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By S. R. McCutcheon, D. R. Lentz, W. S. Downey

"Abstract - The Little Falls member of the Nepisiguit Falls Formation is situated in the northern part of the Brunswick Belt of the Bathurst Mining Camp and has been interpreted as the distal equivalent of proximal tuffaceous rocks that host the stratiform Brunswick No. 12 and No. 6 Pb-Zn massive sulfide deposits. It comprises fine-grained, greenish-gray tuffaceous sandstone in the lower part, and coarse-grained, crystal-rich tuffaceous sandstone in the upper part. Petrographic evidence suggests that these rocks have a turbiditic origin. The Little Falls member is underlain by the Vallée Lourdes member, mainly composed of relatively shallow-water calcareous rocks, and is conformably overlain by Mn-rich sedimentary rocks, mainly red argillites that host the Tetagouche Falls Mn-(Fe) deposit. All these rocks are considered to belong to the Nepisiguit Falls Formation, part of the Ordovician Tetagouche Group. Whole-rock geochemical data from the fine-grained tuffaceous sandstone and coarse-grained tuffaceous sandstone indicate that the two units of the Little Falls member are distinct. Zr and TiO2 contents, and total rare earth element (REE) values are higher in the coarse-grained unit (average Zr/TiO2 = 0.040, average SREE = 247 ppm, n = 6) than in the fine-grained unit (average Zr/TiO2 = 0.048, average SREE = 158 ppm, n = 17), which can be attributed to the variation in crystal content between the two units. Both units are HREE-enriched and have elevated La/Yb relative to the typical Nepisiguit Falls Formation. Overall, the geochemical data combined with evidence from the bounding units suggest that the Little Falls member was deposited in relatively shallow water, possibly in a near-arc environment. The relationship of volcanic facies within the Nepisiguit Falls Formation and the geochemistry of these facies indicate strongly that fine grained, reworked tuffaceous rocks, regardless of whether they are the distal equivalents of proximal tuffaceous rocks, are not associated with the major ore-bearing horizons of the Bathurst Mining Camp. Sommaire - Le Membre de Little Falls de la Formation de Nepisiguit Falls se retrouve dans la partie nord de la Ceinture Brunswick du Camp Minier de Bathurst ou elle a été interprétée comme l’équivalent distal des roches tuffacées proximales hôtes des gisements de sulfures massifs de Pb-Zn stratiformes Brunswick No.12 et No.6. Il consiste en grès tuffacé à grains fins gris verdâtre dans sa partie inférieure et en grès tuffacé à grains grossiers riche en cristaux dans sa partie supérieure. Les données pétrographiques suggèrent que ces roches ont été déposées par des courants de turbidité. Le Membre de Little Falls repose sur le Membre de Vallée Lourdes, lequel consiste principalement en roches calcareuses déposées en eau relativement peu profonde; il est de plus recouvert en concordance par des roches sédimentaires manganifères, lesquelles consistent principalement en argilites rouges hôtes du gisement de Mn-(Fe) de Tetagouche Falls. Toutes ces roches appartiennent à la Formation de Nepisiguit Falls, laquelle fait partie du Groupe de Tetagouche, d’âge Ordovicien. Les données lithogéochimiques des grès tuffacés à grains fins et à grains grossiers indiquent que ces deux unités du Membre de Little Falls sont distinctes. Les teneurs en Zr et en TiO2, ainsi que la teneur totale en Éléments des Terres Rares (ÉTR) sont plus élevées dans l’unité à grains grossiers (Zr/TiO2 moyen = 0.040, SREE moyen = 247 ppm, n = 6) que dans l’unité à grains fins (Zr/TiO2 moyen = 0.048, SREE moyen = 158 ppm, n = 17), ce qui pourrait s’expliquer par la variation de la quantité de cristaux dans chacune de ces deux unités. Chacune de ces deux unités présente un enrichissement en ÉTRL ainsi qu’un rapport La/Yb relativement plus grand que ce qui est typiquement observé dans la Formation de Nepisiguit Falls. Les données géochimiques considérées conjointement à l’information provenant des unités adjacentes suggèrent que le Me"

