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By MacKenzie Dickson

"INTRODUCTIONGold is found in many natural states, native nuggets, loose grain in river sands, veins in rock, as well as associated with sulphides, oxides, etc., disseminated more or less minutely.Its high value in recent years has spawned new technologies to win values from sources once considered too lean for commercial recovery. Cyanide leaching from fine milled ore or tailings, from upstream recovery operations, coupled with adsorption onto relatively coarse granules of activated carbon, concentrate the gold enough to be converted to bullion by time-honoured methods.The carbon granules are fragile. Size degradation in handling must be minimized not only to prevent loss of gold on fine fragments of carbon that could pass with the barren tailings, but to maintain adsorption efficiency. Besides, the granulated carbon itself is costly. Circular Vibroscreens are winning acceptance for dewatering carbon granules thanks to their gentle yet effective performance in gold recovery systems around the world. The system at Equity Silver is illustrative.BackgroundEquity Silver Mines Ltd., Houston, British Columbia, first began production in September 1980. In 1984, a feasibility study showed that additional gold and silver could be economically recovered through cyanide leaching of the flotation tailing.Although the carbon-in-pulp (ClP) or carbon-in-leach (CIL) process is commonly used for extracting precious metals from slurries, the use of circular vibrating screens, and Vibroscreens in particular, for the carbon circuit is an innovation that cuts costs.Rectangular vibrating screens have been the conventional separation mechanism of choice across North America. In contrast, the use of Vibroscreens has been proven to be less costly for the initial purchase and installation. Also, these circular vibrating screens require less power and less space. A description of Equity Silver Mines' process shows how these screens have been successfully integrated into the system."

Jan 1, 1989

By Lloyd A. Clark

"The kuroko deposits, which are extremely variable in size, comprise both stratiform layers of clastic sulphide particles and cross-cutting vein and disseminated components. The ores lie on the flanks of rhyolitic lava domes which have risen from a postulated subvolcanic magma chamber that provided cupriferous hydrothermal solutions and also acted as a heat source driving ground-water convecting cells. The polymetallic sulphides precipitated initially in explosion craters, pipe fillings and feeder veins as rising hydrothermal solutions mixed with sea water. As sulphides clogged the plumbing system, minor phreatomagmatic explosions produced layers of sulphide fragments on the adjacent sea floor. One to ten repetitions of this process produced multiple fragmental sulphide beds. Each deposit formed in a relatively short space of time, because only minor tuff beds are intercalated in spite of active volcanicity in the region. In this model, the heated ground waters convecting through thick piles of acidic pyroclastic rocks leach the zinc, lead and barium later deposited as kuroko ores. As the subvolcanic pluton cools, the supply of silica and copper wanes and the minor counter-circulation cells above the pluton are replaced by main cell fluids bearing zinc, etc. This change in solution flow is abrupt rather than gradual, as the plumbing system is somewhat disrupted by the magmatophreatic explosions that create each ore layer.IntroductionKnowledge of the kuroko deposits ha s greatly expanded during the 25 years since modern recognition of their volcanogenic origin. However, one aspect of the ore s, which may be of unique importance in their genesis, has received little attention. That is the fragmental character of much o f the sulphide ore, which was briefly referred to in a previous publication (Clark, 1971) and is examined in more detail by Barton (1978). Most researcher s have concentrated their attention on or e deposition above and beyond the vent, which is inconsistent with the geology."

Jan 1, 1983

By Robert D. Brown

The federal government kicked off the new budget season in November 1978, when Finance Minister Chretien announced a handful of proposed amendments to provisions of the federal Income Tax Act and Regulations affecting mining. (See Tax Notes in the January 1979 issue of the CIM Bulletin.) Declaring in his budget speech that these changes were in response to the report of the joint federal/provincial task force on resource taxation, Mr. Chretien tossed the ball to the provinces-" I want to take the lead here... I feel confident that the provinces will do their part". Quebec and Ontario, picking up the ball in their spring budgets, have announced favourable modifications to the provincial taxes on mining, with these moves being paralleled in the recent Manitoba budget, which proposes a flatrate mining tax to replace the previous controversial two-tier royalty. In the meantime, the federal government passed a host of amendments to the federal earned depletion regulations. The result is yet another batch of complex tax changes for the industry to note and digest, but this time with the hopeful factor that most of the changes are favourable to the industry. This article reviews the current status of the federal budget changes, comments on the Ontario, Quebec and Manitoba proposals, and reports on the changes to the earned depletion regulations that were passed by Order-in Council in March 1979.

