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By R. Barany

In this paper, closed expressions have been obtained for the frequency spectrum of a Born-Karman square lattice in terms of elliptic and hyperelliptic integrals. This work is part of continuing research by the Bureau of Mines with the thermodynamic properties of metals and minerals. Although other workers have obtained various types of approximations for the general case of the frequency spectrum of a square lattice, no one previously has obtained closed analytic expressions for this spectrum. To understand the optical and thermodynamic properties of crystals, several investigators have studied the distribution of frequencies of normal modes of vibration of the crystal lattice. Born and Karman3 laid the foundation for the theory of lattice dynamics and obtained detailed results for the case of a one-dimensional lattice. Blackman4 used numerical techniques to estimate the frequency distribution of a two-dimensional square lattice. Mbntroll5 analytically determined the frequency distribution of a square lattice for a particular value of the force constants. He also studied the more general problem and obtained some analytic approximations, using the method of moments. However, the calculations by this method were so difficult that it was not always practicable to carry them out. Van Hove6 and Montroll7 studied the nature of the singularities in the frequency spectrum of both a two and

Jan 1, 1962

By P Navarra, R Kuhne

Dynamic simulation (discrete event simulation) is the preferred methodology to evaluate the impact of dynamic aspects of processing plants on the overall plant capacity. This tool can be used to: identify bottlenecks in the plant,justify upgrade and expansion projects by evaluating their impact, oroptimise maintenance and operating practices without disrupting the operation. Iron Ore Company of Canada's (IOC) pelletising plant is a complex operation because of multiple products, varying equipment capacity and shifting bottlenecks. Furthermore, with extensive capital requirements for projects and long lead times, a high level of confidence in project outcome is required. Therefore, a model of IOC's pelletising plant in Labrador City was constructed in 2007 by a joint IOC and Hatch team. The model includes both operational and metallurgical aspects in order to better capture the complexity of IOC operation. In this paper, the justification, boundaries, and functionality of the model are described. A comparison of simulation results to historical plant operation is given. It is observed that projects have interactions and that the benefits of combined projects are not equal to the combined benefits of the individual projects. Projects can have synergies that result in greater benefits when combined or can have overlapping benefits that result in lower benefits when combined. The power of the proposed modeling exercise lies in the ability to assess the impact of projects on overall performance.

Jan 1, 2009

By Stephen D. Cramer

The objective of the present studies was to develop thick adherent and coherent coatings of platinum and palladium on refractory metals and other substrates of industrial and engineering importance. Existing platinum and palladium electrolytes were modified to make them suitable for the electrodeposition of thick deposits. The optimum operating conditions for these electrolytes were established. Pretreatment procedures for columbium, copper, graphite, molybdenum, nickel, stainless steel, tantalum, titanium, tungsten, vanadium, and zirconium substrates were studied. New pretreatment procedures for columbium, molybdenum, stainless steel, tantalum, tungsten, and nickel were developed. The internal stress and hardness of selected electrodeposits were measured. The effects of heat treatment upon the properties of electrodeposits were studied.

Jan 1, 1967

By E. H. W. Hornbrook, P. W. B. Friske

Paper presented at the 28th International Geological Congress, Washington DC, July 1989 (International geochemical mapping sessions). The objective of the programme is to establish and maintain a nationally consistent geochemical drainage database. Towards this end systematic surveys have been conducted since 1973. To date more than 200 surveys have been completed to the required standards, representing 180 000 sites and covering about 2 100 000 km2 throughout Canada

Jun 13, 1905

By Laura Suarez, Jörgen Kajberg, Pär Jonsén

In recent years, slag, a residue from pyrometallurgical processes, has become more attractive in circular economy frameworks to increase the efficient use of resources throughout the life cycle of steel products and help in the reduction of carbon emissions. Its applicability is strongly dependent on the particle size, and therefore, the optimization of breaking processes should be approached by increasing the knowledge of the dynamics of slag to promote fracture. Increasing the knowledge on themechanical response ofmanganese slag opens up the potential for the development of cost-effective numerical models, e.g., constitutive models based on inverse engineering calibration frameworks or digital twins. In this study, rate-dependent tests of manganese slag have been performed using a split Hopkinson pressure bar device for testing its dynamic mechanical response. In order to obtain information about the crack initiation and fracture process, 2D ultra-high speed imaging was implemented with a sampling frequency of 663,200 fps for diametrically loaded specimens. Full-field deformation measurements using digital image correlation (DIC) techniques showed a staggered fracture process where failure points on mechanical response curves vary due to the internal events happening in the material. Localized frictional occurrences and inertial effects acting inside the pre-cracked matrix have a strong effect on the global mechanical response, and therefore, a great variability of strengths was obtained.

