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By Stuart McTavish

"The Brunswick Mining concentrator processes 10,000 D.S. T. per day of a complex sulphide ore. Four separate concentrates- zinc, lead, copper and bulk-are produced by selective flotation. Several major changes have been made to the Brunswick flotation circuit to improve the process and control. This paper will describe the present flotation practices at the Brunswick Concentrator. Special emphasis is given to the conversion of two of the primary circuits to an SO2-aeration flowsheet, and to the addition of a new secondary zinc flotation circuit that produces a zinc concentrate from the plant tailings. IntroductionBrunswick Mining and Smelting Corporation operates a zinclead- copper and silver mine and concentrator near Bathurst, New Brunswick. Since the start-up of operations in 1964, the flotation flowsheet has undergone major modifications to process the increased tonnages and to produce a greater number of concentrates. The flowsheet for the concentrator as it was in 1971 has been described by Neumann and Schnarru) and by Ersklneco. Since then, in 1971, the No.6 concentrator was converted from bulk flotation to selective flotation to produce a copper, lead and zinc concentrate. A separate zinc upgrading circuit was installed in 1972 and a bulk flotation or dezincing circuit, which reduced the zinc in the lead concentrate, was started in 1973. In 1976, the secondary zinc circuit was initiated.In addition to these new circuits, changes have been made to the existing circuits to simplify their operation."

Jan 1, 1980

By K. Chotruangprasert

This paper explores Global Reporting Initiative (GRI) reporting practices within the mining industry. Specifically, this paper investigates how and why a mining company makes voluntary reporting decisions to include the GRI indicators that may be considered ?negative? to the company?s reputation. Due to the voluntary nature of the GRI Guidelines, a GRI adopter is not legally obligated to report every GRI indicator. Not surprisingly, empirical studies that evaluated the extent to which companies? sustainability reports meet the GRI requirements (Guenther, Hoppe, & Poser, 2006; Morhardt, Baird, & Freeman, 2002; Samy, Odemilin, & Bampton, 2010; Skouloudis, Evangelinos, & Kourmousis, 2009) have found that reporting practices of the companies under their studies are well below the standards reflected in the GRI Guidelines. An influential study by Clarkson et al (2008) uses economic-based and socio-political theories to explain variation in companies? environmental disclosure. They have found that, as predicted by economic-based theory, superior environmental performers disclosed more ?hard? (i.e. verifiable) environmental information. Inferior environmental performers are found to disclose more ?soft? (i.e., not easily verifiable) claims, which is consistent with socio-political theories (Clarkson, Li, Richardson, & Vasvari, 2008). However, this study and the existing literature do not adequately explain why a company may act in a way that cannot be explained by economic-based and socio-political theories, for example, why it would report some negative soft data that it is not required to report. This paper intends to address this literature gap. GRI reporting by a Canadian mining company, which I would like to call ?Company C?, is used as a case study for this paper. Company C was selected for this research because in addition to ?positive? information, its GRI-based sustainability report also includes both hard and soft ?negative? information such as grievances. Research methods include interviewing Company C?s employees who are involved in preparing GRI reports and reviewing documents prepared both by the company and by external parties. I find that integrative social contracts theory (ISCT) offers a valuable explanation to Company C?s reporting practices. From the ISCT perspective, Company C?s management appears to feel that the company is obligated under social contracts to be transparent. Therefore, Company C disclosed both positive and negative social and environmental information to the public because the management appeared to think that it is the right thing to do. At the same time, being transparent about the bad news gave the company an opportunity to conclude that it had done something to avoid future occurrence of the negative incidents. Therefore, I propose that, in addition to the economic and socio-political theories that are more often used in literature, insights from ISCT are instrumental in improving our understanding of the corporate non-financial reporting practices phenomenon.

