Search Documents

By L. Yuan, J. H. Rowland, R. A. Thomas, D. Bahrami, G. P. Cole

"The past several decades have seen a steady increase in the use of atmospheric monitoring systems (AMS) in underground mines as sensor technology has advanced and costs for this technology have decreased. The AMS is a reliable tool for early mine fire warning by detecting gaseous products of combustion in underground mines. During a mine fire emergency, mine decision makers rely heavily on the prompt and accurate knowledge of the ventilation and fire situation in the mine, such as fire location, fire size, and the spread of smoke to make effective and efficient decisions on firefighting strategies and miner evacuation. Meanwhile, a prediction of the potential for fire development at a later time, such as whether the currently designated mine escapeways will be contaminated by smoke and toxic gases with the progress of the fire, is critical for effective decision-making to save lives that are in danger. The AMS monitoring data, including carbon monoxide (CO) concentration, airflow rate, smoke, etc., can provide information as to whether the smoke has reached the locations where AMS sensors are installed and if a mine-wide smoke spread has occurred. The National Institute for Occupational Safety and Health (NIOSH) has undertaken a task to integrate real-time AMS monitoring data with the mine fire simulation program, MFIRE, to simulate and predict the spread of smoke and toxic gas in a ventilation network based on the real-time AMS data. This paper reports the developed real-time method for characterizing the size and location of an underground mine fire and for predicting the spread of contaminants throughout the mine ventilation network using sensor data from the AMS.INTRODUCTIONNIOSH conducts research to develop workplace solutions to improve detection of and reduce the risk of hazardous conditions in underground mines. The advancement of senor technology and the increasing demand for real-time mine parameters monitoring have led to extended applications of atmospheric monitoring systems (AMS) in underground mines worldwide. In the United States, AMS is primarily used for early mine fire warning by detecting carbon monoxide (CO) in fire hazard areas, such as belt entries. Mine fires can grow rapidly, and time is the critical element. Prompt detection, timely and accurate warnings to those miners potentially affected, and a proficient response by underground miners can have a tremendous impact on the social and economic consequence of a small underground mine fire (Conti et al., 2005). The early detection of a mine fire could gain time for the first responders to put out the fire before it develops into a disaster. An AMS system with CO sensors has especially played an important role in the early detection of mine fires. The continuous monitoring of an underground mine atmosphere with an AMS could generate a large amount of data in a mine fire event. However, the current application of AMS is mainly limited to sending out an alarm when monitored CO concentration exceeds a certain level. An opportunity arises as to whether these data can be further used in fire emergency response. In order to make effective decisions on firefighting strategies, mine workers’ seeking refuges, evacuation and escape, and the timing on when to send rescuers, decision makers need accurate and timely knowledge of the ventilation and fire situation in the mine. Information about the fire intensity, where in the mine the smoke and toxic gases have spread, and whether designated mine escapeways have been compromised by smoke and toxic gases from the fire would greatly increase the effectiveness of these decisions. However, the monitored AMS data only provides atmospheric conditions in the vicinity of sensor locations. What is concluded from the monitored AMS data highly depends on the decision makers’ capability and experience. Predictive insight into fire growth and smoke transport would greatly help decision makers during a fire emergency."

Jan 1, 2019

By G. Song

This paper reports the anodizing voltage, gas evolution and sparking behaviors of an anodized coating formed on AZ91D in a silicate containing solution. According to their responses to an anodizing current, a four-stage anodizing mechanism is proposed. At the same time, the formed coating is characterized in terms of its microstructure, composition, thickness and corrosion performance. It was found that deposition of MgSiO3, Mg(OH)2 and MgO as well as dehydration of Mg(OH)2 are involved in the anodising process; the vigorous gas evolution accompanied by intensive sparking and the corresponding negative anodising efficiency in the later stage of the anodising process are closely associated with thermal decomposition of water due to the high temperature resulting from the intense sparking on the surface of the anodized alloy; the thickness, porosity, and composition of the anodised coating on a magnesium alloy depend on the final anodising cell voltage; and the corrosion resistance of a thick but porous coating containing more silicates appears to be more corrosion resistant than a thin but compact coating containing less silicates.

