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By D. Warkentin, T. Yeomans, R. Tavakoli, A. Nacu

"One of the most successful commercial methods of extracting gold from ores involves solubilizing gold as a gold cyanide complex, followed by adsorption of the complex onto activated carbon. The gold cyanide is subsequently eluted from the carbon to produce a concentrated gold solution suitable for electrowinning to recover the precious metals. Stripped carbon is treated in a kiln under a flowing steam atmosphere to reactivate its surface, allowing it to be reused. The aim of this study was to investigate the gold elution using a mixture of sodium hydroxide and isopropyl alcohol in both batch and continuous tests, with the eluates being electrowon on carbon foam cathodes. The effects of various factors, including alcohol content and sodium cyanide addition were studied. The addition of alcohol considerably improved gold elution kinetics, while the presence of sodium cyanide did not have a significant impact on either elution efficiency or kinetics. In all cases, efficient electrolysis was shown to be an important factor in maintaining effective carbon circuit operation.INTRODUCTION Gold dissolved as Au(CN)2- complex during cyanidation is recovered either by cementation with zinc powder, also known as the Merrill-Crowe process, or by adsorption into activated carbon through Carbon-in-Pulp (CIP) or Carbon-in-Leach (CIL) processes. Activated carbon loaded with gold is then eluted and gold is subsequently recovered by electrochemical methods. Conventional elution processes such as atmospheric and pressurized Zadra processes, involve stripping with a cyanide (0.1–0.2% NaCN) and sodium hydroxide solution (1–2% NaOH) at high temperature (90–140°C) over long elution times of 8 to 72 hours. In the Anglo American Research Laboratories (ARL) elution process, the acid-washed loaded carbon is pretreated with a strong sodium cyanide and sodium hydroxide solution (1–5% NaCN and 1–2% NaOH), followed by elution with water at 110–130°C. Solvent-assisted elution processes have also been reported, such methods use varying concentrations of alcohols (methanol, ethanol and isopropanol), ketones, or glycols to enhance atmospheric elutions at temperatures up to 95°C (Muir et al., 1985; Ubaldini et al., 2006; Espiell et al., 2008; Soleimani & Kaghazchi, 2008). The present work investigates the efficiency of isopropanol in the gold elution process, as well as the methodology of evaluating gold stripping processes in the lab setting"

Jan 1, 2017

By J. Scrimgeour

"The word ""instrumentation"" has expanded from its original meaning, which in engineering perhaps referred to measuring apparatus alone. In its broadest form, it now includes sensors, display instrumentation, standard pack-aged controllers and, most recently, the use of stored program computers for on-line process control. The paper traces the evolution, in tutorial form, of the successive application of mechanization, measurement instrumentation, automatic control, central operating systems, programmed control, process computer control, direct digital control and, finally, hierarchies of computers used for process control and corporate management as a fully integrated business system. In the field of industrial minerals, the cement industry has seen the most widespread acceptance of these techniques. Computer control has been accepted as the way of life for the blending of chemical materials and for on-line control of the cement kiln. Accordingly, the cement application is selected for further presentation in the paper. This illustrates the trend progressing from control of single loops on process variables toward the objective of total control of the product quality. The economic justification for instrumentation, centralized control, automatic control and computer control is .discussed with reference to savings in fuel, maintenance, operating labour, depreciation, power and product quality improvements."

