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By W. E. Anable

The Bureau of Mines researched methods for recovering copper from cyclone and electrostatic-precipitator dusts of primary copper smelters as part of its program to maximize minerals and metals recovery from primary and secondary domestic resources. Small-scale studies showed that use of 110 pct stoichiometric sulfur and 123 pct stoichiometric carbon, based on producing a 40-pct copper-iron matte, resulted in the recovery of 95 pct of the copper contained in the dust. Typical mattes contained less than 10 pct of the arsenic, 30 pct of the bismuth, and 45 pct of the antimony and tin contained in the dust. Matte was converted to blister copper by injecting up to 200 pct of the stoichiometric oxygen requirement over a period of 2 to 3 hours. Up to 76 pct of the copper contained in the dust was recovered as a crude blister copper containing about 2 pct arsenic, 0.5 pct antimony, and less than 0.1 pet bismuth and tin. A matte-white metal product resulted from carbothermically reducing dust with coal, lime, and silica. Up to 95 pct of the copper was recovered in the combined product.

Jan 1, 1981

By Earl M. Frizzell, Joseph A. Dos Santos

"Conventional belt conveyors offer an economical method for transporting materials at inclines approaching 18 degrees. Sandwich belt conveyors may be used to transport materials at high angles, to 90 degrees, while maintaining the most positive features of conventional conveyors, that is, (1) proven conventional conveyor components. (2) high-speed operation, (3) high-single lifts, (4) continuous cleaning of the smooth surf aced belts, and (5) easy, quick repair by hot or cold vulcanizing. The present discussion deals with the evolution and development of sandwich belt conveyors to satisfy the operational requirements of the open-pit mining and materials-handling industries.A look at the limitation s of conventional shallow angle conveyors reveals the conveying angle at which a cover belt is needed. The relationship between conveying angle and hugging pressure by the cover belt is developed mathematically. A study of past and current developments reveals that the Loop Belt and Beltavator are significant advances in the state-of -the- art. The vertical radius of curvature constraints are discussed in detail and the constraint equations are developed. Criteria for future development is established as a basis for evolutionary developments in sandwich belt high-angle conveyors. The use of intermediate drives in sandwich belt high-angle conveyors is investigated.IntroductionIn connection with U.S. Bureau of Mines funded–study relating to continuous haulage from deep open-pit mines, the authors had occasion to study extensively, the use of high-angle conveyors as a means of hauling mine products continuously from the pit while maintaining optimum mine slopes to minimize total excavation. The many possible high-angle conveying methods investigated included skip hoists, bucket ladders, pocket belts, fin belts, cleated belts, sandwich belts, pipe belts, screw conveyors, slurry pipe lines, and others. The sandwich belt high-angle conveyor appeared to be the most operationally-appropriate and economical solution for the mining industry. The present paper presents the theory, historical development, state-of-the-art, and evolutionary developments in sandwich belt high-angle conveyors."

Jan 1, 1983

By N. Theron, R. F. Meeser

The global emphasis on conserving energy resources has led to the adoption of hybrid power systems in vehicles. Optimally applied, hybrid systems can save up to 40% on fuel costs. To optimally manage a hybrid vehicle's energy flow it is necessary to know, in real time, all the energy requirements to complete a given route. The energy consumption depends mainly on the vehicle mass, speed profile, and route topography. Of these, the topographic profile is the one factor that is only route-dependent and not influenced by the vehicle or driving styles. The heading vs. distance profile is also an example of a route characteristic not influenced by the vehicle or driving style. In this study the topographic and heading profiles are used to identify routes, and are easily measured by means of digital barometric pressure and compass sensors. Correlations between the current route and previously travelled/stored routes are performed based on their topographic and heading profiles in a point-by-point manner. Above-ground tests were first performed using a road vehicle and six routes to evaluate the system. The system consistently and correctly identified a 20 km route within the first 4 km. It also proved to function correctly in underground tests through the implementation of an instrumented hand-held surveyor's wheel. This system finds direct practical application in optimizing the energy management of an underground hybrid locomotive used by the mining industry in South Africa, but can also be of benefit in applications where route identification is required and using GPS is not feasible.

