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By P. J. Routledge

THE purpose of this paper is to discuss the practical aspects of locating gravel deposits and of establishing efficient, portable concrete aggregate beneficiation plants for use on construction projects where limited amounts of high-quality gravel and sand are required. Certain projects are listed, in order to demonstrate the wide variety of problems encountered. Routledge Gravel Contractors Limited, North Vancouver, have supplied concrete aggregate for construction projects in British Colum-bia since 1957. In tl1at year, in sup-plying aggregate for a small project at a site on the northern coast of British Columbia, our quote was as follows: Concrete aggregate to specifications, f.o.b. scow, North Vancouver$ 1.75 per cu. yd. Scowing charges to site. $16.00 per cu. yd. At that time, our company realized that more attractive quotations could be submitted if local gravel was utilized where available. Port-able equipment was then acquired and a simple screening plant (Figures 1 and 1a) was at first used. This was later replaced by heavier, more versatile equipment. The use of suitable equipment, the keeping of cartage to a mini-

Jan 1, 1962

By M. Tanaka, T. Oishi, K. Koyama, S. Alam

"A novel hydrometallurgical process for copper recovery from waste printed circuit boards has been proposed, which consists of selective leaching of copper metal as Cu(I) by Cu(II) in ammoniacal alkaline solution, purification, and electrowinning. The distinct feature of this process is much lower power consumption during the electrowinning than that during the conventional one from acidic copper sulfate media, because the deposition of copper metal from Cu(I) at the cathode and the oxidation of Cu(I) to Cu(II) at the anode take place in the present method. In the laboratory-scale tests using waste printed circuit boards, high purity copper which contains 1.1ppm of impurities was obtained in a chloride system. INTRODUCTIONThe recovery of various metals from waste materials is an important issue in order to conserve the environment and metal resources. Copper is used for cables, electric appliances, etc., and is currently a very important material for industries and will continue to be in the future. Among the wastes that contain copper, one of the most complex recycling materials is electronic scrap like printed circuit boards (PCB), which generally contain 10-30% copper as well as plastics, fibreglass and other metals. There are two ways to recover copper, either pyrometallurgical or hydrometallurgical. Hydrometallurgical treatments generally have more flexibilities in the process scale and control. The separation processes tend to become complicated because of the poor selectivity during the leaching in the sulphuric and hydrochloric acid media. On the other hand, the use of ammonia as a complexing agent, gave a higher selectivity for copper leaching (Nigo, Majima, Hirato, Awakura, & Iwai, 1993; Majima, Nigo, Hirato, Awakura, & Iwai, 1993; Zhou, Shinme, & Anezaki, 1995; Koyama, Tanaka, & Lee, 2006) .In this study, recycling process containing leaching, copper deposition at a cathode and oxidation of copper(I) at an anode from ammoniacal alkaline solutions containing Cu(I) or Cu(II) is introduced. Furthermore, copper recovery from a waste printed circuit boards and impurity behaviour was examined in ammonia-ammonium sulfate (sulfate system) and ammonia-ammonium chloride (chloride system) systems."

Jan 1, 2012

By Dean Millar

Clean, green, cheap compressed air can be produced efficiently and renewably by modernization of a 19th century technology ?The hydraulic air compressor has no moving parts ?After commissioning, the Ragged Chutes HAC operated for 70 years, only being stopped twice for repairs to the intake heads ?Operates using hydropower from Montreal river ?Produced air for ~29 silver mines in Cobalt, 20 km distant

