Search Documents

By Benedetto Corain

The production and dispersion of metal nanoclusters onto inorganic supports and amorphous carbon rest on well consolidated technologies belonging to the realm of industrial catalysis and of basic catalysis research (1). In spite of the existence of a variety of specific synthetic strategies, their very rationale relies on three main approaches i. e.: A: precursors of both the metal nanoparticles and of the relevant supports (or the support itself) are intimately mixed (even let to react) at ambient conditions and then thermo-reduced according to very controlled protocols (2); B: precursors of metal nanoclusters are let to be adsorbed onto suitable supports from the gas or liquid phase and subsequently thermally decomposed (3); C: metastable size-controlled metal nanoclusters are previously generated in a liquid medium and subsequently transferred onto pre-formed support particles (4). The production and dispersion of metal nanoclusters onto organic soluble supports is also a rather well documented academic praxis (5, 6, 7, 8) able to provide e.g. size-controlled Au0 nanoclusters of 4.4±1.7 nm (5). Our group started in 1997 developing (9) an innovative approach to the synthesis of metal nanoclusters dispersed inside insoluble, albeit accessible (see below) mechanically robust gel-type resins (10), which procedure was tested so far on palladium metal. Metal ions are previously dispersed upon ion-exchange inside of the polymer framework, followed by chemical reduction and by the aggregation of born metal atoms into nanoclusters, the size of which is templated (11, 12) by the three-dimensional intercommunicating meshes that build up the overall polymer framework (Figure 1).

Oct 1, 2003

By J. F. Archibald

A research effort has been undertaken, under Workplace Safety and Insurance Board of Ontario (WSIB) sponsorship, to characterize the support capabilities of conventional and innovative spray-on lining materials for mitigating dynamic failure effects created by simulated rockbursts. Conventional spray support media, such as shotcrete and fibrecrete linings, and a variety of new spray-on lining materials [thin, spray-on liners (TSLs)], typically polymer-type thin coatings, were subjected to simulated rockburst influence. For baseline comparison, conventional rockbolt and bolt-and-mesh support products were also evaluated. Observation of lining performance was undertaken through completion of field-scale support and rock detonation trials. Controlled blasting tests were conducted at the Queen’s University Explosives Laboratory to examine the effectiveness of the variety of surface coating agents for modifying dynamic rock spalling processes. All tests were performed upon largely undisturbed and homogeneous rock materials in highly repeatable fashion. All blasts were observed seismically and photographically to provide detailed information concerning rock motion, surface fracturing, ejected fragment motion and support liner survivability characteristics. These material comparison trials were performed to assess the relative effectiveness of a wide range of currently available area support techniques for suppressing hazards associated with dynamic rock ejection. The results of this study validate that thin, spray-on linings may be equally as effective, and often better, than conventional support materials at mitigating rockburst or like damage in highly stressed mine environments.

Jan 1, 2004

By E. R. Packer

"The mill of Anaconda Britannia Mines is located on the eastern shore of Howe Sound, approximately 32 miles north of Vancouver, British Columbia. The mill has a daily capacity of 3400 to 3500 tons and at the present is treating chalcopyrite-pyrite ore from which only the copper mineral is concentrated. For a clear conception of concentrate filtering and shipping practice at Britannia perhaps a bit of past history should be related.For many years the mill concentrated copper and zinc minerals and intermittently a pyrite concentrate was produced. It was general practice to ship copper concentrate by towed barge down Howe Sound, across Juan de Fuca Strait and thence down Puget Sound to Asarco's smelter at Tacoma, Washington. Zinc concentrate was loaded in hopper bottom rail gondolas spotted on rail barges and towed to rail heads in Vancouver, thence by rail to Anaconda Reduction Works in Great Falls, Montana. Most of the pyrite produced was shipped by ocean freighters to Japan and Taiwan with an occasional barge load of 2000 to 4000 tons to nearby customers in Vancouver and the state of Washington.In recent years, because of smelter shut-downs for one reason or another, mostly strikes, a considerable amount of copper concentrates has been shipped by ocean freight to Japan and in 1971 several lots were loaded in gondola cars and shipped by rail to the Anaconda smelter in Anaconda, Montana, because Asarco's smelter was forced by municipal and state anti-pollution laws to limit the amount of S02 emission from the smelter stacks. Zinc concentrate production was halted in the early part of 1Y70 because of zinc depletion in the ores and pyrite production was stopped in May, 1971, because of a lack of markets.Filter equipment in the Britannia mill consists of conventional disc vacuum filters and reciprocating vacuum pumps. The copper concentrate filter was installed in 1923 as a 6 x 8'6"" American disc type manufactured by United Filter Corporation, The zinc concentrate filter, now converted as a spare for copper concentrates, is also a 6 x 8'611 American disc manufactured by Traylor Engineering and Manufacturing Company and was installed the same year. Formerly, there were, in addition, two 4 x 6' disc filters for pyrite and two 6 x 6' disc filters to de-water bulk flotation concentrates ahead of the regrind mills. Installed vacuum pumps were two Ingersoll Rand 22"" x 811 and one 22"" x 9"". One of the smaller machines has since been scrapped.At the time of the writer's transfer to Britannia in 1965, the entire filter system was operating as a unit using two vacuum pumps and a common filtrate tank with a 2"" SRL filtrate pump for five operating filters. The regrind and pyrite filters were in continuous operation and the co11p('r concentrate filter alternated with the zinc concentrate filter because both copper and zinc concentrates were transp0rted to storage by the same conveyor belt."

