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By H. Dundar

The first application of High Pressure Grinding Rolls was in 1985 at a cement plant, for the purpose of capacity improvement. Then various circuit configurations were derived to achieve a reduction in overall specific energy consumption, by transferring more of the grinding required to the HPGR. In most circuit configurations, the recycle of fines is required for effective breakage between the rollers. By increasing the fines amount in the feed material to a specific level within the recycling load, a uniform material bed is created and a higher pressure gradient along the roller width is obtained, resulting in compact flakes, including more fines. The fines recycle results in enhancement of the interparticle breakage. This paper will discuss the effect of the feed size distribution on HPGR performance.

Jan 1, 2012

By A J. Kyle

After a brief description of the shaft and surface facilities, this paper describes the planning for the mining operation, the selection of equipment the general method of mining and the sequence of operation. All of the major items of equipment are described, including the components of the power system. The detailed planning is reviewed -from the shaft sinking to the three-shift mining operation. Excavation and equipment changes, as well as long-range planning, are al o di cussed. Introduction THE successful completion of the Yarbo No. 1 shaft of International Minerals & Chemical Corporation (Canada) Limited in July, 1962, added a new type of mine to Canada&apos;s many producing operations. IMC Esterhazy is a unique mining operation in Canada; in fact, it is unique to potash mining in general. Not only is thi&apos;3 a trackless operation utilizing shuttle cars and belt conveyors in its material handling systems, but it excavates all of the ore with continuous boring machine<:;.

Jan 1, 1964

By B. Yamamoto, D. Post, J. De Leon, A. Meike

"This paper describes the theory, design, building, and testing of the passive magnetic bearing stabilizing system which is the core of the passive magnetic bearing system. The stabilizing system is made up of two large magnetic disks opposing themselves with a stabilizing disk in the center which allows the system to self-locate in a null position without the need for external power sources or sensors. When outside forces act upon the stabilizer, the magnetic fields interact with the stabilizing plate to return the system to its null position. Collaboration between two industry leaders has allowed an actual prototype to be built and tested providing real data to prove out the theory.INTRODUCTIONMagnetic bearing/stabilizer systems have many advantages over conventional mechanical bearing systems. These include near-zero drag losses and no need for lubrication since the rotating elements make no mechanical contact with the stationary elements of the bearing system. However all magnetic bearing systems must contend with a constraint known as Earnshaw’s Theorem in the early 1800’s, this theorem asserts the impossibility of constructing a stable, non-contacting, electrostatic or magnetostatic levitation system using only fixed charges or fixed magnetic poles, such as those produced by permanent magnets. Because of the constraint imposed by Earnshaw’s Theorem virtually all present-day commercial magnetic bearing systems are of the “active” type. That is, they employ electromagnets that are powered by amplifiers the inputs to which come from sensors embedded in the bearing system. These sensors are a part of a feedback loop that operates to keep the levitated rotating parts of the bearing stable and centered. The resulting complexity means that active magnetic bearings are expensive, require periodic maintenance, and continuously consume electrical power to energize their amplifiers and their electromagnets.Passive magnetic bearings are, of course, also subject to the constraints imposed by Earnshaw’s Theorem but they solve this problem in a straightforward and simple way, with only “passive” elements that take advantage of a loophole implicit in the derivation of Earnshaw’s Theorem. This loophole is that Earnshaw’s Theorem as derived applies only to static systems, i.e. an assembly of stationary permanent magnets arranged so as to levitate an object containing other permanent magnets. The theorem can be overcome if dynamic effects are taken into account. In active magnetic bearings the “dynamic effects” involve the afore-mentioned sensors, amplifiers, and electromagnets."