Jan 1, 1967

By A. A. Rogozhin, E. G. Likhnikevich, S. I. Anufrieva, A. V. Kurkov

The Beloziminskoe deposit in Siberia is a large, potentially productive deposit of rare metals contained in ochreous apatite pyrochlore ores formed by weathering of a carbonatite. The ores are composed of pyrochlore, columbitized pyrochlore, monazite, apatite, magnetite, ferric and manganese hydroxide, titanic iron ore, zircon, hydromica, quartz, feldspar, and carbonates. A gravity-flotation enrichment flowsheet with application of cationic and anionic collectors has been developed. This flowsheet allows for obtaining a pyrochlore concentrate containing 44.3% Nb2O5 and 1.89% P2O5 with recovery of 55.83% Nb2O5 as well as an apatite concentrate containing 39.2% P2O5 and 1.05% TR2O3 with recovery of 62% P2O5 and 43.23% TR2O3 from ores containing 0.92% Nb2O5, 16.9% P2O5 and 0.6% TR2O3. Rare-earth concentrate containing 40% TR2O3 with recovery of approximately 10% TR2O3 was obtained at the same time. Major losses of valuable elements are related to slimes, which make up more than 50% of the ground ore. The niobium concentrate does not meet the phosphorus and radionuclide concentrations needed for the production of ferro-niobium. Acid leaching and sulfatization provided a high level of phosphorous and radionuclide removal. Conditions include hydrochloric acid pre-leaching at 75- 80°C with an 18% HCl solution for four hours and low-temperature sulfatization of acid-leached concentrate at 160-180°C for one hour followed by water leaching of the residue. The apatite concentrate could potentially be processed using nitric acid leaching. This technology is based on decomposition of apatite concentrate with 55-57% strength nitric acid with transfer of rare-earth metals into solution in the form of ammonium phosphate. This technology recovers a rare-earth concentrate containing 95% TR2O3 with extraction of 86%, and highly concentrated polynutrient fertilizer (ammophos) with phosphorus extraction of 95%. The completed research shows how complex multicomponent ores of residual soil may be processed for the extraction of niobium, phosphorus, and rare-earth products.

Jan 1, 2016

By R. A. Campbell, R. R. Rogers

"AbstractThe experiments described show that crude bismuth metal containing up to 5 per •cent lead, 0.14 per cent silver, 0.015 per cent copper, 0.02 per cent iron, .and small amounts of antimony, nickel, and tin may be refined to a bismuth content of 99.98 per cent by distillation followed by chlorination. It also is shown that bismuth trichloride of high ,purity may be produced by passing chlorine over hot •crude bismuth metal and allowing the resulting vapours to •condense in a cooler .part of the system.IntroductionBISMUTH is used in the production of alloys and pharmaceuticals. During 1952, the New York price for the refined metal was $2.25 per pound in ton lots.Some months-ago a Canadian producer requested the Mines Branch to investigate methods of refining the bismuth which they had been producing. Their crude product had been selling for $1.50 to $1.70 per pound and it was desired to increase its purity to at least 99.98 per cent so that it could be sold for $2.25 per pound."

Jan 1, 1955

By L. Trytten, S. Bass, P. Nawrocki, J. Mercer

The Sherritt Fort Site nickel refinery and fertilizer plant has been operating continuously since 1954. The ammonia leach process uses ammonia and sulphuric acid, producing nickel and cobalt and an ammonium sulphate byproduct. One of the features of an ammonium sulphate based process is the aggressive nature of ammonium sulphate to concrete and structural steel. After six decades of operation, portions of the structural steel and concrete at the Sherritt facility have become degraded. Infrastructure replacement programs started in earnest more than a decade ago with pipe racks and electrical infrastructure, and have now progressed into building steel. Replacing and repairing this infrastructure within the tight constraints of an operating plant poses several difficult challenges. This paper will outline the approach taken to accomplish this difficult work, and discuss key learnings from the ongoing program.

Jan 1, 2015

By Marc-André Villiard, C. St-Onge, V. Silla, J-C Milot

Rio Tinto Fer et Titane (RTFT) operates a metallurgical complex in Sorel-Tracey, Canada. In the Ore Preparation Plant (OPP), ilmenite ore is roasted through four parallel rotary kilns generating 95% of the plant wide sulphur dioxide (SO2) emissions. RTFT proactively set an annual emission cap for SO2 to be achieved by 2015. To achieve this targeted SO2 reductions, a technology evaluation and selection exercise was carried out, followed by detailed engineering and implementation. After a detailed evaluation of SO2 scrubbing technologies, the Circulating Dry Scrubber (CDS) system was selected as the most appropriate desulphurization system for this application. The system was implemented and commissioned from 2013 to 2015. General performance testing conducted in May 2015 demonstrated that the system achieved and surpassed the anticipated design values in terms of SO2 removal efficiency and hydrated lime utilisation. This paper summarizes the SO2 technology selection process, design features of the selected technology, project implementation and final performance testing of the SO2 abatement system.

