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By A. Brown

IN INTRODUCING the subject of rock pressures, it may safely be assumed that mining men are only too familiar with the physical effects of strata stresses that accompany the extraction of minerals. It may be further assumed that they have, as individuals, arrived at certain conclusions regarding their nature, based upon years spent in observing such phenomena and in learning how to continue mining in spite of them. Such hardly won experience forms the core of what is often referred to as 'pit sense'. This essential type of knowledge is not ?based on theoretical considerations, nor can it be found in text books. It is highly individualistic in nature and almost impossible to pass on from one generation to another in terms of precise rules for guidance. It is this aspect of individual judgment based on practical experience that has led to the significant phrase The Art of Mining.

Jan 1, 1956

By Marcelle A. Hauseux

"The Turgeon Lake granite lies 5 miles north of Baie Johan Beetz, Quebec, at the eastern margin of the Grenville Province. The rocks are classed as granites, granulites, quartzites, biotite schists and gneisses, and amphibolites. The granite's uraniferous character is manifested by phosphuranylite, uraninite, and metamict .zircons associated with magnetite. Field anomalies occur in irregular pods, conformable with the tectonic foliation, in bands roughly paralleling sedimentary bedding. Associated features diagnostic of uraniferous granite are smoky quartz, brick-red feldspar, magnetite and a coarse to pegmatitic grain size. The granite is chemically and physically heterogeneous. Metasediment-granite contacts are diffuse or sharp, and usually conformable to bedding. The regional foliations within all rock types are coherent, and sedimentary structures are often preserved within both metasediments and granite. Autometasomatism probably was a strong granitization agent.A uranium reconcentration into fold-axial zones from original sediments which have been highly granitized during at least two phases of folding is suggested from the available data."

Jan 1, 1977

By Shahé Shnorhokian

Remnant pillars evolve towards the latter stages of mining in an orebody and act as repositories of mining-induced stress. It is therefore crucial to plan ahead as to their dimensions and location with respect to the local geology. A case study of a Canadian base metal mine was examined for the planned mining sequence scenario to identify the stress regimes acting on a future remnant pillar occurring between levels 4800 and 5100, near a brittle dyke. A mine-wide model was constructed in FLAC3D and input parameters included results from field measurements of the direction and magnitude of the principal stresses, and the geomechanical properties of the different formations. Prior to the study, the model was calibrated based on a 6-year record of mining-induced seismicity and rockburst events, focusing on large event clusters. The mining sequence followed at the mine was then used in the model to study the planned future extraction program around the remnant pillar. It is shown that the distance of the remnant pillar from the dyke and another orebody plays an influential role on the stress levels developed in the pillar.

Jun 1, 2012

By H. J. Chalmers

"Since the advent of large volume flotation machines, Cominco Ltd. has actively studied possible application of such machines to their various milling operations. A number of installations have been made and more are on the drawing board. This paper gives a description of these units, information as to choice of equipment, and information as to operating experience. Mechanical and operating details of six installations are summarized. Three different types of machines are discussed.Pine PointThe original Pine Point zinc flotation circuit comprised conventional roughing with two stages of cleaning. Over the years with increase in feed tonnage there have developed two adverse conditions; namely, a reduction in zinc concentrate grade coupled with an increase in MgO in the concentrate. This resulted in higher freight payments along with more severe smelter penalties. An intensive test program, in 1971, showed that the concentrate grade could be raised by 1.5 units of zinc along with a reduction in MgO from 0.8% to 0.47.. Subsequently this was done by adding two additional stages of cleaning using 16 cells of Denver 200-V's. The project was completed in January 1973 at a cost of $510,000 to give an estimated annual savings of about $390,000.Selection of the Denver Model 200-V was based on minimum floor space requirement, availability, and favourable operational and maintenance experience with Denver 100’s. As it happens it was possible to ""shoe-horn"" the 16 cells into place with a minimum of plant alteration. Some problems have been encountered with a tendency to ""sand up"" at high pH, particularly at the corners. Otherwise operational service has been very good."

Jan 1, 1974

By E. J. Schwarz, A. A. Winir

"Absolute magnetite contents were determined for asbestos specimens in various stages of milling by using a Faraday-type thermomagnetic balance. Comparison of these results with magnetic ratings (MR) supplied by the mining companies cooperating in this study reveals strong scatter. The main cause of this scatter is thought to be that the MR values were obtained in magnetic fields well below the saturating field of magnetite (5,000 oe). However, only the saturation moment is an intrinsic property and consequently must be used for the purpose of obtaining reliable estimates of the magnetite content. Curie points indicate that virtually pure magnetite and possibly Ni3Fe is present in all samples, and another phase, probably (Cr, Al) magnetite, is present in a few samples. The susceptibility in fields stronger than 5,000 oe is positive and falls in the normal paramagnetic range, whereas sy nthetic chrysotile exhibits weak diamagnetism. This suggests that, as a general rule, the least adulterated natural chrysotile concurs with the samples showing the smallest positive susceptibility above 5,000 oe. The magnetite appears to increase in quantity with a decrease in fibre length and to be somewhat more uniform in distribution for samples showing substantial fiberization (opening of the fibres)."

