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By G. F. Cross

INTRODUCTION THE electrical system associated with the mining development of the Hudson Bay Mining and Smelting Company, Limited, at Flin Flon, Manitoba, may be conveniently divided into three main parts, namely, the Island Falls power plant, the transmission line, and the distribution systems at the mine and metallurgical plants. For a description of the Island Falls power plant and the transmission line, the reader is referred to the paper, to be presented at this meeting, by R. W. Davis and M.F. Huffaker (1). The transmission line and sectionalizing combinations are shown diagrammatically in Figure 1. The present paper deals with the distribution systems at the Flin Flon mine and metallurgical plants. THE FLIN FLON DISTRIBUTION SYSTEM In the high-tension sub-station at Flin Flon, each incoming 110 kv. line is provided with manually operated, gang-type disconnecting switches. Each line is connected to Canadian General Electric type F.H.K. 39-60B-F.2 T.P.S.T. 110 kv. 400 amp. oil circuit breakers, each provided with M.K.4 centrifugal motor-operated closing mechanism. Gang-type disconnecting switches are installed on each side of incoming line breakers, and a complete ring bus system is formed through station tie breaker, which is' further provided with gang-type disconnecting switches on either side. The?bus tie breaker is of Canadian Westinghouse design, type G.22B, 110 kv., 400-amp., solenoid-operated. All three breakers are provided with bushing-type current transformers, and the two line breakers are further equipped with bushing-type potential devices. Oxide film lightning arresters (121 kv.) are installed on each incoming line and are located outside the station. Each line is further provided with interlocked gang-operated ground disconnecting switches. All disconnecting switches are mechanically connected to auxiliary switches, which provide pilot service to indicating lamps in the remote-control room, located in a separate building.

Jan 1, 1935

By J. Scrimgeour

"The word ""instrumentation"" has expanded from its original meaning, which in engineering perhaps referred to measuring apparatus alone. In its broadest form, it now includes sensors, display instrumentation, standard pack-aged controllers and, most recently, the use of stored program computers for on-line process control. The paper traces the evolution, in tutorial form, of the successive application of mechanization, measurement instrumentation, automatic control, central operating systems, programmed control, process computer control, direct digital control and, finally, hierarchies of computers used for process control and corporate management as a fully integrated business system. In the field of industrial minerals, the cement industry has seen the most widespread acceptance of these techniques. Computer control has been accepted as the way of life for the blending of chemical materials and for on-line control of the cement kiln. Accordingly, the cement application is selected for further presentation in the paper. This illustrates the trend progressing from control of single loops on process variables toward the objective of total control of the product quality. The economic justification for instrumentation, centralized control, automatic control and computer control is .discussed with reference to savings in fuel, maintenance, operating labour, depreciation, power and product quality improvements."

Jan 1, 1967

By M. E. D. Raymont

"During the history of the sulphur industry there have been three distinct phases of production. Factors controlling supplies during these periods have shifted from demand for sulphur to demand for energy and a cleaner environment. The pattern of brimstone production is t raced through these phases and includes estimates of future supply; these indicate an involuntary excess production of some 20 million plus tons per year by 1980 unless some large-scale new uses are found. Traditional uses for sulphur, including fertilizer, chemicals, fibers, etc., are generally expanding slowly; how• ever, supply in ""by-product"" form alone will soon outstrip demand. The predicted oversupply situation can be corrected by the development of novel potential markets. Promising areas include construction materials, insulation and plastics, among others."

