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By Craig M. Sams

"Variable speed mill popularity has grown during the last 10 years with almost every SAG mill fitted with a variable speed drive. In addition, many of today’s larger ball mills are running a variable speed drive for various reasons. In the past, motor suppliers, especially gearless drive suppliers, have considered mills as being an overpriced rotor. This has lead to mills demanding more torque than what a motor can generate. This paper identifies the reasoning of what has happened and how to mitigate the mismatch in the future. Technical and economical issues are discussed, allowing mill operators to make an informed decision of which path to take in deciding what motor to put on a mill.INTRODUCTIONIt has been generally accepted in the past that motor suppliers and specialists in engineering companies understand the workings of a SAG mill or a ball mill and although there is a fair knowledge within the industry, in regards to mill torque requirements, the advent of variable speed drives in ball mills has shown the writer that a complete understanding of the mill torque requirements are not fully understood.This paper will discuss two aspects of mill torque requirements, (operating torque at various charge levels and start up torque), and how it relates to specifying the proper motor torque requirements.MILL OPERATING TORQUEMill operating torque at a given charge level and density in a mill is essentially constant throughout the entire speed range. For the purpose of this paper, we will take a 38’x 22.5’, 20’ EGL, SAG mill and provide the power draw at variable speeds but fixed loading conditions.The power draw and mill torque of this mill at 8% ball charge and 28% total loading (Highlighted) is shown below as Figure 1, at variable speeds."

Jan 1, 2007

By Walter F. Atkins

Fair market value, in the legal sense , is the price which a prudent and knowledgeable buyer and a prudent and knowledgeable seller, acting without constraint or compulsion , will agree upon to exchange an asset. In the ordinary commercial or engineering usage, the term may imply simply the market value or a reasonable and equitable price. The engineer evaluator who is called upon to express an opinion about the fair market value of an asset may be able to base his estimate on the sale price of similar assets or on the market values of stock. Frequently such indicators of value are not available and the evaluator must devise other means of appraisal. Mineral resource properties may be thought of as having value by virtue of the existing or potential ability to produce at a profit. Conventional procedures permit the computation of the present value of future revenues having due regard for the time value of money and the risks attendant upon the realization of the venture. Such computations have gained wide acceptance as a basis for the estimation of fair market value.

Jan 1, 1977

By J. P. Mogan, E. D. Dainty, A. Lawson

"The toxicity reduction of emissions from two diesel engines by the emulsification of water into fuel oil was investigated to determine the applicability of such systems to underground mining machinery. . The engines studied were: 1) the Deut; F6L7J4, four-stroke, air-cooled, 6-cylinder, V-configuration, indirect-injection (IDl) engine, and 2) the Detroit Deisel Allison Division 8V7JN, two-stroke, water-cooled, 8-cylinder, V-configuration, direct-injection (Dl) engine.The application of emulsified fuel treatment to the two-stroke engine did not prove to be practicable. In the case of the Deutz engine, however, substantial benefit resulted. For a modest J5 per cent water content in the fuel and an injection timing of24° BTDC, approximate reductions of40 per cent in the concentrations of both particulate matter and nitric oxide (NO) were produced. These reductions were accompanied by insignificant changes in other toxic constituents. The net result was an approximate 30 per cent reduction in the over-all exhaust toxicity for typical LHD operation as assessed by the Health Effects Index criterion. This toxicity reduction represents a significant advance from the points of view of an improved underground environment and/or reduced ventilation costs."

