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By B. K. Choi, G. E. Kim, S. Noh, T. K. Kim

Oxide dispersion strengthened (ODS) steel has been developed as the most prospective core structural material for next-generation nuclear systems because of its excellent high strength and irradiation resistance. In ODS steel, finely dispersed nano-oxide particles with a high number density in the homogeneous grains can be very attractive to achieve superior mechanical properties at high temperatures, and these favorable microstructures can be significantly changed using process parameters during the mechanical alloying procedures. In this study, the effects of mechanical alloying times on the microstructure of 10Cr-1Mo ODS martensitic steel were investigated. Pre-alloyed powders with Y2O3 powder were mechanically alloyed for various milling times using a high energy horizontal ball-mill apparatus (model: symoloyer CM20). Powder properties such as the mean particle size, size distribution, and crystallite size were evaluated. Uniaxial hot pressing was employed to consolidate the milled powders. The results of a microstructural observation after the MA and UHP processes indicated that the homogeneity of the martensitic structures was considerably increased with the longer milling time. It is thus concluded that the mechanical properties of the ODS martensitic steel are greatly dependent on the mechanical alloying times.

Jan 1, 2015

By R. R. Irrinki

Abstract -The Key Anacon deposit consists of four sulfide zones called, from south to north : Key Anacon No. 1, Key Anacon No. 2, Key Anacon No. 3, and Key Anacon Copper Zone. Massive sulfides of zones 1, 2, and 3 are underlain by rocks correlated with the Nepisiguit Falls Formation and are overlain by matie volcanic rocks correlative with the Boucher Brook Formation. In contrast to zones 1, 2, and 3, narrow northwesterly-trend.ing, copper-rich fracture zones occur within the Patrick Brook Formation. Sulfides in zone 2 occur as three mineralogical associations, namely: pyrite-chalcopyrite, pyrite-sphalerite-galerta, and pyrrhotite-sphalerite-galerta. The distribution of lithologies and en-echelon patterns of the three sulfide lenses of Key Anacon No. 2 zone are the result of F1 and F2 folding. Zone 2 is the most promising economically, with proven reserves of 1.11 million tonnes grading 0.2207o Cu, 3.47% Pb, 8.41% Zn, and 96 g/t Ag; the zone is open below a depth of 427 m.

Jan 1, 1992

By Andrea R. Gerson, Roger St. C. Smart, Russell Schumann, Joan E. Thomas, Warwick Stewart, Stuart Miller

Sequential Net Acid Generation (NAG) accelerated oxidation testing using peroxide was carried out on single sulfide mineral samples. The calculation of the nett acid production potential (NAPP) assumes that all the sulfide is present as pyrite and that dissolution results in a 2:1 ratio of H+:SO42-. NAPP as kg H2SO4/t is calculated as 30.6 x wt.% S present. To test whether this calculation is valid a NAPP* value was defined in which instead of using the wt.% S present for the calculation the wt.% S dissolved is used. Stoichiometric analysis of the dissolution products of the sulfide minerals as they would occur at pH 7 indicates, that in all cases, the ratio of H+:SO42- of 2:1 is viable. The NAG to pH 7 and NAPP* closely coincided for pyrite, bornite, chalcocite and covellite. For the three Cu-containing minerals, the NAG to pH 4.5 value was 0 as is predicted on the basis of the speciation likely to be present at pH 4.5. Acid generation is due to hydroxylation of the dissolved Cu between pH 4.5 and 7.0. The NAG to pH 7 and NAPP* values for chalcopyrite, arsenopyrite and pyrrhotite were in reasonable agreement but were not for either sphalerite or galena. Zn is not completely hydroxylated at pH 7 as is assumed by the calculation. For galena, surface analysis identified polysulfide formation on of the leach residue polysulfide. The formation of polysulfide is an acid consuming reaction. Therefore under conditions of accelerated oxidation the NAPP value is a reasonable estimate of the possible acid production in all cases except for sphalerite and galena. However, under conditions of less intense oxidation, for instance in columns, waste rock and tailings dumps, the formation of polysulfides is likely to be more widespread thus reducing the correlation between NAPP and the maximum possible acid production.