Jan 1, 1972

By Philip W. Johnson, Charles D. Haynes

"Abstract - The coalbed methane industry has become a prominent source of domestic natural gas, with its technology having evolved over the past 30 years. Whereas most coalbed methane wells are able to produce without major interruption over their economic lives, wells operating in an underground mining area are subject to being mined-through. If mine-through occurs, the productivity of the well is at least compromised, and may even be terminated. The economic consequences of mine-through may be relatively simple if mineral ownership and extraction rights are common for the coal and coalbed methane. However, if ownership is not common and a superior coalbed methane lease exists, the coalbed methane ownership must be compensated for lost production caused by mine-through. This paper presents a relatively straightforward method to calculate the value of the lost production caused by the mine-through. It uses technology from mining and petroleum engineering, as well as simple economics and financial management techniques.Sommaire - L’industrie de la production de méthane houiller est aujourd’hui une source importante de gaz naturel domestique dont la technologie a considérablement évolué au cours des trente dernières années. Bien que la plupart des puits de méthane houiller peuvent être mis en production durant l’entièreté de leur vie utile sans interruption majeure, les puits implantés en périphérie de mines souterraines sont sujets à être recoupés par ces dernières. Un tel recoupement peut compromettre, ou même mettre fin à la production d'un tel puits. Les conséquences économiques du recoupement par une mine souterraine peuvent être relativement simples quand les droits miniers et les droits d’extraction sont détenus en commun pour le charbon et le méthane houiller. Si toutefois ces droits ne sont pas détenus en commun et qu’il y a eu octroi d’une concession de méthane houiller de qualité supérieure, les détenteurs du méthane houiller doivent être compensés pour la perte de production résultant du recoupement par une mine souterraine. Cet article présente une méthode relativement simple pour calculer la valeur des pertes de production suite au recoupement par une mine souterraine. Cette méthode fait appel aux technologies de l’industrie minière et pétrolière ainsi qu’à des techniques simples d’économie et de gestion financière."

Jan 1, 2006

By J. E. Dutrizac, J. B. Sunstrum

Until relatively recent times, virtually all gold was recovered by gravity and/ or amalgamation methods. Although such techniques are very effective on coarse gold, they become increasingly less useful for finer grains especially when the gold is partly enclosed in rock matrix. Throughout the nineteenth century a number of bonanza gold fields were found in the United States, South Africa, Australia and Canada. In every case the abundant supply of gold nuggets and coarse alluvial gold soon gave way to hard rock mining with its inevitable losses of fine gold in the stamp mill tailings. Continuing efforts to develop new technologies capable of dissolving gold from finely ground ore were eventually successful first with chlorination (the Plattner process) and subsequently with cyanidation. Even before the nineteenth century, however, European chemists such as Scheele and Berthollet were aware that gold could be readily dissolved in an excess of free cyanide(1). As early as 1840, a patent was issued to the Elkington brothers for the dissolution of pure gold in cyanide solution and its subsequent plating onto various metals, with or without an applied electrical current. In 1846, Elsner showed that oxygen was also required to solubilize gold or silver in cyanide media(1). Despite the fact that much work was done on the reaction of cyanide solutions with gold, a viable leaching process for gold ores did not quickly emerge although cyanide solutions were used to enhance amalgamation from the 1860s onward. Major problems were associated with the use of concentrated cyanide solutions; the costs of cyanide were excessive and it was difficult to recover gold from the concentrated media.

Jan 1, 1999

By The Mill Staff

Introduction The Hollinger cyanidation mill commenced operating in June, 1912, and 49,779,978 tons of solids had been discarded by the end of 1950. The present tailing disposal plant has been in operation since 1924 and holds 39,762,250 tons. The tailing disposal plant is on the property of Kayorum Gold Mines, Limited, about a mile and a quarter south of the mill. The area available for tailing covers 640 acres and is roughly l ¼ miles long by ¾ mile wide. Tailing was first deposited on the McKay veteran claims, l mile long by 1/2 mile wide, which were later included in the Kayorum property. This site sloped from northeast to southwest, the slope amounting to 106 feet between the northeast corner and the low land to the southwest. The low land was wet and a considerable area was covered with muskeg up to 17 feet deep. It was drained by a brook running across the property in a southwesterly direction. Later, when more ground was needed, the low-lying mining claims adjacent to the south and west boundaries were acquired to allow for the extension of the plant. This entailed some extra difficulties and expense that would not have been encountered had the whole of the present site been acquired with the original purchase. At the present time, the top of the tailing deposit stands at two elevations, but eventually the tailing deposited on the extension to the original plant will be raised to the same height as the older deposit. Previous to 1924, all of the tailing was deposited on Low land and in lakes near the mil1. Between 1924 and 1926 an increasing tonnage was sent to the McKay claims until, in 1926, all of it was being sent there. In 1936, the area of the deposit was extended and shortly afterwards all of the tailing was deposited on the new site.