Jan 1, 1979

By C. Caballero, A. Warczok, K. Itagaki, A. Moyano, J. Font

The Codelco Norte Smelter process 2,500 tpd of arsenic-bearing concentrates with an arsenic content of up to 1.5% in one of its two main smelting units, the Teniente Converter. The product, 1,100 tpd high-grade matte or white metal, is traditionally fed to the PS converters, while the 1,700 tpd of slag is fed to the slag cleaning electric furnace for copper recovery. This is achieved in a very reductive environment which reduces the viscosity of the slag and enhances the sedimentation of the high-grade matte droplets. The behavior of arsenic in this non-oxidative environment was studied at lab-scale and fundamental thermodynamic data were obtained. Based on these data a thermodynamicbase model to assess the arsenic behavior in reductive environment was developed. It is based on a mass balance for the reduction and sedimentation stages performed in an electric furnace which allows the recovery of high-grade matte droplets after decreasing the viscosity of the slag. This model can be a very suitable tool for predicting fractional distribution of arsenic in the slag cleaning electric furnace, when the distribution ratio, vapor saturation degree, temperature, y As and pO2 are given.

Jan 1, 2007

By S. Zador

"IntroductionIn the past decade, metallurgical and mining companies have shown an increased interest in the licensing of technology. When licensing technology, it is usually to the benefit of the parties, to have at least some of the technology to be licensed protected by a patent.This paper is intended to bridge the gap between the engineer in the field of mining, metallurgy and mineral processing who is interested in exploiting an invention commercially, and the patent agent or intellectual property lawyer whom he/she might retain to prepare a patent application and then prosecute the application to obtain a granted patent. It is also intended to encourage the inventor or a small business concern to consider the value of patents in the sale and licensing of technology. The lawyer may subsequently advise and assist the inventor in licensing his/her invention.A brief outline of some of the basic features of the patent system follows. The nature of the information, which the patent professional requires from the inventor to enable him/her to draft a patent application, will also be considered in general terms. Furthermore, various types of licenses which may be drawn up between a licensor of specific technical information and a licensee, will be listed and briefly discussed. No attempt, however, will be made to give a comprehensive and detailed account of the above aspects; the interested reader should consult legal publication and reference books, and patent professionals for further specific information.A granted patent is a document which describes an invention and how to practise it. The claims of the granted patent, figuratively speaking, fence off the intellectual property the inventor regards as his invention. The Commissioner of Patents, representing the Government, grants to the inventor or his assignee the exclusive right of making, constructing and using the invention, and selling it to others to be used, for a limited period of time, in exchange for disclosing the invention to the public. Thus, a patent prevents others from practising the claimed invention but it does not, necessarily, bestow the right to the patentee to practise his own invention. The term of a patent now in Canada and in most of the developed countries of the world, is 20 years from the date of filing the patent application. In the United States the patent term is still 17 years from the date of issuance of the patent. In Canada, the term was changed to 20 years in the new Canadian Patent Act which came into force on October 2, 1989. Any patent application filed prior to that date or granted before it, retains a 17 year life, commencing at the time of grant."

Jan 1, 1991

By C. Gravel, A. Fathi, P. Rivard, G. Ballivy, Z. Moradian, M. Quirion

Numerous schemes have been proposed in the past to evaluate the shear strength of rock discontinuities based on in situ and laboratory testing. Due to scale effects, in situ testing is the most reliable way to assess the shear strength parameters. However, practical reasons often impede this kind of testing. This is unfortunate because advances in theoretical rock mechanics are still dependant on qualitative experimental works. This paper presents a mobile high capacity shear apparatus developed for in situ direct shear testing of discontinuities along with testing methodology. The apparatus has the advantage of being simple, although of high capacity, and can be moved to different site locations for other tests. The in situ test was performed on a natural rock outcrop of schist with subvertical schistosity. A concrete block 50 x 50 cm with a base layer of high strength mortar was cast on the rock surface. Prior to the test, the concrete block was lifted and repositioned to have an unbonded joint but with interlocking asperities. The shear load was applied perpendicularly to the schistosity direction. The test was conducted in a constant normal load (CNL) condition. Both normal and shear loads were applied manually. The instrumentation consisted of two load cells for shear and normal loading, eight displacement laser extensometers for shear, normal, and lateral displacements and fourteen acoustic emission sensors for monitoring evolution of asperities’ degradation during the test. The friction angle obtained is 72° for the peak and 58° for the residual. The high values of friction angle indicates that first-order roughness and good interlocking of the joint surfaces can result in high shear strength parameter values in a rock generally regarded to have low values.

