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By James S. Redpath

"AbstractThis paper is an attempt. to outline the present status of underground mining contracting in Canada, and to present certain facts concerning the writing and administration of underground mining contracts which, hopefully, may be useful to those intending to engage a mining contractor . The paper is based on the author' s experience as a contractor and also as a consulting engineer advising others in the purchase of contractors' services.HistoryIN THE early days of mining contracting in Canada, the contractor was primarily a labour contractor. He was expected to bring a good crew of men that normally followed him, and to perform certain work under his own direct supervision. The owner usually looked after all other details including financing, payrolls, withholding taxes, etc , computing and paying the contractor his profit. In the pre-World-War II years, most work was done on this basis.Over the years, the contractor was called on to supply more in the way of services, and the present-day situation evolved.Labour contracts are still used, but now the contractor is expected to carry out his own administration. Most contracts now call for the supply of special tooling required to do the work. In most cases, some, if not all, supplies are the contractor 's responsibility and , in a growing number of cases, the contractor is responsible for such items as design and surveying. The ultimate in this direction is the execution of projects on a turnkey basis. Under this system , the contractor carries the project to a stage where it is turned over fully operational to the owner."

Jan 1, 1977

By Michel Jébrak, Claude Bellehumeur

Abstract - Regional and orientation geochemical stream sediment surveys were carried out by the Quebec Department of Energy and Resources in southwestern Quebec, over a part of the Mont­ Laurier Terrane of the Grenville Province. The area contains some small stratiform zinc deposits. The response of Zn mineralization to geochemical surveys is weak; the known mineralization is not defined by anomalous samples and consistent patterns. This study uses a technique that increases the geochemical signature of Zn mineralization in filtering out geochemical background components related to lithologies and surficial conditions. The background variations were modelled using principal component analysis, and the filtering technique consists of the partial reconstruction of the data matrix from results of principal component analysis . The filtering procedure considerably enhances the Zn anomalies located in the catchment basins of Zn deposits, and defines some new anomalies in proximity to the marbles of the Mont-Laurier Terrane, the principal metallotect of Zn mineralization.

Jan 1, 1993

By Réal Tanguay, Mathieu Piché, Jacques Carignan, Charles Beaudry, André Bonenfant

"Le gisement Isle-Dieu est situé sur le flanc sud de l'anticlinal de Galinée. La stratigraphie locale comprend, de bas en haut, la rhyolite du Groupe du Lac Watson surmontée par le basalte du Groupe de Wabassee. Un horizon repère, siliceux et sulfure, d'origine sédimentaire, appelé ""Tuffite Clef', est présent au sommet du Groupe du Lac Watson et pend à 45° vers le sud.Le gisement Isle-Dieu est constitué par une lentille qui recoupe, en partie, la ""Tuffite Clef"". Elle est séparée en deux trorçons par un dyke de tonalite. Les données obtenues à partir des forages effectues à travers la rhyolite sous-jacente permettent de définir les zonations chimiques et pétrographiques de la cheminée d’altération.Ces transformation minéralogiques et chimiques sont caractérisées par un enrichissement en MgO, Fe2O3, MnO et un appauvrissement en CaO, SiO2 et Na2O. La zonation spatiale de ces altérations permet de mettre en évidence la géométrie et l'extension des conduits hydrothermaux. L'épaisseur maximale des sulfures massifs au sein de la lentille est en étroite relation avec l’importance des zones d'altération. Les patrons de variations chimiques dénotent une orientation préférentielle WNW des conduits hydrothermaux. Les parties les plus altérées et les plus déformées présentent localement de fortes variations positives en Zr, Nb, et terres-rares; ces concentrations sont vraisemblablement imputables a /' enrichissement résultant de la diminution du volume lors de l'altération.L'étude pétrographique montre que la porosité et la perméabilité du milieu ont joué un rôle important dans la circulation des fluides car les roches de la cheminée présentent des phénomènes de dévitrification, de bréchification et de microfracturation très prononces. La nature magnésienne de certaines chlorites et la perméabilité accrue du milieu semblent en accord avec le modelé propose par Roberts et Reardon, ( 1978 )"

