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By Mark Sherman

One of the main functions of a process technology and engineering services provider is to select grinding equipment that will meet the client?s throughput rate target. Prudent risk mitigation strategies would suggest that throughput rate estimates be cross-checked using a variety of techniques. Whilst some comminution circuit designers have estimated specific energy requirements via the manipulation of the Bond specific power equation e.g. Barratt?s Grindpower and OMC?s FSAG approach, other designers have opined that the Bond Indices have no role to play in the calculation of SAG mill specific power. As a result, they have developed their own specific energy estimating methodologies, e.g. SMCC?s Drop Weight based power methodology, SPI, SAGDesign, etc. Each method has its supporters and its critics. The challenge facing the engineering provider is how to nominate an SAG mill based circuit throughput rate estimate when faced with significantly disparate specific energies calculated by the different methodologies. This challenge is exacerbated via the continuing evolution of contemporary circuit configurations such as two stage pebble crushing some of which incorporate HPGR technology as the second stage of pebble crushing. The methodology presented in this paper shows that the Bond Indices are an excellent tool for estimating the specific energy requirements for SAG mills in SAB, SABC and SSS circuits. The method accommodates primary crushed feeds, partial and or fully secondary crushed SAG mill feeds, and emulates the impact of pebble crushing on SAG specific energy. As a result, the new Bond Index based method has provided an additional tool for increasing Fluor?s confidence when predicting SAG mill based circuit throughput rates. Based on this outcome, the author proposes that the decades old conundrum of using Bond Indices to calculate SAG specific energies for SAG mill based circuits has been solved.

Jan 1, 2012

By D. J. Charlton

"IntroductionMaintenance is a business, which to be successful, requires good management, systems and reporting. The prime objective of the maintenance management group, be they large or small, must be to anticipate and prevent interruptions in operations by keeping equipment in good mechanical condition. This objective should be carried out at minimum cost consistent with maximum productiveness.The objective of this chapter is to give an insight into the various aspects of maintenance management that must be considered to effectively and efficiently operate a mill complex. The degree to which the maintenance sub-systems are developed in an operating mill will be determined by the size of the mill and the needs of the operation.The criterion of the management system used is that the system serve the operation and not vice versa. The systems presented should be considered as tools and, as with all tools, they must be sharpened and replaced as the need arises or as more effective tools become available.To understand what is involved in maintenance management, it is worthwhile to consider a systems approach to analyzing management problems. This approach was developed by J.A.B. Rae while reviewing maintenance management systems for Cominco Ltd.A very simple system involving managing results and objectives is shown diagrammatically in Figure 1.The systems approach to organizational development involves four basic elements: an objective, a result, an activity and feedback. In the analysis, the activity element is broken down into individual actions that people could be held responsible for. If we introduce the action of operating into the diagram of Figure l, we arrive diagrammatically in Figure 2."

Jan 1, 1989

"The main purpose of geometallurgy is to develop a model to predict the variability in the mineral processing performance within the ore body. Geometallurgical tests used for developing such a model need to be fast, practical and inexpensive and include as an input data relevant and measureable geological parameters like elemental grades, mineral grades and grain size. Important in each geometallurgical program is to define the number of samples needed to be sent for geometallurgical testing to enable reliable metallurgical forecast. This is, however, a complicated question that does not have a generic answer.To study the question on sampling a simulation environment was built including a synthetic ore body and sampling & assaying module. A synthetic Kiruna type iron oxide - apatite deposit was established based on case studies of Malmberget ore. The synthetic ore body includes alike variability in rock types, modal mineralogy, chemical composition, density and mineral textures as its real life counterpart. The synthetic ore body was virtually sampled with different sampling densities for a Davis tube testing, a geometallurgical test characterising response in magnetic separation. Based on the test results a forecast for the processing of the whole ore body was created. The forecasted parameters included concentrate tonnages, iron recovery and concentrate quality in terms of iron, phosphorous and silica contents.The study shows that the number of samples required for forecasting different geometallurgical parameters varies. Reliable estimates on iron recovery and concentrate mass pull can be made with about 5-10 representative samples by geometallurgical ore type. However, when the concentrate quality in terms of impurities needs to be forecasted, the sample number is more than 20 times higher. This is due to variation in mineral liberation and shows the importance of developing techniques to collect qualitative information on mineral and ore textures in geometallurgy."

