Search Documents

By Claude Hubert, Alex C. Brown, Pascal Marquis, D. M. Rigg

"Numerous studies of the Bousquet mining district, Abitibi, Quebec, mainly following the successive discoveries of new gold deposits over the past two decades, have led to a broad range of genetic hypotheses for their gold deposition. A compilation of petrographic, structural, and geochemical data indicates that the gold deposits are composed chiefly of pyritic schists derived from felsic and mafic volcanic and volcaniclastic protoliths, and of auriferous massive pyrite hosted by pyritic schists of felsic affinity. The deposits are typically located within zones of local pyrite enrichment and advanced-argillic alteration which are in turn enclosed within much larger zones of disseminated pyrite included in regional-scale, commonly anastomosing, zones of sericitic alteration.Overprinting relationships between three sets of folds and foliations indicate that the host-rocks of the gold deposits have retained the imprint of three successive generations of ductile deformation resulting from regional dynamothermal metamorphism. Sericitic and advanced-argillic alteration, together with massive sulphide deposition, are interpreted to have taken place prior to the onset of the ductile deformation, based on observations 1) of altered fragments of wallrocks which are enclosed within massive sulphide bodies and were thus preserved through regional metamorphism, 2) of the syntectonic deformed pyrite, and3) of the syn-tectonic porphyroblasts of andalusite, garnet and plagioclase. The orebodies are oblate to prolate, and the pyrite-gold mineralization is typically vein-type, distributed in foliation-oblique and foliation-parallel veins. The gold-bearing structures postdate all foliations, and are associated with retrograde alteration assemblages that are pseudomorphic after pea~-metamorphic porphyroblasts in host-rocks, and with cataclasticfabrics that overprint syn-metamorphic pressure-solution features and annealing fabrics in pyrite.Retrograde gold-bearing assemblages indicate a chemical disequilibrium between the ore-forming fluids and their host rocks. This disequilibrium rules out the possibility that gold was remobilized from its own host, and suggests, instead, that the ore-forming fluids and their metal contents had an allochtonous source. Stable and radiogenic isotope analyses indicate that the fluids had a metamorphic origin, and that the associated alteration took place after the culmination of the Kenoran orogeny."

Jan 1, 1990

By B. Calver, D. J. M. Farnsworth

"As open-pit operations expanded at Pine Point, hydraulic aquifer evaluation was undertaken to establish the criteria necessary for the design of a feasible dewatering system.The extreme climate of this northern location dictated that the ore zone under extraction be rendered as dry as possible to minimize freezing effects. The design and implementation of such a system necessitated detailed hydraulic evaluation, and the problems that occurred are typical of those inherent in open-pit mining operations in northern areas.The paper describes the problem solution as approached from a mine engineering point of view, with particular reference to the practical aspects of operation and installation. The hydrological analysis used is simple and readily applicable to most open-pit dewatering problems."

Jan 1, 1969

By Paul Hughes

Purpose of Research ? What are the loading mechanics of paste against barricades? ? What is the capacity of the composite paste fill fences? ? Based on the loading mechanics of the paste, do the fill fences pose a risk of failure? Outline ? Glossary of Terms ? General Introduction ? Research Methodology ? Site Description ? Instrumentation Program ? Results ? Analysis ? Conclusions ? Recommendation for Future Work

