Search Documents

By J. M. Whatley

"IntroductionIN UNDERGROUND mining operations, the mine hoist has become one of the most important and one of the most expensive single pieces of equipment. As the means of transporting men and materials to the face, broken ore to the mill, and waste to the dump, it is often the very lifeline of a mine and must operate with dependability and efficiency or the whole operation will suffer. The mine hoist has become synonymous with safety. In few other types of mechanical equipment do so many men so frequently and completely place their lives. In Canada, more has probably been done to assure safe hoisting than in most other countries, but, unfortunately, this has resulted, in many cases, in the mines having to pay a high price for equipment. Hoist manufacturers have carried out much research in recent years in the endeavour to keep down these costs and at the same time maintain or improve the efficiency and safety of their products. Broadly classified, the bases for design research are dependability, efficiency, safety, and first cost.Probably the greatest single factor influencing the design of mine hoists was the introduction of electric motor drives. It was not until about 1905 that an effective start was made in the development of electric mine hoists, and then only with machines of small size. From that time on, however, progress was rapid, as may be gauged from the fact that by 1910 one large group of mines in Johannesburg had in use, or on order, fifty-four three-phase hoists and four Ward-Leonard. type hoists."

Jan 1, 1953

By Robert M. Vadas

Special considerations are described as they apply to the design of ring gears for high-power grinding mills. AGMA requirements, the importance of the supporting structure, material selection and related field experience are discussed, with special emphasis on available and developing manufacturing technologies.

Jan 1, 1978

By Lauri Gregg

The implementation of Energy Management within the global mining industry has advanced significantly during the past 20 years. Consequently, the industry?s knowledge of energy efficiency improvement opportunities, more energy efficient technologies, renewable energy technologies, energy procurement practices, and most importantly, practical approaches for integrating the energy management best practices into business processes and operational procedures has improved greatly. Based on 25 years of experience leading the management of energy in mining operations and the Canadian mining community, the author discusses the key building blocks in the evolution toward becoming an energy efficient mining facility. Sustainable energy management depends on the internalization of the behaviors related to the effective energy use by a mining organization. The paper outlines the typical business drivers that stimulate top management commitment to allocate the resources necessary for this to happen. It also explores the barriers that mining companies must overcome to maintain the commitment. Additionally, it will advocate the need for the application of the principles of organizational change management as part of the energy management implementation process. The question regarding how energy management can be made to happen in a way that is practical for an established organization is answered by providing the details of the framework for energy management, the methodology for controlling energy use, and the roadmap for integrating energy as a key business parameter and production process input variable. An Energy Management System standard developed within the Mining Association of Canada?s ( MAC ) Towards Sustainable Mining ( TSM ) initiative has played an important role in increasing the capacity of the Canadian mining industry to manage energy. The impact of the application the MAC TSM Energy/GHG Management Protocol by Canadian mining companies will be discussed. In June of 2011, the international ISO 50001 Energy Management Systems standard was finalized and published for use. The structure of ISO 50001 will be outlined along with its applicability to the mining industry. Opportunities for practically improving mining energy performance along with the most appropriate current new technologies will be identified. A brief discussion of case studies will be included that demonstrates the successful implementation of Energy Conservation Measures ( EAC?s ) and economic benefits. In conclusion, thoughts on important areas of research and development related to increasing mining energy efficiency will be provided.