Jan 1, 1972

By Richard P. Reiff

"The Facility for Accelerated Service Testing (FAST) program has been involved in numerous rail wear tests since its inception in 1976. A number of specialized tools have been developed to aid in assessing specific performance parameters including gauge face wear, head height loss, metal flow, head area loss, hardness, and welded rail end batter. The layout of a test site, including position in curve, number of measurements per rail, and train operation must be properly controlled/monitored to provide valid wear comparisons.This paper will provide an overview of the above-mentioned tools and techniques. In addition, a summary of recent test results from FAST, including information on head hardened rail investigations, will be provided. A set of guidelines for establishing a revenue service field test site will also be provided to aid users in performing evaluations of their own.IntroductionBackground of Rail Wear Testing at FASTThe Facility for Accelerated Service Testing (FAST) located at the Transportation Test Center, (TIC), Pueblo, Colorado has been involved with testing of rail since program initiation in 1976. A huge data base of rail wear information has been gathered from FAST operations under a variety of rail metallurgies, lubrication conditions, and measurement techniques. Attempts at obtaining meaningful rail wear information from early (1976-1978) FAST rail wear data was hampered by two main factors: (I) measurement techniques were insufficiently accurate for the amounts of wear being experienced, and (2) the lubrication was not sufficiently controlled to obtain uniform conditions for a sufficient measurement time period.Subsequent test periods were operated with improved measurement techniques and controls that ensured statistically valid data. The policies and conditions that permit accurate rail wear assessment will be reviewed and outlined in this paper, along with some specific TIC and field examples that will allow the user to improve the accuracy of a field rail test on their own operating property."

Jan 1, 1988

By Lori Kormos, Jhonny Carrión De la Cruz, Dominic Fragomeni, Elizabeth Whiteman, Jorge Oliveira

"Process diagnosis, flowsheet design and optimisation are most effectively and efficiently achieved through the use of metallurgical testwork combined with more modern quantitative mineralogical techniques. Integration of the mineralogical data in testwork programs provides a resolution that cannot be obtained from assays alone and can direct the flow of work to result in optimized conditions more quickly than would otherwise be possible. At Xstrata Process Support (XPS), QEMSCAN (Quantitative Evaluation of Materials by Scanning Electron Microscope) and EPMA (Electron Probe Micro Analyser) information can be employed to diagnose specific issues in a plant or lab scale test and are routinely combined with other metallurgical data sets to benchmark performance, design and optimise flowsheets. Representative sampling protocols for ore bodies or test products, the use of geometallurgical unit classification and high confidence metallurgical test programs are key components of the strategy. Two case studies from Xstrata Zinc’s Antamina Mine and Concentrator in Perú, and Xstrata Nickel’s Nickel Rim South Mine in Sudbury are described to show how the use of quantitative mineralogy were used to diagnose a plant issue and how the data can be integrated into metallurgical programs to assist mineral processing engineers to design and optimise flowsheets.INTRODUCTIONOver the past decade, there has been a shift away from metallurgical testing that employs only chemical assays to quantify performance; the use of empirical observation in order to optimise a flowsheet; and the extraction of bulk samples for testing or piloting. The integration of geological information into the planning and execution of testwork programs including the use of quantitative mineralogy has improved the overall quality and predictability of metallurgical programs. At the same time, improvements to metallurgical testwork protocols such as rigorous statistical assessment of results, the use of factorially designed experimental strategies (DOE), and replicate flotation with appropriate quality controls, has improved the confidence level in these results.Process diagnosis, which utilizes quantitative mineralogy, can clearly define the root cause of the metallurgical issue. Whether used on its own to diagnose an issue or in combination with other metallurgical testwork, the use of mineralogical data has become the standard in the mining industry."

