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By Eduardo R. Rodrigues, Ankur Narang, Roberto Federico Ausas, U. T. Mello, Jose Maria Segura Serra, M. R. Lakshmikantha, Ignacio Carol, Kamal C. Das

"Modeling of big faults or weak planes of strong and weak discontinuities is of major importance to assess the Geomechanical behaviour of mining/civil tunnel, reservoirs etc. For modelling fractures in Geomechanics, prior art has been limited to Interface Elements which suffer from numerical instability and where faults are required to be aligned with element edges. In this paper, we consider comparative study on finite elements for capturing strong discontinuities by means of elemental (EFEM) and nodal enrichments (XFEM) for Geomechanical applications. For general fracture scenarios, Oliver et al. (2008) have demonstrated advantages of EFEM over XFEM for including: (a) ease of modeling in any standard finite element code due to the possibility of static condensation, (b) higher accuracy in some cases for coarse meshes, and, (c) a reduced computational cost. However, there has been no work that considers cohesive fractures in Geomechanics. We present a numerical analysis based on a linear constitutive model and linear triangular elements for the bulk and a linear constitutive behaviour for the fault for a representative set of fault planes in a circular tunnel made in rock mass. In the numerical examples we consider both well-traced and bad-traced meshes. We focus on traction profile analysis for both EFEM and XFEM, since that is crucial to understand the cohesive fracture behaviour specially rock joint. Therefore in each case, shear, normal and stress ratio are compared across the two methods along the fault plane. This is the first such work that compares XFEM and EFEM behaviour for Geomechanics problems.For the considered class of problems and the sharp penalization approach without regularizations adopted, it can be observed that accuracy and robustness of EFEM may strongly depend on the fault orientation with respect to the element edges, while, XFEM is independent of fault alignment with element edges. It has been also observed that, with mesh refinement model, stress oscillation completely removed with XFEM however EFEM fails to provide oscillation free results with finer mesh in case bad-traced model. We also performed error analysis and found that in case of bad-traced mesh the average error in the XFEM is 84% smaller than of EFEM and for XFEM the error goes to zero with increasing mesh resolution, while for EFEM the error increases with mesh resolution. Thus, we experimentally demonstrate that, XFEM performs better than EFEM in terms of accuracy and rate of convergence with marginal increase in computational cost. This work hence provides novel insights on the application of XFEM and EFEM in Geomechanics."

Jan 1, 2015

By R. F. Robertson

"Adsorption isotherms of hexyl mercaptan vapour on synthetic sphalerite, zinc sulphide and zinc oxide were de-termined with a gravimetric McBain-Baker micro balance incorporated in the B.E.T. apparatus. Isotherms are given for hexyl mercaptan on synthetic sphalerite at 25°C, 0.5°C and 50°C; on zinc sulphide at 25°C and 1.5°C; and on zinc oxide at 25°C. All these isotherms are sigmoidal, with a definite change in slope at or close to the mono-layer. The amount of mercaptan adsorbed below the monolayer increases almost linearly with relative pressure to P/P0 = 0.8.Above this value, the amount adsorbed increases very rapidly with relative pressure. Hysteresis loops appear in the isotherms for all adsorption-desorption cycles. These loops are completely reversible. It is not possible to desorb the mercaptan monolayer from any of the adsorbents, even at elevated temperatures."

Jan 1, 1966

By Parviz N. Farsangi, Ferri P. Hassani, Allen G. Hayward

"Kidd Creek Mines places approximately 10 000 tonnes of consolidated rockfill (CRF) daily. Consolidated rockfill comprises sized aggregate mixed with different ratios and amounts of binders. Consolidated rockfill is employed to simplify subsequent pillar recovery and provide improved passive/active ground support.The consolidated rockfill is designed to sustain not only the gravitational loading of the overlaying fill material, but also to some extent the dynamic loading applied during blasting of the adjacent stopes and/or pillars. This paper describes the steps taken to optimize the pre-sent fill system at Kidd Creek Mines.The emphasis is on four areas which have high saving potential: lower cost alternative binders, structural design, quality control measures, in-situ testing techniques for back analysis. A consolidated rockfill design optimization chart was developed from these investigations."

