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By Karl Dufresne

Blasting in geothermally high temperature ground and/or extremely reactive ground is an increasing common challenge for surface and underground mines. Many current PETN based non-electric and electronic detonators have manufacturer published in-hole temperature limits ranging from 55°C to 65°C (131°F to 150°F). When confronting blasthole temperatures above the manufacturer published limits, operations may request site-specific guidance and qualification for use. The advised safe loading window for in-hole PETN based detonators is often too short to be practicable for production blasting. To overcome limitations of PETN based initiation systems, surface mines with high temperature ground and/or reactive ground are known to load blastholes with a qualified high temperature bulk emulsion that are top primed with a cartridge of temperature qualified detonator sensitive emulsion plus an RDX detonating cord downline. As there is no in-hole delay detonator in this system, blasthole timing is accomplished with surface delays. Although this system is safe, top priming and surface delaying does influence floor quality and top size fragmentation, and safe loading windows times reduce blast block size and increase blasting frequency. A mining company with a site characterized by geothermally high temperature ground plus highly reactive ground employed a blasting system like the one described above. The site desires to improve blasting performance by moving to an in-hole delay initiation system that can withstand the site ground conditions. At the request of the mining house, DynaEnergetics developed an electronic initiation system for application in geothermally high temperature ground and/or extremely reactive ground conditions. The DynaEnergetics IGNEO high temperature electronic initiation system is rated for in-hole use in ground up to 150C (302°F) for 48 hours. The detonator consists of a high strength detonator with an HMX base charge and thermally resistant downline. To make up a primer, the detonator is inserted into a booster charge assembly that is fitted with a small HMX shape charge. This high energy primer is designed to be compatible and reliable for firing bulk emulsions, including those with high percentages of urea inhibition to combat reactive ground. Up to 1000 detonators may be programmed in 1ms increments up to 1500ms. The system is controlled by a digital firing panel that can be used with either a wired or wireless trigger.  The system enables high temperature and/or reactive ground sites to utilize in-hole delay initiation and realize the associated performance benefits. Conclusions and Future Work 1] The HMX based electronic initiation system permits bottom in-hole delaying in ground temperatures above 80°C (175°F). As compared to top priming and surface delaying, in-hole bottom delaying is known to improve floor quality, muckpile fragmentation uniformity and reduce oversize. 2] Field evaluation of the HMX initiation system at the Lihir Mine is continuing. 3] Work on the next generation of the HMX initiation system is underway and will bring with it expanded application range and flexibility. 

Oct 1, 2024

By E. V. Konopleva, H. J. McQueen

Steels in high variety have been providing strength and ductility for more than a century mainly through complex heat treatments following hot shaping. The economical and sustainable goal was a steel with the two operations combined through applying knowledge of dislocations and strengthening mechanisms aided by new mechanical and microstructural techniques. Primary hot reversing-mill rolling produced static recrystallization (SRX) between every pass to significantly finer grain size. Hot torsion showed that with lay-on temperature and rate of reduction suited to gradual precipitation of minor additions of Nb, the austenite grains would become highly pancaked; the existence of very fine subgrains along the grain boundaries (GB) could be deduced from tests on stainless austenite. The HSLA strip had to be water-jet cooled immediately to prevent SRX at austenite GB and ensuring complete transformation to ferrite avoiding grain growth after coiling. Confirmation on old mills and successful product led to the design of more flexible mills for wider range of compositions and products. A significant one was auto bumpers that reduced crash damage. More crack-resisting compositions were developed for strip welding into line pipe for arctic oil transport. Lower metal consumption and easier fabrication has resulted in more sustainable welded bridging.

Jan 1, 2015

By Fathi Habashi

The year 1987 marked the centennial of the beginning of modern hydrometallurgy. On October 19, 1887 British Patent No. 14174 entitled Process of Obtaining Gold and Silver from Ores was issued*. The discovery was made by John Steward MacArthur (Fig. 1), a chemist-metallurgist, supported and assisted by Robert and William Forrest, two brothers practicing medicine in Glasgow. The discovery was made in the basement of their clinic. The process, which became known as the cyanidation process in reference to the alkali cyanide reagent used, immediately received industrial success in New Zealand in 1889 and in South Africa in 1890t. It displaced the chlorination method which had been in use. In 1903 MacArthur was awarded the first Medal of the Institution of Mining and Metallurgy in London1131 - The cyanidation process was responsible for the doubling of gold production in the world in the two decades which followed its first application (Fig. 2). To the modern metallurgist, it may be surprising to think of MacArthur coming across an obscure reagent such as an alkali cyanide as a leaching agent for gold ores. It is the purpose of this paper to discuss the background and the factors that led to this invention, the development of the understanding of the process, and the application of modern technology.

