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By M. Pierce

Empirical relations exist for the estimation of rock block strength at scales larger than standard core sizes. Two recently published relations account for the significant impact that microflaws (pores, open cracks, veins) and weathering/alteration can have on scale effect. These relations were used to estimate the rock block strength of heavily microfractured quartzite from the Bingham Canyon Mine. Predictions were compared to the results of Uniaxial Compressive Strength (UCS) tests conducted on cylindrical core samples of varying microfracture intensity and diameter. The comparison confirms the sensitivity to microfracturing suggested by existing relations and suggests that they would benefit from more detailed consideration of microfracture strength, density and persistence over a range of scales. The results of a numerical study illustrate how Synthetic Rock Mass (SRM) modeling techniques could be used to complement empirical data in the development of such relations.

May 1, 2009

By K. Reipas

"Westmin Resources Ltd. operates the 3300 TPD H-W underground copper/zinc mine on Vancouver Island. Ore storage underground is handled in a 6000 tonne coarse ore bin and a 3000 tonne fine ore bin. Both of these bins have experienced significant wear since excavation and construction in 1985. Wear problems have included both deteriorating rock walls as well as worn out steel liners and concrete at the discharge points from the bins. Extensive rehabilitation work was completed in 1993.The basis o/this paper is the rehabilitation work done on the coarse ore bin. The design and installation of ground control measures are discussed. The bin access methods used to allow the work to proceed quickly and safely are also presented. This involved the use of a Tekfoam safety bulkhead to protect workers.IntroductionMine DescriptionThe H-W mine was commissioned in 1985. Mine access is by vertical shaft with most production areas at a depth of about 500 m. Host rocks are composed of andesite and rhyolite. Mine capacity of 3300 tonnes per day is achieved mainly by longhole open stoping methods, complemented by room and pillar mining. Metals recovered from the massive sulphide ore are copper, zinc, gold, and silver. Mineable reserves at January I, 1994 were 9.7 million tonnes."

Jan 1, 1995

By Tom Shumka

Introduction ?This technique detects 100% of all gear tooth surface indications, providing comprehensive data, and has the ability to size indications accurately. ?The remarkable advantages of ECA technology, is improved inspection capabilities and significant time-savings. ?The advantage of using EMCD is its ability to size indications accurately. ?This technique does not require the gear teeth to be wiped down by hand after cleaning as in MT, LT or UT inspections. (Figure 1) ?This technique will inspect one gear tooth in 30 seconds. ?All of the data can be archived for future comparisons in an electronic report. Methodology ?This technique utilizes Eddy Current Array (ECA) as the principle inspection technique. ?What has been added are specialty scanner probes with multiple coils, a multiplexer and a software package. ?With 2 and 3D dimensional isometric displays, the defect can be seen electronically as it is on the gear tooth surface, thus, reducing the reliance on human interpretation.

May 1, 2011

By David J. Morrison

Scarcity of truck tyres, increasing cost and decreasing availability of labour, increases in fuel costs and project budget blowouts have changed the paradigm behind mining equipment selections. The cycle of commodity changes have occurred in parallel with the increasing maturity of continuous mining machinery, mobile in-pit crushing systems and very large scale conveyor belt systems. This paper will consider the merits of operating continuous materials handling systems, mobile in pit crushing systems, relocatable crushing systems, relocatable conveyor systems and automated waste handling systems in place of the more conventional approach of truck haulage.

May 1, 2007

Agenda ?The Context ?The Challenge ?The Solution ?Benefits and lessons learnt from pilots ?Next Steps The Context ?Facilitate management decision making process by supporting the development of value/risk based business cases. ?Large scale investments by extractive industries are expected tobring broad-based benefits to local communities (e.g.: health, education, jobs, infrastructure) ?Investors continue to expect the demonstration of social performance?Specific interventions bring direct value to companies (e.g. skills development) ?Social Investments are key to protecting a company?s license to operate ?Quantifying the value of these investments and planning accordingly, however, has long posed a challenge for the extractive industries and community development practitioners

