Search Documents

By G. Simard, M. J. Gagnon, A. Charette, G. Péloquin

"In the Bayer process, flocculants are introduced in the feed well to enhance the aggregation of red mud particles. To gain a better understanding of the flocculation process taking place in the feed well, shearinduced flocculation was achieved using concentric rotating cylinders (Couette system). Our previous work has shown the effect of the shear rate on the aggregate’s settling rate and on residual turbidity of the Bayer liquor. In this study, the data demonstrated that the aggregates at selected shear levels appear as a population with a widespread size distribution. By using an imagery apparatus, it was possible to measure the size, the shape, and the sedimentation velocity of the larger red mud aggregates. Marked differences were noticed in the characteristics of the aggregate populations obtained under various shear conditions. IntroductionIn the Bayer process, red mud particles are separated from the liquor in primary clarifiers and washing circuits under the action of synthetic polymers. The agitation in the feed pipe and in the feed well affects the flocculation since the aggregates are formed by the interaction between the red mud particles and the polymers. A minimum shear rate is needed to initiate the aggregation process of fine particles (Warren, 1975).Different systems have been used to study the effects of shear on the flocculation process (Tampo and Watanabe, 1979; Klimpel and Hogg, 1986; Scott et al., 1996; Biggs and Lant, 2000). The Couette flow system has been used in some studies on shear-flocculation (Oles, 1992; Farrow and Swift, 1996a, 1996b). The importance of the physical properties of the aggregates in determining the efficiency of the solid-liquid separation process within a given gravity thickener has been demonstrated (Farrow and Warren, 1989a)"

Jan 1, 2002

The #3 Shaft at Brunswick Mine, Bathurst, New Brunswick, Canada, intersects a soft graphite zone just below the 3400 Level. Ground movement within this zone causes the concrete liner of the shaft to be deflected towards the shaft?s interior, affecting the steel framework of the conveyance. In some areas, the clearance between the cage and the liner has been reduced to less than 2 cm, which is a concern. An innovative surface-mounted extensometer was designed in 2008 to monitor potential movements of the shaft?s liner. Four such novel extensometers were installed in the shaft for the surveillance of a particularly critical 3.0m by 5.5m area. This article describes the approach taken to instrument the shaft, the principle of the new extensometer, as well as the performance of the instrumentation following its installation.

May 1, 2009

By P. A. Selvadurai

This paper presents the results of a research investigation leading to the development of a technique for the measurement of the surface permeability of Indiana Limestone. The tests are conducted on a cuboidal block of the limestone with a flat surface that can be sealed to create a circular aperture through which water influx can take place. Computational results for Darcy flow are used to interpret the results of the experiments. The water entry area can be moved over the surface area of the block to investigate, quite conveniently, the distribution of permeability across the surface of the limestone block sample.

May 1, 2009

By Dan Alexander, Ivan Crnkovic, Sarah Schwarz

"Several plant studies have been conducted at the Zinifex Century Mine over the past 5 years. For each of the plant studies, surveys of the zinc primary circuit were conducted, characterisation measurements for each operating cell taken, and the floatability components of the ore mapped to develop a model of the circuit. The floatability components and machine parameters were then used to simulate changes in circuit configuration and operating conditions, enabling further potential improvements in circuit performance to be identified.This paper reviews the current flotation practice at the mine, as well as various circuit changes and developments implemented by site. The application of the methodology and the evolution of the standard procedure are also discussed.INTRODUCTIONBase metals were first discovered in the Lawn Hill region of Queensland’s North West in 1869 and the first mining lease in this area was pegged in 1887 over what is now known as the Silver King vein deposit. The area encompassing these veins, which includes the Century deposit, was proclaimed the Burketown Mining Field in 1899. Exploration titles were granted to CRA in 1987, precisely 100 years after the initial discovery at Silver King, hence the name ‘Century’.Century was commissioned by Pasminco in late 1999, with the mine becoming fully operational on 1 March 2000 and the official opening taking place in April. Pasminco had bought the Century and Dugald River deposits from CRA in 1997 for A$345 million, and invested some A$710 million in bringing Century into production. Today, Century is the world’s second-largest zinc mine in terms of its output, having reached full capacity in 2003.The Zinifex Century Limited (“ZCL”) lead-zinc-silver deposit is located approximately 250 kms north-north west of Mt Isa in north-western Queensland. The deposit is a large flat-lying ore body covering an area of some 1.2 by 1.4 km, the 45 m-thick stratabound sulphide orebody is hosted within an 850 m-thick sequence of Proterozoic siltstone, shales and sandstone, amenable to open-cut mining methods. The mine has ramped up to full production delivering five and a half million tonnes of ore per annum, yielding approximately 900,000 tonnes of zinc concentrate and 90,000 tonnes of lead concentrate. Mine life is expected to be about 8 years"

