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By Rudolf Gahl

Some time ago the Detroit Copper Mining Co. had to decide the question whether it would pay to re-treat slime-tailings, and several machines were tested in order to ascertain the type of construction which would give the greatest saving. In previous tests on the ore of this company, several tables proved far inferior to the Frue vanner, and for this reason they did not receive any serious consideration. In the late tests, however, one table was found to surpass the vanner in the percentage of saving made. The Frue vanner used in these tests had been adjusted approximately to the slope which the slime-vanners in the concentrator of the Detroit Copper Co. had at that time, about 2 in. between the inside of the wooden posts, or 0.272 in. per ft. It had not been determined, however, if this slope was the most economical one for treating the slime-feed in the mill, or for re-treating the tailings from the slime-vanners, and I was instructed to ascertain by test-runs, under different conditions, the best adjustments for the work to be done. In order to determine if a change in the adjustments of the machines would improve the results, it seemed sufficient to continue running the tests between the vanner and the table before mentioned, keeping the feed and all other conditions the same, but varying the adjustments of the vanner from run to run. I employed a vanner-man of long experience to operate these machines, who expressed the opinion that a slope between 28 and 2.5 in. between the posts (0.323 and 0.340 in. per ft.) would give the best results. Some runs made this way gave a considerable improvement. While for a slope of 2 in. (0.272 in. per ft.) the saving had been only 40.5 per cent. of that of the table, it was 49.2 per cent. for 2.5 in. (0.340 in. per ft.) slope. A decrease of

Jan 1, 1910

By I Mason, A Wellington, J Hargreaves

Many people are familiar with the use of marine echo sounders which are used by fishermen to monitor water depth and locate schools of fish. Similar technology has recently been used in some West Australian mines to provide detailed maps of ore contacts and other geological structures. Whilst drillhole intersections provide details of the location of a contact at a point, echo sounding can be used to obtain a continuous profile of the contact. A series of profiles together with drillhole intersection data can be used to build a more accurate geological model than can be inferred from drillhole intersections alone. The benefits of this are more complete ore extraction, less dilution and the ability to make more informed financial decisions. This paper presents a case history which demonstrates the successful application of the technology.

Jan 1, 2000

By M. J. Price

The usage of Geographic Information Systems (GIS) is increasing rapidly throughout the Mining Industry, especially in the Industrial Minerals sector. GIS provides an efficient and robust link between spatial (often CADD) and tabular (database/spreadsheet) components. Mineral economists and corporate planners employ GIS to perform market analyses, to source raw materials, and to schedule and monitor deliveries to customers. Exploration and acquisition groups apply spatial analysis to identify high quality resources that meet economic guidelines. Mining regulators and environmental affairs departments expedite and monitor permitting, environmental compliance, and best management practices reclamation through GIS data management and Electronic Permitting. Operations staffs monitor overburden removal, material extraction, quality control, and stockpile volumes with GIS. This paper summarizes the many aspects of GIS in Industrial Minerals. It also introduces and addresses issues and concerns commonly encountered during a mining GIS implementation.

Jan 1, 2001

By Harlowe Hardinge

The sound made by ball, pebble and rod mills has long been used by the operator as the "telltale" of their operation. The nature of this sound depends upon local conditions and the type of mill used. By experience an operator can tell whether the mill is running properly or not. Some operators are able to detect the difference in sound much better than others and get better results running the same mill under the same conditions. The automatic operation of a mill using sound as the fundamental means for maintaining control presents many problems. The satisfactory solution of these problems requires, for given operating conditions, a greater average output, with improved product for subsequent processing, than can be obtained by manual control. Relation of Sound to Useful Grinding Energy Experience has taught us that there is a difference in character as well as in intensity of sound between a mill grinding wet and one grinding dry, in open or closed circuit, to obtain a coarse or fine product, on the same material, to say nothing of the effect with a variety of different materials. Broadly speaking, a wet-grinding mill operates best at a lower sound level than the same mill grinding dry, with other conditions the same. Several reasons for this variation in sound intensity under these conditions can be advanced, but the important point is that there is a difference, based upon practical results. Since these reasons may be more or less involved, and may be subject, to much discussion, only one will be considered here. It is apparent that two balls hitting together or a ball striking the lining, if there is no intervening material, will produce the maximum sound. If a complete cushion of material is placed between the balls or ball and liner, so that the energy is dissipated without doing useful work, the balls will be unable to create enough pressure or force to fracture the particles, and the sound will be at a minimum. At some point in between—that is, where there is sufficient material between the balls or ball and liner so that the ball will fracture the particles without mashing them unduly—the sound

