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By G. Bimpilas, G. N. Anastassakis

"Today, one of the most intense problems in mineral processing systems is referred to the treatment of fine (–100 µm), and even smaller size, particles. Fine mineral particles possess specific properties (small mass, high specific surface area, and high surface energy per unit area) that render their separation inefficient with conventional methods (physical, physicochemical) and equipment. As a result, it is not feasible to obtain a concentrate both of high grade and recovery in mineral value and a considerable amount of mineral fine particles is lost to the tailings. As evidence, we could cite numerous examples from industrial practice with considerable loss of mineral values to the tailings because of the fine particles size, e.g. phosphate, tungsten, tin, etc.The objective of the current paper is to investigate the possibility to separate magnetic gangue minerals and rocks (serpentine, ilmenite, and olivine) from magnesite by co-agglomerating all the gangue components and subsequent magnetic separation of the agglomerates.To meet the target, hydrophobic agglomeration tests were initially carried out on single minerals to define the favorable conditions for selective hydrophobic co-agglomeration of the gangue minerals. In this respect, the effect of the following factors was examined: pH, collector dose, conditioning time, and settling time of the agglomerates. Among the combinations examined, the most favorable proved that with amine in the basic pH region. The use of non-polar oil proved beneficial. The preliminary results were confirmed by tests on mineral mixtures. The application of magnetic separation resulted in the removal of gangue minerals and the recovery of magnesite concentrates of commercial grade (magnesite content 95% approximately) and high yield.The current paper contributes to the development of mineral processing, since it successfully copes with a very important problem of mineral processing, such as the efficient separation of fine particles."

Jan 1, 2016

By Rae Simpson

"This paper provides insight into the elements of computerized maintenance systems and identifies some of the factors which influence their effectiveness. The paper describes what to expect in terms of benefits and problems, the nature of effective computerized maintenance systems, some of the systems available and a process for selecting a system for your organization.The paper will be of interest to mining company executives and maintenance or computer personnel who are involved with, or contemplating, the introduction of computerized maintenance systems.IntroductionIn the drive to improve profits in an increasingly competitive world, mining companies are now using some of the most sophisticated equipment available. The introduction of large and complex equipment such as drag lines, haul trucks, and high-capacity milling equipment has resulted in order-of magnitude improvements in productivity. However, this productivity is now, more than ever, dependent on the continued operation of the equipment. A prolonged breakdown of a critical component can have a significant effect on companies' bottom-line results. As more technologically sophisticated equipment is introduced, maintenance costs become an increasingly important factor for mining companies.Fortunately, sound modern management principles are being used more often in maintenance departments. Progressive maintenance managers are turning to computers to help manage the myriad of details associated with running a maintenance organization.Some maintenance departments in larger mining operations would find it difficult, if not impossible, to operate at current productivity levels without their computer systems. Unfortunately, some other companies gain very little from their computerized systems and would probably be better off without them.How can you be sure that computerized maintenance will improve the maintenance picture for your company? What benefits can you expect to achieve? How do you go about selecting a maintenance system for your organization? These are some of the questions facing industry managers and executives today. In the following sections, we will provide some guidelines and insights to help address these challenges."