Jan 1, 2006

By H. J. Oterdoom

SMS Group (SMSG) has always been concerned about safety aspects of electric smelter plants for the ferro-alloy and non-ferrous industry. The awareness for safety increased significantly over the past decades and also SMSG contributed with its design features to a safer operation. Today, safety aspects are not only part of the smelter design but also of the overall plant layout. Explosions in electric smelters are rare, but have a huge impact on peoples’ lives, on equipment and on production. For this reason, SMSG wanted to have a better overview of explosions within the smelting industry in order to see if useful statistics could be extracted. Generally, there is a lack of statistics regarding explosions in the electric smelting industry, and not enough information is collected or published. A significant portion of the explosions seems to be water related. Many companies, both operating and engineering, are trying to handle the risks of water, and apply methods to detect water leakages. Installing such a system is a management decision and management has then to make sure the system is properly implemented. The disadvantages and limitations of these systems should be carefully considered and communicated to operators and authorities.

Jan 1, 2015

By I. I. Inculet, M. A. Bergougnou, J. D. Brown, R. M. Quigley, D. K. Faurschou

"Coal from Hat Creek, B. C., has been successfully beneficiated to remove ash while retaining calorific value by a dry electrostatic separation process using a fluidized bed for triboelectrification. Two samples of Hat Creek coal used in the beneficiation experiments have been characterized particularly with respect to their mineral and clay content. The calorific value recovery exceeds the simple dry coal recovery because of the heat lost in altering the clay minerals of the ash fraction during burning. Recoveries and ash contents of the beneficiated coal are comparable to recoveries by water washing, but the dry process avoids the potential water pollution problems.IntroductionProposals have been made which suggest an interim Canadian coal production target for the end of the century which will require a four- to fivefold increase over the 1977 production. This implies a nominal annual growth rate of about 6070 to achieve a production rate of 115 to 140 million tonnes/year. Whether or not this target is realistic, it is becoming increasingly evident that coal must be utilized more fully on a world-wide basis. The crisis in Iran has provided the latest stimulus to renewed interest in Canadian coals for domestic use and export.The emerging new era of coal utilization for fuel and chemical feedstock will not, however, generally tolerate the level of coal technology which prevailed prior to the availability of abundant cheap oil and natural gas. Economic, environmental and resource management considerations will necessitate, for example, the use of improved methods of beneficiating coal. Continued development and application of conventional processes, principally aqueous, involving heavy media and cyclones will solve many of the problems. However, less conventional processes may be preferable or necessary in certain applications."

Jan 1, 1980

By S. Kashani Nejad, M. Bellino, K. Collins, C. Tovee, J. Godwin

Motivated by safety considerations, logistical issues, transportation cost savings, product diversification, and marketing preferences, several uranium producers are revisiting their business models and supply chain configuration and, instead of selling dried yellowcake to downstream refineries, they are moving to build in-house calcining facilities. Drying and calcining plants are relatively low-cost facilities to build and operate. The execution period of a typical yellowcake drying and calcining project is also relatively short and alternative construction methodologies, such as modularized solutions, are available. The drying and calcining technologies used for yellowcake are relatively mature, environmentally contained, and well supported by qualified vendors. The drying and calcining circuits also seamlessly integrate with upstream and downstream operations. These either produce a dried yellowcake or calcined U3O8 which are notably safer and easier to transport and market. This paper presents an overview of the recommended technology and project development considerations for yellowcake drying and calcining facilities.

Jan 1, 2020

By Edouard Asselin, Tasawar Javed

This study was conducted as a part of ongoing work to characterize sulphide concentrate leach residues generated under CESL (Cominco Engineering Services Limited) and Vale pilot and demonstration plant medium temperature (150 °C) process conditions. Three different samples were analyzed. Derivative samples were prepared by extracting gypsum, sulphur and amorphous/poorly crystalline iron oxyhydroxide phases from the leach residues. Thermal behavior of the samples was studied by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) in the temperature range 25 to 800 °C in both air and nitrogen atmospheres, with XRD analyses both before and after heating. Thermal transformation temperatures for different iron oxides/oxyhydroxides present in hydrometallurgical leach residues vary over a wide range which suggests the variable crystallinity of the phases. Raman spectroscopic analysis was carried out to help identify the type of iron phases in the residues. Furthermore, hydroxylamine hydrochloride (HaHC) and oxalate extractions were used to compare the fractionation of the amorphous/poorly crystalline iron phases in the residues. Given the compositions of the residues, any thermal events in the temperature range of 200 °C to 480 °C were attributed to amorphous/poorly crystalline iron phases.

