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By Ronald L. Bruening

IBC has developed a cost effective MRT process for the selective extraction and recovery of gold, copper, and a mixture of other base metals from mine leach cyanide solutions. This is a two-stage system in which the gold is first recovered selectively as a high purity salt. The copper is then recovered separately as a sulfate salt. The other base metals are then collected as a cyano anion concentrate. Three different SuperLig® materials are used. The first stage can be used alone on gold leach solutions where copper and other base metals are not a problem. The two or three stage system is used when the base metals build up in the leach solution, resulting in increased costs. The cyanide or cyanide/cyano anion concentrate can be recycled back to the leach solution until the build-up of other salts, etc. becomes too high, or this too can be controlled with a percentage bleed stream.

Oct 1, 2003

By R. D. Lindsay

Pamour Porcupine Mines, Limited has been actively engaged in the ''Custom Tolling'' of Gold-Bearing materials throughout the past decade. Experience acquired in this area was utilized to design and commission a custom gold milling facility at its operations in Timmins, capable of:(a) Accepting a bulk ore test sample at the rate of 150 t/d for crushing, sampling, and metals analysis;(b) Processing gold-bearing ores at a rated capacity of 150 t/d, to produce a goldbearing sulphide concentrate;(c) Processing free milling gold ores at a rated capacity of 80 t/d for total cyanidation;(d) Cyaniding custom gold flotation concentrates at a rated capacity of 80 t/d; and(e) Processing of complex gold/copper or carbonaceous ores, requiring an impurity flotation concentrate separation stage prior to cyanidation, at a rated capacity of 100 t/d.Items considered in the process design and development included:- various gold ore types available for processing;- flowsheet flexibility required;- sampling strategy as related to head grade determination and metals accounting; and- contract considerations.This paper highlights how these various considerations were used to design Pamour's ''Custom Gold Milling Facility''.

Jan 1, 1987

By Gordon E. Agar, Brian Lyons, Gregory H. Styles, William B. Kipkie

"Rock rejection during the flotation of a copper-nickel ore was improved by adding carboxymethyl cellulose to both a rougher and cleaner flotation stage. The selection of the rock depressant was based on laboratory rates studies. Plant operating results are presented which confirm the laboratory selection of two particular brands of carboxymethyl cellulose.The rock assay of the concentrate was reduced from more than 40% to less than 15%.IntroductionThe traditional method of selecting flotation reagents relied upon batch bench scale tests, conducted under arbitrary conditions, to identify the effect of the reagent under examination. Too often these were ""one-off"" tests with little or no regard paid to the reproducibility of the results. Sophisticated researchers used statistical methods to design and evaluate the experiments but they were still obliged to rely on the arbitrary and often unreliable batch tests to generate the numbers that were analyzed statistically. An interesting side-effect of the enhanced sophistication of the statistical analysis was often that no significant effects would be uncovered in a series of experiments that would have generated many positive conclusions and much further experimentation if the same results had been evaluated by the traditional method.In the recent past, at least two groups of researchers a have directed their attention to the reliability of the batch experiments with a view toward improving the reproducibility of the test data. In this work the best of the improvements advocated by both of these groups have been adopted in order to generate kinetic data from batch tests that are as reproducible as possible.The objective of the work was to reduce the rock content of a bulk sulphide concentrate produced at Inco's Shebandowan mill. During 1982 the Shebandowan concentrate analyzed 3.5% Cu, 7.4010 Ni, 25% pyrrhotite and more than 40% rock, which resulted in an MgO content of 10.4%. Besides the expense of shipping all of this rock to Sudbury, the rock also contributed to the poor filterability of the concentrate. On favourable occasions the moisture content of the filter cake was slightly over 20% by weight. The magnesia content of the concentrate was deleterious to the reverberatory furnaces used by Inco for smelting nickel concentrate because the slag viscosity increased as the magnesia content increased, and the nickel lost in the slag went up."

