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By The Hollinger Mill Staff

MR. E. L. Longmore (l), in presenting this paper at the Annual General Meeting, suggested that it was neither desirable nor necessary to read any but the briefest portion of the paper. He wished to emphasize that the scale of the milling operations at the Hollinger not only provided several units in continuous operation to ensure that the test work was being carried on under normal conditions, but also provided a large and competent staff to supervise such an extensive experiment and to criticize intelligently the recorded results. He wished to acknowledge the enthusiastic co-operation of the group of assistants whose excellent work was responsible for the confidence with which the conclusions could be presented. The following data were given as a supplement to the published paper. Following conclusion of the test work described in the paper, the size of the balls fed to the mill was changed from 3-in. diameter to 2Yz-in. Within a short time, a gradual rise in the tonnage rate took place and, as no other condition had been changed, the increased tonnage was credited to the changed character of the ball load. At present, the average daily tonnage for the mill with low discharge is 1,507 tons, an increase of 77 tons over the 1,430 tons ground when feeding a 3-in. ball. A similar increase in tonnage should be credited to the high-discharge test, if the 2;Y2-in. ball had been used at that time. This would raise the 1,117 tons ground at that time to a new figure of 1,177 tons. From a study made to determine those factors influencing the rate of pulp flow through the low-discharge mill, it became evident that the ball screen used on the high-discharge mill must have been restricting the flow through the mill, although this was not recognized at the time. Accord-ingly, it was decided to repeat the high-discharge run. Additional length was added to the 21-in. ring grizzly originally used, and the length of the reverse spiral was increased. The end of the grizzly was left open so that, if necessary, excess pulp might flow out. A coarse mesh 3 ft. by 3 ft. flat screen was provided to catch stray balls.

Jan 1, 1937

By Gianni Bartolacci, Patrice Nadeau, Szatvanyi. Gerard, Carl Duchesne, Claude Chrétien

"Combustion is used throughout the mineral processing industry to produce steam in boilers, to dry concentrates in rotary dryers, and to apply heat treatments in pyrometallurgical furnaces. Tight combustion control is very important in latter type of furnace since the combustion conditions directly affect final ore quality. However, achieving tight combustion control is not straightforward since most of the flames encountered in industry are turbulent non-premixed flames, they are affected by several unmeasured disturbances and are often produced by burning several types of fuel simultaneously, some of them coming from other parts of the plant. A novel method is proposed in this paper to improve process and product quality control as well as to optimize the combustion conditions based on digital flame color images. Multivariate Image Analysis and Regression is to used extract the flame color characteristics from images to predict the solids discharge temperature of an industrial rotary kiln. It is shown that this method yield extremely good 10 minutes ahead forecast of the temperature and should lead to a substantial reduction in product quality variability as well as in fuel consumption.INTRODUCTIONFuel-fired furnaces are often used in the mineral processing industry for various purposes, such as for the production of steam (utility boiler), in conjunction with rotary dryers to dry mineral concentrates or in pyrometallurgical processes for induration, roasting, and so forth. These furnaces are necessary in the supply chain from the mine to the metals, but their operating costs are constantly rising due to the fluctuations in fuel prices. Moreover, these processes are now targeted by the Kyoto Protocol since they are energy intensive and they produce significant amounts of CO2 and other pollutants such CO, NOx and SO2. To achieve both a reduction in operating costs (i.e. fuel consumption) and in pollutant emissions while maintaining or improving product quality, one needs to have a very good control of the combustion process."

Jan 1, 2005

By George R. Pratt

Although the title of this paper focuses attention to the Winnipeg coal market the following remarks should be considered applicable not only to conditions in Winnipeg but to the whole western coal industry. Technical descriptions of coal and coal-burning have been omitted. These details are already covered in other numerous publications. In discussing a market the first consideration must be the product which is required to be sold. The class, quality and price at the point of origin must be taken into account and therefore this feature will be discussed before proceeding to outline conditions in the Winnipeg local market. The writer thinks of coal as a manufactured article, not, as it is generally considered, a fuel to be dug from the ground and dumped into the consumer's bin. The work of manufacturing must be considered in detail:- 1. Consider first the coal as it is in the ground: (a) What is its fuel value? (b) Where is its market? © With what will it be in competition? 2. Consider secondly: (a) What it will cost to mine the coal. (b) What has to be done to prepare the coal for market after it is mined. This must be considered in conjunction with the answer to question 1 ©. 3. Thirdly, consider the method of business to be adopted by the producer:- (a) Is it proposed to build a market on price? Or (b) On quality?

