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By J. A. McLennan

Geological uncertainty is an unavoidable characteristic of all mining projects since only limited information is available from sampling. Mine planning and development decisions with significant economic consequences are made when the geological heterogeneity is inherently uncertain. Geostatistical simulation is preferred over kriging because the methodology provides alternative property realizations that can be combined into a model of geological uncertainty. Geological uncertainty can be transferred into production uncertainty, which can help characterize the economic risk of the project. This paper presents a case study for the Pogo property, being prepared for development near Fairbanks, Alaska. The exact dimensions, grades and production predictions have been modified; however, the methodology is illustrative. The geostatistical methodology consists of (1) assembling the relevant drillhole data and establishing a suitable coordinate system, (2) calculating the target distribution, (3) creating a model of spatial correlation, (4) generating multiple realizations at a small scale and (5) linearly averaging all the realizations to the chosen selective mining unit (SMU) support size. The geostatistical model is then used to calculate production uncertainty.

May 1, 2004

By Ted J. Williams

Underhand cut and fill mining methods are used at the Lucky Friday, Stillwater, and Galena mines in the western US in an effort to safely mine in difficult ground conditions and as a primary mining method where access below the ore is limited. The method has evolved at each mine to meet the unique situations associated with their milling procedure and mine layout. Details of the operational aspects of the backfilling and mining cycles at each mine are presented in this paper, accompanied by a summary of the mechanical properties of the backfill and its in-situ geomechanical behavior.

May 1, 2007

By G. Clarkson, M. Hitch, R. Clarkson

"A novel reagent-free method of extracting gold from gravity middling concentrates in the Yukon placer fields is presented in this paper. This method exploits the malleability of gold by submitting concentrates to grinding in a rod mill. Brittle waste minerals are effectively reduced, whereas malleable gold particles are flattened and are then extracted by classification through sieves. Recoveries in the field using a laboratory-sized rod mill regularly exceeded 90%, whereas correlation laboratory tests indicated recovery to be most sensitive to the mill charge size. This method has broad potential, including application to the gravity circuits of large hard-rock processing circuits.RÉSUMÉ Cet article présente une nouvelle méthode sans agents réactifs d’extraction de l’or dans les concentrés gravimétriques mixtes que l’on trouve dans les districts placériens du Yukon. Cette méthode exploite la malléabilité de l’or en broyant des concentrés dans un broyeur à barres. Les déchets miniers cassants sont bien réduits, alors que les particules d’or malléables sont écrasées puis extraites par classification au travers de cribles. Si les récupérations sur le site à l’aide d’un broyeur à barres de laboratoire excèdent 90 %, les essais de concordance en laboratoire indiquent que la récupération est très sensible à la taille de la charge du broyeur. Cette méthode présente un grand potentiel, notamment une application possible aux circuits gravimétriques des grands circuits de traitement des roches dures.INTRODUCTIONExploiting the high density of gold to separate it from waste materials is the oldest known mineral processing technique. This basic technique is still widely used in gravity concentration circuits today; however, gravity processing invariably results in high-value middlings, especially in the Yukon placer gold fields. In addition to having a uniquely high density, gold is also the most malleable metal. This unique malleability can be exploited to extract gold from otherwise inaccessible gravity middlings.The Yukon placer gold industry has been continuously ongoing since the 1860s, and today produces approximately 60,000 oz t (1.87 million grams) of crude gold annually, most of which is from the Klondike region near Dawson City (Van Loon & Bond, 2014). It is important to note that Yukon placer miners do not use any chemical extraction methods; rather, gravity upgrading methods are the sole processing techniques used. Placer deposits are typically coarse, well liberated, and naturally gravity concentrated and recoverable, thus making more expensive chemical extraction unnecessary (Mitchell, Evans, & Styles, 1997). Furthermore, a strict permitting regime, environmental concerns, lack of expertise, and fear of repercussions from regulators prevent miners from attempting more advanced processing methods, such as flotation or cyanidation. Even simple chemical extractions like mercury amalgamation have not been implemented for decades, with one observer noting that, as many as 30 years ago, “the art of mercury for amalgamating appear[ed] to be dying [in the Yukon]” (Osler, 1983)."

