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By Craig Naudé

"An enhanced gravity concentrator was installed in conjunction with an Intensive Leach Reactor at the Sadiola plant in Mali last year and commissioned in Dec 2007.There has been much debate over the years as to the effect of gravity concentration on overall plant performance. The late Dr Laplante suggested that for every 10% of gold recovered by gravity, there was a corresponding 0.1% to 1% additional overall plant recovery. The results at Sadiola are consistent with this hypothesis with an overall 4% gain in plant recovery.With total gold recovery of 12% in the gravity section, grades are increased from 3.54g/t in the gravity feed to an average of 2 600g/t in the concentrator feed to the in-line reactor. The recovery of gold in the in-line reactor is in excess of 98.5%.This paper discusses the background to the project, the laboratory testwork prior to the equipment selection, the operational results of the system, as well as the benefits of the future application of high mass yield centrifugal concentrators in base metals, sulphides and industrial minerals. Bench scale, pilot scale and plant practice examples are also presented.INTRODUCTIONBesides picking nuggets off the ground or out of riverbeds, gravity concentration is arguably one of the oldest methods of recovering gold. In circa 6000BC people discovered that gold can be found behind the rocks and in depressions of creek beds. By placing rocks in a stretch of channel with the proper slope the first sluice is built, probably around 4,000 BC, and this method is still practiced today."

Jan 1, 2009

By B. Stimpson, K. Kosar, K. Barron

"A number of high wall failures have occurred in some of the Alberta coal strip mines of a type called by the authors ""Multiple block plane shear slope failure "". They cause rapid deterioration of the dragline bench, reduced productivity and maintenance costs.The failures are invariably associated with the presence of almost horizontal (± 5 degrees) bentonitic clay bands in the overburden, often immediately above the coal seam, and regress behind the slope as a series of tension cracks which isolate detached blocks. As many as 17 sets of cracks have been observed, at lateral distances in excess of five times the slope height from the toe.The theory of this mode of failure is presented and a limiting equilibrium computer program which will produce deterministic or probabilistic (Monte Carlo) solutions is briefly described. A case history of one such failure is documented. It is shown that the extent of the regressive failure is exceedingly sensitive to the water table elevation, leading to the conclusion that drainage, if practical, represents the best control strategy. IntroductionA number of high wall slope failures are occurring in some of the coal strip mines in Alberta of a type called by the authors ""Multiple block plane shear slope failure""(I). These failures cause a rapid deterioration of the bench from which the dragline operates, reduced productivity, and necessitate conregresses into the slope as a series of tension cracks and detached blocks. As many as 17 prominent cracks or crack zones have been observed, the last being in excess of five times the slope height distant from the toe.The block between each pair of cracks must be at limiting equilibrium, i.e. the factor of safety equals one. This condition can be used to determine the locations of the cracks which develop in sequence behind the face."

