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By C. G. Kemsley

THE ore as hoisted is very wet, and difficulty was experienced i~ screening it to remove the fines before going to the secondary crusher. In fact, the fines had a tendency to form balls and roll down the screen, and only a small percentage was removed. Their inclusion with the other ore going to the Symons secondary crusher caused excessive spring action and pounding between the adjustment ring and main frame, resulting in abnormal wear between the two. To overcome this, it was decided to wash the fines through the primary screen, and use an Akins classifier to de-water the screenings, pumping the overflow from the classifier up to the mill and discharging the oversize onto the mill-feed belt.

Jan 1, 1945

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 André Desbiens, Frédéric Flament, Lionel Ryan

"In December 1991, the GRAHM (Groupe de Recherche sur Jes Applications de L'informatique a L'industrie Minerale), of Laval University started a KBAC (Knowledge Based Automatic Control) grinding project with Falconbridge Ltd. The project was shifted to the Kidd Creek concentrator in the summer of 1992, with the first phase involving the collection of data by GRAHM and Falconbridge personnel for the construction and tuning of a dynamic simulator. This grinding circuit dynamic simulator known as DYNAFRAG was used to assess various control strategies, with a PID-based strategy being selected for ease of installation on a Foxboro II A DCS.The ""B"" primary grinding circuit was chosen for the initial strategy development, which is one of three parallel divisions. The KBAC project was successfully completed in November 1994, with subsequent modifications being implemented by Kidd Creek staff.This paper summarizes, the current control strategy, the project costs, and the realized benefits. Some of the problems which were encountered with the initial installation, and the subsequent modifications are also dealt with in this paper.2.0 IntroductionIn the summer of 1992, the GRAHM of Laval University and Falconbridge Ltd. started a project to design a control strategy for the ""B"" grinding circuit at the Kidd Creek Division. Between 1992 and 1994 several papers have been written to describe the control objectives, the methodology followed, and some initial results (Flament, 1994A, 1994B). Since then, however, the control objectives changed, and several improvements were made to the circuit. In particular, maximizing tonnage was no longer a priority, a variable speed drive pump was installed on the cyclone feed, the ball mill power was lowered, and the geometry of the cyclones changed. As a consequence, the control strategy was revised. Table 1 summarizes the historical developments on the ""B"" division grinding control."

Jan 1, 1996

By L. C. Hsu, M. O. Desilets, P. J. Lechler, Jr. Bonham, J. G. Price, L. J. Garside

Geochemical background levels have been established for unmineralized sedimentary rocks that are elsewhere the hosts of Carlin-type gold deposits in the Getchell Trend. The Paleozoic rocks in the Winnemucca Quadrangle consist predominantly of the lower Paleozoicsiliceous and clastic sequences that were carried eastward along the Roberts Mountains thrust during the Late Devonian and Early Mississippian Antler Orogeny and the late Paleozoic Havallah and Pumpernickel sequences brought along the Golconda thrust eastward during early Mesozoic Sonoma Orogeny. Over 260 rock samples were collected from the Paleozoic sequences. Major and trace elements were determined by instrumental methods best suited for the specific elements. The general geochemical features of the Paleozoic sedimentary rocks are discussed in detail with reference to the data of average abundances of elements in sedimentary rocks. The background and threshold values of certain trace elements in sandstone, shale, and carbonate rock of one formation, as well as back-ground levels for the entire sequence were obtained. The characteristic geochemical features of the Paleozoic rocks in this area include: consistently high Ba and low Au contents (1.1 ppb, 1.5 ppb, 1.1ppb Au for average sandstone, shale and carbonate, respectively); generally low contents of those elements which may be of environmental concern such as As, Cd, Hg and Pb. Plots of major and trace elements suggest that the majority of the Paleozoic clastic rocks are related to a passive-margin tectonic setting. Samples with gold values higher than threshold are considered to have been affected by hydrothermal alteration related to gold mineralization. Most of these samples generally also have higher values of Sb, Hg, V and/or As. These observations support the use of such elements as pathfinders for gold, although V has not been identified as such before. Ba is not effective for gold exploration in this area due to the generally high background value of Ba, even though it may be an important pathfinder elsewhere.