May 1, 2008

By T. Imgrund, A. Bischoff, S. Spürk

"Specific conditions of underground coal mines at great depth, such as high temperatures, high rates of methane inflow and natural ventilation pressure provide considerable challenges for the reliable design of appropriate mine ventilation systems. For decades coal mining in Germany has coped with these extreme circumstances. Based on these experiences appropriate software tools for simulating mine ventilation networks have been developed and continuously enhanced. This paper examines differences in the simulation results and underlying calculation methods of two software solutions. The analysis is based on the comparison of FlowNetTM and VentSim DesignTM (Version 5.1) regarding the accurate prediction of fluid mechanical quantities and their validation with real measurements. A special focus lies on exceptional ventilation scenarios typical for deep coal mines, like gas inflows, fire events and buoyancy effects. The purpose of the comparison is the future utilization of the experiences gained during mining at up to 1,500 m depth for state of the art ventilation design. INTRODUCTION Ventilation is an essential component of mine operations—as providing fresh air to workplaces, diluting and removing explosive, toxic or asphyxiating pollutants and assuring sufficient climate conditions. On the other hand, the costs of ventilation contribute to a large extend to the overall operating costs of a mine, as the share in the energy consumption of a mine may be in the range of 25–50% (Belle, 2008). Accordingly, proper design of ventilation systems has been a task since early times. Consequently software for modelling of ventilation networks has been developed in order to improve efficiency and accuracy of calculations (Maleki, 2018). Compressible flow has not been considered by initial ventilation modelling software tools. In Germany, the consideration of changes in airflow density—depending on pressure and temperature—in the algorithms of ventilation simulation software has been started in 1974 by Duepre & Hofbauer. This development had been continued by the Pruefstelle fuer Grubenbewetterung (Test Centre for Mine Ventilation) and resulted in the release of a computer ventilation software named “Wetter”. The mine inspectorate of the German state of North Rhine-Westphalia, which supervises the major coal mining district in Germany, declared ventilation simulation based on compressible flow being “state of the art” in 1985 (Pollak, 1985). This pronouncement made allowance for assessing the consequences of underground fires and downtimes of main fans based on advanced software solutions."

Jan 1, 2019

By Louis Cabot

A pilot plant of the Modular Gold Processing Unit (MGPU) was designed, installed and operated, over a 8 months period, by RSW-Béroma, at the Granada Mine located near Rouyn-Noranda, Quebec. A description of the project geology, plant set up as well as exploitation results, including productivity and profitability curves, are given for a small scale mining operation in comparison with larger ones. Copyright ã 2001 CIM

May 1, 2001

By G. L. Palmer

"Abstract- ln 1986, anomalous sampling results for heavy minerals were obtained at various sites in Namaqualand on the west coast of the Cape Province. Drilling in 1987 at Graauwduinen penetrated up to 35 meters of heavy mineral-bearing Tertiary sands which extend several kilometers inland from the coast. The heavy mineral suite includes ilmenite, rutile, leucoxene, zircon and monazite, along with garnet, pyroxene and amphibole. Three deposits are recognized, two of which comprise the resource to be mined by Namakwa Sands Limited, a recently formed Anglo American Corporation subsidiary company.Mineable reserves in excess of 500 million tonnes have been delineated, sufficient to sustain mining for over 35 years at projected production rates. During the feasibility study, on-site investigations included test mining at various sites to assess mineability and to provide material for metallurgical testing in a pilot plant located at the site. Ilmenite produced at the mine will be smelted at a new facility to be built at Saldanha Bay . Saleable products comprise titania-rich slag, pig iron, zircon and rutile.During the exploration phase, company environmental guidelines were established and monitored. The feasibility study incorporated a Class 1 Environmental Impact Report, the contents of which were made public following the principles of the Integrated Environmental Management legislation."

Jan 1, 1994

By C. G. McLachlan

Abstract This paper deals with the application of the cyanide process to recover gold from a pyrite concentrate produced by means of differential flotation. This concentrate before cyanidation contains from 0.09 oz. to 0.14 oz. gold per ton, of which only about 60 per cent is recoverable. The rest is so fine that it remains interlocked in the pyrite and therefore is not acted on by the cyanide. The concentrate also contains about 15 per cent pyrrhotite and 0.4 per cent chalcopyrite, both of which are cyanicides. The cyanicidal effect of the pyrrhotite is inhibited by preacracing the pulp with lime, and maintaining a high lime alkalinity during cyanidation. The effect of the chalcopyrice is reduced as far as possible by removing those particles which are free by means of a further flotation step immediately prior to cyanidation. This involves the flotation of some very fine material. After nullifying as far as possible these two cyanicides, the concentrate is cyanided directly, i.e., without being roasted. This leaves the pyrite available for subsequent sale as a source of sulphur dioxide and sulphuric acid, and the entire residue of the cyamde plant, amounting to about 500 tons per day, 1s now being disposed of in this way. Prior to deciding on direct cyanidation, a number of laboratory roasting tests were made. These showed chat, 1f proper control were exercised, a better recovery of gold could be effected from the roasted product than by the direct method of treatment. The tests also showed that the capital cost o the plant would be much higher than that needed for the procedure adopted. The possibility of subsequently selling the pyrite for its sulphur content would also have been eliminated. Introduction A previous paper has described in considerable detail the application of the flotation process to improve gold recovery from Noranda's milling ore, and in so doing has covered the production of an auriferous pyrite concentrate. The present paper deals with the recovery of gold by cyanidation from that concentrate. This gold, though intimately associated with the pyrite, can, for metallurgical purposes, be considered as all occuring in the native state.