Jan 1, 2012

By R A. Burwash

In the Yellowknife geologic province, 2,600-million-year-old granites are cut by three sets of diabase or gabbro dyke : (1) large dykes striking 70°E to E-W, (2) rare dykes striking N-S to 30°E and (3) an abundant swarm striking N 10°-300W. Preliminary potassium-argon dating has been carried out on whole-rock samples of the chilled margins and coarse centers of the dykes, and on mineral separates from the dykes and contact aureoles. Data from seventeen dated samples suggest that the dyke sets were intruded during three periods of basaltic magmatism -2,200, 1,500 and 1000 million years ago. The two earlier periods closely follow the time of emplacement of granites in the Yellowknife and Churchill geologic provinces. The latest diabase dykes occurring in the Yellowknife province are temporally related to a widespread basaltic magmatism, for which the term Keweenawan is not appropriate. D DRING the past ten years, methods of physical age determination have been widely applied to date the time of intrusion or metamorphism of Precambrian rock

Jan 1, 1963

By F. A. Charalambous

Brannerite is commonly referred to as a refractory uranium mineral as it is usually highly resistant to acid leaching. There is however widely varying literature data on brannerite leaching, with some studies reporting that brannerite leaching can be achieved under relatively mild conditions. The differences observed for brannerite leaching are most likely due to the high degree of variation in the composition and structure observed in natural brannerites. These aspects of brannerite chemistry however are not very well understood due to a lack of fundamental research. The aims of this study were to investigate and develop methods for synthesising brannerites of varying composition and to investigate the effects of composition on brannerite leaching in acidic conditions.

Aug 1, 2010

"INTRODUCTION Secondary mine ventilation has been hamstrung by the availability of fans that satisfy many competing operational factors. The sometimes legislated requirement of adequate volume to the working face, the minimisation of excavation required to fit the selected secondary fan and the power requirements of various operational phases has, in the past, not been satisfied with just one system. The new system being introduced overcomes all these competing requirements in one simple unit with an added bonus of being very durable without loss of performance when wear occurs on the impeller. Existing Operational Situation Several studies (e.g., CIPEC, 2005; LCG Energy Management Group, 2009) have found that between 42% and 49% of mining energy costs are associated with mine ventilation, depending on the type of mine and the equipment used. If we then look at the general breakdown of installed power of the secondary fan to primary vent fans, the ratio is around 2:1. Thus the total energy costs of the secondary ventilation represents about 25% of the overall mining energy costs. It is of interest to note that the cost of running a typical two stage axial vs the cost of purchasing and general maintenance cost of the same fan over a 10 year period, the breakdown will be conservatively in the order of 40:1.The currently available secondary ventilation axial fan have one duty curve at any given time. Generally this can be changed manually within the motor power parameters but requires a minor outage and removal of the fan to do the pitch adjustments. As the bag vent ducts grow longer, the supplied air reduces to a point where inadequate air is supplied to the working face. This is exacerbated by underground equipment putting additional resistance in the heading and further reducing the supplied air at the working face. This shortfall is normally corrected by the installation of an additional fan in the system to overcome losses in the bag system but comes at a cost of production as the heading needs to be shutdown to install the second fan. This also means that the heading is supplied with excessive air on the shorter runs with a wastage of fan power."

Jan 1, 2019

By Joachim von Scheele

An oxyfuel-based technology - OXYFINES - has been introduced for in-plant recycling. It provides fines, dust, sludge (without any drying-step) and other by-products arising in the steel and metal producing industries to be recycled directly back into existing processes or a separate unit on-site. Results from full-scale installation (20,000 tpy) for dust treatment, full-scale and pilot-scale trials with dry and wet materials in the steel and ferroalloy industries are presented. Processing rates at 3.5 t/h have been demonstrated. The product is agglomerates or lumpy pieces, the latter if the product has passed an all-liquid stage and thereafter been crushed. The technology does not only provide a solution to the problems connected to dust and sludge generated in metal production. It also turns these materials into a low-cost raw material useful for the production in question, thus replacing part of the raw material input in electric arc furnaces, blast furnaces, etc. Elements harmful to re-use of the processed dust or sludge, e.g., zinc and alkaline components in steel production, are removed as secondary dust, and material yield of main components for re-use is very high, about 98%. The paper reviews the concept, the results obtained and its status; its use for sludge recycling is emphasized.