Jan 1, 1995

By John D. Carriere, Jean Leung, Daniel. Laguitton, Michael .. J. Burrows

"The objective of this expert system application in a copper-zinc concentrator, is to increase the availability of assay data through substitution for erroneous data. The assay data is used by the Operations personnel and automatic process control strategies to control flotation circuit performance. Two online X-ray fluorescence analysis systems analyze 24 streams across four divisions to provide the required data. Data availability of individual streams average 90% while the resulting circuit availabilities are 70%. The unavailability of correct data results from mechanical, X-ray or process problems. The erroneous data can be identified by process experts using knowledge relating stream interdependencies and historical process behaviour. An expert system was devised to provide real time identification of erroneous data and substitute for that data with the ultimate aim of improving metallurgical response by both the operator and automatic control systems.The paper discusses the early development work and architecture of the knowledge base designed using Neuron Data's expert shell NEXPERT.INTRODUCTIONThis paper describes the early development of an expert system (ES) prototype at the Kidd Creek concentrator. The project is a joint undertaking of the Kidd Creek Division of Falconbridge Limited and CANMET. Kidd Creek entered into the project to apply heuristic rules to the XRF assay data to improve the metallurgical control of the flotation process by increasing availability of analysis data. This project provided a problem of suitable size and future expandability while making use of a wide base of in-house expertise and experience. Another important benefit is the introduction of expert system technology to the site providing tools and experience for future system selection and technology application. CANMET has an on-going interest in assessing various aspects of ES technology (hardware, software, knowledge engineering, integration) while addressing problems in process operations that could most readily benefit from the technique. CANMET's role in the project was to provide project assistance, financial support, substitution algorithm assistance and software for data substitution. The knowledge bases (rules) have now been completed and are to be tested in the online environment."

Jan 1, 1989

By L. J. Surges, C. Bazin, D. Hodouin

"A kinetic model was developed for the conditioning and flotation processes of an industrial lead concentrate dezincing circuit. The models were incorporated into a flowsheet simulator. Simulation results demonstrate the advantages of split conditioning of coarse and fine particles and the potential of this approach for the production of the heuristics required for the development of intelligent control strategies.The conditioning model relates the proportions of activated and hydrophobic surfaces and residual reagent concentrations to activator and collector reagent flowrates. The model accounts for the solids and water flowrates, and for the solids grade and size distribution. The flotation model uses the predicted proportion of hydrophobic mineral surface, the aeration rate and the froth depth to estimate cell, bank and circuit performances. IntroductionFlotation has been the object of modelling and simulation studies for more than two decades. The process is usually modelled as a kinetic one in which the particle flotation rate constants are key parameters. Rate constants are related to the operating variables (pH, reagent flowrates, aeration rate, etc), however these relationships are seldom established in the literature.In spite of the large amount of literature on flotation modelling and simulation, few papers deal with the interaction between flotation rate constants and operating variables. This important gap, which was identified in the early seventies by Woodburn (l970), still exists. One of the first attempts to include operating conditions in a flotation simulator was made by King (l973), who explicitly introduced the aeration rate into an air bubble loading model. Lynch et al. (1981) used an empirical model to relate the proportion of slow floating particles to the ratio of collector per ton of ore. Such empirical relationships are difficult to calibrate and cumbersome to use when an activator and a collector are added to slurries in which particle size distribution and surface characteristics are changing. Eascur and Herbst (l982) relate in a fundamental way the mineral flotation rate constants to the aeration rate, froth depth, agitation and frother concentration, however the model does not account for reagent flowrates. Niemi et al. (1982) have proposed a model for the conditioning of minerals and included it into a conventional flotation simulator."

Jan 1, 1988

By C. T. Morley

The steadily increasing interest in high pressure grinding rolls (HPGR) as a legitimate alternative comminution technology for hard rock applications has led to a proportional increase in the demand for trade-off studies comparing HPGR with more established approaches, typically SAG-based but including AG and stage-crushing designs. The primary trade-off is between a) the higher capital cost typically incurred with HPGR-based designs and b) the higher operating costs of the more traditional technologies. However, if, through circuit design innovation, the capital cost penalty of HPGR circuits could be eliminated or reversed, then the need for trade-off studies would diminish.

