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By G. S. Baker, S. H. Carpenter

Langenecker has reported significant reduction in strength of high-strength metals during ultrasonic t'ibration. Decreases in static yield stress an order of magnitude greater than the calculated stress amplitude of vibrations were reported by him for a stainless steel and for tungsten. in the present work, attempts were nzadc to verify such large reductions in yield and flats stresses using resonant librations of measured amplitudes. The results show that both the soft metals (copper and aluminum) and the high-strength metals (sleels) hare reductions in yield and .flow stresses no larger than the stress amplitude of libration. BLAHA and Langenecker,' investigating the effect of vibratory stresses on the deformation of zinc and aluminum, found a decrease in the static yield and flow stresses approximately equal to the vibratory stress imposed. Langenecker later extending this work to high-strength metals such as stainless steels and tungsten2 found a much larger effect. In these metals the static yield and flow stresses decreased by an amount more than an order of magnitude greater than the calculated vibratory stresses. It was suggested that this phenomenon could be a serious hazard to high-strength structures in an acoustic environment, such as a large rocket at launch, or could be used advantageously in the working of hard-to-work materials such as the refractory metals. Langenecker and others3 have investigated the effect of high-amplitude vibrations on many metal-forming operations. The results have been quite favorable with usually a large decrease in the energy necessary for the forming operation. The processes, however, involve large frictional forces and it is not clear whether the decreases in forming forces are to be ascribed to decreased friction or to decreased flow stresses. The present paper reports an attempt to determine the effect of accurately known vibratory stresses on the static yield and flow stresses. I) EXPERIMENTAL TECHNIQUE The standard multicomponent resonator technique for measuring internal friction has been adapted to allow simultaneous high-amplitude vibration, internal-friction measurement, and tensile deformation. This has been described in detail elsewhere.4 Longitudinal oscillations of approximately 50 kc frequency are excited in a multicomponent resonator by a quartz transducer. A second transducer measures the amplitude of vibrations. Fig. 1 shows a schematic drawing of the resonator and grip arrangement and the displacement pattern produced. Since the centers of the dummy bars are at displacement nodes, they represent points where attachments will not materially affect the vibrations. The force is applied by a standard Instron tester. The sample may be deformed while simultaneously vibrating at up to 104 strain amplitude. 11) EXPERIMENTAL RESULTS The effect of high-amplitude vibrations on the yield and flow stresses of copper. aluminum, tantalum. a soft iron, and a stainless steel has been measured. In addition samples of tungsten vibrating at stress levels up to 10' dynes per sq cm have been subjected to static stresses near the static yield stress with no indication of macroscopic deformation. Fig. 2 gives typical results for 99.999 pct polycrys-talline copper. A vibratory stress of 7 x 107 dynes per sq cm is applied at points "a" and removed at points "h". The behavior of aluminum is identical. In agree-

Jan 1, 1967

By Douglas W. Fuerstenau

A detailed experimental study of breakage kinetics in a batch rod mill indicates that while the system is inherently nonlinear, the feed disappearance kinetics for the finer sizes and the coarser sizes at high holdups is well represented by first-order behavior. The set of breakage distribution functions was found to be normalizable and independent of particle holdup in the mill. The size discretized initial breakage rate functions were found to be inversely proportional to particle holdup and almost directly proportional to particle size. A linearized grinding model that results from the first-order Taylor's series expansion of the breakage rate expression was found to give good simulations of the mill product size distributions without recourse to any parameter improvement routines. Material transport through rod mills was evaluated by investigating the effect of operating variables on the holdup and residence time distribution of particulate solids flowing through the mill. Identical experiments performed in a continuous ball mill helped delineate the fundamental differences in particulate transport through these two types of mills. Mechanistic interpretations of the observed transport phenomena are presented, and their implications in the context of tumbling mill analysis and design pointed out.

Jan 1, 1980

By Siegfried Arce

Existen muchas herramientas para la gestión de proyectos. Sin embargo, éstos no están en capacidad de realizar análisis de riesgos y evaluar alternativas que consideren incertidumbre. En ese sentido, aparece GoldSim como una herramienta flexible que a través de una plataforma gráfica, posibilita la simulación probabilística y dinámica de sistemas complejos. Asimismo, permite observar las relaciones entre los diferentes elementos, de forma que nos genera transparencia del modelo preparado, por ende,confianza en el modelo y en sus resultados.