Jan 1, 1987

By John R. Goode

"This paper reviews options for the separation of a mixture of rare earth elements (REE) into its component elements. Earlier separations used selective chemistry such as double salt precipitation and reductive/oxidative processes – methods that still have a place in the industry. Fractional crystallization was developed for more complete separations of adjacent REE. The latter method was replaced by ion exchange (IX), which was in turn replaced by solvent extraction (SX). Two main SX chemistries are in use, solvation and cation exchangers, with several variants (mixed solvents, ionic liquids, etc.) now under investigation. SX plant configurations have evolved including advanced techniques like “hyperlinking”, novel saponification methods, and alternative stripping techniques. The classic mixer-settler is the most commonly employed device although centrifugal contactors have been pilot-tested. Non-dispersive SX options including microfluidic devices and membrane-assisted SX techniques are being developed and could revolutionize the SX option. Other REE separation techniques now being studied include Molecular Recognition Technology (MRT), Free Flow Electrophoresis (FFE), newer IX systems, and electrolytic processes. Additionally, the classical crystallization and selective precipitation methods and newer bacteria-mediated processes, chloride volatilization, high performance liquid chromatography, and magnetic separation systems have been studied. This paper reviews the options and concludes that conventional SX is the technology of choice but viable alternatives could be demonstrated and acceptable within a couple of years.INTRODUCTIONThe chemical properties of the individual REE are very similar which is why REE minerals and ore deposits almost invariably contain a mixture of all fifteen REE, i.e., La to Lu plus Y. That said, the distribution of REE in a given deposit is frequently dominated by the light REE (LREE, i.e., La to Nd). Examples include the Bayan Obo, Mianning, Lynas Mt. Weld, and Molycorp Mountain Pass deposits where heavy REE (HREE – Sm to Lu and Y) typically account for well under 5% of the REE content. The LREE operations produce some HREE but the main sources of these important elements are the ionic clay deposits of Southern China. Importantly, all of the REE recovery operations referenced above, except for cerianite-bearing ionic clay deposits, initially produce a mixed REE precipitate or calcine with a REE distribution similar to that in the ore (Goode, 2016). However, the consumers of the REE, the manufacturers of magnets, phosphors, catalysts, optical glass, etc., require separated products with purities generally ranging from 99% to as high as 99.9999% depending on the element in question and the end use. Hence there is a need to separate the individual REE one from the other. This paper is intended to review the options."

Jan 1, 2016

By Anil K. Beersing

Effective drainage systems are required for reclamation of mine-disturbed areas to control surface water runoff and avoid excessive erosion. For the conventional structural design approach, armouring material necessary to satisfy the design criteria should not move during the design flood event since displacement would uncover the erodible underlying materials. This paper discusses an alternative geomorphic approach for designing drainage channels and watershed landscape. The approach is based on quantitative studies of geomorphic processes operating in a watershed. A design based on the geomorphic approach replicates the configuration, channel regime, sediment volume and hydrology of natural and mature drainage systems. Movement of some armouring material is acceptable in such an approach because the channels are allowed to mature by natural degradation and aggradation, with erosion rates comparable to the natural environment. The key advantages of a geomorphic approach over a purely structural approach include reduced sizes of armouring material, geomorphologically sustainable landscapes, ?walk-away? or maintenance-free design and reduced liability in the future. The geomorphic approach is illustrated using the example of a coal mining operation in northwest U.S.A. The paper discusses field data collection, design criteria, typical design details, and construction methods.

Apr 1, 2005

By Olli Haavisto, Juha Timperi

"Accurate on-line assays of mineral slurries are the basis for effective operation of flotation circuits. Typically the elemental content measurements are obtained by an X-ray fluorescence (XRF) analyzer, which samples the process lines and performs the analysis concurrently line-by-line. For a more frequent measurement of each slurry line the XRF measurements can be complemented with reflectance spectrum information. In reflectance spectroscopy the absorbance properties of the slurry in the visible and near-infrared wavelength range are analyzed. The advantage of reflectance spectroscopy is that measurements can be obtained quickly and simultaneously from several slurry lines. However, since the shape of the spectrum is only indirectly affected by the slurry elemental contents, frequent calibration of the measurement against the XRF analyzer is necessary. This study elaborates the combination of reflectance spectrum analysis with XRF. Results of laboratory tests for different slurries are presented and the operation of the system in a copper-zinc flotation plant is demonstrated.IntroductionElemental analysis of mineral flotation slurries is the most important factor in evaluating the performance of concentration processes. Timely on-line assays are also used as the basis for controlling the circuits and ensuring that the grade and recovery targets are reached. X-ray fluorescence (XRF) is the dominant technology in on-line elemental slurry analysis, and typically centralized XRF analyzers are used. The advantage of a centralized analyzer is that one measurement probe can be used to acquire the data from several slurry lines. This reduces the overall operating cost of the system when compared to distributed analyzer system design with several measurement probes requiring maintenance and spare parts. Slurry samplers are installed in the interesting process flows and representative sample flows are brought to the analyzer, where the slurry is further sampled and measured consecutively by the XRF analyzer. Due to the centralized structure of the analyzers and consecutively measurement of the sampling lines the sampling interval per slurry line can be relatively long. In larger concentration plants with several sampling lines a typical assay interval is in the range of 10-20 minutes."

