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By Eirik Sundvor, Hany Doss, Peter Vogt, Kathleen Crane

"Abstract - In 1989-1990, the SeaMARC II side-looking sonar (11 to 12 kHz) and swath bathymetric system imaged more than 80 000 km2 of the seafloor in the Norwegian-Greenland Sea and southern Arctic Ocean. One of our main goals was to investigate the highly oblique (115°) junction between the Mohns and Knipovich ridges, and to determine, using new morphotectonic data, whether or not this junction is stable or in a state of readjustment. These findings are presented in this paper.Along the northern Mohns Ridge, we observed a highly segmented rift valley undisturbed by transform faults. In contrast to the elevated Reykjanes Ridge, the Mohns Ridge is dominated by deep en echelon fault-bounded troughs, which are bordered by high rift valley volcanoes. These segment boundaries are interpreted to be sites of recent to present volcanic activity, based on their high acoustic reflectivity. The northwestern flank of the Mohns Ridge is marked by shallow quasi-linear ridges parallel to the present orientation of the Mohns Ridge. The orientation and geographic position of these ridges suggest that they were formed at the Mohns Ridge. Only in the northernmost cases are some of these off-axial ridges non-linear. The degree of the non-linearities increases slightly with proximity to the Mohns-Knipovich bend. In addition, because no transform fault was detected between the Mohns and Knipovich ridges, we conclude that the Knipovich Ridge must be obliquely spreading to the NW-SE."

Jan 1, 1999

"Sedimented hydrothermal precipitates of silica, now fine-grained quartz, are described from a Pb-Zn-bearing vein system. Their discrimination from the wall-accreted fine-grained quartz that is common in the shallow parts of epithermal systems is discussed. Local fine-grained (<0.3 mm) quartz accumulations occur in a suite of veins with otherwise normal drusiform and crustified infills. This sediment may fill the vein above chokes in steep segments (axial plugs), or form continuous layers within the footwall material where the vein is inclined at low to moderate angles. Pads of fine-grained sediment are deposited on the upwards-facing surfaces of wall-rock clasts and of drusiform crystals growing from the vein walls. The asymmetry of these deposits differentiates them from the more common symmetrical, crustified walllining deposits of fine-grained quartz and opaline silica, and requires a gravity-controlled, sedimentary depositional mechanism.Thin section examination shows that much of the fine-grained quartz is present as elongate prisms. The prism habit was present soon after deposition, but it is not possible to identify unequivocally the original sedimented grains. Sedimentation of vein- and wall-rock-derived detritus is also recognized. Deposition of the fine-grained sediment accompanies normal in situ drusiform growth of quartz and other vein minerals. The mammilated and spherulitic textures associated with accretion of amorphous quartz are entirely absent from the Tyndrum veins with sedimented materials. The literature on modern hydrothermal waters and physical chemistry of silica precipitation shows that precipitates of silica suspended in hydrothermal fluids are amorphous and derived from colloidal silica. It is argued that much of the suspended silica was present as quartz at the time of deposition or was converted from amorphous silica almost immediately after deposition.Hydrothermal sediments and their distribution potentially provide information on flow directions and velocity in veins. Plugs of sediment obstruct vertical flow and lead to local flows with large horizontal components. It is shown that sedimentation features occur in other deposits and can involve other minerals. If the features seen here can be scaled up to the size of major veins, they may result in up and downdip variations in mineral assemblages and abundances, which may affect grade."

Jan 1, 2007

By Frank Ebbutt

In this paper it is proposed to point out certain structural factors that; have an important bearing on gold deposition. The subject will be treated; more or less generally. Although the writer has had access to a great many; of Canada's gold mines he does not wish to take the liberty of discussing; details of any particular mine or mines; the aim will be to discuss controls; that are evident in many places.

