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By Jeanne B. Percival, Paul Ramaekers, Charles W. Jefferson, Pat A. Hunt, Eric G. Potter, Katherine E. Venance, William Davis, Sean A. Bosman

"A 10-cm thick clay-rich layer near the top of the Manitou Falls Formation of the Athabasca Group is unusual in its breccia texture, alteration, and detrital mineral composition relative to the adjacent overlying and underlying sedimentary beds. This layer is composed of angular quartz grains set in an illite >> kaolinite + dickite matrix. Deformed clay-rich fragments within the layer have very similar mineral assemblages. The presence of euhedral accessory minerals including Ti-oxides and aluminophosphatesulphate minerals points to a diagenetic/hydrothermal origin. The presence of individual grains of Kfeldspar and amphibole is unusual relative to the typical Athabasca quartz arenite; originally, these minerals were probably included in detrital quartz and subsequently liberated during fracturing. The textures and alteration characteristics suggest that this layer is a hydraulically-fractured unit, which has experienced hydrothermal fluid alteration - a possible pathway distally related to uranium mineralization Une couche argileuse de 10 cm d’epaisseur pres du sommet de la Formation de Manitou Falls du Groupe d'Athabasca est remarquable par sa texture brechique, son alteration et la composition de ses mineraux detritiques qui different de ceux des couches sedimentaires sus- et sous-jacente. Cette couche est composee de grains de quartz angulaires dans une matrice composee d’illite >> kaolinite + dickite. Des fragments deformes riches en argile dans cette couche presentent des assemblages mineraux tres similaires. La presence de mineraux accessoires idiomorphes dont des oxydes de titane et des aluminophosphates-sulphates suggere que ces derniers ont une origine diagenetique / hydrothermale. La presence de grains de feldspath-K et d'amphibole est inhabituelle comparativement aux arenites quartziques typiques de l’Athabasca; initialement, ces mineraux constituaient probablement des inclusions dans le quartz detritique qui ont ete subsequemment liberees pendant la fracturation. Les textures et les caracteristiques de l'alteration suggerent que cette unite a subi une fracturation hydraulique et a ete alteree par un fluide hydrothermal - possiblement en lien avec les effets distaux de mise en place de la mineralisation en l'uranium."

Jan 1, 2013

"The pressure leaching of alkali-pretreated limonitic laterite ore in nitric acid was studied. The optimal leaching conditions are as follows: leaching temperature of 458 K, initial nitric acid of 2.44 mol/L, leaching time of 60 min, liquid to solid ratio of 2:1 mL/g, agitation speed of 500 RPM. Under the above conditions, the extraction of nickel and cobalt can be achieved as approximate 95% and 80% respectively while that of iron is as lower as 1%. The leaching residue containing 70% of iron in the form of hematite and trace amount of chromium is suitable as the raw material for iron-making. The nitric acid in the leaching solution can be regenerated and further recycled to leach. INTRODUCTIONIt has been estimated that 60%-70% of the world land-based nickel resources presented in nickel laterites containing 130 million tons of nickel although these only accounted for about 42% of the world nickel production (Sudol, 2005; Luo et al., 2010). The nickel resource of laterite has not yet been fully utilized. Due to the increasing global demand of nickel and the declining global reserves of nickel sulphides, there is an increasing focus on the processing of the huge reserves of laterite ores today. Nickel laterite ores can be simply divided into two types, namely, silicate-rich and limonite. The former can be treated effectively by pyrometallurgical process in which the ferronickel product or nickel/iron sulphide matte is produced (Monhemius, 1987). The limonitic laterite is rich in iron in the form of goethite which is the main nickel-bearing mineral and usually contains cobalt associated with a manganese phase (Chang et al., 2010; Georgiou and Papangelakis, 2004). The limonitic laterite is usually processed by hydrometallurgical methods, such as atmosphere acid leaching (AL) (Xu et al., 2005; McDonald and Whittington, 2008), high pressure acid leaching (HPAL) (Chou et al., 1977; Georgiou and Papangelakis, 1998; Rubisov et al., 2000; Whittington and Muir, 2000) and reductive roasting-ammonia leaching (Caron Process) (Whittington and Muir, 2000; Valix and Cheung, 2002). The AL process can proceed at lower temperature, thus the operation costs may be very low. But two biggest problems associate with the AL process, namely, the slow rates of nickel extraction and potentially the significant amount of impurities such as iron and aluminum in the leaching solutions, which hampers the wide application of the AL process. The Caron Process uses the pyrometallurgical and hydrometallurgical methods together to obtain the metallic values, but the overall metal recovery is relatively low, especially for cobalt. In recent years, the environment-friendly process of HPAL has become increasingly important because it is most suitable for low-grade ores and leads to high extraction of the valuables. However, the HPAL process needs a much higher temperature and pressure (503-533 K, 4-5 MPa) to maintain a relatively fast leaching rates, which results in higher operation costs. Moreover, another serious problem of scale formation in autoclaves occurs in the HPAL process, for example, in Moa Bay, up to 20 cm scale may build up resulting in 5 days descale downtime per month. In addition, the iron residues cannot be utilized for ironmaking due to the presence of high content chromium (Ema and Harada, 1987; Owada and Harada, 1987; Takagi and Furui, 1987)."

