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Effective gas management in coal mines, as well as proper ventilation design, is very important for maintaining the safety of underground coal miners. Advances in numerical modeling techniques have enabled evaluations of the coal mining environment using advanced grid designs and computed gas distributions through detailed mathematical models. These models help engineers to see the unseen areas of the mine through visualization of the data and ultimately help improve worker safety. This paper summarizes the modeling efforts conducted by NIOSH in the U.S. and CSIRO in Australia to address various gas management issues encountered in longwall mines. The modeling studies involved two of the most widely used grid-based techniques, namely computational fluid dynamics (CFD) and numerical reservoir modeling. This paper discusses the application of these techniques for gob inertization and gas control for spontaneous combustion, pre-mining degasification of coalbeds, gob gas venthole design and performance evaluation in longwalls, and gas management during development mining.

Jan 1, 2009

By Keith Pucalik

Understanding Vibrations fr om Blasting focuses on explaining blast vibrations and their effects on people and homes while keeping an eye on the importance of the use and significance of explosives in our daily lives. Unlike many predecessors, this film will help blasting pro f e s s i o nals explain blast vibrations and address many of the layman’s most fre q u e n t l y asked questions. The film can be used in pubic hearings, given to homeowners during preblast surveys, or played at educational seminars for professionals. The film can also be used after blasting has begun and residents have already experienced vibration events.

Jan 1, 2004

By T. J. Lynch

A new class of polymeric dispersants for industrial minerals has been synthesized and evaluated. Currently available dispersants give initial low viscosities at high mineral loadings, however slurry viscosities can rapidly double or triple on standing over the first several days. The new dispersants give low initial viscosities that are more stable and maintain a lower viscosity for at least one month. The new dispersants are made possible by controlling the polymer molecular weight distributions during their manufacture such that essentially all of the dispersant is adsorbed onto the mineral surface, preventing depletion flocculation.

Jan 1, 2012

Two structurally and mineralogically distinct sulphiderich veins cross-cutting the disseminated sulphides of the Nairne Pyrite Member appear to be products of local remobilization of sulphides under fracture-induced free energy gradients during regional metamorphism and tectonic deformation.The contrasting mineralogy of the two vein types may have arisen as a result of differences in the structural orientation of the veins and!or the relative ages of the veins.

Jan 1, 1969

By Bratt G. C

When zinc is electrowon from concentrates or residues of high manganese content, the zinc sulphate electrolyte may contain high levels of manganese. The manganese level is usually controlled by removal of manganese at the anode as the dioxide during the zinc electrodeposition stage.By increasing the temperature of an electrolyte containing 8 gll manganese from 35°C to 90°C, decreasing the acidity from 100 gll to 30 gll, reducing the current density from 432.A.m-2 t6 286 A.m-2 and using new lead anodes containing over 0·75 per cent silver, the current efficiency for manganese dioxide removal was .increased from less than 1 per cent to over 20 per cent.At the same time the current efficiency for zinc deposition was maintained above 90 per cent by additions of high molecular weight cationic polyacrylamides to the cell. By utilization of these conditions in a small number of cells, the manganese level in the circuit could be economically concrolled to any desired level.With these conditions the formation of the dioxide changes from an indirect route, via Mn04-, to a direct oxidation of Mn2+ to Mn02.The incorporation of impurities such as Pb, K, NH4, Cu, Ni, or Fe makes the deposit unsatisfactory for direct use in Zn - Mn02 dry cells. The deposit structure changes from cryptomelane at low temperature to y3-Mn02 at high temperature.

Jan 1, 1975

By Robert E. Johnson

1962 was the second year of recovery from the mild 1960-61 recession. The year-to-year gain in constant dollar gross national product, our most comprehensive measure of the country's economic performance, was 6.0 percent (from $447.7 billion in 1961 to $474.8 billion in 1962). The unemployment rate declined from 6.7 percent to 5.6 percent. Although it was a good year, there were still unused resources of labor and capital which implied that the economy was operating below its potential. The year-to-year change in the Federal Reserve Board (FRB) index of industrial production of 7.6 percent masked the fact that more than one-third of the growth took place within 196L The monthly index rose only 4.8 percent during 1962, from 114.3 in January to 117.8 in September. The fact that the economy as shown by the industrial index, rose rapidly in the first half of the year only to remain on a plateau of 119-120 during the second half, led some people to fear an imminent downward turn. This did not occur. Neither production nor consumption of mineral fuels advanced as fast as the total economy. But consumption showed more gain than production, 5 percent compared with somewhat less than 4 percent. Production of both crude oil and natural gas reached new highs while bituminous coal production was the highest in 5 years.

