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By T. Alan O'Hara

"Annual mining revenue can be computed by formulae relating metal prices, smelting schedules, concentrate grade and recovery to known ore grade and an assessment of core samples. Operating costs at different daily tonnages are related to orebody shape, mining method, milling process and general plant services. Capital costs are related to sizing of mining equipment, mine development, plant-site topography, climate and accessibility, plant services and personnel housing. IntroductionA crude guide to the average 1978 cost of mine projects is shown in Figure 1, but the costs of many mine projects have differed widely from the graphed average costs of $800,000 T0.6 for underground mine/mill projects and $400,000 T 0.6 for low-grade open-pit mine/mill projects.High mine project costs and high operating costs are characteristic of open-pit mines with high stripping ratios, underground mines with thin orebodies, mills with complex metallurgy, and projects located in isolated regions with severe climate, mountainous topography, and lacking access to existing roads, towns and electric power. When none of these adverse conditions prevailed, the mine project cost was typically much less than the graphed average cost. Virtually all the conditions likely to cause high capital and operating costs are known from knowledge of the local topography, climate or accessibility, or can be assessed by tests on core samples, as soon as the orebody has been outlined by drilling .A more accurate estimate of over-all project capital cost and operating cost can be made from a summation of items of cost after judging the effect of specific local conditions on each item of capital and operating cost. This paper offers guides in judging the effect of local conditions on the sizing and 1978 cost of specific items of capital cost and operating cost and operating cost of mine projects. When the specific items of capital cost and operating cost are totaled and measured against expected net revenue and taxes over the life of the mine using the net-present-value or discount-cash-flow methods, the result should show whether the mine project development is clearly feasible, doubtfully feasible or clearly uneconomic. If the development of the mine project is clearly feasible, or probably feasible, a detailed feasibility study by experienced consulting engineers should be commissioned before any financial commitments are made; but if project development appears to be uneconomic, the time and cost of a detailed feasibility study is not warranted."

Jan 1, 1980

By A. W. Jolliffee

ANY attempt to forecast the mineral resources of a largely unknown region is hazardous and, in the case of the Northwest Territories, such a task is even more hazardous than usual. This is not merely because of the immense territory involved (over a million and a quarter square miles), only a small fraction of which has ever been explored or prospected, but also be-cause both the geology and mineral deposits thus far examined show many unique features, and, finally, because the region is being actively prospected at the present time. However, in view of the present widespread interest in Canada's mineral resources, a brief compilation of what is known regarding mineral occurrences and geology in the explored parts of the far north seems timely. From these assembled data, a few inferences are warranted as to future mineral production from this region. HISTORY The story of mineral discovery in the Canadian northwest is a fascinating one. As well, it abundantly illustrates the importance of mineral occurrences in indicating future mining possibilities. The same sequence of events has repeated itself too often to be merely fortuitous.? In most cases, the dis-covery of a mineral deposit of possible economic value has been foreshadowed by the finding of the valuable mineral or an associated mineral in the same district, generally in small quantity, by an early explorer or traveller. Thus, John Franklin reported oil seepages from the base of Bear Rock, near Nor-man, at almost the very spot where oil was struck nearly one hundred years later. Again, some would-be Klondikers, deterred by the hardships of the route, remained to prospect around Great Slave lake, and were the first to report the Pine Point lead-zinc occurrences there and the gold-bearing veins on Yellowknife bay. Sporadic prospecting followed at the latter locality for over thirty years before the recent rich strikes were made. Similarly, in 1847, Dr. John Rae picked up a boulder of copper ore south of Rankin inlet, on Hudson bay. More than eighty years later, a body of copper-nickel sulphides carrying values in platinum metals was found at this locality. Also, the report of cobalt bloom on the east coast of Great Bear lake brought back by a Geological Survey of Canada party in 1900 was a factor in the events leading to the discovery of silver and radium there in 1930.