May 1, 2011

By Fiona Campbell

"Modern history is full of breakthroughs in technology, all striving to increase productivity and efficiency. What are the elements that should be taken into consideration in the design and implementation of modern automation systems in a control room? Both industry and international standards are now demanding that Human Factors be considered as part of the design of control rooms to maximize efficiency and minimize the potential of human error which can lead to downtime and a loss of profit as a result of interruptions in production. As the current workforce ages and the younger generation matures, this is also becoming a key element when planning a control room. New standards are helping to address some of these challenges that are facing the mining industry today. With an increased focus on the operator, an intelligent and ergonomic workspace can both mitigate risk and optimize production. Optimization is money. We will examine how to analyze and implement innovative control room planning to maximize mineral processing production and minimize risks that can impact overall production and profit.INTRODUCTIONIn this day and age, optimization of production in an industrial environment is becoming more and more of a challenge. With ever changing technology as well as other external factors, this can be especially daunting. There are several key elements that may not be immediately obvious when planning a control room design or renovation, most notably the role of the human in this environment. Fatigue, stress, distraction, reaction times and situational awareness are all critical in a 24/7 environment. With the growing need to include human factors when considering and designing an optimal work and production environment, it is becoming even more important to design a control room that can address as many of today’s challenges as possible.The standard definition of the word “optimization” is “an act, process or methodology of making something (as a design, system, or decision) as fully perfect, functional or effective as possible.” (www.merriam-webster.com). If we apply this to business, what it really means is finding the most cost effective way to achieve the highest level of performance while considering constraints, both external and internal, by maximizing the desired factors and minimizing undesired ones. Sometimes, however, we can get caught up in the day to day processes, without taking a moment to step back and objectively review what it is we need to achieve, and more importantly, the steps that can facilitate our success."

Jan 1, 2016

One Data Set for the Lifecycle Complete data captured at the logging stage benefits the entire life cycle Exploration Technical Studies Production and Milling Visible Light Spectrum Hyperspectral, put simply, is the interaction of light with matter based on the nature and chemical structure of the specimen. SpectrumWe develop the library to match the liberation size fraction Analyses every 1mm2 1 meter of NQ core = 35 000 analysis data Crystal size detection : 0.1 micron

May 1, 2013

By S. Koppalkar

ABSTRACT: The development and evolution of the gravity recoverable gold (GrG) test procedure at McGill university is reviewed in this paper. Since the late 1980s, the research group led by the late Professor André Robert Laplante at McGill university has undertaken fundamental studies and applied research of the Knelson concentrator to develop a sustainable method of estimating GrG. Historically, a concept of “free gold” was used, and it was de?ned as the gold that could be separated and recovered from gold ore by amalgamation. Due to health and safety hazards, the practical use of amalgamation has declined. around 1994, a methodology using a 3-in Knelson concentrator to measure gravity recoverable gold was established at McGill university. as a result of more than 10 years of improvement and optimization, this technique has become a standard method of evaluating GrG for gold ores, gold plant streams and platinum group metals. By 2006, about 200 GrG tests were carried out at McGill universityon ores from all over the world. recently, a modi?ed version of the GrG test (a simpli?ed test) was developed to provide a quick and rough estimate of the GrG in a sample; this simpli?ed test has theadvantage of reduced mass, processing time and cost. to recognize and honour the contributions madeby the late Professor Laplante towards the establishment of a standard test procedure for assessing gravity recovery potential, the authors propose that the GrG test be named after Laplante.

