Search Documents

By A-A. Bogno, Ch. -A. Gandin, A. Maitre, H. Henein

Most metallic materials are produced from their liquid state. In order to control the properties of industrial products, it is very important to understand their solidification path and the resulting microstructures which can be significantly affected by melt undercooling. High undercooling results in rapid solidification and a refined microstructure with minimal microsegregation. This paper reports on the analysis of rapidly solidified Al-Cu droplets obtained by a single fluid atomization process, Impulse Atomization. A quantitative analysis by Rietveld refinement method of the Neutrons Diffraction data was carried out to determine the fraction of the intermetallic Al2Cu. Knowing the fraction of Al2Cu, the eutectic fractions and corresponding dendritic and eutectic undercoolings were estimated using the metastable extensions of solidus and liquidus lines of the Al-Cu system calculated by Thermo-Calc. In addition to this work, a model of microsegregation coupled with ThermoCalc software via TQ (application programming interface of ThermoCalc) and the Wang-Beckerman model for dendritic growth velocities has been developed for binary alloys. This has led to the development of a phenomenological relationship between primary phase undercooling and initial growth velocity. A comparison of estimated primary undercoolings using a coarsening model with the adiabatic undercoolings for each alloy composition has confirmed that solidification occurs under adiabatic conditions during recalescence.

Jan 1, 2014

By Rick Wilkins

The stability of steep embankments is a major safety issue in open pit mining, highway passes, and earth filled dams. A failure in any one of these situations could mean a loss of very expensive equipment, a long term inconvenience, and more importantly, a loss of life. These possible catastrophes could be avoided by installing a reliable real time monitoring system. Robotic total stations (RTSs) give one possible cost effective solution to creating a near real time monitoring system. Repeated surveys at predetermined time intervals can automatically generate warnings if slope movements exceed a preset tolerance level. The variation in atmospheric refraction, combined with possible instabilities in reference targets, can make a monitoring system based on RTSs produce false alarms. A methodology has been developed at the Canadian Centre for Geodetic Engineering (CCGE) for reducing these systematic error effects. The methodology has been realized in the creation of a software package that has been successfully implemented at large earthen dams in California and at an open pit mine operation in British Columbia.

May 1, 2002

By M. Y. Solar, W. G. Davenport

Most of the recent growth in nickel demand has been for the production of stainless steels and virtually all of it has been satisfied by new ferronickel and nickel pig iron projects. But "good" laterite resources are more and more difficult to find: Ni grades are decreasing while Fe contents are increasing and SiO2/MgO ratios vary from 1 to 3 and even higher if limonites are included. Predicting the smelting behaviour of such ores requires a more fundamental understanding of the thermodynamics of these systems in commercial operations. One valid question is thus whether these furnaces are at thermodynamic equilibrium or not. The present paper investigates this question, compares calculated and measured O2 partial pressures and mechanical/chemical slag loss ratios and concludes that ferronickel furnaces are not at thermodynamic equilibrium. This departure from expectation is actually to the operators’ advantage: the targeted ferronickel grades can be obtained at lower reduction potentials than calculated from pure thermodynamics.

Jan 1, 2014

By B. Y. Park

This paper develops a series of three-dimensional simulations for the Bayou Choctaw Strategic Petroleum Reserve. The U.S. Department of Energy plans to leach two new caverns and convert of one of the existing caverns within the Bayou Choctaw salt dome to expand its petroleum reserve storage capacity. An existing finite element mesh from previous analyses is modified by adding two caverns and increasing the size of existing Cavern 102. The structural integrity of the three expansion caverns and the interaction between all the caverns in the dome are investigated. The impacts of the expansion on underground creep closure, surface subsidence, infrastructure stability, and well integrity are quantified. The results show that from a structural viewpoint, the locations of the two newly proposed expansion caverns are acceptable, and all three expansion caverns can be safely constructed and operated.

May 1, 2009

By E. Watkins, J. C. LeRoy, A. Vivyurka

"TAILINGS REVEGETATIONWelcome to the Revegetation Session. My instructions are to introduce the Speakers and to provide a general introduction.I do the latter with humility not only because of a lack of personal experience or because tailings revegation is not well established technology, but because any general statement on a country or industry as diverse as the Canadian Mining Industry is bound to be wrong somewhere.Laying aside normal standards of accuracy I proceed as follows:In considering the question of tailings revegetation, one asks two basic questions:1. What ought to be done?2. What can be done?The first question can be broken down into three kinds of criteria or objectives:a) Legislativeb) Technicalc) AestheticThe first I leave to the politicians and the last I will avoid. Aesthetics is the philosphy of taste. It is concerned with the appreciation of things rather than what they really are. It is much easier to get into an argument on aesthetics than to get out of it feeling you have said something of consequence.Technical criteria can be divided into the following sub-objectives: 1. To isolate the tailings basin so surrounding land is not degraded. The first step here is stabilization of the surface to prevent wind and water erosion."

