Search Documents

By J. A. McLennan

Geological uncertainty is an unavoidable characteristic of all mining projects since only limited information is available from sampling. Mine planning and development decisions with significant economic consequences are made when the geological heterogeneity is inherently uncertain. Geostatistical simulation is preferred over kriging because the methodology provides alternative property realizations that can be combined into a model of geological uncertainty. Geological uncertainty can be transferred into production uncertainty, which can help characterize the economic risk of the project. This paper presents a case study for the Pogo property, being prepared for development near Fairbanks, Alaska. The exact dimensions, grades and production predictions have been modified; however, the methodology is illustrative. The geostatistical methodology consists of (1) assembling the relevant drillhole data and establishing a suitable coordinate system, (2) calculating the target distribution, (3) creating a model of spatial correlation, (4) generating multiple realizations at a small scale and (5) linearly averaging all the realizations to the chosen selective mining unit (SMU) support size. The geostatistical model is then used to calculate production uncertainty.

May 1, 2004

By A. R. House, G. W. Shepherd

Newmont USA Limited owns and operates the Phoenix Mine near Battle Mountain, Nevada, USA. The existing milling facility has operated since 2006 (House, 2010). Following the startup of the milling operation, and coupled with the upswing in the copper market, Newmont realized that Phoenix had no process option to treat transition and oxide copper ores. This meant that potentially revenue generating ore would be mined as waste. With no system in place to treat the transition and oxide copper, work began to determine the most feasible approach. After evaluating multiple options, the flow sheet was set for a runof- mine (ROM) heap leach pad and solvent extraction/ electrowinning plant (L-SX/EW). This paper will discuss the eight years of successes and challenges with developing the copper L-SX/EW plant and achieving commercial production of copper cathode.

Jan 1, 2014

By C. H. Stockwell

RICE LAKE-BERESFORD LAKE area, situated 100 miles northeast of Winnipeg (Figure 1), is Manitoba's foremost gold mining district, although it is exceeded in gold production in the Province by the Flin Flon base-metal mining district. At present, the area is producing at the rate of about one and three-quarter million dollars annually, almost entirely from the San Antonio and Gunnar mines. The total production to date is about $14,000,000. Of this total, over $7,000,000 has come from the San Antonio mine, over $2,000,000 from the Gunnar mine, about $4,000,000 from the Central Manitoba mine, and the balance from several smaller properties. The writer has led Geological Survey parties in the area for the past four summers. The present paper gives a summary of the results of this work and also includes the findings of C. S. Lord, who was in charge of a party for one year. Much valuable information was obtained from earlier published reports on the area and from officials of mining companies, to whom the writer is indebted for their kindly co-operation. It is impossible in this short paper to give proper credit to the earlier workers or to discuss certain points o disagreement between their conclusions and those presented here. For further information the following references may be consulted.

Jan 1, 1940

By S. Frimpong

Hydraulic shovels are widely used for primary production in surface mining operations. Variability in material diggability, unstructured mining environments and limited space and operator inefficiency affect the performance of these shovel excavators. Dynamic models of the hydraulic shovels are essential for understanding and improving machine performance. This paper contributes to this subject area by advancing hydraulic shovel kinematics and dynamics using the modified Newton-Euler method. A virtual simulator is developed to simulate the hydraulic shovel performance in the ADAMS environment. The simulator is validated with data on shovel geometry and the physical and mechanical properties of a formation in a surface mining environment. The results indicate that a shorter digging time increases the shovel operating power requirements, and that the required peak power increases by 100% when the digging time reduces by 50%. Simulation results also show that a shallow trajectory facilitates the digging process, with 50% reduction in peak power requirements compared to a deep one. This simulator provides a powerful tool for performance monitoring, excavation process designs and structural optimization of hydraulic excavators. This work also forms the basis for developing comprehensive simulator models for automated shovel operations in constrained mining environments.

