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By P. Amelunxen, E. Herrera, L. Hill, J. Vanderbeek

It is well-known that the particle breakage mode that occurs in a semi-autogenous mill is significantly different from that which occurs in a ball mill, enough so to warrant very different lab scale breakage tests and scale-up models. This phenomenon, at the plant scale, leads to changing process constraints depending on the particular properties of the ore. For example, hard or coarse ores might bottleneck the SAG/AG mill throughput, while the ball mills might constrain throughput when milling soft or fine ores. Because the power draw of a ball mill is fairly constant compared to that of a SAG/AG mill, periods of SAG/AG mill bottlenecks lead to increased ball mill circuit specific energy consumption and a finer grinding circuit product size, which together constitute a loss of efficiency of the overall process. Because HPGR circuit throughput is less sensitive to changes in ore hardness, this situation is less common or severe in those circuits. Furthermore, the ball mills are somewhat decoupled from the upstream crushing circuits through the use of surge bins, which also helps to mitigate this effect. As a result, ore hardness variability constitutes a significant cost penalty that should be applied to SAG mill/ball mill/pebble crusher SABC circuits when evaluating the relative economics of different grinding circuit configurations. Nevertheless, the issue is by-and-large ignored, because most current HPGR trade-off studies are based on averaged ore hardness parameters. This paper provides an estimate of the magnitude of this penalty for a typical operation by using Monte Carlo simulation methods and plant data from Freeport-McMoRan’s autogenous, semi-autogenous, and HPGR-based comminution circuits. A case study from an in-house 96K t/d sulphide project is presented to illustrate the concept. It was found that by including variability effects, the trade-off NPV of the HPGR circuit over that of the SAG mill circuit increases to $84 million from negative $33 million, effectively reversing the original decision of selecting a SAG mill circuit for the fixed hardness case.

Jan 1, 2012

By S. Caron, M. Bourassa, J. Châteauneuf, L. Tardif

"Since many years, the Yvan-Vézina gold plant custom mills and processes different ore types that show different behaviors. Because of this, cyanidation control is more complex than for a typical milling operation. In 1992, a Cyancor™ on-line « free cyanide » analyzer has been installed for monitoring and optimizing cyanidation. This implementation significantly reduced cyanide consumption for the overall cyanidation process. In order to further reduce cyanide costs, an automatic control strategy has been implemented to decrease fluctuations of« free cyanide » from their set points.This paper outlines the major steps of the project: process control audit, control strategy development, implementation and running-in period. Control strategy features include data filtering modules, adaptive PID algorithm and set points management modules are also presented. Finally, the strategy efficiency is illustrated with load-disturbance responses.IntroductionLocated in northwestern Quebec, the Yvan-Vézina plant has an average capacity of 1300 t/d using carbon-in-pulp technology. In 1991, the Yvan-Vézina gold plant was processing three types of ores (Beauchemin, Mouska and Silidor mines) and a pyrite concentrate (Beliveau mine). A cyanide reduction program was then undertaken to reduce « free cyanide» fluctuations <6>. To reach this objective, the optimum cyanide concentration was determined for each ore, a continuous monitoring method with the Cyancor™ on-line analyzer was developed and a tighter control of cyanide addition was applied. These modifications to the leaching practice significantly reduced cyanide consumption.After a while, it was observed that regulation of « free cyanide » concentrations could still be improved by the use of an automatic control strategy. Yvan-Vézina and CRM began collaborating in 1995 to develop and implement such a strategy. Results show that main disturbances of the circuit (e.g. ore mineralogy and pulp feed rate) can be significantly overcome in order to reduce their effects on the leaching operation."

Jan 1, 1998

By Tom Brady

A major focus of ground control research presently being conducted by the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) is to incorporate weak rock masses (such as are associated with operations in the Carlin Trend in Nevada) into existing design relationships. The original database that led to most of the empirical design relationships presently employed in hard-rock mining was derived from fair-to-good-quality rock. In this study, the relationship between weak rock quality and opening design (nonentry/entry methods) is being investigated. The common factor in all mines is a weak back or wall. This work attempts to provide tools that will enable a mine operator to make economic decisions that will also ensure a safe working environment.