May 1, 2013

By A. Zorkovská, S. Castro, P. Baláž, Z. Bujnáková

Enargite (Cu3AsS4) belongs among refractory copper minerals with very low hydrometallurgical extractability of copper. An application of enargite leaching in acid solutions leads to simultaneous dissolution of copper and arsenic and the final leach solutions have to be treated for the separation of both elements. However, the alkaline leaching of enargite is selective. Arsenic passes into leach while produced copper sulphide represents the raw material suitable for pyrometallurgy. The hydrometallurgical processing of mineral can be influenced positively by mechanochemical route. We have shown that more than 80 % of arsenic can be extracted from enargite concentrate by atmospheric alkaline leaching at 95 °C when mechanical activation in an attritor is applied. The produced Cu2S can be further treated with elemental iron where mechanochemical intervention is applied in the second stage of enargite processing. The final product forms Cu/FeS nanocomposite from which copper nanoparticles can be easily separated. The illustrated concept of copper obtaining from copper sulphide is an example of so-called “dry” processing, as reactions in gas and liquid phases are excluded. This concept of environmentally friendly metallurgical processing can be classified as an impetus for novel technology to produce copper from enargite concentrates.

Jan 1, 2012

By R. D. Brown

"""A matter of serious concern to the mining industry in British Columbia""; this comment reflects the attitude of the Mining Association of British Columbia toward the proposed new B.C. Mineral Royalties Act. The proposed legislation, introduced by the provincial government in February and now being debated by the legislature, combines a basic 5% royalty on the selling price, less approved p1ocessing and transpo1•tation costs, of minerals produced in B.C. with an ""excess"" royalty of 50% of any price increases over a predetetmined base. Government estimates project annual revenues of $20 million from the new royalty structure. The accuracy of these figures has been contested by the mining industry. Based on current world prices for copper the industry estimates that the provincial revenues from this mineral alone may run as high as $140 million in 1974 and $150 million in 1975. The Mining Association has warned that the new royalties “threaten to become confiscatory""."

Jan 1, 1974

By L. C. Galloway, G. L. Tiley

"Mine hoist brakes must meet the following statutory performance criteria:- There should be two independent braking systems; at least one should act directly on the hoist drum.-If one brake fail s, the others should be able to retard and stop the hoist safely before the descending conveyance, carrying the rated load, reaches any obstruction.- When all brakes apply, decelerations should not be so violent that men travelling in the conveyance are injured.- The brakes shall not overheat and fade during an emergency stop.This paper discusses design principles and capacities of caliper and disc type brakes, when applied to double drum and friction hoists of equivalent capacity.IntroductionThis paper is about the brakes that are used on mine hoists; their functions, especially in emergencies, typical design, and how they are operated, controlled, tested, and adjusted.There are two basic types of mine hoists:1. Drum hoists, where the ropes are attached to, and coil on drums. The simplest system has only one drum. Most such hoists, however, have two drums, attached to a common shaft. Ropes are wound on each drum in opposite directions, so that when one conveyance is being raised, the other is lowered. The conveynaces may travel in vertical or inclined shafts. In the latter case, the hoist s are referred to as slope hoists.2. Friction hoist s, where the headropes are not attached to the wheel, but are in contact with it for an angle of lap of, typically, between 180 and 195 degree s. Forces are transmitted from the hoist wheel to the head ropes by friction.The lower ends of the conveyances are connected to balance ropes , approximately the same weight per foot as the headropes."

Jan 1, 1986

By W. L. Nelson

The orebodies at Copper Mounta1n lie along and within a few hundred feet of the contact of an intrusive stock of gabbro with a series of bedded volcanic rocks of the Nicola formation. These. orebodies are all entirely within the volcanic series but in many cases the centre line of the orebody at depth is directly under the gabbro contact at the surface, due to a slight overhang of the gabbro. The gabbro and volcanic rocks are cut by a number of faults and fault zones which did not materially affect early mining operations, but, as undeground openings increased in size, the faults became more important factors in determining mining methods and procedure. Caving methods were adopted to take advantage of ground weakness in fault zones, and the effect of ground subsidence which resulted from the division of the ground 1nto large, independent blocks by faulting had to be considered in planning the sequence of mining of certain ore blocks. The faults have been divided into two classes: the longitudinal system and the cross faults, or 'breaks' as they are termed locally. In addition to the two classes of faults, the zones of parallel ore fracture also control mining procedure, but to a lesser degree, in regard to caving or ground subsidence. A third structural feature which influences mining procedure is the mine dyke system. The longitudinal or main fault system roughly parallels the gab? bro contact and is made up of a number of branches and auxiliary fractures. The main fault itself is essentially vertical, but there are a number of branches and fractures on each side of it which, though parallel m strike, may dip as flat as 50 degrees toward or away from the main fault. The full width of the main fault system has not been determined, but it is known to extend beyond the zone of mine workings. A marked schistosity follows the main fault and both schistosity and chloritic alteration have been noticed along the secondary faults of this system. Several prominent orebodies lie along the main fault and its branches. The influence of the main fault system on mining is probably related more to subsidence than to actual cavi.ng, although it is effective in both.