Aug 1, 2013

By A. L. Irwin

THE problem of compensation for labour is probably the oldest and most complicated one in history. The wage that a man receives is possibly the most concrete thing he gets out of his job and, rightly or wrongly, is generally considered by him to be the most important item in connection with his daily work. How today workers in an equitable way has been the study of industrialists for many years, and a great number of ideas have been tried out in an effort to arrive at a reasonable solution of the question. The idea of establishing a measuring stick for various types of work has intrigued industrial management for a long time and, after considerable study, the principle of Job Evaluation has taken form unti1, at the present time, it is becoming increasingly useful to industry at large. Job evaluation is a plan which is used to determine the relative worth of occupations by means of arbitrary measuring scales. These scales are developed for individual industries and are generally 'tailor made' for each particular case. There are as yet no absolute methods of measuring the work done by human beings and, as a result, one has to depend on comparative values to arrive at conclusions. However, job evaluation has provided us with a basis of negotiation for wage rates which is more satisfactory than mere guess work or persona! opinion. It supplies a common ground for discussion which is understandable by all taking part and ensures that thinking with regard to wage setting is carried out along standard lines.

Jan 1, 1943

By D. Krippner, C. Nexhip, D. George-Kennedy, P. Gebski, R. Kaur, W. L. Ying

ABSTRACT Water-Cooled Tapblocks Are Essential Components Of Modern Smelting Furnaces. Uninterrupted Operation Of A Tapblock Is Critical For The Optimal Operation Of A Furnace. This Critical Function, Together With Exposure To Extreme Conditions, Drives The Need For An Efficient And Reliable Means For Tapblock Monitoring. The Main Objective Of Tapblock Monitoring Is To Help Optimize The Life Of The Tapblocks By Better Scheduling Inner Refractory Relining And Protecting Operators By Preventing Sudden Deterioration Of The Tapblock. A Taphole Acoustic Monitoring (TAM) System Was Developed To Meet The Above Requirements. This Paper Describes The Principles Of The TAM System And Selected Case Studies.

Jan 1, 2013

By G. A. Bezuidenhout, J. Davis, S. M. Bradshaw, J. P. T. Kapusta, D. K. Chibwe

"This research work forms part of an assessment to complement the feasibility of implementing high pressure sonic injection into relatively small (2.25 m I.D by 3.66 m I.L) Peirce-Smith converters (PSC) used at Lonmin Plc. Work has been carried out to characterize the fluid dynamics of three-phase (air, matte and slag) fluid flow in these converters using Computational Fluid Dynamics (CFD) simulations. The investigation has been done to study the flow pattern of the three phase system at high air pressure injection achieving sonic velocity at the tuyere exit into the converter. The 2-D and 3-D simulations of the three phase system were carried out using the volume of fluid (VOF) and realizable k -e turbulence models to account for the multiphase and turbulence nature of the flow, respectively. These models were implemented using the commercial CFD numerical code FLUENT. A detailed study of the flow pattern has been presented in the form of contour plots and the results obtained are useful for understanding plume extension and velocity distribution, shear wall stress distribution, and phase distribution characteristics in the system. The results provide a basis for further development of sonic injection technology into relatively small industrial Peirce-Smith converters with the ultimate objective of achieving lower energy consumption, improved process efficiency and increased throughput of the converting process. INTRODUCTIONPeirce-Smith converters (PSC) have been used in copper (Cu) and nickel (Ni) making smelters for more than a century for the purpose of removing iron (Fe) and sulphur (S) chemically associated with copper-nickel mattes through exothermic oxidation reactions. This process is commonly referred to as conversion. In principle, conversion is a submerged injection process, where typically air (or oxygen enriched air), at subsonic velocity (typically < 150 m/s), is laterally blown into liquid matte (Cu-Ni-Fe-S system). Oxygen preferentially reacts with Fe and S to produce iron oxide (FeO), which is slagged off, and sulphur dioxide (SO2), which reports to the process off gas."

