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IN CIRCLES where mining men are wont to fraternize, a statement often heard is: "Yes, I spent six (or two, or ten, or thirty) years down at 'Chuqui.' " This means Chuquicamata, the site in Chile of what in all probability is the world's largest deposit of copper ore. One hears similar remarks regarding Braden and Andes, and, in fact, regarding a score of other big mines in South America, Africa, and elsewhere, but Chuqui seems to lead the others as the locale of engineers who have done a stint in foreign countries. One reason probably is that it is the Anaconda Company's premier foreign operation. Because of its unusual size and the diversity of its operations a great many men are needed. It is a sort of training school for young engineers; but, also, Anaconda has sent down a great many mature members of its big organization for special assignments like metallurgical research or plant construction. Chuquicamata is about 150 miles northeast of Antofagasta, at an elevation of 9,500 ft. It is in an almost rainless desert country where the wind (it is alleged by some) blows most of the time. However, the copper mining entrepreneurs have done their best to make up for what nature has neglected to do in creating a pleasant environment for the people who operate the mines. These include about 160 "foreigners" of whom 86 are from the United States, most of them accompanied by their families. There are 165 Chileans on the staff. Comforts, conveniences, and many luxuries are provided to offset in some measure the disagreeable features of the climate. Nevertheless, as I have implied, engineers at Chuqui generally jump at the chance to become "alumni" when opportunity offers. At the same time, they appear to take pride in their alma mater.

Jan 1, 1957

By R. Plassart, F. Laigle

"As a powerhouse, a transformer or a valve chamber, large underground caverns are a major element of hydropower plant. On the contrary to galleries and shafts which are linear and long underground structures, large caverns are designed with often complex geometries and large spans. Moreover, as these caverns are generally located on the foot of the hydraulic scheme, the high overburden is often responsible of a high stress state. Thanks to current experiences in France and around the world, the Hydro Engineering Centre (CIH) of EDF has defined great principles in the design of caverns leading to a more general methodology. The project of Tehri in India is an example of difficult ground, with in the same time a high overburden, a ductile material and an important schistosity. These physical realities are attempted to be approached in numerical modelling thanks to a constitutive law with softening behaviour and an oriented criterion integrated in the continuum model. As a result, a flexible support is advised, based on a high density bolt system and a thin lay of shotcrete. This methodology has been developed in the case of Gilboa in Israel, except the schistosity which has not been observed in situ. At last, the example of Gavet (France) illustrates a discontinuous case of numerical modelling for a good quality but fractured rock mass.PRINCIPES ET METHODES DE CONCEPTION DE GRANDES CAVERNESHYDROELECTRIQUES SOUTERRAINESRESUME Les grandes cavernes souterraines abritant les turbines, les transformateurs et certaines vannes sont des ouvrages majeurs dans les aménagements hydroélectriques. A la différence des galeries et des puits qui présentent de longs linéaires, les grandes cavernes sont des structures à la géométrie souvent complexe et avec des portées conséquentes. De plus, ces cavernes étant généralement situées en pied du circuit hydraulique, la grande couverture rocheuse peut se traduire par un état de contraintes important. Forte de ses expériences récentes en France et dans le monde, le Centre d’Ingénierie Hydraulique d’EDF a identifié de grands principes de conception des cavernes permettant l’élaboration d’une méthodologie plus générale. Le projet de Tehri en Inde est un exemple de terrain difficile, présentant à la fois une forte couverture, un matériau ductile et une schistosité marquée. Ces réalités physiques sont approchées au mieux grâce à la prise en compte dans les modélisations numériques d’une loi de comportement radoucissante avec un critère orienté intégré dans un modèle continu. Les résultats ont conduit à privilégier un soutènement souple basé sur un boulonnage systématique relativement dense associé à une fine couche de béton projeté. Cette méthodologie a ensuite été reprise pour le projet de Gilboa en Israël, exception faite de la schistosité puisque non observée sur site. L’exemple de Gavet (France) enfin permet d’illustrer un cas de modélisation numérique discontinue d’un massif rocheux de bonne qualité mais fracturé."