Jan 1, 2015

By J. R. Meyer, P. L. Dean

"The Department of Mines and Energy is at present investigating the dimension-stone potential of the Nain anorthosite complex. These rocks are known to host occurrences of labradorite, a semiprecious gemstone known for its beautiful play of colours (chatoyance). Test blocks that contain 5% to 18% chatoyant labradorite were extracted from three prospects south of Nain. These have been slabbed and polished for further evaluation.Second-grade labradorite stockpiled around the Grenfell quarry on Tabor Island is also being evaluated as a potential source of aggregate for use in terrazzo tiles, precast concrete and epoxy-backed wall panels.IntroductionThe Nain anorthosite complex consists of approximately 10000 km2 of anorthosite and related basic rocks , which are well exposed along the coast of Northern Labrador (Fig. 1) (Emslie et al., 1972). These rocks have been known for centuries to host deposits of gem-quality labradorite. The chatoyant nature (i.e. the play of colours or labradorescence) of this semiprecious feldspar has been utilized mostly in the making of jewelry and other polished, handcrafted products. In the early sixties, Brinex Limited (now Brinco Limited) attempted larger scale commercial exploitation of labradorite, including use 'as building stone and in polished precast concrete for facings on buildings' (Brummer, 1984). After six years of work, which included market studies, Brinex decided that, at that time, the demand did not warrant further production.In recent years, there has been a dramatic increase in the markets for dimension-stone. In the period from 1980 to 1985, the demand in the United States for granite, much of which is imported, has increased 1735070 (Marble Institute of America, 1986). The dimension-stone industry's remarkable growth rate has, in part, resulted from new technology that makes it easier and faster to quarry and cut stone. This has allowed natural storie to compete with other building materials. Now, it is not only used for exterior cladding and walkways, but also on interior walls and floors, and in home and office furnishings, such as countertops for kitchens and bathrooms, table and desk tops, stairways, window sills, and fireplaces."

Jan 1, 1988

By H. K. Olsen, B. Thomassen, H. K. Schønwandt, L. Grahl-Madsen, H. Stendal

Abstract-The central part of the early Proterozoic Ketilidian orogen in South Greenland consists of an I-type granitoid batholith transected by four regional NE-SW-trending shear zones. The batholith was probably emplaced during subduction, from the south toward the Archaean craton in the north, in a sinistral transpressional system. A regional sediment sampling program covering 5000 km2 shows a close connection between a gold-mineralized trend and one of the major shear zones within the epizonal facies of the batholith. The gold mineralization is not directly related to the major shear zones, but occurs in quartz-veined and silicified second-order structures. High-grade (up to 114 ppm Au over 6 m) low-tonnage mineralization is found within these second-order structures cutting both amphibolites and granitoids. The mineralization is characterized by negligible or small alteration halos. Gold is associated with various element combinations of enhanced As-Bi-W- Cu, which indicate that the mineralization is mesothermal in origin.

Jan 1, 1995

By E. Larsen

Marine tailings disposal may in some cases be the best solution to one of mining’s major environmental problems. The public standing of this solution is poor, partly because of past bad practices. Among the tailings problems spreading of super-fines and toxic substances stand out. The two are often interrelated as heavy metals, insoluble to sea water, tend to adsorb on fines and spread piggyback on them. Only one paper seen, has addressed the mineralogy of fine particles in suspension. The topic was a secondary tailings deposit. Studies on the sedimentation of fines in large river estuaries show that different minerals sediment sequentially as the salinity of the river increase. Mineralogy in the particle size range where particle separation takes place, has so far, naturally been in focus for the mineral processors. Next to nothing is known about the fines which may cause environmental problems. Tailings disposal has, due to its complexity, to a large extent been taken over by specialists in other fields, biologists, engineering geologists, chemists. The basics of the subject ought also to be given more input by the mineral processing community. A drawn out battle about tailings discharge into some fjords has taken place in Norway. The detractors focus at fine particles (could be dangerous nanoparticles) spreading and emphasize the effects. Calculation is simple: 5 million tonnes tailings annually discharged, containing 1 wt. % < 1µm determined by laser diffraction, results in 50 000 tonnes of nanoparticles let loose in the environment. The industry`s difficulty to answer, is lack of basic research on this topic. Test work to develop a methodology to address the problem is described. One thing the mineral processors know is that final tailings may be comprised of tailings from separate separation processes, with different properties, some of which may require special treatment. One tailings stream from a Norwegian mine is investigated in such a context.