Jan 1, 2012

By B. Chambers, M. Yunovich

"Corrosion monitoring is commonly used in a variety of industries as a means of effective corrosion control programs to extend the life of the asset and ensure safe operation of the facilities. The majority of the monitoring tools have limitations and tradeoffs – e.g., sacrificing the longevity of the probe for higher measurement resolution. Linear polarization resistance (LPR) probes have the advantage of providing the operator with accurate, real-time corrosion rate data; however, the probes can only be deployed in conditions where the measured environment possesses certain minimal conductivity. In many instances, utilization of LPR probes in conditions with intermittent wetting (for example, conditions where the temperature fluctuates above and below the dew point) presents a challenge. To address this limitation, a special-design cooled corrosion probe has been developed, commercialized and integrated into the distributed control system in the plants. In addition to high-accuracy measurement of corrosion rates, the probe allows for monitoring of pitting corrosion. The most innovative feature of the probe is the cooling circuit, which brings the temperature of the sensors below the dew point, forcing precipitation of moisture and thus permitting corrosion measurements. Additionally, the probe was found to be well-suited for monitoring corrosion in crude distillation unit (CDU) overhead space, where condensation of hydrochloric acid may take place at relatively high temperatures, which would require relatively moderate amount of cooling to be imparted to the probe sensors. This paper presents laboratory-based data from a test simulating CDU refinery environment. A case study is presented to demonstrate how the cooling probe can be effectively used in the plants for corrosion monitoring.INTRODUCTIONConventional corrosion-monitoring techniques such as weight-loss coupons to assess corrosion damage are commonly used in plants1. However, the use of coupons is not only labor-intensive, but also does not deliver real-time corrosion data, thus effectively serving as a “backwards-looking” monitoring tool. Linear polarization resistance (LPR) probes have the advantage of providing the operator with accurate, real-time corrosion rate data; however, the probes can only be deployed in conditions where the measured environment possesses certain minimal conductivity."

Jan 1, 2012

By Michael Loken, April Montera

"The process of blending consistent and predictable feed for the roasters is critical to optimizing product quality and controlling production costs. To assist in this process, Online PGNAA Slurry Analyzers have been installed and evaluated at a Sudbury Ontario smelter. They are used to measure 100% of the full process stream to obtain elemental composition data in real time. This paper explains the application details at Sudbury and the benefits achieved from their Full Stream, Elemental Slurry Analyzers.INTRODUCTIONSudbury Integrated Nickel Operations (Sudbury INO), a Glencore Company consists of two underground nickel/copper mines in Sudbury, Nickel Rim South and, Fraser, along with the Strathcona mill and the Sudbury smelter. The facilities are spread throughout the 60 kilometer-long, oval-shaped geological formation known as the Sudbury Basin (Figure 1). The company has been mining nickel-copper ores in the Sudbury area since 1929. Nickel and copper are the primary focus of operations at Nickel Rim South and Fraser. Other base metals such as cobalt and precious metals are also produced."

Jan 1, 2016

By M. S. Fotheringham

Recognition of the Growing Importance of Iron and Steel Few Canadians have yet become aware that Canada&apos;s vast iron ore resources, the greater part of which is only now beginning to be developed, will inevitably have a profound effect on the entire Canadian economy, benefitting in some measure the lives of all Canadians. The great iron mining developments of Ontario, Newfoundland, Quebec, and Labrador are destined to make Canada one of the world&apos;s major producers and exporters of this material, on which our industrial civilization is?based. These developments will create new employment, new communities, new transportation facilities, and new investment opportunities. Iron ore is the foundation and the keystone of modern mechanized civilization. The most prosperous nations of the world are the highest per capita consumers of iron and steel, and in these countries the per capita consumption is increasing steadily despite the advent of light metals, plastics, and other competitive materials. Three-quarters of the human race have too little steel -and consequently too little mechanization -to provide for themselves the necessities and comforts of civilized living. Progressively they will demand, and acquire, the machines, the transportation and communication facilities now lacking, and they will win them by making greater use of the world&apos;s iron resources. It is the good fortune of this generation that Canada&apos;s &apos;iron age&apos; is just getting well under way.