Nov 3, 2023

By Angel Benjamín

En Minera Coimolache se generan aproximadamente 700 Ton de residuos sólidos al año, de los cuales el 50 % corresponden a residuos orgánicos y a través de la fermentación anaeróbica con Microorganismos Eficaces se logra transformarlos en abono en la mitad de un mes. Estos abonos no solo son producidos en menor tiempo sino además han logrado mejorar la fertilidad del suelo transfiriendo nutrientes, incrementado la actividad microbiana y contribuyendo con la mineralización.

Sep 1, 2017

By J. Corman

Las Naciones Unidas iniciaron sus actividades dentro de la minería a través de la formación del Fondo Especial que ahora se denomina el Programa de Desarrollo de las Naciones Unidas (UNDP). Antes de la formación del Fondo Especial, la colaboración técnica de las NN.UU. era mínima y se limitaba tan sólo a prestar servidos de asesoría. Sin embargo, su impacto fue mayor debido a factores como los limitados fondos que poseía, el corto período de duración de las misiones, la incapacidad de los asesores de ajustarse a la realidad, la variable capacidad de los asesores y la falta de continuidad. En ese sentido, el presente texto señala el pronóstico de las actividades mineras de las Naciones Unidas después de la Segunda Guerra Mundial respecto al campo de la exploración y etapas técnicas posteriores, así como se muestra los errores de no contar con un apoyo técnico en los inicios del programa de exploración.

Jul 1, 1981

Historically the insurance industryÆs involvement in any project has been relatively late in the process. Often it was a case of the last item to be ticked off the checklist has been to ensure that the insurance is in place. However, in more recent times insurers have imposed more restrictions on the cover they are prepared to provide, which has in some cases necessitated a change in the contracting structure to accommodate the insurance policy(ies). In addition, changing contractual practices have changed the allocation of risk between the various parties involved. This calls for a more proactive approach to the design and implementation of an insurance program for both the construction and operational phases of any resource project. This paper explores how a risk managed approach to the design and implementation of an insurance program for a resource project can align itself with current management approaches to project development. From the authorsÆ experience, this approach is best adopted early on in the project (often in conjunction with the bankable feasibility study) and follows AZ/NZS4360 to objectively examine and compare a wide range of risk exposures of the project in a time-effective manner across the following areas: personnel; environment; general management; compliance û legislation, systems, protocols; asset management; change management; financial impacts to the organisation; products/services; service delivery; and technology. Having identified and then analysed the risk exposures according to common consequence and likelihood ratings the next step is to develop a risk map of all considered exposures. The true value of this approach lies in the development and implementation of a risk treatment plan for identified exposures where the exposure is unacceptable. The plans will lead to the optimal solution to the appropriate risk prevention, risk mitigation and risk transfer options available. This paper also examines other benefits to the project that may arise from adopting a risk managed approach in addition to the ability to design an insurance program which recognises the exposures and the ability of the organisation (and other project parties) to retain risk.

Jan 1, 2007

By Víctor Barrientos

El presente texto describe una de las formas de liderazgo en el manejo de información de las empresas a través de la técnica de Barrientos y cómo su metodología fue aplicada para el mejoramiento de la información del mantenimiento en una mina a cielo abierto. Para ello, se revisa la gestión de activos, estrategias del cambio y el liderazgo situacional con el objetivo de que alcancen el mayor nivel de desarrollo frente a una meta específica.