Jan 1, 2016

By Charles G. Kemsley

IN view of the truly remarkable development of special steels for special purposes, the mining industry has for years looked forward to a time when steel makers would come forward with a product which would be an improvement over the straight carbon steel which has always held the field for drilling rock. In order to avoid making changes in conventional shop practice, the industry has perhaps been too insistent upon obtaining a water hardening steel which could be handled in the blacksmith shop by long established methods. As early as 1932 or 1933, an oil-hardening tool-steel of the one per cent carbon, plus chrome, plus molybdenum type was applied to hollow drill steel. It was known as a hard as well as a tough steel, and one that, theoretically, should give a good account of itself as a rock drill, if properly heat-treated; and so it has proved in actual trials. There were numerous deterrents which retarded adoption of this steel. For several years there has been a constant improvement in the drilling qualities of the straight carbon steel, and, considering the higher unit price ? of the alloy, there has been considerable doubt in the minds of some mining? men as to what advantage there might be in the use of alloy over straight carbon for hollow drill steel. The alloy being an oil-hardening steel, its adoption meant having two kinds of steel in the mine, for a time, and that spelled trouble, unless some positive means of identification was adopted. The hardening and forging ranges of alloy steel being narrow also made necessary much closer control over these operations if poor results were to be avoided. These thoughts undoubtedly prevented its use becoming wide-spread, for, as a matter of actual record, less than fifteen per cent of all the hollow drill steel used in Canada today is alloy.

Jan 1, 1942

By Wenbin Zhang, George W. Poling

"Prior or simultaneous addition of ammonium sulphate can, not only enhance the activating effect of hydrosulphide ions on xanthate flotation of malachite but it can also eliminate possible detrimental or depressing effects of excess residual hydrosulphide . Use of relatively inexpensive ammonium sulphate appears to reduce the consumption of the much more expensive sulphidizing agent for optimal flotation recovery INTRODUCTIONOxidized copper minerals float poorly with conventional thiol-type collectors. This is believed to be due to the nonadherent character of the collector coating, which is readily re- moved by particle abrasion. Rosas and Polingr reported emulsion flotation seemed capable of resisting abrasion during the flotation of non-sulphide copper ores. It appears that the most common flotation technique for oxidized copper minerals comprises sulphidization with Na .S and subsequent treatment by sulphydryl collector. The principles of this method are available . Malghan recently reviewed the studies on the role of sodium sulphide in the flotation of oxidized copper, lead and zinc minerals.It is well known that in the sulphidized flotation of malachite, the activation process depends strongly on the concentration of the sulphidizing agent, i.e., insufficient sulphide gives poor recoveries because of inadequate sulphidization; excessive sulphide also causes poor recoveries due to the depressive effect of the residual hydro-sulphide ions in solution. A major difficulty in sulphidization, especially with a varying feed nature, is to establish and maintain the optimum sulphide concentration in solution. In plant practice, vigorous control of sodium sulphide is required and stepwise addition of the reagent is recommended to improve the efficiency of the process. Soto and Laskowskim have found that malachite, depressed by an excess of sulphide ions, can restore its floatability if air or oxygen is introduced to the pulp. They attributed this to the oxidation of the HS - ions on the surface of the mineral. Jones and Woodcockuvi showed that a sulphide ion selective electrode could be used to optimize the conditions (e.g . amount of hydrosulphide, sulphidization time, flotation time) more readily and precisely than existing methods in the flotation of oxidized copper ores."

