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By M. C. Makepeace

"It is the objective of designed experiments to obtain more information for less material and process cost than can be obtained by traditional experimentation. In this paper, the fundamental concepts on which the statistical design of experiments is based are briefly re-viewed according to the following outline: The Experiment The Design The Analysis Two simple 2"" factorial experiments are presented as examples."

Jan 1, 1967

By G. Bonin, R. P. Preston

"This paper presents a series of case studies where spherical camera photographs were used to generate 3D shaft models using photogrammetric methods. The shaft models were, checked for accuracy by comparing them to overlapping laser scan data, provided survey data or idealized shaft models. Short lengths of model were found to more accurately reproduce the shaft surface, with a best observed accuracy of 8 mm. Longer models encountered errors with accumulated errors as exhibited by slight deviations from vertical or slightly conical model shape. At present, the models are considered acceptable for general documentation and gross change detection. INTRODUCTION Shaft inspections are required by mining regulations in many jurisdictions and are commonly completed by trained mine personnel via visual inspections. This can be time consuming and prone to errors due to lapses in attention and the rapid travel rate required to inspect an entire shaft in a reasonable amount of time. Similarly, because of the time requirements, there can be impacts on other aspects of mining as a result of occupying the shaft for inspections. Spherical cameras with supplemental light systems offer a modern addition or alternative to conventional inspections. These cameras can be lowered relatively quickly to collect high definition, fully illuminated videos of the shaft that can be reviewed in detail later while the shaft returns to service (Gillis et.al., 2019). The use of cameras offers a further opportunity for valuable survey data generation from the same original data stream. The video data can be processed into three-dimensional (3D) models using Structure-from-Motion (Westoby et al., 2012) based photogrammetric methods. Depending on the quality of the source video and availability of survey control (required for all photogrammetry models) these models can be very accurate. Shaft surveying can be conducted with traditional theodolite methods but such surveys are time consuming and limited in their data density. Similarly, scans can be completed using conventional terrestrial laser scanners, but this requires a significant number of distinct setups to provide sufficient overlap between scans. Work is being conducted both on the laser scanning (SLAM, Durrant-Whyte & Bailey, 2006) and photogrammetry fronts towards kinetic scanning (Benecke, 2017) systems. The major advancement which is permitting these kinetic systems is Inertial Measurement Units (IMUs) which can provide localization in GPS denied environments and reduce errors associated with the open traverse format associated with shaft scanning."

Jan 1, 2019

By G. H. Charlewood, J. W. McBean

"One hundred years after being developed, the diamond drill is still an essential tool in mineral exploration. The basic principle is unchanged, but the technique has been revolutionized, particularly in the past fifteen years. The cost of core drilling has not kept pace with the rising cost of living. The price of machinery, supplies and labour in drilling has doubled and trebled since 1946. Some of the techniques which have made it possible to hold the price line are described."

Jan 1, 1967

By W. M. Williams

The Canadian steel industry is now in many ways a mature one, having achieved many technical successes during its hundred-year history. It is interesting to look back over this period, to learn something of the histories of the different producers and of the people and forces that shaped their development. The following article provides a thumbnail sketch of the Canadian steel industry as it exists today. It is intended for the general reader, not for the specialist who will want to consult the several books and theses written on the development of the industry during the last hundred years. The famous Les Forges du Saint-Maurice, an important iron producer for a century and a half, provides a natural historical starting point for a look at the four major players - Dosco, Algoma, Stelco and Dofasco - who have provided most of the hundreds of millions of tonnes of steel, in every form from horseshoes to tinplate, needed in the twentieth century. The smaller companies which have sprung up in the last 20 or 30 years are dealt with briefly - but only because their history is so recent. Not so long ago the mini-mill, based on scrap rather than on the blast furnace, was thought to be specially suited to the economies of the smaller developing countries of the Third World. However, recent history has made it evident that the small plant, specializing in a few basic products (e.g. reinforcing bar) or taking advantage of special circumstances, can successfully compete with the large blast furnace/primary steel producers.