Jan 1, 2008

By J. Miettunen

"The lining of a grinding mill has an important role in creating the conditions for the grinding process. The main purpose of the lining is to transfer the energy taken by the mill motor to the contents of a mill. The power draw curve of the mill, if measured with sufficiently short intervals, describes how well the lining works in lifting and mixing the material to be ground.The power draw curve can also be used for determining the volumetric filling of a mill. This new measuring technique was developed at the Pyhasalmi concentrator in 1989-90. The measuring device with its PC-connections offers an excellent tool for controlling volumetric mill filling, for maximizing throughput and for research purpose (e.g. process studies, mill linings design).The paper describes the new method and the results achieved at Outokumpu's concentrators.INTRODUCTIONVarious methods have been developed for measuring mill load; weighing, noise, etc. Weighing is one of the most reliable methods but installing the sensor to existing mills is often difficult. Besides the load measurement does not indicate the volumetric filling if the specific gravity of the mill feed fluctuates. Noise measurement has often failed with its sensitivity to various disturbance sources.As known, the power draw measurement is one of the most accurate measurements in grinding circuits and therefore it has been utilized in sophisticated control, e.g. in power peak seeking algorithms for maintaining maximum grinding efficiency.About 10 years ago power oscillation measurement was developed at Pyhasalmi concentrator. In this method the amplitude of the oscillation caused by the lifters was measured. The oscillation amplitude and the mill filling has quite a good correlation and together with the power draw measurement it could be used for maximizing mill throughput (Koivistoinen and Miettunen, 1989). The main difficulties in this method were that the dependence between mill filling and the amplitude is unlinear and that the dependence also is individual for each mill.The method developed during 1989-90 is also based on the power oscillation but on its phase shift. In principle level of the material in a mill is measured. The method has been successfully used for maximizing throughput at Pyhasalmi and Enonkoski concentrators and at Harjavalta slag concentrator."

Jan 1, 1991

By James Anstey

BHP Billiton?s Cannington facility is a mining and minerals processing plant near Mt. Isa in Central Queensland, Australia, producing silver, lead and zinc. Mine ore is processed in a concentrator, which consists of grinding, flotation, thickening and filtration. Grinding is carried out in a fully autogenous (AG) mill. The mill operates in closed circuit with a pebble crusher. Throughput is approximately 380 tph. Cyclone overflow from the grinding circuit is fed into a flotation circuit for the recovery of lead, zinc and silver. Two concentrates are produced (lead and zinc), which are then thickened and filtered. The filtered concentrate is transported by road to a rail receiving station. From here the concentrate is railed to port in Townsville for shipment to the smelter. Matrikon and Engineers at BHP Billiton?s Cannington Mine have used ProcessACT to develop a flexible, nonlinear dynamic simulator for the grinding circuit to further enhance process understanding, as well to investigate various optimization strategies. An online charge volume estimator was also developed for the AG mill to aid in the understanding of overload conditions, which for the previous two months had been the primary contributor to downtime. The models were developed using a combination of first-principles modeling along with input-output dynamic responses. Examples of models used include: Morrell ?C? model for power and charge shoulder/toe angle prediction; Whiten?s mixing model for breakage and hold-up; Nageswararao cyclone model for predicting cut size; slurry recovery and water recovery. The composite model simulates system dynamics starting from the stockpile reclaim system and finishing at the feed for the flotation process. The objective was to provide a tool that assisted Cannington in understanding their Grinding Circuit and allowed them to develop and evaluate circuit optimization strategies. BHP Billiton Cannington Mine is now considering development of a Grinding Circuit Optimizer utilizing the models developed for the simulator.

