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By A. I. A. Salama, M. W. Mikhail, R. J. Mikula

"The Coal Research Laboratory (CRL) of CANMET along with other research organizations in coal-producing countries envisage major benefits from computer applications in coal preparation, Some of these benefits are greater system flexibility, improved coal preparation plant performance efficiency and efficient utilization of manpower, all of which result in economic benefits. Computers can be applied for both on-line and off-line purposes; this paper focuses on the on-line applications from the process control point of view.A critical discussion of the different analog and digital process control systems is presented. Recent developments in Great Britain, West Germany, Poland and Australia on automation and instrumentation using on-line measurements of coal ash and moisture contents are identified.The CRL research and development strategy aimed at achieving on-line computer control of an automated coal preparation plant is presented.IntroductionIn the past twenty years an enormous progress in the area of computer technology has been noticed. Computer applications in industrial processes offer greater system flexibility, improved plant performance efficiency and efficient utilization of manpower. Significant computer control development in mineral processing has already been achieved. Although progress has been made in the area of computer applications in coal preparation, more effort is needed to utilize the full potential.The computer applications in coal preparation can be viewed as off-line and on-line. Considerable progress has been reported in the area of off-line computer applications, especially in the areas of modelling, performance evaluation/prediction and statistical analysis. However, only modest progress in on-line applications has been reported(1-7). This paper will focus on: online instrumentation and process control applications, different analog and/or digital control systems, on-line automation and instrumentation in other countries and CRL strategy toward pilot plant automation."

Jan 1, 1985

By Ron Davidson

"The Utility Mine in southeast Saskatchewan is owned by Saskatchewan Power Corporation and operated by Mana/ta Coal Ltd. Up to 3.3 million tonnes of lignite is supplied annually to Saskatchewan Power's Boundary Dam Generating Station. The coal occurs in two predominant seams which are covered by up to 37 metres of saturated fine-grained overburden. Overburden is removed by two draglines working in two pits. Coal is hauled to the mine mouth power station. Comprehensive drainage and reclamation programs are integral parts of the operation. IntroductionThe Utility Mine is owned by Saskatchewan Power Corporation and operated by Manalta Coal Ltd. It is located in southeastern Saskatchewan, approximately 200 km southeast of Regina and 8.5 km southwest of Estevan (Fig. 1). The climate of the Estevan area is semi-arid with long, cool winters and short, hot summers. The mean annual precipitation is 42 cm and the mean summer temperature is 20°C; mean winter temperature is -10°C. The Utility Mine supplies coal to the adjacent Boundary Dam Generating Station. Increases in the station's generating capacity during the past decade have resulted in an extensive expansion program for the Utility Mine. This expansion program, the geological conditions present in the area, and the mining/reclamation operations will be highlighted in the following sections<1.2). History The Estevan area has a long history of coal mining. In the early years, coal was mined via entries into coal seam outcrops along the slopes of the Souris River valley. Surface strip mining was introduced in the late 1920s and progressed to the point where it totally replaced underground mining by the 1950s. Surface mining methods are currently used exclusively by all of the Estevan area operators."