Jan 1, 2015

The investment worth of a mineral deposit can only be realistically evaluated in relation to specific engineering design criteria, which fully details the proposed method of exploitation. These criteria have not in general been taken into serious consideration when leaseholders have reported reserves in the past. In fact, many "reserve" figures quoted are probably more correctly classified as geological resources. The industry now recognises that it is necessary to take into consideration not only grade and mill recovery factors, but also likely mining and processing costs as well as the current market price for the commodity. Once having estimated those costs which are applicable to the resource under study, they can be deducted from the gross inherent worth of the orebody to result in an estimate of the potential net revenue. Through a process of interactive trial mine designs and evaluation, reserves can be quantified to provide an estimate of the available recoverable economic reserves given a set of assumed cost and operational parameters. It follows then, that the available economic reserve recoverable from a given resource will vary from time-to-time as cost and price factors vary in response to changing technology and economic factors. A methodology is described which may be used to derive economic recoverable reserves based on a computerised model of the geological resource data and appropriate economic and operational cost algorithms. Examples are provided from both coal and gold studies to illustrate the impact of economic criteria on the magnitude of the reserve figure reported for each project.

Jan 1, 1987

By R D. Fleming

A single-cylinder research engine was operated on pure hydrocarbons and simple (two-component) mixtures of pure hydrocarbons to study the effect of fuel composition on exhaust emissions from a spark-ignition engine. Used as fuels were three pure hydrocarbons that represented the primary hydrocarbon types present in commercial motor fuels: A paraffin (2,2,4-trimethylpentane), an olefin (2,4,4-trimethylpentene-2), and an aromatic (meta-xylene). The engine was operated at the same equivalence ratio for all of the fuels used in the experiment. Exhaust gas samples were collected and quantitatively analyzed for carbon monoxide, carbon dioxide, hydrogen, nitrogen oxides, aldehydes, and hydrocarbons. Exhaust hydrocarbons were separated and quantitatively measured with a chromatographic system employing a flame-ionization detector. Unknown hydrocarbons and oxygenated materials in the exhaust were identified with a Time-of-Flight mass spectrometer coupled to a chromatographic system. The results of the exhaust gas analyses showed that ethylbenzene, l-methyl-3-ethylbenzene, and l-methyl-3-vinylbenzene were more abundant in the exhausts from either 2,2,4-trimethylpentane--m-xylene or 2,4,4-trimethylpentene-2--m-xylene fuel mixtures than in exhaust produced from m-xylene. Also, the pure 2,4,4-trimethylpentene-2 fuel produced smaller amounts of C2 to C7 olefins in the exhaust than that produced by the pure 2,2,4-trimethylpentane fuel. The exhaust from pure m-xylene fuel contained aromatic hydrocarbons of higher molecular weight than the parent fuel. The amount of total hydrocarbon (moles of exhaust hydrocarbon per mole of fuel used) in the exhaust from the three pure fuels decreased in the following order: 2,2,4-trimethylpentane > 2,4,4-trimethylpentene-2 > m-xylene. The hydrocarbon mole-fractions of unreacted fuel in the exhausts produced from each of the pure fuels were 0.20 for 2,2,4-trimethylpentane, 0.13 for 2,4,4-trimethylpentene-2, and 0.66 for m-xylene.

Jan 1, 1970

By B Bonfils, P Lois Morales, C Evans

One of the main challenges for current and future mining and processing methodologies is to understand the characteristics of the rock so that its behaviour in one or more parts of the mining process chain can be predicted. Features such as rock texture, mineralogy or border complexity between minerals control how the rock behaves from the processing plant through to the final products, including tailings disposal and thus can affect the feasibility of the project from technical, economic and environmental impact perspectives. Understanding how the mineralogy and texture of rock affect its behaviour in mineral processing is a demanding area of research and is essential knowledge in predicting the processability of complex ores in different stages. This study aims to demonstrate that different types of relevant information can be extracted from a range of currently available analytical methods. However, this information can be used in a complementary way for building a more comprehensive rock characterisation at the microscale and better-predicting ore processing characteristics from the intact rock through to tailing disposal. CITATION: Lois Morales, P, Evans, C and Bonfils, B, 2018. Multisource rock characterisation at microscale for a better understanding of processing characteristics, in Proceedings Complex Orebodies Conference 2018, pp 44–48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By D. V. Fites

