Search Documents

By Charles "Chick" Rodgers

"The Key Lake uranium mine is the largest single uranium producer in the world. It is owned 2/3 by Cameco Corporation and 1/3 by Uranerz Exploration and Mining. Cameco is the operator. Current production is fourteen million pounds per year of uranium oxide (U308).The mine's location is 570 kilometres north of Saskatoon on the southern edge of the Athabasca Basin approximately at latitude 57° 11 'north and longitude 105° 34' west. Access to the mine is by an all-weather road and a private airstrip.The mill was commissioned in 1983. A molybdenum plant was constructed in 1989 in response to increasing molybdenum content in the yellowcake or final product. Early test work had showed that the first ore body to be mined, the Gaertner deposit, would present few problems with regards to molybdenum in the product. However, the test work also showed that the higher molybdenum content of the Deilmann ore, the second Key Lake orebody to be mined, would result in increased molybdenum concentrations. Without the molybdenum plant, penalties would become excessive and some product might not accepted by the refineries.This paper will describe the current Key Lake mill process with emphasis on the molybdenum solvent extraction process. It will cover the chemistry of the process, process development in the mid 1980's, and current operating practices.The Key Lake milling process consists of five individual plants, crushing and grinding, leaching -counter current decantation (CCD), solvent extraction, yellowcake/crystallization and bulk neutralization (Figure 1. Simplified Mill Flowsheet). A detailed mill flowsheet can be found in the appendix."

Jan 1, 1996

By Karla Kaboth, Brad Garraway

"The surface of many concentrate thickeners has traditionally looked like that of a flotation cell. Over the last three years Normandy Golden Grove Concentrator, in partnership with Outokumpu Technology have developed and implemented an innovative breakthrough deaeration technology to address this problem.When installed in the thickener feedline, the system successfully detached air bubbles adhering to the solid particles and removed air bubbles from the feed stream, subsequently presenting a fully deaerated feed to the thickener feedwell.Tests to date have shown an 80% reduction in overflow solids. As a result, costs associated with concentrate loss and measures to recover concentrate that settles in process tanks and ponds have been minimized.MOTIVATIONIt is recognised in mineral processing operations that the entrainment of finely divided air in thickener feeds can cause significant problems in the operation of a thickener. This is particularly the case with thickening of flotation concentrates, in which air bubbles are strongly attached to the mineral particles and are difficult to remove. Such particles attached to fine air bubbles rise to the thickener surface, and hence over the weir and into the thickener overflow. High solids carryover can lead to a direct loss of mineral product, and if the product settles in process water tanks and ponds, the recovery of this product by means of intermittent dredging operations is usually expensive and inconvenient.Many concentrate thickeners are fitted with devices which attempt to alleviate this problem. Froth rings or baffles, skimmers and froth sprays, all play a part in reducing the amount of solids carried over into the overflow. However, many froths are very stable and persist despite these measures. In the worst cases, a thick froth layer forms which builds up to a depth greater than the froth ring, and hence may overflow or pass beneath the ring . Any concentrate that finds its way past the froth ring can also cause blockage of the overflow weir and launder, and has the potential to upset clarification performance by cutting off sections of the overflow handling system. The formation of a froth layer on the thickener also makes it more difficult for the operator to monitor the clarification performance."

Jan 1, 2001

By C. Larsen, E. Goodwin, E. Konigsmann

"This paper describes the development of an innovative effluent treatment process for cyanide and heavy metal removal from tailings wastewaters at Hemlo Gold Mines Inc. Golden Giant operation.The importance of minimizing dissolution of contaminants in the gold leaching circuit is discussed, as well as using recycled water in milling circuits to the fullest extent possible. Finally, a brief description of the role of natural cyanide degradation in the tailings pond is provided.Emphasis is placed on the need for overall water quality management to ensure minimum effluent treatment process costs and complexity while producing excellent quality effluents.1.0 INTRODUCTIONHemlo Gold Mines Inc. owns and operates its Golden Giant Mine located forty kilometres east of Marathon, Ontario. The Golden Giant mine is one of three gold operations exploiting the large gold orebody located in the Hemlo area. The milling facilities include two stage secondary crushing, three stage, closed circuit ball mill grinding with no reagents, thickening, cyanide leaching and carbon in pulp gold recovery unit operations. The average throughput is 3000 tonnes per day of 10 grammes per tonne gold ore. Figure 1.1 shows a schematic flowsheet of the operation."

