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By Daniel Hodouin, Robert Lanthier, Yve Dube

"A procedure f or constructing a grinding mill dynamic model is proposed. This model is used in a dynamic simulator of are grinding circuits. The simulator is designed for flexible flow sheets involving different grinding mills and particle classifiers and is able to accept several single variable PID control loops. The dynamic model is validated on a laboratory ball mill, and calibrated to an industrial installation. The simulator is used for characterization of grinding circuit dynamic behaviour and tuning of control strategiesIntroductionThe ore grinding operation is a critical step of the ore preparation process because it is the last comminution stage before the separation of minerals. The properties of the ground minerals to be concentrated, control the quality and efficiency of the separation process. This is why it is important to control properly the operation of the last grinding stage, commonly constituted of a closed circuit ball mill with classifier . To provide an adequate fine product, the grinding operation should compensate for the perturbations of the feed characteristics (size analysis, grindability, etc.). The main objective is to maintain a constant size distribution for providing stable operating conditions to the separation units. Simultaneously another usual objective is to operate the grinding circuit at a maximum capacity.Automatic control applied to grinding circuit s is the appropriate approach to improve its operation. Most frequently average optimal operating conditions are determined from steady -state performances of the circuit , and the automatic control is used for stabilizing the operation at selected values of the process variables . In the traditional approach, one or several single input! single output (SISO) control loops are implemented and empirically tuned. Advanced control practices'!' are based on a quantitative analysis of the circuit dynamics, which could also give a basis for the tuning of conventional SISO 100ps(2)."

Jan 1, 1987

By W. J. Kuit

"Complex facilities which provide for the collection, management and treatment of effluents emanating from the Sullivan mine and concentrator tailings were made operational in October 1979. Key features of the system are the use of upgraded tailings ponds for the storage of up to 800 million litres of metals-contaminated effluents, a treatment plant employing lime in a high-density sludge process and a sludge-impoundment facility designed for maximum long-term environmental safety. The completed works are capable of satisfying a difficult range of operating requirements imposed by highly variable weather conditions, drainage flows and soluble metals loadings. Final capital expenditures for the project approached $10 million and annual operating costs are about $0.8 million.This paper discusses the Kimberley effluents treatment project and the major considerations in its development. The treatment process, major plant equipment and initial operating experience are also described.IntroductionCominco Ltd. has worked the Sullivan orebody at Kimberley, B.C. since 1909 and has operated a concentrator some 5 km distant from the mine since 1923. Over the last 70 years, in excess of 120million tonnes of ore have been mined, and production continues at an average rate of 6,500 tonnes per day. It is a well-known fact that the contribution of this operation to Canada's mining industry and, in particular, Cominco's development has been significant. However, this success has not been without some undesirable side effects.Unfortunately, the Sullivan is one of only a few major Western Canadian orebodies which may be classed as ""acidic"" in nature. That is, the primary economic minerals, galena and marrnatite, are enclosed in a siliceous host rock with abundant pyrrhotite, but with little or no accompanying alkaline gangue minerals such as calcite and dolomite. The unavoidable consequence of mining such an ore is that contact with air and water generates an acid mine drainage containing various soluble metals orginally present as minerals.This problem also arises in the concentrator's tailings ponds, which, in the case of the Sullivan, are two separate impoundments of different materials. The 1,100 tonnesl day of ""iron"" tailings are primarily pyrrhotite which is surplus to the requirements of a separate operation that produces sulphuric acid as an intermediate to phosphate fertilizers. Inert gangue minerals with only a minor sulphide content are the main constituents of the 1,200 tonnes/ day of siliceous tailings. Corresponding to the relative proportion of sulphides in the solids, the decant from the iron tailings is substantially more contaminated than that from the siliceous pond."