Jan 1, 1985

By D. M. Hausen

"Refractoriness in Carlin-type gold ores results mostly from fine locking of gold in pyrite, locking in various gangue phases, notably quartz, and a ""preg robbing"" condition attributed to organic carbon. All three conditions may occur in any given deposit, including Newmont &apos;s Carlin and Gold Quarry deposits in Nevada, where types of ref ractoriness occur locally in minor amounts.Measurements of specific gravity, water absorption and screen size distributions of gold in alteration rock types from Gold Quarry show transitional changes from siliceous cherts through decreasingly silicified and increasingly argillized siltstones.Low permeability of siliceous ores contributes to ""size dependent"" refractoriness in cyanidation test work. Colligative physical and chemical measurements demonstrate that silicified cherty ores are difficult to grind, poorly permeable, and less amenable to cyanidation. Refractoriness in pad or column leaching of coarsely crushed siliceous siltstones and cherts is shown to correlate with interrelated measurable mineralogic and physical parameters.IntroductionMetallurgical treatment of variably amenable and refractory types of gold ore may be guided by both analytical and mineralogic data on the interlocking of gold (microscopic an d sub- microscopic) in assorted gangue/sulphide phases. Most oxidized ores from the Carlin gold mine, north of Carlin, Nevada, are amenable to direct cyanidation. The permeability of most oxidized ores from Carlin coupled with the fine size of the gold < 1.5 um) yields rapid extractions and high recovery without fine grinding.Small portions of the Carlin ore body, and also the nearby Maggie Creek and Gold Quarry orebodies, are less amenable to cyanidation, and are classified as refractory. Refractory conditions may be attributed mostly to the association or interlocking of gold with pyrite and /or microcrystalline quartz or chert, and also by the adsorption of leached gold by deleterious forms of carbon, termed ""preg-robbing"" carbon. Each of these conditions are described and defined, with emphasis on a form of silica-locking, which has been referred to as "" size dependent"" refractoriness."

Jan 1, 1985

By Stanley G. Butcher

"The methods generally applied to predict performance and financially evaluate beneficiation options are reviewed.Typical costs f or a western Canadian thermal coal operation are examined. Preparation-from truck dump to loadout-frequently amounts 10 over a quarter of total minesite costs. Failure to achieve projected yield-whether caused by mine or plant problems-s-substantially increases production costs because more coal has 10 he mined to meet a specific market demand. Problem identification by mass/ash balances is recommended.Thorough characterization of the coal and associated waste materials and more reliable prediction of beneficiation process performance are therefore essential to determine a project &apos;s financial viability.IntroductionWestern Canadian coal prep a ration plant capacity is partway through a massive expansion program . In 198 1 potential product ion was 14 million tonnes, by 1985 it will be 26 million tonnes per year. Only two years ago the industry was concerned whether it could sustain this rate of growth to meet market demands : now with diminished market demand and lower coal prices being offered by our international competitors there are doubts whether t his potential will be fully employed , even by 1990.One direct consequence o f the occurrence of a variety of coals in a stunningly beautiful but complex geo logical setting such as the Rocky Mountains and their Foothills is that each project is unique. Coal is a low value per tonne product. To supply distant markets from geographically isolated deposit s necessitates expensive , dedicated , infrastructure . T o be profitable these operations must achieve eve ry advantage of the economy of scale.Each of the mi ne complexes commissioned in the 1970s experienced severe problems in the area o f co a l preparation . Most bought their way out , paying for major plant modifications by increasing the scale of their total operation . The current market recession may not allow new operations this route to profitability.The objective of this paper is to illustrate the economic impact of coal preparation problems on the profitability o f the total minesite operation and thus provide a sound basis for decision making process."

Jan 1, 1985

By David A. Grieve, David E. Pearson

"A rank-map of Crowsnest coalfield, showing the distribution of the bituminous coal measures and the locations of major structures, has been produced from vitrinite reflectance measurements on over600coal samples. The timing of coalification in relation to these major structures has also been determined.In the west-central portion of the coalfield a complete stratigraphic succession of coal measures which rides on major thrust surf aces is all of high-volatile bituminous rank, but despite the structural discordance no break in rank is discernible across these structures. The thrust faults therefore predate much of the coalification.Three major valleys expose cross sections of the folded coal measures and in each an increase invitrinite reflectance is demonstrable as individual seams are traced from ridge crest to valley floor. Thus, in these sections, a significant amount of coalification post-dates folding. The proportion of this post-folding coalification is found to increase toward the south of the coalfield.A late gravity-fault, exposed along the east crop of the coalfield, places high-volatile coal-bearing successions in contact with low-volatile coal and demonstrably is a reactivated thrust fault. Coalification at this locality occurred between these two different ages of faulting.The variations in rank and the subtleties of the coalification pattern have, together with systematic changes in the maceral composition of coal seams, had a profound effect on coal quality in the coalfield. Coking coals with a variety of properties occur together with some coals that have no caking capacity."

