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By James S. Browning

Heavy liquids have been used to separate minerals of different specific gravities for many years.4 5 6 7 8 9/ The method permits substantially quantitative evaluation of a variety of minerals and requires much less time than the usual methods of chemical analysis. This Bureau of Mines investigation was conducted to determine the applicability of heavy liquid mineral separation to the evaluation of certain spodumene and kyanite ores, prepared mixtures, and plant products. After careful standardization of the particular mineral and associated gangue, estimates of chemical analyses could be obtained from results of heavy liquid separations.

Jan 1, 1960

By A. Yehia

Fluoride activation has been evaluated by Hallimond-tube flotation of collophanite in terms of fluoride concentration, conditioning time, pH, and temperature. The results reveal that efficient oleate flotation of collophanite can be achieved by fluoride activation. Fluoride adsorption by collophanite as a function of fluoride concentration, temperature, pH, and crystal structure suggests that, at low fluoride concentration, a fluoroapatite-type compound may form on the collophanite surface by chemisorption of fluoride ions at calcium sites; at high fluoride concentration, calcium fluoride ap¬pears to form at the collophanite surface invovling a surface-precipitation phenomenon. The formation of CaF2 on the surface of fluoride-treated collophanite is further substantiated by the FTIR spectroscopic measurements, which clearly shows a metathetic exchange with phosphate from the collophanite lattice during surface precipitation process.

Jan 1, 1986

Alluvial mining even of shallow deposits is often economically a marginal proposition and causes significant disruption of the land surface through the need for large scale excavation. In-situ leaching using chlorine-based solutions eliminates the need for excavation, the disruption of surface activities, and may greatly reduce processing costs and improve recovery especially of fine gold. A spreadsheet model has been developed to design and analyse the economics of in-situ leaching of alluvial deposits. In-situ leaching of shallow deposits may be achieved in a number of ways including solution infiltration via perimeter ditches or the use of injection and production wells. In most instances deeper alluvials may only be processed using well systems. Two deposits are analysed in this paper. The first consists of one metre of payable wash beneath one metre of overburden. Some thirty fields per year are treated processing 450 000 BCM per year at a cut-off grade of around $4/tonne ($8/rn3 or the gold value equivalent of 0.26 gh or 0.52 g/m3). The principal costs are well drilling and labour. Sensitivity analysis indicates that doubling the throughput halves the cost. The economics of the project are relatively insensitive to reagent costs and consumptions, and halving the recovery doubles the cut-off grade. Shallow deposits treated using the infiltration ditch system may be marginally cheaper and more conveniently managed although this depends on the relative cost of digging the perimeter ditches. In a second example, deep leads with one metre of wash beneath 30 metres of overburden necessitate significant drilling and feature reduced throughputs as a consequence. In the example chosen 30 fields a year are processed for an annual throughput of 65 000 tonnes costed at around $20/tonne (1.4 g/t Au equivalent, $40 /m3). Sensitivity analysis indicates that throughput, and drilling cost per metre are not important but there is a high sensitivity to recovery and to the depth to payable wash.

Jan 1, 1992

Assaying, mineralogy, and geology appear in ancient records as early as mathematics, physics, and chemistry. Agricola was the first author to unify the earth sciences, the mineral extractive industries and the mineral processing industries. His text, De Re Metallica, published in Latin in 1556, is recognized as the first technical literature. In 1702 mining instruction was started at Freiberg, Germany. The purpose of this school was to train skilled workers, a program corresponding to present-day, on-job, vocational-technical, upgrading extension training. Formal instruction in mining engineering began at Schemnitz, Hungary, in 1763, at Freiberg, Germany, in 1766, and at St. Petersburg, Russia, in 1773. It is interesting to note that these three schools initiated instruction in mining engineering before formal instruction in civil engineering began at Paris, France, in 1775. Early mining engineering, 1763-1900, was expected to cover all eventualities in the mineral industries. Optional curricula were offered early in the 20th Century but did not reach into all branches until after World War I. Specialization crystallized during World War II under three organic units: (1) Earth Sciences; (2) Mineral Engineering; (3) Mineral Technology, the three together constituting the mineral arts and sciences of the modern world (Fig. 10).

Jan 1, 1950

By Mo Wanqiang

Equivalent-pressure ventilation is a method of balancing the air pressure between a productive face and its gob to extinguish fires and prevent the infiltration of toxic gases, so that the production of the face can be maintained. The method was successfully applied in Coal Mine No. 1 of Hebi Coal Mining Administration in north-central China. In this article, a practical application of the equivalent-pressure method to prevent carbon monoxide from entering an active longwall face adjacent to a fire breeding area is described, and four steps to achieve equivalent-pressure are discussed. The reliability of using this method and measures to maintain the equivalent-pressure are analyzed. It was observed that this method could maintain high production level while no sacrificing safety at the longwall face.

