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By T. Grammatikopoulos, SGS Canada Inc.

"The Nechalacho rare metal deposit, located in the Northwest Territories, Canada, is currently being taken through Feasibility Study by Avalon Rare Metals Inc. QEMSCAN analysis and supplementary electron microprobe analysis were utilized to identify and quantify the mineralogy of the deposit, and determine REE distribution among the minerals. QEMSCAN mineralogy was performed to provide textural information on the mineralization, determine the variability of the ore and identify REE domains, and the liberation and association of the REE minerals. The sample matrix consists predominantly of silicate minerals. The REE minerals include allanite, monazite, synchysite, columbite, fergusonite, and bastnaesite. Zircon is present in considerable amounts and is a REE carrier. Fergusonite and zircon account for most of the HREE, and monazite, allanite, synchysite and bastnaesite the LREE. QEMSCAN mineralogical data is extremely valuable in assessing the mineralogy of the ore. The data are implemented to define the mineralogy of the ore body, support metallurgical test work, and predict recoveries and grades.INTRODUCTIONThe term rare earth elements (REE) is used to describe the 15 lanthanide elements or metals and, more recently, the metals yttrium and scandium, which display similar physical and chemical properties.Economic and potentially economic REE deposits form two main groups, a more commonly occurring “light rare earth element” (LREE) group containing lanthanum, cerium, praseodymium, neodymium, and samarium and a less commonly occurring “heavy rare earth element” (HREE) group which, in addition to the LREE, contains elevated concentrations of the more valuable REE, europium, gadolinium, terbium, dysprosium, holmium, yttrium, erbium, thulium, ytterbium, lutetium and scandium. The first group is hosted primarily by carbonatites and the second by highly alkaline (Na + K > Al) silicate igneous rocks. The LREE are produced mainly from bastnaesite, monazite, etc., while HREE are produced almost exclusively from low-grade secondary ion adsorption clay deposits in which the REE are adsorbed onto the surfaces of kaolinite and halloysite, clay minerals produced by the weathering of granite and sediments. HREE are also found in fegusonite, zircon, xenotime, etc but are not produced presently from these minerals. China is responsible for 97% of the World’s production of the REE, mainly from the giant Bayan Obo, carbonatite-related deposit and from the clay deposits mentioned above.Quantitative automated mineralogy is increasingly being applied to ore deposits. It helps users to understand and improve mineralogical parameters for geological and metallurgical purposes. Data include textural characterization, to quantification and distribution of ore and gangue minerals, liberation and association of the REE minerals. The data can be used to define mineralogical domains and predict the metallurgical response of the ore (Gunning, de Souza, & Grammatikopoulos, 2009)."

Jan 1, 2012

By J. D. Bateman

Introduction The lifting of restrictions on the development of radioactive mineral deposits by private individuals has re-opened the search for uranium in Canada to a large body of professionally trained prospectors. The entry of private capital and experienced prospecting techniques into the search for radioactive minerals has been enormously stimulated by the atomic developments of the past several years; and we can now look forward to the discovery of new productive sources of uranium. The rate of new discoveries will, how ?ever, depend on the effectiveness of the methods used. The large number of new pitchblende occurrences reported within the past several months is largely a measure of the energy with which the portable Geiger-Müller counter has been applied in the field. The counter is simply a 'radio' receiver tuned to one of the products of spontaneous atomic disintegration that is characteristic of all radioactive materials. Its effective use depends largely on how it is applied under the various geological and topographical conditions that ma y be encountered, and also on an understanding of its limitations. Extensive geological information relating to the occurrence of radioactive minerals in Canada has been accumulated during the past several years, and it is now possible to define in a general way many of the geological formations in which pitchblende and related minerals are likely to occur. Furthermore, prospecting can be localized in those parts of the favourable formations that offer the greater promise of containing commercial deposits. In this selection, the Geiger counter is the most useful tool available to the prospector for the actual detection of radioactive materials. As an example, an area of two square miles in the Northwest Territories, within which about a dozen pitchblende occurrences had been found over a several year period by conventional prospecting methods, yielded more than forty-five additional discoveries by application of the Geiger counter. Yet earlier attempts at prospecting this area with the counter had failed, due largely to faulty instruments and lack of experience in field application. The limitations of the counter are very considerable; but, when they are recognized, there is no more useful tool for the discovery of radioactive ores. It was not until 1944 that a practicable portable counter was developed, and then only by co-operation in the field by geologists and physicists. Officers of the Geological Survey of Canada working with physicists of the National Research Council brought about the development of the modern counter.

