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By Lorne Roberts

"This paper describes: how Falconbridge's fire protection system meets the needs of the Lockerby Mine; why the system was chosen over other alternatives; how it is unique, but can be applied to any underground situation; details of the system; how it was installed; the role of a fire protection company; and general considerations when choosing afire-suppresant system.IntroductionIn May 1981, after about three years of searching for the best fire protection system for the re-opened Lockerby nickel mine at Whitefish, near Sudbury, Ontario, Falconbridge Nickel Mines Ltd. installed an AFFF type of fire suppression system. It was designed and supplied by the Fire Protection Systems Division of Levitt -Safety Ltd.The system protects against loss of life, equipment and/or production, and it complies with legislation should fire occur in a fuel storage area and/or scooptram garage and service bay at any or all of the three levels near Shaft No.2.About 18 months after Levitt-Safety began working with Falconbridge, the system was designed and installed at a cost considerably less than that which would be incurred if fire damage caused the loss of two days of production.The fire protection system, which overcomes a limited water supply, is a self-contained balanced pressure proportioning system. It senses the flow and automatically determines the correct concentration of foam to water. It is triggered by a release mechanism which operates a bank of nitrogen cylinders, which in turn pressurize a pressure vessel to expel the foam concentrate and water from the tanks. This solution is piped to sprinkler heads in the specific area."

Jan 1, 1982

By P. A. Verhey

"This paper describes a series of wear-resistant ceramic materials which have been successfully used in the mineral processing industry in Canada. Applications include use with metallic ores, coal, potash and asbestos, and in other processes where wear degradation is of major concern. The paper will also deal with considerations involving the selection of the different ceramic materials available. It will cover the installation of ceramic materials on support structures under varying process ' conditions, as well as the other physical and chemical factors which have to be taken into account.IntroductionIn the mineral processing industry, large volumes of ores tailings and other materials are handled. The abrasive nature of most of these materials results in extensive wear to both handling and processing equipment.Wear ratios versus cost, production losses due to down time and wear-resistant material suitability for a given application all demand particular attention when viewed against the need for increased efficiencies in existing processes. As a consequence, a very active continuous search for materials with improved wear resistance has been carried out for many years.In this search, starting about 20 years ago, dense ceramic materials were tested and evaluated in certain applications, notably in the iron ore and asbestos operations in Eastern Canada. As a result of substantially better performance both in continuous extended life and ultimate economics realized , wear-resistant ceramic applications developed progressively in many other processing applications, replacing traditionally used materials.In the vast majority of wear-resistant ceramic applications, considerable extended life over previously used materials was established. This invariably was not just a fractional increase but, in most cases , in factors of double, triple and often all the way up to 18 and 20 times the life of alternative materials used previously. In certain applications, extended life could not be measured and appears to be indefinite.Obviously, as a result of such experiences, the progressively wider use of wear-resistant ceramic materials is now an established trend."

Jan 1, 1981

By M. Fiset, D. Belley

"To better understand the wear process of various materials that may be used as blades on snow removal equipment, the first step is to evaluate the influence of the load applied and the moving speed on road wear rates of one type of steel and three types of polymers. While the behavior of steel conforms to Archard's law, wear rates of polymers increase to a power of ex of the load applied according to a model implying that the wear of these materials is due to fatigue. The wear rate of some of the polymers varies considerably in terms of speed, unlike the steel. The wear resistance of some of these polymers outclasses the steel tested as long as the speed is not too great. They, therefore, present interesting alternatives for snow removal on more fragile surfaces such as sidewalks and zone made of inter-block slabs.IntroductionSince the dawn of the Industrial Revolution, the massive use of machines has brought with it a number of different problems regarding wear. Snowplowing roads, parking lots and sidewalks is an activity that generates enormous expense in a country such as Canada. To better understand these wear processes and in the hope of stimulating new approaches designed to reduce the costs related to this sector of activity, this paper presents the behaviour of several materials (steel, polymer and rubber) as they wear on an asphalt-fines matrix surface lubricated with water. Also discussed is the effect of various parameters such as the load applied and speed."

