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By K. M. Mayhew, G. D. Barr, T. M. McCoy, C. T. Knilans

"Teck Resources Limited (“Teck”) has developed and extensively tested on a continuous basis the CESL Technology hydrometallurgical process for treating copper and nickel sulphide concentrates, including bulk copper-nickel concentrates. Copper, nickel and cobalt are leached efficiently into solution, utilizing CESL process conditions. Total precious metals including gold, silver, platinum and palladium are recovered from the residue stream via sulphur flotation. This paper describes the CESL Technology testwork on a bulk copper-nickel concentrate derived from Twin Metals Minnesota?s (TMM) deposits within the Duluth complex and evaluates the economic benefits (increased cash flow, increased revenue certainty) and investment criteria (capital cost, payback and cash flow) of incorporating CESL Technology into the staged development of TMM?s deposits.INTRODUCTION Mineral Processing and the Role of Hydromet in the Duluth Complex The Duluth Complex in northern Minnesota, United States (US), represents one of the largest undeveloped accumulations of copper, nickel, gold, and platinum group metals (PGMs) in the world, ranking second in copper and PMs and third in accumulation of nickel. The figure below identifies some of the larger known deposits within the Complex (see Figure 1). Copper, nickel, PM and PGM mineralization within the Duluth Complex is hosted by mafic to ultramafic intrusive rocks that are part of the overall intrusive complex.One of the mineral processing challenges of Cu-Ni-PM-PGM deposits in this Complex is the complicated, polymetallic nature of the mineralization1: copper occurs primarily as chalcopyrite and cubanite with minor occurrence of talnakhite; nickel occurs as pentlandite and refractory nickel oxide/silicates; iron sulphides are present as both pyrrhotite and troilite; and PMs/PGMs occur in both the sulphide matrix as well as discrete minerals. An additional challenge for the Duluth Complex is the ratio between copper and nickel; in most of the identified deposits, copper grade is three to four times greater than the nickel grade, which precludes the production of a simple bulk concentrate due to the lack of a traditional smelting market for a bulk concentrate of this character."

Jan 1, 2017

By J. H. Walsh

IN THE DEVELOPMENT of procedures for the separation of minerals, the choice of reagents for flotation is frequently determined by the extent to which a given mineral is wettable by water. Measurements of the contact angle of an air bubble on wet mineral surfaces are often used in the laboratory to estimate the wettability of the surface. For the results of these measurements to be reproducible, the surface of the mineral must be polished to a mirror-like smoothness and must be free from oily contamination. Elaborate procedures for preparing mineral surfaces have been developed by Wark ( 1) and Taggart (2), and these procedures have been generally accepted as adequate for their purpose. The polishing techniques, how-ever, have certain inherent disadvantages which make it impossible to assess the effects of polishing, entrained abrasive, and adsorbed gases on the wettability of the mineral surface.

Jan 1, 1957

By Lin-fang Shen, Shao-jun Li, Zhi-liang Wang

"The meso-structure of real soil consists of numerous particles with different sizes, while the traditional reconstruction method of quartet structure generation set (QSGS) produce relatively uniform soil particles resulting in significant discrepancy between the actual structure and reconfiguration model. In order to remedy the deficiency, the QSGS is improved by considering the influence of porosity and autocorrelative function of soil, which make the models closer to the real soil. Based on the reconfiguration model, Lattice Boltzmann method is combined in the algorithm to conduct further simulation of fluid flow in soil pores. The D2Q9 model is applied to construct the two dimensional model for simulating mesoscopic seepage field of saturated soil by setting the non-equilibrium extrapolation scheme at the inlet and outlet boundary, and the bounce-back scheme at the soil particles boundary as well as the left and right boundary. According to the case study, the proposed program is realized to simulate mesoscopic seepage field of reconstructed soil with constant inlet seepage velocity. The results show that the seepage direction of soil is along the passage with good connectivity, therefore the permeability is controlled by these passages. The seepage velocity in such channels is faster than in bad connectivity channels. Even if the channel has larger pores, the seepage velocity is still small. INTRODUCTIONUnderstanding the seepage mechanism in porous materials is significant in both theoretical and engineering problems. As a typical porous media, soil consists of solid particles and voids, which form connected channels allowing water to flow through. Such seepage in soil exists widely among geotechnical project of slope, foundation pit, and tunnel, etc. Meanwhile, a number of engineering accidents are caused by limited knowledge of seepage characters in soil (Huang, 2006; Liu, 2013). The conventional method in describing seepage features mostly based on the parameter of permeability, which is a macro statistic mean evaluating the whole connectivity of soil. Obviously, this parameter cannot exactly reflect the details of how water flows through the inner soil structure, especially the flow velocity in local mesoscopic area, hence is unable to represent the actual seepage properties. Therefore, it is necessary to develop mesoscopic approaches to fully study the seepage mechanisms."