Jan 1, 2015

By Marlin E. Sandlin

NORTH-CENTRAL United States is now, and will continue to be, a natural market for Canadian crude oil. This area is a natural market for many basic reasons. There are no physical barriers along the border of our countries. This market is in dose proximity to Canadian production. This market is already joined by crude oil pipe-1,ines to numerous producing areas of Canada. The tariff barriers are reasonable. We are not handicapped by mandatory quota restrictions. There are many of us who desire lo sell Canadian crude oil in this market. Further, and what is really important, there are many of us who desire to buy Canadian crude oil for this market. It is fundamental that for crude oil to be sold in the world market, it must ?be sold at competitive prices. At the same time, it is important that such competitive price must result in a fair price for the crude oil at the we1lhead. The factors of nearness to market, cheap pipe line transportation, and reasonable United States tariffs, all tend to make ?possible a competitive market and a fair wellhead price.

Jan 1, 1958

By G. Granata, C. Tokoro, M. Matsuoka, K. Horiuchi

"Given the high demand of copper and the lack of new high-grade deposits, low grade copper ores containing copper oxides and refractory sulfides need to be processed as well. However, in order to recover copper from refractory copper ores, the leaching performances should be improved. In this study, we investigated the effect of the mechanical activation in the leaching of copper from covellite. The influence of a mechanical treatment by planetary ball milling on leaching rate in sulfuric leaching media was evaluated by using X-ray diffraction (XRD), mineral liberation analysis (MLA) and X-ray absorption fine structure (XAFS). Results showed a significant increase in copper leaching from around 50%up to 100% along with an improvement of the leaching kinetics when using planetary ball milling. XRD spectra showed the disappearance of the covellite peak from (101) face, thus suggesting the amorphization of covellite associated with the use of planetary ball milling. XAFS results showed that the coordination number of Cu changed from 6 to 3, thereby confirming the effectiveness of the mechanochemical effect.INTRODUCTIONDuring the last decades, while the copper grade in copper ores has been decreasing, the concentration of impurities such as arsenic tends to increase, thus requiring for the processing of low grade copper ores. For a suitable processing of copper minerals, hydrometallurgical processes are preferable due to the lower costs, the lower environmental impact and the easier implementation (Watling, 2006). However, for an economical recovery of copper, the leaching performances must be improved.Among the recent advancements in leaching technologies, the mechanochemical activation allows for an improvement of the leaching performances by means of high-intensity grinding(Mohammadabad et al., 2016). In the first place, the improvement is the result of the dramatic decrease of particle size, which results in an increase of the mineral surface area and the consequent enhancement of leaching kinetics. Furthermore, the intense mechanical stress due to the high-intensity grinding could induce the rupture of the crystal structure producing a decrease of crystallinity. Such changes of the mineralogical structure, also known as mechanochemical effect, can lead to more leachable mineral, thereby resulting in a greater dissolution of copper. Last but not least, whereas the mineral surface might undergo passivation during leaching, the high-intensity grinding can continuously refresh the surface of the mineral, thus exposing portions of unleached bulk mineral."

Jan 1, 2017

By N Berkowitz

Slurry pipelining, as now under-stood and practised, can only command marginal interest in Canada, as long-distance railway freight charges in this country are generally lower than slurry pipeline tariffs. Several alternatives to conventional slurry transmission are, however, now emerging, and two such alternatives are briefly discussed with reference to coal pipelining. In one, coal is transported as a suspension in oil; the other contemplates the movement of paste "slugs." Preliminary economic estimates indicate that the resulant process simplification and adoption of common carrier principles could lead to cost reductions that might make Western coal competitive with imported fuel in the power generating stations of eastern Canada. R ECENT appraisals of slurry pipelining techniques, some-what incongruously 'based upon the performance of successful installations (1,2), are making it increasingly apparent that current solids pipelining methods can only command marginal interest as methods of bulk commodity transportation (3). Although some uncertainties remain in matters of detail, it is now generally conceded that long-distance slurry pipelining cannot compete against rationalized railway transportation unless movement of

Jan 1, 1963

By John I. Sharpe

Masses of pyritic copper and zinc ores are entrapped along the contact zone between two volcanic groups in the Matagami area. The upper limits of the sulphide concentrations tend to form concordant contacts against lava or cherty tuffite units of the younger group; the lower extremities tend to either follow transverse structures or merge with zones of dispersed sulphides. The sulphides are deformed and intruded by folded dykes. Close relations between metallization boundaries and volcanic lithology and stratigraphy, and a preliminary investigation of the fabrics and crystallization temperatures of the sulphide masses, suggest that the copper and zinc (but; not necessarily all the iron sulphides) were emplaced at h1gh temperatures during volcanism in near-surface lithological-stratigraphic traps. Introduction T HE Matagami area is centered 120 miles north of the Val d'Or and Noranda camps in north-western Quebec. For the present purpose, it is considered to comprise a 155-square-mile area in Isle-Dieu, Galinee and Daniel townships which encompasses the main sulphide masses. Airborne geophysical surveys within this area in 1956 led to the discovery of a large sulphide body -the.