Criteria for deciding when rock should be ripped and what ripping equipment and techniques should be used in given situations are discussed in this article. The relation between ripper performance and seismic wave velocities in various types of rock is also discussed. The ripper is not a new tool. In fact, it dates back as far as the Roman Empire. The Roman's ripper-mounted on wheels and shaped something like a plow — was pulled by oxen and used to loosen the earth for the shovelers and basket carriers building the Appian Way. There are records of rippers being used in this country in railroad construction between 1860 and 1880. However, the ripper as we know it today did not appear until about 1930. Tractor-drawn models were in use in 1931 on the Hoover Dam project. At that time they weighed about 7500 lb and were pulled by tractors with about 75 flywheel hp and up to 30,000 Ib total weight. The chief shortcomings of trailed

Jan 1, 1969

By N. C. Dunham

"The Bureau of Mines exploratory work on the Bear Lodge, Wyo., fluorite property wider the strategic minerals Program was completed in November 1944. Exploration consisted of surface trenching, shaft sinking, and drifting at shallow depth. Doak C. Cox of the Federal Geological Survey visited the area during the latter part of 1944 and napped the Bear Lodge property.The Bear Lodge property is situated in the Black Hilts National Forest in eastern Crook County, Wyo., 6 miles north of the community of Sundance (fig. 1). Sundance is 29 miles northwest of Upton, Wyo., a station on the Chicago, Burlington, & Quincy Railroad and 43 miles southwest of a siding on the Chicago & Northwestern Railroad, 3 miles south of Belle Fourche, S. Dak. U. S. Highway 14 passes through Sundance in an east-west direction. Sundance may be reached from the south over U. S. Highway 85 and Wyoming State Highway 585.The Bear Lodge property i a situated in the Boer Lodge Mountains in secs. 15, 22, and 23, T. 52 N., R. 63W., 6th P.M.The topography in the vicinity of the fluorite deposits consists essentially of rounded hills which slope gently to the valley floors. Near the north end of the Property the terrain steepens locally, and the canyon walls are Precipitous along the courses of several streams. There is an adequate supply of water and native timber for mining purposes. The average elevation near the deposits is 5,700 feet.The climate of the region is relatively moderate. The summers are usually warm, with frequent rainstorms. Temperatures often fall below zero during the winter months. Snowfalls are moderate to heavy.Fluorite occurrences in the Bear Lodge area have been known since 1914; however, fluorite was not discovered on the Bear Lodge property until 1943, when prospectors working on a nearby manganese deposit found fluorite mineralization in the limestone. No production has been recorded from the property."

Apr 1, 1946

By Graham Crutchfield

THE W. I. Cook pool in Shackelford County, Texas, has been the subject of a number of papers and articles. Its unique position both as to operation and development has made it an ideal location for unit repressuring. The major portion of the pool is located on the W. I. Cook ranch and most of the oil leases are owned by Roeser & Pendleton, FIG. 1.-PRODUCING SAND CONTOURS, COOK POOL, JAN. 1, 1931. Inc. and the Continental Oil Co. and operated by Roeser & Pendleton, Inc. The Humble Oil & Refining Co. and Tom James operate producing leases which have a vital bearing on the unity of the pool. Both have cooperated in the repressuring project. Practically the entire royalty is .owned by Mrs. W. I. Cook and she has given the operators her entire cooperation in all phases of unit repressuring.