Jan 1, 2015

By J. Girard, V. Aubé, M. Barakate, S. Bellec, M. R. Eddahabi, Y. Chaik, M. Deshaies

"The activated carbon used in the carbon-in-leach (CIL) process to absorb gold is subject to breakage. This carbon breakage can be minimized, but it will always be necessary to deal with fine carbon particles, known as carbon fines. These fines contain a significant amount of gold and mining operations generally struggle with the treatment of this product. Since IAMGOLD’s Essakane mine is located in Burkina Faso, shipping carbon fines out of the country was not considered a viable solution due to the logistical burden and legal procedures in place. A benchmarking study demonstrated the complexity of treating carbon fines on site. IAMGOLD partnered with the host government to find an innovative approach to economically recover the gold locked in these fines. This paper describes the new circuits commissioned in July 2016 built to improve carbon fines collection, incinerate the carbon fines and leach the gold in the ashes produced by incineration. These new circuits successfully demonstrate that it is possible to extract more than 94% of the gold content in the carbon fines. This is profitable for the company as it improves the overall mill recovery rate by 1.0% to 1.5% and significantly decreases gold inventory build-up on site.INTRODUCTION The activated carbon used in the carbon-in-leach (CIL) to absorb gold is subject to breakage. This breakage can occur in the CIL tanks, the stripping circuit, the regeneration process or anywhere throughout the pumping and handling processes of carbon through the circuit. Fine carbon particles are invariably created and, because of their small size, present a large specific surface which favors gold absorption (Hilsher et al., 2014). At the very beginning of operations at Essakane, the carbon fines were recovered by means of a thickener and a filter press, but the circuit was undersized and inefficient. Subsequently, a decantation basin was used to settle the fines before the thickener. The settled fines were shovelled from the basin into bags. All these bags were stored in the backyard of the plant. The average tonnage of carbon fines recovered monthly was 23.5 tons with a gold grade at 1938 g/t."

Jan 1, 2017

By Fidelis T. Suorineni

The conditions for rockburst occurrence are traditionally identified as: high stress, high extraction ratio, strong brittle rocks, folding, faulting, and unfavourable excavation geometry. Based on a critical review of case histories, this paper identifies oblique loading of orebodies by the major far field principal stress as a cause of rockbursts. Orebodies subjected to this loading condition are termed orebodies in shear. Orebodies in shear are subjected to compressive and shear loads. The case histories presented unambiguously show that the magnitudes of the far field principal stress alone, and a knowledge of the conventional rockburst causing factors are not sufficient for mine planning and design. The orientation of the major far field principal stress, or for that matter the driving stress relative to the orebody axis, should be recognised as one of the causes of rockbursts. It is suggested that since stress orientation is an important factor, and orientations from stress measurements are so variable, orientations from stress measurement data be complemented with underground observations from borehole and excavation breakouts to determine the actual in situ stress orientation, whenever possible. Also stress modelling for the design of critical elements (pillars) should include a sensitivity analysis on the relative critical field stress direction. The paper emphasises that special attention should be paid to or

Jun 1, 2012

By A. F. Abd El-Rehim

The behavior of both transient and steady state creep of Al-4.5 wt% Cu and Al-4.5 wt% Cu-0.1 wt% In alloys was investigated using a constant stress where torsional oscillations of different frequencies and shear strain amplitudes were operated at various working temperatures. An augment in both transient and steady state creep rates was observed by increasing both frequency and shear strain amplitude of the applied oscillations. The mean values of the activation energy of both alloys for both creep stages were found to be equal to that quoted for dislocation intersection mechanism.

Jan 1, 2006

By J. R. Parga T., P. J. Valenzuela G., L. S. Quiroz C., P. Guerrero G., J. L. Valenzuela G.