Jan 1, 1949

By M. Rylatt, E. Legault-Seguin, C. Mohns

"With energy costs increasing and ore grades diminishing, the role of preconcentration in hard-rock mining operations has gained greater interest. Dense medium separation is a process that can be conducted at particle sizes from 250 to 0.50 mm with high separation efficiency, depending on liberation characteristics of the valuable minerals. Pilot-plant case studies conducted at the SGS Lakefield site are presented, including mineral systems such as spodumene, sulfide-bearing gold ores, and complex sulfide ores. These case studies demonstrate that, for amenable ores, mass rejection of 20–60% is possible while maintaining recoveries of greater than 90%.RÉSUMÉ Au vu de la hausse des coûts liés à l’énergie et du déclin de la teneur des minerais, le rôle de la préconcentration dans les exploitations minières en roche dure présente un intérêt croissant. La séparation (ou concentration) en milieu dense est un processus pouvant être mené sur des calibres de grains de 250 à 0.50 mm avec un rendement élevé de séparation, en fonction des caractéristiques de libération des constituants des minéraux métallifères. Sont présentées dans cet article des études de cas menées dans des usines pilotes du site de Lakefield de SGS, lesquelles incluent des systèmes de minéraux tels que le spodumène, les minerais aurifères sulfurés et les minerais sulfurés complexes. Ces études de cas montrent que pour les minerais présentant les caractéristiques de libération appropriées, il est possible d’atteindre un rejet en masse de 20 à 60 %, tout en maintenant des récupérations supérieures à 90 %.INTRODUCTIONPreconcentration is the process of rejecting gangue minerals while ensuring recovery of valuable minerals prior to more intensive, downstream processing. Preconcentration has been practiced in the industry for many years, and is gaining greater interest as the industry copes with processing lower grade, more difficult ores, which typically require finer grind sizes and incur higher energy costs.The benefits of preconcentration are:• lower mining costs, which allows for nonselective mining;• lower process capital and operating costs (e.g., resulting from reduced grinding, flotation, and fines disposal stages);• increased ore reserves, which provides the potential to treat lower grade ore;• increased mine production without expansion of the existing plant or concentrator;• reduced overall tailings impoundment by converting the reject into a byproduct (e.g., underground backfill or aggregate);• improved efficiency of downstream processes (e.g., silica removal in electric arc furnace feed, removal of softer sliming minerals prior to grinding);• potential application to brownfield operations and greenfield projects; and• a “green” process option, which reduces processing energy consumption;– reduces mill feed;– increases stage metal recovery (higher grade feed);– increases mill metal output per tonne processed;– reduces surface plant, tailings dump, and tailings pond requirements because the plant has a small footprint and can be installed underground; and– can be applied to retreatment of old tailings dumps to recover metal values and reduce environmental impacts (e.g., dissolved metal runoff, acid drainage)."

Jan 1, 2017

By A. Rodriguez-Prado, P. Kuschk, R. L. Legge, W. C. Lennox

Using constructed wetlands to chemically reduce hexavalent chromium Cr(VI) to Cr(III) from industrial and mining wastewater has proven to be feasible and efficient. Applying first-order kinetics to describe the process is simple, but in some cases a more accurate model is required to reflect the process. This paper studies the feasibility of using non–first-order kinetics to describe the reduction process. Results indicate that half- and second-order kinetics adequately described Cr(VI) reduction in laboratory wetland mesocosms. The organic carbon content played a relevant role, whether it was built up by plant growth or spiked into the feed water.

Jan 1, 2014

By G. E. Norman, A. L. Mckague

"The new smelting process commenced operation in 1978. The pelletizing and sinter plants were replaced with slurry-fed roasters and the blast furnaces with electric furnaces. The existing converter aisle and matte handling facilities remained unchanged.Process DescriptionNickel-copper concentrate is partially roasted in two slurry-fed fluid bed roasters. After gas cleaning, the sulphur dioxide gas is transferred to the acid plant. The roaster product is conveyed to two electric furnaces for smelting to produce a waste slag and furnace matte. The slag goes to the disposal area and furnace matte containing the metal values is processed in the converters for further removal of iron and sulphur.The final matte containing about 75 per cent metal values is shipped to the refinery in Norway.The commercial smelter was designed for 2135 tonnes per day of concentrate, with an availability of 85% . Roasters and electric furnaces were sized at 117 per cent of design, or 1250 tonnes per day on each of two lines. Concentrate storage capacity in the plant is sufficient for two to three days' plant operation.The new smelting process will be discussed under the following headings:Concentrate Slurry HandlingFeed PreparationRoaster OperationRoaster Gas CleaningCalcine TransferElectric Furnace Operation and Process Control Converting and Matte HandlingUnder these headings, process control , equipment changes, and plant performance after three years' operation is reviewed. A brief discussion of accident prevention , and working environment is also included ."