Jan 1, 1954

By William H. McCracken, William G. Holroyd

"The People&apos;s Republic of China could very well be considered the largest untapped mineral and metal resource in the world. The proven reserves of antimony, barite, bauxite, fluorspar, graphite, lithium, magnesite, mercury, molybdenum, phosphate, pyrite, rare earths, talc, tin, titanium, tungsten, vanadium and zinc are among the largest in the world.Any company involved in the purchase or supply of industrial raw materials has undoubtedly followed the phenomenal growth of some of the Chinese mineral commodities, where growths in production of more than 200010 have occurred during the past ten years, for commodities like barite, cement, gold, gympsum silver and talc. Others, like bauxite and phosphate, experienced production increases in one year alone of over 45%, from 1986 through 1987!A popular rationale in the United States during the past two years has been the acknowledgment by Professor David Calleo, of Johns Hopkins School of Advanced Studies, that ""America is not sinking-the rest of the world is rising"". While we recognized this rise to be that of economic power for Japan, Korea, Brazil, Taiwan and, more recently, the newly-combined Germanies, China has also successfully completed her own modern five year development binge. But with each boom there is also a bust, and the start of the 1990sfor China shows signs of economic distress. China posted a budget deficit equivalent of US$1.9 billion in 1989 coupled with official inflation at 18010. Projections for 1990 are for US$1.8 billion deficit and inflation as high as 24%. However, government spending in the first seven months of the year climbed 16.4%, outpacing an 11.6% rise in revenue. Spending increases have been related to the government policy to keep prices on domestic goods artificially low, through subsidies, and to bailout inefficient state companies."

Jan 1, 1991

By K. L. Ford, D. R. Lentz, J. H. Rickard, R. P. Taylor

Abstract - Coupled gamma-ray spectrometric and lithogeochemical studies throughout the Heath Steele Mines area, Bathurst Camp, New Brunswick, indicate that primary and secondary geochemical differences exist between the stratigraphic footwall and hangingwall crystal tuff units which host the massive sulfide deposits. Of particular interest is Th, and to a lesser extent, Zr and Y, which are more concentrated in the hangingwall than the footwall crystal tuffs, whereas the opposite is true for TiO2. This expands on earlier lithogeochemical-chemostratigraphic results concentrated in the eastern part of the Heath Steele belt that led to revision of the local stratigraphy, and necessitated a structural re-interpretation of the area with implications for exploration. Although K depletion (decreased K and K/Th) is typical of chloritized footwall zones of chloritization, these features were not fully apparent here due to the recessive nature of these altered zones. In situ radiometric analysis using a portable gamma-ray spectrometer is a rapid, inexpensive analytical technique for chemostratigraphic characterization of rock units within volcanogenic massive sulfide deposit settings, provided there is a contrast in the distribution of natural radioelements, particularly Th and K.

Jan 1, 1998

By E. Lehtila, J. J. Talja, R. Jahila

Kopar Oy is acknowledged for engineering and manufacturing of robust systems for bulk material handling, especially at power plants and non-ferrous smelters. We have over thirty years of experience with systems specifically designed for hot and abrasive conditions, aiming at low cost of ownership, low operational expenses and high availability. Although Kopar has numerous applications in mechanical conveying, there is an increasing number of pneumatic conveying applications at copper smelters. They relate to conveying of concentrate, and primary and secondary flue dusts. Challenges of pneumatic conveying for concentrate are mechanical and do relate to broad particle size distribution and high abrasivity of the concentrate and the silica. Therefore, special attention shall be paid to system design and ceramically lined bends in the pipeline. Challenges of pneumatic conveying of primary flue dust relate predominantly to material stickiness and poor flowability which are mainly due to fine particle size and formation of sulphates and furthermore, crystalline water. Additional challenges of secondary dust, the white converter dust, are primarily due to the extremely fine 0.1–1.5 µm particle size and problems which come with this. Effect of material characteristics like size distribution, morphology and chemical composition in pneumatic conveying are discussed in detail. INTRODUCTION Fine materials like concentrate, feed mix, flue dusts (from waste heat boiler and electrostatic precipitator) and secondary dusts need to be conveyed at smelters. Both horizontal and vertical conveying and combination of those are used. For the purpose, both mechanical and pneumatic conveying are applied. Most widely used equipment are drag chain conveyors and various combination of pneumatic systems, e.g. air lift, dense-phase and dilute phase pneumatic conveyors. Kopar has 30 years’ experience with multiple material handling systems. Furthermore, acquired companies like Elmomet Oy and SITE Oy (both currently fully merged and integrated into Kopar Oy) have even longer history, especially in pneumatic conveying. It is commonly known that the finer the dust the more difficult it is to be conveyed pneumatically. Sulfates with crystal water makes it all even more difficult, if not ineligible. Challenges related to pneumatic conveying of various fine materials is discussed in detail in the paper.