"Pressure oxidation is a hydrometallurgical pre-treatment process used for refractory auriferous sulfide ores. In the work reported here, a refractory pyrite ore sample from the Mulatos mine, Sonora, Mexico was characterized. The sample was subjected to atmospheric cyanidation, and simultaneous pressure oxidation and cyanidation under different conditions of temperature and pressure. The mineral characterization showed that pyrite is the main species in the sample. The gold extraction tests were carried out in an 1-litre Parr pressure vessel at a temperature range of 90-120 °C, a pressure range of 87.5–150 psi (using oxygen), and a cyanide concentration range of 0.8-1.2 %wt. The gold extraction results showed that diffusion through product layer is the rate controlling step.INTRODUCTIONIn hydrometallurgical precious metals extraction, the most commonly used process is sodium cyanide leaching, as shown in the next reactions involving gold and silver (Fleming, 1992; Marsden & House, 2006):4Au(s) + 8CN- (aq) + 2H2O(l) + O2(g) ? 4Au(CN)2 -(aq) + 4OH- (aq) (1)4Ag(s) + 8CN- (aq) + 2H2O(l) + O2(g) ? 4Ag(CN)2 (aq) + 4OH- (aq) (2)“Refractory” auriferous ores or concentrates often contain gold and silver locked inside other sulfide phases such as pyrite. This renders cyanidation ineffective, so oxidative pre-treatments are used in order to convert the sulfide minerals into porous oxide minerals and make cyanidation work more efficiently. Reaction (3) shows the oxidation of pyrite in alkaline media and the formation of the porous oxide (Koslides & Ciminelli, 1992):2FeS2 (s) + 15/2 O2 (g) + 8H- (aq) ? Fe2O3 (s) + 4SO4 2- (aq) +4H2O(l) (3)A process of simultaneous chemical pressure oxidation and cyanide leaching for a flotation concentrate produced in the mine of Bacís, Durango, in Mexico, gave good results (Parga et al., 2007). In the study presented here, it was intended to use this treatment for a refractory pyrite mineral from the Mulatos mine in Sahuaripa, Sonora, Mexico, modifying variables such as pressure, temperature and cyanide concentration to find the best conditions for oxidation and leaching."

Jan 1, 2012

By K. E. Waters, E. R. L. Espiritu, G. R. da Silva

"Rare earth (RE) elements are essential components of emerging green technologies. The increase in demand for these applications have driven the search and development of new rare earth deposits such as the Niobec project in Quebec, Canada. This deposit consists primarily of dolomite with significant amount of RE minerals bastnäsite and monazite, the primary sources of RE elements. Due to the minerals’ fine liberation sizes, flotation is commonly used as a concentration method. To develop an efficient process, the electrokinetic properties of the minerals must be understood. In this study, the surface properties of bastnäsite, monazite (RE minerals) and dolomite (a common gangue mineral) were investigated by zeta potential measurements. These measurements are affected by various ions present in solution; for bastnäsite, monazite and dolomite, some of these ions are H+, OH-, PO43- and CO32-. Dolomite, being a sparingly soluble mineral and a primary component of the ore, may be the greatest contributor of these ions in solution in the form of CO32- ions. Thus, different sources of CO32- ions (from dolomite dissolution and from Na2CO3) were investigated. The research work aims at elucidating how these reagents may influence the minerals’ surfaces. The results have shown that dolomite supernatant and sodium carbonate greatly affect the electrokinetic properties of each minerals. The addition of dolomite supernatant have resulted to relatively similar zeta potential of the minerals; while, sodium carbonate have affected them differently. These observations could be useful in efficient flotation of bastnäsite and/or monazite from bastnäsite-monazite-dolomite system.INTRODUCTIONThe increase in the demand for rare earth (RE) elements has driven the search and development of new deposits. Out of 53 rare earth projects in the world, 19 can be found in Canada (Hatch, 2015). These include the Niobec project of Magris Resources Company in Quebec. This deposit contains a significant amount of rare earth minerals (such as bastnäsite and monazite), with carbonates (such as dolomite) as the primary gangue minerals."