Jan 26, 2023

By D. Harrington

In recent years over 100,000 persons have been killed annually in the United. States by accidents; about one-fifth of these have been workers in some of our industries; about one-third have been killed by motor vehicles; about another third have mot death in home accidents, chiefly falls, burns, scalds, explosions, poisons, asphyxiations, suffocations, cuts, scratches, and so forth; and the rest have been killed in public accidents, excluding those caused by vehicles but including accidents on railroads or electric cars, drowning, and deaths by firearms and. other means. Definite statistics on nonfatal accidents are not readily available, but at least 10,000,000 fairly serious accidents probably occur in the United States annually. The latest industrial-accident statistics are obtainable from 1935 National Safety Council publications, in which annual industrial fatalities are divided about as follows (in round numbers): Agriculture, 4,500; trade and service, 4,500; construction, 3,100; transportation and public utilities, 2,900; manufacturing, 2,600; mining, quarrying, petroleum, etc., 1,900.

Jan 1, 1938

By M. Rieber

The recent history of the mercury market results almost entirely from U.S. Government actions. Its derived demand has been curtailed by U.S.E.P.A. mandates; its supply has been augmented by U.S.D.L.A. controlled stockpile releases. The resultant prices have altered its market structure, impacted mercury mining, refiners and recyclers, and affected international production and markets. From a marketplace product mercury is rapidly becoming a disposal problem. Other minerals may follow in its wake. This paper reviews developments in demand, particularly in relation to environmental constraints. Supply side impacts are considered. The impact of stockpiles, both as a market overhang and as a potential supply is reviewed. Government stockpile disposal activity is emphasized, but the size, estimated disposal rate, and quality of the private stockpiles are considered, as is the potential availability of additional material from shut-in mines.

Jan 1, 1995

By T. M. Barczak

This U.S. Bureau of Mines report investigates shield mechanics and component stress development in a two-legged longwall shield for unsymmetric canopy and base contact configurations. Previous studies analyzed shield behavior for symmetric contact configurations. The goals of these efforts are to improve longwall support selection and design. This study provides vital information that will help develop improved procedures for performance testing of longwall supports and will benefit future research to improve support design through stress optimization and evaluation of failure mechanisms. Combinations of six canopy (three symmetric and three unsymmetric) and six base (four symmetric and two unsymmetric) contacts provided a total of 36 configurations for evaluation. Of these 36 configurations, 10 were eliminated because of fixture limitations or shield instability. Controlled vertical and horizontal displacements were applied by the Bureau's mine roof simulator to the remaining 26 configurations. Component responses were determined from pressure transducer and strain gage instrumentation in order to identify contact configurations and boundary displacements that produced maximum loading in each of the support components. This report describes these test results and provides conclusions relevant to critical contact configurations for performance testing of longwall supports.

Jan 1, 1990

By Forrest T. Moyer

Injury experience in the coal-mining industry was worse in 1965 as both the frequency and severity rates of injuries increased 2 and 6 percent, respectively, over comparable data for 1966 (tables 1-8). The retrogression in the safety record during; 1965 resulted frog the less favorable record at bituminous-coal mines, which more than offset the improved injury experience at anthracite mines. The 259 fatal and 11,138 nonfatal injuries occurred at a rate of 45.77 per million man-hours of exposure and resulted in a severity rate of 8,960 days lost per million man-hours. Although the number of fatalities was the second lowest annual total in the recorded history, it was 17 higher than in 1964. At anthracite operations the total of 6 fatalities in 1965 was the lowest annual figure in statistical history. The annual numbers of nonfatal injuries at ill coal mines and the resulting rates of occurrence have varied little in the past 5 years (table 1). The total days lost from all injuries rose from 2.1.3 million in 19b4 to 2.23 million in 1965 (table 5). Fatal and permanent total injuries, with a standard time charge of 6,000 days each, accounted for 1,650,000 days; Permanent partial injuries, 191,932 clays; and temporary total disabilities, 383,911 days. The severity rate for fatal injuries was 6,241, 8 percent higher than in 1964, and the nonfatal severity rate of 2,718 days lost per million man-hours was 2 percent higher than in the preceding year. The average severity of permanent partial injuries ire; 730, or 48 days fewer per injury than in 1964. The average days lost for each temporary total injury was 36 days in each year.