Jan 1, 2016

By Denis Bois

La Bolivie est un pays en développement qui compte une tradition minière qui précède même l?établissement espagnol en Amérique. Pendant toutes ces années, l?exploitation minière s?est faite sans grands égards pour l?environnement. Au cours des dernières années cependant, le gouvernement bolivien a modifié ses lois afin de rendre nécessaire la prise en compte de l?environnement dans le processus d?exploitation d?une mine. Dans le cadre d?un projet MRN-ACDI1 visant à renforcer le secteur minier en Bolivie et ses retombées pour la population, l?URSTM2 a été mandaté pour développer et mettre en place un programme académique de gestion environnementale minière, basée sur l?expertise canadienne. Ce programme vise à renforcer les institutions académiques boliviennes responsables de la formation en environnement minier en Bolivie ainsi que les ministères et agences gouvernementales concernées.

May 1, 2001

By H. E. Lake

VERY EARLY in the initial stages of underground development work at Eldorado's Beaverlodge operation, the decision was made to use mill tailings as a backfill product. Mining and milling commenced in June, 1953, using locally available sand as backfill, while test work and installation of a plant was carried out to prepare ?and deliver the tailings to the mining areas. The first use of tailings was made in February, 1954, a sandslime separation being carried out with hydraulic cyclones. To date (January. 1956), approximately l 40,000 tons of fill have been used in the stoping areas, providing very effective support in a 50 deg. Vein system of cut-and-fill mining. The recoverable portion of the mill tailings amounts to 40 to 45 per cent, which has resulted in a product giving a percolation rate of 6 to 10 inches per hour. Owing to the fact that Eldorado has milled from 15 to 2 5 per cent more ore than it has mined, through the purchase of custom ore, the degree of control on the sand-slime separation has not been as critical as it might normally be when the filling operation must depend only on the tailings from ore mined. A description of the conditions involved and of the plant as finally installed is given below. It might be mentioned here that, with the impending increase in milling capacity from 700 tons to 2,000 tons p.er day, the present plant will be considerably altered within the ensuing year to handle the increased tonnage and distribution.

Jan 1, 1956

By Mayumi Ito

Mineral processing of rare-earth ore from the Dong Pao deposit, Vietnam, was investigated. The ore contained bastnaesite, (REE (rare earth element)) CO3F, as the valuable mineral and barite, quartz, and fluorite as gangue. To establish a mineral processing flowchart, selective comminution, size classification, and magnetic separation were tested. Bastnaesite shows brittle properties and selective comminution was applied to improve the purity of products. The crushed products were classified by decantation, and the overflow product showed high purity of bastnaesite indicating that bastnaesite becomes fines by crushing and that selective crushing can be used to concentrate the bastnaesite. Magnetic separation for the sink product was carried out and the mag-product showed high recovery rates of bastnaesite, indicating that the combination of size classification and magnetic separation is effective.

Aug 1, 2013

By D. H. Schwarz

The performance of proton exchange membrane (PEM) fuel cells depends on catalyst layer composition and structure. Experimental observations reveal that state-of-the-art catalyst layers consist of microporous agglomerates of carbon-supported catalyst sites bound together by polymer electrolyte. In between the agglomerates are macropores which provide pathways for the transport of gaseous reactants. In this work, three-dimensional, multicomponent and multiphase transport computations are performed using a computational fluid dynamics (CFD) code (FLUENTTM) with a new PEM fuel cell module, which has been further improved by taking into account the detailed composition and structure of the catalyst layers using a multiple thin-film agglomerate model. In this model, it is assumed that thin films of polymer electrolyte and liquid water surround the catalyst sites. The results of CFD computations show that transport limitations associated with the thin film of polymer electrolyte and the presence of liquid water in the catalyst and gas diffusion layers have substantial negative effects on PEM fuel cell performance. Also, the results of computations with variable distributions for a given precious metal loading show that, in general, uniform catalyst loading provides the best fuel cell performance.