Jan 1, 1975

By Jose R. Hernandez-Aguilar

"This paper revisits data from previous studies (Hernandez-Aguilar, 2010, 2011) to better understand the link between metallurgical performance and pulp-zone bubble size (Db) in full-scale flotation systems. To obtain conclusive evidence exclusively related to the pulp (collection) zone, the experiments were designed in those studies to control both the bubble generation method and the influence of the froth zone on the overall metallurgical performance in industrial and pilot-scale flotation columns. The results showed that Db had a significantly larger effect on the recovery of coarse (> 75 µm) particles compared to the effect on fine (< 16 µm) particles. It was observed that, under certain practical conditions, the recovery of coarse particles was close to zero, but dramatically increased by reducing Db. The evidence revealed an inconsistency of the so-called “k–PSb” model: at constant froth recovery, increasing Sb (i.e., the rate of production of bubble surface area) did not always result in higher recovery, as the model predicts. Furthermore, the evidence showed that it was not the Sb but the bubble size that proved to be a more reliable link to metallurgical performance. Only in the presence of suboptimal-sized bubbles (Db > 2 mm) did the froth zone seem to play a role, possibly reflecting an effect of pulp-zone bubble size on froth stability. However, the role of the froth was negligible for Db < 1 mm.High-resolution mineralogical measurements performed on process samples revealed that, regardless of the degree of liberation, Db had a profound effect on the shape of the recovery-by-size curve, particularly the coarse particle size fraction. This observation is key as it implies that the loss in efficiency associated with floating the coarse particles was not the result of neither particle hydrophobicity nor particle detachment issues: even in the absence of mechanical agitation, liberated and highly hydrophobic coarse particles did not seem to attach to the bubbles in the first place, an inefficiency that was corrected by reducing bubble size. The data analysis suggests that poor attachment efficiency can practically affect both fine and coarse particles but via different mechanisms which are discussed here."

Jan 1, 2017

In 2009 Newmont Mining Corporation?s annual global spend on grinding media reached $94M USD, having doubled in the five years since 2004. The major contributing factor to the spend escalation during this period was unit consumable price, with total media consumption also rising as a function of annual ore tonnes milled. In an effort to better understand and manage the growth of this expenditure a significant supply chain management program was implemented. This was complemented by a series of technical initiatives focussed on grinding media specifications, quality management and the prediction of grinding media wear rate as a function of physical ore characteristics. This paper discusses the methodology and outcomes of these activities.

Jan 1, 2012

By Pathies Nawej Muteb, Tom Strombotne, Karl Leetmaa, Irma Gabric, Keith Darby

"Continuous control of the final grinding product size is important to optimize gold liberation for Gold Milling operations. At Meadowbank Mine an on-line Particle Size Monitor has been employed successfully to achieve the targeted final grind which leads to optimizing the gold recovery at maximum grinding circuit throughput. The live monitoring of the final product particle size leads to a maximum grinding circuit throughput every minute during the process. This paper discusses the optimal utilization of the Particle Size Monitor to assist the Mill operator to maximize the grinding circuit throughput as the milling conditions change due to variable ore processed at Meadowbank Mine. Also the paper includes the usage of the Particle Size Monitor to guarantee the final grind target at each instant of the process.IntroductionAgnico-Eagle is a Canadian-based company that Trades on the TSX & NYSE (AEM). It owns eight mines (8) operating in Nunavut, Quebec, Finland and Mexico and has more than 7,500 employees (Figure 1). 1.6 M ounces of gold were produced in 2015 and the annual average annual production from 2016 to 2018 is forecast to be approximately 1.53 million ounces of gold.The Meadowbank Mine is located in Nunavut, Canada (Figure 2). The mine opened in 2010 and from 2010 to 2014 a total of 1.8M oz of gold was produced. The milling rate is 4.2 Mt per year with an average mill throughput of 11,900 tpd or 496 tph. Average annual gold production over life of mine is expected to be 450,000 ounces. Meadowbank has 775 employees, of which 265 are Inuit or 36% of the total workforce. Estimated life of mine is 2010 to 2018. Gold production in 2015 was 381,804 oz. Meadowbank was Agnico-Eagle’s largest Gold producer in 2015."

