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By Chris Dougherty

"This presentation will provide a demonstration of the methodology used in designing a modern shaft and hoisting plant utilizing a review of the challenges faced and solutions delivered for the Elk Creek Superalloy Materials Project (Niobium/Scandium). The development of the design required the review of complex hydrogeological conditions, mine production requirements, demanding capital expenditure (CAPEX) limitations and tight schedules. Through an extensive review of various alternatives to satisfy these constraints, the Nordmin Group (including Nordmin Engineering Ltd.) (Nordmin) was able to define a concept and design that addressed risks to the project, met production requirements, cost and schedule constraints and improved constructability. INTRODUCTION The Elk Creek Project, owned by NioCorp Developments Ltd. (NioCorp) presently, will become Nebraska’s first underground metals mine, built to access the Elk Creek Niobium/Scandium deposit. The development of the design for this facility required the review of challenging hydrogeological conditions, mine production requirements, demanding CAPEX limitations and tight schedules. Through an extensive review of various alternatives to satisfy these constraints, the Nordmin Group was able to define a concept and design that addressed risks to the project, met production requirements, cost and schedule constraints and improved constructability. This paper will review the challenges faced, and solutions arrived at in a demonstration of a methodology used in designing a modern shaft and hoisting plant. THE CHALLENGES Nordmin became involved in the project in 2015, invited by the Feasibility Study Consultant to provide input on estimating and layouts for the new operation. Many of the fundamental decisions regarding mining methodology, water handling and production strategy had been made, and the scope of Nordmin’s involvement was very limited in this first engagement. Following submission of that study in late 2017/early 2018, Nordmin had opportunity to discuss the overall effort, and its many assumptions and challenges, with NioCorp’s project team. The dialogue quickly identified several significant opportunities to improve the project construction schedule and costs along with the mine production profile and operational approach while reducing project risk."

Jan 1, 2019

By W. F. Harkness, D. Hodgkinson

"A non-destructive testing program was established at Crows Nest Resources (C.N.R.), Line Creek mining operation following an in-service fatigue failure of a front wheel spindle on a large haulage truck.This failure identified a definite need for improvements in the ultrasonic techniques used during the mandatory spindle integrity examinations. Initial investigations using common mining industry ultrasonic examination techniques showed that the smallest detectable cracks were 75 mm in length for the spindle types in service at the C.N.R. site. The Initial findings indicated that inadequate inspection technique design was the cause of the poor performance. To improve inspection reliability it was identified that improved ultrasonic techniques were required. Results using designed ultrasonic techniques were encouraging, with the detection of simulated and natural cracks 12 mm long achieved. The cost benefits associated with the extended spindle life, following the removal of these small fatigue cracks, far exceeded those of the expertise and effort necessary to implement and conduct the N.D.T. program.Introduction During 50 years of evolution, non-destructive testing (N.D. T.) has progressed from a laboratory curiosity to a well accepted and invaluable tool used in the assessment of material integrity. Unlike destructive testing, N.D.T. does not deform or render the material useless. Non-destructive tests may involve many applications, from the determination of a corrosion prevention coating thickness to the examination of a raw material for internal and external deformities.Within the mining sector, highly-stressed components will normally have been subjected to some form of non-destructive test during their manufacturing cycle. These tests are used to ensure the component does not contain material flaws whichmay be detrimental to its service performance.While the component may have assured quality when produced, deterioration by fatigue may occur during an aggressive service life. Large dynamically-loaded components such as haulage truck front wheel spindles are , in particular, prone to this service related problem."