Oct 1, 2016

By Tiago Nunes Lima

As propriedades mecânicas de ligas TiNbSn são dependentes do processamento termomecânico. O refinamento dos grãos das ligas é obtido através de processos de conformação a frio, atingindo valores de redução que podem estar acima de 80%. Esta deformação a frio permite o aumento das propriedades mecânicas, mas pode reduzir consequentemente a ductilidade e a tenacidade das ligas. Este estudo tem como objetivo observar o efeito da laminação e forjamento a frio nas propriedades mecânicas de ligas Ti35Nb2Sn com 80% de redução. Foram realizados ensaios de tração, dureza, metalografia e microscopia das fraturas. Ambas as ligas deformadas e envelhecidas apresentam as fases ß, a” e ? em suas microestruturas, porém, com algumas mudanças microestruturais. Foi notado que a liga forjada possui maior resistência máxima a tração e dureza que a liga laminada.

Aug 16, 2017

By Ronald E. Heuer, Debra L. Virgens

INTRODUCTION Behavior of clay soils in response to tunneling is reasonably well understood by reference to the tunnel stability factor NT = Pz/su (Peck, 1969; Heuer, 1974). With this analysis tool, care must be taken to use a value of clay shear strength which represents the actual mass strength, considering such factors as slickensided fissures often found in stiff and hard clays. Behavior of clean sand and gravel soils is also reasonably well understood. Above the water table these soils must be assumed to act as running ground unless they are known to have significant cementation or have a very dense and angular interlocked grain structure. Below the water table they must be tunneled using some form of groundwater control such as dewatering, grouting, freezing, or internal fluid pressure in the tunnel such as compressed air or a slurry tunneling machine. The internal fluid pressure must approximately balance the external water head. Without such precautions these soils behave as flowing ground and may yield large volumes of water flow into the tunnel. A wide range of very fine sand, silty sand, cohesionless silt, and clayey sand soils exist in nature in a variety of geologic environments. The behavior of these soils in response to tunneling, and guidelines for anticipating their behavior, are not well described in the literature. Because of their content of fine particles, these materials may behave as if they initially have appreciable cohesion and moderate to low permeability. They may exhibit significant standup time, and require tunnel internal fluid pressure (compressed air or slurry pressure) less than the full external water head. It is important to be able to estimate the behavior of these soils when planning construction methods. For example, if the external water pressure is 140 kPa (20 psi), but soil stability at the tunnel face can be achieved as a compressed air pressure of 80 kPa (12 psi), a large cost savings may result.

Jan 1, 1987

By C. J. V. Wheatley

Recent studies of the mineralisation at Avoca in southeast Ireland, Parys Mountain in Anglesey, and Coniston in the Lake District result in the proposal of a new metallogenetic model for mineral deposits in the Southern Caledonides. A regional pattern of metal zoning exists, an axial belt, including the major copper deposits, being bordered by areas with lead-zinc deposits. Conformable lenticular pyritic zones occur in the central belt, closely associated with acid volcanic sequences and, often, post-dating them. These zones are thought to have been formed in a marine environment, mineral growth taking place below the sediment-water interface, whereas magnetite-rich zones developed under different Eh and pH conditions. Stockworks containing appreciable copper and, in some cases, lead and zinc were developed at a later date, stratigraphically below the pyritic zones, by migrating hydrothermal chloride and metal-rich fluids. Complex lead-zinc-pyrite mineralisation resulted from the reaction between pyritic zones and the final fraction of the hydrothermal fluids. Crosscutting vein-type fissure infilling mineralisation occurs in every mineral field. These deposits apparently comprise a pulsatory metasomatic sequence, closely related to tectono-stratigraphic controls, ore localisation being influenced by the coincidence of suitable structures and pyritic shale horizons. The implications for mineral exploration are considered and it is concluded that the model offers an explanation for the existing pattern of metal zoning; and it may have wide applicability to mineral deposition in geosynclinal sequences.

Dec 1, 1971

By F. Baerhold

Recycling of hydrochloric acid from the pickling of mild steel using pyrohydrolysis is a state-of-the-art technology. Recent developments have focused on the production of a high value iron oxide by-product, where the chemical purity and physical properties are the main issues. New processing routes, especially for TiO2 and Ni production, use leaching operations with hydrochloric acid. The feasibility of those processes depends on the availability of an economic and reliable process for the recovery of the acid. Depending on the level and type of impurities and the required specification of the by-product, pyrohydrolysis in a fluid bed or in a spray roast reactor can be the ideal solution. In stainless steel annealing and pickling lines, a mixture of nitric and hydrofluoric acids is used to remove the scale from the surface after heat treatment. Nitrate emissions from the pickling and the rinsing processes have to be avoided because of more stringent environmental regulations. An annealing and pickling line that is totally wastewater-free was developed, where not only the nitric/hydrofluoric acid but also the rinse water, is completely recycled. New developments to increase the HNO3-recovery rate and to obtain a metal oxide by-product that is easier to recycle are presented.