Jan 1, 1971

By Roy S. Celland, K. H. Singh

The introduction of 'post' pillar mining at the Strathcona mine represents a new approach to ground support in cut-and-fill applications. The method has also shown significant economic advantages. It is believed that the development of this concept is one of the few examples where rock mechanics principles have successfully been applied in the development of a stoping method. The paper describes the evolution of this method and contains discussions on the theoretical analysis of the technical, operational and economics aspects of the system. Pillar design procedures and field observations on the practical application of theoretical analysis are also outlined.

Jan 1, 1973

By M. Moats, J. A. Gonzalez

A review of operating practices in zinc electrowinning plants is presented in this paper. Surveys were sent to several zinc electrowinning plants and data provided by some of these plants was compiled in a database. Information about anodes and cathodes, electrolyte composition, stripping methods, cells, electrical systems, and additives was compiled and analyzed. From the data analysis, correlations between operating variables are presented. Recent trends in operational practices are also highlighted.

Jan 1, 2008

By Fred E. Gray

The mill of Bralorne Mines, Limited, is located on the government highway in the Bridge River mining district of British Columbia, approximately fifty miles northeast of Shalalth, the shipping point on the P.G.E. railway. Prior to 1931, the property now owned by Bralorne Mines, Limited, was operated by Lorne Gold Mines, Limited. During the early operation of the mine, the ore had been treated at various times in one of three small amalgamation mills on the property. With the succession to ownership by the Bralorne Mines, Limited, work was started on construction of a new mill of approximately 100 tons capacity per day. The new mill was put into operation in the month of February, 1932, and since that date has been in continuous operation, milling an average of slightly over 3,000 tons of ore a month. The ore treated in the Bralorne mill is a gold-bearing quartz containing a very small amount of silver. About 75 to 80 per cent of the gold is in the form of free gold, the principal remaining portion being intimately associated with pyrite and arsenopyrite. The gangue rock is quartz, together with varying but relatively small amounts of altered diorite or albitite. In some of the ore, usually the higher grade portions, there is also considerable talc, which forms much slime in grinding. The mill is situated near the portal of the main haulage tunnel and the ore is received directly from the mine ore-trains, which dump on to the grizzly over the coarse-ore bin of the crushing plant. Figure 1 shows the flow-sheet of the mill as it is now being operated. Various changes have been made in the flow-sheet and in the reagents since the commencement of operations, and doubtless minor changes will continue to be made in order to increase the efficiency of the mill. Among the more important changes were those from two-stage to single-stage grinding, and from amalgamation plates to blankets. The change in the crushing was made because too much crushing was done when both primary and secondary mills were employed.

Jan 1, 1933

By I. Thobadi, C. Pawlik, K. Bisaka, S. Mokoena, M. Erwee

The PyEarth™ process developed at Mintek has been demonstrated successfully at pilot scale. Nine tons of ore containing 2.3 mass % of total rare earth oxides (TREO) from a dormant mineralogically complex iron-rich ore deposit, was subjected to a concentrating smelting step in a 200 kW DC open-arc pilot furnace and the rare earths from the resulting slag were extracted via a hydrometallurgical route. This ore deposit is practically not amenable to extraction by conventional methods. The testwork results proved that the PyEarth™ process was able to optimize the extraction of rare earths while minimizing waste through the removal of iron as a saleable iron alloy. Reduction of iron to the alloy in the smelting step was found flexible, efficient, and controllable, while rare earths were left virtually unreduced in the slag phase. The slag chemistry is selected to optimize both the smelting and leaching performances as well as the alloy composition. Leaching of the resulting slag was found possible and most efficient in hydrochloric acid amongst other lixiviants tested.