Jan 1, 1937

By H. Warren Newcomen, Dennis C. Martin

"This paper describes the investigation of a large, progressive slope failure on the southeast wall of the east pit at Highmont Mine, British Columbia Geotechnical investigation s consisted of geological and structural mapping, assessment of blasthole drilling records, review of rock core information, slope movement monitoring and back analysis of various possible failure modes. Climate records and mining history were also assessed to determine their relationship to slope movement .Analysis of movement monitoring records and geotechnical information indicates that the failure is deep seated. The upper portion of the failure surf ace occurs along clay filled discontinuities. The lower portion of the failure surf ace appears to occur through the highly altered rock mass. High groundwater pressures and mining at the toe of the slope are documented to have had a major influence on stability at various times during the failure. Stability analyses results are presented and possible remedial measures are discussed.IntroductionHighmont Mine is located near Logan Lake in the Highland Valley approximately 50 km southwest of Karnloops, British Columbia (Fig. I). Mining of the porphyry copper and molydenum ore bodies began in 1980. In May, 1983, when mining in the east pit had progressed to a depth of about 60 m (200 feet) , a failure (designated the Southeast Failure) began to develop in the southeast corner of the east pit. Subsequent mining to a depth of 110m (360 feet) was accompanied by frequent and substantial slope movements involving between 500000 and I 000 000 m3 of rock . The slope was monitored extensively to assess short-term movement trends for operational safety. Geological mapping, core logging and rock mechanics testing were used in conjunction with the long-term monitoring information to determine the failure mechanism, conduct stability analyses, assess the effects of instability on pit design and enable design and installation of remedial measures."

Jan 1, 1988

By R. D. Prettie

Wood preservation may be defined as the art of protecting wood from decay. In its broadest sense, however, it includes a much wider field. It might be more properly de-fined as the art of protecting wood from destructive agents, such as decay, insects, marine borers, mechanical wear, etc. The earliest data on record for the preservation of organic bodies is found in Egyptian manuscripts. The bodies which we call mummies were impregnated with antiseptics, of which the principal were natrum (sodium sesqui-carbonate), sodium chloride, and sodium sulphate. After being steeped in the solution, they were subjected to either a boiling or baking process in a bituminous preparation. The first attempts in Europe to preserve timber were made by the Greeks and Romans. They extracted essential oils from the juniper and cypress trees, and either rubbed these oils into the wood they wished to preserve, or bored thousands of small holes in the wood and poured the preservative oil into the holes. The famous statues of Jupiter and Diana were carved out of wood. The ceremony of pouring in the preservative oil by the High Priests was a religious pageant of great importance, of which there are many records.

Jan 1, 1926

By F. F. Langford

"The Athabasca Basin occupies about 100,000 km2 of the northwest corner of Saskatchewan with its western margin extending about 50 km into Alberta (Fig. 1). The basin is filled with a Helikian sequence of predominantly fluvial sandstones up to 1600 m thick. The sandstone beds are generally flat-lying, and rest unconformably on a crystalline basement which consists mostly of granitic intrusive complexes and quartzfeldspar- biotite gneisses. The basement rocks represent Aphebian sediments and Archaean basement rocks that were metamorphosed and remobilized to varying degrees during the Hudsonian Orogeny (ca 1800 Maj.Since 1968, three mining camps and several substantial unconformity-type uranium deposits have been discovered in the area (Figs. 1 and 2). These deposits lie along the unconformity surface, partially enclosed in sandstones, and partially in the basement rocks. The major deposits have elongate, pencil shaped orebodies that are parallel to the strike of underlying graphitic biotite gneisses. The total tonnage of uranium is in the order of 150,000 to 200,000 tonnes and mining grades range from 0.5 to 2.5 per cent U3O8.IntroductionUranium exploration started in Saskatchewan in 1945 when Jolliffe and Murphy headed field parties to investigate uranium occurrences on the north shore of Lake Athabasca (Kupsch, 1978). Their investigation lead to the development of the Beaverlodge camp in the following years. Some of the early prospectors were impressed by the fact that the uranium occurrences at Beaver lodge were centred on a thick sequence of unmetamorphosed arkosic redbeds which are now called the Martin Group. This sequence was referred to as the Athabasca Series by Christie (1949), and although some occurrences of uranium were found near Stony Rapids and Black Lake, the vast expanse of Athabasca sandstones south of Lake Athabasca was generally regarded as unpromising."

