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By Hugo Vásquez Rosas

Jul 20, 1956

By Lowell Stroud

Ten natural gases containing from 0.023 to 8.4 percent helium were investigated. In seven high-helium samples, the isotopic abundance of Ne21 was greater than in the atmosphere, being supplemented by 33 to 85 percent of "excess" or "radiogenic" Ne21. The ratio of He4/Ne21(rad) in these gases was evaluated and found to vary between 2.9 x 107 and 5.9 x 107 , a factor of approximately 2. Argon concentrations were determined by the isotope dilution method. The isotopic ratios of Ar40/Ar36 in the high-helium gases were from 5 to 75 times the atmospheric value, with the Ar40 being about 80 to 99 percent radiogenic in nature. The ratios of He4/Ar40(rad) in all 10 gases were evaluated and found to range from 4 to 18. The isotopic ratio of N14/N15 in four of the high-helium gases was essentially the same as in the atmosphere; in three cases it was approximately 5 percent higher than the atmospheric value of 272.0. The genesis of nitrogen and the relationship of nitrogen to helium in natural gases were reviewed and are discussed in terms of a theory for the concurrent generation of nitrogen, helium, radiogenic neon 21, and petroleum (hydrocarbon gases and liquids).

Jan 1, 1967

By N DavT

Pyritic tailings from the Quirke mine waste management area in Elliot Lake, Ontario were subjected to long-term column leaching experiments in two PVC columns measuring 122 cm in height and 15.2 cm in diameter. At the end of the leaching experiments, the columns were taken apart and sampled at 5 cm intervals for quantitative mineralogical and geochemical characterisation. Each column is represented by a total of ten samples. Polished sections, prepared from the samples, were studied by optical microscopy, scanning electron microscopy, electron microprobe and X-ray diffraction techniques. Mineral quantities were determined based on linear mixing models of whole rock and mineral compositions. Pyrite particle sizes were measured by image analysis interfaced to an electron microprobe. The tailings are coarse-grained (ie 96 per cent passing 75 ¦m) and composed of quartz, K-feldspar, muscovite and pyrite. Pyrite is homogenous and occurs as liberated particles displaying angular to subangular boundaries with strong dissolution features at the end of the leaching experiments. Based on up to 3518 particles measured in a sample, pyrite particle sizes range from 1.7 to 78.6 ¦m. Pyrite concentrations vary from 0.1 to 7.8 wt per cent, depending upon their location from the top of the columns. These correspond to pyrite losses of up to 99 per cent from their original level of 7.2 wt per cent in the upper half of the columns. Pyrite oxidation rates in terms of moles of pyrite oxidised per mole of pyrite per square metre per second were calculated from the effluent data and the measured pyrite particle sizes. The rates vary from 1.71+10-12 to 5.78+10-10 mole+m-2+s-1 within the 1.5 to 3.5 pH range for 10 ¦m particles. These results are comparable with the published oxidation rates at pH 2 where the dissolved oxygen is the only oxidant.

Jan 1, 2003

By Leandro Brunholi Ramos

As superligas de níquel apresentam boa combinação de resistência à corrosão e à oxidação, resistência mecânica, resistência à fadiga e à fluência, além de conseguirem operar em temperaturas elevadas, mantendo tais propriedades. A liga Inconel 625 vem sendo estudada como revestimentos, obtidos por cladeamento ou aspersão térmica, para tubos de aços ao carbono utilizados nas indústrias de petróleo e gás. Esses tubos poderão ser unidos pela técnica de soldagem, quando então se obtém uma junta Inconel-Inconel, e isso pode acarretar modificações nas propriedades dessas superligas. O presente trabalho objetiva obter uma junta soldada da liga Inconel 625 empregandose o processo de soldagem a arco utilizando eletrodo revestido Ni-Cr-Mo 3 e caracterizar o cordão de solda quanto à microestrutura, à dureza e à corrosão. A microestrutura foi avaliada por microscopia óptica; para dureza foi realizado perfil de microdureza Vickers ao longo da junta soldada; quanto à corrosão foram realizadas curvas potenciodinâmicas em três diferentes soluções: 3,5% NaCl, 3,5% NaCl + 0,01M Na2S2O3 e 3,5% NaCl + 1N H2SO4. Os resultados obtidos mostraram que a zona fundida tem microestrutura dendrítica, sendo a zona afetada pelo calor de aproximadamente 1,2 mm de extensão. A solda não alterou significativamente as propriedades de corrosão e dureza.