Jan 1, 2016

By S. Banisi, E. Arghavani, A. Akbari, Gh. A. Parsapour, S. Darvish Tafvizi

The new copper processing plant of the Sarcheshmeh copper complex consists of two parallel circuits. After a primary crushing, the ore is sent to a SAG mill and the product is further ground in a ball mill. The overflow of the hydrocyclones is fed to a flotation circuit which contains 8 rougher tank cells (RCS130), 3 cleaner cells (RCS50), 5 scavenger cells (RCS50) and a 4 x 12 m flotation column as recleaner. The circuit was initially designed to process a feed containing 0.8% Cu, but because of the ore type change, the feed grade decreased to 0.6% Cu. This resulted in a reduction of final concentrate grade and recovery from 28 and 85.5% to 24 and 84.4%, respectively. Based on the original design, the copper and silica recovery in the cleaner cells should be 69 and 55%, respectively, but these values increased to 85 and 75% because of a higher retention time. The rather high silica recovery (i.e., 75%) was found to be the main source of the lower final concentrate grade. In order to reduce the retention time of particles in the cleaner cell from 13.7 to 6.9 min, the rougher concentrates of two parallel circuits were fed to only one cleaner-scavenger and regrind circuit. This modification increased the cleaner and final concentrate grade from 15.1 and 24.5% to 17 and 26%, respectively. To prevent a possible reduction in the copper recovery, the froth depth in the scavenger cells was reduced. The overall outcome of the circuit modification was evaluated to be a 10% reduction in the energy consumption without any loss in the overall copper recovery.

Jan 1, 2016

By Thomas R. Larson

"Many concentrators use re-circulating “plant” water for dilution in their flotation circuits. However, if crusher dust suppressants, ball mill grinding aids, or even agitator bearing grease are introduced into this water, and the water itself is not subject to cleaning steps, then sufficient quantities of these chemicals may appear in the flotation cells and begin to impact the flotation separation. A bench flotation procedure has been coupled with statistical analysis in order to estimate the impact of small quantities of non-flotation chemicals on flotation performance.INTRODUCTIONCleveland Cliffs produces iron oxide pellets for blast furnace feed, and is developing the capability to produce ferrous metallic products to supply a wider customer base. Cliffs manages five North American iron mines, including the Wabush mine sites in Labrador and Quebec. Based on various characteristics of the ore bodies, the flow sheets of the five mines are diverse. For example, Hibbing Taconite uses magnetic separation alone as their primary upgrading method, but Northshore and Empire use magnetic separation followed by flotation, and Tilden uses flotation alone. Last but not least, the Wabush concentrator upgrades primarily with gravity and electrostatic separation techniques.At Northshore, concentrate from the magnetic separator circuit is fed to a reverse flotation circuit. By design, the magnetic separators operate at the highest possible recovery of magnetite, as the separator tails are discarded, and relatively high silica content was acceptable to Northshore’s customers. As the steel-making industry moved toward lower and lower slag volumes, the silica content in the magnetic separator concentrate became a problem. The flotation step was added in the late 1980s in order to decrease the silica assay of the magnetic separator concentrate to meet the current customer requirements. In this setting, the flotation feed stream contains very little silica that occurs as liberated quartz particles. As the degree of liberation of the flotation feed stream is then a limiting factor for silica removal, the online grind control then was linked to flotation in the overall plant control system so that grind can be adjusted to achieve improved liberation if necessary for the flotation process."

Jan 1, 2002

By B. H. Kim

It is hypothesized that the standard approach adopted to characterize the ground and to determine the rock strength properties at depth are flawed and generally tend to underestimate the rock strength and possibly the stiffness, particularly when the rock mass is characterized as massive to moderately jointed or blocky to very blocky. It is therefore necessary to conclusively established that the hypothesis, that the rock strength in highly confined rocks is greater than generally anticipated, is actually valid and generally applicable, and then to develop new procedures to establish rock parameters that can be reliably used for the design of deep excavation.