Jan 1, 1989

By R. Ricketts, D. G. Vanderveer, F. Kirby

"A program of mapping, sampling and testing to determine the potential of the aggregate resources throughout Newfoundland and Labrador was commenced in 1978. A 6-km-wide corridor parallel to all transportation routes was selected as the study area.The study consisted of a preliminary surficial interpretation followed by field mapping and sampling. Granular resources were sampled at a 500-m interval and non-granular materials were sampled at a 1.5- to 2-km interval. Data were gathered on landforms and stratigraphy as well as a field description of the sample and deposit types. Particle-size and lithologic analyses of the samples were also conducted.The locations of samples and deposits were mapped on 1:50,000 topographic base maps and summarized for publication at a 1:250,000 scale. Surficial geology maps were produced at a 1:50,000 scale. A computer program is being developed for the search and retrieval of field data.The first phase of the Inventory of Aggregate Resources program is nearing completion and to date has collected information on approximately 9,500 samples throughout Newfoundland and Labrador. This data will be used to provide f or the effective management of these vital non-renewable aggregate resources.The mineral aggregate industry in Newfoundland and Labrador is very competitive, but undercapitalized when compared to other provinces. The demand for aggregates is forecasted to increase to in excess of23 million tons per annum by the year 2002.In terms of over-all mineral production, the extraction of sand, gravel and stone has a significant impact when compared to other minerals in terms of value and tonnage produced.IntroductionThe province of Newfoundland has approximately 18,000 km of coastline. A large proportion of the population lives in coastal communities where, traditionally, beaches have been a major source of construction materials. Beaches have, therefore, often been subjected to overutilization, resulting in erosion of back beach areas or adjacent headlands."

Jan 1, 1982

By A. Jafarnia

Aluminum alloys are frequently grain refined during solidification in order to promote the formation of an equiaxed grain structure in the casting. The application of Ti-based grain refiners and/or Ti containing master alloys for improving mechanical properties may result in formation of Al-Ti based intermetallics. Although the grain refinement produces many desirable qualities in aluminum castings such as improved castability and mechanical properties, the addition of Ti to Al-Si foundry alloys may lead to the formation of some undesirable intermetallic particles such as AlTiSi and cause a number of operational problems such as nozzle blockage due to segregation and agglomeration of aluminide particles within the nozzle. There are several questions to be clarified when minor amount of Ti is added to Al-Si alloys. They include nucleation and growth of AlTiSi particles, their morphologies and orientation relationships with aluminum matrix and the dissolution of these intermetallics during the course of solidification and/or post solidification treatments. The current study was initiated to study the process and possible mechanism of aluminide dissolution and the related phenomena such as segregation and agglomeration. It reports the results found during reheating of laboratory prepared Ti-added A356 alloy at three temperature ranges of below solidus, mushy zone and above liquidus.

Jan 1, 2004

By Victor Rudenno

"Previous methods have employed statistical analysis to model future mineral resources. The method presented in this paper uses Zipj&apos;s Law to determine the size and grade of tin deposits still to be discovered. The law is applied independently to both known deposit tonnage and grades. A probability distribution for both &apos;tonnage and grade is computed/or those deposits still to be located and then, by applying a correlation between tonnage and grade, a distribution of the probability of metal content discovery is obtained.By considering an economic cut-off in metal contained in a deposit, the probability of economic success for the next tin discovery is computed, both for a world discovery and for the special case of Tasmania, Australia. The results indicate a probability of 11-37% on a world-wide basis and 18% chance of economic success in Tasmania.IntroductionIn the past , most attempts to determine the probability of success in finding an economic mineral deposit have relied on the accumulation of statistical data. These data are then used to predict a suitable frequency distribution to assess the probability of finding a deposit of a given size and grade (Singer,1975).The method not only relies on one having sufficient data, but also on the assumption that the data are not biased and that the distribution (usually log-normal) is a correct one. The method presented in this paper, to analyze tin deposits, uses Zipf&apos;s Law, which has been recently applied to oil, uranium, lead-zinc and gold deposits by Folinsbee (1977) and to Western Australian gold deposits by Rowlands and Sampey (1977). Tapp and Koniuszko (1978) have applied Zipf&apos;s Law to mineral distribution patterns in the Northern Australian orogenic provinces, which has enabled them to make predictions with a relatively small data source."