Apr 1, 2005

By Ben Bradshaw

Context ? Community engagement has become an increasingly significant and challenging part of mineral exploration and mine development; indeed, opposition from communities proximate to a proposed mine site has been known to derail technologically- and financially-sound projects. ? These cases suggest that mining firms need to better understand how to engage constructively with local communities in the pursuit of their claims. ? While a range of publications exist promoting various community engagement strategies, these recommendations, when viewed as a whole, are disjointed and largely untested in real development contexts. Aims of Presentation 1. Synthesize industry, NGO, government and academic publications focused on community engagement best practice in order to highlight those practices that are most commonly recommended. 2. Review the (Canadian) mining industry?s experience with some of these strategies based on existing case material in order to identify the extent to which commonly prescribed strategies are used and validated in practice.

May 1, 2010

By T. Belem

The main objective of this study is to better understand the effect of underground CPB placement conditions on its microstructural, hydro-mechanical and geochemical properties. To reach this objective, three PVC columns, each 3 m high, were built, and were filled with CPB material. The columns allow simulating undrained (UD), half-drained (HD) and fully-drained (FD) conditions along with the measurement of resulting self-weight consolidation settlement of the CPB. Bleed and drainage waters were also collected from each column for geochemical analyses (pH, Eh, EC, SO42- content). After 90-days of curing time, a total of sixty CPB samples were cored from the backfill columns and subjected to uniaxial compression tests followed by physical characterization (Gs, void ratio, water content, degree of saturation, specific surface area). The results showed that the total drainage water and the maximum observed settlement occur mainly within the first 72 hours after the columns are filled. The corresponding volumetric strains suggest that in situ backfilled stopes simulated behave in a similar way to the fully-drained (FD) or the half-drained (HD) conditions. The MIP test results show that the pore structure varies between the top and the bottom of each column.

May 1, 2007

By Lian-Jin Tao

With fast development of China modernization, road construction obtains great achievement. However, in the construction process of highway, especially the high-grade highway in mountainous area, there are many unavoidable high cut slopes. Specifications for Design of Highway Subgrades, China, prescribe that the design scheme of slope with height more than 30m should be compared with bridge scheme and tunnel scheme economically. In spite of the existing guidelines, it is still quite common to see many high slopes due to engineering geological conditions, highway line shape, cost and issues related to traditional design ideas. Actually the traditional way with ?high backfill, the high cut? for mountainous highways seriously damages the original ecological environment and groundwater system, especially to those area with weak ecology, where the damage is unrecoverable. It is quite common practice to use artificial vegetation for cut slope virescence, however it still has problems such as low ratio of survivor, high maintenance cost and lack of species diversity. Now people are more and more aware of the importance of ecological environment, it becomes urgent to decrease the damage to ecological environment after ensuring the stability of high slopes. With the aim to reduce ecological damage, we proposed a new design approach which is ecological environment friendly by decreasing cut slope height with steep excavation scheme. This approach requires that (1) the geological condition is good, and the rockmass can be sTable itself; (2) excavation should not badly damage the rock, which means blasting must be controled by using buffer blasting, smooth blasting and pre-splitting blasting; (3) if local geological condition is not very good, excavation should have intervals for one bench, the advised space is 20m; (4) to ensure the slope stability in construction process, the cut slope should be reinforced more strongly than usual and in time. Finally, the deformation of the slope and the working condition of the reinforcement structure should be monitored to ensure the slope stability. The new design is used to a roadside cut slope of provincial trunk highway S223 in Guangdong Province. Based on intensive geological investigation and borehole tests, it is found that the slope rock mass is intact and sound, and the rock strength is quite high. Results from numerical modeling by UDEC reveal that compared with the traditional design scheme with 90.23m high slope, the steep scheme with only 23.46m high is characterized by its relatively large deformation and stress concentration, however the influenced area only appears at the upper slope and tends to sTable. With cable reinforcement, the stability of slope excavated steeply can be guaranteed. Deformation of the slope and the cable force are monitored in details in the period of construction, which show that the deformation of the slope decreases gradually and the final deformation is very small, and the cable tensions change small after the cables were tensioned. It is optimistically estimated that the steep slope should be sTable during operation. Comparison analysis between the steep scheme and the common scheme affirms that the steep excavation is better than the traditional scheme in terms of ecological environmental effect, slope height, the excavated amount, the excavated quantity of slope surface, engineering cost. It is concluded that if geological condition permits, the steep cut scheme should be used with better benefits.