Jan 1, 1984

By E. Goris Cervantes

"A theoretical framework based on a detailed analysis of mine operations data from an oil sands mine in northern Alberta and the static simulation of truck cycle times are developed, verified, and validated in this paper. Implementation of this framework provides better results than existing tools that rely solely on manufacturer data. This, therefore, aids in efficient equipment planning for the life of the mine. The use of this framework to modify existing productivity curve estimation methods currently in use at the mine site is also proposed. This method replaces “loaded flat haul” with “loaded effective flat haul” in the productivity estimation. Validation of the model results in a 4% overestimation of productivity, versus an underestimation of more than 10% when using the existing in-house method. ¦ KEYWORDS Equipment planning, Life-of-mine (LOM) planning, Oil sands, Productivity, Truck cycle times RÉSUMÉ Un cadre théorique fondé sur une analyse détaillée des données relatives aux activités minières d’une exploitation de sables bitumineux dans le nord de l’Alberta et la simulation statique des temps de cycle des camions sont développés, vérifiés et validés dans cet article. La mise en oeuvre de ce cadre offre de meilleurs résultats que ce que proposent les outils existants, lesquels se basent uniquement sur des données des constructeurs. Ceci contribue donc à une planification efficace de l’équipement pour des projets relatifs à la durée de vie de la mine. On propose également de se servir de ce cadre pour modifier les méthodes d’estimation de la courbe de productivité actuellement utilisées sur le site minier. Cette méthode remplace le concept de loaded flat haul (la distance parcourue par des camions avec un chargement du point de collecte jusqu’au point de déchargement des résidus miniers) par celui d’effective loaded flat haul (la distance relative parcourue par des camions avec un chargement du point de collecte jusqu’au point de déchargement des résidus miniers) dans l’estimation de la production. La validation du modèle résulte en une surestimation de 4 % de la productivité, par rapport à une sous-estimation de plus de 10 % avec la méthode actuellement utilisée en interne. ¦ MOTS CLÉS planification de la durée de vie de la mine, planification de l’équipement, productivité, sables bitumineux, temps de cycle d’un camionINTRODUCTION One aspect that differentiates oil sands mines in northern Alberta from conventional hard-rock mining is the environment in which they operate. Due to ground characteristics, producers in the region experience roads with very high rolling resistance (RR) that, in turn, negatively affect haul-truck performance and greatly increase fuel consumption and emissions. Oil sands mining companies use some of the largest haul trucks in the world. In addition, oil sands mines cover more extensive areas than hard-rock pits, resulting in longer haul distances on roads made of comparatively more viscous material."

Jan 1, 2019

By F. C. Robles Hernandez

This paper presents the results of the electromagnetic semi-solid treatment of the 319 aluminum foundry alloy, Various levels of structure modification were achieved controlling the AC current used to create the Electromagnetic Field, thus manipulating the intensity of the field, The level of grain refinement, partial modification of the Al-Si eutectic, as well as cellular dendrites were observed, A quantitative analysis of the structure was performed using Image Analysis (IA) techniques. In addition a novel Thermal Analysis methodology was developed for the on-line determination of the microstructure modification level.

