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By George E. Fasching

The Bureau of Mines has developed a pulse counting system with improved energy resolution and having dual channels to process pulses at different rates and a pulse pileup detector for channel selection. Pulse input is delayed until the detector determines if any pulse is so closely followed by a second pulse as to constitute pulse pileup. If no pulse pileup is detected, the slower channel is selected; this clips the pulse to a wide pulse width to retain good energy resolution. If pulse pileup is predicted, the fast channel, with correspondingly shorter pulse width, is selected to improve resolution with respect to time. Output of the two channels is transmitted to a pulse height analyzer for interpretation. The pulse processing system can process count rates above 300,000 counts per second with little loss in energy resolution.

Jan 1, 1974

By L. V. Chugaev, Y. M. Shneerson, P. V. Zaytsev, I. V. Fomenko, M. A. Pleshkov

"Pressure oxidation (POX) is one of the most common and reliable methods of processing gold-bearing sulfide concentrates. However, when processing concentrates that contain natural carbonaceous matter, substantial gold losses occur due to autoclave preg-robbing. The latter involves formation of gold chloride complexes under typical POX conditions (high temperatures, high acidity and high ORP) and subsequent sorption of these complexes by carbonaceous matter. Naturally, chloride ion plays a significant role in the process of autoclave preg-robbing; its concentration in POX solution has a well-marked effect on subsequent gold recovery during cyanidation of POX residue. The previous research done by SRC Hydrometallurgy showed that autoclave preg-robbing of gold could be significantly inhibited by the addition of mercury(II) compounds to POX slurry. The positive effect of mercury(II) was well pronounced both at high (>20 mg/L) and low (<5 mg/L) Cl concentrations in POX solution. The successful bench-scale laboratory testing was followed by pilot plant trials at Ore Test Facility in Blagoveshchensk, Russia. The present paper provides the results of these trials. The bench-scale testing results were verified; the optimum oxidizing parameters and reagent dosage were specified. The behavior of mercury (II) at POX pilot plant was found to be in good consistency with industrial practice described in the literature.INTRODUCTION Pressure oxidation (POX) is one of the most common, reliable, and commercially proven methods of processing gold-bearing sulfide ores and concentrates. However, when processing double refractory materials that contain natural carbonaceous matter, POX technology advantages are compromised by autoclave preg-robbing of gold. The latter occurs when natural organic carbon and soluble halides are both present in autoclave feed. Strongly oxidizing conditions of POX (high temperature, oxidation-reduction potential or ORP, and acidity) favor formation of gold-halide (mostly, gold-chloride) complexes, which tend to bond with carbonaceous matter. The exact nature and mechanism of this bonding is unknown, but as the result of this, cyanide is unable to leach gold from POX residue and the precious metal is lost to the tails (Axenov et al., 2014; Dimov, Chryssoulis, & Sodhi, 2003; Fomenko, Zaytsev, Pleshkov, Chugaev, & Shneerson, 2013)."

Jan 1, 2017

By Zhenyang Wang, Yiran LIU, Xiangdong Xing, Jianliang Zhang, Zhengjian Liu

Basic characteristics of marine placer were systematically studied by chemical analyze, scanning electron microscope and X-ray diffraction in this paper. It could be found that the marine placer mainly consists of titanomagnetite and titanohematite. A series of experiments were performed to investigate reduction-magnetic separation for Fe and Ti from the marine placer. Effects of reduction temperature, reduction time, carbon ratio, magnetic density, and grinding fineness on the reduction-magnetic separation process were investigated. And the optimal process parameters were obtained as follows: the reduction temperature 1300, the reduction time 30 min, the carbon ratio 1.1, the magnetic density 50mT, and the grinding fineness of 0.074μm 86.34%. Under such conditions, the metallization rate, iron grade of magnetic substance and iron recovery reached to 94.23%, 97.19% and 90.28% respectively, and the titanium grade in non-magnetic substance and recovery of was 57.94% and 87.22% respectively. The effective separation of iron and titanium could be achieved in reduction-magnetic separation process.

