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By Jr. Fackler

The ionization potentials of gaseous Group 11elements are similar, with Au(0) being 1.5 eV greater than the next highest member of the group, Cu(0). The ionization potentials are all very much greater than the alkali metals, making these ?coinage? elements rather unreactive to chemical oxidation. Ionization from the first oxidation state shows a different pattern, with Ag(I) being the most difficult of the Group 11 ions to lose an electron. Gold(I) is noble and only normally oxidized in the presence of strongly coordinating ligands such as thiols or cyanide. Gold(I) compounds are 2-, 3- and 4- coordinate, with 3-coordinate species generally showing visible photoluminescence under UV excitation. Dinuclear Au(I) compounds with strongly coordinating S or C ligands can be oxidized to form isolable metal-metal bonded Au(II) compounds which are often readily isolable. Many have been structurally characterized. T he ease with which electrons are lost from closed shell dinuclear sp ecies (with anti-bonding M-M interactions) increases when metalmetal bonded compounds are formed. T his observation was made by our group with oxidative-addition studies of dinuclear gold(I) ylide complexes. It was superbly demonstrated recently by Cotton?s group who reported the isolation and characterization of a dinuclear closed shell transition metal species which is more readily oxidized than cesium. Trinuclear Au(I) pyrazolates, TR(pz), carb eniates, TR(carb), and benzylimidazolates, TR(bz), are well known and undergo electron loss through oxidative addition forming Au(I,III) mixed valence species and ultimately trinuclear Au(III) species. Au(II) species are absent from isolation in these oxidations. These carbeniates and benzylimidazolates also are excellent bases for metals ions such as Tl(I) and Ag(I). The acidic, neutral trinuclear compound [Hg(C6F4)3]3 also interacts with these bases. We have also shown that the neutral organic pi acids C6F6 and TCNQ form stacked pi-acid pi-base products with the trinuclear Au(I) compounds. In this paper, the structure of the octafluoronaphthalene acid-base product will be described. It displays a feature not observed previously in that the product is photoluminescent with a bright yellow emission. The 3.5 ms lifetime is very long and reminiscent of the long lifetimes observed by Balch for the stacked methyl,methoxy Au(carb). The electrochemical oxidation of tetragold(I) clusters, [Au4(form)4] have been studied in 0.1 M Bu4NPF6/CH2Cl2 at Pt working electrode at different scan rates. Three waves are obtained at 0.75, 0.95, and 1.09 V vs Ag/AgCl at scan rate 500 mV/s. The potential of the three reversible waves is independent of the scan rate in the range 50 mV/s to 3 V/s. The current at the third wave is larger than those at the first two waves. These tetranuclear species app ear to be effec tive catalyst precursors for the oxidation in air of CO. Introduction. The electronic structural relationships of the coinage elements and the alkali metals are similar in the sense that each have a [closed shell]ns1 configuration, yet their ionization energies (Table) and chemistries are clearly vastly different. The Group 11coinage elements have an underlying nd10 level immediately below the ns1 level. Unlike the alkali elements, ionization leaves the filled d electron shell the next accessible for further ionization. The coinage elements are all relatively ?noble?, much less reactive to environm ental conditions than the alkali metals. With the coinage elements, oxidation becomes very much dependent upon the types of ligand s availab le to bo nd to the ionized state.

Oct 1, 2003

By B. J. Fryer, R. P. Taylor

"As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth element s (LREE), reflecting their high pH, low fluid/rock ratios, and the dominant role of CI- complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F - and CO, 2- become important in metal (e.g. Mo, W,) transport through complexing, and their activity in the hydro thermal fluids is illustrated by mobilization of the heavy rare earth elements (HREE).The relative involvement of CI- versus F - versus CO32- in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F' and CO32- in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geo chemistry, particularly when integrated with fluid inclusion and isotope studies, can provide (1) an effective method for identifying the physicochemical controls of metal transport and (2) a useful criterion for elucidating metal distribution."