Jan 1, 1987

By Michel Garon

"Several years ago computer control of the flotation process was successfully implemented at the Matagami concentrator of Noranda Mines Inc. At that time this was the first computer application being installed at this operation. The last few years have seen an extensive use of programmable controllers in areas such as the copper and zinc dewatering circuits and the lime preparation system. With the aid of such instruments, these areas have attained a high level of automation and as a result, a high degree of efficiency. The controllers have proven to be very dependable and easy to use.IntroductionThe Matagarni Division of Noranda Mines Inc. operates two mines in the Matagami District of northwestern Quebec which is located about 650 km northwest of Montreal. The mines ship ores to a central concentrator whose throughput averages 95,000 tonnes of ore per month. Metal contents of the mill feed average 0.9 per cent copper and 5.0 per cent zinc. Concentrate outputs are approximately 3,200 tonnes of copper and 8,200 tonnes of zinc per month.The concentrator commenced operation in 1963. An on-stream X-ray analyzer was installed in 1968, providing analyses of several samples in the flotation circuit without the aid of a computer. In 1974, control of the circuit by computer was added to the system. As a result, zinc flotation efficiency improved considerably and reagent costs decreased through the reduction of copper sulphate consumption.In the past few years it was realized that significant improvements could also be made in other parts of the operation . Copper and zinc dewatering circuits and the lime preparation system were identified as major areas that could drastically benefit from automation. In 1982, programmable controllers were seriously considered as an attractive alternative for achieving the company 's goal. Because of their relative lowcost and their high degree of flexibility, they were selected for implementing automation and, for improving the efficiency in each of these areas."

Jan 1, 1985

By Charlie Graham, Helen Shang, Ashley Scott, Andrew Hall

"Approaches to Energy Recovery• Upgrading for electricity generation - steam turbines• Direct extraction- process improvement or space heating- support medium for animal or plant growth– fish or microalgae• Heat pumps- space heating/coolingWater Energy Grades• High (150+ °C) - electricity Generation• Medium (26 to 121 °C) - direct extraction• Low (5 to 18 °Celsius)- use of heat pump is required• Temperatures between zones will depend on circumstances for best use."

Jan 1, 2012

By H. Huang, H. M. Chen, W. B. Xie

Cu-0.8Cr-0.1Zr alloy were prepared by atmospheric melting. the microstructure and properties of the CuCrZr alloy after first cold rolled, solid solution, second cold rolled and aging treatment were analyzed by using optical microscope, electrical conductivity analysis and Vickers hardness tester. The results show that with the increase of the first cold rolled deformation, the grain breakage becomes more serious, and the cold hardening becomes more obvious and the hardness increases. The conductivity and peak hardness of the first cold rolled (reduction of 30% and 60%) alloys after solution, secondary cold rolled and aging treatment reaches 81 %IACS and 187 HV, respectively. However, the conductivity in the CuCrZr alloy with a higher rolling degree (reduction of 90%) after solution, secondary cold rolling and aging treatment is significantly higher, and the conductivity and peak hardness is 85.8 %IACS and 178 HV, respectively. INTRODUCTION CuCrZr alloy has been widely used in domestic industry for its excellent comprehensive properties such as high strength and high conductivity, especially in the contact wire and lead frame of high-speed railway (Sun, Tao, & Lu, 2015; Mishnev, Shakhova, Belyakov, & Kaibyshev, 2015; Zhang et al., 2016; Fu et al., 2017). In recent years, a lot of research has been done on how to improve the strength and conductivity of CuCrZr alloy. However, the high strength and high conductivity of copper alloys are contradictory characteristics. On the one hand, the addition of alloying elements is conducive to solution strengthening and aging strengthening; on the other hand, too much alloying elements in copper alloys cause defects in the lattice of copper matrix, resulting in a serious decline in the conductivity of copper alloys (Martienssen & Walirmont, 2005). How to obtain high strength and high conductivity at the same time is the main problem. At present, the main research methods are adding microalloying elements, thermomechanical treatment and severe plastic deformation to study the electrical conductivity and mechanical properties of CuCrZr alloys. For example, Xie et al. (2011) added trace Ag to the Cu-0.26 wt%Cr-0.08 wt%Zr alloy, and the size of precipitated phase Cr and Cu4Zr became smaller and the mechanical properties of the alloy were improved. Su, Dong, Liu, Li, & Kang (2004) found that the addition of trace Mg in CuCrZr alloy inhibits the growth of precipitated phase and reduces the internal stress around the precipitated phase. At the same time, the size of precipitated phase becomes smaller and the peak aging strength of the alloy is improved. Pang et al. (2013) found that adding trace Ni and Si to the CuCrZr alloy could improve the peak hardness, softening resistance and precipitation morphology of the alloy. Experiments shows that the grain size was significantly refined by equal channel angular extrusion combined with aging treatment, while the strength of the alloy was increased, and the electrical conductivity of the alloy did not decrease (Vinogradov, Patlan, Suzuki, Kitagawa, & Kopylov, 2002; Saray, 2016); Kermajani, Raygan, Hanayi, & Ghaffari (2013) showed that the strength of CuCrZr alloy can be improved by rolling at 500 °C. After 150 minutes of aging treatment, the strength and conductivity of the material increased to 431 MPa and 81 %IACS, respectively. Takata, Ohtake, Kita, Kitagawa, and Tsuji (2009) noted that the strain hardening, uniform elongation and tensile strength of the nano-precipitates produced by the mechanical heat treatment process can be notable enhanced. The mechanical and electrical properties of CuCrZr alloy can be improved by combining large plastic deformation with aging treatment in the test process (Gao, Huttunen-Saarivirta, Tiainen, & Hemmila, 2003; Huang et al., 2003; Xia et al., 2012; Zel’dovich et al., 2014).