Jan 1, 2010

By Guillermo Turner-Saad

"Best practice in the economic evaluation of mining projects and operations is based on the integration of geological, mining, metallurgical, environmental, marketing, economic and corporate information and strategies. Fundamentally, the economic evaluation takes into account mining, blending, stockpiling, processing, smelting, refining and marketing ore resources with grades estimated by geostatistical methodologies.Nevertheless, a realistic economic evaluation consists of a concurrent and integrated optimization process that maximizes the concentrates or products of liberated and selected ore minerals from mineral deposits. The optimum solution is obtained through a trade-off among mining, blending, stockpiling and processing ore reserves with distinct mineralogy and texture characteristics. The concurrent optimization determines both the practical mining sequence of ore reserves and the dynamic and robust mineral processing flowsheet design over the expected life of mining projects and operations.A combined risk-adverse and concurrent optimization process takes into account the spatial uncertainty of the mineralogy and texture characteristics of ore reserves. Additionally, a variety of mineral processing linear, non-linear, additive and non-additive parameters modeled spatially. The spatial uncertainty of these ore reserves characteristics and parameters has a direct impact in the expected mining sequence, mineral processing flowsheet design, concentrates or products quantity and quality, and economic value of mining projects and operations.Geometallurgical domain constrained stochastic geostatistical methodologies and multivariate mathematical models are applied for spatial uncertainty modeling of ore reserves characteristics and parameters. These mathematical models correlate the mineral processing liberation and selectivity responses of the mineralogy and textures within each geometallurgical domain. These models, in turn, are defined based on results of mineral processing and environmental testwork of unbiased and representative samples chosen for their variability. These samples are selected within mutually exclusive spatial geometallurgical uncertainty domains with similar mineralogical and textural characteristics in mineral deposits.Geometallurgical domains are defined by applying and combining multivariate statistical analysis and implicit modeling methodologies. These involve determining and constraining mineral processing liberation and selectivity properties explicitly contained in the extensive and integrated exploration drillhole database."

Jan 1, 2010

By Mike Johnson, Niels Verbaan, David Dreisinger

The Search Minerals Foxtrot project in Labrador represents a significant Canadian resource of rare earth elements rich in the sought after heavy rare earth elements (19.8% HREE/TREE). A preliminary economic assessment of the project indicated that the project is technically feasible and economically attractive. A variety of metallurgical test programs have been undertaken which have led to significant streamlining and simplification of the process flowsheet. The improved flowsheet should allow Search to reach production earlier and will use conventional processing equipment. The results of these test programs are presented and discussed in this paper.

Jan 1, 2014

By Shawn Healey, Ray Norcross

"Site IdentificationNew Britannia MineA 50/50 WX Gold Inc. - High River Gold Mines Ltd. Joint VentureTVX Gold Inc. is the OperatorLocationThe New Britannia Mine is located in the town of Snow Lake, Manitoba, which is situated between Flin Flon and Thompson, 420 miles north of Winnipeg.Brief Description of OperationNew Britannia Mine processes 2000 tonnes per day at an average grade of 4.5 g/t. Mill recoveries are currently 91 YO, accounting for forecast of 98,000 ounces for 1998.New Britannia Mine's mill complex incorporates conventional crushing, grinding and carbon-in-pulp technology. The design capacity of the New Britannia Mine mill is 1850 tonnes per day. The mill has processed upwards of 2300 tonnes per day, with no required upgrades.Gold recovery averaged 89.8% for 1997 compared to the planned 87% recovery expected from projected metallurgical test work. Year to date recovery mid December 1998 stands at 91.1 %Cash costs for the 1998 year to date were down to U.S. $221.49 per ounce, down 12% from the 3rd quarter of 1997. Milling costs for 1998 YTD were at Cdn. $9.38 per tonne and Cdn. $73.50 per ounce.Geology - (Orebody Description)The Snow Lake gold deposit is located within the Aphebian Flin Flon / Snow Lake Greenstone belt. This belt is composed of an assemblage of poly-deformed volcanosedimentary supercrustal sequences intruded by pre and sin tectonic ultra mafic and mafic intrusions and sin to post tectonic granitoid.The principal gold bearing rock at the New Britannia Mine is made up of quartzcarbonate material in sequence of basic and acidic volcanic rocks contained within a shear zone. The ore itself is gold associated with the sulphide mineral arsenopyrite and contains some pyrite, pyrotite, plus chalcopyrite. Proven and probable reserves at December 31, 1997 were at 4.04 million tonnes at 4.6 g/t and underground exploration continues to confirm the extension of the ore zones to depth."