Jan 1, 1980

By T. W. Sullivan

"This paper explores the history of AC static variable frequency control drive systems on open cast mining machinery, in particular electric mining shovels and electric walking draglines, over the past ten years. It critiques the peformance of these drive systems from a productivity and operating cost standpoint and evaluates the over-all success of the original design concepts as they were envisaged in the 1970s. The paper details the state-of-the-art as it exists today as well as design improvements contemplated for the immediate future.IntroductionConsidering the fact that the very first successful application of an alternating current electrical distribution system occurred at the Gold King gold mine near Ames, Colorado, U.S.A., in the year 1891, it seems somewhat ironic that almost 100 years later, AC excavator drive systems are just now becoming commonplace in the mining industry.If one were to read the biography of Lucien L. Nunn, the first person to successfully install a commercially viable alternating current power distribution system, one would quickly visualize a parallelism between his fight to achieve acceptance of his new lower cost technology and that of those commissioned with the belief that AC static variable frequency control drive systems are not only a better performing, lower cost drive system for mining excavators today, but moreover, the drive systems of the future in our industry.This paper will deal with the evolution and incorporation of AC static drive systems on open cast mining excavators. It will trace the history of the development of these drive systems in the mining industry, the current state-of-the-art concerning these systems, and what the future holds for these excavators in our industry."

Jan 1, 1990

By K. Mayhew, K. Murray

The CESL Copper Process was developed as a hydrometallurgical alternative to smelting and refining for copper sulphide concentrates. As the majority of such concentrates contain appreciable gold and silver values, effective recovery of these metals is essential to the economics of this technology. Unfortunately, conventional cyanide processing cannot be used on the residue from the copper process, clue to its unusual characteristics when compared with naturally occurring gold and silver ores. An abundance of elemental sulphur, as well as the presence of cyanide soluble copper, leads to the formation of both thiocyanate and copper cyanide which is detrimental to process economics clue to excessive cyanide consumption. This, however, can be reduced to acceptable levels by process innovations such as pressure cyanidation and cyanide recovery. This paper outlines the successful application of the CESL Gold Process to various gold-bearing copper concentrates from bench to demonstration scale.

Jan 1, 2011

By R. Carrier

"There has been a continuous evolution with the use of pre-cast concrete elements in the construction of aluminum smelters. In 1990, Phase I of Alouette was built using cast-in-place concrete exclusively. Whereas, other AP 30 technology plants such as Hillside 2 in the mid-1990s used pre-cast concrete beams with cast-in-place floors. Mozal 2, in 2002, used pre-cast concrete beams with pre-cast partial-slab operating floors. Alouette Phase II went further. Not only were the potroom building beams and floors pre-cast, but the entire pot support system, insulating walls and basement jersey walls were pre-cast. Once the techniques for bending and welding the reinforcement bars and the design for attaching electrical insulating plates to the concrete was perfected, the challenge for the project remained only in the logistics of transporting the pieces to site and simple erection. The overall impact on the project was dramatic. Using prefabricated concrete not only allowed advancement of the schedule, but totally eliminated formwork, re-bar installation, and form removal activities along with the handling of all the materials involved with these activities. With the elimination of these labour and material-intensive portions of the job, exposure to work injuries was dramatically reduced. The most prevalent activity for lost time accidents is during the rough work associated with concrete formwork, placing concrete and form removal. Another area where prefabricated elements were successfully used on Alouette Phase II was for the insulating walls enclosing the pot area, known as the ""claustra walls"". Usually these walls are constructed in-situ using mortar and breeze block. Success was also achieved with prefabrication of the perimetric walls that are installed at the lower floor of the potroom. A big advantage of using prefabricated concrete in the electrolysis area is in assuring electrical isolation for the operating floors. Poured concrete requires a meticulous clean-up effort before commissioning to establish the electrically ""floating"" characteristics of the operating floors. Poured concrete results in ""wash"", stray wood,"

Jan 1, 2006

By S. Orangi

A representative sample of ramming paste from a peripheral seam in an aluminium electrolysis cell was taken in order to develop a process to fabricate ramming paste samples in the laboratory. To this end, paste material was compacted in multilayers in a mould designed to be representative of peripheral seams in Alcoa's smelters. The density distribution in the representative sample was measured ranging from 1.51-1.76 g/cm3. The density range obtained by the proposed methodology in laboratory is 1.47-1.77 g/cm3. The results demonstrate that the proposed fabrication method adequately duplicates paste density from the cell for both one and two layer compaction. Finally, preliminary results related to the compressive strength and Young's modulus of laboratory samples were obtained at various temperatures and are presented in this paper.