Jan 1, 1985

By J. Keith Haddock

"Introduction The Coal Valley Mine is operated by Luscar Stereo (1977) Ltd. with the Alberta Energy Company having a minority interest. The mine produces 2.0 million tonnes of bituminous thermal coal per year. Deliveries include 1.5 million tonnes to Ontario Hydro and 0.5 million tonnes to the export market via bulk handling facilities on the west coast near Vancouver, B.C. There are a number of mining methods utilized at the mine including open-pit by truck and shovel, strip mining with large draglines and stripping with scrapers. The mine is located 100 km south of Edson, Alberta. Geology The coal measures are concentrated within a 210-metre int~rval of the Paleocene section. The coal seams were originally named by the mining companies in the earliest days of development of the area and these names continue to be used today. Of the five main seams, only three are presently economic to mine based on quality, thickness and depth of cover. These are the Val d'Or, Upper Silkstone and Mynheer. The Coal Valley Mine is located in the structurally deformed foothills area of Alberta and the structure of each mining area is therefore very complex. The general bedding strike is 305 degrees azimuth but major thrust faulting and folding has extensively deformed the natural seams as a closer examination will show. The Mynheer Seam, located at the base of the coal measures, ranges in thickness from 5 m to 10 m and has numerous bentonite and shale partings. Because of inherent geological features, the Mynheer Seam has been subdivided into two zones, the Mynheer 'A' and the Mynheer 'B', and the mining of coal in these zones has necessitated the utilization of distinctly different mining methods. The structural regime of the Mynheer 'A' zone consists of an overturned asymmetrical anticline crest containing a steeply dipping major thrust fault which has raised the seam above the present topographic level. Further extensive shearing and rotation of the coal has resulted in the coal taking a 'pod' shape. The Mynheer 'B' Zone is a continuation to the southeast along strike from the Mynheer 'A' Zone. The bedding dips to the southwest at an average of 12 degrees and is interrupted at the south end by a transverse fault and to the north by its outcrop at the surface."

Jan 1, 1985

By G. Swan

"The selection of material comprising a backfill is, of economic necessity, site dependent. Nevertheless, given the existing range of typical components-coarse waste, alluvial sand, tailings a balanced or optimal choice is no straightforward matter. A new design approach toward deciding what constitutes an optimum combination of backfill material promises to be useful. In particular a &apos;binder &apos; number, based on the mean distance between aggregate particles, specific surface and cement content, is proposed. Using this number, related empirically to compressive strength, the expected mechanical performance of any cemented fill can be predicted.IntroductionOver the years a considerable volume of information has accumulated on mine backfill material design. The principal aggregate component has been deslimed mill tailings, though more recently admixtures of rock waste, sand and tailings are quite common. For these materials uniaxial compressive strength and percolation rate properties are known to be controlled by, among other things, aggregate grading. While empirical formulae exist for relating grading to percolation rates, considerable uncertainty exists concerning strength development."

Jan 1, 1985

By F. J. Munn

"Since 1976, Cardinal River Coal s Ltd. has completed mining in eight pits. In each of these pits, at least one wall has failed, none by design, although not totally unexpected, yet there was no loss of production nor risk to personnel or equipment. Cardinal River Coals Ltd. has been successful in implementing a program to cope with failures and now feels justified in adopting more optimistic design parameters.The wall control program at Cardinal River Coals Ltd. is based on the premise that the walls are going to fail, monitoring is to confirm when. The program consists of monitoring slope movements and piezometric levels as well as structural mapping and visual inspections. In case of excessive movement, the frequency and intensity of the monitoring is increased. If a failure is impending, suitable remedial action is undertaken such as cutting down the crest, building up the toe, depressurization of the wall, artificial support, or a combination of the above. If remedial action is not possible, monitoring permits operations to continue up to near the time of failure.At the design stage, the emphasis is on identifying the potential failure mechanisms and the con sequences of failure. Once the potential failure mechanisms are identified, a monitoring system can usually be employed to give sufficient response time, and providing the consequence of failure is not severe and/ or remedial action can be taken to arrest the movements, then it is practical to mine pit slope s which have a higher probability of failure."