Jan 1, 2017

By I. Dymov, W. Phillips

A process has been evaluated, on a continuous pilot plant scale, to treat refractory gold arsenopyrite/pyrite concentrates. The process consisted of biological leaching to partially oxidise sulphides, followed by pressure leaching for complete sulphide oxidation and arsenic precipitation, followed by liquor neutralisation and cyanidation of the autoclave residue for gold recovery. This paper provides a brief description of the treatment flowsheet and discusses some of the main parameters and results of the process. During integrated pilot plant campaigns, it was confirmed that acceptable sulphide oxidation and gold extraction of 96-98% could be achieved by a two-stage oxidation with BIOX® (4 days total retention time) followed by PDX (40 minutes retention time at 220°C). Only partial arsenic precipitation was achieved in the autoclave, followed by complete precipitation by neutralization under atmospheric conditions. The overall process could be significantly simplified, and capital and operating costs reduced, with a flowsheet modification allowing all of the BIOX® liquor to bypass the autoclave directly to the neutralization circuit.

Jan 1, 2004

By A. Rodriguez-Prado, P. Kuschk, R. L. Legge, W. C. Lennox

Using constructed wetlands to chemically reduce hexavalent chromium Cr(VI) to Cr(III) from industrial and mining wastewater has proven to be feasible and efficient. Applying first-order kinetics to describe the process is simple, but in some cases a more accurate model is required to reflect the process. This paper studies the feasibility of using non–first-order kinetics to describe the reduction process. Results indicate that half- and second-order kinetics adequately described Cr(VI) reduction in laboratory wetland mesocosms. The organic carbon content played a relevant role, whether it was built up by plant growth or spiked into the feed water.

Jan 1, 2014

By Lionel C. Piuze

Introduction and Early History The British Canadian Mine is one of four operating properties of Asbestos Corporation, Limited, and is located in the town of Black Lake, Que., five miles southwest of Thetford Mines. In the early days of as1bestos mining, this .property was owned by a few small companies who later became part of the Asbestos Corporation. First .to commence mining operations on the property was the Coleraine Mining Company who, in 1885, began selling part of their large holdings in the area to various asbestos mining interests. Of these, the earliest active companies were Manhattan United Asbestos, the Glasgow and Montreal Asbestos Company, and the Anglo-Canadian, the last named later becoming the Standard and Dominion Asbestos Companies. Extraction of fibre was limited to what is now known as crude asbestos and the methods were primitive. Drilling was done .by hand and the ore was lifted by derricks operated by band winches. These were later replaced by horse power, but it was not until 1887 that the first steam-operated boom derricks were introduced, at the Anglo-Canadian mine. The ore was hand cobbled and the asbestos roughly classified and bagged. The waste rock, which by today's standards contained a considerable percentage of marketable fibre, was dumped near the pit. The first attempt to separate the asbestos from the host rock by mechanical means was made in 1888 by the G1asgow and Montreal Asbestos Company, then known as the Scottish-Canadian Asbestos Company, whose mill, erected in that year, was the world's first asbestos mill. Though the equipment was crude, the principles employed were the same as those used today with much larger units. The next steps were the use of rock drills, the adoption of steam rail transportation for moving mill rock, and conversion to the more flexible cable-derrick hoisting.

Jan 1, 1950

By G. V. Sirianni, G. E. Viens, R. A. Campbell, G. N. Banks

A combination shaft-electric furnace for the smelting of ores and the melting of metallized feed is being developed at the Mines Branch. When iron oxide pellets are smelted in this unit, they are preheated and partially reduced in the shaft before being transferred to the electric furnace where smelting is completed. Also, limestone flux added with the pellets is-preheated and calcined in the shaft. It has been demonstrated that, in smelting iron oxide in this unit, the throughput of the 250-kva electric furnace can be approximately doubled and the amount of electrical energy required can be very significantly reduced when the shaft furnace is operated in conjunction with the electric furnace. These benefits are achieved mainly by utilizing the sensible heat and latent energy contained in the arc furnace off-gases.

Jan 1, 1971

By B. H. Kim

It is hypothesized that the standard approach adopted to characterize the ground and to determine the rock strength properties at depth are flawed and generally tend to underestimate the rock strength and possibly the stiffness, particularly when the rock mass is characterized as massive to moderately jointed or blocky to very blocky. It is therefore necessary to conclusively established that the hypothesis, that the rock strength in highly confined rocks is greater than generally anticipated, is actually valid and generally applicable, and then to develop new procedures to establish rock parameters that can be reliably used for the design of deep excavation.