Jan 1, 2015

By J. F. Neill, O&apos

[The Cartersville mining district is in Bartow County, Ga., about 40 miles northwest of Atlanta. Barite, limonite, ocher, amber, hematite, and, manganese oxide ores have been produced from the strict since about 1840. In the search for a possible source of manganese ore, Bureau of Mines engineers made a preliminary study of the district from September 1950 to January 1951. During this study 139 deposits were examined, and many mineral exposures were sampled. Manganese mineralization occurs as fine oxide and concretionary pellets in residual clays, as fine oxides in umberous clay, in brown-iron deposits, and in a limited quantity in mud ponds and Jig-tailing piles. The future supply of ferrograde manganese ore from the district, using current mining and benefication methods, appears limited to the recovery of the hard manganese ores deposits. Rough estimates indicate a reserve of manganese-bearing clays of about 8,000,000 long tons. This type of deposit has been extensively exploited and the larger deposits mined out to depths of from 50 to 200 feet. The remainder of these deposits are low grade, are covered with deep layers of colluvium, or lie below the ground-water table. Any future production from this source will require systematic prospecting, improved concentration, and an increase in the price of concentrate.]

Jan 1, 1954

By Jared Winkler, Jon A. Hummer, Aleksandar D. Bugarski, Shad Peters, Steven E. Mischler, Steve Cochrane, Shawn Vanderslice, Teresa Barone

The case study assessed submicron aerosols at a continuous miner (CM) section, diesel aerosol concentrations at the longwall (LW) section, and elemental carbon (EC) and total carbon (TC) exposures. Aerosols at CM sections were a mix of freshly generated and those from main drifts. Low ambient concentrations and personal exposures suggest effective control strategies, with further reductions possible by curbing emissions from high-emitting light-duty vehicles.

Mar 16, 2022

By Thomas Fiest, Helmut Wannenmacher, Wulf Schubert, Manuel Entfellner

Mining and tunneling in so-called “squeezing ground conditions” at high in-situ stress can result in substantial and enduring ground deformations. The magnitude of deformations is closely tied to the applied excavation- and support concept, though typically, they can reach tens of centimeters. The yielding principle is based on the idea, that the need for support capacity decreases as deformation increases. To enable controlled ground deformation and safe working conditions, yielding elements as a part of the shotcrete lining are implemented. These types of elements avoid an overstressing of the shotcrete lining. During the deformation process, the support pressure of the yielding elements and lining increases, thus stabilizing the ground. Furthermore, long-term creep deformations of the rock mass can be absorbed with such a system. This economic support technique represents the state-of-the-art infrastructure tunneling practice in squeezing ground condition. A novel yielding element of High-Strength Expanded Polystyrene (HS-EPS) was invented, which overcomes existing systems’ drawbacks. This innovative system is lightweight and allows for safe and rapid installation. Furthermore, the modular setup of the element enables an easy on-site adaption to react to in-situ deformation patterns and changing ground conditions. Recent experiences from applications in Alpine base tunnels in squeezing ground are presented.

Jun 25, 2024

By Charles W. Perry

The options of enhanced oil recovery, coal syncrude, and shale syncrude are compared by approximately equivalent economics. The physical constraints for the major enhanced oil recovery processes are described, followed by new estimates of cost. The range for all three options in terms of light syncrude equivalent are $22 to $40 per barrel in 1980 dollars.

Jan 1, 1982

By Samuel Canchaya

Los paquetes medianos y grandes de software a minería contienen en sus módulos de estimación de reservas alguna forma de análisis variográfico geoestadístico. En esa perspectiva, el presente trabajo señala la optimización de métodos tradicionales utilizados en dicha estimación a través de los conceptos y parámetros de la caracterización variográfica y estadística psra así minimizar las limitaciones de los métodos tradicionales.

