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By BARRY BANNATYNE

About 90 per cent of Manitoba's industrial minerals production is for structural materials. Most of these come from the Paleozoic rocks west of the Precarnbrian Shield, or from glacial deposits that are extensive throughout Manitoba. The major raw materials are sand and gravel, and carbonate rocks for crushed stone (and also dolomite for high-magnesia lime, high-calcium limestone for lime and Portland cement, and dolomitic limestone for Tyndall stone). Glacial lake clays are used both in cement and in lightweight aggregate. The Jurassic and Cretaceous strata exposed along or near the Manitoba Escarpment include siliceous, carbonaceous, kaolinitic and illitic shales, all of which are quarried by Red River Brick and Tile in the Pembina Mountain and Ste. Rose areas for use in a brick plant at Lockport. Non-swelling bentonite near the base of the Pembina Member of the Upper Cretaceous Vermilion River Formation is of value as an absorbent clay, and is the only commercial source in production in Canada. It has been quarried by Pembina Mountain Clays Limited since 1940. Gypsum occurs in the Jurassic Amaranth Formation and supplies much of the market for wallboard and Portland cement additive in the Prairie Provinces. Quarries are operated at Gypsumville by Domtar Construction Materials Limited, and north of Amaranth by Westroc Industries Limited. Silica sand from the Ordovician Winnipeg Formation is of glass-grade quality, and about 100,000 tonnes are produced annually by Steel Brothers Canada Limited on Black Island . It is used as a glass sand, as foundry sand, for sand blasting, and as a filter-bed sand .

Jan 1, 1984

By A. Sargeant

This paper evaluates the application of post consumer glass as a cementing agent in underground mine backfills. The underlying theory indicates that glass is pozzolanic and, when used in a finely divided form, behaves as an activator to generate binding products, thus contributing to the development of backfill strength. The objective of this study was to evaluate the strength performance of backfills when Normal Portland Cement is replaced with various percentages of post consumer glass. The study evaluated the performance of backfills prepared using tailings from three mines. Each backfill was prepared using unique recipes, and were evaluated at cure times of 7, 14, 28, 56, 112 and 224 days. Laboratory work involved visual, physical and chemical material characterization followed by strength evaluations. Results of strength assessment revealed that backfill prepared with glass is reactive and can contribute to the strength of backfill. The results also indicated that the reactivity of glass may be affected by the incorporation of slag within the recipe, the availability of lime and the level of hydration of the binders. The study concluded that, at 15 % glass replacement of NPC, backfill prepared with mine tailings, NPC and glass can achieve improved or equivalent strength performance compared to backfill prepared tailings and NPC alone.

May 1, 2007

By F. S. Su, P. Z. Pan, X. T. Feng, F. Yan, W. W. Ji

"This paper aims to simulate the spalling failure behavior in hard rock based on a self-developed numerical model, i.e. a rock discontinuous cellular automaton (RDCA). A crack initiation and propagation criterion is proposed based on the plastic strain, which is used to link the continuity and discontinuity during the failure process. The discontinuities of rock, such as cracks and other internal boundaries, are represented by discontinuous displacement functions, i.e. tip enrichment and step enrichment. The partition of unity is used to improve integral precision of the elements intersected internal boundaries, which is traced by a level set method. Arbitrary crack geometries can be conveniently represented and it does not require any remeshing in the modeling of crack initiation, propagation and coalescence. Numerical modeling of excavation in hard rock using RDCA is conducted. The spalling failure process of hard rock induced by excavation is well simulated. The depth and shape of hard rock spalling failure are good agreement with in situ observation.INTRODUCTIONThe excavation in rock mass is more and more popular. At the same time, the disasters, such as rock burst, rock spalling and falling etc, induced by excavation are quite prominent. Numerical modeling is an important way to help us understand the failure mechanism of rocks. Many numerical methods have been used to simulate the excavation of rock mass. For example, the finite element method (FEM) (Karakus and Fowell, 2003), the discrete element method (DEM)(Cundall and Strack, 1979, Labra et al., 2008), Finite difference method (FDM)(Zhu et al., 2009), Element Free Galerkin Method (Belytschko et al., 1994), Discontinuous displacement analysis (DDA) (Shi, 1988) and Boundary element method (BEM) (Katsikadelis, 2002, Chen and Hong, 1992) are commonly found in the stability analysis of excavation in rocks. In the modeling of crack propagation or excavation, most of these methods are tedious since the internal boundaries have to be consistent with the element boundaries. And in many cases, the remesh has to be conducted. In recent years, people are interested in particular types of FEMs, such as the extended finite-element method (XFEM), the particle discretization scheme finite-element method(PDS-FEM(Hori et al., 2005, Oguni et al., 2009)), the combined finite-discrete element method (FEM/DEM) (Munjiza and Wiley, 2004, Cai, 2008) and spectral-element method(Gharti et al., 2012) etc."