Jan 1, 2010

By S. Banisi, J. Marois, A. R. Laplante

"This paper compares the behaviour of gold and ore in the grinding circuit of Hemlo Mines Ltd. Particular attention is given to grinding kinetics, classification behaviour, and liberation. For grinding kinetics, laboratory grinding of gold flakes and silica, 840 µm to 1200 µm in size (14/20 mesh), was also performed to provide a standard for comparison and to study in a controlled environment the mechanisms of breakage, folding , smearing and impacting.Grinding kinetics were characterized at laboratory scale with breakage and selection functions. The breakage function showed that 75% of gold disappearing from the 840 µm to 1200 µm class reported to the 600 µm to 840 µm; this figure is much higher than for silica (46%) or most other minerals, and implies that comparatively fewer fine fragments are produced from the breakage of gold flakes, on account of gold's malleability. The selection function of silica was four times that of gold. At plant scale, the ratio of the selection function of ore and gold increased from 6 for at 50 urn to JOO pm to 20 at 500 um to 1000µm.Observation of original flakes and their fragments with the scanning electron microscope showed that the main mechanism of ""grinding"" from the 840 µm to 1200 µm to the 600 µm to 840 µm class was folding rather than actual breakage. This was confirmed by a measure of individual flake weight. The postulated breakage cycle is that relatively globular flakes become increasingly serrated through grinding; they can then regain their original shape through folding and reflattening into cylindrical and spherical shapes, as the majority does; however, some fragments will at this point undergo actual breakage. Photograhic evidence is presented to support the proposed mechanisms.Smearing of gold unto silica was observed when silica was ground after a gold, and embedding of silica into gold flakes when gold was ground after a silica. Both mechanisms occur whenever gold and harder minerals are jointly ground, and result in ""unliberation"" of gold. It is postulated that smearing of gold onto other minerals plays an important role in explaining how gravity recovery can increase over-all gold metallurgy, especially when used ahead of flotation.Classification of gold in the primary hydro cyclones takes place at a much finer cut-size than ore, 20 µm vs 57 µm. This and the slower grinding kinetics result in high gold circulating loads in the primary loop, 6700%, and a gold content in the primary cyclone underflow (PCUF) is twenty-four times that of the ore. The gold size distribution for primary cyclone overflow is much finer than that of the ore, although they are essentially similar in the PCUF.Liberation, or more accurately ""gravity recoverability"", was assessed with a 7.5 cm (3 in.) Knelson concentrator. It varied between the thirties for the primary mill discharge and two cyclone overflows, to highs of 89% and 92% for the PCUF and secondary mill discharge."

Jan 1, 1991

By Steve McMullan, Blaine Webster, Ian Johnson, Ron Matthews

"Time domain spectral Induced Polarization (IP) data from the Tower, Jojay and Laurel Lake gold deposits in northern Saskatchewan are presented. The resistivity data shows both resistivity lows (due to fault, shear or alteration zones) and resistivity highs (due to silicification) in the area of the deposits. The high resistivity zones suppress and distort coincident IP responses, calling f or high quality surveys and special care in interpreting the IP data.Electromagnetic methods are not effective in locating the deposits. This is due, in part, to masking by conductive cover. The Jojay Lake deposit has a strong magnetic response. A more indirect magnetic association is seen for the Tower Lake deposit. The Laurel Lake deposit has no magnetic signature. Magnetic data are useful in defining structure in all cases.All three deposits are outlined in the IP survey results. IP anomaly amplitudes from the pole-dipole array are from two times (Tower and Laurel Lak e) to six times (Jojay Lake) background values. Gradient array IP anomalies are of less amplitude. The spectral time constant is short for the Tower and Laurel Lak e deposits and long for the Jojay deposit. This implies that the metallic sulphides in the Jojay deposit are more interconnected than those of the other two deposits. INTRODUCTIONInduced polarization / resistivity surveys are commonly used in gold exploration program s in the Canadian shield because the IP method is effective in detecting disseminated metallic sulphides which are often found associated with gold. Other common geophysical sur vey methods such as magnetics, VLF and EM are not generally capable of direct detection of disseminated sulphides. Since the introduction of the IP method in the 1950s, it has undergone continuous improvement. The most recent improvement is the development of time domain receiver s which sample the full de cay and record it in digit al form. This results in a more complete measurement of the response which permits analysis and enhancement of data quality and the derivation of a nomaly parameters which characterize the measured decay. This extension of conventional time domain IP methods is called spectra l IP, a term first introduced by Pelton et al. working in the frequency domain Spectral IP surveys are attractive because they allow the possibility of discriminating between IP responses which have similar amplitudes but are due to dissimilar geo logic targets. The discrimination can be important in the selection of IP anomalies for follow-up.Time domain spectral IP survey results are presented over three known gold deposits in northern Saskatchewan-Tower Lake, Jojay Lake and Laurel Lake. The surveys were initiated and supported by Cameco-A Canadian Mining and Energy Corporation (formerly the Saskatchewan Mining and Development Corporation-SMDC) and were carried out by JVX Limited using the Scintrex IPR-II receiver and attendant spectral analysis software."

