Search Documents

By Chris Bennett, Glen Kosick

"Process modeling and equipment sizing procedures for SAG circuits has advanced significantly over the past two decades. However, no matter how exact the hardness tests, models and scale-up calculations, if the ore samples being used for design do not accurately represent the orebody then major design errors can be encountered. This paper will describe a hardness testing method for identiQing the power requirement profile of an orebody, to an extent that design errors due to poor sampling can be greatly reduced or avoided altogether. It will provide some insight into the magnitude of hardness variability that can be encountered in an orebody. Finally, the paper will preview how detailed hardness distribution data can be incorporated into mine block models, to optimize SAG circuit design for an orebody, both fi-om a capital investment and throughput point of view.INTRODUCTIONIt has long been known that many SAG/AG' circuits experience wide swings in throughput. These throughput variations are almost always of a magnitude not anticipated in the plant design; consequently, they are detrimental to the expected return on investment for the mining companies. It is clear that the throughput swings are mainly caused by changes in ore hardness. In 1993, in an attempt to address this problem, MinnovEX began investigating the possibility of using a small scale SAG test (2 kg charge) to predict SAG power requirements from drill core samples. The objectives of the small scale test were to enable mining companies to do many more SAG hardness tests than currently undertaken for a particular orebody. To make this possible, the SAG tests had to use a minimal amount of sample, be cost effective, and give acceptable accuracy in the prediction of SAG power. If this small scale SAG test proved accurate, then the high sampling frequency would yield results that approach the true hardness distribution of an orebody. This hardness distribution could then be used to derive the distribution and variability of specific energy required throughout the complete orebody. This specific energy (kWh/t) can be thought of as the power required to grind one tonne of ore per hour (kW/tph) to a specified size. Once the true distribution of power requirement throughout the whole orebody is understood, the grinding circuit design team can make an informed decision regarding the hardness value that is most appropriate for sizing the SAG equipment. Throughput losses due to hardness variation could be deliberately planned for or avoided altogether (a capital cost decision)."

Jan 1, 1999

By Thomas Clark

This report presents a review of the distribution and exploration potential of platinum-group elements (PGE) in Québec; it is based on published and unpublished analytical data. This qualitative evaluation of the PGE potential, whether in PGE-dominant deposits or in Ni-Cu-dominant deposits with co-product PGE, is based on interelement ratios such as Ni/Pd, Cu/Ir, Cu/Pt, and Cu/Pd. Good PGE targets, i.e., deposits associated with magmas fertile in PGE, are identified. Less favorable PGE targets, i.e., deposits associated with PGE-depleted magmas, are also mentioned. The importance of exploring for deposits similar to those at lac des Îles and East Bull Lake (Ontario) is emphasized.

May 1, 2001

By Ilpo O. Auranen

Background: Mines of today are moving ever increasing tonnages of rock. The new ore bodies tend be of lower grade and located deeper in the earth?s crust. The industry?s focus to overcome this ?deeper but poorer? ore problem has traditionally been to lower the costs by increasing the scale of mining. This has resulted in an ever increasing size of mining equipment like drills, loading shovels, dump trucks. The main focus has been in reducing the cost per ton of mining. This cost focus has often resulted in increased waste rock dilution and more ore losses. From costs to value: Waste rock dilution means waste rock in the concentrator feed. It?s value in open pit mining is equal to the value of ore it replaces. In underground mining, waste rock dilution?s value is equal to the value of ore it replaces added to the costs of mining it. It is commonly accepted that waste rock dilution in open pit mining ranges between 5 and 20% and in underground mining between 5 and 40 % . In a typical large open pit mine ore value is from 20 to 60 USD per ton and mining costs are 1 to 3 USD per ton. One percentage point reduction in waste rock dilution represents savings corresponding to about 20% of total mining operation costs. The difficulty of reducing waste rock dilution comes from the complicated nature of the ores. Accurate ore waste-border detection has not been possible due to excessive costs. Core drilling combined with geochemical lab analysis is the most accurate method for locating ore waste borders. However, it is also expensive and time consuming, which is why it is often combined with somewhat lower cost methods like sampling drill cuttings from blasting drill holes or from reverse circulation drills and analyzing them in a laboratory. The main drawback with these methods, in addition high costs, lies in the sampling accuracy and in the quality control of the whole process when a large number of samples have to be handled manually. In every mine it is possible to halve waste rock dilution by using new on-line analysis technology .