Jan 1, 2004

By D. Yuan, M. Sitter, S. St. Jean, M. Collins

The Ambatovy Joint Venture comprises an operating lateritic nickel mine, ore slurry pipeline, pressure acid leach plant and nickel refinery in Madagascar. The hydrometallurgical process selected by Sherritt for treatment of the Ambatovy ore is a long-term, sustainable approach to producing nickel. Sulphur, used to prepare hydrogen sulphide, which is used to produce mixed sulphide intermediate, is recovered in the refinery as ammonium sulphate fertilizer. Additional sulphur is used to generate sulphuric acid for treatment of the ore in the high pressure acid leach (HPAL) step; fossil fuel consumption is minimized by using the heat generated from the exothermic reaction between sulphur and oxygen in the acid plant to produce power and steam. Steam consumption is minimized by design of efficient flashing and preheat systems for HPAL, while the high temperature of the HPAL step serves to minimize acid consumption. Fossil fuel consumption by the operation as a whole is further minimized by locating the leach plant and refinery near the port of Toamasina and utilizing a 220 km slurry pipeline to transport ore from the mine to the leach plant. In addition, Ambatovy has demonstrated a strong commitment to sustainability programs such as the biodiversity management program at the mine and local procurement in Madagascar. In this paper, the hydrometallurgical process for nickel and cobalt recovery from Ambatovy ore is described, along with highlights of Ambatovy’s approach to sustainability in Madagascar.

Jan 1, 2015

The theory and practice of sampling of particulate material have been the focus of a continued attention on the part of the mining industry worldwide for almost a century now, because of its critical importance at all phases of a mining project, from exploration (bulk sampling, assaying) to production (grade control) and marketing (quality control). A powerful, complete theory was put together by P. Oy (1968 to i982), but its applications to gold ores have met with limited success to date, due to the inadequacy of its sampling variance and minimum sample mass determination formulae to the challenging case of gold ores. This paper presents a research project completed at Inco Exploration and Technical Services Inc., using a geostatistical approach, to shed light on the results of P.Gy's theory, and adapt them to the case of particulate gold ores. After a reminder of Gy's formulae and a simplified demonstration of the generic form of Gy's and more traditional formulae, an empirical approach, based on sampling experiments from four gold deposits, shows how Gy's formulae must be corrected to adjust to the case of gold ores. The generality of the results formula is then substantiated with a geostatistical analysis of the problem. A parameterized formula results, and indications are given on how to fit its parameters to experimental data. Application guidelines and charts to fit any case and budget are presented, along with a detailed practical example.

Jan 1, 1991

Orebodies of the Renison Bell - Mt. Bischoff tinfield in Tasmania are stratabound, conformable lenses of massive cassiterite-bearing pyrrhotite, with underlying discordant, fault-fracture-controlled and more siliceous ore. The deposits occur in eugeosynclinal, trough-deposited sedimentary and mafic volcanic rocks which are stratigraphically equivalent to diff erentiated volcanic rocks that contain volcanogenic massive base metal sulphide deposits in a parallel arc to the east. Textures of the massive pyrrhotite ore suggest that it has undergone metamorphic recrystallization. Although the massive ore contains both monoclinic and hexagonal pyrrhotite, a study of a few samples from one orebody suggests that their distribution is stratigraphically controlled, with the monoclinic variety abundant only at the base. The distribution pattern of rare-earth elements in massive ore is similar to that of volcanogenic massive base metal sulphides in New Brunswick, and suggests that mixing of sea water with exhalative hydrothermal brines occurred during ore deposition. Tin is a common accessory element in many volcanogenic massive base metal sulphide deposits providing strong evidence that it, too, is transported and deposited by volcanic affiliated hydrothermal brines. Sedimentary rocks containing the massive orebodies are fine grained, thinly laminated, compositionally banded and of mixed chemical sedimentary-tuffaceous origin. They include finely recrystallized chert, carbonate-rich and pyritic varieties; and soft sediment deformation structures in these rocks suggest that dense sulphides deformed underlying, less dense chert prior to lithification. Close to ore the chert becomes massive and coarsely recrystallized, as does the carbonate, which is here strongly enriched in Fe and Mn. Apatite is present in pyritic, cherty and carbonate-rich beds and in the ore itself, in all of which it shows a similar pattern of rare-earth element distribution, suggesting that it is of marine sedimentary origin. These deposits have traditionally been considered as epigenetic replacements of favourable carbonate horizons by hydro thermal flu ids derived from later Devonian porphyritic intrusions. Some of these intrusions have associated tinbearing greisens. The above relationships suggest, alternatively, that, like massive base metal sulphides, the tin deposits were of original syn-sedimentary origin. Circulating hydrothermal brines generated during early Cambrian eugeosynclinal subsidence and tectonism rose through steep fault-fractures, there giving rise to the discordant orebodies, and were discharged on the sea floor, where the massive pyrrhotite lenses were precipitated with the associated cherts and carbonates. In some places, Devonian intrusions remobilized the earlier deposits, forming greisens and newepigenetic veins. Finally , the geologic selling of these deposits, in trough deposited sedimentary and mafic volcanic rocks, suggests another favourable environment for massive sulphide exploration which is quite different from the domal felsic volcanic environment so heavily favoured currently in North America