May 1, 2003

By I. P. Swainson, A. Ilbagi, H. Henein

Powders of Al-50wt%Ni, Al-40wt%Ni and Al-36wt%Ni were produced using the Impulse Atomization technique, a rapid solidification technique. The molten droplets were cooled in-flight by the stagnant helium or nitrogen in the atomizing chamber. The resulting powders were sieved into different size ranges. X-Ray diffraction and neutron diffraction were used in order to quantify the phase fractions in the samples. The computer software GSAS was used to calculate the weight fraction of the existing phases, namely Al3Ni2, Al3Ni and Al, by profile refinement method. The effect of processing parameters, alloy composition and particle size will be discussed in this paper. In brief, no AlNi was found in any of the samples analyzed. Higher cooling rates resulted in the reduction of the ratio of Al3Ni/Al3Ni2. Also, at high cooling rates, Scheil closely predicted the ratio of Al3Ni/Al3Ni2. Some metastable phases were found in Al- 36wt%Ni.

Jan 1, 2010

By E. J. Marcotte

"BRIEF DESCRIPTION OF GRINDING CIRCUITCrushed ore at -5/ 16 in. is delivered by a conveyor system from the crushing plant to two 1250 ton fine ore bins. The ore is transferred from each bin by a 30 in. feeder conveyor belt, operated by a Link Belt P.I. V. (variable speed) drive, to a 24 in. conveyor that feeds the 8 x 10 Allis Chalmers rod mill.The rod mill discharges to a common mill discharge pump box. Three 6 x 6 SRL pumps are employed to pump the combined mill discharge pulp to a common distributor box which distributes the feed to two of the three Kreb D lSB cyclones in each of the two banks at a hydraulic pressure of 6 psi.The cyclone overflow at a specific gravity of 1. 25 (i.e. 32% solids) is transferred by gravity to two revolving chip screens for wood chip removal and from there to a pump box. Two 5 x 5 SRL pumps feed the pulp to the thickeners. The underflow from the cyclones is fed to two 8 x 8 Allis Chalmers ball mills which discharge to the common mill discharge pump box. Thus, a closed circuit is formed between the ball mills and their respective bank of cyclones. The circulating load as most recently calculated is 262%."

Jan 1, 1966

Inco Limited has been evaluating options for streamlining the overall flowsheet at its Sudbury, Ontario operations to improve productivity and to minimize the cost of at¬mospheric emissions reduction. Some of the flowsheets being considered include vari¬ous levels of copper/nickel separation at the Clarabelle Mill where all Inco&apos;s Sudbury Basin ores are processed. This paper reports on the laboratory and miniplant studies car¬ried out during the flowsheet development for a commercial Cu/Ni separation plant. There are two potential feed streams for Cu/Ni separation. It was determined that Cu/Ni separation from the rougher concentrate requires no regrind, and a very clean copper concentrate is produced, but the recovery of copper is limited to about 70% from ore. Cu/Ni separation is more difficult from the bulk concentrate because of the presence of excess flotation reagents in the slurry and due to locked particles. By replacing the slurry water with clean process water, and by addition of some hydrogen peroxide, entrainment is minimized and excess reagents are removed from the surface, providing a satisfactory separation of copper from nickel. Fine regrinding is required to increase liberation of the locked particles and to obtain 85% copper recovery with minimal nickel contamination of the concentrate.

Jan 1, 2005

By P. E. Cavanagh

Abstract Many investigators have been interested in developing some non-destructive method for detecting or determining the changes in physical properties in steel occurring during endurance tests or normal service life of a part which fails in fatigue. This paper presents a broad discussion of some of this work and the possibilities of developing useful test procedures based on some of the information obtained in the past. Changes in magnetic properties, electrical resistance, damping capacity, X-ray diffraction patterns, and remaining fatigue life at load different from service load have all been investigated as possible means for following the sequence of events during fatigue failure. In some special instances, tests such as these may be used to predict fatigue failure. As an in stance of practical application of the continuous determination of changes in magnetic properties during fatigue, a brief account is given of work done in non-destructive inspection of mine hoist-rope. As a result of extensive experiments and field crisis, it has been found possible to detect the beginnings of failure in a wire rope in service. The test method used will detect plastic deformation in a wire rope, no matter what its cause. There is no possibility of determining the remaining useful life of a rope by calibrating changes in magnetic properties in terms of remaining fatigue life. A change in magnetic properties at a point in a rope may indicate a decrease or increase in fatigue life, depending on the overload history of the rope. A continuing change in magnetic properties ac a point, however, does reliably indicate a developing weak point which will eventually lead to failure. The important point about any change in magnetic properties is not the magnitude of the change, but whether or not it continues.