Jan 1, 2004

By Michael Jerome Wallace

"This paper refers to the wet open circuit ball mil ls in operation at Sidbec-Normines'5 pelletizing plant at Port-Cartier, Quebec, which commenced operations in late November· 1977. Prior to detailing our experiences in the grinding area at Port-Cartier, a general description of the total Sidbec-Normines project is outlined.HI STORYSidbec-Normines was incorporated in 1976 to develop the Fire-Lake - Port-Cartier iron ore mining, concentrating and pelletizing project. The primary objective of Sidbec-Normines is to produce 6mi11 ion tons per year of oxide pellets, of which 3 mi 11 ion tons per year are of a low silica grade suitable for direct reduction purposes. The participants in the project are Sidbec, the Quebec Government steel producer, British Steel Corporation (lnt'l) and the Quebec Cartier Mining Company. Equity interest is held in the company by the participants in the proportions of 50.1%, 41.6:7% and 8.23%, respectively."

Jan 1, 1979

By J. Satur

In copper mineral processing, pyrite coexisting with copper sulfide minerals like chalcopyrite is separated by flotation as tailings and its oxidation in tailing dams causes the formation of acid mine drainage. This paper proposes carriermicroencapsulation (CME) as a new method for suppressing pyrite flotability, as well as its oxidation. In this method, an organic carrier combined with Ti is used to form a thin Ti02 layer on pyrite, which gives a hydrophilic property and acts as a protective coating against oxidation. To form the coating, a ground pyrite sample was treated with Ti-catechol complex solution under various conditions. Bubble pick-up experiments and flotation experiments showed that the treatment of pyrite with Ticatechol complex changed the hydrophobic nature of pyrite into hydrophilic even in the presence of xanthate as a flotation collector. Oxidation testing of the CME-treated pyrite by 0.02 kmol m-3 HN03 showed that Fe release was suppressed by the CME treatment with respect to the control. This is assumed to be due to the formation of Ti02 coating on the pyrite surface. The effect of CME treatment on chalcopyrite wettability is also discussed.

Jan 1, 2007

By Louise Grondin

Laronde Mine has been working for a number of years to identify substances that could contribute to process water toxicity and to find an effective way of removing these contaminants from the water. Initial studies have identified ammonia, nitrite, cyanide, thiocyanate, cyanate, dissolved organic carbon, copper and zinc as potential toxicants. Bench-scale tests were carried out with Lakefield Research to find a water treatment process that could effectively remove the suspected toxicants. Nine treatment processes were evaluated: 1) granular activated carbon (GAC) filtration followed by zeolite, 2) zeolite filtration followed by GAC filtration, 3) aeration followed by GAC filtration, 4) multi-stage GAC filtration, 5) chlorination followed by dechlorination, 6) addition of clay based polymer, 7) treatment with peroxide and ultra-violet light, 8) bulk addition of GAC and zeolite powder, 9) treatment with bacteria. This article presents a summary of the test results and of the problems associated with the evaluation of technologies for the treatment of toxicity.

Nov 1, 2002

By F. H. Hueston, R. S. Barclay

"Depending on the application, zirconia, fused magnesia and graphite have been found to be the most suitable crucible materials for melting uranium metal and its alloys. Although graphite has been found to be satisfactory for uranium and uranium alloy castings with cross sections of 4 square inches or greater, ceramic-type molds are superior for small sections and those shaped castings which prohibit the economic use of machined graphite molds. Heating cycles, addition mechanisms and furnace conditions for melting are discussed."

Jan 1, 1967

The uranium ore processed by the McClean Lake Operation is co-mineralized with niccolite, rammelsbergite and gersdorffite (nickel arsenides). During the strong acid leach process, the majority of the reduced arsenic is oxidized and liberated into the lixiviant solution as As+5. Following uranium extraction, the residual raffinate solution, enriched in As+5, reports to the tailings preparation process. In this process, Fe+3 is first added and mixed with raffinate (pH~1) to achieve a Fe+3/Astotal molar ratio of at least 3. This is followed by two stages of neutralization, using slaked lime to achieve a solution pH of 4, and approximately 7.5, respectively. Synchrotron based x-ray absorption techniques (XANES, EXAFS) applied to neutralized raffinate solids and tailings samples collected from the tailings management facility provide evidence that arsenic has been precipitated as a poorly crystalline form of the mineral scorodite (FeAsO4?2H2O).