Jan 1, 1986

By T. T. Wang, T. H. Huang, Y. C. Chiu

Quantitatively analyzing deformation of a tunnel with lining anomalies for structural safety evaluation is essential for sustainable tunnel engineering. However, a complete theory and associated methodology accounted for displacement of a built tunnel is absent. This manuscript introduces a novel characteristic matrix method proposed by the authors which is an integrated procedure that analyzes displacement of rock tunnels in operation. First, establish a numerical model expressing a specific state of the tunnel in interest. Derive the characteristic displacement modes by a unit disturbances and check their independency. Once the characteristic displacement modes are proved to be orthogonal (independent), they are ready for use. Given a tunnel displacement, modal decomposition returns the magnitude of each characteristic displacement modes that together consist the given displacement. By realizing the definite value of horizontal and vertical translation, rotation, uniform compression/expansion, elliptic deformation, triangular deformation…etc. for a tunnel displacement, one can distinguish tunnel displacement and deformation types from their modal composition. A circular tunnel with elastic structure and surrounded by elastic rock mass is chosen to demonstrate the outcome of characteristic modes and how they work. The influences of tunnel shape, elastic modulus ratio between rock mass and tunnel structure, and numbers of monitoring points on a tunnel profile were also discussed. Identifying possible tunnel deformation causes is attainable if further connections between mode combination and force increments were built.

Jan 1, 2015

By W. J. Wolfe

"Quartz Hill is a large, low- to moderate-grade quartz vein stockwork porphyry molybdenum deposit, discovered in 1974 during a regional stream sediment geochemical reconnaissance survey of southeast Alaska conducted by United States Borax and Chemical Corporation. Mineralization is localized in the upper parts of an Upper Oligocene (30 Ma) composite quartz monzonite stock which is emplaced discordantly into older Cretaceous to Early Tertiary terrain of the Coast Range igneous metamorphic complex of the northwest North American Cordillera. Subsequent fault-controlled, complex multi-stage intrusion, concentrated in the core of the Quartz Hill stock, produced successive pulses of hydrothermal alteration and molybdenum mineralization at about 27 Ma. Overall, the deposit is tabular and flat-lying and well suited to open pit mining. The 0.05% MoS2 grade limit covers an area of approximately 1500 m by 2750 m and extends to a maximum depth of 520 m below surface. Details of grade distribution show two separate lobes of higher grade material within the larger low-grade deposit.A ten year program of exploration drilling, underground development, sampling and metallurgical testwork led to a 1983 feasibility study based on a resource of 1600 million tonnes grading 0.127% MoS2 at a 0.08% MoS2 cutoff The large size of the deposit and its homogeneous grade distribution, typically showing gradual outward decrease of grade, makes in pit grade selection practical at several cutoff levels. Cominco Ltd. now reports a Probable Resource of 210 million tonnes averaging 0.22% MoS2 with a further Possible Resource of 1100 million tonnes averaging 0.12% MoS:z. At low molybdenum metal prices which have persisted for 10 years since the molybdenum price spike of the late 1970s and early 1980s, the Quartz Hill deposit is sub-economic."

Jan 1, 1995

By W. A. Jankola

Teck Cominco Metals Ltd. operates an integrated zinc-lead smelter at Trail, British Columbia, Canada. The zinc circuit comprises three parallel operations: conventional fluid-bed roasting, direct zinc pressure leaching of concentrates and atmospheric leaching of zinc oxide fume recycled from the lead smelter. The products from these three areas are combined in the main leaching plant where they undergo iron purification. Unlike most leaching circuits, the leach process in Trail begins with an acid leach and is followed by a neutral leach. An evaluation was undertaken to determine if the process at Trail could be improved by converting to the conventional neutral leaching process with a subsequent acid leach of the residues. This paper explores the results of these tests and the implications for Trail Operations.