Jan 1, 1925

By Nick Poushinsky

OVERVIEW OF PRESENTATION ?Stantec?s Northern Presence ?Challenges for Northern Development ?Environmental Approval Challenges ?History/Expectations ?Baseline Data ?Consultation ?Regulatory Processes ?Extra ?Regulatory ?Keys to Success

May 1, 2009

By D. Beneteau, D. Milne

"Advances in technology provide educators with valuable tools to enhance their teaching and efficiently deliver content to larger audiences. University educators are often encouraged to become more “research intensive” and to increase student enrollment. Faced with these pressures, there is a tendency to use technology to improve teaching efficiencies rather than to enhance existing teaching approaches. Practical learning in applied engineering courses would suffer greatly if hands-on experience is not emphasized. This paper discusses advantages and limitations of new technologies applied to learning, and methods to incorporate more hands-on experiential teaching techniques to applied mining engineering courses.RÉSUMÉ Les avancées technologiques fournissent aux éducateurs des outils intéressants pour rehausser leur enseignement et livrer efficacement de la matière à de grands auditoires. Les éducateurs universitaires sont souvent encouragés à devenir plus « axés sur la recherche » et d’augmenter l’inscription d’étudiants. Face à ces pressions, il y a une tendance à utiliser la technologie pour améliorer l’efficacité d’enseignement plutôt que de rehausser les approches existantes d’enseignement. L’apprentissage concret dans les cours d’ingénierie appliquée souffrirait grandement si l’accent n’est pas mis sur l’expérience pratique. Le présent article discute des avantages et des limitations des nouvelles technologies appliquées à l’apprentissage et des méthodes pour incorporer plus de techniques expérimentales pratiques aux cours de génie minier appliqué."

Jan 1, 2016

By R. A. May, P. J. Brooks, W. M. Smith

"Neill and Gunter Limited (NGL) has prepared a preliminary design and a cost estimate for a ferric chloride leach plant to recover copper, lead, zinc, and silver from a typical complex sulphide ore. This plant design is specifically intended to treat unconcentrated ground ore (flotation feed), but can be readily adapted to treat bulk concentrates. Samples of ground ore and bulk concentrate were obtained from Heath Steele Mines, Miramichi, New Brunswick, laboratory testing, and preliminary process flow sheet preparation was carried out by the Research and Productivity Council in Fredericton, New Brunswick. Approximately thirty drawings have been produced, including process and equipment flowsheets, process piping and instrumentation drawings, and preliminary general arrangements. Preliminary capital and operating cost estimates were prepared for a plant that would treat 1000 t/d of crushed and ground ore to produce about 30 000 tpy of zinc. Capital and operating cost estimates were also projected for plants up to 4000 t/d of processed ore. Recoveries of 99% for zinc, 98% for lead, and 96% for copper were achieved in laboratory tests on unconcentrated ore. These recoveries were higher than the overall recoveries obtained from bulk concentrate, yielding approximately 10% more revenue.A 1000 tonne per day plant was determined to have a low return on investment, however, depending on the size and type of mining operations employed and the FCL plant throughput. DCF-ROI projections of 20% to over 30% were calculated for 100% equity financed “green field” mine, mill and FCL plant operations of 2000 t/d and higher"

Jan 1, 1997

By O. Matwijenko

"1. IntroductionThe Falconbridge Owl Creek open pit gold mine is located 17 km northeast of Timmins and 2.5 km west of the Kidd Creek metallurgical site. Diamond drilling first commenced in 1964 with open pit production commencing in 1982. Other operations within close proximity are the Canamax-Pamour Bell Creek Mine and the Falconbridge Hoyle Pond Mine.Since 1982, 1,216,000 tonnes assaying 4.5 g/t have been processed in six concentrators. This paper summarizes the metallurgy achieved with special emphasis on some of the unique problems encountered in the processing of this refractory ore.2. GeologyThe Owl Creek deposit, located 3 km north of the Porcupine-Destor fault is in easterly trending carbonaceously altered volcanic and sedimentary rocks. The deposit strikes east and dips steeply north.The ore body can be best described as a wedge shaped sandwich of volcanic basalt between the surrounding sedimentary greywacke. The north and south volcanic-sedimentary interfaces are marked by graphitic zones. The south graphitic contact is more continuous with its thickness varying from 5 m to 20 m as compared to 0.5 m to 3 m to the north. Quartz veins occur throughout the deposit with a predominant vein running along the south contact where it is characterized by numerous graphitic inclusions. Some veins carrying gold values intrude into the sediments in the north. With depth the sedimentary and volcanic zones taper while the quartz-graphitic zones appear to become more dominant."