Jan 1, 2006

By Changyoon Kim

Technological advances in mobile systems, such as smartphones and tablet computers, provide engineers with new opportunities to enhance the current facility management processes. Equipped with powerful system processors, touch screens, and wireless communication capabilities, mobile systems enable the experience of omnipresence of facility information. Building information modeling (BIM) also enables improvements in facility management. With an advanced data structure and visualization capacity, BIM can be used in numerous applications for facility management. This study aims to incorporate the strength of mobile systems and BIM in facility management. The proposed system, which utilizes smartphone technology, allows engineers to conduct facility management functions, such as maintenance planning, inspection, and assessment, irrespective of a user?s location. The integration of building information modeling in a system provides detailed visual information of the building components. A case study was conducted to verify the applicability of the mobile system in terms of the hardware functions, system design, and user interface. This proposed system, with its study results, provides a guideline as to how mobile systems can be effectively integrated with BIM for improved management of facility information.

Aug 1, 2013

By A. J. Russell

"This paper investigates why it is critical for a mine to accurately determine thermal rock properties and virgin rock temperatures. Theoretical simulations of deep mining production zones have demonstrated that thermal conductivity (k), virgin rock temperatures and specific heat (cp) significantly impact rock heat predictions which can be the dominant component of a mine’s heat load. Natural variability in these factors showed that realistic errors can have a significant effect on mine heat loads. This can ultimately affect miner safety and introduces risk to the viability and sustainability of a project. INTRODUCTION Accurate heat load determinations are critical to ensure that underground working conditions are maintained within legislated and mine specific parameters to safeguard the safety and productivity of employees. Underpredicting mine heat loads will result in hot underground conditions, which risk the health and safety of employees, reduce the productivity of employees or stop production if legislated temperatures in working areas are exceeded. Overestimating mine heat loads will result in increased capital and operating costs reducing the viability of the project. Over- or under- predicting the heat load for a project will increase the project risk. Heat sources in a mine can broadly be broken into two categories. These two categories are defined by Hemp and Rawlins (2014) as natural and artificial heat sources. Those sources which depend on the size, location and depth of the mining areas are defined as natural heat sources, whereas those heat sources which are a result of the actual mining activities are defined as artificial heat sources. Autocompression, or the conversion of potential energy, to enthalpy is an important consideration when determining the air temperature in the mine and its interaction with natural and artificial heat sources. It is documented by Jones (1985) and Hemp and Rawlins (2014), that the heat flow from rock in deep mines can dominate other heat sources; information from BBE’s archives show that this is between 40% and 60% of the total heat load. They also point out the importance of accurately measuring both the thermal rock properties and virgin rock temperatures (VRTs) for determining and planning the ventilation and refrigeration requirements for a mine. Both of these texts cite multiple methods for calculating the heat-flux and ultimately the heat load for the different working areas in a mine. All of these methods demonstrate that the heat flux and heat load will increase proportionally with increased thermal conductivity (k), specific heat (cp) of the rock or mineral, and VRT depending the area of the mine or mining method."

Jan 1, 2019

By M. J. Nicol

The leaching of gold with thiosulfate solutions in the absence of ammonia and copper ions was investigated using electrochemical and kinetic methods. In sodium thiosulfate solutions, the electrochemical oxidation of gold was hindered and the leaching rate using pure oxygen as the oxidant was very slow. It was found that the addition of a small amount of thiourea or formamidine disulfide to the thiosulfate solution greatly enhanced the oxidation of gold. However, the enhancement to the overall dissolution of gold using dissolved oxygen as the oxidant was limited. This was attributed to the fact that the oxygen reduction process was unaffected by the additives and remained slow, which limited further improvement to the overall kinetics. An alternative oxidant, the ferric EDTA complex having a reduction potential of approximately 0.12 V, was found to be promising. The cathodic reduction of ferric EDTA was fast and reversible at neutral pH. While the ferric EDTA complex was effective in oxidizing gold, it did not appear to significantly oxidize thiosulfate. A thiosulfate solution containing thiourea and ferric EDTA has been shown to quickly dissolve gold in the form of a powder as well as from gold ores. In the leaching with the ores high gold recoveries of above 90% was achieved with the best performance obtained in neutral solutions (pH 6-7).