Jan 1, 2014

By R. D. Hossack

"The selection of a site for plant facilities is a function of several factors and has as its objective the maximization of profits, given fixed markets and sources of raw material locations. In practice there are several sites, any one of which or a combination of two or more would be suitable to meet the basic requirements of source of supply of raw material and labour and still fulfill market demands. The model used to select the optimum profit combination utilizes both computer programs and traditional financial analysis techniques. Of the three computer programs used in the mode), one is a linear program and another is a transportation simulator. Basic cost and price data are required. In examining costs, three levels are used: (a) distribution costs of raw material to the plant and finished goods to the market; (b) direct production costs at the plant, such as labour and locally supplied material; and (c) capital and overhead costs at the plant, such as construction costs, taxes, insurance, and federal and provincial cost allowances. The direct costs generally depend on the scale of operations, so that a large plant in one location may have a lower unit cost than two smaller plants. This, of course, must be balanced against distribution costs. In examining profit, it is necessary to think in terms of the price and volume of sales at each of the market locations. Given basic data and relationships, the model can be used to optimally locate production facilities or, alter-natively, optimally structure a transportation network given existing locations of plants and markets. It is dynamic to the extent that it can react to changes in volume, price and cost to optimally locate an additional plant, the expansion of existing plants, the shutting down or cutting back of plants, or the restructuring of distribution networks."

Jan 1, 1970

By D. M. Ramsey

HIGH-INTENSITY magnetic separation as now practised in the commercial treatment of a large variety of industrial minerals is a com-paratively recent development, having had its practical beginning about ten years ago when it became necessary to devise more effective methods for the purification of the electric furnace abrasives and refractories-silicon carbide and fused aluminium oxide. The fundamentals of magnetic separation are, of course, very well under-stood; bur while very, very old in principle, the process has, in recent years, been developed to a point of far greater usefulness than heretofore. In fact, until the development of the high-intensity process,. magnetic separation was limited largely to the removal of tramp iron? with magnetic pulleys and the removal of the very highly magnetic portions of industrial minerals by means of horizontal conveyor-belt-type separators. All magnetic separation processes depend for their success on the fact that various materials are kinetically influenced to a greater or lesser degree by the force that we speak of as 'magnetism'. We have now come to regard 'magnetic separation' and 'high-intensity magnetic separation' as two different and distinct methods. However, both depend upon the reaction of a particle when placed in a magnetic field. The common types of magnetic separators quite generally operate on the principle that a magnetic particle can be lifted by a powerful magnetic force from a stream of material moving on a belt or other type of conveyor. The application of the force removing magnetic material by this scheme is directly opposed to the force of gravity and is, therefore, limited to sub-stances of a relatively high order of magnetic susceptibility, such as metallic iron and magnetite. Until a few years ago, one very important principle was almost entirely overlooked. Practically every substance is susceptible to some extent, at least, to magnetic attraction, and by the application of a magnetic force great enough, and properly applied, separations of materials heretofore considered 'non-magnetic' can be accomplished.

Jan 1, 1937

By Glen Robertson, Jeff McLaughlin

"The Clarabelle Mill rock tailings have the potential to generate sulphuric acid through chemical and biological oxidation of sulphide minerals. Current rock tailings assay between 0.80 -1.40 %S, with sulphur occurring principally as coarse pyrrhotite. Acid generation within the tailings area can be substantially reduced by segregating pyrrhotite rich tailings in a submerged storage area and by depositing only low sulphur rock tailings in exposed areas. Laboratory tests confirmed that low sulphur tailings could be produced by flotation at reduced pH with a small xanthate addition. A plant test was conducted to evaluate the production of low sulphur tailings in conjunction with INCO's continuing commitment to environmental protection and progressive decommissioning of the metallurgical site.During the plant evaluation, approximately 5% of the mill rock tailings were reprocessed in a line of 100 tt3 Denver flotation cells. Tailing grades below 0.40% S were easily achieved through operation at pH 6 -7, with xanthate addition (dosages up to 0.02 lb/ton) and 10 -15 minutes of nominal retention time. Froth depths between 1 -3 inches combined with relatively liberal amounts of frother were required to pull the lightly mineralized froth into the concentrate which averaged 11% sulphur and less than 5% mass recovery. In addition, three field lysimeters were each filled with two hundred.ton bulk samples of low sulphur tails (0.35% S), standard rock tailings (0.98% S), and mill total tailings (2.30% S) for long term monitoring. The implications for full scale plant design, tailings area decommissioning, the possibility of increased nickel recovery and preliminary field lysimeter data are discussed."