Jan 1, 2005

By E. H. Chown

Scattered outliers of the Chibougamau Formation and the more continuous Mistassini and Otish Groups lie unconformably on an Archean basement abutting the Grenville Front. All the Aphebian rocks are deformed and offset by faulting related to the Front. The older Chibougamau Formation is exclusively elastic in origin, whereas the two later, time-equivalent groups include carbonatedominated (Mistassini) and elastic (Otish) sequences. Known syngenetic mineralization within these formations is limited to various radioactive showings in the Mistassini and Otish elastics, and the iron formations of the upper Mistassini Group. Three distinct types of epigenetic mineralization occur within the sedimentary rocks; pitchblende fracture fillings in all types of rocks in the Otish Group, widespread Mississippi-Valley type galenasphalerite showings at certain levels in the Mistassini Group, and chalcopyrite-pyrite bearing veins in or near argillaceous horizons of the Mistassini Group and Chibougamau Formation. The Otish elastic basin is part of a large area of the central Ungava peninsula which contains a variety of radioactive showings, the most promising being of the unconformity type, The final control for many individual showings appears to be local physico-chemical changes within faults and fracture zones. The overall structural control is in part supplied by the faulting episode related to the Grenville Front, which in turn limits the mineralization to the depth zone appropriate for open fracturing. The lead-zinc showings exhibit a strong stratigraphic control as well as close ties to secondary porosity developed by f aulting. The ore solutions were probably derived during the low grade metamorphism of the formations. Chalcopyrite- pyrite veins have provi ded the only mine production (Icon Mine) to date. They appear later than the low-grade metamorphic fluid circulation, and deposition is related to favourable structures and stratigraphy. The veins are clearly related to major faults. Thus, whereas stratigraphic settings appropriate to individual types of deposits are important, an overall structural setting may be demonstrated for a wide range of mineralizations. Detailed structural interpretations of individual showings may be the most fruitful pursuit in developing a concrete prospecting model.

Jan 1, 1984

By A. M. Bell

"Hallnor mine is in the township of Whitney, Porcupine district. To date, its production of gold has been second largest in the east Porcupine field. Ore was discovered in the property in 1936 by diamond drilling in overburdened country. This drilling was undertaken by Noranda Mines following the discovery of ore in conglomerate at Pamour 1 mile to the east.Milling commenced at the Hallnor in June 1938, and to the end of 1945 432,000 oz. gold had been produced from 889,000 tons of ore, giving an average recovery of 0.49 oz. a ton.The West mine of Pamour, the Broulan orebody, and the veins on the Hallnor and Bonetal are all parts of a mile long vein system that has been separated into three sections by cross faulting. In consequence, they could well have been described in one paper. In treating them individually the viewpoint obtained from each may lead to conflicting opinions, and any conclusions advanced in this paper on the general structure should be modified by the conclusions advanced in papers on the neighbouring properties.GENERAL GEOLOGYRock FormationsThe Hallnor orebodies occur within 400 feet of the contact between lavas and sediments, and may lie in either lavas or sediments. The lavas near the ore consist of flows of pillowed andesite and one flow of more acid and less sheared and chloritized lava locally named trachyte. These flows strike east-west and dip steeply. At the surface on the east side of the property the volcanics have been intensely altered to a massive carbonate rock having a north-south thickness in excess of 1,000 feet . This carbonate body extends west across the property with a plunge of 45° (Fig. 1)."

