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By P. Zhang, K. Liu, L. Ou

"The strength and mechanism of Portland cement prepared from stone coal vanadium slag were studied in this paper. Initially, the slag was used as silicon raw materials to prepare clinker. By blending the prepared clinker with gypsum, waste, and fly ash, a series of different grades cement got well prepared. All of performances of the cement were up to the requirements of China’s national standard. The hydration products and microstructure of cement were identified and analyzed by X-ray diffraction and scanning electron microscopy. With the comparison of cement hydration characteristics at different ages, the strength formation mechanism of cement was clarified. The experimental results suggested that adding the fine materials (mainly waste and fly ash) to replace part of clinker would accelerate cement hydration, as it provided additional surfaces for the nucleation and growth of hydration products. And the hydration products were similar to ordinary Portland cement, mainly containing the amorphous calcium silicate hydrates (C-S-H), acicular ettringite (AFt) and portlandite (CH). With hydration time increasing, the hydration products continuously covered the cement particles, resulting in a thicker surface layer. As a result, it gradually condensed into a dense structure block with small pores and smooth surfaces, which led to higher strength. In conclusion, using the vanadium slag to prepare Portland cement can realize the utilization of solid mineral wastes, which will bring huge ecological and economic benefits.INTRODUCTIONWith the development of China’s mining industry, more and more mineral waste residue is discharged every year. These solid wastes cause varieties of resources and environmental problems on people’s living area. While at the same time, the demands of cement are increasing with the remarkable development of the construction industry. Thus, in recent years, utilization of proper solid waste to prepare cement has become an efficient way to deal with the solid mineral wastes problems (Boncukcuoglu, Kocakeri?M, & Tosunoglu, 2002; Simatupang, Hanafi, Purwasasmita, Imran, & Pane, 2012; Tsakiridis, Papadimitriou, Tsivilis, & Koroneos, 2008; Yun, Yong, Choi, Lee, & Lachemi, 2009)."