Jan 1, 1965

By C. Prévost, V. Leclerc, R. Pinto, M. Ruel

"A buffer’s ability to dampen production variations is directly related to its size. Small buffers cannot handle large variations in production, resulting in production losses when their inventory is depleted or saturated. This paper presents a predictive control algorithm used to regulate the inventory in a buffer of limited size, subject to large production variations caused by an upstream batch process. The algorithm was designed to manage the acid flow rates in an acid regeneration process, servicing batch leach reactors at Rio Tinto Fer et Titane, in Sorel-Tracy, Québec. The objective was to increase production by reducing equipment downtime caused by imbalances in the acid tanks servicing the leach reactors. The controller attempts to maintain acceptable acid tank volumes by optimizing the leach reactors acid/slag ratio and reaction time as a function of anticipated acid needs, all while maintaining product quality.INTRODUCTION Some beneficiation processes in extractive metallurgy require processing bulk material in batches. Typical examples of metallurgical beneficiation batch processes are smelting, leaching, electrowinning, elution and carbon-in-pulp. These processes are often situated midstream in an ore beneficiation flow sheet and either receive or transfer ore to continuous processes. Batch processes, by their very nature, introduce large variability in the flow sheet, because they process large finite quantities of material at nearly periodic time intervals. In order to dampen variations in production, various buffers–tanks and stockpiles–are utilized to accumulate ore upstream and downstream of batch processes. A buffer’s ability to dampen production variations is directly related to its size (Phillis & Gumede, 2011). Small buffers cannot handle large production variations, resulting in equipment downtime when their inventory is depleted or saturated (Everett, 2010, Berton et al., 2013). Consequently, the batch equipment production rates must be adequately managed to minimize production losses, attributed to depleted or saturated inventories, while maintaining product quality. Algorithms that anticipate or predict future production variations are often utilized to regulate buffer inventories, subject to large flow rate variations (Salvo et al., 2002; Bonvin, 2013). This paper presents a predictive control algorithm used to maintain an acceptable volume in a spent acid tank servicing several batch leach reactors. The algorithm is implemented at the acid leach plant of Rio Tinto Fer et Titane, in Sorel-Tracy, Québec."

Jan 1, 2017

By B. Drew, K. Budna, C. Wenzl, D. Gregurek, A. Spanring

"The metallurgy of nickel and cobalt and of copper is closely interlinked when processing sulfidic Ni-Co ores and Cu-Co ores. The respective furnaces are typically lined with magnesia-chromite refractories, which are exposed to multiple and complex stresses. The selection of the processing route, furnace type and slag system will be dictated by the specific ore type available, this will determine the individual refractory wear mode. This paper evaluates the common refractory wear mechanisms, namely infiltration, spalling and chemical attack by various slag systems, as well as sulfur attack, as observed when processing primary sulfidic ores. All these wear parameters, which are discussed in this paper, lead to a severe degeneration of the brick microstructure and a decreased lining life. Therefore, a detailed investigation and understanding of the wear mechanisms through “post mortem studies” is an important prerequisite for the refractory producer. Based on such research results, combined with specific process knowledge, appropriate brick lining solutions for nickel and cobalt processing furnaces can be recommended.INTRODUCTION The metallurgical production of cobalt and nickel and of copper is closely interlinked to the mineralogy of the respective ores: cobalt is found in African Cu-Co ores as well as in Co-rich nickel ores (laterites and sulfides). Also, Co-bearing secondary raw materials contain the mentioned elements in different contents. In pyrometallurgical processing of sulfidic ores, cobalt is generally recovered as a by-product during the production of copper and nickel, whereas it is normally not recovered separately during the processing of nickel laterites but remains in the FeNi product. Besides various hydrometallurgical production routes, the pyrometallurgical processes involved comprise smelting (i.e., production of a Cu-Ni-Co-Fe matte in electric or flash furnaces), converting and refining (i.e. removal of Fe and S as well as other elements from matte by oxidation). The ongoing trend to use higher oxygen enrichment in process air enables higher intensity processes but also increases the oxidation potential in the vessel. Therefore, during smelting and especially during the oxidative treatment in converting and refining, some amounts of valuable metals are also transferred to the slag in their oxides form. A subsequent slag treatment is then applied for recovering valuable metals from the slag, namely allowing an economic material stream handling and minimizing metal losses. This is often done in a slag reduction furnace. Additionally, copper and nickel are very good collectors for precious metals and platinum group metals (PGMs) - therefore, depending on the content of these metals, an additional refining process is used to recover these valuable metals from the matte or metal phase (Elvers et al., 1997; Davenport et al., 2002; Crundwell et al., 2011)."

