Search Documents

By A Vigar

Siliceous float sampled in the Wafi River by CRA Exploration in 1977 assayed 22 g/t Au and 89 g/t Ag. Follow up in 1979 led to the discovery of outcropping mineralisation now known as Zone A. Soil sampling in 1980 and 1982 outlined a 350 m by 400 m area of >1 g/t Au at Zone A and smaller areas at Zones B, C and D. Thirty-one diamond holes were drilled between 1983 and 1986. Elders Resources continued evaluation of Zone A under a farming agreement between 1988 and 1990. Mineralised diorite porphyry was discovered in 1990 by drilling conceptual targets 500 m to the NE of Zone A. Evaluation of this copper-gold porphyry became the main focus of exploration for the next five years and a substantial resource was outlined within a single, discrete body. A review of the paths to project development in late-1995 highlighted the need for increased resources via a second mineralised porphyry and/or an additional resource of Zone A size to make the project viable. It was concluded that the greatest immediate potential for increasing the resource inventory was at Zone A itself where the mineralisation was open in all directions. Detailed mapping and drill core logging lead to the geologic and structural models being revised in early-1996. The objectives of the 1996 drill program were to extend the Zone A resource, to test for continuity of mineralisation westwards to Zone B, to better define the controls on gold mineralisation and to delineate high-grade blocks amenable to selective mining by infill drilling and 3D orebody modelling. The last drill hole of 1996 intersected 30 m at 4.6 g/t Au from 273 m in WR147, deep in the western limit of Zone A. This intersection gave impetus to continue drill testing towards Zone B. In April 1997, hole WR154 was drilled 100 m to the west of WR147 and intersected 20 m at 8.5 g/t Au and 70 m at 11.0 g/t Au at similar depths near the diatreme contact. Drill hole WR155 was then drilled 100 m to the west of WR154 and intersected 86m at 5.7 g/t Au and WR159 drilled 100 m to the south of WR154 intersected 36 m at 9.2 and 50 m at 4.4 g/t Au. A significant zone of essentially blind, high-grade gold was discovered beneath the dipping flank of a poorly mineralised diatreme in what became known as the Link Zone. The long history of evaluation has been driven by the conviction of a dedicated team that a mineralised system of the size and complexity of Wafi with strongly anomalous gold in outcrops over the entire Mount Golpu area must contain economic mineralisation hidden within it. The keys which redefined the direction of exploration and lead to the discovery of the blind, high-grade gold Link Zone were, in our view, the critical review of the project status, detailed geological and structural studies to define clear exploration targets and the necessary funding and persistence to carry this through.

Jan 1, 1999

By Pedro Hugo Tumialán de la Cruz

La distribución espacial de los minerales como efecto a ciertas condiciones físicas y geológicas del terreno se conoce como zoneamiento. El conocimiento de este proceso permitirá la planificación de un programa de exploración para una futura explotación. En este sentido, el presente texto señala las formas geométricas de zonamiento encontradas en los yacimientos hidrotermales del Perú a través del empleo de diversos métodos geológicos como el método de distribución minerológica, isovalores de leyes, cocientes métalicos, así como el método de trazas en casos especiales.

Nov 20, 1978

By S. Peterson, E. C. Westman, P. L. Swanson

Coal bumps are brittle, violent failures associated with high stresses and competent host strata. To study bump mechanisms, conditions in the vicinity of a deep longwall mining face in bump-prone strata were monitored using three discrete systems. First, a microseismic monitoring network recorded mining-induced seismic events throughout the mine and surrounding strata. Second, pressure variations and distributions on the longwall shield legs across the face were recorded. Last, tomography surveys imaged seismic transmission properties ahead of the face. Results from the three systems were correlated in an effort to increase understanding of mining-induced stress redistribution and bump potential. An initial, one-week study showed that the correlation between averaged tomogram values and seismically active areas had a coefficient of correlation (R) of 0.89. Further results of these studies demonstrate that the tomography system is capable of imaging heavy shield-leg loading and bump-prone conditions prior to them disrupting the face operations.