Jan 1, 1988

By J. Peck, M. J. Scobie, M. D. Pollitt

"IntroductionOne aspect of current research in the Canadian Centre for Automation and Robotics in Mining (CCARM) involves the automatic identification of different rock types based on particular drill performance parameter responses. In this paper, the four drill performance parameters of torque, pulldown pressure, rotary speed and penetration rate, were measured from an instrumented rotary blasthole drill during field investigations undertaken at the Fording River Mine, Elkford, British Columbia. The variations in these parameters were subsequently correlated with the corresponding rock types using the results from gamma, neutron and core logs in the same or adjacent boreholes. Work to date has sought to understand the relationships between drilling performance parameter variation and rock properties. Using the results of these studies, the present research is aimed at developing techniques whereby classical statistical pattern recognition methods are applied to drill data to permit the discrimination of different rock units. A monitoring system incorporating such a capability would greatly enhance the quality and amount of geological information on a per borehole basis while drilling. This data in tum could be used economically and directly towards explosive loading, geological exploration and reserve estimation. Background and PhilosophyThis work is an extension of equipment monitoring studies at the Fording River Mine. At this site over a two-year period, 5180 m of data was acquired on an instrumented Bucyrus-Erie 60R drill during routine production blasthole drilling. Throughout these studies, a 311mm diameter S8M Security tungsten-carbide tricone bit was used. The mine, located in southeast British Columbia, is a large-scale, open pit coal operation. The means of excavation revolves around a drill-blast-muck cycle and employs a standard shovel-truck system of transport. Four main rock types are present: sandstone, siltstone, mudstone and coal, with average compressive strengths ranging from 10 MPa to 150MPa respectively (peck 1989). However, based on the field studies, very few differences in terms of strength and compositional properties were seen between the sandstones and siltstones at the site. Therefore, they are referred to as sandstone/siltstone in all further discussions."

Jan 1, 1991

By A. L. Holloway, N. M. Soonawala, L. S. Collett

"Since the late 1970s, a major R&D program has been under way in Canada to assess the concept of disposing of nuclear fuel wastes in deep plutonic rock. Atomic Energy of Canada Ltd . (AECL), a federally-owned corporation, has been given the responsibility of directing this research (Rummery et al., 1983).The Underground Research Laboratory (URL), constructed in a granite pluton 15 km east of Lac du Bonnet, Manitoba (Fig. 1) is a major component of the Canadian Nuclear Fuel Waste Management Program. A diverse geotechnical experimental program is being carried out during both the construction and operating phases of the URL. This program involves detailed geological mapping, rock mechanics and hydrogeology studies, and geophysical surveying, to characterize the rock mass surrounding the shaft, and it has been described by Simmons et al. (1983). As part of the construction-phase program, ground-penetrating radar (GPR) surveys are being carried out during excavation, in an attempt to delineate fractures both ahead of the excavation and behind the walls of the excavation. This paper presents the results of surveys performed during shaft excavation and describes a procedure for plotting the data.Ulricksen (1982) cites examples of radar surveys to evaluate surficial deposits, such as peat, sands and gravels, and cavity detection in subsurface hard rock. Fowler (1981) used radar for fracture and clay vein detection in coal seams.In Canada, pioneering work in GPR has been done by Annan and Davis since the mid-seventies (Annan and Davies, 1976). Their work concentrated on problems relating to permafrost in the Arctic ."

Jan 1, 1986

By Robert B. Parsons

"Thrashing one's way through a jungle of entangled tax rules is no easy task today, as Canada's legislators continue to complicate this country's income tax laws. At some magical point, there is presumably some balance to be struck between legislation which is equitable and unambiguous on the one hand, and at the same time is efficiently complied with and administered. It is becoming increasingly clear that the legislation is not in balance, and that there is a pressing need for some simplification of the income tax rules and regulations especially in areas of critical importance to the resource industries-even though such simplification will likely involve some sacrifice of equity and certainty.Introduction""I would wish that ... the superfluous and tedious statutes were brought into one sum together, and made more plain and short, to the intent that men might better understand them."" Edward VI, King of England 1547-1553.Regal decree notwithstanding, the legislation of most developed nations continues to become more complex, lengthy, and confusing than ever before. Canada's income tax system cannot escape the accusatory finger pointing at examples of this serious problem which plagues all of us today.Although many areas of our tax law could easily warrant some degree of simplification, for those who are involved with this country's resource sector, that horrendous, almost unreadable, part of our tax legislation which deals with resource taxation must be regarded s a prime candidate for simplification. In recent decades, but particularly in the past ten years since tax reform in 1972, budget after budget, both federal and provincial, have amended, massaged, modified, and manipulated the resource tax rules to the point where not only are taxpayers totally lost in their attempts to make some sense of the entanglement of rules, but also the draftsmen themselves acknowledge that the outer limits of complexity are being reached, and that the whole set of rules is on the verge of grinding to a groaning halt under its own weight of nonsense and frustration."