Jan 1, 1999

By J-F. Turgeon, Y. Pépin, G. Hudon

The high temperature hydrochloric acid leaching of titanium slag in the QIT upgraded slag process (UGS) creates a harsh environment for materials of construction. Because of their excellent chemical and heat resistance, furan mortars are a key component in the lining system of the UGS pressure leach reactors. Similar products coming from different manufacturers have however shown unequal performances in service. In some cases, cracking of the brick lining has occurred during curing of the mortar. This study was initiated to investigate the impact of the curing conditions on the properties of carbon filled furan mortars. Laboratory tests were conducted to assess the effects of temperature and exposure to water and HCl solutions on mortar shrinkage and mechanical properties (tensile, compressive and bond strength). Three commercial furan mortars that have been used in the UGS leach reactors were thus characterized. Mortar properties were found to vary significantly among the products tested. Moreover, the curing conditions were shown to have a significant impact on mortar shrinkage and mechanical strength. The experimental findings provide explanations for the unequal performances of the mortars in service and for the problems of brick lining cracking that occurred in the UGS leach reactors. This study demonstrates that excessive mortar shrinkage compromises the integrity of a brick lining system.

Jan 1, 2004

By Amauri Garcia, Rodrigo Valenzuela Reyes, Noé Cheung, José Eduardo Spinelli, Leonardo Fernandes Gomes, Rafael Kakitani

"The present research work deals with directional solidification (DS) of both Al-15wt.%Si and Al-15wt.%Si-1.5wt.%Mg alloys and further characterization of the related microstructures. The growth of refined primary Si and refined eutectic is well-known as positive in order to improve mechanical properties of the Al-Si based alloys. Alloying is also an effective method to strengthen the Al-Si based alloys, in which Mg is considered an important alloying element. However, lack of investigation regarding the effects of Mg on microstructure of these alloys is noted. So, in the present research work emphasis is given on both dendritic and eutectic growth being affected by solidification kinetics (V-growth rate and G-thermal gradient) during transient directional solidification. Experimental evolutions of microstructural spacing of both alloys have been determined which becomes possible to understand the effects of Mg coupled with the effects of growth rate on the final microstructural arrangements. A direct comparison of the tensile mechanical properties obtained for the alloys is also performed. It is shown by these correlations that the addition of Mg generally improves the tensile mechanical resistance with a minor decrease in ductility. Furthermore, the Scheil solidification path of the ternary Al-Si-Mg alloy was determined using the computational thermodynamics software Thermo-Calc, resulting in the following sequence of precipitation: Liquid-Si-a (Al)+Si- a(Al)+Si+Mg2Si. This sequence is compared with the experimental microstructure findings.INTRODUCTION Al-Si alloys containing from 4wt.% to 22wt.% Si comprise more than 90% of all Al-based castings. Parts manufactured with these alloys have a wide range of industrial applications due to their excellent castability, crack resistance, good corrosion resistance, good weldability, low density and high strength (Bray, 1976; Zolotorevsky, 2007; Reyes, 2017). Hypereutectic Al-Si alloys are widely used and researched in the automotive and aerospace sectors due to the low coefficient of thermal expansion, resistance at high temperatures, good wear resistance and high strength (Reyes, 2017; Tebib, 2013). Above the equilibrium eutectic composition (~12.5wt.%Si) the amount of primary Si particles becomes significant (Lasa, 2003). In the place of conventional hypoeutectic Al–Si, there is growing interest in hypereutectic Al–Si alloys as a candidate material for the high-quality engines because a higher volume fraction of silicon may bring about superior properties (Matsuura, 2003)"

Jan 1, 2017

By Y. Q. Li, X. H. Long

In this work, structural and electronic properties of smithsonite (ZnCO3) and cerussite (PbCO3) as the typical lead-zinc oxide minerals is simulated by means of DFT. The calculated results could be concluded as: (1) The density of states (DOS) of Zn atom in ZnCO3 is nearer to the Fermi level than that of Pb atom in PbCO3, suggesting that the Zn atom of ZnCO3 is more active and easier to interact with water molecules and hydroxyl ions. Smithsonite, therefore, could be more readily depressed in the flotation process. (2) The bond population value of Zn-O (0.23) and C-O (0.92) in ZnCO3 is obviously larger than that of Pb-O (-0.01) and C-O (0.85) in PbCO3, indicating that the covalent characteristic of ZnCO3 is stronger than that of PbCO3. (3) It is shown that the charge of Pb (+1.32e) in PbCO3 is more positive than that of Zn (+1.22e) in ZnCO3, suggesting that cerussite is easier to interacting with HS- compared with smithsonite in the flotation process. In summary, the structural and electronic property of smithsonite is completely different with cerussite, leading to the difference of their flotation behaviour.