Oct 1, 2009

By L. A. Kaufman

"AbstractThe Bureau of Mines, Ottawa, in conjunction with Eldorado Mining and Refining (1944), Limited, has developed an automatic concentrator for uranium ores.A brief review of radioactivity is given which shows the present limitations for obtaining •good results by electronic concentration. The ores after being mined, or at any other stage of a concentrating process, can be analysed for the uranium dissemination and from these results the possibility of an economical concentration can be estimated.The electronic and mechanical parts of the equipment are described. Difficulties in the operation's, and means by which they have •been and are •being overcome, are discussed. The capacity of the units, the results obtained, the man-power required, and other pertinent data are presented. Simple control analysis on the percent U3O8 has been developed.Research is continuing along lines to develop a more completely automatic unit using a scintillation detector, and applying a few new ideas and some devices that have been developed in colour sorting.IntroductionIt is well known how important the Geiger counter is in the field of exploration for uranium. It was in late 1946 that Dr. C. Lapointe, of the Bureau of Mines, Ottawa, first started work on an automatic picking unit to concentrate uranium ores. He used the principle that if a number of pieces of unknown ore, some of which contained uranium, were individually brought up close to a Geiger-Müller tube, then the pieces containing uranium could •be easily picked out due to their activity. Since then a good deal of work has been done by the Bureau of Mines in conjunction with Eldorado Mining and • Refining (1944), Limited, to develop an electronic concentrator."

Jan 1, 1950

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 Jacob Masliyah, Zhiang Zhou, Dharamdat Christendat, Tshitende Kasongo, Kevin Hyland, Zhenghe Xu, Ted Kizior, Douglas Cox

"A novel on-line visualization system, previously developed at Syncrude Canada Ltd., has been modified to characterize rising bubbles, particles and particle-bubble aggregates in a flotation process. With this system, the bubble size and rise velocity in a laboratory flotation cell can be determined. The technique allows the loading of solids on bubbles to be visualized, thereby providing an in-depth understanding of sub-processes of flotation. A step-by-step data processing procedure is presented. The applicability of the developed system to mineral flotation and bitumen extraction is discussed. Under batch flotation conditions in a laboratory Denver cell, three main bubble-particle attachment patterns are observed. They are: i) single particles attached to single bubbles, ii) particle aggregates loaded on single bubbles; and iii) a group of particles aggregated with a group of bubbles. The results demonstrate that the on-line visualization system is a powerful tool for understanding and diagnosing flotation processes.INTRODUCTIONAir (Gas) bubbles are an indispensable component in a flotation system. Both industrial practice and theoretical analysis indicate (Yoon, 1993; Diaz-penafiel and Dobby, 1994) that the size and population of bubbles are two important process parameters in modeling flotation. More recent investigations (Finch, et al., 1999; Gorain, et al., 1997) suggest that for a given flotation system, bubble surface area flux, defined as the air liquid interfacial area per unit time and unit cross-sectional area of flotation cell, showed a better correlation with the flotation rate constant. As a result, the bubble surface area flux is now being considered as a key parameter to account for the combined effect of bubble size and population in evaluating the performance of flotation machines and modeling flotation processes. However, the success of using bubble surface area flux in flotation process modeling largely depends on how accurate it can be determined or estimated (Finch, et al., 1999)."

Jan 1, 2000

By Ingrid Hann

The Triple Bottom Line ? Economic Sustainability ? Creation of Joint Venture companies ? Planned evaluation of other kimberlites ? Social Sustainability ? Impact Benefit Agreement and Participation Agreements ? Education and training initiatives ? Environmental Sustainability ? Environmental management ? Mine closure planning

