Search Documents

By Robert Voisey, Robert J. Spencer

"LynnGold's MacLellan Mine is located about 8 km south east of Lynn Lake immediately to the east of the Keewatin River (Fig. I). The property is accessible by an all-weather road, leading north from the provincial highway 391, which links with the Town of Leaf Rapids and the City of Thompson to the south.The ore body, as outlined in the original feasibility study, is expected to produce in excess of 9.3 x IQ6 gm of gold and silver over the next 5 years. However, the deposit is open to depth and exploration is continuing on and around the main zone and the many satellite deposits.The start of construction of the MacLellan Mine and mill was scheduled to phase in with the closure of the Fox copper-zinc mine located 48 km west of Lynn Lake. The majority of the employees from the Fox Operation were either employed at the MacLellan Mine or relocated to Sherrin's Ruttan Operation.GeologyThe MacLellan gold ore deposit is located on the northern section of the Lynn Lake Greenstone Belt known as the Rainbow Trend. This Trend is a 40 km gold bearing rock sequence extending both east and west from the MacLellan Mine. The southern section of these two east-west trending structures is known as the Johnson Shear, this is also gold bearing."

Jan 1, 1990

By Fred A. Curtis, Kathryn E. Moore

"The past 14 years have brought an increased awareness of environmental problems. Surface mining for mineral aggregates has been one o f the issues which ha s sparked fierce controversy and debate. Various level s of government, industry, and the public have engaged in an unending battle for adequate planning, regulation, and rehabilitation of pits and quarries. Agreement has seldom been reached and, as a result, few standards, guidelines or policies have been established, or enforced province-wide.Surface mining ca uses a number of environmental problems including noise, dust, water table disturbances, aesthetic degradation, increased traffic, and health and safety hazards. These problems are particularly serious in urbanizing area s, where people are exposed to the mining operations. Associated with the operational phase of surface mining are the issues generated by the multiplicity of abandoned pits and quarries which dot the countryside. These large, gaping, often dangerous waterfilled holes are a blight o n the landscape, and represent a misuse of land.The environmental problems connected with pit s and quarries are compounded by the fact that accessible reserves of mineral aggregates are being lost through the process o f urbanization. In addition, restrictive zoning at the municipal level is restricting access to even more aggregate rich land. This results in the paradox that the very urbanizing process which creates the demand for aggregates is rapidly reducing the available supply. These problems have stimulated the Ontario Ministry of Natural Resources to call for a province-wide program of inventory, assessment and planning for the protection o f high-quality reserves in Official Plans. These proposals have met with strong opposition from municipal leaders, who are jealously protecting their autonomy.Environmental management education is a prerequisite for all parties involved in pit and quarry planning, regulation or rehabilitation. To this end the following bibliography of selected articles with attention given to the Ontario experience, should provide helpful information on these topics."

