals; in proceedings of conventions and seminar's; in reference books; and in other non-Bureau publications. The number of these reports, the wide range of subjects they cover, and the variety of mediums in which they appear make the kind of list and index presented in this special publication both necessary and valuable. This issue describes reports and articles published during the period January 1, 1970, to December 31, 1974. It supplements the 50-year list of Bureau publications issued from July 1, 1910, to January 1, 1960;2 the 50-year list of articles by Bureau authors published outside the Bureau from July 1, 1910, to January 1, 1960;3 and the 5-year lists of Bureau publications and articles from January I, 1960, to December 31, 1964,4 and from January I, 1965, to December 31, 1969.5 It includes all the material in the four annual lists of Bureau publications and articles from January 1, 1970, to December 31, 1973."

Jan 1, 1975

By S. H. Lorain

Tin mining on Seward Peninsula, Alaska, has been intermittently active since the early 1900's. Most of the recorded production (over 2,200 short tons of metallic tin) has been obtained from placer deposits, but recent production also has resulted from development of lode deposits associated with intrusive rocks occurring in the western part of the peninsula. Generally, the lode deposits containing tin minerals (principally cassiterite) are found in dikes, in granite masses, and in silicate zones in limestone overlying the granite. Both the placer and lode deposits have been of considerable strategic interest to the Government because of the almost total absence of a domestic supply of tin. The most important tin-lode deposit discovered to date is in the Cassiterite dike at the Lost River mine, on Cassiterite Creek about 85 miles northwest of Nome. This highly altered, rhyolite porphyry dike averages 12 feet in thickness, strikes N. 75° to 85° E., and dips steeply to the south; it can be traced on the surface for about 8,000 feet. Throughout its explored length of about 2,200 feet the dike everywhere contains some tin and tungsten in veinlets and disseminations; economic concentration of the are minerals, however, is confined to definite shoots. The ore minerals include cassiterite, stannite, hulsite, paigeite, wolframite, scheelite, and base-metal sulfides; gangue minerals include fluorite, boron silicates, and lithium-bearing minerals. Some ore minerals also occur in the numerous other dikes and in the granite and intruded limestone in and adjacent to the mine.

Jan 1, 1958

The rocks of Waihi and the surrounding district are almost entirely rhyolitic and ande5itic in character. Sedimentary rocks, with the exception of some surface deposits of clay loosely compacted conglomerate, etc., and one or two thin and broken beds of a very poor lignite, occasionally changed by igneous agencies into a bituminous coal, are almost absent. In the shafts sunk by the Waihi and Grand Junction companies outside the outcropping andesitic area of the Martha Hill, more than one old surface or lake bottom has been passed through. At these points layers of sand, consolidated volcanic mud and tuff, accompanied by numerous broken fragments of imperfectly silicified wood have been enccuntered, but these occurrences may, for the purpose of this paper, be neglected.The youngest rock of the district are rhyolites, probably of Pliocene age. At least three distinct classes of rhyolitic lava, each possessing features of unusual interest, may be made out. None of these, however, is gold-bearing. The youngest flow, a light-coloured, fine-grained rock, is remarkable owing to its enclosing at times fragments of carbonised wood, varying in size from mere specks up to quite large pieces of almost pure charcoal. Rhyolitic tuff is also met with. The rhyolites cover a large extent of nearly flat country east, south, and west of Waibi, here and there rising into barren, stony hills.Below the rhyolites, geologically speaking, but for the most part. forming hills which bound the rhyolitic plain, or rise out of it as isolated patches, come ahdesites of older...

Jan 1, 1902

By F. Sillers, R. T. C. Rasmussen

"INTRODUCTION This is the third report of investigations by the Bureau of Mines in cooperation with industry to establish the value of electrolytic manganese in the manufacture of ferrous and nonferrous alloys. The manganese was produced by the Bureau at its Boulder City pilot plant from domestic ores and by the process developed by it. 4/ The work was done under the direction of R.S. Dean, assistant director, Bureau of Mines, and R. G. Knickerbocker, chief, metallurgical branch. The first report dealt with the use of electrolytic manganese in the manufacture of stainless steels 5/ and the second with its use in acid electric or open-hearth low- and medium-carbon steel castings. 6/The present report treats of the use of electrolytic manganese in the manufacture of low—carbon rimmed and killed steels. A résumé of these three investigations and two others appeared in the magazine STEEL. 7/ Further reports will be published as tests are completed at some 70 industrial plants. All tests were made on full—scale heats or melts, and the resultant product was processed and used commercially."

Jul 1, 1945

By George K. Clement

Manual estimating method through use of equations, factors and curves for preparation of feasibility type estimates for capital and operating cost of mining and primary beneficiation in the United States and Canada of various types of minerals occurrences, except fossil fuels, using state-of-the-art technology. User should have basic estimating experience in the mining industry and/or related fields. Primary usage of this handbook will be for the preparation of preliminary estimate within a reasonable degree of accuracy with relative small amounts of hard input data. Output may be used to determine if a more finite type of estimate should be produced.