Jan 1, 1950

By Andre L. Du Preez

Global mine hoisting regulations require safety fall arrest systems to be installed on vertical conveyance systems capable of safely decelerating and supporting a fully loaded conveyance in the event of a rope severance. Most current arresting systems are incapable of producing controlled safe deceleration rates. Although safety ?dogs? achieve marginally acceptable results on wooden guides, difficulties arise in achieving safe deceleration performance requirement where safety arrest systems operate on steel shaft guides. Previously, arresting systems capable of operating with steel guides have been incapable of producing controlled deceleration rates during the arresting of free-falling conveyances. Most are ?instanton? systems, whereby an occupant inside a conveyance being arrested would be subjected to unacceptably high deceleration forces. This paper briefly highlights the background to the selection process of Rio Tinto?s Technical Staff of a suitable Mine Conveyance Safety Fall Arrest System for #1 Shaft at Rio Tinto Oyu Tolgoi Mine, Mongolia. It also describes the Drop Test and Free Fall Test procedure and the results leading to the acceptance of the Horne Group Levelok® Emergency Braking Technology for the Oyu Tolgoi #1 Shaft in Mongolia. The paper highlights Rio Tinto?s primary objective for the selection of this advanced technology on their primary production shaft cage system as an emergency safety catch braking system combined as an advance hydraulic chairing system. It describes the design and operational parameters and the 'Fail to Safe' interfacing with current automated mine hoist systems.

Aug 1, 2013

By Vladislava A. Ignatkina, Fillip O. Milovich, Vladimir A. Bocharov

"Complex research of flotation concentrates of monomineral fractions of chalcopyrite, sphalerite, galena, pyrite, pyrrhotite included methods of adsorption of collectors, surface compounds by IR ATR, and surface films of flotoreagents by TEM. They revealed that the proportion of the parts of thionocarbamate (TC) and dithiophosphate had an effect on the adsorption rate of the components of minerals, on the presence of characteristic bands, and, what is an important, visualized surface film of organic flotation reagents on the particles of concentrates by TEM. The predominance of thionocarbamate in a composition selectively increases the adsorption rate constant of the components and recovery of chalcopyrite compared with sphalerite and galena. The highest flotation rate using TC is characteristic for chalcopyrite (0.62 min- 1) in case of individual use, and it's in combination with butyl xanthate (25% butyl xanthate or 3:1) 0.89 min-1 too. We studied the ternary blend - dithiophosphate: thionocarbamates: butyl xanthate. The increase of the proportion of butyl xanthate in combination reduces the contrast of the flotation rate among all sulfides.Practice flotation of refractory sulfide copper-zinc ores of the Urals (content sulfide iron - 75- 95%) confirmed that the use of a combination of selective collectors increases selective recovery of copper sulfide minerals up to 50% at the first fraction that is the conditioned copper concentrate. New selective sulfhydryl collectors resulted in high levels of recovery of copper into a concentrate - more than 90% - against 70-72% (butyl xanthate) from copper-pyrite ore. Low floatability of iron sulfides has been obtained by selective sulfhydryl collectors. Using weak selective sulfhydryl collectors can reduce pH into collective or selective flotation from pH 10-10.5 to pH = 7.2-7.5, which improves the quality of individual concentrates of nonferrous metals and their recovery. The same is true for polymetalic sulfide ore. The volume of gold recovery also increased."