Jan 1, 2015

By E. Yan, M. Mankosa, E. B. Wasmund

Mechanical cells are the dominant unit operation in base metal rougher flotation applications worldwide. As economic demand for metals increase, and as the feasible ore grades decrease, the installed capacity of mechanical flotation units worldwide has greatly increased, adding significant capital and operating cost. One opportunity to improve this situation is to use fundamental knowledge to make the industrial flotation process more efficient. A key insight is that the flotation process can be optimized by dividing the processing of the pulp into two distinct fluidic environments; a collection cell where air and pulp mix in a highly energetic compartment, and a low energy gravity separation cell. This is the basis of the “2-stage flotation device” that has been patented by Eriez and marketed under the tradename StackCell™. Two industrial case studies will be presented to highlight the potential metallurgical and commercial advantages of the StackCell. In the first, a train consisting of three pilot scale StackCells (each 0.6 metre diameter) was run in parallel with a train of conventional mechanical cells in a major copper concentrator and benchmarked against a batch Denver test. In the second, the performance of a 3 metre diameter StackCell in a nickel sulfide cleaning application was benchmarked against a batch Denver test. The flotation kinetics observed in the StackCells were 2.4 to 2.9 times faster when compared with the lab Denver test. In the first case study, the kinetics of the StackCell was about six times faster than conventional mechanical cells. It is hypothesized that the efficiency improvement in kinetics is because of reduced “drop-back” during the froth recovery phase, which is reduced because of the reduction in the shear that is present in a conventional mechanical tank cell. This result suggests that a 2-stage flotation system can be used to reduce the working volume of flotation units by five to six times. This would allow operators to significantly reduce the size of their flotation lines for a comparable flotation objective. Some discussion will follow about the scale-up criteria, maintenance and operability issues, comparisons of layout, and possible cost savings. INTRODUCTION The solution that most equipment suppliers have offered to reduce the cost of mechanical flotation equipment over the last 30 years has been to increase the size of the flotation unit cell (Mankosa, 2017). For example, three 100 m3 machines with three smaller motors, mechanisms and control valves could be replaced with a geometrically similar 300 m3 with a larger version of each ancillary component. While there are some efficiencies and cost improvements to be gained by this approach, it does not take advantage of fundamental insights into the flotation process, and it does not represent a step-change in terms of process design or economic benefit for the customer. The advantage of the “bigger is better” approach is that there is past experience of incremental improvements by making cells larger and there is a well-established scale-up method, which allows practitioners to estimate equipment capital costs based on very simple laboratory test- work. A different paradigm, which is gaining interest rapidly is to use a unit operation in which it is easier to optimize the flotation process, which will be described in this paper. This approach is often referred to “2- stage flotation”. Because this approach is new, it is important to benchmark it against existing conventional technology and to demonstrate a robust methodology for sizing equipment and flowsheets. This paper aims to address these issues with two case studies.