Jan 1, 2016

By S. R. McCutcheon, D. R. Lentz, W. S. Downey

"Abstract - The Little Falls member of the Nepisiguit Falls Formation is situated in the northern part of the Brunswick Belt of the Bathurst Mining Camp and has been interpreted as the distal equivalent of proximal tuffaceous rocks that host the stratiform Brunswick No. 12 and No. 6 Pb-Zn massive sulfide deposits. It comprises fine-grained, greenish-gray tuffaceous sandstone in the lower part, and coarse-grained, crystal-rich tuffaceous sandstone in the upper part. Petrographic evidence suggests that these rocks have a turbiditic origin. The Little Falls member is underlain by the Vallée Lourdes member, mainly composed of relatively shallow-water calcareous rocks, and is conformably overlain by Mn-rich sedimentary rocks, mainly red argillites that host the Tetagouche Falls Mn-(Fe) deposit. All these rocks are considered to belong to the Nepisiguit Falls Formation, part of the Ordovician Tetagouche Group. Whole-rock geochemical data from the fine-grained tuffaceous sandstone and coarse-grained tuffaceous sandstone indicate that the two units of the Little Falls member are distinct. Zr and TiO2 contents, and total rare earth element (REE) values are higher in the coarse-grained unit (average Zr/TiO2 = 0.040, average SREE = 247 ppm, n = 6) than in the fine-grained unit (average Zr/TiO2 = 0.048, average SREE = 158 ppm, n = 17), which can be attributed to the variation in crystal content between the two units. Both units are HREE-enriched and have elevated La/Yb relative to the typical Nepisiguit Falls Formation. Overall, the geochemical data combined with evidence from the bounding units suggest that the Little Falls member was deposited in relatively shallow water, possibly in a near-arc environment. The relationship of volcanic facies within the Nepisiguit Falls Formation and the geochemistry of these facies indicate strongly that fine grained, reworked tuffaceous rocks, regardless of whether they are the distal equivalents of proximal tuffaceous rocks, are not associated with the major ore-bearing horizons of the Bathurst Mining Camp. Sommaire - Le Membre de Little Falls de la Formation de Nepisiguit Falls se retrouve dans la partie nord de la Ceinture Brunswick du Camp Minier de Bathurst ou elle a été interprétée comme l’équivalent distal des roches tuffacées proximales hôtes des gisements de sulfures massifs de Pb-Zn stratiformes Brunswick No.12 et No.6. Il consiste en grès tuffacé à grains fins gris verdâtre dans sa partie inférieure et en grès tuffacé à grains grossiers riche en cristaux dans sa partie supérieure. Les données pétrographiques suggèrent que ces roches ont été déposées par des courants de turbidité. Le Membre de Little Falls repose sur le Membre de Vallée Lourdes, lequel consiste principalement en roches calcareuses déposées en eau relativement peu profonde; il est de plus recouvert en concordance par des roches sédimentaires manganifères, lesquelles consistent principalement en argilites rouges hôtes du gisement de Mn-(Fe) de Tetagouche Falls. Toutes ces roches appartiennent à la Formation de Nepisiguit Falls, laquelle fait partie du Groupe de Tetagouche, d’âge Ordovicien. Les données lithogéochimiques des grès tuffacés à grains fins et à grains grossiers indiquent que ces deux unités du Membre de Little Falls sont distinctes. Les teneurs en Zr et en TiO2, ainsi que la teneur totale en Éléments des Terres Rares (ÉTR) sont plus élevées dans l’unité à grains grossiers (Zr/TiO2 moyen = 0.040, SREE moyen = 247 ppm, n = 6) que dans l’unité à grains fins (Zr/TiO2 moyen = 0.048, SREE moyen = 158 ppm, n = 17), ce qui pourrait s’expliquer par la variation de la quantité de cristaux dans chacune de ces deux unités. Chacune de ces deux unités présente un enrichissement en ÉTRL ainsi qu’un rapport La/Yb relativement plus grand que ce qui est typiquement observé dans la Formation de Nepisiguit Falls. Les données géochimiques considérées conjointement à l’information provenant des unités adjacentes suggèrent que le Me"

Jan 1, 2006

By G. Q. Zhou, H. C. Liang, X. D. Zhao

"This study describes the strain behavior in vertical shaft lining (VSL) embedded in thick soil deposits and its application in assessment of concrete deterioration. The observed strain in VSL continuously decreased companied by a sinusoidal fluctuation due to the influences derived from negative skin friction (NSF) and temperature. The increase in strain increment between peak and trough at each year and compressive strain level as the servicing time continued and VSL depth increased implies that the concrete strength was attenuated, and this attenuation was significantly dependent on the existing compressive strain level in VSL. The reliability of the proposed approach was validated by Schmidt Hammer Technique (SHT) – based concrete strength, and is applicable in concrete assessment and then fracturing prediction of VLSs in thick soil deposits.Concrete strength, Field monitoring, Strain behavior, Vertical shaft liningINTRODUCTIONOver 100 VSLs in Southeastern China subjected to an unpredictable fracturing as shown in Figure1, and there are over 1,000 VSLs embedded in thick alluvium su?ering from challenges of damaging and potential fracturing (Cheng, Yang, Zhou, Li, & Hu, 1993; Zhou, Cui, Lv, Huang, & Chen, 1999; Li & Li,2005). Therefore, a reliable assessment of these VSLs is significant to the normal servicing of mine shafts and the recycle of underground space when these mine shafts were closed.The continuous increasing of NSF induced by the drainage of water–saturated deposits well interpreted such extensive fracturing phenomenon, and it is universally regarded as the governing indicator to determine the VSL stabilization (Cheng et al., 1993; Zhou et al., 1999). Based on this recognition, the fracturing prediction and VSL strengthening according to the field monitoring on hydrogeological characteristics, servicing environments, and mechanical behaviors of VSL were carried out (Zhao, Zhou, Zhong, Zhu, & Liang, 2009; Liang et al., 2009; Xie, Lv, & Wu, 2014). As known, the compressive strain level in VSL and the in–situ strength of VSL concrete were the main factors to perform such fracturing prediction. However, the existing studies in literatures were limited to the strain accumulating or releasing behaviors (Zhao, Zhou, Zhao, Kuang, & Hu, 2017), and lack of considering the VSL concrete strength and its attenuation. In this reported study, the in–situ monitoring data on the strain in typical VSLs and the VSL elevations between 2004 and 2014 were initially analyzed. Then, an observed strain behaviors–based approach was developed to quantitatively evaluate the VSL concrete deterioration."