Jan 1, 2011

By J. Hoover

"IntroductionThis chapter will discuss the operational and maintenance aspects of a heavy media cyclone circuits as applied to coal processing and using magnetite as the media. It deals with heavy media bath separators in terms of types of media, equipment, circuits, media recovery, maintenance, and product handling. It will detail heavy media cyclone operation and supplement the previously described topics.The heavy media cyclone was first developed in the Netherlands by the Dutch State Mines in 1945. A cyclone plant was not built in North America until 1961. Traditionally, heavy media cyclones have been used to treat size fractions between 1lz in. (12 .6 mm) and 35 mesh (0.5 mm). High maintenance related to heavy media bath separators has recently prompted some plants to crush all raw coal to minus 2 in. for treatment in heavy media cyclones.The heavy media bath separators utilize only the force of gravity to make the separation between heavy and light particles. This requires lengthy retention time which can lower capacity and also is inefficient for finer particles. A heavy media cyclone utilizes centrifugal forces which are 20 to 200 times greater than the force of gravity. This means the separation between coal and the impurities occurs very quickly, therefore a low retention time is required allowing cyclones to have high tonnage capacities. Also these greater forces allow better separation for the finer particle sizes.Heavy media cyclones are now widely used to produce both metallurgical and thermal coal. Work is in progress to reduce magnetite consumption, extend wear life, increase tonnage capacity, improve separation efficiency and automatically control these cyclone circuits."

Jan 1, 1989

By W. D. Madeley

Synthetic minerals were made from pure starting materials and galena samples were doped with the title metals. Microscopic, microprobe and X-ray examination confirmed that the dopeants were in solid solution. Paired flotations in a Hallimond-tube apparatus were performed to determine relative flotation response using Aerofloat 238 promoter. Results of these tests show that silver-doped galena floats more readily than pure galena and that galena doped with bismuth floats less readily than pure mineral to a 95% confidence level. Galena doped with both silver and antimony as AgSbS2 shows no detectable effect. Antimony-doped galena followed the expected trend, but not to 95% confidence. The results are consistent with the theory that flotation by thiol-type anionic collectors is enhanced by p-type semiconduction.

Jan 1, 1978

By Barry J. Morash

The over-all slope angle of between 55 and 60 degrees at the Adams Mine necessitates control blasting on the final pit walls. The control blasting techniques used are pre-shearing and buffer blasting. Pre-shearing with 2'I2-inch holes on 5-foot centers is used in areas where jointing and rock type are not conducive to smooth stable walls. Buffer blasting with 12'/4-inch holes is used in areas where the rock is competent. Control blasting adds to the operating costs, but can result in substantial savings in increased slope angle and reduced stripping.

Jan 1, 1978

By Egon Berger

"In recent years the trend in underground metal mining has been toward ever increasing blasts (often in excess of 100 000 tonnes per blast). The Canadian mining industry has been in the forefront of these developments (VRM, LBHand cable bolting to stabilize the surrounding rock /avoid dilution).In order to move these large tonnages, efficient loading systems have to be developed. This paper shows the technical and economic implications of various loading scenarios based on a predefined (however typical) stoping layout by:1 . discontinuous loading using scoop trams;2. discontinuous loading using scoop trams in combination with low profile dump trucks;3. continuous loading (based on loading performance/operating costs of the AL-60) in combination with low profile dumptrucks.The cost advantages of production concentration (loading large tonnages from one drawpoint}, made possible by continuous loading as opposed to sea tiered mining (small tonnages), using discontinuous loading in tunnelling will be presented, based on actual results obtained in a decline development project using the A L-60 continuous loader. At as pacing oj150m between turning bays, it was found that continuous loading was out performing discontinuous loading in approximately80% of the overall decline development.Fuel consumption and total cycle times are compared, and a cost assessment is presented.INTRODUCTIONThe subject of this paper deals with the introduction of continuous loading in underground metal mining and single heading tunnelingContinous mining has been widely introduced both in underground and surface coal mining. Mechanized longwall mining, utilizing moveable shield supports in combination with double drum- shearers, has resulted in a tremendous increase of coal production per working face.This has led to very concentrated mining operations. In a typical German coal mine two mechanized longwalls nowadays would produce the same amount of coal as 12 to 15 longwalls in the 1950s. One longwall in a South African coal mine has recently set a world record with 120 000 tonnes of coal in a single month.In underground metal mines-often due to the irregular nature of the ore body and the mining methods used-mining is far less concent rated. Ore is often produced from a large number of stopes and production sections. Sometimes, a substantial amount of ore may be obtained from development in the orebody (40070 at a German base metal mine)."