Jan 1, 2019

By A. E. M. Warner, A. Vahed, P. J. Mackey

"Since early 2015, the price of nickel has dropped from the region of US$6/pound to current levels of around US$4.60/pound (March 2017), reflecting several market factors, but principally due to lower demand from China. Under such conditions, nickel companies have been under pressure to contain operating costs. In addition, labor and energy costs will continue to rise, while nickel ore grades will likely continue to drop. All major companies now accept the need for climate change action and consequently efforts are being made towards lowering carbon-based emissions. Nevertheless, meeting these challenges can also contribute to higher operating costs without parallel innovative developments - which at the same time, under current conditions, major companies are tending to curtail. In this paper, several productivity improvement opportunities to reduce unit operating costs at nickel sulphide and nickel laterite plants are reviewed. Opportunities include: (a) process technology and energy-type selection, production capability, optimization of process intensity and implementation of newer technologies; (b) improved productivity, equipment availability including maintenance best practice; (c) energy savings and recovery opportunities and use of energy surveys and, (d) process modeling and improved scheduling. Such improvements along with an uptick seen in nickel demand going forward should better position the world nickel industry.INTRODUCTION Nickel is an essential metal to modern society, primarily through its use as an important ingredient in stainless steel. Thus, stainless steel finds vital applications in food preparation facilities, as well as important uses in transportation and industrial applications. Canada has always played an important role in nickel production and nickel metallurgy. In the 1940s and 1950s, Canada supplied over 90% of the world’s nickel. However, this proportion has declined considerably to around 10% of the world nickel supply today. Still, Canada remains an important nickel supplier and contributor to nickel extractive technology. Due to the importance of nickel to society, nickel demand is expected to continually rise. On the other hand, nickel companies have been under pressure to contain production costs amid languishing nickel prices. While demand projections show nickel growth, there are uncertainties in actual levels of future market growth. Ore grades are dropping, while labour and energy costs, which are key cost contributors are rising, hence efforts to lower production costs will generally require innovative approaches."

Jan 1, 2017

By A. Motamedi

Indoor localization has gained importance as it has the potential to improve various processes related to the lifecycle management of facilities and to deliver personalized and location-based services. Radio Frequency Identification (RFID) based systems, on the other hand, have been widely used in different applications in construction and maintenance. This paper investigates the usage of RFID technology for indoor localization of RFID equipped movable assets during the operation phase of facilities. The location-related data on RFID tags attached to fixed assets are extracted from a Building Information Model (BIM) and can provide context-aware information inside the building which can improve Facilities Management (FM) processes. The paper proposes a new approach to use received signals from available reference tags in the building attached to fixed assets to locate movable assets. The approach uses signal pattern matching and clustering algorithms for localization. As a result, a user equipped with an RFID reader is able to estimate the location of target assets, without having access to any Real- Time Location System (RTLS) infrastructure. A case study is performed to demonstrate the feasibility of proposed methods.