May 1, 2009

By Fidelis T. Suorineni

The Ashanti mine, located in Obusai, Ghana, West Africa, has been in production for over 100 years, and is currently the second largest single gold producer in Africa. The mine covers a concession area of 434 square kilometers with four main ore types: the quartz vein type, disseminated sulphide type, supergene sulphides and transition ore, and granitoids stock works (visible gold and quartz veinlets). Various mining strategies and methods have been employed for the mining of the narrow-vein ore at Ashanti. In recent years, the mine owner: Ashanti Goldfields Company Ltd. has embarked on a mine-wide expansion program to boost production to a target of one million ounces per annum. With the rapid depletion of its high-grade ore, a suitable mining method was required to produce a high tonnage at low cost to meet production objectives. This paper discusses how the Ashanti mine applied Canada experiences in mining technology to boost production, and the impact that the differing geological settings between the two countries had on the stope performance at the Ashanti operations. Experience developed at the Ashanti mine led to innovative modifications for stope layout and design methods in relatively poor ground conditions.

Oct 1, 2001

By Michel G. Grenier

Compliance with Diesel Particulate Matter (DPM) exposure regulation is currently performed using timeweighted average (TWA) sampling on underground mine workers. These samples are collected in the span of an entire shift and the resulting concentrations are compared to a legislated exposure limit. While this is very useful to determine the exposure level of an individual to DPM, it fails to clearly identify causes of exposure and highlight opportunities that could help reduce the exposure of workers in the course of the work shift. Real-time DPM monitoring measures the worker?s exposure as a function of time and helps identify circumstances where corrective actions can be taken or design changes can be made by the individual or the employer to reduce the overall exposure of the worker and peers. This work focused on obtaining DPM concentrations using a real-time polycyclic aromatic hydrocarbon (PAH) monitor. The aim was to demonstrate that this instrument, while not a direct DPM analyzer, was able to provide a concentration profile that could easily be linearly correlated to standard TWA elemental carbon measurements. In addition, several instances of improvements that could be implemented to reduce the exposure of underground employees were demonstrated.

May 1, 2010

By L. Rodd, C. Walker, T. Koehler

"The energy content of slag represents approximately 80% of the total energy inputs to a laterite nickel electric smelting furnace. Conventional slag handling methods produce only low grade heat and the entire thermal content of the slag is wasted. A heat recovery system proven on BOF slag in the mid 1980's can be adapted to a laterite nickel rotary kiln electric furnace (RKEF) plant. Slag is granulated using a high velocity air jet inside a waste heat boiler to produce slag granules. Granules are cooled during flight via radiation to water-cooled boiler walls and by convection to the granulation air. This system has the potential to recover 80% of the total slag energy in the form of hot air and steam.Integration of the recovered slag energy into the RKEF smelter can be achieved by a number of methods, including the use of preheated air at the ore dryers, kiln or existing power plant. Energy from the slag boiler may be used to reheat boiler feed water from the power plant or to produce superheated steam and generate electricity. The heat recovery system can provide up to 25 - 30% of the total electrical requirement of each RKEF line and a reduction in CO2 emissions of 234,000 tonnes per year.The total cost of slag heat recovery, including CAPEX and OPEX, is $2.5/GJ, which is competitive with using coal when CO2 credits are $18 per tonne. With Clean Development Mechanism (CDM) carbon credits currently selling at €13 ($20 USD) per tonne CO2, there is considerable opportunity for slag producers in regions including South America, Korea, Indonesia and Africa. Increasing fuel costs and more wide-spread legislation for GHG emissions will likely create conditions in which slag heat recovery could generate a favourable return on investment."