Jan 1, 1947

By Patrick Andrieux

Cet article décrit une nouvelle méthodologie qui quantifie les chances de succès d’un sautage confiné à grande échelle de relaxation des contraintes dans un pilier de mine souterraine, pour un massif rocheux et un régime de contraintes donnés. La méthode est basée sur un nouveau paramètre nommé « Indice de relâchement », qui considère huit paramètres géomécaniques et de forage-sautage qui contrôlent ultimement le procédé. La rétro-analyse d’études de cas bien documentées a démontré que l’approche peut indiquer de manière fiable si une situation donnée de hautes contraintes de terrain est susceptible d’être améliorée par un tir de relâchement confiné à grande échelle et si le design proposé est adéquat pour atteindre ce but.

Jan 1, 2009

By Peter Heine

Diavik Diamond Mines Inc. (DDMI) has treated systems development as an integral part of the construction project when it built Canada?s second diamond mine. Fully aware that the proper collection and processing of operational data is needed to drive business decisions during production and planning, key Performance Indicators (KPIs) were defined to effectively manage operations when the mine went into production. The Production Information Management System (PIMS) allows KPIs to be measured, reported, and transferred to other systems in a reliable and convenient manner. PIMS provides a mechanism to collect real time production data from the various control systems around the site and acts as a tool to ?drill-down? and establish the important cause-effect relationships that impact the value of a KPI. Thus PIMS provides a data collection, storage, management, and an environment in which cause-effect relationships can be analysed and statistically verified. This understanding of the real cause-effect relationships, close to the source of the data and in the context of the operation, can be used to improve both operations and maintenance performance. The PIMS includes the PI Database implementation, its associated external interfaces with the various Control Systems, Cleaning Packaging Weighing System, Environmental System, Enterprise Asset Management (EAM) System, and Diamond Tracking System (DTS), as well as laboratory data collection, custom applications (downtime tracking, data reconciliation) and user clients. The interface with the EAM system provides material flow quantities and equipment availability on which the plant performance reports are based. The transfer of equipment usage to the EAM system is fed into the maintenance notifications and work orders functionality in the EAM. The environmental system interface provides the mechanism for capturing water consumption data required to generate the various regulatory reports. The interface to the cleaning-packaging-weighing system provides the mechanism for capturing batch data for transfer to the DTS for diamond product tracking at the production splitting facility in Yellowknife. The PIMS lab application provides a means of getting sample data into the system for critical metallurgical metrics, and the data reconciliation application provides a means of manually verifying the data before it is published or passed onto other systems.

May 1, 2003

Cambior has been involved in the Guiana Shield since 1990, first in Guyana and then in Suriname starting in 1994. This paper presents the history of Omai Gold Mines Limited in Guyana, where commercial production started in 1993 after an investment of US $150 million. In 1995, the mine was expanded in order to increase the milling capacity to 21,000 tonnes per day. After ten years of production, approximately 3 million ounces of gold have been produced. Building on this experience, Cambior became involved in Suriname with the Rosebel Project. A US $95 million pre-production program started in the fourth quarter of 2002, and the mine should be in commercial production early in 2004.

May 1, 2003

By A. G. Slade

"This paper deals with the direct application of rock mechanics in the underground mines at the Sudbury Operations of Falconbridge Nickel Mines Ltd. It covers mining methods, the use of photoelastic models, the fore-casting of rock strains and their elimination, closure methods and other common methods of ground control.INTRODUCTIONROCK MECHANICS IS A STUDY IN ROCK BEHAVIOUR and, although it is being termed a new science, it has been practiced since the industry began. Every person involved with rock excavations, from the mine superintendent to the stope driller, is actually practising rock mechanics. They probably call it by another name -experience, and applications of this knowledge are in evidence throughout the Falconbridge operations. Only in recent years have formal rock mechanics studies been employed to provide technical assistance to the mine operators in their primary objective of producing ore safely."