Jan 1, 2017

By B. W. Clyburn

"Coals from the Corporation's Lingan and No. 26 mines are classified as high-volatile A bituminous, with a very low inherent ash and containing all essential properties to provide metallurgical coal, with the exception of a high sulphur content. Only through proper cleaning at low specific gravity can the pyritic sulphur fraction of the coal be liberated to an extent where final sulphur meets coking standards. This first section of the paper deals with the operation of a Dutch State Mines heavy-media cyclone circuit to achieve an actual separation in the region of 1.30 specific gravity. A discussion of the parameter of control which must be applied along with an appraisal of the results obtained is included in the paper.Introduction Very high fluidity and unusually low ash are the outstanding characteristics of coal from Devco's mines in the Harbour seam of the Sydney coal field. However, sulphur content, mainly pyritic, ranges from 1 to 2.50Jo. To obtain the low and consistent sulphur level required in metallurgical coking coals, preparation at low specific gravity is required. Metallurgical coke is used as the fuel in an iron blast furnace. Its sulphur content largely determines the quantity of slag required to remove it and therefore influences furnace productivity and unit costs. Typical data on the various coal properties of importance in the production of coke are included in Table 1."

Jan 1, 1985

?General Facts:Barrick?sFirst Mine in Peru Production started in November 1998 ?The Facilities:Open Pit, Primary and Secondary Crusher Valley Fill Heap Leach PadMerrill Crowe PlantRefinery Environmental Facts: High Rainfall - Average Annual Precipitation of 1,200 mm (47 inches) Rainfall Events: Common 20mm daily events High Altitude Site - Elevations range from 3900 to 4250m. Steep topography - Terrain ranges from 3:1 slopes up to cliffs. Water Issues: Sediment Control - Open Pit PAG Encapsulation - Waste Dump Stormwater control - Leach Pad Erosion Control Techniques ? Offsite impacts mitigation Social Issues: 11 communities surrounding the property Town of Huaraz

May 1, 2003

By H. F. Letient, D. C. Johnson

At the 25th Annual B.C. Mine Reclamation Symposium in September 2001, Huckleberry Mines Limited received the Jake MacDonald Reclamation Award for its exemplary mine waste management plan, conceived to prevent the onset of acid rock drainage (ARD) and facilitate reclamation of the site. The mine is an excellent example of a total mine waste management plan, with all materials scheduled in detail for the life of the mine. The filling plan for the waste management facility takes into consideration the requirement for permanently flooding the potentially acid-generating rock. From an acid generation point of view, the tailings fall in the zone of potentially acid-generating material. To avoid long-term ARD concerns, it is planned to float pyrite out of the tailings toward the end of the mine life, thereby generating a non-potentially acid-generating tailings stream which will be used to cap the deposited mine waste. The pyrite-rich tailings will be discharged into the deeper portion of the impoundment. On closure, a permanent water cover will be maintained over the mine waste. Only beaches of non-potentially acid-generating tailings will remain exposed. Mining will be phased to also allow one of the pits to provide storage for potentially acid-generating rock and to be flooded at the end of mine life.

Jan 1, 2004

By Adam Powell, Matthew Earlam

INFINIUM, Inc. is scaling up a new molten salt electrolysis process for producing rare earth metals. Instead of conventional carbon anodes, this process uses Pure Oxygen Anodes™ which employ a stabilized zirconia solid electrolyte between the molten salt and anode. This eliminates two problems with today&apos;s rare earth metal production technology. First, it eliminates carbon anodes and contamination of the product by carbon and its impurities, enabling 10-100 times larger batch size than current practice, and lower labor costs. Second, it eliminates emissions of perfluorocarbons (PFC) such as CF4 and C2F6, which are very problematic greenhouse gases with 6000+ times the global warming potential of CO2. The zirconia also enables a sealed vessel with no LiF emissions, creates a reducing environment enabling use of low-cost welded steel vessels, and either produces a high-purity oxygen by-product or can use natural gas to reduce the necessary electrical energy with no HF production. This paper will describe the technology and its current status for rare earth metal production.