Jan 1, 1984

By Tracy. L. D.

"Since the introduction of pulverized coal as a substitute fuel for natural gas in the various types of heating furnaces used, in steel mills, a number of fires and explosions have occurred, resulting in the loss of life and property.As one of the primary functions of the Bureau of Mines is to conduct investigations in the utilization of mineral substances with a view to increasing safety in the use thereof, it was deemed advisable to investigate the hazards involved in the industrial use of pulverized coal and, if possible, to devise methods of preventing future accidents arising therefrom. The knowledge of the explosive qualities of coal dust which the Bureau has gained in studies affecting dust explosions in coal mines was of material assistance in these investigations.Several plants were visited in which either fires or explosions had occurred, and data obtained as to the probable cause of the accidents.There was found to exist, among some of those employed about the furnaces, a lack of knowledge of the explosive and inflammable qualities of powdered coal.A small stream of pulverized coal leaking down from a defective joint in a coal transport line did not attract much attention, whereas, had a leak in a natural gas line occurred -wider similar circumstances, no doubt it would have had immediate attention.As a matter of fact, if by any means the duet cloud should come in contact with an open flame or hot metal, the effects would be as disastrous as if it had been gas.This is exceedingly well illustrated by an accident which came to the writer's attention. In the system used at this particular plant, the pulverized coal is transported to the furnace through compressed-air lines. The fuel is fed from a storage bin to a blowing tank in quantities as desired, after which compressed air is admitted and the powdered coal blown to the furnaces. At the time of the accident some repairs were being made to the tank, and it was supposed that the air pressure had been entirely released as the pressure gage stood at zero. There was, however, one or two pounds air pressure remaining and when one of the connections was taken off, a cloud of dust was blown across the room, 30 or 40 feet towards the drier furnace where it came in contact with some live coals. Immediately the entire room was filled with flame which rolled back and forth over a specs 50 feet or so in length."

Apr 1, 1921

By Nick Holonyak

Halogen vapor-transport synthesis of Ga(As,-,Px) and its preparation into laser junctions are described. Electrical and optical properties of Ga(As,-,PX) laser junctions are discussed. The present limitations in these properties are related to material proble?vzs and the very early state of development of Ga(As,-,PX), and are discussed in this context. Inhonzogeneity problems, fluctuation of As :P ratio, and problems with deep-level contaminants are described and related to Ga(As,-,PX) junction performance. Laser junctions are demonstrated which operate to wavelengths as short as 6470 A (77°K). The prospect that Ga(As,-,P,) will operate to wavelengths perhaps 100A shorter is mentioned. IN this paper we wish to describe some of the more important features of almost 1 year of experience in the preparation and properties of Ga(As,-,P,) p-n junction lasers. Because much data so far available are far from complete, some of the results still must be considered tentative and subject to correction and revision as work on Ga(As,-,P,) crystal problems progresses. Although the electrical, optical, and device properties of Ga(As,-,P,) junction lasers are understandably of considerable interest, the work to date points out that by far the most serious problems extant and those deserving first attention are problems involving the growth, doping, and perfection of Ga(As,-,P,) crystals. One of the most formidable of these is to grow Ga(As,-,P,) sufficiently free of deep levels, either due to contaminants or to structural imperfections, to allow fabrication of laser p-n junctions which can be cooled and not suffer from "freeze-out" of carriers on deep levels (and consequent double-injection behavior). In addition to the problems of growing crystals adequately free of deep levels and generally of the highest perfection, so that the best possible laser junctions can be realized, the further goal remains of increasing the phosphorus content well beyond 40 pct in an attempt to determine the practical lower wavelength limits of laser action in the Ga(As,-,P,) system. Even though the laser junctions prepared in Ga(As,-,P,) are of importance in their own right, we have considered them at this point mainly a means to study the growth and crystal problems of the material. It can be concluded that the laser junctions now available are almost completely limited by the purity and structural deficiencies of Ga(As,-,P,) crystals, and cannot be fairly compared with, for example, GaAs p-n junction lasers until Ga(As,-,P,) crystal growth has been more extensively developed. The basis for the statements above will become evident in the following sections which describe Ga(As,-,P,) crystal and junction preparation, and laser-junction properties. G(As,-,P,) CRYSTAL GROWTH As previously reported,2 we have found it convenient to employ the halogen vapor-transport process3 for synthesizing Ga(As,-,P,) crystals for use in laser junctions. Commercially available GaAs and Gap, separately prepared by halogen vapor tranport, are sealed in the desired ratio in a quartz vessel with a quantity of column-VI donor and a small quantity of metal halide which supplies the halogen for transport. The sealed ampoule, as shown in Fig. 1, is heated at a temperature in the range from 1025" to 1100°C at the position of the source GaAs and Gap. The GaAs and Gap are simultaneously vapor-transported and deposited as Ga(As,-,P,) at one end of the ampoule