Jan 1, 2004

By Zoltan Hajnal

Magnetic studies have been carried out on 88 surface and 157 underground samples from the Coronation Mine area of northern Saskatchewan. The intensity of the surface samples was compared to trace element determinations from the same locality. A good correlation was found between the titaniferous constituent of the rocks and the intensity of magnetization. From the direction of the remanent magnetism, two virtual geomagnetic poles were determined -latitude 12° 54' North, longitude 158" 17' West; and latitude 23" 42' North, longitude 163° 45' West. The sulphide ore specimens showed anisotropic susceptibility characteristics. A relationship was found between the measured maximum susceptibility values of the ore specimens and the direction of the tectonic forces which are considered to have formed the structure at the Coronation mine. Introduction T HIS paper summarizes the results of a study of the magnetic properties of samples from well-known Precambrian formations. The observed data give information for an interpretation of the magnetic field conditions in Precambrian times. The high magnetic intensity values indicate the importance of the study

Jan 1, 1965

New Millennium Capital Corp. shall not be liable or responsible for any claim or damage, direct or indirect, special or consequential, incurred by the user arising out of the interpretation, reliance upon or other use of the information. Users should not rely on information for any purpose other than for gaining general knowledge of New Millennium Capital Corp. Although New Millennium Capital Corp. believes that its expectations reflected in these forward-looking statements are reasonable, such statements involve risks and uncertainties and no assurance can be given that actual results will be consistent with these forward-looking statements.

May 1, 2011

By Sadough vanini Ali

The silicon anisotropic wet chemical etching technique is widely employed for fabricating various microelectromechanical system (MEMS) structures for advantages such as simple etching equipment and its capability to fabricate special microstructures. In this paper, we consider a complete theoretical derivation of the analytical solution based on geometrical and kinetic aspects of step flow on any surface and with a mathematical method we derive new equation for calculating the microscopic etch rates of surface atoms for a new range of concentrations and temperatures. Furthermore, a novel equation is presented for the calculation of the microscopic activation energies for some typical surface atoms and a new comparison of activation energies between some atoms is made that divides atoms into three categories. The results demonstrate agreement with the experimental results.

Oct 1, 2011

By Gae On Kim, Ki Baik Kim, Suk Hoon Kang, Tae Kyu Kim, Sanghoon Noh

"Advanced radiation resistant oxide dispersion strengthened steel (ARROS) is being developed as a fuel cladding tube material for future nuclear reactor system applications. The research activities consist of advanced radiation resistant ODS steel development and fabrication technology development of ODS steel structural components. One candidate material with a chemical composition of (in wt%) Fe-10Cr-1Mo-0.5Mn-0.1V-0.25Ti-0.35Y2O3and was selected as representative materials, and this material was named as the advanced radiation resistant ODS steel (ARROSTM).On the basis of this ODS steel composition, an optimized fabrication process of structural components such as plates, sheets and tubes has been established through various process conditions in mechanical alloying, hot/cold working, and heat treatment processes. These R&D activities are expected to contribute to the realization of ODS materials in the future.INTRODUCTIONA sodium-cooled fast reactor (SFR) is being developed at the Korea Atomic Energy Research Institute (KAERI) with a view to economics, safety, reliability, and sustainability. The prototype Gen-IV SFR with a capacity of 150 MWe is under design, and this prototype reactor is scheduled to operate from 2028. For a commercial SFR system application, it is necessary to develop an advanced structural material having both high creep strength and irradiation resistance at high temperatures (Jeong, 2014). Oxide dispersion strengthened (ODS)steel is one of the most promising structural materials because of its excellent creep and irradiation resistance on the basis of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperatures under a neutron irradiation environment for a prolonged operating period(Kim, 2016). As the first step, several batches of ODS steel were designed and the candidate samples with a 2 kg scale each were fabricated by mechanical alloying, hot isostatic pressing and hot rolling processes. The mechanical properties of these samples were evaluated. Up to now, two candidate materials with chemical compositions of (in wt%) Fe-10Cr-1Mo-0.5Mn-0.1V-0.25Ti-0.35Y2O3 was selected as representative materials, and these materials were named as the advanced radiation resistant ODS steel (ARROSTM).The next step was to optimize the fabrication process of the ARROS compositions for in-core structural components such as the fuel cladding tubes of a SFR. An optimized fabrication process of fuel cladding tube with a composition of ARROS has been established through various process conditions in mechanical alloying, hot consolidation, hot/cold working and heat treatment processes. Joining technologies of the ODS steel tubes is being developed using solid-state welding such as magnetic pulse welding, friction stir welding and diffusion boding. It is expected that the development of ARROS will contribute to the realization of a commercial SFR with high economics and sufficient safety in the future. In this paper, the study of fabrication process of ARROS structural components is introduced."