Jan 1, 1999

By Grant J. Goddard

"The Iron Ore Company of Canada (IOC) has been in operation for over 30 years. Today, and in the future, technology and its application will play an ever more critical role in the company’s business success.The Carol Mining and Concentrating (CMC) division of IOC is energetically applying technology today to enhance performance and results, and is aggressively exploring opportunities to apply technology to support improved business results in the future.A critical area of focus is the application of technology to maintenance management performance. CMC has taken a “back to basics” approach to the fundamentals of maintenance management in 1995 and 1996. In parallel, the mine is aggressively implementing its Vision 2000 maintenance integration plan. This plan is targeted at levering the energies applied to sound maintenance management fundamentals as the company moves to a fully condition based maintenance approach.This paper discusses some of the strategies, key technologies and objectives of theVision 2000 maintenance integration plan at the mining operations of IOC."

Jan 1, 1996

By Charles Camsell

THE Northwest Territories covers a very large area-more than one-third of all Canada-and its most northern point, Cape Columbia in Ellesmere island, is distant only 500 miles from the Pole. Our first knowledge of the Arctic Archipelago, of which Ellesmere island forms a part, resulted from a gold-mining venture in Queen Elizabeth's reign. The English navigators of that time were eager to find a north-westerly and shorter and Jess hazardous route to the riches of China and Japan than that which Magellan had discovered, but they were unaware that the continent then known to bar a direct route extended in great width far to the north. Frobisher was one of these navigators. He reached in 1576 the bay in Baffin island now named after him, convinced that he had found a passage connecting the Atlantic with Asiatic seas. Forced to re-turn after ordeals in which ice, wind, and Eskimos flayed formidable parts, he brought back, among other novelties, a piece o black stone which had been picked up casually by one of his officers, and gave a little of it to the wife of one of the venturers, or financial backers of the enterprise. To quote now from Hakluyt: ? 'She by chance threw and burned it in the fire so long that , at length being taken forth and quenched in a little vinegar, it glistered with a bright marquesset of gold. Whereupon the matter being called in sorne question, it was brought to certain goldminers in London to make assay thereof, who indeed found it to hold gold and that very richly for the quantity." On the strength of this, the venturers, anticipating much profit, launched a second expedition to secure more of this stone, and 143 persons, including 14 miners and finers, set forth in 1577 and returned the same year, with, however, 200 tons of another mineral. Influenced by glowing accounts of veritable mountains of this mineral and by assays made after "additaments"-that is how "salting" in those days was described-the venturers, including Elizabeth, supplied funds for erecting a smelter and refinery at Dartford and outfitting a stilllarger expedition. And so, in 1578, fifteen ships departed with the Queen's blessing, for the same remote shores. After many mishaps, they returned with over 1,000 tons of the mineral, but when it yielded very little of value at the works in Dartford, the? Company of Venturers was forced into liquidation. Though our first prospector and miner was rather inconsiderate of the investors, he proved the existence of an archipelago, hitherto unknown, and secured much information about the new land and its dwellers.

Jan 1, 1938

By D. Karpoff

"IntroductionUNTIL the recent discovery and development of deposits at Allard Lake, on the Lower Romaine river, practically the whole of Quebec's - and indeed of Canada's - production of ilmenite had come from deposits in the vicinity of St. Urbain, Charlevoix •county, a village about eight miles north of Bay St. Paul on the north shore of the St. Lawrence, some sixty miles below the city of Quebec (see Figure l) . Although these deposits were known nearly three hundred years ago and were worked in a small way during the years 1872-74, when a charcoal blast furnace was operated by the Canadian Titanic Iron Company for making white pig iron, it was not until 1908 that more or less continuous production commenced and has •continued to the present by the American Titanic Iron Company. The whole of the output has been exported to the United States.The ilmenite occurs in lenses •and dyke-like bodies within anorthosite. Production has come chiefly from three deposits: General Electric, Furnace, and East and West Coulombe. During 1951 -52, an extensive diamond drilling programme was carded out under the direction of the writer to test the Furnace and the East and West Coulombe deposits (Figures 2 and 3), which form part of the property of St. Lawrence Iron and Titanium Mines, Limited. The average tenor of the orebodies encountered in the course of the drilling was 38.60 per cent TiO2 and, in addition to these high-grade •bodies, there was found a very considerable tonnage of lower grade ore."