Jan 1, 1996

By Ward G. Wilson

Best practice in the design and construction of soil cover systems for mine waste management has advanced extensively over the past two decades. While significant progress has been achieved, we still have little experience with respect to proven performance for cover systems that must last hundreds of years. Some cover designs appear to be functioning well, while at the same time the performance of many more are now being called into question. This presentation evaluates the integrity of cover systems from both a global and local perspective in relation to the uranium industry within Canada.

Aug 1, 2010

By P. M. Chapman

Risks to aquatic receiving environments from uranium mining and milling fall into three categories: physical (habitat change), chemical (e.g., uranium, selenium, total dissolved solids [TDS], metals including vanadium), and radiological. Although all categories of risk need to be managed, chemical risks are the most significant and are typically chronic rather than acute. For instance, selenium toxicity is primarily manifested as reproductive impairment due to maternal transfer, resulting in embryotoxicity and teratogenicity in egg-laying vertebrates. Risk is best assessed using a weight of evidence approach focused on ecosystem services. Risk management should be based on both risk assessment and adaptive monitoring.

Aug 1, 2010

By M. Oliazadeh

The bioleaching of fine low grade copper sulfide ore is described. A sample of ground (> 1 mm) copper ore from Sarcheshmeh, Iran, was subjected to a series of agglomeration procedures and subsequently leached. The best agglomerate was obtained by using lime and sulfuric acid as binders. A column bioleaching test of agglomerated ore was then run for 105 days along with a non-inoculated control column having thymol as bactericide. The results show that about 77.5% of copper was extracted in the bioleaching, whereas the control column achieved only 57% copper leaching.

Jan 1, 2007

By C. Moctezuma

Since the start up of the IMMSA electrolytic zinc refinery in 1982, the dissolved iron coming from the acid attack of the ferrites has been precipitated by the jarosite process. At the beginning of operations, sodium jarosite was produced; however, the plant was converted to ammonium jarosite in 1990. The final storage of the residue is on the company&apos;s property adjacent to the plant, over the natural surface of the land. Before the construction of the refinery, several studies were done in order to evaluate the characteristics of the ground, such as, permeability, underground water localization, etc. The results showed that the site was adequate for the storage of this kind of material. For several years, the jarosite residue was filtered on rotary drum filters and was sent as a pulp to the storage area for settling. The water from the storage pond was recycled to the re-pulp tank for the jarosite residue. These filters were replaced in 1999 by an automated filter press. Since then, the jarosite residue has had a lower water content, and the zinc recovery improved. At present, a second filter press for the jarosite circuit is in the acquisition process to diminish the soluble zinc content in the residue from the present value of 2% to < 1% Zn.

Jan 1, 2006

By T. Grammatikopoulos, K. Gibbs, H. De Souza, C. Gunning

The mineralogy of any ore body is a key factor in defining ore zones and predicting minerals/metals behaviour during processing. The determination of forms of gold, defined as the different chemical states in which gold is encountered in ore deposits, is critical. The most commonly known form is that of gold minerals and alloys, while other forms of gold have been collectively described in the literature as submicroscopic gold (i.e., less than 1 µm in diameter). Gold mining operations generally deal with very low-grade ores, in the order of a few g/t, in which gold displays complex mineralogy. These difficulties complicate the mineralogical studies and pose challenges for processing and recovering the gold. A comprehensive understanding of the chemical forms of gold is necessary to define gold mineralization and optimize gold metallurgy. SGS Canada Inc. has been using QEMSCANTM and a Tescan automated SEM that are automated mineralogical techniques that provide vast amounts of data for microscopic Au. The data in conjunction with other physical and chemical methods provide a comprehensive delineation of the ore composition and behaviour.