Jan 1, 1979

By A. Grimod

Rockfall drapery systems are commonly used as a simple, fast and cheap measure against the rock falling trajectories affecting very steep slopes. The system basically consists of a steel mesh, which is held on the top edge with a longitudinal cable fixed by means of a suitable number of anchors. The effect of this kind of intervention is to control the falls of the rocks, which are driven toward the bottom with slow velocity, or are stabilized on place. It can be used on any kind of slope to protect sensitive target in the mining industry, roads and railways, and inhabited areas. The falling blocks, typically smaller than 0.6 - 1.0 m in diameter, pile up into a trench (or into a ?pocket of mesh?) at the bottom. In comparison to other types of rockfall interventions, the simple drapery is cheaper, and its maintenance is easier, but on the other hand it cannot be considered the remedy for shallow instabilities, because it can only mitigate the effect of the falling trajectories. The design of simple draperies requires the analysis of several factors like the slope features (height, gradient, morphology), the geological and dynamic features (nature of the ground or rock, type of instability, erosion problem, blocks size), the environmental condition (presence of vegetation, aesthetical problem), the installation problem (accesses to the slope, safety for the workers, safety for the surrounding areas) and finally the performance required (temporary or permanent intervention, required maintenance, cost). Finally the most problematic design-step is the choice of the suitable mesh, the top longitudinal cable, and the top anchors type. Because of the highly variable nature of rockfall behaviour these structures cannot be standardized, but they have to be analyzed and designed for each case. Maccaferri has developed a new software application (MacRO 2) has a practical tool to define the mesh and the related supporting structure composed by up-slope cable and anchors. The software, based on the approach proposed by Muhunthan B. et al. (2005), allows designers to verify the top longitudinal cable, the anchors, and the mesh drapery, and to plan for maintenance procedures. Even if the method seems quite simple and rough, it is effective and lets the designer correctly foresee the materials and the geometrical features to be used on the interventions. This paper analyses the condition for the simple drapery installation, the main steps for the calculations, and it will present a case study in a U.S. mine. Nevertheless, even if the software allows a quick and simple calculation approach, onsite observations are always recommended in order to achieve a good design, with the ultimate goal of protecting property and human lives.

Aug 1, 2013

By S. Vongpaisal, T. R. Yu

"A set of new blast damage criteria has been developed, with special reference to blasthole mining operations, for assessing damage by incorporating the vibration level, rock properties, site characteristics and the effects of ground support systems. The main objective of this work was to provide a database with reasonable accuracy for use in optimizing blast design, numerical analysis and ground control expert system module development.The new damage criteria allow one to estimate the degree of damage to rock structures in terms of a dimensionless parameter defined as Blast Damage Index (BDI). This allows for the description of blast damage in a unified form, and facilitates the development of codes for numerical modelling to express the degree of blast damage universally. A number of field investigations from several stope production and slot opening blasts at a large underground base metal mine were carried out to verify the developed index. The results show a good correlation between the observed damage and the type of damage predicted from the BDI values.Practical measures are also provided for minimizing blast damage in large underground blasthole mining operations"

Jan 1, 1996

By George P. Demopoulos

For more than 20 years the author had the privilege of working closely on a number of R&D projects with Lucy Rosato and her team at CEZinc. Several of these projects were driven from the sustainability agenda that Lucy Rosato championed as an innovation leader that supported research collaborations. Highlights from this highly rewarding collaboration are to be presented in this paper. In particular we will deal with the following works-topics: (a) iron control via solvent extraction as alternative to jarosite precipitation; (b) production of high-density gypsum by controlled neutralization of simulated zinc plant process/waste waters; (c) selenium removal from weak acid solutions; (d) electrolyte purification by cementation; and (e) manganese control by oxidative precipitation with SO2/O2.

Jan 1, 2015

"Accelerated expansion of Western Canada's metallurgical coal industry has again stimulated considerable exploration activity in the Rocky Mountain Foothills Belt and influenced much of the R&D related to transportation, processing and carbonization. Preparation R&D has included further pilot-plant work on desulphurization, spherical agglomeration and modified compound cyclones (which are also proving themselves in other mineral beneficiation studies). Combustion research, aside from increasingly stressing control of combustion source pollution, has directed special attention to lignite PF firing and problems arising from lignite ash. Studies directed toward the non-fuel utilization of coal have centered on such diverse topics as active carbons, carbonaceous filter media, plant nutrients and industrial applications of humic acid derivatives. In addition, a number of long-range research projects related to such matters as coal chemistry and pyrolysis have been actively pursued, and further attention has been given to improved sampling techniques and analytical methods."