Jan 1, 2019

By W. F. James

Introduction The season of 1927, from the point of view of mining development in the area west of Rouyn, was quite satisfactory. Serious prospecting and development' were undertaken over quite a large area, though the results in the matter of discovering new deposits of economic importance were rather disappointing. A large amount of systematic prospecting and geological mapping was carried out in the course of the work, and a considerable body of information collected. A widespread occurrence of sulphide mineralization was noted, chiefly near bodies of older gabbro. The frequent occurrence of pyrrhotite in or near which local concentrations of chalcopyrite were localized, lends support to the idea that such older sulphides as pyrite and pyrrhotite are relatively easy of replacement by chalcopyrite. From the prospector's viewpoint, areas near the contacts of masses of older gabbro are favourable prospecting ground, and pyrite and pyrrhotite mineralization are favourable indications that massive chalcopyrite may be found where it has completely replaced such sulphides. Pyrrhotite being magnetic is easily located, even where drift covered, by the use of such convenient instruments as the dip-needle and the magnetometer. It is suggested that pyrrhotite bodies, when located, be thoroughly prospected because of the fairly strong probability that they may show replacement by the more valuable chalcopyrite.

Jan 1, 1928

By Ron Tessier, Claude Bazin, Robert Grant, Mike Cooper

"Grinding simulators are now widely available to assist in the optimization of industrial circuits. They provide circuit operating conditions or flowsheet designs that yield a given product size distribution. However, they do not provide information of the impact of a change of product size distribution on the subsequent flotation or leaching stages. This paper presents a method to predict grade and recovery indices for a flotation plant as a function of the flotation feed size distribution. The application of the method to various size distributions allows the determination of the optimal fineness of grind. A case study for a CuPb rougher circuit of a New Brunswick complex sulphide processing plant is presented to illustrate the method.IntroductionIs the grinding circuit product fineness optimum for the subsequent separation steps? This is a question that is certainly very difficult, but critical, to answer. Laboratory and pilot plant testworks can provide clues as to whether grind should be finer or coarser. For a full scale operation there is no other way than trying to change the setup of the grinding circuit and verify the effect on flotation. True effects can, however, be masked by the numerous and unexpected disturbances inherent to grinding and flotation circuit operations. A good preliminary investigation requires a noise free environment to elaborate possible solutions for the question.Plant simulators provide this noise free environment. However, despite grinding and flotation simulators having evolved significantly for the last 20 years, very little is available on the integration of both simulators to analyze the effect of fineness of grind on metallurgical performances. For instance, a grinding circuit simulator may help to find the tuning of a grinding circuit that will yield the desired fineness of grind, but does not inform on the effect the new product size distribution will have on the separation stages. Linking grinding and flotation would require a flotation plant simulator with the rate and infinite recovery parameters for each mineral in each size interval considered. This approach is seldom used because of the tedious work required to estimate the model parameters. Recently Leroux(1992) proposed a method to predict mineral liberation from grinding ore of known mineralogical texture. Although the method is still at its infancy it may provide, when combined with a reagent conditioning model (e.g Niemi et al., 1982; Bazin et al., 1988), a way to simulate flotation without the need of entering the numerous parameters of a flotation model."

Jan 1, 1994

By T. Negeri, M. Boisclair, A. Bouajila

CanmetMINING has been working on process development for separation and concentration of rare earth bearing minerals from various ores. Among others, the flowsheet development for the Montviel Rare Earths/Nb deposit, located at the north end of the Abitibi region in Quebec and owned by GeoMegA Resources Inc. (GeoMegA) is now at an advanced stage. The concentrate produced by a flotation-only process at the early stage of the project accounted for higher than 90% TREO and Nb recovery in 40% mass. This concentrate was submitted to SGS Lakefield for hydrometallurgical processing. Lixiviation of the concentrate using hydrochloric acid yielded approximately 99 % REE. An overall (from ore in ground to final precipitate) REE recovery of 80% was obtained through a series of selective precipitation steps. Recently significant additional developments have been made. CanmetMINING is steadily improving the quality of concentrate produced through a simplified, more efficient flowsheet which consists of flotation, magnetic separation, and a thermal treatment procedure. The paper discusses aspects of the process that allowed obtaining 82% recovery of TREO and Nb in 16% of mass, the best result to-date.