May 25, 1998

By George Aristorenas, Carlos Englert, Jesús Gómez

"Laboratory test data of strain softening soils exhibit the development of a maximum (peak) shear strength followed by a decrease in the strength with continued straining. The rate of strength loss decreases such that an asymptotic minimum value, known as the residual strength, is approached. This paper presents an investigation of the evolution of strength degradation in excavation supported soils that exhibit strain softening behavior. The paper presents a numerical investigation of excavation support of slicken-sided clay, and results of shear testing on materials with similar strain softening behavior. A strain softening constitutive law is presented that can be used with the finite element computer software Plaxis for analysis of excavation support. A typical design section of a deep excavation support in stiff, fissured clay is presented that illustrates the limitations and conservatism of the residual strength approach for excavation support design. Finally, a discussion is presented on the impact of stiffer walls such as diaphragm walls, compared to less stiff systems such as sheet piles, on the design parameters.INTRODUCTIONIn the Washington, D.C. metropolitan area, the Potomac Formation is generally composed of stiff, fissured clays. Geotechnical engineers often associate the presence of slicken-sided planes within the formation as evidence that the soil cannot develop its peak strength. Although it is unclear how old and continuous these slicken-sided planes are, their occurrence, persistence and orientation appear to be somewhat random. Due to this uncertainty, the design of open cut slopes in these materials is often conservatively performed assuming residual shear strength values. This design approach may be justified for long-term open cuts when there is limited amount of geotechnical information and in view of back stability analyses of past slope failures. Furthermore, the lack of confinement in open cuts allows relatively high shear strains near the surface and toe throughout their existence, which promote mobilization of post-peak strength values and the ensuing progressive failure. Indeed, such behavior has been discussed in the past (Skempton, 1970; Schnabel et. al., 1982; Derrenbacher, 1998). A thorough study by Mesri et. al. (2003) of numerous slope failures concludes that the lower bound strength for stability analysis of non-failed slopes is the fully softened strength, which is intermediate between the peak and residual strengths, but that part of the slip surface may be in a residual condition prior to failure."

Jan 1, 2015

By Wilhelm Borchers

IN all special branches of the chemical and metallurgical industries, in which large electric furnaces became necessary for carrying out new processes or for the improvement of old ones, the development of the electric furnaces took place on much the same lines. The endeavors to make a success of a new idea brought forth many ingenious designs, which, however, almost without exception, furnished the proof that the safest and shortest way to practical success is the utmost simplicity of construction of the necessary apparatus. Our knowledge of the qualities of materials for building electric furnaces and of the constituents of the furnace-charges, especially their electric conductivity and their chemical affinity . towards one another at high temperatures, is still far from being complete, and from this fact we must conclude that the smaller the number of elements in the construction of a furnace, the fewer the number of unreliable factors both in the construction and in the operation of the electric furnace. This conclusion deserves special attention when an electric furnace for making steel has to be chosen from the constantly growing number of inventions, inasmuch as the chief con¬stituent of steel, the element iron, is a substance which in its liquid phase has so great an affinity fir those elements which are to be removed from the charge, that it is very difficult to comply with the following conditions: 1, to beat the refining-slag to the highest point of its chemical activity ; to prevent the iron from entering the slaw, or, where this cannot be done, to make it enter so that it finally appears in the end-product

Jan 1, 1910

By D. H. Xiong

Low grade oxidized iron ores are usually not economic to utilize. However, the development of SLon magnetic separators and other new technologies make the process cost lower and lower. In this paper, several low-grade oxidized iron ore process flowsheets are introduced. The key procedure is that at the early stage, SLon magnetic separators are applied to discharge as more tails as possible with very low cost, only a small portion of rough concentrate going to the cleaning stage, showing the new technologies are profitable for such iron ores.