Jan 1, 2012

By Bahram Samani

The Bafq - Saghand ore belt (metallogenic zone) is the main region, where the major discovered Uranium resources are located. This belt is a unique Upper Precambrian terrane experienced Katanga ? Pan African tectono ? thermal events. The oldest sialic crust was formed during the middle Proterozoic and followed by K-granite intrusions of Lufilian Cycle (850-800 M.Y.).This event caused Tectono ? Magmatic ? Activization (T.M.A) characterized by intracontinental rifting and associated ore formations. This zone was considered as an iron ore belt in 1960s ? 1970s, and U ? Th ? REE belt in 1980s ? 1990s, but by new discovered of U ? Mo (Co, Au, As, Cu) mineralization is assigned as a U - Polymetal zone, hosting the full sequences of iron oxide (Cu, Au, U) ore forming groups. On the basis of detailed investigations this zone is characterized by the following peculiarities: This zone is the vestigial vessel of Gondwana basement, where the oldest granite and the first platform clastic cover is exposed. This zone is marginal part of Precambrian continental crust, consolidated in 1.3-1.0 B.a. The sub mature continental crust experienced Lufilian Orogenic and Katanga ? Pan African Tectono ? Thermal event by intercontinental rifting, and ore mineralizations. The ore forming stages were sequential processes, started by enriched mantle derived metallogeny, and ended by interaction of silanes/ HACONS (derived from outer core) with crust. The magnetite- apatite (REE, Ti) metallogeny developed from alkaline- ultrabasic magmatic differentiation, capable to from Au- Ni- Sulfide intrusive massifs during 850- 800 Ma. Degassing of silanes/HACONS from deeper level, not only caused mantle enrichment, and plume upwelling as a frontal load, but also played the main role to develop regional Si (-Na-K-Mg-Ca-Co3) metasomatism, and formation of U- Th- Ti- REE- (apatite, magnetite) deposits. The latest (583-510 Ma old) felsic magmatism was major IGU from U-Mo (-Co-As-Au-?Cu?) hydrothermal vein- type deposits. The albitite- type U- Ti- REE (Th) mineralization could be formed by interaction of ascending, and descending solutions along the deep- rooted structural conduits.

May 1, 2007

By N. Campbell, W. T. Orvine

The metalliferous deposits of British Columbia are largely confined to that portion of the Cordilleran province lying west of the Rocky Mountain trench. Massive sulphides in the coastal area carry important copper •values together with lead and zinc and are composed mainly of pyrite which replaces schists or shear zones. The massive sulphide ore of the interior, on the other hand, contains lead and zinc with little copper. Pyrrhotite rather than pyrite is... the dominant metallic and deposition took place through selective replacement of sedimentary beds.