May 1, 2009

By Brad Thrall

"Viceroy Resource Corporation of Vancouver, B.C. has recently developed the Brewery Creek Mine, an open pit heap leach gold mine 55km East of Dawson City in Yukon, Canada. Mineable reserves are 17.1 million tonnes of ore grading 1.45 grams/tonne, containing 24.8 tonnes (797000oz) of gold. Ore processing employs the heap leach technology using run of mine ore. 1996 highlights included construction of 158,000 m2 of leach pad, placing 1.9 million tonnes of ore at a grade of 1.46 gpt on to the leach pad, construction and successful commissioning of the ADR plant, and pouring of the first gold bar on November 15th.Permitting this mine has drawn significant attention because the heap leach technology, while proven in other jurisdictions, has not been used in Yukon where winter site temperatures routinely reach -45 C for extended periods.IntroductionFollowing a comprehensive governmental and public review of the proposed project, a Class A Yukon Water license was issued in August, 1995. Construction started in 1995 and leaching commenced in October 1996. The Brewery Creek Mine is in Yukon, the home of the Klondike Gold Rush nearly 100 years ago. This is the only part of Canada not glaciated in the Wisconsin advance so there is oxide ore resulting from about 80,000 years of weathering -unique in Canada. Discontinuous permafrost is present on site and has required special consideration in the design. Winter temperatures dip below minus 50 C, demanding an approach to mining and leaching that is different than in more temperate climates.Project DescriptionThe mine comprises 8 shallow, largely oxidized gold deposits along a 7km corridor. An 8 year mining program will extract 17.1 million tonnes of ore grading 1.45 grams/tonne, containing 24.8 tonnes (797,000 oz) of gold. The strip ratio will be 1.35: 1. Overall gold recovery is projected at 78%. There will be 2.3 million tonnes of ore placed on the pad annually, with an average of 2.57 tonnes (83, 000 oz) of gold recovered per year. Because of the cold winters, the mine will operate approximately 210 days per year, while the leaching process will operate on a year round basis. Run of mine ore is placed on the heap 150 days per year. The recovery process utilizes conventional sodium cyanide leaching , carbon adsorption, caustic desorption, and on-site smelting. Peak employment during mining is 145 and winter staff is reduced to 45."

Jan 1, 1997

By M. Massinaei, S. Abasi, M. Oliazadeh

Reliable measurement and control of the pulp-froth interface (froth depth) in the flotation columns is critical to achieve the desired metallurgical performance. Shallow froths result in a reduction of grade because of particle entrainment and deep froths reduce recovery because of the drop back of entrained and weak hydrophobic particles to the pulp zone. The cleaner circuit at Miduk copper concentrator consists of three parallel MicrocelTM flotation columns 4 m in diameter and 12 m in height. The interface level of the flotation columns is measured by two pressure sensors located at 1.4 and 2.4 m from the cell lip (in the collection zone). In this study the performance of the level detection system at different operating conditions was evaluated. A calibrated float-ultrasonic location system was used for measuring the actual froth depth. The results indicated that the existing level control system was subject to considerable error. The absolute error was found to be 33.27 cm. This was mainly attributed to the constant set-point value assigned to the froth density (ρf=0.3 g/cm3), which actually varies with the operating conditions. The actual froth density at different conditions was calculated and its average value (ρf=0.12 g/cm3) was re-set in the control system. This resulted in substantial reduction in the level-detecting error. Recommendations for more accurate measurement of the interface level were presented. INTRODUCTION Froth flotation is a complicated process because of many involved variables. One of the most significant controlled variables in the flotation process is the pulp-froth interface (froth depth). The froth depth has a profound influence on the metallurgical performance parameters (i.e. grade and recovery). Shallow froths result in grade reduction because of particle entrainment and deep froths reduce recovery resulted from the drop back of entrained and weak hydrophobic particles to the pulp zone (Finch and Dobby, 1990). Various techniques have been developed for measuring the interface level of the flotation cells in the last few decades. These techniques can be classified as: Techniques based on hydrostatic pressure measurements (Finch & Dobby, 1990), Techniques based on the density gradient (float) (Moys & Finch, 1988), Techniques based on conductivity measurements (Uribe-Salas, 1991), Techniques based on temperature measurements (Moys & Finch, 1989).