Jan 1, 1986

By Claude Bazin, François Robichaud

"The control of the operation of semi autogeneous grinding (SAG) mills is mainly achieved through adjustments of feed rate, water addition and speed of rotation. With the introduction of image based sensors it is possible to have on-line measurements of the size distribution of the ore feeding a SAG mill. This information could be used for the development of a control strategy to regulate a SAG mill feed size distribution to a set-point. The control of the size distribution is carried out by adjustment of the speed of the ore extractors underneath the ore stockpile. The potential and difficulty associated with the implementation of such control are assessed using a multivariable statistical analysis of data collected from the operation of the grinding circuit of the Agnico-Eagle Goldex mine in Val d’Or, QC. A control strategy for the ore feed size distribution is assessed using a simulator of the ore stockpile operation.INTRODUCTIONThe popularity of autogeneous (FAG) and semi autogeneous (SAG) grinding mills has been increasing over the last 20 years (Napier Munn et al., 1996). These mills use the ore or a combination of ore and steel balls as the grinding media. Since the ore is used as a media for the size reduction the mill ore feed size distribution impacts the performance of the mill. Several papers were recently published on this subject (Dance et al.,2011; Wennen & Murr, 2011; Dance & Valery, 2011; Allaire et al., 2011) showing the advantages of preparing the feed size distribution to maximize the circuit throughput or mill efficiency (Wennen & Murr, 2011; Dance & Valery, 2011; Allaire et al., 2011). With the availability of particle size sensor based on image analysis of the ore on a conveyor (Partanen et al., 2001; Bobo et al. 2004; Edwards et al., 2002; Wei & Craig, 2009) it is possible to control the size distribution of the ore feeding autogeneous or semi autogeneous mills (Partanen et al., 2001).This paper describes a method to control a size distribution index to a set point via the manipulation of the speed of the extractors that withdraw the ore from the stockpile feeding the grinding circuit. The paper consists of 4 sections. The first section describes the considered grinding circuit. A statistical analysis of the collected data on the grinding circuit is presented in the second section. This analysis demonstrates the necessity of using real-time adaptation mechanisms to develop a control strategy for the size distribution of a grinding circuit. The third section describes the method used to simulate the ore stockpile operation and the last section describes the preliminary development and assessment of a control strategy of size distribution of the ore feeding a SAG mill."

Jan 1, 2013

By Norman O. Lotter, Dominic Fragomeni, Lori J. Kormos, Guy Comeau, Antonio Di Feo

"A performance opportunity was identified for the Raglan concentrator operation by changing the selection of xanthate from Potassium Amyl Xanthate (PAX) to Potassium Isobutyl Xanthate (PIBX). This opportunity was identified by a Statistical Benchmark Survey of the operation and QEMSCAN measurement of these survey samples, in which fine liberated pentlandite was found in the final tailings. This was confirmed by some laboratory scale flotation testwork using High- Confidence Flotation Testing. A statistically designed plant trial was implemented in 2007 to measure and confirm the performance gain. This trial design used on-off switching following a three-month reference distribution of normal operations using PAX. This layout provided both external and internal reference distributions on PAX to be established. These were used to evaluate the internal reference distributions on PIBX. This trial format was deliberately designed so as to block out the effects of autocorrelation in the operations data. In this way, small but significant metal recovery gains may be measured and proven in a plant trial. The paper describes the case study to show that this approach successfully blocks out autocorrelation in time, which is an obstacle in analysing concentrator operations data. The results showed that the PIBX had produced clear and statistically significant recovery gains for Ni, Cu, Pt and Pd. Adjusted for feed and concentrate grades, these recovery gains were: Ni: 1.00, Cu: 0.96, Pt: 5.07 and Pd: 1.90%.INTRODUCTIONConcentrator OperationsMilling and flotation, sometimes accompanied by gravity separation, are well-established unit processes. These have traditionally been used to treat ore that has been mined, producing a lowbulk concentrate containing a high percentage of the paymetal(s) in the ore mined. These concentrates are more economically treated in subsequent beneficiation processes than the ore from which they were produced.This choice of a concentration process results in a significant and variable paymetal loss to the concentrator tailing. This tailing is discarded and disposed of in an impoundment area, and has no immediate business use. This paymetal loss forms the largest loss of paymetal in the entire flowsheet by which refined, or saleable, metal(s) are produced [Cramer, 2001]. The question arises as to whether any particular concentrator is performing at its full potential, and how this answer may be determined. In a concentrator operation, there is always an ongoing performance improvement programme for this reason."