Jan 1, 2016

By D. Sagara, V. G. Makhado

"A model based control strategy was implemented at Loulo Gold Mine in Mali, to stabilise the thickener underflow stream density. This stream acts as the feed to the leaching circuit. pH control of the leaching circuit was integrated with the model-based controller due to slow process dynamics that are not suited to PID control. The controller performance was quantified over a period of 6 months, and was compared to the performance before implementation. The model based controller reduced process variability for both thickener underflow density and pH considerably, and resulted in a reduction in flocculant and lime consumption of 9.32 and 6.55%, respectively. INTRODUCTION Reagent consumption in gold processing plants significantly contributes to the total operational costs. In a typical Carbon-in-pulp (CIP) circuit, the reagent consumption associated with leaching, adsorption, elution and regeneration contribute to approximately 15% of the total operational costs (Stange, 1999). At Loulo Gold Mine, the reagent consumption associated with leaching, adsorption, elution and regeneration contributes to 6% of the total operational costs. As such, a reduction in reagent consumption will present a significant opportunity for savings on operating expenditure. Variability in feed ore characteristics results in continuous changes in steady state operating regions, which presents process control challenges as a result of the long residence times in some of the process units associated with gold processing plants. Overdosing often occurs in the presence of process variability to ensure safe operation and to maintain recovery targets. As a means of reducing reagent consumption and accounting for significant changes in the feed to gold plants, some of the plants have resorted to improving their process control strategies around their circuits. This paper focuses on the implementation of a model predictive based controller at Loulo Gold Mine on their thickener and Carbon-in-leach (CIL) tank to: •,stabilise the thickener underflow density, and •,the CIL tank pH."

Jan 1, 2017

By R. D. Brown

The first step in achieving a rationalization of Canada's crazy patch-work quilt of mining taxes and policies was achieved with the release last November of a major federal-provincial report on the taxation of the Canadian mining industry. The Report, prepared by a group of federal and provincial civil servants, sets out a concise and informative discussion of the major taxation and incentive issues facing the mining industry, and puts forward major recommendations for more rational and moderate taxation policies. It will be considered by federal and provincial Finance and Resource Ministers for possible action by the respective governments. The Report was prepared in response to a directive from the federal and provincial First Ministers in February 1978 to review the federal and provincial taxation of the resource areas. Although the Report is more successful in identifying problems rather than concrete solutions, and reflects some continuing differences of opinion between the governments involved, it does represent an important first step in a comprehensive review of our resource tax policies. This article summarizes the Report, which is some sixty pages in length. Although a detailed discussion of it is beyond the scope of this article, the report itself is recommended reading for those concerned about the current state of the Canadian mining industry.

Jan 1, 1979

By John Jiang, Brian R. Hart, Stamen S. Dimov, Aparup Chattopadhyay, Barun K. Gorain

"This paper presents a systematic approach to metallurgy diagnostics using an integrated gold deportment methodology developed for complex refractory gold and copper-gold ore bodies. Quantification of gold deportment for these ore bodies is a challenging task due to reasons such as lower grades, high variability of visible and invisible gold content in different sulphides and iron oxide phases, significant presence of disseminated and composite carbonaceous matters along with associations of various copper sulphide phases. Some case studies are presented in this paper to demonstrate the value of a high confidence gold deportment methodology in developing insights for problem diagnostics and to identify opportunities for metallurgical improvements. A holistic approach involving different fields of expertise is critical for successful development and delivery of solutions for complex ore bodies.INTRODUCTION Studies were initiated on various complex ore deposits and also on samples representing various process streams. These complex copper-gold single refractory, double and triple refractory gold ores are mainly composed of silicates and/or carbonates with moderate amounts of clay and mica, along with minor amounts of sulphides and organic carbonaceous matter. Variable proportions of visible gold and “invisible gold” (sub-microscopic gold) were noted in different mineral phases for various ore types and process stream samples. Invisible gold commonly occurs as solid solution or as colloidal-sized particles in different sulphides and other phases for different refractory ores. The dominance of invisible gold and presence of highly preg-robbing along with finely disseminated carbonaceous matters adversely affects gold recovery in flotation and leach circuits for most of these double and triple refractory ores. This paper discusses applications of an integrated gold deportment technique developed for different types of gold and copper-gold ores, namely, complex copper-gold, double and triple refractory gold ores (Chattopadhyay & Gorain, 2014; Chattopadhyay et al., 2016). Various process streams from flotation and gold leaching circuits were investigated. Different concentrates and tailings samples from flotation circuits whereas feed and discharges from pressure oxidation (POX) and carbon-in-leach (CIL) residues were used from gold processing circuits."