Aug 1, 2013

By R. J. Rotzinger

The Gibraltar Mine and Mill facility were commissioned in 1972 by Gibraltar Mines Ltd utilizing a flowsheet consisting of two stages of crushing followed by a rod mill / ball mill grinding circuit. During operations a number of opportunities were evaluated to expand the mill capacity; however, the economics of the day did not allow any of these projects to proceed. The mine continued to operate until late 1998 when it was shutdown and put on care and maintenance due to low commodity prices. Taseko Mines acquired Gibraltar in 1999 and in 2004, with the improvement in the metal markets, made the decision to restart operations. During the restart planning a number of opportunities for mill improvements and upgrades were identified and, after operations were successfully restarted, the decision was made to once again review expansion opportunities for Gibraltar. Taseko evaluated various expansion alternatives eventually deciding to install a SAG Mill, convert the existing rod mills to ball mills and distribute the SAG discharge to the resultant six 6 parallel ball mills. This paper discusses the design, implementation and commissioning of the SAG mill grinding circuit.

Jan 1, 2012

By J. S. Stickling, P. J. Whittaker, N. O. Lotter

"Assessment of opportunities to improve mineral processing performance in existing concentrators and in describing undeveloped orebodies is key to improving the business case of a mining company. This assessment has traditionally been performed using the distinct and separate inputs from mineral processing and mineral science.More recently, process mineralogy has been used to integrate these two disciplines. This trend has been driven by the need to develop and process more challenging ore deposits, and has been assisted by the availability of modern automated instruments. Together with the acquisition of a QemSCAN (quantitative evaluation of materials by scanning electron microscope) from CSIRO in Australia, and with the use of a supporting SEM with EDX/WDX capabilities and an XRD, the development of process mineralogy at Falconbridge commenced in 1997.The sampling challenges in presenting a QemSCAN with representative sample material at the polished section level are significant, but have been effectively addressed. The full description of this aspect is beyond the scope of this paper.It is shown that, by use of this approach, the set nature of an orebody can be best exploited with selected flowsheet changes in a concentrator which address the generic characteristics of the orebody. In this way, the flowsheet provides a process that more effectively fits the mineral processing requirements of the ore. This leads to clear and tangible improvements in grade and recovery."

Jan 1, 2002

Polymer electrolyte membrane (PEM) fuel cell has increasingly become the potential choice of zero-emission power source for portable, mobile and stationary co¬generation applications. However, technical barriers need to be overcome before its widespread commercialization; cost reduction and performance improvement including reliability are the two key areas, that can be realized through better cell/stack design and improved understanding of the transport processes occurring inside the individual cells and stacks. In this presentation, we will provide an overview of various cell/stack models that are available in the literature, their strength and weakness, and then present a comprehensive multi-species, multi-phase and multi-dimensional formulation of a single PEM fuel cell, with consistent and systematic formulation for all the regions involved, including the solid bipolar plates, gas flow channels, the electrode backing layers, the catalyst layers and the electrolyte membrane. Such a detailed approach allows us to extract sufficient information to the analysis of a stack of PEM fuel cells. Stack model will be presented that investigates the various stack designs and flow configurations, and the optimal stack design based on the present study will be described. Also some innovative cell/stack designs will be featured.