Jan 1, 1994

By T. T. Chen

The iron- and elemental sulphur-rich residues generated during batch and continuous pressure oxidative leaching of Inco Limited's Voisey's Bay nickel sulphide concentrate at 150°C in sulphate-chloride media have been characterized by X-ray diffraction analysis and scanning electron microscopy. The residues produced during the continuous leaching of the pentlandite- and pyrrhotite-rich concentrate consisted predominantly of hematite and elemental sulphur, with minor amounts of goethite. Although the iron species generated in the batch leaching tests were similar to those formed during continuous leaching, the morphologies of the hematite and goethite particles were significantly different. In addition to the tiny spheroids and bubble-like particles, the hematite and goethite generated during batch leaching occurred as larger "hollow" shell-like particles that contained residual pentlandite or sulphur cores. Although the leach solution from which the iron oxides had precipitated contained 5-15 g/L sodium, sodium jarosite was detected only in trace amounts in a few of the leach residues.

Jan 1, 2006

By J. Dubinski

Underground mining of copper ore in the Legnicko-Glogowski Copper District basin generates a number of seismic events, whose energy often exceeds 108 J (Butra, 2010). The number of tremors and their location shows that the area of rock mass involved in the deformation and failure processes significantly exceeds the area of mining operations. Locations of seismic foci of high energy tremors, as well as the aftershocks that accompany them, extend hundreds of metres, confirming that processes to restore the energy balance of rock mass occur in a short amount of time and over a wide area. Thus, an area of similar size should be considered in predictive analyses of the tremor?s position. It should be emphasized that a large portion of the rock mass still has a level of freedom resulting from the way the rock mass is held together and its geometric continuity. This level of freedom is dependent on the scale and duration of mining, the number and size of natural structures, and rock mass pressure, including gravitational pressure constricting individual fragments of rock mass in the area (Burtan, 2012). It can therefore be assumed that in real conditions, areas where mechanical strength of the layers has been exceeded may be located a considerable distance from each other and do not necessarily need to coincide with the working area location. In this sense, a rock mass influenced by mining exploitation is essentially a rock mass in which numerous fragments with concentrated energy exist simultaneously. Energy will be released within these rock mass areas each time rock mass strengths are exceeded by the induced stress changes related to mining operations. This paper presents a discussion on how to predict the location of seismic activity areas based on a change of position of seismic energy equivalents. This parameter is calculated for a given set of seismic tremors with defined foci coordinates. For a given set of seismic tremors, the location of seismic energy equivalents may be used for predicting the location of high-energy seismic events.

Aug 1, 2013

By G. A. McGuffin

"IntroductionWITH the increase in quantity of sour gas reserves in the Province of Alberta, and the wider market for sulphur brought about by mounting world demand and restrictions placed on the principal supply, it was inevitable that this important source of sulphur would be .developed. In the light of these facts, it seems timely that a general paper on sulphur recovery from petroleum gases be presented. This, then, is the purpose of the following text. A short discussion of each of the following subjects is presented:(1) Properties and uses of sulphur(2) Existing sources(3) Market research(4) The recovery process in Turner Valley(5) Hazards of sulphur productionNo pretext of originality of material is made since innumerable reports have been prepared on this and related topics and information contained in these has been used quite liberally.Properties and uses of SulphurSulphur is a non-metallic element having an atomic weight of 32.06. The stable crystalline form at atmospheric temperature is referred to as 'rhombic' sulphur. It is bright yellow and has a specific gravity of 2.05, equivalent to 129.2 lb./cu. Ft. Above 204°F. sulphur has another stable crystalline form, referred to as 'monoclinic'. This is reddish-brown and is slightly less dense than the rhombic variety (122.4 lb./cu. Ft.). Sulphur in bulk form weighs 84 to 90 lb. per cu. Ft. Sulphur melts at approximately 240°F. to a straw coloured liquid which is quite viscous."