Jan 1, 2014

By C. Arson

We modeled mode I fracture in shale with an equivalent damage zone (CDM), a cohesive zone (CZM) and discontinuous enrichment functions (XFEM). In the Differential Stress Induced Damage model (DSID model) used in the continuum approach the total work input is equal to the sum of the energy released by crack debonding, the energy dissipated by crack opening, and the elastic strain energy stored in the bulk outside of the damage zone. In CZM and XFEM, the overall stiffness of the rock mass in the process zone drops as soon as the fracture starts propagating (unstable fracture propagation), whereas rock elastic properties in the CDM equivalent damage zone evolve smoothly with the displacement imposed at the boundary of the domain. In the CZM and XFEM, fracture propagation stabilizes after a turning point: this point coincides with damage initiation in the DSID model. As a result, the total energy of the rock mass calculated with CDM is about twice as large as in CZM and XFEM. The relative energy components of the rock mass are in the same order of magnitude and follow the same trends in the three models. This numerical study compares the evolution of dissipated energy potentials during mode I fracture propagation, and is expected to provide a basis to predict the amount of energy released by discrete fracture growth vs. damage propagation in the fracture process zone.

Jan 1, 2015

"An atmospheric process for the synthesis of scorodite(DMSP®)has beendeveloped,in which ferrous ions were oxidized by oxygen gas in the presence of pentavalent arsenic ions. Under optimum conditions, the synthesized scorodite (FeAsO4?2H2O) was well crystallizedand the crystals were faceted; the particle sizes were as large as 15 to 20 µm. In thisstudy, iron (II) sulfate heptahydrate (FeSO4·7H2O), arsenic (V) acid (60mass%H3AsO4) solution, and distilled water were used to prepare the original experimental solution (700 ml), in which the contents of Fe(II) and As(V) were 55.9 g/L and 50.0 g/L, respectively. The effects of various synthesis conditions, such as the type of oxidizing gas (oxygen or air), gas injectionrate, temperature, and the initial pH of the solution, on the size and shape of the scorodite particles wereinvestigated. From the experimental results, the changes in the shape of the scorodite particles wereclarified for each synthesis condition.INTRODUCTIONDOWA has developed a processfor synthesizing well-crystallized scorodite (FeAsO4•2H2O). Theprocess is named andtrademarked as DMSP® (Fujita et al., 2008; Fujita et al., 2008; Fujita et al., 2009; Fujita et al., 2009; Fujita et al., 2009, Kubo et al., 2010). In this process, oxygen gas is injectedinto a sulfuric acid solution containing large amountsof As(V) and Fe(II). Facetedscorodite crystals as large as 15–20 µm weregeneratedthrough the pre-formation of a gel-like precursor. However, it is known that the synthesized scorodite particles become smaller and more aggregatedwhen the synthesis conditionsdeviate from the optimumconditions.In this study, the effects of various synthesis conditions, such as the type of oxidizing gas (oxygen or air), gas flowrate, temperature, and initial pH of the solution, on the size and shape of the scorodite particles were investigated. The experimental resultsclarified the changes in the shape of the scorodite particles for each synthesis condition."

Jan 1, 2016

By A. Dunnett, N. J. Turner, J. Koyanagi, M. Ji

The analysis of rare earth element (REE) samples is a necessary part of the metallurgical process for rare-earth bearing ores, providing invaluable information during testing procedures. This requires a fast, multi-element technique, capable of analyzing a variety of matrices for all rare earth elements. X-ray Fluorescence spectrometry and Instrumental Neutron Activation Analysis are typically used for high concentrations of REE, but they have limitations for some process work applications due to an inability to measure all elements, longer analysis times, significant interferences and elevated detection levels. The work reported here uses new approaches with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in order to achieve high precision and accuracy within acceptable timeframes. A combination of aerosol dilution and Kinetic Energy Discrimination (KED) produce a process solution assay method that is robust enough to deal with changing sample matrices and concentrations, whilst maintaining low reporting limits and precisions of less than 5% Relative Standard Deviation (RSD). For high concentration metallurgical and geological samples, a sodium peroxide fusion digestion procedure was used, followed by ICP-MS analysis using extended dynamic range (EDR) and KED. Using these technologies, it has been demonstrated that the necessary support can be given to metallurgical process work for REE extraction.