Jan 1, 1953

By F. Tanaka

Copper losses to discard slag have long impacted on the profitability of copper smelters. Businesses based on the treatment of secondary materials have also revealed that copper losses are indices of precious-metals losses. Many custom smelters are thus required to obtain more reliable controls for reducing copper losses than ever before. Mitsubishi Materials Corp. has cooperated with academic research institutes in conducting research projects on the pyrometallurgical fundamentals of copper smelting systems, including mutual evaluation of magnetite behavior between synthetic and industrial slags. The state-of-the-art pyrometallurgy has subsequently been introduced to Naoshima smelter for controlling the Mitsubishi process. The revised controls function successfully and the operational results demonstrate that avoiding the discharge of solid magnetite from the S-furnace is quite effective to reduce copper losses. Magnetite behavior has been controlled over the Mitsubishi process so as to reduce copper losses while satisfying the needs of recycling businesses growing in Japan. In-situ estimation of magnetite behavior using the absorbed heat from the melts to cooling water will also be discussed.

Jan 1, 2007

By L. I. Kiss, S. Perron, D. Toulouse, S. Poncsák, A. Perron

Bubbles play an important role in many industrial processes. In a Hall-Heroult cell, used for aluminum production, bubbles contribute to induce flow in the cell. The induced flow is important for the thermal balance of the cell as well as for the distribution and dissolution of the alumina. The existence of the bubble layer does not have advantages only. It increases the voltage of the cell and causes deformation along the cryolite-molten aluminum interface. The role of the anode inclination in the behaviour of the bubble layer as well as in the hydrodynamics of the bath is not clearly understood. In this work, the effect of the anode inclination angle on the bubble driven flow is studied in an industrial scale air-water model. The inclination angle is varied up to 5° from the horizontal. The instantaneous flow field is captured by Particle Image Velocimetry (PIV) system. The mean velocity fields were calculated by ensembleaveraging the instantaneous velocity fields measured at different time. The existence of the counter-flow in the interpolar space and the vortex in the side channel has been confirmed. Furthermore it has been observed that the effect of anode slope on the velocity field is weak.

Jan 1, 2006

By Shanjun Mao

This paper summarizes current achievements of Digital Mining in China, puts forward the concept, framework and key technology of Smarter Mining, and finally points out that there is still a long way to go in order to acheive Smarter mining.

Aug 1, 2013

By W. L. Falconer

"IntroductionThe very recent emphasis on the importance of the northern portions of the Alberta basin as a prospective oil province has led the oil companies northward into new and undeveloped territory. Northern Alberta is a land of continuous forest, covering a plains-type topography. The plains are only occasionally broken by sharp, broad river valleys. Tributary streams head up quickly and very soon lose themselves in large undrained areas. It is these pseudo-swamps that cause most of the troubles and headaches of the oil explorer.The rivers have served as the main transportation arteries since people first ventured into this area. The bush is being pushed back, but the advance is slow and there is very little more than trappers' trails beyond a few miles from the Northern Alberta Railway lines and the recently built Grimshaw or McKenzie Highway. Indeed, bush and muskeg flank many miles of the railways and roads within as close a distance as fifty miles of Edmonton. Northern Alberta is pioneer country in the truest sense of the word, and our greatest problems derive from this fact. In all pioneer areas, the first requirement is the development of access roads, and before active oil exploraton can get down to the job at hand these roads and trails must be an accomplished fact. There are two factors in Northern Alberta which offer discouragement to the oil explorer: the first and greatest stumbling block is presented by the numerous muskegs, large and small; the second is the fact that road building uses up so much of reservation time. Of course, the second is aggravated by, and a direct result of, the first. So we come back to the main problem facing the development of the north - the muskegs."