Jan 1, 1960

By R. L. Bailey

"The Acheson D-3 Pool was discovered in August 1950, and contains 88 producing oil wells on 40 acre spacing. Initial oil-in-place was 118 million stock tank barrels and initial well potentials averaged 2,000 barrels per day.In early 1956 studies of hydraulic interference between the Acheson and Leduc D-3 Pools were conducted on the Carter Petroleum Reservoir Analyzer. These studies indicated that the natural water drive to Acheson would be incapable of replacing reasonable withdrawal rates over the life of the pool. To avoid shrinkage losses a scheme of pressure maintenance by water• injection was therefore instituted in March 1957.This pressure maintenance scheme is notable because pressure is being effectively maintained by high volume injection through one well located on the flank of the pool. Close control on reservoir behaviour is maintained by regular bottom-hole pres-sure surveys and observation of water cuts on producing wells. No evidence of pressure gradients or channelling of the injected water has been observed to date, and the water-oil contact has remained level over the whole field. It is possible to control the average reservoir pressure within very close limits by varying the rate of fresh water injection.Ultimate recovery estimated from the rise of the oil-water contact and calculated water influx to December 31, 1958, is 335 barrels per acre foot, or a total of 91.4 million barrels from the pool. This compares to 217 barrels Per acre foot or a total of 59.4 million barrels indicated from laboratory test data."

Jan 1, 1961

By George P. Demopoulos

For more than 20 years the author had the privilege of working closely on a number of R&D projects with Lucy Rosato and her team at CEZinc. Several of these projects were driven from the sustainability agenda that Lucy Rosato championed as an innovation leader that supported research collaborations. Highlights from this highly rewarding collaboration are to be presented in this paper. In particular we will deal with the following works-topics: (a) iron control via solvent extraction as alternative to jarosite precipitation; (b) production of high-density gypsum by controlled neutralization of simulated zinc plant process/waste waters; (c) selenium removal from weak acid solutions; (d) electrolyte purification by cementation; and (e) manganese control by oxidative precipitation with SO2/O2.

Jan 1, 2015

En quoi consistent les études de suivi des effets sur l?environnement (ESEE)? Les ESEE constituent une méthode de suivi scientifique que l?on peut employer pour déterminer la santé des écosystèmes aquatiques (qui peuvent être touchés par l?activité humaine) et l?efficacité des mesures de protection de l?environnement. Les ESEE sont des évaluations scientifiques itératives du poisson, de l?habitat du poisson et des ressources halieutiques. Le programme comporte des phases séquentielles de deux à six ans de suivi, d?interprétation et de compte rendu au cours desquelles la fréquence et le type de suivi dépendent des résultats des études précédentes. Le programme des ESEE pour les mines de métaux est fondé sur un accord conclu à l?unanimité entre les intervenants. Les exigences du programme et les guides techniques connexes ont été élaborés à la suite d?une consultation multilatérale à laquelle ont participé les représentants du secteur privé, du gouvernement et des collectivités. Toutes les mines assujetties au Règlement sur les effluents des mines de métaux (REMM), aux termes de la Loi sur les pê ches, doivent procéder à une ESEE dans le cadre de l?autorisation qu?ils ont reç ue de rejeter des effluents. Le REMM a été enregistré le 6 juin 2002 et publié dans la Partie II de la Gazette du Canada le 19 juin 2002 (SOR/DORS/2002-222).

Nov 1, 2002

By K. A. Clark

A meeting between representatives of the Scientific and Industrial Research Council of Alberta and the Deputy Minister of Mines for Canada was held at Edmonton in May, 1929, for the purpose of formulating a co-operative plan for carrying forward studies in aid of the development of commercial methods for utilizing the bituminous sands of Alberta. It was agreed that to the Alberta Research Council should be allocated the general problem of investigation of the processes for the separating of bitumen from the sands, including studies of methods of emulsifying, dehydrating and otherwise preparing separated bitumen for industrial applications. It was further agreed that during the present year the work of the Alberta Research Council should be to continue its laboratory investigations of points of design of its separation plant; to further perfect its separation procedure; to recondition its existing separation plant at Dunvegan Yards, Edmonton, in the light of laboratory studies and to operate it for the purpose of demonstrating its efficiency; to carry on tests in emulsifying and dehydrating or otherwise preparing separated bitumen for industrial application; and on the basis of the experience gained in the operation of the preliminary plant at Dunvegan Yards to prepare and design and, as far as possible, to proceed with the erection of, a semi-commercial separation plant at a site to be chosen, probably at the bituminous sand deposits near McMurray, Alberta. This paper presents, in the main, a progress report of the carrying out of this programme.

