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Applying DEM to prediction of tumbling mill performance is challenging because several different modes of breakage are active in the process. As our knowledge of breakage and computational capacity improve, it is worth revisiting previous simulation tasks which did not produce a satisfactorily realistic description of a measured process. At SAG 2006, we reported the simulated and measured outcomes of treating a well characterised ore in a 1.2 m diameter mill. This well instrumented, pilot scale mill at the University of KwaZulu-Natal has been combined with some new approaches to ore testing to allow different modes of breakage to be tested. The mill design allows the rate of generation of fine material to be measured in close to real time for autogenous and SAG mill charges. The updated simulation model estimates mass loss with particle evolution and embeds the cumulative damage and breakage. The simulated results are compared with the measured results. Issues such as relating modelling inputs to particle breakage characterisation data and the accuracy of the predictions of the models are discussed.

Jan 1, 2012

By Jodi Wilding, Barry Lurnsden

The implementation of new technology to mineral separation operations requires rigorous testing to confirm the technology&apos;s technical and economic benefit. The Jaguar Mine owned by Jabiru Metals is located in Western Australia and sequentially separates a copper concentrate and then a zinc concentrate. Fine grinding (80% of zinc in tail is <25µm) is required to achieve efficient mineral separation. All mineral losses are therefore fine mineral losses, and so improvements in metal recovery must focus on this fine mineral. Magnetic aggregation technology has been shown to increase the recovery of fine paramagnetic minerals so it was an appropriate technology to evaluate at Jaguar. Testwork commenced in the copper circuit and it was found that there was a substantial reduction in copper in copper tail and an increase in zinc recovery to the zinc concentrate. The increase in zinc recovery in the latter zinc circuit was an interesting result and initiated the second stage of testwork that was to install and test a second magnetic conditioning unit in the zinc círcuit. This showed a further increase in zinc recovery. Magnetic conditioning technology has now been fully evaluated in the plant and is now part of the Jaguar flowsheet.

Jan 1, 2011

By Donald F. MacDonald

THE cement plant nearest to Nova Scotia is not far from Montreal. Cement is a heavy product which, because of its relatively low value, cannot stand a high freight charge without unduly enhancing its cost. This is one reason why cement costs are high in Nova Scotia. The regular retail price per bag (8772 lb.) in Antigonish is 85 cents, which would be $3.40 per Canadian barrel of 350 pounds, or $3.65 per American barrel of 376 pounds.It is said that the lowest wholesale price in Halifax is 65 cents per sack, which would be $2.60 per Canadian barrel or about $2.80 per American barrel. According to U.S. Bureau of Mines statistics, the average factory price for cement in 1937 was $1.48 per American barrel, which is practically the same as the value per barrel indicated in Dominion statistics for the Canadian output during that year. The difference between $3.40 and $1.48 is $1.92. It is evident that the average user of cement in the Mari-times pays a stiff premium because Maritime cement raw materials have not been developed. Rock-wool, the manufacture of which is rapidly increasing in Ontario and the United States, is much needed for building insulation in the cold climate of Nova Scotia.

Jan 1, 1939

By M. A. Hararah, T. Neesse, M. G. Farghaly, G. Proellss, P. Kaniut, W. Rubarth

ABSTRACT: This paper presents two new options for hydrocyclone control. Volume split control using a control valve in the overflow is applied for the stabilization of separation results at changing feed conditions. Controlled water injection to the conical part of the cyclone leads to the reduction of fine particles in the underflow. Hydrocyclone monitoring in both cases is performed by optical sensors that indicate the spray angle of the underflow. Applications in mineral processing for desliming, classification in closed-circuit grinding, and dewatering are demonstrated.

