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By D. Brand

"The risk management objective of the AMIRA Code of Practice for Metal Accounting has seldom been systematically investigated in the literature up to the authors’ knowledge. Risk is defined in the Australian Standard on Risk Management (AS/NZS 4360:2004), as “the chance of something happening that will have an impact on objectives”. The simplified economic analysis performed in this paper has lead to define “something happening” as measurement non-representativity and “impact on objectives” as NSR loss from the optimal NSR. This has pinpointed a missing link being the establishment of a relation between NSR in flotation plants and measurement representativity. The proposed framework, referred to as the total cost of representativity, answers the previously unanswered question of how much accuracy/reproducibility is fit for purpose in a given flotation plant. Authors readily acknowledge that it is way easier to assess the cost of accuracy/reproducibility than the cost of inaccuracy/irreproducibility. However, this exercise not only answers previously unanswered questions but also establishes an essential link with operational excellence. This paper exposes why such operational excellence could neither be attained nor proved without a state of the art metal accounting system. This should impact not only how metal accounting systems are audited/designed/refactored, but also how flotation plants are designed.IntroductionBecause representative metal accounting is a vital source of information for the financial accounts of a mining/metallurgical company, the need for a code on metal accounting was recognized in 2001 and a team was formed in 2003, under the sponsorship of several major mining houses, to produce such a code. Table 1 exposes the two main objectives of this AMIRA Code of Practice for Metal Accounting."

Jan 1, 2017

By H. Hejny

Economy needs mineral raw materials in almost each sector of modern life. They can only be provided by mining activities. An increasing share of the total mining production will be by underground mining. The mineral deposits will be found at gradually greater depths, including all problems associated with them. It involves an increase in overburden pressure with subsequent rock stability problems and risks of structural collapse. There is a need for new and safe technologies for almost all parts of a modern mine. The mining industry faces a number of challenges which require technical solutions that encompass the entire network and include the economic, social and environmental issues. The industry needs a new image based on pioneering solutions and a modern structure that can exploit minerals at greater depths and promote both high productivity and safe working conditions. Funding has been secured from the European Commission for the I²Mine project. Work started in November, 2011. This initiative is designed to focus on the technological challenges that the mining industry is currently facing including the exploitation of ever deeper deposits and the aspiration for an invisible, safe, zero impact mine. The project comprises a consortium of 27 organisations from 10 European countries. I²Mine marks the start of a series of development activities aimed at realising the concept of an invisible, zero impact, deep mine. The extractive sector, still seen as being old fashioned and environmentally unfriendly, will show that mineral extraction and processing can be done in a highly innovative and sustainable manner with low impact underground and zero impact above ground. The concept of I²Mine is to develop innovative methods, technologies, machines and equipment necessary for the efficient exploitation of minerals and disposal of waste, all of which will be carried out underground. This will dramatically reduce the volume of surface transportation of both minerals and waste, minimising above ground installations and reducing the environmental impact. New eco-efficient technologies will be applied in order to make the entire mining process more efficient and environmentally sound. The concept is for an integrated mine, with the majority of the installations underground, and only the final product will be transported above ground to be shipped to the customer. Production waste will be treated and stored underground and gaseous emissions will be managed underground as far as practical. I²Mine will also focus on ideas and concepts that increase energy efficiency and decrease waste. The core of the project will be to develop breakthrough technologies for autonomous, highly selective, continuous mineral extraction processes and machinery based on new sensor technologies, face front separation as well as innovative concepts for mass flow management and transportation integrating state of the art technologies. The concept of an invisible, zero impact mine requires a refined process underground that selectively extracts the mineral thereby reducing waste. For this reason, improved extraction machines and near to face processing methods, including backfill procedures, need to be developed. These developments include rock mechanics and ground control solutions, incorporating health, safety and environmental issues.