Jan 1, 2017

By S. U. Baltuch, E. G. Baltuch

"Ventilation in process buildings is key to proper mill function. Correctly engineered systems to evacuate surplus thermal energy from process areas allow optimized rates of air change, thus assuring the good functioning for the lifecycle of the process while demonstrating conformity with occupational hygiene standards. Computational fluid dynamic simulations, coupled with traditional calculations and physical modeling, can demonstrate to end users and assist engineers in the optimization of mill ventilation, reducing total installation costs while assuring that the proper solution is in place for the complete lifecycle of the process equipment. Results have been fully implemented on a number of steel mill and aluminium smelter applications and we continue to study, optimize, and innovate as new tools become available to provide the best possible engineered solutions for particular applications. INTRODUCTIONThe objective of this research project is the development and implementation of modern approaches and computational fluid dynamics (CFD) simulation in the engineering of green ventilation of hot process buildings. This will assure the predictive performance and improve the quality and ease of construction of industrial gravity ventilation equipment, along with the adjunct hot process buildings, while lowering the overall project costs and time to completion.In order for a hot process building, such as a steel mill, to properly function, heat must be extracted from within. This is accomplished by having air inlets at the bottom of the building and outlets at its apex. The reason for this is to maximize the potential chimney effect. When using stack (buoyancy) effect ventilation, the process heat becomes the driver. Therefore, increasing this distance (height) improves the ability of the heated airstream to utilize basic gravity for acceleration of the heat/air flow, allowing a regular number of air changes per hour while ensuring that the process environment remains weather resistant under normal operating conditions.This process has been understood since the time of King Charles I of England, who decreed in 1600 that buildings should have 10 foot ceilings and that windows should be made taller rather than wider to allow better smoke extraction.Figure 1 is a painting of the Bethlehem Steel Works in the 1860s, where the concept of air inlets and penthouses on the roofs for air outlet was already being put into practice. Figure 2 is an early photograph of the Pittsburgh Steel Works."

Jan 1, 2012

By R. W. Thompkins

In order to evaluate the impact of air quality control on mine design, a few examples are given of cases in wh.ich ventilation has affected the economics of the total design problem. Principles for the drainage of gas contaminants are shown, and the contamination control problems created by differential pressures in complicated booster fan installations are discussed. The paper also deals with the use of advanced mathematics for solving some of the ventilation problems likely to be encountered.

Jan 1, 1967

By G. Morin, F. Chiesa, B. Duchesne

The Quality index is a useful tool allowing to assess the metallurgical quality of aluminium AlSiMg foundry alloys (A356/357). Its value is calculated from the ultimate tensile strength and elongation; it increases with the metallurgical quality of the casting, i.e. with finer dendrites, lower microporosity and inclusion count and lower iron content. This Quality index does not depend on the degree of temper applied during the heat treatment (aging time and temperature). After defining the Quality index, it will be explained how it can be predicted from the knowledge of the local solidification conditions obtained from modelling. The paper will then present four case studies of castings for which the prediction of the Quality index by modelling was made. These case studies from different authors will involve the three most common casting processes used for producing high integrity aluminium castings, namely: sand casting, permanent mould casting and investment casting (lost wax). In all cases, the accuracy of the prediction will be assessed by comparing the predicted Quality index distributions to the experimental values based on the published measured values of the local tensile properties.

Jan 1, 2006

By K. V. Lindell

Introduction This paper describes a recent innovation in the design and construction of mine headframes. A reinforced concrete headframe was built by using sliding forms. A concrete headframe of conventional design was originally considered, but investigation of this project showed that it was doubtful if the bearing strength of the soil was sufficient to support the great weight of a structure of this type. In addition, the slope and the fractured condition of the serpentine bed-rock did not permit satisfactory piling. A conventional steel headframe with storage bins was then designed, but, due to the steel situation, delivery promises were set back many months. The concrete headframe was again investigated, and a design was adopted incorporating a circular headframe lower in height than that first considered, with skips discharging into a smaller surge bin. The upper section of the shaft collar was strengthened to result in a stable structure which would be supported by bed-rock, as well as by the concrete and steel lining of the shaft itself.

Jan 1, 1948

By M. L. Jeremic

The design of the long-hole sublevel mining method was originally based on the traditional assumption that the principal load was due to the weight of the overlying rock, and that the horizontal stresses are equal to one-third of the vertical stress. However, as mining progressed, the virgin lateral stress was found to be equal to or greater than the vertical stress. The virgin stress in the rock mass is not uniform throughout the folded orebody and adjacent strata. From detailed investigations, three basic patterns of virgin stress in ore panels have been inferred: uniform, bent and twisted. Stresses induced by stoping are up to three times greater than original stresses in the rock mass; they cause heavy ground conditions and make extraction of ore difficult. In the last ten years, the original mining system has been modified several times in order to destress the ground and improve the extraction of ore.

Jan 1, 1978

By H. Perez, A. Lavoie, V. Prévost, P. Létourneau, P. Lind

The Home smelter is a custom copper smelter located in Rouyn-Noranda, Quebec. In 2005, the smelter produced 145,000 t of copper containing 807,000 oz of gold, 20,388,000 oz of silver in addition to 515,000 t of sulphuric acid. Recently, a flexible flow sheet has been developed incorporating the intermittent use of the Noranda Continuous Converter allowing for the increasing or decreasing of production based on market conditions, while attaining 90% or greater sulphur fixation regardless of operating mode. For 2006, the smelter is operating in full production mode and production is expected to be approximately 185,000 tm of copper. Mechanical modifications, process changes, metallurgical concepts, minor element treatments, and operational techniques that have allowed the smelter to develop this flexibility are presented. Current efforts to increase the productivity of the converter aisle and anode furnaces as well as improvements being made to address fugitive emissions are also discussed.