Jan 1, 1978

By Thomas Fraser

"INTRODUCTION The Santa River Valley of northern Peru contains extensive deposits of a good-grade anthracite that offer one of the most accessible sources of solid-fuel supply for South America. This region is served by the narrow-gage railroad of the Corporation Peruana del Santa, which taps the coal fields along the Chuquicara River and terminates at the port of Chimbote, where facilities have been provided for loading coal into ocean-going vessels.This Government-sponsored corporation is prosecuting a vigorous program of development in this region, envisaging an intensively industrialized area around Chimbot Bay, fueled and powered by the anthracite of the upper valley and a hydroelectric generating plant now being constructed in the Cahn del Fate, where the Santa River has cut through the coastal range of the Andes.This development also includes the construction of extensive irrigation works to greatly expand agricultural production in the valley and thus estab¬lish the basis for a prosperous, well-balanced, industrial and agricultural community. It is hardly necessary to point out the importance of the local anthracite-mining industry to this general plan.At the invitation of the Peruvian Government, through the agency of David Dasso, chairman of Corpoacion Peruana del Santa, a technical mission was sent to Peru in March, April, and May 1945 to examine these coals and assist the corporation in promoting preparation of the coal for most effective use in the contemplated expansion of industry and trade."

Feb 1, 1948

By R L. Brathwaite

The gold-scheelite-quartz lodes of the Wakamarina valley were the most productive of the mesothermal gold-bearing areas in the Marlborough Schist. Most of the production came from the Empire City and Golden Bar mines which worked the Golden Bar lode. Only 134 m of its 1800 m strike length are accessible, in the No.2 level of the Golden Bar Mine. A fault has downthrown the Golden Bar Mine section by = 47 m and displaced it left-laterally by 18 m. The lode is a typical ribbon-banded mesothermal vein, averaging c. 1.75 m wide, and enclosing narrow horses of schist country rock. It is composed of bands of milky æbuckÆ quartz with thin laminae of schist. Scheelite occurs in short strings of grains within quartz on the footwall side of the lode and also in small quartz-carbonate veinlets in the foot wall and hanging wall schist. The lode quartz contains only localised traces of pyrite and arsenopyrite. They are more abundant in the wall-rock schist.   The Golden Bar lode lies within a steeply dipping normal fault, which, on its footwall side, is adjacent to a 40 m-wide, shallow-dipping mylonite shear zone. Within 1 m of the lode, the shear foliation has been dragged down to nearly parallel the lode footwall. Wall rock alteration is manifested by a marked increase in K and Rb, which correlate with abundant illite/muscovite and K-feldspar within 2 m of the footwall of the lode. Amphibole, stilpnomelane, and pumpellyite show a progressive decrease towards the lode. As and Sb increase close to the lode, but are at background levels within the lode itself. Enhanced Cr (150-430 ppm) in the quartz, relative to the schists (~40 ppm), suggests that the source hydrothermal fluids passed through and leached mafic rocks, such as the metabasites from the hanging wall of the lode (~400 ppm Cr).

Jan 1, 1995

Fossil fuel consumption in the United States increased markedly over recent years, and future demands expect to be even greater. Coal, this Nation's most plentiful natural fossil fuel, will play a key role in fulfilling these demands. With expectations of increased coal exploitation, the U. S. Bureau of Mines authorized this project, the objectives of whi.ch were to prepare an authoritative report on current surface coal mining technology, to define current problems and possible solutions, and to project future developments necessary to assure adequate surfaced mined coal production to meet the Nation's future energy needs. These objectives we're accomplished by an extensive review of available published literature and data gathering field visits to active surface coal mines throughout the country.

Jan 1, 1975

By R. S. Dean

"It has long been recognized that the properties of polycrystalline substances are not the same as those of single crystals. These differences are especially marked in metels and metallic minerals, and are of greatest practical importance in metal working and ore treatment. The property changes encountered in passing from a metal single crystal to a poly-crystalline aggregate are the same as are produced by cold-working a metal or by the precipitation of a disperse phase. Hence, we may logically assume that the property changes are all due directly or indirectly to the formation of interfacial area or internal surface. Our problem, then, is to ascertain the physicochemical state of the metal atoms at such internal surface and show how this physicochemical condition accounts for the pronounced changes of mechanical, magnetic, and electrical properties that accompany increased internal surface.GENERAL CONCEPT OF INTERNAL SURFACEIn 1678, Huyghens attempted to explain the double refraction of calcite by postulating that crystals were built from a regular arrangement of ellipsoidal particles. Over 100 years later, Abbé Hauy concluded from his studies of cleavage that crystals might be built from small units, but the units were of the same shape as the entire crystal. This idea, which was prevalent in mineralogical thought before the advent of X-ray spectrometry, was discarded when the great success of Bragg made it appear that the chemical atoms were in reality the elements of structure. In the further development of X-ray technique, however, C. G. Darwin, in England, and P. P. Ewald, in Germany, found it necessary to postulate crystal units con¬taining many atoms. The latter gave the name of mosaic crystals to those so constituted. The individual units are supposed to Possess the ideal atomic arrangements revealed by the X-ray but are not oriented with respect to one another."