Jan 1, 2017

By Dong-Hyeun Koh, Yun-Soo Lee, Min-Seok Kim, Hyoung-Wook Kim

High strength AA7068 (Al - 7.88 wt.% Zn - 2.68 wt.% Mg - 2.07 wt.% Cu) aluminum alloy strip was successfully fabricated by horizontal-type twin roll casting. A simulation technique was used to obtain the range of casting conditions for fabricating strip without defects. The cast strip with thickness of about 5 mm was hot rolled, intermediate annealed, cold rolled to final thickness and subsequently annealed at various temperatures. Tensile properties of annealed and the aged specimens were evaluated at ambient temperature. Tensile strength and elongation of the annealed sheet are about 365 MPa and 28%, respectively. Also, the tensile and yield strength after the aging at paint baking condition (180 °C x 0.5 h) are 586 MPa and 551 MPa, respectively. Therefore, it is expected to show good formability prior to press or stamping and also provide high dent resistance after paint baking treatment.

Jan 1, 2015

By M. A. Halim, V. I. Lakshmanan, Z. Jankovic

An innovative mixed-chloride process for the separation of iron from lateritic ore is described. The separation of Fe(III) from leach liquor is an important process step for the recovery of nickel and cobalt. The patented process of Process Research ORTECH Inc. uses a lixiviant containing hydrochloric acid (HCl) and magnesium chloride (MgCl2) for the leaching of lateritic ores/concentrates followed by the selective solvent extraction step of Fe(III) over other value metals such as Ni and Co. The use of MgCl2 increases the activity of the hydrogen ion in the lixiviant, which reduces the consumption of HCl in the leaching stage and enhances the formation of HFeCl4-, thereby increasing the solvent extraction efficiency of Fe(III) with ketone. The process produces high purity iron oxide (Fe2O3) and regenerates HCl by the pyrohydrolysis of the FeCl3 rich pregnant strip solution. The developed process flowsheet is in closed loop, economically attractive and environmentally friendly.

Jan 1, 2015

By L. Drisdelle, S. Gendron

"Survival in today's business climate requires participation of all employees in a Total Quality Management Program encompassing everything - ""safety, quality of products, quality ofet1ch and every job done, and of course production "". We all know what needs to be accomplished, but struggle with how to do it, especially in an industry which has not always experienced management/union cooperation, and mistrust is still present.This paper describes a process to improve team work and employee involvement in Inco's nickel carbonyl refinery at Copper Cliff The process involves facilitatorship training for all employees, and a system for reinforcing and accomplishing the required behavioural change. The system is described in detail and a number of examples are presented. At the refinery, the staff is starting to understand as Max DePree recently wrote ""Without Quality Behaviour, you cannot have Quality Product"". IntroductionThe Copper Cliff Nickel Refinery (CCNR) is Inco's largest and most modern nickel refinery, which celebrated its twentieth year of successful operation in April 1993.The heart of the refinery is the Inco pressure carbonyl (IPq plant which produces high purity nickel pellets and specialty powders by refining an approximate 80% nickel granule feed. The carbonyl plant is a modem chemical plant with very special and demanding requirements for safety and environmental protection due to the toxic nature of the refining gas.Since 1987, there has been an emphasis at CCNR on a comprehensive Total Quality Improvement (TQI) Program which was designed based on recognizing customers' needs for improved systems for quality management. This program is customer oriented and comprises such elements as team organizational concepts, customer audits, process assessment and internal quality auditing.A detailed review of progress was made in early 1991 and it became apparent that the ""ownership"" of the TQI program was not broad based. In fact, the program was very much a staff driven effort and fell far short of total employee involvement and relentless continuous improvement that are now considered essential to remain competitive and stay in business.Inco staff has now come to regard that early phase of our TQI program as ""the technical aspects of total quality improvement"".The safety experience was also puzzling. Even though the safety statistics were good with an average lost time frequency of 1.6 for the last five years, the perfonnance improvement had plateaued and remained pretty much the same. Clearly a new approach was required if significant progress and continuous improvement was to be made."