Jan 1, 2012

By L. Bichler, A. Siebert-Timmer

In this research, novel YSZ ceramics doped with 5 mol% Nd2O3 were manufactured via Spark Plasma Sintering (SPS) process. The sintered Nd2O3-YSZ ceramics were subjected to a static supercritical water environment at a temperature and pressure of 400 °C and 31 MPa, respectively. The weight loss and microstructure development of the sintered ceramic before and after exposure to supercritical water was studied. The results suggested that Nd2O3 addition significantly improved the degradation resistance of the YSZ ceramics. This was attributed to the improved phase stability of the 5 mol% Nd2O3-YSZ ceramics, since X-ray Diffraction (XRD) studies showed that the cubic stabilized matrix in these ceramics was retained after exposure to supercritical water. In comparison, pure YSZ ceramics exhibited a rapid degradation behavior as well as a phase change.

Jan 1, 2014

By Robert J. McCarthy

Mining has a record of achievement in developing and adopting new technology to facilitate the extraction of increasingly challenging resources. Certainly larger, or more capable, mining equipment has allowed mining companies to mine mineral deposits at lower unit costs; however, there has also been the advent of computerized systems that aid in the management and tracking of mining operations. Unfortunately, the latter computerized systems have not always had the success anticipated with their implementation. This paper explores the view that increased transparency of the planning and operating cycle in a mine, as provided by certain computerized systems, can result in some resistance from those whose work becomes ?exposed?. Examples are drawn from industry-leading technologies for both mine management and reconciliation that illustrate the issues and challenges that result. The adoption of appropriate change management principles is suggested as a best practice in planning and mitigating the challenges in implementing technologies which increase transparency in the mining environment.

May 1, 2011

By K. D. A. Whaley

The Captain North Extension deposit consists of five sulfide lenses hosted in cherty and chloritic metasediment that is bounded by quartz-eye rhyolite and laminated rhyolite. Lens 2 consists of sphalerite and galena with silver-rich tetrahedrite in chert. Lens 3 contains massive pyrite, with chalcopyrite and minor gold, gradational to minor pyrite in a chloritic metasediment. The other lenses are unexplored. The sulfides occur as beds, fracture infills, and disseminated grains. Reserves are estimated at 207 555 tonnes grading 7.380/0 Zn, 2.76% Pb, and 91.81 g/t Ag. The deposit is isoclinally folded, dips steeply west, plunges 50 degrees south, and is faulted out to the north, where drag folding has reversed the plunge. Minor cross-faults contain talc and sericite. High sphalerite but low pyrite abundances result in poor responses to standard electromagnetic techniques. Lens 3, which contains more pyrite than Lens 2, responds better to induced polarization and allows detection. Geochemical anomalies are found in a nearby swamp and stream, but an impervious till cover inhibits the development of soil anomalies.

Jan 1, 1992

By Christian M. Bauer

Modern surface mines are among the world's largest single consumers of diesel fuel. A typical mine site can consume in excess of 200 million liters of diesel fuel per year. Delivered diesel fuel is not necessarily clean. Depending on the mode of transportation, handling practices and local climate, incoming bulk fuel can contain up to 20 mg/L suspended solid contaminants and also significant quantities of free water, which can amount to substantial quantities ? for a typical mine site 200 to 400 kg of dirt per year. Standard on-board fuel filters are not designed to handle high levels of contamination, and most engine manufacturers have specific fuel cleanliness requirements to ensure reliable engine operation. New developments in fuel injector technology, such as high pressure, common rail injectors require even cleaner fuel. In order to ensure reliable operation, it is therefore recommended to control particulate contamination throughout the entire Diesel supply chain - from the bulk storage on mine sites to the injection systems on-board through the use of particulate filtration and liquid coalescence technologies. In this work, the author introduces a comprehensive approach to contamination control for the entire fuel supply chain, and discusses the benefits of using advanced filtration and separation technologies, with a particular focus on the requirements of modern high pressure, common rail (HPCR) fuel injection systems.