Jan 1, 1990

By P. Su

Friction stir spot welding of a range of Mg-alloys is investigated (AZ91, AZ31, AM50 and AM60). The peak temperatures during friction stir spot welding of all Mg-alloys are close to their solidus temperatures. Also, the apparent material viscosity of Mg-alloy sheet is lower than that when Al-alloy sheet material is spot welded. This is important since it means that the widths of the stir zones forming during spot welding of Mg-alloy sheet are smaller than those when Al-alloy sheet is welded (when identical welding parameter settings are applied). These lower apparent viscosity values must be taken into account during numerical modeling of the Mg-alloy spot welding process. The efficiency of energy utilization is very low when Mg-alloy sheet is spot welded and is of the same order as that when fabricating Al-alloy sheet. The energy generation contributions of the rotating pin and the tool shoulder are investigated. When the spot welding operation is carried out without the application of a dwell period, the contribution made by the rotating pin vis-à-vis energy generation is around 66%. The contribution made by the tool shoulder increases to about 65% when a dwell period of four seconds is incorporated during the spot welding operation. This increase results from a longer contact time between the tool shoulder and material within the stir zone, The failure load during overlap shear testing increases when the bonded area and the energy input increase during spot welding. Sample failure initiates from unbonded regions and from discontinuities at the edge of the stir zone. The formation tendency of discontinuities is increased when Mg-Alloy sheet is spot welded because of the limited deformation characteristics of the base material at lower temperatures.

Jan 1, 2006

By Niels Verbaan, Ernesto Bourricaudy, Ronald Molnar, James Brown, Sunil Jayasekera

"SGS Minerals commissioned an internal R&D program to develop in-house expertise to design, set up and operate REE separation pilot campaigns at its Lakefield, Canada site. A team approach was used that included expert consultants in the field of REE separation as well as in-house expertise supported by the on-site Analytical Laboratories.A mini pilot scale SX circuit was designed and constructed consisting of several modular banks of 30 stages each. About 80 stages of mixer-settlers were used to separate Pr and Nd from La and Ce contained in a synthetic REE chloride stream simulating the raffinate from an initial La-Nd|Sm-Lu+Y separation.Two pilot campaigns were operated totalling 25 days of 24/7 operation with 99.4% plant availability in the final 20 day campaign. Purities of > 99.9% in the Pr-Nd strip liquor and > 99% in the La- Ce raffinate were achieved and simultaneously sustained in the second campaign for prolonged operating periods. Key to controlling and adjusting the circuit was the rapid assay turnaround (as low as 2 hours) provided by the on-site SGS analytical lab. This permitted the operating team to modify conditions and observe the effect of changes relatively quickly considering the large number of stages. A portable XRF analyser was also used to track evolving assay trends in the circuit. The small physical size of the circuit enabled longer operation with a limited amount of sample.This paper discusses the design of the circuit, operating conditions, some of the key operating factors and controls and results obtained.INTRODUCTIONSGS Minerals commissioned the design of and built a solvent extraction (SX) pilot plant for the separation of rare earth elements (REE). The plant consists of a battery of 120 mixer-settlers set up in a dedicated piloting facility.The purpose of the programme was to develop capabilities and in-house expertise in REE SX separation technology. The program aimed to establish operating procedures, sampling regimes, and analytical methodologies and protocols for this type of process/plant. A team comprised of SGS personnel and several external consultants with prior industrial and REE separation piloting experience was assembled to achieve these objectives."

Jan 1, 2016

By M. Savich

A graphical method has been developed for the evaluation of the U.S. Occupational Safety and Health Act Noise Exposure Index and the Equivalent Continuous Sound Level. The method makes use of a noise survey form and a mechanical integrator with two sliders, and is less tedious and susceptible to error than alternative methods. The graphical method is adaptable to various codes for noise exposure and may be used with any instrument that measures noise level. One example of its application to a practical situation in a Canadian mine is given to demonstrate the procedure .

