Search Documents

Arsenic bearing minerals such as enargite (Cu3AsS4) and tennantite (Cu12As4S13), which may associate with major copper minerals such as chalcopyrite (CuFeS2), chalcocite (Cu2S) and bomite (Cu2FeS4), usually report to the copper concentrate in conventional flotation due to their similar flotation properties. Arsenic in a copper concentrate causes environmental problems and also problems in the subsequent pyrometallurgical process. Voltammetric studies were carried out to investigate the oxidation characteristics of enargite, tennantite, chalcopyrite, chalcocite and bomite. Contact angle measurements and micro-flotation tests were conducted to examine the flotation characteristics of enargite and chalcopyrite under controlled pulp potentials. Selective flotation of enargite from chalcopyrite under varied pulp potentials was conducted to investigate the feasibility of arsenic removal from a copper concentrate. The test results indicate that the non-arsenic bearing copper minerals ( chalcopyrite, chalcocite and bornite) were easier to oxidise than arsenic bearing minerals ( enargite and tennantite) in an alkaline solution. Enargite floated well at a potential as high as +0.45 V vs. SCE while chalcopyrite was completely depressed at a potential higher than +0.43 V vs. SCE. Selective flotation revealed that enargite can be successfully removed from chalcopyrite through controlling the pulp potential at +0.30 ~ +0.50 V vs. SCE.

Jan 1, 2007

By T. E. Wakefield

"Final Galloway (stage) designs for vertical drill and blast shaft sinking projects evolve from complex thought patterns which integrate operational processes, systems and methods of communication, power supply, drilling, blasting, ventilating, mucking, supporting, surveying, dewatering, sealing, concrete lining and shaft furnishing. Attention to ergonomic design detail at the shaftsman / structure interface is at the heart of safe and successful multi-deck working platforms. For economy the end product must have a low mass to reduce suspension rope end loads to be able to use smaller suspension hoists and have lighter headframe structures, be robust to withstand concussion damage, be easily constructible on site, be maintainable in the shaft barrel, and comply with safety and legislated standards. This paper’s ambition is to describe a systematic design framework and sequenced thought process that delivers a product that is engineered with excellence, illustrated by making use of two designs that evolved during recent Galloway projects, one destined for a large diameter man/material shaft, the other for a ventilation shaft. The stage engineering iterative process starts with mapping permanent and sinking hoisting layouts, followed by laying out horizontal deck plans, mostly constrained by the permanent shaft purpose and configuration, whilst maximizing openings to enable muck to be removed rapidly for the best sinking cycles. Concurrently the designer needs to understand the chosen sinking methodologies in conjunction with crewing to determine the number of decks and fix their spacing. Insufficient access to move and line up formwork, set reinforcing rods and pour concrete in the confined spaces of the stage is an inherent major risk to be mitigated. An iterative and integrative process follows for the primary configuration which delves into increasing design detail, accommodating all other methodology influences, resulting in 3D layouts for further risk assessment, review and fine tuning by seasoned shaftsmen. INTRODUCTION Documented colliery shaft sinking practice from the late 1800’s makes reference to purpose built walling (bricked lining) cribs with floors suspended in sinking shafts, thereby allowing shaft lining to proceed concurrently with the excavation. Improvements were made by Sir William Galloway who introduced two decks supported at the corners by angle irons. The sinking stage, or Galloway, has developed substantially over time to be the in-barrel heart of the sinking operation, with overwhelming complexity for those who have to design one for the first time."