Aug 25, 2002

By Robert Merritt

Approximately 2,500 tons of low-grade uranium ore were used to conduct a field-scale heap leaching test as well as throe column leach tests. The ore used to construct the field-scale heap leaching test had a grade 0.023% U308 while the ore used fur column leach tests had a grade of 0.027% U308. The ore was crushed to minus 4 in. The field-scale heap was constructed on a clay base with parallel effluent lines running under the heap spaced 7.5 ft apart. The heap was leached for 45 days, drained, washed, and dismantled. Based on residue analysis, approximately 205 tons of ore were leached with a final U308 extraction of 96%. The heap was 17.9 ft in height and leached in a near-vertical pattern down to approximately 1 ft, at which point the leached zone become bell-shaped. Two 8-ft column charges and one 18-ft column charge were leached for 36 and 45 days, respectively. Based on residue analyses, all U308 extractions were greater than 96%. The conclusions generated by the studies showed that (1) flow rates were similar for column leaching and field-scale leaching, (2) final U308 extractions were the same for both types of leaching; however, the deeper ore beds tended to require longer leaching times, and (3) the reagent requirements were reduced with increased bed depth.

Jan 1, 1980

By Benjamin A. Allou

La seule production de columbo-tantalite réalisée en Côte d?Ivoire est effectuée dans les éluvions et alluvions du gisement d?Issia, localisé au Centre- Ouest de la Côte d?Ivoire. Même si un lien direct avec les roches granitiques est suspecté, aucune attention particulière n?a été accordée à l?étude de la minéralisation primaire en relation avec l?évolution des granites et des pegmatites associées. Ces granites, qui sont en intrusion dans les roches sédimentaires du Protérozoïque inférieur, comprennent : le granite orienté à deux micas (Lobo), le granite orienté à muscovite dominante (Bitapia) et le granite porphyroïde non orienté à muscovite dominante (Issia). Les résultats de cette étude indiquent que les pegmatites à Nb-Ta-Be-Li sont liées au granite de type Issia. Les observations de terrain et les analyses sur roche totale des granites montrent que: (1) les trois principaux granites de la région sont de type- S et peralumineux dans leur composition, (2) ils ont été formés pendant la période tardi- à post-Éburnéenne, (3) le granite d?Issia fut le dernier à se mettre en place. Les pegmatites liées au granite d?Issia ont été classées en quatre types : Apegmatites stériles; B- pegmatites à Be; C- pegmatites zonées à Nb-Ta-Be; et Dpegmatites zonées à Be-Nb-Ta-Li. Les pegmatites zonées comprennent les zones suivantes: I- zone à aplite; II- zone graphique; III- zone à albite, microcline, béryl et columbo-tantalite; IV - zone à microcline massive; V- zone à quartz. Ces pegmatites présentent une zone d?altération métasomatique externe. La minéralisation de Ta, Nb et Be est liées à la zone III des pegmatites de types C et D, et celle de Li est associée aux greisens qui peuvent être observés n?importe où dans les pegmatites de type D. Les données de terrain et de laboratoire indiquent que le granite d?Issia est la roche parentale des pegmatites à éléments rares de la région. Les pegmatites minéralisées sont distribuées seulement autour du granite d?Issia et les patrons des terres rares des granites et ceux des pegmatites à éléments rares sont très similaires. Les analyses de la composition totale montrent un lien génétique entre le granite d?Issia et les pegmatites à éléments rares. Il est suggéré que les pegmatites ont été formées durant le transport et la cristallisation fractionnée du magma.

May 1, 2003

Escalating energy and electricity costs have become one of the largest drivers of expenditure in mining operations. Over the last eight years, energy costs have tripled when expressed as a percentage of total expenses in South African mines. In an effort to manage and reduce electricity costs, energy management strategies can be developed, inefficient operating units replaced, and the operation of energy-consuming components of ventilation systems optimized. Power consumption on mines is controlled mainly by three strategies, namely load clipping, by which energy use is reduced for certain parts of the day; load shifting, by which energy use is shifted to other parts of the day; and energy efficiency, by which energy use is reduced permanently. In this paper several projects that were implemented using the first two strategies of load clipping and load shifting are investigated. The actual and potential savings that can be achieved by implementing such energysaving interventions are presented. To reduce the operating costs of ventilating and cooling underground mines permanently, system optimization studies must be completed. Methods that can be used to reduce energy usage by optimizing cooling and ventilation systems are described, and network simulation models that accurately reflect the current and planned ventilation conditions are discussed. These models are then used to examine various options for improving the overall ventilation and cooling strategy. Different optimization scenarios can be simulated, and this assists the design engineer in obtaining the most energy-efficient system that will satisfy design workplace conditions. The final outcome is a reduction in operating costs, which can result in better operating margins and an extension of the life of mine.