Jan 1, 1989

By N. Saracoglu, J. P. Golightly, R. H. Wallis, J. J. Brummer

"The McClean uranium deposits are located 11 km west northwest of the Rabbit Lake Mine. Their average grade is 1.8 % U3O8 , and they contain 6. 350 tonnes of uranium oxide in seven pods of variable grade and mineral assemblage. They are hosted by both basal Athabasca Group and the regolith developed on the underlying crystalline basement. The major mineral facies are: sulphide, arsenide, 'bleached', and hematite, with the important uranium minerals being coffinite, uraninite and pitchblende. Abundances of carbon and sulphur isotopes are consistent with their derivation from pyritic graphite in basement gneisses. Isotopes of oxygen and hydrogen suggest equilibration at temperatures of about 200°C. Ar39/ Ar40 age determination of illite associated with ore suggest mineralization began about 1300 m.y. ago and that significant alteration had ceased by about 1170 m.y. ago though Pb/ U data suggest the deposits continued to evolve into the Mesozoic.IntroductionThe McClean deposits lie on the eastern side of the Athabasca Basin of northern Saskatchewan where they are part of a cluster of uranium deposits lying west of Wollaston Lake (Fig. 1). The general stratigraphy is schematically portrayed in Figure 2 which emphasizes that mineralization is hosted by both the Athabasca Group and the underlying regolith and also that the deposits are preserved at depth and have not suffered from preand post-Pleistocene weathering and erosion. This circumstance, combined with their simple shape and the presence of seven separate zones of mineralization (pods) allows a description, based on over 450 fully cored drill holes, to be made of the wide variation in chemistry, grade, alteration patterns and position relative to the sub-Athabasca Group unconformity. Ar39 / Ar40 age determinations have been made of illites associated with regolith, Athabasca Group and mineralization and studies are in progress on C, S, 0 and H isotopes of mineralized material and host rocks. Only some of these data have been published; Brummer et al., (1981); Golightly et al., (1982); Bray et al., (1982); and Saracoglu et al., (1983). The only other published data on McClean geology are by Tremblay (1982, 1983)."

Jan 1, 1986

By A. Longval, Q. Jiao, T. Shannon

In 2000, Xstrata Zinc (former Falconbridge Ltd.) Brunswick Smelter commissioned a modified lead blast furnace. Since then, efforts have been made to improve its operation in order to achieve optimal operation in terms of coke consumption, lead loss to slag, and improved environmental and hygiene conditions. This paper will review the important step changes in operational philosophy, undertaken since 2004, for the control of the blast rate, oxygen enrichment in blast, slag chemistry and charge level. Furthermore, a review of the improvements made in secondary materials consumed at the blast furnace will be made. This paper will also discuss the significant reduction of the frequency of accretion removal as a result of improved furnace operation.

Jan 1, 2008

By Oleg G. Tovmachenko

We have studied optical properties of fluorescent nanoparticles. These particles consist of a metal (gold/silver) core, an empty and a dye labelled silica shells. The different dye molecules with moderate quantum yields (about 0.3) has been used. Almost all of types of nanoparticles show fluorescence enhancement. This enhancement is strongly dependent on the degree of the overlap between the surface plasmon band of the metal and the absorption/emission band of the dye molecules. The results are interpreted in terms of competition between local field enhancement and quenching of fluorescence by the metal surface.