The Canada Centre for Remote Sensing (CCRS) has developed an airborne sensor, the SWIR Full Spectrum Imager (SFSI) which detects in the short wave infrared range of the solar spectrum from 1220 to 2420 nm. In June of 1995, a demonstration flight was undertaken in the state of Nevada with the support of the companies listed above. The focus of the flight was to collect image data over well known mineral deposits with the objective of evaluating the applicability of this sensor to alteration mineral mapping. Some of the Nevada sites chosen include Cuprite and Goldfield, volcanic hosted acid sulfate systems; Yerington, a structurally complex porphyry copper deposit; and Virginia City, a quartz-sericite-pyrite vein system with advanced argillic pods. Ground spectral data was collected with the PIMA-II spectrometer. Solar reflectance calibration was done by Desert Research Institute personnel at Virginia City and Cuprite. This paper will discuss the configuration of the sensor and present image and ground data for Goldfield and Virginia City.

Jan 1, 1995

By Thomas J. Kuli, Tim Rape

When a fan or blower breaks down or becomes worn, customers have two choices. They can replace it or they can have it repaired. In the past, replacement was the preferred option, especially when the equipment was severely damaged or worn. Now, however, customers are discovering the benefits of repairing or rebuilding. Even when the cost of repair is more than 60 percent of the cost of a new fan, customers are choosing the repair option. The cost savings can range from 20 percent to 80 percent. In many cases, the quality of the repaired part or component will exceed the quality of the original. This is because repair engineers have an advantage over the original designers. They can see how the existing fan performed — or failed to perform — in a specific application.

Jan 1, 2005

By H. A. Dakin

"An introduction to the metallurgical requirements of the Flin Flon concentrator reveals the magnitude of ore blending which is required in its operation of three flotation circuits. The resulting variability in flotation heads which has in-creased the separations complexity justified the development of an on-line analysis system.This paper provides a summary of the development and operation of that system. Particular attention is devoted to the problems encountered and where possible their solutions; as the requirements of accurate information and minimum downtime of the sampling system and x-ray analyzer are considered essential. The addition of a recess central computer has provided information in a more easily understood form and as well has allowed the start of automatic reagent control.An indication of the on-line analysis system's value to the concentrators' operation is provided by an examination of the plant in metallurgical data and reagent costs in previous years.The metallurgical plants of Hudson Bay Mining and Smelting lie adjacent to the city of Flin Flon on the Manitoba-Saskatchewan boundary. Plant operations commenced in 1930 treating copper-zinc ore from the local mine. In recent years ore bodies near Flin Flon and in the Snow Lake area, about seventy-five miles east, have been brought into production.By the beginning of 1973 the number of producing mines had increased to nine; with all the ore being handled by the Flin Flon concentrator. Figure l, showing mine ore assays during 1973 indicates the variation in metal content possible."

Jan 1, 1974

By L A. Maslov

We have considered the following characteristics of the crust and upper mantle of the Pacific Belt: seismic wave velocity anomalies, mechanical stress and shear deformation rate fields, heat flow and the pattern of metallogenic provinces of the Belt. It has been noted that there exist certain .regularities in distribution of the above mentioned geophysical characteristics and metallogenic zones within the Belt, displayed by prevalence of the lithophile elements in the Asia-Australian part of the Belt, and of the chalcophile ones within the American part.

Jan 1, 1995

By João Batista Ferreira Neto

A escória de aciaria pode ser uma alternativa como mistura para o cimento portland, substituindo parcialmente a escória de alto-forno. Um processo pirometalúrgico tem sido desenvolvido para promover a modificação química da escória de aciaria LD. Os experimentos foram realizados através da refusão de 300 kg de escória de aciaria LD, seguido de sua modificação no estado líquido. Essas escórias foram resfriadas com o uso de esferas metálicas. Análises de fluorescência de raios–X (FRX) e microscopia eletrônica de varredura (MEV) das escórias revelaram uma relação entre composição química, condição de resfriamento e a formação de fases cristalina ou vítrea. As amostras de cimento foram obtidas através da mistura de 25% de escória modificada e 75% de cimento Portland, resultando em mais de 280 J/g de calor de hidratação acumulado em 72h, expansão abaixo de 0,1% em ensaio em autoclave e resistências à compressão acima de 42 MPa com 28 dias. O processo mostra potencial para ser aplicado no tratamento de escória de aciaria LD.