Jan 1, 2010

By S. A. H Tyrrell, R. Rotzinger

"Taseko Mines Limited recommenced operation of the Gibraltar copper-molybdenum mine in 2004 and embarked on series of development projects to modernize the mine and increase throughput capacity. The Gibraltar Development Plan 3 (GDP3) project included a second stand-alone copper-molybdenum concentrator, a stand-alone molybdenum separation plant and associated services. Ausenco was contracted to commence the detailed design in 2Q2011, commissioning commenced in 4Q2012 and first ore was processed in 1Q2013. This paper discusses the design, implementation and commissioning of the GDP3 Concentrator.INTRODUCTION The Gibraltar Mine (Gibraltar) property is located in the Cariboo Region of south central British Columbia, approximately 360 kilometers northeast of Vancouver. The site is accessed via an 18 kilometer paved road from the town of McLeese Lake, which is located on the province’s main north-south highway between the cities of Williams Lake and Quesnel. Gibraltar was originally developed by Placer Development and commenced production in 1972. Gibraltar was acquired, while on care and maintenance, by Taseko Mines Limited (Taseko) in 1999 during a period of unusually low metal prices. Taseko recommenced operations at Gibraltar in 2004, and embarked on series of development projects to modernize the mine and increase throughput capacity. The 1972 Gibraltar process flowsheet incorporated two-stage crushing followed by rod and ball milling and flotation. In 2008 Gibraltar completed their first development stage that included the installation of a SAG mill, converting the existing rod mills to ball mills and adding additional flotation capacity. Gibraltar continued development with the installation of an in-pit primary crusher, expansion of the bulk regrind circuit, expansion of the cleaner flotation circuit, replacement of the tailings pumping system and replacement of the concentrate filters and dryer."

Jan 1, 2014

By John Frostiak, Lloyd Buckingham, Kenneth G. Thomas, Luis Wilson

"The El Indio roasting facility associated with El Indio Mine in Central Chile has operated since 1981. It is a facility developed to remove arsenic and antimony from gold bearing enargite/pyrite flotation concentrates.The three installed roasters are Nichols Herreschoff units each with 14 hearths and measuring 4.85 metres diameter. Hearths are rabbled by central shaft driven rabble arms. Product is progressively heated to 750°C under neutral to reducing atmospheric conditions to drive off labile sulphur, arsenic and antimony.Ancillary equipment includes skip hoist feed arrangements, water cooled screw conveyors for transporting and cooling calcine, gas cyclones, post combustion chambers, heat exchangers, electrostatic precipitators, bag houses, gas scrubbers and packaging facilities .Operating practices, history, mineralogy and results are reviewed. The improvements to arsenic and antimony extraction, ambiental conditions and environmental achievements are discussed.INTRODUCTIONHistoryThe El Indio property lies in the El Indio belt, a copper, gold and silver area approximately 175 km long by 10 km wide. The property is located in the Andes Mountains of the central part of Chile at latitude 30"" South and 160 km from the sea-side city of La Serena. Plant location is at 3850 meters above sea level.The property currently consists of two underground mines feeding the El Indio plant and an open pit feeding the newer Tambo leach plant. The property has been controlled by a succession of owners (St. Joe Minerals, Fluor, Bond Gold International and Lac Minerals Ltd.) before acquisition by Barrick Gold Corporation in 1994."

Jan 1, 1999

By A. Mazhary, T. Huff

Sensor-based ore sorting technology is a growing area of interest due to lower-grade ore deposits and higher costs of processing, among other reasons. Among the sensors currently utilized in the particle sorting industry, X-Ray Fluorescence (XRF), as the only sensor with elemental analysis capabilities, has always attracted more attention. Currently, the bench-scale amenability tests for this sensor are performed using hand-held XRF analysers. However, this testing method overestimates the performance of the XRF sorter, and therefore, the results from these tests can be misleading and are often mispresented. The work presented here was conducted on a copper mine and investigates how the sensor’s sensitivity to copper deteriorates under different testing methods. This work compares and correlates the results of an Olympus hand-held XRF analyser, static, and dynamic sorter responses with the actual grades of the rocks. The results confirmed that, the sorter response was extremely prone to blind spots. Furthermore, the results demonstrated that although the static sorter’s responses were comparable in terms of rock identification to those of the hand-held XRF analyzer and assays, the accuracy of the dynamic sorter response deteriorated both as a function of grade of the rocks as well as the potential for blind spots. INTRODUCTION Sensor-based sorting technology has been gaining increasing attention even by larger mining corporations as ore grades decrease, deposits get deeper and therefore cost of mining and processing increases. There are various types of sensors that are currently being used in the particle sorting industry such as X-Ray Transmission (XRT), Color, Electromagnetic (EM), Near-Infrared (NIR) and others. However, none of the sensors are capable of identifying and quantifying particles by the elemental content, except for X-Ray Fluorescence (XRF). XRF is a non-destructive, surficial analytical technique used to measure elemental composition of materials. X-ray fluorescence happens when a secondary x-ray (fluorescence) is released after a sample is bombarded by a primary x-ray source. From a sorting perspective, the most common and expected issues that are associated with XRF sorting are lower throughputs compared to other sensors due to particle presentation limitation as well as the need to wash the material before introducing to the sorter. However, one important issue that is mostly neglected is how the amenability tests are performed and how realistic the obtained results are. Current amenability test procedure utilises a handheld XRF analyser (such as an Olympus InnovX, as used in this work) on multiple, generally 4, sides of the rock and uses the average measured grade as a criterion for separation. While this is a widely accepted technique, it fails to consider some important factors such as exposure time and the distance between the sensor and the particle. These factors can significantly affect the sorting outcome.