Jan 1, 1981

By Zorigtkhuu Davaanyam, Bern Klein, Stefan Nadolski, Amit Kumar

"The High Pressure Grinding Rolls (HPGR) is a relatively new comminution technology that has been shown to be more energy efficient compared to semi-autogeneous (SAG) mills. Full and fair consideration cannot be given to HPGR-based comminution circuits in early stage projects, because presently pilot scale testing is required for assessing and sizing; pilot scale testing requires bulk samples weighing more than one tonne. A CAMIRO research program was conducted at the University of British Columbia to develop bench scale tests that would reduce the quantity of sample required to assess HPGR.Three test procedures were developed.1. The Direct Calibration Methodology calibrates piston press test results to pilot scale test results such that piston press tests can then be used to determine the energy–size reduction relationship for a range of ore types.2. The Database Calibrated Methodology, which is similar to the Direct Calibration Methodology except that it calibrates piston press tests against a database of pilot scale and piston press tests.3. The Semi-Mechanistic Methodology was developed to use piston press test results as an input for an HPGR based energy-size reduction performance model.Through utilization of these methodologies, the energy–size reduction performance of an HPGR can be predicted with minimal sample requirement. In addition, piston press testing is far more cost effective, faster, and accessible than pilot-scale HPGR testing.IntroductionOne could argue that in the future, decisions regarding selection of comminution circuits will be made primarily on the basis of energy consumption. The following facts and predictions support the argument:"

Jan 1, 2015

By G. Couture

"The Glencore Raglan mine Concentrator, located in Quebec’s Nunavik region, has been in operation since 1997. The nickel metallurgical plant was originally designed to process 100 tonnes per hour of ore to produce 130 000 tonnes of nickel concentrate per year at 16% Ni. The increased grinding capacity and the discovery of rich ore bodies have increased the annual production to more than 190 000 tonnes of concentrate at 19% Ni. In 2014, the Metallurgical group, with support from BBA, implemented an expert control system on the flotation circuit. This project was initiated to cope with the high variability of the concentrator’s feed. Increasing the plant recovery and final concentrate grade were also important project objectives. The implementation of the expert system ensures better control of concentrate inventory while maintaining maximum plant throughput. This paper describes the successful implementation of the new control system, the control technology selection and the flotation circuit optimization. It will also discuss the performances obtained with this new approach and the improved process stability.IntroductionThe Raglan Mine is located in Northern Quebec along the 62th parallel. It has been in operation since 1997 and was originally designed to produce 130 000 tonnes of concentrate annually at 16% Ni. The increasing of the grinding capacity and the discovery of rich ore bodies have increased the annual production to more than 190 000 tonnes of concentrate between 18 and 20% Ni."

Jan 1, 2015

By Flavio Rojos-Tapia, Oscar Pereira-Cerda, Samuel Sánchez-Pino, Samuel Sánchez-Baquedano

"Pneumatic flotation was introduced to the Chilean Copper Mining Industry in 1993 by Ingeniería de Minerales S.A. (IDM). The technology is based on the designs of Dr. Rainer Imhof from Germany, who is the designer of several different types of pneumatic flotation cells, already sold through his Company Maelgwyn Mineral Service Limited (MMH). The company is represented by Ingenieria de Minerales S.A. (IDM) in South America.Pneumatic flotation, has been used in tough industrial applications .It has been successfully used for metallic ores such as copper sulphide and oxide minerals, copper slag, silica and silicates from iron magnetic preconcentrate (reverse flotation) and gold. It has also provided promising results when applied to molybdenum flotation. The latest applications, with ultrafine molybdenum particles in operating plants, is showing the V and G Cell (end model designed) as a real technological alternative to conventional flotation., The G Cell is an extremely high speed flotation machine with high selectivity which introduces the possibility of producing a final molybdenum concentrate with only one stage of cleaning. This is a completely new development in molybdenum flotation in the industrial circuit which has the potential to dramatically reduce the circulating load in the cleaning circuit. As a consequence the capital costs of future Molybdenum plants may also be reduced. The suitability of the G Cell will have to be determined on a case by case basis but it provides the metallurgist with an alternate flowsheet for consideration.The good performance of the G Cell can be explained by the high gas hold-up and very effective micro-turbulence which helps improve the attachment of solid particles to the bubbles. This technology may change our traditional concept of residence time in flotation. Additionally, the rotation phenomena introduced in the vessel of the G Cell ,creates radial separation forces which are critical to achieving a more rapid separation of the target minerals from the tailing. This results in a much reduced residence time requirement in the flotation machine. Some benefits associated with the use of the new G Cell are: less energy consumption, less maintenance costs, simple and reliable circuit to operate and a small area required for installing the circuits.As a result of the industrial experience in the Chile, the pneumatic flotation type G Cell can be regarded as a technology which must be considered as a replacement technology for the rougher and cleaner stages for fine particle flotation."

