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By W. B. Xie

The hardening behaviour and microstructure evolution of Cu-30Ni-30Mn alloys aged at 350 °C has been investigated utilizing optical microscope, scanning electron microscope, transmission electron microscopy and Vickers hardness tester. The results show that the discontinuous precipitation of NiMn phase results in a remarkably hardening effect in Cu-30Ni-30Mn alloy during aging at 350 °C. The maximum hardness (~494HV) is attained in the sample after aged for 48 h. The NiMn precipitates are ordered and have a face-centered tetragonal structure. The coherent orientation relationship between the NiMn precipitates and Cu matrix is (220)Matrix // (220)P, [1-1-2]Matrix // [1-1-2]P. In addition, there is a linear relationship between hardness and volume fraction of the discontinuous precipitation, which indicates that the hardness increment of Cu-Ni-Mn alloys aged at 350 °C is attributed to the microstructure characteristics of discontinuous precipitation. The high strength of discontinuous precipitation colony is caused by the formation of nanoscale NiMn precipitates with a lamellar structure in discontinuous precipitation. INTRODUCTION Cu-Ni-Mn alloys are attractive candidates for oil drilling, aerospace and energy applications due to their high elasticity, high strength and excellent corrosion resistance (Sun et al., 2009; Liu, Yang, Xia, Jiang, & Gui, 2016). The high strength of the Cu-Ni-Mn alloys is mainly attributed to the precipitation of NiMn phase (Shapiro, Tyler, & Lanam, 1974; Xie et al., 2015). The uniformly dispersed nanoprecipitates formed by continuous precipitation can impede dislocation movement, and thereby lead to a significant improvement in strength of traditional precipitation-strengthened alloys. However, it is reported that there are two precipitation types observed in Cu-Ni-Mn alloys, namely, continuous precipitation and discontinuous precipitation (Shapiro et al., 1974). The discontinuous cellular colony with a lamellar structure nucleates at grain boundaries, and progressively grows inward the grain on the process of discontinuous precipitation (Ng, Bettles, & Muddle, 2011). It is found that the discontinuous precipitation can occur in many Cu-based alloys, such as Cu-Ni- Mn alloy (Shapiro et al., 1974), Cu-Be alloy (Monzen, Hasegawa, & Watanabe, 2010) and Cu-Ni-Sn alloy (Zhao, & Notis, 1998). Many studies consider that the discontinuous precipitation results in a detrimental effect on hardness and strength, and the discontinuous precipitation occurring during aging treatment should be suppressed (Markandeya, Nagarjuna, & Sarma, 2004; Semboshi, Sato, Iwase, & Takasugi, 2016). The mechanical properties can also be improved by discontinuous precipitation in AZ91 magnesium alloy (Tamura, Kida, Suzuki, & Soda, 2009) and AM30 magnesium alloy (Saikawa et al., 2012). Jun (2017) found that the reduced interlamellar spacing of precipitate fibers in discontinuous cellular colony leads to a significant increase in hardness. Indeed, the strengthening contribution of discontinuous precipitation is similar to that of continuous precipitation in Cu-20Ni-20Mn alloy. Discontinuous precipitation of NiMn phase can provide a significant strengthening effect in Cu-Ni-Mn alloys.

Jan 1, 2019

By Gustavo Brunello

Motor Failure Rates and Cost ? Motor failure rate is estimated: 3-5% per year. ? In Mining, Pulp and Paper industry failure rate is up to 12%. ? Sometimes process downtime costs are higher than motor ?? Motor failures are due: Electrical 32% Mechanical 31% Environmental 36%

Feb 1, 2008

THIS article describes the origin and details of a hydraulically operated switch to control the operation of an automatic underground pumping system. This system was installed in December, 1939, on the 2,350-foot level at No. 5 shaft of the Buffalo Ankerite mine. The pumping unit consists of an 8-stage centrifugal pump direct-connected to a 150 h .p., 2,200 volt motor. Pumping capacity is 200 gallons per minute under a 1,315-foot head and with a flooded suction. The control consists of a 200 amp., 2,200 volt oil-immersed starter with thermal overload protection, thermal protection on the pump, and a flow switch that is bypassed for 30 seconds after the pump starts. The 30-second time lag is operated by a relay mounted on the panel. There is a swing check valve in the discharge line of the pump which originally operated the flow switch by means of a connected outside lever which closed the switch as the check valve opened.