Jan 1, 1929

By L. Heber Cole

Introductory During the past few years, salt (sodium chloride) strata have been encountered in western Canada in a number of wells, while prospecting for oil and gas. The ever increasing number of such wells points to the presence of a vast salt basin, the boundaries of which are at present unknown. This basin extends in a northwesterly direction from a point near the United States boundary south of Regina, crosses the Saskatchewan- Alberta boundary northwest of Unity, Sask., and continues with more northerly trend to Waterways and beyond. The beds, as encountered, appear to have a general dip to the southwest of between 10 to 20 feet to the mile and a pitch along the strike to the southeast. Thus one finds the salt strata at Waterways, Alta., at 600 feet below the surface (121 feet above sea level) whereas at Radville, Sask. south of Regina, the top of the salt is at a depth of 6,643 feet below the surface (4,430 feet below sea level). Whether this is a continuous salt basin or a series of separate basins is not yet known. We do know however, that in some of the well~ more than one salt horizon occurs while in others which normally should have encountered corresponding beds, the salt strata are absent. This latter condition, however, may occur only in the southern part of Saskatchewan, where a barren area seems to come in from the southwest. In the northwestern part of the basin, on the other hand, the occurrence of the salt strata seems to be more regular and continuous, and depths at which salt should be encountered in a drill hole in this part of the basin may be predicted with a fair degree of accuracy.

Jan 1, 1948

By A. Mcdonald, F. W. Breaks, T. F. Morris, S. A. Averill, D. C. Crabtree

Abstract-Gahnite, a zinc-bearing spinel, is a resistate mineral that may be used as an indicator mineral of polymetallic deposits in high-grade metamorphic terrain. The Ontario Geological Survey recently completed surficial mapping and sampling programs in the Separation Lake area of northwestern Ontario and Kinniwabi Lake area of northeastern Ontario in which gahnite was recovered from samples of surficial sediments. Ternary plots of the composition (ZnO, MgO, FeO[t]) of gahnite recovered from these surficial studies reveal three distinct groups: Group 1 is characterized by low (< 1 wt%) MgO values; Group 2 by higher (>1 wt%) MgO values; and Group 3 by higher FeO(t) values than Groups 1 and 2. The composition of in situ gahnite recovered from volcanogenic massive sulfide mineralization, Zn-rich Sedex-type mineralization and peraluminous rare-element mineralized granite and pegmatite also was determined. The composition of the gahnite obtained from surficial samples was compared with that of in situ material. Gahnite from the peraluminous rareelement granite and pegmatite overlapped very well with surficial gahnite of Group 1. Gahnite from volcanogenic massive sulfide mineralization and Sedex-type mineralization overlapped well with surficial gahnite of Group 2. These results suggest that determination of gahnite composition in indicator mineral surveys may be useful in exploration programs when assessing the mineral potential of a region.

Jan 1, 1997

By A. Mcdonald, F. W. Breaks, T. F. Morris, S. A. Averill, D. C. Crabtree

Gahnite, a zinc-bearing spinel, is a resistate mineral that may be used as an indicator mineral of polymetallic deposits in high-grade metamorphic terrain. The Ontario Geological Survey recently completed sur?cial mapping and sampling programs in the Separation Lake area of north-western Ontario and Kinniwabi Lake area of northeastern Ontario in which gahnite was recovered from samples of sur?cial sediments. Ternary plots of the composition (ZnO, MgO, FeO[t]) of gahnite recovered from these sur?cial studies reveal three distinct groups: Group 1 is characterized by low (< 1 wt%) MgO values; Group 2 by higher (>1 wt%) MgO values; and Group 3 by higher FeO(t)values than Groups 1 and 2. The composition of in situ gahnite recovered from volcanogenic massive sul?de mineralization, Zn-rich Sedex-type mineralization and peraluminous rare-element mineralized granite and pegmatite also was determined. The composition of the gahnite obtained from sur?cial samples was compared with that of in situ material. Gahnite from the peraluminous rare-element granite and pegmatite overlapped very well with sur?cial gahnite of Group 1. Gahnite from volcanogenic massive sul?de mineralization and Sedex-type mineralization overlapped well with sur?cial gahnite of Group 2. These results suggest that determination of gahnite composition in indi-cator mineral surveys may be useful in exploration programs when assessing the mineral potential of a region.