Jan 1, 2008

By Kyle Selga, Christopher J. Greet

"The Pulp Chemistry Monitor (PCM) has been installed and operated in a number of concentrators in Australasia, and has produced some very interesting results. PCM measures the pH, Eh, dissolved oxygen, temperature and oxygen demand of process streams within a concentrator continuously and in real time.In the example presented in the paper the cleaner feed pulp chemistry is measured, and related back to changes in the mineralogy as well as variations in metallurgical response. For example, a decrease in Eh and dissolved oxygen as well as an increase in the oxygen demand. These changes in the pulp chemistry appear to coincide with increases in the feed grades, probably higher pyrite grades. Further, these variations in pulp chemistry and feed mineralogy have a negative impact on the concentrate grade and recovery.The implication is that if the pulp chemistry is monitored it is possible to predict changes in the mineralogy of the system, and from this the metallurgical response. Further, the changes in pulp chemistry can be used in a control system to counter the changes in mineralogy and maintain the metallurgy.IntroductionIt has long been recognized at a fundamental level that the flotation behaviour of sulphide minerals is dependent on the pH and Eh of the system (for example: Tolun and Kitchener, 1964; Woods, 1976). However, measuring pulp chemical parameters within an operating concentrator has had limited attention. Woodcock and Jones (1970a and b) were among the first to actually collect data from operating plants. Jones and Woodcock (1984) identified some of the chemical complexities of flotation pulps, and noted that most concentrators already operate at high levels of metallurgical performance but there was still considerable scope for improvement. These gains would, in part come from more effective chemical control. In the same volume, Healy (1984) discussed metal ion hydrolysis and precipitation, redox chemistry and how the surface chemistry of sulphide minerals can be influence flotation behaviour. The impact of grinding environment on the pulp chemistry and flotation response of a complex polymetallic sulphide ore is discussed by Forssberg and Subrahmanyam (1993). Their work essentially contrasts the pulp chemical and flotation performance of pulps ground with conventional ferrous grinding media to a fully autogenous system. The data suggested that the reduction or removal of iron hydrolysis contamination from the system could have a positive influence on flotation behaviour, and perhaps the first stage of “controlling” the chemistry of the system should be in the grinding circuit. Grano et al (1995) demonstrated that the collection of pulp, solution and surface chemical data could identify weaknesses within a concentrator, and from these data develop, test and implement solutions that improved the process. Greet et al (2006) showed that the pulp chemical trends observed through primary grinding and rougher flotation circuits of most sulphide flotation concentrators are approximately the same. There are differences in the magnitude of various pulp chemical parameters (pH, Eh, dissolved oxygen, temperature and oxygen demand) as a result of variations in the feed mineralogy and processes employed. Further, it was noted the Eh shifted to more reducing values of the ten days measurements were collected, and this change could be traced to an increase in the iron sulphide content of the feed. Metallurgically, this resulted in an increase in nickel recovery through the recovery of nickeliferous iron sulphides, and a decrease in nickel concentrate grade."