Jan 1, 1983

By Seong-Taek Lim

Recently, 7xxx aluminum alloys have been evolved into new variants for thick semiproducts which have low amount of 2nd phases and low quench sensitivity. Commercial 7xxx alloys, especially in the thick forgings made of big ingots, often entail microstructural inhomogeneities and concurrent poor mechanical properties due to limited heating ranges and slower quench cooling. In this study, high strength aluminum alloy 7175 and 7050 are adjusted as an attempt to control the equilibrium phases (M-, T- and S-phase) to have optimum microstructure for the thick forging applications. The effects of the relative content of (Zn, Mg, Cu) on the evolutions of the coarse equilibrium phases, hardening response and resultant mechanical properties are investigated. Equilibrium phases (M,T,S) are evolved depending on the constitutional effect, primarily the change of Zn:Mg ratio, and cooling rate following solutionizing. The formation of the T- and S-phases is effectively controlled, and M-phases are homogeneously precipitated in the adjusted (dilute and high Zn:Mg ratio) alloys. It provides extended heating range and lower quench sensitivity than conventional alloys. The attempts ensure the microstructural homogeneity and improved properties, and is expected to be uniquely applicable in 7xxx thick forgings.

Jan 1, 2004

By Francisca San Martin, Tomas Vargas, Willy Kracht

"In Cu-Mo deposits it is usual to find considerable amounts of pyrite (FeS2). When processing this kind of ore by flotation, pyrite is rejected using lime to increase the pH to alkaline conditions (pH ~10.5). In the case of using seawater without pre-processing, i.e., raw seawater, the lime consumption increases dramatically and the recovery of molybdenite drops due to the precipitation of magnesium hydroxide on its surface. In order to avoid these negative effects, alternative ways of depressing pyrite should be considered.The current work introduces the use of Acidithiobacillus ferrooxidans, bacteria commonly used in bioleaching, as an alternative to depress pyrite in seawater flotation. The paper presents the results of biodepression in three systems: fresh water, water with added sodium chloride at 35 g/L (which corresponds to the salt concentration in seawater ) and seawater. The results show that it is possible to bio-depress pyrite with A. ferrooxidans in natural seawater pH (7.8-8.2). A similar behaviour is observed when running the experiments in fresh water, and in water with sodium chloride added.INTRODUCTIONWater is a scarce but essential resource for human development. The main reason for this scarcity is that, although 70% of the earth's surface is covered with water, only 3% of the total is fresh water and an important part of this water is frozen, so that only 1% of fresh surface water can be used for human activities. In Chile, most of the mining activity is concentrated in the north of the country, located in the Atacama Desert, considered the world's driest desert. That is why some mining companies have chosen to use seawater in their processes. For example, Esperanza (Antofagasta Minerals), and Sierra Gorda (KGHM International) use raw seawater in their flotation processes."

Jan 1, 2016

By G. R. McMeekin

"THE TOPIC suggested for my contribution to this Symposium was ""Lead-Zinc Smelting - 40 Years of Pollution Control"". The history of the development of smelting industry at Trail and the control of sulphur dioxide could make quite an interesting historical study. However, in the field of environmental control, the public is not particularly interested in what you did yesterday, but rather what you are doing today and what you are planning to do tomorrow. I can't fault this approach, but because there are some subject lessons that history can demonstrate, I would like to tell enough of the story (under three headings) to bring a focus on matters of contemporary concern in regard to public relations and ecology. The three general headings suggested are: (1) time before the capture of by-product sulphur; (2) the capture of sulphur; and (3) the ecological and public relations conclusions from these."

