Search Documents

By J. B. Austin

Jan 1, 1945

By L. L. Probert

A three-year project focusing on the depth profiling of respirable coal mine dust particles using scanning electron microscopy coupled with energy dispersive x-ray analysis resulted in the development of statistically classified particle-behavior models. The models depict the changing silicon fraction for 5-, 7-, 9-, and 11-keV accelerating voltages, thereby giving a clear indication of the nature of various types of particles. This paper will focus on the results for respirable quartz particles that occur in underground coal mines across the U.S. The relationship between the amount of surface-available quartz and coal seam rank is well established for Pennsylvania

Jan 1, 1994

By Victor Spironello

The Bureau of Mines is studying cupola ironmel technology with the objectives of conserving high-quality raw materials through substitution and productivity. In the research re-ported here, a ize was modified by a gas-fired melting and/or ing chamber into the stack above the level of the coke bed, for study as a prototype for a coal-fired melting chamber. The modified cupola, in which natural gas was used to partially replace foundry coke, was evaluated in several trial runs. Data were obtained on furnace performance, metal and slag chemistry, and scrubber waters as particulates. Results of the modified ion were compared to those of conventional cupola operation. Although this research was preliminary--since the ultimate goal is to use pulverized coal instead of yielded ample evidence that the melting rate of a cupola can be icantly increased with less than a increase in energy input. Other evidence suggests that melting of low-density scrap can be enhanced and that scrap containing undesirable and/or oxidizable elements can be appreciably upgraded. This work is continuing and will include the use of pulverized coal of low rank to assist in melting.

Jan 1, 1984

By WILLIAM BOWIE

IN most human endeavors a knowledge of the terrain is essential to the effective carrying out of projects, but no line of work is more dependent on maps than theoretical and applied geology. Maps of a kind do exist for all of the area of the United States, but most of them are crude affairs and of little use in engineering, planning, and scientific research. Topographic mapping in the United States was initiated on a national scale by the U. S. Geological Survey and the organizations that were merged in its creation to make base maps for geologists. Their work could not be effectively done then and cannot be effectively done now without maps that accurately delineate the earth's surface. The distribution of the rock masses that contain valuable mineral bodies, or that by their intrusion brought them into existence, is the first step in a study of the mineral resources of the nation. This work requires three-dimensional maps, that is, topographic maps on which the land forms are shown by contours.

Jan 1, 1938

By Wang Xu, Tao Dongping, Zhang Jie, Tao Youjun

Based on the principle of fly ash triboelectrification, the mineral electrical index and testing method are introduced. The electric differences of various mineral components of fly ash are discussed in view of the results of chemical and mineral composition analysis of the fly ash sample acquired from the Xin-wen power plant. The dielectric constant and charge-mass ratio of carbon and ash in the fly ash are determined. The data were then used along with the rotary triboelectrostatic separator (RTS) testing results to investigate the charging characteristic of fly ash particles in different sizes. The results show that the dielectric constant of fly ash with different particle size decreased with the decrease in particle size, which led to a poor electrical conductivity. Thus particle size has an important effect on conductivity. The charges of carbon and ash particles increased with decreasing particle size. The charge-mass ratio of carbon and ash particles of the same size increased with decreasing particle size. This indicates that finer particle size is more favorable for triboelectrification separation from the charging efficiency point of view. The rotary triboelectrostatic fly ash separation tests show that the best decarbonization performance was achieved with particles in the size range of 0.038-0.074mm with which the decarbonization rate and efficiency index reached 38.93% and 120.83% spectively.

Jan 1, 2014

By V. Z. Sun

One of the major concerns of ground control in a coal mine is safety against failure of one of three components (i.e. roof, pillar, or floor) of the mine entry. In order to better design and evaluate stability of the mine entry with a certain confidence, a reliability approach is introduced rather than using the conventional safety factor (SF) method only. Advantages of using the reliability approach is that it not only takes variability of both rock/coal properties and stress distribution into consideration, but also assesses the stability of each component and mine entry as a whole system. Therefore, it is anticipated that, by using this approach, the current ground control technology in coal mine will convey a better sense of confidence. The results of a case example show a significant influence on the current design concept and stability evaluation of mine entry.