Nov 1, 2011

By R. P. Viljoen, A. L. Sokolov

"The distribution of mineralized provinces is analyzed on the basis of their genetic link with specific blocks of the earth's crust including ancient platforms, mobile belts and zones of tectonicmagmatic activation. Mobile and fold belts surround the Siberian platform in Russia and the Kaapvaal craton in South Africa, with decreasing age zoning away from ancient platform margins. The main differences in the geological development of the two cratonic areas are: (1) the long period before the final stabilization of the Siberian platform (3600 Ma to 1600 Ma) and the comparatively short period of time for the stabilization of the Kaapvaal craton (3600 Ma to 3050 Ma) and (2) the intensive multiple activation of the marginal zones of the Siberian platform and the tectonicallycontrolled, magmatic sedimentary, intracratonic activity, typical of the Kaapvaal craton. Mineralization of the Siberian platform is largely characterized by marginal reactivation zones of differing ages although mineralized intracratonic Cu-bearing basins of Proterozoic age are also known. Mineralization of the Kaapvaal craton is mainly related to the formation of the intracratonic basins i.e., Witwatersrand (Au, U) and Transvaal (Au). The latter is characterized by multi-age volcanic-intrusive activity including the emplacement of Bushveld Complex (Cu, Ni, Pt, Cr, Au, V). The Siberian platform is characterized by the prolonged development of inherited mineralization from Archean until the late Mesozoic. The main period of mineralization in the Kaapvaal craton is restricted to the middle Proterozoic.The Baykal-Patomskaya and Namaqua-Natal mobile zones occupy similar positions adjacent to the Siberian and Kaapvaal cratons, respectively, and demonstrate similar modes of metallogenic development: i.e., the early formation of exhalative Pb-Zn-Cu deposits during the early stage and magmatic Cu deposits during the late stage. The more remote mobile belt near the Siberian platform, the Trans-Baykal, is characterized by intensive multi-age mineralization (Wo, Mo, Sn, fluorite), related to a period of tectonic-magmatic activation. The Saldania Belt occupies a similar position near the Kaapvaal craton but is known for its poor Au, and Cu mineralization. It does, however, have some similarities with Trans-Baykal Belt in regard to Mo-W bearing granitoids.The phenomenon of interference of geosynclinal, orogenic, platform, and tectono-magmatic activation regimes is known for the Russian section of the Pacific Ocean Volcanic Belt."

Jan 1, 1994

By F. F. Roberto

Sulfuric acid has been demonstrated to be an efficient lixiviant for in situ extraction of copper in the past. It has also been proposed that microbial production (by iron-oxidizing acidophilic bacteria) of acidic ferric solution either in situ or ex situ could provide an economic strategy to generate an effective lixiviant for secondary copper sulfides like chalcocite and covellite. Copper heap bioleaching also takes advantage of this approach. One of the major environmental challenges for in situ copper recovery projects is the containment of acidic solution within the ore deposit, and ultimate restoration of the depleted ore body to its original state. A perhaps overlooked aspect of projected site operations is the possibility that transient acidic conditions and pumping of solutions from surface reservoirs into the subsurface could stimulate the growth of iron- or sulfur-oxidizing species of acidophilic microbes in the ore body, leading to additional generation of sulfate, acid, and ferric iron. This outcome would benefit extraction of copper in mixed oxide/sulfide deposits in the near term, but could complicate restoration activities. Possible impacts of pumping acidic solutions into the subsurface on microbes resident in, or introduced into the extraction zone will be discussed in the context of our understanding of copper heap bioleaching and acid rock drainage. INTRODUCTION As high-grade deposits of metals such as copper continue to decline, conventional mining methods have evolved to mine and process larger and larger quantities of ore. What is currently defined as ore today often contains less metal than the tailings of past operations. The throughput of current-day mines also leads to tremendous amounts of waste rock and tailings that may threaten the environment and communities around the mines, as has recently been experienced by 3 major tailings disposal facility (TSF) dam failures in the past 5 years. Community acceptance of large mine operations thus becomes more difficult to achieve—loss of the social license to operate. In response, the mining industry urgently pursues innovations that can fundamentally change the way in which metals are mined. In situ recovery (ISR) of metals represents one approach to a more sustainable mining industry, by virtually eliminating the need for a pit or underground excavation, eliminating the excavation and transportation of ore to a process plant and the ensuing noise and dust that is generated, and any need for waste rock dumps or TSFs. An ISR mine could have very little visible footprint beyond a network of wells, pumps, and piping to transport pregnant solution to a recovery facility, such as a solvent extraction- electrowinning (SX-EW) plant for copper. Some solid waste streams and/or storage ponds may still be necessary to treat and store bleed streams, PLS and raffinate, or as part of groundwater restoration activities. Thus capital and operating investments would be potentially much lower than that required for a conventional mine. In theory production could also be controlled to adjust to subsurface ore grade and match market demand. A not insignificant challenge of in situ recovery is the requirement for an efficient, low-toxicity, and ideally selective lixiviant for the metal that is targeted.