Jan 1, 2005

By Esau Arinaitwe

The most extensively used methods and approaches for characterizing and selecting frothers for plant application are based on measurements in clean water in the absence of solids and without consideration of physicochemical factors that are known to influence the properties and behavior of practical flotation froths, and hence metallurgical performance. These factors include aquatic chemistry, collectors, modifiers, particle shape and size, and pH. Understanding interactions between these factors and the role and relevance that they play in characterizing frothers and froth zone properties will greatly aid in the frother selection and evaluation process. Such an understanding will also greatly enhance the ability to create frother solutions that are sufficiently robust to plant variability (such as mineralogical, comminution, operational, physical and chemical). This paper reports results of a “systems approach” study designed to probe ways in which physicochemical factors a) influence frothing and bubble size in 2- and 3-phase systems, and b) confound correlation of fundamental measurements with flotation outcome. The concepts and insights gleaned from fundamental frother studies, together with empirical laboratory flotation tests and a thorough understanding of plant needs and challenges were used to develop and implement customized frother formulation at a Cu-Mo flotation plant. Plant metallurgical data and qualitative assessment of froth zone properties showed that a frother formulation developed using the approach described here provided marked improvements in froth characteristics (mineralization, mobility, stability, persistence). These improvements resulted in better circuit control and significant performance advantages, such as improved coarse particle recovery, without detrimental downstream effects. INTRODUCTION Successful recovery of value minerals of sufficient grade via the flotation process requires selective manipulation of the value minerals to render them hydrophobic using collectors and modifiers. The hydrophobized minerals then attach to air bubbles and the mineral-bubble aggregates are selectively transported through the froth zone into the launder. Frothers play a critical role in froth formation and more importantly in achieving and maintaining desirable froth characteristics (for example, stability, mobility, persistence) that are essential in facilitating the selective transport and recovery of value minerals. Fundamentally, frothers contribute to the transient stability of thin liquid films and so aid in reducing bubble coalescence rates in the pulp and froth zones, thus maintaining the small bubbles required for efficient bubble-particle attachment. Invariably, the action of frothers at the liquid/gas interface in the pulp and froth zones impacts bubble stability, water and solids transport to the froth, which in turn impacts froth mobility, froth carrying capacity, and the concentrate grade. Consequently, selection and evaluation of frothers for flotation plants requires careful consideration of the frother type, though the choice is limited to only two main classes of compounds in terms of fundamental chemistry (short chain alcohols and polyglycols). Even with the selection of what is thought to be the best frother for a given application, practical knowledge of the froth zone and experience in controlling its properties is essential for maximizing metallurgical performance.

Jan 1, 2019

By Roland Hunt

This paper deals with the practical problems as sociated with blasting a heated pillar remnant. This pillar remnant was the final stage in the blasting of a multi-stag e pillar blast. Production from the previous stages had produced burning sulphide ore, resulting in high rock temperatures in the final unblasted stage. This is an account of how, under difficult conditions, the pillar remnant was blasted.

Jan 1, 1977

By Robert J. McCarthy

Many technologies have been adopted over the last half century for the haulage of material from open pit mining operations. Some of the technologies utilized include rail, off-highway trucks, conveyors, and slurry pipelines - each having its unique application and benefits. Over time, truck haulage has become the primary means of surface mine material movement, though recently it has been plagued by problems of tire shortages, high diesel fuel costs, labour shortages, and carbon emissions. This paper focuses on In-Pit Crushing and Conveying (IPCC) as a competitor to truck haulage which has the potential to solve many of these problems. An overview of the available technology is presented along with measures required to overcome perceptional if not physical barriers to implementing this technology in modern open pit mines.