Jan 1, 1997

IT will be noticed, from the following contributed papers on the various plant, what an infinite number of parts are required to be kept in active operation in order to derive a resultant product of commercial value from the ores and materials received at the works. Crude ores and concentrates, in every degree of complex structure and resistance to treatment, are arriving daily from near and distant places, moreover their metallic contents are so varied that an outsider, unacquainted with the operations, would naturally wonder how it is possible that the rare elements are to be sorted out and classified into their true order, to meet industrial requirements.The proposition is necessarily not a simple one and owners of mining properties have naturally refrained from smelting their complex ores on account of the technical difficulties of attaining high efficiency and recovery of the metals, where limitations are imposed in procuring a variation of ores that lead to the best smelting and refinmg result. This difficulty obviously imposes many disabilities on the smelter, who is prepared to accept all such complex ores, and it may be said that were therenot available a large weekly supply of lead concentrates from the company's own mine at Broken Hill, of standard quality, much of the material being treated in the world today would certainly not be marketable.In order to sustain full efficiency, each section of the works must maintain its.true balance and synchronize with the requirements of such other departments as are dependent on its partially treated materials. This harmony of operations is not only imperative as regards tonnage output, but also relies on the condition of the resultant treatment by each plant, no large variations being permissible.The various officers are, therefore, dependent on one another to keep the order of the operations flowing regularly. This is accomplished by constant intercommunication and observation, as...

Jan 1, 1918

By A. G. Wylie

The dimensions and shape of both airborne and bulk amphibole-asbestos fibers are different from those of cleavage fragments of the amphiboles. These differences are related to the mineralogical properties unique to the habit of asbestos. These properties include the fibrillar structure, small fibrill widths and distinctive crystallographic faces of fibrills. Criteria for distinguishing amphibole cleavage fragments from amphibole-asbestos include mineralogical proper-ties observable in bulk samples and the dimensions of particles collected on air filters.