Jan 1, 1939

By C. O. Aksoy

Operating the underground marble quarries effectively, it is important to evaluate the deposit blocks economically which are affected by the suitability of the topography and configuration of bedding. The joint sets within the deposit and the spacing between these discontinuties are also of great importance. In this study, the marble deposits that could be geomechanically eligible for underground excavation have been selected throughout Turkey and these selected reserves have been classified accordingly by Q-Rating System. These classified marble deposits that forms groups of 1,2, and 3 (groups were determined by evaluating the O-rating, topography, quarry situation, cracks, joints etc.) are convenient for this type of production. Nevertheless, when the auxiliary factors (topography, location, production method etc.) regarding the deposit have also been investigated, the most convenient sub-group of deposits (Afyon Tiger Skin, Burdur Beige, Diyarbakir Pink and Mugla White) have emerged. The sizing of the pillars have been performed utilising Bieniawski?s stress profile. The LAMODEL software, developed by National Institute for Occupational Safety and Health (NIOSH), USA and run under the laminated displacement discontinuity method, has been used to size the pillars. This work brings in a novel opportunity to Turkey, in which no underground marble quarry has been attempted up-to-date similar to its several examples in Italy, USA, etc. This study serves as a reference for the marble operators and for the pioneering application of laminated displacement discontinuity method in hard rocks.

Apr 1, 2005

By R. C. Bates

Uranium mine workers? daily exposure to radon daughters was estimated by two methods of sampling, detailed and spot-check. Both methods involve time- weighting measured exposure levels to arrive at an average exposure figure. Random sampling, or sampling without regard for the duration of exposure, has proved inadequate for estimating average exposure levels. During the first phase of the study, the breathing zones of eight workmen in three underground uranium mines were sampled for an entire shift; 20 to 36 radon-daughter samples were collected per man-shift, Analysis of these data indicated that a suitably accurate estimate of the full-shift exposure could be made by time weighting a considerable lesser number of representative radon-daughter samples. This analysis led to the spot-check method of estimating full-shift exposures to radon daughters. Additional detailed studies were made in seven mines to Learn more about the full-shift radon-daughter exposures and to test the spot-check method, In all, 617 radon-daughter samples were taken in 10 underground uranium mines during 26 man-shifts, and the spot-check method was tested 35 times.

Jan 1, 1962

By Marco D. Boscardin

During subsidence, the ground surface may settle, change slope, change curvature, go into tension, and/or go into compression. In response to these ground movements, buildings and buried utilities in the subsidence area may settle, tilt, bend, distort, and sustain extension, compression and/or torsion. In order to develop measures to protect existing structures and utilities, or to design new structures and utilities to withstand potential movements in areas of subsidence, it is necessary to understand the interaction between the ground and the building or buried the utility. This paper reviews subsidence-induced ground movements, how these ground movements are transmitted to and accommodated by buildings and buried pipelines, and how these structures may alter ground movements relative to free field subsidence-induced ground movements.

Jan 1, 1986

By A. F. Baker

The Bureau of Mines conducted pressure-drop studies in a 4-foot-diameter simulated blast furnace shaft to compare anthracite metallurgical briquets with coke and formcoke. The test materials were used alone, layered, and in mixed burdens of commercial fuel-to-ore ratios. Anthracite briquets had a higher pressure drop per foot than furnace coke, but they had a lower pressure drop per foot than formcoke. This appears to be due to packing and shape, as well as to particle size. The superficial air velocities at which beds of briquets and furnace coke disrupted were about the same. However, if briquets of the shapes and sizes tested are substituted for furnace coke in commercial metallurgical furnaces, higher blowing pressures will be required to deliver comparable amounts of air. Test burdens with more than 5 percent material smaller than 1/4-inch diameter showed significant increases in resistance to airflow.