Aug 1, 2013

By N. Aslin, G. Heferen, H. DeWaal

"Mount Isa Mines (MIM) acquired a reputation for the successful application of R&D to develop break-through technologies for the mining industry starting in the 1978’s through until the early 2000’s. The ISAPROCESSTM tank-house technology has been licensed to copper refineries throughout the world, and a significant per cent of the world’s copper is refined using this technology. Since development in the late 1980’s more than 20 ISASMELTTM copper and lead smelting furnaces are now installed in countries around the world. Jameson Cell flotation technology developed jointly by Mount Isa Mines and Professor Graeme Jameson is widely used in the Australian coal mining industry and increasingly in the base-metal and gold industry. The IsaMillTM’s developed at Mount Isa and McArthur River made it possible to develop the McArthur River and George Fisher orebodies and has been successfully implemented into base metal fine grinding applications around the world. The most recent commercialised innovation is the atmospheric leach Albion ProcessTM with its supersonic HyperSpargeTM gas sparger, is being adopted as a solution to the increasing complexity of orebodies. MIM’s contribution to the industry was significant given the size and the remote location of its operations with Townsville Copper Refineries more than 1350 km and Mount Isa 1800 km from the nearest state capital of Brisbane. This paper will briefly discuss the development of each of these technologies and why MIM – now owned by Glencore - was so successful innovating and developing such technologies over a period of nearly 40 years.INTRODUCTION Mount Isa is located in the Gulf Country region of Queensland about 1800 kilometers North West of Brisbane (see Figure 1). It came into existence because of the world class mineral deposits found in the area. In 1923 the orebody containing lead, zinc and silver was discovered by the miner John Campbell Miles. Mount Isa Mines Limited (MIM) was founded in 1924 to develop the minerals discovered by Miles, but production did not begin until May 1931. It paid its first dividend in 1947 after 16 years of troubled production. In 1954 the 1100 copper orebody was discovered and with rapidly rising reserves during the 1950’s and 1960’s led to the construction of new concentrators to treat lead/zinc/silver ores in 1966 (#2 concentrator) and copper ore’s in 1973 (#4 concentrator). The difficult nature of the Mount Isa lead-zinc orebodies has meant that the company had always needed to be at the forefront of mining technology. In the 1970’s through to the 1990’s, it became a world leader in developing new mining techniques and processing technologies as a response to declining metal prices and rising costs. Mount Isa has been smelting copper since 1953 and lead since the early 1930’s. Copper Refining at Mount Isa’s fully owned subsidiary of Copper Refineries Proprietary Limited (CRL) had commenced operations in 1959."

Jan 1, 2018

By M. C. Pietrobon

"A common problem in assessing the applicability of laboratory flotation data is determining how closely conditions during laboratory testing of the ore matches those that occur in a plant. Typical laboratory based investigations do not consider factors such as water quality, pulp temperature and the pulp chemical environment during both grinding and conditioning on laboratory flotation performance. Disregarding these important factors may seriously compromise the validity of conclusions based solely on laboratory experimental results. Furthermore, considering these factors during the flowsheet design stage in the development of new ore resources may reduce financial risk associated with building a new plant. A methodology is described here which embraces these factors in an attempt to bridge the gap between laboratory and plant. The methodology should be considered a vital first step in all laboratory based experimental programs and has implications for fundamental studies on the flotation behaviour of single minerals. This methodology increases the confidence with which findings of laboratory based studies can be transferred to the plant and highlights the effect of variables which may be accessible to manipulation in the plant.Pulp chemical parameters, such as pulp dissolved oxygen demand, pH, Eh, mineral oxidation and solution composition were manipulated in the laboratory by adjusting the duration of gas purging after grinding, the process water input and pulp temperature. A key finding was that matching of the laboratory pulp chemistry to the plant pulp chemistry was dependent upon oxidation after grinding. In turn, mineral oxidation was dependent upon the pH in grinding, water composition and the duration of oxygen purging after grinding. The methodology closely matched the dissolved oxygen demand and surface chemistry of laboratory and plant pulps."