Jan 1, 1988

By Anton Sawatzky, Erich Vogt

By means of mathematical solutions to the appropriate diffusion equations, we describe the kinetics of the thermal diffusion of hydrogen in Zircaloy-2 for the various temperatures and concentrations encountered in a heavy water moderated reactor. When the hydrogen concentration is below terminal solid solubility only the a Phase is present. Redistributions are then described in terms of the characteristic functions of the difhsion equation. For higher concentrations both the a and 6 phases are present. We assume the two phases to be always in equilibrium. For moderately small hydrogen concentrations exact solutions of the two-phase equation approach the the approximate solutions derived by Sawatzky and for all concentrations the exact solutions exhibit the qualitative features of his result: the two-phase concentration increases with time, everywhere; in the absence of a hydrogen current at the hot end of the sample an a-phase region always exists there; the interface of the a + 6 , a-phase boundary moves toward the cold md of the sample and the hydrogen concentration is discontinuous at the interface. Simultaneous solulions of the a and a + 6 hydrogen distributims and of the concomitant interface motion are obtained and compared to the observations of Sawatzky and Markowitz. The kinetics of the hydrogen diffusion process are shown to lead to m apparent heat of transport of the a phase which is lower than the actual value (even for samples with long anneals) thus resolving at least partially the disparity between experimental measurements of this quantity. A number of recent papers1"4 have reported measurements on the diffusion and redistribution of hydrogen in Zircaloy-2 under temperature and concentration gradients. These studies were instigated by problems arising from increasing use of Zircaloy-2 as a fuel element cladding material in pressurized-water power-reactors. The Zircaloy-2 picks up hydrogen during the operation of the reactor: the consequent precipitation of zirconium hydride in the Zircaloy-2 has pronounced effects on its mechanical properties. The Purpose of the present Paper is to describe the kinetics of the thermal diffusion of hydrogen in Zircaloy-2 for the various hydrogen concentrations and temperatures likely to be encountered in reactors. When the hydrogen in the Zircaloy-2 is entirely in the solid solution phase (a phase), the differential equation for thermal diffusion is well known and the redistribution can be described by standard mathematical methods some of which are given in Section 11 below. The treatment of the a + 6 (hydride) region differs from the earlier treatment of sawatzky3 by taking into account several modifications of the two-phase diffusion equations as suggested to us by Markowitz4 and Kidson.5 Even with the modifications the results obtained in our more complete treatment are substantially the same as those found by Sawatzky. As we show, the difference between the results of sawatzky3 and kIarkowitz4 is largely due to the difference in the geometry of their experiments. In the next section we derive the modified two-phase equation for arbitrary geometry. The exact solution of this equation is given in Section III for linear and cylindrical geometry. It is shown that Sawatzky's approximate solution is quite accurate for almost all the temperatures and hydrogen concentrations which are actually encountered. In Sawatzky's approximate theory the hydrogen concentration everywhere in the two-phase region increases continuously. As his paper pointed out, this result, together with hydrogen conservation, implies that in a sample with no hydrogen current flowing into the hot end a two-phase region is always accompanied by a single-phase region at the hot end of the sample. The net hydrogen gain in the two-phase region is supplied by the decrease of hydrogen in the single-phase region and by the movement of the (a, a + 6) boundary toward the cold end of the sample. Hydrogen conservation at the (a, a + 6) boundary leads to a discontinuity in the concentration and its derivative there. In Section IV it is shown how these qualitative features of the thermal diffusion kinetics arise from the simultaneous solution of the a-phase differential equation and a + 6 phase equation. Methods derived by us previously for the solution of the redistribution in both phases and the accompanying motion of the boundary are used to obtain approximate solutions valid for large times. The solutions account well for the observed redistributions of Sawatzky and Markowitz. It is shown how the continuing motion of the (a, a + 6) boundary leads to measured values of the heat of transport lower than the actual value, even for specimens with relatively long anneals.

Jan 1, 1963

By M. Wrobel, J. Hammerschmidt, M. Runkel

Fluid-bed technology is a key pyrometallurgical step for processing a vast number of ores and concentrates. Over the past 50 years, considerable research and development efforts have been made by Metso Outotec to expand the application window of this technology. This paper illustrates different processing routes where fluid-bed technology plays an important role in the production of the copper. The fluid-bed processes utilized are partial, sulfate-producing, and dead roasting. The focus of this paper considers the advantages of the dead-roasting process. This “zero waste” process can provide copper oxides, steam, electrical power, and sulfuric acid for new and existing solvent extraction–electrowinning plants. In a case where an operation is running out of oxidic ores and concentrates, fluid-bed roasting can be applied to close this gap and provide the required copper oxides in a sustainable way.

Jan 1, 2023

By Forrest T. Moyer

[The safety record of the nonmetal mining industry during 1965 way worse than that of 1961 in all general measures s of injury experience except for a slight improvement in the number and frequency rate of nonfatal injuries Work fatalities in 1965 totaled al and occurred .it a frequencyrate of 0.29 and a severity rate of 1,711 per million man-hours of worktime. The fatality total was seven oven higher than to 1964 and the injury ratess increased d 32 and 28 present, respectively Thin total. of 2,172 nonmetal injuries u- in 1965 was 3.4 less than in 1964 and the frequency rate per million ion man-hours worked declined percent to 22.73 from: 23.14 in 1964. However, the 1965 nonfatal severity rate of 1,339 per million man-hours worked was 15 percent our the: d.96,1 rate of 1,160, This increases was largely attributable to two more permanent total and nine more permanent partial injuries. in 1965 than in the proceeding year. The average severity all injuries in 1965 was 132 days, 1-I. or charged per injury or 25 days more than in 1961. Injury experience in the nonmetal mining industry, including and excluding officeworkers, for the a-year period 1961-65 is shown in table 1. The average number of men working, on active days in 1963 was 48,429, or 635 fewer than in 1961. However, mines and mills, wore active an average: of 5 days more for a total of 277 in 1965, and each worker averaged 2,245 hours compared to 2', 190 hours in 1961. As a result, aggregate worktime of 108.7 million man-hours increased 1 percent over the 1964 total of 107.4 million hours.]