Jan 1, 2007

By Amir Zavichi

Today, with the necessity of timely, on-budget and high quality completion of projects, proper use of construction equipment is essential to ensure project success. Construction equipment places a large monetary burden on the project and if not utilized efficiently, it can result in economic losses. Cranes are one of the most important and expensive operational devices on construction sites. They play a central role, and often activities that rely on crane services fall on the project?s critical path. Currently, material-handling scheduling is done by the crane operator or by an on-duty superintendent using his/hers personal judgment, making the process manual and timeconsuming. Thus, developing an optimal schedule, which considers different dynamic constraints in construction job site, may not be possible based on the current practice. This leads to longer operation times and a negative impact on project cost. This paper presents the latest results of an ongoing study, which aims to design and implement a nearreal time crane operation decision support system to be utilized directly by the crane operator or as an aid for the superintendent in scheduling optimal operation services. This system has several advantages such as maximizing the efficiency of crane operations, guaranteeing the best operation possible to reduce the crane?s travel time, reducing crews and equipment idle time, and minimizing the dependence on subjective human judgments.

Aug 1, 2013

By V Dolmage

In 1957 and 1958, ten topographically suitable damsites were investigated along the Peace river between Finlay Forks and Hudson Hope, B.C. Of these, three were eliminated after a reconnaissance survey indicated that the geology was unsuitable for the 650-ft.-high dam contemplated. ?After extensive drilling, five other sites were deemed unfeasible because of geological factors and, in 1959, the two remaining sites were designated as being suitable, one for the high dam and the other for a low dam downstream. The sites are located in the Peace River canyon, on the west and the south? side of Portage mountain, west of Hudson Hope. The site for the large dam, the Portage Mountain dam, has since been investigated by surface mapping, thousands of feet of diamond drilling, a seismic survey, laboratory rock tests and on-site grouting tests in order to establish the possible effect on the dam of all facets of the foundation rocks. Three diversion tunnels, 50 ft. in diameter and 2,200 feet in length, have been driven through massive sandstone and shale, and an intake cut, 500 ft. in length, 200 feet in width and 200 feet in depth, has also been excavated in rock.

Jan 1, 1963

By L. R. Wilkinson, W. J. Howarth, G. J. Wenk

Over a period of three years, a cooperative program in Australia has resulted in the development of radioisotope immersion probes for the on-stream analysis of mineral slurries. Two basic probe types are now available on a commercial basis - fluorescence and absorption probes - and within each type there are a number of variations so that optimum sensitivities can be obtained for elements with atomic number greater than titanium (22), thus covering most metals of interest to modern metallurgy.

Jan 1, 1973

By T. Miura, Y. Mori, H. Aoki

In a flash smelting furnace, easily combustible concentrate particles excessively oxidized and melt. The excessively oxidized molten particles then collide with less oxidized solid ones to create uniform oxidized molten particles. This collision phenomenon plays a very important role in achieving high smelting performance. The authors developed a mathematical model describing above combustion phenomena. This model incorporated fluid flow, heat and mass transfer, chemical reactions and collisions of concentrate particles. Both gas flow and particle motion were calculated using the Eulerian method. Copper concentrate was assumed to consist of chalcopyrite(CuFeS2). Considered in the concentrate reactions were the decomposition of CuFeS2, and the oxidation of the resulting sulfur(S) and pyrrhotite(FeS) to produce magnetite(Fe30 4) and sulfur dioxide(S02). Moreover a reaction due to concentrate particle collisions, in which Fe304 in the excessively oxidized molten particle reacts with FeS in the less oxidized particle, was also considered. The particle collisions were assumed to occur according to a collision probability rule obtained by computational experiments. Particle growth in diameter was described as a change in the volume fractions of particle phases. When applied to a commercial flash smelting furnace, this model reproduced the particle growth and component transfer as observed in the actual furnace.

Jan 1, 2007

By Shae K. Kim

The aim of this study is to manufacture magnesium alloys with alkaline earth metal oxides (BeO, CaO, MgO or SrO) additions with the objectives of (1) ensuring safety during processing and applications by raising the ignition temperature and reducing oxidation, (2) protecting the environment by reducing or eliminating use of protective gases, (3) maintaining or improving elevated temperature properties with lower amount of Ca or Sr or rare earth metals when compared with conventionally developed high-temperature magnesium alloys, (4) developing cleaner strip casting and continuous casting processes without hot tearing and (5) obtaining all of these objectives without sacrificing mechanical properties or increasing the cost of magnesium alloys.

Jan 1, 2006