Jan 1, 1985

By M. Oliazadeh, A. Vazirizadeh

"The inclusion of small amounts of silicon, phosphorus and sulphur in iron ores or concentrates can have a profound effect on the steel making process and thus on the final iron and steel products. In nature however, it is inevitable that iron deposits contain unwanted elements. Each element has its own distinct effect on the final steel product. The effect of high silicon is the formation of gray iron. Phosphorus mainly increases hardness and strength, lowers solidus temperature and increases fluidity and cold shortness. Finally sulphur contamination causes cracks in the iron texture when smelting and forms white iron when casting. Overall, the acceptable level of phosphorus, sulphur and silica in the iron concentrate should be less than 0.04%, 0.15 % and 1.5 % respectively.Scarcity of high grade iron ores necessitates using lower grade ores with higher amounts of impurities. The purpose of iron concentrators is to increase iron grades to an appropriate level suitable for steel making as well as removing impurities. Although many impurities can be traced in the ore, the most predominant impurities are limited to one or two elements. In this paper the beneficiation methods for removing SiO2, P and S are presented, including flotation, and the parameters that need to be considered in the design of beneficiation plants are discussed. Finally industrial cases are discussed along with their metallurgical performance.INTRODUCTIONIn metal sector, value of iron ores and concentrates is determined by iron percentage as well ascontent of:• Useful elements (Mn, Ni, Cr, V, Ti): natural alloying elements in steel• Deleterious impurities (S, P, As, Zn, Pb, K, Na): impair metal properties or complicate operational process in blast furnace• Fluxing components (Si, Ca, Mg,, Al)Sulphur and copper result in red-short, phosphorus is the cause of cold brittleness and arsenic and copper decrease welding characteristics. Sulphur should not exceed 0.15 in commercial ore. Acceptable sulphur content in ores and concentrates for producing sinter and pellets is 0.6%max, as sintering and heat hardening of pellets remove sulphur 60-90%. Phosphorous content in ores, sinter and pellets is limited to 0.07%-0.15%. 0.00.1% As max, 0.1-0.2% Zn max and up to 0.2% Cu are allowed in iron-ore part of the blast furnace burden for the production of standard conversion pig iron. Slag-forming components are divided into basic oxides (Ca, Mg) and acidic (Si, Al). Higher ratios of basic to acidic oxides are preferred since this reduces raw fluxing material."

Jan 1, 2016

By B. J. Morash

"The six mineable coal seams at Quintette Coal Limited (QCL) vary in thickness from 0.75 m to 9.5 m and include waste partings varying from 0.2 m to 4 m thick. They are highly faulted and folded in some areas and dip angles range from horizontal to 90 degrees. Due to this variation in thickness and orientation of the seams, several different mining methods are used to economically recover the coal. The key to QCL's success depends on the timely collection of detailed geology data and on mine planning which allows selection of the best method of mining to achieve maximum coal recovery with minimum dilution and cost. This paper will describe the various methods of mining employed and the criteria used to select them. IntroductionThe unique challenge in mining at Quintette Coal Limited (QCL) is to extract large quantities of coal and waste, from a complex orebody, with constricted areas for mining and waste disposal. This challenge dictates the mining of as many as four 10 m benches per year, through complicated coal structures, from three separate open pits with a total of 19coal seams. This total is made up of 5 seams at Mesa, 8 seams at Wolverine and 6 seams at Shikano (Fig. 1).Computer-aided mine planning and scheduling is carried out on a routine basis to ensure the prudent selection of methods of mining, to produce plans which ensure delivery of appropriately blended raw coals to the plant, and to coordinate disposal of large quantities of waste.Several methods of mining are applied simultaneously, and as a result coal and waste are released at different rates from twelve to fifteen mining faces. In order to ensure uninterrupted flow of material from excavators and to utilize the truck fleet effectively, a computerized dispatch system is employed.GeologyGenerally, geological conditions can be related to structural (faults and dip angle) and/or stratigraphic (coal seam and interseam waste thickness) sources"

Jan 1, 1988

By P. Cielo

"Nondestructive inspection is an important quality control tool in the material processing industry. Being nondestructive, such a control may be applied to the whole production, as long as the available techniques are fast and easily automated. Ideally, nondestructive testing (NDT) methods should operate in a noncontact configuration in order to be deployable on-line with minimum perturbation of the production process.After a short introduction to the most common NDT techniques, with particular emphasis on ultrasonic, radiographic and electromagnetic methods, a few new approaches which are under development at the Industrial Materials Research Institute, (Boucherville, Quebec), are reviewed. Noncontact techniques such as laser ultrasound, thermoelastic and thermographic methodologies will be described, and their applications to materials of industrial interest will be discussed."