Aug 17, 2017

By Steve Kral

In a lagging economy where profits are tight, businesses cut costs. No revelation there. The mining industry, though, has always looked for ways to reduce production costs — no matter the state of the economy or commodity prices. The fact is, when planning a new mine or the expansion of an existing one, mining companies gamble that commodity prices will be reasonably high when a project comes onstream. It takes millions of dollars and several years to bring a mine into operation. And a lot can happen economically between the time management gives the go-ahead for a new project and its completion.

Jan 1, 2002

By Y. Shiraishi, Y. Sakurai

A new method, the gliding cylinder method, was proposed as a wide range viscometer for the measurements of molten salts, slags, and glasses. The method consists of two coaxial cylinders, cylindrical bob and a vessel containing a liquid sample. There is a narrow gap between bob and vessel. When the vessel moves against the bob, the generated force on the bob consists of three types of resistance: (1) Stokes’s resistance on the bob, (2) a capillary flow resistance though an annular gap between vessel and bob, and (3) lubricating resistance in a gap. The last two can be calculated on a theoretical basis but the first cannot be estimated by a simple calculation since a wall effect did not calculate easily. However, it can be assumed that the generated force depends on both the viscosity of a liquid and velocity of the vessel. Thus, the relation between viscosity and a force at desired velocity of the vessel was measured using several standard reference materials including glycerol aqueous solutions and standard reference oils. The results depended on the magnitude of the gap between the bob and the vessel. For the wider gap, it was shown that the viscosity is a linear function of a gradient of force with respect to a vessel velocity. In contrast, if the gap is small, the viscosity depends on the gradient (of force with respect to velocity). This implies that the non-linear phenomena would occur in Stokes resistance. Though detailed analysis is in a further investigation, a calibration method can be applied to determine the viscosity by this method, because good correlation was obtained among these quantities. Viscosity of molten salts, such as NaNO3and ZnCl2was measured by this method as high temperature demonstration. Keywords: viscometer, viscosity, sphere pull-up method, fused salts, molten slags, glass melts

Jan 1, 2004

By Yi Luo

In dealing with various subsidence cases, accurate predictions of mining induced subsidence are the basis for correct assessment of subsidence influences and subsequent mitigation efforts. There is a good demand for a reliable tool to perform the subsidence predictions and related tasks. A comprehensive and integrated subsidence prediction model, CISPM, developed by the senior authors in the later 1980?s and early 1990?s (Peng and Luo, 1992) is one of such tools. Built on solid mathematical models and calibrated by a large number of collected subsidence cases, CISPM provides a rich set of features needed in subsidence engineering and research works. Its reliability and usefulness have been proven by numerous field applications. This upgrade of CISPM will not only preserve its original features and reliability but also provide some new needed features and a more user-friendly working environment.

Jan 1, 2008

By Robert A. Cortese, Henry E. Perlee

Coal dust and float coal dust, produced during normal mining operations, in underground coal mines, are carried from the point of origin downstream by the ventilating air, where it deposits on the surfaces of the mine entry. In an explosion, this dust is lifted from the surfaces by the aerodynamic disturbances and, if of sufficient quantity, can continue to propagate the explosion. To prevent the surface coal dust from contributing, it must be inerted, typically by spreading pulverized limestone, i.e., rock dust, over the coal dust surface. To facilitate the dusting operation, the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory(PRL), developed an automated system that continuously monitors the accumulation of coal dust. This system could activate a rock-dusting machine that disperses rock dust into the ventilation air when dangerous deposits accumulate and deactivate the machine when sufficient inert has been deposited on top of the coal dust. The system consists of a microprocessor-controlled optical float dust deposition meter. This device measures the light intensity reflected from a deposited layer of dust. A standard cap lamp is used as a fixed-position light source. From the reflected light signal, the microprocessor determines the hazard level of the deposited layer and performs the appropriate action. Full-scale studies conducted in the Experimental Mine at PRL's Lake Lynn Laboratory, using alternating thin layers of rock dust and coal dust, successfully demonstrated the operation of the device. Based on the statistical data from these studies, a mathematical model was developed to predict long-term error in total rock dust content using this inerting procedure. Downwind dust dispersion was also examined to provide optimum placement of the dust sensors and to determine the need for better rock dust dispersion techniques.

