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By J. Fellowes, V. Landais, J. Robson, J. Carr

"Aerospace Al-Zn-Mg-Cu (7xxx) alloys are known to be susceptible to environmentally assisted cracking (EAC). This phenomenon has been studied intensively for many decades, leading to empirically adopted methods to mitigate this problem through overaging and composition design. In parallel, many theories have been developed to explain EAC in 7xxx, but none is yet universally accepted. Today, a number of emerging techniques offer potential to shed new light on EAC in 7xxx. The purpose of the present paper is to demonstrate how X-ray tomography (XCT) combined with electron microscopy can be used to identify the true crack path in 3-dimensions, and hence identify material for site specific electron microscopy analysis. Composition mapping over large areas to high accuracy has been performed using a modern electron microprobe analysis system. This has been combined with transmission electron microscopy to investigate local composition in matrix and precipitates at high resolution. This combination of techniques across length scales offers the potential to provide new insights into the links between local composition, microstructure, and EAC resistance.INTRODUCTION Environmentally-assisted cracking (EAC) is a phenomenon which dramatically decreases the performance of metals and can cause premature failure of large structures. Observed in situations where components were not subjected to critical loads and no widespread corrosion was involved, this type of brittle failure is extremely difficult to predict. The EAC designation covers a number of phenomena, e.g. stress corrosion cracking (SCC), hydrogen embrittlement (HE), corrosion fatigue (CF), etc. Initially identified in steels, EAC can also affect other metals such as high-performance aerospace aluminium alloys, and this phenomenon has been a concern for industries for decades. Extensive research has been conducted on the effects of various environments (moist air, saline water, dry hydrogen gas, etc.) on microstructures and crack propagation, however no consensus has been reached and the exact nature of the mechanisms that control EAC is still being debated (Birnbaum & Sofronis, 1994; Gangloff, 2007; Holroyd & Scamans, 2013; Lynch, 2012; Oriani, 1972; Scamans, Alani & Swann, 1976, Young & Scully, 2002)."

Jan 1, 2018

By Barbara Kirby

Mining Industry Human Resource Council Who we are: National Sector Council for the Minerals and Metals Sector 18-person Board of Directors Over 100 Industry Volunteers PPP - Funded by HRSDC and industry What we do: Identify national HR challenges and opportunities for the Canadian mining industry Create national solutions through collaboration, partnerships and Synergy

Oct 1, 2010

By E. M. Timoshenko, A. V. Tarasov

The results of laboratory, bench-scale and semi-commercial investigations of a method for adding surfactant (technical-grade lignosulphonate) to the process of pressure leaching of nickel-containing pyrrhotite concentrates have been discussed. Lt has been demonstrated that feeding of technical-grade lignosulphonate distributed along the length of an autoclave ensures a reduction in its requirement by a factor of 1.5 to 2 as compared with single-point feeding; it also results in a decrease by 5% in the unit requirement of metallized iron-bearing precipitator in the process of non-ferrous metals precipitation and reduces by 0.05 to 0.1% (abs.) the nickel and copper contents in the tailings of the given process. Technical solutions have been proposed for commercial introduction of the process.

Jan 1, 2004

By A. Golpaygan

Application of Computational Fluid Dynamics (CFD) modeling for simulation of fluid flow and combustion in industrial scale electric furnace is presented. Poor combustion efficiency, roof and/or side wall overheating, carry over to off-gas system and non-ideal radiative heat transfer to processes or cooling systems have been common limiting factors causing inadequate process performance of the furnace, operational problems, and safety hazards. This paper describes how CFD analysis can be used to obtain a better understanding of commonly observed problems associated with freeboard combustion. Examples are presented to describe using combustion CFD modeling to understand requirements to diagnose a problem with furnace design including required freeboard volume or possible roof/side wall overheating.

Jan 1, 2011

By F. L. Casey

"Part 1 – Published Papers Baria, G., and Boshkov, S., ""Insights into Undercuttingin Block Caving"", Proc. 5th Rock Mech. Symp.,Mines Br. - Information Canada, 41-58, 1970.Barron, K., Coates, D. F., and Gyenge, M., ""ArtificialSupport of Rock Slopes'', Mines Branch ResearchReport R228, July, 1970.Barron, K., ""Criteria for Brittle Fracture Initiation inand Ultimate Failure of Rocks and Their Applicationto Fracture Zone Prediction"", Proc. 2ndCongr. Int. Soc. Rock Mech., Belgrade, 1970, 3-37.Bauer, A., and Calder, P. N., ""Projectile Penetration inRock"", Proc. 5th Rocle Mech. Symp., Mines Br. -Information Canada, 157-170, 1970.Bauer, A. M., ""Site Development and Rehabilitation ofPits and Quarries"", Canadian Mining Journal,Vol. 91, No. 7, 77, July, 1970."