Jan 1, 1952

By Fiona Campbell

"Modern history is full of breakthroughs in technology, all striving to increase productivity and efficiency. What are the elements that should be taken into consideration in the design and implementation of modern automation systems in a control room? Both industry and international standards are now demanding that Human Factors be considered as part of the design of control rooms to maximize efficiency and minimize the potential of human error which can lead to downtime and a loss of profit as a result of interruptions in production. As the current workforce ages and the younger generation matures, this is also becoming a key element when planning a control room. New standards are helping to address some of these challenges that are facing the mining industry today. With an increased focus on the operator, an intelligent and ergonomic workspace can both mitigate risk and optimize production. Optimization is money. We will examine how to analyze and implement innovative control room planning to maximize mineral processing production and minimize risks that can impact overall production and profit.INTRODUCTIONIn this day and age, optimization of production in an industrial environment is becoming more and more of a challenge. With ever changing technology as well as other external factors, this can be especially daunting. There are several key elements that may not be immediately obvious when planning a control room design or renovation, most notably the role of the human in this environment. Fatigue, stress, distraction, reaction times and situational awareness are all critical in a 24/7 environment. With the growing need to include human factors when considering and designing an optimal work and production environment, it is becoming even more important to design a control room that can address as many of today’s challenges as possible.The standard definition of the word “optimization” is “an act, process or methodology of making something (as a design, system, or decision) as fully perfect, functional or effective as possible.” (www.merriam-webster.com). If we apply this to business, what it really means is finding the most cost effective way to achieve the highest level of performance while considering constraints, both external and internal, by maximizing the desired factors and minimizing undesired ones. Sometimes, however, we can get caught up in the day to day processes, without taking a moment to step back and objectively review what it is we need to achieve, and more importantly, the steps that can facilitate our success."

Jan 1, 2016

By T. E. Morimoto

Summary The Research Council of Alberta has made a series of tests with the cyclone washer to investigate the influence of the following operating variables: underflow apex diameter, .specific gravity of medium, pulp ratio, density distribution of the feed, and size analysis of the feed. The results obtained for all the variables studied, except size analysis of the feed, are included in this paper. The tests were made with smaller underflow apex diameters and lower specific gravity .suspensions than have been recommended by Cerchar for the sharpest separations. However, what is considered to be sufficiently good cleaning was accomplished with a suspension of 1.30 specific gravity and an underflow to overflow diameter ratio of 0.56. It was found that the sharpness of separation was not affected appreciably by variations in specific gravity of suspension or underflow apex diameter provided that the density of separation was within the normal range of washery operation. Cyclone performance was not too adversely affected by decreasing the pulp ratio. The minimum figure which gave reasonable separation was 4 to 1. The tests with various density distributions of feed revealed .that the degree of washing difficulty had no detrimental effect on the .sharpness of separation given by the cyclone. Introduction A major problem of the bituminous coal industry today is that of reducing the ash content of the finer sizes (minus 1/4-inch) of coal. This problem is particularly acute in Alberta, where, because of tectonic movement subsequent to deposition, the coals have been rendered friable, and bands of impurities have been intimately mixed with the clean material. As a consequence, most Alberta coals, as mined, contain a large proportion of fines and have a high inherent mineral-matter content. The advent of mechanized mining and stripping operations ?has further aggravated this problem.

Jan 1, 1952

By Dharmendr Kumar, Pradip, Beena Rai, Venugopal Tammishetti

"Due to rapid depletion of high grade Indian iron ores, there is a need to utilize low grade fines and slimes. However, these fines and slimes, in their current form, cannot be utilized in steel making due to their high alumina (6-10%) contents. Several beneficiation strategies such as gravity separation, magnetic separation, flotation and selective flocculation are currently being explored for the upgradation of low grade fines and slimes. In our previous work density functional theory simulations were employed to come up with selective flocculants for beneficiation of iron ore slimes. Our simulation results suggested that starch and guar gum are more selective towards iron minerals than other minerals present in the sample. Grinding of iron ore fines becomes necessary in some cases to achieve adequate liberation for removing alumina impurities in Indian iron ores. We have thus investigated effect of grinding of iron ore fines on its selective flocculation-separation.In the present work, we have taken natural iron ore fines from one of the Indian iron ore mines and ground it to -400 mesh (<37 microns) in dry and wet conditions. X-ray diffraction study confirmed the presence of minerals hematite, goethite, gibbsite and kaolinite in the sample. The fine ground samples were used in selective dispersion-flocculation study with corn starch and guar gum flocculants. It is interesting to note that even though the dry and wet ground samples possess almost similar particle size distributions, significant differences were observed in yield and grades of the concentrates thus produced. These differences may be arising due to the coating of alumina containing minerals on iron minerals. We have also studied the effect of addition of dispersant while grinding. Our study suggests that grinding conditions determine the efficiency of the separation process."