Jan 1, 2011

By Junior Santos

Kinross Paracatu started the operation of the new gold processing plant in the end of 2008, being composed by one SAG mill and two ball mills. During the first year of operation the plant had several problems related to stability and throughput capacity, mainly due to low grinding efficiency of the ball mills. In this period many actions were taken to maximize the throughput rate. Among the actions are reducing the size of balls in the mills, increasing the ball charge in the SAG mill, changing cyclone configuration and return of circulating load to SAG mill. With better stability of the circuit, the second stage of improvements has begun with the objective of increasing throughput rate and also reducing operation costs. Among the actions are the optimization of ball charge in the mills and a better operational control of cyclone parts. After two years of operation was obtained a significant increase in plant capacity, but still requires the addition of a third ball mill in order to maximize the use of SAG mill, which has spare capacity.

Jan 1, 2012

By D. D. Liu

This paper proposes a charge induction dust measurement method based on detrended fluctuation analysis (DFA) for use in coal mine environments, based upon electrostatic interference, dust properties, wind speed, particle size, moisture content and other factors. In this methods, sequence x(t) is first obtained through a dust concentration sensing probe, and then the cumulative deviation y(t) is calculated, and y(t) is divided into same lengths. Secondly, a first-order linear fit is used for data of each interval, and mean-square deviation filtered DFA was calculated for each interval. Finally, the dust mass concentration of the corresponding time is obtain by supplemented calibration coefficient and fitted the data point which is the mean and square root for all lengths of interval. Simulation and verification experiments showed that the charge induction dust measurement method based on DFA can reduce coal mine electrostatic interference effects with high accuracy. The design has been successfully applied to select areas.

Aug 1, 2013

Phelps Dodge has recently operated a commercial scale, super fine grinding circuit of copper concentrates for use in a medium-temperature pressure leaching process. Two 355 kW vertical stirred mills were installed in series, targeting a grind of 80% passing 7.5 µm and 98% passing 15 µm as outlined in Phelps Dodge&apos;s concentrate leaching patent portfolio. This paper details the operation and results of the test program at Bag dad, as well as some of the operating challenges encountered.

Jan 1, 2007

By S. Devereaux, P. Gover, S. Everett

Having real-time data of blast furnace burden profile with respect to burden height and temperature is critical to making informed decisions on blast furnace operation. Given the high temperature and gaseous environment within the blast furnace shaft, traditional instrumentation has been limited at providing the level of real-time feedback information needed to optimize blast furnace operations. Infrared thermal imagery technology provides non-contact temperature measurement across the entire burden profile, allowing for better understanding of the dynamic movement of the burden within the blast furnace shaft. This technology increases blast furnace performance by improving the decision-making process for hour by hour operations. This paper will discuss the development of incorporating infrared thermal imagery technology into the operating strategy of a lead blast furnace.

Jan 1, 2015

By V. Concha, M. Hashemzadeh

"The objective of this study was to gain a better insight into the kinetics of chalcocite leaching in an acidic ferric sulfate media. Chalcocite leaching in acidic media is known to occur in two sequential stages, with the first stage being much faster than the second. The leaching residue from the first stage is typically assumed to be a covellite type of material. This study hypothesized that the mineralogy after the first-stage leaching varies in response to different leaching conditions. We investigated the dependency of the mineralogy of the first-stage leaching residue on temperature and initial ferric concentration. The experimental results showed that chalcocite leaching behavior altered upon temperature and initial ferric concentration. A proposed combined reaction model was found to be able to describe the experimental data. The first stage was described very well by the shrinking core diffusion model while the second stage was described very well by the shrinking core chemical reaction model. This finding has important implications for mine operations to manipulate leaching conditions to create the desirable leaching kinetics.INTRODUCTION The kinetics of chalcocite leaching in sulfate media has been extensively studied (Cheng & Lawson, 1991; Fisher, 1994; Fisher, Flores, & Henderson, 1992; Niu, Ruan, Tan, Jia, & Sun, 2015). Sullivan (John D. Sullivan, 1930) proposed a two-stage process for chalcocite leaching in an acidified ferric sulphate solution. The two-stage leaching of chalcocite is presented as the following reactions:"