Jan 1, 1990

By J. L. Collins

"This paper deals with the quantitative analysis of mine maintenance records. Based on a case study of dozer engine records, the author suggests an easy method of deriving useful information for managerial decisions in a step-by-step manner.More specifically, the paper deals with the following topics:• determination of the most economical replacement time,• determination of reliability characteristics,• determination of the number of replacements, and• determination of the number of spares.IntroductionThe mining industry collects a lot of information about every aspect of its activities, an example of which appears in Table I. In Table I , the distribution describes the operating hours at failure of 56 different dozer engines used in severe applications. Besides calculating an average and possibly a standard derivation from the data, little else is derived, at least from a statistical point-of-view.More information can be obtained from these records that could help management in the decision-making process.To illustrate this point, the sample data appearing in Table I will be analyzed in detail by making use of well-known concepts in reliability engineering.Distribution of DataTable I represents a distribution obtained from the recorded hours cumulated from the operators' time cards. The operating hours have been divided into fourteen classes for each 1000 hours of engine running, e.g . all engines scoring an operating time of between 1001 and 2000 hours formed a class , those scoring between 2001 and 3000 hours another one, etc. Generally, the class interval should be a multiple of the equipment preventive maintenance check period.The minimum acceptable sample size should be large enough to ensure that the score in each class interval is at least one. Ideally, the score for each class interval should be at least five so that a chi-square test could be carried out if necessary.The average life of an engine can be found by adding the products of the frequency and the class mark (mid-point) values. Therefore:"

Jan 1, 1987

By D. W. Smith, J. J. Koskinen, T. A. Enwald, M. E. Ball

"A full-scale demonstration unit of Tampella's LIFAC desulphurization process was tested at SaskPower's Poplar River Power Station Unit No. I. The test program included a series of parametric tests, followed by a 1500 hour operational evaluation. This paper summarizes the results of the test program, and SaskPower's economic evaluation which led to selection of the LlFAC process for SaskPower's 300 MW Shand power station. IntroductionOne of the major influences on the coal mining industry today is public and legislative response to acid rain. When sulphur-bearing fuels such as coal are burned, the sulphur oxidizes to sulphur dioxid e (S00 which, if uncontrolled, enters the atmosphere as one of the by-products of combustion. S02 then combines with water in the air to form an acid and acid rain results. Combustion also produces nitrogen oxides (N0J which can combine with water in the air forming nitrogen based acid , also contributing to acid rain.Acid rain has become a significant international concern. Newspapers have reported on dying forests, dead lakes and crumbling statues. Papers also include articles professing that the physical results of acid rain are vastly overstated. In the United States, a IO-year, Y2-billion dollar study called the National Acid Precipitation Assessment Program (NAPAP) was commissioned to evaluate the effects of acid rain. Even this extensive scientific study did not resolve the controversy. Despite disagreement over the quantitative effects of acid rain, there is no doubt that public concern over the issue is widespread and deeply felt.In response to this concern, legislators throughout the world have reacted with programs that restrict the emission s o f SO, and NO,. To industries involved in the supply and use of coal, the impact of these legislative programs has been extensive. United States power plants will be spending 10 billion dollars in the next decade for flue gas clean-up equipment. Even all this new equipment will not stem the tide of change to low sulphur coals and to “clean “natural gas. The following summarizes legislative actions taken for Canada and the United States."