Jan 1, 1968

By George Oprea, Tom Troczynski, Joe A. Rigby, Waiman Lo

The refractory lining of the tuyere line in Peirce Smith converters have usually much shorter life in service than the rest of the lining, above or below it. There are already recognized chemical, thermal and mechanical factors which contribute to the wear of the lining. Our study presents the experimental results on microstructural changes occurring on these tuyere line bricks in a nickelcopper converter. The experimental bricks, after use at the tuyere line, were investigated using SEM/EDS and XRD techniques, to identify the mineralogical changes due to interactions with the nickel-copper matte or fayalite type slag at the process temperatures. The microstructural changes were correlated with physical and mechanical properties of the brick before and after use and a wear mechanism was suggested. Although the matte does not theoretically react with the mineralogical components of the brick, a partial oxidation of the Ni-Cu sulphides was identified using a line analysis by SEM/EDS in the densified layer at the hot face, which allows for mineralogical changes at the matte-refractory interfaces, with a high probability of microcrack formation due to the thermal cycling during use. These microcracks were also identified to open through inter-granular fractures parallel to the hot face, which appeared to be the main cause of lost lining during use. The reactions between the fayalite slag and refractory brick could eventually play a role in chemical dissolution of the brick only in the superficial layer at the hot face, as no slag components were identified deep into the brick.

Jan 1, 2009

By Manjeet Chowdhry, Qingxia Liu, Phillip Choi, Zhenghe Xu

Computational chemistry methods, such as density functional theory (DFT), are powerful tools to quantify reagent-mineral interactions encountered in sulphide mineral flotation. A quantitative relationship between theoretically calculated parameters based on chemical structure of collectors and their reactivity with different metals/minerals can provide valuable insights for design and development of more powerful and tailor-made reagents offering enhanced metal/mineral selectivity. DFT calculations at B3LYP/6-311++G(3df,3pd) level were employed to elucidate the reactivity of neutral sulphide collector reagents, including thionocarbamates (TC), thioureas (TU), xanthogen-formates (XF), dialkyldithiocarbamates (DTC) and dialkyltrithiocarbonates (TTC) with different heavy metal ions (Cu2+, Zn2+ and Pb2+) in solution. The extent of delocalization of lone pair electrons of heteroatoms (attached directly to C in C=S) over C=S group was found to be the dominant factor in determining the collector’s reactivity. Order of reactivity was established as: TU > TC > XF > DTC > TTC. All the collectors showed superior affinity towards copper followed by lead. Unidentate binding was observed through sulphur atom except for xanthogen-formate for which bidentate binding mode was observed. Effect of nature of substituent groups at N and/or O atom on reactivity of thionocarbamate and thiourea was also investigated. The results obtained through DFT calculations are consistent with the experimental data reported in literature.

Jan 1, 2015

As a bubble travels through the pulp region of a flotation cell, it will collect the most hydrophobic particles of an intermediate particle size range, this being the primary source of true flotation selectivity. Despite its role on bubble-particle attachment, however, particle hydrophobicity is still missing a mathematical definition that can be used for plant simulation. In this paper, particle hydrophobicity is defined in terms of the induction time necessary for attachment and then linked to the mass of collector adsorbed per particle. This allows particle hydrophobicity to be written as a function of density of collector adsorption as well as particle size and mineralogy. The model is calibrated from the experimental measurement of the flotation rate constant. Liberation data from an industrial flotation rougher is used for model validation. It is demonstrated that the model can describe a broad experimental dataset by means of a minimal number of parameters. Main industrial application is in simulating the effect of the chemical environment upon plant metallurgical performance.

Jan 1, 2006

By JESSE L. MAURY

DEVELOPMENT of new gold mines in Canada since the price of that metal was increased in 1932 and 1933 has been of interest and importance to many of us. The day-by-day story has given an impression of aggressive effort and enough good luck so that the spirit of enterprise has been encouraged. It is the purpose of this article to report the results of a statistical appraisal which give emphatic numerical confirmation to this impression, together with certain side lights on the costs of development and equipment of new mines. The data presented have been taken from all readily available published sources up to the close of 1938 and are representative of that year. A. B. Bower did a large part .of the spadework and Weston Thomas offered many helpful suggestions.