Jan 1, 1945

By Simon W. Houlding

The mining community is geographically remote and widely dispersed. There is a growing requirement for formalized professional development of members by professional associations, and increasing recognition of the advantages of continuing education and training by both individuals and corporations. Working against these trends are the increasing expense and time commitments required for attendance at conventional courses and workshops. The result is a perceived need for a readily accessible source of continuing education and technical reference on the Internet. The design constraints for an Internet model for professional development include: ? browser compatibility, with any time, any place, any pace accessibility; ? a content presentation model with low bandwidth requirements, appropriate interactivity for examples, tools and reviews, and viewer performance monitoring capabilities; ? formal accreditation of content, presentation and process so that viewer achievements may be formalized in terms of widely recognized Continuing Education Units; ? availability of tools for conversion of source material to the presentation format with minimal effort. A model that meets the design constraints is presented and illustrated by examples from an existing Internet site for continuing education in mining.

May 1, 2002

"In numerous meetings, conferences and discussions over the past year, the Conference Board of Canada has been impressed with the efforts of Canadian organizations to improve their competitive position. The attempt should be made to try to pull together and synthesize what has been heard. The topic of this paper, however, is even more daunting. The task is not only to analyze and discuss what is happening now, but also to look into the future—to the year 2000.The future seems to have an endless capacity for surprises, often unpleasant. This is one of the lessons learned in the twentieth century, particularly over the last 15 or so years.This paper covers three areas of managing in a changing com¬petitive environment: (1) the major global and domestic trends that will influence the ways in which Canadian organizations are managed (2) how Canadian companies are responding or will need to respond to these trends; and (3) the implications of the preced¬ing for human resource management and human resource professionals."

Jan 1, 1991

By Roger J. Higgins

Papua New Guinea is a country on the cusp of development, struggling to find a balance between the demands of national and regional growth, landowner expectations and the maintenance of cultural identity. Ok Tedi Mining Limited is the single largest contributor to PNG?s economy, representing about 10 percent of the country?s GDP. OTML is demonstrating that business and country risk can be managed through effective, respectful partnerships with local communities. OTML?s relationships with the communities of PNG?s Western Province are multifaceted. Communities have borne the brunt of the mine?s environmental impact, yet have benefited enormously from the development that the mine has brought. Importantly, the PNG economy is now the ultimate beneficiary of more than four-fifths of the dividends from the mine, the majority of which are held in trust for long-term sustainable development projects. The paper describes how OTML works with the Western Province communities to create a secure operating environment that recognizes the people?s aspirations for development and self-determination.

May 1, 2002

By P. R. A. Andrews

"The sillimanite group minerals, kyanite, sillimanite and andalusite are identified as alumino-silicate minerals with the common chemical composition AIP3.Si02' so that each possesses similar physical properties. Kyanite is the most abundant mineral and mainly occurs in Quebec, Ontario and British Columbia; sillimanite occurs in Ontario and Manitoba; and andalusite in Nova Scotia. The main use for the sillimanite-group minerals is in refractory applications for the production of refractory bricks and shapes. In refractory applications, the main performance criterion is the relative percentage of mullite formed within the material during firing. This phase gives a greater degree of resistance to creep deformation and slag attack, and improves the ability of the refractory to withstand high temperatures under load. The beneficiation of refractory silicate minerals has been the subject of many investigations at CANMET, and the former Mines Branch. Eighteen kyanite, two sillimanite, and three andalusite evaluation studies were conducted between 1933 and 1987. A review of some of the more important studies is presented, which includes information concerning mineralogy, beneficiation methods and flotation data."