Jan 1, 1978

By Lawrence D. Meinert

Abstract-Most large skarn deposits are zoned in both space and time relative to associated intrusions. Zonation occurs on scales from kilometers to micrometers, and reflects infiltrative fluid flow, wallrock reaction, temperature variations, and fluid mixing. The most spectacular examples of skarn zonation usually occur at the skarn-marble contact, where transitions between monomineralic bands can be knife sharp. Other small-scale examples occur in zoned veins and individual mineral crystals. Although, visually striking and scientifically interesting, in mineral exploration these small-scale variations are less useful than deposit- or district-scale zonation. In most skarn systems there is a general zonation pattern of proximal garnet, distal pyroxene, and vesuvianite (or a pyroxenoid such as wollastonite, bustamite, or rhodonite) at the marble front. As well, individual skarn minerals may display systematic color or compositional variations within the larger zonation pattern. Such patterns are reviewed for 14 well-studied examples of Cu, W, Sn, Au, and Zn-Pb skarns. In addition, many deposits have endoskarn or other alteration of the associated intrusion, and recrystallization or other subtle changes have occurred in the surrounding wallrocks. Copper skarns, such as Mines Gaspé in Quebec and Big Gossan in Irian Jaya, have high ratios of garnet:pyroxene and are zoned outward from the intrusion, to garnet, to pyroxene, to massive-sulfide replacement and vein deposits. Garnets in Cu skarn are Fe-rich and change from dark red-brown near the intrusive contact to paler brown, green, or yellow in distal locations. Pyroxenes in Cu skarns are pale and diopsidic near the intrusion, and become darker and more Fe- and Mn-rich away from the intrusion. Tungsten skarns, such as Salau and Costabonne in France and Pine Creek and Garnet Dike in California, have intermediate ratios of garnet:pyroxene, are more extensive vertically and along strike than perpendicular to the intrusive contact, and have zonation patterns commonly complicated by overprinting of metamorphic lithologies. In W skarns, garnet is commonly subcalcic and the pyroxene is Fe-rich, reflecting particularly reducing wallrocks or great depth of formation. Tin skarns, such as Dachang in China and Moina in Australia, also can have subcalcic garnet and Fe-rich pyroxene, but this reduced mineral assemblage typically is due to an association with reduced S-type granites. Tin skarns differ from most other skarn types in having a late greisen stage that may replace earlier Sn-bearing calc-silicate minerals, thus liberating Sn to form cassiterite. Many high-grade Au skarns, such as Hedley in British Columbia and Fortitude in Nevada, have low ratios of garnet:pyroxene and are associated both with reduced plutons and reduced wallrocks. Goldrich zones occur in Fe-rich, pyroxene-dominant, distal skarn. Zn-Pb skarns, such as the Yeonhwa- Ulchin district in Korea and Groundhog in New Mexico, have low ratios of garnet:pyroxene and generally form distal to associated intrusions. These skarns also are zoned from proximal garnet to distal pyroxene and pyroxenoid (bustamite-rhodonite), with significant zones of massive sulfides within and beyond skarn. Manganese enrichment of most mineral phases, particularly pyroxene, is characteristic of distal zones. Fundamental controls on skarn zonation include temperature, depth of formation, composition and oxidation state of associated plutons and wallrocks, and tectonic setting. Most W skarns form at relatively great depth, 5 km to 20 km, with extensive high-temperature metamorphic and metasomatic mineral assemblages. In contrast, most other skarn types are relatively shallow, <10 km and mostly <5 km, with limited, lower temperature metamorphic aureoles. Differences in oxidation state correlate well with different skarn zonation patterns, particularly garnet:pyroxene ratios and compositions, and can be used in both classification of and exploration for s