Aug 1, 2013

By D. Ibarra, J. Jacob, A. G. Guezennec, P. d’Hugues, A. Archane

The lack of adequate gas mass transfer is a rate limiting step in many bacterial leaching processes. Oxygen often becomes a limiting factor because of its low solubility compared to the high demand induced by sulfide oxidation. One way of increasing the solubility of oxygen in water or in media solution is by increasing the driving force, i.e. raising the oxygen partial pressure in the gas stream supplied to the leach pulp. The use of oxygen is a well-known practice in high-temperature bioleaching reactors (above 70°C) whereas air is usually preferred in medium and low-temperature operations in order to avoid too high dissolved oxygen concentrations which could impact negatively the bacterial activity. The purpose of this study was to investigate the use of oxygen-enriched gas in bioleaching reactors at 40°C in order to improve the gas transfer in the system when operating at high solid load (20% and more). Bioleaching experiments were performed on a sulfide-rich tailing waste (pyrite 60%, copper 0.8%, cobalt 0.06 %, gold 1 g/t) using the “BRGM-KCC” bacterial consortia. The reactor used for the tests was designed on the basis of a new bioleaching reactor concept developed by Air Liquide, Milton Roy Mixing and the BRGM which uses floating agitators to inject gases and to mix and to suspend solids in the bioleaching solution. Two types of tests were carried out: with air injection and with oxygen enriched gas mix injection. The aim of this work was to confirm the capacity of bacteria to grow and to dissolve pyrite in this type of bioreactors in oxygenrich atmosphere, and to compare sulfides dissolution rates during both types of bioleaching tests. The results obtained show that the use of oxygen enriched gas mix does not decrease bioleaching performances compared to air injection. High metal extraction yields were achieved (above 80%). No deleterious effect due to oxygen use was observed on the bacteria despite the high level of dissolved oxygen reached in oxygen tests (up to 14 mg.L-1).

Jan 1, 2016

By M. Roy, Y. Roux, R. McIvor

"La Compagnie Minière Québec Cartier at Port Cartier. Quebec, utilizes six parallel wet grinding open circuit ball mills to grind iron ore concentrate for the pellet making process. In an attempt to improve grinding efficiency, a mix of 605 25 mm (1 in.) and 405 38 mm (1 ½ in.) grinding balls was charged to mill D while the opposite mix was used in all the other mills. Because media costs were higher for mill D, it was necessary to find out if the smaller balls provided a net economic benefit. Therefore, a test program was undertaken to determine the relative efficiency of the charge in mill D compared to the other grinding mills. Mill F was chosen for comparative efficiency measurements.The first problem was to choose a suitable definition of grinding efficiency. In management's view, previous attempts to quantify milling performance using population balance modelling were ineffective because they were unable to relate breakage rate functions to grinding circuit economical in any meaningful way. Work index analysis was also not favoured because of a number of complicating effects, including the fineness of the feed and product streams and open circuit grinding.It was decided to adopt a recent innovative approach which had been successfully applied to closed-circuit ball milling. For ""functional performance analysis of ball milling"" (McIvor et al., 1990; McIvor et al., 1991), a size criterion is first chosen to define ""fines·' and ~'coarse particles"". In this case 45 microns (325 mesh) was chosen to distinguish fines from coarse material. The relative grinding efficiency of each ball mill environment would then be ~e cumulative grinding (disappearance) rate of coarse (plus 45 nucrons) material per kilowatt hour of energy applied to the coarse material in the mill, divided by the grindability (measured in the laboratory) of the coarse material in the mill feed.Because the disappearance rate of coarse particles is also the production rate of fines, the following equation can be written for the efficiency of the mill environment, Effe, as defined above:"

Jan 1, 1994

By Ronald C. Schimmel

In 2006, the Corus IJmuiden pellet plant produced approximately 4.6 mln tonnes of pellets. Corus IJmuiden is about to increase its pig iron production to 6.4 mln tonne HM per annum. The burden of the Corus IJmuiden blast furnaces consists of approximately 50% high basicity sinter and 50% acid pellets, both produced in-house. To enable an increased iron production, the capacity of the pellet plant needs to be raised to 5.0 mln tonne per annum. The capacity is increased by modifications to the plant layout, which were implemented during the 2006 cold maintenance stop. In addition, the composition of the ore blends is optimised to gain productivity.