Jan 1, 2019

By Karen Munro

Importance of Aquatic Studies for Mining ?Aquatic habitat is usually the first area where a mine interacts with the ?real world? outside the mine footprint ?Water management is a key consideration for a mine?Effects on the aquatic environment often extend to wildlife and human uses ?There is a lot of regulatory focus on issues of water quality, fish and fish habitat

May 1, 2011

By Rénard Chaigneau

Quality during induration Drying ??40% of energy ??Drying velocity = f(1/radius2) ??Size versus risk of condensation ??Flow is important (minimise fines)Oxidation ??IOC Fe2+ typically 0.04% ??Important to minimise Fe2+forLow Temperature Disintegration ??Tight size distribution is key13

May 1, 2011

By S. Konetschnik, Lux Degel, R. Degel, T. Haslinger

UrbanGold and its partners from Mettop and SMS group have developed a novel technology for the recovery of valuables from all non-ferrous metals’ fractions of WEEE (Waste Electrical and Electronic Equipment), with a special focus on low qualities which are commonly landfilled or incinerated. The technology is marketed under the brand name “UrbanGold Flex” to illustrate the high flexibility in respect of plant design and raw material portfolio, allowing also the processing of low grade material and materials with high caloric values. The process of the technology’s centrepiece, a modified and enhanced bath smelting furnace called “HENRI”, was investigated in numerous pyrometallurgical trials as basis for a scale-up towards a capacity of up to 100,000 tons of WEEE-concentrates per year. All relevant facility components have been evaluated in respect of references, fall-back options, as well as exit strategies (alternatives) to minimize risks when establishing a novel technology. A spin-off within the development is the “UrbanGold Compact” technology which can be seen as optimization of state-of-the-art smelters by using an optimized TBRC as primary processing unit. As an UrbanGold Compact plant will be the first industrial scale reference of UrbanGold’s technologies, it is also explained in the publication. As precious metals recovery is of major (economical) importance when recycling WEEE, major attention has been given to minimize the losses of these valuables. These measures, as well as a sophisticated way of utilizing waste heat as far as possible, result in interesting business cases with gross profits of up to 20% or even more. INTRODUCTION Over the past years, the demand of electrical and electronic equipment has increased dramatically with technological progress. Innovations on the technology of electronic devices led to a shorter usage and lifespan and thus boosted the generation of Waste Electrical and Electronic Equipment (WEEE). WEEE is one of the fastest growing waste streams, growing at 3 to 4% per year worldwide and is expected to reach more than 52 million tons per year by 2021. Currently, about 45 Mt of these wastes are estimated to arise worldwide, and the trend is rising (Baldé et al., 2017).