May 1, 2008

By John Kostuik

"This paper discusses the outlook for uranium resources, and comments briefly on the measures needed to meet market objectives. Areas of recent exploration interest are also discussed.THE PREVIOUS SPEAKER has capably described the truly phenomenal growth in demand for energy from all sources. The basic factors -population growth and industrial development -which will create energy demand are so fundamental to national economies that the ascending energy demand curve will be little affected by short-term factors.Because of the economic and practical advantages of nuclear power and the degree of present acceptance by electric utilities, there is no doubt that uranium will be a principal source of primary energy in industrial countries -and this will happen within a decade. Indeed, during this period it will be the fastest growing source of energy, capturing, for example, more than half of the electric utilities' expansion in the United States by 1980. The ready availability of energy sources from domestic and foreign resources is so essential to industrial nations that the long-range outlook for their adequacy is of prime importance. There has been international concern about the availability of uranium resources at reasonable cost to adequately support and foster the development of the nuclear power industry. Canada, fortunate in having established reserves and a potential in excess of any forseeable domestic demand, can confidently look forward to being a principal supplier to the industry."

Jan 1, 1969

Stress induced, gravity-assisted failure processes typically dominate long before stress levels approach the strength of the intact rock (at approximately smax > 0.4UCS where smax = 3s1 ? s3 and UCS is the Unconfined Compressive Strength of the intact rock (Martin et al. 1999)). Under these conditions, discontinuities typically become clamped and the failure process becomes brittle. This brittle failure process is dominated by new stress induced fractures growing subparallel to the excavation boundary. While it is possible to identify areas with the potential for brittle failure, for example, using the general assumption that brittle failure will occur in areas at right angles to the major principal stress (Hoek et al., 1995), when the threshold smax > 0.4UCS is reached in areas around the tunnel boundary, or elastic modelling and the Hoek-Brown brittle parameters proposed by Martin et al., (1999) (i.e. m? 0 and s ? 0.11), amongst others, recent observations discussed by Everitt & Lajtai (2004), and Kaiser (2005; 2006) suggest that brittle failure processes are enhanced when structural features such as joints, weakness zones, bedding planes or foliations are preferentially orientated around the excavation boundary creating stress raisers which in turn facilitate the stress-driven rock mass disintegration process (e.g., as illustrated by Everitt & Lajtai (2004) on Figure 1b). Such weaknesses induce stress heterogeneities that thus promote tensile-spalling failure processes (Diederichs 2000). The observations suggest that stress induced damage can occur ?prematurely? depending on the orientation of micro and macro structures in situations where the known stress conditions should not yet initiate brittle failure processes. In general, when structural features (micro and/or macro), especially foliations, are present in a rock mass, the strength is effectively reduced, largely due to tensile strength heterogeneity in areas depending on the orientation of the structural features with respect to the excavation boundary. As a result, stress induced damage could occur in areas not normally considered due to the influence of anisotropy (Figure 1).

May 1, 2009

By A. R. Hekmat

Hypereutectic Al-Si alloys are used in applications that require high resistance to wear and corrosion, hardness and low coefficient of thermal expansion, To maximize the properties of these alloys, semi-solid processing can be utilized to modify the solidification structure of the primary silicon crystals as well as to reduce microsegregation and porosity, The transformation and spheroidization of primary Si crystals by shearing in the semi-solid state are not fully understood as they precipitate in the presence of other alloy phases, The objective of the present work is the determination the rheological characteristics of A390 (Al-17%Si-4,5%Cu-0.5%Mg) alloy using a Couette type (Haake RV12) viscometer and examining the microstructural evolution during continuous cooling and isothermal shear rate experiments, The effect of shear rate, solid fraction (temperature) and morphological evolution of the silicon crystals are investigated.

Jan 1, 2005

By D. Ling, Santos. R. M., T. Van Gerven, M. Guo

The valorization of alkaline waste materials from thermal processes utilizing intensified mineral carbonation routes is investigated. The principal advantages of this approach are the chemical stability and storage safety of mineral carbonates, the opportunities for process integration presented by the technology, and the potential for conversion of low-value materials into useful products. Treatment and disposal of steel slags are a costly burden on steel plants. Sustainable solutions for Argon Oxygen Decarbonisation (AOD) and Continuous Casting (CC) stainless steel slags and Basic Oxygen Furnace (BOF) steel slag are desired. An integrated on-site mineral carbonation approach is envisaged as a favourable solution.