Jan 1, 1931

By W. M. Moon, Hugh G. Miller, C. -S. So

"Digital image processing and enhancement techniques have been applied to airborne gamma ray spectrometry data from Sudbury, Ontario. These results have been correlated and compared with the available geological maps to evaluate their usefulness for identifying lithological units. Digital processing allows the correlation of various data sets, and different combinations of images can be tested and viewed as a composite image. Composite images with pseudocolours provide an opportunity to analyze and correlate information that is not otherwise apparent in individual images. Principal component analysis has been applied to the gamma ray spectrometry data to evaluate their efficacy and relative information contents of the measured and computed data. The results of this study indicate that the combined radioelements image (obtained by combining the radioelement image and the ratio images) is effective for defining areas of relative concentration of a specific element in near surface materials. Furthermore, the composite radioelements image (produced by combining three separate radioelement images) and composite principal components image reflect large-scale lithological variations. IntroductionThe Sudbury area is a unique geological structure located in the southern Canadian Shield (Fig. 1). Because the area hosts economically significant nickel-copper deposits (Pye et al., 1984), it has been surveyed in great detail by geological and geophysical methods. In order to obtain meaningful geological infonnation about the Sudbury area, several studies have been carried out with the application of innovative mathematical techniques for geophysical modelling, and attempts have been made to integrate the multisensor geophysical data available for the area (e.g. Gupta et aI., 1984; Moon et al., 1988; Singh et al., 1993). The main objective of this paper is to apply digital image processing and enhancement techniques to airborne ganuna ray spectrometry data in order to determine their usefulness for regional geological mapping."

Jan 1, 1994

By Christiano Gianesi Bastos Andrade

Clays with high content of smectite are denominated bentonites, and are widely used in industry as, for example, agents for bleaching of vegetable oils, animals and minerals. For this use, the smectite clays are treated with inorganic acid of high concentration at temperatures under boiling point, which provide the bentonite´s bleaching power. In the present study, a sample of smectite from Cubati, Paraiba, Brazil, was submitted to treatment under moderate conditions (90°C, reaction times of 1, 6, 12, 18 and 24hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5 M, acid solution/clay ratio of 1g/10mL), aiming to reduce impurities, responsible for the color of the clay, without causing significant changes in their structure. Thus, clay can be used in the cosmetics industry and other products with high added value. The treated clay was characterized by scanning electron microscopy (SEM), stereomicroscopy, energy dispersive X-ray detector (EDS) and X-ray diffraction (XRD). It was observed a bleaching in samples with time of 12h to 18h. With the DRX was possible to monitor the peak intensity of the clay structure and the sample with 12 hours of treatment was not significantly altered its crystalline structure, maintaining the peak clay at d001. The most pronounced changes in the bleaching occurred within the first 12 hours of acid treatment.

Aug 8, 2018

By J. W. H. Clare

An equilibrium isotherm at 550°C is given for ternary alloys rich in aluminum containing 0 to 15 wt pct Cr and 0 to 20 wt pct Mn. Phases encountered are: aluminum solid solution; stable temary compound G; and MnAl8,. In addition, a limited number of alloys were annealed at 450°C to check for differences from the 550°C isotherm. These experiments limited the composition of the G phase at 550°C and further experiments established that the G Dhase is not stable above 590 ± 1 °C. RAYNOR and Little1 established several equilibrium isotherms using aluminum-rich alloys containing up to 5 pct of the elements chromium and manganese. These isotherms showed that, in addition to an a solid solution and the two binary intermediate compounds 8 and MnAl6, a stable ternary compound ex-isted in the system. This phase was called the G phase because of its ghostly appearance in micro-sections. Little, Raynor, and Hume-Rothery2 found a similar phase in binary aluminum-manganese alloys and, as a result of their experiments, concluded that the G phase was a metastable phase existing in the aluminum-manganese system. This phase was stabilized by the addition of chromium. The constitutional work of Raynor and Little,' although showing the existence of the G phase in the aluminum-chromium-manganese system, did not establish precisely the composition limits of the phase or the temperature above which the phase became unstable and disappeared from the system. The work described in this paper was undertaken to provide this information. An examination of the previous work' showed that an isotherm at 550°C would provide the required data regarding composition in the shortest possible time, as the (a + G) phase field narrows considerably at higher temperatures. The same work showed that the G phase ceased to exist between 580° and 595°C. A more precise estimate of the transformation temperature would therefore be obtained by annealing selected alloys at successively higher temperatures beginning at 580°C. EXPERIMENTAL PROCEDURE 1) Materials Used—The experimental alloys were prepared from four master alloys containing 15.00 w pct Cr, 15.28 wt pct Cr, 19.80 wt pct Mn, and 19.38 wt pct Mn which were made from super-purity aluminum, electrolytic chromium, and electrolytic manganese. The aluminum was of 99.996 pct purity, the principal impurities being copper, iron, and silicon. The chromium and manganese were 99.9 pct pure, the principal impurities being antimony, calcium, and magnesium. 2) Preparation of the Experimental Alloys—The alloys were prepared in 20-g quantities by melting together the requisite amounts of master alloy and aluminum in an alumina-lined crucible and, after thorough stirring with an alumina rod, cast into a cold copper mold to give ingots 1/4 in. in diam and 3 in. in length.