Jan 1, 1985

By J. Keith Haddock

"Introduction The Boundary Dam Mine is located 5 km south of the City of Estevan, Saskatchewan and is operated by Manitoba and Saskatchewan Coal Company Ltd., one of the Luscar companies. The entire production of 1.7 million tonnes per year is delivered to the Boundary Dam Generating Station of Saskatchewan Power Corporation. Geology There are basically two seams mined on the property, the main Estevan seam ranging in thickness from 3.0 m to 4.5 m with partings and the upper Roche Percee seam (roughly 15 m to 23 m above the Estevan) which ranges from 0.6 m to 2.0 m in thickness. Most of the reserves are concentrated in the Estevan seam, the Roche Percee only being mined whenever its thickness makes it economic to recover. The coal measures belong to the Ravenscrag Formation of Tertiary (Paleocene) Age. This formation is widespread in North Dakota and Montana and contains the lignite fields of North Dakota and subbituminous coals of Montana. The formation is gently tilted to the southeast at Boundary (0.5 degrees) and consists of weak sandstones, siltstones and silty mudstones. Reserves and Coal Quality The present minesite encompasses a coal reserve of approximately 50 million tonnes calculated to a maximum stripping depth of 37 metres or 20:1 mining ratio. The reserves form only a part of the total reserves in the Estevan area which are owned by the Saskatchewan Power Corporation. The coal being mined is classed as Lignite ""A"" and has the following specifications:"

Jan 1, 1985

By John D. Campbell

"IS YOUR MANAGEMENT CONTROLLOOP FUNCTIONINGMineral processors make use of hundreds of control circuits in their mills, process plants, smelters and refineries, to optimize throughput and recovery and minimize cost. This afternoon, I would like to discuss what is probably the weakest circuit in any mineral processing operation - the management control loop.In their recent book ""The Winning Streak"", Goldsmith and Clutter describe extensive research on unsuccessful companies. They conclude that ineffective control, which does not immediately identify the problems, is one of the main failings of unsuccessful companies.We will look at the three key components of control which, from the manager's point of view, ensure that the loop is complete. These three are:• measuring what's happening,• assessing its significance, Rnd• altering performance.If we compare management control to process control as shown in this first figure, ""We see that parameter sensing by the analyzer in a process circuit is analogous to performance monitoring by management in a responsibility centre. The analyzer senses temperature, pressure, flow, weight or some surrogate indicator such as colour to indicate ion concentration. For manage1nent, the performance to rnonitor is dependent upon the objectives of the responsibility centre, and the key factors which affect these objectives."