Jan 1, 2014

Following a decline in direct and indirect employment in the minerals industry between 2000 and 2003, the situation reversed in 2004 and employment rose by 12 per cent. Furthermore, there are forecasts of continuing employment growth in the minerals industry in the immediate future. For those of us charged with promoting the virtues of a career in the minerals industry this is encouraging news, as it provides us with the evidence to promote the increasing employment opportunities of a healthy and vibrant industry. However, for many others û particularly the employers in this industry û the news is not so rosy. The jobs are there, and in increasing numbers, but the workers arenÆt! Employers right across the industry are finding it increasingly difficult to fill vacancies with suitably qualified and skilled employees and the competition is becoming fiercer. In the minerals and energy sector, questions are being asked and solutions sought on the industryÆs ability to attract and retain a skilled workforce. From many quarters û industry, government and the education sector, calls for urgent action are becoming louder. The reasons for this are well known û the nature of the work, the remote location, perceptions of the industry, an aging workforce, the gender imbalance, the shrinking demographic of school leavers. It is the latter I wish to focus on û the Generation Y demographic û those who have recently left school, those who are in higher education or have recently entered the workforce, or those who are still at secondary school. These young people are the next cohort of potential employees for the industry. But our need for them appears to be greater that their perceived need for us! How do we engage them so they are informed about the industry? How do we inform and advise them so they are prepared to consider further education and training in disciplines and skill areas relating to our industry? How do we guide and motivate them to give it their best shot and work in it û at least for part of their working life? These are fundamental questions that many within the industry have been grappling with for quite some time. Let me share with you some of the strategies that the Minerals Council is implementing to address this issue.

Jan 1, 2005

By Guy Demers

"This paper defines the responsibilities and functions of the Maintenance Department, and its organization, physical and human assets, highlighting the unique operating problems. Due to the self-sufficient aspect of the Asbestos Hill Deception Bay project, the Maintenance Department cover-s fields that are numerous and very dissimilar: production, mobile, processing, service, power generation, fire protection, heating, water and sewage disposal equipment. Added to this, buildings, plant and camps, wharves and communications equipment all demand versatility, adaptability and expertise from maintenance personnel. Good maintenance practices are a necessity in this environment and are more critical than at southern locations; that is, high-quality replacement material, complete and well-controlled preventive maintenance, major repairs on a component-replacement basis, updated inventory, efficient training and permanent contacts with suppliers, combined with an equipment improvement program, updated specifications on lubricants, hoses, seals, filters, etc., are mandatory. The seasonal aspect of the operations applies a great deal of pressure on the maintenance team, as the production months do not permit major repairs. Short- and medium range planning and accurate evaluation of equipment conditions highly influence production efficiency. Maintenance control, planning and scheduling do not follow the accepted standard routines, as personnel turnover normally does not permit an accumulation of knowledge of the equipment history and condition by the •individual tradesman."

Jan 1, 1976

By P. Lees, N. Parkinson, K. Hartley, D. M. Donaldson

The reprocessing of advanced fuels such as carbides, oxides, and cermets, containing up to 30pct pu has been studied. Dissolution of uranium carbides in nitric acid produces appreciable quantities of mellitic acid which has undesirable effects in subsequent stages of the process. Mixed oxides containing up to about 40 pct Pu in solid solution with UO, are soluble in nitric acid and a leaching type process in nitric acid for a stainless steel/UO,. PuO, fuel containing 30 pct Pu appears to be feasible. It offers considerable economic advantages THE reprocessing of the U-Cr alloy core of the Dounreay Fast Reactor was described by Buck and others at the Second Geneva conference.&apos; This paper described the flowsheet and plant for processing a relatively simple fuel of good dissolution charac- over total dissolution routes. A new oxidation-sub -limation process is described for metallic fuels containing up to 12 pct Mo. New data is presented on the solvent extraction of uranium and plutonium nitrates into tributyl phosphate -odorless kerosene and of the influence of radiolytically produced acid phosphates on this part of the process. It is concluded that there are no insuperable difficulties which will prevent the satisfactory reprocessing of high burn-up plutonium fuels by a solvent extraction route. teristics and of low-plutonium content after irradiation. However, it has been clear for some time that more satisfactory operation of the reactor can be obtained by the use of a core with better irradiation performance than U-Cr alloy and a U-Mo alloy will be used for the next charge. Recent modifications to the core mean that it is now possible to carry out irradiations of fuel element subassemblies similar to those which might be used in a fast power reactor and trials with plutonium-bearing fuel elements will be made in the relatively near future. These changes have meant that a considerable amount of reprocessing development work has had to be carried out for

Jan 1, 1963

By R. Angulo

Carbon nanotubes (CNTs) have recently emerged as materials with outstanding properties. This has promoted their consideration as reinforcements for other material systems, such as ceramics. However, one of the fundamental problems with producing CNT-reinforced ceramics is the effective dispersion of CNTs during processing. This has been successfully carried out recently using organic solvents. This paper is a preliminery investigation into the rheological behavior of aqueous CNT-alumina slips, with the objective of moving towards a more environmentally friendly aqueous tape casting process for the production of CNT-ceramic composites.