Jan 1, 1981

By F. S. Hoseinian, M. Irannajad, M. Safari

In this study, the effect of chemical interactions of materials used in ion flotation on the removal of Ni(II) ions from low concentration synthetic wastewater was studied. Sodium dodecyl sulfate (SDS) and ethylhexadecyldimethylammonium bromide (EHDABr) as collectors and methyl isobutyl carbonyl (MIBC) and Dowfroth250 as frothers were used. To investigate the effective parameters and interactions of them, 16 experiments including 6 level variables were performed by supporting DX7 software and on the bases of 2-level factorial method. In the first step, the tests were conducted in a Hallimond tube. The result showed that collector of SDS and frother of Dowfroth 250 had appropriate interaction with each other at pH = 3. In the second step, optimal results from the first step were evaluated in a mechanical flotation cell. The removal of Ni(II) ions increased by increasing the time of flotation and they have a direct relation with the water removal. The kinetics study shows that the order and the rate of removal of the reaction do not follow any of the zero-order, first-order and second-order equations. The flotation rate curve on the removal of Ni(II) ions will divide the separation process to two stages, a fast flotation rate at the first stage and a slow flotation rate at the second stage. Ni(II) ions removal was obtained 88% at the best condition.This study showed that the use of ion flotation was a very effective method for Ni(II) ion removal from industrial wastewaters.

Jan 1, 2016

By Georges Houlachi, Raynald Labrecque, Jean-Noël Cloutier

"Electrodialysis (ED) is an electro-membrane technology based on electrochemical process using electrical energy for the production of chemicals. The process can be used for concentrating, extracting, separating products, modifying molecules, purifying solutions, pH adjustment and regenerating salts into their base and acid. This paper reviews the principle of ED, present some of the different options and discuss applications that are relevant to the hydrometallurgy and mining industries for the treatment of effluents focusing on recovery of chemicals (acid and metals) and recycling of water minimizing the environmental footprint.INTRODUCTIONElectrodialysis (ED) is usually defined as an electrochemical separation process in which electrically charged membranes and an electrical potential difference are used to separate ionic species from an aqueous solution and other uncharged components [1]. ED technology consists of an electro-membrane technology based on an electrochemical process using electrical energy for the production of chemicals. It is a method combining electrolysis and dialysis was proposed for the first time in 1890 by Maigrot and Sabates [2]. In the late 1930s Teorell, Meyer and Sievers discussed membrane phenomena, revealed membrane potential, electric conductivity, transport number [3]. Meyers and Strauss introduced a multi-compartment ED apparatus consisting of two electrodes and a stack of ion-exchange membranes between them [1]. They succeeded to double the concentration of a KCL solution [3- Tarleton]. In general, ED consumes less energy than electrolysis to perform salt splitting. In that regard, one can expect an energy reduction of about 30% [4–5]. ED offers a great versatility in the domain of separation processes. Indeed, it can be used for concentrating, extracting, separating products, purifying by desalination, pH adjustment and regenerating a salt to acid and base components. This paper reviews the principle of ED, presents various options available and discusses potential applications relevant to the mining and metallurgy industries with economics of some successful industrial applications."

Jan 1, 2016

By F. R. Ploeger, J. H. Crocket

"IntroductionRocks in the Kirkland Lake district form part of the Timiskaming Group, a south-facing homoclinal sequence of wackes, conglomerate, trachytic flows and pyroclastic rocks and syenitic intrusive rocks. Hewitt (1963) indicates that the thickest section, about 5 km, of the Timiskaming Group rocks is attained in Lebel Township. Several writers (Thomson, 1948; Hewitt, 1963; Hyde, 1978; Jensen, 1978; and Downes, 1979) have observed that the Timiskaming Group unconformably overlies the Keewatin volcanics, particularly along the northern contact. Recent work by Downes (1979) in McGarry and McVittie townships to the east of Kirkland Lake has shown that much of what had formerly been classified as Timiskaming actually belongs to an older group of rocks, the Larder Lake Group (Jensen 1978).General GeologyA series of fluviatile, braided-stream sedimentary rocks (Hyde, 1978) form the oldest of the three major rock suites at Kirkland Lake. Conglomerates constitute a large proportion of these sedimentary rocks and typically contain a large percentage of a variety of locally derived alkalic rock clasts as well as the distinctive red jasper iron-formation pebbles (Fig. 1a). The associated wacke units can be massive to finely bedded and are interbedded with the conglomerate. They also contain a large alkalic tuffaceous component.Interbedded with these sedimentary rocks are alkalic extrusive rocks, including tuffs, agglomerates, breccias and flows, which represent episodes of fissure and explosive crater eruption (Cooke and Moorhouse, 1969). The tuffs, although dominantly alkalic in composition, are commonly reworked and contain sedimentary features such as graded bedding, scouring and crossbedding (Fig. 1 b). The trachytic flows are massive to porphyritic and outcrop mainly east of Kirkland Lake in the adjoining townships. Altered leucitic porphyritic flows, locally referred to as red and green spotted trachytes, commonly occur."