Jan 1, 1997

By L. Jiang

This report investigated the dynamic recrystallization (DRX) phenomenon in magnesium alloy AZ31 billets to understand the deformation mechanisms and microstructure evolution during extrusion and other metal forming processes, Compression tests of coarse-grained as-cast magnesium alloy billets containing lamellar Mg17Al12 eutectic phase and (Al, Mn) particles suggest that temperatures higher than 300°C, strains greater than 0,25 and strain rates above 0,l/s lead to the formation of fine DRX grains in the deformed samples. Microstructural observations also indicate particle-stimulated DRX nucleation (PSN) during hot deformation of the AZ31 alloy, facilitated by the presence of Mg17Al12 and (Al, Mn) particles, While the Mg17Al12 is dissolved into the matrix at about 350°C, (Al, Mn) particles may remain effective for PSN at temperatures up to at least 400°C, This study suggests that alloy design with a proper distribution of second-phase particles can provide the desired microstructure for improved properties and formability in wrought magnesium alloys.

Jan 1, 2004

By K. G. Chipman

THE discussion on Dr. Chipman&apos;s paper, Mapping by the Topographical Survey, centred mainly on the urgent need for aerial photographic reconnaissance of unmapped portions of the country as an initial phase in the provision of suitable topographical maps for use as a guide in geological mapping, prospecting, exploration, and development work in the areas concerned. This, ir was pointed out, would necessitate an expansion of the topographical work of the Bureau of Topography to keep pace with the photographid work and to meet the demand for maps for use by geologists of the Bureau of Geology and others. A resolution requesting Institute Council to make representations to the proper authorities, urging that aerial photography and topographic map-ping be greatly expanded to meet the pressing needs of the situation, was moved by DR. W. F. JAMES and seconded by MR. L. G. SMITH, and carried unanimously. The full text of the resolution appeared on page 221 of the May BULLETIN. Others who spoke in support of the resolution were MESSRS. E. S. MOORE, L. B. ROCHESTER, F. D. SHEPHERD, and W. J. WRIGHT. Dr. Hansen then presented his paper, Mapping by the Geological Survey, discussion on which is summarized below. MR. FRANK EBBUTT(l) spoke of the very valuable service the Geological Survey bas rendered the mineral industry, and indeed the whole nation, in its century of existence, despite the very inadequate financial support it has received. Now, more than ever before, a strong and expanded Geological Survey is essential if the Industry is to continue to prosper. Our known ore reserves are being depleted very rapidly, and we are finding no new orebodies to take their place. As an aid in prospecting and exploration, and also in the development of orebodies when they have been found, we must have geological maps of the vast sections of the country which at present are unmapped or inadequately mapped. The Institute should make every endeavour to have the Geological Survey strengthened so that such maps may be made available as soon as possible.