Jan 1, 1954

By C. A. Lorenson

THE Marmoraton mine is located a mile southeast of Marmora, a village in Hastings county, Ontario, 130 miles east from Toronto and 143 miles west of Ottawa. Highway No. 14 from Belleville intersects Highway No. 7 at Marmora and the branch line of the Canadian National railway between Trenton and Bancroft passes through the property just east of the open pit. HISTORY AND GEOLOGY The Marmora orebody appears as the whorls of a thumb print on the aeromagnetic survey map released by the Ontario Department of Min.es early in 1950, the survey of the district having been made in 1948 and 1949, under the joint auspices of the Department of Mines and the Geological Survey of Canada. The 'anomaly' appeared to have interesting possibilities, so Bethlehem representatives carried out a ground survey and began drilling the property in June, 1950. A total of 40 holes, aggregating 37,000 feet, were drilled to delineate the ore-body. The Marmora orebody is a re-placement of Precambrian limesto.ne with zones or bands of magnetite interlaid with metamorpl1ic rocks and cut by later intrusives. The ore and associated Precambrian rocks are overlain by 100 to 150 feet of flat-lying Palaeozoic limestone. It is a low-grade deposit averaging 33 per cent iron and requires concentration to raise it to 65 per cent iron grade.

Jan 1, 1958

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 G. Beckstead, L. Gormely, R. Zimmer, K. Hanneman, B. Nethery

As part of the EIS and permitting activities for the Pogo Mine in Alaska, a risk assessment study for the water management plan was carried out. The basis for the study was a site water volume and contaminant balance model. Probabilistic modeling was carried out using the @Risk Monte Carlo simulation package to investigate the frequency, quantity, and quality of discharges under varying assumptions. The results were used in discussions with regulatory officials as part of the permitting process for the project. The simulation allows probabilistic modeling of key environmental parameters based on input frequency distributions involving both quality and quantity of flow. When combined with predictions of water treatment plant capacities and removal efficiency, this was very useful for defining the likelihood of important regulatory outcomes. Based on the model, certain project modifications were made. Using the simulation as a basis, ongoing dialog with regulators led to consensus that all potential risks have been considered and mitigated for the Pogo Mine according to their likelihood and severity, and that regulatory requirements would be achieved. The paper describes the model and some of the applications for which it was used.

Jan 1, 2005

By D. F. Sherwin

"THE AREA which is described in this paper (Fig. 1) includes the continental margin of eastern Canada extending from the Gulf of Maine to the north edge of the Grand Banks, which, including the continental shelf, slope and rise, comprises an area of about 600,000 square miles. The paper is intended to give a background of the geological setting of this region in the context of its ultimate potential for oil and gas reserves in close proximity to the Nova Scotia energy market.HISTORY OF EXPLORATIONThe history of geological exploration of this area really began in 1878, when U.S. fishing boats brought back samples of rock recovered in trawls from their expeditions to the long-famous fishing banks off Canada's East Coast. Tertiary and Cretaceous fossils recovered from these samples indicated that the eastern Canadian continental shelf was actually the submerged northern extension of the Atlantic Coastal Plain."