Jan 1, 2002

By Francis Chachula, Niel Erasmus

"In 2002, Titanium Corporation Inc. focused its attention on the development of a process for the recovery of valuable heavy minerals, including zircon and titanium bearing minerals from oil sands froth treatment tailings. The development of a process flowsheet to recover the titanium and zircon minerals from the Athabasca oil sand tailings has evolved through many laboratory, bench and pilot scale iterations.Initial development work focused on so-called ‘beach sand’ material, which is tailings material deposited over a period of time close to the tailings pipe discharge. The derived process flowsheet primarily consisted of gravity concentration stages, which is typical of all mineral sands operations. Titanium Corporation’s business plan calls for the utilization of tailings directly from the tailings pipeline – the process developed around the beach material is therefore risky as it differs from the live tailings in a number of aspects, with the effects on the process unknown. Titanium Corporation successfully obtained an intermediate product through a ‘bulk sampling plant’ coupled directly to an Oil Sands operator’s froth treatment tailings pipeline, during the summer of 2005. Subsequent further processing of this material resulted in poor separation or concentration of the heavy minerals due to a number of reasons. A more effective process flowsheet had to be developed.The newly derived process is basically a marriage between mineral sands technology and oil sands technology that can economically concentrate and recover the heavy minerals and entails the incorporation of a flotation process that takes advantage of the entrained bitumen in the feed to separate the heavy mineral fraction from the quartz gangue This paper will describe the newly derived process as well as the successful results of a subsequent on-site concentrator pilot campaign completed during the 3rd Quarter of 2006."

Jan 1, 2008

Vale Inco?s Coleman Mine 153 Orebody is a narrow vein deposit with a dip that varies from 30 to 70 degrees. It has a strike length of 1200-feet and the current mining extends from the 4250 level to 5100 level. The primary mining method is mechanized cut-and-fill although drift-and-fill is also used in wider sections of the ore zone. The ore body is divided into six main mining horizons with an average of three mining blocks on each cut. There are some interesting rock mechanics challenges related to mining upward from the 4550 level and these challenges are increasing as the mining front progresses toward the 4400 level. The mining of the 4550 block is currently at cut 13 whereby the crown pillar thickness is approximately 60-feet. Significant factors including increased stress levels in the crown pillar, the change in the orebody dip at this level and a recently indentified geological structure in the footwall, have all combined to introduce seismic activity in the footwall of 4550 level. Closer studies revealed a consistent trend of seismicity that was further examined with core logging and Acoustic TeleViewer technology. The data from these assessment tools disclosed a geological structure that is influencing the mining environment. This paper reviews the seismic analysis for the 4550 level mining zone and the subsequent procedures used to locate the new geological structure. The paper also discusses the key mining practices used to successfully mine cut 13 of 4550 level and briefly reviews the studies that are underway to up-date the mine design for continued extraction of high-grade ore in a safe and productive manner.

May 1, 2009

By J. R. Goode

Rare earth elements (REE) and their compounds are critical ingredients in numerous necessities of modern life including: the permanent magnets used in electric motors, generators, speaker and hard drives; high performance automobile tires; catalysts; phosphors; optical glass; etc. World production of REE in 2014 was about 110,000 t with about 98,000 t/a being “Light” (LREE) and the balance “Heavy” (HREE). Unlike other mined commodities, the majority of the LREE produced in the world is a by-product and that from a single iron ore mine in China. The balance of the LREE production comes from four REE-only mines, two in China, one in Australia and one in the USA (now on Care and Maintenance basis). The LREE operations comprise very unusual flotation processes and complex hydrometallurgical plants. In contrast, most of the HREE come from a multitude of small in-situ leach operations exploiting a single, dispersed deposit in China using hydrometallurgy alone. All of the current REE operations produce an intermediate mixed REE product that must be separated to yield the high purity, individual, REE required by the market. This paper describes the processes being used to produce LREE and HREE intermediate products and the separation plants used to make the high purity REE compounds that are key ingredients in the magnets in earbuds, turbines, and automobiles; catalysts used in the production of gasoline, and so on.