Jan 1, 1939

By Jens Classen

"GENERAL PROJECT DATA The Sparvo Tunnel belongs to “Variante di Valico” project, a new 65 km highway link between Bologna and Florence, designed to renew the existing A1 route and to connect in a faster way Bologna and Flor-ence. It is composed of a 2,5 km twin tunnel excavated in a complex geological context, characterized by the presence of a series of surface landslides and methane gas. The gradient is 2.6 % and the minimum radius is 1’400 m. The internal diameter of the precast seg-ment lining, equivalent to the final section of the tunnel, is 13.6 m. MAIN TBM SPECIFICATIONS TBM Earth Pressure Balanced S-574 “Martina”, manufactured by Herrenknecht, has a theoretical excava-tion diameter of 15’615 mm. It is equipped with a conical shield 12.2 m long and four back-up gantries. The total length of the machine is approximately 130 m, weighing approximately 4’500 tons. The total installed power is 16’800 kW. The main drive has a diameter of 8’700 mm and has a triple axis roller type bearing equipped with a labyrinth system including 4 sealing lips. TIME SCHEDULE OF INITIAL TBM DRIVE A time schedule of the initial TBM drive is presented in the following list: •,August 25, 2011: start of the excavation of the 1st drive of the Sparvo tunnel •,October 29,2011: stop of the advance of the TBM for gear oil contamination and clogging •,October 29 to December 20, 2011: repair works on the main drive system and modifications on the conditioning system •,December 20,2011 to July 25, 2012: restart excavation of the 1st drive (north tunnel) and its breakthrough •,July 25 to November 29, 2012: 180° turning of the TBM, detailed check of the main drive seal-ing system and fixing problems on gear boxes, race ring, clamping ring and cutting wheel •,November 29,2012 to July 24, 2013: excavation of the 2nd drive (south tunnel) and its break-through •,August 2013 to July 31, 2014: disassembly of the TBM (first 4 months) and standstill of the jobsite for structural issues on precast concrete lining of the tunnel •,July 31, 2014 to March 10, 2015: inspection, dismantling and packaging of each part of the main drive (flange ring, gear box housing and main bearing). The various phases are described hereafter in detail."

Jan 1, 2016

By Lloyd A. Morley

This annual report details progress under USBM Grant G0155003 during the project period of January 1, 1977 through December 31, 1977. The report contains four principal chapters covering accomplishments in the mine electrical safety research areas of continuous monitoring, battery and battery-charging safety, and computer modeling. Highlights of the work are summarized in the last report chapter.

Jan 1, 1978

By G. Akdogan, I. J. Geldenhuys, Q. G. Reynolds

Efficient recovery of titanium from titaniferous magnetite ores continues to be a promising, yet unrealised opportunity, despite significant occurrences of titaniferous magnetite deposits worldwide and the existence of established industrial-scale practices. Current smelting processes only recover iron and vanadium, while the titanium is discarded in the waste slag. These slags are stockpiled and present massive environmental challenges, while still containing value as residual iron, vanadium and titanium. The complex mineralisation of these deposits does not allow for a significant opportunity to separate the titanium and magnetite minerals through normal physical upgrading processes. An upgrading process is therefore required to derive economic value. An efficient process technology could create an opportunity to unlock all three valuable commodities. South Africa’s Bushveld Complex, the largest known deposit of its kind in the world, is known for the high vanadium content but is also associated with relatively high concentrations of titaniferous magnetite. The quality of the Bushveld Complex was one of the drivers for the establishment of the Highveld Steel and Vanadium Company in the mid-1960s. The unfortunate demise of Highveld Steel and Vanadium created an opportunity to review current practices and evaluate the best available process for this complex ore in the context of the three elements of interest. Past and current processes, the nature of these deposits and the potential to recover titanium are assessed to highlight the potential of fluxless smelting of titaniferous magnetite to produce a titania-rich slag as feedstock to the pigment, titanium metal industry in conjunction with recovery of iron and vanadium. Ilmenite smelting practices are proposed as a suitable alternative to achieve the goal, namely sustainable processing. Keywords: Titaniferous magnetite, titanomagnetite, smelting, titania slags, comprehensive processing

Jan 1, 2020

By Chu E. Ho

This paper reviews the design of jet grouting at re-entrant corners of excavations where the diaphragm wall and secant pile wall installation were interrupted by existing utilities in the streel sidewalk. Jet grout blocks were formed to seal the gaps in the walls for excavation support, consisting of four to six columns in clusters. Jet grouting was performed around an electrical duct bank which had to be maintained. Jet grouting was executed through stratified soils using various combinations of jetting parameters for different soil strata. The installation sequence and age of the neighboring columns within a cluster will affect the jet’s ability to form subsequent columns. When jet cutting is limited next to hardened grout columns or embedded obstructions (such as diaphragm walls or secant pile walls in this case), the specific gravity (SG) of spoils would be reduced and tend toward the value of the injected grout SG. The magnitude of spoil SG is also influenced by the variability of the grout mix supplied. Specific Gravity Ratio (SGR) defined as the ratio of spoil SG to the actual grout SG at the time of jetting can be used as an indicator of successful treatment, with SGR > 1.0 indicating effective soil erosion. Verification coring and testing were implemented to confirm target column diameter and strength of grouted soils have been achieved.