Jan 1, 2017

By J. R. Giegerich

Purpose It is the purpose of this paper to describe the application of underground conveyor systems to the transportation of ore in the Sullivan mine of The Consolidated Mining and Smelting Company of "Canada, Limited, at Kimberley, British Columbia. General Applications Conveying has been recognized as a means of underground transportation for a great number of years but only during the past fifteen to twenty years has there been any extended application of the method to underground metal-mine operations. Coal miners became conveyor conscious before metal miners. Probably one reason for this is the fact that there are more flat coal seams than flat orebodies. A second reason is that coal is light and is a less abrasive material than most metallic ores. The vast improvements made in belt construction during the past few years, together with improvements in mechanical conveyor equipment, have gone a long way in making this form of transportation attractive to the metal miner. In new mines being opened today, or in major extensions to older mines, the possibilities of conveyor transportation should receive serious consideration. There may not be any widespread application of the belt conveyor as a replacement for the conventional hoisting and locomotive haulage. Where there is an application, tl1e saving in cost can be appreciable and many operating ad-vantages gained because of ease in operation.

Jan 1, 1951

By Philip W. Johnson, Charles D. Haynes

"Abstract - The coalbed methane industry has become a prominent source of domestic natural gas, with its technology having evolved over the past 30 years. Whereas most coalbed methane wells are able to produce without major interruption over their economic lives, wells operating in an underground mining area are subject to being mined-through. If mine-through occurs, the productivity of the well is at least compromised, and may even be terminated. The economic consequences of mine-through may be relatively simple if mineral ownership and extraction rights are common for the coal and coalbed methane. However, if ownership is not common and a superior coalbed methane lease exists, the coalbed methane ownership must be compensated for lost production caused by mine-through. This paper presents a relatively straightforward method to calculate the value of the lost production caused by the mine-through. It uses technology from mining and petroleum engineering, as well as simple economics and financial management techniques.Sommaire - L’industrie de la production de méthane houiller est aujourd’hui une source importante de gaz naturel domestique dont la technologie a considérablement évolué au cours des trente dernières années. Bien que la plupart des puits de méthane houiller peuvent être mis en production durant l’entièreté de leur vie utile sans interruption majeure, les puits implantés en périphérie de mines souterraines sont sujets à être recoupés par ces dernières. Un tel recoupement peut compromettre, ou même mettre fin à la production d'un tel puits. Les conséquences économiques du recoupement par une mine souterraine peuvent être relativement simples quand les droits miniers et les droits d’extraction sont détenus en commun pour le charbon et le méthane houiller. Si toutefois ces droits ne sont pas détenus en commun et qu’il y a eu octroi d’une concession de méthane houiller de qualité supérieure, les détenteurs du méthane houiller doivent être compensés pour la perte de production résultant du recoupement par une mine souterraine. Cet article présente une méthode relativement simple pour calculer la valeur des pertes de production suite au recoupement par une mine souterraine. Cette méthode fait appel aux technologies de l’industrie minière et pétrolière ainsi qu’à des techniques simples d’économie et de gestion financière."