Jan 1, 1970

By CHARLES R. KETES

I. INTRODUCTORY. Lake Valley, New Mexico, has long been one of the most widely known mining districts of southwestern United States. For many years its silver-mines have been among the most famous of the country, visited by many mining men and geologists; yet little information regarding the origin of the ore-deposits and the influencing geologic conditions has found its way into print. With the recent revival of public attention, after a decade and a half of utter stagnation, to the mining of silver in the Southwest, special interest attaches to the genesis and geologic disposition of the ore-bodies which are so finely open to inspection in the Lake Valley district. Moreover, the local features here described are typical of the conditions existing over a much larger field. The fact that the ores are chiefly the chloride and the chloro-bromide of silver adds further interest. Data bearing upon the genesis of haloid ore-deposits are, at the present time, very much sought. Arid regions offer particularly favorable conditions for the formation of such ores. This New Mexican district appears to supply solutions to many problems concerning this class of ores, which have long vexed the student of ore-deposits. II. LOCATION AND HISTORY. The town of Lake Valley is situated in Sierra county, in the southwestern part of New Mexico, and 100 miles northwest of El Paso, as the crow flies.From a mining standpoint, the location of the place is itself suggestive, as it lies on the southeastern slope of the great quaquaversal arch of the Colorado plateau. The center of this vast dome is in north-central Arizona, and radii about 150 miles in length reach its foot in all directions. Around its basal margins runs the broad mineralized belt containing most of the great mines of the Southwest, which extends from south-central Colorado southward and southwestward through New Mexico, thence westward through Arizona, northwestward and northward through southeastern California and western Nevada, and, finally, eastward through Nevada and Utah into Colorado again. This great mineralized belt is important as geographically limiting profitable mining over the greater part of five States.

Jan 1, 1908

By B. F. Giyani, A. Salama

Tanzania is a country with a variety of mineral deposits, including metallic minerals, gemstones, mineral fuels, industrial minerals, and critical minerals. This study provides an overview of mining legal framework, mineral occurrence and production, challenges in the mining sector, and government initiatives. The aim is to demonstrate the development of the mining sector in Tanzania and explore the potential for further mining investment in the country. The mineral production data showed generally increasing trends over the years, for example, gold production increased from 42 tonnes in 2018/2019 to around 50 tonnes in 2023/2024. Despite the growth, the mining sector encounters several challenges, including a lack of detailed geological information on mineral deposits, inadequate infrastructures in some remote mining sites, the existence of informal artisanal miners, and mineral smuggling. The Tanzanian government has introduced several initiatives to address these challenges, including carrying out the highresolution airborne geophysical survey to increase geological information in some areas, the formalisation of artisanal and small-scale mining, establishing mineral markets to combat mineral smuggling, and encouraging mineral value addition within the country.

Oct 24, 2025

By J. A. Herrick Nashua

IN this country steel made in a Siemens furnace or Bessemer converter, is generally tapped into a ladle or shoe, and then drawn through an aperture in its base into the various moulds. In order to regulate the flow of the molten mass a refractory valve is arranged at the aperture. A plumbago nozzle is fixed firmly in this aperture, and a stopper of like material is fitted to it, making a socket valve. In order to raise and depress this stopper at will, a rod is fastened-to it, extending through, the metal and over the brim of the ladle, where it is bent back in a half circle and secured in a slide. This slide plays vertically in a frame, permanently fastened to the outside of the ladle, and is moved by a lever having as a fulcrum a pin fixed in this frame, one end, of the lever being temporarily fixed to the slide, and the other end being moved by hand. Reference being had to the drawing (see Plate 1, Fig. 1), E is the nozzle, D is the stopper, A is the rod, protected as hereinafter described, C is the cast-iron framework, B is the wrought-iron slide, B' is the offset into which the rod, A, enters, and is secured in the usual manner by a key, a. Section J, K, shows the manner of hanging the lever. J is a pin attached to the slide by which the end of the lever raises the slide, B. J is the fulcrum fastened to the frame, C. K (Fig. 1) is a hand-nut fastening the slide, B, to the frame, C, at will. Fig. 2 is a side elevation of ladle, showing the outside working of the parts above described. It is the common practice to protect the rod, A, by a coating of clay and fire-sand, kneaded to the right consistency and applied to the rod, and then thoroughly dried. Just before casting, the plumbago stopper, D, is heated at its extremity to redness separate from the ladle and, at the moment of pouring, is placed in the ladle and slide, and adjusted as well as practicable. Some very serious defects ensue, causing much trouble and vexation as well as actual loss. The fire-clay coating in drying becomes cracked and seamy, and at its best is more or less loose on the rod. The hot metal sometimes cuts