Jan 1, 1989

By A. B. Barlow, D. H. Pitcher

"The Geophysics/Geochemistry Section of the Ontario Geological Survey initiated an aerial geophysical survey in the James Bay Lowlands, Cretaceous Basin area, District of Cochrane, Ontario. The survey was contracted to Scintrex Limited and was carried out in 1978. Approximately 8000 line kilometres of airborne electromagnetic and magnetic data were recorded. The Tridem airborne electromagnetic system was employed, mounted in a twin-engined PB Y Canso aircraft. This specific Tridem system uses a vertical coaxial coil configuration and measures in-phase and quadrature components of the secondary field at 500, 2000 and 8000 Hz.The primary purpose of this survey was to map subsurface conductivities and, in particular, to search for lignite deposits. Physical property measurements show that electrical methods should detect differen ces in conductivity between the moderately conducting clay-lignite horizons and the less conducting clay, soil, muskeg and gravel horizons. A preliminary Tridem test survey, as well as surface DC resistivity soundings, confirmed this approach. The interpretation of the present survey data indicates that Tridem is a suitable electrical method to aid lignite exploration in the James Bay Lowlands."

Jan 1, 1980

By Georgia J. Lysay

Kemess South Mine ended operations in March 2011. Final reclamation works began during operations in 2008 in anticipation of closure. The focus of reclamation during mine operations was on the inactive areas of the tailings dam, waste rock dumps, and expended borrow areas. The general reclamation strategy for the Kemess Mine site marries long-term erosion control with successional reclamation principles. For disturbed areas, this requires application of growth media, proper preparation of surfaces, and introduction of native pioneer plant species to initiate successional processes of recovery. Tailings are retained behind an earthfill dam of approximately 140 m in height, with a crest length in excess of 1 km. Reclamation activities at the dam have included placement of growth media, specialized surface preparation and construction of diversion ditches. The final closure spillway is currently being constructed, with completion scheduled for summer 2011. The two main waste rock dumps contain segregated non-acid generating (NAG) waste rock and potentially acid generating (PAG) waste rock. Resloping of the NAG dump for long-term stability commenced in 2009, followed by placement of growth media and ground preparation. The PAG waste rock will be fully relocated into the expended open pit for final, permanent subaqueous disposal.

May 1, 2011

By Rocky (Yaokun) Wu

Rock burst is one of the biggest challenges to ground control in the mining industry. With increasing mining depth and mining scale, there are more and more industry requirements on yielding rock support. Since 2008, Jennmar has been conducting large scale research and development works to develop a technically reliable and cost effective yielding rock bolt. This paper introduces a new yielding rock support - Yield-Lok bolt. The bolt is characterized by the designed yielding ability to produce 150 ~ 250 mm of deflection at 8 ~ 10 metric tons (Mt) loads for every 16.4kJ energy input. Its performance characteristics are consistent through multiple and varying amplitude of impacts. In this paper, the design criteria of the bolt and the principle of performance are described, the dynamic testing results are discussed; and the features and application of the bolt are presented.