Jan 1, 2006

By C. Cutts, K. Wheatley

The Dragon Lake Zone (uranium prospect) comprises a N160º trending vein that is approximately 110 m long, up to 5 m wide and from 1 to 40 m high. The zone is mostly within altered sandstone of the Fair Point Formation, the basal unit of the Paleoproterozoic Athabasca Group, but it also extends downward (up to 3.5 m) into basement rocks that occupy the northerly trending Maybelle River Shear Zone (MRSZ). This subvertical shear zone separates graphitic paragneiss and weakly deformed granitoid rocks to the east from non-graphitic paragneiss and foliated granitoid rocks to the west. The Dragon Lake Zone cuts across both the MRSZ and N060º-N070º-trending cross-faults that offset the shear zone but not the mineralized vein, which contains values up to 54.5% U over 50 cm core length. Strong chloritization occurs in graphitic paragneiss and sandstone adjacent to mineralization. Silica was depleted from the basement rocks and redeposited at the borders of the 5-15-m-wide alteration zone, as well as within overlying sandstone of the Manitou Falls Formation. There are minimal alteration effects in the overlying Lazenby Lake Formation. Geochemistry shows that the alteration zone in the Fair Point Formation is highly anomalous in metals, most notably in Ni, As, U, Pb, Co, and B. Clay within this zone is illitic and Fe-rich chlorite is also present. Brittle deformation is not as widespread or as well developed in the Fair Point Formation as it is in the overlying Manitou Falls Formation, which is extensively brecciated and contains some anomalous metal values.

Jan 1, 2013

By Denis Racicot

"L'Abitibi québécois a produit essentiellement de l’or, du cuivre, du zinc et de I' argent, ainsi que de faibles quantités de nickel, de plomb, de molybdène, de bismuth, de lithium, de fer et d’amiante. Depuis l’ouverture de la mine Horne en 1927, cent-cinquante mines ont contribué à la production de 1 420 tonnes d’or de 4,1 millions de tonnes de cuivre et de 4,7 millions de tonnes de zinc. Les productions minières annuelles ont été d'importance variable: des records de production ont été établis en 1955 pour I' or avec 35 tonnes et, vers 1965, pour le cuivre, le zinc et la quantile globale de minerai extrait avec respectivement 130,000, 275 000 et 13 millions de tonnes. Deux dépressions généralisées ont eu lieu, l’une vers 1946 et l'autre, a lafin des années soixante-dix. Des ralentissements de la production ont été observes pour le cuivre en 1953 et le zinc en 1959. Depuis le debut des années quatre-vingt. I' or et, de façon plus irreguliere, le zinc sont en progression, landis que le cuivre, malgre une hausse en 1983. pour suit son dec/in.La teneur de récupération des mines d’or est demeurée régulière et n’a subi qu’une faible diminution au cours des quarante dernières années. Célie du cuivre a diminué d'environ 50% dans la même période, landis que celle du zinc a subi d’import antes variations, aussi bien positives que négatives. Près des trois quarts des mines d'or ont une durée de vie inférieure à 12 ans et la distribution des tonnages de minerai extrait montre un maximum pour la classe de 100 000 à 1 million de tonnes. Du cote des mines de métaux de base, la durée de vie est plus étalée et les volumes de minerai ont une occurrence maximale dans la classe de 1 à 10 millions de tonnes.Concernant la distribution géographique de la production minière dans l'Abitibi québécois, le camp minier de Rouyn-Noranda vient en tête pour l’extraction de minerai et la production d’or et de cuivre. L’est sui vi par le camp de Val d'Or pour le minerai et l’or, landis que le camp de Chapais-Chibougamau occupe la deuxième place pour le cuivre avec une production équivalence a 60% de celle de Rouyn-Noranda. Le camp de Cadillac-Malartic suit de tres pres celui de Val d'Or pour ce qui est de I' or. Finalement, dans le casdu zinc, le camp minier de Joutel-Matagami domine largement avec une production qui a connu un développement accélère depuis 1963. Une analyse pré liminaire de ces données indique qu' i/ subsiste unpotentiel encore élevé de production d'or, décuivre et de zinc dans I' Abitibi québécois. ABSTRACTThe Quebec portion of the Abitibi belt has essentially produced gold, copper, zinc and silver, as well as some small quantities of nickel, lead, molybdenum, bismuth, lithium, iron and asbestos. Since the opening of the Horne mine in 1927, one hundred and fifty mines have produced 1420 tons of gold, 4,1 millions tons of copper and4,7 millions tons of zinc. Annual mine production has fluctuated: production records were established in 1955 for gold with 35 tons, and around 1965 for all extracted ore copper and zinc with respectively 13 millions, 130 000 and 275 000 tons. Two main recessions have occurred, the first around 1946 and the second during the late seventies. Cut backs in copper and zinc production occurred in 1953 and1959. Since the beginning of the eighties, gold production and to a lesser extent zinc production have been in progression. Except for a small jump in 1983, copper production is still declining.The average recuperation grade of gold mines has been quite steady and has only slightly diminished in the past forty years. The average copper recuperation grade was halved during the same time interval. For zinc there have been important ups and downs. At least three quarters of gold mines have an average lifespan of 12 years the tonnage distribution shows a peak in the 100 000 to 1 million tons class. Base metals mines show a more widespread life expectancy and have a tonnage peak in the 1 to 10 millions tons range"