Oct 1, 2003

By A. Hutwalker, T. Plett

"Blast fumes are one of the major sources for NOx in underground mines. In 2016, the Occupational Exposure Limits for NOx in Germany were reduced by 90%. The task is to keep re-entry times after blasting at the present level and thereby ensure an economic operation of the mine. Measurements show that using ventilation solely is not sufficient. A new approach to reduce NOx from blast fumes is described. Laboratory experiments were performed and a reduction of NOx was observed. Measurements were conducted at an explosive factory’s testing facility and in an underground mine at blasting operations. INTRODUCTION Whether for production of ore or for drift development, the processes in an underground mine are always the same: 1) fracturing the rock, 2) loading the pile, 3) support the resulting cavity. The fracturing of the rock can be done mechanically, by cutting, for example by using continuous miners or tunnel boring machines, or by drilling and blasting. Drilling and blasting is more flexible than mechanical driving, as it can be used independently of the rock strength. Furthermore, this driving method allows a more flexible reaction to changes in geological and/or operational conditions. Thus, underground mining and blasting are almost inextricably linked with each other, and regardless of the size and level of technology of the mine, blasting is hardly avoidable. Depending on the mining method chosen and the existing framework conditions, such as the mechanical properties of the rock or the availability of machinery, blasting is an integral part of daily operations. Even in mines where blasting is not part of regular operations, it cannot be completely avoided. The blast fumes generated by the explosions are, in addition to diesel engine emissions, one of the two main sources of emissions of nitrous gases underground. Up to now, state of the art for dealing with blast fumes is ventilation. The fumes are diluted with fresh air and ventilated out of the mine. This treatment of blast fumes is more than sufficient with the former German Occupational Exposure Limits (OEL). The adaption of the OEL in Germany to the recommendations of the Committee on Occupational Exposure Limits (SCOEL), a committee of the European Commission, leads to big challenges for the mining industry in reducing the concentrations of these gases at the workplaces underground. On its meeting on May 2nd and 3rd 2016, the Committee on Hazardous Substances (Ausschuss für Gefahrstoffe, AGS), an advisory body of the German Federal Ministry of Labour and Social Affairs (BMAS), advised the BMAS to copy the OEL, as recommended by the SCOEL, to the Technical Rules for Hazardous Substances (TRGS 900). BMAS followed this advice, consequently the new OEL where published on November 4th 2016 and became part of the TRGS 900. Table 1 shows the former and new OEL for Germany. These new OEL became law after publishing, but two exceptions were made: For tunneling operations, they became law on October 31st 2017, for mining operations they will become law on October 31st 2021 (BAuA, 2004, 2016, 2017)."

Jan 1, 2019

By Umbreen Agha, Stephan L. Chryssoulis, A. Margaritis

"The deportment of gold in samples of the biooxidation feed and product from the Harbour Lights mine in Western Australia was determined using optical microscopy and microbeam techniques such as Secondary Ion Mass Spectrometry (SIMS), Time-of-Flight Laser Ionization Mass Spectrometry (TOF-LIMS), and Electron Probe Microanalysis (EPMA). The main objective was to determine the mechanisms by which acidophilic bacteria (Thiobacillus ferrooxidans) liberate refractory gold which is locked in a sulphide minerals host as visible gold inclusions (> 0.1 µm) and as submicroscopic or 'invisible' gold.Using the integrated mineralogical approach approximately 99% and 100% of the assayed gold in the biooxidation feed and biooxidation product was accounted for. The results were compared to and verified by chemical assays.The gold deportment study indicates that during biooxidation, locked visible and 'invisible' gold is rendered cyanidable by the direct action of Thiobacillus ferrooxidans as well as indirect chemical leaching. Visible gold which is enclosed in sulphide minerals is liberated or partially exposed and is therefore rendered cyanidable as the host mineral is oxidized and dissolved. 'Invisible' gold either coalesces on the surface of the host sulphide mineral as the particle is dissolved or is released into the liquid phase and immediately adsorbs onto the surface of other ore particles with a net negative charge.The shakeflask suspension indicates that direct bacterial oxidation pits and channels correspond to zones of 'invisible' gold and arsenic (in pyrite) enrichment in the host sulphide mineral."