Jan 1, 1982

By E. M. De Souza

"A scientific testing program, sponsored by the Mining Industry Research Organization of Canada (MIROC), was undertaken on the surface and underground facilities of Inca's Crean Hill Mine to investigate the effectiveness of using dry drilling with a dust control system.The surface test work consisted of the monitoring of advance rates and bit life white a series of 165 mm holes, wet and dry, were drilled at both mine air (0.69MPa) and high pressure air (1.72MPa). The results, based on statistical evaluations of field data, indicated that penetration rates can be increased by an average of 24% when drilling dry with high air pressure and by approximately 27.5% when drilling dry with mine air as compared with wet drilling under the same conditions. Dry drilling also has the effect of reducing button wear by approximately 69% using high pressure air. The underground test work employed a dust collection system developed for use with large diameter holes (165 mm) and high pressure drilling. The testing program has indicated that an average increase in penetration rate of 35% can be achieved when dry drilling in rock (waste) and of 49% when dry drilling in ore with high air pressure. Although preliminary dust monitoring did not indicate any appreciable increase in dust concentration during dry drilling, further dust monitoring is still required.A comparative cost analysis has indicated the potential for reduction in drilling costs when dry drilling is utilized. Further testwork is to be conducted to develop a reliable dust collection system for underground production."

Jan 1, 1992

By W. H. Hodgson, A. R. Preston

"Improved rail production techniques provide new options for the rail user. Steelmaking improvements offer tighter composition control, lower oxide and sulphide counts, greater control of segregates and freedom from hydrogen problem s. New ultrasonic, laser and eddy current equipment gives printout information on surf ace flatness, straightness and internal condition. These have come along at a time when dramatic changes have occurred on the rail heat treatment scene. Rails can now be deep hardened on or offline in ways which should eventually result in a complete rewrite of the world's specifications. Rails of simple composition can be produced in the hardness range 2801400 BHN as required. The rail user can choose the hardness within this range according to requirement without the necessity for any step changes in the process routes.It is suggested that this is the pattern f or the next decade.IntroductionRails have been the subject of very slow improvement over many years but developments gathered momentum in the early seventies. Recent improvements in quality and properties have provided dramatic increases in rail life under the more severe service situations. Rail profile grinding, lubrication and other track improvements have greatly added to expectations of even longer life. All of this, coupled to even newer mill heat treatment developments, tilt both technical and economic advantages away from tradition to the point where specifications will need to be rewritten so that railroads can take full advantage of these new products."

Jan 1, 1988

By Peter Harben

"This paper discusses the benefits of industrial minerals, their sources of supply, price and marketing trends, and their increasing use as substitute materials and ""strategic"" minerals. IntroductionKaolin finds have yet to spark the kind of frenzy associated with the 1849 California gold rush; no dolomite deposit has ever gained the notoriety of the Comstock Lode; and few industrial minerals are counted among the currently fashionable list of "" strategic mineral s"". Nevertheless, the glamorous zhine associated with metals may be somewhat superficial; further digging provides perhaps the real foundation of modern society - industrial minerals.They are often tagged as common, everyday materials that are simply dug out of the ground, crushed and hauled to a local point of consumption. Although this description is accurate in the case of road aggregates, sand and gravel, and the like, there are many exceptions to this rule. The term industrial minerals is rather nebulous, covering as it does the mundane and esoteric, the chemically active and the refractory, the $2 and the $10m-a-ton product. All of these minerals influence every facet of modern life from fertilizers to fire retardants, ceramics to cars, construction to clothes, and toothpaste to tennis courts. Their usefulness is well illustrated by the variety of industries they serve; the main ones are listed in Table 1. It is now time to dismiss the notion of non-metallics as the ""third world"" of natural resources business after the metallic and energy products by dispelling some of the myths regarding abundance, variety and value of the group's sixty-plus products."