Jan 1, 2016

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 Joel T. Werner

Tire costs represent one of the highest controllable costs in open-pit mining, accounting for approximately 10% of mining costs. Tire monitoring technology has evolved rapidly in recent years and is emerging as a viable tool for extending tire life and reducing costs. The majority of the major tire manufacturers and several independent companies are in various stages of developing monitoring systems that capture and store vital tire data. Previously this information had only been accessible when the vehicle passed a fixed point in the mine, or when mine personnel manually downloaded the data. Integrating this technology with a mine management system enables remote collection and management of trend and alarm data. Mine personnel can now monitor a tire?s health parameters at any time, anywhere on site, regardless of the vehicle?s location. Anomalous tire conditions can be detected early and corrective actions taken. This information can then be integrated with other major onboard systems, operating conditions, and geographical information. Tire monitoring no longer exists as a stand-alone technology, but has evolved into an important integrated tool for mine operators. This paper will review the current status and benefits of integrating this emerging technology with a real-time mine management system.

May 1, 2002

By Samuel Frimpong

The interaction of oil sands with a ground articulating pipeline (GAP) system has been simulated with the dynamic model established in this work by combining the multi-body and soil dynamics with the Automatic Dynamic Analysis Mechanical Systems (ADAMS) software. Mathematical models governing the interaction of the GAP system with the oil sand terrain have been modeled based on the theory of multi-body and soil dynamics. These models consist of GAP track-oil sand contact model for generating the contact force between oil sands and track and load-deformation oil sand model for capturing the dynamic behavior of oil sands. A virtual prototype has been created and simulated in the ADAMS environment. The simulation result of the effect of load on oil sand deformation indicates that maximum deformation value increases non-linearly with load varying from 0 to 60t. This study provides a solid foundation for further research and the GAP technology development.

May 1, 2004

By Rodrigo Toro, Mario Delisle, Claudio Zamora

"The mining market is researching innovative methods to train the workforce for mining which is normally extremely difficult to get. Thus, the dynamic simulation-based technologies become an essential pillar to educate and train the inexperienced staff at the pace required by this industry. Even if Operator Training Simulator (OTS) systems are commonly used in most of industries, knowledge transmitted to operators are unfortunately not ""capitalized"" in general. The OTS systems are usually delivered as a single hardware and software platform and very little as a full service long-term.In this article, an integrated solution to increase the efficiency of the operators is proposed. This solution is based on the combination of dynamic simulation, processes knowledge, virtual reality and the knowledge capitalization through the creation of simulation scenarios and e-learning. The Codelco Ministro Hales plant simulation project for a copper concentrator plant is presented as a real life example.IntroductionDynamic and real-time process simulation have proven to be a must in the development of greenfield projects, providing mechanisms to design and test controls design, interlocks, start-up, shut down sequences and operator training, among others (see (McMillan, 2006) for further details). Early adopters of this technology were utility power plants; in the petrochemical industry have become a standard, and in the mining industry the use of dynamic simulations is growing, especially in new projects and training of operations personnel for the adoption of best practices and new technologies, see (Nikkhah & Anderson, 2001) and (Toro, Ortiz, & Yutronic, 2012).This paper outlines a solution that utilizes dynamic simulations as the base of an integrated platform for operational effectiveness, which takes into account the current scenario of new mining projects and operations, where high turn over rates and needs of specialized workforce have given a special value to this kind of technologies."

Jan 1, 2015

By Claude Deveau

"With ever decreasing feed grades, finer mineralogy and increased demand for product, it became obvious that a major step in equipment performance was required to reduce operating costs and increase production. Offsite testwork indicated that a Centrifugal separator was capable of recovering fine tantalum and that the newly developed C Series Falcon concentrator would be capable of replacing many pieces of aging equipment and provide improved performance. Further investigation led to the rental and the purchase of a Falcon C20 concentrator followed by a C10 to maximize circuit performance.Falcon Concentrators Inc’ s practice of working with the customer mirrors Tantalum Mining Corporation of Canada’s (Tanco) philosophy of continuous product development. This synergy honed valve design for continuous operation in a highly abrasive ore environment.Tanco has recently purchased two more Falcon concentrators for the recovery of additional tantalum from its spodumene circuit. These new units have additional user friendly operating features partially based on developments made at Tanco.The Falcon C Series units have enabled Tanco to maximize recovery of tantalum that was otherwise lost while using the original conventional gravity circuit."