Jan 1, 2015

By Arthur Dubé

An account is given of the developments brought about in the last fifteen years by metallurgical research in the field of heat treatment of steels. The practical aspects of these developments are especially emphasized. Methods of representation of the phase-change during austenitizing and sub-critical transformation of austenite are described and the importance of time-temperature-transformation charts for the planning of heat treatment cycles is shown. Special copies such as retained austenite and internal stresses developed on quenching are also discussed in some detail. Due to the interest shown currently in these problems, it has been thought advisable to describe briefly the underlying principles and present some of the results already available.

Jan 1, 1945

By E. R. Weltevreden, C. Klauber, C. Vernon

"In this paper a review of the current status in recycling technologies for cathode ray tubes is given for both the glass and phosphors. Particular emphasis is placed on the opportunities for the recovery of the rare earth elements (REE) from the phosphor coatings. This is placed in the market context of alternative virgin sources and some of the advantages and disadvantages for REE waste recovery. Future opportunities are explored and also some experimental detail on a low cost leach system is presented. INTRODUCTIONThe disposal of cathode ray tube (CRT) based colour televisions has accelerated world-wide with the development of high definition flat screen panels. The total number of colour CRT televisions that have been sold in the United States in the mid-20th century is estimated to have been over 2 billion (U.S. Environmental Protection Agency, 2007), with high current rates of disposal. It is estimated that of the 20 million televisions annually discarded, 78% are send to landfill (Nnorom, Osibanjo & Ogwuegbu, 2011). However, this easily accessible item of electronics cannot only be turned into a valuable resource using the right recovery procedures, it can also prevent the substantial environmental contamination arising from improper disposal. In this review we focus on previous and current work performed on the recycling of CRT based televisions. Due to the increasing demand for rare earth metals, the main focus will be on the possibilities and challenges of recycling the fluorescent phosphor powders on the CRT’s panel glass.CATHODE RAY TUBE’S GLASS RECYCLINGConventional cathode ray tubes consist of three main parts, the panel, the funnel and the neck (Figure 1). To produce the different colours on the screen, the inside of the panel is coated with a matrix of hundreds of thousands of small phosphor dots. Each dot is one of three types of coloured phosphors, emitting either red, green or blue light. These emit light when excited by a beam of electrons generated by electron guns located in the neck of the CRT. These beams pass through holes in the shadow mask and excite the phosphor coating on the inside of the panel, to give light of variable RGB composition, see Figure 1."

Jan 1, 2012

By B. Holaday, H. McLaughlin

Orano Canada Inc. (Orano) operates the McClean Lake mill, located in the Athabasca Basin region of northern Saskatchewan. It processes high concentration uranium ore, delivered in slurry form from the Cameco Corporation operated Cigar Lake mine. After the ore slurry is leached at the McClean Lake mill, the leach residue solids are washed in a process known as counter-current decantation (CCD). This process uses six thickeners to facilitate counter-current washing of solids with diluted acid, flocculation and settling, as well as pumping the washed leach residue to the tailings neutralization circuit (TN), and the uranium laden aqueous to the solvent extraction circuit (SX). Challenges in settling the slurry in CCD started in early 2017. This is largely due to the variation in fines content of the slurry (D80≤75μm), and clay content. There are several changes that have allowed the mill to adapt to the evolving challenges of settling leached Cigar Lake leach residue. Flocculant selection and mixing, temperature effects, bed level management philosophy, and centre-well feed density are key parameters that have been explored as part of adapting to changes in Cigar Lake ore quality.