Jan 1, 1960

By Garrett R. Hyde, Aleksandar Stojsic

Introduction Economic pressures in the international marketplace have spurred advances in almost every facet of flotation. New developments have occurred in flotation chemicals, flotation machines, and in the application of automated process control technology to grinding and flotation. Many of these advances are the results of concerted efforts to apply the knowledge obtained from basic flotation research over the past 15 to 20 years, to develop industrial technology for the more efficient separation of sulfide minerals in real ores. Mining company executives and equipment manufacturers are being called on to make decisions for incorporating some of this technology into present operations. This discussion is limited to two developments now at the stage of being engineered into industrial scale operations. They are control of the electrochemical environment or redox potential of the slurry, and control of bubble size in column flotation. Potential economic impacts are noted. Froth flotation Froth flotation makes use of differences in the surface properties of finely ground minerals to obtain separation. If the mineral surface is water repellent, the mineral particle will stick at the air-water interface of a bubble and float. If a mineral surface is not naturally water repellent, a chemical collector is added to the slurry to make it so. The collector must adsorb on, and make water repellent only the mineral to be recovered, not the gangue minerals. To achieve this degree of selective adsorption, chemical modifiers may have to be added to the slurry. Modifiers include pH regulators, activators, and depressants. Electrochemical control One of the most significant developments in recent years in the area of mineral processing technology is the recognition that collector adsorption of sulfide minerals is an electrochemical process. Consequently, flotation of these minerals depends on the electrochemical or redox potential of the system. Many of the modifiers used to control various flotation processes are actually potential controlling reagents. For example, the role of well known depressants, such as cyanide, sodium hydrosulfide, and sulfur dioxide, is essentially to

Jan 7, 1987

By B Brattli

The dispersion pattern of heavy metals in soil and water is a consequence of complex geophysical and geochemical processes. Metal release from mining sites and subsequent migration occur primarily through acid mine drainage and erosion of waste and tailings dumps. Water plays a significant role in heavy metal mobilisation. Whilst it acts as a storage buffer for the pollutants, it is also the medium in which most of the reactions take place, and is undoubtedly the most significant transport vector in the pollution process. The intrinsic properties of the acidic drainage such as chemical composition, speciation of key mineral components, redox potential and pH are master variables controlling metal release, transport, deposition, reactivity and availability to biota. The mobility of heavy metals is strongly increased by acidification from acid mine drainage, and the discharge of these metals into the receiving waters results in numerous physical, chemical and biological responses in which the environment can affect the metal and vice versa. The result is an overwhelming number of association/dissociation, substitution, adsorption/desorption reactions, giving rise to a complex migration pattern. The attempt to understand and describe the dispersion pattern of heavy metals is complicated by the nature and level of interaction between the geochemical and hydrodynamic processes that generate and control the movement of the pollutants in the geosphere. Transport models which can be used to predict the behaviour of metal pollutants in a natural environment are still in the initial phases of development and their application to real life situations is limited. The Biochemical Cycle adds another dimension to the mobility of heavy metals. Metals form an important component of the food chain for man and plants. Biological uptake of metals from the bedrock and soil by organisms can result in migration paths very difficult to follow. Biodegradation or assimilation is just a tip of the iceberg.