Jan 1, 1988

By S. G. Coultis

Turner Valley is in the foothills of the Rocky mountains, at an altitude of 4,000 feet, and is 42 miles south west of Calgary. The present producing area is 8 miles long by 1 1/2 miles wide, while drilling is being carried on over an area of 10 miles by 2 miles . There are 32 wells producing, 26 wells drilling, and 17 wells shut down, making a total of 75 wells, which range in depth from 2,160 feet to 5,900 feet, varying according toa the well location on the anticline centre wells being shallower than those located on the flank. The first indication of possible production in this field was a gas seepage on the banks of Sheep river, in what is now the Royalite plant yard (Figure 1). Geologically, this seepage proved to be located on an anticline running through the valley in a southwesterly direction. The Calgary Petroleum Products Company was formed in 1912, and under the direction of Mr. A. W. Dingman, President, and associates, the first well was drilled. Production was obtained in this well. Gas was found in several horizons from 884 feet to 3,960 feet, and oil at 1,557, 2,718 and 3,839 feet. In May, 1914, oil was struck at a depth of 3,839 feet, this being a light straw-coloured oil of 60 gravity, which was blown spraying from the well accompanied by three to four million feet of gas. The latter contained some 200 grains of hydrogen sulphide per 100 cu. ft., giving it the disagreeable odour so well known in Turner Valley gas. This strike caused considerable excitement and started the famous 1914 boom, when some 400 oil companies were formed. The well referred to produced from two to five barrels of 60 gravity oil per day, and 4,000,000 cu. ft. of gas. The oil was used in the crude form in cars and trucks.

Jan 1, 1929

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 N. N. Rulyov

"Starting from fundamental principles of colloid-hydrodynamic theory of disperse systems we have shown that application of strongly non-uniform hydrodynamic fields allows to achieve not only faster rates of flocculation of suspension, but also supports significant improvements in the quality of clarified water and separation characteristics of solid phase. Specifically, it has been experimentally proven that the new treatment method based on these principles (then termed as ""ultra-flocculation"") allows:•,Increase the output of thickeners and pressure filters by 1,5-1,7 times;•,Decrease solids fall through into the filtrate in the process of vacuum filtration by 2¬3,5 times;•,Improve the rate of purification of water phase in the upright thickener by 1,5-1,9 times;•,Decrease flocculant consumption by 1,5-3 times;•,Increase the effective operational life time of cloth filters by 3-4 times;•,Ensure sustainable operation of separation equipment, i.e. decrease the sensitivity of process to variation in suspension concentration, as well as to variations of suspension composition and dispersion characteristics;•,Apply flocculant solutions of concentration 2-3 times higher, thus increasing the capacity of equipment used for solutions preparation."

Jan 1, 2004

By G. V. Lewis

"INTRODUCTORY REMARKS""I believe we need to communicate as much as possible with the industry. I don't think that we should be a body that just goes around doing dust surveys and writing nasty letters. We should get together on these problems and try and solve them as a group. I've only been with the Department a little over 12 months. I haven't visited all of your plants. I've visited most of the major open pits and I have had a chance to observe a lot of problems that you have encountered and a lot of the problems that you have brought up this morning. I thought the best thing I could do is perhaps mention a few of the approaches to the problems that my superior has suggested to me and we have discussed in the Department, and then perhaps go over a few of the evaluating problems and what we are trying to do with our dust surveys and perhaps ways and means of improving the present setup."""