Jan 1, 1971

By G. Bylapudi, K. Mondal, J. Hirschi

ABSTRACT: Rock bolts are the main form of defence against rock falls in mines. Conditions under-ground are conducive to corrosion. A perception exists about American coal mines that bolt corrosion is not an issue, especially when bolts are fully grouted. This perception is not necessarily accurate due to the formation of micro-cracks as the resin sets and to subsequent rock movement that breaks the resin column’s continuity. Corrosion should be considered when designing rock bolt support in long-term excavations. This paper explores the problem of corrosion, outlines a method to determine the corrosion potential of bolts, and suggests ways to mitigate such effects.

Jan 1, 2010

This paper presents the results of research aimed at proposing new solutions in the area of belt conveyor elements. Many factors, such as energy consumption costs, and operating costs of belt conveyor elements, including belts, idlers and drives have an impact on the operational costs of conveyors. The paper presents special tests of new materials for the bottom cover of an energy-saving belt conveyor, which decrease rolling resistance. It also presents large-scale in-situ tests of a high-output belt conveyor for the purpose of simultaneous measurements of various types of conveyor belts (standard vs several energysaving types) under typical operating conditions of a lignite surface mine. Improvements in materials used for the bottom belt covers, supported by specially developed comprehensive tests of the new types of belts have provided valuable results of various proposed solutions. Since the tests of belts were done at exactly the same time and in the same operating conditions, direct comparison of the results is valid and should lead to a substantial decrease in the conveyors? drives? energy consumption, which will improve the effectiveness of belt transport and minimize its negative influence on the environment.

Aug 1, 2013

By Michael Chender

Emerging Equity Sources ? Larger IPOs ? China Inc. ? Other sovereign wealth funds ? New funds and higher allocations ? Private equity

May 1, 2010

By Robert B. Parsons

"Ontario and Quebec taxpayers will have to dig deeper into their pockets to pay more tax, according to budget papers tabled in these provinces in May 1993. Individuals will be hardest hit, but corporations will also have to ante up in the face of higher rates, reduced deductions, and new taxes.Up, up, and away...Somewhere in the bleak picture of the 1993 Quebec and Ontario budgets, there is a bit of good news for the mining industry.Careful scrutiny reveals:• Ontario will correct a capital tax provision which inadvertently penalizes flow through share issuers;• Quebec's flow-through incentives will be extended to December 31, 1995; and • both Quebec and Ontario will allow deductions for mine site reclamation payments.The industry may also find some comfort in the fact that Ontario's new corporate minimum tax will be profit-based (unlike the federal minimum tax), so that non-producers should not face a liability for this tax. There is some concern though, about Quebec's announcement that the refundable credit mechanism in the Mining Duties Act will be reviewed."

Jan 1, 1993

There are many inherent risks in creating a mine plan for a new ore zone in an underground mine; one of such risks is the redistribution of stresses that could be a cause of instability. Using numerical modelling tools, it is possible to model the planned stope extraction sequence and evaluate the influence of mining induced stresses on the stability of remnant pillars, and use this information to remedy potential setbacks. This paper demonstrates this approach through a case study of the short-term mine plan of the Lapa mine of Agnico Eagle Mines Ltd., an underground gold mining operation near Val d?Or. Three-dimensional boundary element modelling is used to compute the stresses induced by the stope extraction sequence as planned with a longitudinal retreat mining method. The proposed methodology can be generalized to other mines that require an understanding of the stress concentrations at the pre-feasibility stage of mine design.

May 1, 2009

By Y. Chengxian

Many factors about the HIC (hydrogen-induced cracking) resistance of pipelines are discussed in this paper. The main factors that influence the ability of HIC are environmental and material factors. The chemical compositions, non-metal inclusions and microstructure are discussed in detail, while a group of tests on HIC resistance are done according to varying C, S, Mn and P contents in pipeline steels, different experiment time and different strength to the coupon. It is concluded that decreasing the amount of C and S can obtain good HIC resistance; the test time has an effect on the different microstructure of X70; microstructure is the most sensitive factor for the initiation processes of HIC.