Oct 1, 2010

By K. A. Hildebrant, J. R. Norgate

"Synthetic lubricants have for many years documented extended service life and provided superior performance in temperature extremes. Increasing interest in synthetics' ability to reduce energy costs has resulted in laboratory and industry application evaluations. These tests have documented savings in functions such as worm gear drives, spur gears and in compressors. Energy savings data are presented as well as payback calculations as low as thirty days.The National Research Council of Canada has estimated that the Canadian economy loses over five billion dollars per year in friction and wear. Figures quoted were for 1986 during which it was estimated that nine hundred and forty million dollars were lost in the mining industry alone"" It has been further estimated that about 115 million dollars can be immediately recovered through improved tribology practices (Table I).The purpose of this paper is to present results and savings opportunities through the use of synthetic lubricants in various but common applications. Many other areas exist with the opportunity for energy savings such as in the use of more efficient drive equipment, reduced contact seals, spray mist lubrication systems and reduced friction coatings on rotating equipment such as pump impellers"

Jan 1, 1994

By Yi-xin Zhoa

The characteristics of coal bumps are analyzed based on the microseismic data from No.8935 workface in Xinzhouyao coal mine, Datong Mining Group. The geology of this workface is characterized by the thick sandstone roof and coal seam, both with relative higher stiffness and strength. In order to investigate the mechanism and precursors of coal bumps occurred in No.8935 workface, the locations of microseismic, the relationship of microseismic energy and frequency and the spectrum of microseismic signals are analyzed. The result shows that the coal bumps in No.8935 workface were mainly induced by the seismic caused by roof failure. The coal pillar near the goaf is more easily to bump. The statistics results indicate that the coal bumps were mainly occurred in the gate road near the pillar, less than 50m ahead of mining face and located in the hard roof adjacent with coal seam. Moreover, the frequency, energy, b-value and frequency spectrogram of microseismic events were found to decrease before coal bumps. It was found that the frequencies of the microseismic events before coal bumps mainly concentrate upon 5~60Hz. The sudden decreasing of frequency and increasing of amplitude of microseismic events can be regarded as a precursor of coal bumps.

Aug 1, 2013

By M. Pesowski

"Certain environmental problems can substantially alter the physical properties of the subsurface. In such cases, geophysical methods can be used to map the distribution of subsurface contamination or buried wastes prior to drilling or sampling. For example, inorganic contamination by acids, bases, salts, or metallic ions can be detected by instruments that measure ground conductivity; metallic objects such as buried drums, pipelines, etc. can be located by magnetic survey, and radioactive mine waste can be mapped by radiometric techniques. Geophysical methods can also be used to characterize site geology. If carried out prior to development, they can assist in identifying areas of high- and low permeability and sources of natural contamination. The methods can also be used to establish baseline values and to locate stable areas for development of environmentally sensitive facilities. Application of geophysical methods to environmental problems is illustrated with examples from base-metal mines, uranium operations, and potash and oil-sands operations. Particular attention is given to the problem of acid mine drainage. =IntroductionGeophysical methods have been used for many years by the mining industry in exploration and geotechnical investigations. The basic techniques for mapping variations in physical properties of the subsurface have been adapted to meet the special needs of resource exploration and development in the coal, potash , oil sands, industrial minerals, precious metals, and base-metal industries. Now the mining industry is facing another challenge: to operate the mining cycle, from discovery to closure, with minimum impact on the environment. This involves the rehabilitation of abandoned mining sites, the minimization and effective containment of pollutants at operating and developing sites, and the longterm containment and monitoring of sites after mine closures.Some of the most difficult aspects of environmental control and monitoring relate to the location of buried waste and contaminated fluids in the subsurface. As in the search for buried ore deposits or in geotechnical investigations, geophysics can be a valuable aid in subsur face environmental investigations. Investigations can be remedial , involving the location or monitoring of existing problems, or preventative, where problem areas are identified or background values are established before site development. In either case, geophysical methods should not be considered as a substitute for drilling. Geophysical interpretations in general do not provide the detail required for a complete environmental or geotechnical investigation. They are most useful as rapid reconnaissance methods for targeting subsequent drilling or for interpreting subsurface condit ions away from drill holes. Table I lists the common geophysical methods and the physical properties to which they are sensitive."