Jan 1, 1995

By Andrew J. Neale, Brian C. Flintoff

"In most mineral processing operations the term ""audit"" is usually reserved for the exercise of checking financial records and/or safety practices. While these activities are time-consuming, no one disputes their necessity or value. If these areas are subjected to such careful scrutiny, why is it that the same principles are not normally applied to critically examine process operation. After all, the operating efficiency of the plant impacts directly on the measures of profitability.A mineral processing plant is a complex system that has a number of distinct, but mutually dependent elements: process equipment, instrumentation, operating policies, maintenance policies, control strategies and people. To ensure maximum economic performance in the dynamic environment that characterizes a concentrator, requires a periodic review of each of these areas. However, to be useful, the study must be based on sound metallurgical principles and be conducted in a highly focussed manner. Experience has shown that the exercise is very revealing and rewarding.This paper will discuss the plant audit process and illustrate its potential value through examples taken from plant studies."

Jan 1, 1992

By N. Schmitt, E. Blond, F. Hild

Working linings of steel ladles progressively damage during the steel manufacturing process due to both severe thermomechanical and chemical stresses. In the framework of the coupling scheme proposed by Blond et al. (1), this study examines the effects of the thermomechanical loading on the onset of microcracking by considering that the complex microstructure of the slag-impregnated brick is fixed during the steelmaking process. The behaviour of the refractory is identified by using thermoelastic-(asymmetric)viscoplastic constitutive equations. Numerical simulations of a simplified geometry of the lining subjected to cyclic thermal loadings at the inner side are shown. Two cases are analysed, namely, i) the material is a homogeneous continuum with a thermoelastic-(asymmetric)viscoplastic behaviour, ii) the material is porous and saturated by liquid slag, and the skeleton has the previous non-linear behaviour. The stress and strain fields are shown, and for the porous medium the interstitial pressure of slag as well. Comparisons between these assumptions are made to assess the role of slag on the degradation of the working lining.

Jan 1, 2004

By Carol E. Jones

?Reclaiming the land? in the Athabasca Oil Sands is becoming a household phrase in Canada. Advances in soil salvage and placement, increasing biodiversity of forest ecosystems and improved design of the landforms are beginning to change the trajectory of the ?reclaimed land? towards a boreal forest. The boreal forest is much more than just a forest; in the area of Fort McMurray AB, roughly one half of the boreal forest is composed of organic wetlands, often called muskeg. How important is muskeg to the boreal forest ecosystem and to the local aboriginal people? Should muskeg be reclaimed? Can muskeg be reclaimed? Ten years ago it was broadly accepted that organic wetlands could not be re-established; in fact this was so well accepted that reclamation of organic wetlands had not been attempted. Over the past decade this conclusion has been re-evaluated and research projects have been undertaken to examine the potential to create organic wetlands in a reclaimed oil sands landscape. This paper examines these questions and the research initiatives necessary to reclaim the other half of the Athabasca Oil Sands.

May 1, 2011

By G. B. Harris

A new process for the recovery of copper and associated base metals from a polymetallic massive sulphide ore is described. The massive sulphide contains copper and especially nickel sulphide in a mineralogical form which negates both good recovery and high grades in concentrates using conventional flotation methods. Flotation concentrate processing and smelting from this ore is therefore probably not an economically viable option. Utilising the properties of high concentration chloride brines, a flow sheet has been developed and tested whereby the recovery of all of the metals and some of the power requirements for the plant itself can be derived from the ore. The new process overcomes the less-amenable-to-flotation ore characteristics, and provides the opportunity of economic processing in remote locations where the dependency on fossil fuels is both a logistical and an economic concern. The Ferguson Lake deposit of Starfield Resources in Nunavut, Canada, is the subject of this paper, which focuses on the leaching and copper recovery unit operations of the proposed flow sheet.

Jan 1, 2007

Aur Resources is Canada's leading copper mining company with producing mines and development projects in North, Central and South America. Copper production from Louvicourt Mine in Quebec, Quebrada Blanca and Andacollo Mines in Chile was a record 245 million pounds in 2001. Located 600 km North of Montreal, Louvicourt Mine is a joint venture between Aur Resources (30%), Novicourt Inc (45%) and Teck-Cominco (25%). Aur Resources is the mine operator with 280 employees working to produce a copper and zinc concentrate. In operation since 1994, the mine has produced a total of 12,606,000 metric tonnes of ore grading 3.6% Cu, 1.5% Zn, 26 gr./m.t. Ag and 0.9 gr./m.t. Au. This highly mechanized mine reached full production in August 1995 at 4,000 tpd. From 1996 to 2001, the average mine production rate was more than 4,300 tpd. The Louvicourt Mine continued its record of solid performance in 2002 and is expected to continue to do so for the balance of its 2.5 years mine life.