Jan 1, 1985

By N. J. Duncan

"Coal mining, whether surface or underground, has hazards that make it unique in the field of industrial safety and health. The often soft, faulted and folded sedimentary strata make wall or roof movement a risk to the safe and economic removal of the coal, while the extraction and handling of coal may create an explosion hazard even in surface operations, In Canada, these problems are compounded by the situation of the coal fields which range from deep undersea deposits in Nova Scotia to steeply pitching thick coal seams high in the Rocky Mountains. Climate too can create its own problems, particularly the effect of metals of minus 40°C temperatures, as crumpled dragline booms at prairie strip mines witness. Because of the difficult and sometimes hazardous conditions, Canada's underground colliery managers, in common with those of other Commonwealth coal-producing countries, must have a government ""certificate of competency"" before being appointed as mine managers. Certification of assistant managers (""under-managers"") and foremen (""fire-bosses"") is also a legal requirement for all of Canada's underground collieries, while the province of Alberta requires certification of surface management personnel. Electricians and mechanics who install and maintain the specially designed equipment underground and in hazardous areas of surface mines and processing plants, and mine surveyors who ensure accuracy of the location of underground workings, must also hold government certificates of competency. The requisites for all certification include a minimum work experience and knowledge of coal mining technology and mine safety and health legislation. Despite recognition of the hazards and increasing knowledge of methods of preventing explosions of flammable gas and coal dust in Canada's underground mines, there have been several disastrous explosions such as those at Springhill Colliery in Nova Scotia in 1891 with the loss of 125 lives, at Hillcrest Colliery in Alberta in 1914 with 189 dead, and more recently · explosions and fires in No. 20 and No. 26 Collieries in Cape Breton. Preventing explosions has required developing optimal ventilation techniques, reducing ignition potential, suppressing ignition at source, draining flammable gas before it can enter the air courses, and preventing, or sealing off, autogenous heatings with their associated carbon monoxide or explosion dangers."

Jan 1, 1985

By C. Mills, A. O. Burt

"The paper examines the role of gravity concentration in both an historical context and within the modern mineral processing industry. It discusses the principles of the process on both a theoretical and practical level. The importance of more mineralogy and its effect on the choice of the wide range of equipment available is discussed. The paper concludes with a discussion on the relative merits of gravity concentration with other forms of processing.IntroductionIt is an unfortunate, albeit popular, misconception among otherwise enlightened engineers in the mineral processing industry that gravity concentration was a process developed in the dark ages, perfected in the middle ages, and abandoned in the modern ages.Gravity concentration was developed in the dark ages - long indeed before that. Agricolau: cited examples of gravity concentration, crude examples admittedly, being practiced over 3000 years ago. However, gravity concentration is not dead. Far from it. As recently as 1978 it was reported that the total mineral tonnage treated by this process in the United States was greater than that processed by flotation. Coal represents the bulk of the or e treated by gravity separation in the U.S.A., with iron ore representing a major portion of the balance."

Jan 1, 1985

By Ken Musgrave

"What Most Effective Management Does?It must satisfy the demands, of three groups of people: owners, employees and the public.OwnersOwners want profitable operations that will pay them a return on their investment, plus operations managed for long life. Many owners are also concerned with employee&apos;s well being and their company&apos;s public image.EmployeesJob security and a good income are probably still the most important demands, however, as time goes by, employees are also demanding more involvement in safety issues, working conditions, and even how work is done.The PublicThe public requires acceptable environmental standards, as well as enjoying the prosperity supplied by a successful operation.How are Mines Managed?Most mines are managed very traditionally. The basic credo is that the managers make the decisions, and the hourly, and junior salaried employees do what they are told. Clearly this is the extreme case, epitomized by the long service shift boss who might say ""It took twenty-years to become a shift boss, and no miner is going to tell me what to do"" .There are some exceptions, two notable ones being Campbell-Chibougamau, and T.G.S. (now Kidd Creek Mines) which, in very different circumstances, decided on a more participative style.Campbell-Chibougamau, having closed down due to unprofitable operations, reopened, using a team structure with working leaders, and a system for sharing gains against cost targets with employees. Although the system has some problems, and development miners are bonused conventionally, this has been a basically successful program.Texasgulf Sulphur, a company with a history of non-union operations, and a participative management style, made a corporate decision to operate their Kidd Creek Mine in the same way. The orebody was rich enough to allow them the luxury to do this, but they have never had a strike, so perhaps they have more than saved the cost of the benefits and salaries they needed to pay. They also reward employees with a stock distribution scheme based on service and earnings."