Jan 1, 2014

By Kjell Winther

"Hydralift Scanmec introduced early in the eighties a new and different mill design for very large grinding mills. The design described has actually no size limitation upwards and is so far suggested with motor power up to 40 MW. The mill is furnished with gearless ring motor drive transmission. It is totally fabricated, without heavy castings. The first installation, an 8, 1 MW ball mill dia. 6,5 m x 9,65 m length, has been in continous operation in 13 years without problems. Total grinding costs has been reduced with 3 0% compared to traditional smaller mills. Reductions has been achieved in maintenance cost, power consumption, liner wear and grinding media consumption.So far 3 ball mills of the described design are delivered and in operation, one grinding Iron ore and two grinding Nickel ore.IntroductionThe design of mills for mineral ore dressing has basically been unchanged since grinding in mills started some I 00 years ago, in spite of the fact that mills have grown larger and larger. This has resulted in structural and mechanical problems, causing expensive failures and loss of production.Hydralift Scanmec engineers were designing mills for more than 20 years according to the old «rules». As they experienced interest for an increase in the mill size at the time when reports about failing mills were published, they started analyzing the different mill parts to find new solutions. One goal was to only use elements from proven technology in the new design. Two key items were ring motor (wrap around motor)(Isch et al. 1977, Meintrup and Klein 1982, Ranze 1983) and large diameter pad bearings (wrap around bearings)(Fuller 1984), both acknowledged from other industries."

Jan 1, 1995

By Stephan Buys, Dan Curry, Chris Rule

"The use of fine grinding (FG) in mineral processing is well established. The application of FG in the South African platinum industry is more recent and it’s use in the recovery of PGM’s from dormant tailings dams is unique. Anglo Platinum uses IsaMill FG technology at their Western Limb Tailings Retreatment project (WLTR) near Rustenburg in the North West Province of South Africa.In December 2003, Anglo Platinum commissioned the first purpose built tailings re-treatment facility for PGM recovery in South Africa. The concentrator re-treats Merensky ore tailings from concentrators that operated early last century. The WLTR facility takes advantage of modern technology, such as FG, to economically recover PGM’s from material historically considered as waste. The WLTR concentrator has a capacity of 4.8 Mtpa, and has been designed to easily expand to 10.8 Mtpa. The flow sheet includes recovery of tailings by high pressure water monitoring, ball milling, rougher flotation, rougher concentrate regrinding and cleaner /recleaner flotation.The rougher concentrate is reground in an IsaMill, which is a stirred mill that operates with inert silica sand grinding media. For this project, Anglo Platinum required a stirred mill of a unit size not previously available. Xstrata Technology and Anglo Platinum collaboratively developed the largest wet, fine grinding mill available; the M10,000, 2.6 MW IsaMill.The use of IsaMill technology was enabling for the WLTR project, as it allowed smeltable concentrate grades to be produced from the oxidised, slow floating tailings. The economics and practicality of fine grinding has fundamentally changed with the M10,000 IsaMill. Flotation is transformed by high intensity attritioning in the inert media environment, and the narrow size distribution of product in open circuit configuration. The use of conventional steel media grinding to improve fine particle flotation is limited due to the oxidation of liberated mineral surfaces inherent in these environments."

Jan 1, 2005

By John R. Craynon

Science and Sustainable Development Each of the ?pillars? of sustainable development are directly impacted by mining. We need science to understand exactly how mining contributes to each. Overview of presentation ? History of mining and sustainable development ? Role of stakeholders in measuring/accepting contributions of mining to SD ? Identified ?shortfalls? in understanding mining and SD ? Science needs

Aug 1, 2013

By T. Strong

"Selectively recovering pentlandite from high levels of pyrrhotite presents a technical and operational challenge. The liberation characteristics and also the chemical environment is critical to performing a successful separation. Reviewing the mineralogy to understand the characteristics of the ore and the plant flotation behavior is fundamental to designing a successful improvement program.At Savannah Nickel the challenges presented by a falling nickel price required a rethink of the flowsheet to improve the project economics through improving the concentrate grade and recoveries. Glencore Technology reviewed the plant performance and proposed and tested solutions to improve the grade performance of the concentrator with the support of the plant team. A pilot plant comprising a M20 IsamillTM followed by an L500/1 Jameson Cell was operated on various plant streams. In addition to the pilot plant, flotation surveys and a plant based laboratory program was used to supplement the plant understanding and within two weeks significant improvements were identified and demonstrated. The combination of the pilot operation and the plant based laboratory program was able to quickly demonstrate the improvements and test with equipment that is fully scaleable from pilot plant to full scale.IntroductionPanoramic Resources Limited is a Western Australian mining company formed in 2001 for the purpose of developing the Savannah Nickel Project in the East Kimberley region of Western Australia. Panoramic successfully commissioned the $65 million Savannah Project in late 2004. The process plant at Savannah comprises a single stage crusher, SAG mill, flotation, thickening and filtering stages to produce a bulk nickel, copper, cobalt concentrate. Metallurgical recoveries average 86-89% for nickel, 94-97% for copper and 89-92% for cobalt. The plant was originally designed for a throughput of 750,000 tonnes per annum, but has consistently outperformed the design specifications.Due to low nickel prices the Savannah Nickel mine and processing plant were placed into care and maintenance in May 2016. Prior to suspending production Glencore Technology was engaged to investigate options to improve the concentrate grade. With the discovery of Savannah North in 2014 and the Savannah North Scoping Study demonstrating LoM ~8 years and Mining Inventory of 6.07Mt @ 1.26% Ni, 0.64% Cu and 0.09% Co significant future potential exists. By completing pilot plant studies prior to shutting down, the plant engineering studies can be completed and the plant readied for restart by the time the nickel price improves."