Jan 1, 1972

"HPGRs operate in a wide array of applications in mining and minerals. These range from relatively coarse crushing of copper and gold ores at one end of the spectrum to the processing of fine iron ore pellet feed and fine industrial mineral products at the other. Traditionally these circuits involve the treatment of relatively moist materials in pre-grinding circuits; using single stage HPGRs in open circuit or as a closed circuit operation with screening or partial product recycle. More recently, HPGR is increasingly deployed in dry grinding in combination with air classification. The high throughput demonstrated by larger HPGRs has stretched the application towards coarser size reduction duties for a number of new projects. At the same time, the basic principle of inter-particle crushing for generating a product with a high fines proportion gives ground to investigate applying the technology further towards finished product duties. The advantages that HPGR brings are clear. Multi Stage grinding enables energy efficient size reduction across more of the comminution circuit. Primary HPGR serves for a coarse grinding duty, whereas a secondary HPGR is geared towards generating a fine product for downstream processing or even a finished product. This publication summarizes some of the features of staged HPGR circuits and discusses some examples of operating and projected applications.INTRODUCTION In most HPGR applications, the grinding units are used as a single process stage, either in open circuit, such as for pebble crushing [Rose 2002, Westermeyer 2000, Van der Meer 2015] or in closed circuit with classification [Van der Meer 2009, 2012] or product recycling [Van der Meer 2010]. Where a higher plant capacity is required, the HPGRs are commonly installed in multiple lines in a parallel arrangement [Parker 2005, Koski 201, Vanderbeek 2006]. HPGRs can take a wide range of feed size distributions, and grind this down to a product with a high fines content. In general view, there is a limit on the size reduction range that even an HPGR can provide. Grinding down from a very coarse ore (e.g. 70-100 mm) to a very fine product (e.g. 100 microns range) is stretching the ability of a single stage HPGR circuit. Fine grinding generally requires a classification stage that returns the classifier oversize to the head of the HPGR circuit. From one point of view, it can be demonstrated that when recycling a large proportion of fines and middlings back to the HPGR feed results in an effective feed with an overrepresentation of middlings and fines, which will eventually reduce the grinding efficiency and consequently result in an increased recirculation mass flow [Van der Meer 2014]. From another point of view the large recycling mass puts a strain or even a limit on the capacity of present-day conveyor capacity."

Jan 1, 2018

By Arthur Brant

STEEPROCK LAKE (Figure 1) lies about two miles north of Atikokan, a village approximately one hundred and forty miles west of Fort William and one hundred miles east of Fort Frances on the Canadian National railway. The possible presence of hematite beneath the waters of Middle arm was inferred by early geological investigators (1890-1903) from the dense hematite float found on the southerly shores of this portion of the lake (1). A dip-needle survey of Middle arm, undertaken in the winter of 1930-31 by J. G. Cross, indicated two areas of high magnetic attraction which Mr. Cross thought might be due to magnetic iron oxides associated with possible hematite bodies. Bedrock could not be reached by the ineffectual hand-drilling so courageously attempted, and further work was abandoned. It was not until 1937 that Mr. Jos. Errington, of Toronto, convinced of the possibilities, determined to support Mr. Cross to the extent of several thousand feet of drilling. During the winter of 1937-38, holes Nos. 1, 3, 4, 5, and 13 were put down (see Figure 1). The first four of these holes demonstrated that the areas of magnetic attraction outlined by the dip-needle survey east of the Narrows and southwest of Elbow point were due to ash rock (2). As a result, Mr. Cross decided to investigate the bordering areas of low magnetic attraction and selected a location near the high ferruginous lime (3) point in the northeast of Middle arm. Dense, hard hematite beneath approximately 350 feet of water and clay was struck in the first hole, and, before the end of the winter's drilling, hematite had been encountered in holes Nos. 6 to 13 along a straight line 700 feet in length (see Figure 1). In the meantime, the Steerola ( 4) Exploration Company had been formed to continue development and already, in the spring of 1938, W. D. Neeland, the Company geologist, had come to the conclusion that the most probable location for possible hematite was at the ash-lime contact. Accordingly, during the summer, drilling was continued off-shore in holes Nos. 15, 25, and 27 (see Figure 2) toward possible hematite bodies inferred by Mr. Neeland.