May 1, 2007

By Xiao Huang, Dongmei Wang, Prakash Patnaik

Further increase in gas turbine engine temperature necessitates continuous development and advancement to thermal barrier coatings. While tremendous effort has been devoted to developing new thermal barrier coating materials and processing methods in order to decrease the thermal conductivity, limited attention has been paid to radiative thermal transport through coatings. It is the purpose of this study to develop a new layered coating structure that can be used to effectively reduce the both radiative thermal transport as well as thermal conductivity, and to demonstrate the mechanism and effectiveness of the proposed multilayered structure. Mathematical modeling based on the multilayer quarterwave stack and simulation results are presented.

Jan 1, 2004

By A. J. Goodman

Introduction The position of Turner Valley in the foothills of Alberta, some thirty-five miles southwest of Calgary, is too well known to need further description. This attempt to interpret in detail the nature of the structure, and its relationship to neighbouring structures, together with general observations on the foothills belt, is based on work carried out in the office of the Supervisory Mining Engineer, at Calgary. The object in view was the correlation of the mass of evidence which had accumulated from the detailed examination of drill cuttings, and to discover, if possible, its structural significance. Unfortunately it is not possible to publish most of this detail owing to its confidential nature, and in consequence the reader is asked to accept certain statements, which under other circumstances would not be made without supporting evidence. The main argument for the general structural interpretation rests on evidence which has already been made public, and it is possible to proceed to logical conclusions on the main points. The evolution of ideas concerning the structure of Turner Valley is somewhat difficult to follow, as, compared with all that has been said on the subject, there is not a great deal on record.

Jan 1, 1930

By B. Stuckert, P. Sheehan, J. Balfour, B. (Manas) Das, D. Fawcett

"With the growth of large scale surface mining operations, waste disposal and stability of waste dumps pose a challenging problem to engineers. Vibrations due to blasting operations proximal to these dumps further complicates dump design. Many dumps which are statically stable may become unstable due to the effects of blasting vibrations.A joint project between CANMET and Smoky River Coal Ltd. has been initiated to study the dynamic stability of waste dumps. The study involves development of an analytical algorithm combined with field monitoring to assess dump performance.Another objective of the study is to provide baseline data for a vibration attentuation relationships for sedimentary rock (coal) environments: most studies to date are for base metal mines. The effect of dump thickness on vibration response is also addressed.The key objective of the study is to present a methodology for assessing the dynamic stability of waste dumps. Implicit in this methodology are a number of assumptions concerning vibration attenuation in sedimentary rock environments, and response of the dump material to induced vibration. Where possible, these assumptions have been compared with monitoring data as a check on their validity."

Jan 1, 1989

By M. D. Quinn

THE sand and gravel used for backfilling at the Hollinger mine is obtained from deposits in a low range of hills some three miles north of the mine, where the Company owns a number of claims. The material is transported to the mine by aerial tram. Shipments from these deposits to the Hollinger mine commenced in June, 1927, and since May, 1936, sand has been supplied also to the McIntyre mine. During 1942, Hollinger requirements were 1,700 tons per day, and 900 tons per day was delivered to McIntyre. For the past seven years production has averaged 900,000 tons annually, and total deliveries to the end of 1942 were 13,129,022 tons, of which 11,075,339 tons went to Hollinger and 2,053,683 tons to McIntyre. Some years ago, when the original pit was approaching exhaustion, new workings were opened on claims east and south of the tramway terminal. It soon became apparent that the sand varies considerably in character from place to place. The weight per cubic foot was found to range from 85 to 130 lb., and the water percolation rate from 2 to 50 inches per hour. As the mine requirement is a sand with percolation rate of 6 inches or better per hour, it was evident that in certain parts of the deposits the material was not suitable for use as backfill. As a consequence, it was decided to carry out a programme of systematic sampling of the claims in order to select the areas containing suitable material for back-fill and at the same time estimate the tonnage available.