Jan 1, 2016

By Jose R. Hernandez-Aguilar

"Three models to predict the effect of bubble size (Db) on metallurgical response were tested in a pilot-scale flotation column at Teck Highland Valley Copper mine. The column was fed with slurry collected from the Cu/Mo separation circuit. The first model was the one developed by Gorain et al. (1997), which assumes that the collection zone rate constant (kc) is inversely proportional to Db. The second model was the one proposed by Hernandez-Aguilar et al. (2010), which considers kc as an inverse square function of Db. The third model was the one developed by Yoon and Luttrell (1989) which provides expressions to describe the efficiency of particle collection (E) based on first principles. The results showed a significant bias between experimental and predicted data using the model of Gorain et al. (1997), possibly reflecting the model’s inability to explain the impact of bubble size, bubble rise velocity and flow regime on E. The model of Hernandez-Aguilar et al. (2010) well described the experimental evidence. The model of Yoon and Luttrell gave accurate and unbiased predictions. However, Yoon and Luttrell’s approach calls for a criterion to determine whether the flow regime is potential or intermediate, a subject that requires more fundamental research.INTRODUCTIONParticle collection, i.e., bubble-particle collision followed by attachment, is the basis of flotation. In a quiescent environment (such as the one observed in a column, or away from the impeller in a mechanical cell), a collision event can take place as long as the “degree of turbulence” caused by the rising bubble does not prevent particle and bubble to flow in close proximity. Upon collision, the particle slides on the bubble surface for a period of time. If the particle is hydrophobic, attachment occurs when the “sliding time” is longer than the “induction time”, which is the time required to thin and rupture the intervening liquid (usually water) film forming a three-phase contact angle. While the induction time is largely influenced by the degree of hydrophobicity of the particle, the degree of turbulence is governed by the bubble size. Generally, direct control of bubble size is not exercised by most mineral processing practitioners, in spite of its obvious importance. Studies to model the effect of bubble size on particle collection using fundamental approaches have been conducted (e.g., Anfruns and Kitchener, 1977; Webber and Paddock, 1983; Yoon and Luttrell, 1989; Dai et al., 1999). However, these models have been validated under highly idealized laboratory conditions (micro-scale experiments using single minerals and uni-sized bubbles), far from resembling those existing in practical industrial applications. Fundamental studies to interpret the effect of bubble size on particle collection in industrial environments are largely absent in the literature. Partly because of this lack of practical knowledge, many mineral processing practitioners perceive laboratory “bubble size” studies to be valuable academic exercises, but not something that can be directly applied to daily production issues."

Jan 1, 2011

By William D. Macdonald

The Upper Devonian Kettle Point black shale of southern Ontario is poorly exposed. Structural maps pre-pared from the data of numerous wells show that the upper surface of the formation has low regular relief, and that the lower surface reflects domes in the Middle Devonian and also local subsidence of the Devonian rocks due to solution of salt in the Silurian Salina Formation. The appearance of minor amounts. of marcasite, pyrite, and calcite, m that order, as interpreted from the evidence of concretions from the type locality at Kettle Point is thought to have been influenced by a rise m the pH within anaerobic sediments preceding compaction.

Jan 1, 1960

By Luis Castelli, Aldo Bonomelli, Giselle Schifferli, Claudio Zamora

"This paper introduces the operational concept and the description of a multi-site Remote Support Center for knowledge management and long-term process performance improvement.This centralized Support Center provides real-time monitoring of open-platform process automation systems, and on-line access to process data and control applications information for multiple sites.Considering that process automation is a key enabler to business performance improvement, sustaining effective performance benefits over time becomes essential. Unfortunately, changes in manufacturing process dynamics, technology obsolescence and in plant operational practices cause the control strategies to lose their effectiveness over time unless their performance is periodically evaluated, and if required, tuned to the new process conditions.A new concept in process automation is proposed through the addition of a new control loop based on performance analysis methodology which is intended to feedback process and automation operation information to system and process specialists, allowing for continuous manufacturing process improvement and sustainable production benefits through effectual control strategies.A remote support center can play a key role in the delivery of such services, by providing the base platform from which a comprehensive process overview and a centralized knowledge database can be executed and additionally, as an enabler for plant operational practices change.INTRODUCTIONA Benchmark on Automation Level in Copper Concentrators conducted by AMIRA in 2004, reported that the Codelco divisions scored below their peers in several categories.Codelco had thereafter been looking for a new automation concept, and had focused on process automation as a key enabler for process manufacturing and business performance improvement. The final decision was to create a strategic alliance with a world-class automation technology provider.The traditional approach based on isolated automation solutions/projects, showed that the control strategies benefits were decreasing progressively over time, because of the on-going need to adapt the control models to the ever-changing process conditions and different plant operational practices. Another consequence of this traditional approach was the wide variety of technologies and automation systems deployed in the different plant sites, with no common automation standards, and with low opportunities to transfer knowledge or practices."