Jan 1, 1972

By C. Bazin

"Discrete transfer functions which use the grinding circuit feed tonnage to predict mass flowrates at reagent addition points in the flotation circuit were calibrated using a dynamic grinding/flotation simulator. Predicted values are multiplied by g/t ratios to calibrate reagent flow. The transfer functions are currently integrated into the distributed control system at Les Mines Selbaie.INTRODUCTIONThe development of adequate tools for the control of flotation processes is a continuous challenge. Since the early 1970's there have been numerous publications dealing with practical applications of flotation process control. A review of that literature shows that basic feedback and feedforward controls are the two preferred strategies for flotation processes. Some advanced control schemes started to emerge (e.g. Zaragoza and Herbst, 1988). Feedforward and feedback aim at reducing the effect of the following flotation process disturbances (e.g. McKee, 1991):0 Changes in throughput;0 Changes in feed grade;0 Changes in particle floatability (size, liberation, surface oxidation ... );0 Deliberate changes of set-point;Feedforward strategy acts on manipulated variables, mainly reagent addition, to attenuate the effect of disturbances such as changes of feed rate and grade. The feedforward strategy is driven by measurements of disturbances. Feedback control acts to compensate unmeasured disturbances, such as ore floatability, and to bring process variables to targeted set-points of concentrate or tails grades. The feedback control action is driven by set-point error, caused by either a deliberate change of set-point or unaccounted disturbances.This paper proposes a way to improve feedforward control schemes by addition of a simple model of solids transportation. The feedforward strategy considered in this paper is of ratio type, i.e. the manipulated variable is changed according to a predefined ratio between this variable and the measured disturbances. A typical example is the ratioed reagent addition to mass flow of ore."

Jan 1, 1993

By Samuel Frimpong

The interaction of oil sands with a ground articulating pipeline (GAP) system has been simulated with the dynamic model established in this work by combining the multi-body and soil dynamics with the Automatic Dynamic Analysis Mechanical Systems (ADAMS) software. Mathematical models governing the interaction of the GAP system with the oil sand terrain have been modeled based on the theory of multi-body and soil dynamics. These models consist of GAP track-oil sand contact model for generating the contact force between oil sands and track and load-deformation oil sand model for capturing the dynamic behavior of oil sands. A virtual prototype has been created and simulated in the ADAMS environment. The simulation result of the effect of load on oil sand deformation indicates that maximum deformation value increases non-linearly with load varying from 0 to 60t. This study provides a solid foundation for further research and the GAP technology development.

May 1, 2004

By C. H. Stockwell

RICE LAKE-BERESFORD LAKE area, situated 100 miles northeast of Winnipeg (Figure 1), is Manitoba's foremost gold mining district, although it is exceeded in gold production in the Province by the Flin Flon base-metal mining district. At present, the area is producing at the rate of about one and three-quarter million dollars annually, almost entirely from the San Antonio and Gunnar mines. The total production to date is about $14,000,000. Of this total, over $7,000,000 has come from the San Antonio mine, over $2,000,000 from the Gunnar mine, about $4,000,000 from the Central Manitoba mine, and the balance from several smaller properties. The writer has led Geological Survey parties in the area for the past four summers. The present paper gives a summary of the results of this work and also includes the findings of C. S. Lord, who was in charge of a party for one year. Much valuable information was obtained from earlier published reports on the area and from officials of mining companies, to whom the writer is indebted for their kindly co-operation. It is impossible in this short paper to give proper credit to the earlier workers or to discuss certain points o disagreement between their conclusions and those presented here. For further information the following references may be consulted.

Jan 1, 1940

By Ryan L. Veenstra

This paper presents a modelling study of a cemented paste backfill in an underground stope. The model was developed to help provide a better understanding of what is happening in the stope during the filling stage of the stope. In order to do this, the model incorporates the paste rise rate, stope geometry, and time-dependent input parameters. This paper looks at the effect of geometry in two parts. The first part compares a series of simple rectangular stope models. These models differ in size both in two and three dimensions. The second part compares the results of four 2D models together and then to the field instrumentation data. Part of this section introduces the geometry and instrumentation within the test stope.