Jan 1, 1982

By A. Piche, J. Nantel

"This paper describes the recent developments in Canada toward the establishment of a Canadian Centre for Mining Automation and Robotics, at McGill University and École Polytechnique in Montreal. The role of the Mining Association of Canada (MA C) and of the National Advisory Committee on Mining Automation will also be reviewed. IntroductionIn order to remain competitive, the mining industry must increase its productivity and reduce its costs. In the last two decades, this objective has been achieved through mechanization. From now on, any further improvement in productivity will be gained through increasingly more automated mining equipment.Recent international developments following the Versailles Economic Summit in June 1982, having given rise in Canada, to a renewed interest in applications of robotics and automation to mining.The mineral industry in Canada is at a crossroads. Competition in emerging from everywhere: lower grade ore bodies, increasing distances between viable mines and markets, third world massive production of certain commodities, substitution of "" space age"" materials (ceramics, plastics, composites, etc.) for metals.On the positive side, it is generally believed that present mineral commodities, i.e. base metal, gold, iron, industrial mineral s, etc ., will continue to be in high demand for centuries to come despite substitution. New applications for conventional metals will be found and the enhancement of certain properties of these conventional metals mean continued demand. For some mineral commodities, there will never exist an y substitute."

Jan 1, 1988

By J. R. Meyer, P. L. Dean

"The Department of Mines and Energy is at present investigating the dimension-stone potential of the Nain anorthosite complex. These rocks are known to host occurrences of labradorite, a semiprecious gemstone known for its beautiful play of colours (chatoyance). Test blocks that contain 5% to 18% chatoyant labradorite were extracted from three prospects south of Nain. These have been slabbed and polished for further evaluation.Second-grade labradorite stockpiled around the Grenfell quarry on Tabor Island is also being evaluated as a potential source of aggregate for use in terrazzo tiles, precast concrete and epoxy-backed wall panels.IntroductionThe Nain anorthosite complex consists of approximately 10000 km2 of anorthosite and related basic rocks , which are well exposed along the coast of Northern Labrador (Fig. 1) (Emslie et al., 1972). These rocks have been known for centuries to host deposits of gem-quality labradorite. The chatoyant nature (i.e. the play of colours or labradorescence) of this semiprecious feldspar has been utilized mostly in the making of jewelry and other polished, handcrafted products. In the early sixties, Brinex Limited (now Brinco Limited) attempted larger scale commercial exploitation of labradorite, including use 'as building stone and in polished precast concrete for facings on buildings' (Brummer, 1984). After six years of work, which included market studies, Brinex decided that, at that time, the demand did not warrant further production.In recent years, there has been a dramatic increase in the markets for dimension-stone. In the period from 1980 to 1985, the demand in the United States for granite, much of which is imported, has increased 1735070 (Marble Institute of America, 1986). The dimension-stone industry's remarkable growth rate has, in part, resulted from new technology that makes it easier and faster to quarry and cut stone. This has allowed natural storie to compete with other building materials. Now, it is not only used for exterior cladding and walkways, but also on interior walls and floors, and in home and office furnishings, such as countertops for kitchens and bathrooms, table and desk tops, stairways, window sills, and fireplaces."

Jan 1, 1988

By L. Dekker

"In 1979 Chevron Standard Limited and Irving Oil Limited intersected a thick, high-grade sylvinite zone in the Windsor Group in the Chevron Irving Malagawatch No. I well in central Cape Breton. This well was the third and final hole of a program designed to evaluate a non-commercial oil discovery made by Chevron Standard's Mineral Staff in 1978 while carrying out base metal exploration. Nine holes were subsequently drilled to evaluate the significance of the potash discovery. The delineation drilling proved the Malagawatch structure to be complex with the potash zone showing erratic grade and thickness distribution. Based on the drill information the potash accumulation at Malagawatch is uneconomic, however, other salt ""structures"" in the Bras d'Or Basin may in time prove to have better potential.History of DiscoveryIn 1972 Cuvier Mines discovered the Gays River lead-zinc deposit (MacEachern and Hannon, 1974) which prompted Chevron Standard's Minerals Staff to carry out a study of the Windsor basins in Nova Scotia (Figs. I and 2). As a result of this program several carbonate-hosted lead-zinc prospects were identified in the basal Windsor carbonate; one of these was at Malagawatch on Cape Breton Island . In 1978, after preliminary exploration surveys, a diamond drill program commenced consisting of 5 BQ holes (Fig. 3), three of which tested the basal carbonate. Instead of the reefoid bank facies of the Gays River Formation (Giles et al., 1979), the favoured host for economic base metal mineralization, this carbonate was developed as a laminated, pelletoidal, lime packstone more characteristic of the facies equivalent Macumber Formation (Schenk, 1967). While drilling one of these holes, No. 3-78, oil scum was intermittently detected on the drilling mud. The hole was abandoned at 191 m in anhydrite, without having reached the basal limestone."