Jan 1, 2019

By G. Song

Magnesium has excellent bio-compatibility in terms of its density, strength, elastic modulus and toxicity. However, due to its poor corrosion performance, so far magnesium has not been successfully used in the human body as a permanent implant material. Nevertheless, there is a possibility to utilize the low corrosion resistance of magnesium to make magnesium into a temporary implant component that can gradually dissolve in the human body after surgical region heals. This will avoid the secondary operation to remove the temporarily implanted component and the chronic inflammatory discomfort caused by the implant. This paper is aimed at exploring the possibility of using magnesium as a degradable bio-material through investigating the corrosion behaviors of pure magnesium and surface treated magnesium in a simulated body fluid (SBF) solution. It was found that magnesium corroded rapidly in the SBF solution, resulting in vigorous hydrogen evolution and a strong alkalization effect. Hence, it is impractical to use magnesium as a permanent implanted material or even a degradable implant. However, a proper anodizing treatment can significantly improve the corrosion resistance of magnesium, and hence slower down the hydrogen evolution and alkalization processes, which will allow to control the corrosion or degradation of magnesium at a desired rate in the human body. With a controllable corrosion rate, it is believed that magnesium as a degradable implanted material will be eventually achievable.

Jan 1, 2006

By K. V. Phani Prabhakar, G. Padmanabham1, L. Subashini

Laser-arc Hybrid Welding (LAHW) is a relatively recent concept which effectively combines the advantages of laser welding such as the high depth of penetration, low heat input, high welding speed and the positive aspects of arc welding such as better edge bridging and possibility to add filler. For example, steel sections upto 12 mm thickness have been successfully welded in a single pass at a welding speed of 1 m/minute using a 3.5 kW CO2 laser in combination with a MIG arc. Maraging steel of grade M250 is widely used in the aerospace industry in thicknesses upto 10 mm. Conventionally, it is possible to MIG weld such thicknesses in 3-5 passes employing V-Groove joint preparation. However, this multi-pass welding results in formation of reverted austenite in the weld zone after post weld aging; and the high heat input widens the reverted austenite containing heat affected zone which is popularly known as the dark zone/eyebrow zone. Both these zones are detrimental to strength of the welded joint, specifically the fracture toughness. The width of the dark band is an important factor because, thinner the band, it is supported more effectively by the surrounding material. Therefore, in order to avoid multi-pass welding and reduce the overall heat input, single-pass laser-MIG hybrid welding was attempted on 10 mm thick maraging steel M 250 plates using a hybrid laser arc welding system comprising a 3.5 kW CO2 slab laser and a MIG welding system. Simultaneously, multi-pass MIG welds also are produced. Both the laser-MIG hybrid and MIG welds are characterized microstructurally and subjected to mechanical tests such as tensile and fracture toughness in as-welded and post weld aged condition. The amount and distribution of reverted austenite in the fusion zone and width of the dark band was found to be different. Hybrid welds showed a narrow dark band zone and improved mechanical properties. Laser-hybrid and MIG welding investigations carried out on thick section maraging steel M 250 will be presented in detail, including microstructure, tensile properties and fracture toughness of the welds. To the best of the knowledge of the authors there are no reports on laser-MIG hybrid welding of maraging steels.