Jan 1, 2017

By Lucas G. Thompson

My topic, "The Administration of Mineral Rights'.' is possibly an unusual one, as it deals with a subject upon which many of us have a more than passing interest, I thought ?it might prove consistent with the objects of this meeting, more especially as I propose to deal, not with those broad subjects of nation-wide importance which are often the subject'? of learned (and sometimes futile) academic discussion, but rather with problems in their practical light. To the scientist, the important question is What is it? to the technician, Can it be utilized? to the business-man, Will it pay? All three questions are important, and so quick has been the march of business on the heels of science? that the one question follows the other with astonishing rapidity and all three must be considered in the modern management of a mineral estate. A .good illustration of the force of this can be found in the recent advance of our knowledge of the element helium in which we have advanced from a solution of the first question to the last question in the short period of 55 years. It is to be borne in mind, however, that in the administration of mineral rights, the question "Will it pay?:' is of primary importance. What forms a mineral estate ? A former practice in western Canada in selling lands was to sell the hair with the hide. All transactions sold the lands in fee simple, which included all mines, minerals and rights and privileges whatsoever, excluding only the royal metals, gold and silver, which by imputation, though not by specific reference, in deeds. of title are reserved to the Crown. At that time the country was in the first ?stages of settlement and the value of our mineral resources was hardly appreciated and little understood.

Jan 1, 1923

By S Romanchuk, V N. Macvkiw, D. J. I. Evans

The paper describes the processes developed and piloted by Sherritt Gordon Mines Limited for recovering copper, in the form of specification copper powders, from Lynn Lake sulphidic copper concentrates and Fort Saskatchewan Refinery by-product copper sulphides. The process includes ammonia pressure leaching and hydrogen reduction from solution. Nickel and cobalt present in the con-centrates dissolve in the leach solution and a method was developed for separating these metals from the cop-per. Methods are described for con-trolling the physical properties of the copper powder produced in the reduction vessel. The chemistry of the process is briefly discussed and the effects of some of the more important process variables are described. SHERRITT Gordon Mines Limited have developed and proven on a pilot plant scale, a process (I) for the production of copper powder

Jan 1, 1961

By R. H. Fett

T HE APPROACH to maintenance must always be ?completely positive: there must be no question of putting off difficult problems until it is more convenient to tackle them. By this it is meant that a piece of machinery or equipment which, by experience, is known to be due for a check should not, merely because it appears to be operating satisfactorily, be left until it reaches a critical .condition and breaks down. The mentality of the Maintenance Manager must be completely orderly and methodical and he should, in fact, possess a ledger-book mind, having a debit and credit outlook. The debit side would be that applying to time out of service, cost in wages, material, personnel involved, etc., and the credit side that relating to continuous operational time of the locomotive and therefore to the ultimate benefit of the mine and the personnel who work there. The Maintenance Manager is not concerned with design problems, and although he and the personnel under his jurisdiction are not engaged in productive work, he and his staff do, nevertheless, add greatly to or detract from the overall efficiency of the organization. Provided the machinery placed in his care is good to start with, he must take the best steps he possibly can to keep it running. However, he may, on occasion, be forced to improvise and this is where the ingenuity of a clever man rises to the occasion.

Jan 1, 1956

By Jean-Louis Robert

Field work inaugurated in 1962 in the townships of Lemieux and Lesseps, in the Gaspe Peninsula of Quebec, has permitted the author to delineate the lithologic units of the area, to elucidate a few stratigraphic problems and to outline several zones of alteration. Certain features of these zones and the numerous mineralized showings in the area merit the attention of prospectors and exploration companies.