Jan 1, 1993

By Naoki Takada, Dae-Sung Cheon, Minoru Sato, Masaji Kato, Manabu Takahashi, Weiren Lin

"The permeability and specific storage of rocks and sedimentary layers deep underground are critical parameters for issues related to the buried evaluation of natural gas and oil, CO2 aquifer storage, various kind of waste storage and so on.The Shirahama sandstone of the Wakayama prefecture, Kii peninsular in central Japan, consists mainly of quartz grains with no cracks and rock fragments that are aggregations of various kind of minerals. The quartz grains have an average size of about 150 micron. The pre-existing pore sizes were distributed dominantly at approximately 1 micron, and the total porosity was about 13%.During the hydrostatic compression test, we measured permeability of Shirahama sandstone by Transient Pulse test for three mutually perpendicular directions. Permeability of Shirahama sandstone remained fairly constant while increasing the effective confining pressure. Permeability anisotropy was observed slightly in the normal and two parallel directions to the bedding planes.We used micro focus X-ray CT with high resolution of 10 micron to visualize and measure the voids space information in Shirahama sandstone. Three-dimensional data were obtained in the intact and stressed sandstone simultaneously. Pore structures and grain boundaries were clearly distinguished. Pore closure and grain movement were clearly observed with increasing confining pressure. Micro focus X-ray CT is an effective tool to visualize and measure the geometrical information in rocks.Three-dimensional medial axis (3DMA) method was introduced to quantify the flow-relevant geometric properties of the voids structure in Shirahama sandstone using µfocus X-Ray CT data. The number of connecting path between two faces, tortuosity and the shortest path distribution within an arbitrary region of Shirahama sandstone specimen were analyzed. Geometrical information on the number of connecting path shows reasonable correlation between permeability anisotropy and mutually perpendicular directions normal and parallel to bedding planes. In addition, we introduced numerical simulation of fluid flow of pressurized Shirahama sandstone by LBM, to discuss the permeability change caused by pressurization on effective confining pressure. We obtained the detailed distributions of fluid pressure and fluid velocity in relatively narrow voids space more than 10 µm. It was confirmed that pressurization effect on permeability caused by the decrease of the connecting path and the shortest path between arbitrary faces, and then caused a complex condition on fluid pressure and fluid velocity."

Jan 1, 2015

By C. Pichler, S. Luidold, C. Wagner, C. Sagadin, D. Kreuzer

Engineers and scientists have been combating the attack upon refractory materials of molten metals/matte and slags for hundreds of years. The details in many cases are still questionable or at least debatable. The corrosion is a major concern for furnace operators as refractory wear or failures inevitably results in reduced production efficiency and furnace reliability. Also the cost to industry is considerable and only a thorough understanding of all the complexities of the process will help to minimize that cost. One of the critical questions to overcome is the correct selection of refractories for the individual process steps to provide long and predictable refractory life together with high furnace availability. To understand the nature of the reactions involved in refractory corrosion, it is crucial to determine the complex thermo- chemical equilibria of the reactions occurring between the refractory materials and the process phases. A simulation model coupled with commercial software like FactSageTM is demonstrated aiming to understand the corrosion mechanisms between refractories and the molten process phases and draw implications for improving the performance of refractories and refractory lifetime. INTRODUCTION The extraction or recycling of valuable materials, e.g. metals, can be done by two main routes, pyro- and/or hydrometallurgical processing, depending on the chemical behavior of the used ore, scrap or pre-treated concentrate. Sometimes it is also necessary to use both process routes for the extraction or the recycling of valuable materials. In the case of a pyrometallurgical treatment, the usage of refractory materials is inevitable. This is mainly caused by high temperatures, prevailing during processing. The interaction between refractory material and slag, metal or matte leads to different reactions and interactions. As a main result corrosion of the furnace lining (refractory material) takes place. Hence, recurring furnace shutdowns occur for renewing the refractories. This leads to reduced production efficiency. Such refractory lifetimes are between some hours and decades, depending on the processes.