Jan 1, 1985

By W. Evans, C. E. Ells

Nuclear power reactors using zirconium alloy pressure tubes generate electricity in several countries. Such reactors are particularly important in Ontario, where CANDUs* generate about 30% of the total electricity produced in the Province. Starting with the commitment of NPD-2 in 1956, the pressure tubes of the first five CANDU reactors were made of coldworked Zircaloy-Z, an alloy of Zr and Sn. This alloy was developed by the US Navy, but the decision to use it in a cold-worked condition was based on AECL work. In 1958, the USSR published information on a new alloy, Zr-2.5 wt% Nb. The Nb promotes stabilization of the (3-phase in the material, thus presenting opportunities of exploiting metallurgically strong pressure tubes analogous to the heat-treatable cx-{3 titanium alloys. After construction of two reactors using Zr-2.5 wt% Nb in a quenched and aged condition, an extensive development program on cold-worked Zr-2.5 wt% Nb pressure tubes resulted in them becoming the reference tubes for all CANDU reactors committed since 1966. Anticipating the future needs of the domestic and export markets, AECL have pressure tubes of Zr-3.3 wt% Sn-0.8 wt% Nb-0.8 wt% Mo (Excel) in an advanced state of development. These tubes will be used in an annealed condition; our projections show that they will have improved dimensional stability over the lifetime of the reactors. These improvements result from experimental programs leading to an understanding of the relationship between microstructures and fabrication variables and effects of the environment during service in nuclear reactors.

Jan 1, 1981

By K. J. Brouwer, J. P. Haile

"Construction of the first stage of the tailings disposal facility for the Montana Tunnels Project was completed in October 1986. The project is located 37 km south of Helena, Montana, and involves mining of42 million tons of weathered diatreme are at a rate or 13 500 tpd to produce a gold/silver dore, as well as lead and zinc concentrates. The tailings disposal facility for the project includes a fully drained tailings impoundment for storage of the tailings solids, and a process waterpond for storage of all decanted water prior to recyling to the mill. The over-all facility is designed to achieve the basic objectives ofminimizing seepage to the environment in the short- and longterm, and achieving a fully drained stable tailings mass suitable for immediate reclamation on completion of mining. Specific features of the design include a soil bentonite seal and drainage system within the tailings basin, a free draining embankment with a design flow-through capacity of 4000 US gpm and an ultimate height of 230 ft (70 m), and a soil bentonite lined make-up water pond with a capacity of 420 acre-feet (530 000 m'). The tailings will be discharged in a rotational sequence through multiple spigot offtakes to achieve a thin-layer low energy laminar flow. This 'sub-aerial' deposition results in higher stored densities and maximizes liquid-solid separation on the tailings beaches. The over-all design played a major role in the successful permitting of the project, and was significantly cheaper than a conventional wet disposal system, with overall unit costs for tailings disposal of less than US$0.36 per ton.This paper outlines the site characteristics and the tailings material properties and their influence on the design. Extensive use was made of naturally occurring free draining materials as well as bentonite modified soil liners within the tailings basin, embankment and retention ponds. General construction procedures for the various components are described, as well as on-going construction requirements utilizing materials from the open pit. Finally, the over-all costs and unit costs for tailings disposal are presented."