Jan 1, 1944

By J. Gillies

"Those of you who were at last years C.M.P. meeting are aware there was discussion at that meeting concerning the best method of assisting the assayers of metal mines to exchange new ideas and methods of assaying. The opportunity to advise you of what came of that discussion is very much appreciated.There are several societies, including the Chemical Institute of Canada, the Spectroscopy Society and others that could be of some assistance to assayers. However, since these societies cover a rather broad field and not many mine assayers have the opportunity to attend their meetings, it was felt that an organization oriented to the specific needs of the mine assayers would be of more value to them.Several years ago an attempt was made to hold meetings for the benefit of assayers in conjunction with the Conference of Metallurgists held each year by the Metallurgical Society of the C .I.M.M. This did not work because very few of the mine assayers attended the meetings.With the very evident success of the type of meetings the C.M.P. have and the excellent groundwork done by your secretary, Mr. Stevens, in talking about this to mine management and assayers at many mines across the country, it was decided to hold a meeting at Noranda on October 8 to discuss how best we could help ourselves solve our problems.For the initial meeting it was felt that perhaps it would be better to start with a smaller group, so invitations were sent to mines in Ontario and Quebec that were geographically fairly close to Noranda."

Jan 1, 1970

By R. C. Snider

The Roy Lloyd Mine in northern Saskatchewan is a high-grade underground gold mine which is currently supplying ore to Golden Band Resources Inc. (Golden Band)?s Jolu mill. Prior to the operation of the mine, an underground exploration program was conducted intermittently at the site. During both the underground exploration phase and mining, Golden Band has implemented water recycling to reduce freshwater usage within the mine in order to address concerns over the potential for impacts associated with freshwater usage and to reduce the volume of effluent discharged from the site. Golden Band initiated an underground exploration program at the Roy Lloyd Mine site (formerly called the Bingo Project) in October 2007 to better delineate the mineralization of the Bingo gold deposit. The exploration program provided geological information required in order to improve the confidence level of the geological resource model and also provided information to aid in the mining of the deposit, such as the determination of groundwater inflow rates. Underground production mining started in March 2011. This paper provides an overview of the mine water recycling methods implemented at the site during both the exploration and initial mining phases of the project, and the success/drawbacks of these measures to date, including the potential cost savings in the form of reduced treatment and monitoring costs inherent in a reduction of the volume of effluent discharged from the site. The paper will also discuss options that are currently being evaluated in order to further assist Golden Band?s ability to recycle water and reduce the volume of effluent discharged to the environment, while ensuring effluent discharged from the site to the environment meets criteria.

Nov 1, 2011

By Simon C. Dominy, Alwyn E. Annels, Mark A. Noppé

Abstract - Mineral Resources and their subsequent conversion to Ore Reserves are of key importance to mining companies. Their reliable estimation is critical to both the confidence in a feasibility study, and also to the day-to-day operation of a mine. Together with sampling, assaying, geological and other errors introduced during interpretation and estimation, additional errors are likely to be introduced during the application of technical and economic parameters used for conversion of resources to reserves. There is thus a requirement for high-quality interpretation and estimation to be supported by high-quality data. Any company expecting to make sound investment or operational decisions must base this on both relevant and reliable information. An Ore Reserve statement generally contains a single set of grade and tonnage figures without a discussion of the potential inherent errors in these estimates. Some sensitivity studies may be run, but confidence limits are rarely quoted and, if they are, often do not take into account many of the factors that cause uncertainty in the grade and tonnage estimates. Mineral Resource and Ore Reserve estimates thus carry certain errors leading to uncertainty and risk; some of these are unquantifiable for various reasons, for which the operator should be aware. This paper presents a review of the potential sources of error that might occur during a resource estimation program, which are carried through into the reserve estimate. A number of methods are discussed that allow the estimator to be more transparent about the inherent risks in his/her estimate. Emphasis is placed on data quality, and the requirement for strong quality management to be linked to continuous improvement.