Jan 5, 1998

By Grant R. J. Bearss

Due to environmental concerns in urban construction, many typically simple projects become very complex or feasibly impossible. The introduction of relatively new concepts has redefined "impossible", again simplifying these projects and making them "possible". Case Study One covers the use of Pressed-in Tubular Piles on portions of the Long Island Expressway in Queens, New York. Innovations in the design, material and installation method solved many typically inherent problems on projects of this type and resulted in cantilevered walls that supported a 35ft (10.668m) excavation. Design predictions and actual measured deflections of this wall were within millimeters. Case Study Two covers the use of Pressed-in Tubular Piles on portions of the Hodogaya Bypass in Yokohama, Japan. Innovations in equipment development allowed for a cantilevered retaining wall to be constructed without affecting the adjacent right-of-way, dramatic reduction of the overall construction duration and installation of tubular piles in soils with SPT N values greater than 160.

Jan 1, 2002

By Michael Horn

[An economic trading region made up of 22 eastern Washington, northern Idaho, and western Montana counties, with Spokane, Washington as the central place, was defined for this study. modeling system with the, 1985 county database was to create an Input/Output based model of the regional economy. The leading ice, with respect to income, employment, value of exports, and total industry output are shown for each county and the region. The value of total industry output from natural resource based industries is also shown for each county and the region. Interindustry transactions, final demand, and value added components for the region are shown in the Regional Gross Flows Table. The total gross output for the region is valued at $36.7 billion. Total industry output for the region is $18.1 billion. The region provides $5.4 billion in income to a work force of 286,000. Spokane County, Washington accounts for about 50 percent of the regional total industry output, income, and employment. Both Spokane County and then as a whole produce about 80 percent of the total industry output for final demand with remaining 20 percent going to intermediate inputs for further production. Spokane County exports about 43 percent of its total output while 35 of the regional output is exported. Exports account for more 50 percent of the total in 18 of the 22 counties within the region. About 9 percent of the total industry output from Spokane County and 19 of the total output from resource f: .t *III For counties Spokane a industry ? N from nafural resource based represents 18 percent ?.{1 to 71 s. ?-{ and averages 39 r. ?-11 of total county +' ' 7:. FS.-f.?) If t. Natural resource it us -t for more than 50 coutny 1 s ? sass in seven counties within region.]

Jan 1, 1992

By B B. Beamish, J Theiler

Current spontaneous combustion index parameters such as SHT, CPT/RIT and R70 self-heating rate all have deficiencies that need clarifying from a risk management perspective. In some instances they can produce a false negative evaluation and in others they can produce a false positive evaluation. These tests all use a relative rating scheme that does not provide any indication of the time it takes for a spontaneous combustion event to develop, nor do they consider the moderating influence of moisture present in the coal on self-heating rate in the low temperature oxidation region. This is viewed as a major deficiency since the true self-heating behaviour of broken coal is primarily a function of time that is governed by the interaction of the initial boundary conditions (initial ambient temperature and moisture state) with the reactivity of the coal (both intrinsic coal reactivity and accelerated self-heating from reactive pyrite if present). The current index tests are also not appropriate for assessment of coalmine immediate roof and floor rocks.CITATION:Beamish, B B and Theiler, J, 2017. Recognising the deficiencies of current spontaneous combustion propensity index parameters, in Proceedings Australian Mine Vent Conference 2017, pp 113–118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By C. K. Kocsis, S. Hardcastle