Jan 1, 2011

By Hans Lundberg

An electric survey from a &apos;plane flown over the ground is much faster and cheaper than an electric survey carried out on the ground. The results are obtained as continuous recordings that are resolvable into both a depth expression and a conductivity effect, so that the indications are easier to evaluate, as well as to correlate from one flown line to the other. The prospecting technique adopted in our electric airborne surveys may be brie fly described as follows: A loop of many turns of insulated copper cable is fastened around the fuselage of the &apos;plane and connected to a generator supplying a few ampere alternating current, usually of a frequency less than 1,000 cycles per second. Just as the current in the primary coil of a common transformer will induce current in the secondary coil when shorted, the alternating magnetic field from this primary current now induces alternating current in electric conductors that happen to be located in the vicinity of the path over which the &apos;plane is flown. This induced secondary current in each conductive section of the ground causes, in turn, an alternating magnetic field, secondary field, which disturbs or dampens the normal alternating magnetic field from the primary loop flown by the &apos;plane. These secondary fields are then picked up and recorded by the help of detecting solenoids, amplifiers, and recorders carried in the &apos;plane. By closer study of such a secondary field it is possible to localize the secondary current causing it and, thereby, the conducting body that contains the secondary current. In the &apos;plane are continuously recorded, besides the amplitude or intensity of the field, also the phase, which is a measure of how much the recorded secondary field is out of step with the primary field.

Jan 1, 1950

By A. Lopez-Valdivieso

Particle size enlargement processes play an important role in solid/liquid separation, and in beneficiation unit operations. In the latter, not only the size of the formed aggregates but also their surface properties are very important. Oil agglomeration has a special place among such processes: it is a selective process in which hydrophobic particles are agglomerated into hydrophobic agglomerates which can be recovered by flotation. This explains the broad applications of oil-assisted beneficiation processes not only in the beneficiation of fine coal, but also in agglomerate flotation of many different types of ores, and in coal/gold agglomeration.

Jan 1, 2004

By H. C. M. Gordon

IT is essential to the success of any mining op::ration that the roadways through which the material wrought and ocher materials and supplies are to be transported should be kept in such condition that this transportation cart be effected rapidly and without difficulty. The longer the roadway and the greater the tonnage to be taken over it, the more necessary it becomes chat the construction and maintenance of the road be such chat traffic delays can be reduced co a minimum. le is proposed co deal with the development and construction of roadways serving longwall operations and, since a recreating system of longwall is worked, as a rule, only where roadways driven in the solid coal can be readily maintained, the discussion will be confined co advancing longwall roads which are driven through areas from which the coal seam has been totally extracted. In order to construct a roadway through extracted ground in such a manner that it will remain in a state of reasonably good repair without undue maintenance, it is necessary chat everything possible be done to bring the overlying strata co a state of equilibrium as quickly as this can be effected, and the operations should be so planned that future workings will not disturb the equilibrium so set up more than can be avoided. Obviously, the readiest way to obtain a stable roadway is to develop it by tunnelling through a settled waste. However, this cannot always be done, as some of the roadways must be developed and constructed as the walls progress, but level or lateral cut-offs can be constructed in this manner. Main-slope roads can be developed in a similar manner after the coal has been extracted and a waste formed for at !east five hundred feet on either side of the line of the permanent roadway from temporary subsidiary roads developed for this purpose along one or other of the flanks of the waste to be formed. This interval must be obtained in order chat the lacer extraction of the seam will not set up movements in the waste immediately overlying or adjacent to the constructed roadway, thus upsetting the equilibrium of the strata and distorting the road.

Jan 1, 1940

By Robin Belley

Outline Introduction Wabush Mines HistoricalBackground Mine and Concentrator at WabushMines High Intensity Magnetic Separators (HIMS) Development of the Manganese Removal Process Pilot Plant Testing Phase Manganese Removal Line 1 Coming Phase: Manganese Removal Line 2 Manganese Concentration Process Development Historical Background 1847: Creation of the Cleveland Iron Company1850: Opening of its first iron ore mine in the Upper Peninsula of Michigan 1965: Beginning of Wabush Mines at Scully Mines, Wabush, Labrador. 1980-1990: Questions raised about how to exploit Scully high Mn Ore (> 2%)Part of the available ore is not saleable due to too high a level of pyrolusite (MnO2) Adding this ore to the resources would be valuable (longer mine life and lower stripping ratio) 1990s: Testwork for Manganese removal Many different processes are studied over more than a decade High Intensity Magnetic Separators (HIMS) are identified as the best technology for Mn removal 2007: Pilot Mn removal line installed Testing carried out through 2007-2008 First Production Line is ordered (2008) 2009: Cleveland Cliffs (now Cliffs Natural Resources)acquire the remaining part of Wabush Mines 2010: Mn Removal Line 1 construction & commissioning Summer 2011: Mn Line 2 Construction