Jan 1, 1951

By G. M. Humphrey

It is a great honour and privilege to be here in this distinguished company of the outstanding men in the mining industry and the political life of Canada. I fully recognize that I am so honoured as a symbol of the combination of American and Canadian leaders in industry who are partners in the sponsor-ship of the Quebec-Labrador iron-ore mining development which we are undertaking, and as such I want to express our great appreciation of the co-operation and assistance we have met on every hand in Canada, and the genuine friendliness and never-failing courtesy which we are always accorded. We are quite aware that it springs primarily from the very high regard in which our partner and sponsor, Jules Timmins, and our other Canadian associates are held. Their high standing among you is well known and we quite naturally fall heir to the benefits of the great esteem in which you hold them. Jules Timmins and his long-time associate, John Knox, were the original inspiration for our participation in this venture. It was their enthusiasm and vision which caught our interest and led to our joining with them in the years of exploration and search which have brought us to the threshold of this great development where we stand today. So much has been written of the details of our exploration and plans for future development that it would bore you for me to review them further here, but there is a phase of this development, and an extremely important phase of it, which I think has passed almost unnoticed and which it may be well worth while for me to bring to your attention this evening.

Jan 1, 1951

By J. G. Phillips

Introduction Throughout the Great Plains region (the provinces of Manitoba, Saskatchewan, and Alberta), numerous clay deposits of widely varying composition and character are to be found. These may be classified into two general types: (1) surface clays, and (2) shales. The surface clays consist of a heterogeneous mantle of silts and clays interspersed with grave! and sand deposits, and may belong to any of the following groups: (1) lake clays: (2) river-terrace or flood-plain deposits; (3) delta deposits . In most cases, the water from which these deposits were ' laid down was derived from the melting ice of the continental glaciers. These surface clays, in general, possess certain characteristics in common, being all more or less calcareous, often silty, and showing a tendency to 'check' in air-drying. The shales found in this region are of Cretaceous and Tertiary age. These deposits have a wide extent, but there is frequently such a heavy covering of drift material that the clays are accessible chiefly along the walls of stream valleys, or along the escarpments of uplands.

Jan 1, 1929

By J. P. Caulfield

THE Hudson Bay Mining and Smelting Company's underground mine at Flin Flon, Manitoba, has in the past been serviced by two working shafts-the North Main shaft, and the No. 3 shaft. The North Main shaft is used to hoist the total production from under-ground, and handles the greater part of the mine supplies and crews. The shaft is five-compartment design, rectangular in cross-section, and is equipped entirely with steel shaft sets from the surface to the finished depth of 2,210 feet. Hoisting equipment in the surface plant will not permit the North Main shaft to be extended below its present finished depth. The No. 3 shaft, located approximately 2,300 feet from the North Main shaft, is used primarily as a ventilation shaft, and for hoisting lower-level development waste to the 390 level, where this material is used as mine fill. The No. 3 shaft is of standard rectangular design, timbered with 8-in. by 8-in. creosoted fir sets, hung on 6-foot centres. From the surface to the 1,430 level, the No. 3 shaft consists of three 5 ft. by 5 ft. compartments, and below this level to the completed depth of 2,300 feet, the shaft is increased to four compartments. To service the mine and to expedite development below the 2,210 level, a one and one-half compartment winze was sunk from the 2,210 level to a depth of 766 feet, or approxima tel y the 3,000 level.

Jan 1, 1941

By Atul Bhatnagar, M. P. Sinha, Md Zahid Ahmad, Pallav Garg, Sanjay Kumar Singh, Shashi Ranjan, An Ecolab Company Nalco Water

"Froth Flotation is undoubtedly one of the most critical processes in coking coal washing plants. This work was carried out at Bhelatand Coal Preparation Plant of Tata Steel was with an objective of cost optimization in fine coal processing. The sources of raw coal for the plant include coal from underground mines of Jharia coalfield and procured open-cast raw coal. Coal from different sources vary in quality and possess different floatability characteristics.Synthetic collector is being used in plant as a flotation reagent. An alternate collector with new chemistry was developed for reducing total treatment cost without compromising product yield and quality. A series of laboratory tests were conducted to assess the performance of various sources of raw coal and plant scale trial was started. At first, the new generation coal collector was entirely substituted with the existing collector in the laboratory scale. However the plant scale trial data was not in accordance with laboratory results and indicated inferior flotation performanceThe issue was studied and data based conclusions were drawn that the new generation collector aids faster and uncontrollable kinetics. A decision was taken for co-dosing of the synthetic and new collector for the second phase of the trial. A detailed laboratory analysis was done again and few dosing ratios that predicted optimum results were selected for plant trial. The dosing ratio was optimised as per flotation yield and product ashes during the plant trial. The results showed significant improvement from the first phase and optimum dosing rates were decided based on plant observations and data collection. The influence of various process indicators including water quality, feed and product ashes and process yield was studied during all the trials and promising results were established. The co-dosing of both the collectors conferred cost advantage and enabled to achieve superior performance."