May 1, 2009

By J. S. Edwards

The ISASMELT? process is recognized worldwide as a modem, flexible, environmentally-friendly and low capital cost smelting technology. Due to the inherent simplicity, and the advanced process control that has been developed, personnel become competent within weeks of being introduced to the ISASMELT? technology. This compares with the years required to become proficient with alternative technologies. Copper smelters in Australia, USA, India, China, Peru and Zambia have installed ISASMELT? technology under licence from Xstrata Technology. In the secondary copper business, plants in Belgium and Germany are processing copper and/or lead materials in ISASMELT? furnaces in a two stage process. In a single furnace smelting is followed by converting. Both plants have exceeded design capacities and are continuously improving their performance. The next evolutionary step for the technology is the implementation of the continuous copper converting process on a commercial scale. The present work describes the design status of the continuous converting process - ISACONVERT?.

Jan 1, 2007

By Andre Panteleyev, Charels S. Ney, John M. Anderson

"Sam Goosly prospect, 22 miles southeast of Houston, B.C., was discovered in 1967 through geochemical reconnaissance. Soil sampling interpreted with respect to an east-to-west ice movement led to drilling targets.Mineralization is in a window of rocks thought to be Hazelton Group surrounded by Tertiary volcanic rocks and intruded by two stocks separated by about one mile. A westerly quartz monzonite stock is dated 61.1 m.y. and an easterly gabbro-monzonite complex is dated 52.5 m.y. The Tertiary volcanics are trachyandesites shown by the B.C. Department of Mines and Petroleum Resources to be in part extrusive equivalents of the gabbro, and they overlie Hazelton rocks uncomformably. Copper-molybdenum mineralization is sparsely developed in the westerly stock. Silver-copper mineralization forms an elongate west-dipping slab between the stocks in Hazelton rocks, which are continuously pyritized. The gabbro stock is not mineralized, but some dikes related to it are slightly so. Tertiary rocks are pyritized, but are not known to carry copper-silver mineralization. Hazelton rocks are divided into a lower conglomerate, an intermediate pyroclastic unit and an upper mainly sedimentary unit. They form a west-facing homocline. Coppersilver mineralization resides in the pyroclastic unit, mainly in a massive dust tuff through which are lenticular units of lapilli tuff. Well-mineralized rock is typically a breccia of light fragments in a dark chlorite-sulphide matrix. Sulphides are pyrite, chakopyrite and locally pyrrhotite, with very minor tetrahedrite, s phalerite and other sulphosalts. Rock alteration is predominantly a pervasive pyrite-sericite type, with widespread tourmaline, scorzalite, gypsum, ankerite and traces of fluorite. The most evident control of the copper-silver mineralization is the gross parallelism, over a strike length of 1.5 miles, to Hazelton strata, particularly a massive dust .tuff unit. In detail, mineralization crosscuts bedding and there is no appreciable banding within sulphides . A strictly syngenetic origin is untenable, but some initial concentration in a volcanogenic environment with subsequent modification by thermal processes seems likely."

Jan 1, 1972

We report the studies of Proton-Exchange Membrane Fuel Cells (PEM FC) and hydrogen storage materials at McMaster University for the last 14 years. From the initial investigation of ionic conduction mechanism to the revelation of the origin of non-Arrhenius temperature dependence, as well as the synthesis and characterization of high temperature polymer electrolytes, both experimental and theoretical works have been compiled for the fuel cell membranes. In addition to the discovery of suppressed ionic conduction in Electrode-Membrane Assembly (EMA) and novel hydrocarbon PEMs based on micro-emulsion, the first evidence of hydrogen adsorption saturation by carbon nano-tubes was also achieved, which has been the bottleneck for the application of PEM FC. Prior to our study, a number of controversial publications have claimed the hydrogen capacity of these materials to be between 0.1 to 10.0 wt.%, and none demonstrated a plateau of adsorption with pressure that is consistent with monolayer saturation. Others suggested that the tube bundle structure is opened under high pressure to enable higher adsorption on newly uncovered surfaces, but received no confirmation. Using our home made high-pressure instrument with in-situ electrical probes, we found that a plateau is nearly achieved at about 300 atm in the room temperature isotherm, and that nanotube bundles actually compress with pressure instead of splitting, using in-situ electrical measurements.

Jan 1, 2005

By Zbigniew J. Hladysz

A Deep Underground Science and Engineering Laboratory (DUSEL) is being planned at the site of the former Homestake Gold Mine in Lead, South Dakota, under the sponsorship of the US National Science Foundation (NSF) in cooperation with the US Department of Energy (DOE). This national facility will host a variety of multidisciplinary science and engineering experiments including physics experiments that require shielding from cosmogenic radiation. Geotechnical mapping was performed in 2010 in large excavations of the Davis Campus at the 4850 Level of the former Homestake Mine. LIDAR mapping included laser scanning using a red light laser scanner and 288 Mpixels 360° still camera. The resulting vector map with the photographs digitally draped over the model, was used to create an accurate, virtual model of the excavations. For model verification, the laser scanning was accompanied by surveying and manual mapping of the geology and rock structure. The immediate use of the model was to perform structural analysis and interpretation of geology needed for the design of the DUSEL?s super large excavations. The second round of scanning, after the application of shotcrete to the excavations walls, will be used as a technical blueprint to assess the effectiveness of shotcrete application.