Jan 1, 1951

By G E. Craig, W. M. Williams

A simple, easily constructed apparatus suitable for the zone refining of iron and other reactive materials is described. After eight passes at one inch per hour, the iron produced showed a marked drop in hardness to 49 Brinell. In addition, an arbitrarily -defined recrystallization temperature was lowered by about 35°C and the rate of grain growth greatly increased. CERTAIN materials, of which iron is one, are so reactive that they cannot be zone refined in any known container without becoming contaminated. For such substances, the floating zone method ( 1) may be used. In this method, the specimen is supported vertically in an inert atmosphere and the molten zone supports itself by its own sur-face tension. The method was first applied to silicon (2) and has since been used for other reactive metals such as zirconium and titanium. Smith and Rutherford (3) have previously reported on the floating zone refining of iron; the efficiency of the method for reducing the car-bon content was demonstrated on

Jan 1, 1962

By T. J. Wells

THE blast furnace is the base of the steel industry, since there is no commercially practical way of converting iron ore directly into steel. In three hundred years, the blast furnace has developed from a small unit using charcoal as fuel and producing about one ton of iron in twenty-four hours to a furnace making upwards of 1,500 tons a day. The principle of the blast furnace is briefly this: A descending column of stock, consisting of ore, fuel, and flux, is met by an ascending stream of gases, consisting in part of gases formed by the combustion of the fuel and in part of pre-heated air which is blown into the lower part of the furnace. The flux combines with the impurities in the ore and the ash in the fuel to form slag, which is drawn off as liquid.

Jan 1, 1943

By A. Pearson, F. A. Auld, S. O. Colbeck

"""The theory of buckling of shafts and Steel tunnel-linings"" was published by E. Amstutz in 1970 and commented on by S. Jacobsen in 1974. The authors have revised and enhanced Amstutz’s work to address Jacobsen's comments on its limitations and to extend its validity over a wider range of pipe/shaft geometries, including those commonly found in deep mine access shafts. The author has looked at Amstutz’s assessment of strengthening with flexible shear anchorages and adapted the theory of non-linear shear deformation response of bolts to develop a method of assessing increased buckling capacity utilising the full plastic shear capacity of studs. INTRODUCTION “Amstutz Buckling” refers to the buckling of pipe embedded in concrete under external uniform pressure. In terms of a mining environment, this relates directly to the design of a watertight shaft. This load case will commonly occur where a main shaft is cast against a geostatically stable primary liner and the only load applied to the final shaft is that of a uniform ground water load. Ernst Amstutz wrote his first paper on buckling of pressure-shaft steel linings in 1950 and subsequently improved his theory (Amstutz, 1970), which was then widely adopted for use within the industry. Years later, an alternative approach (Jacobsen, 1974) was proposed. Within his paper Jacobsen critiques Amstutz work, identifying some mathematical inconsistencies and highlighting limitations of the theory imposed by approximations adopted by Amstutz. Despite these limitations Amstutz work has still been used as the favoured design theory for use in the mining industry. In reviewing this body of work the author realised that with the advent of readily available computing software it was possible to adopt an iterative approach using Amstutz approximate formulae to find a solution to the original precise formulae, thus eliminating the limitations highlighted by Jacobsen The shear deformation to load characteristics of bolts has long been established (Crawford & Kulak 1968) and used for the plastic design of bolted connections in shear. This relationship is directly transferable to the design of shear studs, typical properties are well known, and actual values easily established in simple lab tests. The author has taken this relationship and modified Amstutz theory (Amstutz, 1970) for shear anchored strengthened liner buckling, to give a more efficient solution, using readily available material properties."