Jan 1, 2005

By J. R. Goode

"Coarse ore sorting is here defined as the physical separation of a mixture of coarse (+3/8 inch) ore particles into two or more separate groups of total value greater than that of the unsorted ore. An ore will probably be sortable if the geology of the orebody and the mining practices employed meet conditions outlined in this paper.The paper points out how sorting can substantially reduce tonnage variable operating costs because sorting can double the mill head grade of amenable ores by rejecting waste rock from the mine output. The effect of sorting on ore reserves is outlined. It is also suggested that sorting is a low cost alternative to conventional expansion.The mode of operation of the Ore Sorters Kadel 13 Photometric and MK VI A Radiometric sorters is detailed. The report concludes with detailed descriptions of the photometric sorting plant operated by the Doornfontein Gold Mining Company is South Africa and the Radiometric Sorting Plant presently under construction at the Schwartzwalder mine of Cotter Corporation in Colorado."

Jan 1, 1975

By M. Maccagni, J. Nielsen

"Engitec developed the EZINEX® Technology some years ago to recover zinc from oxidized secondary sources. This process works at neutral pH and can take into solution any kind of metal, but iron is rejected and remains in the leach residue. Engitec has also developed the FLUOBORATE System, which is able to recover lead and copper from relevant concentrates. Some iron is leached into solution, but it is controlled through a solution purification bleed treatment. In this paper, we present the two above mentioned technologies. They are very different with regards to the chemical environments and the methods used to control the build-up of iron in solution, but both systems are suitable to treat iron bearing feeds.INTRODUCTIONIn the design of hydrometallurgical processes, the most important issues are the water balance, the filtration and the control of impurities. This is particularly important when the process includes an electrowinning unit. Iron has been one of the most problematic elements to remove, especially in acidic environments.Engitec Technologies has developed several hydrometallurgical processes divided in two different electrolyte lines: the Fluoborate Technology for the recovery of lead and copper from primary and secondary sources and the Ammonium Chloride System based on a chloride electrolyte for the recovery of different non-ferrous metals, among which zinc and lead are the most important. In both cases, iron is present in the feed and needs to be eliminated from the solution. It is not a problem for the quality of the metal produced, but when present in solution, it consumes the basic electrolyte reducing its free concentration which is very important both for both the leaching and electrowinning unit operations. Both process systems are very peculiar, the fluoborate case being much more intriguing."

Jan 1, 2016

By Craig M. Sams

"Variable speed mill popularity has grown during the last 10 years with almost every SAG mill fitted with a variable speed drive. In addition, many of today’s larger ball mills are running a variable speed drive for various reasons. In the past, motor suppliers, especially gearless drive suppliers, have considered mills as being an overpriced rotor. This has lead to mills demanding more torque than what a motor can generate. This paper identifies the reasoning of what has happened and how to mitigate the mismatch in the future. Technical and economical issues are discussed, allowing mill operators to make an informed decision of which path to take in deciding what motor to put on a mill.INTRODUCTIONIt has been generally accepted in the past that motor suppliers and specialists in engineering companies understand the workings of a SAG mill or a ball mill and although there is a fair knowledge within the industry, in regards to mill torque requirements, the advent of variable speed drives in ball mills has shown the writer that a complete understanding of the mill torque requirements are not fully understood.This paper will discuss two aspects of mill torque requirements, (operating torque at various charge levels and start up torque), and how it relates to specifying the proper motor torque requirements.MILL OPERATING TORQUEMill operating torque at a given charge level and density in a mill is essentially constant throughout the entire speed range. For the purpose of this paper, we will take a 38’x 22.5’, 20’ EGL, SAG mill and provide the power draw at variable speeds but fixed loading conditions.The power draw and mill torque of this mill at 8% ball charge and 28% total loading (Highlighted) is shown below as Figure 1, at variable speeds."