Jan 1, 1989

By B. K. Gorain

"Mining of low grade deposits along with the necessity to design and operate flotation plants with high throughput presents unique metallurgical and environmental challenges that need to be addressed to reduce project risks, improve project economics and to sustain the profitability of operations over the life of a mine.Some of the key challenges include poor recovery of valuables and concentrate quality issues due to complex mineralogy, the need to use poor quality water such as brackish or sea water, reduce environmental impact from the process, integrate flotation with hydrometallurgy to maximize precious metals recovery, escalation of capital and operating costs, use of unproven technology and constant use of larger equipment, high ore variability, worldwide constraints on resource availability and an ever increasing need for reliable metallurgical input to financial models to evaluate economic viability of projects.The need to develop effective solutions to these problems in a short time frame is becoming a key to the success of any new project and for sustaining the profitability of a mining operation. An integrated multi-disciplinary approach to problem solving is crucial with the need for a more lateral thinking along with strategic partnerships and collaboration involving the right players. This paper presents some of the key findings based on experiences from a large number of challenging projects and operations focused on solving complex flotation problems.INTRODUCTIONThere are various challenges to successful development of mineral resources. Most of the ore bodies being developed worldwide are of lower grades requiring high throughput to be economical. Many of these lower grade ore bodies have significant occurrences of deleterious and penalty elements that could render a deposit unworthy of development unless there are technological solutions to process them economically in a sustainable manner with minimal environment impact. Even in a high metal price scenario, the economics for some of these low grade ore deposits is marginal. From a metallurgical perspective, these ore bodies have complex mineralogy and use of any off-the-shelf technology is not always effective. Development of innovative processes are often required, which is expensive, time consuming and sometimes risky.This paper will provide a broader perspective on the steps involved in solving flotation problems for operating plants and for greenfield development projects. In addition, some of the key challenges in flotation of complex low grade ore bodies along with the economic benefits in developing solutions to these problems will be presented."

Jan 1, 2013

By J. M. Simard, S. Morissette, P. Coursol, P. Mackey

A new, powerful model is presented that focuses on plant logistics and scheduling aspects of the smelting, converting, fire refining and casting operations at the Horne smelter. This plant complex is the largest custom copper smelter in North America. It handles a wide range of feeds and utilizes a number of proprietary continuous and batch technologies that require good scheduling in order to maximize plant capacity and efficiency. The present model was developed by Xstrata Process Support, in collaboration with the Horne smelter, and uses the Arena® software to evaluate the impact of a number of plant variables on the annual copper capacity of the plant. Model development was carried out by Xstrata Process Support, in collaboration with the Horne smelter, through the effective combination of process chemistry knowledge and detailed knowledge of the plant operation (including all material flows and transfers, as well as information such as operating on-line times, plant stoppages and also scheduled and unscheduled maintenance activities). A number of case studies were then examined, including the impact of anode furnace and casting cycle times on annual copper capacity and the impact of a one-crane mode of operation in the converter aisle, which normally operates with two cranes in service. The model predictions were found to match actual plant results very well. The present modelling of plant logistics and the scheduling aspects were found to add important dimensions at the plant with regard to projections of the real-life plant capacity. As demonstrated in the present case, this type of model and application can have a significant impact on optimizing operations at a given plant. This impact is particularly important in the current market environment, where emphasis is on maximizing plant output and lowering costs. These models can help yield the easily obtained gains that are clearly desirable in these times. Xstrata Process Support has developed Arena models for other operations and is available to explore new applications for a win-win situation at other plants, including mines and concentrator operations.