Jan 1, 2014

By V. Murugaiyan

The Geotechnical Engineer is faced to view problems emerging from the task of protecting the environment and also the problems related to prevention of natural hazarders. Geo-Environmental Engineering, based on the development of geotechnical engineering, addresses the problems for the industrial world and the impact on health and welfare in relation to pollution of the ground. In the recent years, acute land pollution due to indiscriminate discharge of industrial effluents especially Organic acid based effluents has become one of the major concern due to erosion in the privatization of sustainable development under Indian Scenario. To study the effect of chemical changes on soil properties due to amino acid effluent contamination on soil and erosion behavoiur. The changes in the soil properties of effluent contaminated clay and silty soil were experimentally observed to be due to the interaction of organic and inorganic constituents of effluent on index properties of soil. The surface reactivity of soil mass is experimentally reported to be varying proportionately with respect to clay (%) in the soil. Also higher surface reactivity of clay increases the Solid Retension Time (SRT) with increase in rate of chemical transformation of organic and inorganic solids within soil. Hence soil S1 (high clay content 54.5%) showed increased SRT and soil S3 (low clay content, high silt and clay content 94.9%) showed decreased SRT and long transformation stage.

May 1, 2004

By D. Ingram

"PRIMARY DUST COLLECTOR A. 42,000 CFM James Howden Fan Z-6 Size 3650 Fan Dia 40"" HP 75It was found that the fan was not large enough to remove the air that was displaced by the trucks dumping. So it was removed and an enclosure was installed to isolate the gyro from the rest of the building.B. FANSJames Howden Fans Model RPM 3500 Series 357 FW HP 10These fans were installed when the first dust system was put into operation. It was found that the high RPM and extreme fan wear caused a major maintenance problem. These fans were replaced with Chicage Blowers Model SWS1 RPM 1180 Dia 36"".DRY CYCLONE COLLECTORS A.,Three four foot rubber lined cyclones. Four six foot rubber lined cyclones.All under flow. Water is controlled manually and gravity flows to a central sump box. From there it flows to the grinding circuit in the Mill.Cyclone under flow product runs between 100 and 200 tons of dust per 24 hours with a screen analysis 30% + 400.The cyclone under flow product is diluted to about 3 to 4%. Solids total gallonage approximately 400.B.,Elbair Wet Scrubber125 HP RPM 56042,000 CFM,Model PX861The Elbair collects the total product from the discharge. Of the Cyclone fans the under flaw goes to the Mill - the Elbair discharges stack goes to atmosphere.The Elbair wet scrubber had to be redesigned in order to keep it in service."

Jan 1, 1976

By J. Stiksma, J. Dennett, R. Kalanchey, J. Ji, M. Collins, T. Chan, R. Berezowsky

A pilot plant campaign has been conducted by Sherritt Technologies in support of Eldorado Gold Corporation’s evaluation of pressure oxidation technology for the treatment of refractory gold concentrates from the Certej deposit in Romania. Four separate concentrates, containing 3.5 to 5.4 g/t Au, 13.0 to 14.5% S2- and 12.0 to 32.5 g/t Ag, were tested in the eight-day campaign. The major gold-bearing mineral was pyrite. Preliminary batch tests indicated that gold extraction from the oxidized concentrates in subsequent cyanide leaching was adversely affected by the presence of organic carbon in the pressure oxidation feed when chloride in solution was at an elevated level. As such, the process conditions that were tested during the pilot plant operation were selected to either counteract the negative impact of the organic carbon, or to deactivate it during pressure oxidation. Both process routes proved feasible, yielding gold extraction of 95 to 98% in cyanide leaching of the oxidized concentrates. Silver extraction was typically in the range of 80 to 90%, provided that the oxidized concentrates were also processed in a lime boil step prior to cyanide leaching.