Jan 1, 1985

By J. G. Mieczaniec

"A key element for a successful mining operation is the grinding circuit. It must be reliable, maintainable and must perform to or above design capacities for 95% of the time. Once chosen and installed major modifications are either prohibitive or very expensive. The selection of mills and drive system is probably the single most important decision made within the concentrator complex.Economic studies revealed that the optimum expansion for Lornex was a 68070 increase in plant throughput. This indicated that the new mill would have to be larger than the existing 32-foot mills.The Lornex ore has a wide range of hardness which has a great influence on mill throughput (Table 1). To smooth out the fluctuations, a blending program ha s always been in effect at the mine, coupled with ball charge control for the primary mills. As can be appreciated, an optimum balance is difficult to achieve. A sudden change to so ft ore with a high ball charge puts the mill into jeopardy with a constant speed drive.The blending philosophy would continue after the expansion, but with the addition o f a second primary crusher, it was envisaged to have the new mill process harder ore to maintain production targets. In theory, the new mill would have a proportionally larger ball charge than the existing mills.This scheme makes the new mill vulnerable for processing so ft ore for a fixed speed mill. Thus, variable speed seemed an attractive option.In early 1979 prominent mill manufacturers were invited to submit proposals for the new mill. Fixed and variable speed mills were to be considered with mill size ranging from 32-foot to 36-foot diameter. The proposals were to include the drive, ball charge, % critical speed, couplings, gears, etc. - the complete package. The recommendations were variable with most manufacturers submitting several alternatives. Recommended mill speed varied from 68% to 78% critical. The concept of variable speed was becoming more attractive, Lornex ultimately decided on a twin DC motor drive system for a 34-foot diameter mill.After start-up it was discovered that best throughput occurred at 78% mill critical speed or top speed of the drive motors. The motor speed range was adjusted upward from 186 to 200 rpm. Today the mills operate at 79% critical or a motor speed o f 193.5 rpm.Clearly the selection of the variable speed mill allowed the flexibility to optimize throughput."

Jan 1, 1985

By Paul L. Broughton

"IntroductionThe coal deposits, all of lignite rank, of economic interest in Saskatchewan are associated with the Ravenscrag Formation (Paleocene). Several Cretaceous formations have less significant lignite accumulations (Broughton, Irvine and W'hitaker, 1974). The Swan River Group (lower Cretaceous) and Judith River Formation (upper Cretaceous) have the only coalbearing strata in the shallow subsurface of central Saskatchewan. The Swan River Group coalfield is relatively small and underlies only 15 sq km of the surface approximately 40 km south of La Ronge, Saskatchewan. An estimated 36 billion short tons are within 45 m of the surface. No reserve estimates are known to have been calculated for the coal-bearing Judith River Formation exposed at the surface in the vicinity of the South Saskatchewan River valley in west-central Saskatchewan. Although no coalfields have been delineated, lignite beds up to 1.8 m thick have been intersected in test holes. The coal-bearing upper Cretaceous and lower Tertiary strata of the northern Williston Basin extends the full width of southern Saskatchewan for 650 km, and from the United States border 120 km north to 50° latitude (Fig. 1). Only the coalfields of the Ravenscrag Formation, because of their economic interest, will be considered further. There are four major coalfields. They are, from east to west: Estevan, Willow Bunch, Wood Mountain and Shaunavon (Cypress) coalfields. Cumulative lignite seam thickness for each basin is 10 -15 m (Figs. 2 and 3). The origin of each coal basin, resource calculations, seam stratigraphy, and mining activity are discussed. Regional Setting The Williston Basin is an ellipsoidal depression in the Precambrian basement, centered in western North Dakota and marginal to the exposed craton of northern Saskatchewan and central Manitoba (Fig. 1). The sediments of the basin range from Cambrian to Pleistocene in age and have a maximum known thickness of 4614 min western North Dakota. A maximum of 3200 m is recorded in southern Saskatchewan. Most structural deformation is late Cretaceous to early Tertiary (Paleocene) in age, coinciding with the Laramide Orogeny. The pre-Laramide Williston Basin, with a depocenter near Williston, North Dakota, began developing during the middle Ordovician, or possibly earlier."