Jan 1, 1997

By Daniel J. Schulze

Abstract-Eclogite is an important source of diamond in the upper mantle, but is more localized than peridotite. Using eclogitic minerals in kimberlite and diamond exploration is also more problematic than using the well-known peridotite-derived indicator minerals Cr-pyrope and magnesiochromite. The problems include color similarities between orange garnets from eclogites, Cr-poor megacrysts, and crustal garnets, chemical similarities with Cr-poor megacryst suite garnets (specifically elevated Na2O contents), and low abundance of eclogite garnet xenocrysts in most known kimberlites. Chemical screens must be used carefully to distinguish between varieties of orange garnets in exploration samples. For example, most orange garnets of crustal origin have >22 wt% FeO, with mantle eclogite garnets having lower values. Na2O-bearing garnets from the Cr-poor megacryst suite can be distinguished from Na2O-bearing garnets from diamondiferous eclogites by the elevated TiO2 contents of the former. The low abundance of eclogite garnet xenocrysts in kimberlites worldwide, however, may dictate that use of eclogite garnets in diamond exploration in most cases be restricted to advanced stages of kimberlite exploration and evaluation of kimberlite diamond potential. Crpyropes, Mg-ilmenites and Cr-rich chromites are more useful than eclogitic garnets in most stages of diamond exploration. If orange garnet xenocrysts are sought in a kimberlite exploration program, those from the Cr-poor megacryst suite will be more useful than eclogite derived garnets, due to the typical great abundance of the former, although they carry no information of the diamond potential of the host kimberlite.

Jan 1, 1997

By Daniel J. Schulze

Eclogite is an important source of diamond in the upper mantle, but is more localized than peridotite. Using eclogitic minerals in kimberlite and diamond exploration is also more problematic than using the well-known peridotite-derived indicator minerals Cr-pyrope and magnesio-chromite. The problems include color similarities between orange garnets from eclogites, Cr-poor megacrysts, and crustal garnets, chemical similarities with Cr-poor megacryst suite garnets (speci?cally elevated Na2O contents), and low abundance of eclogite garnet xenocrysts in most known kimberlites. Chemical screens must be used carefully to distinguish between varieties of orange garnetsin exploration samples. For example, most orange garnets of crustal origin have >22 wt% FeO, with mantle eclogite garnets having lower values. Na2O-bearing garnets from the Cr-poor megacryst suite can be distinguished from Na2O-bearing garnets from diamondiferous eclogites by the elevated TiO2contents of the former. The low abundance of eclogite garnet xenocrysts in kimberlites worldwide, however, may dictate that use of eclogite garnets in diamond exploration in most cases be restricted to advanced stages of kimberlite exploration and evaluation of kimberlite diamond potential. Cr-pyropes, Mg-ilmenites and Cr-rich chromites are more useful than eclogitic garnets in most stages of diamond exploration. If orange garnet xenocrysts are sought in a kimberlite exploration program, those from the Cr-poor megacryst suite will be more useful than eclogite derived garnets, due to the typical great abundance of the former, although they carry no information of the diamond potential of the host kimberlite.

Jan 1, 1997

By W. Tse, D. Wong

Dense medium separation (DMS) is one of several preconcentration methods used for early waste rejection from run of mine ores at relatively coarse particle sizes prior to additional milling and beneficiation. DMS has been used extensively in the coal, diamond and iron ore industries but lab scale and pilot test work has demonstrated successful separation and upgrading of other minerals such as lead, zinc, copper and lithium based ores using DMS. This paper reviews historical dense media systems, results from the pilot scale Condor DMS system as well as associated laboratory heavy liquid separation (HLS) test work.