May 1, 1938

By Thomas Brunsing

The program was carried out to develop deep kerfing and core breaking techniques to be incorporated into the design of a field prototype hard rock mining machine. The field machine is designed to mine non-abrasive bedded deposits up to 20,000 psi in uniaxial compressive strength. The mining technique involves cutting approximately 2 ft deep parallel kerfs spaced 2 ft apart in either a horizontal or vertical direction and subsequently breaking out the cores so defined. The prototype machine is intended for demonstration of the technique in a quarry or equivalent field environment. The program was aimed at minimizing the required kerf width, obtaining reliable breaking within that kerf width and determining cutter blade requirements necessary to achieve a mining rate of 20 ft3/min. Full scale breaking experiments and 1/2 scale kerfing experiments were employed to evaluate the system. High strength concrete test specimens were used to simulate the rock being cut and broken. The test results indicate the kerf/break technique can achieve the desired mining rate by utilizing two 7 ft diam blades to cut 2 in. wide by 24 in. deep kerfs. A lateral load applied at the base of the kerf (base shear) was selected at the core breaking technique to be employed by the full-scale prototype machine.

Jan 1, 1983

By Deren Zhu

Based on the results of in-situ observations and physical model analysis, a computer simulation method, FEAEBP, has been developed to predict the behaviors of main roof breakage in longwall mining by considering it as a Kirchhoff plate on Winkler elastic foundation. This method in used to investigate the initiation, and development of the breaking process of main roof and its displacement field before and after its breakage. In this paper the simulation method is introduced, characteristics of the displacement field of the main roof is discussed and monitoring variation of the displacement field of the main roof in a Chinese longwall face is demonstrated.

Jan 1, 1989

Editor?s note: Each year, the June issue of Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue, all the while doing their own jobs. Thank you to the industrial minerals annual review editor, to the Industrial Minerals and Aggregates Division technical committee chair and vice-chairs, and to the authors of the individual commodity profiles. Jim Norman, member SME, of Tetra Tech, is the industrial minerals annual review editor. Candace Trimble, member SME, of Oil-Dri Corporation of America, is chair of the Industrial Minerals and Aggregates Division?s Technical Committee.

Jan 1, 2012

By E. L. Rawlins

The development of commercial natural-gas reserves in the Michigan stray sandstone horizon of central Michigan during the past few years has resulted in expansion of the natural-gas industry in that State. The location of the natural- gas reserves of Michigan in the general vicinity of domestic and industrial markets is of economic importance, and in supplying these markets with natural gas a reasonable knowledge of the extent and availability of the reserves is needed in formulating regulations for drilling gas wells and producing natural gas, in analyzing the feasibility of projects to construct natural-gas transmission lines, in promoting and developing markets for the domestic and industrial consumption of natural gas, and In solving many engineering and economic problems common to the natural-gas industry. The development of the natural-gas industry in Michigan has been related closely to the development of oil production. The potential oil production of Michigan is comparable with that in most of the eastern oil-producing States. The development of oil production probably will continue, especially in the central Michigan Basin area; and as wells are drilled to deep horizons in the search for oil, more knowledge will be obtained of the gas reserves in formations above the oil- bearing horizons.

Jan 1, 1936

By Keith L. Harris

The performance of the world economy improved significantly in 1984. Real world output!/ grew 4.3% (compared with 2.6% in 19831, the highest since the 4.4% increase recorded in 1978 (table 1). The output of industrial nations rose 4.9%, while that of the developing nations rose 3.7%. The United States and Japan had the largest increases in output of the major industrial nations, with respective increases of 6.8% and 5.8% (table 2). The components of real output with the most significant growth in the industrial countries were gross fixed investment (9.2%), consumer expenditure (3.1%), and public consumption (2.5%) (table 1). Industrial output, as measured by industrial production indices, has returned to about the 1980 level for most of the major industrial nations (table 2). Exceptions to this were industrial production in Japan and the United States; Japan's industrial production rose steadily throughout the 5-yr period and is now more than 16% above the 1980 level, and the industrial production index for the United States reached 11 1.2 (1980=100.0). Real total domestic demand grew at 8.7% in the United States, more than double the rate of Japan, which, at 4.0%, had the second-largest growth. Average demand for all industrial countries was up 5.1%. During 1984 the U.S. dollar showed great strength on international markets, contributing to large current-dollar negative net exports of goods and services and even larger negative net exports of the merchandise sector. While growing U.S. imports helped spread the benefits of the recovery, they also led to a widening of current account imbalances and growing trade tensions throughout the world.3/, 4/

Jan 1, 1985

By Y. Luo

A PC based computer model has been developed by the authors for predicting the surface subsidence due to underground coal mining. Its reliability, comprehensiveness and user friendliness demonstrate that it is a good tool for the mine operators, government agencies and scientific researchers alike.

Jan 1, 1989