Jan 1, 1944

By K. D. Watson

"THE Mindamar zinc-lead-copper mine, owned by Mindamar Metals Corporation Limited, is at Stirling in Richmond County, near the south-eastern shore of Cape Breton Island, Nova Scotia (Figure I). It is connected by several roads with the Canadian National railway at Sydney and St. Peters.The deposit is said to have been discovered around 1895 as an outcrop in the bed of Copper brook, but the details are obscure. Not until 1925, when it was optioned by American Cyanamid Company, was it developed underground. Between 1927 and 1938, the 1-nine was operated intermittently by The British Metal Corporation (Canada) Limited, and yielded approximately 200,000 tons of ore averaging about IO per cent zinc, 2 per cent lead, I per cent copper, and small quantities of silver and gold. In December 1950, Dome Exploration (Canada) Limited made an agreement with Mindamar Metaî Corporation Limited, which was exploring the old mine, to assume management and prepare the property for production. Production started in April 1952 with a new mill and a new four-compartment shaft, and between that time and the end of 1954 it has totalled 545,347 tons of ore averaging 5·89 per cent zinc, 1·35 per cent lead, 0·66 per cent copper, 0·032 oz. gold, and 2 151 oz. silver.The Mindamar orebodies are irregular lenses and large veins lying within a wide, almost vertical shear zone of remarkable persistency. The shear zone consists mainly of well-foliated sericite schist derived from siliceous siltstone, and it contains a vast amount of dolomite and magne-site of hydrothermal origin. Most of the ore is extremely fine-grained and some of the high-grade material has a conspicuous thinly layered structure. The metallic minerals, in order of decreasing abundance, are pyrite, sphalerite, chalcopyrite, galena, and tennantite; the gangue minerals, in the same order, are dolomite and magnesite, quartz, sericite, talc, chlorite, barite, albite, and alunite.The geological setting of the deposit is shown in Figure 2. Except along streams and lake shores, almost all of the bedrock is concealed by glacial drift. The group of rocks in which the deposit occurs consists principally of greywacke, siltstone, tuff, brecoia, and Javas, and has been correlated lithologically with the Bourinot group of Middle Cambrian age. A short distance west of the mine, these rocks are in contact along the Stirling fault with conglomerate, arkosic sandstone, and quartzite belonging to the Middle River group of Silurian or Devonian (?) age, which elsewhere in the area overlies the Bourinot group unconformably. The large bodies of granitic rocks in the region, and the large lenticular masses of diorite and quartz diorite associated with them, have been assigned by Weeks (5, pp. 68-69) to the Devonian."

Jan 1, 1949

By F. Siciliano, D. Bai, S. Yue, A. M. Elwazri

The influence of niobium addition and very low temperature (`cool&apos;) deformation on the microstructure and properties of low carbon microalloyed steels was investigated. In this work, the specimens were heated at 1200°C and held at this temperature for 20 minutes. Some specimens were aged at 400°C for times ranging from 10 minutes to 10 hours followed by air-cooling. Others were subjected to deformation at 400°C (`cool deformation&apos;) prior to aging. It was observed that the proportion of acicular ferrite was increased as the amount of Nb was increased. It was found that cool deformation increased both yield and tensile strengths significantly compared to that of the aged only specimens.

Jan 1, 2005

By D J. Murray

This paper outlines the principles of friction hoisting and the components involved, and gives a description of a specific mine hoist. Friction hoisting is compared with conventional drum hoisting, and the depth of shaft at which friction hoists become more economical than drum hoists, with respect to power consumption, is determined. Introduction T HE purpose of this paper is to outline the principles of friction hoisting, to describe the components and to show the advantages of multi-rope friction hoisting. Some calculations are made to show that the power requirements and the initial costs of friction hoists are less than those of conventional drum hoists, once a certain depth of shaft has been reached. The use of multi-rope friction hoists is gradually superseding the employment of the conventional drum hoist in many parts of the world. It results in heavier payloads from deeper levels, an increase in shaft safe-ty and a more compact installation for protection against adverse weather conditions. It was observed that where drums and friction sheaves exceeded 30 feet in diameter, a number of mechanical disadvantages were being experienced;

Jan 1, 1965

By A. van As, J. McGaughey, M. J. Mol, R. Tosen

Geotechnical monitoring is a key element of the successful management of a block cave mine. The interrelationships between production and various monitoring datasets are often not realized due to a lack of data integration and appropriate 3D visualization. Timely delivery of information to ensure best cave management practices is only possible with an integrated cave management system. At Rio Tinto, a state-of-the-art cave management system (CaveCAD) has been designed and developed in cooperation with Mira Geoscience to integrate and analyze vast datasets and report this as instructive information regarding the current \u201cstatus\u201d of the cave.

Jan 1, 2014

By B. W. Williams

The crack propagation behaviour of Zr-2.5Nb pressure tube material was studied through comparison of the measured behaviour with the predicted response from finite element analysis. Three-dimensional finite element simulations of compact tension specimens were performed using the crack tip opening angle as a fracture criterion to allow for crack propagation. To obtain reasonable agreement with the measured behaviour, it was important to capture both the anisotropic plastic deformation behaviour of the Zr-2.5Nb material through use of the Hill-48 yield criterion and damage due to void growth, nucleation, and coalescence through the use of a Gurson-based constitutive model in the simulations.