Aug 1, 2010

Thermal barrier coating (TBC) systems provide thermal insulation to high temperature for aero¬propulsion. A fracture mechanical model developed earlier for multilayer systems is applied on TBC to realize superior performance by enhancement of fracture resistance. Functionally gradient materials (FGM) solution concept is the basis of approach followed here. A few realistic FGM TBCs are considered in the analysis in addition to a conventional TBC as the base case and a hypothetical worst case with YSZ-YSZ interface. Parameters like number, composition and thickness of graded layers and elastic modulus are considered for the analysis and quantitative improvement of fracture resistance of TBCs. The analysis is confined to deep crack with crack size to width ratio as 0.5.

Jan 1, 2010

Iron deposits of every major type except laterite occur in Quebec, and form one of the major iron ore resources of the world. The five principal types of ore described are: (1) hematite-goethite masses derived from iron formation through the oxidation and enrichment of iron by natural processes; (2) taconites consisting of fine-grained iron formation; (3) metataconites composed of coarse-grained iron formation; (4) iron and titanium oxide minerals in massive or disseminateed deposits within gabbro and anorthositic rocks; and (5) replacement or contact? metasomatic magnetite deposits associated with complex silicate and skarn mineral assemblages. Most of the ore, although relatively low grade, is easy to concentrate. The physical properties of the ores that affect the choice and efficiency of beneficiation methods are described. The extent to which iron ore from this area can be utilized in the future will depend on the continued use and improvement of highly efficient methods of beneficiation.

Jan 1, 1964

By André Desbiens, Frédéric Flament, Lionel Ryan

"In December 1991, the GRAHM (Groupe de Recherche sur Jes Applications de L'informatique a L'industrie Minerale), of Laval University started a KBAC (Knowledge Based Automatic Control) grinding project with Falconbridge Ltd. The project was shifted to the Kidd Creek concentrator in the summer of 1992, with the first phase involving the collection of data by GRAHM and Falconbridge personnel for the construction and tuning of a dynamic simulator. This grinding circuit dynamic simulator known as DYNAFRAG was used to assess various control strategies, with a PID-based strategy being selected for ease of installation on a Foxboro II A DCS.The ""B"" primary grinding circuit was chosen for the initial strategy development, which is one of three parallel divisions. The KBAC project was successfully completed in November 1994, with subsequent modifications being implemented by Kidd Creek staff.This paper summarizes, the current control strategy, the project costs, and the realized benefits. Some of the problems which were encountered with the initial installation, and the subsequent modifications are also dealt with in this paper.2.0 IntroductionIn the summer of 1992, the GRAHM of Laval University and Falconbridge Ltd. started a project to design a control strategy for the ""B"" grinding circuit at the Kidd Creek Division. Between 1992 and 1994 several papers have been written to describe the control objectives, the methodology followed, and some initial results (Flament, 1994A, 1994B). Since then, however, the control objectives changed, and several improvements were made to the circuit. In particular, maximizing tonnage was no longer a priority, a variable speed drive pump was installed on the cyclone feed, the ball mill power was lowered, and the geometry of the cyclones changed. As a consequence, the control strategy was revised. Table 1 summarizes the historical developments on the ""B"" division grinding control."