Jan 1, 1946

By V. Gangrade

Recirculation is the major concern associated with the utilization of booster fans. In controlled recirculation, a portion of the return air is purposely mixed with the intake air and the mixture is directed towards a working district, while the air quantity and gas concentrations in the air are closely monitored and managed. The objectives of this study were to determine the gas concentration in intake and return airways during controlled recirculation, and to determine the recirculation fraction for multiple headings. Experiments were conducted in a laboratory model to determine the effect of controlled recirculation on the quality of air circulated through the working faces. Preliminary results showed that recirculation is beneficial to ventilation planning because it reduces the build-up of air contaminants at the working faces and reduces the overall power consumptions. The experimental results were used to quantify the recirculation fraction and to calibrate ventilation models of the laboratory model. These models are used to simulate the controlled recirculation and to predict the gas concentrations in multiple headings.

Aug 1, 2013

By George J. Simandl, Donald F. Gunning

At the beginning of the 20 century, British Columbia produced a wide variety of quality dimension stone products for both domestic and foreign markets. The industry flourished until the 1930s when most of the producing quarries closed as a result of the Depression. During the 1990s, British Columbia experienced the resurgent North American dimensional stone production trend. The industry benefited from increased prospecting activity and from substantial new investment in processing equipment, particularly in the granite sector. These activities resulted in new quarry developments, the reopening of abandoned quarries such as on Granite and Fox Islands <www.quadrastone.com>, and a renaissance in downstream value-added activities. British Columbia has reestablished itself as an important, reliable and innovative source of high-quality stone products.

Jan 1, 2001

By Brandt Porter, Lawrence K. Nordell, Alexander Potapor

"Improving comminution efficiencies with better machine geometries and motions, improved nip angles, rock movement control, and voids regulation among rocks are some of the next steps to better machine performance. Recent gains (~30%) using high pressure grinding rolls (HPGRS) and vertical roller mills, in theory and practice, are based on Prof. Klaus Schönert’s academic studies (1979–1996) on rock breakage physics. More recently, University of British Columbia Prof. Bern Klein’s studies (2006–present) via the Ph.D. thesis of Z. Davaanyam (2015) further validate theory with practice from laboratory measurements used in this paper.They demonstrated ideal rock compression breakage, within HPGR and vertical roller mill machines using a piston-die apparatus. Similar rock size range is used. The piston-die confine rock breakage behavior. However, these studies do not extend to larger rocks (> 75 mm), and do not demonstrate the influence of rock voids among bifurcation of rocks during comminution. Further, machines fed with larger rock sizes, such as gyratory, jaw, and cone crushers, are not designed or evaluated for geometry nip angle efficiency.Herein we illustrate a performance gain of a new comminution machine, the conjugate anvil-hammer mill (CAHM), first presented at SAG 2011 (Nordell, 2012). The CAHM machine digests rock sizes 400% larger than HPGR, improves rock grip/nip geometry, better improves rock voids, improves surface wear life > 500%, and improves rock containment and slippage during compression. In all, the CAHM machine shows 22 potential improvements over the HPGR. Most importantly, CAHM shows a 50% kWh/ton improvement compared to the HPGR. Our studies use an advanced Discrete Element Method (DEM) computer program called ROCKY. ROCKY simulates moving boundaries, surface wear mechanics, and incorporates rock breakage physics based on the fundamentals of JKMRC T10 protocol [×] with tuned A × b breakage parameters.We calibrate rock breakage in our DEM code to mimicking both UBC laboratory piston-die and HPGR comminution measurements. We then model CAHM with these known ore and machine properties. Differences are illustrated using DEM techniques on each machine, including key points of when each: use geometry; initiate bifurcation breakage; provide a map of particle size distribution by location; illustrate the importance of controlling voids to minimize agglomeration after breakage; machine performance limits; and kWh/ton benefit."