Jan 1, 2019

By J. R. Kadambi, E. Kucukal, J. Furlan

"Hydrocyclones are used in various industrial applications, including mineral processing and tailings management, to separate or classify solid particles and/or liquid droplets from multiphase feed. The fluid flow in a hydrocyclone (used in mineral processing) was investigated numerically and experimentally using particle-image velocimetry (PIV) and refractive index matching techniques. Two turbulence models were used in the calculations: the k–? model and the Reynolds stress model. Particle image velocimetry measurements were taken at various spatial locations along the cyclone. Computational results were validated globally using pressure and flow-rate readings at the boundaries, and locally by comparing the PIV velocity-vector maps and profiles.RÉSUMÉ On utilise les hydrocyclones dans diverses applications industrielles, dont la minéralurgie et la gestion des résidus, pour séparer les particules solides et/ou les gouttelettes liquides de l’alimentation polyphasée, ou pour les classifier. Une étude numérique et expérimentale sur l’écoulement des fluides dans un hydrocyclone (dont on se sert en minéralurgie) a été menée à l’aide des techniques de vélocimétrie par images de particules (PIV, de l’anglais particle image velocimetry) et d’appariement des indices de réfraction. Deux modèles de turbulence ont été utilisés dans ces calculs, à savoir le modèle de turbulence k–? et le modèle aux tensions de Reynolds (RSM, de l’anglais Reynolds stress model). La valeur de la PIV a été mesurée à diverses positions spatiales le long du cyclone. Les résultats de ces calculs ont été validés globalement à l’aide de relevés des pressions et du coefficient d’écoulement d’une extrémité à l’autre de l’hydrocyclone, et localement à des coordonnées spatiales spécifiques en comparant les cartes et les profils du vecteur vitesse PIV."

Jan 1, 2017

By Z. D. Hora

The major fluorite producer in British Columbia was the Rock Candy Mine, inactive since 1942. Other deposits of economic interest include the Rexspar deposit, in which fluorite is associated with uranium and rare earth mineralization, and the Eaglet and Liard River occurrences. THE former Rock Candy fluorite mine, located 26 km north of Grand Forks, is the only major past producer of fluorite in British Columbia. The deposit was in production from 1918 to 1929 and again in 1942; total output was about 36,000 tonnes with average grade between 22 and 32 per cent CaF2. The fluorite body occupies a steeply-dipping vein structure, approximately 175 m long and up to 12 m wide, in porphyritic syenite. The chief vein-filling minerals are quartz and fluorite with local small len ses of barite. Fluorite content decreases with depth and the deposit becomes silicified. The Rexspar (or Birch Island) fluorite deposit is located 130 km north of Kamloops. The deposit is complex with rare earth elements and high uranium values, but !1uorite mineralization forms an independent zone adjacent to the uranium orebodies. Fluorite is present as fine-grained impregnations and as breccia cement in strongly schistose or brecciated alkali feld spar porphyry. Reported reserves are 1,088,000 tonnes of 22 per cent CaF2 or 450,000 tonnes of 29 per cent CaF2. 268 Another potential deposit of fluorite is Eaglet, situated on the north side of Quesnel Lake. Fluorite occurs as a stock work with scattered veins and irregular lenses up to 20 centimetres wide and as impregnations in altered Proterozoic Kaza Group feld spathic gneiss over an area of 1,500 metres by 500 metres. To date (1983) approximately $2 million have been spent on the exploration of this property and reserves of 18.8 mimon tonnes grading 11.59 per cent CaF2 have been outlined . A group of significant occurrences is known from north of Liard River Hot Springs Park , where fluorite occurs in small zones up to 17 m thick along the interface between Middle Devonian Dunedin Formation limestone and Middle Devonian to Mississippian Besa River Formation argillite. Fluorite, associated with witherite, barytocalcite and barite, is present as replacement bodies, breccia fillings and minor veins.