Jan 1, 2007

By Ivan C. Machado

Jaguar Mining Inc. is implementing a 1.1 Mtpy, 7-year LOM gold project in the Iron Quadrangle (?Quadrilátero Ferrífero?), Brazil. Construction is on schedule and startup is programmed for Q2 2010. Mill feed grade averages 4.43 g/t and LOM gold production is estimated at 800,000 oz. The project entails two sulfide underground mines and three oxide/transition open pit mines. A state-of-the-art flotation/gravity concentration/CIP Plant has been designed based on testwork carried out by internationally recognized Canadian, U.S., and Brazilian laboratories. The mass recovery of the flotation section is only ca 10%, while its gold recovery is about 90%. Therefore, the CIP-ADR Plant will treat only 10% of the solids mass contained in the mill feed, while 90% will be fully cyanide-free material that will be partially used to feed a Backfill Plant. The leached tailings will be conveyed to a rather small tailings dam, whose 20- m3/h supernatant solution will be treated by a new electrolytic technology. The plant design contemplates a High Density Thickener for the cyanide-free rejects exceeding the backfill demand and a Regrinding Section before the Leaching Circuit. The estimated overall metallurgical recovery sits around 92%. This paper focus on the use of modern technologies to reduce costs, risks, and liabilities.

May 1, 2010

By M. Beth McClenaghan

This paper summarizes diamond exploration techniques used in glaciated terrain, focusing on indicator mineral and geochemical methods applied to glacial sediments. Understanding the ice flow history, depositional history, and stratigraphy of glacial sediments are essential to successful sampling, interpretation and follow-up of indicator mineral and geochemical anomalies related to kimberlites. Kimberlite indicator minerals survive glacial transport over long distances and the relative abundance of each mineral in till is a function of the primary mineralogy of individual kimberlites. Indicator mineral distributions observed at a regional scale define the net effect of glacial dispersal, often along different ice flow directions. Local-scale distributions define individual dispersal trains. The medium sand (0.25 to 0.5 mm) fraction of heavy mineral concentrates prepared from glacial sediment samples is best suited for indicator mineral surveys. The application of till geochemistry to diamond exploration is increasing because it is significantly cheaper than indicator mineral analysis and it can be performed quickly. The <0.063 mm (silt+clay) and 0.5 to 2.0 mm (coarse sand) fractions provide the best geochemical contrast between background and kimberlite-rich till. Kimberlite pathfinder elements that provide good contrast include Ni, Cr, Ba, Co, Sr, Rb, Nb, Mg, Ta, Ca, Fe, K, Ti and REE, the relative importance of which will depend on kimberlite composition as well as that of the surrounding bedrock.

May 1, 2002

?? Intro ?? Mass blast principle ?? LaRonde evolution toward mass blast ?? Overview ?? Mining method ?? Longitudinal ?? LaRonde evolution (2002 to today) ?? Drill and blast design ?? Consumptions and statistics ?? Mucking strategies ?? Case study ?? Examples ?? Conclusion ?? As underground mines extends to greater depths, few questions must be asked: ?? How to: keep operations safe eep operation effective reduce the cost maintain and control the dilution ?? Geomechanic method and practices; significant advances have been observed in the field of: ?? ground support ?? mining sequencing ?? Drilling and blasting; research and development has been less extensive, probably due to the following characteristics: ?? Drill and blast are mainly production-oriented ?? Drilling and blasting are more oriented toward productivity ?? Technology relies heavily on suppliers ?? Highly stressed ground conditions ?? generally help the explosives to break the rock for fragmentation ?? intensify over-breaks or blast-induced

Feb 1, 2008

By Hua-Zhong Yu

Gold is one of the most widely used substrate materials for self-assembly. Self-assembled monolayers (SAMs) prepared from alkanethiols and their derivatives on gold are the most reliable and well-studied systems to date, which have attracted much attention because of interest in two-dimensional molecular assemblies, and of their potential applications in molecular devices, sensors, and functionalized interfaces. Gold electrodes are also very important in microelectronics and electroanalytical chemistry. This work reports the characterization of a new type of gold substrates for self-assembly. The gold substrates are constructed from recordable compact disks (R-CDs) with simple and straightforward wet-chemical treatment, and can be made at desired sizes and shapes that satisfy different experimental needs. In particular, an easy, inexpensive, and reproducible method to prepare self-assembled monolayers (SAMs) on CD-R gold substrates after removing the protective polymer films with concentrated nitric acid was described.