Jun 1, 2012

By K. V. Konigsmann

"The results of Mr. Klymowsky's research confirm the essential role played by oxidation products in the flotation of base metal sulphides. They invite a discussion on the subject of aeration which I may open by a brief description of the development and current practice of aeration. The first installation of pre-flotation aeration in Canadian milling practice was undertaken during the years 1928 and 29 at the then new Noranda Mill. C.G. McLachlan and his collaborators demonstrated that the flotation differential between chalcopyrite and iron sulphides was enhanced by aeration in soda ash alkaline pulps. The ores treated contained more than 80 per cent sulphides. It was proposed already then that the products of mineral oxidation assisted copper and retarded iron sulphides, at least pyrrhotite flotation. The concentration of thiosulphates was used as a measure of the progress of oxidation. Several papers by C.G. McLachlan elaborate on this subject.The aerator was also used as classifier since it was held that aeration, i.e. controlled oxidation, should go hand in hand with creation of new mineral surfaces. Grinding mills and aerators were placed in closed circuit. Figure 1. This aeration was essential for successful separation at Noranda.Following the application of aeration at Noranda the technique was applied to existing mills in N.W. Quebec. Impressive improvements in concentrate grades and recoveries were obtained. It was observedthat the zinc flotation benefitted from aeration as much as the preceding copper float. In the late forties and fifties the aerator classifier was installed in new mills associated with the Noranda group. A diagrammatic sketch of the Quemont flow-sheet (figure 2) may serve as a typical example."

Jan 1, 1973

By André Desbiens, Jocelyn Bouchard, René del Villar

"The metallurgical performance of the column flotation process is determined by the concentrate grade and recovery. Although the former can be continuously measured using an on-stream analyzer, the latter must be estimated by a material balance calculation based on seldom verified steady-state assumptions. Consequently, the automatic control and optimization of flotation columns should be performed using secondary variables having a strong influence on the metallurgical performance, such as froth depth, gas hold-up or bubble surface area flux and bias. The aim of this paper is to present a model-based automatic control strategy using froth depth and bias measurements obtained from virtual sensors developed at Laval University. Preliminary pilot plant results on two-phase (water– air) and three-phase system (water – minerals – air) will be presented and eventual industrial implementation of such a strategy as well as the possibility of achieving effective real-time optimization from bias and froth depth measurements will also be discussed.INTRODUCTIONFlotation columns have been widely studied and used in mineral processing for about twenty years. Although a great deal of work has been accomplished to understand the influence of different variables such as froth depth (H), bubble surface area flux (Sb) and bias (Jb) on the metallurgical performance, the measurement of some of these variables is still difficult to be performed – except at the laboratory level – because in most cases, no commercial device yet exists.As a result of this, it is almost impossible to achieve neither efficient control nor optimization of the process at the industrial level, even in open-loop operation. This paper aims at presenting a simple control strategy of froth depth and bias. Description of the sensors used to achieved measurements, preliminary pilot plant results for froth depth control, eventual industrial applications and possibilities for process optimization are also treated."

Jan 1, 2003

By M. C. Pietrobon

"A common problem in assessing the applicability of laboratory flotation data is determining how closely conditions during laboratory testing of the ore matches those that occur in a plant. Typical laboratory based investigations do not consider factors such as water quality, pulp temperature and the pulp chemical environment during both grinding and conditioning on laboratory flotation performance. Disregarding these important factors may seriously compromise the validity of conclusions based solely on laboratory experimental results. Furthermore, considering these factors during the flowsheet design stage in the development of new ore resources may reduce financial risk associated with building a new plant. A methodology is described here which embraces these factors in an attempt to bridge the gap between laboratory and plant. The methodology should be considered a vital first step in all laboratory based experimental programs and has implications for fundamental studies on the flotation behaviour of single minerals. This methodology increases the confidence with which findings of laboratory based studies can be transferred to the plant and highlights the effect of variables which may be accessible to manipulation in the plant.Pulp chemical parameters, such as pulp dissolved oxygen demand, pH, Eh, mineral oxidation and solution composition were manipulated in the laboratory by adjusting the duration of gas purging after grinding, the process water input and pulp temperature. A key finding was that matching of the laboratory pulp chemistry to the plant pulp chemistry was dependent upon oxidation after grinding. In turn, mineral oxidation was dependent upon the pH in grinding, water composition and the duration of oxygen purging after grinding. The methodology closely matched the dissolved oxygen demand and surface chemistry of laboratory and plant pulps."