Jan 1, 1989

By Nicholas J. Welham

"The effect of extended ball milling has been studied for two industrial processes: (1) the processing of metal sulphide concentrates; and (2) the carbothermic reduction of ilmenite to synthetic rutile. The plant concentrates were a gold ore with 128 g/t Au of which 8% was non-refractory and a zinc concentrate with copper impurities.The gold concentrate showed complete dissolution of the gold bearing minerals after milling giving almost complete gold liberation. The zinc concentrate showed almost all of the sulphides had solubilized leaving the gangue and elemental sulphur. A study of pure pyrite and arsenopyrite shows that selective dissolution should be possible by a simple leaching process directly after milling.The milling of ilmenite and coal together results in a temperature decrease of 150°C in the subsequent carbothermic reduction of ilmenite, in addition to improving both the rate of reaction and the selectivity of reduction to rutile. IntroductionAlmost all mineral processing plants use mills for the size reduction of particles prior to physical and chemical processing. When continuing beyond size reduction the energy transferred causes deformation, breakage and realloying of particles giving a steady-state particle size. The breaking also causes increasing damage to the crystal structure by formation of smaller grains giving an increasing number of grain boundaries and increasing crystalline defects due to deformation. The increasing number of grain boundaries and defects leads to increased reactivity, which can be seen directly by a reaction within the mill, or indirectly, via a decrease in the subsequent annealing temperature required for reaction."

Jan 1, 1997

By L. M. Ame, W. D. Harwood

"This paper outlines a management philosophy aimed at promoting employee involvement, quality and process improvement at Inco 's Thompson operations. It describes the use of statistical process control techniques, lessons learned and examples of progress.IntroductionThis paper provides an overview of the Manitoba Division's performance through the promotion of greater employee involvement, quality and process improvement. Having learned from other practitioners o f quality management, the Manitoba Division believes its experiences are applicable to all mining and other businesses.The Thompson operation consists of two underground mines, an open pit, a mill, a smelter and an electrolytic refinery. The workforce consists of 2000 members. The main products are electrolytic nickel slab and proprietary nickel rounds. Production levels are currently at capacity in response to heavy market demand.Paralleling much of the mining industry the corporation was faced with six years of decreasing nickel prices (Fig. I). Inco Limited survived by focusing on productivity and cost improvement. Manitoba Division productivity improved 32070 over three years beginning in 1982-the worst financial year in the company's history (Fig. 2). A real unit cost reduction of 20%, net of inflation, was also achieved (Fig . 3)."

Jan 1, 1990

By P. S. Daly

"The purpose of this paper is to describe the types of instrumentation used at Sherritt Gordon's Ruttan Mine to monitor the"" effects of mining. The aim of the monitoring program is to establish parameters to achieve a maximum ore recovery with minimum dilut ion in a safe environment.The copper-zinc Ruttan Mine is in northwestern Manitoba, approximately 760 km from Winnipeg (Fig . I) . Production commenced in 1973 from the open pit at the rate of 10,000 tons per day. Pit bottom lies 58 metres above the first mine level. Underground development has overlapped with open-pit mining throughout. The open pit was phased out in the latter part of 1980.Underground production began in early 1979. The mining method employed in the first lift is sub-level blasthole open stoping with delayed hydraulic filling. Large-diameter (6.5-in.) holes are being drilled in the crop stope area and are also planned for some other areas for vertical retreat mining into a slot. GeologyThe orebody consists of numerous sulphide lenses of variable size, geometry and geology . The lenses occur within volcanoclastic host rocks which exhibit a strong variability in intensity and type of alteration and structural characteristics. Stope design and sequencing were based on these complex geological factors."

