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By B. K. Gorain

Barrick' s Buzwagi copper-gold deposit in Tanzania comprises oxide, saprock and sulphide mineralized zones averaging approximately 0.058oz/t gold, 0.13% total copper and 0.03% cyanide-soluble copper. A comparative evaluation of the project based on two potential flowsheet alternatives is presented. The first flowsheet included a gravityconcentration and carbon-in-leach (CIL) plant. The second flowsheet was based on a Gravity-Flotation-CIL plant, which proved to be more economically robust. Selective flotation of copper minerals to produce a saleable copper concentrate proved to be challenging. Detailed characterization of the Buzwagi deposit was carried out through understanding of ore mineralogy, mineral liberation, floatability and selectivity, reagent chemistry and regrinding issues. With this insight, a flotation concentrate of greater than 25% Cu was achieved, recovering a significant amount of copper minerals and tellurides. The overall economics of the project improved significantly with the addition of flotation. Leach tests on gravity and flotation tailings showed an overall increase in gold recovery of approximately 6% for a Gravity-Flotation-CIL plant compared to that for a Gravity-CIL plant.

Jan 1, 2007

By G. H. McKay

AT the Eagle mine, near Gilman, Colorado, where the Empire Zinc Company have installed an underground mill, transportation problems were comparatively simple. A railway siding on the Denver and Rio Grande railway is equipped with an unloading dock or platform at the portal of their service incline adit to the mill. This 18-degree incline is approximately 600 feet long from the unloading track to the head of the mill skipway. For the Big Missouri mill, upwards of 2,500 tons of material and equipment had to be trucked from tidewater at Stewart, B.C., a distance of 21 miles to the Big Missouri camp at elevation 2,800. From that point, this freight had to be moved either over or through the Big Missouri ridge, rising to elevation 3,450, to its final location 800 feet from the surface between elevations 2,150 and 2,350. Immediately after leaving the government dock at Stewart, the road crosses the International boundary line into Hyder, Alaska, and then follows a water grade for eleven miles along the lower stretches of the Salmon river. leaving the river, the road climbs for two miles before crossing back into British Columbia territory at Silver Heights, and then continues for another mile and a half to where the Big Missouri road branches off from the main road to the Premier mine. For a distance of four miles from the junction of the roads, the Missouri road is very narrow, with many sharp curves and with irregular up and down pitches and grades up to 25 per cent until it reaches the Summit. From there on, a fairly easy grade leads a mile and a half to the end of the road on Joker Plats. In winter, the last stretch of road is subject to heavy snow drifting, especially through a narrow funnel-shaped gulch, known as 'The Gap', where the snow may pile up to a depth of over twenty feet.

Jan 1, 1938

By G. Forté, R. Girard

The Alcan Bayer Process Experimental Centre (BEC) is an essential development tool for the Bauxite & Alumina researchers at the Alcan Arvida Research and Development Centre in Jonquiere, Quebec. Between the laboratory tests and the industrial prototypes or the industrial applications, the BEC is a key element for technology transfers. The Bayer process is the extraction of aluminium oxide (or alumina) from the bauxite ore. The Bayer Experimental Centre's history and flowsheet are presented. The major pieces of equipment are described. Safety and design considerations are presented. Finally, examples of applications, double digestion and pressure decantation, are briefly described.

Jan 1, 2004

By Davis. B. R.

There are a number of hydrogen storage systems proposed for automotive applications. However, all of the current suggestions fall short of the DOE targets for storage density and volumetric density. The DOE has suggested that only through radically new ideas will a practical solution to hydrogen storage for automotive applications be realized. This paper provides some background in chemical hydrogen storage and discusses roadblocks to the implementation of some proposed technologies.

Jan 1, 2005

ABSTRACT The inevitable uncertainty in modelling spatial variables decreases as more data become available. This reduction depends on the properties of the variable being modelled. Spatially continuous variables show less uncertainty for a given spacing than erratic variables. A geostatistical simulation based approach is developed to quantify the relationship between uncertainty and data spacing. Reference realizations are sampled to condition additional realizations and quantify uncertainty. The procedure is automated, making it straightforward to consider sensitivity and different geological domains. A case study of the relationship between uncertainty and data spacing for net oil sands thickness data from northern Alberta is presented. _ KEYWORDS Simulation, Sampling,

Jan 1, 2013

In the flotation of a copper ore, entrainment of fine silicate and iron sulfide gangue minerals resulted in poor copper concentrate grade. In the cleaning stage, rejection of these gangue minerals was particularly difficult due to severe mechanical entrainment when the rougher concentrate was ground to 10 µm. To reduce gangue entrainment, polymeric depressants were tested. The rationale being that with the use of such polymeric depressants that also possess flocculation power, not only minerals-to-be-depressed can be made hydrophilic, but their particle size can also be enlarged. In this manner both the "genuine" flotation and the mechanical entrainment can be reduced. An effective polymer to reduce entrainment of silicate gangue mineral in sulfide flotation was identified from bench flotation tests conducted on single minerals. It was then applied to the flotation of a copper-gold ore confirming the beneficial role of the polymeric depressant in the reduction of fine gangue entrainment.