Jan 1, 2002

By J. T. Fyles, C. G. Hewlett

"THE TOWN OF Salmo, rail centre for the Salmo lead-zinc mining district, is in southeastern British Columbia 26 miles by road east of Trail an about the same distance south of Nelson. The belt in which the mines occur is a few miles east of Salmo and extends about 6 miles north of the town and 17 miles south and southwest to the International Boundary. The belt includes the H. B. mine of The Consolidated Mining and Smelting Company of Canada, Limited, the Jersey mine of Canadian Exploration Limited, the Reeves MacDonald mine, and the Jack Pot property of New Jersey Zinc Explorations Limited.Since 1949, the Jersey and Reeves MacDonald mines have produced most of the lead and zinc in the district. From 1949 through 1954 these two mines together produced a total of 233,134 ounces of silver, 87,659,399 pounds of lead, 215,708,856 pounds of zinc and 475,397 pounds of cadmium. This amounts to more than 80 per cent of the total production of lead and 95 per cent of the total production of zinc from the district since the first recorded production in 1906. Reserves at the largest properties amount to several million tons of ore containing 4 to 7 per cent combined lead and zinc. Several prospects are potential producers.Regional StructureThe main structural units in the Salmo area are outlined in Figure I, and the major rock units of the stratigraphic column are listed in the following table. The lead and zinc deposits are replacements in a highly deformed limestone formation near the base of the Laib group, and all mineralized zones are on the south and east side of structural unit 2 (see Figure I)."

Jan 1, 1949

By A. Boehm

"For recycling LD slag into the steel making process, the phosphorous containing calcium silcate phases have to be removed from iron oxide phases. One possible technical solution could be magnetic separation in a wide range of susceptibilities from ferromagnetic to paramagnetic. To check the feasibility of magnetic separation the distribution of the magnetic susceptibility in size classes as well as the liberation of the phosphorous containing phase were evaluated by a new method combining two dimensional physical property analysis with QEMSCAN analysis. The particle size classes of energy controlled comminution products were subdivided into fractions of defined magnetic susceptibility using a hand magnet of well known field properties (pick up method). On the one hand the susceptibility classes were wet assayed on the other hand analyzed by QEMSCAN followed by data evaluation using iDiscover 5.3.1(FEI), which was adapted to the data structure of two physical properties (size and magnetic mass susceptibility). The results allow the comparison of mass based (3D) cumulative distribution of grades from the wet assays with the area based (2D) distribution from QEMSCAN analysis, in order to control a systematic (size dependent) stereological error for this special type of material. As the physical separation property forms a crucial parameter the results from the liberation analysis by QEMSCAN can be interpreted more profound with respect to an expectable separation result. Once the various mineral compositions of the particles are assigned to the physical properties the Henry Reinhardt chart serves to predict the best possible separation result and thus the feasibility of a separation technique.INTRODUCTIONThe two Austrian steel plants operated by voestalpine AG produce about 650,000 t (voestalpine 2014) of LD slag in the course of steel production from pig iron according to the basic oxygen process blowing oxygen in the converter by an oxygen lance. The process is also known as the Linz Donawitz (LD) steelmaking process. By the addition of lime (CaO), carbon, phosphorus, silica, manganese and sulfur, which are present in the molten pig iron, shall be oxidized and bound in the slag either as oxide or silicate phases, or leave the slag in the gaseous phase (CO). The average chemical composition of the investigated LD slag is given in table 1."