Jan 1, 1963

By V. N. Rampton, C. F. Gleeson

"Exploration results over three overburden drilling anomalies defined by the Ontario Geological Survey in 1981 in the Kirkland Lake area, Ontario are presented. The anomalies come from lowland areas where overburden is thickest. By mapping the bedrock and surficial geology, by prospecting, humus sampling and shallow till sampling over the surrounding upland surfaces, one can initially evaluate such overburden drill anomalies without costly reverse circulation drilling. The drilling should follow, if necessary, only after surficial base data has been obtained. Preliminary work on these three properties has defined the presence of at least two styles of gold mineralization. One occurs in silicified zones in intermediate volcanics closely associated with northwesterly trending faults and shear zones. The second occurs in quartz-carbonate alternation zones in volcanics intruded by quartz-feldspar porphyry dykes. IntroductionThe three examples presented in this paper present first-hand information on an approach to the follow up of several geochemical anomalies that were found by the Ontario Geological Survey when they carried out reverse circulation overburden drilling as part of the Kirkland Lake Initiative Program (KLIP) in 1980 (Routledge et al., 1981). The initial approach is relatively simple, systematic, and cost and technically effective. It readies the properties for further exploration, or conversely, it could downgrade the properties as viable gold targets."

Jan 1, 1987

Prominent among the ore minerals at Mt. Ellison, in the Brock's Creek district, Northern Territory, are a number of copper-bismuth sulphides wittichenite, aikinite, emplectite, in association with nativebismuth, chalcopyrite, bornite, chalcocite, sphalerite and linnaeite.Linnaeite and aikinite formed first and were followed by native bismuth. Wittichenite was later and substantially replaces earlier minerals. Replacement of aikinite by wittichenite has produced secondaryor reaction bismuth.INTRODUCTIONThe Brock's Creek district of the Northern Territory lies to the south east of Darwin and has been the locale of intermittent mining of small but rich deposits of diverse ore type. Gold, tin, and copper ores were recovered especially between 1890 and 1910 with minor exploitation up to the present time. Copper ores were of prior importance, the main production coming from supergene enriched deposits of chalcocite.The mines are situated in strongly folded Precambrian strata comprising slates, sandstones, volcanics and amphibolites with replaced haematitic rocks (Sullivan, 1953). The strata in the Brock's Creek area immediately north of the Darwin-Birdum railway line are domed around a roughly circular granitic mass some 5 miles in diameter. The Mount Ellison mine is located near the N.E. margin of the granite in metamorphosed basic country rock.Study of a series of polished sections from Mt. Ellison revealed the presence of linnaeite, chalcopyrite, bornite, aikinite, wittichenite, emplectite, bismuth, sphalerite, and chalcocite. With the exception of sphalerite and emplectite each of these minerals is prominently developed and intimately intergrown with the other constituents.

Jan 1, 1963

By I F. Bell, K P. Hammerschmid

Well planned and executed environmental management plans can reduce life-of-mine operating costs and the need to deal with major environmental issues at the time of mine closure. With proper planning during the exploration, feasibility and execution phases of a project, final closure costs can be reduced. The reduction of closure costs should be considered during exploration and initial feasibility studies and when process facilities, waste rock dumps and tailings impoundments are designed. During the mining of the resource, closure cost reduction will depend on effective and efficient environmental management plans for ongoing land clearance, segregation of mine waste materials, management of mine site water and workshop wastewaters, and the establishment of progressive rehabilitation strategies. These issues are the responsibility of planning, production, technical support and maintenance personnel at an operating site. The successful implementation of environmental plans will ensure that all impacts are reduced and that closure issues with major cost implications are addressed prior to closure of the mine.

