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By P. Homola, M. Karlík, M. Slámová

"Aluminum sheets (AA1199, AA8006, and AA5754) were processed by accumulative roll-bonding (ARB) in the temperature range from 20 to 350°C. The microstructure of the sheets was characterized by means of scanning and transmission electron microscopy and electron backscattered diffraction. Mechanical properties were monitored by hardness measurements and tensile tests. Increasing strain (number of ARB cycles) led to incremental development of lamellar microstructure with a decrease of the spacing between high-angle grain boundaries in the normal direction of sheets. ARB process produced an important increase of strength while maintaining thickness and relatively high ductility, without accenting of the anisotropy of mechanical properties of sheets. The level of hardening decreased with the processing temperature and at 300 and 350°C ARB caused even the softening of the material due to the recovery of the deformed microstructure or partial recrystallization during heating to ARB processing temperature.INTRODUCTION Accumulative Roll Bonding (ARB) is a technique of grain refinement by severe plastic deformation (SPD) proposed by Saito et al. (1999). One ARB cycle consists in sheet cutting, surface treatment, stacking of two pieces, heating (optional), and rolling with 50% reduction in thickness. Since the sheet thickness remains unchanged by this cycle, ARB processing can be repeated as many times as desired. The goal of ARB is to impose an extremely high plastic strain on the material, resulting in structural refinement and strength increase without changing specimen dimensions. After several cycles, ultra-fine grained (UFG) materials with high strength and relatively high ductility are produced. An advantage of this method is that it does not require any special equipment as other SPD methods such as equal channel angular pressing (ECAP) (Valiev & Langdon, 2006), high pressure torsion (HPT) (Valiev et al., 2000), or cyclic extrusion and compression (CEC) (Richert et al., 1999), but only a conventional rolling mill and so it is seen as an economically viable and industrially scalable processing route. ARB processing has been successfully applied to various kinds of metallic materials at room or elevated temperatures (Tsuji, 2005). Besides processing single metals and alloys, ARB has also been used for creating ultra-fine grained and nanograined metallic composites (Wu et al., 2010; Qu et al., 2014)."

Jan 1, 2018

By Free. Michael L.

Crushing ore prior to heap leaching enhances mineral liberation and creates fine particles that may require agglomeration to avoid permeability problems during leaching. Conventional modeling is relatively successful in describing general fluid flow and extraction in heaps. However, most models do not adequately account for the effects of mineral liberation and exposure or the effects of agglomeration, curing, and loading on heap leach performance. This paper will discuss methods to account for mineral liberation and exposure as a function of comminution. It will also discuss methods for incorporating liberation, exposure, and mineral locking as well as curing and fluid flow in heap leach modeling. It will also provide information regarding agglomeration and the effect of loading in heap leach modeling.

Jan 1, 2014

By K. Schimann, H. D. Knipping, J. P. Fouques

"The Cigar Lake uranium deposit, in the Athabasca area of north Saskatchewan, was discovered in May 1981 by Cogema (Canada) Ltd., as operator of the Waterbury Lake Joint Venture.The deposit, which is devoid of direct surface expression, is located at the unconformity between the Lower Proterozoic (Aphebian) Wollaston Group meta-sediments and the Middle Proterozoic (Helikian) Athabasca sandstone, at a depth of 410 m to 450 m below surface.At the end of 1984, the deposit had been defined by 105 mineralized holes over a length of 1800 m and a width of between 25m and 105m. It has the shape of flat-lying /em 5 m to 30m thick and shows a remarkable longitudinal and lateral continuity from the information obtained to date. A well defined bulge of the unconformity underlies the mineralized zone over its entire length.The deposit appears to be controlled by an east-west trending structure within which a particular rock facies (""augen gneiss'') has developed in the graphitic metapelites of the Wollaston Group. It is surrounded by a strong alteration halo affecting both sandstone and basement, characterized by extensive development of Mg-AI rich clay minerals (illite-chlorite). The mineralization is hosted principally by the Athabasca sandstone, and consists mainly of uraninite and sulfa-arsenides of nickel and cobalt. Numerous geochemical and geophysical surveys have been carried out in the Cigar Lake area, and although no specific geochemical or geophysical anomaly can be directly associated with the mineralized body, there may be locally a good coincidence.However, a combination of several methods proved extremely useful in interpreting the regional geology and defining the drilling targets within the favourable areas.Although the Cigar Lake deposit shows many similarities with several classical deposits of the Athabasca region, it is characterized by the intensity of its alteration processes and the presence of massive, extremely high grade mineralization.At the end of 1984, the global geological reserves estimated by geostatistics on the main mineralized ""pod"" of the deposit amounted to 110,000 metric tonnes of uranium at an average grade of 12.2% U, with a precision of 25% at the 95% confidence level."