Jan 1, 2005

By N. Haghdadi, D. M. Maijer, A. B. Phillion

B206 is a recently-developed high-strength Al-Cu casting alloy with reduced Ti and Fe, as compared to the well-known AA 206 alloy, for improved hot tearing resistance. In the current study, the solidification kinetics of this alloy as a function of cooling rate from 1 to 15 K/min were studied using differential scanning calorimetry (DSC) and microscopy. Specifically, the evolution in fraction solid, grain size, and secondary dendrite arm spacing have been characterized. The DSC results show the occurrence of three peaks during cooling from the liquid state, which are related to the formation of primary aluminum, a pre-eutectic intermetallic, and the eutectic phases. Thermal analysis also indicates that while the liquidus temperature is not sensitive to the cooling rate, the temperatures at which the pre-eutectic and eutectic phases form are strongly coupled to the rate of heat extraction. A decrease in the latter temperatures was observed when the rate of solidification was increased, leading to a lengthening of the freezing range of the primary phase. The results will be useful for improving B206 casting processes, specifically through modification of mould cooling conditions.

Jan 1, 2014

By R. J. Rotzinger, K. W. Major

The Gibraltar Mine and Mill facility were commissioned in 1972 by Gibraltar Mines Ltd utilizing a flowsheet consisting of two stages of crushing followed by a rod mill / ball mill grinding circuit. During operations a number of opportunities were evaluated to expand the mill capacity; however, the economics of the day did not allow any of these projects to proceed. The mine continued to operate until late 1998 when it was shutdown and put on care and maintenance due to low commodity prices. Taseko Mines acquired Gibraltar in 1999 and in 2004, with the improvement in the metal markets, made the decision to restart operations. During the restart planning a number of opportunities for mill improvements and upgrades were identified and, after operations were successfully restarted, the decision was made to once again review expansion opportunities for Gibraltar. Taseko evaluated various expansion alternatives eventually deciding to install a SAG Mill, convert the existing rod mills to ball mills and distribute the SAG discharge to the resultant six 6 parallel ball mills. This paper discusses the design, implementation and commissioning of the SAG mill grinding circuit.

Jan 1, 2012

By H. Soto, P. Lacombe, R. del Villar

"During the summer of1989, Les Mines Selbaie, with the cooperation of Université Laval initiated a research project to evaluate the column flotation technology for its concentrator near Joutel, Quebec. The experimental work involved both a 5 cm by 11 m laboratory column and a 45 cm by 10 m home-made pilot unit Amenability tests were conducted using both units on various streams of the plant. Results showed that columns are not suitable for the copper cleaning circuit because the loss of precious metals, associated with the rejected pyrite, overcome the improved copper metallurgy. On the other hand, column testing at the zinc circuit showed improved zinc selectivity.Scale-up testing was', therefore, conducted on the first zinc cleaner concentrate using the laboratory-size column. The influence of variables such as porous parger grain size, wash water flow rate, airflow rate and froth depth values on column performance was' first assessed. Scale-up parameters were then determined using the optimal operating conditions from the previous tests. Simulation facilitated the determination of the most convenient plant-scale column arrangement.A number of conclusions concerning the experimental determination of scale-up parameters are also presented."

Jan 1, 1993

By Mi, Dong Liang, Jingyuan Bai, Victor Zhou, Xujun

Squirrel cage induction motors are the mostly used motors at present. Currently, the rotors of the squirrel cage induction motors are produced by aluminum die casting technique with the advantages of low cost of rotors. It is well known that the copper’s electrical conductivity is around 40% higher than that of aluminum. If copper is used to replace the current widely used aluminum in rotors, the total loss of motors will be reduced, hence increasing the overall motor efficiency. Copper rotors can be used to produce high efficiency and even super premium efficiency motors without enlarge the motor frame size. Considering the huge quantity of motors, the die casting process is the best solution to produce copper rotor with economic cost. Because of the characteristics of copper, it is difficult to produce copper rotors by casting similar to that done in aluminum rotors. In order to improve the die casting quality of copper rotor, a new tooling structure was developed and the casting process of copper rotor was simulated and analyzed by Any-casting software. The filling process, solidification process, inner gas distribution and residual melt modulus were analyzed. It was found that the design of symmetrical runner and inner runner on both sides was helpful to reduce the impact of molten copper to the cavity surface during the filling process. The use of Slag traps array can reduce die casting defects inside the end rings. That will be helpful to improve the rotor quality. INTRODUCTION Squirrel-cage AC induction motors are most widely used in the world. In 2017, the total installed capacity of AC motors in China has reached more than 1.2 billion kW, and the annual power consumption accounts for about 60% of the total national electricity consumption. To improve the efficiency of squirrel-cage motor will be helpful to energy conservation and environment protection. There are several ways to improve efficiency of induction motors, using copper rotor is one of the most effective solutions. It is well known that the copper’s electrical conductivity is around 40% higher than that of aluminum. If copper is used to replace the current widely used aluminum in rotors, the total loss of motors will be reduced, hence increasing the overall motor efficiency. Copper rotors can be used to produce high efficiency and even super premium efficiency motors without enlarge the motor frame size.