Jan 1, 1968

By Hökmark. H., M. Lönnqvist

"The Swedish Nuclear Fuel and Waste Management Company are planning to construct a permanent storage facility for high-level nuclear waste at about 500 m depth in fractured crystalline rock. One potential concern for the long-term performance of the repository relates to large fracture shear displacements, since these may damage intersected waste containers. Although details in fracture surface geometries are known to influence slip magnitudes and distributions, fractures are commonly approximated as planar features with lab-scale properties due to lack of relevant field-scale data and to limitations in available modelling tools. The purpose of the work described in this paper is to explore the possibilities to use the distinct element code 3DEC to generate and analyze models with isolated, non-planar fractures and, based on the results of such models, get perspectives on the influence of basic disturbances such as ridges, steps and waves. Given the model set-up, fracture segments with orientations deviating from the critical one will contribute to stabilize the fracture. As a result, all analyzed non-planar fractures slip less than the critically oriented planar fracture. We demonstrate that the angle of deviation is the most influential parameter determining the slip magnitude for comparable surface geometries. Similarly inclined steps and ridges have almost equal slip reductions despite differences in surface area restricting the movement. Although it may be possible to translate the influence of such irregularities to an effective coefficient of friction that could be used as input to models with idealized planar fractures, additional analyses with randomly shaped and distributed asperities, different fracture sizes and with alternative stress loads, need to be carried out to devise a defensible strategy for this type of parameter variation. INTRODUCTIONThe Swedish Nuclear Fuel and Waste Management Company’s (SKB) concept for deep geological storage of high-level nuclear waste is the KBS-3 method according to which the waste will be encapsulated in copper canisters and deposited, surrounded by compacted bentonite clay, in vertical deposition holes at about 500 m depth in fractured crystalline rock (SKB 2011). A site has been selected in the Forsmark area, which is located some 120 km north of the Swedish capital Stockholm. One potential concern for the long-term performance of the repository that has been identified by SKB (SKB 2011) is related to large shear displacements along repository host rock fractures induced by a nearby earthquake, since these may cause mechanical damage to intersected waste containers. Due to lack of relevant data at the appropriate field scale and to limitations in available modelling tools, fractures are commonly approximated as planar features with lab-scale properties. The standard numerical tool, 3DEC (Itasca 2013), used in SKB’s rock mechanics analyses, for example, generates planar fractures by default. Results from dynamic 3DEC earthquake-models (Fälth et al. 2010) currently provide input to layout decisions, i.e., the diameter of the smallest planar fractures that must be avoided when deciding on waste container positions at different distances from potential earthquake faults. It is, however, well known that fracture surfaces are rough or undulating on a wide range of scales (e.g., Candela et al. 2012) and that such deviations from planarity influence the mechanical behaviour of the fractures (e.g., Dieterich and Smith 2009, Marshall and Morris 2012, Ritz and Pollard 2012). It will probably never be a realistic option to attempt to represent the geometrical complexity of a population of fractures of different size, shape and surface structure in any large-scale rock mechanical analysis relevant for the performance assessments of the nuclear waste repository. It may however be possible to find approximate ways to represent different styles and degrees of non-planarity by assigning mod"