Jan 1, 2014

By Henk E. Brassinga

In Rotterdam a number of underground parking facilities have been built and are under development in the inner city, and in the suburbs. These parking facilities are located at already densely built areas. The design of these constructions has to take into account the impact of the building activities and that of the final construction on the surroundings. In this paper some examples of the different building methods of newly realized underground parking facilities are described, and problems that occurred during the construction are pointed out. In the soil conditions as present in Rotterdam the cost effectiveness of underground facilities can be improved by deepening the parking facility, and at the same time reducing the surface area so that the total parking volume remains constant. In this way the total volume of the diaphragm walls and the costs of the project is reduced.

Jan 1, 2006

By Jewel A. G. Gomes

Electrocoagulation (EC) has been performed with Al-Fe electrode system with changing polarity for the removal of arsenic from water. The removal process has been studied using ICP-AES and Anodic Stripping Voltammetry with a wide range of arsenic concentration (1-1000 ppm) at various pH (4-10) and residence times (1-60 min). Electrochemically generated by-products have been analyzed using XRD, FTIR, XPS, SEM/EDS and Mössbauer Spectroscopy. Results revealed expected crystalline iron oxides (magnetite (Fe3O4), lepidocrocite (FeO(OH)), iron oxide (FeO)) and aluminum oxides (bayerite (Al(OH)3), diaspore (AlO(OH)), mansfieldite (AlAsO4?2(H2O)), as well as some interaction between the phases. The amorphous or ultra-fine particular phase was also found in the floc. The substitution of Fe3+ ions by Al3+ ions in the solid surface has been observed, indicating an alternative removal mechanism of arsenic in these metal hydroxides and oxyhydroxides by providing larger surface area for arsenic adsorption via retarding the crystalline formation of iron oxides.

Jan 1, 2006

By Andy Alder

The Docklands Light Railway (DLR) Extension to Woolwich Arsenal provides a much-needed public transport link to this area of London. The project includes construction of 5.3mID running tunnels under the River Thames, in ground conditions that proved challenging for the Earth Pressure Balance Tunnel Boring Machine (TBM). The project also includes cut and cover tunnel approaches, an underground station, and an emergency shaft on the bank of the river. Major challenges have included tunneling under sensitive infrastructure, and working adjacent to existing operational railways at Woolwich Arsenal. This paper will describe the design and construction of the project and how these challenges were overcome.

Jan 1, 2008

By Harry Perry

One of the most notable achievements of the iron and steel industry in the United States in this century has been the general increase in productivity of individual blast furnaces and the reduction in coke rate. Most of the improvement in furnace operations has occurred within the past decade. During this time the output of the average furnace increased about one-third, while fuel rates decreased from 15 to 20 percent. For example, in 1949, the iron and steel industry produced 811.2 short tons of pig iron per blast-furnace day with a coke rate of 1,870.4 pounds per ton of pig iron, By 1960, the average production of pig iron per blast-furnace day had risen to 1,182.4 tons, while the coke rate had decreased to 1,497 pounds per ton of pig iron. These figures are averages for the entire industry; many furnaces produced over 2,000 tons per day and one furnace, operating on pellets, reached 2,700 tons of pig iron per day, Coke rates of individual furnaces varied, but some furnaces operated on less than 1,200 pounds per ton of pig iron. The significance of this decrease in coke rate is shown clearly when data on pig-iron production and coke consumption in 1959 are compared with 1948. In 1948, 57.3 million short tons of coke was charged into blast furnaces to produce 60.1 million tons of pig iron; in 1959 only 47.6 million tons of coke was needed to produce 60.2 million tons of pig iron. Thus, in 1959, nearly 10 million tons less coke was required to produce about the same amount of pig iron as was produced in 1948.