Aug 17, 2017

By B Besa

Australia is a world leader in the design and operation of mines accessed by the decline method. Literature indicates that a number of metalliferous underground mines using the decline system are also increasing steadily. This increase has generated a great deal of interest in underground haulage systems in future due to the huge costs involved in the development of declines. Studies have also shown that the current method of accessing orebodies by the conventional decline method has proved to be expensive, especially for narrow vein deposits. This is because decline development costs are influenced by mine planning and design parameters as well as available haulage systems that the mining engineer can choose from. The current access method suggests that more waste material is being extracted because of the size of decline openings adopted (5.5 mW and 5.5 mH). Also the conventional 1:7 decline gradient and turning radius of 20 m makes decline lengths, as well as the duration of development, excessively longer. This paper discusses results of a mine design case study with monorail technology as a method of accessing and developing the decline. The proposed system is economical, has high advance rates and offers a significant reduction in capital expenditure. The study compares costs, development metres and the duration of decline development using the monorail system with the conventional (truck haulage) access method. Results obtained indicate that the monorail technology has the potential to reduce the decline length by over 62.6 per cent and decline costs by 63 per cent for the case study. The monorail system also reduces the total capital development costs by 22 per cent for the same case study. Due to rapid development resulting from increased advance rates and the shorter decline length coupled with smaller decline openings, the time to access the deposit reduced by 71.8 per cent. This case study demonstrates that the economics of narrow vein deposits can be improved significantly by using the monorail system of decline development.

Jan 1, 2008

By John S. Stevenson

The Twin ''J' mine is on mount Sicker; 8 miles by road northwest from Duncan; on Vancouver island. It includes the old Lenora; Tyee; and Richard III mines; formerly under separate ownership but now under the single ownership of Twin "J' Mines; Limited.

Jan 1, 1954

By H. M. A. Rice

"The Ainsworth mining camp is on the west side of Kootenay lake; British Columbia; 14 miles south of the town of Kaslo. It is in one of the oldest mining districts in central British Columbia; for mining started there in 1888. Its principal production was between 1905 and 1920. Activity since then has been sporadic. According to available records; some 222; 000 tons of ore had been produced from the camp up to 1942.GENERAL GEOLOGY Bedrock in the district consists of a succession of quartzite, quartz-mica schist, hornblende schist, and limestone of Late Precambrian, Carboniferous, and Triassic age. Most of the hornblende schists are of volcanic origin but some formed from related intrusions. The Nelson granodiorite batholith of Jurassic age borders the camp on the west. There is also a series of basic dykes of much later age."

Jan 1, 1954

By W. L. Zeigler

The mill is a departure from gravity concentration and has gained a reputation for the low initial cost of erection, extreme simplicity and the low cost of milling on the refractory character of the ore which is treated. The structure is of heavy timbers with board walls and corrugated roofing. The floors are concrete and the general layout is of the ground floor only. All the machines are driven by individual motors and the transmission usually found in such a plant is entirely absent. (Fig. 2.) ORE The ore from the Galena mine is sheared Wallace quartzite replaced with quartz, siderite, pyrite, sphalerite, gray copper (tetrahedrite) and very fine-grained argentiferous galena. Much of the silver is undoubtedly associated with the gray copper, the amount, however, apparently varies with different localities in the vein. An average assay of the ore is 6.0 per cent. lead, 1.3 per cent. zinc, 0.3 per cent. copper, 17.5 per cent. iron and 4.5 oz. silver. The concentrates produced are of an average 53 per cent. lead, 40 oz. silver, 8 per cent. zinc and 11 per cent. iron, while the tailings are 0.5 per cent. lead, 0.4 oz. silver. With the present market for zinc no attempt is made to produce a zinc concentrate.