Jan 1, 2009

By J. Ling, L. Racine, P. Cousin, A. R. Laplante

"The problem of gold recovery by gravity from high density gangues is first discussed from a fundamental perspective. Three potential difficulties are presented: poor liberation and fine gold particle size, concentrate bed erosion by coarse dense particles, and slow percolation of gold particle through the high density gangue bed. Two case studies are presented to illustrate the impact of these three problems on circuit performance and the feasibility of gravity recovery. It is concluded that careful testing can determine the scope of the first problem and feed preparation can limit the extent of the second. The third problem is clearly the most serious and results in lower gravity recoverable gold recoveries than would be achieved with the same recovery effort on a low density gangue application.IntroductionSince the commercialisation of the Knelson Concentrator in 1980, gold gravity recovery has experienced a surge in interest, in Canada and the United States first, then Australia, Zimbabwe and Russia, and finally worldwide. Table I details number of units sold in various countries, which corresponds approximately to their importance as gold producers 1. Exceptions. such as the low rank of South Africa or the importance of Zimbabwe, despite the much higher gold throughput of the former, are generally the result of differences in the effectiveness of the local marketing strategies, as well as a reflection of the ""philosophy of recovery"" prevalent in the country.The impact of the Knelson has not been felt equally in all plants. Typically, a highly successful application falls into the following categories: (a) alluvial or hard rock recovery for which gravity is the sole recovery method, (b) hard-rock free gold milling with ores which have a very high gravity-recoverable gold (GRG) content, (c) low grade sulphide copper-gold ores which include flotation ahead of cyanidation and (d) free-milling gold ores ahead of Other applications can be successful, but are not as common. The ""explosion"" of centrifuge concentration, of which the Knelson is the most successful but by no means the sole model, has created a certain euphoria which can be summarized as ""gravity recovery will improve the profitability of gold milling, no matter what."" This presentation is about applications that are not so successful, or even downright unsuccessful. The rationale is not to down-play gold gravity recovery, but to set it in its rightful position: metallurgically, it is not appropriate all of the times; it can become inappropriate if poorly designed; and it can be metallurgically possible but economically unjustifiable. In this paper, this will be illustrated and explained rather than demonstrated, with the use of both industrial plant surveys and laboratory test work. Alternate gravity approaches will be suggested."

Jan 1, 1997

By R. Pelton, Z. Dai, S. Yang

ABSTRACT Hydrophobic polystyrene nanoparticles were evaluated as potential flotation collectors for pentlandite. The flotation of hydrophilic glass beads demonstrated the nanoparticles’ ability to induce flotation. Deposition of nanoparticles on glass surfaces increased the contact angle and enhanced adhesion of the beads to air bubbles. High flotation recoveries were achieved when 5–10% of the bead surfaces were covered with nanoparticles. Surface functionalization—the addition of vinylimidazole to polystyrene nanoparticle surfaces—caused the nanoparticles to selectively deposit onto pentlandite surfaces in the presence of Mg-Si slimes. Ongoing work includes attempts to identify specific applications where nanoparticle collectors might be cost effective. _ KEYWORDS Flotation, Nanoparticle collector, Coverage

Jan 1, 2014

By Andrew Chapman

The scope of the SA (Situational Awareness) working group is to analyze the effectiveness of information delivery systems in mining equipment and develop a unified display design, to mitigate against the proliferation of screens within equipment cabs. This working group comprises a variety of stakeholders representing a cross-section of relevant mining and mining-related organizations. This stakeholder network will help guide the direction of the working group towards a common, mutually beneficial end. For now, the focus is on shovel displays; however it should be noted that this work is expected to form the foundation for similar work with other equipment in the future.