Jan 1, 2019

By T. Johnson, D. Kelley, J. Graham

"Hydrometallurgical processes can be exceptionally corrosive. Conditions associated with metal extraction and refining require materials of construction that can withstand process acids and acid chlorides at temperatures up to 90°C (194°F). Process vessels, piping, scrubbers and ducting can be rapidly compromised in these aggressive environments if not designed with care. Design engineers are challenged to find materials that can stand up to hydrometallurgical processes especially for copper, zinc, nickel, cobalt and uranium. This paper will evaluate material solutions to determine which provides attractive economics for initial procurement as well as high durability for reasonable life cycle costs.INTRODUCTIONMining activity in a number of metal ores has been running quite high over the last few years. In particular, those metals that employ acid functional extraction processes such as copper, nickel cobalt and uranium have been particularly active.The world’s largest nickel mine – the massive $4.76 billion Ambatovy nickel mine on the African island nation of Madagascar is nearing completion. When it reaches its full production capacity in 2013, the mine will produce 60,000 MT/yr of nickel and 5600 MT/yr of cobalt. Coming on the heels of the Ambatovy project is the Long Harbour Processing Plant in Newfoundland, Canada which will process the ore from Vale’s Voisey Bay mine in Labrador. Voisey’s Bay is expected to generate more than 50,000 MT/yr of nickel ore when it starts up in 2013. Next up will be the Boleo project in Mexico on the Baja peninsula. When commissioned in 2013, the $858 Million Boleo project is expected to produce 60,000 MT/yr copper, 3100 MT/yr cobalt, 36,000 MT/yr zinc and 100,000 – 250,000 MT/yr manganese carbonate.High nickel alloys and rubber lined steel have been used for decades to design corrosion resistant equipment for mineral processing environments. These materials demonstrate reasonable resistance to corrosion for most environments. Unfortunately, higher nickel alloys are quite expensive. Rubber lined steel is a bit more affordable but requires continuing service over time which ultimately drives up its cost as well. FRP (Fiberglass Reinforced Plastic) has also been used extensively in mineral processing for tanks, piping and ducting employed in aggressive environments. Today, more and more design engineers and material specifiers are calling for FRP composites for both new and replacement equipment used in the refining and processing of a variety of metal ores."

Jan 1, 2012

By S. P. Cashin, D. Kashuba, W. Esplin

Barrick has had 6 autoclaves in operation at the Goldstrike Mine, North of Carlin Nevada, since 1993. The 6 autoclaves operate in parallel, processing slurry of gold ore. The gold in the ore is predominantly associated with, and encapsulated by, sulphide minerals. It is necessary to oxidize at least 90% of the sulphide mineral before the gold can be concentrated using a cyanide/carbon-in-leach (CIL) circuit. Sulphide oxidation chemical reactions occurring in the autoclaves are exothermic; however, the sulphide content in the ore is not high enough to operate the autoclaves in an auto-thermal mode. Heat from steam is added to the first 2 of 5 autoclave compartments to initiate the sulphide oxidation reactions. The steam used to heat the autoclaves is supplied by three boilers, which are fuelled with propane gas. The completion of a few operations and maintenance projects in the last 2 years has resulted in a 50% reduction in propane energy requirements. The autoclave operating temperatures were minimized. Excess oxygen addition was held as low as possible. The material of construction for the compartment walls inside the autoclaves was changed from brick to Titanium metal. And, the speed of the autoclave slurry agitators was increased. All of these activities had an impact on the propane energy requirements of the autoclaves. Presented below is a description of the autoclave systems, and a discussion of how the energy needs were reduced, resulting in significant operating cost savings.