Jan 1, 2019

As part of the Australian Mineral Industries Research Association (AMIRA) P9 project, methods of characterising both the ore and the machines in flotation circuits have matured considerably over the past 15 years. Machine characteristics include gas dispersion measurements, such as bubble size, gas hold-up and superficial gas velocity. Ores can be characterised in terms of floatability parameters on a size and mineral basis. Measurements have been performed on various copper plants in many countries around the world over the last 5 years. This paper outlines the cell and ore floatability characteristics of each copper plant and provides a discussion on the differences between these plants. In general, most porphyry copper ore bodies are processed at high tonnage through several parallel banks of cells at each stage of flotation. The floatability parameters of these copper ores are very similar in terms of rate of flotation and proportion of fast, slow and non-floating material. The cell characteristics are also similar, with superficial gas velocity, bubble sizes, and gas hold-up values being of similar magnitude. Investigation of the similarities and differences of the modem copper flotation circuits has allowed an increase in understanding of the particularities of copper flotation. Comparison against other copper circuits provides a benchmark and opportunities for future optimisation.

Jan 1, 2007

By J. A. Harle

Introduction When considering power in Alberta, there automatically come to mind ideas of either hydro or thermal generation, leaving in one's thought an uncertainty as to which one would propose. There is frequently an obvious source of power in some locations on our fastflowing rivers, the major possibilities being described in the report on Surface Water Supply and Water Power of Alberta issued by the Alberta Government in 1948, but it must be realised when reading that report that the sites so described will require extensive geological and other surveys before they can be exploited, and account must be taken also of the transmission distances involved in each instance. From a conservation point of view, where water power can be economically developed and power transmitted to the load centres, this should be done, and our thermal resources should be husbanded for our coming generations, especially if our water resources are falling owing to glacial shrinkage.

Jan 1, 1951

By F. O. Verret

Several grindability tests were developed over the years to design grinding circuits or optimize existing operations. Each test has its own strengths and weaknesses and it is imperative to select the proper test procedure(s) to meet project deliverables and minimize the risk of a project. Pilot plant testing of large bulk samples historically constituted the traditional approach for AG or SAG design, but was gradually replaced by small-scale tests. Nowadays, conducting grindability tests requiring only a few kilos of material on several samples is a more typical approach to grinding mill design. This paper summarises the requirements and deliverables of various bench-scale test procedures, their strengths and weaknesses, and cases where AG/SAG pilot testing should still be performed.

Jan 1, 2012

By A. A. Wessels, D. P. Allison

"Mine hoists are built to handle a certain nameplate capacity; they are specified and designed according to the required duty. However, as production capacity increases in other parts of an operation, the hoist capacity can become the critical constraint. Such a situation occurred at Lundin Mining’s Neves-Corvo operation. This paper examines how each component of the existing hoisting system was examined and optimized. Through a combination of engineering study and hoist simulations, the annual hoisting capacity was improved by 24% through increases in payload capacity and available hoisting time combined with a reduction in cycle time, while no changes were made to the hoist motor, drum or headframe. The additional payload capacity was achieved by reducing the mass of the hoist ropes and skips, and improving load monitoring systems. The cycle time was reduced through the shortening of the creep distances and increased availability through the installation of a shaft collar safety platform, alternative guide rope bushes, and superior liners for both the skips and underground measuring flasks. Enhanced cooling of the hoist electrical system was also incorporated to increase hoist availability by reducing downtime during hot summer months. The changes will increase the capacity from the current 4.5 mega tonnes per annum (Mtpa) to a planned 5.6 Mtpa and are being implemented over a 2-year period whilst maintaining the mine production during the upgrade work. INTRODUCTION Neves-Corvo Mine Neves-Corvo is primarily a copper and zinc mine producing copper, zinc and lead concentrates. The operation is owned and operated by Somincor, the Portuguese subsidiary of Lundin Mining. Located in the Alentejo district of southern Portugal, the operation is situated approximately 15 km southeast of the town of Castro Verde, where summer temperatures can reach as high as 45ºC, and approximately 220 km southeast of Lisbon. The principal means of mine access is via a ramp from surface, with the vertical shaft used to hoist ore and waste from the 700 m level, while conveyors descend from the 700 m level to transport ore and waste up from the deeper levels of the mine. The mine is highly mechanized and several different stoping methods are employed, with the most significant being bench-and-fill and drift-and-fill. The Neves-Corvo mine currently exploits five orebodies: Neves, Corvo, Graça, Zambujal and Lombador for copper and zinc-lead ores which are processed in one of two plants. All the orebodies are currently exploited over their full elevation with the exception of Lombador which is only mined down to the 220 m level, approximately the top 50% of the orebody, known as Lombador Phase 1."