Jan 1, 2014

By Dean McDonald

The Committee Bay Greenstone Belt extends over 300km and is one of the largest unexplored greenstone belts in North America with excellent gold and diamond potential. Committee Bay Resources Limited holds over 550,000 acres of land with prospective geology in the Committee Bay area southwest of Melville Peninsula, Nunavut. Committee Bay is a typical Archean greenstone belt comparable to the Yellowknife, Red Lake, Kirkland Lake and other prolific gold belts. Drilling during 2003 at Committee Bay resulted in: 1) the discovery of high-grade gold-bearing quartz veins with silicification and sulphidation at Three Bluffs, and 2) the continuation of high-grade gold mineralization in the hinge area of the iron formation at Inuk. Gold mineralization at Three Bluffs is identified in iron formation and adjacent sediments and has been traced by drilling for over 700m. The Three Bluffs iron formation is open to depth and along strike where is has been traced on surface for over 6km. In January 2004 Committee Bay and joint venture partner Gold Field?s announced a $7.1 million exploration program for the Committee Bay project in 2004. A total of 8,000m in exploration drilling has been approved for the expansion of the Three Bluffs to the resource stage and drilling of at least five new target areas. Additional mapping, sampling and geophysics will be used to identify new gold targets along the very prospective Committee Bay belt.

May 1, 2004

By D. R. Pyke, R. S. Middleton

"Three main types of base metal sulphide mineralization are present in the Timmins area:(1) -Massive and stringer-type copper-zinc deposits occurring mainly in pyroclastic rocks, as typified by the mines of Kam-Kotia, Jameland and Canadian Jamieson, or within or close to possible breccia pipes as shown by the Genex and Kidd Creek mines. With the exception of the Kidd Creek mine, all of these orebodies occur northwest of Timmins (Kamiskotia area) and appear to lie within or close to a major center of volcanic activity characterized by a thick accumulation of felsic pyroclastic rocks and subordinate epizonal intrusions. The margins of the rhyolitic pile are interfingered with mafic volcanics; overlying sedi-ments mark the termination of a vol-canic cycle. The copper-zinc deposits in the Kamiskotia area are confined to a particular stratigraphic unit. Ore-bearing solutions were probably derived from the intrusive complex of the volcanic pile.(2) -Porphyry copper deposit of the Mcintyre mine. The deposit occurs in a quarz porphyry intrusion related to the volcanism in the area (Hurst, 1936). Mineralization was probably introduced at the time of intrusion, and subsequently redistributed within the porphyry during deformation. (3) -Massive and disseminated nickel mineralization, associated with serpentinized alpine-type ultramafic intrusions, as shown by the Alexo, McWatters, Hart, Inco and Texmont deposits. The nickel mineralization occurs at or near contacts of the serpentinites with felsic or mafic volcanics, or sulphide-bearing iron formations. The nickel deposits south of Timmins are confined to a particular stratigraphic unit along the margins of domical-shaped structures which appear to outline former volcanic centers. Sulphurization as pro-posed by Naldrett (1966) appears to be a workable hypothesis for the formation of some of the deposits."

Jan 1, 1971

By S. R. L. Harding

"Introduction0N MAY 2th, 1953, Socony Seaboard Pembina No. 1 well, located 70 miles west-southwest of Edmonton, was completed as a producer of high-gravity oil from the Cretaceous Cardinm sand. This event is possibly the most significant in the development of the oil industry in Western Canada since the Devonian discovery at Leduc in 1947. The result of the Pembina discovery and the follow-up drilling has been a tremendous increase in interest in the Cardium formation.Descriptions of the Cardium formation, as it occurs in the 'Central Foothills' and in the 'Southern British Columbia Foothills' have been presented by R. E. Folinsbee (9)-and C. R. Stelck (21), respectively. The purpose of this paper is to discuss the more regional aspects of the subject.The name Cardium was first used .as a stratigraphic term in 1863. Dr. James Hector ( l2), geologist attached to Captain John Palliser's exploratory expedition, gave the name 'Cardium to the whole section of marine Cretaceous beds exposed along the Bow river west of Calgary."