Jan 1, 2014

By A. -I. Abenhaim, I. Sasu, C. Perron, I. Mantegh, S. Larose

Manufacturing long shafts, such as those used in turbine engines, normally involves with drilling inside them in order to take the excessive mass out. Concentricity between the shaft axis and that of the drilled hole is very crucial as it impacts the mass distribution around the axis of rotation. It is important that the shaft mass be well balanced around the central axis in order to minimise the centrifugal forces on the bearings and supporting structure as well as any unwanted vibrations. The eccentricity problem, mostly in long shafts, comes due to machining limitations. It is difficult in long shafts to maintain the concentricity tolerances while drilling inside the shaft. In this work, we address the problem of correcting this eccentricity problem, i.e., when the axis of the inside hole deviates from the central axis. The presented work is based on a threepoint bending method and investigates its effect on the residual stresses and plasticity regions induced on the shaft. A full finite element model is presented that can used to design the solution parameters (bending load, location, etc.) and predict the effect. Limited experimental results are also presented to validate the finite element modelling.

Jan 1, 2006

By James Ransford Dankwah

High sulphur carbonaceous materials like petroleum coke and rubber tyre are unsuitable as reductants in ironmaking because part of the sulphur is transferred to the reduced metal. Globally, while large amounts of petroleum coke are produced annually from the industrial processing of crude oil, billions of end-of-life rubber tyres are held in landfills and stockpiles. This work therefore investigates the potential feasibility of utilising these high sulphur carbonaceous materials as reductants in ironmaking without transferring the sulphur into the reduced metal. Composite pellets of iron oxide containing end-of-life rubber tyre (RT), petroleum coke and blends of RT/petroleum coke and petroleum coke/high density polyethylene (HDPE) were heated under argon atmosphere in a horizontal tube furnace. Reduced pellets were analysed after 10 minutes of reduction for their sulphur content. The results showed that sulphur-free metallic iron can be successfully synthesized using RT and petroleum coke as reductants. The level of desulphurisation depends on the nature of blending of the carbonaceous materials.

Jan 1, 2014

By R. D. Brown

In view of the many changes which have taken place since 1950 in the rules of the Income Tax Act concerning the deduction of exploration and development expenses, many corporate taxpayers each year face the tedious task of determining which particular rules their unclaimed exploration and development expenses are subject to and in what sequence these expenses are to be claimed. Recent amendments to the Act have cleared up some of the mystery of the "ordering" of these deductions. This article examines the sequence in which various categories of exploration and development expenses are to be deducted in accordance with the terms of the Act as amended by Bill C-11.

Jan 1, 1978

By F. G. Smith

Abstract Laboratory methods are now in use whereby the temperature and pressure during the crystallization of hydrothermal minerals can be determined. The techniques include the use of the decrepitation method of studying liquid inclusions, and electrical measurements of pyrite. The determinations are sufficiently accurate that the data can be used in solving a variety of ore deposition problems. Within the last year, several new laboratory techniques have been developed in the Geochemical Laboratory of the Department of Geological Sciences, University of Toronto. The results of several tests of ore by these methods have proved to be useful in treating some problems which previously were considered unsolvable. It is now possible to determine the temperature of deposition of most of the minerals in a hydrothermal ore deposit, also the depth below the surface during deposition. Measurements can also be made of the reopening history of a complex ore. The temperature-pressure determinations depend upon the fact that minerals deposited from a hydrothermal solution always trap a small amount of the solution at the time of crystallization. The solution, being predominantly composed of water, has a density which depends upon the temperature and the pressure prevailing during crystallization. After ore deposition is complete, erosion and isostatic uplift finally exhumes the vein. During this slow fall in temperature and pressure, the solution contracts and a gas bubble appears. If the trapped solution in the mineral is examined, the gas-liquid ratio records the density of the solution at the time the mineral was deposited (except for a slight change in the volume of the mineral). The thermal expansion and compressibility of water and water solutions are known to a sufficient degree that, if the gas /liquid ratio can be determined, the temperature-pressure relations during deposition can be calculated.