Jan 1, 1996

By G. R. Guillet

Salt is restricted to five major beds in south western Ontario, totalling as much as 200 m in thickness. These beds are located at depths ranging from 270 m to 750 m below the surface, fringing Lake Huron and the Detroit River from Windsor to Kincardine, and extending inland as far as London. Manitoulin Island, the Bruce Peninsula and the north part of the Niagara Escarpment form the northeastern rim of the Michigan Basin, a major structural depression in which the salt was deposited 400 million years ago when much of North America was covered by the Silurian sea. Salt is mined underground at Windsor and Goderich; it is also brought to surface as brine through deep wells at Windsor, Samia and Goderich. Artificially- created caverns in salt beds are extensively used for storage of liquid hydrocarbons at Windsor and Samia.

Jan 1, 1984

The morphology of environmentally assisted cracks in stressed pipeline steel has been investigated, For a dilute and neutral solution (NS4) simulating ground water in contact with the steel, semi-elliptical cracks grow faster on the surface (2c) than in the depth (a), hence, the aspect ratio (a/c) decreases, This is explained using a deterministic concept since corrosion is dominant and the primary constraint is the conservation of charge, By contrast, when mechanistic conditions prevail, significant growth occurs in the depth, When underloads are imposed in the loading history, temporary accelerations in crack growth occur because corrosion rather than mechanical effects become dominant.

Jan 1, 2005

By A. Plumtree

The morphology of environmentally assisted cracks in stressed pipeline steel has been investigated. For a dilute and neutral solution (NS4) simulating ground water in contact with the steel, semi-elliptical cracks grow faster on the surface (2c) than in the depth (a), hence, the aspect ratio (a/c) decreases. This is explained using a deterministic concept since corrosion is dominant and the primary constraint is the conservation of charge. By contrast, when mechanistic conditions prevail, significant growth occurs in the depth. When underloads are imposed in the loading history, temporary accelerations in crack growth occur because corrosion rather than mechanical effects become dominant.

Jan 1, 2005

By Gema Ribeiro Olivo

The hydrothermal Au-Pd deposits are hosted by the jacutinga in the Lake Superior-type iron-formation of the Itabira Group, Minas Supergroup. Jacutinga is a highly sheared, metamorphosed, hydrothermally altered iron-formation composed of hematite, magnetite, quartz, talc and phlogopite (Cauê) or muscovite (Conceição) and minor tourmaline, palladian gold, arsenopalladinite, mertierite II and palladeisite (hydrothermal) and native gold, native palladium Pd-Cu-oxides, and kaolinite (weathering products). The highest concentrations of Pd-Au occur in quartz and hematite veins parallel to the S1 foliation (Corpo Y, CorpoX, Aba Leste and Central orebodies, at Cauê and a single orebody at Conceição) or parallel to the S2 foliation (Aba Norte). The average ore grade is 30-40 g/t Au+Pd. The characteristics of the Au-Pd ore favor an epigenetic model for gold and palladium concentration in the iron-formation. During the D1 deformation and peak metamorphism, the oxiziding, acid and hot hydrothermal fluids transported Au and Pd preferentially as chloride complexes. The reaction of the fluid with the dolomitic carbonate (the probably protolith of the jacutinga) would have dissolved carbonate and K-feldspar to form muscovite or phlogopite and tourmaline, resulting in an increase in solution pH and a decrease of Cl concentration and subsequent deposition of gold and palladium minerals.

May 1, 2003

By S. Vaidya, R. C. McKellar, N. K. Sinha

Nominally [001]-oriented nickel-base single crystal (SX) superalloy CMSX-10 was investigated at 900°C under constant load, equivalent to an initial stress of 700 MPa, for creep strains from 7% to fracture strain (18.2%). The cross-sectional dimensions of initially uniform cylindrical specimens were measured along their entire length after the tests. The cross-section changed from circular to near elliptical shape. The anisotropic deformation, measured in terms of eccentricity, increased with the increasing strain level, but for a given strain level, it remained constant along the entire length of the initially uniform gauge section. The results are discussed in terms of diameter, eccentricity, area, local stress and microstructural observations. The most striking observation was the fact that all the specimens displayed a yoke-like shape, or the reduction of cross sectional area, at two locations within the originally uniform gauge section. Such observations have not been reported in the literature for single crystal superalloys.

Jan 1, 2006