Jan 1, 1962

By E. V. Lilford

The South African Minerals Development Act (?the Act?) has been promulgated and will come into full force and effect once it is gazetted. Thereafter, all Old Order mineral rights will have to be converted into New Order mineral rights within a 5-year period, probably by the end of 2008. The conversion of rights will be achieved only with the demonstrated inclusion of empowerment groups in the conversion applications. In addition to the Act, the first draft of the proposed Royalty Bill (?the Bill?) was released during the week beginning 17 March 2003. Comments on the Bill?s contents had to be submitted before 30 April 2003. The contents were to be considered in terms of applicability and acceptability to the South African minerals industry, where after proposed comments and suggested amendments were to be submitted to the relevant State Treasury office. Specifically referring to the Bill, the general response from the industry is one of concern. Since any royalty is tantamount to a tax, the general feeling is that the current mining taxation rates are already internationally competitive and to increase these effective rates, notably at differing rates depending on commodity type, will have an adverse impact on the South African mining industry. A number of these impacts can be mitigated to some degree, depending on the flexibility of the State to address the major concerns.

Jan 1, 2003

The above referenced contract between Badger Manufacturing Corporation and the U. S Bureau of Mines was executed June 30, 1975, as a result of the request for proposals for innovative machine concepts. We selected the cutting machine category because of the obvious lack of technical progress in this field for many years: Phase I of the contract required blasting fragmentation tests to determine proper blasting patterns for use with the auger-type kerf cutting machine. Phase II required design concept development for a machine capable of cutting a circular void as an aid to blasting.

Jan 1, 1975

By Patrick Frenette

Résumé La Mine Goldex entrera en production au 2ième trimestre de 2008. Pour permettre une production de l?ordre de 6960 tpj, le forage ITH à une pression de 400 psi (28 bar) à été sélectionné. Il s?agira d?une des premières applications du forage ITH à cette pression sous terre. Cet article traitera des gains anticipés et montrera certains résultats préliminaires. Il sera aussi question du bras manipulateur utilisé pour manipuler les tiges de forage. Abstract The Goldex Mine will start production in the second quarter of 2008. In order to achieve a production of 6960 tpd, ITH drilling at 400 psi (28 bar) was selected. ITH drilling at this pressure will be one of the first underground applications. This paper will discuss the anticipated gains and show some preliminary results. The use of the rod handler will also be discussed.

Feb 1, 2008

By Brad Simser

The Brunswick No. 12 Mine is a 10 000 tonne per day producer of lead-zinc-copper-silver ore that has been in operation since 1964. Mining of this multiple lens deposit is primarily by blasthole stoping techniques between 400m and 1200m below surface. The combination of a high overall extraction ratio and high horizontal stresses (twice the vertical) has elevated the induced stress regime to levels comparable to much deeper operations. Improved mine design, and a better understanding of how the rock mass responds to mining in high stress environments is essential to improve overall recoveries and maintain safety. Seismic monitoring has proven to be an essential tool at Brunswick, for both short-term safety of workers, and long-term strategic planning. Practical case studies illustrate how seismic data, particularly source parameter information, can be used to measure the rockmass response to mining and improve mining layouts in difficult regions. As the global trend continues towards mining in deeper, higher stress environments (e.g. South African Witswatersrand Basin, Sudbury Basin) and as local extraction and thus ground stresses continue to increase in existing deposits, seismic monitoring will play a critical role in mining safely and economically.

May 1, 2003

By D. A. Wilson

A cyclic leaching process was developed for selectively leaching and recovering cadmium from nickel-cadmium scrap battery waste. The six major steps in the process are the following: (1) washing the plates to remove KOH electrolyte, (2) roasting at 550° to 600° C to oxidize metallic cadmium and decompose cadmium and nickel salts, (3) leaching with an ammonium nitrate solution, (4) precipitation of the leached cadmium from solution as cadmium carbonate using CO2 gas, (5) removal of CO2 from the lixiviator by adjusting to pH 4.5, heating, and evacuating the system, and (6) removal of small amounts of leached nickel from the lixiviator using a solvent extraction technique. The regenerated lixiviator is then recycled to leach additional plates. Cadmium extraction was 94 percent and the cadmium carbonate product contained 0.14 percent nickel and 0.12 percent cobalt impurity. The leached plates were smelted to a high nickel-low iron alloy with no detectable amounts of cadmium.

Jan 1, 1971

By Paul M. Buttermore

As part of a national canvass of water use the Bureau of Mines compiled data on water requirements in the petroleum and natural gas industries for the calendar year 1962, specifically in well drilling, secondary-recovery operations, and natural gas processing plants. Total new water use in the petroleum industry of the United States, excluding refining, was 5.3 billion barrels. Secondary-recovery operations and natural gas processing plants required about 2.5 billion barrels of new water input; each of these requirements was about eight times greater than that for well drilling. Total use, including recirculated water, was 45.3 billion barrels of which 3.4 billion barrels was consumed. The greatest use of recirculated water was for natural gas processing, amounting to 38.2 billion barrels. Projections of total water use show that by 1975, 75.4 billion barrels will be used by the petroleum industry, of which 10.2 billion barrels will be new water. By 1985, the total use requirement will be 92.8 billion barrels, of which 13.1 billion barrels will be new water.