Jan 1, 1879

The Inglewood Gold Project consists of several titles in and around the Inglewood and Wedderburn Goldfields which were purchased from Strata Mining Corporation (now Excalibur Mining Corporation). The Inglewood goldfield has a historical production of approximately 160 000 tonnes at 23 grams per tonne. The company has reopened and developed the Maxwells reef, picking up a high-grade shoot (Max Shoot) identified and worked by Goldquest et al up until 1994. Production ceased on a low gold price, rapidly reducing vein size and a requirement for further development. Greater Bendigo Gold Mines Ltd (GBM) has undertaken the development and encountered the mineralised vein in an increasing size setting with high grades and the existing mine development has access to a further shoot to the north (Max North Shoot). The Maxwells reef also contains the Woolf shoot south of the Maxwells shaft and an inferred resource of ~20 000 ounces is contained from 60 m below surface. Best intersection 2.9 m at 50 g/t. The Maxwells reef area produced approximately 20 per cent of the Inglewood goldfields production and GBM is preparing to increase its exploration efforts across the rest of the field. A processing plant has been constructed at the Maxwells mine site, which is capable of treating tailings, hard rock and alluvial material utilising gravity recovery. The existing Maxwells tailings have been excavated and treatment commenced. It is intended to produce a sand product from the tailings for resale and to reduce the storage requirements per tonne. Several large water dams constructed by Goldquest in the 1990s are being re-engineered to enable storage of significant tonnages of tailings. A level of surface and underground production is planned for 2008 and this is to be expanded into 2009 and beyond. The long-term future at Inglewood is envisaged as structural repeats at depth below the current workings and a project plan to gain deep access will be prepared on successful drilling results.

Jan 1, 2008

By Steve Thoman

After the 1989 Loma Prieta Earthquake, the California Department of Transportation (Caltrans) initiated an overview of the Caltrans Bridge Design Specifications (BDS) and bridge seismic design practice in California. This overview is continuing under the direction of the Applied Technologies Council (ATC-32), to review and revise as necessary existing standards, performance criteria, specifications, and practices for design and construction of new bridge structures within California. The ATC-32 project began in August 1991 and is expected to be completed in 1995. Since 1990, Caltrans project-specific seismic criteria have been developed and implemented on the I-280 and I-480 projects in San Francisco. Caltrans and an independent seismic safety review panel continue to develop and implement these criteria on other projects. In 1991 and 1992, project-specific seismic criteria were used on the I-880 reconstruction project in Oakland. The seismic safety review panel considered the I-880 seismic design criteria a state-of-the-art methodology to ensure seismic safety against collapse of bridge structures subjected to a maximum credible seismic event. This paper highlights the 1992 "I-880 Reconstruction Project Seismic Design Criteria Review" report prepared by the Seismic Safety Review Panel and Caltrans Division of Structures and will compare pre-1989 BDS and AASHTO methodologies to the I-880 criteria.