May 1, 2022

By J. G. Pippenger

Rio Tinto Coal Australia (RTCA) developed Meandu Mine in Queensland, Australia in 1983 to supply thermal coal to the adjacent newly constructed Tarong Power Station (TPS). In designing the mine, RTCA selected Meandu?s best economic reserves for a 25-year life based on station owner Tarong Energy Corporation?s (TEC?s) estimated life for TPS. That 25-year plan changed dramatically in the early 2000s when TEC approved life extensions to TPS?s four existing units plus construction of a fifth unit. After reviewing Meandu?s remaining reserves, RTCA decided the nearby Kunioon reserve offered the more economic option for maintaining deliveries beyond 2010. Those plans changed yet again in 2007 when TEC chose to purchase the Meandu Mine and nearby reserves rather than extend RTCA?s contract. TEC then selected Thiess Pty Ltd (Thiess) to continue operating Meandu until the new mine at Kunioon could be developed.

Jan 1, 2011

By M. D. Aldridge

The results of designing, constructing, installing and operating a ventilation monitoring system throughout an entire commercial coal mine is presented. Measured parameters were airflow, methane, carbon monoxide, temperature, relative humidity and differential pressure. A central computer provided for automatic system operation. Preliminary tests of two remotely controlled ventilation regulators were performed in conjunction with the monitoring system.

Jan 1, 1977

By Robert C. Hickman

In its search for strategic minerals, the Bureau of Mines investigated the Rutherford Mine property in Amelia County, Va. The property was visited by F. W. Horton, mining engineer, and Margaret Fuller Boos, mineral technologist, of the Bureau of Mines, in company with Eugene Dawson, of the War Production Board, on July 16-11, 1943. An exploration program by the Bureau was recommended, and work was started on July 28, 1943, and continued until September 16, 1943. A total of 1,250 feet was diamond drilled in 5 holes on the property.

Jan 1, 1950

By Nicola Robjohns, Kenneth A. Grace, Jane Spooner

"The important volume end use sectors for the rare earth elements and yttrium continue to be in steelmaking, petroleum cracking catalysts and glass polishing. The market sectors which may provide future high volume demand, to replace the older sectors where demand has declined over the past decade, include magnets, automobile catalysts, ceramics and superconductors. Increases in production capacity in all major rare earth producing countries are expected to restrain large price increases for high purity rare earth oxides over the short term. A sharp increase in demand for yttrium in advanced ceramics and superconductors would lead to a shortage in separation capacity, however, and to a corresponding rise in prices for separated rare earths.IntroductionWhile visiting the Geology Department of the University of Toronto in 1981, Professor Lu from the Institute of Geochemistry of Academia Sinica at Gweiyang in China introduced one of his seminars with the observation that in China, rare earths are not rare at all.Indeed, while being rare in terms of abundance as measured by, say, the Clarke scale, the rare earth elements, like many other low abundance elements, are subject to geological, geochemical and mineralogical concentration.The rare earth elements comprise the fifteen inner transition elements of Group IIIB, Period 6, of the periodic table, from lanthanum to lutetium (the lanthanides), as set out in Table 1. The rare earths constitute a distinct group as they have extremely similar chemical characteristics due to the uniformity of their outer electron shells. The element yttrium is usually, by convention, included in the rare earth group as it occurs with the rare earths in nature and has properties very similar to them.The rare earths are divided into two subgroups, the ""light"" rare earths, made up of the first seven elements of the series, lanthanum to europium, and the ""heavy"" rare earths, comprising the remaining eight elements, gadolinium to lutetium, plus yttrium. These two subgroups are also referred to as the cerium subgroup and the yttrium subgroup, respectively. The subdivision is based on differences in the atomic radii resulting in somewhat different properties for the two subgroups."

Jan 1, 1991

By Hiroyuki Matsuura

The effects of P2OS or Na2O addition on the reaction rate of CO2 dissociation on the surface of FexO-base molten oxides was investigated at I 773K by isotope exchange method 1-6. The rate constant decreased with increasing P2Os content of molten oxides and the residual rate constant was observed at high P2OS content. On the other hand, the rate constant increased with increasing Na20 content for FexO-SiO2 melts, The rate constant was evaluated by the composition of oxides and the rate controlling step of CO2 dissociation was discussed.

Jan 1, 2003