Aug 1, 2013

By Costa

The fly-in-fly-out (FIFO) mining model has significant implications for the industry as it plays an important role in fulfilling the economic, social and workforce needs of the contemporary mining industry. It has increasingly been adopted in countries such as Canada and Australia, but is the current nature of the FIFO model challenging the place women have achieved in the mining workforce? Research in the mining and oil and gas industries reveals that major sources of stress for fly-in-fly-out mining workers are the times of parting and of reunion, the challenges in defining roles within the family, parenting, and conflict between spouses over the use of the leave time and money. So how are women in the industry coping with the FIFO schedules and consequent intermittent relationship with families and partners? How is the mining industry adapting to recruit and maintain female employees in FIFO operations? This paper describes an exploratory study conducted in Canada, which intended to provide some initial insights that might help us answer the questions above. There are several inferences made from this exploratory study. It is clear that FIFO poses significant challenges for both female and male workers. It is largely seen as rigid, extremely challenging for employees with young families and workers who are single mothers, and it is generally incompatible with starting a family and caring for small children. FIFO creates severe stress on relationships and on workers psychological well-being. It seems to be indeed harder for women, since they are often in lower paying positions and therefore have less financial reward for the FIFO lifestyle. On the other hand, FIFO creates the opportunity for young women, including Aboriginal women, to jump-start their careers, as well as opportunities for mature women to work while pursuing other personal interests during their time off. This paper concludes with recommendations to improve the FIFO system in order to increase the ability of mining companies to hire and retain women

May 1, 2006

By Andy Cole, Ken Thomas, Stephen Durn, Jacques McMullen

"The roasting and gas handling circuits of the Barrick Gold’s new Roasting Facility at the Goldstrike Mine in Nevada, USA incorporate well proven technologies in a unique combination. During the design of the plant, every effort was made to utilize the best available technologies from the perspective of capital, environment and operating costs.Product from the up-stream dry grinding circuit requires roasting to maximize gold recovery. The roaster utilizes Freeport-McMoRan whole ore roasting technology with pure oxygen as the oxidizing gas. This process was chosen based on its proven application on Carlin-type “double refractory” ores. Double refractory is indicative of the gold being difficult to direct leach due to a combination of pyrite encapsulation and the carbonaceous preg-robbing of the ore.A very extensive gas cleaning train follows the roaster and comprises direct cooling, dust scrubbing, indirect cooling, wet electrostatic precipitation, mercury scrubbing, SO2 scrubbing, CO incineration and NO, reduction before venting to the atmosphere.The roasted calcine is quenched, neutralized and then thickened before leaching in the carbon-in-leach-circuit.INTRODUCTIONBarrick’s strategic development plan integrated the production of gold from Goldstrike’s carbonaceous ore reserves by 2000. A due diligence review of carbonaceous ore processing options was initiated during the second half of 1 996. Processes considered included autoclaving followed by a proprietary ammonium thiosulfate leaching process, fine grinding/autoclaving as practiced then by Santa Fe, and whole ore roasting as practiced by then Independence Mining and Newmont. The objective by year-end was to recommend the most robust and economical process for Goldstrike’s carbonaceous resources. In the fall of 1996, a detailed review of roasting as a processing alternative for Goldstrike was initiated."

Jan 1, 2001

By P. B. Demarsh

"Location: - Mine village of Perron, 11 miles east of Val d’Or in northwestern Quebec.Life; - Started production 1932, ceased 1951.Ore: - Flat lying quartz tourmaline veins within granodiorite. Gold values related to coarse segregations of pyrite. Specific gravity 2. 80.Capacity: - 30 tons 1932-35; 125 tons 1935-37; 350 tons 1937-51.Assay: - Heads 0.21 to 0.34 oz. per ton. Grade obtained by mining 600 tons daily, sorting belt reject 250 tons, balance to milling; tailings loss 0.003 to 0.005 oz. per ton; extraction 9 8. 5%.Grind: - 70% minus 200 mesh. Detention time 26 hours.Treatment: - Cyanidation process.Reagents: - Per ton, aero cyanide (NaCn) 0.36; unslaked lump lime 1.50; zinc 0. 03; lead acetate 0. 006; steel consumption 2. 50.Water: - Equal mixture of swamp creek water and underground seepage.Cost: - Per ton, sorting and crushing 0.21; grinding 0.31; cyanidation 0.11; filtration 0.05; precipitation 0.02; miscellaneous 0.22; total 0.92.Power: - Hydro-electric, 25 cycle, 12, 000 volts reduced to 550 volts.Labour: - 95% Maritime and European, balance Quebec and Ontario.Tailings: - Absorbed over large swampy area on barren mining claims.Personnel: - 1 7 men including supervision.Flow sheet: - Canadian Mining Manual 1947"