Jan 1, 1994

By V Dolmage

In 1957 and 1958, ten topographically suitable damsites were investigated along the Peace river between Finlay Forks and Hudson Hope, B.C. Of these, three were eliminated after a reconnaissance survey indicated that the geology was unsuitable for the 650-ft.-high dam contemplated. ?After extensive drilling, five other sites were deemed unfeasible because of geological factors and, in 1959, the two remaining sites were designated as being suitable, one for the high dam and the other for a low dam downstream. The sites are located in the Peace River canyon, on the west and the south? side of Portage mountain, west of Hudson Hope. The site for the large dam, the Portage Mountain dam, has since been investigated by surface mapping, thousands of feet of diamond drilling, a seismic survey, laboratory rock tests and on-site grouting tests in order to establish the possible effect on the dam of all facets of the foundation rocks. Three diversion tunnels, 50 ft. in diameter and 2,200 feet in length, have been driven through massive sandstone and shale, and an intake cut, 500 ft. in length, 200 feet in width and 200 feet in depth, has also been excavated in rock.

Jan 1, 1963

By D. M. Maijer, S. M. Mohseni, A. B. Phillion

The microstructure evolution kinetics of aluminum alloy B206 during artificial aging has been investigated using non-isothermal calorimetry. A combination of differential-scanning calorimetry (DSC) and tensile tests have been utilized to develop an Avrami model to predict the precipitation kinetics as a function of the thermal processing parameters. The Avrami coefficients, found based on a Kissinger analysis, compare well against those reported in the literature for aluminum-copper alloys. The rapid precipitation kinetics predicted by the Avrami model at temperatures higher than 200°C were assessed through a qualitative comparison against hardness measurement results. In contrast to the continuous hardening observed at 150°C, the material softens with continuing heat treatment at 250°C resulting in an overaged state. This can be attributed to the rapid precipitation kinetics at this temperature, leading to the termination of the precipitation-hardening effects at early stages of artificial aging.

Jan 1, 2015

By C. Tissot, R. Palmer

"Due to the low concentrations of gold, direct measurement of gold concentration in ore on belt has not been seriously considered to now. Pre-concentration or sorting strategies have largely consisted of particle sorting based on secondary characteristics such as colour, which can be successful in select cases. CSIRO has produced sample measurement results using gamma activation analysis of ~300 gm samples with accuracies of around 30 ppb at best. With this encouragement, a feasibility study into gold ore measurement on belt for the purpose of sorting pods of gold ore has been undertaken. The study described here included, prototype design options with existing industrial Linacs, extensive Monte Carlo modelling of measurement sensitivity and shielding, further sample measurement, a study of the interaction of target measurement accuracy and sorting efficiency, and a rough estimation of potential economic benefit. The projected model sensitivity of around 0.1-0.15 ppm (1 standard deviation) in 10 seconds for 1 ppm average feed result in good bulk sorting performance and intriguing economic potential.INTRODUCTION Pre-concentration or sorting strategies for gold ores have largely consisted of particle sorting based on secondary characteristics such as colour or density, which can be successful in select cases (Klein, 2010). No method is available to measure gold content for sorting in particles or even in bulk on belt, principally due to the low concentrations of gold present. In fact, in many cases it is difficult to do rapid bulk grade measurements of base metal ores with concentrations many orders of magnitude higher. By a fortunate quirk of nature gold is particularly amenable to gamma activation analysis (GAA). CSIRO has performed extensive work in GAA of samples of crushed ore (Tickner, 2017). This has resulted in the Photon AssayTM technique that is currently being commercialised through the CSIRO spinoff company Chrysos. The technique relies on the recent availability of industrial high intensity X-ray sources such as Linacs which are currently being used in industry for security, medical and sterilisation applications. This development has led to CRC ORE funding a feasibility study to determine whether on-belt measurement of gold concentration is possible at a rate and accuracy sufficient to be useful for bulk sorting, where pods of ore are diverted rather than individual rocks. The study in the first instance is based on Monte Carlo modelling that has successfully predicted the performance of the sample based gold measurements. As well as the measurement feasibility consideration was also given to the likely heterogeneity of gold ores and hence the degree to which useful separation could be achieved. This is then tied to a back of the envelope evaluation of the order of magnitude economics of bulk sorting in an example deposit."