Jan 1, 1955

By J. Shang, P. Howarth, B. Morris

Tailings from the nickel refinery in Copper Cliff, Ontario, consist of fine silicates mixed with a variable amount of conductive and magnetic minerals mainly associated with sulphides and iron oxides. Subsequent oxidation of sulphide- rich phases within the tailings results in the formation of an acidic leachate that may contain significant concentrations of trace metals. Mapping the spatial distribution of regions of higher sulphide concentration therefore provides insight into the distribution of the acidgenerating potential within the tailings. Electrical conductivity is constrained by two parameters — the concentration of metallic sulphides and the ionic concentration of acid in groundwater. Magnetic susceptibility is directly related to the pyrrhotite and magnetite content. It is proposed that combining information derived from airborne electromagnetic and magnetic surveys can provide an indication of metallic sulphide distribution. Preliminary investigations of airborne electromagnetic and magnetic data acquired concurrently over the sulphide-rich Copper Cliff tailings site reveal that these parameters can provide information on mine tailing extent and permit separation of tailings with varying compositional and alteration levels. Airborne geophysical data provide information about the subsurface while a digital elevation model (DEM) and hyperspectral imagery record surface conditions. Integration of the two data sets can reduce ambiguity when interpreting mine tailing distributions and their subsequent alterations.

Jan 1, 2001

By R. P. Taylor

"This paper covers the development of the property to its present production level of20,000 tonnes per day from the Valley Mine. It will also review the analysis of various case studies for the expansion of the project to its full potential, and discuss the impact of the recent structural change in the copper market on the development of a large low-grade deposit such as Valley.IntroductionIn 1964 Cominco participated, along with a number of other companies and individuals, in the formation of Valley Copper Mines Ltd. This company was formed in order to facilitate exploration on a large number of mineral claims held by these parties in British Columbia's Highland Valley, approximately 400 km northeast of Vancouver (Fig. I). Cominco 's ownership of Valley Copper was gradually increased over the years bot h through shares gained for exploration expenditures and through shares purchased on the open market. By the mid- 1970sCominco' s interest in Valley Copper exceeded 80%.ExplorationExploration from 1964 to 1969 led to the discovery of a massive porphyry copper depo sit now known as the Valley orebody. A claim boundary divided the deposit with 80% of it on Valley Copper claims and 20070 on claims held by Bethlehem Copper which was already mining adjacent copper orebodies. During the period when the Valley ore body was discovered, exploration by other companies resulted in the discovery of the large Lornex and Highrnont deposits nearby. The stage was now set for the Highland Valley to become an important copper-producing area (Fig. 2)."

Jan 1, 1986

By Kenta Suzuki, Toshiya Anami, Daisuke Shimosaka

"In an Al-Mn alloy heat exchanger fin stock, the effect of annealing conditions for as-cast and 0.1%Zr addition on recrystallization behavior is investigated using metallurgical analysis. Refinement of post-brazed recrystallized grains in fin stocks with Zr addition are suppressed for long-time annealing. In 0.1%Zr fin stocks, there was a decrease in the number of fine a-Al(Mn,Fe)Si dispersoids for pinning of sub grain and grain boundary. In addition, relatively homogeneous distribution of Al3Zr dispersoids was observed with increasing annealing time in as-cast. Homogeneous distribution of Al3Zr dispersoids can have a major effect on pinning of sub grain and grain boundary during brazing heat treatment. The homogenous distribution of fine dispersoids prior to brazing heat treatment is effective in causing the suppression of refinement of post-brazed recrystallized grain structure in aluminum alloy fin stocks.INTRODUCTIONAl-Mn based alloys are widely used as fin stocks in automotive heat exchangers because of their superior mechanical properties, braze ability, sagging and so on. In particular, coarsening of recrystallized grain structure is beneficial to avoid erosion, and achieve excellent sagging resistance (Lee, Yoon, Kim & Jung, 2002). For resisting grain coarsening, the alloys should contain a dense and homogeneous distribution of fine dispersoids to retarder crystallization (Humphyreys& Hatherly, 2004). It has been demonstrated that addition of Zr to Al-Mn alloys can shift recrystallization to higher temperatures because of the distribution of fine Al3Zr dispersoids in matrix(Pokoba, Cieslar& Lacaze,2012). According to Tohma, Asanoand Takeuchi (1987), coarsely recrystallized grain structure was obtained in 3003alloy with Zr addition after heat treatment. However, fine Al3Zr dispersoids are usually heterogeneously distributed because of segregation during casting and low diffusion rate of Zr in aluminum. Therefore, a homogeneous distribution of Al3Zr dispersoids can be achieved through long-time precipitation annealing(Jia, Hu, Forbord& Solberg, 2008)."