Jan 1, 1966

By Pierre Beaudoin

"This paper deals with the repairs made on two damaged mills. It investigates briefly the causes of the damage, explain its nature and the design of the repair. It explains the detrimental effect on operation and the solutions implemented to reduce them. Finally, to review the follow-up required for such repairs. LOCATIONThe Holt McDermott Mine is located 75 kilometers Northeast of Kirkland Lake and 30 kilometres west of the Quebec border in Northeastern Ontario. The town of Kirkland Lake is located approximately 500 kilometres north of Toronto. HISTORYThe discovery of gold in Holloway Township dates back to early 1920. In 1984 Barrick Resources, which amalgamated with Camflo Mines, acquired more claims on the property and initiated an extensive drilling program. By 1985, the drills indicated reserve increased to 2,500,000 tonnes grading 6.8 g/mt. In 1986 a production decision was made and in 1988 the mine was officially opened.As of December 31, 1998, 4,691,507 tonnes grading 5,66 g/tonnes have been milled from 4 ore-bodies. The mill started up in June 1988."

Jan 1, 2001

Leadership "Organizing a group of people to achieve a common goal" Paradigms ? Rush to produce or cut costs. ? The most important thing after safety is production. ? We?ll take care of ??this?? once in production. ? I know what to do, 30 years of experience in mining. ? I want a 100% reliable operation.

Aug 1, 2013

"The Detour Lake Mine is located in northeastern, Ontario, approximately 300 kilometres northest of Timmins and 185 kilometres by road northeast of Cochrane. The mill processes a free milling gold ore using both gravity circuit and leaching with a state-of-the-art carbon-in-pulp circuit. The grinding circuit is a conventional SABC circuit with a tonnage of 55,000 mtpd at 95 microns with the addition of pre-crushing upstream of the SAG mill.The present paper will describe the methodology used to successfully prove that gold of the Detour Lake Mine ore is mostly concentrated into the fine size fraction of the blasted rocks. It will describe the various options possible to create value from this ore property.IntroductionThe purpose of this test work was to determine the grade of the pebbles and consider if there was value into discarding the pebbles and replacing the material by fresh feed.1. Pebble samplingThe pebbles were sampled and assayed for grade every day for 3 months. After 3 months of sampling, the results showed that the pebbles only carried 28% of the fresh feed grade. This phenomenon can possibly be explained by the fact the gold is located into area of fracture in the rocks.January-March 2014 – Pebble assay average• Line #1 = 0.222 g. Au/t• Line#2 = 0.275 g. Au/t• Head grade = 0.88 g. Au/t2. Crushing and grinding circuit surveysWith the above information, a grinding circuit survey was planned. The purpose of the survey was to build a JKSIMMET model of the grinding circuit for mill optimization but also to understand the deportment of gold into various size fractions that may explain why there is so little gold in the pebbles. All streams and size fractions was analysed for particle size analysis and for gold.Since Detour has dual grinding lines, both circuits were sample at the end of May. Two supplemental survey of the secondary crushers were also done and a survey of the gyratory crusher."

Jan 1, 2016

By H. O. Ghaffari

A complex network approach on a rough fracture is developed. In this manner, some hidden metric spaces (similarity measurements) between apertures profiles are set up and a general evolutionary network in two directions (in parallel and perpendicular to the shear direction) is constructed. Also, an algorithm (COmplex Networks on Apertures: CONA) is proposed in which evolving of a network is accomplished using preferential detachments and attachments of edges (based on a competition and game manner) while the number of nodes is fixed. Also, evolving of clustering coefficients and number of edges display similar patterns as well as are appeared in shear stress, hydraulic conductivity and dilation changes, which can be engaged to estimate shear strength distribution of asperities.