Jan 1, 1969

By V. C. Pandolfelli, L. Paulino, C. E. Zangiacomi

The continuous improvement in aluminum industry over the last years has increased metal output at lower cost. The potlining plays an important role in this regard due to high cost involved and more recently in its environmental aspects. In order to increase potlife and thus minimize the aluminum cash cost, a systemic approach is needed, through investigating the main cathode failure mechanisms by using a pot autopsy as a powerful tool, and then making the necessary chances to achieve extended potlife. In addition, preheating and pot start-up may also damage the cathode if not performed with an appropriate technique or even if the lining materials are not specified correctly, among other factors. All these aspects will be presented and discussed in this paper. Increased potlife, especially now that the current is reaching values up to 300kA, will allow aluminum plants to match their goals more efficiently at lower costs.

Jan 1, 2006

By C. A. Jeffrey, K. Pearson

Abstract - The Croft diorite in central England belongs to a suite of Caledonian igneous rocks collectively known as the South Leicestershire diorite complex. Although the intrusions occupy separate outcrops, they are linked at depth to form a single pluton, buried beneath a cover of Triassic sediments (Le Bas, 1972; 1982, Allsop and Arthur, 1983). Both the Caledonian diorites and the overlying sub-Triassic unconformity have been affected by a complex history of alteration and mineralization which can be subdivided into four stages: (1) deuteric effects, caused by the release of volatiles during magmatic cooling; (2) albitization through sodic enrichment; (3) formation of lowtemperature laumontite, analcime and calcite veins with associated wall-rock alteration to prehnite and pumpellyite; and (4) sub-Triassic unconformity-hosted base metal, manganese and palygorskite mineralization. Zeolite mineralization occured some 200 Ma later than the intrusion itself, during post-Triassic times, as indicated by the presence of a single vein of laumontite and microcrystalline calcite which cross-cuts the sub-Triassic unconformity surface and enters the overlying Triassic sediments. Evidence from fluid inclusion work indicates that two fluids were involved in the deposition of the zeolite veins. One fluid was initially of relatively high temperature (~100°C to 320°C) and low salinity (~0.2 to 5.9 wt% NaCl equiv.), and was probably meteoric in origin, whereas the other was of relatively low temperature (~41°C to 165°C) and high salinity (~0.4 to 16.72 wt% NaCl equiv.), and is interpreted to represent a basinal brine. During Triassic rifting, thinning and fracturing of the crust, with the possible rise of associated magmas (Halliday and Mitchell, 1984), could have increased permeability and heat flow, initiating the circulation of hydrothermal fluids. Triassic unconformity-hosted base-metal mineralization in Central England is similar to other Triassic-Jurassic mineralization in Europe (Mitchell and Halliday, 1976).

Jan 1, 1997

By C. A. Jeffrey, K. Pearson

The Croft diorite in central England belongs to a suite of Caledonian igneous rocks collectively known as the South Leicestershire diorite complex. Although the intrusions occupy separate outcrops, they are linked at depth to form a single pluton, buried beneath a cover of Triassic sediments (Le Bas, 1972; 1982, Allsop and Arthur, 1983). Both the Caledonian diorites and the over-lying sub-Triassic unconformity have been affected by a complex history of alteration and mineralization which can be subdivided into four stages: (1) deuteric effects, caused by the release ofvolatiles during magmatic cooling; (2) albitization through sodic enrichment; (3) formation of low-temperature laumontite, analcime and calcite veins with associated wall-rock alteration to prehniteand pumpellyite; and (4) sub-Triassic unconformity-hosted base metal, manganese and palygorskite mineralization. Zeolite mineralization occured some 200 Ma later than the intrusion itself, duringpost-Triassic times, as indicated by the presence of a single vein of laumontite and microcrystallinecalcite which cross-cuts the sub-Triassic unconformity surface and enters the overlying Triassic sediments. Evidence from ?uid inclusion work indicates that two ?uids were involved in the deposition of the zeolite veins. One ?uid was initially of relatively high temperature (~100°C to 320°C) and lowsalinity (~0.2 to 5.9 wt% NaCl equiv.), and was probably meteoric in origin, whereas the other wasof relatively low temperature (~41°C to 165°C) and high salinity (~0.4 to 16.72 wt% NaCl equiv.),and is interpreted to represent a basinal brine. During Triassic rifting, thinning and fracturing of the crust, with the possible rise of associated magmas (Halliday and Mitchell, 1984), could have increased permeability and heat ?ow, initiating the circulation of hydrothermal ?uids. Triassic unconformity-hosted base-metal mineralization in Central England is similar to other Triassic-Juras-sic mineralization in Europe (Mitchell and Halliday, 1976).