Jan 1, 2019

By W. H. MacLean, S. Liaghat

The Key Tuffite is a thick (0.3 m to 6 m) and laterally extensive (-10 km) cherty, sulfide-bearing tuff unit in Archean greenstones in the Matagami mining district in northwestern Quebec. It lies at the contact of the Watson Lake Group and overlying Wabassee Group volcanic rocks, and is host to major Zn-Cu volcanogenic massive sulfide deposits. The tuff component is highly altered and its volcanic precursors are not identifiable by petrographic means. The tuff is mixed with a volcanic exhalative component comprising chert, carbonate and sulfides (pyrite, pyrrhotite, and minor sphalerite and chalcopyrite). The normative mineral composition of the Key Tuffite is 33% quartz, 28% sulfides, 16% sericite, 8070 carbonate, 6% chlorite and 9% other minerals. In the vicinity of the Bell Allard and Orchan mines, the precursor tuff components are identified using immobile major and trace elements, as Watson Lake tholeiitic rhyolite (Zr/Y = 1.5 to 3.5, LaN/ybN = 1.7 to 2.8, SiO2 = 72.5 ± 1.2 wt %, and Wabassee calc-alkaline andesite (Zr/Y = 9, LaN/YbN= 4 to 8, SiO2 = 56% to 65%). Immobile element computation techniques were used to calculate mass additions and losses in the conversion of the tuff to the Key Tuffite. Average net amounts of FeP3 (27% total iron), Si02 (14%), Cao (8%), S and K2 (+ 2%), were added, Nap was removed (-2.8%), and MgO was over-all unchanged. Total net mass change was +63%, which comprises mainly exhalative additions, but also includes changes owing to hydrothermal alteration of the tuff component.

Jan 1, 1992

By F. Chiesa, Jeremy Carignan, B. Duchesne, D. Levasseur

"Aluminium A206 (AlCu4) is one of the strongest aluminium casting alloys with tensile properties approaching those of ferritic ductile iron. If the specification on the silicon content (< 0.05%) is easy to achieve during alloy ingot production, it is not the case in a foundry, where returns are used which are not perfectly cleaned from the silicate containing molding sand (Olivine). In alloy A206, the Si content is controlled in order to avoid the formation of a low melting point intermetallic phase (such as phase Q Al5Cu2Si6Mg2); these phases will melt during the solutionizing heat treatment to which alloy A206 must be subjected to develop its outstanding mechanical properties. This incipient melting may deteriorate the mechanical properties of Alloy A206 if the solutionizing treatment is applied at the standard temperature of 530°C.In the present study, a lower temperature solutionizing (520°C) was applied to a high Si content 206 alloy in order to reduce or eliminate the possible incipient melting. This was carried out on a complex shape industrial casting weighing 14 kg (31 lb) and 560x410x250 mm (22x16x10”) in size poured in aluminum 206 with a high silicon content (0.22% vs 0.05% max for alloy A206). Twenty ASTM E8 subsize tensile specimens were excised from two locations in the casting in order to compare the tensile properties for the two solutionizing temperature used (530 and 520°C). Optical and SEM microscopy allowed to investigate the causes of the differences in the properties observed between the 2 zones of the casting studied for 3 different heat treatments. INTRODUCTIONIn spite of their “textbook” outstanding mechanical properties (Up to twice the strength and elongation of the widely used A356 alloy), aluminum-copper alloys of the 2xx series are seldom used because of their propensity for hot tearing [Li, 2011], the segregation of copper [Cho, 2003], and their sensitivity to stress corrosion cracking [Jean, 2009, p. 113)]. Also, because of their wide freezing range and high thermal conductivity, a wide mushy zone makes feeding difficult, unless strong temperature gradients are created by liberal use of chills and risers in the critical zones of the part. Because they are prone to hot tearing, grain refining of Al-Cu alloys is particularly important, titanium playing a major role in the process [Sigworth, 2003]; grain refining has also been shown to be beneficial to fatigue strength [Jean, 2009, p. 103]. The practical basis of foundry practices pertaining to these alloys is outlined in an AFS webinar [Weiss, 2014]."

Jan 1, 2016