Jan 1, 2007

By M. E. Holuszko

Although there is no widely accepted rigorous definition of handleability, the handling coal characteristics often referred to as handleability define whether a coal has the ability to flow unhindered through the processing and transportation systems. The handleability may be severely affected if fine coal particles tend to aggregate. In the pelletization process, the rolling action of the drum is applied to bring the individual particles into proximity with each other so that they can aggregate and form pellets. Because of apparent similarities between these two processes, the pelletization tests are carried out in parallel to the handleability tests in this project, and the pelletization results are used to explain coal handleability properties.

Jan 1, 2004

By D. Van Tonder

ABSTRACT The comparative economics of ion exchange and direct precipitation have been analyzed by developing indicative CAPEX/OPEX models for typical alkaline leach uranium circuits. An agitated tank ore leach application is considered, comparing resin-in-pulp and direct precipitation as recovery options. Capital and operating cost estimates are derived from rates and factors used in recent studies and projects. The analysis showed the main economic drivers to be the ore grade and resin loading. The resin loading is impacted by the prevalence of competing ions, especially chloride. At resin-in-pulp solution chloride concentrations below 3 g/L and uranium grade below 640 g/t U3O8, resin-in-pulp is more economical, whereas at chloride concentrations above 3 g/L, direct precipitation is more economical.

Jan 1, 2012

By R. G. S. Mussi

An inclined cooling plate is utilized as a modification in the compocasting process of magnesium alloy and the mechanical properties of the composites obtained are studied in this work. Based on crystal separation theory, molten AZ91D is poured onto an inclined plate in order to produce solidification nuclei inside the fluid metal, and is mechanically stirred while reinforcement is added. Particulate SiC was utilized as reinforcement in quantities varying from 0 to 15%vol. Dispersion of the reinforcement was observed by macro and microstructure analysis. SiC was properly mixed into matrix until 15%vol., and Vickers hardness tests were carried out for the composites produced. Results obtained for hardness were shown to increase with reinforcement addition and comparable to those of traditional compocasting. Utilization of Inclined Cooling Plate produced good inclusion and homogenization of SiC through an AZ91D matrix, at lower temperatures and shorter times than traditional compocasting.

Jan 1, 2006

By M. Medraj, M. A. Arafin, D. P. Turner, P. Bocher

In this study, the kinetics of isothermal solidification during TLP bonding of Inconel 625 and 718 superalloys with nickel based multi-component filler alloy BNi-2 have been studied through a combination of direct experimentation and mathematical modeling in order to determine the effect of process variables and, thus, to optimize the process. The predicted isothermal solidification completion times from the boron diffusion model and migrating solid/liquid interface model were in good agreement with the experimentally determined values and, they were found to be significantly less than those of other nickel superalloys with different nickel based filler alloys. Further, significant reduction of holding time was observed with increasing bonding temperature and with decreasing joint gap. No significant grain growth in the base metals has been observed in the temperature range being investigated (1325 - 1394K).

Jan 1, 2006

By Imane Benhamed, Jaouher Diouani, Laurent Cassayre, Florent Bourgeois, Carine Julcour-Lebigue, Université de Carthage

The attrition-leaching process aims at improving leaching performance when formation of passivation layers at the surface of leached particles is a severe limiting factor, as discussed recently by Julcour and coworkers (Julcour et al., 2015). This paper proposes a geochemistry-based modelling scheme for deriving the window of possible operating conditions for the attrition-leaching process to match the properties of the processed ore. The rationale is that the attrition-leaching process maintains the surface of reacting particles in an unpassivated state by continuous mechanical removal of surface leach layers, so that the process reactions can be modelled from thermodynamic equilibria throughout the duration of the process. The strength of the proposed modelling approach is that it bridges the gap between the properties of the ore and the process operating conditions. The present paper exemplifies the proposed process modelling route for derivation of the attrition-leaching process operating conditions in the context of the leaching of silicate ores, matching model predictions against controlled laboratory experiments. It is shown how thermodynamic modelling, when used in conjunction with a solid knowledge of the phases present in the system, can assist with deciding upon suitable process operating conditions. As an example, this firstprinciple modelling approach predicted that steel grinding medium would be converted into siderite (FeCO3) under a wide range of operating conditions, which led to questioning this initial choice of grinding medium for the attrition-leaching process under mineral carbonation conditions. It is emphasised that the same approach could be applied to ores of greater economic significance.