Jan 1, 1950

By James Stenhouse

Abstract The aqueous oxidation of pyrite in caustic solutions under oxygen pressure was investigated by measuring that effect of reaction variable on oxygen consumption by the reactions. From the results of this investigation, a model for the process has been proposed. In this model, sulphur diffuses as a positive ion through an oxide layer which forms on the sulphide particles and is then oxidized to sulphate ion. Iron is oxidized by substitutional diffusion of oxygen atoms into the oxide layer. The effect of most reaction variables on the rate of oxygen consumption can be explained with this model. Introduction Recent investigations (1,2,3) have shown that certain sulphide ores can be readily leached by agitating the ore in the form of a pulp under pressure in the presence of oxygen. Since very little was known of the mechanism of this oxidation, a programme of investigation was inaugurated in 1949 in the laboratories of the Department of Mining and Metallurgy of the University of British Columbia. Financial support for the investigation was received from the National Research Council in the form of student grants and bursaries, from the Canadian Liquid Air Company, Limited, and from the Consolidated Mining and Smelting Company of Canada, Limited. The first objective was to devise a technique to study the primary oxidation reactions in aqueous solutions and to apply the technique to a detailed study of the oxidation of pyrite in caustic solutions.

Jan 1, 1952

By M. Clotilde Apua, A. F. Mulaba-Bafubiandi

"The efficiency of hydrochloric acid (HCl) leaching of gold from low grade gold-bearing material has been investigated in the presence of sodium hypochlorite (NaOCl) to produce in situ chlorine gas which is an oxidizing agent able to oxidize gold metal to its soluble forms. The effect of concentrations of HCl, NaOCl, and mixtures of HCl + NaOCl was sought. Iron and potassium present in the feed were leached and consumed all the HCl. Gold found as inclusion in pyrite was not exposed to the lixiviant. Therefore, leaching of gold from low grade gold-bearing material in aqueous chlorine solution is not an effective process for now.INTRODUCTIONHydrometallurgy of gold is commonly based on cyanide leaching solution. Due to the environmental concerns related to cyanidation and mercury processes, and inefficiency of cyanide gold leaching to dissolve refractory ores, sustainable alternative lixiviant systems, capable of generating gold (I) and gold (III) complexes must be studied. Amongst non-cyanide gold lixiviants there is the chloride/chlorine system (Hilson and Monhemius, 2006; Senanayake, 2004; Pilsniak and Trochimczuck, 2007; Wang et al., 2007; Reeves et al., 1999; Khodadad et al., 2008).In practice, the most oxidizing agents utilized for the leaching of gold as chloride, are chlorine (Cl2) or hypochlorite (HOCl) which are either generated in situ by suitable reaction or added in solution (Adamson, 1972). The dissolution of gold concentrate using hydrochloric acid, sodium chloride and sodium hypochlorite (Cl-/HOCl system) were studied (Puvada and Murthy, 2006). The effect of NaOCl and NaCl concentrations were also investigated. The leaching was performed under the following conditions; time: 4h, solid–liquid ratio = 1:4, at room temperature. It was found that the increase of the NaOCl concentration from 25 to 75 g/L did not have any meaningful effect on the recovery of gold which was about 30% (experimental conditions; S/L ratio = 1:4, NaCl concentration: 25 g/L, HCl concentration: 0.35 M). It was also found that from 25 g/L to 200 g/L NaCl, the recovery of gold rose from 30% to 40% (experimental conditions; S/L ratio: 1:4, NaOCl concentration: 25 g/L, HCl concentration: 0.35 M)."