Jan 1, 2006

By D. J. King

The development in recent years of a fluidized bed system for use as a counter-current solid ion exchange loading contactor for the purification and concentration of uranium from leach liquors has had a major impact on the design of uranium extraction plants. The main object of this paper is to describe many of the variations that can be applied to the design of uranium extraction plants arising from the use of a fluidized bed loading contactor with a view to providing a guide for the development of a flowsheet for a new uranium extraction plant. The paper has been devoted primarily to the consideration of conventional uranium extraction plants in which a ground ore is leached in mechanically or air agitated tanks. The effect of the use of a fluidized bed loading contactor on each of the plant sections from leach to uranium purification and concentration has been considered. In order to describe most effectively the impact of using a fluidized bed solid ion exchange loading contactor, its use has been compared with the performance that can be achieved with the most common alternative purification processes. The comparisons are made largely on a technical basis, but the effect on the capital and operating costs of the different uranium extraction flowsheets are described qualitatively. In making these comparisons, consideration is given to the effect on the size, number and materials of construction of equipment items and how the quantity and composition of the liquid effluents can be controlled to reduce the environmental problems arising from the disposal of these effluents. The paper also discusses some of the factors that should be taken into consideration in the design of a fluidized bed loading contactor and describes various designs of the elution section that can be used in conjunction with the loading contactor.

Jan 1, 1979

By X. G. Zhao, M. Cai, L. K. Ma, P. F. Li

"Crack initiation stress is one of the characteristic stress thresholds in the rock deformation process under compression. By analyzing AE responses of brittle rocks in uniaxial compression, a new method which is called cumulative AE hit (CAEH) method is proposed for determining the crack initiation stress. An advantage of the CAEH method is that the method removes the user's subjective judgment. To verify the CAEH method, uniaxial compression tests with AE measurement using 77 crystalline rock specimens were conducted. The test specimens cover eight rock classes with different mineral grain distributions. Crack initiation stresses of these specimens were determined by the proposed CAEH method and the LSR method, and the resulting mean crack initiation stresses determined using the two methods were comparable. In addition, taking one rock class with 20 specimens for example, the mean crack initiation stresses determined using the CAEH method and those from several established strain-based and AE-based methods were similar. Hence, the CAEH method can be used as an alternative method for crack initiation stress determination.INTRODUCTIONExperimental observations indicate that the failure process of brittle rocks is associated with crack initiation, crack propagation, crack damage and final strain localization (Brace et al., 1966; Bieniawski, 1967; Lockner, 1993; Wawersik & Fairhurst, 1970). Compression tests on cylindrical specimen are often used to characterize the crack development process. The crack initiation stress (sci), crack damage stress (scd), and peak stress (sc) represent important stress thresholds during the failure process of brittle rocks. Among the three characteristic stress magnitudes, sci is difficult to be determined objectively, directly from examining the stress–strain curves. Some researchers argued that sci obtained from laboratory compression tests is an important parameter for estimating the spalling failure observed in brittle rocks around underground excavations (Andersson et al., 2009; Diederichs, 2007; Martin, 1997). sci can also be used to estimate rock tensile strength and Hoek-Brown failure criterion parameter mi (Cai, 2010). Over the last 40 years, various strain-based methods have been proposed to determine the crack initiation stress in compression tests (Brace et al., 1966; Diederichs, 2007; Eberhardt et al., 1998; Lajtai, 1974; Martin & Chandler, 1994; Stacey, 1981). Nicksiar and Martin (2012) proposed a Lateral Strain Response (LSR) method for establishing sci for low-porosity rocks. Meanwhile, they also used different strain-based methods to evaluate sci of Äspö diorite, and the results showed that all strain-based methods gave acceptable crack initiation stress values. Subsequently, they utilized the LSR method to further investigate the crack initiation stresses in igneous, metamorphic, and sedimentary rocks in compression tests (Nicksiar & Martin, 2013). Compared with previously proposed strain-based methods, an advantage of the LSR method is that it removes the user judgment when interpreting sci. However, the use of the LSR method relies on accurate determination of scd and on having a polynomial fitting equation to find the maximum LSR value."