Jan 1, 1964

By R. D. Currie

Haulage accidents in the anthracite region cause fewer fatal and lost-time accidents per million man-hours than similar accidents in bituminous mines, a fact that may be accounted for in several ways, but primarily because haulage, in a large part of the region, is restricted to haulage crews operating only on the gangways where most of the miners seldom come in contact with movement or handling of cars and locomotives. Generally in underground mines the number of men injured compared with the number killed is greater for haulage than for roof-fall accidents, while the number of men killed by haulage is second only to the number killed by roof falls.

Jan 1, 1939

By George D. Brunton

The past and present argillaceous rock studies for the U.S. National Waste Terminal Storage Program consist of: (1) evaluation of the geological characteristics of several wide- spread argillaceous formations in the United States; (2) laboratory studies of the physical and chemical properties of selected argillaceous rock samples; and (3) two full-scale in situ surface heater experiments that simulate the emplacement of heat-generating radioactive waste in argillaceous rock.

Jan 1, 1981

By J. R. Riding

In situ solution mining of uranium has environ- mental advantages over conventional mining. The leaching of uranium, however, alters the groundwater quality in the aquifer where the mining occurs. Currently, regulations require that the groundwater be restored to approximately its original condition. This paper, a summary of a study funded by the Bureau of Mines, reviews the state of the art in restoring groundwater quality after in situ uranium leaching. Current restoration practices discussed include disposal of liquid wastes in deep disposal wells and evaporation ponds, producing from all wells during restoration, and recirculating water purified in surface plants. Methods for predicting the effectiveness and cost of current techniques are presented. Possible alternative techniques are also described. Two restoration operations are discussed.

Jan 1, 1979

By Abid O. Adekunte

The design, construction and monitoring of the deep excavation support for the basement of a large-scale commercial development in Cavan, Ireland is presented. Excavation area was adjacent to existing structures and retained height H varied between 4.0m ? 11.0m. In areas where excavation depth H < 5.0m, wall was designed as cantilevered section. However in sections where 5.0m = H = 11m, additional wall supports were required for serviceability reasons. Traditionally, designers often provide additional wall support through the use of tie-back ground anchors, raking props and braces. On the current project, the main contractor was not in support of the use of temporary props so as to maximise working space, while owners of adjacent properties disapproved the use of tie-backs. The limited set-back between the wall line and site boundary also contributed to the complexity of the project. A rare alternative solution has been adopted. This novel approach involved buttressing the wall with steeply raking bored tension piles at regular intervals along the wall. Comparison of the monitored deflections in the cantilevered sections with those recorded at sections where tension piles were used shows the novel solution to be safe and quite effective. This approach is also considered to be more economical when compared with ground anchorage and propping.

Jan 1, 2008

By Albert L. Brautigam, Michael C. Leigh, August J. Kwitowski

The U.S. Bureau of Mines developed and tested a teleoperating system to control a new highwall mining system. A remote operator was provided out-of-sight sensory information and control of coal extraction and haulage equipment. Surface and production testing proved that the teleoperating system supplied the operator with sufficient sensory information to operate the mining system. Details on the teleoperating system provided in this report include (1) sensor selection, (2) a description of the electronic control system, (3) equipment selection and modifications, (4) the positive test results, and (5) recommendations for system improvements.

Jan 1, 1992

By R. E. Hucko

The principal thrust of the U.S. Department of Energy (DOE) Coal Preparation R&D Program is to develop technology to reduce the ash and sulfur contents of United States coals to levels such that the resultant product can be formulated into a high quality solid or slurry fuel that could replace oil or natural gas in both new and retrofit applications. Specifically, the objective is to develop and refine cost-effective physical and chemical beneficiation processes to extract 85-95 percent of the total sulfur and ash. The Coal Preparation program is implemented by the Pittsburgh Energy Technology Center (PETC) and is conducted both in-house and by a cross section of industrial organizations, universities, and national laboratories. Research is subdivided into three areas -coal characterization, beneficiation, and ancillary unit operations. This paper will provide a brief overview of many of the research projects being carried out in these areas in fiscal year 1984.