Jan 1, 2000

By Dave Rose, Jacques McMullen

"The Detour Lake mine is located 200 km northeast of Timmins, Ontario, Canada.The mill processes a free milling gold ore using both a gravity circuit and leaching with a state-of-the-art carbon-in-pulp circuit. The grinding circuit is a conventional SABC circuit with a tonnage of 55,000 tpd at 95 microns with the addition of pre-crushing upstream of the SAG mill.The Detour Lake mine has one of the largest gyratory crusher in the world (60"" x 113"") and over the years, many improvements have been made to this crusher with the result of improving plant throughput. This paper will present how choke feeding the gyratory crusher has been found to be one of the main influences on crusher product particle size and plant throughput. It will explain how the effect of choke feeding the gyratory was measured and from that, the various changes made to improve choke feeding of the gyratory crusher.IntroductionOre is hauled from the open pit mine and dumped directly into a single 60"" x 113"" primary gyratory crusher. The live capacity of both the feed and discharge hoppers of the gyratory crusher are designed for two (2) truck loads each, assuming a nominal payload of 300 tonnes per truck. The surge bin under the primary crusher feeds an apron feeder that controls the ore feed rate at approximately 4,200 tph onto a 227 metres long x 1.52 metres wide belt conveyor with a nominal capacity of 4,200 tph.The primary crusher is operated at an open side setting of 172 millimetres to produce a F80 feed to the secondary crushing circuit of 135 millimetres."

Jan 1, 2017

By André Desbiens, Jocelyn Bouchard, René del Villar

"The metallurgical performance of the column flotation process is determined by the concentrate grade and recovery. Although the former can be continuously measured using an on-stream analyzer, the latter must be estimated by a material balance calculation based on seldom verified steady-state assumptions. Consequently, the automatic control and optimization of flotation columns should be performed using secondary variables having a strong influence on the metallurgical performance, such as froth depth, gas hold-up or bubble surface area flux and bias. The aim of this paper is to present a model-based automatic control strategy using froth depth and bias measurements obtained from virtual sensors developed at Laval University. Preliminary pilot plant results on two-phase (water– air) and three-phase system (water – minerals – air) will be presented and eventual industrial implementation of such a strategy as well as the possibility of achieving effective real-time optimization from bias and froth depth measurements will also be discussed.INTRODUCTIONFlotation columns have been widely studied and used in mineral processing for about twenty years. Although a great deal of work has been accomplished to understand the influence of different variables such as froth depth (H), bubble surface area flux (Sb) and bias (Jb) on the metallurgical performance, the measurement of some of these variables is still difficult to be performed – except at the laboratory level – because in most cases, no commercial device yet exists.As a result of this, it is almost impossible to achieve neither efficient control nor optimization of the process at the industrial level, even in open-loop operation. This paper aims at presenting a simple control strategy of froth depth and bias. Description of the sensors used to achieved measurements, preliminary pilot plant results for froth depth control, eventual industrial applications and possibilities for process optimization are also treated."

Jan 1, 2003

By Rob Barber

This paper shares the experience of the Alberta Energy and Utilities Board (EUB) Field Surveillance Branch over the past few years in building relationships with Aboriginal communities. Our goal is to provide and encourage best practices that may benefit you and your organization and result in strong, mutually beneficial relationships with a focus on Aboriginal communities. Historical information provides insight that aids in establishing effective working relationships with Aboriginal communities. An important component is appreciation of the perspective of these communities, which is achieved through awareness training. The use of local Aboriginal resource people as part of the training is recommended. A plan that is supported by management and staff is essential and lays the foundation for successful relationships. However, the plan must be flexible enough to change as circumstances warrant. The concept of having local people in communities address local issues is essential. This ?grass roots? approach, combined with the goal of exceeding a community?s expectations with respect to addressing issues, will go a long way to establish trust and credibility. Measuring the effectiveness of this work is the final building block to complete the picture.