Jan 1, 2009

By D. M. Doyle

"The Strathcona Concentrator operations, the application of control systems in the crushing, flotation and tailing fill sections, and current and future computer control concepts are described in this paper.The computer has been used for reporting and monitoring roles and operating the on-stream analyzer since start up of the mill in 1968, while over the past twenty months, it has been used for process control. The systems which have been developed include:1. The blending of pentlandite concentrate with pyrrhotite concentrate to produce a special product of constant nickel analysis.2. The blending of cement with tailing fill to produce backfill of consistent cement content.3. The supervisory control of xanthate, frother and pH to the flotation circuits to maintain the nickel copper concentrate grade within narrow limits.IntroductionThe Strathcona Concentrator is currently treating 7,200 tons per day of an ore which contains nickel associated with the minerals pentlandite (28 -32% Ni) and pyrrhotite (0.3 -1.0% Ni). The ratio of the nickel minerals varies from 4 to 15 parts of pyrrhotite to 1 part of pentlandite over the orebody. The production of a high grade concentrate re4uires the separation of this small quantity of .oentlandite from the much greater proportion of pyrrhotite and gangue and is complicated by the presence of two pyrrhotite minerals differing in nickel content, floatability and magnetic susceptibility."

Jan 1, 1974

By Shawn Healey, Ray Norcross

"Site IdentificationNew Britannia MineA 50/50 WX Gold Inc. - High River Gold Mines Ltd. Joint VentureTVX Gold Inc. is the OperatorLocationThe New Britannia Mine is located in the town of Snow Lake, Manitoba, which is situated between Flin Flon and Thompson, 420 miles north of Winnipeg.Brief Description of OperationNew Britannia Mine processes 2000 tonnes per day at an average grade of 4.5 g/t. Mill recoveries are currently 91 YO, accounting for forecast of 98,000 ounces for 1998.New Britannia Mine's mill complex incorporates conventional crushing, grinding and carbon-in-pulp technology. The design capacity of the New Britannia Mine mill is 1850 tonnes per day. The mill has processed upwards of 2300 tonnes per day, with no required upgrades.Gold recovery averaged 89.8% for 1997 compared to the planned 87% recovery expected from projected metallurgical test work. Year to date recovery mid December 1998 stands at 91.1 %Cash costs for the 1998 year to date were down to U.S. $221.49 per ounce, down 12% from the 3rd quarter of 1997. Milling costs for 1998 YTD were at Cdn. $9.38 per tonne and Cdn. $73.50 per ounce.Geology - (Orebody Description)The Snow Lake gold deposit is located within the Aphebian Flin Flon / Snow Lake Greenstone belt. This belt is composed of an assemblage of poly-deformed volcanosedimentary supercrustal sequences intruded by pre and sin tectonic ultra mafic and mafic intrusions and sin to post tectonic granitoid.The principal gold bearing rock at the New Britannia Mine is made up of quartzcarbonate material in sequence of basic and acidic volcanic rocks contained within a shear zone. The ore itself is gold associated with the sulphide mineral arsenopyrite and contains some pyrite, pyrotite, plus chalcopyrite. Proven and probable reserves at December 31, 1997 were at 4.04 million tonnes at 4.6 g/t and underground exploration continues to confirm the extension of the ore zones to depth."

Jan 1, 1999

By Chris Larsen, Carole Fortin, Dave Scott, Curtis Deredin, Ian Orford, Jean Guy Gauthier, Andy Trusiak, Lyne Côté, Mike Cooper

"Upon successful commissioning of the Stage Grinding Project (Cormier et. al., 2002), process improvements predicted through pilot plant testing were obtained in several flotation circuits, resulting in higher grades and recoveries for zinc and lead concentrates. Subsequent to establishing new baseline operating conditions from the Stage Grind Project implementation, additional opportunities were identified, and through the application of Six Sigma methodologies further gains were made. Six Sigma improvement projects were carried out in the copper-lead, zinc, lead upgrading and bulk flotation circuits. The overall performance increase resulting from incremental improvement projects has been substantial.Most remarkably, given the operational maturity up to the late 1980’s, the Brunswick concentrator team has continued to deliver a steady stream of major improvements over the past fifteen years. While senior managers and their programs have changed several times, there have been some critical constants over the long run. Common elements have been a commitment to team work, a commitment to recruit and maintain technical personnel, a structured business improvement framework supported organizationally by senior management, and focus on a few priority initiatives rather than trying to fix everything at once.The paper briefly discusses the longer term setting and then endeavors to illustrate, with examples, how improvements are presently achieved by applying the Six Sigma quality program.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is one of the world’s larger lead/zinc mines. Milling of ore began in 1964 from the No. 12 orebody, with an expansion in 1966 to accommodate ore from the No. 6 mine. In excess of 100 million tonnes have been milled to date. The concentrator employs differential flotation to produce lead, zinc, copper, and lead/zinc bulk concentrates. The ore is massive sulphide, with approximately 20% valuable minerals, 60% pyrite and 20% silicates."