Jan 1, 1986

By D. Lascelles, J. A. Finch, E. El-Ammouri

Flotation separation is expected to be related to the degree of dispersion of the pulp. For instance, highly aggregated systems may show reduced selectivity, reduced entrainment and increased flotation rate. In an attempt to test the impact of aggregation on flotation, we have taken advantage of the effect of Mg ions. Using combinations of Mg2+ and pH gave a wide variation in aggregation of several Cu-Zn ores (measured by settling rate) and corresponding flotation response was determined by batch tests. The trials were conducted on-site at Louvicourt and Agnico-Eagle. In a majority of cases a similar trend in aggregation and flotation selectivity (grade at given recovery) was observed. At Louvicourt, improved selectivity with increasing aggregation at pH 10.5 was found. At Agnico-Eagle, an analogous association between aggregation and selectivity was observed at pH 11.5. It is suggested that aggregation influences particle entrainment, the increased effective particle size reducing gangue recovery and hence improving selectivity.

Jan 1, 2004

By K. Niboucha, M. Zergoug, S. Brick-Chaouch, H. Houali

"Corrosion is an electrochemical process that causes degradation and deterioration of various steel works (pipelines, drains, cisterns) whether they are buried, immersed, or not. Worldwide, we estimate that corrosion destroys a quarter of the annual production of steel at a rate of 5 tons per second. Several techniques are used to protect against corrosion. Among these processes, Cathodic protection, which is regarded as the best technique to assure the protection of steel, works against this phenomenon. This is achieved either by a system of reactive anodes, or by the technique of impressed current protection or other techniques. Before any installation of cathodic protection, a preliminary study and pre-evaluation of certain parameters must be made. In the present work, we will present an example of dimensioning of an installation of cathodic protection by imposed current of a pipeline using solar energy, where we discuss the following items:•,Evolutions of the potential as well as current along the pipeline and their respective expressions deduced from the laws known as telegraphists;•,Range of protection (potential of protection along the pipeline);•,Influence of the isolation resistance of the coating on the range of protection;•,Effect of the aging of the coating and its influence on the current of protection."

Jan 1, 2005

By E. F. Evoy

"The Gunnar uranium deposit was within metasedimentary rocks of the late Archaen Tazin Group. These rocks were intensely altered by albitization so that the immediate host to the ore consisted dominantly of albite, and by the subsequent introduction of calcite. The ore consisted of disseminated pitchblende and uranophane in a pipe-shaped breccia zone. Oxidation of the ore was more intense near surface than at depth, but there was no near-surface enrichment.IntroductionThe Gunnar Mine site is on the tip of Crackingstone Peninsula, on the north shore of Lake Athabasca, Province of Saskatchewan, Canada. The peninsula forms the southern part of the Beaverlodge mining area. The ore consisted of disseminated pitchblende and uranophane in brecciated metasedimentary rocks of the Tazin Group, and the deposit was characterized by extreme albitization and subsequent carbonatization of the host environment.Production from the mine began in 1954 and the ore was depleted by 1963. In that interval the deposit yielded about 5 million tonnes of ore containing about I. 75 kg/tonne U3O8. It was mined initially from an open-pit and subsequently from underground; the open-pit contributed about 55% of total tonnage. Uranium was recovered by atmospheric leaching in sulphuric acid, ion exchange concentration, and precipitation with magnesia.This paper is based on studies made during the productive life of the mine and is concerned primarily with pre-ore alteration of the rocks containing the deposit, and with the ore mineralogy."