Jan 1, 1940

By Cesar A. Urbano Jr., Gretchen T. Lapidus

A series of experiments examined silver extraction from a high-grade sulfide concentrate employing thiourea solution. Thiourea was initially oxidized with hydrogen peroxide (H2O2) to form formamidine disulfide (FADS) and used to extract silver from the as-received concentrate and after various pretreatments. Very low recoveries (~30%) were obtained with the as-received concentrate due to competitive cementation reactions by metallic iron and easily oxidizable copper phases. Over 80% Ag recovery was obtained when the concentrate was pretreated to remove this iron and copper. The results suggest that an oxidative acid pretreatment of this concentrates significantly improves silver recovery upon leaching with thiourea.

Jan 1, 2014

Strips of AA6111 automotive alloy were cast on a horizontal single belt strip casting simulator, Pure copper and carbon steels substrates plasma sprayed with different coatings for improving the strip surface quality, were used as chill moulds, Experimental studies revealed that a graphite coating provided the greatest benefit in achieving good surface quality. The interfacial heat fluxes during solidification of AA6111 strip were calculated by the IHCP method (Inverse Heat Conduction Problem). Temperature variations and cooling rates within the strips were then calculated through numerical simulations based on the time-dependent heat fluxes obtained by IHCP, The effects of casting parameters, including casting temperature and strip thickness, on interfacial heat fluxes, cooling rates and microstructures, were investigated, Although the maximum interfacial heat fluxes on the chill copper substrate were much higher than the results obtained from the steel substrates, the solidification times of the melts were mainly determined by strip thickness. Very fine equi-axed grains were obtained for both 1.2mm and 2.5mm thick strips thanks to the rapid extraction of heat, and effective grain refinement.

Jan 1, 2005

By Prodipto Ghosh

This paper is prepared as a review of existing and traditional methods related to electrical maintenance strategy. Its primary focus is to explore newer ideas and how they point the way to a more efficient and effective manner of electrical maintenance. This discussion is primarily related to large electrical distribution assets typical of heavy industry such as mining.

Aug 1, 2013

By Finch. J. A., C. Perez, J. M. Ortiz, G. Cortes, A. B. Yañiez, F. Coddou, P. Morales, H. Elgueta

A campaign to perform characterization tests in a TankCell®-300 flotation cell installed at Chuquicamata Codelco's concentrator was conducted. The campaign included integrated gas dispersion measurements (gas velocity radial mapping and single point gas holdup and bubble size) and determination of frother concentration. Cell streams were sampled to assess metallurgical performance at the same time. The experimental program was designed to establish the bubble surface area flux operating range and its effect on performance, and the effect of using longer residence times and of a device designed to enhance mixing in the collection zone (FlowBooster(TM)). The gas dispersion results and their relationship to metallurgical performance are discussed.

Jan 1, 2009

By X. W. Yi, Z. J. Li, G. W. Ma

In this paper, the compressive strength and failure patterns of reinforced cemented paste backfill (CPB) were studied aiming to promote the stability of backfilled stopes. The concept of ductile backfill was proposed and a series of unconfined compression tests were carried out on both non-reinforced and reinforced cemented paste specimens. Portland cement (3% to 5% by weight of tailings) and five different types of ductile materials (0 to 0.5% by weight of solids) were employed in this experiment for the specimen preparation. The test results showed that inclusion of ductile materials enhanced the unconfined compressive strength (UCS), reduced the post peak stress loss and transformed the failure behaviour of specimens from classical brittleness to ductility. The strength of CPB reinforced with different proportions of polypropylene fibres was compared. The stress-strain curves illustrated that both cement and fibres contributed to the increase of UCS, but higher strain values at the peak stress were achieved by fibre reinforcement. CT sliced images acquired from X-ray computed tomography (CT-scan) demonstrated that the reinforced specimen developed irregular crevices at the edge of cross sections and gained the capacity of bearing large displacements owing to the mobilised tensile strength of fibres. It leads to the potential of avoiding unexpected falling blocks of CPB when adjacent mining occurs. This finding highlights a strategy to improve the self-supporting capacity of the fill mass with less cement usage and reduce the ore dilution rates when excavating to adjacent stopes.

Jan 1, 2015