Jan 1, 1993

"Nanisivik Mines Ltd. operates a 10-M W diesel-electric generating plant at its zinc-lead operation on Baffin Island in the Canadian Arctic. This paper provides a description of the plant and the integrated waste heat recovery system. Data is presented detailing the actual costs of operating a plant over a period of seven years. Problems in operation are described as well as the success of the plant in meeting its objectives over the years. IntroductionNanisivik is located on the shore of Strathcona Sound at the north end of Baffin Island (Fig. I). Nanisivik Mines Ltd. has operated a 2,100 tonne per day zinc-lead underground mine and a concentrator, together with supporting infrastructure, at this location since October 1976. Annual production of 100 000 tonnes of zinc and 10 000 tonnes of lead concentrate is transported by ship to Europe during the mid -July to mid October shipping season.All electrical needs of the project are provided by the company-owned and -operated power plant. Facilities served by this electrical system are the underground mining areas, the concentrator and industrial area, a townsite, airport, and shiploading dock complex."

Jan 1, 1986

By S. N. Kalyakin, D. S. Flett, M. A. Mulagaleeva, N. V. Gudkova, S. S. Serdyuk, V. I. Kuzmin, Institute of Chemistry and Chemical Technology SB RAS, O. A. Logutenko, V. N. Kuzmina, V. G. Lomayev

"The Chuktukon niobium-rare earth elements ore deposit is located in Siberia (Russia). Weathered carbonatite crusts are the basis of the ore deposit. The deposit itself is 3.5 km in length, about 800 to 1400 m in width and up to 200–300 m in thickness. The ores are composed of iron-manganese oxides (hydrogoethite, hematite, psilomelane, pyrolusite) and contain 3–7% of rare-earth phosphates (florencite, monazite) and 0.5–1% of niobium oxide (pyrochlore). The ore is completely finely dispersed and consists of oxide particles formed of compact, dense aggregates which makes ore dressing as well as leaching of the rare and radioactive elements very difficult. Several options for processing of these ores have been considered: 1) reduction of the iron oxides to magnetite followed by beneficiation with magnetic separation to produce a rare metal concentrate; 2) processing of the rare earth elements (REE) containing minerals by direct alkaline-acid treatment; 3) processing of the ores using nitric acid leaching in an autoclave.INTRODUCTIONThe Chuktukon niobium-rare earth metal ore deposit is located in Siberia, in the Krasnoyarsk region, 110 km from the Boguchan hydroelectric power station which has recently been commissioned. This mineral raw materials is capable of providing impetus for the modernization of the Russian rare metal industry because of its qualitative and quantitative characteristics. The deposit is located in a region of promising industrial development and is a part of the territoriy where the Russian Federation’s Program “Complex Development of the Lower Angara Region” is currenly being realized. The main program directions are creation and development of industrial activities in sectors such as power, metallurgy, oil and gas, gold, rare-metals, and timber. The program will aid the development of the niobium and rare-metal resources of the Lower Angara and neighbouring regions as well as increase the national production of REE and therefore import substitution (Lapin, 1997; Lomaev & Kuzmin, 2003; Lomaev & Serdyuk, 2011; Serdyuk, Lomaev, & Kontorovich, 2000)."

Jan 1, 2016

By Dirige. A. P. E.

A study was conducted for an operating mine to determine the appropriateness of its tailings material to be used for the preparation of a low modulus, high density backfill. The research was initiated due to issues arising from increased observations of compressive failure of backfill placed in stopes and inconsistent backfill behaviour (i.e. increased backfill brittleness and modulus). Backfill materials investigated were classified tailings and de-slimed tailings. Characterization of the physical properties of the classified and de-slimed tailings materials was conducted to assess the effect that these material properties would have on the strength and deformation behaviour of high density backfill products made using them. Such behaviour was investigated to determine whether differences in tailings physical properties would influence the strength and modulus character of the backfill materials. Uniaxial (UCS) and consolidated-undrained triaxial compression strength tests were conducted to determine strength performance and deformation behaviour of backfill. This paper presents the results of the backfill material characterization study and how different particle size distributions affected the strength performance and deformation behaviour of the different backfill mixes. It also demonstrates how stress-strain curves generated from material strength tests were used to evaluate variation in high density backfill mix response when such materials were subjected to unconfined and confined (triaxial) compression loading.