Jan 1, 1981

By K. Musgrave, E. Solis

"This paper tells the story of how the Dome Mine in South Porcupine increased its maintenance effectiveness and reduced its maintenance costs in two phases. In the first phase, a maintenance audit was conducted, and the results led to some changes that improved maintenance, especially in the underground equipment area. The audit methods, and the changes made will be reviewed. In the second phase, management made changes in the maintenance organization and methods, following a prolonged strike during which management operated the mine. These changes were in part the result of insights learned from their hands-on operating experience. IntroductionEarly in 1989 the Dome Mine of Placer Dome Inc. in South Porcupine, Ontario, decided to improve the effectiveness of the Plant Department. The Plant Department was centralized, except for a mill mechanical crew, and serviced all operations, a townsite of 120 houses, a curling rink, and an arena. The department also operated the powerhouse, the hoists, the mine dry and provided mechanical/ electrical engineer services.At that time the Dome Mine, located in the east end of the city of Timmins and Canada's first large gold mine originally discovered in 1909, was producing about 3500 tons of ore per day with about 742 employees. Over the 83 years of continuous operation of Dome over 50 million short tons of gold ore have been processed. The Plant Department consisted of 156 hourly and 24 staff employees. At present, the mine is producing 4000 tons of ore per day with a total of 341 employees on the payroll. The Plant Department consists of 80 hourly-rated and 18 staff employees."

Jan 1, 1993

By Stephen G. Hardcastle, Michel G. Grenier

"Safety and health issues are and have been in the last decade a very high priority item with all parties involved in the Canadian mining industry. As a result of this high level of concern for workers' safety and health, Canadian mines are at the leading edge of environmental control technology. For the most part, the occurrence of pollutants in mines is unavoidable. Dust from mining operations, airborne radiation, gases and heat from the strata as well as gases and particulate from diesel engine emissions will undoubtedly be found to some level in most Canadian mines. A lot of work remains to be done, however, in order to bring all Canadian mines at the same level of proficiency when it comes to safety and health. Also, more work is needed in order to maintain our status as world leaders in this field.CANMET's Mining Research Laboratories (MRL) in Elliot Lake and Bells Corners, Ontario, with the cooperation of the mining industry, have contributed to improving environmental conditions in underground and surface mining and milling operations. The extent of collaboration and efforts vary widely from long-term, multi-million dollar projects between several interested parties to smaller projects involving one laboratory and a single mining operation. This paper gives examples of such collaborative efforts and potential future directions as they apply to: mine ventilation analysis using tracer gas techniques, optimization of mine ventilation network efficiency using real-time monitoring and controlled recirculation (heat saving), respirable dust and radiation sampling and control techniques, diesel emission control using regenerative ceramic filters and, finally, the control of sulphide dust explosions and resulting sulphur dioxide production."

Jan 1, 1990

By J. C. Thornley, H. L. J. Drummond

"Fifty years of wear on the original carbon steel shaft of this hydro turbine necessitated repair operations in 1980. Both austenitic and martensitic stainless steels have been used individually as journal materials in separate trials on an80-inch long and 22-inch diameter radial bearing but neither one nor the other has been successful.The wear and cracking problems of the stainless steels leading to the present abandonment of both classes of stainless steel are described. In particular the dependence of the toughness of type 410 stainless steel on its tempering temperature and the susceptibility of that steel to quench cracking are highlighted because problems have been caused by both of these metallurgical factors.IntroductionAs part of a desire to improve the efficiency of a fifty-year old hydro-electric generating station on the Saint John River, the decision was made to change the journal and bearing material for the shaft bearings, which are stave-type bearings. For the initial fifty years of operation the bearings had been wooden (lignum vitae) and had run on the carbon steel shaft directly. For one of the four unit s at this station the performance of this combination has been truly excellent, and the remaining three sets of bearings had performed well. However there had been shaft wear on the units and the wear had made the shafts somewhat elliptical when a decision was made to install some sort of new journal on to three of the old shafts. [In addition to the wear on the carbon steel journals it was found that one shaft was significantly softer in the bearing area than it was immediately above the bearings (180 Vickers in comparison with 230 to 250 Vickers)] ."