Jan 1, 2016

By V. K. Karra

"A simplistic algorithm jar simulating the rod or ball mill Bond grindability test applied to ores and minerals is presented. A performance comparison between the present algorithm and a previously published algorithm by Kapurot, modified in this work jar a fair evaluation, is also given. A worked example is furnished jar leading the reader through the various calculations.IntroductionThe Bond grindability test is widely used for the prediction of the power requirement of an industrial grinding mill. The procedures for conducting this test in either a ball or a rod mill are available(1). In the case of a ball mill, batch grind abilities have been correlated to Bond grindabilities to help monitor day-today variations in ore grindability for the purpose of plant control( 2,3). Of special interest is the algorithm presented by Kapur(3) for the simulation of the Bond test. In practice, the test lasts from 6 to 14 cycles (4 to 10 hours). With this algorithm, one can predict the Bond grind ability using information available from only the first two cycles.Sometimes the prepared feed for the grindability test contains too much fines compared to the total product desired at the mesh of grind under consideration. In such a case, the operator separates the fines from the test feed and adds to the remaining coarse fraction an equal amount of fresh feed. This combined feed then forms the feed to the first cycle of the test. In the present work, Kapur&apos;s algorithm is modified to include this special case. A new and relatively simpler algorithm is also presented. Statistical equations relating work index to pertinent variables are also given."

Jan 1, 1981

By Thom Sedun

No sector of the mining industry is more closely tied to local communities than aggregates. Noise, dust, traffic, visuals aesthetics and environmental impacts all fall under the purview of neighbours, local governments and nongovernment organizations. It is no surprise that aggregate operations may not be welcome neighbors in many communities. In British Columbia (BC), the regulatory environment for aggregate operations includes a local component of municipal bylaws and land use-planning in addition to the usual suite of federal and provincial statutes that apply to its sister mining sectors. Additionally, under common law aggregate extraction is not considered to be a land use subject to land use zoning, and some aggregate processing activities can be regulated by zoning. Often traversing multiple local government jurisdictions, aggregate producers find themselves negotiating not only local traffic, but also a mosaic of regulatory environments. There is an opportunity in this present situation to facilitate the application of current technology and practices in the mitigation of many community and environmental concerns associated with aggregate operations. Moving a bulk commodity is a volume-based business, and operators often don?t have time for matters that don?t directly or obviously affect the bottom line. Regulatory agencies often play multiple and complex roles with respect to their industry, not the least of which is the fiduciary role. Balancing how and when to assist an industry is often a difficult decision. For the aggregate industry in BC, the Ministry of Energy and Mines saw an opportunity to assist not only aggregate operators, but also regulatory agencies, local governments, and the general public. Through investing in the Aggregate Operators Best Management Practices Handbook (handbook) project, the Ministry of Energy and Mines (MEM) believes that it will realize a return of upheld community values, enhanced environmental protection, improved regulatory compliance, reduce disputes and a stronger provincial aggregate industry. It is the intent to publish the handbook electronically through the MEM website later this year.

May 1, 2002

By C. H. Madsen

THE Hard Rock gold mine is in the Little Long Lac mining area, Thunder Bay district, northwestern Ontario. It is four miles by road from the town of Geraldton, which is on the Canadian National railway, 180 miles northeast of Port Arthur. The original discovery of gold-bearing quartz veins on the property was made in 1931. Shaft sinking began in the fall of 1934 and approximately 7,400 feet of lateral development on four levels was completed. In 1935, further discoveries were made half a mile west of the early workings, and the No. 2 shaft was sunk in this area in a porphyry zone. In January, 1938, a 20C-ton cyanide plant was completed and began drilling ore from the gold-bearing porphyry orebody. The daily feed was increased gradually to 300 tons in the next six months and a recovery of 97.5 per cent was effected. During the summer of the same year, a new and larger orebody was discovered to the north of the porphyry zone. It occurs in a band of iron formation and contains a high percentage of pyrite and arsenopyrite. Extensive tests were rr.ace on this sulphide ore in the Mines Branch ore dressing laboratory at Ottawa, in the laboratory of Canadian Industries, limited, at Toronto, and later at the mine, to find a suitable method of treatrr.ent. As a result of this research, a Potation plant was added to the original cyanide mill and on November 7th, 1938, differential flotation was used to separate the pyrite from the arsenopyrite fraction of the ore. The pyrite concentrate was re-ground and cyanide:l, and the arsenopyrire concentrate was stored for subsequent treatment. Differential flotation was discontinued in April, 1939, in favour of bulk formation of all the sulphides, and the whole cyanide residue was stored. On March 15th, 1939, a 10-ton pilot roaster was completed and rests were conducted on the arsenopyrite concentrate and the bulk concentrate. The results obtained led to the building of two roasters of the same type, large enough to roast all the concentrates. These roasters were put in operation on September 24th, 1939, and the calcines were cyanided in the original circuit.