Jan 1, 2014

By Mehmet F. Tauer, Pierre Trudel

"The metamorphosed mineralized Archean Bourlamaque batholith, dated at 2710 +-54 Ma, is a homogeneous body, composed mainly of quartz diorite; it is cut by late dioritic, mafic and aplitic dykes, and contains metasomatized ultramafic xenoliths. A geochemical investigation confirms the calc-alkaline affinity of the batholith, and the REE profiles are similar (Lal Yb = 3.9 to 8.1) to those of the intermediate to felsic metavolcanic rocks at Val d&apos;Or into which the batholith was intruded and to those of the calc-alkaline members of the Blake River Group at Rouyn.Gold distribution within the batholith is heterogeneous and anomalous. Although the background Au content of the batholith is estimated to be 3.2 ppb Au by RNAA , the estimated median gold content of the batholith is 10 pp b (with P84 =32 and PI 6=3.1 ppb), much higher than that of ""normal"" granites (I to 5 ppb A u). The gold mineralization exhibits a close relationship with shear zones (e.g. Belmoral Mine) or with diorite dykes (e.g. Sullivan, Perron and Courvan mines).The following sequence of geological events is proposed: (I) pretectonic emplacement of the batholith, which is cogenetic with its volcanic host rocks; (2) regional metam orphism and deformation with localized shearing; and (3) hydrothermal alteration and quartz veining. We conclude that: (1) the Bourlamaque batholith is a gold-enriched intrusion, and (2) the determination of average gold content may be an effective method f or distinguishing ""sterile"" intrusions from those with potentials for gold mineralization.RESUMELe batholite archéen minéralise de Bourlamaque, daté de 2710+-54 Ma, est une intrusion homogène, constituée principalement de diorite quartzique, qui a été recoupée par des dykes tardifs de diorite, d&apos;aplite et de composition mafique. Il contient aussi des enclaves de roches ultramafiques metasomatisees. L &apos;étude géochimique confirme le caractère calco-alcalin du bath olite et les profits des ETR sont semblables (La/ Yb=3.9 a8.1) a ceux des volcanites intermédiaires afe tsiques de la région de Val d&apos;Or dans lesquelles le batholite fait intrusion et à ceux des unites calco-alcalines du Groupe de Blake Ri ver a Rouyn. La distribution de Au dans le batholite est à la fois anomale et hétérogène. Bien que le bruit de fond du batholite ait été estime à 3.2 ppb A u par AANR, sa médiane a été estimée a10 ppb Au (avec P84=32 et PI6= 3.1 ppb) , ce qui est nettement plus élevé que la valeur des roches granitoides ""normales"" donnée dans la littérature (1 a 5 ppb A u). Dans la batholite, la minéralisation aurifère est intimement associée aux zones de cisaillement (e.g. mine Belmoral) au aux dykes de diorite (e.g. mines Sullivan, Perron et Courvan).La séquence des évènements géologiques suivante est proposée: (1) emplacement pre-tectonique du batholite, lequel est cogenetique avec les roches volcaniques encaissantes; (2) deformation et metamorphisme regional avec des cisaillements tectoniques locaux; et (3) altération hydrothermale et développement des veines de quartz. Nous concluons que: (1) le batho lite de Bourlamaque est une intrusion enrichie en Au; (2) la determination de la teneur en Au peu être une méthode efficace pour distinguer les intrusions stériles de celles qui possèderaient un pot entiel pour des minéralisation s aurifères."

Jan 1, 1989

By X. -G. Chen, K. Liu

Nowadays, great interests are rising on aluminum alloys for the applications at elevated temperature, driven by the automotive and aerospace industries requiring high strength, light weight and low cost engineering materials. As one of the most promising candidates, Al-Mn-Mg 3004 alloys is found to possess considerably high mechanical properties and creep resistance at elevated temperature resulted from the precipitation of a large number of thermally stable dispersoids during heat treatment. In present work, the effect of Fe contents on the evolution of microstructure as well as high temperature properties of Al-Mn-Mg 3004 alloys has been investigated. Results show that the dominant intermetallic changes from a-Al(MnFe)Si at 0.1 wt.% Fe to Al6(MnFe) at both 0.3 wt. % and 0.6 wt. % Fe. In the Fe range of 0.1 to 0.6 wt.% studied, a significant improvement on mechanical properties at elevated temperature has been observed due to the precipitation of dispersoids, and the best combination of compression strength and creep resistance at 300°C is obtained in the alloy with an intermediate Fe content (0.3 wt.%) with finest size and highest volume fraction of a-Al(MnFe)Si dispersoids. The superior properties obtained at 300°C makes 3004 alloys more promising for high temperature applications. The relationship between the Fe content and the precipitation of stable dispersoids as well as the materials properties has been discussed.

