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By D. M. Wyslouzil

"This paper was prepared for presentation at the 16th Canadian Mineral Processor's Annual Meeting, Ottawa, Ontario, Jan. 17 to Jan. 19, 1984.This paper gives an account of the development of treatment procedures for the differential flotation of refractory copper-zinc ores. Special references are made to the effectiveness of various zinc depressants and their combinations.Studies carried out on refractory copper-zinc ores demonstrated that conventional zinc depressants such as cyanide and zinc sulphate were not particularly effective when secondary copper minerals were present in the ore; the flotation activity of sphalerite was enhanced in the presence of cyanide.Among the various zinc depressants evaluated, the following depressant combinations were found most effective: Zn(OH) 2-S02 , 802-CaO, Na2S-Na2S03-S02, Na 2 S-S02 and Na 2S-S0rDS22.The practical application of any of these systems depends on the type of ore treated and other conditions such as pH, levels and points of collector and depressant additions.In this paper the effect of each depressant combination on different ores is described with reference to the selection of collectors."

Jan 1, 1984

By George A. Lawrence, J. C. McHardy

"Field operating experience with an improved flotation mechanism for handling various flotation applications is covered in this paper. Some aspects of designing flotation machines are also presented. Operating data from extensive testing of commercial size equipment under actual plant operating conditions in the following applications is detailed:1. Copper Flotation2. Fine Coal Flotation3. Base Metal Sulfide FlotationDesign features, design improvements, modifications tested, and overall performance data are reviewed. Some mecl1anical performance data as well as metallurgical performance results are presented. Some comparisons with conventional flotation equipment are reported in this paper.Flotation sizing theories are reviewed and an actual equipment selection ex2.mple is presented. Scale-up criteria used for developing large cells are briefly covered.The paper concludes with a brief review of anticipated future flotation equipment design needs. IntroductionThe mining/milling industry is faced with increasing pressure to cut costs while maintaining product quality and indeed, in some instances, expanding production. For copper, nickel, iron, molybdenum, lead and zinc sulphides, coal, phosphate and some other minerals;, flotation remains the primary method of concentration and recovery of the valuable mineral away from the gangue. Cost reduction in flotation can be broadly focused on two areas:1. Flotation Chemicals2. Flotation Equipment"

Jan 1, 1985

By R. Grant, C. Bazin

"Brunswick Mining has investigated grinding media optimization for the purpose of improving the flotation feed and regrind product size distributions to enhance metal recoveries. This paper presents the findings of on-going testing of various sizes and shapes of grinding media. Plant observations combined with estimated breakage rates demonstrate the importance of appropriate selection of media sizes on the milling operation.IntroductionBrunswick Mining and Smelting is located near Bathurst, New Brunswick, and operates one of the world's largest lead and zinc mines. The ore mineralogy and processing flowsheet have been described elsewhere (Petruk and Schnarr, 1981; Shannon et 01., 1993). Despite the 25 years' milling experience, there has been considerable disagreement as to the required grind size (Grant et 01., 1991). Since 1964, fineness of the flotation feed ranged from 60% to 80% passing 400 mesh (37 um) and averaged slightly above 71% in 1992. Results from mineralogical analysis (Petruk and Schnarr, 1981), laboratory and pilot plant experiments, as well as plant sampling (Grant et al., 1991; Hendriks and Ounpuu, 1985; Shannon et al., 1993) indicate that improved metal recoveries can be achieved by an increase in the fineness of grind, and more specifically by maximizing the amount of material in the 15 urn to 25 um range.This paper shows the results obtained so far from the evaluation of the effect of grinding media size and shape on grinding mill efficiency. The problem of finding optimum grinding media size, shape and composition has been recogrtized since the early 19405. The main criterion for the selection of media size is the size of the material to be ground (Bond, 1958). Although several relationships have been proposed to assist in the selection of grinding media size, none of them are entirely satisfactory (Wills, 1988). Other approaches using the breakage rates and process simulators were developed to help in the selection of grinding media size (Austin et al., 1976; Lo and Herbst, 1986; Concha et 01., 1992; Samskog et al., 1990; Martinovic et al., 1990). Although considerable effort was put into the analysis of grinding media size, very little information is available on the effect of grinding media shape (Norman and Decker, 1985, p. 3C-4). Norris (1952), Kelsall et al. (1973) and Herbst and Lo (1989) have shown that balls are more efficient than other shapes of grinding media including truncated cones and cubes."