Jan 1, 2016

By X Dai

This paper investigated the loss of cyanide via oxidation in CIP or CIL processes by relating the cyanide oxidation to its major oxidation product, cyanate. The results showed that the oxidation of both free cyanide and copper cyanide complexes are substantially enhanced by the presence of carbon. The rate of cyanide oxidation was found to occur in the order: Cu(CN)32- > CN- > Cu(CN)2-. The cyanide oxidation rate in the presence of copper and carbon increased significantly with increasing dissolved oxygen concentration, typical of CIL vs. CIP conditions. Cyanide oxidation rate of iron, zinc or nickel cyanide complexes was minimal.

Jan 1, 2011

By T. M. Ruff

A GPS-based traffic awareness and collision avoidance system has been implemented at mines with long, narrow access roads to help avoid accidents involving two approaching vehicles or vehicles following too close. A simple display in the cab of each outfitted vehicle gives an indication of oncoming traffic and a voice announcement indicates the type of vehicle that is coming as far out as 300 meters. Advanced warning of approaching vehicles is increasing driver awareness, especially around blind corners and in adverse weather such as heavy fog, snow, or rain. Speeding alarms have also been implemented and are especially critical as a vehicle approaches reduced speed areas near single-lane bridges or tight curves. A description of the system, safety improvements seen since its introduction, and implementation challenges will be discussed.

Aug 1, 2013

By M. H. Leite, R. Corthésy, D. E. Gill

"La connaissance des contraintes naturelles qui prévalent dans les massifs rocheux est un prérequis indispensable pour la conception sécuritaire et économique des excavations comme on en retrouve dans les exploitations minières souterraines. Certains chercheurs se sont attardés à colliger les résultats de mesures de ces contraintes et les ont utilisés pour produire des modèles de prédiction basés sur leur traitement statistique. Ces modèles de prédiction sont très populaires auprès des exploitants miniers puisqu’ils permettent, du moins dans les étapes préliminaires de design, d’obtenir de façon s’apéconomique mais approximative, une partie des paramètres dont ils ont besoin. Dans le cadre d’un projet initié en 1994 avec la collaboration de l’IRSST, il a été décidé de produire un modèle de prédiction englobant une partie de la zone périphérique de la faille de Cadillac, soit une zone plus restreinte que le Bouclier Canadien utilisé jusqu’ici comme région pour l’élaboration de tels modèles. Pour produire ce modèle de nouvelles données obtenues avec une technique permettant d’exercer un excellent contrôle de qualité ont été ajoutées à celles déjà disponibles. Une telle régionalisation des données de base permet d’obtenir un modèle où les intensités et les orientations des contraintes principales sont beaucoup moins dispersées que ce que rapportent les modèles publiés jusqu’à ce jour. Enfin, il est démontré que le modèle proposé pour la région étudiée est en toute probabilité plus sécuritaire que les modèles plus généraux publiés à ce jour. Knowledge of the in situ state of stress existing in a rock mass is essential to the safe and economical design of underground mining excavations. Prediction models have been published, based on the statistical treatment of stress measurement results. Such prediction models are very popular among mine operators because they allow them, at least at a preliminary design stage, to economically obtain part of the information needed, even if this information is approximative. In 1994, a research project financed by IRSST was initiated aiming to produce a prediction model that would comprise a peripheral zone around the Cadillac fault. This region is more confined than the Canadian Shield on which the existing prediction models have been based up to now. In order to produce such a model, existing stress measurement results have been used in conjunction with new stress measurements that have been performed based on a technique which allows full control of the quality of the measurements. Restricting the data upon which the model is based to a more specific region gives a model in which the intensities and the orientations of principal stresses are far less scattered than the results published to date. Finally, it is shown that the proposed model is probably safer for the studied region than the models previously published."