Jan 1, 2016

By Cesar Carrasco

Mine reconciliation is the art and science of comparing predictions and real-world outcomes with the intent of revealing the true quality of performance of models, planning, mining, and mineral processing. When mine reconciliation is conducted in a systematic, transparent and sustainable way it can play a central role in the governance of Mineral Resource and Mineral Reserve (MRMR) estimation and reporting. The core processes of modelling, planning, mining, and processing need to be transparent to be able to demonstrate that MRMR are reliable predictors of mine performance and value. Transparency is also necessary for mine technical staff to generate meaningful analyses, conclusions, and business improvement actions that demonstrably maximise value for all stakeholders. Most mines have some form of mine reconciliation practice, however because there is no agreed industry standard, and because mine reconciliation is difficult for a variety of reasons, it is often unsustained and/or ineffective at delivering the required transparency of performance. To deliver true governance of MRMR and business value, mine reconciliation must be sustainable. There are two categories of issues that combine to make mine reconciliation extremely difficult to sustain, these are technical, and people related. Technical issues include defining standard terms, accurately tracking material flows, data availability/adequacy/quality, calculation of key performance indicators and tolerance limits, analysis, and interpretation of results, understanding limitations of modelling techniques, and defining appropriate actions that can deliver value. These technical challenges are non-trivial, however compounding these are a range of people issues that include personal agendas, scepticism, lack of knowledge and experience, poor teamwork, absent leadership, toxic workplace culture, staff turnover, ineffective communication, siloed organisational structure, and lack of deliberate change management. All these problems can be solved with clarity of purpose, definition of the process of mine reconciliation, discipline in following the process, appropriate resourcing, and commitment to success across the entire organisation. Outlined in this paper is a management system that delivers sustainable mine reconciliation by addressing both the technical and people issues described above. This approach can deliver significant value for a mine and adds a robust, defensible governance over MRMR estimation and reporting.

Oct 1, 2024

By N. B. Clarke

LIMESTONE, as a name, covers a great variety of stone consisting of varying amounts of calcium carbonate, magnesium carbonate, and impurities such as silica, alumina, and sulphate of lime. In the iron and steel industry, limestone is roughly divided into two classes, namely Calcite, when the magnesium carbonate content is below 10 per cent, and Dolomite, when the magnesium carbonate is over 10 per cent. In practically all metallurgical melting, the quality of the finished product is related to the character of the slag, and limestone is used as a flux to achieve the proper analysis and consistency. The function of the slag is to absorb the undesired elements of the bath and also to act as a protective cover over the metal. The carbonates of calcium and magnesium are the effective agents in fluxing, and the silica, alumina, sulphur, and other foreign matter are objectionable impurities which should be as low as possible, totalling not over S per cent and preferably below 3 per cent, since all of these so-called impurities must be fluxed by the lime and magnesia of the stone. When the lime and magnesia of the stone have to be used to flux its own impurities, there is that much less of these two oxides left for fluxing the impurities from the balance of the charge, and, as a result, more lime-stone must be used than is desirable with good practice.

Jan 1, 1939

By J. F. K. Brown

WHEN I first received the kind invitation extended to me by the Mining Society of Nova Scotia, I read over very carefully the suggested title-"The importance of long-distance planning and budgetting in modern methods of mining, and the advisability of working to some definite plan". I came to the conclusion that I might as well confess my inability to handle properly such a vast and intricate subject within the scope of any one paper. More properly, I think a round-table discussion should be indulged in-a sort' of symposium carried on in similar fashion to the World Power and Coal Conferences- you know, a committee for this, a committee for that, and, finally, a committee to see what the committees are doing. Weil, your Secretary's suggestion is just like that- much too comprehensive for any half-hour's presentation. As a paper, also, it either becomes too general and therefore uninteresting, or i.t descends into detail and describes means and methods to the end desired, which have little attraction because they were designed to meet quite different conditions than those my audience would mentally be considering. Of the two evils facing me, I have chosen the one that sticks to the generalities. Your Secretary's query almost automatically divides itself into two distinct phases: First, the importance, and second, the advisability, of planning. Let us dwell for the moment on the second, because, if we can prove advisability, that leads to desirability and, finally, to doing. Proving is the difficult part of the little problem. Here was something I, personally and as a mining engineer, had been battling for all my corporate life without being able to prove it to anybody. Then I saw the way out of that. I perceived I could put that little question of advisability on another basis altogether-:put it in the class of "coming- some day- soon" whether you or l or anybody else liked it or not; call it, if you please, mandatory, certain, necessary, enforceable planning. All of which means that the problem of advisability has rather suddenly become the very practical one of "how to do it". Why?