Jan 1, 1966

By S. N. Dixon

"Maximizing the value of each tonne of processed ore is the goal for all operations. Cyanidation processing of gold-copper ores has been challenging since its first use in 1889. The current practice treats a bleed or the total flow of mill solution to recover copper as copper sulfide (by sulfidization, acidification, recycling, and thickening), or to recover the cyanide (by acidification-volatilization neutralization). The process presented uses the adsorption of copper cyanide by carbon and the selective elution of copper from carbon to concentrate copper into a smaller stream. Copper contained in the smaller stream is precipitated as copper cyanide.RÉSUMÉ Toutes les exploitations ont pour objectif commun d’optimiser la valeur de chaque tonne de minerai traité. Depuis sa première utilisation en 1889, la méthode de traitement par cyanuration des minerais aurifère et cuprifère s’est révélée complexe. La pratique actuelle traite la saignée ou le débit total d’une solution de traitement du concentrateur pour récupérer le cuivre sous la forme de sulfure de cuivre (par sulfuration, acidification, recyclage et épaississement), ou pour récupérer le cyanure (par acidification, volatilisation et neutralisation). Le procédé présenté dans cet article utilise l’adsorption sur charbon actif de la solution de cyanure de cuivre et l’élution sélective du cuivre depuis le charbon pour concentrer le cuivre en un plus petit jet. Le cuivre contenu dans ce plus petit jet est précipité sous forme de cyanure de cuivre.INTRODUCTIONProcessing gold-copper ores by cyanidation has been a cost-control challenge since the cyanidation process was first used in 1889. Copper cyanide is stable only in the cuprous state, not the cupric. This factor results in the oxidation of a mole of cyanide per mole of nonchalcocite copper extracted. Each mole of copper extracted forms a cyanide complex with a minimum of 3 mol of cyanide. This cyanide-to-copper mole ratio is required to dissolve gold. The oxidation of cyanide and copper complexation with cyanide results in high cyanide consumption for copper-gold ores, which is a significant operating cost.One challenge in processing gold-copper ore is the cost of cyanide related to the extraction of copper. Processing 10,000 t/d of ore containing 1,000 mg/kg copper and 10% copper extraction yields 1,000 kg/d of copper. Currently, processes to remove copper from cyanide leach solution treat either the total flow of the barren or a bleed of the barren. The two processes used for copper-gold ores are sulfidization, acidification, recycling, and thickening (SART), which produces a copper sulfide product for sale; and acidification- volatilization-neutralization (AVR), which recovers the cyanide from a gas and produces a low–cyanide content solution. This low–cyanide content solution can be recycled to the process or might require additional treatment before being disposed from the operation."

Jan 1, 2017

By D. L. Johnston

"Function and ApplicationsWater-only cyclones, (WOC) are a dynamic mineral separator which cause minerals to separate in a water medium by virtue of difference in specific gravity. Figure 1 shows diagramatic plan and sectional views of a water-only cyclone.A slurry of mineral matter and water is fed through the inlet opening under gravitational or pump pressure. The combined effect of centrifugal action and conical shape is to concentrate the heaviest fraction of mineral on the periphery and bottom of the cyclone. This layer of higher specific gravity particles increases in thickness and density between the cyclone inlet and apex. The action in the bed of higher gravity particles formed in the flattened portion of the cone surrounding the tip of the vortex finder deter;nines the specific gravity of separation or cut-point. Mineral particles of lower specific gravity flow with the bulk of the water, out the vortex finder. Mineral particles of higher specific gravity flow with little water out the apex. A more technically e:mct description of the functioning of the water-only cyclone can be found in previous publications noted in the references.The water-only cyclone was invented and refined by J. Vis man, formerly of the Canadian Mines Branch staff, between 1958 and 1965. The first industrial application noted in the literature was when it was introduced as a cleaner for fine coal in 1962. Since 1970 the water-only cyclone has become a common separation apparatus in many Canadian and foreign coal processing plants. The only other mineral industry application known to the author is in separation of gold bearing heavy minerals from sand<'>. The potential does exist for other applications and this area deserves to be investigated more thoroughly than it has been."

Jan 1, 1989

By J. M. R. Carvalho, M. T. A. Reis, M. R. C. Ismael, M. J. N. Correia, S. M. C. Santos, J. M. Carvajal

A sulphide zinc concentrate (Zn-40%) has been leached in sulphuric and chloride media to optimize the conditions for the recovery of zinc and copper. Previous results showed that extractions of 95% zinc and 20% copper can be achieved in just one stage, after two hours of leaching at 80°C with a solution 0.5M in Fe2(SO4)3 and H2SO4 and a solid/liquid ratio of 5%. This work presents the results obtained in the leaching experiments carried out in sulphuric and chloride media using two and three crosscurrent stages and a countercurrent process simulation for a solid/liquid ratio of 10%.