Jan 1, 1994

By F. Hassani, K. Moozar, J. Ouellet, P. Gauthier

"This paper describes a sudden spill of waste rock used for backfilling from a waste pass at an underground mine in Canada, thus causing a major failure/accident. The mine operator immediately launched a detailed investigation to understand the causes of this accident and develop procedures to prevent any recurrence of such events in the future. The authors from McGill University were invited to collaborate with the engineers at the mine to examine this accident. The events leading to the accident were studied, appropriate measurements were taken and samples of the waste material were collected for further testing and analysis.The field visit and the interview of the witnesses allowed the detailed documentation of the events. The sequence of events related to the incident, along with the experimental results obtained in the course of the investigation, are presented. The waste material was characterized in the laboratory with regard to its behaviour in the presence of water. This information is discussed and the failure mechanism involved in the accident is identified. Finally, the full recommendations as well as the immediate operational measures implemented by the mine to prevent the future occurrence of such events are presented and discussed."

Jan 1, 2004

By L. Lariviere, M. Grenier, R. Khalili, D. Shook

A mineral processing facility near Montreal, CEZinc, Noranda Inc., has recently implemented a leading-edge intranet solution for monitoring the performance of plant operations, and providing condition-based maintenance. This innovative multi-faceted software implementation incorporates: web-delivered plant information systems; area-wide control loop performance assessment (using sophisticated algorithms to evaluate poorly performing controllers); and integrated alarm management functions.The system has enabled a project to improve plant operations through better process control. Maintenance technicians, engineers, supervisors and managers all can see the performance of the controllers, and the performance of the plant itself, through webdelivered graphics and reports. Information is combined from many sources, real-time, historical, relational and analytical, to provide a complete picture of plant operation.The web-based solution centralizes the administration of user access, and simplifies the deployment of several different kinds of information to many desktops. It is an extensible system that allows users to create and share their own web pages and data views.The paper will discuss the solution architecture and the improvements the IT, operations, maintenance, and engineering groups have experienced, and overall benefits to the facility.

Jan 1, 2003

By R. O. Burt, D. J. Ottley

"SYNOPSISRecent developments in the use of the Bartles-Mozley table and the Bartles CTS screen are described for the gravity preconcentration of fine heavy mineral and metal particles present in low grade pulps. The B-M table is a relatively new device used for the recovery of particles of up to 100 micron size down to 5 microns or in the case of gold and platinum, down to 1 micron. The CTS screen is a wet screening device used for feed preparation ahead of the Bartles-Mozley table and will size effectively down to about 300 mesh. Results and operating data for a number of different materials are given including outline flowsheets; the effects of the major variables on the performance of the table are briefly discussed. The potential of the B-M table to treat a variety of different ores, coal, tailings, and waste products are considered. The utilization of the B-M table in association with other unit processes to improve overall results as well as to improve the economics of design and performance of plants are also mentioned.INTRODUCTIONA number of new gravity concentration devices have been developed in recent years for the recovery of fine heavy mineral and metal particles but for reasons which include low capacity, high capital or operating costs, competition from other and better processes, the absence of simplicity or reliability in operation etc., only a few which include the Bartles-Mozley table, have been proved to be of commercial application.The name of the machine is derived from the inventors name, Richard Mozley, who developed the B-M table at the University of Bristol in England. The table was subsequently taken up and patented, world-wide, by the National Research Development Corporation a British government agency. An exclusive license to manufacture the table was granted by NRDC to Bartles (Carn Brea) Ltd. in Cornwall, England."