Jan 1, 1967

By A. F. Grandt

What is prime farmland? Can such land, once it has been strip-mined for coal, be restored so that it will produce corn, soybeans, wheat, and alfalfa? What methods or practices are necessary to bring about restoration within a reasonable time so that crop yields will be equivalent to or higher than those of unmined prime farmland under high levels of management? These questions concerned land use researchers in Illinois as early as 1948 when the Illinois Agricultural Experiment Station experimented with growing cultivated crops on strip-mined land in St. Clair County (1). This research was done almost 30 years before requirements of Public Law 95-87 were passed by the United States Congress and signed August 3, 1977.

Jan 1, 1980

Unplanned open stope hanging wall dilution is a significant cost for many open stope mining operations. Significant advances in empirical and analytical approaches for estimating stope dilution have been made, however, many important factors are still either ignored or assessed in purely subjective terms. There are many hard to quantify factors that simultaneously influence opening stability and dilution. This creates a significant difficulty for determining the influence of a single variable, such as exposure time, on opening stability. Open stope exposure time has been found to be one of the important factors that influences overall stope stability and dilution. A study is currently being conducted to quantify many of the factors influencing open stope dilution. The assessment of a large comprehensive case history database of Hudson Bay Mining and Smelting Co. Ltd. (HBMS) operations forms the basis of this study. This paper presents the findings of a study on the influence of stope exposure time on open stope dilution. The study is based on applying existing empirical stope dilution prediction methods to the extensive HBMS database. Minimising stope mucking time has been recognised as a method to significantly reduce stope dilution. Factors which influence hanging wall dilution, such as drill and blasting methods as well as undercutting the hanging wall, have been applied to reduce the scatter in the database. Empirical design techniques based on rock classification attempt to relate opening stability to ?stand-up time?, however, these approaches have not frequently been applied to the mining industry. Data from a ?stand-up time? graph have been interpreted in terms of an equivalent average depth of hanging wall slough and compared to the HBMS database findings. To add to the existing HBMS database, several stope case histories have been taken from Geco mine. These cases include data from very large open stopes with long exposure times. Data from all three sources suggest that hanging wall slough increases between .14 and 0.3 metres per month for a rock mass Q? value between about 4 and 13.

May 1, 2003

By Edward Sampson

Bases of National Power At a time when the economy of the world is in a particularly troubled state it is appropriate to examine some problems of the distribution of natural resources. I should like particularly to call attention to the remarkable increasing demand for natural resources, to give an analysis of the demand for certain mineral resources, and to direct attention to some problems in satisfying this demand. All industrial power is based on natural resources and the most basic of these are soils, energy resources, and mineral resources. There is a strong interrelation of these resources, more than is obvious, and I shall take up certain aspects from the point of view of a geologist. Few nations are well endowed with all three of the kinds of natural resources I have mentioned and much has been done by some small countries whose peoples are industrious and enterprising and where conditions for free world trade have been favourable. However, major industrial power is dependent on a substantial endowment of all three classes.

Jan 1, 1949

By Jörg Holzhäuser, Matthew Crow

An 18.5 km (12 mile) long tunnel is being driven by four Earth Pressure Balance Tunnel Boring Machines (EPB-TBMs) of 4.7 m (15.5 ft.) diameter through alluvial sand, gravel, silt and clay above and below the groundwater table in Los Angeles beneath buildings, railroads, freeways and the L.A. River. Continuous automatic data recording of TBM operation and field inspectors' records, accompanied by monitoring of 5,000 surface reference points and 268 borehole extensometers were used to obtain information. The paper explains the reason for selecting the method of EPB-tunneling to ensure stability of the tunnel and meeting of environmental requirements, and presents data collected to monitor and demonstrate the performance of the TBM sin the different ground conditions encountered.