Jan 1, 1990

By J. K. Szymanski

"RÉSUMÉPour maintenir de bonnes performances technique et économique dans l’exploitation par chambres vides (open stope) il est primordial d’assurer un contrôle efficace des limites réelles des chantiers d’abattage. C’est pour cette raison que, de plus en plus souvent, les opérateurs miniers utilisent un dispositif de laser (Cavity Monitoring System: CMS) qui permet de mesurer les dimensions réelles de chantiers en vue de calculer principalement la dilution et les pertes du minerai ainsi que d’autres paramètres. Malheureusement, il n’existe présentement aucune méthodologie commune, qui permettrait d’interpréter ces résultats selon les mêmes critères pour faciliter d’évaluations juste et précise de la réalisation par rapport à la planification en vue d’en apporter de corrections, dans les différentes opérations minières, si nécessaire. Dans la première partie du présent article on discute les principales séquences d’exploitation utilisées dans l’extraction par chambres vides. Par la suite, à l’aide des sections transversales et longitudinales on illustre toutes les phases des travaux miniers. Ceci en vue de permettre au lecteur de comprendre mieux c’est qui peut se passer effectivement dans les chantiers d’abattage. Par après on donne les définitions générales de principaux facteurs de performance technique. Finalement, l’exemple numérique, élaboré à partir des résultats de l’arpentage au laser effectué par la mine Bousquet 2 dans un chantier d’abattage, donne les détails concernant les définitions ainsi que les valeurs de nombreux facteurs de performance technique, qui pourraient être utilisés, par après, par les opérateurs miniers dans le suivi de leurs exploitations souterraines."

Jan 1, 1997

By H. Warren Newcomen, Dennis C. Martin

"This paper describes the investigation of a large, progressive slope failure on the southeast wall of the east pit at Highmont Mine, British Columbia Geotechnical investigation s consisted of geological and structural mapping, assessment of blasthole drilling records, review of rock core information, slope movement monitoring and back analysis of various possible failure modes. Climate records and mining history were also assessed to determine their relationship to slope movement.Analysis of movement monitoring records and geotechnical information indicates that the failure is deep seated. The upper portion of the failure surf ace occurs along clay filled discontinuities. The lower portion of the failure surf ace appears to occur through the highly altered rock mass. High groundwater pressures and mining at the toe of the slope are documented to have had a major influence on stability at various times during the failure. Stability analyses results are presented and possible remedial measures are discussed.IntroductionHighmont Mine is located near Logan Lake in the Highland Valley approximately 50 km southwest of Karnloops, British Columbia (Fig. I). Mining of the porphyry copper and molydenum ore bodies began in 1980. In May, 1983, when mining in the east pit had progressed to a depth of about 60 m (200 feet) , a failure (designated the Southeast Failure) began to develop in the southeast corner of the east pit. Subsequent mining to a depth of 110m (360 feet) was accompanied by frequent and substantial slope movements involving between 500000 and I 000 000 m3 of rock . The slope was monitored extensively to assess short-term movement trends for operational safety. Geological mapping, core logging and rock mechanics testing were used in conjunction with the long-term monitoring information to determine the failure mechanism, conduct stability analyses, assess the effects of instability on pit design and enable design and installation of remedial measures."