Jan 1, 2015

By J. Kuipers, R. W. Lawrence, P. B. Marchant, W. Brooks, J. T. Chapman

"Bioleach testing and piloting was conducted on refractory gold sulphide concentrate from Austin Gold Venture in Nevada during 1988. The objective of the test programme was to determine the technical and commercial viability of bioleaching as a concentrate pretreatment step prior to gold extraction by cyanidation. Baseline CIL cyanidation typically resulted in < 20% gold extraction from the Austin concentrate. Bioleaching enhanced gold extraction up to 95% using conventional CIL techniques. This paper summarizes the bioleach test programme and results, including pilot plant studies onsite, and describes the commercial design details for a possible retrofit of the Austin flotation tailings leach circuit to accommodate 20 tpd and 40 tpd capacity concentrate bioleach facilities.INTRODUCTIONBioleach testing on a refractory carbonaceous sulphide concentrate from Austin Gold Venture (AGV), was initiated in late 1987 as part of an ongoing programme at Austin to investigate alternatives to concentrate smelting. Preliminary batch biooxidation tests at Coastech indicated that over 90% gold extraction by carbon-in-leach (CIL) cyanidation of the bioleach residue could be achieved, compared with less than 20% gold extraction on untreated concentrate by similar CIL processing.Subsequently, a more rigorous laboratory study was undertaken at Coastech to establish continuous biooxidation operating criteria on a bench scale. The objective of continuous testing in the laboratory was to provide confirmation of enhanced CIL response based on continuous bioleach products and to determine key process operating and design parameters for pilot testing. The success of the laboratory test program led to the installation of a mobile pilot plant at Austin Gold Venture. The plant was operated by Coastech and AGV during 1988 to provide scaleup data and design criteria for commercial design and feasibility analysis. Based on pilot plant operating data, a detailed commercial bioleach plant was designed as a possible retrofit to the existing 1000 tpd CIL plant. Capital and operating costs were estimated to provide a commercial feasibility study of bioleaching as an oxidative pretreatment for Austin refractory concentrate."

Jan 1, 1989

By P. Reyes

The Codelco Chile El Teniente Division Caletones Smelter has an objective to smelt 1,250,000 tonnes per year of copper concentrate. This is a great challenge for the smelter facilities and particularly for the acid plants. The analysis ensuring that there are no obstacles to achieve the production capacity was of great importance. Therefore a series of activities were undertaken as well as studies dedicated to reach the target. This paper presents work focused on a fluid dynamic study, translated in an operation methodology of integrated handling of the smelting and converting gases with the objective to optimize the gas flow and S02 concentration. The optimization should be done employing the current installations, equipment and instrumentation and/or minor modifications. In the first part of the work the condition of the instrumentation involved in the gas handling was checked, improvements determined and the corresponding corrective actions were carried out. The proposed operation method consists of operation of the Cleaning Gas Plant 2 (TC&apos; s gases) and operation of Gas Cleaning Plant 1 (the remaining gas plus the gases from CPS). The implementation of the operation method involves the modification of the valve of the gas into the duct to plant 1 from On to Off to modulate flow. After modification a three days test was carried out. To evaluate the tests, a "Sulphur Capture" indicator was used. During the test the behaviour of the effluent treatment plants was closely examined. No problems or unusual operating conditions were observed. The reduced flow of gas to Gas Cleaning Plant No. 1 permitted the start up of the 2nd test day treating most of the gas received by Gas Cleaning Plant No. 2. The operation was carried out with the limitation not to increase the effluent pond level, which was maintained constant.

Jan 1, 2007

By J. E. Moran

A groupd of French capitalists, La Compagnie Française des Mines d&apos;Or du Canada, has undertaken the considerable task of developing Otter creek, in the Atlin district, B.C., by hydraulic mining methods. It has long been known that the gravels of this stream carry sufficiently high values in gold to make it attractive as a mining venture, but it was impossible to ignore the existence of formidable natural obstacles to hydraulicing them, and these needed to be taken into serious account before embarking upon any costly programme of development. The tide to the Otter Creek leases was originally held by Mr. H. Maluin, a French engineer well known throughout the north, to whom was to fall the task of financing whatever programme might be decided upon. It was he, too, who would have to assume the responsibility of finally passing judgment upon the practicability of the various devises for overcoming the adverse natural conditions. With an infinite attention to detail, which I believe to be a characteristic of the French people generally, he studied his problem and was finally able to submit to his financial backers a programme which left the very minimum possible to the hazard of accident or chance. Dr. Mandy, on his visit to Otter creek this season, expressed the opinion that our method of opening this difficult creek presented certain features which might be successfully applied in placer operations elsewhere in British Columbia, and it is largely for this reason that the present paper has been prepared. I shall set forth, as well as I can, the practices which have enabled us to overcome rather easily some of the obstacles which nature had unkindly placed in the path which we must take. The natural flow of water in Otter creek is far too little to deal success-fully with the rather excessive amount of glacial drift overburden which lies directly over the gold-bearing gravels. For this natural defect, the only remedy was to procure more water. This we have clone through a system of flumes and ditches, totalling between ten and eleven miles in length, which bring to the mine a supply of water adequate for our needs.