Jan 1, 2003

By R. M. Santmyers

Thorium and cerium are two of the group of elements known as "rare earth metals," and are obtained from the mineral monazite. Previous to the employment of thorium and cerium in incandescent gas mantles these elements were nothing more than laboratory curiosities, as the rest of the rare-earth metals are to-day. The most important salts of these rare earths are the nitrates. In the manufacture of gas mantles, thorium nitrate is the principal ingredient and forms prom 92 to 99 per cent of the impregnating material; the other 1 or 2 per cent is largely cerium nitrate and is quite as necessary, for without it there would be little luminosity to the mantle when in use. When the mantle is "burned off," the nitrates are changed to oxides. The monazite used as a source of thoria contains from 6 to 9 per cent of thorium oxide (Th02) and 24 to 32 per cent of cerium oxide (Ce203). As only the thoria and a very small hart of the ceria from the monazite could be used in gas-mantle manufacture, for a time the residues consisting mostly of ceria with somewhat smaller quantities of other rare earths found no commercial application. Later, however, they came to be utilized in several ways, the most important being: (1) the manufacture of cored flaming arc carbons, a great, irmprovement over the plain arc carbons used in electric lighting; (2) cerium metal used in the manufacture of pyrophoric or sparking alloys or "flints" for automatic pocket lighters and miners' lamps; and (3) the production of special kinds of optical and art glass.

Jan 1, 1930

By G. R. Fitterer, E. A. Krockenberger, B. E. Sockman, R. B. Meneilly, J. F. Eckel, E. W. Marshall

"Steel manufacturers have noticed a decided tendency on the part of many of their customers to become more exacting in their steel specifications. Under these conditions, the steel must not only meet the specifications of physical properties (tensile strength, reduction of area, elongation, impact strength, grain size, normality, etc.) and the chemical analyses, but must also pass the inspection test of ""cleanliness.""By cleanliness is commonly meant the absence of oxide and sulphide inclusions. Other foreign particles such as furnace or ladle slag, ladle and runner brick, etc., must also be absent. The determination of cleanliness at present is usually made by microscopic inspection or macroetching.The rejection of steel for lack of cleanliness is increasing, out cleanliness is one of the most difficult requirements for the manufacturer to fill. The reason for this is that every steel inspector has a different conception of a. clean steel. A material which does not pass the examination of one inspector way be regarded as entirely satisfactory by the metallurgist of an¬other company. The cause of this confusion and disagreement concerning the definition of a clean or a dirty steel is simply that as yet no standardized procedure for the determination of impurities has been proposed and generally accepted, since many variables are encountered which interfere with the development of a satisfactory method. An idea of the complexity of this situation will be obtained from the following pages.A Survey of Proposed Analytical MethodsAlthough no analytical method has been accepted, many procedures have been proposed, as may be seen in Table 1. Therein are listed 16 of the better-known processes, pith references to the work of their originators, their mechanisms of determination, and their applicabilities. Among these is included the electrolytic method developed by one of the present authors, and some comparison between this and previously proposed procedures may be obtained by a study of the table. It appears that this new method Las many advantages over the others, and this paper presents a critical Study of its value."

May 1, 1933

By L. L. Brundred

The major portion of the production of the Gulf Coast area, represented by South Texas and South Louisiana, comes from the flanks of well-defined salt domes. This oil, containing an excellent lubricating stock, ranges from 17° to 28° Be. gravity. Some lighter oil is encountered but the life of such fields is, in general, an open question. In fact, there are few light-gravity fields which have proved of much value. In all of the fields water encroachment, or, more properly, water produced with the oil, is a vital factor. After the first head of high-pressure gas is removed, ever-increasing percentages of water appear, and naturally the life of the wells is materially affected thereby. The sands are, as a rule, extremely fine, very soft, and must be carefully excluded from the hole by the use of fine screen to prevent sanding up. All sands are tipped at such extreme angles as to make coring essential for the location of water strata, oil-bearing sands and important shale. beds. Even with modern coring, the correlation of logs is a difficult problem. Due to the fact that the bulk of the oil is refined for its lubricating properties, little attention has been paid to losses by evaporation in the field. This is largely influenced by the fact that the major companies have set a price schedule, showing but two grades, "A" and "B." The average oil company, therefore, does not attempt to use the gas-lift but relies primarily on the air-lift and then only on wells considered to be particularly adapted to its use, namely those capable of producing large quantities of fluid and yet not having sufficient "kick" to flow. Furthermore, as the gas contained in the reservoirs is mostly ricthane such gas being very quickly vaporized and produced in large quantity in the early life of the fields, there is little gas left after the first flush flowing period of the wells. In fact, it is very generally conceded that gas is a precarious fuel to depend on in any of the coastal fields. This situation largely accounts for the fact that air, as the lifting medium, is almost universally used. In the average field, wells are drilled on the flanks of the domes in close proximity to one another, largely on account of the extreme dips of the formation and "town lot" leases, and space to set up machinery and