Jan 1, 2019

By Mohammad Noaparast, Babak Fotoohi

"Due to certain advantages in (semi-)Autogenous-Ball mill circuits in most of the high-throughput ore grinding units of mineral processing plants, much attention is paid to optimize the mill performance. Despite the maturity of the grinding mill mechanical design, there had been made less attention to the efficiency of the grinding media in the past. In this research, the possibility of establishing a relationship between liner/lifter wear rate and variations in the composition of the iron ore (from Chadormalu mine) is investigated.Measurements and determination of liner/lifter wear rates and patterns concluded in recognition of critical liner segments exposed to much abrasion during the ore grinding. After metallurgical analysis of liner materials and correlation of wear rate with the ore composition, the homogeneity in the metallurgical microstructure of the alloyed steel (such as the uniform distribution and amounts of the constituent phases) was determined as the most influential factor in the response of the liner/lifter to the variations in the ore composition. Magnetite with greater abrasion index than hematite, in finer particles, is responsible for additional abrasion of liners; hematite with greater work index exists in the mill with larger particle sizes, thus it could produce wear on liner parts with less tolerance to impact as is the situation for martensitic steels.INTRODUCTIONThe mineralization in Chadormalu plutonic iron ore deposit is consisted of mostly magnetite, hematite, martite, apatite, quartz and carbonates. The average composition of the ore is presented in Table 1. In the processing circuit, the gyratory crushed ore reduced to 30 cm would finally be the feed to three similar 32’ semi-autogenous mills in parallel processing lines. The pulp in the mill would have the characteristics mentioned in Table 2. The quality of the mill output has its direct effect on the downstream processes either physically or chemically (e.g. in cycloning or flotation respectively). In order to take advantage of optimum performance for these circuits, a close control of the ore grinding conditions is necessary; because any shortages in throughput, liner/lifter damage or changes in ore composition could bring the unexpected casualties. In this work, it has been attempted to find (possibly) a reasonable relationship between variations in ore characteristics together with liner quality and the amount of wear rate in different liner/lifter segments of a semi-autigenous mill. Liner/lifter segments are supplied by three different domestic steel making companies. The alloy structure of the liners/lifters is made up of pearlitic chromoly steel."

Jan 1, 2005

By Peter Claus

In the last years, supported gold catalysts with particle sizes smaller than 10 nm have attracted a lot of attention. While gold bulk metal is rather inert in chemical reactions and, thus, is of low interest for catalysis, highly dispersed gold particles supported on oxides as TiO2 or ZrO2 show surprisingly high activities in some reactions important for the chemical industry. The oxidation of carbon monoxide at low temperatures is mainly used as model reaction to study the unusual properties of gold catalysts [1]. On the other hand, to evaluate the catalytic potential of gold, other chemical reactions which allow to control also the selectivity have to be considered. The selective hydrogenation of ???-unsaturated aldehydes to allylic alcohols is of both commercial relevance (e.g. in fine chemical and pharmaceutical intermediate production) and specific scientific interest [2]. Note that thermodynamics favors hydrogenation of the C=C over the C=O group (stronger negative free reaction enthalpy of 35 kJ/mol), and for kinetic reasons the C=C bond is more reactive than the C=O group. Thus, in the presence of most of the conventional hydrogenation catalysts, based on Pt, Rh or Pd, -unsaturated aldehydes such as acrolein and crotonaldehyde are hydrogenated predominantly to the saturated aldehydes and only to a minor extent to unsaturated alcohols. Therefore, it is desirable to find catalysts which are able to control the intramolecular selectivity by hydrogenation preferentially the C=O group while keeping the olefinic double bond intact (Fig. 1).