Jan 1, 2019

By W. Noel O?Brien

Introduction Since 1930 numerous improvements have been made in equipment designed for the mechanical removal of broken ore in underground mining operations. New applications of mechanical equipment, as? well as improvements and adaptations of well established systems, are being made continually. It is the purpose of this paper to discuss present-day equipment for the removal or transfer of broken ore by means of a powered hoist and scraper arrangement. The terms used throughout the paper are those commonly employed in the trade literature and by mining men. The terms slusher hoist, hoist, and scraper hoist are used inter-changeably to mean a machine, powered by compressed air or electricity, with drums for the winding of wire rope. The tail rope, also known as the pull-back rope or return rope, drags the empty scraper toward the tail-sheave, that is, back to the loading point. No attempt is made to cover the entire field of application of scraping methods. Rather it is the? writer's desire to emphasize the fundamental principles of scraping practice and design and to relate them to some modern applications. The available literature on scraping practice has been freely used. together with personal observation and information and advice of practising engineers and representatives of companies manufacturing slushing equipment.

Jan 1, 1951

By J. Sliwinski, H. Kikutani, J. Atwood, D. Larimer, J. Pyecha

"The Pogo mine start-up milling targets of 2005 are vastly different than the targets of today. Improvements have been driven by unintentional design oversight, continual circuit optimization or optimization due to changing mineralogy. The more significant process improvements to date have occurred in the gravity, flotation and leach/CIP unit operations. Details of the significant improvements are presented along with the impacts to the process.INTRODUCTION Deposit Overview Pogo mine is located along the Goodpaster River, southeast of Fairbanks, Alaska. This deposit sits in the center of the Tintina Gold Province (Figure 1), a region of similar Intrusion Related Gold deposits in Interior Alaska, the Yukon and British Columbia Canada (McCoy et al., 1997). The Pogo deposit is hosted in a rock sequence of amphibolite-grade gneisses intruded by mid-Cretaceous granitic plutons and dikes, which in turn, were cut by and host the auriferous quartz veins of the Pogo deposit.The Pogo deposit is comprised of three distinct zones of auriferous quartz veins spatially adjacent to each other. These are the Liese Zone, North Zone, and the East Deep Zone. The Liese Zone consists of three stacked, massive quartz veins, designated the L1, L2, and L3. Vein thickness averages 3.0 m, with variations from 0.3–18 m thick. The North Zone mineralization is comprised of four veins with more consistent thickness, between 1 and 1.5 m. The East Deep deposit lies northeast of the Liese Zone ore body. It is separated by a post mineralization, quartz diorite pluton. The East Deep Zone is comprised of two stacked massive quartz veins with similar orientation as the Liese Zone."

Jan 1, 2017

By Muhammad Zaka Emad

Cemented rockfill (CRF) plays a vital role in pillar-less mining. Many factors are associated with optimum design of a CRF material. Factors like strength, placement method, mixing, curing time, water content, binder contents, binder composition and additives require to be studied for appropriate rockfill design. The most important factor is strength of a CRF. The design engineer considers fill strength requirements (FSR) for the estimation of CRF strength requirements. Inappropriate CRF strength can cause excessive ore dilution. The recent studies on CRF practices at some of the Canadian mines revealed the most common flaws. Comparison of different types of fill determined that most of the failures occur in cemented rockfill, and the compressive strength can be improved by small addition of sand and mine tailings. This work discusses the studies on determination of unconfined compressive strength, Young?s modulus, density and water contents of CRF being placed in the excavated stopes. It was found that the CRF properties were largely influenced by the variation in gradation and curing time. The 7% binder content improved compressive strength of rockfill significantly but it has an influence on the economics, whereas 4% and 5% binder contents are better choices. The maximum Young?s modulus values were obtained at 28 days curing time for most of the samples.