Jan 1, 1984

By N. Katsikaros, N. S. ‘ Yap, B. Adaszynski

"Cyanide is a well proven, effective lixiviant that has been utilised for centuries in gold extraction processes. Despite being used in close to 90% of gold processing plants, cyanide leaching is still being scrutinised due to its toxic nature. With governments tightening the regulations on cyanide management, and recently erected sites situated closer to community and environment, leach waste and tailings treatment has become increasingly important. Gekko Systems has worked with engineering companies and directly with gold producers to provide technical services and supply complete modular cyanide destruction (detox) systems for plants leaching both run-of-mine ore and high sulphide gravity and flotation concentrates. Although similar in principle, the different materials presented unique challenges in design and implementation. Similar to designing any section of a processing plant, the development of the cyanide destruction plant design began with laboratory test work to simulate the full scale operation. This paper focusses on the laboratory test work and how other critical factors such as geographical location, logistics, and local community play a role in the process design and construction. Two design and supply cases are discussed in this paper; one treating intensive cyanidation concentrate leach tails and one treating whole ore CIL tails. Although these plants both use the SO2/O2 process, each presented different challenges in laboratory testing and plant design, resulting in variations in final implementation including reagent choice, oxygen supply, and process control.INTRODUCTIONSince 1887, cyanide has played a large part in the beneficiation of gold from gold bearing ores. Cyanide is used to solubilise gold into solution, and is typically added in excess to maintain the leaching process. Some or all the excess cyanide can often be recovered and reused in the process however chemical destruction of cyanide is often necessary to manage cyanide levels in the tailings storage facility (TSF)."

Jan 1, 2016

By Christian Brits, Bob Blain, Lloyd Buckingham, Juliu Stieger, Jean-Francoi Dupont

Barrick Gold Corporation (Barrick) has undertaken innovative methods of evaluating and improving the performance of grinding mills in several of its operations around the world. The results have been positive with some of the mines showing more than 20% net energy improvement leading to more than 43,000 tonnes per year reduction in CO2 emissions in four of the operations reviewed.

Jan 1, 2012

By M. Bavand-Vandchali, F. Golestani-Fard, S. Khalili, S. Rowshanfekr-Fallah

In the secondary metallurgy of steel, the availability of ladles plays an important role in decreasing the production cost. The refractory lining, therefore, should satisfy optimized quality to grant higher heats. This paper reports the results of an investigation carried out in Iranian Mobarakeh Steel Company in order to increase the lining life of ladles by employing different types of MgO C and Al203 - Mg° - C. The zoning concept was used in replacing the conventional refractories either in slag line or the lower parts of ladle. The number of heats could be improved to almost two times as before. The results are explained in terms of refractory quality as well as zoning approach. The economical impact of this improvement will also be analyzed.

Jan 1, 2004

By M. A. Roche

The property of the Hudson Bay Mining & Smelting Company, Limited is located at Flin Flon lake, 85 miles northwest of The Pas, Manitoba, on the Manitoba-Saskatchewan boundary. The area is at latitude North 54°, and is approximately 1,000 feet above sea level. The ore-body occurs in amygdaloidal greenstones, which are to be referred to the earliest basic volcanic flows in the district. It was discovered in an outcrop on a point of land jutting into Flin Flon lake, and subsequent diamond drilling proved that it extends under the lake both to the north and south of the point of discovery. After the taking of soundings from the ice during the winter months, it was estimated that l,000,000 tons of overburden, mainly mud and clay, would have to be removed to expose the underlying ore. Flat diamond-drill holes indicated that the ore-body was separated into more or less independent lenses by horses of unmineralized greenstone, and that in places the overall width, including horses of waste, reached 450 feet. These several] conditions were the main factors influencing the management in their decision to adopt an open-cut method for the mining of the upper portion of the ore-body. Before it was possible to commence stripping operations, it was necessary to dam-off the eastern portion of Flin Flon lake, instal pumps, and de-water the dammed-off area. Dams for this purpose were constructed of mine waste rock and clay filler from nearby hillsides. Material for the bottoms of the dams was taken across Flin Flon lake in hopper-bottom barges. Trestles were then built on the dam bottoms and dams were complete by the time trackage was available. De-watering commenced in April, 1930, and was completed by the latter part of May of the same year. Estimated pump output for the period was roughly four billion gallons. Two Morris 10-inch dredging pumps were used, direct-connected to 250 h.p. electric motors. Individual pump capacity was rated at 3,000 g.p.m. against a 150-foot head. Average head for the operation was 50 feet, which increased the total output considerably. The pumps were mounted on floating barges in cribbings of piling driven at the lowest points in the lake bottom.