Jan 1, 1927

By Yoshii Y

Many kinds of shield machines are being driven in the soft ground of Tokyo metropolitan area. Tunnel alignments for underground power transmission lines are generally planned to pass under public roads where facilities, especially life-line facilities, are densely located. Therefore, it is frequently required to drive the shield machines along very sharply curving routes. This paper reports on the performance of the new shield machine - the Sharp Curve Excavation Shield Machine - developed by Tokyo Electric Power Co., Inc., which can freely drive along a much sharper curve than conventional machines. Some of features of the developed devices of this machine are, maximum flexing angle of 6.5 degree in all deirection at the middle of shield body, maximum bending angle of 3.5 degree in all direction at the cutter disc, and so on. This shield machine can there- fore drive along curve of minimum radius 15m. The machine was confidently applied to the const- ruction of tunnel in soft clay strata at N values 2 to 5. Outer diameter 3.7m. Length 202m. Horizontal curve; radius 15m, length 20m x 2. Vertical curve; radius 30 m, inclined driven up 29%. The behaviors of the shield machine, segments and surrounding ground were monitored during construction for safety and efficiency check of this machine.

Jan 1, 1987

By J-P Franzidis, E V. Manl, K Runge

Over recent years a number of techniques have been developed as part of the Australian Minerals Industries Research Association (AMIRA) P9 project to represent mathematically or measure directly subprocesses occurring in flotation cells. These include the determination of a:machine parameter (bubble surface area flux, Sb); froth parameter (froth recovery, Rf); entrainment and drainage parameters; and ore floatability parameter (Pi). A cost-effective methodology was developed for using these techniques to derive models of flotation circuits. This methodology was applied to derive a model of the flotation circuit at the Western Mining Corporation (WMC) Ltd Mt Keith Nickel Concentrator. The model was used to simulate a number of minor circuit flowsheet changes, the results of which are discussed in this paper. One year later, a second study of this plant was conducted. In this second study, data were collected while operating the plant in the flowsheet configurations that were simulated from the model developed from the first study. The results obtained from the second study showed reasonable agreement with the trends predicted from the first study model; discrepancies can be explained in terms of the model assumptions. This suggests that this simple circuit modelling methodology can be useful in assisting plant engineers to optimise flotation circuits.

Jan 1, 2000

By William B. Plank

ENGINEERING students to the number of 73,269 had been enrolled in United States and Canadian schools on Nov. 5, 1945, but, as shown in the following tables, even this sizable number will not greatly remedy the 150,000 deficit reported by Vannevar Bush, director of the U. S. Office of Scientific Research and Development, to exist in the engineering and scientific man-power supply. These figures were received in advance from the Society for the Promotion of Engineering Education, and are given in detail in the January 1946 issue of the Journal of Engineering Education. Although the enrollment on Nov. 5 was an increase of 76% over the low of 41,632 in 1944-45, it was still 36% below the peak enrollment in 1941-42 of 115, 228. These figures include both undergraduate students and graduate students in the schools of the United States and Canada and are therefore comparable. As was to be expected, almost half of this enrollment is in the first or freshman year and 25% of the total are veterans. Also, 1,850, or about 2.5%, are women. A measure of the seriousness of the engineering graduate supply in these two countries is indicated by the trend of the number of first degrees that have been conferred during this period of scarcity:

Jan 1, 1946

By S. Tan

In this paper, several commonly used computer truck dispatching criteria are evaluated. A computer-oriented truck dispatching and production simulator was developed to provide data for comprehensive cross comparison among the dispatching criteria. The definitions, primary considerations, characteristics, and performances of these dispatching criteria were investigated. From the simulation results, it was concluded that, in general, no one criterion can dominate all others. All basic dispatching criteria including minimizing truck waiting time, minimizing shovel waiting time, minimizing truck saturation, maximizing truck momentary productivity, or truck routes optimization provide a local optimal solution. To obtain a direct global optimization solution for this complex stochastic process does not appear to be likely. Therefore, the search for an optimal dispatching criterion that will fit all conditions may not be realistic. However, based on the simulation results of the mine operation, several dispatching criteria which have good potential to increase performance can be selected. It may be necessary to search for the best combination of these truck dispatching criteria for a given situation. For example, a truck flow measurement such as the truck clustering factor at shovels can be used as a switch parameter to change from one criterion to another. The values for the switch parameter at which actions should be taken to change the criterion can be established through simulation programs.

Jan 1, 1992

By Thomas J. Kingston

A general overview of the taconite crushing process at Minntac is presented The process is controlled from a central control where the control room operator uses closed circuit TV, computer process control and alarms, graphic panels, and radio communication to roving attendants to run the Plant. This paper points out the operating controls and parameters as the plant operator sees and uses them.

Jan 1, 1980

By Denis Yeung

In an effort to find better ways to dispose of potentially toxic material, the effect of longitudinal and lateral dispersion on the dilution of toxic fluids was investigated numerically and experimentally. Homogeneous and non- homogeneous tests were conducted to model this effect for surface mine backfills. These tests used a high-density zone [package] to bury undesirable material. The studies, utilizing inert tracers, showed that an increase in density in a soil will decrease the maximum level of tracer in the discharge. Within the range of experiments performed and using only natural materials, a 65 percent reduction in peak concentration was obtained.

Jan 1, 1982

By T. M. Yegulalp

Geometric programming is a mathematical optimization technique, first formulated by Zener [1], for dealing with certain types of functions which typically arise in engineering design problems. The theory provides algorithms for finding the optimal solution, existence theorems by which one can show that a particular design is possible or not; and characterization theorems that especially make possible to obtain the relationships among the optimal design parameters at optimum. It has been demonstrated [2] that this technique can be applied to several design problems in chemical, electrical and mechanical engineering. Design problems in mining, metallurgical and mineral engineering have many aspects similar to that of other engineering problems. Thus it is only natural to consider geometric programming as a potential tool for solving certain optimization problems in mineral industries.

Jan 1, 1974

By Taylor GP

Mining Lease SML 57 was registered to Mount Kasi on 5 January, 1995. The Mount Kasi gold mine is located in Vanua Levu, Fiji's second largest island and operated from 1932 to 1946 producing 261,000t of ore at an average grade of 7.5g/t Au. The deposit represents a structurally controlled style of high sulphidation copper gold mineralisation with peripheral low sulphidation mesothermal vein type gold mineralisation. The resource consists of 1,048,000 tonnes of residual soils (eluvium) containing 1.9 g/t Au at 0.5 g/t Au cut off and 1,240,000 tonnes of hard rock at 3.0 g/t Au and 1.0 g/t Au cut. 94 drill holes, 298 auger holes and 85 pits were modelled to outline the resource. 29% of the pits bottomed in mineralisation and it is likely the full thickness of eluvium has been understated. The pit is scheduled to produce 500,000 tonnes of ore per annum to yield 35,000 ounces of gold with an initial 2 years of eluvial ore followed by a further 2 years of hard rock ore. Total capital costs are estimated to be less than 10.0 million dollars with construction planned to commence in 1995. The likelihood of locating further ore is high.