Jan 1, 1949

By W. Beres, R. E. Miller, B. Shiari, L. R. Zhao

A dynamic multiscale simulation method has been developed to study the material scratching processes on nanoscale single crystals. The model simultaneously captures the atomistic mechanisms near the free surface and the long range mobility of dislocations and their interactions, without the computational cost of full atomistic simulations. The method also permits the simulation of system sizes that are approaching experimentally accessible systems, albeit in 2D. Simulations are performed on single crystal aluminum to study the atomistic details, surface evolution, and generation and propagation of dislocations for a variety of scratching depths at room temperature. Simulations demonstrate the power of the developed method in capturing both long-range dislocation plasticity and short-range atomistic phenomena during tool advance. Variations of scratching normal and tangential forces are investigated and related to plastic deformation and dislocations generation during the simulation process.

Jan 1, 2006

By C. Bourgoin

"The limited development and application of new technologies to narrow-vein mining is currently impeding progress in the industry to a point where productivity, working conditions and operating costs have reached a critical stage in many Canadian mines.In an effort to foster the emergence and application of new technologies, Université Laval, together with other organizations, has carried out a R&D project focussed on the need of identifying new development pos5ibilities and of facilitating the transfer of technology in matters related to underground mining methods and machinery.The first phase of the study consisted of an in-depth assessment of current practices and problems in narrow-vein mining. The second phase was a state-of-the-art survey of mining methods and equipment, together with proposed modifications and innovations. The third phase of the project concerns the experimental development as well as the principal application of various proposed technologies.This paper presents an overview of the organizational, technical and strategic considerations which guided the University group and it serves as well to introduce a newly-published brochure, entitled ""Underground Mining Techniques of Vein Deposits"", which summarizes such work to date. More specifically, a perspective of technological developments applicable to narrow-vein mining is presented."

Jan 1, 1994

By Z. Liang, Z. Q. Liu, X. F. Li, H. L. Zhang

"Dynamic characteristics of frozen soil is important for the safe, effective and rapid construction in cold regions and artificially frozen engineering. In this paper, dynamic characteristics of frozen clay with various low temperature and different strain rate were studied by using Split Hopkinson Pressure Bar (SHPB) test and numerical simulation test. Variation of dynamical parameters and dynamic stress-strain curves of frozen clay were obtained and analyzed. The results of these test show that: Frozen clay exhibits temperature effect and strain rate effect that the failure type tends from plastic failure to brittle failure with the increase of strain rate or decrease of temperature; Under impact loading, frozen clay exhibits three typical dynamic stress-strain curves as strain rate increases, and the maximum strain of frozen clay only linear increases with strain rate.INTRODUCTIONArtificial freezing technology has been widely used in the construction of underground engineering, such as the coal mine shaft, the deep foundation pit, the urban metro and subsea tunnel, etc. Research on dynamic mechanical behavior of artificial frozen soil will provide supports for these artificially frozen engineering (Xu et al. 1998; Ma 2009). However, the dynamic mechanical research on frozen soil is mainly carried out at low frequencies or small amplitudes of the waves, behavior of frozen soil under impact loads or high strain rate loads has not been made clear."

Jan 1, 2015

By Dwayne D. Tannant

The Fox Pit at EKATI Diamond Mine reached a depth of approximately 150 m as of September 2005. The pit is designed with 11 m wide benches excavated using a double benching technique leaving 30 m high bench faces. A series of blasting tests were conducted to improve catch bench reliability and increase the percentage of benches that meet an 11 m catch width. The design changes focussed on reducing damage to the bench crest because maintaining the bench crests is the most important factor in achieving good bench reliability. The most significant improvement was obtained by raising the bottoms of the lower trim blastholes by 0.5 m. This change decreases the depth of broken rock below the final bench elevation, and consequently reduces damage to rock that forms the bench crest below. Another improvement was the use of smaller diameter (165 mm vs. 270 mm) blastholes in the A and B rows for the upper trim blast. This change reduces the charge per delay during detonation, reduces the powder factor slightly, and reduces the energy affecting the final pit wall and crest. As mining and the blast testing progressed, the portion of the bench with crest achievements (>11 m) increased from 57% to 75%.