Jan 1, 2016

By A. Roca, G. Ríos, I. Ruíz, M. Cruells

Flash Smelting Furnace (FSF) hot dust-laden is cooled in a waste heat boiler (WHB) and then dedusted in electrostatic precipitators (ESP’s) before being treated, together with the Peirce Smith Converters off-gases, in the sulfuric acid plants for SO2 removal. FSF dust is sulfated by SO2 and O2 in the WHB. Typically, 70% of the dust from the FSF drops in the WHB while the remainder is caught in the ESPs. The collected dust is recycled to the FSF for Cu recovery. Some smelters have developed hydrometallurgical treatments to recover Cu from the dust; impurities, such as As and Bi, are bled as leach plant residues. This paper presents a study (laboratory scale), of leaching the FSF dust, generated in Atlantic Copper Smelter using the weak acid bleed from the gas scrubbing/cooling section (GSCS) of sulfuric acid plants. Leaching was performed with 0.5 mol L-1 sulfuric acid concentration, 60ºC, and a solid/liquid ratio 1/3. After leaching, H2O2 was used for arsenic and iron oxidation. pH was adjusted for precipitation of arsenic and iron as scorodite or as scorodite and arsenical jarosite. The precipitation was carried out at 95ºC during 3-6 h. Liquids after precipitation are suitable for subsequent treatments of electrolysis. INTRODUCTION The copper smelter dusts are usually recirculated totally or partially to the flash furnace. This practice increases the amount of impurities feeding the furnace. Some authors have developed processes for treatment of these materials for copper and zinc recovery and for arsenic, antimony and bismuth inertization. The processes for the treatment of copper smelter dusts can be pyrometallurgical (Yu, 1987; Carter, Vance, Aldridge, Zaw, & Khoe, 1994; Fu, Jiang &Wang, 2000), hydrometallurgical, or mixed processes (Yin et al, 1992; Mulale, Mwema, & Mashala, 1999; Gorai, Jana, & Khan, 2002). Hydrometallurgical processes have been extensively studied and, in some cases, applied to an industrial scale. The most important chemical reagent proposed for leaching the dusts has been sulfuric acid (Roman-Moguel, Plascencia, Pérez, & Garcia, 1995; Gabb, & Evans, 1997; Larouche, 2001; Morales, Cruells, Roca, & Bergó, 2010; Cáceres, Cruells, Morales, & Roca, 2012; Ecometales, 2013; Yang, Fu, Liu, Chen, & Zhang, 2017). Processes developed in alkaline media, and in some cases with the presence of sulfide, have also been carried out (Gabler, & Jones, 1988; Morales, Hevia, & Cifuentes, 2009; Alguacil, Garcia-Diaz, Lopez, Rodriguez, & Alonso, 2013), as well as by using a bioleaching process (Massinaie, Oliazadeh, & Seyed Bagheri, 2006; Bakhtiari, Atashi, Zivdar, Seyedbagheri, & Fazaelipoor, 2011).

Jan 1, 2019

By Morris Wong

"An antimony-bearing gold ore was studied in a cyanide slurry containing 7 -20 ppm dissolved oxygen. 1 g/L NaCN at pH 9.5 and 48 hours retention time is required to extract 94 % of the gold from the 90 % minus 200 mesh ore by conventional cyanidation at a 7 ppm O2. As oxygen concentration was increased to 20 ppm, the conditions required to extract the same amount of gold were: 0.25 g/L NaCN, 16 hours retention time and 80% minus 200 mesh. Compared to conventional cyanidation, oxygen-enriched leaching was shown to reduce retention time by three times and cyanide consumption by four times. The kinetics of gold dissolution related to the dissolved oxygen concentration in slurry was expressed by following equation:XAu = 100 * (Kt + I0) / (1 + Kt + I0)where XAu is the percentage gold extraction; t is the retention time; K and Io are the slope and the intercept of the plot of XAu I (100 -XAu) vs. t respectively. The values of Kand Io depend upon the concentrations of cyanide and oxygen, the fineness of grind and the origin of ore sample etc.. A preliminary cost analysis was also performed to justify the use of oxygenating slurries.IntroductionGeneral:It was proposed almost 149 years ago (Elsner 1846) that oxygen is required for the dissolution of gold in cyanide solution. However, little attention were paid to oxygen application in the gold milling industry during the following one hundred years. Due to the constraints of gold price, reagent costs, refractory ores, and environmental issues in the past decade, the oxygen enhancement in the cyanidation process was introduced to the gold milling industry for increasing operation efficiency, reducing production costs, and meeting the requirement of environmental standard.The advantages of oxygen-enriched cyanidation have been reviewed by several investigators (Hague 1992, Jara et al 1992, Henderson 1989, Loroesch et al 1988, Elmore 1987, Cathro 1963). Common to all conclusions are the following advantages."