Jan 1, 2002

By L. D. Smith

"Those who submit competing proposals for projects seek to present senior management with complete and fully supported material that will not fail under questioning. Hopefully, misleading notions and omissions will have been minimized and there will have been testing of the assumptions regarding the economic, social and political environments.A capital project evaluation team can do management and itself a service by including a sound approach to the impact of inflation (and its twin problem, interest) on a project and a great disservice with an inappropriate approach to inflation.InflationHandled deftly, inflation can alter a project evaluation to show almost any result the handler desires. It must be a constant source of frustration for design people and cost estimators to spend weeks perfecting the technical aspects of a project in order to minimize costs, only to have all of their efforts set awash in a sea of financial and economic assumptions that submerge all of the detail. In all of this, inflation is perhaps the largest offender, with inflation criteria often being brought to bear at the last minute, almost as an afterthought. Perhaps this tardiness reflects the difficulty of the subject and the belief that senior management will take its own approach to the problems of inflation. Such a belief is unfair to senior management, for it is entitled to not being misled by omission. It is entitled to the full use of the skills of the evaluating team, including reasonable assumptions of the impact of inflation.Working in a consulting context, one has the opportunity to participate in the evaluation of a large number of projects."

Jan 1, 1990

By C. D. Smith

Numerous studies have shown the potential of air rate profiling to significantly improve the flotation performance of a bank of cells. To date many profiles have been implemented; balanced, increasing, decreasing and combinations of these. Previous work has typically shown using an increasing air rate profile, where the air rates are increased proportionally to each cell down the bank, yields a higher grade for a given recovery compared to other profiles. Air rate profiling can then be thought of as having two distinct components; determining the correct distribution of a given volume of air and, perhaps more importantly determining the correct total volume of air to add to the bank. To date no method for this second component has been established. In an alternative technique the air rate to each cell is adjusted in order to optimise the air recovery from that cell. Air recovery is the fraction of the inlet air which overflows the weir of a cell as unburst bubbles. The peak in air recovery (PAR) is a robust measurement that indicates optimal performance for the operating conditions in the cell, and sets the PAR air rate. By doing this for each cell in the bank, the optimal total air rate to the bank and the optimal distribution of that air can be simultaneously determined. In this study plant trials evaluated different air rate profiles, and profiling based on PAR. The total air rates to the bank for all profiles tested were approximately equal, allowing direct comparison. The results showed that the highest cumulative mineral recovery was achieved by operating at air rates which gave the PAR for each cell down the bank. Different distributions of the same total air rate to the bank gave the same cumulative upgrade ratio, but lower cumulative recoveries. In this study, the increase in cumulative mineral recovery, at the same upgrade ratio, was more than 33%. Peak in air recovery (PAR) based optimisation of air rates to banks of cells and to the individual cells has been shown to significantly improve flotation performance as it simultaneously determines the optimal air rate to the bank, and the optimal distribution of that air.

Jan 1, 2009

By H. H. Wober, P. J. Morgan

"The proposed classification of ore reserves based on geostatistical and economic parameters is designed to be used as a communication tool to identify for investors, bankers, and financial analysts the degree of risk associated with a specific class of ore reserves. The class designation identifies the degree of accuracy of the estimates for tonnage and grade of annual production volumes of ore. It thus enables decision makers to quantify the risks and uncertainties inherent to the ore reserve in achieving over-all economic goals and annual financial objectives.IntroductionDuring the evaluation, in 1980, of the Creede silver deposit in Colorado, U.S.A., as a potential bulk mining project, the authors were faced with the problem of conveying to senior management the risks and uncertainties that are implied by using common or conventional classification systems to categorize ""ore reserves"". The estimated numbers for tonnages and grade of the projected ore reserves represented the only entry for future revenue from the project. It was, therefore, necessary to convey to management the level of risk associated with those numbers when implementing further stages of development, and to convey what impact significant differences would have on the profitability of the project. The desire to quantify these risks led to a revised definition of ""ore"" and to a re-examination of the classification system of ""ore reserves"". Traditional methods for estimating tonnage and grade of reserves do not include a quantification of the errors of these estimates. The advent of geostatistical methods made this quantification possible. The proper application of geostatistical methods, with adequate geological input and a reliable set of sample data, is essential to its validity.Others have proposed a classification of ore reserves based on geostatistical parameters. Diehl and David (1982) recognized ""that concepts of proven, probable and possible have to be linked to the production rate or time horizon"". Royle (1977) had also addressed this problem. Forsyth (1987) pointed out that bankers are concerned with ""the probability that the variability will fall within a certain degree of accuracy"" especially for grade estimates, and would like to see grades expressed together with the error of the estimate at the 950Jo confidence level."