Jan 1, 1976

By A. D. Yell

"Recovery of water is always a major factor in the Beneficiation process. As Preparation Plants become larger the recovery of water for reuse, is a critical cost consideration. Tema Isenmann Inc in conjunction with our sister Company Multotec Manufacturing, has over the years, developed numerous different Screen Panels, Sieve Bends and Static Screens for dewatering. This paper will focus on a new innovation, the TeePee™ Panel which has double the open area of conventional Screen Panels. This results in efficient dewatering (reduced filter cake moistures) which allows for the use of smaller Vibrating Screens or increased capacity on existing Vibrating Screens. A major factor in the efficiency of any Screen Panel, including TeePee™ Panels, is the performance of the Vibrating Screen. If the Vibrating Screen does not have the required gravitational force or screen area to drain it will not dewater efficiently. Therefore a holistic approach has to be taken where the Vibrating Screen needs to operate at an optimal level, in conjunction with the correct Screen Panels, to achieve efficient dewatering. Key performance areas for Vibrating Screens are therefore detailed in this paper with an emphasis on important dewatering criteria. Case studies of different dewatering applications are included, where the use of TeePee™ Panels, has shown a marked improvement over conventional flat Screen Panels in reduction of filter cake moisture content.INTRODUCTION Dewatering can be done in a number of different ways and is largely dependent on the ore type, the particle size distribution and to what extent one needs to dewater will determine the method used. There are a number of different dewatering methods that can be used for particles above 200 micron, including Screen Bowl Centrifuges, Filter Presses, Static Screens, Static Sieve Bends and Vibrating Screens. This paper will focus primarily on Vibrating Dewatering Screens showing improved drainage and a reduction in the filter cake moisture content. KEY PERFORMANCE CRITERIAL FOR VIBRATING DEWATERING SCREENS For clarification the critical key performance criteria for Vibrating Dewatering Screens are set out in this paper. Dewatering Screens Vibrating Dewatering Screens are normally linear motion, either horizontal or inclined at 5 to 7° upwards with a vertical or back sloped plate at 45° to the rest of the screen deck. The back plate will often have screen panels in them to increase the dewatering capability, as shown in Figure 2 below."

Jan 1, 2017

By Javier Linares García

At then end of this year will be 10 years of producing concentrate for Antamina. This is a summary of what occurred over the last decade to increase production and tonnage above the design tonnage of 70,000 tonnes per day, up to an average of 100,018 tonnes per day in 2010, an increase in production of 42.9%. Equipment currently in use is the originally installed equipment, signifying a meaningful increase in capacity without capital. In this paper, the different phases of improvements and the realization of their impacts in chronological order will be outlined. Figure 1 below shows the average daily tonnage processed each year (tonnage throughput each year/calendar days), as well as the percentage increase over the tonnage of design.

Jan 1, 2012

By P. Sauriol

This work addresses the design challenges and demonstrates the capabilities of a novel water transfer factor measurement apparatus. Several measurement concepts were screened on the basis of their water transfer factor accuracy using Monte-Carlo generated virtual experiments. The most promising measurement concept was assembled and tested to assess its actual measurement accuracy. For these concept validation experiments, the polymer electrolyte membrane fuel cell was simulated by adjusting the water injection rate to corresponding levels. Combining the anode and cathode measurements, the water transfer factor accuracy was typically better than 0.01. Real-time measurements of the water transfer factor on both anode and cathode sides of a polymer electrolyte membrane fuel cell were achieved. The anode and cathode side measurements were in good agreement with each other; however the anode side measurements were generally more reproducible. A parametric study showed that stream humidification plays an important part in the water transfer across the membrane electrode assembly. Finally the water transfer factor along the channel of a 300cm2 co-current fuel cell was obtained by using a series of six 50cm2 sub cells. The results were in good agreement with predictions from a recently proposed model.

Jan 1, 2005

By T. L. McCall

CHANGES in mining practices have evolved so quietly and unobtrusively that perhaps we scarcely appreciate how truly startling these changes are unless we cast our minds back so as to compare the past with the present. Such retrospection is, indeed, necessary when attempting to forecast the future, for it is only by carefully reviewing the past that we can hope to obtain an indication of what the future may hold in store. In this instance, it is not necessary to delve into the very early history of . coal mining, as our purpose will be served if the last three or four decades are reviewed, a period that is still fresh within the memory of many of us. These earlier days might be termed the selective period of mining, for at that time the coal resources of the world had not been tapped to anything like the extent they are at present and this condition enabled the owners and operators to exercise selective powers and only mine such seams of coal as could be most easily reached an worked at the lowest possible cost and which, at the same time, would suit the requirements of the market. Carrying this thought of selective mining still further, the miner, who was then an artisan skilled in all the branches of his calling, was able to select or discard such parts of the seam he was working that the co al sent out of the mine was acceptable to the consumer with just the barest minimum of preparation. Compare these conditions with the? conditions prevailing today, when coal seams of medium height, good quality, and readily accessible have been largely depleted and the operator has been compelled either to carry on his operations under much greater depths of cover where the coal is more costly to win, or else to work seams of lesser height or of poorer quality.