May 1, 2011

By W. F. James

"The property of Siscoe Gold Mines, Limited, comprises about 1,600 acres, including Siscoe island and adjacent claims under water in Montigny lake, in Dubuisson and Vassan townships, Quebec.For many years the property was reached by way of Harricana river and its chain of lakes from Amos, Quebec, about 45 miles distant. In later years a highway has been built from Noranda east through Val d'Or, about 5 miles distant.Gold was discovered on one of the claims on the north shore of Montigny lake as early as 1911, but these gold discoveries have never been economically important. Several years later gold was discovered on Siscoe island and considerable surface work was carried out. Still later, iscoe Gold Mines, Limited, was formed and carried out further work, some of it through shallow shafts. In 1928, larger scale operations were undertaken and a 100-ton mill was constructed. In the years following, production· was on a larger scale with lower grade, until finally a milling rate of over 1,000 tons a day was attained. Approximately 1,500,000 tons were treated between the end of 1940 and mid-year 1945. At present the milling rate is down to about 200 tons a day and work is confined chiefly to some of the less important veins that have been recently developed.The following is a summary of production up to December 31st, 1946:"

Jan 1, 1954

By H. J. Rowley

THERE are many varieties of limestone, but for the general purposes of the pulp and paper industry, two classifications are sufficient: (1) High-calcium stone, which should be quite free from impurities and contain not less then 90 per cent calcium carbonate. (2) High-magnesium stone, containing not less than 25 per cent of magnesium carbonate. Before proceeding with detail on the use of limestone and lime in the industry, a few words regarding the pulp products made in Canada are desirable. By far the largest tonnage is made by grinding spruce and balsam logs on rotating sandstones or on artificial abrasive stones of the Norton or Carborundum types. This mechanical or groundwood pulp finds its largest use in the production of newsprint paper, of which it comprises about 80 per cent of the total fibrous substance employed-the remaining 20 per cent being unbleached sulphite pulp. No limestone or lime is directly employed in making groundwood pulp, as contrasted with the chemically prepared pulps, all of which require one or the other form of the base for their processing. Sulphite pulps comprise the next largest tonnage group. They are produced by boiling, under pressure and at elevated temperatures, spruce and balsam wood in chip form in solutions of bisulphites and sulphurous acid. The usual bisulphites employed are those of calcium and magnesium. Sodium, potassium, and ammonium bisulphites give progressively better pulps, but to date, in the absence of efficient recovery methods, cost has precluded their use.

Jan 1, 1939

By Euler De Souza, Kyle Penner

"Booster fans play an important role in assisting main fans by boosting the air pressure of the ventilation air passing through it. The correct placement of underground booster fans in a mine is a critical decision since it not only influences the mine’s operational capacity in terms of costs and efficiency, but also affects safety and environmental conditions. There are many booster fan installations around mines that are inappropriate, in some cases resulting in system failure (fan stall) or in a major negative impact on mine production. Inadequate booster fan placement has resulted, in some cases, in extensive air leakage which has compromised the economics of the operation and, in other cases, in recirculation of contaminants which has seriously compromised safety. This paper provides guidelines for proper design and siting of booster fans underground, to not only achieve an economic ventilation system but to create safe work conditions and efficient atmospheric conditions. Procedures for the planning, installation, operation and maintenance of booster fans are also presented. A case study illustrating the design and siting of a major booster fan installation in a potash mine, supported by computational fluid dynamics analysis, is presented.INTRODUCTIONIn large underground operations with complex ventilation networks offering high resistances, the never ending increased required quantities of air can almost only be supplied through use of high pressure main fan systems. These fans may, in effect, induce significant leakage losses in the system, having a negative impact on safety performance. In such cases, booster fans can be designed to decrease the main fan pressures and reduce the leakage flows, improve system efficiency and reduce costs. In well designed systems, booster fans can thus be used to redistribute the airflow and assist the main surface fans.When the pressure supplied by the main fans is insufficient to meet the ventilation circuit pressure requirements, booster fans are placed in strategic locations where pressure boosting is essential. Booster fans are typically sited in sections of the circuit offering high ventilation resistance and requiring this form of ventilating air motivation. Booster fans are thus required when the mine expands, and so the resistance of the ventilation network, and the primary fans no longer can supply the required pressure and flow."