Jan 1, 2012

By W. E. Newton

THE following notes are offered primarily to show that industrial minerals or their products have a much more important place in the metallurgical industry than is perhaps generally realized, and with the hope also that some statement by the metallurgical consumer of the relative merits of various materials for particular requirements or services will l;>e of value to the industrial mineral producer. These notes are not in any way presented as complete. Also, some of the statements made may be debatable. The grouping adopted is as follows: (1) Refractories; (2) Fluxes; (3) Construction materials; and ( 4) Miscellaneous applications. Fuels are not dealt with in the present paper. REFRACTORIES GENERAL: Refractories are materials which will withstand high temperatures with-out melting or becoming markedly soft or pasty. While their primary function is to withstand heat, they are usually called upon to resist one or more of the following destructive influences: abrasion, pressure, corrosion by slags or fluxes, and rapid changes in temperature. Refractory materials may be conveniently divided into three classes: (1) Acid refractories-consisting of silica, or containing silica as their chief constituent. They combine more or less readily with metallic oxides, forming silicates, and are hence termed 'acid'. The most important of these are quartz, quartzite, siliceous sand, tripoli, Dinas rock, and ganister. Most fire-clays, although generally considered neutral sub-stances, contain relatively small amounts of free silica and are, to that extent, acid. (2) Neutral refractories-the term is merely relative in most cases, since, at high temperature, many of the refractories that are classed as neutral will react chemically with a strong base, functioning as a weak acid; or, conversely, with a strong acid, functioning as a weak base. Chrome and graphite are the most nearly neutral of all the commonly used refractory materials.

Jan 1, 1936

By M. Pötsch, A. Kluckner, P. Söllner, W. Schubert

"The in situ block size is a key parameter in the geomechanical characterization of rock masses. It describes the fracturing of the rock mass and thus is a measure for the degradation of the rock mass strength. Several classification systems use the in situ block size. For instance, the Geological Strength Index (GSI) requires the “blockiness” and joint surface condition factor as key input parameters. The “blockiness” has recently been related to the in situ block volume (Cai et al., 2004). Due to the limited information about the internals of a rock mass, it is not possible to determine the in situ block size directly. Currently, the in situ block size is determined by calculations using oversimplified models, vague estimations or, due to the lack of relevant information, it is neglected. As remote measurement systems have become available for rock mass characterization, a more comprehensive record of discontinuities can take place. Measurements can be performed on exposed rock outcrops and in particular on tunnel faces and walls, delivering the location, orientation, spacing and persistence of discontinuities at an arbitrary number and locations. An estimation of the in situ block size at the same level of sophistication is still not available. This paper aims at examining the relationship between visible and measureable information at the rock surface, and the in situ block size. Three-dimensional block model simulations were performed using the block model engine of the distinct element code 3DEC. Initial investigations focussed on the minimally required observation area in order to obtain reliable block size distributions. Based on a representative volume element, a reference distribution of the block area at the observation area for a specific discontinuity system was determined. Subsequently, the size of the observation area was decreased stepwise and each new distribution was compared to the reference distribution. For all analyzed systems, it turned out that the mean block area must be smaller than 1% of the observation area to achieve a reliable block size distribution. Further simulations focussed on discontinuity systems with three non-persistent sets. The results were compared to the formula proposed by Cai et al. (2004). A transformation factor T was introduced which replaces the persistence terms in Cai et al.’s proposed formula. The factor describes the correlation between block volumes generated by persistent and corresponding non-persistent discontinuity sets. The simulations included the variation of the discontinuity set spacing, persistence, and orientation. The mean and additionally the 25%-, 50%- and 75%-quantiles of the block size distribution were analyzed. Examining all values for the transformation factor the distribution can be described by a power function with a negative exponent. The function depends on the persistence only. Finally, the results of random simulations were compared to the analytical formula using the transformation factor. The predicted mean and selected quantiles show a good agreement with the simulation results. It gives a comprehensive picture about the block size distribution in discontinuity systems with three non-persistent sets."