Jan 1, 1928

By Martin H. Stanezyk

The Bureau of Mines investigated leaching of selected copper sulfide minerals and a composite of impure flotation concentrates at elevated temperatures and pressures with ammoniacal solutions. Copper 1 (tractions of 96 percent were obtained by leaching chalcopyrite at 75° C under oxidizing conditions for 60 minutes. An extraction of 99 percent of the copper contained in the composite concentrate was obtained by leaching the product for 90 minutes at 75° C. In tests of bornite, chalcocite, and covellite, 90 to 97 percent of the copper was extracted at 20° C provided an 8-hour reaction period was used. At 75° C essentially complete dissolution of the copper from these three minerals was accomplished in 60 minutes. Additions of ammonium sulfate to the leach solutions were required to obtain high-percentage extractions of the copper from bornite, chalcocite, and covellite. Although ammonium sulfate was not required when digesting chalcopyrite, copper extraction was enhanced and less free ammonia was required when ammonium sulfate was added to the leach pulps. The chemistry of leaching copper minerals was studied. It was C, termined that chalcocite altered to covellite as one step in the dissolution When leaching iron-bearing copper sulfides, hydrated iron oxide formed on the mineral surfaces, indicating that a diffusion process prevailed. No evidence of covellite was detected.

Jan 1, 1966

By G. Gauvin

Life span of aluminum smelting electrolysis cells can reach up to 3000 days. During this period, cathode blocks go under various physical and chemical changes that could result in an increase of electrical resistivity. The increase may be due to carbon migration from the cast iron to the steel bars, gap evolution between the cathode block and the cast iron, cathode cracking, etc. This paper focuses however only on the collector steel bar electrical resistivity evolution. To reveal the main phenomena responsible for the electrical resistivity increase, chemical analysis, metallographic and electrical resistivity tests were conducted on two steels bars picked from two Hall-Héroult cells after autopsies. Cathode voltage drop and temperature were measured using electrically insulated internal probes and thermocouples on 16 samples from each steel bar. Electrical resistivity can reach up to 1.21µO-m for a steel bar aged 2505 days compare to 0.142µO-m for steel AISI 1008 at room temperature.

Jan 1, 2011

By Taner Kavas

The refractory bricks of a rotary cement furnace containing of alumina and magnesium chromite were studied in order to determine whether they could be used in the concrete production as aggregates. Three mortars were prepared by mixing 1 part cement, 3 part aggregate materials, 0.5 part water by weight and mechanical, chemical, thermomechanical and microstructural characteristics were evaluated. The compressive and bending strength of samples were determined after 2 and 28 days curing. Resistance to chemicals were established by calculating the weight gain of mortars stored in 2 % HCl solution for 1 h and 24 h. Thermomechanical characteristics were determined by measuring the compressive strength of heat treated specimens at temperatures of 400 °C, 600 °C and 800 °C. Consequently, magnesium chromite containing waste brick aggregates have given the best results.

Jan 1, 2006

This Bureau of Mines publication contains five papers pertaining to the effective grounding of mine power systems, as follows: Ground-check monitor types and safety characteristics; ground wire monitors for surface coal mines; ground bed design and measurement; electrical ground rod corrosion; and a continuous ground bed resistance monitor.

Jan 1, 1979

By Jr. Wilkinson

Mine planners are under pressure to evaluate the impact of changing economic times and newly acquired data on the mine plan. Incorporating change, such as commodity prices, customer sales, changing cost assumptions, and newly acquired geologic data into the mine plans requires quick turn-around for model building and planning to keep the mine plan on pace with changes as they are occurring. Because of the length of time required to perform some of the geologic modeling and mine planning tasks, planning frequency may not be keeping pace with the frequency of change. This paper discusses how one company has increased the frequency rate and accuracy of mine plans to keep current with incoming data, ensuring mine plans reflect the latest information, thereby minimizing or eliminating production cost variance.

Jan 1, 2010