Jan 1, 2017

By C. H. Madsen

THE Hard Rock gold mine is in the Little Long Lac mining area, Thunder Bay district, northwestern Ontario. It is four miles by road from the town of Geraldton, which is on the Canadian National railway, 180 miles northeast of Port Arthur. The original discovery of gold-bearing quartz veins on the property was made in 1931. Shaft sinking began in the fall of 1934 and approximately 7,400 feet of lateral development on four levels was completed. In 1935, further discoveries were made half a mile west of the early workings, and the No. 2 shaft was sunk in this area in a porphyry zone. In January, 1938, a 20C-ton cyanide plant was completed and began drilling ore from the gold-bearing porphyry orebody. The daily feed was increased gradually to 300 tons in the next six months and a recovery of 97.5 per cent was effected. During the summer of the same year, a new and larger orebody was discovered to the north of the porphyry zone. It occurs in a band of iron formation and contains a high percentage of pyrite and arsenopyrite. Extensive tests were rr.ace on this sulphide ore in the Mines Branch ore dressing laboratory at Ottawa, in the laboratory of Canadian Industries, limited, at Toronto, and later at the mine, to find a suitable method of treatrr.ent. As a result of this research, a Potation plant was added to the original cyanide mill and on November 7th, 1938, differential flotation was used to separate the pyrite from the arsenopyrite fraction of the ore. The pyrite concentrate was re-ground and cyanide:l, and the arsenopyrire concentrate was stored for subsequent treatment. Differential flotation was discontinued in April, 1939, in favour of bulk formation of all the sulphides, and the whole cyanide residue was stored. On March 15th, 1939, a 10-ton pilot roaster was completed and rests were conducted on the arsenopyrite concentrate and the bulk concentrate. The results obtained led to the building of two roasters of the same type, large enough to roast all the concentrates. These roasters were put in operation on September 24th, 1939, and the calcines were cyanided in the original circuit.

Jan 1, 1941

By A. Khan

The purpose of this paper is to demonstrate the value of identifying and optimizing throughput constraints by utilizing a Constraint Model. This will be achieved by first understanding the overall concept of Operational Excellence, Continuous Improvement and Theory of Constraints as practiced within Vale Canada Limited. Next, the value of utilizing a Constraint Model is demonstrated by primarily identifying constraints. The applications in utilizing Constraint Models will be demonstrated, including the primary benefit of identifying constraints. The remainder of the paper will focus on how to properly setup a Constraint Model using discrete simulation (regardless of simulation software). Benefits of understanding the severity of constraints and movement of the bottleneck will be recognized. The paper will conclude with the summary of real applications within Vale Canada Limited.

Aug 1, 2013

By H. R. Stockford

"A pyroxenite-carbonatite complex containing extensive pyrochlore mineralization was discovered during January, 1966, within an exploratory license area held by Consolidated Morrison Explorations Limited. Located 32 miles south of Moosonee, Ontario, the deposit was found under 100 feet of glacial till and Paleozoic sedimentary cover using airborne and ground magnetometer surveys. Exploratory and detailed drilling, totalling 47,625 feet in 85 holes, was completed in outlining the deposit to a maximum depth of 900 feet. Pyrochlore reserves are estimated at 62,000,000 tons averaging 0.52 per cent Cb,05 to a depth of 825 feet. Included in this tonnage is a high-grade section containing 10,000 tons per vertical foot grading 0.82 per cent Cb20 5• The deposit is still open at depth and the intrusive complex has by no means been fully explored.The columbium (niobium) mineralization occurs in a lineated calcite-dolomite host rock which has been intruded along a fault zone within a northeast-trending granulite belt. Potassium-argon dating indicates an age of 1655 million years.Preliminary studies suggest that the complex was intruded in a series of pulses in the form of a partially crystallized mush. The James Bay intrusive is unusual in that it is linear in form and contains only two main rock types - p•yroxenite and carbonatite. Nepheline-bearing syenites and associated rocks are notably absent. Moreover, the pyrochlore is essentially non-radioactive and free from many of the impurities generally associated with other pyrochlores. A test shaft to investigate soil conditions and to provide a 250-ton bulk sample was completed during 1968. Subsequent pilot-plant operations indicate that good quality pyrochlore concelttrates can be produced from this deposit."