Jan 1, 2019

By Frederick Biery

Outline ? Project Challenges ? Results from 100 recent projects ? What factors are driving the best and worst projects ? A look at recent mining projects ? Conclusions

May 1, 2009

The AG/SAG circuit discharge P80 is now increasingly referred to as the “Transfer Size” or T80 for short. From the literature it is apparent that in circuit design some approaches to the sizing of AG/SAG mills as well as the ball mills that they feed use this parameter. This paper reviews whether the use of the T80 is appropriate in this context. In the course of the review examples of AG/SAG discharge size distributions measured from range of operating circuits are used to illustrate the arguments made.

Jan 1, 2012

By G. Ladouceur

"LOCATIONThe mine and mill are located in Lemoine township which is 20 miles directly south-east of the town of Chibougamau Quebec. Personnel live in Chibougamau and commute to the property over 33 miles of paved and gravel roads. Concentrates are trucked 13 miles to a railway siding on the line connecting Chibougamau and Quebec city.HISTORY Several companies explored the property before acquisition by Patino Mines (Quebec) Limited in 1973. Further exploration led to the discovery of a high grade copper-zinc orebody and the property was brought into production by the above company in 1976.ORE The ore contains 85% - 95% sulphides consisting of chalcopyrite, sphalerite, pyrite, pyrrhotite and minor gold and silver. Argenti tetrahedrite, antimonial silver, native bismuth and galena are also pre sent in very minor quantities. Associated gangue minerals are quartz, carbonates and occasionally chlorite."

Jan 1, 1979

By Sobczyk

The article will present a comparison of classifications of resources according to the JORC Code System with Polish classification, basing on system used in Eastern Europe. The differences between these classifications are significant. The information about mineral resources in Poland is not comparable to the main international system of reporting reserves like JORC, SAMREC, and PERC. Although comparisons between these systems are used, the transfer of particular categories of resources from the Polish system into a JORC category is not simple. Basing on the examples of privatization of Polish coal companies through initial public offering on the Warsaw Stock Exchange, the current practices providing guidelines how to convert resources from the Polish classification to the JORC system are described. Such independent assessment of resources is necessary for development of Mineral Expert?s Report (MER or CPR) which is an integral attachment to the prospectus.

Aug 1, 2013

By J. Seidel

In 2009 Newmont Mining Corporation’s annual global spend on grinding media reached $94M USD, having doubled in the five years since 2004. The major contributing factor to the spend escalation during this period was unit consumable price, with total media consumption also rising as a function of annual ore tonnes milled. In an effort to better understand and manage the growth of this expenditure a significant supply chain management program was implemented. This was complemented by a series of technical initiatives focussed on grinding media specifications, quality management and the prediction of grinding media wear rate as a function of physical ore characteristics. This paper discusses the methodology and outcomes of these activities.

Jan 1, 2012

By Masaru Kato

The plated gold being used by the electronics industry can be broadly classified into two categories: soft gold and hard gold. Soft gold is used for circuit metallization and for bonding semiconductor chips, while hard gold is indispensable as the contact material on electrical connectors, electromechanical relays, and printed circuit boards. The traditional baths from which to plate soft gold as well as hard gold contain the cyanide complex, [Au(CN)2]-, as the source of gold, which liberates free cyanide ions during the plating. The free cyanide is not only highly toxic but also attacks photoresists used to delineate circuit patterns and bonding pads. For these reasons, non-cyanide baths are in use to plate soft gold, whereas hard gold can be plated only from cyanide baths at present. In this presentation, the current status of both electrolytic and electroless non-cyanide processes for plating soft gold will be reviewed.

Oct 1, 2003

By J. Drozdiak

In this paper we present the results of preliminary investigations into the applicability of new laboratory scale tests for the prediction of operating gap and specific throughput in high pressure grinding rolls (HPGR). The work is a part of the CAMIRO HPGR research program being conducted at the University of British Columbia, which aims to develop a suite of small-scale tests and procedures for the selection and sizing of HPGRs. A focus of the presented study is to test sample types in terms of their terra-mechanics based characteristics and relate them to specific throughput and gap results from pilot HPGR testing on the same samples.

Jan 1, 2012