Jan 1, 2003

The Agnew Mine No. 1 Ventilation Shaft is the largest diameter shaft blind drilled in a hard rock mining environment. The selection of this method of shaft development was based on achieving an accelerated mine development and exploration programme. Drilling the shaft from a pre-sink depth of 73m commenced on March 22, 1982 and the shaft was stopped due to rig structural problems at a depth of 750m, 280m from the designed depth, on February 12, 1983, 137 days behind schedule. While problems with rig mechanical availability, cutter life and lost drilling tools in the hole hindered progress and escalated costs, penetration rates above prediction were achieved and both the speed and safety aspects of the method were well demonstrated.

Jan 1, 1983

By Timothy J. Rohrbacher

This report presents a U.S. Bureau of Mines study that incorporates coal mining factors, coal recovery factors, and economic factors into the definition of an economically recoverable coal resource. The relationship between these factors to the Energy Information Administration's estimate of U.S. coal resources-the "Demonstrated Reserve Base"-is discussed. The Matewan 7-1/2 minute quadrangle in eastern Kentucky was selected as the initial study area. Results indicate that of the original 1,193 million tons of resource in the quadrangle, only 89 million tons (7.5%) are economically recoverable at a cost of $25 per ton or less. At the current production rate of 5.3 million tons per year, this represents only 16.8 years of remaining reserves.

Jan 1, 1993

By Ulrich Langosch

In the 1990s the German mining industry introduced a new generation of shield supports. The new design of support has a maximum load capacity of 10,000 kN, making these units as strong as the shields used in Australia and in the USA. DMT took more than 3,100 underground observations in order to verify the roof fall frequency by statistical analysis. The results of this work have led to practical recommendations for roof control and the required shield support system on longwall faces. The underground observations have been correlated to Rock Mass Classification, to stress calculations and to the angle between the direction of the fissures and the direction of longwall mining_ The analysis work yielded the following two sets of results: 1. There is a critical distance between the canopy tip and the coal face (Tip to Face TF,n,). The TF,n, is predictable and relates to: the thickness of the first roof layer and its uniaxial compressive strength. The face support should have a TF that is less than the TFcrtt in every underground longwall situation. Exceeding the TF crit call immediately result in a roof fall. 2. Using the obtained regression equation DMT is able to calculate the probability of the roof fall frequency (FF), which describes the roof fall sensitivity. When TFcr;, is exceeded the predicted roof fall FF relates to: the measured support resistance (MSR) of the shield support the calculated vertical stress (p?) the fissure-direction index (DI = angle between main fissure direction and direction of mining) and the distance by which TFcrit is exceeded (ATF). Armed with these results DMT is now able to predict the critical distance between the tip of the canopy and the coal face (TFcrit), as well as the roof fall frequency, for all shield designs. By applying the new calculation method it is now possible to compare alternative longwall layouts and different shield support types under pre-set geological conditions. Mining engineers on site are therefore in a position to make the necessary roof control preparations required to run the longwall operation to maximum efficiency. The results provide a useful basis for making practical recommendations and for selecting the most effective design of shield support. The paper uses practical examples to demonstrate the R&D results and present the various methods now available for calculation and prediction in longwall roof control.

Jan 1, 2003

By Richard Franchot

From an efficiency viewpoint, the greatest loss of energy to the blast furnace is in its failure to convert more than about a third of the coke carbon from carbon monoxide to carbon dioxide. This result has usually been ascribed to a necessity of a 2:1 excess of CO in order to reduce iron. It has, however, been proved that iron is completely reduced by equal volumes of carbon monoxide and carbon dioxide. Hence there is room for the hypothesis that vaporization, as cyanid, of accumulated alkalis is a serious primary factor limiting the ratio of ore to coke. Observed cyanid vapor concentrations and those measured by the variations of the nitrogen-oxygen ratio in the hearth gases form the basis for a quantitative explanation of the furnace action. As EVERYBODY knows, the blast furnace is a gas producer. As to the reason for this, people are not so well agreed. The significance of the fact is obvious, for the extent to which the fuel leaves the furnace as combustible gas measures poor economy in iron smelting; while good efficiency in this respect means poor gas. The furnace thus works at cross purposes. The present trend of the steel industry is toward. a primary use of the blast furnace as a gas producer with pig iron as a byproduct. Needless to say, this trend is away from improvement in iron making. The production of more and better iron in a given furnace consuming a given amount of coke would seem, at least, to involve a decrease in the relative proportion of the combustible gas. The possibility at the same time, however, of making more and better gas need not necessarily be excluded. (The more the furnace acts as gas producer, the bigger is the sulfur problem.) Whatever the object, it would seem desirable to have a, clear, comprehensive, mathematically exact estimate of why and how the blast furnace functions, to the large degree that it now does, as a gas producer. The literature does not give a definite answer to the question. That for which explanation is sought is the fact that only a minor part, usually not more than a third, of the coke carbon burned is oxidized to carbon dioxide; that the development in the furnace of the fuel energy is thus limited usually to little more than 50 per cent.; that it requires about twice as much fuel coke to make a ton of iron as is indicated by the rela-