May 1, 2004

By Roy McKinstry, Mark Rantapaa, Thomas Bolles

"More efficient drilling and blasting techniques have shown measurable improvements in throughput at the Barrick Goldstrike wet grinding mill.A decrease in throughput at the autoclave, due to increasingly hard ore, was identified in early 2002. A team of individuals from the Open Pit and Process areas participated closely on the Drill-to-Mill (D2M) Continuous Improvement initiative to ensure that it would address the needs of both groups, with the target of improving throughput in future years, despite the projected harder ores. Plant studies were conducted to determine if adjustments to drilling and blasting could positively influence throughput. At the Goldstrike mill the greatest opportunity from the D2M initiative is realized on the hardest ore. Grinding throughput for softer ore, <15 kWh/st, can meet or exceed the downstream pressure oxidation requirements. Grinding throughput for harder ore, >15 kWh/st, is limited by the SAG milling capacity. Better fragmentation in the D2M ore, as demonstrated by image analysis, increased throughput 5% to 10% (25 to 50 stph) compared to the standard mining methods.Better fragmentation and a subsequent increase in mill throughput were achieved through the use of:1) Electronic caps for more precision and flexibility, as well as for allowing extremely fast shots.2) Explosives with a higher velocity of detonation (VOD), to provide for improved shock energy.3) Improved distribution of the explosives by decreasing pattern spacing.INTRODUCTIONThe Barrick Goldstrike Open-Pit group, along with the Process division, began experimenting with novel blasting technology and techniques to improve mill throughput in the spring of 2001. A series of tests were developed to determine if fragmentation and ultimately mill throughput could be influenced by optimizing the drilling and blasting program in known"

Jan 1, 2004

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 K. K. Murray, D. G. Gelderland

"The pressure oxidation autoclave at the Goldcorp’s Red Lake Gold Mines (RLGM) was commissioned in 1991. Since commissioning, the circuit has been well maintained and its capacity increased to mechanical and gaseous oxygen limitations. With advances in available technology, opportunities to produce more sulphide concentrate and a changing business environment, an optimization project has been initiated at RLGM. A multi-phase approach has been developed to optimize both the operations and economics of the circuit. This paper describes the history and future of the autoclave circuit at RLGM.AcknowledmentsWe would like to thank the operations and maintenance staff at Red Lake Gold Mines for their support and openness of mind to enact changes to enhance the operation. We would also like to acknowledge the members of the integrated team from Red Lake maintence, metallurgy, operations and corporate technical services that did the hard work to push past the status quo in order to advance productivity.OpportunityThe Red Lake Gold Mines (RLGM) pressure oxidation (POx) circuit has been in operation for over 25 years processing the high sulphide content gold bearing minerals. Increased sulphide concentrate production from improved flotation recovery and increasing gold sulphide association at depth has led to the POx circuit becoming a throughput bottleneck. The opportunity exists to process increased tonnages of sulphide concentrates and increase gold production. In order to realize this value, it will be necessary to increase the throughput capacity of the POx circuit.BackgroundThe POx autoclave at the RLGM, commissioned in 1991, was Canada’s first gold autoclave. It was installed to replace the two-stage fluid bed roaster that was built when the Campbell mine and mill were constructed in the late Forties. The circuit was originally designed to process 12.5 t/d sulphide sulphur in about 50 t/d of Campbell flotation concentrate. Following the merger of the Campbell and Red Lake Mines in 2006, the POx circuit started processing flotation concentrate from both Campbell and Red Lake Mills. In recent years, the circuit has been processing about 18 t/d sulphide sulphur in 75-85 t/d flotation concentrate."