Jan 1, 1998

By N. Novikov, M. Jastrzebski, N. Kryzhanovskaya, D. Shevchenko, I. Kapran, N. V. Novikov, T. Koehler, B. Zaporozhets

"The PFK FeNi Smelter was re-commissioned by Solway Resources in 2002, ending a long period of economic decline in the adjacent town. In 2009 Hatch was retained to design, supply and install a custom furnace crucible that would accommodate a capacity increase from 34 MW to 40 MW and increase campaign life through binding and cooling technologies, as part of ongoing improvement efforts. The involvement of PFK personnel was critical to the successful integration of the new furnace technology with the existing process and operational practice. The furnace upgrade project was completed in 18 months during 2010 – 2011. Since start-up, the furnace has exceeded production expectations, operating successfully at 42 MW.INTRODUCTIONAfter ceasing operations in the 1990’s, the Pobuzhsky Ferronickel Combine (PFK), located in central Ukraine, was stripped of useful equipment and deteriorated while dormant. The surrounding town experienced a period of economic decline throughout the 1990’s. Solway Industries purchased the complex in 2002 and began a systematic incremental program to re-commission the smelter using both local expertise and specialists from other parts of the former Soviet Union. This led to the re-birth of PFK as a successful toll-smelting complex, and a renaissance for the surrounding economy.As part of the continuing improvement program, PFK approached Hatch in 2009 to study the possibility of a capacity expansion from 34 MW to 40 MW. It was decided, based on the results of the study, to design and install a custom furnace crucible integrating the unique PFK FeNi process with modern Hatch furnace technology. This novel approach had many benefits, including: maximum re-use of existing furnace components (off-gas, feed equipment and transformers), minimal impact on upstream and downstream equipment and building structure, and the retention of a familiar operating regime. The latter was a key factor in the success of the project, as it allowed the extensive operating expertise of the PFK staff to remain highly relevant to the upgraded furnace. This led to minimized capital investment, a rapid start-up and no significant operational challenges switching over to the new equipment incorporating Hatch furnace technology."

Jan 1, 2012

By T. Mulja, Michel Boily, Anthony E. Williams-Jones, Pierre Pilote

"The Preissac-Lacorne batholith is composed of suites of early metaluminous calc-alkalic gabbroic to granodioritic intrusives, three late peraluminous monzogranite plutons and numerous Li, Be and Ta-bearing granitic pegmatites. The Lacorne pluton is dominated by biotite and biotite + muscovite monzogranites containing abundant Be and Ta-bearing granitic pegmatites (40-80% volume). The pluton is surrounded by swarms of unzoned or poorly zoned spodumene-rich pegmatite dykes. The La Motte pluton is composed of biotite monzogranites, biotite+ muscovite monzogranites and rare muscovite + garnet monzogranites. Li, Be and Ta-bearing pegmatites are less abundant than in the Lacorne pluton and are commonly associated with molybdenite bearing quartz-muscovite-K-feldspar veins. In the Preissac pluton, muscovite + garnet monzogranites and muscovite + biotite + garnet monzogranites are the dominant rock types. The pluton rarely contains granitic pegmatites and these are generally barren. However, numerous molybdenite bearing quartz and quartz-feldspar-muscovite hydrothermal veins are observed.Li, Be andTa-bearing pegmatites display a crude spatial zonation around their parent monzogranites. Spodumene-rich pegmatites are generally unzoned or poorly zoned and are confined to the surrounding metasedimentary or metavolcanic rocks or crop out in the early gabbroic to granodioritic intrusives surrounding the monzogranites. Ta and Be-bearing pegmatites are usually concentrated towards the margins of their parent monzogranites. The highly fractionated nature ofmonzogranites (high Rb/Sr, low K?Rb, Ba?Sr, Zr/Nb ... ), their peraluminous composition (corundum normative and muscovite bearing) and the numerous occurrences of Ta and Be-bearing pegmatite dykes represent important criteria for the exploration of fertile granites."