Jan 1, 2005

By A. Darragh

"Past Growth The Canadian coal industry has grown rapidly during the past two decades. Coal production increased over four-fold between 1965 and 1982; consumption almost doubled, imports remained relatively flat, exports soared and total demand increased nearly two and a half times. Coal production grew during this period at an average rate of 8.60/o, compounded annually; this remarkable performance is shown in Table 1 and Figure 1. The relationship between production and consumption is shown in Figure 1, where in 1981 the total Canadian production of coal for the first time exceeded total Canadian consumption. ln Figure 2, the relationship between imports from the United States and Canadian coal exports is shown; in_ 1981 again for the first time, exports offshore exceeded imports into Canada. The rapid growth in Canadian coal use between 1965 and 1982 followed a major decline after World War II, as the country moved rapidly to an oil based economy. Changes in consumption patterns between 1945 and 1982 are shown ~n Table 2. Railway consumption of coal was reduced to zero m the early 1960s. The industrial and domestic consumers market share fell from about 660/o in 1960 to 6.70/o in 1975; this share, however, appears to have stabilized in recent years and actual volumes can be expected to increase in the future. The steel industry's share of the coal market fell over the same period, but the volume in recent years has remained fairly constant at about seven megatonnes per year.Perhaps the most significant change in consumption is in the share of coal consumed in the generation of electricity; this has increased from 80/o in 1960 to over three quarters of the total Canadian coal consumed in 1982. This increase in thermal coal consumption has been supplied by indigenous coal, and was accompanied by a decreasing share for coal imported from the U.S.A. into central Canada. It is expected, because of the nuclear power commitment in Ontario, that this share will continue to decrease, although the total volume of coal imported may increase slowly over time. This will likely also have a dampening effect on future coal sales to Ontario from western Canada."

Jan 1, 1985

By D. Kulchyski, R. Thibault, D. Lamoureux

"Mine tunneling applications are sensitive to the leakage and friction performance of ducting systems. Improvements in performance can help project economics through reduction in drift height, booster fan spacing, fan electrical power requirement, and deferral of ventilation raise construction. Semirigid plastic ducting has enjoyed significant adoption in mine tunneling in recent years. This paper explores technical properties and performance aspects of this relatively new material application.INTRODUCTIONUnderground mining projects are sensitive to mine development cost and schedule to meet first production—both of which are defined to a substantial extent by mine access construction. The very nature of mine access development requires driving accesses into new areas and even mechanized and automated tunneling methods require ventilation. Until underground airways are connected, allowing a flow-through circuit, ducted ventilation is required to establish ventilation within any single-access (i.e.: dead-end) heading. See Figure 1 as an example of ducted ventilation. Improving performance of ducted ventilation systems impacts project cost and schedule in several ways:For drifts whose height is defined by overhead clearance above haul trucks or tall equipment, smaller diameter ducting will decrease heading size.With higher ventilation flows, activities can be less ventilation-constricted; secondary headings can be worked without restriction, which improves schedule.Given the ability to provide more air for a given fan power, blasting gasses can clear the face and mine more quickly so crews can return to work more quickly - allowing higher advance rates.Lower electrical costs – both due to lower power consumed by fans and with the requirement for fewer electrical stations to power booster fans."

Jan 1, 2019

By Manqiu Xu, Songtao Yang, Zongfu Dai, Robert Pelton

Five years ago, VALE Base Metals (then INCO), approached Pelton's group at McMaster and described a challenging mineral separations problem. The McMaster group has a strong track record in colloids, polymers, and chemical additives for papermaking; however, they had no experience in mineral processing. They proposed employing hydrophobic nanoparticles to replace conventional low molecular weight, water-soluble flotation collectors. Over the last five years, Vale, together with the Ontario Government (OCE) have funded two graduate students at McMaster who have worked closely with flotation experts at Vale. Experiments involving both very clean model mineral suspensions at McMaster and complex ores at Vale, have shown that hydrophobic nanoparticles do indeed function as collectors. Key nanoparticle properties and mechanisms have been identified and the technology has been protected in patent applications. Efforts to commercialize the technology are on-going. We believe that this project is a good case study demonstrating the advantages of industry-university collaboration and the use of outside experts, who may come up with novel solutions to complex problems.

Jan 1, 2011

By Y. Chengxian, F. Yaorong, Xinzhe. L.