Aug 1, 2013

By S. Kelebek

Batch flotation tests were carried out using samples from stockpiles that were up to 1.5 months old as well as fresh samples oxidized in the lab for up to six months. Head grades and size distributions of samples were equalized whenever possible. The samples from stockpiles and oxidation experiments produced inferior nickel grade-recovery compared to the fresh sample. The poorer grade-recovery performance was attributable to two factors. First, a significant dilution effect was observed due to complete flotation of pyrrhotite. Secondly, the same stockpiling conditions caused nickel losses that were attributable to non-floatability of some pentlandite. Application of a high pH of 10 compared to the regular pH of 9.2 slowed down pyrrhotite flotation kinetics, but was not able to prevent complete flotation after 8 minutes. The samples oxidized in the lab did not match full characteristics of stockpile samples. They provided somewhat better selectivity for pentlandite. Some correlations were observed on a qualitative basis between surface characteristics such as elemental sulphur formation, activation and flotation behaviour. Oxidation conditions, which induce floatability on pyrrhotite while causing incremental loss in pentlandite floatability appear to be the root cause of difficulties in the processing of oxidized forms of these ores.

Jan 1, 2006

By Vlad Ruzicka

"Uranium deposits in the Rabbit Lake-Collins Bay area are associated with the sub-Athabasca unconformity which separates crystalline Archean or Aphebian basement rocks from Helikian clastic sedimentary rocks of the Athabasca Group. The basement rocks are a part of Wollaston lithostructural domain.Most of the high grade deposits, such as Collins Bay ‘A’ and 'B' Zones and Eagle Point are associated with altered rocks of the basal unit of the Wollaston Group. Some deposits, such as Raven and Horseshoe are confined to the uppermost unit of this Group. The Rabbit Lake deposit occurs in the middle, meta-arkose unit of the sequence. Locations of some deposits (Rabbit Lake, Collins Bay ‘A’ and 'B' Zones) are also controlled by thrust faults, such as Rabbit Lake Fault and Collins Bay Fault.The deposits contain either monometallic (uranium) mineralization (Rabbit Lake, Raven, Horseshoe) or polymetallic (mainly uranium-nickel) assemblages (Collins Bay “A’ and 'B' Zones).IntroductionThe Athabasca Basin region, a part of the Churchill Geological Province of the Canadian Shield, is composed of Archean and Aphebian crystalline basement and younger, Helikian, unmetamorphosed supracrustal rocks. The Rabbit Lake-Collins Bay area is situated at the eastern margin of the Athabasca Basin region, which hosts a substantial proportion of Canadian uranium resources.The crystalline basement complex was subdivided by Lewry and Sibbald (1979) into lithostructural domains and these domains were grouped into major crustal units designated, from northwest to southeast, as Western Craton, Cree Lake Mobile Zone, consisting of Wollaston, Mudjatic and Virgin River domains, and Rottenstone Complex (Fig. 1)."

Jan 1, 1986

By T. B. Armstrong

"The energy situation is extremely fragile and there is a critical need for energy conservation in the short term and development of new technology in the long term. To keep tabs on energy flow, separate electrical metering is being installed in major industries: The first step reduces demand through peak load control; the second reduces the waste of energy by monitoring energy used per unit of production. IntroductionThe current energy situation is best described as being extremely fragile. The supply of hydrocarbons is being exhausted, while energy needs remain the same in the industrialized nations and are increasing in the Third World.The petroleum era is expected to come to an end in this century, as there will no longer be enough. Gas, coal and electricity will replace some oil as it becomes scarcer during the transitional period before new sources are gradually developed.There is a critical need for energy conservation in the short term. Conservation will, to a great extent be justified by savings, as it will be less expensive to recover energy that is being wasted than to acquire additional energy.The gradual development of new technology is expected to increase energy self-sufficiency in the long term. New energy sources are attracting a growing interest and are becoming more economically feasible and marketable. These rediscovered energy sources include peat, wood, solar, domestic waste and windmills.The sudden increase in energy prices has forced users to look at the way energy is used and find ways to save it. Major industries have found that using separate meters for each department spurs energy responsibility. Energy trim programs now rank in importance with profitability, productivity and with quality.Energy has become such a crucial cost element that better data are essential for planning. Data acquisition varies with plant size and number of utilities. Meters can be read manually or monitored by computerized energy management systems.The relationship of electrical energy input and production levels for a typical uranium mine will be used to demonstrate two steps to energy management. The first step reduces demand through peak load control; the second reduces the waste of energy by monitoring energy used per unit of production.The direct benefit of saving energy is the money saved."