Jan 1, 1990

By Claudia Gasparrini

"The ore microscope and electron microprobe, two common instruments for academic research, have not been used to full advantage in the Canadian mining industry, perhaps because they are not readily available to most mining companies.The present paper gives a description of the two instruments and of the manner in which, when used together, they contribute to the identification and description of mineralogical and metallurgical samples, and reviews the applications, to . date, in the mineral industry.The metallurgical applications can assist in determining the best separation technique for a particular metal or other economically important element, can provide explanations for poor recovery and/or liberation, can be used to determine theoptimum concentrate grade and can indicate environmental problems that may arise from the extraction process.In certain cases, the use of the two instruments may assist in the evaluation of new mineral deposits and in the determination of the origin of mineralization.IntroductionThe ore microscope and electron microprobe, two widely used instruments in universities and other research institutions, have not been exploited to their full potential by the Canadian mining industry.High-magnification, high-resolution ore microscopes, owned by most Canadian universities and government mining branches, are not widely used by mining organizations. The situation is very much the same with the microprobe. The geology departments of several major Canadian universities have easy access to this instrument. Fifteen of them, to the author&apos;s knowledge, own one and a few have already acquired or are planning on acquiring a second and later model. The mining branches of the Canadian Government have similar easy access to microprobes, as at least four of these instruments are available to them in Ottawa alone. The mining companies, on the other hand, except for the few larger ones which have their own research laboratories, have not been able to take advantage of electron microprobes in the past.This failure to exploit good ore microscopes and electron microprobes has been mainly due to a lack of expertise in the use of the two instruments for the study of metallurgical problems related to ore mineralogy. Government institutions providing research and test work to the industry are few in number, and are not always equipped with these instruments or are not geologically-oriented. Information provided on a consulting basis by universities and by government mining branches is normally limited, and frequently is not oriented to the needs of the mining company."

Jan 1, 1980

By J. Budac, E. Krause, C. L. Stewart, D. Wrana, S. W. Laundry

"As part of an over-all arsenic management strategy, Inco has developed a novel process that converts a by-product high moisture copper/arsenic sulphide precipitate into a crystalline copper arsenate suitable for the manufacture of wood preservation chemicals.The copper/arsenic sulphide precipitate is atmospherically leached with oxygen and sulphuric acid, producing a crude (blue) copper arsenate precipitate, elemental sulphur, and a copper and nickel containing solution. The blue copper arsenate is dissolved with sulphuric acid, the molar Cu/As ratio is raised to 2, and a crystalline copper arsenate (olivenite) is precipitated by the addition of sodium carbonate. Dissolved copper is recovered using metallic nickel (or matte) and elemental sulphur, to produce a low-moisture (low-arsenic) precipitate suitable for standard nickel-copper processing.The process was successfully piloted at Inco&apos;s Manitoba Division between September 1990 and June 1991. The copper arsenate product typically analyzed 43% Cu and 25% As, and the moisture content was about 10%."