Jan 1, 2020

By M. Bustin, A. Hosseinian, G. Preisig

Hydraulic fracturing and hydraulic shearing techniques are essential for the development of unconventional oil & gas and geothermal resources. Such techniques will also play a key role in the development of CO2 sequestration, and management of high stresses encountered with deep mining. However, the optimal design of hydraulic injections is often limited by continuum treatments of the rock mass without consideration of the influence of the natural fractures present. These may interact with the hydraulic fracture to promote offsets or arrest, or may cause the natural fractures to undergo shear and dilation. Given the limited access to the rock afforded by deep boreholes common to oil & gas and geothermal projects, advanced numerical modeling is critical for understanding key mechanisms and interactions. In this work, we first present a coupled hydromechanical distinct-element model focusing on the propagation of a hydraulic fracture. Normal and shear displacements arising from the generated hydraulic fractures are subsequently integrated into a fracture flow model for detailed analysis of specific flow behaviour and fracture permeability. For this, a scanned 3-D profile of a natural fracture is used to correlate surface roughness to dilation as a function of shearing. Fracture flow is computed at different time steps corresponding to different fracture propagation states and geometries. Modeling results indicate that the opening of a tensile hydraulic fracture is accompanied by millimetre-scale shear displacements associated with slip and wedging between adjacent blocks. This may leads to a mismatch between the upper and lower walls of the fracture if asperities are irregular and strong enough. However, fluid-induced tensile fractures have low Joint Roughness Coefficients (JRC), and associated millimetre-scale shear displacements are too small to ensure a significant offset of asperities that prevent a fully-elastic closure when the hydraulic fracture is depressurized. Injection of proppant is thus critical to keeping hydraulic fracture apertures open. Future work is planned that will see the models calibrated against field data including microseismic event locations, magnitudes and source mechanisms, tiltmeter deformations, stress change, and pore pressures.

Jan 1, 2015

By Y. Yhang, D. C. Sego

ABSTRACT This paper evaluates the potential of freeze-thaw dewatering using Albian mature fine tailings (MFT). Freezing tests were first performed to study the effect of freezing rate on dewatering efficiency. Lower freezing rate resulted in higher thawed solids content and shear strength. Subsequently, large strain consolidation tests were conducted to investigate consolidation behaviour and how it is affected by freeze-thaw. The consolidation behaviour was presented in terms of effective stress versus void ratio and permeability versus void ratio. The results can be used to predict the field behaviour of Albian MFT and optimize the application of freeze-thaw for MFT dewatering.

Jan 1, 2014

By Brian C. Asbury

Gold-bearing quartz veins with auriferou pyritic wall rock alteration haloes at the Komis deposit near Waddy Lake in northern Saskatchewan occur in fractured Archean intermediate volcanic rock flanking a plutonic felsic intrusion. Three ore zones totalling 1.5 million tonnes grading five g/t gold have resulted from a combination of patterns of high density of fracture-filling quartz veins created by contrasting competencies of four predominant rock types and preferential gold deposition in magnetitebearing andesite host rock. Pre-glacial surface weathering remobilized gold from a nearby pyritized intermediateto- felsic dyke to form the EP Zone with a wide variety of supergene accessory minerals. Much of the EP Zone wa eroded by glacial action to forn1 a highly anomalous gold-bearing till dispersion train which facilitated its di covery.

Jan 1, 1986

By N. Schreithofer

The deposition of octadecylamine (ODA) at the KCI crystal/NaCI-KCI brine interface was investigated using atomic force microscopy (AFM). The AFM images of freshly cleaved KCI specimens immersed in KCI-NaCI saturated brine at room temperature reveal disappearance with time of the atomic steps and formation of cubic NaC1 crystals. These crystals were found to form when the specimen was withdrawn from the saturated solution. Depending on the way of contacting the specimens with the octadecylamine dispersion, the AFM images show huge differences in the deposition patterns of ODA on KCI crystals. Adequate dispersion was found to help the formation of quite even ODA coverage. The coverage was several monolayers thicker when air/brine/solid contact took place, suggesting that in the potash flotation the collector is likely to be carried to the solid surfaces by air bubbles. The presence of methyl-isobutyl carbinol (M IBC) enhanced the dispersion of ODA in brine, thus helping the spreading of the surfactant on the KCI crystal surface.