Jan 1, 1986

By D. MOORE, A. REINSBAKKEN, A. J. Sinclair

The Gypo quartz vein lies near Oliver, British Columbia, and was quarried between 1955 and 1968 for decorative chips. The vein is one of many quartz veins hosted by the Late Jurassic Oliver Plutonic Complex, specifically by the porphyritic quartz monzonite phase of the pluton. The vein has a known length of 155m and a thickness of 46m. It strikes east-west and dips at 60 degrees to the south. Mineralogy is predominantly quartz with minor pyrite, muscovite, fluorite, calcite, apatite and manganese; trace amounts of chalcopyrite, pyrrh otite, marcasite and molybdenite also are present. Quartz in the vein is zoned. A thin grey quartz zone found near the margins of the vein fades gradually into white quartz, which comprises over 95% of the vein. Late-stage boxworks cut earlier mineralization, particularly fluorite, which occurs as pods in a zone fairly close to the hanging wall. Sulphide minerals are found in a centrally located zone in the quartz vein. The hanging wall of the Gypo veins is altered only slightly, but thefootwall is altered extensively to a greisen of muscovite and grey quartz. Evidence suggests that early in rhe vein development, the adjoining country rock was feldspathized. As grey quartz and muscovite was deposited, a period of intensive greisenization and fracturing occurred which so weakened the rock that a central block of greisenized country rock foundered. This provided the open space in which the vein was deposited.

Jan 1, 1984

By Waldbillig. D.

A baseline of the poisoning effect of hydrogen sulfide (H2S) fuel impurities on solid oxide fuel cell (SOFC) anodes was developed using polarization testing. After the baseline behaviour was characterized, tests to study the effect of various H2S concentrations on the rate and amount of cell voltage degradation and recovery were performed. Attempts were made to improve the rate and amount of recovery by various methods. Testing was very reproducible, but significant electrochemical performance degradation was seen after all H2S poisoning tests even at an H2S concentration of 0.1 ppm. Degradation is initially quite rapid, but after a period of time the rate of degradation levels off. After poisoning was complete, the H2S flow was stopped and the cells were allowed to recover. Some recovery was seen after poisoning, but cell performance was never fully recovered.

Jan 1, 2005

By Nathalie Gauthier

Bien que le système de ventilation du Puits Penna soit de taille imposante et que plus de $30M y seront engloutis pour son développement, aucun budget spécifique n?avait été préalablement consenti pour refroidir l?air acheminé aux places de travail dans la partie profonde de la mine. Le système de ventilation a été conçu en deux étapes distinctes : le réseau du haut de la mine lequel dessert jusqu?à 1550 m de profondeur et le réseau du bas de la mine (de 1550 m à 2200m) qui a été créé ultérieurement. Le réseau inférieur a été imaginé de façon à acheminer l?air frais directement au gisement et de permettre l?évacuation aux extrémités afin de rejeter l?air chaud immédiatement après l?avoir utilisé. Au total, lorsque le réseau de ventilation sera complété, plus de 670 m3/s d?air sera véhiculé dont jusqu?à 495 m3/s pour la partie inférieure de la mine considérant une capacité totale maximum de 710 m3/s en utilisant la mine adjacente.

May 1, 2003

By Kai Bartram

The successful application of color sorting machines has established sensor-based sorting in the mineral industry in recent years and is considered today as a significant innovation in processing technology. However, we are only at the beginning of (market) introduction. New sensor systems have been developed, which exploit material properties such as electrical conductivity, magnetization, molecular structure, thermal conductivity etc. This opens up new exciting preconcentration and upgrading possibilities for many applications such as nickel, gold, copper and other ores as well as for industrial minerals, diamonds and other gem stones.

May 1, 2009

By R. Hagiwara, S. Kobayashi, K. Yasuda, T. Nohira, K. Kondo

To establish a process for the electrochemical recovery of rare earth elements from used magnet scraps, the electrochemical formation of RE-Ni alloys in molten NaCl-KCl-RECl3 salt at 973 K was investigated. Cyclic voltammetry and open-circuit potentiometry indicated the formation of several phases of RE-Ni alloys. The formation potential for each RE-Ni alloy phase was determined from the results of scanning electron microscopy and X-ray diffraction of alloy samples prepared by potentiostatic electrolysis of a Ni plate electrode at various potentials. The optimum electrolysis conditions for the separation of Nd, Dy, and Pr are discussed.