Jan 1, 2019

By Tom Shumka

INTRODUCTION ?The Electro-Magnetic Crack Detection (EMCD) technique is an electromagnetic inspection method used for detecting and sizing surface breaking flaws. ?It works well on structural material or welds, ferrous or non-ferrous metals. ?EMCD?s rapid scanning is achieved using a hand-held probe. ?EMCD provides reliable crack detection and sizing (length and depth). Cracks can be sized accurately. ?EMCD dramatically reduces most cleaning requirements as there is no need to clean to bare metal. ?EMCD is capable of inspection through thin metallic coatings, or through non-conducting coatings up to 10mm thick. ?EMCD allows full data storage for back-up, off-line view and audit purposes.

Oct 1, 2010

By A. E. Boudreau

It has long been recognized that platinum-group-element (PGE) deposits in layered intrusions preferentially occur in intrusions that crystallized from high-Mg parent magmas. Recent studies suggest that evaluation of any given intrusion for economic PGE potential should also include assessment of the PGE, sulfur and chlorine concentrations in the cumulates and potential parent liquids. PGE: Magmas that contain relatively abundant Pt and Pd are the best candidates for forming economic deposits. Although analyses of coeval sills and dikes are the best indicators of primary magmatic PGE concentrations, analysis of the cumulates themselves is also valuable. For example, within the Stillwater complex, background PGE values in cumulates from the ultramafic sections of the complex contain, on average, several 10s of ppb Pt and Pd. Background concentrations of this order are suggestive that the magma was not depleted in the PGE. Sulfur: Conventional petrogenetic models for the formation of PGE deposits in layered intrusions require the PGE to have been concentrated during a magmatic sulfide-saturation event. In contrast, some hydro thermal models suggest that sulfur and the PGE were mobilized from footwall cumulates by upward-migrating, high-temperature hydrothermal fluids. Both models suggest that significant PGE deposits are likely to occur at and below the level where stratigraphic increases in whole rock sulfur concentrations occur. Chlorine: In both the Stillwater and Bushveld complexes the cumulate sequences below the major PGE-bearing zones contain anomalous Cl-rich apatite. The chlorapatite component of apatite in these rocks may exceed 40% and, in the Stillwater complex, typically exceeds 90%. It is stressed that pristine igneous mineral analysis and not whole rock data be used, as whole rock Cl concentrations may be affected by very localized (grain boundary), low-temperature alteration. Intrusions that crystallized from high-Mg, high-Cl magmas appear to have the best potential to host significant PGE deposits.

Jan 1, 1995

By G. O. Crowell

This paper gives the history of the celestite deposit, now being mined by Kaiser Celestite Mining Ltd., near Sydney, Nova Scotia. Mining and milling procedures are covered, and the regional and local geology of the area are described, including the origin of the celestite.

Jan 1, 1971

By W. S. Urbanski, A. L. Devernoe, R. W. Stuart, M. S. Walker

"Although many investigators have successfully achieved separations using variations of a concept wherein particles are buoyed upwards against gravity in a magnetically attracted fluid, none have succeeded in separating fine particles in a manner that is practical tor mineral beneficiation. This paper describes laboratory tests and preliminary economic analyses for a new mineral separation process which provides enhanced magnetic buoyancy and separation capabilities. The process provides a means of gravity separation in a regime where conventional gravity separation is inadequate; that is for small differences in mineral densities and for very fine particles. Although early interest centers on gravity separation, the process has also been successfully used for precise magnetic separation.Tests were conducted on a variety of mineral mixtures, ore samples and concentrates including; a sphalerite ore, pyrochlore ores and concentrates, cassiterite pre-concentrates, a chromite pre-concentrate, and heavy mineral placer samples. Separations requiring high discrimination between fine particles narrowly different in density or weak magnetic properties were obtained. Of particular interest is the ability of the process to concentrate or remove oxide minerals or gangues, especially silicates. Potential applications are discussed."

Jan 1, 1985

In 2009 Newmont Mining Corporation?s annual global spend on grinding media reached $94M USD, having doubled in the five years since 2004. The major contributing factor to the spend escalation during this period was unit consumable price, with total media consumption also rising as a function of annual ore tonnes milled. In an effort to better understand and manage the growth of this expenditure a significant supply chain management program was implemented. This was complemented by a series of technical initiatives focussed on grinding media specifications, quality management and the prediction of grinding media wear rate as a function of physical ore characteristics. This paper discusses the methodology and outcomes of these activities.