Jan 1, 1982

By W. Dan Hausel

"Abstract-Hundreds of diamonds have been found in the United States. The majority of the discoveries occurred during the 19th century as a by-product of placer gold mining. Most of these early diamond finds have no known source, and in many cases are situated in areas unfavorable for diamond exploration based on current models that require kimberlite or lamproite to be emplaced in a stable Archean craton or Proterozoic craton margin.Diamonds have also been recovered in situ from lamproite at Murfreesburo, Arkansas, from kimberlite in the Lake Ellen region of Michigan, and in several kimberlites in the Colorado-Wyoming State Line district. Unverified reports also suggest that diamonds may have been recovered from other related intrusions at a number of localities in the United States."

Jan 1, 1995

By L. C. Bird, A. I. A. Salama, M. W. Mikhail

"A program of sampling in Canadian washeries was carried out by the Coal Research Laboratory (CRL) over a period of two years to evaluate the performance of various density separators in these operations(1). Operating data on quality and recovery of products, separation efficiencies and cutpoints for each separator type are compared with data predicted using computer models developed from previously existing data.The Heavy Medium Cyclone (HMC), Heavy Medium Bath (HMB) and jig models give predictions of recoveries and qualities of products for sizes coarser than 10mm with absolute value of error mean less than 7 per cent, whereas predictions of the Water Only Cyclone (WOC) model for -10mmfine coal are with absolute value of error mean less than 8 per cent. Although less accurate for -10 mm fine coal, the HMC and jig models produce predictions of recoveries with absolute value of error mean less than 2 per cent and quality of products predictions with absolute value of error mean less than 28per cent which are generally acceptable because more liberation in the fine fractions appears to compensate for any difference in the accuracy of separation, resulting in good prediction of the clean product. However, ash content of the actual fine refuse was lower than predicted. The difference is attributed to the highly friable nature of Canadian coals which tends to cause an excessive loss of coal fines to the fine refuse.A comparison study based on quality and recovery of products is made between the Dutch State Mines (DSM) models and the recently modified models, both produced comparable predictions."

Jan 1, 1985

By C. Desmeules

"Carbon addition in the oxide pelletizing process is a big concern at the Sidbec-Normines pelletizing plant since 1976.Laboratory pot-grate testing carried out before the initial start-up of the Port-Cartier plant indicated that the nominal pelletizing grate capacity could be increased by fifteen per cent with a suitable carbon addition. Also an improved induration cycle offered the possibility of a significant energy reduction within the process with no adverse effect on pellet quality. A one-month plant scale program duplicated the lab test results and confirmed the anticipated cost saving by using these techniques. Since March 1980, Sidbec-Normines used coke addition as a current operation.This paper reviews briefly earlier laboratory and in-plant test work carried out to investigate the effects of adding carbon materials to the Fire Lake hematite concentrate, and presents operation techniques and plant results of carbon addition in the Port -Cattier pellet plant.IntroductionThe Sidbec-Normines pelletizing plant at Port-Cartier, Quebec, is designed to produce six million ton s per year of oxide pellet s. It is a Dravo-built two-line plant; one line to produce three million s tons per year of blast furnace grade pellets averaging 5.5 per cent silica, and another line of three million ton s to produce direct reduction grade pellets of about 2.0 percent silica.The laboratory pot-grate test program was conducted in 1977 at the British Steel Corporation Research Laboratories in England, with the assistance of J .E. Appleby, consultant to British Steel Corporation (overseas services) Limited.The purpose of that test program was to determine the optimum energy saving cycle and to study the physical and metallurgical effects on blast furnace and direct reduction pellets."

Jan 1, 1983