Jan 1, 1999

By H. Zhu, Y. Sato, O. Takeda, K. Nakano

Recycling of rare earth magnet wastes is essential to insure the stable supply of rare earth resources. For the development of a novel recycling process, the removal of rare earth oxide from an off-spec alloy magnet was investigated by melting the alloy magnet at 1503 K together with fluoride flux, LiF-50 mol% NdF3 and LiF-?25 mol% NdF3-25 mol% DyF3. After melting, the separation of magnet alloy from the fluoride flux was achieved, and neither suspension of alloy in the flux nor suspension of flux in the alloy was observed. Oxygen concentration in the alloy decreased from 5000 mass-ppm to 160 mass-ppm by utilizing 1.5 times of equivalent amount of flux needed to completely dissolve the oxide. The investigated process is suitable for mildly contaminated waste such as a used (end-of-life) magnet because of its simplicity, low energy consumption and small limitation on location for operation.

Jan 1, 2014

By L. M. Gould

"Syncrude Canada operates the largest oil sands crude oil production facility in the world and produces over 13% of Canada’s total oil requirements. To achieve this, Syncrude mines the oil sands in open pits, extracts the raw oil known as bitumen from the sand using water-based processes and upgrades it into sweet light crude oil by fluid coking, hydroprocessing, hydrotreating and reblending. The final product, Syncrude Sweet Blend (SSB), is sent by pipeline to three Edmonton area refineries and then to pipeline terminals which ship the SSB to refineries in Canada and the United States.As parts of the Mildred Lake base mine reached their economic life, they were replaced with new facilities at the Aurora Satellite mine. Aurora is situated on Oilsand Leases 10, 12 and 34, 35 km northeast of the Mildred Lake facility (Fig. 1).In 2000, the first hydrotransport low-energy extraction production train started up at Aurora. A second production train is scheduled for start-up in 2003. Open pit mining at Aurora occurs using two hydraulic shovels, two cable shovels, and trucks ranging from 320-ton to 380-ton payload capacities (Fig. 2).Once the oil sands is excavated, the trucks dump the ore into a crusher designed to break up the big lumps of oil sands and rock at peak rates of 11 000 t/hr. The ore is then transferred by conveyor to a surge pile and then to a mixing box which combines the oil sands with hot water. Following bitumen separation in the primary separation vessel, froth is delivered to Mildred Lake for processing via the intersite pipeline (Fig. 3).The goal of this paper is to illustrate how high precision shovel GPS (HPGPS) is being used at the Aurora mine to aid in mine planning. This can be accomplished by first describing the function of the mine planning department, describing the Aurora orebody, and finally explaining how the HPGPS system functions and how it is employed at Aurora.The short range mine planning department ensures a steady supply of ore is delivered to the plant at the desired grade in a sequenced and economical manner. This is done by creating a mine plan that consists of shovel dig locations that require the shovels to mine in a specified area at a specified elevation."