Jan 1, 1988

By J. R. Pronovost, P. M. Tiley, D. W. Watts

"In 1980, J.S. Redpath Limited were retained by Dickenson Mines Limited to increase hoisting capacity from 700 to 1000 tons per day. The hoisting capacity of the present skip-over-cage system could not be increased significantly through design modifications. The other constraint was a minimum of disruption to the current production. The Dickenson shaft was a three-compartment shaft from surface to the 8th level and four compartments before the 8th to the 23rd level. The solution to the problem was to remove the services from the shaft man-way compartment from the 8th level to surf ace by drilling a borehole close to the shaft and rerouting those services through the borehole to the 8th level. A service compartment would then be available from surf ace to the 23rd level.By providing a service hoist in this compartment, the skip hoist would then be free to produce the 1000-tons/day required production. This paper will describe the search for the required hoist and the friction hoist selected for the project, and trace the design modifications required to modify the hoist to suit the Dickenson application and satisfy the Department of Labour safety requirements.The paper has been co-authored by J.S. Redpath Limited and C.L. Tiley Associates, who participated in the design changes and eventual commissioning of the hoist.IntroductionIn the earl y part of 1980, J.S. Redpath Limited conducted an engineering study on the Dickenson Mines Limited No. 1 Shaft materials handling system. The object of the engineering study was to investigate the possibility of increasing the tonnage hoisted from the No. 1 Shaft complex by adding a service cage compartment and service hoist. This would permit utilization of the existing hoisting plant solely for production hoi sting. A further consideration of the engineering study was that any alterations had to be accomplished with little, or no, interruption to production."

Jan 1, 1982

By P. K. Chatterjee

"The operations of a large-scale open-cut mine are simulated to produce a user-oriented interactive digital model. SIMULA is chosen as the programming language and a sophisticated data base system is designed to consider the complex information network of large mines. The main features of the program are the mine planning and mine evaluation modules. These modules are responsible for the computation of truck-shovel performance and other equipment details in a mine. Stochastic methods are employed to generate event times. The use of a Data Base Management System and the data base provide an efficient method of information storage and retrieval. Truck allocation techniques have been examined in detail and comparisons between random dispatching and conventional methods are made. The model is intended for mine operators and engineers and the program is well structured and very readable. It is hoped that these features will make the model readily acceptable.IntroductionThe Department of Mining and Metallurgical Engineering at the University of Queensland has been conducting research into computer simulation methods in mining since 1972. The research has been mainly applied to actual operations, with both open-cut and underground mining being equally emphasized. The results of the research to date have not only strengthened the methodology of the approach to complex mining problems, but have also increased confidence in the use of modelling and computer simulation technique s in mining.The model described in this paper translates a complex LHD situation into a user-oriented interactive digital model using SIMULA. The present methods of evaluating truck dispatching and trolley assist are tedious and laborious. This model provide s the engineer with readily acceptable means of rapidly assessing the relative merits of these techniques in a large-scale open-pit operation. Poor utilization figures in many current operations (for example, 40% for trucks, 70% for shovels) are of serious concern to mine officials and computer-controlled dynamic truck dispatching systems have been considered by some of these mines to improve equipment utilization ."