May 1, 2011

By I. H. Warren, Forward F. A

The reduction of aqueous slurries of uranyl carbonate at elevated temperature with compressed hydrogen m the presence of metal catalysts and certain organic promoters has been shown. to yield uranium dioxide. The reduction takes place in a sequence of steps. The purity and sintering properties of the dioxide make it of interest as a starting material for fuel element production. Simple control can be exercised over the surface area and oxygen/uranium ratio of the product during reduction. URANIUM dioxide for fueling atomic power reactors 1s conventionally produced as a powder by simultaneously decomposing and reducing ammonium diuranate with hydrogen in a furnace at high temperature. Fuel elements are then generally made from this powder by compacting and sintering ( 1). In order that elements approaching theoretical density may be obtained,

Jan 1, 1961

By W. D. Robson

THE prevention of silicosis by metallic aluminium has been reported by Denny, Robson, and Irwin in two papers. The first (1) was published in 1937; the second (2), in 1939. The results definitely established that silicosis was prevented in animals by the inhalation of small quantities of aluminium. The present communication records subsequent progress in this field of research. HARMLESSNESS OF ALUMINIUM Animal experiments having served their purpose, it became necessary to consider means to test the discovery on humans. A question for immediate consideration was: Is aluminium harmful to man when inhaled as a fine powder? While the animal experiments were reassuring, since they conclusively showed the powder to be innocuous when breathed by animals, it was, nevertheless, desirable to have additional reassurance with regard to its effect upon human beings. Through the courtesy of the Aluminum Company of America and especially the valued interest in this problem displayed by that Company's Director of Research, Dr. Francis C. Frary, a study was made of the records pertaining to the health of a group of 125 employees who had for many years been engaged in the manufacture of finely powdered, metallic aluminium for the paint and ink industries. The conditions were such that these employees had inhaled varying and oft-times very dense concentrations of this powder daily over periods ranging from 6 to 23 years, the average for the group being 12 years. X-ray pictures of their chests showed no abnormalities attributable to aluminium. Their general health seemed better than that of the 3,000 workers in other sections of the plant. In fact, the early films of three employees in this group of 125 showed shadows suggestive of minimal tuberculosis, which shadows were not discernible in films taken after considerable periods of exposure to aluminium powder. The harmlessness of aluminium was, by this study, reasonably well established at the outset, a finding subsequently verified by Ontario research on humans.

Jan 1, 1944

By P. D. S. St. Pierre

IN REGENT YEARS, blast furnace operators have found it necessary to improve their technology in order to handle increasingly low-grade feed and yet satisfy the demands for greater tonnages of metal. Studies have been made covering several aspects of the problem, and in this connection the slags produced in the iron-making process have been critically examined with a view to discovering the slag with the optimum properties for a given operation. A good slag should combine, as far as possible, the properties listed in Table I. Unfortunately, some of these desirable properties are incompatible. For example, the advantage of the small ?bulk of a low-flux slag is offset by its low desulphurization potential and high viscosity. Similarly, a very fluid slag increases refractory wear. It will be seen, then, that a balance must he struck between these conflicting requirements. In the .present paper only the melting relationships of blast furnace slag ?compositions will be considered in detail. In interpreting the data herein presented, the optimum property requirements listed in Table 1 must strictly be borne in mind. It should also be noted that the discussion presented here always relates to calcined fluxes, since this facilitates reference to the final slag composition. Thus, in making calculations pertaining to the ?burdening of the furnace, due allowance should ?be made for the fact that the fluxes are added as carbonates.