May 1, 2009

By Robert K. Jonas

"Minerals processors can improve production by using the best available control technology to control their operations. Many mines use expert systems that can provide improved results over manual or basic control, but better results can be achieved using multivariable predictive control. Over the past few years, the application of multivariable predictive control has gained acceptance in many mining processes and has recently proven to be suitable for some of the most challenging processes. This advanced control technology has been successfully applied to a wide variety of processes; alumina digestion, ball mills, CCD/thickeners, kilns/calciners/roasters, heat exchangers/evaporators, and more demanding processes like SAG mills and flash smelters.This paper discusses the needs of advance control technologies in the mining industry, including the impact of these technologies on best practices for implementation and long term sustainability. Results of the multivariable predictive control applications in mineral processing are discussed, and in particular the application to the SAG mill. In addition, an example of the benefits improvement that can be achieved with this technology is presented.INTRODUCTIONThere has been a long term perception in the mainstream mineral processing industry that best advanced control solution is an expert system. There a numerous instances of expert systems used for control of SAG mills, as well as kilns or roasters, thickeners and more recently flotation circuits. Many of theses expert systems have been installed by small, independent companies or by OEMs of processing equipment. Undoubtedly these expert systems have provided millions in benefits to the owners of mineral processing plants.It is this author’s proposition that it is a misconception to believe that expert systems are the best solution for mineral processors, and that in many cases the best solution is Multivariable Predictive Control (MPC). Better control and optimal operations can be achieved through the use of MPC. Another important consideration when considering advanced control technologies is the implementation and support effort. These types of applications have been known to deteriorate, even to disuse, when they are not kept up to date with changes to the process or equipment. The audience is invited to listen to discussion and draw their own opinion. The author has been involved in installing control systems for over 20 years, advanced solutions for over 15 years, and has had privilege to consult with many miners concerning the selection and application of advanced controls over the past 6 years."

Jan 1, 2008

By Norman O. Lotter, Dominic Fragomeni, Jorge Oliveira, Dee J. Bradshaw, Rebecca Monnapula

"The role of mixed collectors in enhancing the metallurgical performance of sulphide flotation processes was reviewed in 2008, and later published as an integrated theory by Lotter and Bradshaw, 2009. The theory proposed that xanthates, dithiophosphates and dithiocarbamates could be synergistically combined in an optimal formula to deliver improved grade and recovery. The approach uses a five-step structure, viz.1. A mineralogical study of the ore to be treated, identifying and quantifying the economic minerals (with hosting and association) and gangue species present.2. Selection of candidate collectors from this mineralogical information and from the known pulp conditions of that operation (e.g. Eh, pH).3. Design and execution of a factorial experiment to estimate and test the main effects and interactions, and to model the response surface for an optimum formulation [Box et al., 1978].4. Use of a High-Confidence Flotation Test platform in the factorial to reduce overall errors and allow for clearer observations [Lotter, 1995; Lotter and Fragomeni, 2010].5. Statistical design of a plant scale trial to measure and validate the gains [Napier-Munn, 1995; Lotter et al., 2009]. Eland Platinum, which was commissioned in November 2007, appointed a team to apply this theory to formulate an optimized mixed collector suite for use in the operation. The West Pit ore (UG2 - Normal ore) was sampled at site and brought to Xstrata Process Support, Sudbury, Canada, for mineralogical and metallurgical testing in 2008. Microprobe and QEMSCAN measurement characterized the type, grain size and textural association of the discrete Platinum Group Minerals (PGM) present. From the mineralogical data, it was clear that a mixture of dithiocarbamate and two xanthates would be a likely reagent suite selection. A factorially designed set of High-Confidence Flotation Tests studying these was performed, concluding that an optimal suite using certain amounts of these collectors was a viable formulation that would advance the grade and recovery performance at Eland above the standard PIBX by approximately 2.13% 4E PGE. The plant trial, which used a form of the replicated block design after Napier-Munn, 1995, and Lotter et al., 2009, exceeded this estimate with an overall PGE recovery gain of 2.48% (absolute basis) and a concentrate grade gain of 26.4 g/t PGE (absolute basis), as well as reducing chrome in concentrate from 2.04 to 1.62% (absolute basis). These gains proved to be statistically significant using the analysis of variance method, and have validated the theory."