Jan 1, 1938

By R. H. Fett

T HE APPROACH to maintenance must always be ?completely positive: there must be no question of putting off difficult problems until it is more convenient to tackle them. By this it is meant that a piece of machinery or equipment which, by experience, is known to be due for a check should not, merely because it appears to be operating satisfactorily, be left until it reaches a critical .condition and breaks down. The mentality of the Maintenance Manager must be completely orderly and methodical and he should, in fact, possess a ledger-book mind, having a debit and credit outlook. The debit side would be that applying to time out of service, cost in wages, material, personnel involved, etc., and the credit side that relating to continuous operational time of the locomotive and therefore to the ultimate benefit of the mine and the personnel who work there. The Maintenance Manager is not concerned with design problems, and although he and the personnel under his jurisdiction are not engaged in productive work, he and his staff do, nevertheless, add greatly to or detract from the overall efficiency of the organization. Provided the machinery placed in his care is good to start with, he must take the best steps he possibly can to keep it running. However, he may, on occasion, be forced to improvise and this is where the ingenuity of a clever man rises to the occasion.

Jan 1, 1956

By G. P. Holmes

"IntroductionThe copper-molybdenum property of Brenda Mines Ltd. is located 18 miles north west of Peachland in the Okanagan Valley of the Southern Central interior of British Columbia. The actual site is 50 miles north of the international boundary and 150 air miles east of Vancouver at an elevation of 5000 feet above sea level. The earliest written mention of the prospect is found in the Geological Survey of Canada, Memoir No. 243, issued in 1947 by Dr. H.M.A. Rice. In 1954 the area was staked by a prospector, Bob Bechtel, who interested Bern Brynelsen of Noranda Exploration in examining the claims. A joint Noranda - Kennecott program resulted but since the grades were so low the property was not taken up until in 1964 a re-examination by Chapman, Wood and Griswold produced recommendations leading to the construction of the Brenda Mine as it is today.The rounded, timber covered mountains of the area are composed of the tuffs, argillites and limestones of the Upper Triassic Nicola Group, which is intruded by a Jurassic quartz diorite, called the Brenda stock0 The actual orebody occurs in a strongly fractured zone within the Brenda stock, approximately 1500 feet from the contact with the Nicola group0 The ore minerals, .chalcopyrite and molybdenite, associated with pyrite and magnetite of lesser importance, occur as fillings within the fractures 0 The grade of the ore decreases outwards from a central higher grade core and in January 1971 total reserves were estimated at 165 million tons assaying 0,182% Copper and 0,049% Mo."

Jan 1, 1972

By G. A. Bezuidenhout, J. Davis, S. Lefume, J. P. T. Kapusta, D. K. Chibwe

"Although the centennial of the Peirce-Smith (PS) converting process has recently been celebrated, the technology has essentially not changed much since its inception. PS converting is used extensively in the Cu, Ni and PGM industry to remove iron and sulphur from a molten matte phase. A typical PS converting process would use low pressure air supplied by a blower to bubble air through the molten bath. This bubbling injection regime is inherently inefficient from a process and energy consideration. In the late 70’s and early 80’s, Brimacombe and co-workers demonstrated at both laboratory and plant scales that sonic injection (jetting regime) into copper or nickel converters could reduce or eliminate the above hindrances characteristic of PS converting. Since then, in spite of these successes, very little industrial applications have made headway in the converting process of non-ferrous metal mattes on a commercial scale. As part of its operational improvement and energy reduction program (process efficiency), Lonmin Platinum decided to conduct a full scale industrial evaluation of sonic injection using air only to establish if punchless, high efficiency sonic injection was feasible in its small 3.05 × 4.57 m converters (10’ × 15’). A plant trial was run for four weeks in one of its three converters. This paper discusses the plant demonstration with a focus on the experience acquired by Lonmin together with the key learnings from the trials. Reference will also be made to the commercial aspects of a full scale implementation of sonic injection in all three converters in the smelter. INTRODUCTION AND OBJECTIVESAlthough the centennial of the Peirce-Smith (PS) converting process has recently been celebrated (Peirce and Smith, 1909; Southwick, 2009), the technology has essentially not changed much since its inception. PS converting is used extensively in the Cu, Ni and PGM industry to remove iron and sulphur from a molten matte phase. A typical PS converting process would use low pressure air supplied by a blower to bubble air through the molten bath. This bubbling injection regime is inherently inefficient from a process and energy consideration."