Jan 1, 1995

By Klaus Tietz, Hamish Adam, John Selby, Ian Glazier, Brian Sinfield

"Room-temperature tunable diode laser (TDL) analyzers are gaining in acceptance for highly critical safety monitoring applications in a variety of industries. This paper describes the testing, evaluation and deployment of a laser-based hydrogen cyanide monitoring system at the Campbell Complex of Goldcorp’s Red Lake Gold Mines in Balmertown, Ontario, Canada.A trial, single channel installation was followed by a staged multi-channel installation. Unexpected technical issues with the multi-channel installation were addressed and resolved.INTRODUCTIONLaser-based gas detection has several advantages over existing gas detection techniques (Ballangrud, 1993; Silver, 1992; Bomse, 1995; Table 1). For practical purposes, lasers generate light at a single wavelength. Room temperature tunable diode lasers (TDL) emit light in the near infrared (NIR) part of the electro-magnetic spectrum. Many gases of interest, including HCN, NH3 and others, absorb energy in the near infrared (NIR). Each gas has a unique absorption signature, or spectrum, made up of a large number of individual “absorption lines”. A TDL can be tuned to select a single absorption line of a target gas, which does not overlap with absorption lines from any other gases. Therefore, laser gas sensing is selective and does not suffer from interference from other gases. The single-wavelength nature of laser light also means that laser gas analysers have a linear response over a wide dynamic range.Tunable Diode Lasers (TDL) generate only a few mW of power. However, all this power is concentrated at one wavelength, the wavelength where gas absorption occurs, resulting in high signal-to-noise ratios and short response times, typically of about 1 or 2 seconds (Ballangrud, 1993). This also means that long path lengths can be used, enabling accurate measurements of very low concentrations, even with weakly absorbing gases. Tunable Diode Lasers provide all the advantages of other semiconductor devices: they are small, solid-state devices, operate at room temperature, and have long-term reliability (over 15 years). Currently, they can be obtained for any wavelength throughout the NIR (700nm to 2000nm). Because many gases absorb in the NIR, the technique is widely applicable."

Jan 1, 2011

By Foster Fraas

The most important lithium resource in the United States is in the form of the feldspathoid mineral spodumene. This mineral has not been used to any important extent as a source of lithium salts or lithium metal, as other more easily decomposed minerals have b en available in sufficient quantity to supply the relatively small demand. The need for cheaper lithium salts for such promising new uses as air conditioning or dehumidification and of lithium feldspar for use in the glass and [ramic] trades has justified the recent work done by the Bureau of Mines on King available, through improved beneficiation and extractive processes, some of the lower grade but extensive spodumene deposits.

Jan 1, 1937

By Foster Fraas

The most important lithium resource in the United States is in the form of the feldspathoid mineral spodumene. This mineral has not been used to any important extent as a source of lithium salts or lithium metal, as other more easily decomposed minerals have been available in sufficient quantity to supply the relatively small demand. The need for cheaper lithium salts for such promising new uses as air conditioning or dehumidification and of lithium feldspar for use in the glass and [ramic] trades has justified the recent work done by the Bureau of Mines on [king] available, through improved beneficiation and extractive processes, some of the lower grade but extensive spodumene deposits.

Jan 1, 1937

By Christophe Bragard

The Los Angeles Metro Eastside Extension light rail project included a 1.5 mile underground segment, which consisted of twin 18'?10" ID tunnels, bored with two EPB-TBMs. One of the major project challenges after the completion of the bored tunnels was the excavation of six cross passages within alluvial geology below the water table and with low ground cover. Sequential excavation methods were employed and this paper details the design, ground treatment, support measures, and construction methods used to mine these cross passages beneath the congested urban streets of the City of Los Angeles.

Jan 1, 2008

By Tim O’Neil

The search for precious metals opened up the American West. And Nevada was right in the heart of this development. In the mid-19th century, prospectors seeking gold roamed the hills of Nevada and discovered the ComstockLode. The development of this huge silver and gold deposit began in1859 and was responsible for Nevada’s early entry to statehood. Mining was Nevada’s first industry. In more recent years, the Nevada mining industry has led the nation in gold, silver and barite production. Nevada also produces many other minerals. These include aggregates, clays, copper, diatomite, dolomite, gypsum, lime and limestone, lithium and magnesium compounds, perlite, salt and silica. Even today, Nevada’s mining industry continues to be a major economic force in the state. The mining industry has made more than $10 billion in capital investments in Nevada since 1985. And the value of Nevada’s mineral production last year was about $2.7 billion.