Jan 1, 1973

By Ray Walton, Ron Colquhoun, Ken Thomas, Dwayne Fentie, Barney Burke

"The new Roasting Facility at Barrick’s Goldstrike Mine in Nevada, U.S.A. was developed to process 12,000 tons per day of refractory gold ore. The process consists of crushing, dry grinding, roasting, extensive gas purification, calcine quenching and leaching in the presence of activated carbon. The new plant is integrated into the existing Goldstrike facility, treating ore from both open pit and underground sources.The process design, procurement, construction and commissioning of the Roaster facility was performed successfully over a 3% year period with peaks of 400 engineering personnel and 950 construction personnel supporting the project. The US$330,000,000 project was completed ahead of schedule and under budget. The commissioning was well planned and proceeded smoothly through a rapid start-up to achieve all primary goals within three months of the start of processing of ore.BACKGROUNDAs early as 1992, Barrick’s Goldstrike Mine, located north of Carlin, Nevada had indications of the ore becoming ever increasingly carbonaceous in nature. As the open pit and underground exploration programs proceeded to step out over the years that followed, the accumulative amount of carbonaceous refractory ore and tons had become significant. By 1997, 29 million tons of double refractory carbonaceous ore containing an estimated 11.6 million ounces of gold had been identified. By 2000 the resource had increased to 14.3 million ounces."

Jan 1, 2001

By J. S. Stachulak, K. A. Mackinnon

This paper deals with specifying and evaluating fans for mine ventilation projects. Topics such as fan and equipment design life, operating points, and operating conditions are discussed. Common operating problems, such as vibration, parallel operation, mechanical failure, erosion, corrosion, and deficient fan performance are covered. Apart from identifying the potential operating problems, likely causes and suggested remedies are given. Fan type, fan accessories, and likely system effects and fan testing are discussed. Suggestions on what should be covered when evaluating different fan options and proposals and suggestions on the verification of supplier claims and guarantees, including cost of operation, the evaluation of initial capital cost, estimate on maintenance costs, and likely replacement expenditure over the life of the fans. In addition, fan reliability, operational flexibility, suggested construction details and fan vendor past history and experience are reviewed.

Jan 1, 2004

By Tim Hughes, A. H. (Sandy) Gray, Jennifer Abols

"The selective recovery of gold and silver from solutions containing other metals such as copper is possible using AuRIX®100 resin in conjunction with the Gekko Resin Column. Selectivity is driven by controlling the solution pH, which enables activities such as loading copper, gold and silver and then selectively stripping copper before gold and silver. Alternatively gold and silver can be loaded and the copper left in solution. The selective loading of gold while reducing the silver loading has also been demonstrated opening the possibility of producing high grade gold doré from high grade silver pregnant leach solutions. This paper reviews the AuRIX®100 resin and Gekko Resin Column Technologies, discusses the uses of AuRIX®100 in the recovery of gold and silver and the chemistry relating to several projects for which AuRIX®100 is being tested.INTRODUCTIONGekko SystemsGekko Systems specializes in the design, development and distribution of innovative mineral processing equipment and systems with a particular focus on gravity separation for the gold and diamond industries. The company, which has been around since 1996, has five main products: the InLine Pressure Jig, the InLine Spinner, the InLine Leach Reactor (ILR), Gekko Resin Column and Modular Systems.The InLine Leach Reactor is an intensive cyanidation reactor that uses high cyanide (0.5 – 2 % NaCN) and high oxidant (20 ppm dissolved oxygen as O2 or hydrogen peroxide) to dissolve gold from medium and high-grade gravity or flotation concentrates. The ILR, which typically replaces a shaking table in the gold room, is available in both batch and continuous models. There are 42 installations worldwide. Further details on this technology can be found in papers written by Gray et al (2003) and Longley, McCallum and Katsikaros (2003). By replacing a shaking table with an ILR, the overall gravity and plant recoveries can be increased significantly. Other advantages include reduced security risks, lower operating costs, reduced operator involvement due to the automatic process and increased safety for gold room operators."