Jan 1, 2010

By A. E. Soregaroli, H. D. Meade

"The Keystone porphyry molybdenum deposit, located in southcentral British Columbia, is hosted by intrusive rocks of the Cretaceous Mount Lytton batholith and the early Tertiary Keystone quartz diorite stock. The molybdenite mineralization is associated with rhyolite porphyry dikes flanking a large 1300 m by 2100 m breccia complex. Recognition of the potential for the buried molybdenum porphyry system was based on quartz-molybdenite vein fragments within the hydrothermal breccias.The full extent of the molybdenum mineralization is not known. The few deep drill holes along one comer of the breccia complex defines strong metal zoning of molybdenum and associated elements of F, Mn, Zn, Pb, Au, Ag, Fe and W about the molybdenum stockwork mineralization that may be useful for guiding additional exploration. The best mineralization occurred near the base of the deepest drill hole with 0.114% Mo in rhyolite porphyry near the edge of the breccia pipe at a depth of 1350 m.The exploration history of the deposit has been complex, focussing on both porphyry-style mineralization and precious metal veins and stockworks on the periphery of the porphyry system. Exploration to date has defined an attractive porphyry molybdenum system with uneconomic grades at great depth; however, there remains significant potential to define economic mineralization elsewhere in the Keystone porphyry system and adjoining occu""ences."

Jan 1, 1995

By M. Melashvili

"The SART Process was introduced to the gold mining industry in the late 1990s and several commercial plants were built over the following 10 to 15 years. Most of these plants have operated well and enjoyed plant performance in line with expectations based on the underlying chemistry of the process. However, two of the plants have consistently suffered from high reagent consumption and poor product quality, which has motivated a re-examination of the process fundamentals in the hope of understanding the reasons for poor performance when it occurs, and developing mitigating strategies.This testwork along with a review of the relevant literature has demonstrated that the amount of sulphide added to the primary reactor, relative to the copper concentration, is the most critical parameter dictating plant performance, with pH and residence time important secondary factors. The primary product in the SART Process is synthetic chalcocite, Cu2S, and the stoichiometric requirement for sulphide addition is therefore 0.5 moles per mole of copper in solution. Testwork shows that when sulphide is added in excess of this amount (generally with the express purpose of lowering residual copper in solution) it not only fails in its intended purpose, but can have a negative impact on the settling and filtration characteristics of the copper sulphide product, as well as the final product quality. Moreover, these problems are exacerbated the higher the selected operating pH in the pH 3 to 5 range, and the longer the residence time of slurry in this pH range.Freshly precipitated copper sulphide compounds are known to be very fine and slimy, with poor settling and filtration characteristics. It is therefore important to engineer the SART Process in such a way as to encourage growth in the average particle size of the precipitate crystals. This was the rationale for recycling a portion of the thickener underflow to the primary reactor when the SART Process was developed. The theory of crystallization predicts that compounds of extremely low solubility, such as chalcocite (Cu2S: KSP = 10-48), are likely to experience growth in crystal particle size through aggregation rather than heterogeneous nucleation. On this basis, the SART practice of recycling a portion of thickener underflow to the primary reactor in the commercial plants is unlikely to lead to crystal growth via nucleation, and could in fact promote breakage of the aggregates that formed in the thickener. Recycling thickener underflow could therefore have the opposite of the desired outcome. The result of testwork that is reported here lends credence to this theory and questions the wisdom of recycling in the SART process.There is evidence to suggest that operating the copper sulphide thickener in the SART Process without flocculants may be beneficial. Thickener underflow densities could improve from the current 10 - 15% range to 40 - 50%. This will not only reduce the flowrate of slurry to the filter, but the filtration properties of the slurry (filtration rate, filter cake moisture content) will also improve. This is one of the most critical engineering and design aspects of the SART Process, and the achievement of high solids density in the thickener underflow will not only improve the health and safety aspects of the operation, but also has the potential to lower capital costs and improve the quality of the final product."