Jan 1, 1985

By W G. Brese

The attention of the world is being focused on the spectacular rise of elemental sulphur production in Alberta. In the short space of a decade, production has increased from less than 10,000 long tons, in 1952, to al-most 1,000,000 long tons in 1962. Moreover, 1963 sulphur production is expected to rise by 50 per cent to approximately 1,500,000 long tons, and further increases are forecast for ensuing years. The reason for this dramatic in-crease in elemental sulphur production, particularly in the last year or two, is that Alberta elemental sulphur is recovered in association with the production of sour natural gas. When very large volumes of natural gas began moving to U.S. markets in the latter part of 1961, the resultant increase in sour gas production led to a marked increase in the production of sulphur. Consequently, Canada, mainly on the strength of sulphur produced in Alberta, will soon become the second largest producer of sulphur in the Free World

Jan 1, 1963

By Roger J. Goodman

"Major industrial restructuring, which started to manifest itself in the mature economies of the Western World and Japan in the 1970s, will accelerate in the 1980s and 1990s. Conventional heavy manufacturing industries will continue to lose ground to lighter processing/assembly operations and the new wave of high technology, information and service sectors. The decline in heavy manufacturing has severely impacted on the steel industries of Western Europe, the U.S.A . and Japan.World trade in metallurgical coal has shifted correspondingly, with declining demand in the mature developed countries being only partially offset by large increases in the steel intensity of the newly-industrialized countries (NICs) of the Far East, Latin America and, to a more limited extent, the Middle East and Africa. These trends will be accentuated in future years with direct implications for the distribution of metallurgical coal trade. This paper discusses, in quantitative terms, such changes in the 1980s and 1990s, and examines the implications for, and impacts on, Canadian metallurgical coal exporters.IntroductionThe twenty-year period from the early 1950 s to the early 1970s was characterized by inexorable growth in consumer demand and industrial expansion in most of the advanced countries of the western world. Long- term forecasting during this period typically used linear extrapolation techniques which , despite their simplicity, invariably ended up predicting future demand and production level s with uncanny accuracy. Times have changed!The last decade has been characterized by a n abysmal failure of our economies to respond to simple long-term, linear growth patterns. We appear to have entered a new world in transition, where we can observe a wave of dying or sunset industries reluctantly being submerged by a wave of emerging or sunrise industries.This paper is aimed a t examining the evidence for long-term industrial restructuring trend s. For want of a better word, these so -called, megatrends are then used to predict future demand level s and spatial distribution of steel development and , hence, metallurgical coal trade. It is tempting to correlate the decline in economic activity in the western world with the first Organization of Petroleum Exporting Countries' (OPEC) crisis of 1973. This crisis was probably no more than the straw that broke the camel's back, as the megatrends and embryo s of major industrial restructuring were already evident. Today these megatrends are merely more apparent and transparent than they were ten years ago.While the concept of industrial restructuring is the new economic buzz word, the process was at work, to a lesser degree even throughout the period of strong economic growth of the post-Second World War boom. Many people still remain convinced that our present-day sluggish economy is just part o f the typical , though rather more prolonged, recessionary cycle. Yet, we have always been part of a dynamic economic system and industry throughout history has been the subject of a continuous process of evolution, restructuring and reconstitution . Now the time is ripe to examine the evidence for such restructuring in order to develop coherent policies of adjustment in this transition from one industrial regime to another."