Jan 1, 2002

By Robert Keyes, Charle Knowles, Glenn Kendall, Gary Fletcher

"The metal mining industry in Canada has been dramatically affected by the changes that have occurred in the world mineral market place. World economic restructuring in the post ""oil shock"" period of the mid-1970s, greatly increased competition from suppliers in the developing countries, and commodity price and currency pressures have all combined to severely test Canadian competitiveness. In the new mining world, the rate of growth of demand for metals has declined due to product downsizing, materials substitution, and a relatively slower growth of over-all world economic activity.The interplay of market and political factors is complex. Canadian metal mining companies must compete in world markets against low-cost producers in developing nations whose priorities often appear to be centred on maximizing foreign exchange earnings to foster development goals and debt repayment. Many of these countries have high levels of government intervention in their mining industries. The result is a greatly in-creased number of suppliers all vying for a share of a world demand growing at a relatively slower rate than in the past. To be able to compete under these circumstances, Canadian companies have had to undertake 'survival mode' measures and look to new ways of doing things. In order to identify the effects that the recent market and economic trends have had on the Canadian metal mining industry, a study was undertaken by Canada Employment and Immigration to assess these changes and their implications for the metal mining workforce.The Canadian Occupational Projection System (COPS)—Sector Study Group with the cooperation of the Mining Association of Canada, undertook a human resource survey to gather current employment and occupation information. This formed an important part of the Canadian Occupational Projection System Metal Mining Sector Study. This article addresses the with survey results, a C.E.I.C. worker mobility study, and trends and issues that are changing the mix of jobs and the way they are being done.Figure 1 shows metal mining employment for the period from 1974 to 1984. It provides a clear picture of the employment swings that the industry has experienced especially during the recession period of 1981 to 1983. From 1981 to 1983, employment dropped by 14 000, from 68 000 to 54 764, and then dropped to its lowest point in 1984 of 52 783. We feel that employment in the medium term will be flat with growth in gold mines being largely offset by continued workforce rationalizing in other sectors.Perhaps the key point is that equivalent levels of output have been achieved in the recent period (1981-1984) with a workforce that is 25% smaller than it was in 1974. This also raises the questions which the COPS/MAC survey and COPS mobility study sought to clarify, namely, what jobs have been cut and where have these people gone? Equally important are the questions of occupational skill level changes, and what types of jobs are declining and which ones are becoming increasingly important, as economic and technological changes have altered the mining work place."

Jan 1, 1987

By James A. Finch, Stéphanie Gélinas

"A colorimetric technique, originally developed for methyl iso butyl carbinol (MIBC) based on the Komarowsky reaction, has been extended to a wide range of common mineral flotation frothers. The procedure, which is briefly described, is shown suited to on-site determination in a series of industrial campaigns. Some frother observations are described, including: concentration evolution down a bank, distribution between pulp and froth phases, and a mass balance around a circuit. Minute amounts of frother in recycle water were also measured.The contribution of frother and alcohol by-products in the analysis was generally additive for plants using aliphatic alcohol type frothers and decoupled for systems using glycols. Typically, U250C (polyglycol) was used at higher concentration (>10 ppm) than MIBC (aliphatic alcohol) (<10 ppm) or F-150 (polyglycol) (<3ppm).The ability to monitor frother easily will help interpret gas dispersion behaviour and should permit further optimization of flotation cell hydrodynamics and chemistry. The capability to directly measure should help optimize the type, amount and location of frother addition, and to assess frother recycled with reclaim process water.INTRODUCTIONOwing to the lack of analytical methods, the task of determining frother concentration in plant flotation circuits is not routinely performed. Industrial sites seldom outsource analyses that are both costly and inconvenient, due to the necessity of shipping freeze-dried samples to remote testing facilities. A more direct colorimetric method has recently been demonstrated for the laboratory characterization of common industrial frothers (Gélinas and Finch, 2004). The approach, based on the Komarowsky reaction (Penniman et al., 1936; Coles et al., 1942; Duke, 1947), was previously described by Parkhomovski et al. (1976) for methyl iso butyl carbinol (MIBC). The reaction involves the interaction of the OH group of a higher alcohol, concentrated sulphuric acid, and salicylaldehyde, to yield coloured solutions with intensities that can be analyzed by UV-visible spectrophotometry."

Jan 1, 2007

By K. C. Viveros, R. R. Ambriz, C. García, F. De Villèle, A. Talha, D. Jaramillo

Cold hole expansion on base metal, weld metal and heat affected zone of 6061-T6 aluminum alloy welds was simulated by means of finite element method. Three dimensional compact test models with a previous fatigue crack length with a relation of ??= a/W = 0.3, were used to analyze the hole expansion process. Considering the local mechanical properties for each zone of the welded joint, the optimal expansion degree (1.64 to 2.46 %) was determined. The residual stress field, through thickness, after the expansion process in all welding zones, were correlated with the crack opening displacement obtained by finite element analysis. It was observed, that compressive residual stress fields for a post-expansion, in different crack lengths, provided a crack closure mechanism for base metal, weld metal and heat affected zone. Contrary, the crack remained open when residual stresses are positive. The results are given as tangential stresses versus distance from the edge of the cold expansion and crack opening displacement as a function of applied load.