Jan 1, 2016

The JKRBT (JK Rotary Breakage Tester) is a newly developed impact breakage testing device for rapid ore breakage characterisation, and has recently been commercialised after a three year comprehensive validation study, involving five major mining companies and six industrialised JKRBT units deployed worldwide. Comparisons of breakage mechanisms and characterisation data between the JKRBT and the Drop Weight Tester (DWT) indicate that, despite the differences in the breakage modes, the JKRBT can provide statistically similar A*b parameters, by using a data reduction procedure which takes into account the difference in the number of contact points, strain rate and potential for secondary breakage. Feedback from the validation sponsors has indicated higher productivity and better repeatability of the JKRBT compared with the DWT. This better precision, combined with the JKRBT?s wider particle size capability and wider specific energy range, provide a more powerful tool, ideally suited to rapid mapping of ore hardness in geometallurgical and comminution applications.

Jan 1, 2012

By W. A. Gow, V. F. Harrison, H. H. Mccreedy

A semi-continuous bench-scale, countercurrent-decantation system, in which the ore was moved countercurrently to the flow of leaching solution, was used to conduct acid-leaching tests on uranium ore with the aid of bacteria. This method, which involved a low degree of agitation, was successfully applied to extract uranium in practical amounts and at practical rates. The acidity of the leaching solution was the main variable investigated in the bench-scale tests done at the Mines Branch, Ottawa. Over 90 11er cent of the uranium was extracted in a six-stage system. The results suggest that this technique could be ap-plied in the utilization of bacterial oxidation and leaching as a method for treating Elliot Lake uranium ore.

Jan 1, 1969

By M. Mohammadijoo, J. B. Wiskel, D. G. Ivey, S. Kenny, H. Henein

Cold-wire tandem submerged arc welding (CWTSAW) has recently been developed as a novel welding technique to replace the conventional tandem submerged arc welding (TSAW) process and improve the productivity of pipeline manufacturing. The process involves two electrodes with arcs and one electrically cold electrode. Since heat-input of the welding process is a key factor affecting the properties of the weld metal (WM) and the heat-affected zone (HAZ), and the additional cold-wire affects the heat introduced to the weldment, it is of interest to investigate property and geometry changes in the WM and HAZ when a cold-wire is added to the welding process. In the current research, the CWTSAW process is investigated and optimized by correlating the main welding parameters with the micro-hardness of the WM and HAZ and the geometry of the weld, i.e., the bead width (BW), penetration depth (PD), reinforcement area (RA) and coarse grained heat-affected zone (CGHAZ) area. Three statistical and mathematical methods are employed to optimize the CWTSAW process in terms of the mechanical properties and WM and HAZ geometry of a typical microalloyed steel used for pipeline manufacturing.

Jan 1, 2015

By J. H. C. Scrimgeour, T. Toong, R. E. Hamilton

"The principles involved in the use and application of mathematical models as an aid to the development of advanced process control computer systems are described briefly. This is followed by a brief survey of known models of this kind for the simulation of mining industry processes.The main part of the paper describes a dynamic model of the flotation process developed by Canadian General Electric. Using flotation rate constants for each species of mineral and gangue, the model provides a numerical solution of the differential equations describing cell behaviour. The cell mode] is used repeatedly as a subroutine in the •over-all-plant model. The features of the cell and plant models are described.Simulation runs from the plant model show stream .assays and other indications of plant behaviour printed typically in 1-to 10-minute steps for several hours of •Operation following typical disturbances such as changes in feed rate or reagent addition rate. The simulation can :Show expected behaviour for both uncontrolled and computer-controlled plants."