Jan 1, 2004

By L. O. Thomas

THE Alaska Highway, in its course through British Columbia, traverses parts of two great physiographic divisions of Canada which are also distinctive geologically-the Cordillera in the western section and the Interior Plains in the eastern. The Cordilleran region in the portion of the Province with which this paper deals can be divided into four major northwest systems, known respectively from west to east as Coastal, Plateau, Cassiar-Omineca, and Rocky Mountains. The Coastal system consists solely of the Coast range except in the extreme northwest, where a part of the St. Elias range is included. The Coast range, characterized by mountains of great ruggedness,. is made up of an igneous complex of granitic rocks intruded chiefly as a great batholith. In places, spurs of these rocks extend into the Plateau heft, a partly mountainous tract largely occupied by quartzites, quartzose mica schists and their gneissic phases, and crystalline limestone with interbands and broad areas of chlorite, _hornblende, and sericite schists and bodies of intrusive granite gneiss-an assemblage of rocks known as the Yukon group. The Cassiar-Omineca system marks the divide between the Pacific and Arctic drainages. Its eastern boundary is well defined in the south by the Rocky Mountain Trench (see p. 229). The rocks of the system are, miainly, highly altered Palaeozoic sediments, but there are also Precambrian and Mesozoic rocks, the latter largely volcanic. The core of the system is granitic and there is evidence (see p. 221) to support the belief that it is of such a length as to constitute a batholith comparable to that of the Coastal system.

Jan 1, 1944

By W G. Forbes

SOME 20 years ago, upon finishing second year at the University of Manitoba, I was faced with the choice of whether I wanted to be a geologist or a chemist. Accordingly, I sought out Professor Brownell, Head of the Department of Geology, to ask him what a geologist did. His reply contained the statement that following graduation one went out into the field in northern Canada for 5 to 15 years to reduce to practice what had been learned at university. To a young man, very socially conscious, even one year, let alone 5 to 10, in a small mining community sounded like being banished to a monastery in the Himalayas and thus I turned to chemistry. Moving to the present, last month I asked a geologist, and then a mining engineer, what does the fresh graduate in their field do these days? The reply was: usually serve an apprenticeship for an indeterminate period either underground or in the field learning the job.

Jan 1, 1965

By Patrick Fantin

Mining ? The Past Safety Not a priority; Health Not a priority; Energy Manual Labour; Horsepower? Literally. Financially Robust For the Owner?s; Mining ? The Future Safety Zero Harm Health Understanding and elimination of Industrial Disease Energy Efficient use of energy through technology. Full value of renewable energy. Financially Robust Continually build shareholder value through optimum CAPEX/OPEX.

May 1, 2013

By G. A. Bezuidenhout, J. Davis, S. Lefume, J. P. T. Kapusta, D. K. Chibwe

"Although the centennial of the Peirce-Smith (PS) converting process has recently been celebrated, the technology has essentially not changed much since its inception. PS converting is used extensively in the Cu, Ni and PGM industry to remove iron and sulphur from a molten matte phase. A typical PS converting process would use low pressure air supplied by a blower to bubble air through the molten bath. This bubbling injection regime is inherently inefficient from a process and energy consideration. In the late 70’s and early 80’s, Brimacombe and co-workers demonstrated at both laboratory and plant scales that sonic injection (jetting regime) into copper or nickel converters could reduce or eliminate the above hindrances characteristic of PS converting. Since then, in spite of these successes, very little industrial applications have made headway in the converting process of non-ferrous metal mattes on a commercial scale. As part of its operational improvement and energy reduction program (process efficiency), Lonmin Platinum decided to conduct a full scale industrial evaluation of sonic injection using air only to establish if punchless, high efficiency sonic injection was feasible in its small 3.05 × 4.57 m converters (10’ × 15’). A plant trial was run for four weeks in one of its three converters. This paper discusses the plant demonstration with a focus on the experience acquired by Lonmin together with the key learnings from the trials. Reference will also be made to the commercial aspects of a full scale implementation of sonic injection in all three converters in the smelter. INTRODUCTION AND OBJECTIVESAlthough the centennial of the Peirce-Smith (PS) converting process has recently been celebrated (Peirce and Smith, 1909; Southwick, 2009), the technology has essentially not changed much since its inception. PS converting is used extensively in the Cu, Ni and PGM industry to remove iron and sulphur from a molten matte phase. A typical PS converting process would use low pressure air supplied by a blower to bubble air through the molten bath. This bubbling injection regime is inherently inefficient from a process and energy consideration."