Jan 1, 2015

By M. B. Shongwe, R. K. K. Mbaya, C. K. Thubakgale, P. Mendonidis

"A low-grade nickel-bearing ore was pre-concentrated on a SB40 laboratory model Falcon Concentrator. Three size fractions, -212+125, -125+75 and -75 µm were tested with the intent to upgrade the nickel content by reducing their content of fine silica, which becomes amorphous during leaching. Separation of silica from nickel-bearing magnesium silicate minerals; hornblende, clinochlore and talc, was more efficient in the finer particle sizes, -125+75 and -75 µm, and at high G-forces. For these two size fractions, nickel was upgraded from 0.06 to 0.07%, with a reduction in silica content from 52.12 to 50.71%. Leaching of feed samples prior to pre-concentration resulted in the formation of amorphous silica, indicative of the presence of fine silica in the samples. Leaching of nickel from the -125+75 µm fraction increased with increasing G-force and feed pulp percent solids, while that of -75 µm was not influenced. The optimum nickel recovery was 15.68% to the Falcon underflow, using the feed size fraction of -75 µm, 30 G and a feed pulp solids content of 10% solids, after 120 minutes of treatment.INTRODUCTION A low-grade South African nickel-bearing ore with about 0.06% Ni was previously studied for atmospheric pressure acid leaching using sulphuric acid. The study was motivated by the continuing search for methods to treat of low-grade ores, which appear to be an increasingly important source of valuable metals as a result of a declining production from rich sulphide ores. Nickel is a base metal that is used as an alloy in steelmaking and chemical industries because of its resistance to corrosion (Haudet et al., 2015). Nickel laterite ores with grades lower than 1.50% Ni are considered to be complex ores, accounting for 70% of the global nickel reserves (MacCarthy et al., 2016). Their complex nature may be attributed to the indefinite mineralogy of these ores, in which nickel may occur in more than one mineral host. In some cases, nickel may be finely disseminated in the ore. The grade of such an ore and complex mineralogy do not justify the application of pyrometallurgical methods for extraction of nickel (Zhu et al., 2012). This suggests that there is a need for less expensive alternative methods of extraction. This study investigates the application of centrifugal gravity concentration, using the Falcon concentrator, followed by leaching to determine the effect of pre-concentration of the ore prior to extraction by atmospheric pressure leaching with sulphuric acid."

Jan 1, 2017

By A. R. Pasieka, J. C. Wilson

"Compressed air still remains an essential source of power in underground hardrock mining. As a power medium it has a high convenience factor, although, in many cases, it is expensive to generate and maintain. Until new methods of breaking rock and/ or satisfactory alternatives to air-driven rock drills are developed, compressed air is indispensable. It is essential to utilize this source of power to a maximum by keeping all pneumatic tools supplied with air in adequate quantity and at optimum pressure.In search of the optimum operating air pressure, con-trolled drilling tests were undertaken at dynamic pressures ranging from 90 to 140 psi.Test results show the effect of increasing air pressure on: the performance of various jackleg drills at varying pressures, the life cost of drill steels and TC bits, and drilling efficiency at varying pressures. From the fore-going, a criterion is proposed for selecting efficient rock drills, and, also, optimum air pressure at each mine can be determined for its particular conditions."