Jan 1, 2014

By L. M. Lowe, D. G. Feasby, J. R. Goode

"Rare earth resources usually contain minor amounts of radioactive elements. The most widely recognised sources of radioactivity are associated with thorium and uranium. However, also present in the resources are isotopes of rare earth elements (REE) that are themselves radioactive, including lanthanum (La-138), lutetium (Lu-176) and samarium (Sm-147). These radioisotopes, as well as remnants of the natural thorium (Th-232) and uranium (U-238, U-235) decay series, can contribute to significant levels of radioactivity in mixed REE concentrates and in separated products. Levels such as these can present challenges for transport, transboundary movement, product storage, workers’ health and safety, as well as waste management issues at the facilities that separate out the individual REE’s. These are discussed in this paper. A particularly challenging radioactive isotope is Ac-227 (a decay product in the U-235 decay series). Actinium behaves chemically similar to lanthanides and hence normally concentrates with REE multi-element composites. Reliable analysis of Ac-227 is not widely available and the methodology required to deal with this challenge is briefly described. A principle reason for minimization of radioactive content throughout REE processing is restrictive specifications by concentrate purchasers in order to reduce waste management challenges. Approaches to the minimization of radioisotope content in REE concentrates and separated products are outlined in this paper."

Jan 1, 2014

By Donald Strickland, Peter Kresin, Dave Hall

"Have your parents or grandparents ever tried to share with you their wisdom and you ignored it because it did not relate to you‘? I have been ignorant and inevitably grew older and wished I had listened. The result: learning the hard way. As British Astronomer Fred Hoyle once said. “It is the true nature of mankind to learn from mistakes not from example.“ Hopefully we will continue to learn from the examples shared by our fellow mineral processors in these conference proceedings. It is the intent of this paper to share wisdom from the Musselwhite Mine that you may apply to your own operation.This paper is divided into three sections:1. Feasibility3. Operation3 . DesignKey points of the Feasibility and Design stages are summarized. followed by an analysis of actual operating statistics. An attempt is made to relate these statistics back to the feasibility and design with emphasis on areas of success and those with potential for improvement."

Jan 1, 1999

By Sergei Decterov, Peter Hayes, Evgueni Jak, Taufiq Hidayat, Denis Shishin

Copper smelter operations around the world are under sustained pressure to reduce costs and increase output. Through the provision of reliable data on fundamental properties of the chemical systems the opportunities for improvements of industrial copper production can be identified. Experimental and modelling studies on phase equilibria, thermodynamics of copper slag/matte/metal/gas systems have been combined into an integrated research program undertaken at PYROSEARCH. Experimental phase equilibria studies involve high temperature equilibration in controlled gas atmospheres, rapid quenching and direct measurement of compositions of equilibrium phases with electron probe X-ray microanalysis (EPMA). Thermodynamic databases development and modelling is undertaken using the computer package FactSage in conjunction with advanced models used for complex solution phases. Progressive development of these research methodologies has brought significant advances in characterisation of these complex systems, including a new optimised thermodynamic database for the copper-containing slag system Cu2O-Al2O3-CaO-FeO-Fe2O3-MgO-S-SiO2.The new data and models can now be applied to assist in improvements of the processes. The effects of changes to chemistry and process conditions within the smelting reactor can be examined. Several examples of new descriptions of the phase chemistry of the Cu2O-CaO-SiO2 and Cu2O-FeO-Fe2O3-SiO2 systems in equilibrium with metallic copper showing calculated and experimental data are presented.