Jan 1, 1981

By Richard Cyr, Peter Larsen, William Quesnel

"The need to continually improve efficiency and lower costs in mining operations is of paramount importance to all concerned in the industry. Mining operations are constantly testing new methods and equipment in order to lower costs and improve productivity. Equipment suppliers strive to fulfill the demands of the mines through improved design and innovative ideas for productivity increases. In some cases, however, an increase in productivity does not require new equipment design, but rather the application of an existing mining method into different operating parameters. Such is the case in applying longhole methods to narrow vein ore deposits.Bulk mining methods have long been recognized as efficient, low-cost alternatives in narrow vein operations. Typically, shrinkage and some cut-and-fill methods are employed. The shortfall of these methods is the tendency to be labour intensive. The demand for miners skilled in these methods far outweighs their availability. Consequently, labour-efficient methods have to be employed to fill the void. The application of longhole drilling techniques to narrow vein deposits is one such method.IntroductionPercussion longhole drilling evolved in Canada in the early 1940s. Prior to percussion drilling, blast holes were drilled using diamond drill equipment. Jack Gardner, of Gardner Steel, began testing with carbide percussion bits and extension drill steel in applications where diamond drills had been previously employed. Percussion drilling equipment proved to be considerably more productive and cost-efficient. The experiment eventually led to the replacement of diamond drills in this application.Over the years, the percussion methods were improved, with particular emphasis on the equipment used. Rifle bar rotation machines evolved to independent rotation. Bar and arm set ups evolved into self-contained mobile drill carriers that increased productivity while reducing the physical labour. The introduction of hydraulics further improved efficiency and production figures. Today, it is not uncommon to see fully computerized jumbos in production longhole drilling applications. These machines represent the ""state-of-the-art"" in longhole drilling equipment.Production longhole drilling is considered to be one of the most efficient bulk mining methods in use today. Production statistics normally exhibit low-cost, efficient ore extraction. As a rule, longhole (blasthole) methods are associated with substantial ore deposits. These methods have exhibited high production figures and low mining costs.Over the past decade, long hole methods have been applied to several narrow vein deposits. These applications have proven that, given the right parameters, longhole methods will produce the same advantages in narrow vein deposits as are seen in more conventional applications."

Jan 1, 1990

By P. O. Rag, Daniel E. Walsh

"Gravity concentrators are evaluated either in closed or open circuit. The process developed by MIRL employs the use of neutron activated gold (/98Au) and radiation detection circuits which monitor the concentrator's product pulp streams. Concentrator recovery is determined from the ratio of the number of gold particles detected as passing into the concentrate to the total number of gold particles detected over all monitored pulp streams. This system eliminates the experimental errors introduced by sampling, sample reduction, and assaying and allows recovery to be evaluated for gold particles of specific sizes, shapes, and flatness. In addition to allowing for a more accurate and detailed recovery analysis, this process significantly reduces the time and cost required for unit evaluation when compared to other gold recovery analysis procedures. This system enjoys its greatest utility where a large number of tests are to be run in order to evaluate a concentrator over a variety of operational settings, i.e. factorial designs, and allows accurate testing of concentrators operated in closed circuit systems.IntroductionThe surge in gold prices of the late 1970s and early 1980s was followed closely by a renewed interest in gravity concentration processes, especially in concentrators claiming efficient recovery of fine placer gold. Cones, spirals, spinning bowls, jigs and cyclones are all considered potential fine gold concentrators. Fine gold, in this context, is defined as not only that gold finer than 250 um (60 mesh""), but also coarser gold, whose low shape factor may decrease its recovery by conventional, large-scale sluicing operations.Adoption of fine gold concentrators by the Alaskan placer milling industry was retarded by the lack of reliable, accurate, and reproducible data on concentrator efficiency with respect to fine placer gold recovery. In most cases, concentrator performance was based on a limited number of tests run on placer material, about which only slight knowledge of gold size and shape characteristics existed. In order to be prepared for the resurgence of interest in fine gold concentrators, which will follow the next upturn in gold prices, a detailed study of the fine gold recovery characteristics of gravity concentrators needs to be conducted."

Jan 1, 1986

By R. Frank Chiappetta, E. B. Wilson

"The maintenance records for AL-60 airlegs at Falconbridge Ltd. are used to demonstrate some of the procedures for the analysis of such data.The data are not representative of pure failure s of one type or another. In fact, the records are for the undefined pseudo-failures which are usually found in industrial operations. However, because the machines are brought to the shop only when inoperative, the individual recorded components are treated as failures. Manual calculations are conducted to show the analysis of variance (ANO VA) approach to determine whether certain data can be combined; only a limited number of the 206 machines being considered. The manual procedures continue with the weighting of the suspensions; i.e. terminations f or reasons other than the failure of the given component. After the data are sequenced in the proper order, the nature or pattern of the data is determined using the Kolmogorov-Smirnov (KS) test.It is recognized that these manual examples must be replaced by compute r methods 10 process voluminous data of this nature. Such programs are developed and available. However, a program called RELCODE is used in this case to correspond to the manual examples and to take into account the suspensions. These analytical procedures form the basis for those studies required for good maintenance management."