Jan 1, 1997

By Peter M. Watt

The objective s of this paper are: (a ) to examine and discuss the burdens we place on our extractive industry; (b) to compare the levels of taxation in Canada with those in other countries; and ( c) to suggest certain broad parameters within which our taxation policies may be made more rational and stable. Among the burdens identified are taxation, the ownership and use of our resources, environmental issues and the rather emotional issue of so-called 'super profits'. Finally, the paper will address certain broad but key areas of policy which need attention and agreement if our tax system is to be made more rational. Such areas include: whether and if so why the extractive industry should be given incentives;. what circumstances, if any, justify a 'higher' than normal' level of taxation, and, ?if the concept of economic rents is a justifiable one, how might a basis for them be established which recognizes the fluctuating value of much of the industry's output. Note: The paper was written before the 1977 Federal and Provincial budgets were presented. Consequently, the paper does not reflect any changes proposed in these budgets.

Jan 1, 1977

By Charles Camsell

At the last annual meeting of this Institute the programme very properly was drawn up and carried out with the special object of calling attention to the Dominion's position and problems with regard to fuel supplies. That subject, always one of serious concern, was a source of considerable anxiety twelve months ago. It is still so, but in a decidedly less degree than at that time. So far as the immediate fuel situation is concerned our anxieties have been relieved. And I think we can safely say that such a consciousness of our difficulties and determination to overcome them, has been developed in the minds of our people that there will be no slackening of the offensive until a final solution is reached. In selecting a subject of major importance for the present occasion I have felt free to digress from the pressing problems of last year and to go back, for a starting point, to the presidential address of two years ago .. I do not, however, wish to enter the controversy that has developed as a result of that address, though in spite of my own failure to amass a fortune from participation in certain mining ventures, I am decidedly inclined to the optimistic view that Dr. Corless presented of the future of our mining industry. You will perhaps have observed that in its general wording the title of my paper bears a marked resemblance to that of that address. This simila1ity of titles is not accidental. It is intentional on my part.

Jan 1, 1924

By F. H. Edmunds

I N presenting this paper, the writer wishes to point out some of the difficulties and problems of geological work in that part of Saskatchewan in which outcrops are few. These problems are well known to all geologists who have made investigations in this region, but may not be so well known to those outside. A table of the strata as known in certain areas of Saskatchewan and the adjacent provinces is given, with a brief discussion of some of the formations and beds about which there is little knowledge due to their being deeply buried and not exposed in the region. Comment with regard to possible oil and gas structures is made and some features of the structures in the Battleford and Simpson districts are described. The writer wishes to make acknowledgment to members of the Geological Survey of Canada to whose work in Saskatchewan and the adjacent provinces reference is made, and to others who have made, or are making, valuable contributions to the stratigraphy of Saskatchewan. Mr. G. C. Webb has kindly furnished information regarding and materials taken from a well bored recently in the Paynton district. Special thanks are due to the Simpson Oil and Gas Company for permission to use much valuable information with regard to their wells and for the generous way in which the officials and staff co-operated with the writer. The opportunities the writer has had to visit many parts of the Province have been in connection with investigations for the Provincial Department of Natural Resources and through facilities provided by the Department of Soils of the University of Saskatchewan. To these Departments the writer accords his thanks. For the purposes of this discussion, Central Saskatchewan may be considered as that portion of the Province extending from Township 16, with Regina, Moose Jaw, and Swift Current situated on or near the southern boundary, to Township 48, with Prince Albert and Lloydminster on the northern boundary. This region includes territory underlain by Cretaceous sediments and excludes the southern portion of the Province, where Tertiary beds underlie the surface and are exposed to an extent sufficient to permit a measure of systematic mapping.

Jan 1, 1937