Jan 1, 2006

By M. Poirier, J. H. Mbouche

"The research question of the present work is the following: at which speed should a rotary sample divider operate in order to produce representative samples of iron ore concentrate? In order to solve this problem, the representativity of a rotary sample divider treating iron ore concentrate from Iron Ore Compagny (IOC) Carol Lake mine in Labrador City was studied in the laboratory of mineral processing of “CEGEP de Sept-Îles”. The rotary sample divider speeds tested are: 20, 40, 50, 60, 80 and 100%. The results show differences in both weight and particles sizes distributions with respect to the various rotation speed used. 20% has shown to be the speed that generates an almost normally distributed samples for both weight and particle size. As the speed of the rotary sample divider increases, the polygon of frequency for weight distribution progressively becomes a two modal distribution curve. 40, 50 and 100% speeds generate normal samples distribution curves with respect to particles size only. 60 and 80% are the speed to be avoided since they generate multiple modal distribution curves for both weight and particles size.IntroductionIn the mining industry, samples representativity is part of the key elements for management decisions. In fact, “Sampling provides vital information to plant operators, clients and geologists to profitably run and operate iron ore mines and plants” (Kevin Thorne et al. 2007). At the laboratory scale, several types of techniques’ are currently used to perform sampling. This include: grapping, alternate spading, quartering, riffles divider and rotating divider etc.. Among all these instruments, rotary divider is the most commonly used. Nevertheless, the usage of a rotary divider is not a guaranty for samples representativity since the results have shown to be related to running speed of this instrument. For the present research work, the idea is to use iron ore concentrate to quantify the representativity of a rotary sample divider. In other words, the research idea is to determine the speed at which a rotary sample divider produces representative samples while treating iron ore concentrate from Carol Lake mine. The present report will give an overview of the methodology used and the principal results obtained."

Jan 1, 2016

Taking Up the AFN Corporate Challenge ?? About MAC ?? ?Towards Sustainable Mining? ??Mining and Aboriginal Peoples Framework ?? AFN-MAC Relationship ?? A New MAC Northern Initiative ??Social and Economic Progress ?? A View to the Future?

May 1, 2009

By K. E. Barnes

"The IsaMill was developed for fine-grained ores that required at least double the grinding efficiency of ball or tower milling to be economic. This was achieved, but in practice, the benefits of using inert media (eg sand, slag, ore, ceramic) have proven to be at least as important as the higher grinding efficiency. Flotation selectivity and rate was improved for all particles, particularly fines. This allowed a dramatic simplification of the Mount Isa lead zinc flotation circuit – adding 6 MW of ultrafine grinding power reduced reagent addition and flotation volume and increased plant energy efficiency. This was quite unexpected.This paper examines four orebodies that were enabled by inert grinding – McArthur River, George Fisher and Black Star Open Cut Mines (complex fine-grained lead zinc orebodies in Australia), and the Western Limb Tailings Retreatment plant (a PGM operation in South Africa). In a unique case history, the operating performance of the Mt Isa lead zinc concentrator is explained by size-by-size mineralogical data collected over 25 years, systematically explaining the impact of declining ore quality, and the effects of additional conventional grinding, inert grinding, and circuit and reagent redesign.The mineralogical case histories are so compelling that it is argued that the advantages of inert grinding should not be confined to difficult, fine-grained orebodies. The availability of largescale efficient inert grinding mills could have profound impact on circuit design for many orebodies.INTRODUCTIONThe IsaMill was developed by MIM (now Xstrata) to enable the development of the McArthur River Orebody in the Northern Territory of Australia. This ultra-fine grained ore needed a grind size of 80% passing 7 microns to produce a saleable concentrate. Such a fine grind was not economic with conventional ball or tower milling. Below about 25 microns the low energy efficiency and high media consumption of these mills is prohibitive. Critically, the high steel consumption and associated change in pulp and surface chemistry also seriously affects flotation metallurgy."