Jan 1, 1985

By B. V. Knelson

"GENTLEMEN:This paper will deal with centrifugal separation - theory and practical, and since the Knelson Concentrator is the only centrifugal concentrator with a properly fluidized bed, this paper will cover the Knelson Concentrator and its technical and structural advances over the last five years. As I am the person with the most experience in this line, I guess I am some kind of an expert; what kind I’m not sure, but some kind.This type of concentrator truly was developed because I’m lazy and I constantly look for easier ways to do things. My experience in the mining industry was very limited but I did realize in looking at placer operations, which is the application where I spring from, that it was tremendously labour intensive and my first reaction that ""my god, there must be some method or way-of handling product in a more efficient (and you can read that as being able to quickly recover very fine particle gold) way than was being shown at that time"". So, the Knelson Concentrator was born - about 6 or 7 years later. Our first attempt was a cone with about the same degree of slope as our present machine and since we had no knowledge of vibration dampening and centrifugal forces at that point, it was just an idea that this should work.Our first run was one of twenty minute duration. We did make that first machine variable speed by a mechanical belt system and we found that at about 240 rpms we were virtually shaking the gravel plant apart that we were attached to. So the first run was twenty minutes and back to the drawing board. However, that first run produced a concentrate so superior to anything we had seen previously, that we knew without any question, we were definately and accurately on the right track."

Jan 1, 1985

By Peter J. Franklin

"Short-term mine planning of open pits is an activity that has historically been carried out by hand. Typically, the use of computers has played little part in this type of mine planning. This paper describes the objectives and the procedures involved in short-term mine planning, comments on the type of computer systems available, and describes in detail a computer-aided short-term planning and scheduling system known as STEPS.IntroductionThe mine planning department of any o pen-pit mining operation performs a wide variety of different tasks. However, their primary concern is the preparation of detailed long-and short-term mine plans. These mine plan s will define the long-term operating strategies and definitive everyday working plan s for the ongoing development of the open pit.In this day and age, when operating costs have spiralled upwards due to inflation , and product revenues have decreased due to depressed economies and poor markets, it is vitally important for all aspects of the mining operation, including mine planning, to be efficient and cost effective.There are numerous options available for planning engineers when generating a mine plan. A cost effective mine plan must investigate all these options and select the optimum. When using manual planning techniques, it is often impossible to evaluate all the available options. To do this, and to produce an optimum mine plan, a computer is required.This paper discusses mine planning, with emphasis toward the short-term plan and comments on how the processes may be computerized. It also describes in detail, a computer software system called STEPS, which has been designed as an interactive graphics, computer-aided short -term mine planning and scheduling tool."

Jan 1, 1985

By P. G. Keohane, J. S. Drake

"Cominco&apos;s Polaris Mine is a lead-zinc underground operation that began commercial production in early 1982. The mine site is located on Little Cornwallis Island in the Canadian Arctic at a latitude of 75°23&apos;N and at a longitude of 96°55&apos;W. The nearest settlement, Resolute Bay, some 100 kilometres southeasterly from the mine, is accessed from the mine by light aircraft. The mine site can be accessed by sea during the six-week ice-free period each year. During this time all major operating supplies are brought to the mine and the lead and zinc concentrate products are shipped out to market.GeologyThe Polaris orebody lies near the top of the Thumb Mountain Formation of Ordovician age. This formation is a relatively homogeneous section of thin to medium bedded limestones which are brecciated and dolomitized in the area around the orebody. The deposit is described as a Mississippi Valley-type orebody. Ore minerals are sphalerite and galena with the waste being predominantly dolomite with calcite and marcasite. The ore is quite porous with voids being generally filled with ice as the mineralized zone lies entirely within permafrost. Reserves consist of about twenty million tonnes of ore grading 3.8% Pb and 14.3% Zn with a further three million tonnes of inferred ore at a slightly lower grade.The orebody strikes in a north-south direction with the hangingwall dipping at about twenty degrees to the east. It is generally conformable with the stratigraphy. The footwall in the western portion of the orebody, the Panhandle, lies about 10 to 30 metres below the hangingwall. To the east the footwall drops sharply, creating an orebody height of up to 110 metres in what is referred to as the Keel Zone. The Panhandle Zone has typically 80 - 110 metres of cover above the hangingwall , About 25% of the reserves are in the Panhandle Zone, the remainder being in the Keel Zone. Figure I illustrates a plan view of the orebody relative to other surface facilities on the property and Figure 2 illustrates a simplified section through the Panhandle and Keel Zones."