Jan 1, 1995

By Sylvie Lévesque, Frederic Couët, Laura Pérez-Barnuevo, Cory Hennessey

Determining mineralogical characteristics of samples throughout the iron ore concentration process – from drill core samples up to the concentrate – is critical to process improvement and remediation. However, assessment of mineral proportions, liberation, and texture, although essential, can be time-consuming and costly. Thus, a mineralogical study is often not performed or only restricted to a limited number of samples. New iron ore deposits or new ore zones in active mines will bring new challenges as they are known to be problematic due to their lower grades, complex textures and presence of mineral impurities. In those cases, applied process mineralogy will be necessary to understand and to diagnose potential processing issues. To take full advantage of mineralogical information along the iron ore concentration process, new tools are being developed to provide mineralogical data based on texture, composition and liberation. In an early stage at the mine, the automated identification of drill core textures could provide essential information for the prediction of ore concentrability and grindability. In a later stage, the automated modal tool, combining the knowledge of the iron ore mineralogy of a specific deposit and the results of chemical analyses, can quantify the mineral proportions of the ore; results show good agreement between mineral estimation via chemical analysis and modal analysis using a Mineral Liberation Analyser. A bulk mineralogical analyser allowing semi-quantitative evaluation of the liberation of iron oxides is being validated. The results from the bulk mineralogical analyser will eventually be linked with the mineral proportions issued by the automated modal tool to provide complete mineralogical characteristics of iron ore samples. Ultimately, these mineralogical tools could provide valuable and timely insight for predicting concentrators’ performances or troubleshooting gravity separation processes.

Jan 1, 2016

By L. V. Chugaev, Y. M. Shneerson, P. V. Zaytsev, I. V. Fomenko, M. A. Pleshkov

"Pressure oxidation (POX) is one of the most common and reliable methods of processing gold-bearing sulfide concentrates. However, when processing concentrates that contain natural carbonaceous matter, substantial gold losses occur due to autoclave preg-robbing. The latter involves formation of gold chloride complexes under typical POX conditions (high temperatures, high acidity and high ORP) and subsequent sorption of these complexes by carbonaceous matter. Naturally, chloride ion plays a significant role in the process of autoclave preg-robbing; its concentration in POX solution has a well-marked effect on subsequent gold recovery during cyanidation of POX residue. The previous research done by SRC Hydrometallurgy showed that autoclave preg-robbing of gold could be significantly inhibited by the addition of mercury(II) compounds to POX slurry. The positive effect of mercury(II) was well pronounced both at high (>20 mg/L) and low (<5 mg/L) Cl concentrations in POX solution. The successful bench-scale laboratory testing was followed by pilot plant trials at Ore Test Facility in Blagoveshchensk, Russia. The present paper provides the results of these trials. The bench-scale testing results were verified; the optimum oxidizing parameters and reagent dosage were specified. The behavior of mercury (II) at POX pilot plant was found to be in good consistency with industrial practice described in the literature.INTRODUCTION Pressure oxidation (POX) is one of the most common, reliable, and commercially proven methods of processing gold-bearing sulfide ores and concentrates. However, when processing double refractory materials that contain natural carbonaceous matter, POX technology advantages are compromised by autoclave preg-robbing of gold. The latter occurs when natural organic carbon and soluble halides are both present in autoclave feed. Strongly oxidizing conditions of POX (high temperature, oxidation-reduction potential or ORP, and acidity) favor formation of gold-halide (mostly, gold-chloride) complexes, which tend to bond with carbonaceous matter. The exact nature and mechanism of this bonding is unknown, but as the result of this, cyanide is unable to leach gold from POX residue and the precious metal is lost to the tails (Axenov et al., 2014; Dimov, Chryssoulis, & Sodhi, 2003; Fomenko, Zaytsev, Pleshkov, Chugaev, & Shneerson, 2013)."

Jan 1, 2017

By L. Tong

The nickel laterite ore is composed of soft and hard minerals, and nickel distributes preferentially into the soft mineral rather than in the hard. Selective comminution of saprolitic and goethitic nickel laterites is investigated to upgrade nickel into the fine fraction using stirred milling. The optimal selective grinding conditions were determined through a kinetic study and the limit of selective grinding and nickel upgrade was analyzed. The breakage rates of minerals, grinding time, and the weight ratio of soft and hard minerals in the feed play an important role in selective grinding. A small breakage rate on hard minerals and a large breakage rate difference between the minerals are optimum for selective grinding. The soft mineral grade decreases with grinding time and the optimum grinding time is a trade-off of the soft mineral upgrade and recovery. The minerals weight ratio determines the limit of selective grinding. The effect of nickel upgrade is determined by both the conditions that influence selective comminution and the nickel grades in both the soft and hard minerals. The nickel grade in the soft mineral determines the limit of nickel upgrade.

Jan 1, 2015