Jan 1, 2015

By K. Robertson, K. A. Scalise, K. C. Kocsis, M. B. Teixeira

"Many deep and highly mechanized underground metal mines require cooling. In many cases, appropriate working conditions might be fulfilled by ventilation alone, but some require the implementation of cooling systems. The most common cooling systems are bulk air cooling and localized cooling. These systems are effective, but they use considerable amounts of electricity. Ground source heat pumps (GSHP) can supplement existing cooling and heating systems, while geothermal systems can cool the mines in their entirety if there are significant sources of geothermal energy are present. A major advantage of geothermal and GSHP systems are their renewability, which reduces the carbon footprint of the mine.INTRODUCTIONThe western United States has abundant alternative energy sources including a high potential for geothermal energy. Geothermal utilization is a viable energy alternative that many areas throughout the world have access to because high geothermal potentials are located near areas of volcanic activity such as along plate boundaries, mid-oceanic ridges, rift valleys and hot spots (IRENA, 2017). There is significant potential to use geothermal energy for many applications. With constantly evolving and innovative technologies being developed, an increasing number of geothermal applications are becoming feasible. The western United States is an ideal candidate for alternative energy applications due to the geothermal availability and the emergence of modern technology. This paper investigates the incorporation of renewable methods and the alternative energy possibilities of Barrick Goldstrike, located in northern Eureka County, NV and Rio Tinto/BHP Billiton’s Resolution Copper mine located in Superior, AZ.RENEWABLE SYSTEMSGeothermal SystemsGeothermal temperatures are typically defined as either high or low temperature systems(Shengjun, Huaixian, & Tao, 2011). The high-temperature reservoirs (>220°C / 428°F) are feasible forlarge, commercial production of electricity with dry stream and flash stream systems (Shengjun, Huaixian, & Tao, 2011). Low temperature systems, below 220°C (428°F) (Shengjun, Huaixian, & Tao, 2011), aremuch more difficult to use for energy production. Low-temperature reservoir heat can be harnessedthrough the implementation of a binary cycle plant. The working fluid for a binary cycle plant is eitherorganic (Organic Rankine Cycle (ORC)) or an ammonia-water mixture (Kalina cycle). Organic fluids andammonia-water mixtures have low boiling points that allow for the recovery of heat from low-temperaturesources (Eymel Campos Rodriguez, et al., 2013). The efficiency of the binary cycle plant varies depending upon the fluid, thus the proper selection of the fluid is critical for maximum energy output"

Jan 1, 2019

By Terry A. Lee

The grade of mineral resource estimates underpin all major economic considerations of mining prospects. While there are reporting requirements to satisfy when stating a mineral resource estimate, an examination of NI 43-101 style reports suggests that authors believe that there are a number of ways of addressing these requirements. As a reader of these reports, some processes are helpful and others are not so in getting a real appreciation of how realistic is the mineral resource estimate. Critical to the quality of the mineral resource estimate is how realistic is the economic mineral concentration component. In many cases, this parameter is called grade. The industry experiences increased difficulty in achieving realistic grade estimates as the sample grade variability increases. The level of transparency in a mineral resource estimate is very much a function of the competence of the author. An objective presentation of the critical data, such as grade sampling variability can assist a reader in determining if the geology of the mineral concentration is adequately understood and how realistic is mineral resource grade estimate. This paper has considered 75 NI 43-101 style reports released in the past 2 years. The review demonstrates features that were helpful in determining how realistic the mineral resource grade estimate is. If there is insufficient transparency in a report, there is a high probability that the mineral resource grade estimate will not be realistic.