Jan 1, 2019

By A. Ignatieff

This is the first in a series of Coal Technology Reviews being prepared in accordance with a recommendation voted by the Coal Division in session at the Jubilee Meeting, Vancouver, April, 1948, that the Department of Mines and Resources be requested to arrange for publication by the proper Government authority of a Quarterly Review' of Coal Technology, for distribution among those concerned in the production and use of coal in Canada. This recommendation was subsequently endorsed both by the Council of the Institute and by the Dominion Coal Board. Further reviews (or digests) will appear at intervals in the Bulletin, or will be published and distributed by the Board which, meanwhile, has undertaken to distribute reprints of Mr. Ignatieff's review.-En. * * * The fields in coal mining technology which are considered to demand most attention and study at the present time are reviewed under the headings appearing below. Mechanization In the light of the growing shortage of skilled miners and the necessity of mitigating constantly increasing mining costs, interest continues to centre in mining methods and applications of mechanization chat will produce the maximum reduction of man power. The growth of strip or open-cut mining, also, is a consequence of this trend. Mechanization at the face attracts most attention and the trend is toward developing and adopting machines capable of cutting and loading the coal in one operation instead of having the separate operations of cutting, drilling, blasting, and loading. In Great Britain, where longwall mining is? the general practice, the A.B. Meco-Moore machine still receives much attention, and accounts describing its performance over reasonably long periods have appeared in the technical press.

Jan 1, 1948

By T. K. Bose

According to the Intergovernmental Panel on Climate Change (IPCC), the average global temperature has risen over the last century. If this trend continues over the next century, the IPCC projects a significant increase in temperature and a rise in sea level. The changes in climate could adversely impact human health, agriculture, water resources and ecosystems. Most national and international agencies have concluded that our use of carbon-rich fuel is responsible for global warming through the greenhouse effect. In the future, the situation may get worse if the increased need for energy in countries like China, India and Brazil is fulfilled by burning fossil fuel. Advanced natural gas-fuelled vehicles have the potential to reduce carbon monoxide and reactive hydrocarbon emissions substantially compared to gasoline vehicles. Further environmental benefits can be realized by using a blend of natural gas and hydrogen. Such an approach will help create an infrastructure for an eventual transition to hydrogen.

Jan 1, 2005

By John Convey

This paper, a follow-up to an earlier study, gives the history of Canadian developments in mineral processing from 1921 to the fall of 1964. It deals extensively with comminution and flotation, and then goes on to cover the fields of gravity concentration, magnetic concentration, cyanidation, the processing of uranium ores, and instrumentation. Several outstanding examples of installations are given. The paper concludes with a discussion of present-day trends in mineral processing. Introduction T HE history of the developments in mineral processing in Canada from its earliest times to 1920 has already been published by one of the authors (1). The present paper is thus a logical follow-up to bring this history to date. From 1834 to 1920, mineral processing in Canada, as elsewhere in the world, was in its formative stage. This, however, prepared the ground for developments that have resulted in a mining empire from the Atlantic to the Pacific, a mining empire which could be said to be almost on par with that in the United States.