Jan 1, 1933

By J. A. Hudson

"The paper begins with a brief summary of Professor Müller’s formation of the ISRM and the contents of the previous six Müller lectures with their emphases on rock fractures. The geological origin of fractures is described via a deformational spectrum diagram and a matrix characterising the consequences of a sequence of superimposed deformational events. The different fracture frequencies encountered along lines in all directions through a fractured rock mass are explained. The value of computer modelling and simulation is demonstrated through an example of the effects of fracture zones on the distribution of the in situ stress field. The need to establish the validity of computer programs, i.e., that the modelling/simulation, does actually represent the rock reality, is discussed with reference to the work of the DECOVALEX project. Finally, examples are given of the effects of rock fractures on engineering design and construction, from pre-split blasting to caverns.INTRODUCTIONIt is a great honour to have been chosen as the recipient of the ISRM 7th Müller Award and I am grateful to the representatives of the International Society for Rock Mechanics (ISRM) National Groups who voted for me. In addition, I am especially pleased because my working life in rock mechanics and rock engineering has been devoted to understanding the geometry and mechanical properties of rock fractures and rock masses—which were the key subjects that Professor Müller promoted. In the ISRM 50th Anniversary Commemorative Book, Hudson and Lamas (2012), Professor Charles Fairhurst notes that on 24 May 1962, i.e., the day before the constitutional meeting of the ISRM took place in Salzburg, a reporter asked Professor Müller, “Do we know the strength of rock?”, to which Professor Müller replied, “For rock tested in the laboratory, yes. For a rock mass, no. This is what we need to determine. This is why we need an International Society for Rock Mechanics”. Also, in his Opening Address at the 1st ISRM Congress in Lisbon, Professor Müller, as the then ISRM President stated,“Many experts agree with me that discontinuity and anisotropy are the most characteristic properties of the material rock and that the properties of jointed media depend much more upon the fabrics bond of the unit rock block system than upon the rock material. Therefore any theoretical investigation of that material has to go its own ways, in the same way as the construction material of soils years ago suggested to soil mechanics its own methods, which differ greatly from the way of thinking of technical mechanics”."

Jan 1, 2015

By L. Shang

In conventional continuous hot rolling processes, metals are usually reheated to a temperature such that the workpiece will maintain appropriate hot working characteristics as it proceeds through the rolling mill, assuming that the temperature is continually decreasing. Metallurgically, reheating will reduce micro-segregation in the as-cast material, may increase the as-cast grain size and will affect any second phase particles present in the as-cast structure. All these changes can affect the hot working characteristics, and the final as-hot rolled microstructure. In order to study the effect of reheating on AZ31 magnesium alloy, a plate sample was cast in a water cooled copper mould and a series of compression tests was performed at a temperature of 350 °C, strain rate 0.01 5-1, and strains from 0.2 to 1.0, after different reheating schedules. It was found that there is no significant difference in flow behavior between the as-cast sample and all but one of the reheated ones. The reheat treatment of the &apos;anomalous&apos; sample was a two stage heat treatment; it was first reheated to 450 °C, cooled to room temperature, then reheated to 350 °C. The effect on the flow curve was to increase the flow stress. This result may be related to changes in second phase particle characteristics.

Jan 1, 2006

By W. H. MacLean, S. Liaghat

The Key Tuffite is a thick (0.3 m to 6 m) and laterally extensive (-10 km) cherty, sulfide-bearing tuff unit in Archean greenstones in the Matagami mining district in northwestern Quebec. It lies at the contact of the Watson Lake Group and overlying Wabassee Group volcanic rocks, and is host to major Zn-Cu volcanogenic massive sulfide deposits. The tuff component is highly altered and its volcanic precursors are not identifiable by petrographic means. The tuff is mixed with a volcanic exhalative component comprising chert, carbonate and sulfides (pyrite, pyrrhotite, and minor sphalerite and chalcopyrite). The normative mineral composition of the Key Tuffite is 33% quartz, 28% sulfides, 16% sericite, 8070 carbonate, 6% chlorite and 9% other minerals. In the vicinity of the Bell Allard and Orchan mines, the precursor tuff components are identified using immobile major and trace elements, as Watson Lake tholeiitic rhyolite (Zr/Y = 1.5 to 3.5, LaN/ybN = 1.7 to 2.8, SiO2 = 72.5 ± 1.2 wt %, and Wabassee calc-alkaline andesite (Zr/Y = 9, LaN/YbN= 4 to 8, SiO2 = 56% to 65%). Immobile element computation techniques were used to calculate mass additions and losses in the conversion of the tuff to the Key Tuffite. Average net amounts of FeP3 (27% total iron), Si02 (14%), Cao (8%), S and K2 (+ 2%), were added, Nap was removed (-2.8%), and MgO was over-all unchanged. Total net mass change was +63%, which comprises mainly exhalative additions, but also includes changes owing to hydrothermal alteration of the tuff component.