Jan 1, 2016

By R. F. Robertson

"Adsorption isotherms of hexyl mercaptan vapour on synthetic sphalerite, zinc sulphide and zinc oxide were de-termined with a gravimetric McBain-Baker micro balance incorporated in the B.E.T. apparatus. Isotherms are given for hexyl mercaptan on synthetic sphalerite at 25°C, 0.5°C and 50°C; on zinc sulphide at 25°C and 1.5°C; and on zinc oxide at 25°C. All these isotherms are sigmoidal, with a definite change in slope at or close to the mono-layer. The amount of mercaptan adsorbed below the monolayer increases almost linearly with relative pressure to P/P0 = 0.8.Above this value, the amount adsorbed increases very rapidly with relative pressure. Hysteresis loops appear in the isotherms for all adsorption-desorption cycles. These loops are completely reversible. It is not possible to desorb the mercaptan monolayer from any of the adsorbents, even at elevated temperatures."

Jan 1, 1966

By H. J. Oterdoom

SMS Group (SMSG) has always been concerned about safety aspects of electric smelter plants for the ferro-alloy and non-ferrous industry. The awareness for safety increased significantly over the past decades and also SMSG contributed with its design features to a safer operation. Today, safety aspects are not only part of the smelter design but also of the overall plant layout. Explosions in electric smelters are rare, but have a huge impact on peoples’ lives, on equipment and on production. For this reason, SMSG wanted to have a better overview of explosions within the smelting industry in order to see if useful statistics could be extracted. Generally, there is a lack of statistics regarding explosions in the electric smelting industry, and not enough information is collected or published. A significant portion of the explosions seems to be water related. Many companies, both operating and engineering, are trying to handle the risks of water, and apply methods to detect water leakages. Installing such a system is a management decision and management has then to make sure the system is properly implemented. The disadvantages and limitations of these systems should be carefully considered and communicated to operators and authorities.

Jan 1, 2015

By T. B. Williams

Most geologists have felt the need of a longer base than is ordinarily available when using a Brunton compass or other convenient instrument for taking strikes and dips in the field. To overcome this difficulty a lath or stick with straight parallel sides is frequently used. This accessory adds to the accuracy of the work, but it is a decidedly inconvenient one for the geologist to carry, especially if he be heavily loaded or is travelling on horse-back or through thick brush on foot. The writer has abandoned its use in favour of a sturdy two-foot carpenter's rule. The rule preferred is manufactured by J. Rabone and Sons, Birmingham, England. It is provided with a good level-bubble set in one of the limbs, and a scale, of the protractor type, graduated to five degrees through 180 degrees, attached to the main joint at the middle of the rule. (See Figure 1). For an instrument of its kind it is very accurate, and, in addition to the uses mentioned below, it 'is a handy thing to have around any camp. It is frequently used when plotting roughly in the field and for a protractor when one is not available. When not in use it may readily be carried in the top of the high-boot or legging. Ordinary strikes are measured as illustrated in Figure 1, the compass being held against the rule, which is in a horizontal position. Dips may be measured in a corresponding way by holding the Brunton compass against the extended rule, which is thus used merely as a straight edge. It is usually much more convenient, however, to ? use the rule only for this purpose, in which case one foot of the length rests as a straight-edge against the rock surface. This adaption is shown in Figure 2.

Jan 1, 1929

By K Morrison

Different individuals have calculated the boundary stresses around elliptical openings in an infinite elastic medium for various conditions of loading. With caution, such calculations are useful in indicating stress trends in mining. This paper illustrates an application to caving operations and suggests that abnormal field stress would have an adverse effect. Introduction GELDART and Udd (1), applying elastic theory, confirmed, and set out graphically, the stress distributions on the surface of elliptical openings with axis ratios varying from 1.0 (a circle) to infinity (a crack). The loading conditions varied from uniaxial to hydrostatic, and inclinations for the opening, with respect to the stress axis, varied from 0° to 90°. As most mine openings can be generalized into this elliptical conception, the usefulness of the presentation lies in the fact that given reasonable estimates for the stress ratio, the axis ratio, and its inclination, then the trend in stress concentrations as an opening develops can be readily approximated.