Oct 1, 2003

By Tarrant Elkington

Underground mine planning practices are typically manual and time consuming and will often produce sub-optimal solutions due to the application of generic rule-of-thumb assumptions or ?tried and tested? choices. The development of computer-automated tools for underground mine planning enable a wide range of scenarios to be considered rapidly in arriving at an optimised solution, subject to input assumptions. We have applied these tools to demonstrate ?optimised? solutions that challenge industry standard practices. Further, we have incorporated grade and price/cost uncertainty into these tools to gain an understanding on how the consideration of uncertainty may further alter strategy selection. Finally, we enable the tools to dynamically adjust cut-off grades in conjunction with the evolution of prices/cost.

May 1, 2010

By M. Sturzenegger

This paper documents a field survey using long-range terrestrial digital photogrammetry at the Palabora open-pit mine, South Africa, for multi-scale characterization of rock mass discontinuities. Stereomodels covering the entire mine were generated based on photographs taken from a distance of 1600m across the pit, using a series of f=20-400mm lenses. Details on the methodology used and its accuracy are discussed. Preliminary results on discontinuity orientation, persistence and intensity are presented, highlighting the effect of observation scale. The potential uses of long-range terrestrial digital photogrammetry in open-pit mine and large natural rock slope environments is emphasized. The use of an f=400mm lens from distances larger than 1.5km may represent an important step forward in the geotechnical characterization of inaccessible remote rock faces.

May 1, 2009

By Janis A. Shandro

The mining sector is a major economic driver for Canadian, and British Columbian communities. In parallel strong commitments have been made by industry to the well-being and sustainability of associated communities. However, these dimensions are the least understood. Especially lacking are focused regional investigations that compare the well-being and sustainability of communities dependent on different resources sectors. It is hypothesized that this type of comparative analysis will help to foster a greater understanding of what makes a resource or mining community healthy and sustainable. This paper describes research that examined community-level indicators associated with well-being (e.g. education, income and employment) and sustainability (e.g. economic diversity). The indicators were derived from Canadian Census data for 31 British Columbia resource-based communities (with a focus on mining) during a period of time (1991 to 2001) when resource sectors experienced an economic downturn. Our findings identify that during this decade, mining communities differed significantly from other resource-based communities, and comparative analysis of census derived indictors illuminate challenges that mining communities in British Columbia face with respect to wellbeing and sustainability (such as economic diversity, unemployment, and population loss). To contribute to the mining sector?s efforts towards meeting their commitments to communities, this paper concludes by proposing strategic opportunities aimed at the enhancement of mining community sustainability for policy-makers, communities, and the mining industry to consider.

May 1, 2011

By Khosrow Ebrahimi

We document the occurrence, mineralogy and firing properties of magnesite from hydrothermal deposits in the upper Cretaceous ophiolites of Eastern Iran. These deposits occur as thin veins of nearly pure cryptocrystalline magnesite with only trace amounts of quartz, calcite, and dolomite. Ratios of CaO/SiO2 in the bulk ore are variable. The composition of dead-burned magnesite from these deposits, calcined at different temperatures and durations, is predictable from phase equilibria. Textures of the calcined magnesite were studied by SEM; results show that the principal impurites produced during calcination are forsterite, monticellite, merwinite, dicalcium and tricalcium silicates, and that these are located principally at triple junctions of the periclase crystals. The size of periclase crystals increased with temperature and duration of calcination and the amount of periclase-periclase grain contacts was reduced by increasing the concentration of impurities in the starting products. EPMA show: 1) that CaO and FeO contents in periclase increase steadily with an increase in the CaO/SiO2 ratio and the FeO content of the bulk ore, respectively, and 2) that limited solid solution exists between impurites. This study demonstrates that high quality dead-burned magnesia refractories can be produced from the Iranian magnesite with low CaO, SiO2 and FeO contents.