Jan 1, 1995

By C. H. B. Leitch, T. N. MacAuley, R. L. Linnen, A. E. Williams-Jones

"The Trout Lake stockwork molybdenum deposit is temporally and spatially related to the emplacement of a late Cretaceous granodiorite-tonalite stock in southeastern British Columbia and contains an estimated 49 million tonnes grading O.I9% MoS2- No metal zonation patterns are apparent, with the exception of peripheral tungsten skarn, and exploration was guided largely by geological interpretation. It is typical of the granodiorite, or fluorine-poor type of molybdenum deposit. Molybdenite is contained within a quartz-feldspar vein stockwork and coeval dissemination in igneous (and less commonly metasedimentary) hosts. In general, molybdenite is strongly associated with alkali feldspars, but in detail it is intimately associated with incipient muscovite replacement of albite and K-feldspar; veins that lack feldspars are also typically barren of molybdenite. These textures suggest that fe/dspathic alteration (and precipitation in veins) was an important precursor to mineralization, and the occurrence of similar textures elsewhere (e.g. Henderson) suggest that early feldspathic alteration is important to the genesis of molybdenum deposits in general. Molybdenite deposition at Trout Lake was preceded by contact metamorphism, skarn and potassic alteration, and was overprinted by muscovite-ankerite (phyllic) alteration. Only moderate temperature changes are recorded by the metamorphic and alteration mineral assemblages (350°C to 450°C}; however, with time, fluids became increasingly more acidic and enriched in C02- In light of the intimate molybdenitemuscovite intergrowths, the decrease of pH probably exerted a major control on mineralization.IntroductionGranite-hosted molybdenum deposits can be classified in terms of the composition of the related intrusion, e.g., the granodiorite and granite types of Mutschler et a!. (1981), or the calc-alkaline, alkali-calcic, and alkalic types of Westra and Keith (1981). They have also been classified on the basis of their fluorine contents (Theodore and Menzie, 1984) with the fluorine-rich and -poor varieties roughly corresponding to granite- and granodiorite-type deposits, respectively. For economic reasons, most exploration and research has concentrated on the high-grade/large tonnage granite-type of deposit, exemplified by Climax. F1uorine-poor, granodiorite-type deposits are, however, the most common type in Canada and have been mined in the past (e.g., Endako). In this paper, the authors summarize the research that has been carried out on the fluorinepoor Trout Lake deposit (Boyle and Leitch, 1983; Linnen, 1985; Linnen and Williams-Jones, 1987; 1990) and use what has been learned to develop guidelines for the future exploration of fluorinepoor, granodiorite-type molybdenum deposits."

Jan 1, 1995

By C. Hari Manoj Simha, J. Gholipour, M. J. Worswick

Due to the high pressures involved in the hydroforming process, friction and lubrication play an important role and can affect formability of the material. Tubes of A1Mg3.5Mn aluminum alloy, of 76.2 mm (3 inch) outside diameter and 2-mm thickness were considered in this study. Three kinds of lubricants, Al070, Hydrodraw711 and water, were applied to the tubes and tubes were hydroformed to burst in a square shape die cavity. The key process parameters were recorded during the tests. An in-house Gurson-Tvergaard-Needleman (GTN) damage-based material model, implemented in LS-DYNA, was used to model the process and predict the formability of this material. The applied axial loads and internal pressures recorded during the tests were used in the computations. The effect of different types of elements (solid and shell) with different constitutive models (von Mises and GTN models) in predicting the strain distribution is studied. The GTN damage-based material showed a good ability to capture necking and displacement histories in this process. Both predicted and measured results showed that the lubricant with lower coefficient of friction can effectively increase the comer expansion.