Jan 1, 1941

By R. F. Robertson

"Adsorption isotherms of hexyl mercaptan vapour on synthetic sphalerite, zinc sulphide and zinc oxide were de-termined with a gravimetric McBain-Baker micro balance incorporated in the B.E.T. apparatus. Isotherms are given for hexyl mercaptan on synthetic sphalerite at 25°C, 0.5°C and 50°C; on zinc sulphide at 25°C and 1.5°C; and on zinc oxide at 25°C. All these isotherms are sigmoidal, with a definite change in slope at or close to the mono-layer. The amount of mercaptan adsorbed below the monolayer increases almost linearly with relative pressure to P/P0 = 0.8.Above this value, the amount adsorbed increases very rapidly with relative pressure. Hysteresis loops appear in the isotherms for all adsorption-desorption cycles. These loops are completely reversible. It is not possible to desorb the mercaptan monolayer from any of the adsorbents, even at elevated temperatures."

Jan 1, 1966

By J. B. Mawdsley

From the view point of the mining engineer, the square-set method of stoping as practised at Butte, Montana, is one ?of the outstanding features of well conducted mining operations in that camp. The following information was obtained in the course of two months underground work in the Granite Mountain mine, during the summer of 1920, which is one of the properties of the North Butte Mining Company, situated on the well known Speculator vein. Most of the information was derived from personal observation and from discussions with various miners and with members of the staff. Geology The copper mining area of the Butte district is some two miles long by one and a half miles wide, a mineralized area in a great batholith of monzonite granite, locally known as the Boulder batholith. This extensive body of granite is traversed by several series of mineralized fault-fissures which differ in strike but generally dip steeply. Geologists agree that following the formation of the fissures, alkaline solutions ascended and decomposed the felspathic portions of the granite in the immediate vicinity of the fissure walls, and that these alkaline solutions were followed by cupiferous solutions which filled the fissures and replaced the granite next to the walls. A zone of oxidized ore, varying in thickness from 10 to 400 feet, overlies a sulphide zone containing chalcocite, enargite, bornite and chalcopyrite, with a small amount of quartz gangue. The veins are from 3 to 100 feet in width and contain, on the average, 3 per cent of copper, 2 ounces of silver, and 15 cents in gold per ton.

Jan 1, 1925

By Jozef S. Stachula

"INCO Limited operates eleven under-ground mines in the Sudbury area. The mines are located on the rim of the Sudbury Basin, an oval with the axis in the range of 27 km and 60 km. The ore dips to at least 3000 m below surface. The ores are mined primarily for nickel and copper. Total ore production from underground is in excess of 55 000tonnes per day.Over 40 surface fans have been installed since the late 1960s. All of the fans are adjustable pitch, axial flow units. A major factor influencing ventilation design in the last 30years has been the introduction of diesel equipment underground. Volumes per fan have ranged from 60 m3/sec. to 330 m3/sec., with motors from 100 hp to 2500 hp.Fans of the axial flow type have been commonly used for main fan installations at Canadian mines for many years. The standard arrangement has been to mount these fans horizontally, i.e. with the fan shaft and the long axis of the housing horizontal. This is a natural arrangement for an underground fan, but for a surface installation, a vertically mounted fan has definite advantages.The surface area taken up by a typical vertical fan installation is generally about one quarter that of a horizontal fan of the same capacity (Rutherford, 1957). This is not a problem with isolated fans and fat surface out crop sites, but where the installation is to be near existing buildings, or where there are poor surface soil conditions, space and cost considerations greatly flavour vertical fans."

Jan 1, 1996