Jan 1, 2000

The study of gas emitted from face coal samples at the coal face is part of an investigation of instantaneous outbursts of coal and gas. Normally, seam gas essentially comprises methane of which the origin in the metamorphism of coal is undoubted. The origin of other gases sometimes occurring in high proportion in seam gas, particularly carbon dioxide, is more controversial. A simple meter for rapidly assessing gas in coal was developed. Tests with the meter enabled comparisons of seam gas in face coal at some outbursting and nonoutbursting mines, and under various working conditions. The varying results of widespread testing suggest certain trends, including some prospect of recognising outbursting potential at the coal face.INTRODUCTIONThe aim of this work is identification of differences in gas condition between coals subject to instantaneous outbursts and coals which have not outburst, and between faces of coals which will and which will not subsequently outburst. Any comparative test should be conducted right at the coal face on coal about to be worked and the results of testing should be available after a short period. Moreover, the method and the comparison of results should require no special skill, and be well within the capacity of junior mine officials. Any consistent relation between gas condition and subsequent mining conditions - outbursting or not might be valuable in prediction of outbursts.INSTANTANEOUS OUTBURSTSInstantaneous outbursts (Hargraves, 1958) , are largely unpredictable and unaccountable ejections of coal (up to 5,000 tons) and gas (up to 5,000,000 cu.ft.) from a standing coal face. Usually the gas is essentially methane (CH4 ) but may be essentially carbon dioxide (C02 ), or an intermediatemixture...

Jan 1, 1962

Analysis for pillar extraction potential (A-PEP) is an intelligent tool, which could be used as a preliminary output indicator when considering the secondary extraction of regional support pillars in the Witbank and Highveld coalfields of South Africa. The safe and economic extraction of underground coal pillars is of paramount significance and importance to the South African coalmining industry to ensure continuity of supply of this fossil fuel. Pillar extraction practices in South Africa have been responsible a significant proportion of safety and fatality statistics in relation to its relative output (less than 5 per cent of total South African coal production) and, as a result, research was undertaken in local pillar extraction operations and extended to similar operations in New South Wales, Australia to assess a way forward for pillar extraction in South Africa. It was found that, although little in the way of new technologies has emerged in this field in the recent past, significant contributions could be made in the field of risk analysis to obtain a generic design methodology for pillar extraction in South Africa. The resultant A-PEP tool to assess pillar extraction potential is based on certain physical, risk and economic factors, which combine to indicate operational success in terms of economic, health and safety attributes. At the time of A-PEP?s development there was alack of operating underground coal pillar extraction operations, which made it difficult to validate its applicability. Since then, however, A-PEP has been successfully tested and validated against two unique underground coal pillar operations, which is the discussion of this paper. One operation is situated in the Witbank coalfield and is extracting pillars, which are 20 years old and at a depth of 80 metres below surface, while the other operation is situated in the Highveld coalfield-which is extracting 6 month-old-pillars underneath a massive dolerite sill at a depth of 220 metres. A-PEP has shown that its predictive nature is consistent the workings at both operations, irrespective of their unique conditions, and as such it can be successfully used as a mine planning tool. The A-PEP mine planning tool thus represents a positive step toward an integrated approach to underground coal pillar extraction when considering legal and operational aspects, which could form the basis for legislative guidelines when considering the future of pillar extraction in South Africa.