Jan 1, 2011

By P. A. Witt

"Highland Valley Copper is a conventional truck-shovel mining and flotation concentrator operation located 75 km southwest of Kamloops, British Columbia (Fig. 1).The ore is situated within a porphyry copper deposit and is mined at a rate of 135,000 mt/day from two separate open pits. The nearby mill produces concentrates containing 375 million pounds of copper and 5 million pounds of molybdenum metal yearly. In the Valley pit, head grades are roughly 0.40% Cu at a 0.23% Cu equivalent cut-off. The Valley pit strip ratio currently sits at 0.55:1 with waste quantities made up of separate rock and unconsolidated overburden units. From the mill, concentrates are trucked to nearby Ashcroft and then hauled by rail to ocean port facilities in Vancouver. The mine employs 950 people and is planned to operate until 2009. The operation is a partnership between Teck Cominco (63.9%), BHP Billiton (33.6%), and others (2.5%). Management is shared by the two principal owners and directed by a management committee."

Jan 1, 2005

By Tom Shumka

"All mineral processing facilities that use girth gear driven mills need to inspect the gear teeth on a routine basis, whether it be every six months to every three years. The inspection frequency depends on gear tooth condition, and the objective is to ensure the operational integrity of the gear teeth. Conventional methods such as magnetic particle testing, visual inspection or dye penetrant examinations rely heavily on operator interpretation. At best, these techniques can determine whether a defect exists, but are unable to provide information on defect severity. This paper describes the use of combining combined eddy current array (eca) and alternating current field measurement (acfm) to provide a complete survey of all surface breaking indications on the whole gear tooth depth. This method accurately determines the size, length and depth of any cracks found on the surface.INTRODUCTION In order to gain a fundamental understanding of the evolving operational and production behavior of a piece of machinery over a specified time period as part of an effective condition monitoring program, a robust data collection process must be firmly established and adhered to. To be effectively implemented within an organization, a condition monitoring program must have support of not only the maintenance, production and engineering staffs, but also executive management support to ensure successful roll out to realize the maximum productivity of the machinery and subsequent cost-savings. One of the key elements of a mineral processing facility that use gear driven SAG Mills as a primary stage for grinding solution, is the integrity of the critical gear unit that drive the mill. For the maintenance team, condition monitoring on the gear unit is crucial for preventative maintenance. A catastrophic failure in the critical gear unit would require a minimum of ten days to replace the gear set, depending on the damage occurred. This, of course, would only be applicable if the client had a spare critical gear set in inventory. If a gear set had to be ordered, it could take from four months to two years to receive a new gear set. For example, in 2007, there was a global backlog of these types of gears sets resulting in a two year delivery. The maintenance costs associated with a catastrophic failure of this type would easily cost in the millions."

Jan 1, 2012

By Kevan J. R. Ford, Chris A. Fleming, Robert D. Henderson

"Kinross Gold Corporation’s Maricunga mine in Chile presents an ideal opportunity to apply the SART process to a heap leach operation. Given increasing levels of cyanide complexed copper in current pregnant solutions from Maricunga heaps (over 300 ppm Cu), there is a need to reduce these levels and decrease cyanide consumption and cost. Additionally, a means of disposing of this copper is required, preferably as a saleable product. The well published SART process applied to gold-copper cyanide solutions was selected as it allows rapid precipitation of cyanide soluble copper as a relatively pure copper sulphide. The process also allows effective recovery and recycle of cyanide back to the heap leach operation.This paper reviews the SART process chemistry and presents a summary of SART bench-scale and pilot plant testwork completed by Kinross. Key design parameters and engineering aspects of the proposed plant at Maricunga are discussed. SART plant operating costs and net revenue analysis are included and illustrate the compelling economics of installing a SART process plant. INTRODUCTIONMaricunga OperationCompañia Minera Maricunga (CMM), fully owned by Kinross Gold Corporation, operates the Maricunga mine (formerly Refugio) which is located 120 km due east of the city of Copiapó at an elevation of 4,200m above sea level in the Andes mountains of northern Chile. Figure 1 shows a map of the location of the Refugio mine relative to other gold and copper mines in the region."

Jan 1, 2008