Jan 1, 1937

By Bert S. Hall

"The purpose of this paper is to review the evidence at hand concerning the earliest centuries of cast iron in Europe, from roughly 1400 A.D. until the second half of the sixteenth century. For the most part it is concerned with the relationship between two technologies which emerged first in China and then later appear in Western lands, gunpowder weapons and iron founding. We should not assume, as I hope to show later in this discussion, that weapons constituted the only product for which the iron founder had any market, but it is clearly true that attempts to produce weapons constituted the most severe technical challenge for the early founder. Firearms appear for the first time in Europe in the 1320s and develop into significant weapons on the field of battle by the end of the century. Theirs is a complex history, subject neither to easy summary treatment nor to simplified models of development. I hope to be able, through the analysis of the evidence concerning cast iron, to show that one important strand in the fabric of gunpowder's history concerns the materials from which cannon could be made. This question is subject to a number of shades of meaning, because ""cannon"" can be made for many purposes under a profusion of different names, and under sharply varying conditions of use. As a result, the question of materials is frequently really a question of competing materials, and involves a complex set of factors, of which production costs and the ultimate safety of the user seem the most important. Judged in this manner cast iron was an important but unsatisfactory metal for weapons purposes until 1543, at which time English founders learned to make iron muzzle-loading cannon which could rival bronze ordnance in most important performance criteria, but which cost much less to produce. With that event, the history of cast iron and the history of weapons entered into the close relationship that persisted until the advent of rifled artillery made of steel in the middle of the nineteenth century."

Jan 1, 1999

By P. A. Peach, W. H. Gross

The modern economic geologist in Canada is well equipped to apply geological, geochemical or geophysical techniques in the exploration for ore. Recently, great advances have been made in geophysics and geochemistry, and a large number of new orebodies have been discovered by these methods. An attempt is made in this paper to show that there has also been a considerable advancement in geological knowledge and that the most effective application of geophysics and geochemistry often occurs in areas already considered geologically favourable for the occurrence of ore. Ali exploration methods sooner or later suffer from diminishing returns. Therefore, as time goes on, one can expect to see the application of some of the more subtle or refined geological techniques that are presently being developed.

Jan 1, 1967

By D. R. Keck

"SINCE the .Canadian Chemical Company has no direct connection with mining operations, and I have had no experience with mining, there is little I can tell you that you do not already know. However, we have had considerable experience with certain types of metallurgical problems and I would like to discuss with you some of these problems and their solutions by our metallurgists.In order to acquaint you with the type of plant and processes to be employed at Edmonton, I would like first to take a few .minutes to trace briefly the history -of the Canadian Chemical Company's affiliate, The Celanese Corporation of America. In the early •part of the twentieth century, two young Swiss brothers, Camille and Henri Dreyfus, received their P.h.D. degrees in chemistry. They were extremely interested in work which was being carried on at that time to find a suitable synthetic fiber that could compete with natural fibers, both quality and price-wise. Early man-made fibers were both coarse and hard to dye. The Doctors Dreyfus• poured all their earnings into research and ultimately developed cellulose acetate filament. During World War I, the Dreyfus brothers were invited to the United States to produce cellulose acetate 'dope' for airplane wing coverings. Dr. Camille Dreyfus built the first American plant for fiber production at Cumberland, Maryland, in 1924.Due to resistance of textile mills to the new fibers, Celanese was forced to set up its own dying, weaving, and finishing mills to prove the new materials. Through the years, however, this operation has •been retained primarily for fabric development purposes,.. with the majority of the acetate being sold to other textile mills."