Jan 1, 2018

By D. Yuan, L. Yan, R. Kalanchey, M. J. Collins, I. M. Masters

Pressure oxidation tests have been conducted by Sherritt for a refractory gold-silver project located in China. The feed contained 39 g/t Au and 970 g/t Ag; the major gold-bearing minerals were pyrite and arsenopyrite. Since the feed contained a significant amount of silver, which can be refractory to cyanide leaching after pressure oxidation due to the formation of argentojarosite, the test program included investigation of methods to enhance silver recovery. The "lime boil" process proved successful and was incorporated into the flowsheet. Gold extraction from the lime boil product solids was 95 to 98%; silver extraction was up to 94%.

Jan 1, 2011

By L. A. Homeniuk, R. Bonnar

"The Fond-du-Lac uranium deposit is located on the northern rim of the Athabasca Basin. The uranium mineralization is, for the most part, confined to the Athabasca Group, which is underlain by pre-Helikian metamorphic rocks of the Western Craton.The deposit is characterized by a remarkable train of mineralized glacial erratics which led to the original discovery. The mineralization is present as a ""high-grade"" core and a diffuse ""low-grade"" aureole. The ""high-grade"" core occurs as a stockwork of steeply dipping pitchblende veins which strike N 50°E. Hematite, siderite and secondary silicate are also abundant. The ""low-grade"" aureole contains uraniferous goethite, argillaceous material and rare carbon buttons. Recent alteration to coffinite has taken place along the margins of pre-existing ore minerals.The ""high-grade"" core is 390 m long and 10 to 40 m wide, and is surrounded by an irregularly shaped zone of ""low-grade"" mineralization with a similar length and a width of up to 350 m.Comparing the Fond-du-Lac deposit to other unconformity-type deposits, several important differences can be noted:1. Ninety per cent of the ore is above the unconformity, in the Athabasca sandstone.2. The deposit is not associated with underlying graphitic rocks or a major structure.3. The clay-rich alteration zone is not extensive around the Fond-du-Lac deposit.Although there are differences with other Athabasca unconformity-type deposits, the high-grade portion below the unconformity suggests a common origin.The ore deposit is postulated to have been formed from uranium-bearing solutions which entered the stockwork of fractures. Following the reduction in part of these solutions by pre-existing carbonaceous matter and pyrite and/or chemical reaction with pre-existing hematite, deposition continued as a result of decreasing temperature and pressure. Subsequently, minor supergene redistribution of the uranium has taken place."

Jan 1, 1982

By L. A. Homeniuk, R. Bonnar

"The Fond-du-Lac uranium deposit is located on the northern rim of the Athabasca Basin. The uranium mineralization is, for the most part, confined to the Athabasca Group, which is underlain by pre-Helikian metamorphic rocks of the Western Craton.The deposit is characterized by a remarkable train of mineralized glacial erratics which led to the original discovery. The mineralization is present as a ""high-grade"" core and a diffuse ""low-grade"" aureole. The ""high-grade"" core occurs as a stockwork of steeply dipping pitchblende veins which strike N 50°E. Hematite, siderite and secondary silicate are also abundant. The ""low-grade"" aureole contains uraniferous goethite, argillaceous material and rare carbon buttons. Recent alteration to coffinite has taken place along the margins of pre-existing ore minerals.The ""high-grade"" core is 390 m long and 10 to 40 m wide, and is surrounded by an irregularly shaped zone of ""low-grade"" mineralization with a similar length and a width of up to 350 m.Comparing the Fond-du-Lac deposit to other unconformity-type deposits, several important differences can be noted:1. Ninety per cent of the ore is above the unconformity, in the Athabasca sandstone.2. The deposit is not associated with underlying graphitic rocks or a major structure.3. The clay-rich alteration zone is not extensive around the Fond-du-Lac deposit.Although there are differences with other Athabasca unconformity-type deposits, the high-grade portion below the unconformity suggests a common origin.The ore deposit is postulated to have been formed from uranium-bearing solutions which entered the stockwork of fractures. Following the reduction in part of these solutions by pre-existing carbonaceous matter and pyrite and/or chemical reaction with pre-existing hematite, deposition continued as a result of decreasing temperature and pressure. Subsequently, minor supergene redistribution of the uranium has taken place."