Jan 1, 2014

The successful application of color sorting machines has established sensor-based sorting in the mineral industry in recent years and is considered today as a significant innovation in processing technology. However, we are only at the beginning of (market) introduction. New sensor systems have been developed, which exploit material properties such as electrical conductivity, magnetization, molecular structure, thermal conductivity etc. This opens up new exciting pre-concentration and upgrading possibilities for many applications such as nickel, gold, copper and other ores as well as for industrial minerals, diamonds and other gem stones.

Oct 1, 2009

By Bradford C. Wesstrom

An overview of the challenges encountered at the Freeport McMoRan El Paso Copper Refinery with higher concentrations of antimony electrolyte will be shared. The observations will cover the detrimental effects on copper starting sheets, commercial cathodes and anode slimes. The study will show negative effects on quality and productivity. Experimental work will utilize a test cell to study the effects on electrolytes by different Antimony, Arsenic concentration and anode molar ratio. Best practices will be shared for producing high quality cathodes while effectively managing the detrimental effects of higher antimony electrolyte.

Jan 1, 2014

By Shigeru Sarata

A wheel loader is one of the main loading machines in open pit mines. The authors have been conducting research and development on autonomous operation of loading by a wheel loader. The most common loading method by a wheel loader is the ?V shape? path method. The loading operation consists of cycles of scooping from the pile, traveling to the dump truck, loading on the dump truck and return traveling to the scooping point for the next cycle. The traveling path includes a switchback in the middle of the path. The moving direction of the loader is changed at the switchback point. From observation of V shape path loading operations by experienced human operators, it seems that they control the bucket position between the scooping point and loading point on a shorter path for higher productivity. A new path planning method is proposed this paper, whereby a point on the center of the tip of the bucket is controlled moving from the initial point and the final point. The motion of the controlled point is generated by the wheel steering the wheel loader. The controlled point is moved along the direction to the final point; however, the motion and mechanism of wheel loader have restrictions, such as the velocity of the loader, the steering angle, and the steering angular velocity. Because of these restrictions, the path of the controlled point is not a straight line between the initial and final points. When this control method is applied between the scooping and the dumping points directly, the planned path is not stable in the leaving wing of V shape path. Therefore, the initial position of the wheel loader is set at the switchback point, then two approach wings to the scooping and the dumping points are made. The whole planned path is obtained by connecting the two paths. The shape of the planned path is strongly affected by the position of the switchback point, as well as the scooping and the dumping points. By simulation of path planning at different switchback points with the combination of the scooping and the dumping points, the paths for more effective loading are determined. The results of the simulation are presented in the paper.

Aug 1, 2013

By R. B. Harkness

Many of us are familiar with the history of oil in the Province of Ontario, but for the benefit of those who have never heard the story I will repeat it. In 185 7 J. H. Williams, of Hamilton, an old-country Scotchman, who had the advantage of experience gained from the primitive methods used for refining the oil collected at seepages in Roumania, heard of the "gum beds" along Black creek in Enniskillen township, Lambton county. He erected a small plant in the bush and refined illuminating oil, where the village of Old Springs now stands. The labor of collecting this thick ?gummy substance from the sluggish water of the creek, prompted him to dig a well, the next year ( 1858), in the hope of obtaining a greater quantity. When his excavation reached a gravel bed on top of the rock, oil, resembling "lubricating oil of commerce", rose several feet. Several of these wells were dug and his refining business flourished. The following year the Drake well, in Pennsylvania, was drilled into rock, resulting in an oil find which encouraged one James Shaw to make a similar attempt on Black creek. With a spring-pole drill he completed his well in the spring of 1861 to a depth of 160 feet, and at that depth struck a gusher that flowed uncontrolled for several days. Great excitement followed and the village of Oil Springs had a mushroom growth. The Petrolia field was discovered in 1865. Lick followed up the Thames with a spring-pole rig testing the formations along that river and discovered the original Bothwell field in 1865. During the sixties wells were drilled in many counties in southwestern Ontario.