Jan 1, 1966

By Paul M. Buttermore

As part of a national canvass of water use the Bureau of Mines compiled data on water requirements in the petroleum and natural gas industries for the calendar year 1962, specifically in well drilling, secondary-recovery operations, and natural gas processing plants. Total new water use in the petroleum industry of the United States, excluding refining, was 5.3 billion barrels. Secondary-recovery operations and natural gas processing plants required about 2.5 billion barrels of new water input; each of these requirements was about eight times greater than that for well drilling. Total use, including recirculated water, was 45.3 billion barrels of which 3.4 billion barrels was consumed. The greatest use of recirculated water was for natural gas processing, amounting to 38.2 billion barrels. Projections of total water use show that by 1975, 75.4 billion barrels will be used by the petroleum industry, of which 10.2 billion barrels will be new water. By 1985, the total use requirement will be 92.8 billion barrels, of which 13.1 billion barrels will be new water.

Jan 1, 1966

By R. H. Storch

"A preliminary examination of the Bi-Metallic molybdenum prospect was made in October 1944, as a result of which it was recommended that a trench exploration project be undertaken on the property. This report presents the information obtained from project work done during June 1945.In its program of exploration of mineral deposits, the Bureau of Lanes has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to the national security and. economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.With respect to this report, special acknowledgment is due S. H. Lorain, chief, Albany Division, Mining Branch, for aid in preparing the report.The property is situated in the NW1/4, sec. 26, T. 39 N., R. 29 E. about 21 miles northeast of Tonasket. Tonasket (population 643), the nearest town, is a way point on a branch line of the Great Northern Railway. The prospect is reached by a good gravel road through Havillah to Vincent's ranch, about 3 miles northeast of Havillah. From the ranch, an abandoned dirt road extends to the portal of the Moly alit, about 1 mile distant. The mine road could be kept open without difficulty if properly graded and surfaced."

Aug 1, 1946

By E A. Amaral Jr, A C. Chieregati, J C. O Souza

Cross-belt samplers are designed to sample particulate material in processing plants, usually when there is no space to install a conventional linear falling stream sampler. Most of the available cross-belt samplers are mounted on the top of conveyor belts, and remove each increment from a loaded moving conveyor with a 360° rotation of an open faced cutter, in a plane perpendicular to the material flow. Despite the practicality of this equipment and the fact that it occupies very little space in the plant, cross-belt samplers are well known for collecting biased samples, especially due to the increment extraction error. Sampling consultants around the world tend to condemn this sampling equipment, claiming that it is incapable of collecting the fine material from the bottom part of the load, and, since the sampling probability is not uniform for all fragments and depends on its position in the stream, this kind of sampler generates biased samples and its use should be avoided. Furthermore, the greater the segregation effect between particles, the larger the bias. However, some plants, whose initial design did not plan for the installation of a falling stream sampler, must rely on cross-belt samples for process control and reconciliation. For the past years, sampling equipment manufacturers have been putting effort in modifying the cross-belt sampler design in order to comply with the principles of correct sampling. Changes to the cutter material, shape, position, speed and movement in relation to the material flow have been made, and are continually being tested for different types of ore with various chemical and physical characteristics. This paper presents the improvements made to a cross-belt sampler at a gold plant feed in Brazil and describes the tests performed until it was possible to validate the new sampling equipment for reconciliation purposes.CITATION:Chieregati, A C, Amaral Jr, E A and Souza, J C O, 2017. Validation of a modified cross-belt sampler for reconciliation purposes, in Proceedings Eighth World Conference on Sampling and Blending , pp 247–254 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By S. J. Rodgers

This report presents the results of in-mine studies to determine the severity of dust sources in conventional mining operations. Three underground coal mines were surveyed using gravimetric samplers and GCA RAM-1 continuous dust monitors. Two additional mines were surveyed using only GCA RAM-1 monitors. Data on dust control methods were acquired during the survey, also. The results indicated that cutting/drilling and loading out were the dustiest operations during a conventional mining cycle. Roof bolting, shot firing and product transport were less severe dust sources.

Jan 1, 1983