Jan 1, 2005

By Gerardo Vargas

Without an adequate data sample there can be no Reliability Analysis (RA). Without analysis there can be no systematic, verifiable improvement in reliability or in operational economy. A sample is a collection of life cycles. A beginning and ending event define a failure mode life cycle. Well known obstacles impede the reliability engineer in his role to analyze maintenance data. The main problem lies in the difficulty to obtain analyzable data samples. Although modern Computerized Maintenance Management Systems (CMMSs) should provide the needed information they rarely deliver samples of adequate quality. Cerrejon, an integrated mining operation in Colombia, South America solved the information management problem by applying a "Living Reliability Centered Maintenance (LRCM)" process to its fleets of Trucks, Graders, Dozers, Loaders, and Shovels. This paper describes a method wherein completed work orders capture reliability analysis enabling information. The 'right' maintenance observations reference significant failure modes. Work orders link to records in a continuously growing Reliability Centered Maintenance (RCM) structured knowledge base. Grouped and filtered knowledge-to-work order links, being instances of failure modes, provide the samples required by reliability analysis software tools and methods. LRCM software and related procedures facilitate the growth of knowledge, manage the work order-to-RCM relationship, and generate samples for subsequent reliability analysis.

May 1, 2011

By Paul Hosford, Tim Haldane

"The paper describes the fast-track development of the project from feasibility study through to detailed design and construction, highlighting the process adaptations for handling sticky ore and water management in a tropical environment, and subsequent commissioning and operating experience of the mine. The paper discusses the geological setting, the environmental and socioeconomic considerations in developing and operating a mining operation in an underdeveloped country and the logistical challenges involved in bringing a large capital investment into Central America.INTRODUCTIONGlamis Gold Ltd. acquired the San Martin project in Honduras as a result of its merger with Mar-West Resources in late 1998. Despite the prevailing low gold price environment at the time of acquisition, Glamis anticipated rapid development of the San Martin project due to the quality of the deposit and other positive factors.Following favorable exploration and permitting activities in the first half of 1999, Glamis prepared a Feasibility study. In October 1999, Glamis decided to proceed with the development of the project and selected Hatch to provide the engineering, procurement and construction management services for the project. The San Martin project was in full-scale commercial operation approximately 14 months after the receipt of Board approval, and by July 2001 the San Martin project was operating at approximately 150% of its feasibility design capacity."

Jan 1, 2002

By James F. Archibald

In historic mining practice, typical thin liner support systems have been considered to comprise non-reinforced or mesh-reinforced shocrete linings. In the early 1990?s, development of alternate forms of liner systems was initiated in Canada which is now undergoing significant international growth in countries which sustain major mining activity. Now internationally designated as thin, spray-on liner systems, a wide spectrum of liner materials, ranging from liquid/liquid to liquid/solid component combinations, has become commercially available. This innovative family of products is characteristically identified as being rapidly deployable, capable of creating ultra-fast setting coverage over rock surfaces, and able to develop tenacious adhesion and pull strength capacities for resisting rock falls and movements. This paper presents a summary of current liner developments and use in principal mining districts world wide. Additionally, a database of material properties for principal product types used in mining and a review of common quality control testing procedures under development are provided. Such information is based upon recent Canadian and international efforts being taken to assess and develop user standards for the implementation of thin, spray-on liners as rock support in mines. This work is intended to continue for a period of years, with the eventual goal being to establish support and installation guidelines for mines based on quantifiable laboratory and field research.