Mine ventilation, requires electricity to operate the fans and fossil fuel for heating. Typically, this accounts for approximately 40% of the overall underground energy consumption. This is considerable, and one of the major causes of this expense is that most mine ventilation systems are designed for the "worst-case-scenario" with respect to ventilation demand, which is commonly dictated by diesel equipment usage. Once designed, mines tend to operate their ventilation system at this peak level despite their exceeding day-to-day development and production needs due to lack of appropriate ventilation controls. In underground metal mines, TeleminingTM, which includes the tele-remote operation of mobile development and production equipment from surface, will change the mine design criteria including its support infrastructure such as the ventilation system. With the removal of machine operators to surface control rooms, conventional ventilation systems designed to dilute and remove pollutants can become redundant. Depending on the ultimate need for ventilation, its cost in automated mines with tele-remote equipment operated from surface will be lower than the cost of ventilation in conventional mines. These cost savings, which could be significant, would not only come from the ability to reduce the amount of ventilation in the mine, but also through the capacity to automate its distribution. This paper provides an indication of the new airflow requirements in stopes and dead-end developments for the tele-remote and automated mining processes based on climatic modelling. Furthermore, this paper makes a cost benefit analysis by comparing the ventilation system operating cost of a conventional underground metal mine based on the mobile diesel powered equipment design criteria with the newly redesigned ventilation system operating cost of an automated mine based on the "heat management" design criteria.

Jan 1, 2002

By John L. Schaller

The Bureau of Mines, U.S. Department of the Interior, has investigated the extraction of alumina from domestic kaolin clay by leaching with boiling 26 wt-pct hydrochloric acid. Acid leaching of crushed calcined kaolin feed yields slurries that are slow settling and difficult to filter because of the presence of fine particles generated in crushing, calcining, and leaching. Laboratory research showed that tumbling and moistening crushed raw kaolin on a pelletizing disk caused the fines to agglomerate on the surfaces of the larger particles, while the sharp edges and corners of the larger particles were rounded off. Minus 16-mesh crushed raw kaolin was misted on a 36-in-diam, 8-in-deep pelletizing disk at rates of 175 to 250 lb/hr, and was calcined in either a rotary or a fluidized-bed calciner; negligible degradation occurred. The physical properties of the misted calcined kaolin were evaluated in the leaching system of the clay-hydrochloric acid miniplant. Only minor attrition occurred during leaching, and the slurry was readily filtered on a continuous belt filter.

Jan 1, 1982

A study of drilling data at various stages of development of an orebody show that the semi-variogram, used for calculating the accuracy of block estimates can be ill-defined if too few data are available. The consequencesin this case are to have blocks supposedly more accurately known than is possible at the early drilling stage; such a result being potentially dangerous. However, as the amount of data increases the recalculated, semi-variograms approach the underlying semi-variogram of the deposit and the calculations made using them become more reliable and robust.

Jan 1, 1977

By R. N. Gow

The presence of enargite (Cu3AsS4) is problematic in gold processing because it is environmentally hazardous due to its arsenic content but also because it is double refractory causing both cyanide and oxygen consumption to increase. Selective leaching and treatment of the arsenic would prove advantageous prior to applying conventional gold leaching methods. The reactivity of enargite samples from Butte, Montana and Quiruvilca, Peru were spectroelectrochemically studied under alkaline conditions, pH range of 8-13, using Raman spectroscopy and cyclic voltammetry. Raman spectra of the surface were collected during and after voltammograms were potentially cycled in order to determine and compare surface species against theoretical EH-pH diagrams determined from mass-balanced thermodynamic calculations using StabCal software. Under slightly oxidizing conditions, covellite (CuS) peaks were found in a short matter of time, above ~100mV vs SHE for pH 9-13, suggesting arsenic leaching specifically occurred. At longer conditioning times, elemental sulfur was observed and tended to passivate the surface. The presence of sulfur suggests that copper was eventually leached. By operating above pH 12, under slightly reducing conditions near -300mV vs SHE, arsenic can be selectively leached as thioarsenate (AsS43-) or thiosulfate (AsO43-) without sulfur formation.

Feb 27, 2013

By Avery H. Reed

RECORD production of crude petroleum, lime, crushed marble, and talc highlighted the mineral industry of Alabama in 1963. Among the States, Alabama ranked second in the production of bauxite, third in the production of scrap mica and native asphalt, and fifth in iron ore. The mineral industry of Alabama was dominated by mining and processing coal and stone, the manufacture of cement, and the production of crude petroleum, which together comprised 86 percent of the total value of production, compared with 82 percent in 1962. The iron-ore industry continued to decline; in 1959 the value of iron ore produced was 12 percent of the total State production value; in 1960, 11 percent; in 1961, 10 percent; in 1962t 8 percent; and in 1963, 5 percent.

Jan 1, 1964