Jan 7, 1925

By Malcolm J. McPherson

INTRODUCTION The use of computers to assist the mine ventilation engineer began to grow in the early 1950s when electrical analogue devices were developed for the analysis of mine airflow systems in Europe and the United States (l,2,3). The need for quantitative planning of airflows in mines had become pressing and analogue computers fulfilled a useful purpose for over a decade. From about 1964 onwards, digital computer programs for mine ventilation network analysis became available (4,5) and, superseding the analogues, spread rapidly throughout the major mining countries. The successful implementations of such programs resulted in further research being directed towards the development of simulation programs to model the quality as well as the quantity of air flowing through underground workings. It is no understatement that digital computers have revolutionised environmental planning techniques in modern mining industries. This paper discusses the complex interaction of natural and mining factors which governs environmental hazards in underground mines and further indicates some of the simulation techniques which have entered practical usage or are at an advanced stage of development. THE PROBLEM OF ANALYSING THE MINE ENVIRONMENT The traditional methods of approaching environmental problems underground were based largely on empirical or intuitive techniques. The reason for this lay in the intricate relationships which exist between the many variables that influence the mine environment - and which limit the use of purely analytical methods to the simplest of cases. In order to illustrate the need for simulation techniques, Table 1 shows the three most widespread mine environmental hazards

Jan 1, 1977

By E. R. Torak

Custom Coals, International has installed and is presently testing a 225 kg/hr. (500 lb/hr.) micronized-magnetite, fine-coal cleaning circuit at PETC's Process Research Facility (PRF). The cost-shared project was awarded as part of the Coal Preparation Program's High Efficiency Preparation Subprogram. The project includes design, construction and testing of a fully-integrated, bench-scale circuit, complete with feed coal classification to remove the minus 30 micron slimes, dense-medium cycloning of the 300 by 30 micron feed coal using three different size micronized-magnetite mediums, and medium recovery circuits using drain and rinse screens and various stages and types of magnetic separators. This paper describes the project circuit and goals, including a description of the current project status and the sources of coal and magnetite which are being tested.

Jan 1, 1996

By G. W. H. Norman

The surficial Archæan rocks of the southern gold belt of western Quebec are constricted near Kewagama lake by granite masses to the north and south. This divides the belt into natural eastern and western parts. This paper deals with the eastern part, extending from Malanie to Haig township. In this section the Keewatin-Timiskaming rocks have a length of about 70 miles and end abruptly against garnetiferous gneisses of the Grenville terrain. In the western half of the section where exploration has been under way since the early twenties, there are sixteen mines that are or have been in operation, and eleven prospective mines. In the eastern half where exploration has been carried on since the early thirties, six prospective gold mines are under development, one· of which, Louvicourt Goldfields, is at the initial production stage. Of the sixteen properties in the western half that are operating or have operated, all, except the Golden Manitou, which is a base metal mine, and the old Green Stabell from which there was a small production of copper, produce gold. Of the eleven prospective mines in the western half nine have gold. New Bidlamaque has gold and copper and one, East Sullivan, has copper-zinc ore. Since production began in 1927 gold, silver, zinc, copper, and lead having a total value of about $10,000,000 have been produced from the mines of the eastern section of the southern gold belt of western Quebec.

Jan 1, 1954