May 1, 2004

By B. Haugrud, E. McConaghy, M. Collins, G. Smith

"Laterite ore processed by the Ambatovy Joint Venture in Madagascar is primarily limonitic in nature, containing about 40 to 45 wt.% Fe and 1.1 wt.% Ni. The process selected for treatment of this ore considered the behavior and deportment of iron in each step of the commercial flowsheet. Such considerations included nickel and cobalt recoveries, reagent consumptions, liquid-solid separation characteristics, and both intermediate and final product purities. In this paper, the results for the first three years of commercial operation at Ambatovy are compared with the design parameters, with emphasis on the behavior of iron.INTRODUCTION The main component of nickeliferous laterite ore is iron, and the Ambatovy deposit in Madagascar is no exception. The Ambatovy ore is primarily limonitic in nature, containing about 40 to 45 wt.% Fe and 1.1 wt.% Ni. Since the nickel content of the ore is roughly one fortieth that of iron, successful recovery of nickel depends on close control of the behavior of iron in the selected process. Exploration of the Ambatovy area, which is located to the east of Antananarivo, the capital of Madagascar, dates back to 1960, when the Malagasy Service Géologique carried out a limited pitting and auger-drilling program. Phelps Dodge Corporation (now Freeport-McMoRan Copper & Gold, Inc.) was granted the mining rights to the property in 1995 and carried out significant resource definition, environmental assessment and engineering studies between 1995 and 2001 (Chou, Rooke, Williams, & Hanks, 2000). In 2003, Dynatec Corporation, which was formed in 1997 by the merger of Dynatec International Ltd. and Sherritt International Consultants Inc., signed a joint venture agreement with subsidiaries of Phelps Dodge to evaluate the Ambatovy Nickel Project. Dynatec then became extensively involved in the development of the project, including process selection and pilot plant testing in Fort Saskatchewan (Collins et al., 2004, 2005, 2009; Collins & Vardill, 2005). Dynatec acquired 100% of the project in 2005 and a joint venture between Dynatec, Sumitomo Corporation, Korea Resources Corporation (KORES), and SNC-Lavalin Inc. (SLI) was formed shortly thereafter to provide funding for further development. SLI was responsible for engineering, procurement and construction management of the commercial facilities. Sherritt International Corporation reacquired Dynatec Corporation, including 40% ownership in the Ambatovy Nickel Project, in 2007. The current Ambatovy Joint Venture consists of an integrated nickel and cobalt mining, processing, refining and marketing enterprise between subsidiaries of Sherritt (40% owner and mine and plant operator), Sumitomo Corporation (32.5% owner) and KORES (27.5% owner)."

Jan 1, 2016

By Y. Faitakis

In the mining industry, maintenance is a key priority and a major expense. As mining equipment is large in scale, high in cost, and difficult to tow, it is key to maintain equipment on a timely basis. Breakdown in -40°C or away from a maintenance station can cause great costs in repair as well as lost production. It has often been quoted that about 5% of the North American production is lost every year due to unscheduled downtime. About one-third of the downtime is attributable to equipment failures. From this fact alone, it is evident that proper equipment maintenance can add tremendous value to the bottom line. As organizations and equipment become more sophisticated, maintenance expectations begin to evolve. This evolution can be traced through three generations: The first generation (1940?1950): A ?fix it when it broke? attitude prevailed during that time, mostly because the industry was not highly automated. The second generation (1950?1980): Automation and mechanization of the industry increased. The industry now was dependent on machines performing the majority of the work. Preventive maintenance (overhauls at fixed intervals) appeared as the first maintenance practice. Maintenance costs started to rise rapidly. The third generation (1980?): Assets become more complex. Failure modes are better understood and computerized maintenance methods are becoming mainstream. Condition-based maintenance (CBM) starts to gain ground as a cost-effective alternative, replacing the fixed interval overhauls. As corporations amalgamate and market places are becoming more complex, multi-functional teams become responsible for maintenance. At the beginning of the third generation, maintenance organizations began embracing technology to provide efficiencies in maintenance management. A strong push was made to transition from reactive maintenance to proactive maintenance. At the forefront of this push is condition-based maintenance.