Many factors about the HIC (hydrogen-induced cracking) resistance of pipelines are discussed in this paper. The main factors that influence the ability of HIC are environmental and material factors. The chemical compositions, non-metal inclusions and microstructure are discussed in detail, while a group of tests on HIC resistance are done according to varying C, S, Mn and P contents in pipeline steels, different experiment time and different strength to the coupon. It is concluded that decreasing the amount of C and S can obtain good HIC resistance; the test time has an effect on the different microstructure of X70; microstructure is the most sensitive factor for the initiation processes of HIC.

Jan 1, 2005

By A. C. Munro

The concrete work on the new Britannia mill was started in April, 1922. The erection of steel commenced on July 10th, following. The installation of wood work and machinery , began on November 4th of the same year and was pushed to completion in January, 1923. The new mill building is an all steel structure enclosed with galvanized corrugated steel. All main floors and foundations are of reinforced concrete, which makes the building practically fireproof throughout. The mill building rises on a steep hillside to a vertical elevation of 210 feet and has seven distinct floors, for the various opera-tions. Only one elevator, with 30-foot centres, is used in the entire mill. The building is exceptionally roomy and well lighted, both by day and night. The capacity of the mill, as originally designed, was to be 2000 tons daily, but this tonnage can be readily increased to over 3000 tons daily by making slight changes in the fine grinding equipment; in fact, an average of 2700 tons per 24 hours was maintained throughout the month of September.

Jan 1, 1923

By Michael L. Free, Zongliang Zhang, Joshua M. Werner

In the copper electrowinning process, short-circuiting between the anodes and the cathodes is a critical problem that changes the current allocation among local electrodes and reduces the current efficiency significantly. Possible reasons for the short-circuiting include the improper alignment of the electrode, bent electrode, and nodules on the cathode surface. In typical tankhouses, there is often a time between shorting and harvesting as well as between shorting and clearing. Therefore, it is inevitable to have short-circuiting affect the operation performance in practical electrowinning operations. However, one key piece of missing data is the actual measurements of the current efficiency as short-circuiting is approached and allowed to continue. Consequently, short-circuiting tests that allow tracking of electrowinning parameters before and after short-circuiting were performed in a laboratory scale Cu electrowinning cell. In the tests, the electrode spacing change, the mass of electrodeposited Cu, the deposition morphology, and the current allocation as well as the current efficiency before and after short-circuiting were studied. Results show that the short- circuiting affects the current allocation and the current efficiency significantly. Moreover, it changes the Cu deposition on the short-circuited cathode and therefore causes problems for Cu electrowinning. INTRODUCTION Electrowinning (EW) is commonly used for copper production around the world, with a rated production from 120,000 to 200,000 tons per year per operation (Wiechmann, Aqueveque, Henríquez, Muñoz, & Morales, 2014). In Cu electrowinning, Cu ions in the electrolyte are reduced on the cathode surface as metallic copper with a DC current, while on the anode, a counter anodic reaction occurs with oxygen gas generation (Werner, Zeng, Free, Zhang, & Cho, 2018; Zhang, Werner, & Free, 2018; Zhang, Werner, & Free, 2018). In copper electrowinning, an average current density of 200 to 400 A/m2 is applied to the electrowinning cell (Wiechmann et al., 2014). As the Cu deposits on the cathode, the distance between anode and cathode reduces and most of the time, short-circuiting forms between some anodes and cathodes in a large tankhouse containing thousands of electrodes, reducing the current efficiency and increasing the energy consumption significantly. The current efficiency in well-run copper EW operations is typically above 90 %. Most of the unused current is wasted through short circuits, stray currents, and by-byproduct formation (Davenport, King, Schlesinger, & Biswas, 2002; Wiechmann, Vidal, Pagliero, & Gonzalez, 2002; Wiechmann, Morales, & Aqueveque, 2010). Usually, in the tankhouse, the short-circuiting increases the current in the involved cathode by up to 1500 A (Wiechmann et al., 2010). Multiple reasons can cause the short-circuiting in the cell, and the most common reasons include the uneven current distribution among cathodes, tilted electrodes, bent electrodes, and nodules formed due to the large deposition roughness. Recognition of this challenge in the Cu electrowinning process has led researchers to perform many investigations on approaches to avoid and reduce the short-circuiting in the cell. A series of research investigations have been conducted to develop and improve a new type of intercell bar for Cu electrowinning (Wiechmann et al., 2002; Wiechmann, Morales, Aqueveque, & Burgos, 2007; Wiechmann, Morales, & Aqueveque, 2009; Wiechmann et al., 2010; Wiechmann et al., 2014). The associated test results show that this new design limits the occurrence and magnitude of short circuits and allows operation at higher current densities. Sandoval, Clayton, Dominguez, Unger, and Robinson (2010) stated several keys to control short circuits, such as maintaining the straightness of the cathode, removing “edge hair” from the cathode starter, and maintaining electrode alignment in the cell. Prengaman and Siegmund (1999) from RSR technologies developed a new Pb-Ca-Sn anode to prevent the anode deformation, thereby reducing the short-circuiting in the Cu electrowinning cell. Although the negative effects of short-circuiting on the Cu electrowinning have been recognized, and various investigations have been conducted to address this issue, the actual measurements of the electrowinning behavior and performance as short-circuiting is approached and allowed to continue are seldom reported. However, in typical tankhouses, there is a time between when shorting occurs and harvesting/clearing are performed. One key factor in determining the harvest time is the frequency of shorting. Consequently, we have performed short-circuiting tests that allow us to track electrowinning parameters before and after short-circuiting.