Jan 1, 2006

By Lewis Martin

Whereas many researchers and mine engineers have conducted tests using different types of grout, grout ratios, and physical modifications of the cable to determine cable bolt load characteristics, few studies have been conducted on cables fitted with internal instruments. Those studies that have been done have concentrated on cable behavior averaged over significant cable lengths. Researchers at the Spokane Research Laboratory (SRL) of the National Institute for Occupational Safety and Health in Spokane, WA, are investigating the physical properties of cable bolts by replacing the conventional king wire with a modified king wire on which strain gauges have been installed . This paper documents test results on these modified cable bolts. Three tests were conducted at SRL on 1.83-m-long cables grouted into two 0.91-m-long pull-tube assemblies. Load along the cable was monitored with 20 strain gauges installed along the length of the cable. The instrumented cable bolt provided reproducible point measurements of cable load as opposed to load measurements averaged over significant cable lengths. Such point measurements can assist in interpreting the influence of cable confinement, grout quality, rock mass stiffness, and other factors. The instrumented cable bolt is a practical field and research tool because it can predict point loading along the cable and thereby allow interpolation of maximum possible loads on a cable.

May 1, 2002

By G. Lipsett, S. Dessureault

Information technology (IT) initiatives in the past have tended to be sold on their ability to maximize resource output and return on capital by allowing assets to be used more effectively and efficiently. Many IT projects fail, not delivering return on their investment. This is known in the IT industry as the “productivity paradox,” where increasing investments in IT do not result in comparable increases in productivity. Experiences and studies of most business sectors reveal that this paradox is rooted in the false assumption that more IT spending automatically results in financial benefit, whereas the benefits are in how effectively IT is used. Most business sectors have accepted that re-engineering of processes is required to gain the full benefits promised of IT. A mining operation has organizational processes similar to most business sectors, but unique operational processes. The lessons of changing business practice in more common business processes, such as inventory control and customer-supplier relationships, can be adequately transposed into a mine setting. The unique operational processes in mines, in turn, require unique redesign efforts. Several enabling information technology opportunities have recently become available, such as more integrated mine production management systems and tactical manager training simulators. This paper reviews some of the latest IT products and outlines the processes and kinds of change that will be required in order to benefit from these new investment options.

Jan 1, 2009

By Chuck Edwards

Whatever your opinion of the validity of the scientific case for global warming, or of the wisdom of the Kyoto Protocol, it would seem judicious to err on the side of caution and try to sensibly minimize global climate change. To this end, we should take prudent steps to minimize our emission of greenhouse gases. Cameco is the world's leading supplier of uranium for use as fuel in nuclear power plants. Cameco’s uranium production fuels nuclear power plants in 16 countries. Nuclear power plants generate clean electricity without greenhouse gas emissions. This presentation describes the role that uranium and nuclear power can have in meeting the growing demand for electricity and at the same time combating global climate change.

Jan 1, 2004

By Donald Leroux, Colin Hardie

"New or improved mathematical models of mineral processing machines are published almost on a monthly basis. Often, these models can be calibrated from bench-scale test results and programmed using spreadsheet software to simulate different designs and operating conditions in open-circuit configuration. However, since mineral processing plants frequently operate comminution, separation and/or extraction machines in closed-circuit configurations, open-circuit simulations often have limited applicability.The simulation of closed-circuit configurations necessitates the programming of an iterative loop to bring the circuit to equilibrium. This can be done by using spreadsheet software but often requires advanced programming skills. As an alternative, LIMN® software, which simplifies the programming of closed-circuit configurations within spreadsheets can be used. This software was specifically designed to turn a Microsoft EXCEL® spreadsheet into a closed-circuit modeling and simulation platform with minimal programming.During the past few years, the Mineral Processing Group at the Noranda Technology Centre, has used this software for numerous projects which include the simulation of multi-stage cyclone circuits, closed-circuit regrinding and locked-cycle flotation tests. Using these projects as examples, the flexibility and the easy to use nature of the LIMN® software is demonstrated.INTRODUCTIONMineral processing engineers routinely have to make predictions regarding comminution and separation processes. Predicting the appropriate dimensions of equipment and the process response to changes in operating mode are probably the most common situations that they face. In all cases these predictions are expected to be rapid and accurate.Predictions made by engineers are frequently based on mathematical models. Many first principles, empirical, semi-empirical, steady state and dynamic models of mineral processes can be found in the literature. In fact, new or improved mineral processing models are continuously being proposed and in spite of this variety, process engineers often have to either develop their own or tailor existing models to suit their particular needs."