Jan 1, 2006

By D J. Murray

This paper outlines the principles of friction hoisting and the components involved, and gives a description of a specific mine hoist. Friction hoisting is compared with conventional drum hoisting, and the depth of shaft at which friction hoists become more economical than drum hoists, with respect to power consumption, is determined. Introduction T HE purpose of this paper is to outline the principles of friction hoisting, to describe the components and to show the advantages of multi-rope friction hoisting. Some calculations are made to show that the power requirements and the initial costs of friction hoists are less than those of conventional drum hoists, once a certain depth of shaft has been reached. The use of multi-rope friction hoists is gradually superseding the employment of the conventional drum hoist in many parts of the world. It results in heavier payloads from deeper levels, an increase in shaft safe-ty and a more compact installation for protection against adverse weather conditions. It was observed that where drums and friction sheaves exceeded 30 feet in diameter, a number of mechanical disadvantages were being experienced;

Jan 1, 1965

By A. B. C. Stothart

"IntroductionIn the past four years Ontario Mines have made great progress in the development of reliable mine conveyance safety dogs. History shows that, prior to 1945, a rope failure on a descending conveyance was usually followed by unsatisfactory safety dog operation.It is proposed in this paper to discuss briefly;The history of this development. Progressive .development of one type (E. Long).Free fall testing of safety dogs. Anti-trailing rope device.HistoryOn February 2nd., 1945, a hoisting rope broke at the Paymaster mine. The safety dogs proved ineffective and permitted the cage to crash through to the bottom of the shaft, with disastrous results.Following this accident, the Ontario Government appointed a Technical Committee to investigate The Safety of Hoisting Equipment and Hoisting Practice in Ontario Mines. This Committee consisted of Dr. C. R. Young (Chairman) and Professors T. R. Loudon, E. A. Allcut, V. G. Smith, and Lloyd M. Pidgeon. The Ontario Mining Association (at the request of the Ontario Government) also appointed a Committee consisting of Messrs. R. E. Dye, R. D. Parker, and R. L. Healy."

Jan 1, 1950

"The pressure leaching of alkali-pretreated limonitic laterite ore in nitric acid was studied. The optimal leaching conditions are as follows: leaching temperature of 458 K, initial nitric acid of 2.44 mol/L, leaching time of 60 min, liquid to solid ratio of 2:1 mL/g, agitation speed of 500 RPM. Under the above conditions, the extraction of nickel and cobalt can be achieved as approximate 95% and 80% respectively while that of iron is as lower as 1%. The leaching residue containing 70% of iron in the form of hematite and trace amount of chromium is suitable as the raw material for iron-making. The nitric acid in the leaching solution can be regenerated and further recycled to leach. INTRODUCTIONIt has been estimated that 60%-70% of the world land-based nickel resources presented in nickel laterites containing 130 million tons of nickel although these only accounted for about 42% of the world nickel production (Sudol, 2005; Luo et al., 2010). The nickel resource of laterite has not yet been fully utilized. Due to the increasing global demand of nickel and the declining global reserves of nickel sulphides, there is an increasing focus on the processing of the huge reserves of laterite ores today. Nickel laterite ores can be simply divided into two types, namely, silicate-rich and limonite. The former can be treated effectively by pyrometallurgical process in which the ferronickel product or nickel/iron sulphide matte is produced (Monhemius, 1987). The limonitic laterite is rich in iron in the form of goethite which is the main nickel-bearing mineral and usually contains cobalt associated with a manganese phase (Chang et al., 2010; Georgiou and Papangelakis, 2004). The limonitic laterite is usually processed by hydrometallurgical methods, such as atmosphere acid leaching (AL) (Xu et al., 2005; McDonald and Whittington, 2008), high pressure acid leaching (HPAL) (Chou et al., 1977; Georgiou and Papangelakis, 1998; Rubisov et al., 2000; Whittington and Muir, 2000) and reductive roasting-ammonia leaching (Caron Process) (Whittington and Muir, 2000; Valix and Cheung, 2002). The AL process can proceed at lower temperature, thus the operation costs may be very low. But two biggest problems associate with the AL process, namely, the slow rates of nickel extraction and potentially the significant amount of impurities such as iron and aluminum in the leaching solutions, which hampers the wide application of the AL process. The Caron Process uses the pyrometallurgical and hydrometallurgical methods together to obtain the metallic values, but the overall metal recovery is relatively low, especially for cobalt. In recent years, the environment-friendly process of HPAL has become increasingly important because it is most suitable for low-grade ores and leads to high extraction of the valuables. However, the HPAL process needs a much higher temperature and pressure (503-533 K, 4-5 MPa) to maintain a relatively fast leaching rates, which results in higher operation costs. Moreover, another serious problem of scale formation in autoclaves occurs in the HPAL process, for example, in Moa Bay, up to 20 cm scale may build up resulting in 5 days descale downtime per month. In addition, the iron residues cannot be utilized for ironmaking due to the presence of high content chromium (Ema and Harada, 1987; Owada and Harada, 1987; Takagi and Furui, 1987)."