May 1, 2003

By D. Seke, E. Katsande, R. Khumalo, K. Seerane

Palabora Mining Company (PMC) processes a multi-component ore body using a circuit consisting of two AG mills in parallel, closed with vibrating double deck screens and hydrocyclones. The bottom screen undersize feeds the hydrocyclones, but the screen oversize products can be treated in a variety of ways. The top deck screen pebbles can be crushed and then combined with the bottom deck oversize and recycled to the AG mill. Alternatively both the top and bottom deck screen oversize can by-pass the recycle crusher and be recycled directly to the mill. A full tap-off is a configuration when both the top and bottom deck screen oversize streams are stockpiled. The other configuration is when the bottom deck screen oversize is recycled to the mill while the top deck screen oversize is stockpiled - termed partial tap-off. This article reports the findings from the surveys performed to evaluate the performance of the PMC auto mill circuit when operated under the four different configurations discussed. Ore characterisation tests were performed to assess the deportment of the key ore components for the different configuration.

Jan 1, 2012

By P. R. A. Andrews

"Garnet occurs in schists and gneisses in all provinces of Canada, all mainly in Quebec and Ontario. There is currently a renewed interest in exploration for economic sources of garnet for abrasive applications because of the inherent dangers from exposure to ground silica from sandblasting operations.High-quality garnet is used for lapping and grinding of glass and ceramics; for coated and bonded products such as sandpaper and cloth; and abrasive wheels for grinding and finishing various metals, woods, rubber and plastics. Low-quality garnet is used for cleaning and conditioning aluminum and other soft mewls, particularly by aircraft manufactures. Garnet may be added to grouting cements for oil-well drilling applications, and it has also been used for low- to medium-level radiation shielding. Garnet has been studied extensively by CANMET and its predecessor, Mines Branch, between 1917 and 1990. Twenty-nine studies relating 10 various aspects of beneficiation are presented and a review of the more important studies is presented. The information includes mineralogy, beneficiation methods, product sizes and analyses."

Jan 1, 1995

By Christina Graf

A synthesis of colloidal gold shell particles with a silica core is described. Small gold nanoclusters were attached to the functionalized surface of colloidal silica particles. Reductive growth and coalescence of these clusters lead to the formation of a closed gold layer. By variation of the thickness of this gold layer and the radius of the shell it is possible to adjust the plasmon resonance of the gold shell particles over the whole visible and infrared region of the spectrum. The optical properties of the particles made are in good agreement with theoretical calculations for coreshell particles. Due to their low polydispersity these gold shell particles form in solution large crystals with submicron lattice constants. It is also possible to produce hollow gold shells by dissolution of the silica core. A new method to coat the silica core gold shell particles with an additional outer silica shell is also presented. This allows due to a reduction in the Van-der-Waals forces to make more permanent dried crystals and facilitates functionalization of the particles for use in various photonic applications.

Oct 1, 2003

By T. Saksala

In this paper, the embedded discontinuity approach is applied to finite element modeling of rock fracture. A rate-dependent constitutive model based on the embedded displacement discontinuity theory is developed to describe the mode I, mode II and mixed mode fracture of rock in tension and compression. The bulk material is described as linear elastic until reaching the elastic limit. Beyond this limit, a ratedependent exponential softening law governs the evolution of the embedded displacement jump. The present approach incorporates the rock heterogeneity by random description of the mineral texture of rock. Moreover, the inherent initial microcrack populations of natural rocks are accounted for as randomly oriented embedded discontinuities. Numerical examples demonstrate the model behavior in uniaxial compression and tension. The effect of loading rate and confining pressure is tested as well in 2D numerical simulations. These simulations show that the model captures the main features of rock in confined compression and uniaxial tension. The developed method has the computational efficiency of continuum plasticity models. However, it has an important advantage of accounting for the orientation of introduced microcracks.