Jan 1, 1932

By K. Thuro, S. Schneider, H. Kasling, P. Ellecosta

"One of the most important methods for material testing is the characterization of the hardness, which is defined as the resistance of a material to the penetration of another one. The methods according to Brinell, Vickers, Rockwell and Knoop are today the most common and standardized tests for metal. As they are developed for predominantly ductile materials like steel, they can’t easily be applied to rocks which react much more brittle under indentation. But just as steel, rock is composed of different minerals and has a specific microstructure. Its mechanical parameters are connected with the particular grains, their cohesion and interlocking, just like steel.The abrasivity of rocks and the accompanied wear of drilling tools today are mainly determined by simple and fast laboratory tests such as the Cerchar abrasivity test or the rubber wheel test. Such laboratory tests are good tribological tests, but there are limits. The Cerchar abrasivity test for example has weaknesses in extreme cases, that mean soft or very hard rock types. This leads to an underestimation of abrasivity, e.g. in poorly lithified sandstones or very hard, fine grained and extremely abrasive rocks. As mentioned, hardness characterizes, depending on the type of deformation, predominantly plastic (metal) or elastic properties (rubber). Rocks are in the range between these two extremes. Since the rock drilling process can be seen as a kind of penetration process on macroscopic and microscopic scales, we picked up the idea to characterize the interaction of rock materials and TBM-disc-cutters with hardness tests. In addition, this supports for a better understanding of the wear process on disc cutters. We used the hardnessdisparity concept after Cardu & Giraudi (2012) because wear can be understood as the interaction between the wear part and the material which causes the wear (tribological system). Several rock-forming minerals and some fine to coarse-grained monomineralic and polymineralic rocks were tested. In contrast to Cardu & Giraudi, we used in the first step of investigations the method after Vickers with loads up to 294.2 N (HV 30), depending on the estimated hardness to get bigger indentations and therefore as well information about the cohesion and interlocking of the minerals/grains. We also tested several associated disc cutters. First results show that with higher loads (HV 5 - 30) and at least 15 indentations, we get a structural hardness in fine-grained rock samples, which allows a good characterization of the elasticity and brittleness. Nevertheless, for the coarse-grained rock samples we need up to 40 indentations for a good characterization. Using this method, a prediction of disc cutter wear is feasible taking into account the hardness of the disc cutter steel. In this paper, we would like to present this approved method in material sciences to derive an additional parameter for the characterization of rock abrasivity and wear."

Jan 1, 2015

By J. Mosher, G. Banini, J. Hollow, A. Villanueva

Prior to installation of High Pressure Grinding Rolls (HPGR) at PT Freeport Indonesia (PT-FI) a series of laboratory tests were carried out to determine the design parameters and also determine key performance indicators (KPIs) for the industrial unit. The design parameters derived from the lab test work were then scaled up to estimate the industrial capacity of the HPGRs to be installed. These parameters include specific power draw, specific throughput, and specific force, rolls speed, product size distribution and wear rate of the rolls. This paper compares the performance of the scale-up procedure against the installed industrial size HPGR. Overall, the specific throughput of the industrial size HPGR is higher by a minimum of 30% compared to the expected scale-up value. As a result of the high specific throughput, the specific power draw and grind sizes are below the scale-up expectations in the commercial application. The impact of these factors also contribute to a lower than expected wear rate on the industrial rolls. Installed rolls achieved a service life in excess of 18,500 hours relative to the target of 6,850 hours predicted from the laboratory testing.

Jan 1, 2012

By Nitin Bhavsar, Kaushik Vakil, Lakshmikanth Reddy, Sanjay Sarkar, Tathavadkar. Vilas, Bhavin Desai, Raghavendra Adiga