Jan 1, 1964

By N. Bakhshizadeh

In this investigation, the aging effect on creep behavior of A12024-10%SiC composite fabricated by powder metallurgy was studied. P/M bars were manufactured by hot powder extrusion method at 450°C with a ratio of 16 to 1. Creep specimens were over-aged at 187 ºC for 43 h. It was found that almost full density composite with relatively homogenous distribution of reinforcing particles throughout the aluminum alloy matrix could be attained by direct powder extrusion process. Creep tests were conducted at temperatures from 275 to 325°C under stresses from 25 to 60 MPa. The analysis of the creep mechanism determined that dislocation glide was the predominant mechanism of plastic deformation. The activation energy of the creep process was found to be higher than that of lattice self-diffusion in pure aluminum.

Jan 1, 2007

By W. Hardtke, B. Perry

Model reconciliation problems at the low-grade, high-nugget Phoenix gold-copper deposit led to an examination of the influence of production decisions on ore-waste classification. A conditional simulation study of the deposit was used as the basis for: 1) quantification of dilution at different bench heights, 2) quantification of ore-waste misclassification relative to bench heights and cut-off wades, and 3) determination of an appropriate number of samples to optimize ore-control polygon definition. Actual reconciliation data were empirically used to support conclusions. Simulations of both gold and copper were combined through net revenue modelling. These simulations increased understanding of the nature of the deposit and provided insight for resource modeling and mine planning.

Jan 1, 2011

By T. Plikas, T. Porretta, M. Al-Dojayli, B. Pretorius, J. Woloshyn, H. Ghorbani

"Water-cooled ducts represent an integral part of high temperature off-gas systems in metallurgical processes. Typically, off-gas enters these ducts at significantly elevated temperatures; therefore, water cooling may be required to maintain the duct skin temperature within allowable design limits. These off-gases are typically of high mineral content that could lead to dust buildup, and there is a possibility of slag buildup / molten metal splashing. Therefore, dust cleaning provisions may be necessary in order to remove or minimize accretion on the duct wall, which could otherwise impact the water cooling and the system process efficiency. These ducts may have complex geometry and experience a wide range of loading, including gravity loads, water and gas pressures, cyclic thermal loading and dynamic impact forces. Consequently, the thermo-mechanical assessment of such water-cooled ducts is critical and requires consideration phenomena such as high temperature gradients, potential nucleate boiling, thermal ratcheting and fatigue failures. Such assessment is not comprehensively covered by design-by-rule design codes and guidelines due to its complexity. This paper presents a successful implementation example of design-by-analysis methodology to improve the design and extend the life of a water-cooled furnace transition duct using Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA).INTRODUCTION Water-cooling represents an important part of high temperature off-gas systems in metallurgical processes. Typical temperatures of the off-gas in the furnace uptake are in excess of 1400°C, and thus there is a need to maintain the water-cooled duct and jacket skin temperatures within their material allowable design limits. Water-cooled channels have been used effectively in arc furnace roof design (Sosonkin et al., 1972; Smolyarenko and Khainson, 1988) and other furnaces as well as in furnace fuming jackets (Scholey et al., 1994). The design of these systems was based on one-dimensional analysis to ensure sufficient cooling is available under extreme furnace conditions (Smolyarenko and Khainson, 1988; Scholey et al., 1994). With advancement in furnace and fuming system designs, water-cooled duct designs have become more complicated in geometry. Numerical techniques, such as three-dimensional fluid flow and heat transfer modeling, are therefore needed to more accurately calculate water velocity, temperature and convective heat transfer coefficients in the water-cooled channels (Haywood et al., 2002; Henning et al., 2010). This is of particular importance around geometric corners where stagnant water flow may lead to local nucleate boiling at the critical heat flux, causing hot spots (Bergman et al., 2011). High wall skin temperatures increase the risk of failures due to thermal stresses as well as increasing corrosion rates (Gelfi et al., 2012), leading to costly equipment downtime and potential safety risks."

Jan 1, 2017

By M. Kowalczyk

The successful application of color sorting machines has established sensor-based sorting in the mineral industry in recent years and is considered today as a significant innovation in processing technology. However, we are only at the beginning of the (market) introduction. New sensor systems have been developed, which exploit material properties such as electrical conductivity, magnetization, molecular structure, thermal conductivity etc. This opens up new exciting pre-concentration and upgrading possibilities for many applications such as nickel, gold, copper and other ores as well as for industrial minerals, diamonds and other gemstones.