Jan 1, 2014

By Takahiro Kubo, Katsunori Yamaguchi, Hidehiro Sekimoto

Equilibrium relation between B2O3 slag, RExOy-B2O3 (RE = rare earths) slag and Fe-C alloy formed by melting treatment of neodymium magnet and B2O3 was investigated. When neodymium magnet was melted together with B2O3 and Fe-C alloy in carbon crucible, 3 liquid phases of B2O3 slag, RExOy-B2O3 slag and molten Fe-C alloy formed and clearly separated by the difference of the specific gravities. In the case that excess amount of Cu was also introduced in that system, molten Cu phase additionally formed. Almost all amount of RE were concentrated in RExOy-B2O3 slag. The concentration of RE in RExOy-B2O3 slag increased with the decrease of the melting temperature. While chromium, phosphorous, nickel, cobalt, and copper were concentrated in molten Fe-C alloy, silicon and aluminum were distributed in B2O3 slag and RE2O3-B2O3 slag.

Jan 1, 2014

By Evelynn Stirling

Agenda ? Emissions legislation ? Cummins Tier 4 Technology ? Cummins Experience with Technology ? Operation and Maintenance Impact The Emissions Challenge ? The 2014/5 emissions regulations present the most significant challenge to our customer?s diesel powered equipment design and operation in recent history? ? ?and Cummins has the solution.

Aug 1, 2013

By I. M. London, G. P. Hatch

The Canadian Rare Earth Elements Network (CREEN) was formally launched at the Rare Earth Symposium at The Metallurgy and Materials Society of CIM (MetSoc) Conference of Metallurgists in October 2013. CREEN is an industry-led, multi-stakeholder network focused on providing collaborative solutions that will advance Canada’s REE sector to produce a significant proportion of the global production of separated critical rare earth products by 2018. The Network is industry driven by companies with REE projects under development and supported by universities, engineering firms, national and commercial laboratories, and government. CREEN aims to accelerate the development and delivery of timely solutions to technical and economic issues specifically facing Canada’s emerging rare earth sector. It will facilitate partnerships with other national and international organizations to leverage existing research initiatives. It will also support training and education to ensure that the needed qualified human resources are available to achieve the sector’s goals. CREEN membership spans the full rare earth supply chain and technical support organizations, from prospective producers, advanced project developers, national and commercial laboratories, engineering consultants, university researchers, and other innovators. This paper provides an update on CREEN&apos;s developing networking and project develop

Jan 1, 2014

By F. P. Hassani, H. B. Poorooshasb

"A kinematically admissible velocity field is applied to study the arching phenomenon in a cohesionless granular backfill placed between two rough vertical inflexible walls. The study is different from the previous works which are almost entirely based on statically admissible stress fields. It is shown that the development of arches is strongly influenced by the previous loading history of the backfill which controls the nature of the constitutive laws that govern the mode of stress deformation of the backfill. This preliminary study employs simple models in order to show the potential use of such an approach in evaluating and understanding mine backfill behaviour in the underground excavation. The pressure exerted on the floor supporting the backfill is also studied in some detail.INTRODUCTIONAlthough the importance of the design of mine backfill has been discussed extensively by a number of authors, i.e. Hassani et al. (1985), such theories have not as yet been incorporated in design criteria for underground mine backfilling operation . One factor that such theories must incorporate is the so-called arching action .The phenomenon of arching has been the subject of study by many researchers in the field of civil engineering and mining engineering. Among these scholars the works of Terzaghi (1943), Krynine (1945), Lusher and Hoeg (1964) and Handy (1985) are noteworthy. All these authors use a statically admissible stress field as a starting point to develop their theories. The approach taken by the authors of the present paper is completely different because they employ a kinematicallyadmissible velocity field. It is their belief that the arching phenomenon is closely linked to the interlocking of grains as manifested by the degree of dilatation of the granular mass when subjected to a shearing process.This paper is written in the following sequence. To define the interlocking quantitatively it is necessary to state the constitutive law governing the stress deformation characateristics of the granular mass. This is done in the next section as the law proposed by Poorooshasb and Pietruszazck (1985, 1986) is stated and simplified to suit the present analysis. Next the mode of formation of an arch in a simple system consisting of a mass of backfill sandwiched between two vertical rough walls of infinite extent is examined. The velocity field obtained from the above example is used to obtain solutions to two more complicated situations. The first situation assumes that the backfill is supported, in addition to the vertical rough walls, by a Winkler foundation at its base. The second situation assumes that the Winkler foundation has been replaced by a horizontal beam of uniform section and simply supported at its extremities. The findings of the study are summarized and their practical implications discussed in the concluding remarks."

Jan 1, 1989