Gold and platinum group metals (PGM) do not dissolve in sulfate electrolyte from anode during electro-refining of primary copper. The PGM form solid ‘slimes’ which accumulates at bottom of the electrolytic cell. Typically, 8 to 10 ppm silver is present in copper cathodes, which is equivalent to almost 2% of silver loss during electro-refining. The silver can be cemented with cathode copper as soon as it is dissolved into the electrolyte from anode or during entrapment of slime particles in cathode. Over a period of time, the concentrates grade has deteriorated and change in type & amount of impurities in concentrate has resulted in higher silver loss during refining process. Therefore, an in-depth investigation was carried out in both fire- and electro-refining processes to understand the root causes of higher silver loss in copper cathodes. The detailed characterization and the plant data analysis were carried out. The results of study revealed that higher silver loss in 3rd crop cathodes as compared to 1st and 2nd crop cathodes from same anode. In anode silver was present in two forms, dissolved in copper (solid solution) and in slime phases such as Cu2-xAgxSeTe. SEM-EDX study of anode cross section confirmed higher silver and oxygen content in central region (core) of anode as compared that in both air and mold sides. This is due to non-uniform cooling of anode which was confirmed by the solidification modeling. Higher concentration of oxygen & silver at core of anode rised Ag+ concentration in electrolyte and slime particles during 3rd crop. The results of study were used to optimize the anode cooling process and also electrolyte chemistry to reduce the silver loss. The details of study carried out are discussed in this paper using the results of modeling, characterization and experimental studies. INTRODUCTION In the electrolytic refining of copper, fire refined copper anodes are used as raw material. Anodes contains copper of the range 99.5 to 99.6%, rest being the impurities. Hence, the purpose of the refining is (1) to remove the impurities so that final cathode conforms to the LME specifications and also (2) to recover the precious metal from the anode copper. When anode is dissolved, most of the impurities reports to the anode slime settled at the bottom of the cell, and rest dissolves in the electrolyte. Dissolved impurities remains in electrolyte and are removed during electrolyte recycling. However, sometime dissolved impurities and slime particles get entrapped in cathode due to disturbances in operational conditions. Metals dissolving in the electrolyte are the elements such as Ni, Co, Fe, Zn. The electrode potential of As, Sb and Bi being close to that of copper, these elements partly dissolve in the electrolyte. Noble metals like Ag, Au, Pt and Pd are generally insoluble and are thus expected to report to the anode slime. A small amount of the sliver content from the anode is dissolved in the electrolyte. Because the dissolved silver electroplates on the cathode at a smaller applied potential than copper, the cathode typically contains up to 8 ppm of silver. This is referred to as ‘silver loss’ in cathode (Cooper, 1987). Fortunately, silver is a rather benign impurity in copper due to its electrical conductivity being higher than copper. However, higher silver loss in cathode is loss of revenue for Copper smelter due to significant difference in their LME price.

Jan 1, 2019

By José Cáceres

Mine To Mill? ? Carlisle(1954) ?The economic of a fund resource with particular reference to mining?. ? Steine(1978) ?Coarser grind may mean lower metal recovery but higher profit?. ? Metalica (1999) ?Mine Plant Integrated Planning?. ? JK (2002) Mine to Mill Strategic Planning ? Camus, Kelebek (2002) ?Management of Mineral Resources: Creating Value in the Mining Business?. ? Caceres (2003) ?Integrating Milling Parameters in the Mining Planning?

May 1, 2006

By F. S. Hoseinian, M. Irannajad, M. Safari

In this study, the effect of chemical interactions of materials used in ion flotation on the removal of Ni(II) ions from low concentration synthetic wastewater was studied. Sodium dodecyl sulfate (SDS) and ethylhexadecyldimethylammonium bromide (EHDABr) as collectors and methyl isobutyl carbonyl (MIBC) and Dowfroth250 as frothers were used. To investigate the effective parameters and interactions of them, 16 experiments including 6 level variables were performed by supporting DX7 software and on the bases of 2-level factorial method. In the first step, the tests were conducted in a Hallimond tube. The result showed that collector of SDS and frother of Dowfroth 250 had appropriate interaction with each other at pH = 3. In the second step, optimal results from the first step were evaluated in a mechanical flotation cell. The removal of Ni(II) ions increased by increasing the time of flotation and they have a direct relation with the water removal. The kinetics study shows that the order and the rate of removal of the reaction do not follow any of the zero-order, first-order and second-order equations. The flotation rate curve on the removal of Ni(II) ions will divide the separation process to two stages, a fast flotation rate at the first stage and a slow flotation rate at the second stage. Ni(II) ions removal was obtained 88% at the best condition.This study showed that the use of ion flotation was a very effective method for Ni(II) ion removal from industrial wastewaters.

Jan 1, 2016