May 1, 2011

By George A. Lawrence, J. C. McHardy

"Field operating experience with an improved flotation mechanism for handling various flotation applications is covered in this paper. Some aspects of designing flotation machines are also presented. Operating data from extensive testing of commercial size equipment under actual plant operating conditions in the following applications is detailed:1. Copper Flotation2. Fine Coal Flotation3. Base Metal Sulfide FlotationDesign features, design improvements, modifications tested, and overall performance data are reviewed. Some mecl1anical performance data as well as metallurgical performance results are presented. Some comparisons with conventional flotation equipment are reported in this paper.Flotation sizing theories are reviewed and an actual equipment selection ex2.mple is presented. Scale-up criteria used for developing large cells are briefly covered.The paper concludes with a brief review of anticipated future flotation equipment design needs. IntroductionThe mining/milling industry is faced with increasing pressure to cut costs while maintaining product quality and indeed, in some instances, expanding production. For copper, nickel, iron, molybdenum, lead and zinc sulphides, coal, phosphate and some other minerals;, flotation remains the primary method of concentration and recovery of the valuable mineral away from the gangue. Cost reduction in flotation can be broadly focused on two areas:1. Flotation Chemicals2. Flotation Equipment"

Jan 1, 1985

By K. Najim, D. Hodouin

"The raw ores which are processed in mineral processing plants exhibit very strong variations of their physical and chemical properties. As a consequence, the performances of the comminution and separation processes vary greatly from time to time. Model-based control strategies improve the performance of the plant; however, they require some form of adaptation to cope with the variations of the are properties.This paper deals with the use of adaptive techniques for the control of mineral processes. It begins with a survey on adaptive control algorithms including parameters estimation aspects. Then several examples dealing with crushing, rod, ball, autogenous and semi-autogenous grinding, flotation , drying and calcination processes are reviewed.IntroductionThe operation of the various processes of mineral processing plants (crushing, grinding, flotation, dewatering, etc.) is generally controlled using empirically tuned regulators of constant structure, such as PID controllers. To improve the operation performance, mineral processors try to implement specifically designed controllers, i.e. controllers based on plant dynamic models. Most of the time, these techniques improve the control of the mineral processing installations. However, modelling is a complex procedure because of the problems of measurement and data management, specific to this industry, and because of the variations of the model parameters. In this context model-based control strategies do not always bring the expected improvements or are sometimes discarded and replaced by more conventional techniques .The sources of variation of the dynamic behaviour of mineral processing systems can be classified into three categories: (I) the inherent changes of the raw ore properties (composition, grindability, mineralogical texture, etc.); (2) the process tuning modifications (grinding media loads, number of hydrocyclones, slurry level in flotation cells, agitation speeds, etc.); (3) the feedrate variation of the ore, water, chemical reagents, etc. All these factors change the fundamental properties of the process dynamics such as the grinding or flotation rates and the residence time in the equipment. The simplified linear models which are used to describe the process dynamics are not able to track the complex behaviour of the mineral processing systems when the amplitude of the sources of variation are too large. The mismatch between the model and the plant behaviour is then frequently a cause of model-based controller failures."

Jan 1, 1992

By I. Govender

Positron-Emission-Particle-Tracking (PEPT) has enabled the non-invasive observation of charge and slurry transport in model mills under operational conditions. We use high quality PEPT data to infer that the charge motion can be effectively described by a non-Newtonian granular fluid. An improved theory for slurry transport, including inertial effects, is presented.

Jan 1, 2012