Jan 1, 2016

By A. Mazhary

"Although ore sorting in mining is not a new concept, sensor-based sorting has failed to gain broad acceptance due to perceived challenges with the technology. In order to gain wider applications, this research focuses on treating waste rock and low-grade ore to identify and test appropriate sensors and to evaluate the response. Results showed that amenability of rocks to sensor-based ore sorting is both sensor and ore specific. It was also observed that the efficiency (recovery) of sorting is directly influenced by the degree of heterogeneity of the rocks. The overall outcome showed that with the right sensor, several of the materials tested are amenable to sensor-based ore sorting. Mining companies could benefit from multiple economic and design impacts, such as lower energy cost, lower transportation costs, higher metal recoveries and smaller footprints that lead to more sustainable mining. This paper will focus on the effects of heterogeneity of rocks on sorting potential and efficiency.IntroductionSensor-based ore sorting has been attracting more attention since the pressure for effective resource extraction and management has increased. An urge to make most of the current deposits, and to make the low-grade deposits economic to mine has ushered the technology to find new ways to overcome the new challenges. No matter the terminology used, such as coarse beneificiation, waste rejection, particle or bulk sorting, the purpose of sensor-based ore sorting is to remove low-grade rocks before the comminution circuit, increasing the feed head grade and quality while reducing the energy costs related to comminution.Despite nominal advantages, there have always been some concerns that have impeded the intorduction and acceptance of the technology. One of the most important shortcomings of ore sorting is their capability, or capacity, to keep up with the high-tonnage mining. Some other issues that have been mentioned as drawbacks to sorting include installation cost of such devices, feed preparation for effiecient sorting along with accuracy of sorting and probability of false negatives (Manouchehri, 2003)."

Jan 1, 2015

By Chris Larsen, Ian Orford, Mike Cooper

"An autogenous grinding circuit was commissioned at the Brunswick concentrator in October 1998. The autogenous grinding circuit replaced existing surface crushing plants, fine ore storage, rod and primary ball mills. The 8.54m diameter x 4.27m long (EGL) AN1 mill is driven by a bidirectional variable speed 6.3MW ABB wound rotor motor with Slip Energy Recovery (SER) drive. The AG mill was subsequently converted to SAG operation in May 1999 for a number of reasons. The mill is operated in closed circuit with horizontally inclined 660mm diameter cyclones to produce a circuit product P80 of 85 microns. Extensive test work and JKSimMet design modeling resulted in a production circuit operating closely within design expectations.The circuit is highly instrumented and controlled via a hybrid Programmable Logic Controller (PLC-5) and Fisher PROVOX Distributed Control System (DCS) that is in communication with the property information highway. An expert control system (Gensym G2) is used for control of the SAG mill load.Engineering and construction were completed in 28 months from the time of management approval for the project. The Brunswick AG/SAG mill circuit was commissioned on schedule at the $M 23.5 forecast budget."

Jan 1, 2001

By Harry Siewert

"The commissioning of the 4th concentrator (C4) at Freeport Indonesia in early 1998 increased total mill throughput from 130k to 230k tonnes per day. The C4 flowsheet consists of a single 38 ft diameter SAG mill, four 24 ft diameter ball mills followed by four banks of 4,500 ft3 WEMCO flotation cells.The design of the C4 rougher flotation circuit was based on the expectation that the copper and gold recoveries achieved with the 4500 ft3 flotation cells would be equivalent to or better than that achieved with the 3,000 ft3 flotation cells in the 3rd concentrator (C3) rougher circuit. This assumption was due to the fact that the C4 flotation feed size would be less than 15% +212 microns compared to the C3 rougher flotation feed size of less than 23% +212 microns. By mid 1998 it had become apparent that the C4 rougher flotation copper and gold recoveries were below those predicted.In order to determine the cause of the lower recoveries, stage by stage rougher flotation surveys were performed in all four concentrators. The results of the surveys showed that the C4 rougher flotation circuit had a lower recovery of +200 micron material than that achieved in the C 1, C2 and C3 concentrators. Through mineralogical analysis, it was determined that a majority of the copper contained in the +200 micron fractions was liberated and recoverable. This paper describes the steps taken to increase coarse particle recovery, overall plant recovery and the results achieved."