Jan 1, 1980

By W. P. Clement, M. C. Bell

"PT International Nickel Indonesia, a subsidiary of Inco Limited, mines and processes nickel laterite ores for the supply of nickel matte, primarily to the Japanese market. It has large ore reserves and a substantial portion of its energy requirement is supplied from its own hydro-electric plant. Since the early 1980s, the company has increased its production level and has dramatically reduced its unit costs. Projects are in progress to further decrease costs and recently a major expansion - 31% increase in nominal capacity - has been undertaken, consistent with marketing opportunity in Japan. The expansion project, which has a low capital cost per unit of production, is outlined in this paper.IntroductionPT Inco is a fully integrated mining and smelting facility located in Indonesia on the island of Sulawesi, and is based on a very large, world class nickel laterite orebody located 60 km inland from the Gulf of Bone. Construction of a single furnace line plant started in 1973. Complete supporting infrastructure of townsite, hospital, schools, shopping centres, road systems, and an airport, all had to be built. Prior to completing the first phase, the decision to expand the plant to a three kiln-furnace line was made. A major factor in the decision was the ability to develop the hydroelectric potential of the nearby Larona River. This involved construction of a 30 m high dam, and a 7 km surface canal to the generating station. The penstocks drop 150m to three 55 Mw turbines. The power generated is sufficient to supply the entire electrical load for the complete smelting complex and town site. The unique capability to supply the high smelting energy requirements for a lateritic nickel ore by fully captive hydro power, has, over the past decade insulated PT Inco from the large upward swings in oil prices suffered by other lateritic nickel producers.Wet ore is first partially dried to 20% moisture in two co-currently fired rotary driers, screened on an internal trommel, and delivered to two dry ore storage buildings. The partially dried ore is calcined at 750°C and partially reduced in three large 100 m by 5.5 m kilns. Reduction is accomplished by lancing bunker C oil onto the ore bed at the discharge end of the kiln. The kilns are equipped with five air pipes with onboard blowers to gradually bum the combustible gases generated by the lance oil. The kilns were also originally equipped with two side burners to supply additional heat close to the feed end of the kiln. Calcined ore is transferred by 20 ton refractory lined containers to the furnace feed bins at the top of the smelter. Smelting is carried out in three 18 m diameter furnaces powered by 45 Mw transformers. Slag is skimmed at 1550°C through water cooled breast plates and removed to the slag dump by Haulmaster Carriers. Matte of 25% Ni, 1O% S, 65% Fe is tapped at 1350°C into the converter aisle. The iron is slagged in converters to produce a nickel sulphide matte at 80% Ni. Three rotary Kaldo converters were initially installed. The product matte is granulated, dried, and shipped in returnable rubber bags to Japan. Most of the matte is fluid-bed roasted to nickel oxide and then directly reduced in a second reducing fluid bed reactor at our facilities in Japan.The smelting complex was designed to smelt two million tonnes of dry ore per year, equivalent to 34 000 tonne nickel production at an ore grade of 2% Ni. The cost of the entire project including working capital was $900 million."