Jan 1, 1966

By C. S. Lord

"The Regal Silver mine is 5 miles north-northwest of Albert canyon; a station on the main line of the Canadian Pacific railway; 21 miles east of Revelstoke; British Columbia.Development, commenced in 1918, comprises more than 8,000 feet of workings from six adits, one of which extends into the Regal Silver property from the adjacent Snowflake ground. Production has been limited to a little tungsten concentrate recovered recently from a few r..undred tons of ore treated in a small underground mill. The property has received some attention as a possible source of tin. The deposits are large quartz veins containing irregular sulphide bodies. Ore minerals normally make up less than 1 per cent of the veins and include pyrite, galena, sphalerite, scheelite, and stannite. The veins are approximately parallel with the bedding of the enclosing graphitic, siliceous to calcareous, slates and argillites. These strata are of Precambrian age, strike about northwest, and dip northeast. No other rocks are known in the vicinity of the workings . Granitic rocks, intrusive into t'he sediments, outcrop 4 miles to the southwest and 7 miles to the northeast and may underlie the property at no great depth."

Jan 1, 1954

By J. Fellowes, Z. Liang, J. Robson, M. Kenyon

"Dispersoids play a significant role in the recrystallization and texture development for wrought Al-Mg-Si (6xxx series) alloys by inhibiting grain boundary motion. It is therefore important to understand the precipitation kinetics of such particles. It is the additions of Mn and Cr in Al-Mg-Si based systems that can lead to dispersoid phases being formed. These phases are currently thought to nucleate on ß’-Mg2Si via an intermediate semi-coherent precipitate. Scanning transmission electron microscopy (STEM) has been conducted to study the precipitation of a-Al(CrFe)Si and a’-AlCrSi dispersoids. Corresponding electron dispersive spectroscopy (EDS) has been used to distinguish the dispersoids. The volume fraction and size distribution of dispersoids has been measured as a function of distance across a grain. Electron probe microanalysis (EPMA) has been conducted to study the inhomogeneity of elements in the cast structure and the effect on dispersoid precipitation. Dispersoid free regions have been observed in the microstructure correlating to regions depleted in the dispersoid forming elements.INTRODUCTION Al-Mg-Si (6xxx series) based alloys are increasingly being used in the automotive industry. The primary reason is to reduce the weight of vehicles, resulting in a reduction of CO2 emissions and increased fuel efficiency. The demand for 6xxx series is predicted to increase over the coming decade. Due to the high cost and CO2 emissions produced by raw extraction of aluminium, close loop recycling of these alloys becomes a more important process. However recycling of automotive alloys can be difficult due to pick up of impurity elements such as Mn, Cr and Fe. The addition of these elements can form dispersoid particles during early heat treatment processes. Although a controlled population of dispersoids is necessary to control the grain structure during thermo-mechanical processing, a significant change to the dispersoid population due to a composition change could profoundly influence the final microstructure, affecting the final properties of the material. More research is required on the precipitation and effect of additional minor alloying elements; in order to increase the 6xxx series alloys recyclability."

Jan 1, 2018

By C. M. Offenhauer

Abstract Zirconium markedly affects the formation of graphite in cast iron and may promote the formation of normal flake gaphite, fine flakes of eutectiform graphite, or spheroid nodular graphite, according to the composition of the Iron and the amount of the zirconium addition. Usually, it is employed in the form of a complex addition agent in order to facilitate its introduction and to guide its effect. The reported applications of zirconium as an inoculant for the production of pearlitic high-strength cast iron indicates that it is most effective as a silicon-manganese-zirconium alloy. Added in this form it reduces chill and minimizes zones of ferrite and eutectiform graphite. In low-sulphur cast iron, zirconium in amounts greater than 0.10 per cent tends to promote the development of eutectiform graphite. These irons are characterized by freedom from primary cementite or normal flake graphite and exhibit very little tendency to shrinkage on solidification. In hyper-eutectic low-sulphur cast iron, zirconium causes the formation of a partially nodular graphite structure. A combination of magnesium with silicon-zirconium alloy was found to produce completely nodular graphite structures without the hazards associated with the addition of elemental magnesium.