Jan 1, 2009

By R J. Tremblay, R. R. Hoffman

This paper deals with materials of construction and problems encountered and overcome in leaching and filtration of oxidized sulphuric acid slurry in the Port Radium mill after eight years of operation. The slurry is characterized by a high calcium sulphate content as well as a high chloride level under oxidized conditions, both of which affected initial design and subsequent changes. Leach agitation tanks are of wood with a mild steel superstructure and stainless steel agitator and moving parts below solution level. Electro-polished 316 stainless steel cooling coils are used for temperature control of the slurry. The string filters are of the Oliver type with wood decking. Extensive use is made of wood, Linatex lined mild steel and stainless steel for the slurry handling. A typical analysis of the slurry solution follows:(pH-1.30) ClOa Fe+++ Free Acid UaOs c1-so.--0.10 gms/litre 10.2 gms/litre 6. 7 gms/litre 3.5 gms/litre 2.0 gms/litre 155 gms/litre

Jan 1, 1961

By G. Kipouros, M. Dadvand, A. Dadvand

"A novel methodology was developed to obtain a 3D porous layer with a high aspect ratio of porosity on a titanium electrode. The porous structure allowed more active material such as hydrous ruthenium oxide to be accommodated during the fabrication of the supercapacitor, resulting in an exceptionally high capacitance per surface area. The electrode demonstrated a remarkably high capacitance of 4,800 mF/cm2. The porous layer was composed of functionalized nanoparticles of TiO2 organized in a perfect 3D hexagonal close-packed array that resulted in a highly porous 3D structure. The layer was used as a template to electrolessly deposit a thin layer of silver prior to the electrodeposition of active material. KEYWORDS Capacitance, Porous, Ruthenium, Silver, Supercapacitor, Titanium RÉSUMÉ Une méthodologie innovante a été mise au point afin d’obtenir une couche poreuse tridimensionnelle (3D) affichant un rapport d’aspect élevé en termes de porosité sur une électrode en titane. La structure poreuse permet d’utiliser une matière plus active telle que l’oxyde de ruthénium hydraté durant la fabrication du supercondensateur, ce qui se traduit par une capacité exceptionnellement élevée par surface active. L’électrode affichait une capacité remarquablement élevée de 4 800 mF/cm2. La couche poreuse était composée de nanoparticules fonctionnalisées de dioxyde de titane (TiO2) organisées dans un arrangement regroupé parfaitement hexagonal en 3D, qui a engendré une structure en 3D hautement poreuse. Cette couche a servi de modèle pour le dépôt autocatalytique d’une fine couche d’argent avant l’électrodéposition de la matière active. MOTS CLÉS argent, capacité, poreux, ruthénium, supercondensateur, titaneINTRODUCTION There is a growing demand for integrating compact energy storage elements into electronic circuits due to the miniaturization of electronic circuits, sensors, and actuators, and the increasing importance of portable and wear-able devices incorporating more advanced electronic technologies that operate in controlled or uncontrolled environments to gather, process, store, and communicate information (Deng, Ji, Chen, & Banks, 2011; Beidaghi & Wang, 2012; Chen, Ramachandran, Mani, & Saraswathi, 2014). The manufacturing of compact energy storage elements needs to be compatible with the electronic circuit microfabrication processes. Recently, interest in integrating miniaturized supercapacitors into electronic circuits has increased due to their high charge–discharge rate and long operating life; however, ultra-high power miniaturized supercapacitors suffer from low energy density, hence requiring significant enhancement in their energy density for various applications (Deng et al., 2011; Beidaghi & Wang, 2012; Chen et al., 2014)."

Jan 1, 2019

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 Jennifer Abols

In July of 2013, Lundin Mining acquired the 2,000 tpd Eagle nickel and copper project from Rio Tinto. The project had been put on hold earlier in the year and construction was approximately 50% complete. Lundin immediately accelerated project activities and by September of 2014 the project was constructed, commissioned and ramping up. The newly commissioned facilities went on to reach design throughput, recovery and product quality targets by the end of the year. This was accomplished ahead of schedule and below budget despite numerous obstacles including the worst winter on record in the past 50 years for the area. What led to the success of the project, and in particular the commissioning phase of the project? This paper takes a high level look back and provides an overview of the methodology used, key issues encountered and lessons learned to answer this question.

Jan 1, 2015