Jan 1, 1970

By M. A. F. Fedikow, D. A. Baldwin, C. Taylor

The Agassiz Metallotect and the Johnson Shear Zone represent two metallogenetic fea tures located within the northern and outhern belts, respectively. of the Aphebian-aged Lynn Lake greenstone belt in northern Manitoba . Numerous gold occu rrences are associated with these two regional features . The tratabound Agas iz Au-Ag deposit with 2.9 million tonnes of 5.2 g/tonne Au and 11.8 g/tonne Ag. occurs within the Agassiz Metallotect. The stratigraphic sequence characterizing the Agassiz Metallotect comprises interlayered ox ide. silicate and sulphide facies iron formations, biotite-rich and siliceous siltstones. and a high Mg- i-Cr basaltic rock that ha previou ly been identified as tholei itic picrite. These rocks can be traced in outcrop and by their INPUT and gradiometric signature for 65 km. The Johnson Shear Zone is an ill-defined 35 km long zone of strucwral disruption that crosscuts volcanic. sedimentary and intrusive rocks and contains numerous vein-type gold occurrences. Both of these metallotects are characterized by their low level of exploration activity and as a result offer excellent residual exploration potential. Rock, basal till and vegetation geochemical techniques applied in the vicinity of the Agassiz deposit indicate the presence of trace element dispersion halos associated with the mineralization. The halos define an exploration target larger than the mineralized zone. Gold occurrences within the two metallotects are described with emphasis on the Agassiz Au-Ag deposit . A wide range of gold occurrence-types is documented including syngencticstratabound , epigenetic-replacement and epigenetic-quartz vein .

Jan 1, 1986

By R. Khettabi

The mechanical, thermal and bioproperties of titanium alloys allow their wide use in different industries. Compared to aluminum alloys, titanium alloys are very tough, making them that much more difficult to machine than aluminum alloys. Most studies conducted on these types of materials have mainly covered and made comparisons in terms of cutting speed, cutting force and mechanical properties. Recently however, their sustainability and environment parameters have begun to attract significant interest, and it has been found that machining processes generate particles that can be harmful for health and the environment. In this paper, particle emission is investigated during the turning of the titanium Ti6A14V and 6061-T6 aluminum alloys.

Jan 1, 2011

By A. Panteleyev, C. S. Ney, R. J. Cathro, A. Sutherland Brown

The general distribution of metal deposits in the Canadian Cordillera can be related to its tectonic evolution. The Canadian Cordillera is naturally divisible into five longitudinal tectonic belts within which rocks are broadly similar in type, age and history. From west to east they are the Insular, Coast Crystalline, Intermontane, Omineca and Eastern Marginal belts. Seven classes of metal deposits in the Canadian Cordillera are defined and their characteristics described. These classes are skarn, porphyry, massive sulphide, stratiform, magmatic, copper in basic lavas, and vein deposits. Maps showing the distribution of medal and metal-group concentrations serve to illustrate the relations in space and time between mineralization and geologic evolution.

Jan 1, 1971

A newly developed damage model was used in the study of rock fragmentation mechanisms involved in crater blasting. Simulations show that at the detonation of the explosive charge, a crushed zone around the explosive charge is formed due to compressive failure and then a strong pressure wave is sent out forming a pressurized ring that propagates at the dilatation wave velocity. As the pressurized ring leaves the crushed zone, two tensile stress components perpendicular to the radial stress are developed in response to the action of the radial pressure, causing tensile failure and forming a damage zone around the charge. The formation of this damage zone is quite independent of the depth of the explosive charge provided there is no interference by the reflection from the free face. When the pressurized ring reaches the free face, it is reflected there and causes rock failure on the ground surface that forms another damage zone. Under the simulation conditions, it is revealed that the depth of charge is a factor controlling the relationship between the two damage zones. At a depth smaller than the optimum, the two damage zones coalesce into one and there is excessive rock breakage; otherwise, the two damage zones tend to isolate from each other with the increase in the depth of charge. Calculations of fragmentation indicate that the average fragment size increases and the uniformity of fragments decreases when the depth of charge increases as observed in practical blasting.

Jan 1, 1998

By C. Juers

Laboratory chromate coating was applied on AM50 and AZ91D alloys and compared to phosphate-permanganate one. Evaluation of the corrosion behaviour was performed using electrochemical DC and AC methods in ASTM water D1384-87. This electrolyte was chosen because it was moderately aggressive and found to give generally good correlations with long period exposure results in atmospheric conditions. Electrochemical impedance spectroscopy was used to determine more accurately the corrosion rates from the analyses of the high frequency capacitive loop. Anodic polarization was applied in order to evaluate the pitting resistance of the different coatings. These results were correlated with weight loss data evaluated from experiments performed by immersion tests in ASTM water D1384-87 and climatic cyclic chamber tests.

Jan 1, 2006