Jan 1, 2012

By Maurice Séguin

The primary aim of all ground geophysical work has been, of course, to locate orebodies. As with any geo-physical method, its success depends on a proper mastering of the types of surveys and equipment used and their application to the physical properties associated with the orebodies. The Schefferville deposits are iron ores subjected to enrichment by the process of leaching. Although some ore types are porous and low in demiity, most of the ore zones have had a net increase in density brought about by enrichment. In the course of their formation, the magnetic characteristics of the rocks have usually changed, as much of the magnetite was altered to relatively non-magnetic iron oxides and hydrous iron oxides. Ali drift-covered areas underlain with iron-formation are potential ore-producing areas. From these first two physical proper-ties and a determination of the thickness of the over-burden, a combined gravity-magnetic-seismic and/or resistivity survey allows for the detection and sorting out of iron-formation and potential ore zones from the country rocks. If the iron-formation possessed relatively uniform physical and chemical properties, the problem of locating areas underlain with ore, using geophysical methods, would be greatly simplified. Unfortunately, the iron-formation is a complex assemblage of rock types, each having different physical and chemical characteristics. In spite of this, qualitative and semi-quantitative correlation between the results of the surveys and the geology and structure of the area could be established. In addition, a semi-quantitative to quantitative correlation of the values of the residual gravity anomalies with the specific gravity, the iron content, the porosity factor, the dimensions of the under-lying orebodies and the values of the ground magnetic intensity above a reference lithologie unit, with the per cent weight Fe304 recovery and the susceptibility, led to the discovery of a direct-shipping iron ore deposit in the Schefferville mining district of Canada.

Jan 1, 1968

By Y. Thibault, L. Morin, R. Cameron, D. Gould

"There are an estimated 50 to 100 million dry metric tonnes of low-grade nickeliferous pyrrhotite tailings in the Sudbury area alone, with an average nickel grade ~0.8% (plus cobalt). Pyrrhotite is a highly reactive sulphide mineral that has the potential to generate acidity; consequently, it is stored in large tailings ponds that require perpetual treatment to avoid the production of acidic drainage. Re-processing this material using bioleaching technologies has the potential to recover valuable metals, while reducing the toxicity, reactivity, and acid generating potential of the remaining residues. CanmetMINING is currently developing a stirred-tank bioleaching process to recovery nickel and cobalt from pyrrhotite-rich tailings. Stirred-tank experiments have been conducted with one tailings sample over a range of pH and temperature conditions, resulting in 80 to 90% and 70 to 80% leaching of nickel and cobalt respectively in 10 days.INTRODUCTION Sulphide tailings may represent a significant financial liability for mining companies as these wastes may produce acidic drainage under some disposal conditions. As a result, the companies must post financial bonds large enough to ensure there are sufficient funds for perpetual management of these wastes. At the same time, there are billions of dollars in metals incorporated into these mining wastes waiting to become valorized. Many sulphide tailings are amendable to bacterial oxidation for metal extraction. Re-processing of tailings using bacterial leaching has the potential to recover valuable metals from waste; and reduce the toxicity, the reactivity, and the acid generating potential of the remaining residue. By reprocessing these wastes there is an opportunity to significantly reduce liabilities and financial assurance bonds, while recovering metal values. There are an estimated 50 to 100 million dry metric tonnes of low-grade nickeliferous pyrrhotite-rich tailings in the Sudbury area alone with an average nickel grade ~0.8% (Peek et al., 2011) plus cobalt and copper. Pyrrhotite is separated from pentlandite concentrates by magnetic separation and flotation. It is already finely ground and has often been segregated from other tailings material, making „mining? relatively inexpensive. This represents roughly (> $100/ton) in contained value, with negligible mining costs. This paper reports on the development of a stirred-tank bioleaching process for recovering nickel and cobalt from pyrrhoitite-rich tailings, which is currently underway at Canmet MINING."

Jan 1, 2017