Jan 1, 2006

By Abdelaziz Baçaoui, Imane Aarab, Mohammed Derqaoui, Abdelrani Yaacoubi, Khalid El Amari, Abdelmoughit Abidi, Abderahman Etahiri

Numerous researchers have addressed the complexity of the direct flotation separation of apatite from low-grade phosphate ore. The majority of these studies were limited to the micro-flotation scale. In fact, there is no warranty that a reagent scheme that showed a direct flotation of apatite at a micro-flotation scale on pure minerals would automatically replicate the same expected results on the natural ore in the mechanical flotation cell and so was the case for the phosphate ore studied. The overall trend was concentrating apatite in the non-float product. This study aspired to thoroughly assess the flotation performance of this never-exploited low-grade sedimentary phosphate using design of experiments (DOE). Unveiling new insights on such a strategy twist, various parameters and operating conditions, namely, desliming, type of collector and depressant, reagents dosages, conditioning times, flotation time, and pH, were addressed by multiple-factor screening using asymmetrical fractional factorial design followed by statistical interpretations. The collectors tested were the sodium oleate and a fatty acid mixture (FAM). The depressants tested were sodium alginate (NaAL), corn starch, carboxymethylcellulose (CMC), and sodium silicate. The results of the multivariable analysis revealed that desliming, pH, collector dosage, and flotation time significantly influenced the flotation process. Desliming was beneficial for the yield, P2O5 recovery, and SiO2 removal; however, there was still a compromise between grade and recovery. A strongly alkaline pH value of 12 stood out from the whole range. P2O5, CO2, and SiO2 grades of the products and flotation recoveries were improved, except for P2O5 recovery, which was negatively affected. A collector dosage between 2000 and 3000 g/t increased the P2O5 grade and reduced CO2 grade and recovery, enhancing the apatite/carbonates separation. A flotation time of 15 min was significant for P2O5 grade and CO2 recovery, nevertheless, at the expense of yield and P2O5 recovery. The products having initial concentrates of 28.08% P2O5 with a recovery of 88.96% and 29.41% P2O5 with a recovery of 62.71% were obtained using 25 g/t of NaAL and 2000 g/t of the collector FAM and sodium oleate, respectively, at pH 12.

Jun 5, 2022

By John Dodd

Advances in the technology of abrasion resistant irons and steels, which could help in combating abrasion and wear in mining operations, are reviewed. Nodular irons alloyed with nickel or copper and molybdenum, with acicular, bainitic or bainitic-martensicic microstructures are described. These alloy irons combine excellent castability and relatively easy machinabilitv with good resistance to wear. Recent progress in the development of high chromium molybdenum alloy irons is outlined, by which high temperature heat treatment of massive castings can be eliminated, alloy costs can be reduced and cracking problems avoided. Data is also given on the erosion-corrosion resistance of these irons. Trends in the development of improved cast steels are outlined. Factors influencing the toughness and abrasion resistance of manganese steels are considered. The 6% Mn 1% Mo manganese steels are shown to have a useful combination of toughness and abrasion resistance. Composite castings are seen as a means of com- bating abrasion in applications involving severe impact. A brief appraisal is given of recently developed martensitic wrought steels with improved weldability.

Jan 1, 1981

By M. Royker

Gold has been demonstrated as a possible catalyst for oxidation reactions. Some evidence for a possible promotion effect of platinum has also been recorded. The influence of platinum as promoter for Au/?-Al2O3 prepared via anionic ion-exchange for the oxidation of glycerol was investigated in a batch reactor at 60°C. It is inferred that the addition of platinum reduces the catalytic activity and the rate of deactivation, resulting in an overall higher final conversion of glycerol with increasing platinum loading. The addition of platinum to the catalyst favours the formation of the desired product, glyceric acid.