Jan 1, 2012

By R. M. Graves, C. B. McKenzie, D. Barbour, D. W. Desnoyers

"Abstract -The prospective Tulks volcanic belt hosts five significant massive sulfide deposits, Tulks Prospect, Tulks East, Jack's Pond, Daniel's Pond and Victoria Mine, as well as numerous showings and indications throughout its 70 km outcrop length. Regionally, the 498 Ma sequence consists dominantly of felsic pyroclastic rocks and flows with interbedded mafic volcanic units and fine­ grained sediments, commonly graphitic. Contemporaneous granitoid rocks occur in the south half of the belt. Rocks usually display a strong NE-SW, steeply dipping, penetrative foliation and other shear-related high-strain fabrics. Facing directions are normally northwest, although there is local evidence of folding. Sulfide bodies and their alteration systems are deformed and shape-modified in the style of ambient strain.The Tulks, Tulks East and Jack's Pond prospects appear to occupy a similar stratigraphic level, on or near the contact between a thick felsic pile and an overlying broad, conductive package of graphitic sedimentary rocks. AU are pyritic deposits with well-developed footwall alteration systems. The Tulks prospect comprises four polymetallic lenses totalling 750 000 t. Three lenses constituting more than 6 000 000 t of sulfide mineralization are indicated at Tulks East but only the 210 000 t ""B"" lens contains significant base metals. Jack's Pond consists of a very extensive, zoned alteration complex in which four lenses of massive to semi-rnassive pyrite + chalcopyrite are known.The central part of the system, characterized by Mg chlorite and carbonate, is enveloped by pervasive sericitization and capped by intensely silicified and pyritized volcanics. The sulfide lenses are interpreted as part of the footwall zone and are beneath that part of the system most likely to host polymetallic massive sulfides.Daniel's Pond differs from the other prospects in such fundamental ways as metal content, associated alteration and structural setting. The deposit comprises strongly tectonized, Ag-rich, Zn-Pb mineralization distinguished by a pronounced Ba-As-Sb signature. Mineralization is confined to a narrow, north-south high-strain zone which separates unstrained mafic volcanic rocks to the east from well-foliated felsic rocks. The deposit Jacks an extensive alteration halo and at its north end is associated with a lens of barren, undeformed massive pyrite.The Victoria Mine deposit, the most cupriferous of the five, is related to a moderately dipping structure that separates well-foliated Tulks volcanic rocks from an overlying, Jess deformed volcanic­ sedimentary sequence that may be as young as 462 Ma. The structure is also the locus of black chlorite, dolomite and quartz alteration. Structurally remobilized precursor sulfide mineralization is one possible source for the deposit."

Jan 1, 1993

By John Kazakoff, Andrew Mortimore

"Production at the remote Kumtor Gold Mine in Kyrgyzstan commenced on schedule in December 1996.The ore mined during the first few months of 1997 from the upper benches of the pit did not produce the results predicted by the feasibility study. Low metallurgical recoveries experienced at the time were cause for great concern.It soon became clear the recovery difficulties centred around the preg robbing nature of the ore.Procedures were developed to selectively stockpile highly carbonaceous low recovery ore types. Testing methods were developed in the mill to quante the preg robbing activity of the ore. Preg robbing masking agents were added to the process to reduce the preg robbing activity of the ore.The importance of coconut carbon activity relative to the preg robbing activity of the ore was realized. Every aspect of the performance of coconut carbon in circuit was evaluated and optimized to improve carbon activity.Mineralogical analyses were completed defining the deportment of gold in ore and process tailingsBy year end the recovery difficulties had been overcome and plant design production had been achieved. Process improvements continue through 1998."

Jan 1, 1999