May 1, 2011

By R. Argane

In this work we assessed the geochemical behavior of concentrator tailings deposited at the abandoned mines of Zeida and Mibladen (Upper Moulouya, Morocco), using physico-chemical analyses, mineralogical characterization, acid base accounting and weathering cell tests. The aim of the study was to evaluate mine drainage quality and to assess metal mobility from these concentrator tailings. Chemical analyses show that the Upper-Moulouya abandoned tailings contain relatively high quantities of lead (0.261 to 0.594 % wt). Mineralogical analyses reveal the abundance of neutralizing minerals (calcite, dolomite, ankerite, and aluminosilicates) which influence mine drainage and metal mobility in mine tailings. Leachate analyses from weathering cell tests show alkaline conditions, small conductivity values, and low solubility of Pb-mineral phases. According to these results, abandoned mine tailings in the Upper-Moulouya district have very low potential for generation of contaminated mine drainage and for leaching of heavy metals. However, the inhalation of tailings exposed to winds generate dust problem facing the local population and may cause health consequences.

Aug 1, 2013

By Martin Bouchard, Bruno Paillard, Jean-Claude Dubé, André L’Espérance

"A precise analysis of the noise emitted by an aluminum plant has shown that one of the main sources of noise is the noise emitted by an exhaust stack 40 m high and 1.8 m diametre, emitting a pure tone at 320 Hz. Because a classical cost effective solution is not available for this source, active noise control (ANC) solution was investigated.Commonly available ANC systems, how-ever, are not applicable to the chimney considered because the diameter of the stack (f) is too important compared to the wave length(?)of the frequency to control. In fact, until now, active noise control (ANC) has been successfully used to reduce the acoustical energy emitted at the end of ducts in the case of plane wave propagation, i.e. ?/f< 1.7 [1,4].When f> ?/1.7, high order modes propagate in the duct and a single canal active noise control system is not sufficient.This paper presents an ANC system developed to control higher modes in a circular duct. The controller used is based on a multiple-input, multiple-output adaptive filtered X-LMS and allows up to 11 error micro-phones and controls sources. The system has been used in a laboratory on a finite duct of3.5 m long and 0.30 m diameter which corresponds to the same ratio ?/f for the real stack. The efficiency of the system with different numbers and location of control sources and errors sensors has been analyzed. Noise reduction of 15 dB(A) could be obtained with some configurations. Actually, the system is being considered for installation on the real chimney stack."

Jan 1, 1997

By E. Lee Cameron

The old mine workings on four barite-fluorite veins of the Lake Ainslie district, Nova Scotia, were opened recently and channel sampled. The samples were then forwarded to the Ore Dressing Laboratories, Bureau of Mines, Ottawa, for chemical analyses. Following the analyses, the sample rejects were combined to form bulk samples, representing ore from each vein, for small-scale batch test work. Tonnage samples from the veins, for pilot mill testing, were submitted when requested by the Bureau. The results of the analyses on the channel samples showed that there are two grades of ore in the di strict, represented, for test purposes, by the Trout River vein and Johnson vein ores. Small-scale and pilot-plant test work was undertaken on both these ores. The Trout River ore is amenable co concentration but, because of the high-barite-co-fluorite-co-calcite ratio, a fluorite concentrate was not obtainable from the Johnson vein ore as received. However, Johnson ore blended in a 1 :1 ratio with Trout River ore gave a mill feed that was readily concentrated. The test work on these ores showed that the following concentrates are obtainable : (a) A barite concentrate, with a recovery of 85 to 95 per cent of the available barite, analysing 93 co 96 per cent BaS04, 4 co 6 per cent CaF,, and 0.5 co 2 per cent CaCO3. (b) A fluorite concentrate, with a recovery of 80 co 85 per cent of the available fluorite, analysing 94 to 97 per cent CaF, , 1 to 3 per cent BaSO., and 1 to 3 per cent CaCO3