May 1, 2002

By G. Hausen, H. Micka

"Modern signal and power electronics made adjustable-speed AC drives technically feasible and reliable and economically attractive. Cycloconverters are discussed as a proven technology for mine hoists. \IntroductionUntil rather recent technical and commercial advances in power and signal electronics, DC motors were used almost exclusively for applications requiring continuously adjustable operating speeds and torques. More recently, the significantly higher efficiency and the accordingly lower operating costs of AC motors gained importance. An effective and efficient speed control of AC motors requires the control of AC voltage and frequency. Table 1 shows typical applications of adjustable-speed AC drives.CycloconvertersOf particular interest to the mining industry are cycloconverters for hoist drives. The cycloconverter represents by far the simplest, most efficient and most economical means of converting a constant-voltage, constant-frequency supply into an adjustable-voltage, adjustable-frequency supply as required for the speed control of AC drives operating in the frequency range to half of the utility frequency.Cycloconverters feeding synchronous motors or induction motors are ideally suited for slow-speed direct-coupled drives."

Jan 1, 1988

By P. S. Capper

"Generally speaking, the most intensive efforts at dust control in the mining industry have, in the past, been concerned with underground operations and where uranium ore or high silica material is processed. In the past several years, Stoop Rock has made Intensive efforts to reduce dust levels in it's Iron ore pelletizing complex. There have been no great engineering break-throughs with regard to dust control in such plants, and certainly no new engineering techniques have had to be applied at Steep Rock. This paper deals with how significant improvements in dust levels have been achieved through minor modification to dust collectors and ventilation units, improvements in operating practices, and education of supervisors and hourly personnel.PROCESS DESCRIPTIONSteep Rock Iron Mines is located 120 miles west of Thunder Bay near Atikokan. (fig. 1) Run-of-mine ore is pelletized along with some -1"" concentrate that has been processed in the concentrator (a summer operation only), which utilizes gravity separation to upgrade a mechanical mixture of ore and waste."

Jan 1, 1976

By Xie Qiang

It is known that the stress state inside rock discs under Brazilian tests is neither simple compression nor tension, but a complex combination of both stress types, as well as for a beam subjected to bending, where compressive and tensile stresses are separated by the neutral axis. In this study, AE generation was obtained on pure white marbles from south Portugal that were submitted to both Brazilian and bending tests. Main questions to be answered were: (1) Does Kaiser effect exist in tests which create complex distributions of tension and compression? (2) Are there any meaningful differences in AE behavior of marble under Brazilian and bending tests?

May 1, 2009

By Jack J. Ayotte, Michael R. Nadon

"Today's demand for better and more efficient methods inspires new approaches to construction and mine development.A project at Asarco's Aquarius Mine provided a challenge that resulted in the adaptation of a civil construction technique to a mining application.This paper describes the construction of an escapeway shaft to surface from the mine's 150m level. The prime consideration was to provide the most cost-effective method of establishing a shaft collar in the 145 ft (44 m) of water-bearing overburden. This problem was resolved with the employment of the drilled in-caisson method.The remainder of the 500ft (152m) deep shaft was raise bored and portable hoisting equipment was used to install a permanentmanway and shaft liner.IntroductionHaving completed the first phase of exploration development in 1982, J.S. Redpath Limited was engaged to carry out an engineering and cost study to investigate the feasibility of re-opening Asarco's Aquarius Mine near Timmins, Ontario. The scheme was to develop the proven ore reserves and proceed with shrinkage stoping while carrying out further exploration development and diamond drilling.One significant and costly component of the project was the provision of an escapeway shaft to supply additional ventilation as well as a second means of egress from the mine. The major complication to this task was the presence of 145 ft (44 m) of water-bearing overburden at the site. The first and obvious approach was to use conventional ground-freezing methods as had been employed previously on .this property for the initial development shaft. This being the only ""sure"" method available at the time of the budget estimate, it was used as a basis for the study but its considerable projected cost and time demand inspired further investigation into other possible solutions.After considerable research and several brainstorming sessions, a Redpath team came up with an approach whose basic procedures had been used extensively in the civil construction field, although they were novel to the mining industry."