Jan 1, 1984

By C. McDonald, S. Slottee

Deep "paste" thickeners have been used in the alumina industry for several decades to improve chemical recovery and allow “stacking” of the red mud for disposal. These paste systems have eliminated many traditional tailings ponds in addition to providing better tails washing and better water recovery. This technology is not widely used or understood in other mineral processing applications. However, there is growing worldwide recognition of the advantages of concentrating mill tailings to a “paste”, i.e. a solid suspension that does not settle or segregate. This technology offers several alternatives to the traditional tailings pond such as “stacking” or mine backfill. More water recovery is possible than with high rate thickeners. Process benefits come in the form of better chemical and metals recovery through better washing in counter current decantation (CCD) applications. Obtaining a true paste (non-segregating suspension which exhibits a yield stress) and understanding the handling characteristics for applications outside alumina, are recent developments. Achieving all of the benefits available from a paste system requires careful design that takes into account the specific requirements of the disposal application along with the peculiar difficulties in producing and handling paste. In fact, design of a paste system is markedly different from a conventional system. Project design usually requires the cooperation of experts in several interrelated specialties including geotechnical, thickener design, pumping and discharge design and controls. A successful project must coordinate all activities to ensure that the overall objectives for the project are achieved. This paper describes the properties of paste, reviews the applications, and discusses the design of a complete paste deposition system.

Jan 1, 2003

By Richard L. Ash

In many instances, blasting exerts the dominant control over the economics and safety of excavation, where the materials involved are too hard and tough to be fragmented efficiently by other means. However, associated with the fragmentation process other effects very often result that are not desirable and may even be hazardous, such as fly rock, air blast, excessive overbreak, and damaging ground virbrations. It has always been the desire of those concerned with blasting to better control the forces involved so as to improve the breakage of materials, but at the same time reduce, or eliminate if possible, the unwanted side effects. Until the last decade or two, little was known of the phenomena concerned with blasting. However, since that time many investigators have studied blast mechanisms produced from both chemical and nuclear explosions, with the result that general concepts of the principles have been developed. But, in general, it is assumed that the energy from the explosion would be propagated spherically throughout the material, the latter of which for convenience of analyses is considered homogeneous and isotropic, i.e., the properties are the same in all directions, However, rocks are not isotropic as a rule, and evidence clearly indicates blasting forces rarely function uniformly or in spherical form as theorized.

Jan 1, 1965

By D R Quick

The Goodall gold mine is located 30 km east of Adelaide River, within the Pine Creek 1:250 000 map sheet, at 8 525 000 mN: 750 000 mE, on the AMG grid. The first gold was poured in April 1988 and the mine closed in September 1993, having produced 228 400 ounces of gold from 4.095 million tons of ore, at a head grade of 1.99 g/t. Oxide and primary ore was mined from one large open cut and low grade oxide ore from three smaller pits. The gold mineralisation was discovered in 1981 by means of a helicopter borne rock chip sampling survey, which delineated 13 discrete anomalies. Systematic grid sampling of rock chips outlined an area of 1300 m by 300 m within the 2.0 g/t contour. Over 7500 m of costeaning was used to delineate the A and B-Pod mineralised areas. Geochemical soil sampling played only a minor role in the discovery and geophysics none at all. By the end of 1984, 40 diamond drill holes had been completed and a resource of 3.63 million tonnes at 3.0 g/t calculated. In January 1985, Western Mining Corporation Ltd became a joint venture partner and funded exploration to cam a 60 per cent interest. Additional drilling led to a feasibility study in 1987, based on a Measured and Indicated resource of 4.25 million tonnes at a grade of 2.35 g/t. The host rocks are quartzo-feldspathic wacke and interbedded phyllitic siltstone, of the Proterozoic Burrell Creek formation. The main zone of gold mineralisation, A-Pod, occurs in a sub-vertical vein array, up to 50 m wide and 800 m in length, of quartz and sulphide veins (5-20 mm wide), It is parallel to and on the east limb of an upright, north plunging anticline. Five types of veining have been recognised, with the bulk of the gold mineralisation associated with quartz-pyrite-arsenopyrite and chlorite-quartz-pyrite veins. The gold occurs as particles, from 1-20 micron, as inclusions and along fractures in pyrite and arsenopyrite and to a limited extent in chlorite. The mineralisation is epigenetic and structurally controlled by fractures developed during an earlier folding event. The gold is assumed to have been derived from the underlying sediments of the Koolpin Formation by hydrothermal fluids emanating from the deep seated northern margin of the Cullen Batholith. Precipitation of gold may have been controlled by variations in temperature and pressure.