Jan 1, 2019

By Steve Massman, Edward Wipf, Gary Beerkircher

"As mine size and tonnage continues to increase, material handling/processing equipment has also increased in size with 400 MT haul trucks, 2000 KW crushers, 12 M SAG/AG mills, 8.5 M ball mills, 3000 M3 flotation cells and 12.5 MW HPGR’s all with planned designs to increase in size further. Related equipment including vibrating screens have also increased in size with screens seeing feed rates of 3000 MTPH. Open circuit SAG Pre-Crush and closed circuit HPGR flowsheets are becoming more common with large screening requirements. Large multi-slope (banana) or horizontal screens are commonly used for these applications, however as the size of these screens has increased, the number and size of the brute force/overhead exciters has increased but with limitations. An example is a SAG discharge screen that will see surges of material from the SAG mill which overload the screen, reducing the screen stroke or throw causing a large reduction in screen efficiency with excessive fines & moisture in the screen oversize feed to the pebble crushing circuit. This paper will present some actual examples of the use of Two-Mass screens as a solution to these overloading problems and the advantages of Two-Mass screens in other high tonnage applications.Brute Force Drive Compared to Two Mass Drive Vibrating ScreensThe standard single mass screen as depicted by figure 1 is generally recognized in the mining industry. It is characterized by the screen body – labeled as the single mass (Mt) that is supported by isolation springs (Kiso). The stroke needed to process material is obtained by incorporating large eccentric wheels and/or drive boxes (Fb) directly mounted to the screen body via a drive tube."

Jan 1, 2017

By John D. Campbell

"IS YOUR MANAGEMENT CONTROLLOOP FUNCTIONINGMineral processors make use of hundreds of control circuits in their mills, process plants, smelters and refineries, to optimize throughput and recovery and minimize cost. This afternoon, I would like to discuss what is probably the weakest circuit in any mineral processing operation - the management control loop.In their recent book ""The Winning Streak"", Goldsmith and Clutter describe extensive research on unsuccessful companies. They conclude that ineffective control, which does not immediately identify the problems, is one of the main failings of unsuccessful companies.We will look at the three key components of control which, from the manager's point of view, ensure that the loop is complete. These three are:• measuring what's happening,• assessing its significance, Rnd• altering performance.If we compare management control to process control as shown in this first figure, ""We see that parameter sensing by the analyzer in a process circuit is analogous to performance monitoring by management in a responsibility centre. The analyzer senses temperature, pressure, flow, weight or some surrogate indicator such as colour to indicate ion concentration. For manage1nent, the performance to rnonitor is dependent upon the objectives of the responsibility centre, and the key factors which affect these objectives."