Jan 1, 1993

By Karim Ramji

The extractive sector today faces growing social, legal and political risks (SLPs) from so many different stakeholders including national and local governments, name and shame groups, civil society and environmental groups, and the ?Occupy? movement. Beyond these stakeholders, there are the indigenous peoples who have growing legal, social, political and economic influence which can often determine the outcome of the Project. The development curve in the extractive sector from initial exploration to mine start-up has become longer, steeper and more risky and expensive as these SLPs have grown in scope and complexity. Even if a project is permitted or starts commercial production, its ongoing development and operations are also facing these SLPs. The continuous assessment of these SLPs and the strategy to mitigate for them has now become critical for every project in the extractive sector. A project will only be successful if it is able to obtain the legal permits to operate, then withstand any judicial reviews, and then also to be able to gain and maintain the Social License to Operate (SLO). Stakeholder identification, management and engagement are key risk-mitigation tools. This paper focuses on the growing influence that indigenous peoples are now enjoying and the impacts on the extractive sector. Indigenous peoples are a unique stakeholder group because their legal rights and interests to lands and resources, their aboriginal title and rights, are gaining more recognition. When indigenous peoples form alliances with other stakeholders, this simply adds to their growing momentum and leverage, and this can become a daunting challenge for the extractive sector. More due diligence is required by companies to understand and assess the challenges posed by operating in areas claimed by indigenous peoples. There is a real need for mining companies to develop an effective indigenous engagement strategy to address these challenges in order to successfully convert risks into opportunities. Early identification and engagement with the indigenous peoples is required and the goal should be to conclude an Impact Benefits Agreement (IBA) with the affected indigenous peoples. The real objective must be to develop a real and transparent relationship between the company and the indigenous peoples so as to gain and maintain the SLO.

Aug 1, 2013

By Karl J. C. Harries

This paper looks briefly at some of the agreements and types of royalties that may be met during exploration activities, but does not go into details relating to them. Agreements can either make or break a deal or relationship. A well drafted, comprehensive and fair agreement can create good relations and trust among the parties and will go a long way towards making a deal work. In the best of all worlds the agreement will be put away and not need to be referred to after it has been signed (but it will be there if needed to sort out potential problems). On the other hand, a poorly drafted agreement or one that is inappropriate to the circumstances or unfair to one of the parties can break a deal and end up with the parties facing each other in that expensive, unproductive and time-consuming occupation ? a lawsuit. Accordingly, it is advisable to involve professional advisers with any agreement. The straightforward one may involve no more that a read through whereas the more complex agreement will require considerable involvement. There is, however, one rule for every explorationist to remember: a professional adviser is only an adviser. His responsibility is to make sure that you have the necessary information to make a reasoned decision but the decision is yours, not the adviser?s. It is your deal, you are going to have to live with it, and it is inappropriate for an adviser to introduce new concepts or amend negotiated ones without your specific instructions. Mineral exploration agreements, although basically option, acquisition and joint participation agreements, come in all the shapes and forms, appropriate to give effect to the endless variety of deals negotiated by the ever-active minds of explorationists. You will note the reference to "joint participation agreements" rather than "joint venture agreements". The latter term was purposely avoided because, with the current activity of explorationists from common law jurisdictions in civil law jurisdictions, it has become necessary for the explorationist to become familiar with corporations and shareholders agreements. As most of you are no doubt aware, under the civil law system a joint venture is normally not recognized as a legal entity and, therefore, joint participation in projects is usually by way of corporations.