Jan 1, 2005

By Ramdane Bahar

"Abstract The design foundations can be performed using Menard pressuremeter rules that require a limit pressure and a pressuremeter modulus. In recent years, another trend of interpretation of this test is appeared. It consists of identifying the rheological soil parameters using analytical or numerical methods and then used to evaluate the bearing capacity and settlement of soil foundations using numerical software. This paper deals with the bearing capacity and settlement predictions of bored piles using two approaches. The first one is the method called ""Pressident"" which is a numerical program developed to analyse pressuremeter tests taking into account the Duncan and Chang model. The second approach is the method developed by Bahar and Olivari based on the generalised elastoplastic Prager’s model with the Von Mises criterion which is suitable to describe the behaviour of saturated clays under undrained conditions. The pressuremeter data, collected on various research and consulting projects are used to explore the relationship between limit pressure and undrained shear strength obtained by the two methods. Numerical calculations, by FLAC2D software taking into account the rheological parameters derived from these two methods, are performed in order to predict the behaviour of a single bored pile subjected to an axial vertical load. The predictions are comparedto the measured data.IntroductionThe Menard Pressuremeter test has been used extensively to measure in situ soil properties and for the design deep foundations in Algeria. These tests are an useful and economical way for obtaining reliable in situ properties of soils and provide the measurement of in situ stress-strain response of soils. From this test, the design foundations can be performed using pressuremeter rules that require a limit pressure, pl, and a pressuremeter modulus, EM. These two parameters are derived from the pressuremeter curve or deduced from existing correlations with undrained cohesion and internal angle friction (Ménard, 1957; Amar and Jézéquel, 1972), and are used to evaluate the bearing capacity of soil foundations and the expected settlements. But, they can also help to identify usual soil parameters required by simple constitutive models for soils in numerical calculations."

Jan 1, 2014

By William Wilkinson, Vladisla Kecojevic

Current three-dimensional (3D) computer design technology leveraged into drill and blast planning and operations is changing the way engineers and operations approach drill and blast design. Additionally, Global Positioning Systems (GPS) technology that is now readily available to the civilian population is being implemented into the mining sector with a variety of new products specifically designed for drill and blast operations. The objective of this article is to discuss the steps involved with 3D Computer-Aided Design (CAD) of drilling and blasting, and the benefits such a design can provide in conjunction with GPS and drill monitoring systems.

Jan 1, 2004

By J. Maheu

Heap leaching is an old technique for the recovery of copper, but a fairly new technique for the recovery of gold.The paper outlines the equipment required for the establishment of heap leaching test facilities and the procedure required to insure meaningful results. Sampling methods, the metal balance, carbon adsorption and stripping and safety procedures are discussed in broad outline.

Jan 1, 1982

By K. M. Tompson, R. L. Armstrong, C. I. Godwin

"Tungsten skarn deposits on the Clea property in the Selwyn Mountains, Y. T., are related genetically to a quartz monzonite stock, about 500 metres in diameter at the surface. Lower Paleozoic sedimentary rocks are metamorphosed for a distance of 3 km from the stock. Tungsten-bearing skarn mineralization within the altered sedimentary rocks is of two types: sulphide-rich pods and calc-silicate beds. The most significant scheelite concentration is in calc-silicate beds near or adjacent to the quartz monzonite stock. Discordant K-Ar and Rb-Sr isotopic dates indicate that the stock is probably of early Late Cretaceous age, 94 Ma or slightly older, and that it cooled slowly. High initial 87Srl86Sr ratios and disequilibrium relationships between K-jeldspar phenocrysts and groundmass minerals in the porphyritic phase of the granitic rock , and between different granitic rock specimens, indicate contamination of crystallizing magma by old sialic continental crust which extends westward under the Selwyn Basin.This study is significant to regional tungsten exploration. Granitic rocks associated with tungsten deposits, in this part of the Canadian Cordillera at least, appear to have specific isotope characteristics that indicate they were generated at a specific time and in a particular way.IntroductionThe Clea tungsten skarn property (Fig. I) is owned by Canex Placer Limited, and lies in the Selwyn Mountains (Bostock, 1948) near the eastern margin of the Selwyn Basin (Wheeler and Gabrielse, 1972), Yukon Territory. The property covers a 20-square-mile area centered near latitude 62°47 ' north and longitude 129°52' west, and is accessible by helicopter. An airstrip and the terminus of a summer-use gravel road at MacMillan Pass, Yukon, are about 20 miles to the northnorthwest.This paper deals mainly with the geochronemetry of granitic rocks from a stock associated with tungsten mineralization on the Clea property. We show that these rocks have specific characteristics that not only define the genesis of this stock, but also have significance for regional tungsten exploration around plutons in the Canadian Cordillera."

Jan 1, 1980