Jan 1, 1982

By B. Stettner, J. Asante, S. Abraham

The levels of nitrogen in steel produced in various metallurgical vessels vary significantly. For example, the tap nitrogen levels in steel produced in the BOF are around 4Oppm, as compared to 70-100ppm in both DC and AC electric arc furnaces. Given the pressing need to reduce nitrogen levels in steel to satisfy customer demand, IPSCO Inc. has gained considerable experience in controlling nitrogen levels in steel over the course of the last three years. Hence, a cost effective process has been developed through an intensive nitrogen control program from steel melting in the EAF through to the continuous slab casting stage. This paper describes the practices employed at each stage of the steelmaking process that have enabled IPSCO Inc. to reduce and control nitrogen levels in steel.

Jan 1, 2004

By V. A. Preto

The Rexspar uranium deposit is located approximately 5 kilometres south of Birch Island, B.C. Three separate zones of commercial-grade uranium mineralization mineable by open pit have been outlined. Uranium and fluorite-celestite mineralization occur in a trachytic member of alkali-feldspar porphyry, lithic tuff, tuff breccias and pyritic schist conformably interlayered with a succession of strongly deformed greenschists and fragmental rocks that are, in large part at least, of volcanic origin. The age of these strata is not precisely known, but they are considered as part of the possibly Mississippian Eagle Bay Formation. Commercial-grade uranium mineralization is always associated with fluorphlogopite-pyrite replacement of the trachytic unit and is contiguous to, but separate from , a zone of ore-grade fluorite mineralization. In all zones, ore occurs in lenses of variable thickness and lateral extent, which lie parallel to the schistosity of the trachytic rocks and surrounding greenschists. The principal radioactive minerals at Rexspar have been identified by other workers as uraninite, uranothorite, bastnaesite, torbernite and metatorbernite. Considerable amounts of thorium oxide and widespread rare earths have been reported from all three radioactive zones. The geology of the deposit suggests that the trachytic rocks represent a highly differentiated intrusive-extrusive system in which fluorphlogopite, pyrite, fluorite and uranium-bearing minerals were deposited late in the evolution of the system by deuteric, volatile-rich fluids. The considerable amounts of thorium and widespread rare earths associated with the uranium tend to support the thesis that this element is of primary origin rather than secondary.

Jan 1, 1978

By G. Zárate, G. Tapia

Anglo American Chile has been doing copper concentrate leaching studies at the laboratory and small pilot plant scale since 1992. Among the processes evaluated are bacterial leaching and pressure leaching using Mantos Blancos, Salobo Project and Quellaveco Project concentrates. Late in the nineties, it was decided to focus the research on pressure leaching, either medium or total pressure oxidation. Preliminary scouting tests were run with Mantos Blancos concentrate samples during 2000, which were repeated during 2003 together with samples of Los Bronces and El Soldado concentrates, in order to define the most suitable concentrate for running a pilot plant campaign at AARL, which was carried out in two campaigns, a first one from November 2003 through January 2004 and a second one during April 2004. Mantos Blancos was the selected concentrate and the laboratory and pilot plant results are discussed in this paper together with some preliminary economic estimates.

Jan 1, 2004