Jan 1, 2015

By Min-Yuan Cheng

Heavy rainfall and typhoon oftentimes cause the collapse of hillslopes across mountain roads. Disastrous consequences of slope collapses necessitate the approach for predicting their occurrences. In practice, slope collapse prediction can be formulated as a deterministic classification problem with two class labels, namely ?collapse? and ?non-collapse?. Nevertheless, due to the criticality and the uncertainty of the problem, evaluating the collapse susceptibility of an area is a challenging task. This study proposes a novel Artificial Intelligence (AI) approach, named as K-Nearest Neighbor Based Bayesian Classifier (KNNBC), to deal with slope collapse assessment. In the proposed model, Bayesian inference is used as a framework to achieve probabilistic prediction of slope collapse. Meanwhile, K-Nearest Neighbor (K-NN) is employed as a density estimation technique. Equipped with probabilistic outputs, the K-NNBC is able to yield predictions with different levels of confidence and diminish misclassified cases. Experimental results point out that the proposed model is very helpful for decision-makers in slope collapse assessment and disaster prevention planning.

Aug 1, 2013

By R. J. R. Schaller

NO. 3 winze, the sixth shaft to be sunk on the San Antonio property, is practically a duplicate of No. 3 shaft, which was the main shaft prior to the installation of the larger hoisting equipment in 1939. It is collared on the tenth, or 1,500-ft., level, and goes down vertically to the sixteenth, or 2,500-ft., level, with a loading pocket, spill pocket, and sump below this. It is 1,000 feet east of No. 3 shaft. All ore, men, and materials are handled through the latter. The winze location with reference to the rock formation is shown in Figure 1. (In plan, this section strikes N.30°E. and cuts most of the main orebodies of the mine normal to their strike.) It is collared eighty feet inside the footwall contact of the basalt and cuts through it before reaching the eleventh level. In this location there will be no ore tied up in shaft pillars, as the closest ore to the shaft is on the tenth level, and here it is eighty feet northeast of the collar. The winze headframe and hoist-room straddle the main haulage to the No. 3 shaft, on the tenth level (see Figure 2). At no time during the excavation for the headframe and hoist-room was the general routine work of this haulage held up.

Jan 1, 1941

By Peter Hood

Data on world-wide geophysical activity in mining exploration programs are collected annually by the Society of Exploration Geophysicists' Geo-physical Activity Committee as part of a continuing service to the industry. The data are obtained by sending out questionnaires to all organizations which are known to be carrying out mining geophysical work; the organizations canvassed include mining companies, contractors, government departments and universities. The questionnaire is divided into three sections; namely, ground methods, airborne methods and research. The data compiled from the questionnaires show that world-wide utilization of mining geophysical methods reached a new high in 1967 with total expenditures of (U .S.) $32,323,240. This was divided as follows: ground methods, $18,106,785; airborne methods, $10,-123,405; and research, $4,093,050. For the ground methods, most money was spent on the induced polarization technique ($5,681,780); electromagne-tic methods were second in reported expenditures ($2,010,900). The total reported geophysical line mileage flown was 1,275,072 line miles, with aeromagnetic surveying being the most popular airborne method. The total amount spent on aeromagnetic surveys was $5,832,564 for 895,420 line miles. This gives an average cost of (U.S.)$6.50 per line mile.

Jan 1, 1968

By K. J. Fair, G. Van Weert, J. E. Schneider

"IntroductionCyanidation is the principal process for extracting gold from ores . Many primary gold ores, however, are partially or totally refractory in the conventional cyanidation process.Considerable success has been achieved with new gold leaching techniques, such as intensive cyanidation, pressure cyanidation, carbon-in-leach cyanidation, etc. These techniques however, do not offer substantial gains in gold extraction from refractory pyrites.The more drastic pretreatment processes such as roasting, chemical oxidation, autoclave oxidation, and bacterial oxidation all utilize oxidation to break down the structures of pyrite and arsenopyrite. This generally renders the gold amenable to cyanidation.Comparative cost studies indicate that the oldest commercial pretreatment method, i.e. high temperature roasting, is currently the least expensive option if the sulphuric acid can be sold. It operates with air at atmospheric pressure and is characterized by fast reaction rates. For an alternative hydrometallurgical con centrate treatment method to be competitive, it too should operate with air at atmospheric pressure and with fast reaction rates. The NITROX process meets these conditions."

Jan 1, 1986