Jan 1, 1945

"Dry crushing trials at pilot scale have shown that the IMPTEC Super-fine Crusher has the capacity to generate ultra-fine products from hard mineral assemblages presenting at either coarse or fine feed sizes. The super-fine crusher was introduced at the 27th International Mineral Processing Congress in Santiago Chile, with results from a range of duties, which demonstrated the crusher’s potentially expansive operating scope. This paper focuses on current preparations to progress the technology from pilot scale to commercial scale within a concrete production plant, where lead blast furnace slag will be crushed to ultrafine sizes to generate an active silica product for use as a supplementary cementitious material, which can replace Ordinary Portland Cement. A key objective of the operation is to demonstrate an economical route to reducing the cost of concrete production, improving concrete quality and reducing greenhouse gas emissions. The paper also highlights the potentially key contribution super-fine crushing can make to the long-term viability of iron ore beneficiation by simplifying comminution flow-sheets and reducing operating costs. There is every indication that the technology has the potential to feature universally in metalliferous and industrial mineral flow-sheets. INTRODUCTIONToday’s IMPTEC super-fine crusher is the successful end product of development work over 19 years and is the third particle size reduction device conceived, built and tested over that time. The concept evolved as engineering design progressively developed a mechanism capable of harnessing a highly efficient combination of fundamental particle breakage mechanisms. Early development trials at pilot scale indicated that super-fine crushing had the potential to establish a wet or dry, media free, low energy route to ultra- fine products from hard mineral assemblages. Having achieved some impressive results from open circuit pilot tests on fly ash and granulated blast furnace slag it became clear that the cement industry may well provide opportunities to apply the technology commercially. Following expressions of interest from local cement and concrete plant operators, IMPTEC negotiated an agreement to undertake commercial trials with a SFC 350 super-fine crusher installed on site at a concrete supply plant in South Australia. Super-fine crushing scope was recently expanded following further expressions of interest from research groups involved in the processing of iron ores. Pilot trials are progressing in these areas."

Jan 1, 2016

By D. Sancho, M. Weber

"At the start of a new shaft project, a specific number of ground investigations are performed. However, it is not uncommon that the ground conditions during shaft sinking may differ from the designed ones. Therefore, it is extremely important to use tools which minimize discrepancies and to include a monitoring system in the shaft design to collect sufficient data. The paper presents an overview of existing monitoring techniques and discusses future works required to improve, not only the construction during shaft sinking, but also the lining design methodology. INTRODUCTION In most cases, the investigations performed at the start of a new shaft are based on the analysis of rock and soil probes obtained from boreholes. In practice, such analysis performed on a single core often leads to different results when conducted by various experts. The discrepancy in core analysis influences further rock mass assessment and design assumptions. It is not uncommon that the ground conditions during shaft sinking may differ from the designed ones, which affects the estimated stress and strain state of the shaft lining. Therefore, it is extremely important to use tools which minimize such discrepancy and to include into the shaft design a monitoring system to collect sufficient data, which enables control of important phenomena, not only during shaft sinking but also during the life of the shaft. Furthermore, the information collected during shaft sinking, while it is important for proper shaft lining design and updates to the shaft lining due to the local mining and geological conditions, it is also important after shaft sinking. In the whole shaft lifetime, it is not uncommon that the shaft lining is damaged and the liner needs to be renewed (Figure 1) due to various reasons. For this purpose, detailed information collected during construction can be extremely important."

Jan 1, 2019

By S. Shairp

At the Hudbay zinc pressure leach plant, filtration and washing of the second stage leach slurry takes place on a vacuum belt filter prior to disposal to tailings. Due to periods of poor filterability, laboratory studies were undertaken to investigate the effect of temperature of the filter feed slurry, and to compare filterability to the resulting cake particle size distribution.