Nov 1, 2011

By Michael J. Lawrence

"The VALMIN Code was developed and formally adopted by The Australasian Institute of Mining and Metallurgy (AusIMM) in 1995 and a revision was issued in 1998. The VALMIN Code applies to all relevant reports under the Australian Corporations Law, including submissions to the Australian Stock Exchange (ASX) and the Australian Securities and Investments Commission (ASIC).The VALMIN Code and Guidelines sets standards for the preparation and commissioning of independent assessment and/or valuation reports on mineral and petroleum assets or mineral and petroleum securities.It is mandatory for AusllvI:M's members to follow this Code in these relevant circumstances and failure to do so will result in serious sanction of the member by the Ausllvllvfs Ethics Committee. Public support for the use of this Code has been given by regulators (ASX/ASIC) and market participants ( eg major accountancy firms). It is also endorsed as a guide to general best practice in project assessment and valuation.This paper will discuss how the VALMIN Code has worked in practice over the past few years. It will also examine areas where the Code could be improved and how it could form the basis of a new Canadian Code for mineral property valuation."

Jan 1, 2003

Deformation is a critical indicator required to evaluate the structural safety, stability, and integrity. For example, the deformed shape of a building structure is a key parameter that needs to be measured and tracked during laboratory testing or post-disaster inspections. However, existing techniques used for the deformation measurement and tracking do not have all the desirable characteristics, such as: reliability, accuracy, low-cost and simplicity of tools installation. In order to address this issue, a novel method has been proposed in this study. The method consists on using the image processing technique to automatically measure and track the deformations of concentrically braced frame (CBF) structures. Accordingly, the critical points in a CBF structure are first identified and the topological configuration of the structure is retrieved. The points and topological configuration characterize the basic shape of the structure. In this way, the deformation of the structure can be determined by measuring and tracking these points and their topological configuration. To show its effectiveness, the proposed method has been tested against the manual deformation measurements.

Aug 1, 2013

By D. G. Cerigo

"INTRODUCTIONAn interim report covering an uncompleted project on revenue mill optimization was presented at the invitation of Mr. C.S. Stevens, the Secretary of the Canadian Gold Metallurgists. The work described summarizes the preliminary work carried out at the Noranda Research Centre on computer mill optimization and is an attempt to arrive at a model of a circuit using the ""black box"" approach and hence by using economic factors related to concentrate dollar value to maximize revenue. The help and cooperation of Mr. J.D. Wild, Mr. M.J.S. Bennett of Noranda and Dr. A. Bobkowicz of McGill University is gratefully acknowledged.DERIVATION OF MODELHistorical data from the Normetal mill were used for the study. Normetal ore contains chalcopyrite, sphalerite, gold, silver, pyrite and pyrrhotite. For simplicity, data were chosen for days when only two concentrates had been derived, a copper concentrate which also contains the gold and silver, and a zinc concentrate. In these periods when pyrite concentrate was not produced, its circuit was used as an extra zinc scavenger unit. Figure I is a schematic drawing of the circuit and Table I explains the nomenclature.The mill had been operated to obtain a fixed grade of copper and zinc in the copper and zinc concentrates respectively, at the same time insuring acceptable recovery levels. The target grade for the copper and zinc concentrates had been derived by manual calculations based on past experience. The data used were 170 sets of daily mill reports, a sample of which is shown in Table II. The data consist of daily tonnages of feed, concentrates and tailings and their average compositions obtained by taking samples every twenty minutes from each stream and analyzing the daily composite samples."

Jan 1, 1967

By Mikael Ramström

In 2002 Atlas Copco Rock Drills AB released the new RCS technology for all of its drill rig types. RCS opened the way for a new generation of computerized drill rigs based on modern, standard PC-computer technology. Drilling accuracy, information logging and reduction in manpower in some types and serviceability, have all taken a quantum leap forward when compared with previous generations of drill rigs. The RCS (Rig Control System) is modularised and distributed is accomplished by means of CAN-bus technology. This technology, which is well proven in automobile applications, forms the communication backbone of the rig. The modularity facilitates almost unlimited possibilities for the expansion and adaptation of drill rig functions.

May 1, 2003