Jan 1, 2010

By C. Xiao, F. Mohamm, A. Borsoi

"Nitrogen compounds produced by cyanide destruction and/or blasting are often a cause of concern for environmental compliance and at times, for water re-use in metallurgical circuits. Natural attenuation in tailings ponds and wetlands is not always sufficient to ensure compliance and/or achievement of overall water management objectives. This paper provides a general overview of active treatment methods for nitrogen management followed by an investigation of selective adsorption combined with electro-oxidation as the potential treatment method for thiocyanate. Results from bench scale treatability study are presented. The concept of holistic assessment of nitrogen management at mine sites using Risk Adjusted Life Cycle Cost is introduced and discussed in the context of gold mining operations using sodium cyanide.INTRODUCTION Unlike metals, nitrogen compounds present in mine waters originate entirely from anthropogenic sources rather than mineral deposits. Table 1 summarizes the main sources of nitrogen compounds reporting to mine wastewater.The best management practice related to the use of ANFO involves minimizing contact between ANFO and water, control and monitoring of blasting to reduce the occurrence of misfires, and reducing the consumption of blasting reagents for a given ore body. The most common practice for the management of NaCN is the incorporation of cyanide destruction in the metallurgical flowsheet and the use of tailings impoundments and holding ponds for natural attenuation of cyanide destruction residues such as NH4-N and CNO. At most mine sites there is no active management of NO3-N and SCN in wastewater. While current practices have produced satisfactory results, new enhanced methods to manage nitrogen compounds at mines are needed due to: 1) Increased scrutiny over the adverse effects of nitrogen compounds released into the environment; 2) New effluent standards; and 3) The shift away from wet tailings towards dry stack systems resulting in diminished natural attenuation and dilution of nitrogen residues prior to effluent discharge or water re-use in mineral processing."

Jan 1, 2017

By M. Epiney, A. Ghahreman, R. Kim1and

"Pre-oxidation and cyanide leaching behavior of gold in the presence of sulfide minerals were reviewed, focused on the effects of oxygen injection in the gold leaching process. Generally, pre-oxidation and gold leaching kinetics from iron sulfide refractory minerals, such as pyrite, pyrrhotite, marcasite, pentlandite and arsenopyrite, can be enhanced with higher dissolved oxygen (DO) concentration. However, most of copper sulfide minerals dissolved well both in water and cyanide solutions, and copper from the minerals consumed DO and cyanide to oxidize and leach. Only in the presence of chalcopyrite, gold leaching was effectively occurred with increasing DO. However, chalcocite and covellite severely retarded gold leaching. Stibnite, an antimony mineral, formed a passive film on the gold surface under any DO conditions, and it slowed gold leaching. This impeding effect can be alleviated by leaching at low pH or adding lead salt. Using oxygen and lead together can make synergistic effect in oxidation of sulfide minerals and can enhance gold extraction. Depending on the mineralogical characteristics of the ore, the optimum DO and lead concentrations can be optimized. However, lead can cause environmental problems, and so its dosage should be minimized or eliminated by substituting it with oxygen injection.INTRODUCTIONGold ores containing sulfide minerals are becoming more significant as high grade gold oxide deposits are continuously becoming difficult to find. In light of this situation, to produce more gold, recovery methods from refractory gold ore containing various sulfide minerals should be investigated. Generally, sulfide minerals have impeding effects on gold leaching: formation of a passive film on the gold surface, high consumption of chemicalssuch as cyanide and oxygenduring leaching, reduction of gold cyanide by sulfide ions, etc. (Senanayake, 2008). Therefore, sulfides must be properly treated for better gold recovery. Pre-oxidation of sulfide minerals by injecting pure oxygen can decrease the impeding effects in gold leaching. Prior to cyanidation, sulfide minerals can be oxidized to metal hydroxide and sulfate form, which consume negligible cyanide in the following cyanidation circuit (Bodnaras et al., 1993). Moreover, gold cyanidation can be enhanced by increasing concentration of the dissolved oxygen (DO). In general, the optimum concentration ratio of [CN-]/[O2] is calculated as 6, but it goes higher in the real system (Marsden &House, 2006), which means that the reaction is typically controlled by DO concentration."

Jan 1, 2017