May 1, 2003

By K. Thuro, H. Käsling, F. Menschik

"With increasing data volume, due to enhancing requirements for ground investigation programs for large construction projects, the demand for more efficient filing systems is more and more growing. Depending on the project we also have to use flexible systems to cope with varying data out of different lab and field tests.The chair for Engineering Geology at TUM is developing a web-based database solution to handle all project relevant data in a more appropriate way. We aim to optimize our data management to achieve a fast and easy way of collecting, documenting and analyzing our gained data. The second objective is to provide an easy access to our data for project partners across broadly distributed locations.This Database system consists of a PHP web interface and a MySQL database core. The current setup allows an online access via Internet (www). We are able to grant and constrain access to all data or only arrays of data with our user management system to guarantee the safety of project data and respect all rights and proprietorship. The database system is of modular design and consists of the following three base modules: module of general project data, module of laboratory data and user management module. At the current stage we are able to save and work with all usually generated specific values from unconfined compressive strength tests, brazilian tensile strength tests, point load tests, CERCHAR and LCPC abrasivity tests and ultrasonic tests. The user is able to perform a simple statistical analysis within our database (e.g. average calculation of one sample) and export data as csv or xls files for further analysis.For specific questions within projects we are able to deploy and integrate further modules in our database system. At this moment, we are developing an add on to use this database for different drill test analyses. One of the tools correlates drilling performance and drill head wear measured in the field with rock mechanical properties, and extrapolates the data to estimate the performance and wear in new projects. Today we are managing 90 projects with 550 samples and almost 1350 lab tests with the base module.In our contribution we aim to demonstrate an efficient way of data structuring using a relational database for laboratory and field testing data."

Jan 1, 2015

By R. D. Livingstone

"THE LETHBRIDGE COAL FIELD lies mainly .to the north and west of the city of Lethbridge. Mining carried on in this area for over eighty years until 1965. Before the building of a railway the coal was carried by bullock wagon to Montana for use in smelting, and for a while by river boat to Medicine Hat for railway use. The single, almost flat, worked seam is designated the ""Galt"" seam and is about 1.5 metres thick. It belongs to the Belly River formation and is under cover of 80 to 180 metres of weakly stratified sediments. A complex system of cross faults adds to the mining difficulties. Close timbering required in the entries and rooms reflected in a high timber cost and lower output per man shift. The coal is High Volatile"" C"" bituminous in rank with maximum gross calorific value of 11,200 Btu per pound and with a well defined cleavage. Roof conditions in the field range from very tender and very heavy on the south end of the field and west of the Oldman River to a more stable character to the north. Relatively speaking, the whole field would earn a rather tender rating and definitely so in relation to many U.S. fields. Floor conditions are characterized by a bentonitic type heaving in the south end of the field west of the Oldman river to a more stable situation in the north, which can tolerate shuttle car operation if kept drained. Water problems are minimal, except paralleling the Oldman River, where the seam dips below the river level. While vigilance is necessary to prevent accumulations of gas, the volume is rather limited. The seam was entered by shafts, except where small mines were located along the Oldman river banks and gained access by drifts. The coal seam was developed by driving either 3 or 4 Face entries 2 1/2 metres (8 ft) wide on 18-metre ( 60-ft) centres. Sets of dual butt entries driven at right angles to the Face entries completed development work. Normally rooms up to 8 metres wide were turned off the butt entries on up to 11 - metre centres. These were worked in groups of three to five, depending on the roof conditions, and normally advanced 60 m (200 ft). In some areas rooms had to be abandoned short of their objectives due to roof pressure, heaving floor and intermittent work."

Jan 1, 1985

By P. Radziszewski

Industrial practice in mineral processing shows that an important problem in understanding and monitoring in-mill parameters is due to the lack of fundamental knowledge and appropriate sensors. With the development and growing use of DEM charge motion simulators for mill optimisation and design, it is possible to describe the fundamentals of grinding mill behaviour, in improving the understanding of internal grinding mill dynamics and in developing solutions to industrial practice. The main challenge to bringing this DEM technology to the mill operator however was the need for substantial computing power and time. However, what about a simplified DEM charge motion model running in real-time? What about the use of sensor technologies to correct any possible drift in simulator prediction? Could such a technological system be used to predict mill performance and eventually be used for mill control and optimisation? Some of these questions are answered with the development of an "on-line" DEM charge motion simulator package (SAGTools?) along with that of a number of sensor technologies (liner wear, acoustic, instrumented ball) that can contribute to simulator precision. With the objective of bringing this modelling and sensor technology into the concentrator control room to assist operators, this paper aims to describe the main elements of this emerging and developing technology and discuss how it can lead to online mill performance prediction and eventual control.

Jan 1, 2007