Jan 1, 1965

By Jun Xiao, Xiaodong Li, Chunming He, Daixiong Chen

"Benzohydroxamic acid with double dentate can react with copper to form cyclic hydroxyl oxime acid copper chelate, indicating a good selectivity for copper oxide minerals flotation, especially for malachite. The flotation results of the pure malachite mineral show a strong synergistic collecting effect between hydroximic acid and xanthate at a ratio of 3.5:1, achieving a malachite recovery of 95.5% when certain sodium sulphide is used as a sulphidizing agent in the optimal pH range. Thanks to the synergistic collecting effect, the flotation recovery of malachite of a real refractory ore flotation ,can reach over 92% under the optimum condition, a 12% higher than the recovery achieved with the conventional collectors. In industrial application, the flotation of the copper oxide minerals is improved , leading to a high efficiency utilization of copper oxide resources.INTRODUCTIONBeneficiation of copper oxide ore is one of the recognized challenges in mineral processing industry. Copper oxide ore is a vital component of copper resource in the world, which has abundant reserves. Majority of sulphide deposits has oxidized zone on the top, and some deposits are oxidized to become the large and medium-sized oxide deposits (Willam & Chavez, 2001). Most copper oxide ores have problems in processing such as high slime consumption, poor floatability, complex ore property and low flotation recovery, so it is of great significance in beneficiation of copper oxide ores to develop an efficient collector, especially for malachite (Fu & Gu, 1997; Wen, 2010; Riet, Kier & Elford, 1980). At present, sulphidization-xanthate flotation is the most important method for treating copper oxide ore. In recent years, due to the decreasing ore grade, the utilization of refractory copper oxide ore draws more and more attention (Zhou, 2003), except for sulphidization-xanthate method, chelating flotation method (Lu, 2009), chemical beneficiation method (Lenormed, Salman & Yoon, 1979), microwave radiation flotation method, hydrothermal sulphidization-flotation method (Mao, Wen & Fang, 2014) and ammonia leaching of sulphide precipitation-flotation method (Lekang, Stevik & Bomo, 2003) have occurred."

Jan 1, 2016

By Guy Archambault, Réal Daigneault

"Un trait marquant du cadre tectorwstratigraphique de la Sous-province de l'Abitibi est la présence de nombreux couloirs de déformation d’extension régionale et sub-concordants au grain stratigraphique. La présence de grandes masses granitoïdes qui perturbent l'allure du grain tectonique est typique de la partie nord de la Sous-province de l'Abitibi. Des rides E-W constituées de complexes plutoniques précoces forment des reliefs structuraux agissant comme des moles résistants qui interfèrent avec la déformation régionale.Deux types de couloirs de déformation sont distingués, les couloirs de bordure et les discontinuités structurales. Les couloirs de bordure représentent des auréoles de déformation élevée qui s’accompagnent généralement d’un métamorphisme au faciès amphibolite. lls suivent /'interface entre les roches granitoïdes et les assemblages supracrustaux. Ces couloirs sont de puissance kilométrique et sont confines, surtout au sein des roches vertes, a l’interface des complexes granitoïdes d’importance. La limite entre la Sous-province de l'Opatica et les roches supra crustales de l'Abitibi est caractérisée par un important couloir de bordure issu possiblement d'un chargement tectonique irrégulier et concentre lors du raccourcissement horizontal.Les discontinuités structurales sont des failles ductiles qui se propagent surtout en direction E-W mais avec des variantes de directions SE et NE. Les discontinuités E-W se caractérisent par la présence d'une linéation d'étirement à fort angle de chute. Les discontinuités SE sont caractérisées par des linéations d'étirement horizontales et directionnelles et les mouvements observes sont system attiquement dextres. Les discontinuités NE sont des failles à comportement beaucoup plus fragile et se distinguent par des composantes de mouvement senestre. Elles sont tar dives par rapport aux discontinuités E-W et SE et ne représentent pas la symétrique du système SE.La combinaison des systèmes E-W et SE décrit un motif anastomose a l' échelle régionale. Les failles ductiles se rejoignent defaçon asymptotique, isolant des blocs peu ou pas affectes par la déformation. L'anastomose est un phénomène qui se produit a toute échelle et est reliée principalement aux Mt érogénéités et aux anisotropies 1) des forces agissantes (champs de contraintes régionale et locale) et 2) de la réponse del' empilement supra crustal (compositions différentes, fabrique initiate, propriétés mécaniques variées, niveaux d'altération).Dans le but de respecter un raccourcissement horizontal N-S, différents modelés sont proposés; ils mettent en cause soit une transpression dextre, soit des failles inverses réactivées en failles décrochèrent dextres soit des failles de chevauchement redressées."