May 1, 2006

By Mario Giavani

"IntroductionBy the 1980s, the continuous casting process had almost replaced the ingot casting of steel in Japan, Europe and North America. While economic benefits were probably initially the prime motivator, the transition rapidly proved that continuous casting in conjunction with ladle metallurgy offered a much greater degree of process control and made possible routine steel specifications not previously available.This new technology demanded improved procedures for the quantitative addition of the required metallurgical reagents, especially as regards the more volatile or toxic elements such as calcium , boron, carbon, sulphur, lead and tellurium. The injection of a thin steel tube containing the additive into the metal bath of a ladle refining station offers the best procedure for this. In the industry this has been referred to as ""Cored Wire "".Operators using this technology find that they are faced with balancing the injection speed against the small cross section of the tube to feed the required amount of reagent within the short time span available to the operation. Large-ladle shops requiring major quantities usually resort to multiple machines and high speeds. Many machines approach a maximum feed rate of 400 m/min. Higher speeds exceed the melting rate of the system, and the ferro static buoyancy of the tube will cause it to coil up the ladle wall and possibly resurface into the slag layer, and even eject itself above the surface. Under these conditions, exact control of element recovery becomes difficult, especially with the commonest addition, calcium silicon alloy.Many experts are persuaded that the final melting position of the carrier tube has major importance in establishing consistent element yield to the bath.For instance, the vapour pressure of calcium at l500 °C is close to I bar. Reaching a melting depth sufficient to accommodate this value is considered to be critical to achieving an acceptable and reproducible yield.Many studies have elaborated semi-empirical formulae to establish the melt zone depth, connecting this value essentially to the diameter of the tube , the injection rate and the superheat of the steel. The author's experience in steelmaking could not confirm such formulae in many cases, and he set about to develop a mathematical model which would be useful in addressing this problem, taking into account the several parameters which will regulate the behaviour of a filled tube immersed in molten steel."

Jan 1, 1991

By J. Robitaille, P. Cousin

"Agnico-Eagle Mines Ltd, Laronde Division, is a gold operation processing ore containing copper and zinc. Copper is recovered as a concentrate prior to gold cyanidation.Copper concentrate grade was improved with the implementation of an on-stream analyzer. Further improvements to the copper concentrate grade could be achieved throughefficient zinc depression.High cyanide cost linked to the copper content in the flotation circuit tails, prompted some modifications to the flotation circuit. Economics and environmental issues were considered. A Maxwell cell was retrofitted with an Outokumpu HG cell mechanism stabilizing it's operation. Secondly a flotation column was added to increase circuit capacity.This paper will address flotation circuit operation difficulties, successes and results achieved before and after modifications.RESUMELes Mines Agnico-Eagle division Laronde sont considéré comme étant un producteur d'or. Le minerai révèle toutefois des teneurs appréciables en cuivre et zinc. Un circuit de traitement combinant des étapes de flottation du cuivre et de cyanuration de l'or a été adopte. Le rejet de la flottation est lixivie pour son contenu en or.La teneur moyenne en cuivre du concentre final fut augmentée suite a l'implantation d'un système d'analyse en continu. Une séparation plus efficace de la sphalérite se devra d'être obtenue afin d'améliorer davantage la qualité du concentre produit.Le contenu en cuivre au rejet du circuit de flottation influence directement la consommation en cyanure. Pour cette raison, certaines modifications à la flottation sont devenues nécessaires. Des facteurs d'ordre économique et environnemental ont été considérées. Une cellule existante fut transformée en cellule HG d'Outokumpu, stabilisant son opération, et une colonne de flottation fut ajoutée au circuit afin d'accroitre sa capacité.Le présent document se veut une rétrospective des problèmes d'opération vécus, des solutions apportées ainsi que des résultats obtenus et de leurs implications suite aux améliorationseffectuees."

Jan 1, 1995