Jan 1, 2011

By J. S. Roberts

"Campbell mines has been in operation since 1948. Part of the process consists of roasting of a flotation concentrate which contains arsenopyrite.At present operation level the milling rate averages about 850 t.p.d. and about 48 t.p.d. of concentrate is roasted. The gas emissions at present contain between 3 and 3.5 t.p.d. of arsenic trioxide, about2 - 2.5 t.p.d. of particulate matter and between 19 - 25 t.p.d. of sulphur dioxide. The particulate is extremely fine calcine dust and it assays about 4 oz. Of gold per ton.Until 1974 the gas was discharged untreated through a 125' stack.UntreatedThe decision was made in 1972 to erect a gas treatment plant, construction ran through 1973 and operation began in 1974. The cost of the installation was about 1.3 million dollars.On investigation the process technology, it was apparent that the plant operated by giant Yellowknife for the same purpose was the model we should study. I would like to acknowledge the fine cooperation we had from giant, the plant that emerged is very similar to theirs and incorporates some improvements suggested by them and based on their operating experience.The plant is designed to remove arsenic and solid dust and it has no provisions to remove sulphur dioxide.We depend upon the 125' stack to assure adequate dilution. Because of the nearby airport the stack cannot exceed 125'. A stack burner is provided that can ""y used to heat the stack gas and carry it higher into the atmosphere when there is an inversion condition.The removal of arsenic from hot gas is fairly simple. The sublimation point is about 425°f, a few degrees above this point the arsenic is a gas and a few degrees below it condenses into a solid form. The arsenic could have been removed by simply dropping the temperature below the condensation point and collecting all the solids in a baghouse. This would have removed the possibility of recovering the gold in the calcine dust and would have produced an impure and more bulky arsenic material to be placed in safe storage. The decision was made to collect the solid dust in a hot electrostatic precipitator operating above the sublimation point and subsequently lower the temperature below the condensation point and collect the arsenic in a baghouse."

Jan 1, 1976

By W. M. Armstrong, John A. H Lund

The paper describes an investigation of some of the tensile properties of single crystal vanadium, poly-crystalline vanadium and polycrystal-line tantalum, in the range of: W°C to -196°C. Techniques employed in the preparation and testing of specimens are discussed in detail. Some results of determinations of the temperature dependence of yield stress and ductility are given, and discussed in terms of the Cottrell-Bilby Theory of yielding. At subnormal temperatures, all the body-centred cubic transition metals in the Periodic Table exhibit; a) the "yield phenomenon" in tension, b) a strong temperature and strain rate dependence of yield stress, and c) a large decrease or complete loss of ductility. The yield phenomenon (existence of an upper and lower yield point) has been explained by Cottrell and Bilby ( 1) in terms of the dislocation-locking effect

Jan 1, 1961

By E. W. Williams

THE Ontario Research Foundation has developed a process for producing low-density steel shapes by direct reduction of iron oxide powders. The process is a combination of reduction, sintering (without compaction), and carburizing, and has been described by Cavanagh (1). Iron oxide powder, in the form of mill scale or highly concentrated iron ore, carefully sized, is poured into a porous mould. A reducing agent, generally coke breeze, is placed around this mould in a heat resistant sagger which is sealed off and heated to 2,000°F. for a number of hours. The coke/ ore ratio, the particle size distribution, the temperature and time of soaking, and the size and shape of the reduced product, determine the densities and carbon contents attained. The Defence Research Board sponsored a programme of research into some of the mechanical properties of the material (which was named Controlled Density Steel) and this paper is an account of various factors which govern the tensile strength of the steel. The ?practically attainable range of density is from 1.5 to 5.5 gm./ cc. but higher densities are obtained on hot working. This paper, however, is restricted to discussion of results for moulded products.