Jan 1, 1990

By J. Warner, K. A. Hughes, P. E. R. Blanchard, J. Esslifie-Dughan, J. W. Reid

Tailings management plays an important role in reducing the environmental impact of Orano Canada’s uranium mining operations in Northern Saskatchewan. Uranium ores mined from Northern Saskatchewan are often associated with large amounts (10-20 wt%) of other harmful elements, such as arsenic and nickel. The JEB Tailings Management Facility (TMF) located at McClean Lake, Saskatchewan is designed to prevent potentially harmful water-soluble elements, particularly arsenic, from contaminating the surrounding environment by promoting the formation of water-insoluble minerals. It is therefore important to determine which arsenic-containing mineral species are present in the TMF and how they evolve over time. Researchers at the Canadian Light Source (Saskatoon, Saskatchewan) were successful in identifying the arsenic mineral species present in tailings samples collected from the TMF in 2013 using X-ray absorption near-edge structure (XANES) spectroscopy. XANES analysis verified that the majority of arsenic species in the TMF existed as amorphous and crystalline ferric arsenates with minor amounts of arsenite and arsenide species. Herein, XANES is again used to analyze a new set of tailings samples collected from the TMF in 2018, specifically focusing on the difference in the distribution of arsenic species in old and new tailings.

Jan 1, 2020

By Claudia Gasparrini

"The ore microscope and electron microprobe, two common instruments for academic research, have not been used to full advantage in the Canadian mining industry, perhaps because they are not readily available to most mining companies.The present paper gives a description of the two instruments and of the manner in which, when used together, they contribute to the identification and description of mineralogical and metallurgical samples, and reviews the applications, to . date, in the mineral industry.The metallurgical applications can assist in determining the best separation technique for a particular metal or other economically important element, can provide explanations for poor recovery and/or liberation, can be used to determine theoptimum concentrate grade and can indicate environmental problems that may arise from the extraction process.In certain cases, the use of the two instruments may assist in the evaluation of new mineral deposits and in the determination of the origin of mineralization.IntroductionThe ore microscope and electron microprobe, two widely used instruments in universities and other research institutions, have not been exploited to their full potential by the Canadian mining industry.High-magnification, high-resolution ore microscopes, owned by most Canadian universities and government mining branches, are not widely used by mining organizations. The situation is very much the same with the microprobe. The geology departments of several major Canadian universities have easy access to this instrument. Fifteen of them, to the author's knowledge, own one and a few have already acquired or are planning on acquiring a second and later model. The mining branches of the Canadian Government have similar easy access to microprobes, as at least four of these instruments are available to them in Ottawa alone. The mining companies, on the other hand, except for the few larger ones which have their own research laboratories, have not been able to take advantage of electron microprobes in the past.This failure to exploit good ore microscopes and electron microprobes has been mainly due to a lack of expertise in the use of the two instruments for the study of metallurgical problems related to ore mineralogy. Government institutions providing research and test work to the industry are few in number, and are not always equipped with these instruments or are not geologically-oriented. Information provided on a consulting basis by universities and by government mining branches is normally limited, and frequently is not oriented to the needs of the mining company."