Jan 1, 1956

By A. Dubé

Introduction It is common experience that on re-heating a fully martensitic steel below the Ac, point, a softer and tougher structure is formed as the tempering temperature is raised. The mechanism of tempering of plain carbon and low-alloy steels has been the subject of many investigations. In a very comprehensive study, Cohen and associates have recently established three different tempering stages, the last of which reaches completion at about 700°F., with heating rates of 5°F. per minute. This latter stage has been established ta be the carbide-forming stage, so that the steel consists of a mixture of ferrite and carbide, which are the metastable equilibrium phases. Any subsequent changes which take place at higher temperatures below the Ac, point in the absence of graphitization or carbide lattice conversion normally consist of agglomeration of the carbide particles. This naturally results in the softening of the steel. However, in many cases the Ac, point, as determined by dilatometry, thermal analysis, etc., only gives a rough estimate of the temperature where the reaction, ferrite plus carbides to austenite, is initiated. This appears to be especially true in the case of alloy steels in which three phases can co-exist in certain temperature ranges. Bain has given data on the three-phase equilibrium in both manganese and nickel steels. In these steels, the formation of austenite at temperatures just above the AeIL apparently involves the diffusion of the alloying elements to the first pools of austenite, thereby making the process very sluggish. As a consequence, the critical Ac points determined by ordinary methods at normal rates of heating can be quite distant from the true equilibrium Ae temperatures.

Jan 1, 1946

By Hua-Zhong Yu

Gold is one of the most widely used substrate materials for self-assembly. Self-assembled monolayers (SAMs) prepared from alkanethiols and their derivatives on gold are the most reliable and well-studied systems to date, which have attracted much attention because of interest in two-dimensional molecular assemblies, and of their potential applications in molecular devices, sensors, and functionalized interfaces. Gold electrodes are also very important in microelectronics and electroanalytical chemistry. This work reports the characterization of a new type of gold substrates for self-assembly. The gold substrates are constructed from recordable compact disks (R-CDs) with simple and straightforward wet-chemical treatment, and can be made at desired sizes and shapes that satisfy different experimental needs. In particular, an easy, inexpensive, and reproducible method to prepare self-assembled monolayers (SAMs) on CD-R gold substrates after removing the protective polymer films with concentrated nitric acid was described.

Oct 1, 2003

The process of gold recovery by gravity concentration is incorporated in the metal recovery flowsheet at seven Newmont Mining Corporation owned mining operations in Australia, North America and Africa. In 2009 gold recovered by gravity processing was equivalent to nine percent of Newmont's total gold sales of 5.3 million ounces. This paper will discuss these applications in detail including a review of plant flowsheets and presentation of recent operating results. Operating performance will be discussed with reference to ore characterisation procedures, interpretation of results, design considerations and optimisation practices as they relate to the recovery of gold by gravity concentration.

Jan 1, 2011

By R. P. Nicholson

On September 3rd, 1947, the Acadia Coal Company put into operation a central coal preparation plant. This plant was designed to process all coals mined by this Company in the Pictou County coal field. The problem, briefly, was to make a three-way separation of the raw coal fed into the plant. It was desired to remove all stone, metal, and wood from the marketable coal and to produce a splint coal from the raw material which would be suitable for making power. This splint coal product is belted directly to the power plant which is adjacent to the wash plant. To attain this object it was therefore necessary, first, to wash the raw coal, removing all splint, stone, metal, and wood. The stone, metal, wood, and highest-ash splint had then to be removed by a second washing in order to obtain the lower-ash splint for use in the power plant. The plant is on the east side of the Allan colliery, in the town of Stellarton (see accompanying photograph). It is of steel frame construction with wood siding, covered on the exterior with corrugated galvanized iron. Considerable concrete had to be poured for the foundation piers as the plant site is largely 'fill' ground. This necessitated the construction of extremely heavy footings containing a large amount of reinforcing steel. In all, 884 cu. yds. of concrete were poured for the various pits, tanks, and foundations; its average test was about 3,500 lb. per square inch. At the time the plant was constructed, the steel shortage in Canada and the United States was acute and, in order to obtain steel for the structure which is four stories high- an unused part of the Allan bankhead was torn down. Enough steel was obtained from this demolition to fabricate the new plant.

Jan 1, 1948

By A. M. Cameron

THE HOISTING PLANT at the Stobie section of the FroodStobie mine is a two-shaft installation designed to handle a daily production of 18,000 tons of ore at depth. The two vertical shafts are within 100 feet of -each other, an arrangement made to provide the needed capacity and to give flexibility of operation (Figure 1). No. 7 shaft, used for handling men and supplies as well as for hoisting ore, has been sunk to the 3000 level and is served by a manhoist handling two cages and an orehoist with two 14-ton capacity Kimberley skips. No. 8 shaft, so far completed to a depth of 1,900 feet, handles only ore. The hoist is semiautomatic with push-button control and the skips are 15-ton capacity bottom-dump. The ore-loading pocket for first stage hoisting at both shafts is 120 feet below 1,600 lev-el and additional pockets are planned, as the shafts are deepened, at 800 foot intervals down to 4,000 feet.

Jan 1, 1956