Jan 1, 2006

By J. F. Archibald

A research effort has been undertaken, under Workplace Safety and Insurance Board of Ontario (WSIB) sponsorship, to characterize the support capabilities of conventional and innovative spray-on lining materials for mitigating dynamic failure effects created by simulated rockbursts. Conventional spray support media, such as shotcrete and fibrecrete linings, and a variety of new spray-on lining materials [thin, spray-on liners (TSLs)], typically polymer-type thin coatings, were subjected to simulated rockburst influence. For baseline comparison, conventional rockbolt and bolt-and-mesh support products were also evaluated. Observation of lining performance was undertaken through completion of field-scale support and rock detonation trials. Controlled blasting tests were conducted at the Queen’s University Explosives Laboratory to examine the effectiveness of the variety of surface coating agents for modifying dynamic rock spalling processes. All tests were performed upon largely undisturbed and homogeneous rock materials in highly repeatable fashion. All blasts were observed seismically and photographically to provide detailed information concerning rock motion, surface fracturing, ejected fragment motion and support liner survivability characteristics. These material comparison trials were performed to assess the relative effectiveness of a wide range of currently available area support techniques for suppressing hazards associated with dynamic rock ejection. The results of this study validate that thin, spray-on linings may be equally as effective, and often better, than conventional support materials at mitigating rockburst or like damage in highly stressed mine environments.

Jan 1, 2004

By V. Barranco, K. Yliniemi, A. Hubin, B. P. Wilson, D. Janas, M. Lundström, P. Hannula

Typical copper electrorefining electrolyte contains tens of grams of copper, some nickel and a wide variety of impurities. Some of these impurities comprise trace amounts of dissolved precious metals like Ag, Pd and Pt that currently are not fully exploited. This study presents an electrochemical method to recover precious metals via a combined electrodeposition-redox replacement (EDRR) process, where energy is used only to deposit copper during the ED-step, while the RR-step relies on the spontaneous replacement of copper by the precious metals (i.e. cementation). In order to conduct the recovery successfully, process parameters such as deposition potential (EDE), deposition time (tDE), redox replacement time (tRR) and the number of cycles (n) was adjusted. Investigations performed in synthetic electrolyte (40 g/L Cu, Ag = 10 ppm) proved the possibility to recover a high purity silver. Short deposition times (tDE) were found to result in small Cu particles that provided a suitably high surface area for silver cementation. In addition, experiments performed in real industrial electrolytes containing 44 g/L Cu and 54 ppb Ag (Boliden Harjavalta, Pori), demonstrated that EDRR could attain Ag recoveries of between 46–67% in an energy efficient, additive-free manner. INTRODUCTION The raw materials used in the state-of-art primary and secondary copper smelters contain mainly base metals, but also notable amounts of Ag, Pt and other precious metals. These valuable metals distribute mostly into the copper matte during the pyrometallurgical treatment (Tirronen et al., 2017) and end up into the cast anodes. During the electrorefining stage, metals more noble than copper such as gold and platinum, are not dissolved but enrich into the anode slimes. In contrast, silver may dissolve slightly and thus, minor chloride addition is used to retain silver in the slime as sparingly soluble AgCl. Moreover, other metals less noble than copper may also dissolve, such as nickel. Therefore the electrolytes used in electrorefining typically contain substantial amounts of copper, nickel and even arsenic as well as minor metals such as antimony and bismuth. In the Boliden electrorefinery these were reported to be in the magnitude of 51.2– 60.4 g/L of Cu, 10.9–15.8 g/L Ni, 7.2–15.9 As, 0.2–0.4 Sb and 0.1–0.4 Bi with an associated sulfuric acid concentration of 139–155 g/L (Lehtiniemi et al., 2018). Copper is the most noble of the dominating base metals in the electrolyte and is thus deposited on the cathode as 99.99% purity LME-A grade. Anode slimes are collected and subjected to precious metals treatment e.g. via pressure leaching—selenium recovery— Doré smelting—Ag refining—Au/Pt/Pd leaching and reduction process (Ludvigsson & Larsson, 2003). The Pori refinery, operating in Finland since 1941, not only produces 133 000 t Cu cathode and 2300 t nickel sulphate annually but also 66 t silver, 4.6 t gold and palladium and platinum (in year 2017).

Jan 1, 2019