Jan 1, 1953

By Christoph Miller

About 80 years ago the mining industry saw an advertisement of a machine manufacturer: ?One man ? one machine?, meaning the productivity gain by using a pneumatic rock drill instead of manual tools. Mechanization in mining had started. In the 1950's and 1960's when mechanization progressed the word could be transformed into the meaning of ?one man ? one drill rig?. During the 80's automatic functions were added to the machines. Automation started. In the 90's, the first autonomous machines were seen, transforming the advertisement from the 1920's into ?one man ? multiple machines? operated from a remote control room. Soon, the productivity gain achieved by pure automation will also be flating out meaning that the margin cost of further productivity gain will be inefficiently high. What next? In mining operations there is still a high potential of unused productivity lost by ?trivial? things like organization, logistics and operational management. Changing the focus from mechanization and automation towards optimizing the overall mining process will unleash another big potential for cost cuttings and for enhancing efficiency of production. Optimizing an overall process is a task of much higher total complexity compared to an isolated machine automation focus. And a successful process integration requires the collaboration of machine vendors, infrastructure suppliers, IT services and the mine itself. It requires a number of of important preconditions to be fulfilled: ? Integrated IT systems with seamless interfaces between all components and peripherals involved ? Real time information access in all locations ? Real time overview of all operational aspects A crucial aspect for all of these issues is a seamless communication both above and also under ground and IT interfaces which are easy and price efficient to implement. This paper highlights ways to achieve productivity gains by process optimization. It also discusses needs for industry wide activities in order to enable cost efficient performance of mine process optimization projects.

Oct 1, 2009

By Paul T. Fitzgerald

Risk financing solutions are emerging to fully address environmental liabilities for mining operations. Supported by specialized insurance and alternative risk transfer (ART) products, mine owners can fund, cap and guarantee the environmental liabilities and closure obligations of a mine within a financial structure that will be acceptable to regulators. An environmental risk financing program will permit an owner to transfer the liabilities and indeed the ownership of a site to a third party that has the ability and resources to responsibly execute the closure plan. A properly structured program will be financially viable for the owner and will also respond to community and environmental opposition concerns about sustainable development and the environmental legacies associated with mining activities.

Apr 1, 2005

By John F. Kearney

After World War II Canada?s fledgling iron ore mining industry developed along the ill-defined Quebec / Labrador border near what became the town of Knob Lake and later renamed Schefferville. For about twenty-five years from 1954 to 1982 Schefferville was the epicenter of Canadian iron ore mining and the foundation of the Iron Ore Company of Canada. In about 1982 it all stopped, shut down, the miners moved away leaving behind a mining camp and a ghost town that have sat idle and almost deserted for the past twenty five years. The story looks set to change with new plans to re-establish the former mining operations in the historic mining camp. This paper outlines the proposal to reactivate the direct shipping iron ore operations in the Schefferville mining camp, and specifically the properties in Labrador owned or optioned by Labrador Iron Mines Limited (?LIM?), a wholly owned subsidiary of London Stock Exchange listed Anglesey Mining plc. The Schefferville mining camp is located about 1,000 km northeast of Montreal. There are no roads connecting the area to southern Labrador or to Quebec. Access to the area is by rail from Sept Iles to Schefferville, or by air from Montreal and Sept Iles.

May 1, 2007

By H. C. Gunnings, C. O. Swanson

"The Sullivan mine; at Kimberley in southeastern British Columbia; is the largest silver-lead-zinc mine in the Empire and one of the largest in the world.The original discovery was made in 1892 by four prospectors. Until 1899, when the branch line of the Canadian Pacific railway from Cranbrook to Kimberley was completed, little work was done on the property. In 1900, systematic development was started, and during the next 3 years 5,000 tons of ore was shipped to the smelters at Nelson and Trail. By 1903, some 300,000 tons of ore was developed, and a smelter was started at Marysville, about 5 miles from the mine. However, this smelter closed down in 1907 because of metallurgical difficulties after treating 75,000 tons, and the property came under the control of the American Smelting and Refining Company. An option on the property was taken in 1909 by the Consolidated Mining and Smelting Company of Canada, who exercised their option in the following year. During the next 5 years by selective mining and sorting 188,000 tons of high-grade ore was produced and shipped to Trail. This tonnage came from the upper levels, about 4,600 to 4,800 feet in elevation. At the same time, deep drilling down to the 3,900-foot level showed the presence of an immense body of complex ore. In 1915, the main adit-the 3,900-foot level-was started, and by 1919 this had been driven a distance of 2 miles to develop the ore above this level. Meanwhile, progress was being made in overcoming the milling problems. An interesting account of this work was written by the staff ( 4). In 1923, the first unit of the present concentrator was erected, with a capacity of 2,500 tons a day, and thereafter the rate of production increased rapidly. In 1934 it was around 8,000 tons a day, and to date a total of about 30,000,000 tons of ore has been sent to the mill. In recent years, a considerable part of the production has come from levels between the 3,900-and 3,350-foot, which were opened by an internal incline shaft started in, 1930. In 1942, tin was added to the products separated at the concentrator."

Jan 1, 1954