Jan 1, 2015

By J. T. Vehkala, S. S. Kerr, D. E. Robertson

"Since the late 1970s, extensive work has been carried out at Placer Dome Inc. 's Dome Mine to develop new mining methods and equipment to improve the productivity of narrow vein mining (Mining Magazine, Oct. 1986, pp. 308-317; Mar. 1988, pp. 176-/79). This work has been focused on mining veintype deposits varying from 0.9 m to 1.5 m in width using open stoping and cut-and-fill mining methods.In 1989, the Dome Mine entered into a contract with Ram Raising Ltd., a joint venture company of Angus Martin and I.S. Redpath Ltd., to develop and mine a narrow vein test stope using an Alimak Raise Climber. Early results have been favourable, indicating that Alimak methods can be used successfully to mine narrow vein are.HistoryThe Dome Mine, which has been in continuous operation since 1910, is located in South Porcupine, part of the city of Timmins, Ontario. The mine is wholly-owned and operated by Placer Dome Inc. and is part of Placer Dome Inc.'s international stable of of 19 mines."

Jan 1, 1990

By William Petruk

Mineralogical investigations in connection with gold metallurgy are usually performed to find the reason for poor recoveries by cyanidation or by other leaching techniques. Poor recoveries most commonly are obtained when (I) native gold is encapsulated in an insoluble mineral as "invisible gold"; (2) native gold is coated with a precipitate; (3) gold-bearing products are insoluble in cyanide solutions; (4) carbonaceous material in the ore adsorbs gold; and (5) associated minerals decompose and consume cyanide. Samples of refractory material quite often have low gold tenors. It is difficult to find the gold-bearing minerals in such samples with an optical microscope because the probability of finding trace minerals in samples is small. The probability decreases with decreasing grain size of the gold-bearing mineral and with decreas¬ing gold tenor of the sample. Techniques have been developed to increase the success rate of finding gold grains; some are (1) concentrating heavy minerals; (2) preparing special polished sections; (3) searching with an image analyzer; and (4) dissolving associate silicate and sulphide minerals.

Jan 1, 1989

By G. J. Hutchins

Precision surface mining is gaining traction in the iron ore, copper, iodine, limestone, bauxite, coal and gypsum markets. In this paper, we first address the possible improvements of a surface miner control using GPS techniques. An application in an iron ore mine in Western Australia is presented. The second item addressed is improvements of a new drum driving technique for a 100 ton surface miner. This technique involves installing a slow speed hydrostatic motor directly on the cutting drum rather than driving the drum through chain and sprockets. Details of the performance of this direct-drive versus the chain-drive are detailed. In addition to the 100 ton machine, we also present a 200 ton surface miner. This larger machine has 1600 hp (894.8 kg), and has been successfully introduced into a large iron ore mine in Western Australia. Performance of the 200 ton surface mining machine in various rock hardnesses is detailed. Some comments on the cost effectiveness of using a built-in loader versus loading with wheel loaders are included.

Aug 1, 2013

By Robert B. Parsons

"Finance Minister Paul Martin's second budget might be good for Canada's mining industry in the long run, but the budget raises a number of concerns for the industry in the near term. The budget papers suggest that the 25% resource allowance is not working as intended, and report that the Department of Finance will be reviewing this valuable allowance. The so-called ""large corporations tax"" rate will be increased. This annual tax, which is imposed on a corporation's capital even when the corporation is not in production, is particularly harmful to the mining sector.IntroductionThe Honourable Paul Martin, in his second federal budget, emphasized spending cuts and made only modest tax changes. However, two of these tax changes could have a serious impact on the Canadian mining industry: the proposed review of the 25% resource allowance; and, the increase in the large corporations tax rate.Personal Tax Measures Personal Tax Rates UnchangedThe government has been under political pressure not to increase personal tax rates. Mr. Martin's announcement that rates would not change will be popular."

Jan 1, 1995