Jan 1, 2001

By Robert E. McIvor

"The design/optimization of the pump and cyclones to maximize grinding circuit efficiency first requires a concise understanding of, and clearly defined specifications for, desired grinding circuit performance. Subsequently, the pump and cyclone performances that provide the desired grinding circuit performance can be defined. Once the performance requirements of each process unit are determined, selection of physical equipment parameters that will deliver those performances can be carried out.The Functional Performance Equation shows that there are two distinct efficiencies in closed circuit ball milling. One of these, “Circuit Classification System Efficiency” (CSE), is the fraction of “coarse” material inside the ball mill upon which grinding energy is deliberately expended, versus the remaining fraction of “fines” or finished size material inside the mill, upon which grinding energy is wasted (on over-grinding). The role of the pump and cyclones is to maximize CSE, which is the desired grinding circuit performance. The obtainable target CSE for any given circuit can be estimated, for example, by referring to a plant data base of CSE’s. Design/optimization guidelines then allow us to specify the pump and cyclone performances that will achieve the target CSE.This paper outlines the step-by-step, systematic method of pump and cyclone selection which maximizes CSE. Numerous examples of its successful application are provided.THE FUNCTIONAL PERFORMANCE EQUATIONObservation of the feed and product size distributions going into and discharging from the mill in grinding circuits with low versus high circulating load ratios initially led to the definition of “Circuit Classification System Efficiency” (or CSE, McIvor, 1988a), and subsequently the discovery of the Functional Performance Equation (McIvor, 1988b; McIvor et al, 1992). The CSE is the fraction or percentage of “coarse” (usually in reference to the plus P80) size material inside the mill, versus “fines” or product size material finer than the circuit P80. It can be readily calculated by taking the average of the percentage of said coarse material in the mill feed and mill discharge streams. As this also represents the percentage of the mill energy expended on targeted, coarse size material, it is directly proportional to overall grinding circuit efficiency and production rate. This is all clearly expressed in the Functional Performance Equation for ball milling circuits, for which the derivation has often been presented (e.g. McIvor, 2006)."

Jan 1, 2011

By W. J. Wright

Summary This paper describes the general situation of the mining industry in New Brunswick, and gives a detailed description of the recent developments in the antimony deposits at Lake George and the copper deposits in the vicinity of New Horton. At the end are lists of the most interesting geological literature relating to the Province and of the geological and topographic maps that have been published. Introduction In presenting this paper to the Institute, I apologize for the small amount of scientific data which it contains. Recent investigations in the Province of New Brunswick have been carried on largely by outside interests, and at present we ourselves are in the position .of taking stock. However, I am glad of the opportunity of giving you a general idea of the situation. The Province is making an honest effort to learn the truth concerning her mineral deposits and in time hopes to collect data which should be of interest to the mining community.