Jan 1, 1985

By T. Patching

"THE FOLLOWING notes on coal mining in the Edmonton city area are based, in the main, on scattered reports and accounts as little coal mining has been done in this area for about 20 years and few people are left who were involved in what was at one time an important industry of northern Alberta. Although coal mining is not likely to be permitted in the city area itself in the future, a record of this work is warranted to indicate the ·conditions and problems that may be encountered if underground mining again is proposed in the district in the same geological formations and in similar strata. Coal mining in the Edmonton area developed with the influx of settlers in the latter part of the nineteenth century and the first part of the present century. Probably local coal was used by the Fort's blacksmith as early as 1841, and the early settlers probably were 'gopherholing' into the outcrops along the river banks by the 1870s. The first report of commercial coal mining was in 1880 when a contract was let by the Hudson's Bay Company for the provision of 300 tons. As the population in the city and northern parts of the province grew, many new mines were opened along the river and in the district, and coal was even shipped by barge to points in Saskatchewan(1 ,2) By 1909 the Department of Public Works reported that 'Edmonton stands as the second largest domestic coal producing centre in the province'. It continued to hold this position until 1942. From about 1912 to 1951 annual production from mines in the city and surrounding district ranged between 0.38 and 0.65 million tons, depending on weather, wars and strikes. Production began to decline in 1951 because of the increasing availability and consumption of natural gas which was piped into the city and then provided to other towns and rural areas in the northern part of the province. Taylor noted that between 1880 and March 1970, when the last mine within the city area closed, the total of mines and prospects within the Edmonton city area rose to 153. Most of them were small; not more than 20 produced more than a quarter of a million tonnes during their entire life, and only three produced a million tonnes or more. As described by Taylor ""within the city district workings extend discontinuously from the apex of a narrow triangle near Groat Bridge to the base of the triangle in the Clover Bar area"". The larger mines were in this latter area. Approximate locations of the old mine workings in the city are shown in Taylor's atlas. A number of other coal mines were worked in the Rabbit Hill, Big Island, St. Albert, Namao, Cardiff and Morinville districts around the city."

Jan 1, 1985

By W. M. Scheding

"There has recently been a resurgence of interest in unit flotation of mill discharges. At the Kidd Creek concentrator, this technique has been successfully applied to silver flotation in a 3050 mtpd silver-copper-lead-zinc division. The major incentive has been improved silver payment through increased overall recovery and better distribution between the sequential copper, lead and zinc concentrates. A large, but variable fraction of the silver in the ore is present as native silver and, being dense and malleable, is susceptible to overgrinding. Grinding circuit surveys showed high concentrations of silver in both primary and secondary circulating loads. Laboratory testwork confirmed that this was selectively flotable, identified the secondary ball mill discharge as the best feed stream and optimized flotation conditions. A 10 t/h pilot plant campaign confirmed that the rate of accumulation of silver was sufficient to sustain continuous production of a silver concentrate and that flotation of the whole stream was not necessary.The present 30 t/h production circuit recovers from 5 to 50% of the silver in the ore at a concentration ratio between 25 and 250. The circuit also contributes to a better understanding of ore mineralogy, as an 'on-line' indicator of elemental silver content."

Jan 1, 1985