Oct 1, 2003

By Bruno Bussière

Le drainage minier acide (DMA) provenant de la circulation des eaux à travers les rejets miniers sulfureux est sans doute le principal problème environnemental auquel est confrontée l?industrie minière. Afin de prévenir les problèmes environnementaux reliés au DMA, on doit restreindre la présence de l?une et/ou de l?autre des principales composantes menant à la production d?acide, soit l?eau, l?air et les sulfures. Pour ce faire, différentes techniques ont été proposées au cours des dernières années, dont la désulfuration environnementale et les couvertures avec effets de barrière capillaire (CEBC). Dans ce papier, on propose d?utiliser ces deux techniques en combinaison. Ainsi, on produirait un rejet désulfuré à l?usine de traitement qui pourrait, par la suite, être utilisé comme matériau pour la couche de rétention d?eau de la CEBC. Dans un premier temps, on présente les résultats d?une étude de laboratoire qui montre qu?il est possible de désulfurer les rejets de concentrateur à l?aide de la flottation non sélective jusqu?à l?obtention d?un résidu non générateur d?acide. Par la suite, des essais en colonne ont permis de démontrer qu?il est possible de limiter la production de DMA d?un résidu sulfureux à l?aide d?une CEBC dont la couche fine est constituée de résidus désulfurés. Des prédictions théoriques estiment même que la présence de sulfures résiduels dans la fraction désulfurée utilisée comme matériau pour la rétention d?eau peut avoir un effet bénéfique en réduisant la migration d?oxygène. En effet, les sulfures contenus dans la couche de rétention d?eau peuvent consommer l?oxygène qui tente de migrer vers le bas et, ainsi, réduire les flux d?oxygène qui atteignent les rejets réactifs.

Nov 1, 2002

By Ron Board

"Probably the only thing that can he said about conveyor belt scales without fear of contradiction is that they have been responsible for as much or more puzzlement, argument and frustration than almost any other piece of equipment commonly found in ore processing facilities. To be sure, there are certainly a good number of satisfactory installations, some of these having been achieved through forethought and careful consideration in the early stages of plant design, while others seem to owl their success to what seems to be little more than good luck or white witchcraft; and it might also appear that black witchcraft or other gremlins are solely responsible for the poor performance of many belt scales that enjoy well-designed installations with apparently good operating conditions.This paper is intended to acquaint users with the major operational reasons why belt scales seem so fickle (and downright ornery too), and establish some reasonably simple test standards against which the performance of scale hardware can be measured. Then it shall be shown how the design flexibility of electronic scale systems can offer particular advantages in overcoming some of these everyday problems in a practical way, and without undue inconvenience to plant operations."

Jan 1, 1975

By C. A. Pickles, D. K. Xia

"In the last few decades, microwave energy has been widely employed in food processing, rubber and plastics curing, and in ceramic sintering. Recently, the application of micro waves as an energy source in extractive metallurgy has received considerable attention from a number of researchers. During the period from the mid-1960s to about 1988, the majority of the research was focussed on the behaviour of materials in microwave radiation. These research activities will continue to be important, since fundamental data on the interaction of microwaves with materials are vital for the successful application of the technology. Since1990, a number of potential applications of microwave processing have been investigated.These include: pretreatment of ores and concentrates, leaching, reduction, preheating of refractories, heating of slags and waste treatment. In this paper, the interaction of micro -waves with materials of interest in extractive metallurgy are reviewed and potential applications are discussed.IntroductionMicrowaves were first used in 1946 for the heating of materials, shortly after radar equipment was invented during the second world war. It was evident that microwaves were very effective for heating water and the technology was quickly adopted for drying and cooking. Since the introduction of the first microwave oven by Raytheon in 1952, many millions of domestic microwave ovens have been sold annually (National Research Council,1994; Atomic Energy of Canada and Voss Associates Engineering, 1990).In extractive metallurgy, microwaves are in the early stages of development (National Research Council, 1994; Atomic Energy of Canada and Voss Associates, 1990; McGill and Walkiewicz, 1987; Bradhurst and Worner, 1990;Peng et al., 1993). However, there are several reasons for the growing interest in the use of this technology in the field of metals extraction. These include the following potential advantages of microwaves: (1) rapid and selective heating of materials; (2) reactions can be catalyzed because the heating occurs on a molecular or atomic level; (3) clean and controllable energy source; (4) the gas volume is reduced and the atmosphere can be controlled as there are no gaseous combustion products; (5) the material is heated internally in comparison to external heating with conventional methods; (6)the temperature of the refractory can be minimized; and (7) the working environment is improved."