Jan 1, 1995

By Marcella Gautê Cavalcante Xavier

As ligas livres de chumbo (Lead-free solder alloys) potencialmente utilizáveis em processos de soldagem branda, tais como as ligas à base de Sn, vêm sendo estudadas como alternativas para substituir as ligas do sistema Sn-Pb. Em vista disto, o presente trabalho, aborda tanto a análise das características microestruturais formadas durante a solidificação transitória das ligas eutética Sn-0,2%Ni e hipereutética Sn-0,5%Ni, quanto a determinação das suas respectivas correlações com os parâmetros térmicos de solidificação: velocidade da isoterma eutética (VE) e taxa de resfriamento (?E). Para tanto, as ligas foram solidificadas unidirecionalmente no sentido vertical ascendente e em regime transiente, e caracterizadas por técnicas de microscopias ótica e eletrônica de varredura. Na liga hipereutética Sn-0,5%Ni, o aumento da quantidade de Ni na liga influenciou tanto o comportamento térmico quanto o espaçamento celular (λC), proporcionando maiores valores de ?E, porém, λC mais grosseiros.O intermetálico NiSn4 formou-se na região eutética de ambas as ligas, enquanto que na liga Sn-0,5%Ni, as fases primárias identificadas por EDS-MEV foram NiSn4 e Ni3Sn4. A transição morfológica celular/dendrítica(?E> 1,2ºC/s) ocorreu apenas para a liga eutética, enquanto que as células regulares da liga hipereutética deram origem as células do tipo placas(?E> 1,4ºC/s).

Oct 30, 2017

By Sergio Castro

Los modelos geotécnicos disponibles suelen estar basados en las litologías existentes, sin considerar el impacto de las soluciones hidrotermales en las rocas y, por tanto, en la estabilidad de los taludes de un tajo abierto. El estudio de caso presentado en este artículo muestra que realizar una zonificación en términos de los tipos de alteración hidrotermal es muchas veces necesario; pero también que ello debe acompañarse de investigaciones geotécnicas adicionales y un análisis de la estabilidad física de taludes, con el fin de lograr un rediseño basado en la variabilidad de la resistencia de la roca en cada tipo de alteración, ya que el efecto puede haber sido tan intenso que la roca termina transformándose en un suelo residual.

Jun 30, 2020

By Pedro P. Olórtegui F.

El objetivo del texto es señalar la importancia de las relaciones públicas -en tanto grupo que responde a un interés común- con la industria minera. Las relaciones públicas se dividen en dos campos: relaciones públicas internas y externas. Las primeras, tienen por objetivo mejorar las condiciones del personal y su habilidad en el trabajo a través del gestionamiento de los asistentes sociales, quienes regularán un programa de vivienda, educación y asistencia social que fortalecerá los lazos comunicativos y culturales con el trabajador y la empresa. Los segundos, regulan la relación de la empresa con la comunidad y otras empresas a nivel nacional, asi como con los representantes locales y regionales de la prensa.

Aug 20, 1965

By Rodney J. Ishak

The reduction of Mn3O4 to MnO has been investigated in a thermobalance apparatus. The charge was composed of manganese ore (decomposed by heating/calcination or pre-reduction to mainly Mn304) and coke. The material was charged to a crucible, which was suspended in the balance. CO-gas was distributed through a grid in the bottom of the crucible. Two sizes of ores were used; 2.4-4.8 mm and 6.7-9.5 mm. Coke particles were in the size range 4.8-6.7 mm. Experiments were conducted in the 900-1100°C temperature range. The composition of the product gas was monitored continuously. External mass transport between bulk gas and particle surface does not seem to limit the rate of reduction. Assuming that both diffusion through product layer and chemical reaction at the interface between MnO and Mn304 are rate controlling, the data was tried both in a shrinking core model and in a grain model using regression. The grain model gives the best physical description of the process, because the reactant is in fact a porous medium. With this model the effective diffusivity was calculated to be in the 1.5-6.10-5 m2/s range. The pore size was mainly between 0.1 and 10 um.

Jan 1, 2003