Jan 1, 2003

By S. Banisi, M Nesari, J. A. Finch, N. Nobari, H. Javani

"The flotation circuit of the Sarcheshmeh copper mine, which processes 40,000 t/d of ore at 0.9% Cu, consists of rougher, cleaning and recleaning stages. Mechanical flotation cells are used in all stages. To investigate the amenability of flotation columns in the plant especially for cleaning and recleaning stages, a column was designed, constructed, and installed at the Sarcheshmeh pilot plant. The pilot plant, which has an identical circuit configuration compared to the plant, can process up to 2 t/h of ore. The overall rate constant of the ore along with the target recovery of 94% were used to size the column. A 26 cm by 550 cm column with two filter cloth spargers and a submerged froth washing system using perforated tubes was constructed. To detect the interface level a 180 cm conductivity probe consisting of 1.5 cm diameter ring electrodes was installed. The tailings flowrate controlled by a variable speed pump was used as the main control variable. The initial testing program revealed that the optimum superficial gas and wash water flowrate were 1.5 and 0.3 cds, respectively. It was observed that the cleaning stage grade when using the column could increase by 2-3% at constant overall copper recovery.IntroductionThe Sarcheshmeh copper ore body which may rank as third or fourth largest in the world contains 1 billion tomes averaging 0.90 % copper and 0.03 % molybdenum. It is in located south-east Iran and has been processing 40,000 t/d of ore since 1982. After three stages of crushing, the ore with a F80 of 12.7 mm is fed to 8 parallel ball mills in closed circuit with cyclones to produce a product 70% finer than 75 microns. The concentrate of the first stage of flotation is reground and the tailings constitutes the main component of the plant final tailings. A concentrate with an average grade of 31% Cu (chalcopyrite and chalcocite) is obtained after cleaning and re-cleaning stages in mechanical cells. Total recovery of the plant varies between 83-87 % depending on ore type and operating conditions."

Jan 1, 2000

By Bruce Jago, Joe Zhou, Chris Martin

"From the perspective of metallurgical processing, gold ores can be classified into free-milling and refractory ores. Their extractive metallurgy are largely driven by mineralogical factors such as: gold particle size, association with other minerals, coatings and rimmings, presence of cyanicides, oxygen consumers and preg-robbers, presence of refractory gold minerals and locking of submicroscopic gold in sulfide mineral structure etc. Gold process mineralogy helps address issues and problems related to gold ore processing. It provides useful information on process selection, flowsheet development, recovery improvement and reagent consumption optimization. By combining classic mineralogical techniques, modern instrumental analysis and diagnostic metallurgy, the mineralogist is able to balance the various types of gold occurrence in an ore. This paper will provide a broad review of gold process mineralogy and the techniques available, and use case studies to describe how they can be used together, to provide the complete picture of gold process mineralogy in an ore. Examples will be used where applicable.INTRODUCTIONSince the early 1980’s, a great deal of work has been done in the characterization of gold ores, particularly refractory ores (Gasparrini, 1983; Wang, 1984; Hausen, 1985; Haines, 1986; Henley, 1989; Chryssoulis et al., 1990; Wang et al., 1992, 1994; Kojonen, 1999; Simon et al., 1999; Hong et al., 2000; Pals et al, 2003). Process mineralogy has come into its own as a respected inter-discipline in the fields of mineralogy and metallurgy – a subject that occupies an important place in both research and industry. As the free-milling gold ores are being depleted and more refractory ores are being discovered and processed, gold process mineralogy receives more and more attention from both the mineralogist and metallurgist as it helps to solve various problems encountered during gold ore processing. Steadily rising gold prices are also stimulating the need for gold process mineralogy due to the increasing demand for and production of the yellow metal. At SGS Lakefield Research, gold process mineralogy studies are conducted routinely on all types of gold ores and mill products to assist in a wide variety of metallurgical projects. This paper will briefly discuss the gold ore types and gold mineralogy, review the common mineralogical factors affecting gold extractive metallurgy and the techniques available to gold process mineralogy, introduce the procedure employed at SGS Lakefield Researc"