Jan 1, 1985

By P. L. Lehoux, R. F. Lopes

"Unanticipated low recovery or extraction of gold from heap leachable are can often be attributed 10 phenomena such as non-uniform percolation (channelling) of solution through heaps, excessively slow percolation rates due to densification of ore during stacking on the pads and parasitic or competing reactions of the cyanide solution with undesirable elements or geochemical ""impurities"" in the ore. The nature and causes of these phenomena are discussed in this paper, and it is suggested that geotechnical and geochemical expertise can contribute significantly to a better understanding of the relationship between laboratory results and actual field performance of the leaching process. Recommendations are made for bench-scale metallurgical testing to be complemented by geochemical and geotechnical laboratory evaluations, to ensure more successful heap leach projects. IntroductionHeap leaching is a simple, low-cost method of recovering metals from low grade ores which has now come into widespread application particularly for gold and silver metals in the United States.The heap leach process involves percolating a lixiviant (leaching agent) solution through broken or crushed ore (Chamberlain and Pojar, 1984). In the case of gold a dilute sodium cyanide solution is used and crushed ore is ""heaped"" on specially prepared impervious pads.The potential for use of heaping leaching methods for northwestern Ontario gold deposits was discussed by Beard (1983), who suggested that the use of this extraction technique in Canada should grow significantly for low grade ores as well as for small high grade deposits which cannot justify the installation of a new mill or the use of remote custom milling facilities. Two other potential situations for lise of a heap leaching extraction method are : as a low capital cost cash generator in the opening phase of a larger new project, and as a low cost output augmenter to complement a milling operation."

Jan 1, 1989

By Y. Prevost, D. Verhelst

"A computer-assisted process control system for the Noranda Process Reactor Wa5 installed at the Home smelter in 1991. Operating as an advisory tool for the furnace operators, and using a flexible oxygen balance as the basic building block of the computer program, the new control system has helped to reduce the variability in the grade of the matte produced by 50% . The smelter is currently operating at a 72% copper matte, with a standard deviation of between 1.0 and 1.3, while treating a wide range of concentrates, secondary materials and scrap. Enhanced process control has allowed for longer reactor campaigns, and improved stability of the converting operation.This paper reviews the feed classification and blending practice used at the smelter, outlines the strategy of the new computer control system, and summarizes the benefits realized since the implementation of the system in early 1990.IntroductionUntil 1989 the Noranda Home smelter operated as a multi furnace smelter, at one time having three hot-charge reverberatory furnaces, and finally operating with one wet-charge reverberatory furnace and one Noranda Process Reactor. In 1989 the final reverberatory furnace was closed and the Reactor became the sole smelting vessel, treating around 750 000 tonnes of concentrate, secondary materials, and scrap per year. At the time of the start-up of theNoranda Reactor in 1973, the vessel was capable of treating 750tonnes per day of a heterogeneous mixture of copper concentrates, fluxes and secondary materials to produce copper in one operation. Through process improvements, and the introduction of additional oxygen in 1982(pannell and Mackey, 1988), the daily tonnage increased to 1800 tonnes by 1988. The operation had also been changed to produce a high-grade matte instead of copper. Figure1 illustrates the main features of the reactor, a cylindrical vessel which is charged at one end and tapped at the other. The matteis subsequently processed through Peirce-Smith converters and anode furnaces before being cast into copper anodes. Figure 2 outlines the progressive increase in the furnace smelting capacity. Over this period the percentage of secondary materials, and scrap feeds also increased to approximately 110 000 tonnes per year, or 15% of the total new feed input (Bedard et al., 1991). Now operating wholly as a custom feed operation, the Home smelter can treat over 2200tonnes per day of new metal-bearing material."

Jan 1, 1993