Jan 1, 1990

?NWCC has the highest number of Aboriginal students of any post secondary institution in BC and the region served includes 25 bands ? Chair of the Board of Governors is Irene Seguin (Hagwiloo K?am Saxwhl Giis) from Gitwinksihlkw ? FN council ? 39 First Nations Members * focus is to develop policy recommendations to increase student success rates

May 1, 2009

By J. P. Aiello

"INTRODUCTIONWhile this paper deals specifically with potential coal use at the Cold Lake Project of Esso Resources Canada Limited, a majority of the technical aspects of coal conversion could apply to any oil field and industrial boilers or stearn generators. In 1962, Imperial Oil Limited's production arm (the forerunner of Esso Resources), began examining methods of extracting bitumen from a 50 m thick layer of oil sand buried 450 m below the surface in the Cold Lake area. Almost two decades of research followed to develop an in situ oil sands recovery technology that made commercial production feasible.A $13 billion mega project that would have produced 22 000 m3/d (141 000 barrels/day) of synthetic crude oil (160 000 bpd of bitumen) was shelved in 1981, and ultimately replaced by a phased development strategy, involving smaller production units, to bring blended bitumen production on stream as markets and prices permit.The first two phases came into production in 1985. There are currently a total of six phases in production with four more in the construction stage. Each phase has 130to 140production wells (initially) and a central plant with water treatment, crude treatment and stearn generating facilities capable of producing 150 m3/d (9500 bpd of raw bitumen). The stearn generation section for each phase consists of three 180millionBtulhour oil fieldsteam generators.In its natural state, the bitumen is too thick to be recovered using conventional oil recovery techniques. At the Cold Lake Project, bitumen is recovered by a method called cyclic stearn stimulation. Water is pumped to the central plant where it is treated and heated to produce high pressure, high temperature steam. During the steam cycle, this steam is transported in insulated pipelines to the wells for injection into the oil sand formation. This cycle lasts from 30 to 50 days, heating the formation and causing the bitumen to flow. Following an initial flowback period, a surface based artificial lift system pumps the heated liquid bitumen, mixed with water and gas, out of the well and back to the central plant. The water and gas are separated from the bitumen, with the gas being used to provide some of the fuel for the stearn generators and the water being treated and recycled. Approximately 5% of the water cannot be recycled and is disposed of by injection into deep formations . The bitumen is blended with a diluent and shipped by pipeline to market."

Jan 1, 1989

By G. Lucas

"Material substitution occurs continuously in response to competitive and economic pressures. Technical development can accelerate or slow substitution by improving the performance of the invading or defending material. The choices are seldom simple and have to be made in the context of continuous commercial change.The development and commercialization of a new aluminum material is examined. The material has been introduced into· several different markets, so it is possible to compare and contrast the degree of success obtained in each.IntroductionAluminum-based materials have been in use for over one hundred years and , therefore, the development of a new family of alloys is rare. In the early 1970s, Dr. L.R. Morris and his coworkers at Alcan' s Kingston Research Centre started work on what was, at the time, something of a scientific curiosity-a family of alloys strengthened by an unusual mechanism.This paper deals with the development and commercialization of what became known as the Alcan 255 alloys"". These alloys have found uses in several markets, usually as improved substitutes for existing materials. Forecasting the usefulness of a substitute material in an existing marketplace is difficult, in part, because even material users are seldom able to specify precisely their requirements. This uncertainty can cause the failure of some substitutions but can also lead to opportunities which were not initially obvious.Technical BackgroundPure aluminum is a soft, weak material. It can be strengthened by the addition of various alloying elements and by work hardening. Alloying elements usually act by forming solid solutions which are stronger than the pure metal or by precipitating during heat treating or aging and so preventing the easy movement of dislocations during deformation. Elements which can perform either role had been investigated for decades and were thought to offer little chance of technical breakthrough in 1970. An outgrowth of the then new and exciting research on directional solidification seemed, however, to offer such promise.Some aluminum-iran-manganese alloys will solidify under certain conditions as 'coupled growth' eutectics (Figs. I and 2). The microstructure shows one phase growing as long rods through the other. This is an uncommon structure and it was investigated to see if it had equally unusual properties. On deformation by rolling the rods were broken up into small equiaxed , evenly-spaced particles (Fig. 3). Materials with this structure were found to be stronger than other alloys with similar amounts of alloying addition, and to resist thermal softening remarkably well. This combination of properties was thought initially to be due directly to the particles by a dispersion strengthening mechanism, but later this was found not to be strictly true."