Jan 1, 1972

By Jr. Carmichael

"THE MAYO AREA was prospected as early as 1887. The first major activity started in 1898, when the Stewart River and its tributaries were examined for placer deposits, and in succeeding years the district became a small producer of placer gold. The first discovery of the lead-zinc-silver mineralization which has become the main interest of the district occurred in 1906, when a vein was found in the canyon of Galena Creek on the northwest slope of Galena Hill. This deposit was later known as the Silver King mine. In 1919 further discoveries were made on Keno Hill, approximately 15 miles east of the Silver King, the most important being the No.9 vein. Directly or indirectly, these finds are attributable to the search for placer gold, as galena was frequently found in the stream gravels.The 1919 Keno Hill discoveries were acquired by Yukon Gold Co. and operated through a subsidiary, Keno Hill Ltd., from 1920 to 1923. Most of the production came from No.9 vein. In 1921 Treadwell Yukon Corporation entered the field and acquired the Ladue mine. This company continued to operate for 21 years. It acquired in succession the Ladue, Sadie, Friendship, Lucky Queen, Elsa, Silver King, and Calumet mines. Its record of successful operations is very largely the achievement of the late Livingston Wernecke. Under his direction, the Treadwell Yukon Corp. produced metals with a gross value in excess of $21,000,000, in the face of greater transportation problems than exist today and with considerably lower metal prices.Treadwell Yukon ceased operations in 1942. Its entire assets were acquired in 1946 by United Keno Hill Mines Ltd., which has substantially increased the original holdings. It has drawn the bulk of its production from the Hector mine, adjacent to the Calumet. The Hector was not developed by Treadwell Yukon because of legal disputes among the vendors. It has proven to be the largest deposit yet discovered in the district."

Jan 1, 1949

By The Staff

Introduction In this paper it is proposed to discuss briefly some of the problems confronting the management of a gold mine in choosing a method of milling to recover the gold from various classes of ore. In order to simplify the discussion, the more common types of gold ores are classified from a metallurgical point of view as follows: Class 1?A: Free-milling ores which require only relatively coarse crushing. B: Free-milling ores which require finer grinding to release the gold. Class 2?A: Gold ores which contain the gold partly in the flee state and partly associated with a small amount of iron sulphide, and which do not require fine grinding. B: Gold ores similar to 2A, but which require fine grinding. Class 3?A: Gold ores containing copper in quantities insufficient to interfere to a serious extent with cyanidation. Gold ores containing copper in sufficient quantity to interfere with cyanidation but in which a large proportion of the gold is in the free state, the remainder being chiefly associated with the copper mineral, chalcopyrite. Gold ores containing copper and other sulphides, such as pyrite, etc., in which the gold is principally associated with these sulphides.

Jan 1, 1931

By Robert J. Shank

This paper describes the Federal Government assistance available for northern mining development. The paper commences with a discussion of why the Federal Government should give assistance to northern mining development. It then uses a hypothetical case of a company which has a property it wants to develop to list the sectors within the . Federal Government that would have to be consulted in order to obtain federal financial assistance. The paper also outlines the type of information a company must be willing to provide the government in order to qualify for such assistance.

Jan 1, 1978

By P. Mengé

The covering of a hydraulically filled goethite pond is discussed from a geotechnical point of view. The characteristics of the goethite were defined in order to allow a detailed study of the procedure for the construction of the cover on top of the soft material and a verification of the stability of the cover and side slopes after construction. These characteristics and the main results of the studies are given, as well as the experiences and observations made during the execution of the work. Finally, the monitoring plan, during and after construction, is also discussed and some results are given. The &apos;Design and Construct&apos; contract form was used to allow the contractor to choose the optimum and most economical method to realize the closing of the pond, based on his experience with similar projects. The works were carried out between mid 2003 and the end of 2004. The paper will, amongst others, discuss the special method of working that had to be developed to allow the covering of the whole pond in a relatively short time period, without soil improvement methods such as vertical drains or stabilization by in situ treatment. Fill material was used to establish a platform on top of the soft material so that the cover liner and finishing layer could be installed on top of the fill layer. The &apos;floating roof&apos; principle was used; subsidences were allowed to occur during the installation of the impermeable top liner and soil cover.

Jan 1, 2006