Jan 1, 1949

By A. D. Pittuck

Refractory minerals .containing uranium and columbium have been successfully treated at Queen&apos;s University, Kingston, to produce high-grade concentrates. Recoveries of over 90 per cent of the uranium and columbium have been obtained when treating concentrates containing euxenite, fergusonite, betafite, and pyrochlore. The processes ?consisted -of leaching the columbium with hydrofluoric acid, and the uranium with nitric acid, sulphuric acid, or sodium carbonate solutions. The leach liquors were extracted with organic solvents from which the values were stripped and precipitated, producing final products assaying 45 to 55 per cent Ob2O5 and 60 to 70 per cent U3Os.

Jan 1, 1958

By D. M. Rippley

THE St. Lawrence Seaway Project ranks with the greatest engineering undertakings of all time. A summary of major materials going into the construction of this project, shown in Table I, will assist in an appreciation -of this fact. These data relate to Seaway construction only, and it should be remembered that two large-scale power projects are in the construction stage on the St. Lawrence river concurrently with construction of the Seaway. A project of such magnitude as the Seaway would attract widespread interest even if it were being constructed in a remote area. The fact that it is located in a heavily populated and developed section of both Canada and the United States has done much to enhance this interest, and in many ways complicates the problems confronting the engineer in the design and construction phases. Many consider the St. Lawrence Seaway to be a new idea that has developed within the past decade - such is far from the fact, because the St. Lawrence River canal systems have existed for more than a century, and the Seaway Project is but a new, larger, and more efficient version of a continually expanding facility.

Jan 1, 1957

By M. Epiney, A. Ghahreman, R. Kim1and

"Pre-oxidation and cyanide leaching behavior of gold in the presence of sulfide minerals were reviewed, focused on the effects of oxygen injection in the gold leaching process. Generally, pre-oxidation and gold leaching kinetics from iron sulfide refractory minerals, such as pyrite, pyrrhotite, marcasite, pentlandite and arsenopyrite, can be enhanced with higher dissolved oxygen (DO) concentration. However, most of copper sulfide minerals dissolved well both in water and cyanide solutions, and copper from the minerals consumed DO and cyanide to oxidize and leach. Only in the presence of chalcopyrite, gold leaching was effectively occurred with increasing DO. However, chalcocite and covellite severely retarded gold leaching. Stibnite, an antimony mineral, formed a passive film on the gold surface under any DO conditions, and it slowed gold leaching. This impeding effect can be alleviated by leaching at low pH or adding lead salt. Using oxygen and lead together can make synergistic effect in oxidation of sulfide minerals and can enhance gold extraction. Depending on the mineralogical characteristics of the ore, the optimum DO and lead concentrations can be optimized. However, lead can cause environmental problems, and so its dosage should be minimized or eliminated by substituting it with oxygen injection.INTRODUCTIONGold ores containing sulfide minerals are becoming more significant as high grade gold oxide deposits are continuously becoming difficult to find. In light of this situation, to produce more gold, recovery methods from refractory gold ore containing various sulfide minerals should be investigated. Generally, sulfide minerals have impeding effects on gold leaching: formation of a passive film on the gold surface, high consumption of chemicalssuch as cyanide and oxygenduring leaching, reduction of gold cyanide by sulfide ions, etc. (Senanayake, 2008). Therefore, sulfides must be properly treated for better gold recovery. Pre-oxidation of sulfide minerals by injecting pure oxygen can decrease the impeding effects in gold leaching. Prior to cyanidation, sulfide minerals can be oxidized to metal hydroxide and sulfate form, which consume negligible cyanide in the following cyanidation circuit (Bodnaras et al., 1993). Moreover, gold cyanidation can be enhanced by increasing concentration of the dissolved oxygen (DO). In general, the optimum concentration ratio of [CN-]/[O2] is calculated as 6, but it goes higher in the real system (Marsden &House, 2006), which means that the reaction is typically controlled by DO concentration."

Jan 1, 2017