Jan 1, 2004

By J. I. Mathis

"The failure that was utilized for developing this model was a double bench-scale failure, approximately 20 m in height, in the Misery pit at BHP Billiton’s EKATI mine site. The bench that failed was excavated in biotite schist. Due to previous problems with bench-scale toppling failures, this bench was excavated with a 70° inclined, 30 m deep preshear. Upon exposure, the wall was very clean with half-barrels commonly observed from the pre-shear operation.In August 2003, a bench failure of about 1000 t occurred in this pre-sheared biotite schist (Fig. 1). Upon examination it was noted that the foliation that paralleled and dipped at 70° into the face when excavated was approximately horizontal at the top of the failure (Fig. 2). While the failure mode itself appears complex, the failure was apparently driven by three factors:• a low-angle, low-frictional strength fault or discontinuity at the base of the failure area;• water either contributed meteorically from precipitation and/or from permafrost melt; and• foliation planes providing a viable toppling geometry once toe block motion began to occur.The above details are illustrated in Figure 3.After considerable thought and analysis, a model was postulated for the failure.It is thought that the entire failure had been triggered by displacement of a toe block (Fig. 4). This toe block is bounded on the back by foliation, the bottom by a low-angle, lowstrength fault, and the front by the bench face. Water pressures behind the bench face developed forces on the block as can be seen in Figure 5. These forces were sufficient to induce block motion. As can be seen in the relative shear strength diagram in Figure 6, only a small amount of water is necessary in the face to initiate block displacement. Note that in this figure, a simplistic piezometric pressure distribution was assumed."

Jan 1, 2004

By S. Banisi, M. Pourkani, A. Kargar, D. Hamidi, M. Sarvi

"Flotation circuit of the Sarcheshmeh copper mine, which processes 40,000 t/d of ore at 0.9% Cu, consists of rougher, cleaning and recleaning stages. To study the stage recovery of copper, one of the eight identical flotation banks was selected for sampling. It was observed that 17% of copper goes to the tailings and the lowest copper recovery was for particles coarser than 105 microns. The third five-cell unit of this bank not only did not recover appreciable amount of copper but also decreased the concentrate grade. The grade of the last five cells was lower than the feed grade suggesting that mixing of the concentrates of the three units was not beneficial. To alleviate the problem, the concentrate of the first four-cell unit was directed to the cleaners feed box (i.e., by- passing the regrind mill). This increased the overall copper recovery by 1.7 %. Also rather than the current practice of adding the reagents only at the feed tank (i.e., 100-0-0%), various combinations of stage addition were examined. It was found that 75-25-0% addition regime could increase the total copper recovery by 1.3%. At the recleaning stage in order to increase the final copper concentrate grade, a froth washing system was used. To ease the maintenance of the system, a shower type washing system was installed. The optimum wash water superficial flowrate was found to be 0.06 cm/s. Continuos sampling of the recleaners with and without wash water over a period of two months showed an increase of 1.5% in the final copper concentrate grade at constant overall copper recovery.INTRODUCTIONThe Sarcheshmeh copper ore body that may rank as third or fourth largest in the world contains 1 billion tonnes averaging 0.9% copper and 0.035% molybdenum. It is located in southeastern Iran and has been processing 40 000 t/d of ore since 1982. The mine produces 100 000 tonnes of copper and 2200 tonnes of molybednite concentrate per year.After three stages of crushing, the ore with a F80 (80% passing size) of 12.7 mm is fed to eight parallel ball mills in closed circuit with cyclones to produce a product 70% finer than 75 microns. The concentrate of rougher flotation circuit is ground; rougher tails constitute the main component of the plant final tailings. A concentrate with an average grade of 31% Cu (chalcocite and chalcopyrite) is obtained after cleaning and re-cleaning stages. Total recovery of the plant varies between 83% and 87%, depending on operating conditions and ore type."

Jan 1, 2001