Jan 1, 1994

By George R. Stephans

The Climax Mine is a panel caving mine which has had a long history of incidents of severe ground control problems. The nature of the ore deposit, which lends itself to the caving meth- of of production, a1 so makes the mine susceptible to large scale stress concentrations which are referred to as ?weight? problems. These problems have increased with increased production and also with expansion to deeper mine levels. During the past twenty years the mine has had to learn to cope with these problems in order to remain in operation. A number of practical guidelines and useful techniques have emerged from these efforts. The purpose of this paper is to share a few of these ideas. The Mine is located near Leadville, Colorado on the continental divide at an elevation of 3450 meters. The ore body is a large low grade deposit of disseminated molybdenum sulfide. It measures about 1200 to 1600 meters in diameter and it had an original depth of about 660 mters. The Mine has been in operation since 1918 and the massive nature of the ore body together with its blocky, highly fractured condition made it natural for the caving system to have been adopted for production at an early date. Open pit mining was started in 1973. The total plant has a capacity of more than 50 thousand tons per day, and more than 400 million tons of reserves at an average grade of 0.310 percent molybdenum disulfide remain to be produced.

Jan 1, 1982

By Seiji Mizutani, Hirofumi Taguchi, Makoto Yoshida, Hidenori Takahashi, Naotoshi Shinkawa, Kazuo Konishi, Yoshiyuki Morikawa, Masaya Kawata

"The lattice-shaped cement treatment method has been used to improve the seismic performance of liquefied sandy soil in Japan. The efficacy of the method has been confirmed by the huge earthquake in Japan. In the present study, a new method to improve sandy ground by using the lattice-shaped cement treatment method is proposed as a liquefaction countermeasure. It is the floating-type and lattice-shaped cement treatment method, where cement treated soil is not fixed to an un-liquefiable stratum. In this method, a fixed-type structure such as treated soil should be formed at the side of the floating-type treated soil to reduce its lateral displacement. In the study, one-dimensional dynamic response analyses were firstly conducted to confirm the mechanism of the new method. Secondly, a series of centrifuge model tests were performed to demonstrate the effect in a proto-type scale's stress condition. The analyses and model tests confirmed the effect of liquefaction countermeasure of the new method.INTRODUCTIONLiquefaction induced by an earthquake generates sand boiling and ground settlement. Other problems have also been reported, including a decrease in bearing capacity and an increase in the horizontal earth pressure against retaining walls. To prevent these problems caused by liquefaction of the ground, various countermeasures have been proposed, such as cement deep mixing and high-pressure jet mixing methods. These methods have the big advantage of being applicable to ground that contains soil with a fine-grain fraction. Furthermore, the unnecessary displacement caused by the construction can be reduced. In Japan, a lattice-shaped cement-treatment method has frequently been used at many construction sites to prevent liquefaction, where cement-treated piles are intersected to form a lattice, as shown in Fig. 1. The lattice-shaped walls can reduce the shear stress generated by an earthquake, restricting the liquefaction at that location. However, the construction cost of the cement treatment is relatively high compared to other methods such as the sand compaction pile (SCP) method, and needs to be reduced. Therefore, decreasing the total volume of the cement treatment is necessary to reduce the construction cost."

Jan 1, 2015

By Lloyd A. Morley

The primary goal of this research report is to discuss safety considerations involved in the use of lead-acid batteries for traction purposes in underground coal mines. In order to arrive at the objective, the topic of battery safety has been divided into two specific areas. The first deals with the fact that batteries emit hydrogen gas during and after the charge cycle. Hydrogen gas can be the source of dangerous explosions or mine fires. The second major topic deals with the electrical nature of the battery and battery-charging systems, which also provides a source of mine fires as well as electrocution hazards. In addition to the discussion on battery safety, a literature review has been undertaken to acquaint the reader with some basic concepts inherent to the battery usage process. The result of this research is a set of design specifications and procedural recommendations directed at improving the safety factors inherent in any underground battery usage scheme.

Jan 1, 1977

By Chas. F. Jackson

This paper is a tabular compilation of data contained in a series of information circulars dealing with mining methods and costs at a large number of mines in the United States and some foreign countries. There circulars have been published from time to time during the years 1929 to 1934 inclusive. From time to time, as enough data became available in these circulars, other circulars and. bulletins have been published in which the data bearing upon different phases of nine operation were summarized, discussed, and analyzed. The present paper is a compilation of data on costs of drifting and crosscutting contained in earlier circulars, .designed to assemble this information in a convenient form for reference without attempting lengthy discussion of details of drifting and crosscutting practice. For such details the reader is referred to the circulars on individual mines.

Jan 1, 1935