Jan 1, 2017

By K. Barbetti, J. Avraamides

"The processing of gold ores with high silver contents can provide operational challenges, such as high cyanide consumption, retardation of gold leaching and competition during adsorption stages of carbon-in-pulp/leach/column (CIP/CIL/CIC) circuits. In particular, the silver, which is about 1.5% of the value of gold, competes with gold during carbon adsorption due to its higher concentration in many Ag-Au ores, potentially leading to gold solution losses. Fresh and partially fouled (barren and regenerated) activated carbons were evaluated at various Ag:Au ratios and total metal concentrations with regard to the adsorption kinetics and equilibrium loadings. Conventional Freundlich isotherms were found to be highly inaccurate for predicting equilibrium loadings in the competitive adsorption environment. An integrated model, which incorporates competitive adsorption kinetics with a modified competitive adsorption isotherm model has been developed and validated using plant and laboratory data. The model performance and some of its salient features will be discussed.INTRODUCTIONThe processing of gold ores with high silver contents can present a range of operational challenges, such as high cyanide consumption, retardation of gold leaching and competition in carbon adsorption circuits. Silver is often present at significantly higher concentrations than gold in many gold-silver ores and competes with gold in carbon adsorption circuits, limiting the gold loading rate and capacity, resulting in gold solution losses and reduced gold recovery.Curtin University’s Gold Technology Group has evaluated fresh and partially fouled (barren and regenerated) activated carbons at various Ag:Au ratios and total metal concentrations to determine the adsorption kinetics and equilibrium loadings for gold and silver. Conventional Freundlich isotherms were found to be highly inaccurate for predicting equilibrium loadings in the presence of both gold and silver.An integrated model, which incorporates competitive adsorption kinetics with a modified competitive adsorption isotherm model has been developed and validated using plant and laboratory data. This paper describes the model performance and some of its salient features."

Jan 1, 2016

By Georges Houlachi, Raynald Labrecque, Jean-Noël Cloutier

"Electrodialysis (ED) is an electro-membrane technology based on electrochemical process using electrical energy for the production of chemicals. The process can be used for concentrating, extracting, separating products, modifying molecules, purifying solutions, pH adjustment and regenerating salts into their base and acid. This paper reviews the principle of ED, present some of the different options and discuss applications that are relevant to the hydrometallurgy and mining industries for the treatment of effluents focusing on recovery of chemicals (acid and metals) and recycling of water minimizing the environmental footprint.INTRODUCTIONElectrodialysis (ED) is usually defined as an electrochemical separation process in which electrically charged membranes and an electrical potential difference are used to separate ionic species from an aqueous solution and other uncharged components [1]. ED technology consists of an electro-membrane technology based on an electrochemical process using electrical energy for the production of chemicals. It is a method combining electrolysis and dialysis was proposed for the first time in 1890 by Maigrot and Sabates [2]. In the late 1930s Teorell, Meyer and Sievers discussed membrane phenomena, revealed membrane potential, electric conductivity, transport number [3]. Meyers and Strauss introduced a multi-compartment ED apparatus consisting of two electrodes and a stack of ion-exchange membranes between them [1]. They succeeded to double the concentration of a KCL solution [3- Tarleton]. In general, ED consumes less energy than electrolysis to perform salt splitting. In that regard, one can expect an energy reduction of about 30% [4–5]. ED offers a great versatility in the domain of separation processes. Indeed, it can be used for concentrating, extracting, separating products, purifying by desalination, pH adjustment and regenerating a salt to acid and base components. This paper reviews the principle of ED, presents various options available and discusses potential applications relevant to the mining and metallurgy industries with economics of some successful industrial applications."

Jan 1, 2016