Apr 1, 2005

By W. G. Hubler

It has been within only the last two or three years that enough progress has been made in preferential flotation to warrant metallurgists in recommending the installation of commercial-sized plants for the treatment of copper-zinc-iron ores. Until the new processes had been worked out successfully, the treatment of this type of ore had proved a stumbling block in the path of metallurgical progress. Separation of lead-zinc ore is comparatively simple. A lead-zinc ore low in iron may be separated and concentrated by gravity con-centration, provided it is not necessary to grind too fine. Owing to the specific gravity of chalcopyrite and sphalerite being so nearly the same, however, their separation by gravity concentration is out of the question. Complex lead-zinc-iron ores in which the several minerals are intimately associated, requiring fine grinding to free them, have been successfully treated by flotation for the past fifteen years. Galena is easily floated, and its flotation, unlike that of chal¬copyrite, is not affected by the reagents used to inhibit the flotation of sphalerite and iron sulphides. When an attempt was made to use the methods of lead-zinc se-paration on copper-zinc ores, it was found that the depressant re-agents added to inhibit the flotation of the iron and zinc minerals would, under certain conditions, depress a large part of the copper. It was also recognized that, in the grinding of copper-zinc ore, soluble salts were generated which were detrimental to flotation unless properly controlled. The main part of this paper will be a discussion of solutions in the grinding circuit in relation to the pro¬duction of soluble salts and their effect on flotation.

Jan 1, 1931

By S. L. Zekovic

This paper analysis the medium and long-term perspectives, framework and considered possibilities of sustainable development of RTB "Bor" (Copper mines in East Serbia) after consolidation in the period of transition. The copper mine was opened in 1903. and today is the best quality copper producer on Balcan. This paper are elaborates the problems of privatization, debt, investment, growth of copper production from own mines (and imported raw), opening of new mines, economical efficiency of production, markets, environmental problems and impacts of the recent industry consolidation. The RTB "Bor" is a serious hot spot in Serbia. Unsustainable trends and processes are identified, as follows: open-pit waste dumps, flotation tailings, mining and processing waste waters, air pollution; no efficiency (excessive) using nonrenewal resource in the copper production; inefficiency in the use of energy, water and other inputs in copper complex; transboundary character of emissions of dust; environmental degradation and quality of wide area and ecologically highly risk, etc. Analysing some trends and planning-developmental perspectives and development strategies of company, it might be assumed that in the forth coming period, in parts of the Serbia, the borders areas of Bulgaria and Romania, there is an anticipated increase of ecological risk.

Jan 1, 2007

By D. Ibarra, J. Jacob, A. G. Guezennec, P. d’Hugues, A. Archane

The lack of adequate gas mass transfer is a rate limiting step in many bacterial leaching processes. Oxygen often becomes a limiting factor because of its low solubility compared to the high demand induced by sulfide oxidation. One way of increasing the solubility of oxygen in water or in media solution is by increasing the driving force, i.e. raising the oxygen partial pressure in the gas stream supplied to the leach pulp. The use of oxygen is a well-known practice in high-temperature bioleaching reactors (above 70°C) whereas air is usually preferred in medium and low-temperature operations in order to avoid too high dissolved oxygen concentrations which could impact negatively the bacterial activity. The purpose of this study was to investigate the use of oxygen-enriched gas in bioleaching reactors at 40°C in order to improve the gas transfer in the system when operating at high solid load (20% and more). Bioleaching experiments were performed on a sulfide-rich tailing waste (pyrite 60%, copper 0.8%, cobalt 0.06 %, gold 1 g/t) using the “BRGM-KCC” bacterial consortia. The reactor used for the tests was designed on the basis of a new bioleaching reactor concept developed by Air Liquide, Milton Roy Mixing and the BRGM which uses floating agitators to inject gases and to mix and to suspend solids in the bioleaching solution. Two types of tests were carried out: with air injection and with oxygen enriched gas mix injection. The aim of this work was to confirm the capacity of bacteria to grow and to dissolve pyrite in this type of bioreactors in oxygenrich atmosphere, and to compare sulfides dissolution rates during both types of bioleaching tests. The results obtained show that the use of oxygen enriched gas mix does not decrease bioleaching performances compared to air injection. High metal extraction yields were achieved (above 80%). No deleterious effect due to oxygen use was observed on the bacteria despite the high level of dissolved oxygen reached in oxygen tests (up to 14 mg.L-1).

Jan 1, 2016