Jan 1, 1997

Material scheduling, sequencing planning and execution are the core tactical mine plan for achieving production targets that maximize the objective function of any mine production entity. This objective function is constrained by several exogenous and endogenous constraints including geological, operating, technological, marketing, financial, political, social and local field constraints. Linear and dynamic programming techniques have been used to formulate algorithms to solve the problems associated with scheduling and sequencing operations. These algorithms possess the mathematical rigor for dealing with the fundamental problems but they fail to provide adequate answers to random and dynamic process problems. Materials scheduling and sequencing are carried out within the bounds of random and dynamic fields. The functional relations between the output and dependent variables are random, and thus, current algorithms are limited in their abilities to address the problems arising from these random field processes. In this study a production simulator is developed to capture the random field process associated with materials scheduling and sequencing in an open pit environment. The algorithm incorporates a geometric pit evolution model, using solid geometry of an ellipsoidal frustum to capture material displacement dynamics. Taylor series expansion about the dimensions of the initial frustum is used to provide numerical solutions to the resulting partial differential equations governing the pushback dynamics. A production simulator, derived from the stochastic and dynamic models, is developed, validated and used to simulate the changes in the pit volume resulting from periodic incremental pushbacks and the random field process. The hybrid stochastic-optimization algorithm provides a powerful tool for addressing the random field and dynamic process problems. Combined with a hybrid stochastic-optimization dispatch system, tactical production planning and execution will be efficient and economic for achieving desired.

May 1, 2004

By Phil Thwaites

"The mining industry uses many types of mineral and metallurgical plants to produce saleable product from ore mined. Plant design history has left current operations with a mixture of manual operation and various forms of automated process controls. Consequently, we typically see high variability in the continuous operations together with a shortfall in the attainment of full capacity, or higher utilization of consumables.At a level of best practice, “Operational Performance Excellence” focuses on process control, using automation and control systems to deliver process optimization. This more sophisticated delivery is a great deal more difficult than the first stage of equipment selection / installation. It includes the appropriate selection of the right instrumentation, control system, key process knowledge, individuals with a solid control engineering background/experience, and the essential backing/ support of the operations management team together leading to higher value delivery. Robust solutions can be realized, considerably minimizing process variation, thus leading to process optimization. This approach results in an easier, efficient and safer process while providing considerable returns for the plant owners.How variable are your processes, and do you maintain optimized process performance with dedicated resources, modern instrumentation, ‘best practice’ control systems and performance monitoring tools? In this lecture, these questions and their possible answers are discussed.357"

Jan 1, 2013

By David H. Searle

This paper will discuss the common trends existing in various Canadian jurisdictions for the closure and reclamation of mines. Included will be a discussion of the requirement to post security as well as its form and how security is calculated and refunded. Reclamation can no longer be left to the end of mine life. Progressive reclamation must occur throughout mine life and must be part of the mine plan from the beginning.

May 1, 2006

By Rick Moignard

Relationships between Information Technology providers and their clients are often segmented according to job specific tasks. As a consequence, technology providers tend to focus on automating repetition and complexity, resulting in software that improves individual productivity while failing to address the interdependency of mining functions. For this reason, technology vendors like Gemcom are following partnership approaches with their clients, engaging corporate and operational stakeholders to better understand mining business objectives. This presentation examines some of the approaches that help foster the development of solutions that leverage the information produced during mine operations to improve downstream process control and tactical decision support.

May 1, 2006