Jan 1, 1987

By Richard Morland

Some simple and fundamental objectives To challenge and inspire our people to embrace safety as a value ?A stand for safety as a value ?A stand for our people ?A stand by our people ?Prevent harm to our people ?Eliminate suffering for individuals, families, friends, colleagues

May 1, 2010

By Dara L. Hrytzak-Lieffers

Canada has long since been a place that has led the world in mining development, in a safe, clean, and sustainable manner. This has led to the integration of corporate social responsibility (CSR) philosophy in corporate governance, policy, and programming. The paper will identify the basis of CSR practise in Canada?s mining industry and provide a Canadian example of CSR implementation. Biography Dara Hrytzak-Lieffers is the manager, corporate social responsibility at Cameco Corporation. She oversees corporate CSR initiatives including the Sustainable Development report and public engagement programs. Dara received her BA in International Studies from the University of Saskatchewan and an MA in International Conflict Analysis from the Brussels School of International Studies. She is a recent graduate of the World Nuclear University summer institute.

May 1, 2011

By R. Clarkson

"The Yukon's numerous (185) placer gold mines are still a major social and economic force in this developing economy. Gold recovery at each of the various sluiceboxes is not optimized due to extremely difficult sampling logistics and a shortage of technical expertise and industrial research.At each of six operating placer mines, numerous sluicebox tailings samples were collected with hand held sample cutters and combined into large (2-7 cubic yards) duplicate samples. The entire sample volumes were screened and processed on a shaking table to determine gold losses. The existing and potential gold recoveries and recommended sluicebox design and operating parameters are presented.2 ACKNOWLEDGMENTSThe Project Manager gratefully acknowledges the following support for this placer research program:The funding received from the National Research Council's Industrial Research Program, the Canada/Yukon Economic Development Agreement and the Canada Center for Minerals and Energy Technology (CANMET): andThe technical advice provided by Tad Cienski (CANMET), Ron Johnson (KPMA), George Poling (University of B.C.) and Dan Walsh (University of Alaska).3 OBJECTIVESThe objectives of the Gold Recovery Project are to: evaluate gold losses with statistically based sampling programs; determine how to improve gold recovery; assist miners with the recommended technology and make this information available to the entire placer industry."