Jan 1, 1957

By M. Kane, B. Bissonnette, D. Hodouin

"A laboratory cell has been designed for a careful investigation of gold ore cyanidation using mathematical modelling of the process kinetics. The cell is a stirred vessel with continuous monitoring and control of pH, oxygen and free cyanide contents. Samples are automatically extracted for gold analysis. The instruments are connected to a microcomputer which records all the measured variables and calculates the reagent consumption (air or oxygen, cyanide, lime). For cyanide control a sample is automatically extracted and filtered and the solution analyzed, using a specific electrode, by a flow injection technique. The rate of gold dissolution is modelled using a kinetic model the parameters of which are calculated by a non linear least-squares technique. The parameters of an empirical model of reagent consumption are also estimated. The resulting model is used in a simulator for gold cyanidation plant design, tuning and control.INTRODUCTIONThe leaching of gold ores in a cyanide solution is the usual method for gold extraction from raw ores. This process requires long reaction times and leads to very significant consumption of cyanide. The optimization of the cyanidation plant operation is a very important aspect of gold ore processing for increasing gold recovery and decreasing operating costs. The key parameters to the improvement of gold extraction are the selection of an efficient solution chemistry, the design of the size and the arrangement of the equipment and the correct tuning of the operating variables. Automatic control strategies can then be applied to maintain industrial operations at their optimum setpoints.Two approaches can be used for optimizing design and control of cyanidation circuits, either empirical trials for improving process performances or mathematical modelling of the process kinetics for subsequent analysis, simulation and optimization. The advantages of the second approach, which is used in this study, is that it gives a systematic pattern to interpret data and reliable tools, in as much as the models are good, to improve operation performances. In order to determine the structure and the coefficients of cyanidation models, well controlled measurement and calibration procedures must be used. The purpose of the paper is to present an equipment and a test procedure for modelling the kinetics of gold ore cyanidation."

Jan 1, 1990

By V. I. Ryaboy, V. P. Kretov, I. V. Ryaboy, E. D. Shepeta

This paper studies the features of known and newly synthesized dialkyldithiophosphates and reagents with thioamide groups when separating copper-containing and arsenic-containing minerals in the flotation of skarn-scheelite-sulphide ore at the Primorskaya concentration plant. The optimization of dialkyldithiophosphate collectors was based on the study of their surface activity at the liquid-gas interface and estimated hydrophobic abilities. The flotation experiments show that the selectivity of action of the reagent increases with an increase of its surface activity and a reduction of hydrophobic ability when separating chalcopyrite and arsenopyrite. IMA-225-5 was proposed as a more efficient dialkyldithiophosphate collector, which increases the recovery of copper by 2.8% compared to the industrially used collector IMA-I413. Selection of the optimal structure for reagents with thioamide groups (derivatives of thionocarbamate and thiourea) was carried out according to their acidity and the presence of hydrophilic particles in their structure. Calculations were performed depending on the pH of the solution of chalcopyrite to determine the optimum reagent sorption and to further optimize the structures of these reagents. The tests with reagents with thioamide groups show an increase in copper recovery by 3-4% together with a significant increase of arsenic content compared to IMA-225-5. As a stronger collector with thioamide groups, it was recommended to use sample 234, which belongs to the thiourea derivatives. IMA-225-5 was recommended for industrial tests at the Primorskaya concentration plant. Thus, this study has shown that using dialkyldithiophosphate is more appropriate if it is necessary to increase the selectivity of separation of copper-containing and arsenic-containing minerals, and using reagents with thioamide groups, or their combinations with dialkyldithiophosphates, is more appropriate if it is necessary to increase the recovery of copper or the quality of copper concentrate with less selectivity of the process.

Jan 1, 2016

By Jirí Faltus

The paper deals with studying the impact of structural properties and anodizing of surface on the corrosion properties of extruded rods from commercial aluminium alloys: AA6082, AA6262, AA6012, AA2007 and new lead-free aluminium alloys AA6023, AA2015 and AA2111B. Samples were exposed to the corrosive atmosphere NSS, AASS in the chamber by EN ISO 9227. Surface of samples were either in the original state or anodizing by selected mode. The depth of corrosion attack and the form of corrosion attack are evaluated depending on the type of alloy, the metallurgical condition and surface treatment of the samples.