Jan 1, 2012

By Mark Flower

A 20L ignition test chamber has been used to test suspensions of 7 UK and world traded coals in air and O2/CO2 mixtures typical of oxy-combustion conditions. The coals varied in rank from sub-bituminous to bituminous and were tested in varying concentrations from the ignition limit to 400g/m3. Following each successful test the combustion residue was collected, weighed and analysed within a thermogravimetric analyser, allowing Q factors to be estimated. The ignition limit varied slightly in air, but was mostly around the 200g/m3 level. With the exception of Coal C, which was much harder to ignite, it correlated roughly with coal rank. The ignition limit changed significantly with O2 concentration when in mixed O2/CO2 gases. Only a few high volatile coals ignited in 21% O2/CO2 v/v, and then only with a 2500 J, rather than a 1000J, igniter. An increase in O2/CO2 levels to 30 or 35% gave ignition patterns similar to those carried out in air with a further increase to 40% having little additional effect. In addition the minimum ignition concentration decreased with increase in O2. Heterogeneous combustion or gasification of the coal by CO2 appears to be confirmed by comparing weight loss results for air and O2/CO2 mixtures respectively for an equivalent peak pressure rise.

Jan 1, 2009

By Q. Liu, P. Katsabanis, J. A. Meech

A thermohydrodynamic computer code has been used to simulate dust explosions. For sulphide dusts, the thermodynamic predictions are used to investigate the effect of dust concentration, mineral content and inert materials as well as the quantity of sulphur dioxide produced. It was found that the amount of oxygen available for the explosion is very important and that the dust concentration which gives maximum explosion pressures is obtained at zero or slightly negative oxygen balance values. The sulphide minerals were found to have the following explosibility sequence: pyrrhotite, pyrite, chalcopyrite, sphalerite, covellite, chalcocite and galena, which is in agreement with mine experience. The results show that theoretical calculations can be used to predict explosion pressures and toxic gases produced by a dust explosion and therefore they can assist in the design of protective measures .

May 11, 1988

By Jeffrey H. Welsh

The Bureau of Mines studied the use of computerized, continuous, remote monitoring systems for safety from power system faults in underground coal mines. In this report the need to improve protection against power system faults is documented, and types of faults are identified. The relationship between mine safety regulations and computerized, continuous, remote monitoring is analyzed.

Jan 1, 1983

By Truman H. Aldrich

The red, or fossiliferous, ore is found in the Clinton group of the Silurian formation. This group is from 100 to 500 ft. thick in Alabama, and its outcrops have been mapped by the State or the U. S. Geological Survey. In some places, it is entirely missing (doubtless islands in the Silurian Sea). In Etowah County, in part of Greasy Cove and vicinity, the upper seam is a coral reef impregnated with the red ore; in this same county, step faults bring up the ore in three or four practically parallel ridges. In Blount County and on Raccoon Mountain, the ore runs under the carboniferous rocks and outcrops in the valleys. When examining the logs of holes drilled for oil, wherever the drill has gone deep enough, the writer has found the Clinton group underlying the Warrior coal field. The following records of holes drilled primarily for oil, given in Bull. No. 22, Geological Survey of Alabama, show the presence of either ore or red rock, and suggest vast resources yet to be outlined and developed for ore in the future. The locations are given by number on the map. Hole No. 1 was drilled 6 miles southeast of Russellville, Franklin County, by the Woodward Oil & Gas Co. It passed through 160 ft. of the Clinton, but only a small show of red ore was found at 1280-1400 ft. A test well, No. 2, drilled near Atwood, Franklin County, in sectioil 26, township 8, range 14, penetrated the Clinton at 1608 ft. and found 38 ft. of limy red rock, also 8 ft. of some blood red ending at 1820 ft., making 46 ft. of red rock in all. It is reported that some good ore was cut through but this work was done by a churn drill. At least 400 ft. of the formation was classified as Clinton. Well NO. 3, called Frankford Well, was bored by S. A. Hobson and associates in the northwest quarter of section 7, township 6, range 12, Franklin County. At 927 ft., it is supposed to have entered the Clinton; the log is as follows: Ft. Sandy limestone with reddish, high ferruginous argillaceous inclusions 10 Same growing more ferruginous................................ 18 Hematitic limestone......................................... 30 Same with slightly less iron.................................... 23 81

Jan 1, 1925