Jan 1, 1992

By J. Palarski

In the Polish coal mining industry, the use of mine waste in underground backfill has been the most common means of providing ground support to minimize surface subsidence, increasing extraction ratios, and reducing the quantity of waste for surface disposal. Over the last decade attention has been focused on the use of different waste as filling material of underground workings and grouting of roof fall rocks in caving area. In the paper, a brief history of the development of fill technology in Polish coal mining industry is presented. Next, the paper discusses various criteria that should be taken under consideration in the preparation process of a fill slurry and grout, fill distribution systems, mining geometry and placement methods. Moreover, in the paper evaluation of the potential of utilizing coarse and fine waste as a resource material in the production of a backfill slurry and grout for filling and injection in abandoned mines is presented.

May 1, 2007

By C. Sui, J. E. Nesset, M. Li, J. Y. Kim, S. L. Chryssoulis

"A plant study of zinc rougher flotation at Brunswick Mining was conducted using lime, soda ash and a combination of both as the pH modifiers in order to establish the effects on sphalerite and pyrite kinetics and mineral selectivity. The plant sampling and analysis was augmented by surface analysis using TOF-LIMS, SEM and XPS as well as fundamental precipitation and surface-charge studies in the sphalerite Ca/C03/S04 system.The results revealed the important role of carbonate ions in cleaning the sphalerite surface for effective activation by CuS04 to occur, and the beneficial role of combined soda ash and lime in increasing pyrite and galena depression.1.0 IntroductionThe studies reported in this paper were initiated as part of an investigation into the causes of a particularly pronounced seasonal deterioration in metallurgical performance at the Brunswick Mining concentrator during the summer of 1995. The concentrator treats a complex base metal ore having a typical feed composition of 9.0% Zn, 3.5% Pb, 0.4% Cu and 100g/t Ag at a current throughput of 9,000 TPD, although at the time of the problem in 1995, the average production rate was closer to 10,500 TPD. Zinc, lead, copper and bulk (zinc-lead) concentrates are produced with overall metal recoveries of 86% zinc, 63% lead, 60% copper and 60% silver; results which are typical of the lower recoveries associated with fine-grained, highly complex VMS and SEDEX type deposits. The main economic minerals of interest are an iron-containing (7% Fe) sphalerite, galena and chalcopyrite with the main diluent (about 60% wt) being pyrite.Figure 1 shows a simplified flowsheet of the Brunswick milling circuit while the seasonal decrease in summer metallurgy in 1995 is illustrated in Figure 2. Of significance is the rapid drop in copper and lead recovery in June while there is an apparent delay until late August-September before the zinc deterioration reaches its lowest point. A more typical seasonal effect within the experience of the authors is the reverse of the Brunswick situation, namely an improvement in summer performance thought to be associated with improved differential flotation kinetics during warmer weather leading to better mineral selectivity. The historical Brunswick experience was particularly severe during the summer of 1995 with estimated incremental losses of $10 Million for this period. The potential of the very significant economic benefits to be gained from understanding and hopefully improving the annual drop in performance led to an investigation involving the minesite metallurgical group, the Noranda Technology Centre (NTC) as well as researchers in Professor Jim Finch's group at McGill and the surface analytical services and interpretive skills of AMTEL."

Jan 1, 1998