Jan 1, 1988

By J. Budac, R. Kofluk, D. Belton, M. Sjogren

A series of tests were performed to determine the flammability limits of mixtures of oxygen, ammonia, steam and nitrogen, over a solution, in a sealed autoclave. The partial pressures of ammonia and oxygen in the vapour space were varied by adjusting the character of the solution and by adjusting the oxygen concentration in the oxidant gas respectively. The data shows that flammable conditions can be minimized by controlling the operating temperature, reducing the ammonia content in the solution, increasing the concentrations of Ni, Cu and Zn in solution and keeping the % oxygen in the gas phase less than 15.5. Observations were also made that suggest that the presence of an aerosol in the vapour space may hinder ignition.

Jan 1, 2004

By Yongjun Peng, Yufan Mu, Rolf A. Lauten

"Chalcopyrite, a major source of copper, is commonly found associated with iron sulfides, particularly pyrite. The separation of chalcopyrite and pyrite by flotation is difficult due to the galvanic interactions between pyrite and chalcopyrite during grinding and flotation. Galvanic interactions may cause oxidation and dissolution of chalcopyrite, copper activation of pyrite and the formation of hydrophilic iron hydroxide coating. The overall effect may change the floatability of the components and lead to the misplacement of pyrite into chalcopyrite concentrate. The objective of this study was to investigate the effect of lignosulfonate-based biopolymers on the depression of pyrite in the flotation of chalcopyrite with xanthate as collector and the mechanism responsible for the selective depression of pyrite. The flotation results showed that biopolymers depressed the flotation of both copper-activated pyrite and chalcopyrite in single mineral flotation although to different extents. In the flotation of mixed mineral systems, biopolymers significantly depressed pyrite flotation but had a less influence on chalcopyrite flotation. The selective depression of pyrite by biopolymers was due to the preferential adsorption of biopolymers on copper-activated pyrite surface. Galvanic interactions between pyrite and chalcopyrite surfaces promoted copper activation on pyrite. Presence of cuprous ions on pyrite surface favored biopolymer adsorption by the formation of a complex between the cuprous ions and biopolymer molecules. The same galvanic interactions also facilitated chalcopyrite oxidation leading to the formation of hydrophobic polysulfide that enhanced the hydrophobicity on chalcopyrite surface. The biopolymer structure controlled the depression effect. The results showed that the biodegradable biopolymers are promising depressants for pyrite.INTRODUCTIONCopper sulfide minerals, such as chalcopyrite (CuFeS2), bornite (Cu5FeS4), chalcocite (Cu2S) and covellite (CuS), are the major mineral source for copper. They are often found finely interlocked with iron sulfides, especially pyrite (FeS2) (Owusu, Brito e Abreu, Skinner, Addai-Mensah, & Zanin, 2014). Pyrite, as the most abundant sulfide mineral, is perceived as gangue in most cases and should be removed from the associated sulfides to minimize its contamination of the copper concentrate (Owusu, Addai-Mensah, Fornasiero, & Zanin, 2013; Wang & Forssberg, 1991). The commonly used strategy to remove pyrite is flotation (Wang & Forssberg, 1991)."