Jan 1, 1985

By P. L. Lehoux, R. F. Lopes

"Unanticipated low recovery or extraction of gold from heap leachable are can often be attributed 10 phenomena such as non-uniform percolation (channelling) of solution through heaps, excessively slow percolation rates due to densification of ore during stacking on the pads and parasitic or competing reactions of the cyanide solution with undesirable elements or geochemical ""impurities"" in the ore. The nature and causes of these phenomena are discussed in this paper, and it is suggested that geotechnical and geochemical expertise can contribute significantly to a better understanding of the relationship between laboratory results and actual field performance of the leaching process. Recommendations are made for bench-scale metallurgical testing to be complemented by geochemical and geotechnical laboratory evaluations, to ensure more successful heap leach projects. IntroductionHeap leaching is a simple, low-cost method of recovering metals from low grade ores which has now come into widespread application particularly for gold and silver metals in the United States.The heap leach process involves percolating a lixiviant (leaching agent) solution through broken or crushed ore (Chamberlain and Pojar, 1984). In the case of gold a dilute sodium cyanide solution is used and crushed ore is ""heaped"" on specially prepared impervious pads.The potential for use of heaping leaching methods for northwestern Ontario gold deposits was discussed by Beard (1983), who suggested that the use of this extraction technique in Canada should grow significantly for low grade ores as well as for small high grade deposits which cannot justify the installation of a new mill or the use of remote custom milling facilities. Two other potential situations for lise of a heap leaching extraction method are : as a low capital cost cash generator in the opening phase of a larger new project, and as a low cost output augmenter to complement a milling operation."

Jan 1, 1989

By A. J. Hyett, R. D. Reichert

"A laboratory and field research program was conducted to investigate the major factors influencing bond capacity of grouted cable bolts. The results indicate that cable bolt capacity most critically depends on the grout uniaxial compressive strength (UCS), the radial confinement, and the embedment length.In the laboratory &apos;split-pipe&apos; tests were conducted using P VC, aluminum and steel pipes to provide radial confinement, and field test sites were chosen in granite, limestone and shale rock masses. For both datasets higher capacities were obtained under conditions of higher radial confinement. A correlation between the two was obtained through a comparison of the radial wall stiffness of the laboratory pipes with that of the field boreholes as measured using a high pressure dilatometer. Cable bolt capacity was found to increase with embedment length though not in direct proportionality.The use of low water cement ratio grouts (<0.40) can increase cable bolt capacities by 50% to 75%. This effect is maximized under conditions of high radial confinement. However, the use of super thick grout paste (0.30 and less) may be both impractical and undesirable, first because of their limited pumpability and second because of their inconsistency in strength. Grouts with a water cement ratio of between 0.35 and 0.40 are recommended for practical cable bolt applications."

Jan 1, 1992

By C. F. Harris

Following the initial development of the zinc-lead blast furnace, efforts have been directed both at increasing the scope of the process and increasing the cash return. The paper reviews the process developments which enable the process to smelt efficiently a range of material which encompasses high-grade zinc sulphide concentrates. mixed concentrates, Waelz oxide, zinc ashes and other materials blended to give a furnace feed ranging from 25 to 65% zinc and from 1 to 25% lead, with a copper-lead ratio exceeding 1 to 8. The paper also reviews the process developments which have enabled the capacity of a furnace and condenser system of standard size to be boosted from 30,000 to 80,000 tonnes/annum. The benefits achieved are used as a justification for continuation of the development of the zinc-lead blast furnace. Predictions are made of the benefits expected from further developments.

Jan 1, 1979

"Since World War II, urban communities have expanded at an unprecedented rate. The industrial mineral industry supplies the sand, grave], limestone, crushed rock, cement, gyp-sum, etc. for urbanization. Most de-posits in use are close to or within communities. Pollution of water and air has become a matter of public concern. Waste disposal and the effects of noise and vibration are subjects of public debate. Need for the reclamation of land after operations such as strip mining is discussed in magazine articles and on TV pro-grams; i.e., the general public is educated in the unattractive features of mining.Legislation is on the books and being drafted to regulate mining operations and their side effects. To avoid over-regulation and restrictive legislation, it is necessary that the public be educated and legislators informed of problems peculiar to the mining industry. Our side of the story needs publicity."