Jan 1, 2019

By D. Farrish, W. A. Grell

"IntroductionMost base metal mines sell their concentrate to a custom smelter. The two parties concerned therefore draw up a contract which would detail the conditions under which concentrate sales will take place. The contract will identify treatment and marketing charges (including escalations), deductions for metal losses in the smelter, pricing formula, timing of payments, penalties for deleterious elements, etc.An understanding of the smelter contract is important to the mineral processor, for it will determine how he operates the plant to maximize economic return.Description of Contract ClausesUsing copper concentrate as an example, the smelter contract generally contains the following three basic charges:I. Metal Deductions- as the smelting process does not recover all the metal contained;2. A Smelting Charge- expressed per ton of material to cover costs on the bulk material such as receiving, unloading, thawing in winter, sampling, roasting to drive off sulphur, smelting through the matte and blister stages to recover mostof the copper and precious metals;3. A Refining Charge- expressed per pound of copper.The following is a review in some detail of a number of clauses which could be considered typical of a treatment and marketing type of copper concentrate sales contract. Most normal considerations in an agreement could be covered by the following types of clauses.Terminology- covers definitions, units of measurement to be used (e.g. short tons, troy ounces, etc.), currency (Canadian dollars). The term ""unit"" may be defined - l OJo of a ton of concentrate, e.g. one unit of copper means 20 pounds of copper per short ton of concentrate."

Jan 1, 1989

By Fathi Habashi

Poland has a unique copper industry. Copper sulphide concentrates are smelted in six shaft furnaces to produce matte and in a flash furnace directly to blister copper. Anodic slimes from electrorefining are treated by a modern technology to recover the precious metals. INTRODUCTION Poland's copper industry began in 1950 when the old and relatively small mines Lena and Konrad, located in Lower Silesia, were drained and recommenced production. In 1957 the industry entered a period of rapid development with the discovery of a rich ore body in the vicinity of Lubin and Polkowice which was the basis for the establishment, in 1961, of the Copper Mining and Smelting Combine (KGHM). In 1991 the Combine was restructured into a state-owned, joint-stock company under the new name of KGHM ?Polska Miedz? (KGHM ?Polish Copper?). It consists of three mines, three smelting and refining plants, and one rolling mill, and produces about 4% of the world?s copper and about 7% of the world?s silver.

May 1, 2001

By Mark Kennedy, Allan MacRae, Cameron Hams

New technology projects, particularly those involving first-of-a-kind metallurgical facilities, have a poor track record of achieving their overall financial targets, as they incorporate technological risks in addition to normal project risks. Traditional project management tools focus on risk from concept development through implementation, but typically fail to address the additional risks associated with a new technology project including slow start-up, slow ramp-up, and failure to achieve design performance (quality or throughput). These additional risks affect future cash flows produced by the project and hence its value, typically measured as net present value (NPV) or internal rate of return (IRR). Common accounting practice is to reduce the present value of future cash flows by applying a chosen discount rate, often reflecting the corporation's cost of capital. This discount rate does not contain an allowance for technological risk, which is often underestimated or misunderstood by both the financial and engineering project managers. This paper will focus on the topic of project risk and new technology, and how these play a role in the probability of achieving the predicted future cash flows. By properly addressing technological risk in the form of risk-weighted returns, marginal projects can be prevented from proceeding, while sound projects can be given the additional time and resources required to achieve the optimal level of front-end-loading (the level which returns the maximum risk-weighted net present value). A simple set of mathematical tools should enable engineers and financial professionals to establish a common level of understanding, thereby leading to a more accurate assessment whether a new technology project is ready to pass through its next level of approvals.

Jan 1, 2011