Jan 1, 2016

By M. B. McClenaghan

"Abstract - The Matheson area of northeastern Ontario is of great interest for mineral explo­ ration because of its geological similarities with the adjacent Timmins, Kirkland Lake and Larder Lake gold camps. Exploration in the area, however, is hampered by the presence of an extensive and thick cover of glacial sediments. For this reason, till geochemistry has be­ come an important exploration method. The Ontario Geological Survey&apos;s Black River -Matheson (BRiM) reconnaissance till sampling project, carried out between 1984 and 1988, was designed to aid exploration in the Matheson area by documenting the Quaternary stratigraphy and providing a database of till geochemistry. Till samples were collected by backhoe trenching of surface pits in areas of thin drift ( < 5 m) and by sonic overburden drilling in areas of thicker drift. This paper summarizes the results from the shallow till sampling component of the BRiM project.Two hundred and eighty-two surface samples were collected from Matheson Till, the youngest till sheet in the area, which was deposited during the Late Wisconsinan. For each sample, the non-magnetic heavy mineral (>3.3 S.G.) and fine (-250 mesh) till fractions were analyzed geochemically. In addition, visible gold grains were recovered by panning the heavy mineral fraction. Five areas that display multi-element anomalies in both till fractions warrant further investigation: (1) western Egan Township, overlying the Bradley Lake Syenite; (2) around and south of the Munro and Croesus mines, in Munro and Guibord townships; (3) central Garrison Township overlying the Garrison Stock; (4) south of Ore Car Lake in northern Thackeray Township; and (5) southeastern Harker Township. In these areas, Matheson Till has a local provenance and the bedrock sources for these anomalies are nearby in the up-ice (north­ northwest) direction. Due to the fine-grained nature of gold in bedrock deposits in the BRiM area, the small size of most gold grains recovered from till samples (<50 1-1m) and the variable distribution of gold in the heavy mineral concentrate and fine fractions, the fine fraction in addition to the more commonly used heavy mineral concentrate should be used for gold exploration.Surface till samples have been affected by weathering to a depth of s3 m. Weathered till is characterized by a very low carbonate content in the matrix fraction, the absence of sulfide grains in the heavy mineral concentrate and higher concentrations of copper, nickel and zinc in the fine fraction than in the heavy mineral concentrate. As a result of the weathered/ oxidized nature of the surface till samples, the fine fraction is a better sampling medium for base metal exploration."

Jan 1, 1992

By C. T. Morley

The steadily increasing interest in high pressure grinding rolls (HPGR) as a legitimate alternative comminution technology for hard rock applications has led to a proportional increase in the demand for trade-off studies comparing HPGR with more established approaches, typically SAG-based but including AG and stage-crushing designs. The primary trade-off is between a) the higher capital cost typically incurred with HPGR-based designs and b) the higher operating costs of the more traditional technologies. However, if, through circuit design innovation, the capital cost penalty of HPGR circuits could be eliminated or reversed, then the need for trade-off studies would diminish.

Jan 1, 2012

Abstract - A method to extract certain types of error variance information from paired data is presented, which constitutes an important tool for the calibration of Gy’s formula for variance predictions in the sampling of broken ores. The research summarized here complements publications by others on geochemical precision. The model and method proposed for treating duplicate data provide a practical means of deriving separate estimates of the purely analytical and aliquot sampling variances, from a unique set of duplicate assays, and, hence, proposes a new avenue for estimating effective mineral grain size.

Jan 1, 1998

By G. Gabra, M. Nagamori, J. J. Panneton

"RESUMELa calcination contrôlée de 10 serpentine permet de produire de 10 magnésie active. Le degré de I&apos;activation est mesure par 10 solubilité du magnésium dans les acides faibles tel que I&apos;acide acétique, La serpentine contenue dans les résidus d&apos;amiante du Québec peut donc être activée par calcination. Le teneur en magnésie active des rejets d&apos;amiante calcinés est fonction de divers paramètres: température, temps de calcination, granulométrie, etc. Les rejets d&apos;amiante de différentes provenances démontrent des comportements thermochimiques différents qui sont étudiés dans Ie présent travail au moyen d&apos;ATD, de TG, de la diffraction des rayons X et de la lixivation par l&apos;acide acétique. On constate qu&apos;un maximum d&apos;environ 80% de la magnésie totale peut être activé dans certains rejets d&apos;amiante du Québec et Ie degré d&apos;activation dépend de la provenance.vIntroductionOn sait depuis longtemps que la serpentine, Mg3Si2O5(OH)4, un silicate hydroxylé de magnésium, devient amorphe lorsqu&apos;elle perd de I&apos;eau d&apos;hydratation entre 600 et 700 °C. La serpentine ainsi calcinée est alors dissociée en magnésie et en silice. Cette magnésie, dite active, est soluble dans un acide faible ou même dans les solutions de sels d&apos;ammonium.Plusieurs precédés chimiques ont été proposés afin d&apos;extraire sous forme de composés magnésiens la magnésie de la serpentine. La plupart de ces procédés comportent une activation par calcination de la serpentine préalablement à une Iixiviation par un acide ou par une solution d&apos;un sel d&apos;ammonium.Malgré la contamination par Ie fer et par d&apos;autres éléments, les compositions chimiques des rejets de différentes mines d &apos;amiante du Québec, présentées au tableau 1, sont très proches de la serpentine typique. Puisque Ie degré d&apos;activation de la magnésie varie grandement d&apos;une serpentine à I&apos;autre lors de la calcination, la première étape de la recherche sur la transformation chimique des rejets d&apos;amiante du Québec se résume à une étude de leurs comportements thermochimiques."