Jan 1, 1990

By D. Imeson, T. Grammatikopoulos, G. Pearse, M. Aghamirian, C. Mohns

"Spodumene mineral is a source of lithium for lithium ion batteries. Thus, the production of a spodumene concentrate with an approximate grade of 6% Li2O is targeted. Traditionally, spodumene is concentrated by froth flotation using fatty acid as the collector. Amine collector can also be used to float mica ahead of spodumene as required or feldspar from the spodumene tailings. Slimes have a negative effect on spodumene flotation and they are commonly separated by scrubbing and de-sliming prior to spodumene flotation. The main losses in spodumene flotation typically occur in cyclone overflow, scrubbing slimes, spodumene flotation tailings and mica concentrate. In recent years, dense media separation (DMS) is the main concentrating process in Australian spodumene operations. In these operations, DMS is efficient at generating coarse grain concentrates and rejecting large portions of silicate gangue, thereby directly reducing the milling cost. The ore should be crushed to 3/8” or coarser while further crushing is possibly necessary on the middling particles to scalp further spodumene. The DMS feed should be classified to remove fines (typically -0.5 mm particles). The final middlings and undersize fractions could then be processed by flotation. The main requirement in DMS operations is to have good spodumene liberation at relatively large grain size. This paper reviews the most significant DMS and flotation parameters in spodumene beneficiation. The treatments of different minerals in the spodumene ore are also addressed.INTRODUCTION A number of laboratory/pilot plant programs have been recently conducted at the SGS Lakefield site, sponsored by different clients. The main objective has been to develop a process flowsheet to generate a spodumene concentrate containing 6.0% or higher Li2O (~75% spodumene) suitable for producing lithium carbonate by a hydrometallurgical process. Depending on spodumene liberation size, dense media separation (DMS) can be an attractive option to produce a final high grade concentrate and to reduce the mass to be treated in the flotation circuit. In such a case, crushing would typically be performed in stages, with DMS separation to recover a spodumene concentrate and reject gangue minerals following each stage. DMS middlings and -0.5 mm fines can be processed by flotation to further recover spodumene. In the flotation process, coarse stage grinding minimizes the grinding cost and formation of slimes. In the majority of cases, a grind size (K80) of approximately 200 microns is sufficient for flotation. After primary grinding, mica, if present in an appreciable amount, should be floated to minimize interference with spodumene flotation. Desliming after scrubbing and high density conditioning are the key process operations prior to spodumene flotation. Spodumene can then be floated from silicate gangue minerals with a fatty acid or a mixture of fatty acid and petroleum sulfonate at slightly alkaline pH. Subsequently, feldspars can then be floated from the spodumene tailings."

Jan 1, 2012

"The success or failure of coal mining operations in Western Canada may hinge on the ability to extract thick coal under a variety of geological and mining circumstances and conditions. The paper presents, in who-where, what- how pattern, the current status of undergrounud mining of thick coal seams based on a review of foreign technical literature. The underground production of coal from what are considered to be thick seams is over 300 million tons per year. Methods of mining have evolved, through years of trials and tribulations, capable of meeting the requirements of a modern mine: high bulk outputs from a limited number of mining faces by concentrating in the horizontal (mechanization) and in the vertical (increased working lift)."

Jan 1, 1972

By Valentin Choquenaha Bombilla, Oscar Alvarez Muiloz

"Tintaya’s basic production line is copper concentrate, which has an important gold content. The process used is flotation; the objective of the metallurgical department is to obtain the best results in the copper recovery without neglecting the gold, using very specific reagents. Copper recoveries are considered high, nevertheless every day emphasis is placed upon increasing those recoveries. Regarding gold, optimum recoveries could not be achieved with flotation; and implementation of a gravity circuit was considered.According to microscopy studies, the coarse and very fine grains of gold in native form are lost to tails. The native gold due to its high specific gravity is concentrated at the underflow of the cyclone, remaining in the circulating load of the circuit. It reaches three times the concentration compared to the head grade entering the ball mills. This re-circulation generates very fine and laminated gold particles inside the ball mill, passing to the classification stage making a short circuit to the overflow of the cyclone.The very coarse gold particles as well as the thick flakes of gold do not react favorably to the conventional flotation process; thus studies that have included gravity separation have been conducted to increase the gold recovery. Part of the research included concentrating tables, jigs, and Knelson Concentrators. The Knelson Concentrator proved to be the best selection in terms of metallurgical performance and recoveries considering the throughput and operation conditions of the Tintaya Plant.The gravity concentration circuit with the Knelson Concentrator was commissioned in BHP Tintaya in October 1998, as per the flowsheet shown later on. Presently the global gold production surpasses any estimated expectations.Present efforts are directed towards showing the evaluation and optimization of the different parameters that govern the performance of the Knelson concentrator, as well as illustrating the difficulties and successes throughout the operating period.In the first year of operation 200 tons of gold concentrate have been produced with an average concentrate grade of 320 gramdton, having paid back in full the cost of the automated KC-XD- 48 Knelson Concentrator, the peripheral equipment, and the cost of the installation."

Jan 1, 2002