Jan 1, 2017

By Bryan A. Bartley

"Jim Macdonald was promoted from Waterworks Engineer to Streetworks Engineer for the Wellington City Council. He thus took over the City quarry and responsibility for its performance. The crushing plant needed upgrading and he thought it would not be difficult to make a crusher to overcome a problem. If he had a longer association with the quarry industry he would have used conventional methods and equipment, so his invention arose from a fresh view of crushing.He invented the Barmac Rotopactor after observing a wear resistant chute with a lining of dead stone trapped above a piece of angle. This idea led to a rotor lined with trapped stone, rotating on a vertical spindle. In trying - a model rotor he observed the impact against a circular rill of stone in half an oil drum and thus was started a very fertile new area of developement in comminution. The writer helped in the developement and shares in the patents. Jim died in January 1982, just as the machine was becoming known and some 200 were in use in various countries. Most were working in hard rock quarries et that time but recent uses have carried the machine into the mining and mineral processing field. This paper is directed at that industry."

Jan 1, 1985

By A. I. A. Salama

The CANMET Western Research Centre (CWRC) has developed a hydrocyclone model simulation of dewatering and fine particle separation circuits. The simulation is based on an existing empirical model. Utilizing a cyclone manufacturer’s published data, some modifications have been developed and integrated into the model. Feed stream characteristics, cyclone mechanical dimensions, and operating conditions are used in the CWRC modelling simulation. The computer results are presented in 3D graphs and corresponding 2D maps showing the cyclone mass recovery, percent solids by mass in underflow and overflow, and cut size as functions of the cyclone apex diameter and cyclone throughput (i.e., inlet pressure or pressure drop). Results of the computer simulation have been used in the economic feasibility and design of several dewatering circuits in oil sand plants.

Jan 1, 2003

By Niklas Willemsen

Introduction to SVCs ? SVC = Static var Compensator ? Dynamic step-less control of reactive power without switching of passive components: ? Voltage control/stabilization ? Harmonics- and flicker mitigation ? Dip mitigation ? Main components: ? TCR (Thyristor Controlled Reactor) ? Tuned harmonic filters ? Control- and cooling systems ? Typical applications: ? Mine hoists ? Large mining complexes ? EAF, SAF, rolling mills, wind/solar farms etc..

Aug 1, 2013

By Phillip J. Mackey, Gerardo R. F. Alvear F.

It is now 38 years since the publication of the first edition of "Extractive Metallurgy of Copper" by Professor W.G. Davenport and the late Professor A.K. Biswas. The text book would be issued in a total of five editions, soon became the standard for students and those in industry. Interestingly it was published at the onset of great change in the industry. This was a time when sulphur dioxide controls in the USA were introduced, and almost simultaneously, world oil shocks caused significant increases in the cost of fuel - all leading to efforts to adopt new technology and move away from the reverberatory furnace, which had no potential for sulfur capture and required large amounts of fuel. At the time of publication of the book, new processes such as the Noranda Process and the Mitsubishi Process were in their infancy, while flash smelting (which was first commercialized in 1949 at Harjavalta, Finland) had made significant in-roads in boosting copper output, with some 22 new flash smelters licensed by 1976. Computer technology and associated process control techniques were rudimentary compared to systems today, available physico-chemical data remained largely in tabulated format and needed to be manually entered into the main frame computers of the era, while modeling techniques common today had not yet been developed. The copper industry has therefore seen immense changes since the time of this textbook: world tonnage of smelted copper has risen from 7.34 million tonnes/year in 1976 to 16.7 million tonnes/year in 2012, over a two times increase. Technologies such as the El Teniente Process, or Top Submerged Lance technologies, typified by the ISASMELTTM, not commercialized at the time, now treat large tonnages of copper concentrate in a single furnace. Advanced heat and mass balance software and thermochemical modeling are now used extensively to examine chemical and physical characteristics for process design and to support process optimization. These changes in the industry have been chronicled in subsequent editions of the book. This paper looks at the issues and problems seen in 1976 and over the intervening years, and compares this with the challenges facing the industry with the available tools and technologies today. Some ideas looking into the future are also discussed in the paper.

Jan 1, 2014