Jan 1, 1980

By R. K. Jonas

"Pressure leaching and pressure oxidation in autoclaves are important alternatives in the extractive processing of gold, copper and nickel ores. The application of advanced control to pressure leach and pressure oxidation autoclaves could achieve significant benefits as has been shown in alumina pressure leaching. This paper compares and contrasts alumina digestion autoclaves to other mining autoclaves with respect to advanced controls. The application of advanced control in alumina with over 30 units controlled worldwide, and its benefits will be reviewed. The design and potential benefits from advanced control for pressure oxidation and leaching will be presented.INTRODUCTIONIt is this author's position and the purpose of this paper to propose that advanced control could be effectively applied to autoclaves in the nickel, gold, and copper mining processes. This is based on the proven effectiveness of advanced control on autoclaves used in the alumina industry for pressure leaching of bauxite ores. Incremental, but significant increases in production could be realized by applying advanced control to autoclaves, as evidenced by the alumina industry, and this not being implemented in other autoclaves in the mining industry.In addition, today the mining industry is being challenged to improve their production methods. In some markets like nickel, there is pressure to improve productivity and reduce the cash cost per ton. While in other markets like copper and gold, demand is vigorous with favourable pricing, and there are advantages to increase production and productivity given limited plant capacity. Advanced control has proven its capability to improve mineral processing operations through increases in throughput, recovery, as well as reducing variability. In today's mines, autoclaves are being used to a much larger scale and with much larger importance, thus it would be beneficial to improve operational performance through the use of advanced control.Accordingly, it is the author supposition that an opportunity exists in the mining industry to use a proven advanced control technology to improve the operations and financial performance of mines using autoclaves."

Jan 1, 2012

By Michel L. Bilodeau, Brian W. Mackenzie, Dallas W. Davis

"The paper formulates an evaluation procedure for examining the effects of location on the economics of developing mineral deposits. This methodology is applied to assess locational aspects of Nova Scotia's competitive position f or mine development relative to other Canadian regions and provinces. The appraisal concerns two representative mine development opportunities, a medium-size open-pit tungsten deposit, and a small underground gold deposit. The influence of regional economic conditions is initially assessed. Then, the consequences of taxation are isolated. Finally, the combined impact of regional and taxation conditions is examined. SettingThe economic potential of mining may be assessed in a number of ways. One approach, increasingly used for both corporate planning and government policy purposes, is to evaluate the competitive position of an actual or potential mineral producer in the international marketplace relative to other suppliers.Such examinations of competitive position vary from cost league comparisons of breakeven costs for operating mines, through the assessment of medium-term costs associated with developing new mine capacity, to long-term evaluations of the economics of mineral supply from the start of exploration. The complexity of the analysis increase s with the scope and timeframe of interest. Many factors are involved. One component of competitive position is the quality of the mineral resources available. Other key factors include existing technology, wage and salary rates, labour productivity, the cost of capital, infra structure requirements, distances from sources of materials supply an d to mineral markets, management attributes, organizational efficiency, government mineral policies (particularly taxation), and inflation and exchange rates. The paper fits within this competitive position framework.The variable economic conditions which exist within Canada have a direct bearing on the viability of mine development and, thereby, on mineral exploration potential. The paper examines locational aspects of Nova Scotia 's competitive position."

Jan 1, 1986

Flotation works very well for particles that are typically in the range 20 to 150 µmin diameter, for base metal ores. In this range, it is possible to get quite high recoveries in conventional flotation machines. Outside this range, the recoveries decline progressively, whether it be with the very fine or the coarse end of the size spectrum. In this paper, the reasons for the drop-off in recovery are briefly reviewed, together with strategies for future work. Recent progress in the author's laboratory will be described. These include the Concorde Cell, which takes advantage of the high dissipation rates in the shock wave created when a gas-liquid mixture reaches supersonic velocities. The environment thus created is very beneficial for the flotation of ultrafines. For coarse particles, the reasons for the drop-off in recovery can be related to the highly turbulent nature of the pulp in a conventional flotation cell. To improve recovery, it is necessary to find a way of bringing particles and bubbles into contact in a quiescent environment. A new process for coarse particle flotation will be described, in which a fluidized bed is created in the flotation cell. The flow conditions are very gentle, and the high solids concentration leads to rapid rates of capture of the particles. Experimental results are presented. It is apparent that the maximum floatable size for coal and minerals can be increased by a factor often over the limits found in current practice. Advances