Jan 1, 2008

By J. R. Foster

Investigations into the effect of a variety of acid digestions on common rock-forming minerals demonstrated a considerable variation in the proportion of the total metal extracted. A similar situation applies to the analysis of a number of common rock types. In addition, grain-size variation has an effect on the amount extracted by certain digestions. This work indicates that considerable care needs to be given to selecting an appropriate acid digestion capable of determining metal held in particular components of a sample. By using partial extraction techniques, the identification of certain patterns of metal distribution, undetectable by normal methods involving total metal analysis, may be achieved.

Jan 1, 1973

By John C. Luck Jr.

"DEVELOPMENT of oil emulsion mud dates back to the early days of rotary drilling when oil was added to the drilling mud solely for the purpose of freeing stuck drill pipe. After the drill pipe was freed, and drilling resumed, this oil was considered a contaminant. Efforts were made to remove the oil but some of it remained and was emulsified with the drilling mud, thus forming a mechanical emulsion.During the late 1930's, operators found that adding crude oil to drilling muds seemed to alleviate 'sticky-hole' problems and so oil was allowed to remain in the mud. This practice was adopted when it was found that faster drilling rates and longer bit life were obtained. These observations led to the development of emulsion drilling muds. During the past five years their application has become more widespread because of the lower fluid losses obtained, greater lubrication qualities, faster penetration rates, and generally better hole conditions.An emulsion may be defined as a two-phase system consisting of a mixture of either finely divided oil droplets in water or of finely divided water droplets in oil. The surrounding liquid is known as the continuous phase. The emulsifiers reduce the interfacial tension, making the droplets tend to repel each other so that they remain dispersed and stabilized. These emulsions are classified as oil-in-water or as water-in-oil, depending upon whether water or oil, respectively, is the continuous phase. Briefly, close inspection shows that they consist essentially of globules of• the one liquid suspended in a continuous mass of the other liquid. Oil emulsion muds are usually of the oil-in-water type. Two basic types of emulsifiers •commonly used in Canadian muds are soaps and lignites."

Jan 1, 1954

By David J. T. Carson

"The metalliferous deposits of Vancouver Island have generally been assigned to the Mesozoic ""Coast Range Orogeny."" However, a metallogenic study by the writer has revealed that several important classes are early or middle Tertiary. Included are porphyry coppers, and gold-quartz, arsenic and copper-arsenic veins.The porphyry coppers and many gold-quartz veins are within and adjacent to Oligocene-Eocene quartz diorite intrusive complexes. Arsenic and copper-arsenic veins have a close spatial relationship to sills and laccoliths of Oligocene dacite porphyry which intrude the late Cretaceous Nanaimo Group.Other deposits of demonstrable Tertiary age include a molybdenum stockwork related to a relatively potassic Eocene plug and a few small copper-skarn occurrences. Some copper stockworks and a mercury deposit are probably also Tertiary.The copper deposits of previously recognized Tertiary age are those of the Sooke area that occur in Eocene basalts and Oligocene gabbros."

Jan 1, 1969

By I. Silin, M. Stapelmann, H. Wotruba, K. M. Hahn, C. Gerold, J. Katzmarzyk

New deposits are often characterized as low-grade and complex ore bodies. To date, processing of fine grained ore deposits implies complex processing routes with high energy consumption. For that reason, the investigation of dry grinding, e.g. with vertical roller mills (VRM), is an approach to save energy reserves. It is already proven that dry grinding can influence subsequent processing steps. In terms of flotation, the surface characteristics of the minerals are crucial for a successful flotation process, e.g. the sufficient adhesion of mineral particles and air bubbles. Wet grinding results in different surface properties of the product entering the conditioning stage than dry grinding, which has direct influences on the subsequent flotation process. To investigate the consequences for flotation, processing of a copper sulfide ore containing chalcopyrite and bornite was investigated, including grinding and rougher flotation. The effects of wet tumbling mill and dry VRM grinding on the degree of liberation of valuable minerals are characterized using mineral liberation analysis by scanning electron microscopy. The obtained flotation results, as well as the recorded flotation parameters such as dissolved oxygen, oxidation reduction potential and conductivity are presented and discussed. INTRODUCTION Copper production is mainly connected to porphyry copper deposits as main source for copper sulfides such as chalcopyrite and bornite. State-of-the-art processing of these deposits is already established worldwide for decades, combining crushing, fine grinding and subsequent flotation with rougher, cleaner and scavenger stages (del Villar, Desbiens, & Maldonado, Bouchard, 2010). While the demand for copper is increasing, copper grades of the deposits are decreasing and the remaining ore bodies have more complex mineralogy and finer particle size distribution. This implies processing routes with high water and – due to the liberation of fine grained valuable minerals – high energy consumption by fine grinding. One of the main energy consumers in processing plants is the grinding section, which accounts for more than 50% of the energy consumption in processing plants and even 4% of the worldwide energy consumption (Jeswiet, & Szekeres, 2016). Therefore, dry fine grinding alternatives are applied to enhance the overall energy consumption of mineral processing plants: high pressure grinding rolls (HPGR) and vertical roller mills (VRM).