Jan 1, 1987

By Elma van der Lingen

Gold is considered the most inert of all metallic elements, but the metal can show catalytic activity when prepared by specific techniques. Preparation techniques being used to prepare gold catalysts systems mainly involve precipitation methods incorporating gold compounds or complexes. This paper introduces a totally different method for the preparation of gold-based heterogeneous catalysts that can be used for oxidation and reduction reactions, as well as electrocatalysts. The method involves alloying of gold with a less noble metal, such as aluminium, to form a gold-containing intermetallic precursor. AuAl2 was produced by melting gold and aluminium together in a vacuum arc furnace under a protective atmosphere. The aluminium is then dissolved from the AuAl2 precursor by means of NaOH to produce a highly porous gold structure. The paper also reports on a method of incorporating transition metal oxide(s) with the porous gold to form an active heterogeneous catalyst. Promoter elements can also be melted with AuAl2 to improve catalytic activity. Alloying has the advantage that the promoter element can be in contact on atomic level with the gold. In-situ xray photoelectron spectroscopy (XPS) studies have also been done on the porous gold catalysts to further clarify the CO oxidation mechanism on gold-based catalysts.

Oct 1, 2003

By Yann Sivry, S. Subramanian, Divyasree C. Prabhakaran, Jean Riotte

The potential of a bacterial strain isolated from water samples collected from a chromite mine in Odisha, India has been assessed for the bioremediation of hexavalent chromium, a toxic environmental pollutant. The isolate was identified as Sphingopyxis sp., a Gram negative bacterium, adopting molecular biological protocols and biochemical characterization techniques. Detailed investigations on the bioremoval of Cr(VI) were carried out using Sphingopyxis sp. cells and the various parameters affecting the biosorption process were evaluated. About 55 % biosorption of Cr(VI) was obtained using Sphingopyxis sp. bacterial cells and the residual chromium in solution was found to be bio-reduced to the trivalent form, namely Cr(III). Thus, complete bioremediation of Cr(VI) could be achieved using the mine isolate, with contributions from both biosorption and bioreduction mechanisms. The Cr(VI) biosorption isotherm obtained for the isolate was found to follow a typical Langmuirian behavior and the free energy value of biosorption was determined to be ~-25 kJ/mol, indicative of involvement of chemical binding forces in the bioremediation process. The chromium biosorption kinetics by the isolate followed a pseudo second order reaction. The FTIR spectral studies revealed that carboxyl, hydroxyl, amino and phosphate groups were involved in the biosorption process. X-ray photoelectron spectroscopic studies on the bacterial cells interacted with Cr(VI) confirmed the presence of both Cr(VI) and Cr(III) on the cell surface. The electrokinetic studies revealed that the surface potential of the bacterial cells were less electronegative subsequent to interaction with Cr(VI), compared to the cells alone, which further testified to the binding of positively charged Cr(III) ions, formed by bioreduction of Cr(VI), to the bacterial cell surface. A marginal shift in the iso-electric point obtained for the bacterial cells interacted with Cr(VI), corroborated the involvement of chemical binding forces in the bioremediation process.

Jan 1, 2016

By Pierre Buteau

Peat/ands distribution in Canada is widely spread thoughout the country and corresponds to a wide spectrum of wetland habitats which overlay peat deposits. The development and the evolution ofpeat/ands and peat deposits are closely linked together, since the vegetal remains of the peat deposits originate from the peatland habitats, and the peatland habitats constitute a response to many factors, including the properties of the substrate, which are the peat deposits. Peat/ands are defined as waterlogged terrains where the production of plant materials usually exceeds the rate of decomposition. The underlying peat deposits consists of organic residues associated to peatland vegetation, more or less decomposed, built up and kept under anaerobic conditions. Peat/ands evolution and distribution are determined primarily by climatic factors, but also by the geomorphology and edaphic conditions. All of these create particular hydrodynamical environments which will vary according to different regional settings, and sequentially to an evolutive time frame.