Jan 1, 2015

By Michael J. Lord, Richard H. O. Wagner

"The technologies used in the mineral processing of ores are being increasingly applied to the identification and remediation of metal contaminated industrial, military and landfill sites. The objective of mineral processing treatment of contaminated site material is to restore the value of the land and to concentrate the contaminants into a very small volume of separated material which, depending upon its nature, can be further processed, marketed, or sent to a landfill. A systematic characterisation of the site material is first undertaken. Bench and pilot testing follows to evaluate criteria for metal separation. The testing may examine one or more physical or physico-chemical reprocessing methods, singly or in combination, for the remediation of the test samples. These mineral processing tests determine the % metal removal fiom the soil and the contaminants concentrated from the medium. The usefulness of mineral processing testing for site remediation flowsheet design and execution is illustrated by the case studies presented. This paper will present the test results of three case studies: an industrial site decontamination, the cleanup of a small arms firing range, and the reclamation of property within a landfill.INTRODUCTIONEnvironmental legislation and our society’s quest for a cleaner environment has led to the application of mineral processing expertise and technology for industrial site decontamination, military site cleanup and landfill reclamation. Although the required level of decontamination varies between jurisdictions, a site becomes a candidate for decontamination once the contaminant concentrations are found to exceed the Canadian Council of Ministers of the Environment (CCME) Interim Remediation Criteria for soil (decommissioning guidelines) or applicable provincial guidelines. The objective of mineral processing treatment of contaminated site material is to restore the value of the land and to concentrate the contaminants into a very small volume of separated material which, depending upon its nature, can be further processed, marketed or disposed of in a landfill"

Jan 1, 1999

By Guy Chevalier, Jean-Guy Chartrand, Louis Barrette, Daniel Michaud, Michel Fortin

"COREM has developed, specifically for the mineral industry, a mobile laboratory using the Laser-Induced Breakdown Spectroscopy (LIBS) technique. It has been used to perform onstream analysis (OSA) of the chemical composition of slurries in both gold-ore and iron-ore processing plants. Industrial tests have been carried out respectively at La Mine Doyon (Cambior), a gold-ore processing plant near Rouyn-Noranda, Quebec, and at QCM's iron-ore pelletizing plant in Port-Cartier, Quebec. The aim was to demonstrate that the LIBS technique is capable of providing information that meets the needs for process control. C, Si, Ca, Mg, Mn and Al were the elements targeted on iron ore while Cu, Fe, Ag and Au were targeted for gold ore. The results obtained meet or exceed the requirements for process control and consequently clearly show that the LIBS technique is suitable for industrial applications.The feasibility of OSA, through in-plant validations using COREM’s LIBS mobile laboratory, has been demonstrated in four essential aspects: slurry sampling, LIBS chemical measurement, robustness for continuous operation, and functionality for industrial operators.INTRODUCTIONThere is a general need for optimization in the mineral industry. Process control is a favoured means to achieve this goal (McKee 1991). Real-time knowledge of process status is the key to effective control (Da Silva 1994). Only a few techniques, such as XRF, NMR and digital imaging, are currently amenable to chemically monitor industrial processes (Braden 2002). LIBS is an emerging technique with appealing characteristics for on-line and real-time measurement of bulk material (Lorenzen 1992, Palanco 2000). While our ultimate goal is to provide our industrial partners with performing monitoring tools, a shorter-viewed objective is to demonstrate the feasibility of developing a LIBS system for OSA. The LIBS technique has shown interesting capabilities for measuring solids, liquids, dusts and gases. Our work has focused on mineral slurries (Barrette 1999 and 2001, Turmel 1999). Special equipment is needed to perform in-plant validations. A mobile laboratory based on the LIBS technology has been assembled for this task."

Jan 1, 2004

By Dwight Newman

This paper discusses the author?s work identifying international law norms of consultation with indigenous communities and poses a potentially counterintuitive argument that corporate stakeholders? interactions with indigenous communities may have effects on the content of those norms. The claim is counterintuitive because the international law of pertinence is customary international law, which arises from consistent state practice and opinio juris (a belief by states that they are acting in a way they are legally bound to do so). Customary international law traditionally has no reference to corporate conduct per se. The paper first surveys several sources on developing international law on consultation obligations. Then it references the impact these norms can have on corporate stakeholders in industries like mining. Then, it poses an argument as to an economic ratcheting effect that can occur through various agreements between corporate stakeholders and indigenous communities that then feeds through into international law via several mechanisms. The consequences for mining companies are diverse and include the possibility that conduct by one company can have longer-term implications for the obligations of other companies and, indeed, of states. The effects will differ in the context of different competitive environments and may actually have effects on the economics of different competitive models.

Aug 1, 2013