Jan 1, 2014

By W. I. van Drunick

The Anglogold Ashanti (AGA) Navachab single stage SAG mill has provided an excellent setting for incremental optimization. Over the past decades, several interventions have resulted in marked improvements in specific performance; including steel ball scat removal, re-design of the mill lifters, replacement the pebble crusher and cyclone cluster, as well as the use of a vibrating screen in place of a discharge trommel. Recent initiatives now include an operating fine DMS circuit, studies on pre-crushing of the ROM feed and also fine-screening as an alternative to hydrocyclone classification. The current optimized state of the Navachab mill allows it to operate at approximately 20% higher efficiency when compared to mills of similar shell dimensions in gold mining, treating similar ore. This paper describes the systematic improvement of the SAG circuit to its current state.

Jan 1, 2012

By H. J. McQueen

Aluminum was hot worked at 400 - 500°C and strain rates (e ) of 0.004 -0.1s-1, under reversing strains (c) of 0.5 to 0.2 or 0.5 to 0 and also advancing from 0.5 to 1 or 0.5 to 5. Under similar test conditions for different parts of the strain paths, the average measured flow stresses are found to agree with each other. In the forward and backward strain path tests, the almost identical steady state plateaus affirm the occurrence of dynamic recovery (DRV). On reversal of strain direction at constant e , there was generally negligible Bauschinger effect. In specimens annealed at 400°C, static recrystallisation (SRX) was followed microstructurally. mainly by disappearance of elongated grains with serrated boundaries because the new grains were only little a finer than the old due to low strain energy. The only influence of reversing strain path observed was the effect of change of grain boundary area as grains elongated or returned towards equiaxed. In optical microscopy, elongated grains with serrations and deformation bands confirmed DRV in forward path specimens. In reverse path specimens, equiaxed grains were gradually restored with retention of serrations and bands. In low magnification polarized optical microscopy, grain alignment increased with strain for forward path specimens; whereas it decreased in reverse path ones, supporting DRV. Orientation imaging microscopy (OIM/SEM) revealed that elongated grains are broken up as deformation bands rotate during the forward path and that grains return to equiaxed appearance on backward straining. Comparative studies using optical microscopy in polarized light (POM), OIM/SEM and transmission electron microscopy (TEM) revealed that while subgrains remain equiaxed and constant in size and character during the forward and backward paths, the fraction of low angle facets decreased while that of high angle grain facets increased with increasing strain; these are coupled with a fairly low fraction of medium angle boundaries. The results contribute to the understanding that dynamic recovery in aluminum maintains sub-boundaries with low misorientation but as grains elongate and more subgrain become adjacent to grain boundaries the fraction of high angle boundaries rises (with backward straining it was vice versa).

Jan 1, 2007

By D. Song

In this paper, the differential equations governing the mass transport and the electrochemical reaction in a cathode catalyst layer of polymer electrolyte membrane fuel cells are solved based on the polynomial series expansion method. Explicit expressions for the polarization curve as well as for the distributions of oxygen, current density and overpotential are obtained when a quadratic, cubic or quartic polynomial is employed to approximate the oxygen concentration distribution. These kinds of explicit solutions are desirable for MEA design and diagnosis purposes. The comparison between the conventional numerical approach and the explicit solution approach proposed here shows that satisfactory accuracy can be reached by the first four terms of the polynomial series. The effect of the catalyst layer thickness on the accuracy of the obtained explicit polynomial solutions is also discussed.