Jan 1, 2017

By A. G. Doll

"Many power-based grinding models exist, and most operators are familiar with Fred Bond's ""third theory"". Bond's model is most commonly used to describe primary and secondary grinding to product sizes above, for example, 100 µm. Operators sometimes use Bond's equation to describe grinding in situations where it is not appropriate, such as fine grinding below 50 µm. Using an alternative model would be a better choice in this situation.Bond's equation is one in a large family of models. Related equations better suited to fine grinding include the “signature plot”, Von Rittinger's model and Charles' equation. These models have a similar form to Bond's and can be fit to industrial regrind mills and laboratory tests using the simple regression tools in the charts of computer spreadsheets. Operators will find that fine grinding calculations are both easier and more accurate when using the alternative equations to fit their regrind milling surveys or when performing laboratory regrind mill scale-up for plant design.None of these models are new: Charles' equation was published in 1957 and Von Rittinger's model was proposed in 1867. A quick refresh how to apply these equations can turn these oddities from the undergraduate curriculum into useful tools for plant optimization. They can be fit to any type of mill including stirred and tumbling ball mills.IntroductionBuilding a case for fine grind modelling requires reviewing some theory before building a framework for doing fine grinding calculations. The actual calculation procedure recommended is easy and can be applied by plant metallurgists. Don’t be frightened by the theory; the end result is reasonably simple.The observation that mineral breakage is related to the absorption of energy is usually attributed to Von Rittinger (1867). Lynch and Rowland (2005) describe that the ability to empirical test and calibrate energy models of breakage didn’t exist until the widespread adoption of electric motors in the mining industry during the 1930’s and 1949’s. A series of technical papers published by the Allis Chalmers company during the 1940’s demonstrate that they were attempting to do such a calibration using Von Rittinger’s model which is usually stated as: “the energy consumed in the size reduction is proportional to the area of new surface produced.”"

Jan 1, 2017

By Pablo González, Rodolfo Espinosa, Jose-Luis Noyola, Sergio Cossio

"Minera Penmont, at La Herradura, is a joint venture between Industrias Peñoles, S.A. de C.V., and Newmont Mining Corporation. The mine is located in the northern Mexican state of Sonora. La Herradura consists of an open pit mine with two-stage crushing and heap leaching facility, the gold is recovered from the pregnant solution using the Merrill-Crowe process; production began in July 1998. La Herradura produces about 130,000 gold ounces per year, and treatment capacity is 22,000 tonnes/day. Ore mineralization occurs in a shear zone with quartz and native gold. Gold distribution is quite heterogeneous due to the coarse visible gold, in some coarser particles ranging from 100 to 600 microns.Sampling and assaying protocols where established during exploration and prior to starting up operations, based on nomographs developed from early heterogeneity tests. But, as the coarse gold problem became noticeable, it was necessary to develop new sampling protocols to have an acceptable relative standard deviation to control the fundamental error within ± 15%.An experimental program was developed and conducted on a selected ore block made of 195 blastholes; regular ore grade control procedures were applied to both sets of data to evaluate the difference in results between the protocol established prior to starting up operations (“existing”) and the new protocol (“leaching”). In the “existing” protocol, subsampling is done through riffle splitters, and coning and quartering. Fire assaying is used to estimate the gold content, on a 50 g sample. In the “leaching” protocol a 12,000 g sample was bottle rolled cyanide leached, and the leach residue was assayed on a 50 g sample using fire assaying, and a weighted average total gold content was calculated. Currently, a new alternative method is being evaluated, where sub-sampling is done using rotary splitters, and fire assay on a 50 g sample; in this “rotary sampling” protocol and for comparison purposes, gold assays were also repeated using the “leaching” protocol.Test results were compared in three groups < 0.30 g/t (below cut-off), 0.30 to 0.8 g/t, and >0.8 g/t. Overall. Results show that the protocol established prior to starting up operations underestimates the gold assays. Detailed technical results, alternative options, and their implications are discussed in the paper."

Jan 1, 2003