Jan 1, 1985

By T. Banerjee, D. Felsher, G. Leavoy

"Lake Shore Gold is engaged in commercial gold production at both the Timmins West and Bell Creek mines, located in Timmins, Ontario. Run of mine ore is processed at the Bell Creek mill which consists of a conventional gold mill flow sheet involving crushing, grinding, gravity concentration and carbon-in-leach (CIL) for gold recovery. Since 2009, the operating capacity of the mill has been upgraded from 2000 tpd tonnes per day (tpd) to over 3,000 tpd. The most recent expansion involved the installation of a low aspect ratio SAG mill to replace the secondary crusher. Without operational data on the low aspect mill, combined with a site team that was new to SAG milling, there were many challenges in achieving the target throughput from the circuit. Through the implementation of AwaRE advanced controllers, running in closed loop with PRC fragmentation cameras as well as embedded PARC modules within the Allen Bradley PLC, the site was able to rapidly develop a best operating practise and has been successful in creating a stable and consistent operational environment. The process, lessons learned and eventual solution will be reviewed in this paper.INTRODUCTIONLake Shore Gold is engaged in commercial gold production at both the Timmins West and Bell Creek mines, located in Timmins, Ontario. Run of mine ore is processed at the Bell Creek mill which consists of a conventional gold mill flow sheet involving crushing, grinding, gravity concentration and carbon-in-leach (CIL) for gold recovery. Since 2009, the operating capacity of the mill has been upgraded from 2,000 tpd tonnes per day (tpd) to 3,150 tpd. The most recent expansion involved the installation of a low aspect ratio SAG mill to replace the secondary crusher. This endeavor was split into two phases: the expansion of the back-end (Phase 1) and the front-end (Phase 2) of the mill. Phase 1 of the expansion was completed at the end of 2012 and involved enhancements and capacity addition to the leaching and adsorption circuits, which increased the mill’s capacity to 2,500 tpd. Phase 2 of the expansion commenced at the end of July 2013 and involved the expansion of the crushing and grinding circuits. The expanded front-end of the mill now has a capacity of 5,500 tpd, and processes ore from both Bell Creek and Timmins West mines. The updated flow-sheet, as shown in Figure 1, illustrates the replacement of the two-stage crushing and ball milling circuit with a single stage crusher and a low aspect ratio SAG mill."

Jan 1, 2015

By D. W. Bacon

Plant process optimization programs are often costly, both in technical effort and loss of production. Evolutionary Operation or "EVOP" is a mode of plant operation consisting of controlled cyclical changes in process conditions by which information is provided concerning potential process improvements while both volume and quality uniformity in production are maintained. Its conceptual simplicity and low cost of utilization have led to successful adoption in a variety of industrial manufacturing operations. This paper is an expository account of basic EVOP theory, the problems encountered and the organization required in applying it to a processing plant. Illustrations are provided which indicate the payoff that can result.

Jan 1, 1967

By Donald Leroux, Asim Tuzun, Simon Gariépy, Luc Lachance, Hayley Halsall-Whitney

"The importance of coherent material balance results has long been recognized by mining and metallurgical companies. Although this is still true nowadays, various stakeholders are increasingly concerned about the origin and the accuracy of the reported numbers. The last decade has shown that most metallurgical accounting concerns can be addressed by making two important changes to plant performance monitoring practices. First, introducing data redundancy into the metal balance procedure allows the estimation of measurement errors. Second, the migration from spreadsheet-based to relational database based systems brings transparency, data integrity, traceability and auditability into metallurgical accounting. Relational databases also facilitate the production of reports that metallurgical accountants must issue routinely. Recognizing the caveats of the spreadsheet-based metal accounting method they had been applying for years, Strathcona decided to switch to a commercial relational database system in 2008. For the most part, the migration was seamless. Some challenges were raised but they could all be overcome and outweighed by benefits gained from day-to-day utilization of the system.INTRODUCTION Metal accounting (Morrison, 2008) has always been essential to high-quality corporate governance of mining and metallurgical companies. Although the importance of coherent material balance results has long been recognized, various stakeholders are increasingly inquisitive about how the reported numbers were obtained and how much accuracy can be attributed to them. This accrued scrutiny is obviously no stranger to the corporate governance tightening that happened through the years in response to outrageous accounting scandals. It is also in continuity with securities laws (such as NI-43-101 in Canada) that were passed to protect the public from other market fraud. Recognizing the importance of spotless metal accounting in their reports to the public, a group of global mining companies gave AMIRA International the mandate of developing a set of rigorous yet practical metal accounting guidelines for the mining and metallurgical industry. The AMIRA P754 project was launched in 2004 and the first version of the resulting Code of Practice was released the following year. Since then, the Code was reviewed twice and revised releases were issued (AMIRA, 2007). While some parts of these guidelines are in continuity with current commonplace practices, other parts recommend changes to inherited practices that may be significant. For example, they highlight the importance of data redundancy (Lachance & Flament, 2011) which in many operations is either already available but unexploited or achievable with reasonable efforts. These guidelines also stress the importance of state-of-the-art metal accounting systems, such as those based on relational databases, which are secure and entirely auditable by a Qualified Person. Because most spreadsheet software packages allow data and formulae to be modified at any time, without a trace and anonymously, they do not meet these requirements."

Jan 1, 2012