Jan 1, 2008

By Ben E. Lusk

First of all let me say what a genuine pleasure it is to be here. Acapulco certainly is a beautiful change. I&apos;m going to spend sometime talking about change, because frankly I&apos;m astounded at the rate of change in our world today. One good example of this, reminds me that the first time I spoke before the AIME two years ago, we were at the Ramada Inn in Beckley, West Virginia. Today we&apos;re at the Princess Hotel in Acapulco, Mexico. Now that&apos;s what I call a change. Seriously though, I&apos;m sure you&apos;ve all heard it said that the most consistent thing about our society is its constant change. Five years ago, no one could have predicted the changes we experienced in the United States during the first half of the 1970&apos;s. In the past twenty-four months alone, we have seen two presidents, three vice-presidents and hundreds of administration and government personnel changes. We have stumbled from one social crisis to another, while suffering through rising inflation, major energy shortages and labor unrest that could plunge us into a full scale economic depression. In view of these constant and unpredictable changes around us, it&apos;s obvious that we must learn to deal with change and "roll with the punches" if we are to survive. A controversial book published recently, explores in detail the various aspects of change and its impact on man.

Jan 1, 1974

By W. F. Marshall

This report describes exhaust-emission data from 10 diesel engines: six 4-cycle, direct-injection, naturally aspirated engines; two 4-cycle, direct-injection, turbocharged engines; one 4-cycle, precombustion-chamber, turbo-charged engine; and one 2-cycle, direct-injection engine. These engines were tested over a 3-year period (1968-70). Lowest emissions were obtained with a precombustion-chamber engine. Emissions from the 2-cycle, direct-injection engine fell within the range of emission rates for the 4-cycle, naturally aspirated, direct-injection engines. Excluding the precombustion-chamber engine and excepting one of the 4-cycle, naturally aspirated engines, carbon monoxide emission rates were about the same for all engines tested. Test data on smoke, odor, and emissions of hydrocarbons, oxides of nitro-gen, carbon monoxide, and aldehydes are given.

Jan 1, 1971

By Wilson Pascheto

One of the main outcomes of a capital project is the reliability of a new plant, system or equipment. During 20 years of experience working in various capital projects for the mining industry, the author experienced failures which have caused significant losses to Owners, in many cases amounting to millions of dollars and almost jeopardizing entire projects. Often, failures were related to faulty design, shop fabrication and/or construction. Therefore, significant opportunities exist in the Mining Industry to improve the success rate of capital projects, improve on-line time at start-up, minimize the occurrence of unplanned maintenance due to equipment failures, and all this with positive contribution to health and safety. This paper presents some examples of failures and how they could have been prevented by proper Quality Assurance methodology. It also discusses some of the main challenges in the implementation of such methodology, including awareness of the Materials discipline and availability of trained Engineers.

Jan 1, 2015

By Brenda J. Wolfe

Following successful laboratory and pilot plant investigation of dewatering characteristics of molybdenum concentrate produced by a Chilean copper/moly producer, two (2) DENVER SALA 500 Series Tube Press Filters were installed in 1994 to handle the total production volume. Moisture requirements in the filter cake have been consistently met, eliminating the need for thermal drying after filtration. Operating data and Tube Press Filter are described herein.

Jan 1, 1995

By Charles Zdazinsky

Over-break is undesirable in underground civil construction because it excessively damages rock along the perimeter of the tunnel, which directly influences the cycle times of advancement. A quicker cycle time for each process is required to optimize the operation and therefore minimizing over-break is essential for operational success.

Jan 1, 2015