Jan 1, 2009

By Paul R. Terry

This paper presents a brief picture of the quality of coal produced in Eastern Canada for use in thermal generating stations. It describes, in particular, the characteristics of coals burned in six power plants -two in New Brunswick and four in Nova Scotia. Each station is dis-cussed in turn, and comments are made on the coals used therein with regards to origin and physical and chemical properties affecting station operation. A table of coal data shows, at a glance, the wide variation in the quality of coals received by these stations from producers in New Brunswick and Nova Scotia. "The promotion of improved coal quality for thermal generation can benefit our national economy." T HIS is the opening statement in a paper which was presented by Mr. D. A. Pirttinen at the Coal Division's Toronto meeting in April, 1960. In bringing the power engineer's viewpoint to the coal producers' attention, Mr. Pirttinen made a survey of utility steam plants operating in Canada, and the results of this survey formed the basis for his paper, which he titled: "Generating Station Coal Quality.

Jan 1, 1965

By Pritii Tam Wai Yin, Tony Leong, Neetu Bansal, James Vaughan, Amiel Boullemant

Mercury is a toxic element that is associated with many industrial activities including the Bayer process. Mercury is known to enter the Bayer process with the bauxite feed material and has the potential to accumulate as the process solution is recycled. This paper explores the speciation of mercury in Bayer process streams. The process parameters considered are the oxidising-reducing potential, basicity and temperature. The results of a refinery circuit survey are presented and compared with the thermodynamic predictions. Electrochemical measurements on relevant synthetic systems are also included.

Jan 1, 2014

By J. E. Gillespie

Introduction Mineral wool may be defined as "rock, slag, or glass fibres made by a process of melting and blowing by steam or air, containing a minimum of oil and unfiberized material" (U.S. Bureau of Standards CS 117-44). The earliest production of the material was in Wales, about one hundred years ago. In the United States, the industry daces from 1870 when a plant, using slag as raw material, was established in Greenfield, New Jersey. It was not until 1897, however, that large-scale production was commenced on this continent at a plant in Alexandria, Indiana, which utilized rock from nearby deposits. Today, mineral wool is manufactured in many parts of the United States and Canada, the plants for the most part being in close proximity to deposits of suitable rock or to sources of slag. In the United States there are some seventy-five producers with a total annual capacity of nearly one million tons of wool. In Canada, in 1946, eleven manufacturers produced about fifty million square feet of batt-type mineral wool insulation material. Mineral wool is, perhaps, the most efficient of all heat-insulating materials and, moreover, it is fireproof, extremely durable, and insect- proof. Its high efficiency is due to the very low thermal conductivity of the fibres themselves and to the fact that the produce as marketed contains up to 90 per cent non-conducting air space. Depending on the degree of compression of the fibres in the manufactured product, the specific gravity ranges from 2 lb. to 10 lb. per cubic foot. Products Marketed Following are the principal forms in which mineral wool is marketed: Blanket. - Mineral wool with or without reinforcing on one or both sides, with various types of confining media, all suitably bound together.

Jan 1, 1948

By N. C. Karmakar, Y. V. Rao, M. Aruna

No one can properly work without sufficient light and this is especially so in mines where conditions are difficult. Artificial lighting is very important for the night shift to provide a safe and efficient working environment, which must be evenly illuminated with no obvious dark spaces and a minimum amount of glare. During an illumination survey of a large mechanized surface mine, it was found that the illumination level varied and was not uniform throughout the length of the road; it was high at one side of the road instead of at the centre. There were also different combinations of lamps, with angles of light arm varying from 35º to 70º. In this respect, an experimental study was carried out with a fabricated telescopic light pole to uncover the optimum design parameters of lighting installations. The analysis was done by plotting isolux contours for fixed installations and drawing graphs for various combinations of luminaries, reflectors, light arm angles, and height of lanterns by plotting the horizontal angle of the light arm along the abscissa, and the contour area along the ordinate. The study revealed that the design parameters of the lantern are mainly dependent on the type of luminaires. It was revealed that the pot reflector with a combination of tubular bulbs produces a wide distribution of light, and contributes towards a reduction of luminaries when installed in longer roads.

Jan 1, 2005