Jan 1, 1996

By Georgios Kalamaras, Chiaia Dinu, Platania Paolo, Alessio Carlo, Giampiero Cirvegna, Claudio Santucci

The Project alignment initiates north of Pinerolo, along the State Road 23[S.S. 23] that is one of the principal arteries to the northwestern Alps where a number of Olympic events for the 2006 Winter Games will be held. The 3.5 km ring road bypasses the Porte habitat by traversing twice the Chisone River. It consists of the following principal structures [Figure 1]: San Martino bridge [130 m in four bays] Prarostino viaduct [130 m in four bays] Craviale tunnel [1055 m] Turinella bridge [a 50 m long bridge that connects the two tunnels] Turina tunnel [665 m] Malanaggio viaduct [350 m in 9 bays]. The road section is 13 m wide and is made up of two 3.75 m lanes, a hard shoulder [1.50 m wide] and a 1.25 m wide curb for each lane. The Project maximum velocity is 100 km/h.

Jan 1, 2005

By D. Morin

A general study of gold refractory arsenopyrite-pyrite concentrate bioleaching has been carried out including two continuous bioleach testworks at different sizes, namely one at a laboratory scale with a 100 I unit at a 2 kg/d dry solid flowrate and the other at a pilot scale at a 100 kg/d dry solid flowrate. Both tests show a 80% bioleaching of arsenopyrite in about four days of treatment and with the same kinetic. Pyrrhotite is attacked at the earlier stage of the bioleaching but pyrite remains unaffected. The weak potential of oxidation associated with the decomposition of arsenopyrite and the abundance of arsenite leads to a high grade of elemental sulfur in the bioresidue which consumes the major part of the cyanide during the gold recovery. Furthermore. the arsenite and ferrous produced in solution have to be oxidized to obtain a stable precipitate in the waste products and as outlined in previous works of other authors on this subject the addition of iron to obtain a Fe/As molar ratio at least above 3 is necessary. The agitation equipment used in the pilot unit allowed an optimization study calculation for scaling-up the design and power requirements of an industrial installation. For the pretreatment of a gold refractory As high-graded concentrate the reagent cost has the greatest part in the operating cost of the biooxidation step due to the necessary retreatment of the biosolution. In that conditions the power cost is quite marginal. actually it is significant for the treatment of pure pyrite.

Jan 1, 1991

By Larissa Koroznikova, Steve Durkin, Patrick Bouwmeester, Michael Tuck

In currently used mining methods, blasting techniques often causes dilution of valuable ore and results in costly processing requirements. In the context of narrow vein mining of thin and highly concentrated orebodies there is a need of a mining method that can reduce dilution in order to remain economically viable. This research project explored the viability of a new mining technology, thermal fragmentation, in narrow vein mining. Thermal fragmentation technology uses a flame jet to produce extreme heat that spalls the surrounding rock to a strategically located drill hole, as an alternative to traditional blasting. This paper creates a net present value (NPV) model of a mining method using thermal fragmentation, as well as for an existing method used for narrow vein mining; comparisons and evaluations were made regarding the feasibility of the new technology. It was found that while overall costs for thermal fragmentation were relatively high, reductions in wages, haulage and processing costs, as well as increased productivity and ore recovery, meant that the new method would improve the financial performance of any operation. These results identify that there is an opportunity to introduce the thermal fragmentation technology to narrow vein mines within Australia, in order to lower costs and increase profit.

By Run-bo Wang, Zhe Wang, Fan-yi Meng, Jian-Liang Zhang

The influence of semicharcoal substitution for coke breeze on sintering performance was investigated by pot-grate sintering test. At a fixed fuel ratio, sinter productivity and strength decreased with the substitution increasing from 0 to 100% due to better combustibility. To enhance the utilization efficiency of 100% semicharcoal, sintering parameters (moisture and suction pressure) was adjusted. With the moisture increasing, sinter performance of 100% semicharcoal increased because of the suppression of semicharcoal incomplete combustion. As the moisture further increasing to 9.0%, sinter quality gave rise to a decrease trend. The results also showed that the increase of suction pressure was benefit for the increase of heat transfer rate, leading to the improvement of heat utilization energy. Measures to enhance magnetite oxidation during sintering are discussed based on current understanding of the fundamentals that control the sintering process.

Jan 1, 2015