Jan 1, 2005

By David Sanscartier, Elizaveta Petelina, Alexey Klyashtorin

This paper provides an overview of the radiological risk mitigation approach applied by the Saskatchewan Research Council (SRC) for the remediation of 35 legacy uranium mine sites in northern Saskatchewan where uranium exploration and extraction took place in the 1950–60s. Mining activities resulted in an irregular increase of the gamma radiation dose rate (up to 18 μSv/h). The radiological objectives for the sites include a gamma dose rate at a spot (<2.5 μSv/h above local background), and the dose rate averaged over a hectare (<1 μSv/h above local background). These objectives are generally achievable at the impacted sites through the installation of shielding soil cover. This method may be impractical for site areas with rough terrain (e.g., steep slopes) and/or difficult access. A risk assessment approach is applied to determine if these areas can be safely left uncovered or if additional mitigation measures should be implemented. The risk assessment approach is based on two factors: (i) the ambient radiation dose rates collected through gamma surveys, and (ii) actual land use data collected through various surveys of activities of local community members at the sites. Exposure scenarios based on four land uses are applied to estimate a potential annual dose load for members of the public. The estimated doses are compared with the criterion of 0.3 mSv/a recommended by the Canadian Guidelines for the Management of Naturally Occurring Radioactive Materials (NORM). If the criteria are not satisfied, a mitigation plan is developed, and post-remediation gamma levels are modelled using GIS tools to evaluate the performance of the proposed mitigations. The proposed approach allows the team to optimize resources for the site remediation so that public exposure to NORM are as low as reasonably achievable after remediation.

Jan 1, 2020

By L. Tikasz

The primary purpose of ore hauling model studies is to capture the variability of the ore delivery ? stockpiling process in order to improve the estimation of equipment capacities and achievable throughputs. The operation of a mine-to-site ore delivery system is the subject of a number of challenges. Typically, ore is hauled by a given combination of trucks, conveyors and trains. In addition, ore loading, ore transferring to another means of delivery, stockpiling, reclaiming, and further deliveries involve many other types of equipment. The concurrent operation of all these units is scheduled; nevertheless, they are subject to planned maintenance and random breakdowns. To support our engineering design work on ore hauling operation, discrete event type models were built for each specific task. Then, due to recurring demands, an ore hauling library was gradually compiled. The now available model library allows fast and efficient simulation of various mine-to-site hauling arrangement, adaptable to various mining and mine construction operations (e.g. bauxite, iron ore, copper ore and coal).

Aug 1, 2013

By Yves Bellemare

Entre 1983 et 1997, l'exploitation de la pierre de taille au Québec a été marquée par l'émergence et la consolidation de plusieurs nouvelles variétés de granit, provenant exclusivement ou presque de la Province de Grenville. Le Québec demeure toujours le principal expéditeur canadien de granit dimensionnel, avec des expéditions annuelles représentant près de quatre-vingt-dix pour cent des expéditions totales canadiennes de granit brut et transformé. La production annuelle de granit brut oscille, depuis 1994, autour de cent mille tonnes métriques. Cette production a plus que doublé de 63 000 à 140 000 tonnes métriques entre 1981 et 1990, mais elle a connu une chute importante en 1991 (67 000 tonnes métriques); cependant depuis 1994, elle est en forte progression (Ménard, 1998). En 1983, le granit dimensionnel était extrait de plus de vingt-cinq carrières, dont les trois quarts se localisaient dans la Province géologique de Grenville. Comparativement, en 1997, le Québec comptait trente-sept carrières actives, dont trente-cinq dans le Grenville (Gaudreau et al., 1998). Cette concentration des carrières dans la Province de Grenville s'explique par la demande accrue de nouveaux produits au fil des ans et par le potentiel élevé de découvertes de nouvelles variétés dans cette Province géologique. L'accessibilité au territoire, toujours plus grande, a facilité la mise en production de carrières favorisant la diversification des produits. Le ministère des Ressources naturelles du Québec (MRNQ) a consacré depuis 1980, beaucoup d'efforts dans la recherche de nouveaux gisements et de nouvelles variétés. En plus des programmes de subvention destinés aux prospecteurs ou aux compagnies, le ministère a réalisé des campagnes d'inventaire de pierre de taille, de pierre concassée et de pierre d'enrochement pour en connaître le potentiel géologique et à orienter les recherches futures (Nantel, 1983; Nantel et Martignole, 1991; Bellemare, 1995a, b, c, d, e, f, 1997, 1998a and b; Bellemare et Petryk, 1996a, b, c and d). Cette étude donne un aperçu des différentes variétés de pierres extraites dans la Province de Grenville entre 1983 et 1997, les situe dans leur contexte géologique et en localise les principales régions productrices. Elle est une suite à l'article publiée par Nantel (1984).

Jan 1, 2001