Jan 1, 1924

By Charles G. Kemsley

IN view of the truly remarkable development of special steels for special purposes, the mining industry has for years looked forward to a time when steel makers would come forward with a product which would be an improvement over the straight carbon steel which has always held the field for drilling rock. In order to avoid making changes in conventional shop practice, the industry has perhaps been too insistent upon obtaining a water hardening steel which could be handled in the blacksmith shop by long established methods. As early as 1932 or 1933, an oil-hardening tool-steel of the one per cent carbon, plus chrome, plus molybdenum type was applied to hollow drill steel. It was known as a hard as well as a tough steel, and one that, theoretically, should give a good account of itself as a rock drill, if properly heat-treated; and so it has proved in actual trials. There were numerous deterrents which retarded adoption of this steel. For several years there has been a constant improvement in the drilling qualities of the straight carbon steel, and, considering the higher unit price ? of the alloy, there has been considerable doubt in the minds of some mining? men as to what advantage there might be in the use of alloy over straight carbon for hollow drill steel. The alloy being an oil-hardening steel, its adoption meant having two kinds of steel in the mine, for a time, and that spelled trouble, unless some positive means of identification was adopted. The hardening and forging ranges of alloy steel being narrow also made necessary much closer control over these operations if poor results were to be avoided. These thoughts undoubtedly prevented its use becoming wide-spread, for, as a matter of actual record, less than fifteen per cent of all the hollow drill steel used in Canada today is alloy.

Jan 1, 1942

By C. Okay Aksoy

In Turkey, the increasing demand for lignite has necessitated an increased emphasis on both lignite production and recovery. This emphasis has resulted in a gradual increase in the application of the retreat longwall mining method for both its product recovery and productivity benefits. Also, in order to maximize the recovery of the natural resources and to increase total production, it is necessary to take advantage of underground reserve before abandoning the mine. This means that at the end of the life of the mine, the main drift safety pillar and the shaft pillar will generally be extracted. This investigation a preliminary study of the stability of the main drift and the shaft at the Hustas Mine as the safety pillars are extracted. In this study, field surveys belonging to the underground colliery of Hustas Co. in Soma have been investigated with the help of LAMODEL working under the Laminated Displacement Discontinuity principle for the models calibrated as a results of physical model and finite element analyses. The convenience of Laminated Displacement Discontinuity Analysis has been researched in such studies. The results out of the models have been coherent with the previous studies.

May 1, 2004

By Takashi Nakamura, Atsushi Iizuka, Yong Fan, Etsuro Shibata

Magnetic separation of precipitated magnetite as iron resources in copper slag is one of the potential effective ways to recycle the slag. It is preferable to convert molten fayalite slag after copper smelting process to magnetite slag via oxidation. With a TTT (Time-Temperature-Transformation) diagram, the crystal composition of the slag obtained after air isothermal oxidation could be estimated through a designed cooling path. The crystallization behaviors concerned with molten oxidation was studied for better understanding of the trade-off relationship between magnetite and hematite during molten heat treatment. Moreover, a brief consideration was implemented of the reaction mechanism.

Jan 1, 2014

By G. E. Agar, W. B. Kipkie

"This paper deals with the prediction of locked cycle flotation results from data developed from individual batch tests. A postulate is made that the distribution of material in a separation stage is determined by the chemical conditions and the flotation time and that this distribution can be characterized by split factors which are constants for a fixed set of conditions. With this premise, it is demonstrated that a steady state balance can be calculated for a circuit.Although the necessary equations can be solved algebraically, a computer program was written that uses an iterative tec1nique to arrive at the steady state balance. The program is written so that a variety of circuits can readily be simulated.A number of examples are examined to demonstrate the validity of this simulation procedure. The sensitivity of the material balance to changes in the split factors was examined. Data developed from different flowsheets is presented on sulfide ores, on copper-nickel separation and on silver flotation,"

Jan 1, 1978

By B. Dubreuil, J. -M. Lalancette, D. Lemieux

Arsenical bearing deposits are posing an increasing challenge for the mining industry. In particular, mineral processing of arsenical sulfidic ores for base and precious metals recovery tend to produce problematic arsenical tailings. This arsenic being present as sulphide or oxide, tends to dissolve, contaminating surface and underground waters. To meet the environmental regulations, it is often required to stabilize the arsenic in a more insoluble form. Dundee Sustainable Technologies has developed a new patented technology using vitrification of the arsenic oxide in an economical way, giving a stable solid, well below the environmental regulations upon leaching. This technology involves oxidation of As (III) to As (V), by using a low cost natural oxidizer and transformation of the produced arsenic oxide into calcium arsenate, which is not volatile at the melting temperature of the glass. This technology would be advantageously applied on most cases around the world where sulphide concentrates are oxidized in a fluidized bed or smelted.

Jan 1, 2014