Jan 1, 2012

By M. B. Shongwe, R. K. K. Mbaya, C. K. Thubakgale, P. Mendonidis

"A low-grade nickel-bearing ore was pre-concentrated on a SB40 laboratory model Falcon Concentrator. Three size fractions, -212+125, -125+75 and -75 µm were tested with the intent to upgrade the nickel content by reducing their content of fine silica, which becomes amorphous during leaching. Separation of silica from nickel-bearing magnesium silicate minerals; hornblende, clinochlore and talc, was more efficient in the finer particle sizes, -125+75 and -75 µm, and at high G-forces. For these two size fractions, nickel was upgraded from 0.06 to 0.07%, with a reduction in silica content from 52.12 to 50.71%. Leaching of feed samples prior to pre-concentration resulted in the formation of amorphous silica, indicative of the presence of fine silica in the samples. Leaching of nickel from the -125+75 µm fraction increased with increasing G-force and feed pulp percent solids, while that of -75 µm was not influenced. The optimum nickel recovery was 15.68% to the Falcon underflow, using the feed size fraction of -75 µm, 30 G and a feed pulp solids content of 10% solids, after 120 minutes of treatment.INTRODUCTION A low-grade South African nickel-bearing ore with about 0.06% Ni was previously studied for atmospheric pressure acid leaching using sulphuric acid. The study was motivated by the continuing search for methods to treat of low-grade ores, which appear to be an increasingly important source of valuable metals as a result of a declining production from rich sulphide ores. Nickel is a base metal that is used as an alloy in steelmaking and chemical industries because of its resistance to corrosion (Haudet et al., 2015). Nickel laterite ores with grades lower than 1.50% Ni are considered to be complex ores, accounting for 70% of the global nickel reserves (MacCarthy et al., 2016). Their complex nature may be attributed to the indefinite mineralogy of these ores, in which nickel may occur in more than one mineral host. In some cases, nickel may be finely disseminated in the ore. The grade of such an ore and complex mineralogy do not justify the application of pyrometallurgical methods for extraction of nickel (Zhu et al., 2012). This suggests that there is a need for less expensive alternative methods of extraction. This study investigates the application of centrifugal gravity concentration, using the Falcon concentrator, followed by leaching to determine the effect of pre-concentration of the ore prior to extraction by atmospheric pressure leaching with sulphuric acid."

Jan 1, 2017

By Lucien Piché

"IN any opportunity such as I am now given, I suppose that one should not fail to say that what the world has to offer to this year's graduates in science and in engineering is the greatest promise ever held out. High-ranking new scientists and engineers -particularly those with the Ph.D. degree -find themselves in an apparently delightful situation; the glow of attention that surrounds them and the dazzling starting salaries that are offered to them may indeed be turning their heads a bit and the attitudes of some of them are sometimes expressed with a smugness that can find its equivalent only in freshmen. On the average, however, the new graduates are, without any doubt, the best trained ever, or at least they have been the most expensive to train in the universities.There appear to be exciting opportunities for competent, well-trained and educated scientists and engineers far beyond the numbers that can be annually produced, and the demands for excellence in depth as well as in breadth of training probably will continue to increase for many years to come. The problem is visible all around us in Canada that there is much more money to buy brains than there are brains to be bought."

Jan 1, 1966

By J. A. Drozdiak

In this paper we examine, through pilot-scale testing, the possibility of operating a circuit comprised of two stages of HPGR comminution, followed by grinding through a horizontal stirred mill. In order to assess whether the novel circuit design could achieve the reduced energy requirements indicated in the literature, two more-established circuits, a cone crusher / ball mill and an HPGR / ball mill, were examined using a combination of testing and flowsheet simulation. The results showed that, based solely on the specific energy requirements for comminution, the HPGR / stirred mill circuit achieved a reduction of 9.2% and 16.7% over the HPGR / ball mill and cone crusher / ball mill circuits, respectively.

Jan 1, 2012

By Matthew Novak, J. Brent Hiskey

It is well known that when chalcopyrite is put in direct contact with copper in an acidic medium a galvanic cell is created. Chalcopyrite is reduced to iron and sulfur deficient defect phases such as bornite, chalcocite, and at very low potentials to elemental copper. Galvanic conversion experiments were performed using three chalcopyrite concentrates. The first chalcopyrite contained less than 10% impurity phases. The second concentrate had a high concentration of pyrite, and the third concentrate had a high concentration of pyrrhotite. The effect of temperature, acid concentration, chalcopyrite grain size, copper grain size, and agitation on the rate of chalcopyrite conversion was studied.

Jan 1, 2014