Jan 1, 2001

By Gang Mei, Nengxiong Xu, Yanlin Zhang

After open-pit mining finishes, an iron mine with steeply inclined ore-bodies will generally transform to underground mining. Non-pillar sublevel caving method, with horizontal slice mining from up to down, is commonly used for mining deep ore-bodies under the open-pit bottom. As horizontal slice mining proceeds, a gradually enlarging goaf will be formed under the open-pit bottom, the rocks surrounding the handing and heading sides of the goaf will collapse continuously, and then these results in rock-mass failure with large deformation and displacement in the open-pit slope. Based on FLAC3D, a modeling approach to predict pit slope deformation and failure induced by transitioning open-pit to underground mining is proposed in this paper. This method mainly consists of three procedures of modeling, i.e., mining modeling, landslide modeling, and filling modeling, of which landslide modeling is the core of the proposed approach. In the procedures of modeling with FLAC3D, iteration non-convergence is taken as a local failure criterion of pit slope. When iteration calculation cannot converge, the sliding modeling will start by deleting some elements with large displacements, and finish until convergence. Before modeling landslide, several displacement contours of rock-masses in the pit slope are searched out, and each contour is an approximate possible sliding surface of the open-pit slope. From these contours, the most proper one is selected as the slope sliding surface by using the iteration calculation convergence and minimum element deletion as the judgment condition. Landslide modeling is then realized by removing the elements outside the slope sliding surface. Finally, to demonstrate the effectiveness, the proposed approach is used to simulate the process of open-pit to underground mining at Yanqianshan Iron Mine, and to predict the deformation and failure characteristics of open-pit slope during underground mining. The case study results show that: the prediction of the slope stability determined by using our method is consistent with that calculated by using the limit equilibrium methods.

Jan 1, 2015

By Robert B. Parsons

"New Brunswick Finance Minister John Baxter pulled something out of a hat for the mining industry in April, but there is a general concensus in the industry that he should put II back where it came from.The industry has never been in the mood f or progressive rate structures, but that is exactly what New Brunswick 's 1984 budget offers to this depressed sector of the economy.IntroductionThe Province of New Brunswick stunned the Canadian mining community in April with the announcement that the province' s 16% mining tax rate would be replaced with a progressive rate structure effective January 1, 1984 (Table I). The proposed change, contained in the bud get papers tabled by Finance Minister John Baxter on April 17, caught the industry totally by surprise. The move to a progressive rate structure was completely unexpected for a variety of reasons:• Generally speaking, relations between the province and the industry have been relatively good, yet the industry was apparently not consulted with respect to the proposed measure and had no indication that a change of th is nature was coming. This is in stark contrast to the mood which prevailed during the major revamping of the province' s mining tax regime in 1977: at that time, the industry was invited to contribute in advance to the province's plan for a new tax structure.• The new structure would appear to make th e province less competitive in terms of mining tax rates with Ontario , Quebec, and other provinces, despite indications in the past that New Brunswick is very cognizant of this competitive factor in formulating mineral policy.• A joint report in November 1978 by federal and provincial officials to federal and provincial finance and resource ministers, which was careful not to directly criticize Ontario and Quebec's progressive mining tax rate structures, recommended that provincial "" tax regimes be examined to ensure the inclusion of appropriate mechanisms to avoid the excessive taxation of cyclical type profit "" , and that ""the federal and provincial governments consider the concern over progressive tax regimes expressed by the industry and examine mining and royalty tax regimes and the income tax regime with a view to alleviating the effect of such regime on the aggregate marginal tax rate"". In this context, any move to a progressive rate structure would be viewed by many observers as retrograde."

Jan 1, 1984