Jan 1, 1931

By Rob Morrison, Peter Cameron

"Many products and technologies have been developed from outcomes of research projects carried out by the Julius Kruttschnitt Mineral Research Centre (JKMRC). When these products and technologies are applied to the design and optimisation of blasting, comminution and separation, improvements in profitability can be realised.In 1970 Alban Lynch promoted two practical ideas to improve plant operations:• Ore and equipment properties can be separated allowing experience with one type of ore or equipment to be transferred to other types of ore and equipment. If this experience was encapsulated in a mathematical model, then these properties could be combined and used to simulate (ie. to design and to optimise) complete mineral processing circuits.• Many problems associated with scale-up from laboratory to industrial equipment could be eliminated by experimental work on full-scale equipment in the plant.Many JKMRC research projects have focussed on the development of models of unit operations in mineral processing and their application to process simulation.Models of comminution and classification developed at the JKMRC have been used since the early 1980's. Ore characterisation techniques developed to support these models are licensed world wide through JKTech. The application of comminution modelling techniques to blasting, which optimises the process feed size distribution is used in Mine-to-Mill® projects. The advances in the understanding and modelling of froth flotation over recent years have provided the opportunity for integrated ore characterisation and process optimisation from resource to product.JKMRC project outcomes often provide proven opportunities for the mineral industry to improve performance and productivity. JKTech was established in 1986 to commercialise and market the most promising outcomes and thus ensure their continuing availability to the mineral industry.They include:• Commercial software (JKSimMet, JKSimBlast and JKMetAccount).• Monographs (Comminution and Blasting).• Technologies (Mine-to-Mill® and flotation optimisation).• Hardware products (JKFrothCam, JKJetLift® and the Mineral Liberation Analyser).This paper summarises these technologies and their benefits."

Jan 1, 2003

By Peter Radziszewski

"Comminition process costs, which typically represent an important contribution to mining operating costs, can themselves be divided roughly between energy and liner /charge wear. As such, developing the ability of predicting mill wear will allow a more accurate estimation of wear costs and therefore their control. In this paper and based on the possibility of estimating energy dissipated in impact and abrasion by using a discrete element charge motion model for mill charge motion simulation, media wear will be investigated principally as a function of three wear mechanisms : impact, abrasion and corrosion. Experimental results will be used to identify a total media wear model. Model results will be compared with real mill data from three operating Australian mines. These preliminary results show for the cases tested that the overall average error, as compared with the observed cases, is 0 % with a standard deviation of 66.1 %. Results from the Bond abrasion index tests, for the same cases investigated, give an overall error of 73 % and a standard deviation of 192.5 %. Further work is in progress to improve test procedure, validity and confidence.INTRODUCTIONComminition process costs, which typically represent an important contribution to mining operating costs, can themselves be divided roughly between energy and line / charge wear. In Greenfield situations where the estimation of operating costs is critical in determining project feasibility, the level of confidence in such estimates becomes quite important. With regards to media wear, the Bond abrasion test currently serves as the standard media wear prediction device. However, as shown [l, 21 test results once compared with actual wear rates can vary greatly. Figure 1 shows test results as compared with 15 cases. Average error over this data is 73 % with a standard deviation of 192.5 %. As such, developing the ability of more accurately predicting mill wear will allow greater confidence in wear cost estimation and therefore their control."

Jan 1, 2001

By D. du Plessis, R. Stobbs

The Canadian Clean Power Coalition (CCPC) was created in 2001 to protect and enhance Canada’s vast coal and other carbon-based resource wealth, and to ensure that environmental public policy decisions recognize that these resources are a Canadian asset, not an environmental liability. To achieve its mandate, CCPC has undertaken to demonstrate technologies for use in new coal-fired power plants to control air emissions including carbon dioxide (CO2), nitrogen oxides (NOx), sulphur dioxides (SOx), mercury (Hg), and particulates (PM). The first phase of the demonstration project assessed three existing technologies for coal-fired power plants that reduce all emissions, including CO2, to levels equivalent to or below that of gas-fired power plants. The technologies considered in this phase included integrated gasification combined cycle (IGCC), ‘oxyfuel’ combustion, and amine scrubbing of pulverized coal. These technologies were evaluated with three coal types: Eastern bituminous, western sub-bituminous, and lignite coals. This paper presents the studies, conclusions concerning the capital and operating costs of these technologies, the cost of electricity produced (with CO2 removed), and the cost per tonne of CO2 avoided. It also discusses the potential for using captured CO2 for enhanced oil recovery, and possible technology enhancements for improving the competitiveness of gasification of low-rank western Canadian coals. The second ongoing phase of CCPC’s work includes the design and construction of a commercial-scale plant to demonstrate the feasibility of integrated gas combined cycle (IGCC) and/or polygeneration technologies and the potential for using the CO2 generated for enhanced recovery of conventional oil.

Jan 1, 2006