Jan 1, 2019

By R. Lodha, C. Oprea, G. Oprea, H. Zargar, T. Troczynski

"The basic refractories used in non-ferrous industry contain chrome ore for improving the thermal shock resistance, thus reducing the penetration of molten metal and fayalite-type slags into the lining. The current study aims to replace chrome ore with Me4+ ions along with Fe3+ ions in order to form MgO-Al2O3- FeOx-Me4+O2 based complex spinel systems that could perform similar to the complex chromia-bearing spinel in the magnesia-chrome refractories. This system allows for lower temperatures of synthesis and sintering. In our study, compositions with 60% MgO were fired below 1500°C and resulted in complete formation of complex spinel, and open porosity less than 5%. The in-situ formation of the complex spinel from the fine mix of oxides in the MgO-Al2O3-FeOx-Me4+O2 system offers a suitable alternative of binding system to produce basic refractories at lower temperatures and of similar physical and mechanical properties with magnesia-chrome bricks fired above 1750ºC. INTRODUCTIONThe synthesis of magnesium aluminate spinel (MgAl2O4) (Maschio, Fabbri, & Fiori, 1988) or magnesium chromate spinel (MgCr2O4) from their respective oxides is diffusion controlled resulting in a sluggish reaction even at high temperatures. For instance, the diffusion of Mg2+ and Al3+ ions in the intermediate spinel layer during reaction is slower than the diffusion of Mg2+ in corundum and Al3+ in periclase. The interfacial layer of spinel formed during the reaction increases the diffusion path for the spinel forming cations. This accompanied by ~8% volume expansion retards further reaction resulting in incomplete spinel forming reaction during sintering and hence densification during the reaction cannot be achieved. In order to assess sintering studies with fine particulate oxides that would result in a lower diffusion path, a mechanical mixture of the hydroxides of aluminium and magnesium calcined at 1400ºC to 1600ºC for 1 hour does not result in complete spinel formation (Sarkar, Das, & Banerjee, 2003), which indicates that reaction sintering of stoichiometric magnesium aluminate spinel is retarded by initial reaction forming the interfacial spinel layer. The basic bricks used as linings in non-ferrous pyro-metallurgical convertors are manufactured using magnesia and chrome ore, the sintering of which produce spinel solid solution. This solid solution is a mix of both normal and inverse spinel structures that sinters at temperatures in excess of 1800ºC in air."

Jan 1, 2012

By Sergio Romo, Gerardo Fuentes, Adriana Garcés

Refractory ores with gold entrapped in a sulfide matrix, must be processed in a first stage with chemical or physical treatment in order to liberate the gold for a subsequent step with cyanide. The goal of this research was to compare the refractory behavior of a gold concentrate treated using two pretreatment methods: pressure oxidation and fine grinding. Gold concentrate from Viacha Mining in Bolivia, assaying 50.11 gpt, with a P80 of 131 ?m was used. The concentrate contains arsenopyrite and pyrite as main sulphides in the matrix. A preliminary test with cyanide resulted only 13.5% of gold extraction with 4 hours of stirred leaching. Using an autoclave oxidation with sulphuric acid and 12 bar oxygen pressure at 220°C pretreatment, the cyanide gold extraction increased to 69.0% in 4 hours. When material was ground in a pulverizer, producing a P80 of 20 ?m and the product directly cyanided, stirred leaching gave a gold extraction of 65% in 4 hours. For both techniques, the effect of temperature, sulfur produced in autoclave oxidation, optimization of the cyanide and the nature of residues were also studied.

Jan 1, 2014