Jan 1, 1968

By H. Utsunomiya, Mehdi Sanjari, Abu Kabir, Steve Yue, Jing Su, L. Kestens, In-ho Jung

The microstructure and texture evolution of low temperature rolled AZ31 magnesium alloy during annealing were investigated. The specimens were rolled at the temperature of 100? at a high rolling speed of 1000m/min with a reduction of 30% in one pass. Annealing was conducted at various temperatures ranging from 200? to 500? for different time. To study the effect of fast speed rolling, the same annealing procedures have been applied for the specimens rolled at a significantly lower speed of 15m/min. The microstructure was characterized by optical microscopy and scanning electron microscopy, while the texture was analyzed by X-ray diffraction analysis and electron backscattered diffraction analysis. Texture weakening occurred during annealing at both fast and slow rolling speeds. However, at the same annealing condition, fast rolled specimens always had weaker intensity of basal texture than slow rolled ones.

Jan 1, 2014

By R. G. L. McCready, R. O. van Everdingen, M. Kalin, R. van Everdingen

"This paper is based on data generated between October, 1986 and October, 1989, during the implementation of an Ecological Engineering close-out for a zinc mine in Northern Ontario, where 690000 tonnes of tailings contain 41.1% pyrite and 4.1% pyrrhotite. The objective was to determine rates of sulphide oxidation and iron precipitation in the tailings. Those rates are relevant for the assessment of the long-term effectiveness of biological systems employed in the removal of heavy metals from contaminated drainage issuing from tailings.Data were collected on the topography and stratigraphy of the tailings basin, subsurface temperatures and groundwater levels, and chemical analyses were made of water samples collected from a number of piezometers. The thickness of unsaturated tailings varied widely between individual piezometer locations; annual maxima ranged from 0.67 m to 3.55 m, and annual minima from 0 to 2.68 m. Sulphate concentrations ranged from 36 mg/L to 20180 mg/L; iron concentrations from 0.36 mg/L to 9938 mg/L; and zinc concentrations from 0.33 mg/L to 1123 mg/L.The geochemistry of the piezometer samples suggests that some of the initial Fe content, resulting from metal sulphide oxidation, is subsequently precipitated in the tailings pile and, possibly, in the underlying unconsolidated sediments, probably in the form of iron-hydroxide and Na-jarosite. Other metals such as Zn may be co-precipitated with Fe. The discharge of a portion of these metals to the environment would be delayed by this process. Some of the initial sulphate may also be lost from solution, probably by precipitation of gypsum; approximate saturation degrees for gypsum ranged from -3.27 to +0.47. The precipitated minerals will somewhat decrease the porosity and permeability of the tailings.Sulphide-oxidation rates, calculated using the analytical results and the estimated amount of annual recharge at the tailings site, average 0.0057 mol/kg/yr. Calculated iron-precipitation rates average 0.000386 mol/kg/yr. It is concluded that the characteristics of seepage from mining wastes may change with time, reflecting the solubilization of precipitated secondary minerals."

Jan 1, 1992

By G. E. Norman, R. E. Michelutti

"One of the major objectives of Falconbridge has been and continues to be, to minimize the impact of its operations on the environment around its Sudbury operations.The approach to achieving this objective and the results, are discussed under the following topics .I . Sulphur Dioxide Emission Improvements.2. Effluent Treatment Improvements .3. Effect of the Envrionmental Improvements.Sulphur Dioxide Emission ImprovementsHistoryThe rejection of pyrrhotite in the concentrators is one method of reducing the amount of sulphur to the smelter and therefore the sulphur dioxide emissions. In the 1950s and 1960s, Falconbridge developed the capability to remove 54% of this pyrrhotite. Numerous attempts were made to increase this amount by treating the pyrrhotite for recovery of nickel and in some cases elemental sulphur. Processes tested and operated were: hydrometallurgical pilot plant, roast-leach commercial operation and nickel-iron refinery. None of these processes proved to be commerically successful for both technical and economic reasons. Falconbridge therefore redirected its efforts to reducing sulphur emissions by improving its smelting process under The Smelter Environmental Improvement Project. A major component of this project was the installation of a sulphuric acid plant to recover the S02 in the roaster off-gases."

Jan 1, 1984