Jan 1, 1996

By Barbara A. Filas

The IFC goal is to promote private sector investment in developing countries which will reduce poverty and improve people?s lives. The developing country goal is to promote health, education and employment opportunities that improve their economies and their standard of living. The mining company goal is to Promote successful ?triple bottom line? mining projects that will grow shareholder equity

May 1, 2002

By K. Östcrdahl

We are developing a cost-saving and environmentally friendly process with low energy consumption to recover the metal content and recycle the acid from spent pickle baths. The metals are precipitated as metal fluorides, which can be turned into metal oxides and hydrofluoric acid by thermal hydrolysis. In the proposed process the solution is concentrated by nanofiltration and the metals are precipitated in a subsequent crystallization step. Different nanofiltration membranes have been evaluated in experimental batch tests. The membrane MPF-34 from Koch Membrane Systems offered both good flux and acceptable metal retention even after long periods of acid storage. The solubility of B-FeF3.3H20 has been measured at varying acid concentrations and at different temperatures. The solubility decreases with increasing hydrofluoric acid and nitric acid concentrations. This suggests that the crystallization process should be operated at high acid concentrations. The crystal growth rate of B-FeF3.3H2O is found to be quite low but increases significantly with temperature. This suggests that the crystallization process should be operated at higher temperatures (40 - 60°C). Within the project a pilot plant has been constructed where the spent pickle bath solution is concentrated by nanofiltration to the desired metal fluoride supersaturation, and B-FeF3.3H2O is crystallized in a 10 L continuous crystallizer.

Jan 1, 2006

By S. M. Grillo, Fiori. M., R. Bornioli, C. Marini, S. Fadda

Abstract - The Na-feldspar orebodies in Sardinia occur along structures belonging to a regional ENE-WSW system that developed during the late stages of the Hercynian orogeny, and that was reactived during the Alpine orogeny. The main petrographic facies include granitoids, albitized granitoids, albitites (more or less rich in quartz), and albitites containing Mg minerals. Field observations and petrological and geochemical data point toward a metasomatic origin for the albitite orebodies. Albitization involved depletion of K from K-feldspar and biotite, dissolution of free quartz, and a lowering of Sr/Na2O and CaO/Na2O ratios in the protolith, under conditions of a positive thermal gradient. The absence of later K-metasomatism implies that, during a subsequent decline in temper- ature, the composition of the albitizing fluids was modified by an influx of meteoric or other waters.

Jan 1, 1996

By Troy Boisjoli, Sean Hillacre, Matt Batty

Discovered in 2014, the Arrow Uranium Deposit has undergone rapid development through successive drilling programs informed by geostatistical drill hole spacing studies. An independent third-party geostatistical drill hole spacing study was completed by Clayton V. Deutsch Consultants Inc. in 2017, evaluating the uncertainty of thickness, grade, density, and areal limit of the Arrow Deposit to determine a drill hole spacing suitable for Indicated Mineral Resources. Indicated spacing was defined to be 24 to 32 metres (“m”) to be within 15% of predicted for a nominal quarterly production volume with a probabilistic tolerance between 75 and 90%. The study not only defined the Indicated Mineral Resource resultant from the 2016 drill program, but also provided drill hole targeting criteria for subsequent drill programs aiming to convert Inferred to Indicated Mineral Resources. A subsequent geostatistical drill hole spacing study on the Arrow Deposit was completed by Clayton V. Deutsch with Resource Modeling Solutions in December 2018 to define Measured Mineral Resource spacing in support of the 2019 drill campaign. The study resulted in a drill hole spacing of 9 to 17 m to be within 15% of predicted for monthly and quarterly production volumes using an accepted industry probabilistic tolerance of 90%.

Jan 1, 2020

By Michel Carreau

Presentation topic Introduction to Renewable Power in Remote Mining Industry Trend What are the Challenges and How to address them Acceptability (Management Buy-in) ? RP not core business to mining company Significant upfront costs Project Risks - Technological and Delivery Wind and solar power variability Operating hybrid power (Operator Buy-in) Conclusion Introduction ? RP at Remote Mining Sites Mining Project Cost Energy represents 25% of mining project CAPEX Energy represents 25% of OPEX Diesel, HFO, ? cost : 30+ cents/kWh RP - Proven technology - Excellent track record ?Wind (20 years), Solar PV (10+ years)? Hundreds of GW installed ?Reliable, High availability, very small OPEX. ?Wind/Solar cost : 15 to 22 cents/kWh (with good resource) ?Potential 10% to 20% Reduction in net cost of energy ?Price certainty for 20 to 25 years

May 1, 2013