Jan 1, 1982

By Derek E. McBride

"Exploration work in the Beardmore - Tashota area has led to a reinterpretation of relationships between gold mineralization and the geologicalevolution ofthe area. The host volcanic rocks form two parallel volcanic belts connected by a much smaller cross-cutting band, which trends northeast from Beardmore to Tashota. This connecting band consists of mafic and felsic volcanic, plus clastic sedimentary rocks in a sequence conformable with the contact of the Onaman Lake Batholith to the east. A metamorphic aureole or incorporated xenoliths are lacking along this major contact and the only intrusive relationship observed is chilling between mafic dikes and a cold host granite in proximity to it. Granite dikes are totally lacking in the volcanic succession, or the overlying sedimentary sequence. A major part of this sequence consists of a polymict basal conglomerate with granite boulders and volcanic clasts in a fine-grained chloritic matrix. The nearest source for these boulders is the Onaman Lake batholith.Gold mineralization in significant economic quantities (+ 50 000 ounces) occurs at the top or above the mafic volcanic succession as quartz bands. In the Northern Empire Mine, the band is conformable, folded, boudinaged and the mineral zoning shows a relationship to variations in the host rock, not structural overprinting. In general, where the host mafic tuff is medium-grained, the quartz band is thicker, up to a metre wide, and carries economic grade; where the tuff is finer-grained and bedded, the band is very thin and low grade.Stratigraphic control and metal zoning shows that the mineralization formed as part of the development of the volcano- sedimentary succession. The other major deposits in the area (Leitch and Sturgeon River) have a similar structural history suggesting that they are also syngenetic in terms of the stratigraphic development. Regionally, these deposits were emplaced prior to any significant tectonic deformation but at the end of the mafic volcanic event.The mafic activity was related 10 a period ofextension which caused the volcanic troughs to develop along centres of rifting. The hiatus at the end of this event permitted extensive hydrothermal systems to form and deposit siliceous exhalite bands within sedimentary or terminal mafic volcanic environments in promixity to major thermal sources. Subsequently, the Kenoran Orogeny deformed the entire succession into upright folds with a sub-vertical schistosity. Evidence shows that the deposits have remained intact since deposition."

Jan 1, 1987

By M. Lahtinen, H. Takala, B. Saxén

Oxidic zinc fume dusts are formed in electric arc furnace (EAF), Waelz furnace operations, and also in the Top Submerged Lance (TSL) furnace of Outotec Ausmelt. These dusts are normally considered as secondary raw materials for zinc metal production, as they are mainly originated from steel scrap recycling or zinc plant residue processing. The latest development in zinc fuming is direct smelting of zinc concentrates in the Ausmelt TSL furnace and hydrometallurgical treatment of produced fume dust. This technology is for primary zinc production like roasting and concentrate direct leaching, as concentrates are directly treated. The various oxidic zinc raw materials differ in composition and content of impurities. Thus, they require different hydrometallurgical processes to produce pure zinc metal. In addition to zinc these dusts typically contain also lead, silver and indium, which can be recovered and can increase recovered metal value significantly. From the impurity point of view the most relevant elements in the fume dusts are iron, arsenic, fluoride, chloride and cadmium. This paper describes hydrometallurgical processes to treat Ausmelt TSL fume dusts to extract valuable metals at high recovery and also to control and separate various impurities efficiently.

Jan 1, 2014