Jan 1, 2004

By Y. Faitakis, G. J. Powley, C. Mackenzie

"In the mining industry, maintenance is a key priority and a major expense. As mining equipment is large in scale, high in cost, and difficult to tow, it is key to maintain equipment on a timely basis. Breakdown in -40°C or away from a maintenance station can cause great costs in repair as well as lost production.It has often been quoted that about 5% of the North American production is lost every year due to unscheduled downtime. About onethird of the downtime is attributable to equipment failures. From this fact alone, it is evident that proper equipment maintenance can add tremendous value to the bottom line. As organizations and equipment become more sophisticated, maintenance expectations begin to evolve. This evolution can be traced through three generations:The first generation (1940–1950): A “fix it when it broke” attitude prevailed during that time, mostly because the industry was not highly automated.The second generation (1950–1980): Automation and mechanization of the industry increased. The industry now was dependent on machines performing the majority of the work. Preventive maintenance (overhauls at fixed intervals) appeared as the first maintenance practice. Maintenance costs started to rise rapidly.The third generation (1980–): Assets become more complex. Failure modes are better understood and computerized maintenance methods are becoming mainstream. Condition-based maintenance (CBM) starts to gain ground as a cost-effective alternative, replacing the fixed interval overhauls. As corporations amalgamate and market places are becoming more complex multi-functional teams become responsible for maintenance.At the beginning of the third generation, maintenance organizations began embracing technology to provide efficiencies in maintenance management. A strong push was made to transition from reactive maintenance to proactive maintenance. At the forefront of this push is condition-based maintenance."

Jan 1, 2004

By Peter Mitschke, Friedrich Rosenstock, Heinrich Meiler

"The development of the Centrifugal Mill jointly by Chamber of Mines (Johannesburg) and LURGI GMBH (Frankfurt) had been described by L. Kitschen e.al. during the 14th IMPC at Toronto in October 1982. Further investigations, using a 55 kW semi-industrial mill, installed at LURGI's Research Laboratories, were concentrated on efficiency and wear in grinding.The test results showed, that efficiency increases when increasing the ball load between 60 and 80 % by volume. Furthermore, the efficiency is increased by speeding up the mill, thus increasing the centrifugal force to up to 14 times the force of gravity. Applying these findings to grinding of a Canadian iron ore spiral concentrate, a saving in grinding power of 30 % was experienced, when comparing with ordinary wet ball milling.Investigations of several shapes of the grinding chamber cross section and linings and several types of materials showed, that no increase of liner or ball wear will occur compared to conventional ball mills when choosing suitable lining patterns. 1. DEVELOPMENT OF THE CENTRIPUGAL MILLThe centrifugal mill was developed with the aim of finding a grinding unit that can operate at a higher power concentration than the conventional tumbling mills.LURGI felt the necessity for such a mill in connection with a hydrometallurgical process developed at the beginning of the seventies, which incorporated an activating grinding step as one of the essential process features. At that time, the Chamber of Mines in Johannesburg was investigating possibilities of underground wet grinding and preconcentration of gold ores aiming at a decrease of mining costs by reducing the quantities, especially for mines operating at depths up to 3600 m, by changing over from rope hoisting to hydraulic transportation systems. After the Chamber of Mines had initiated the development work on its own, in 1974 a cooperation between the two organisations was started."

Jan 1, 1985

By P. A. Riveros, W. D. Gould, R. Molnar, D. W. Koren, P. Bédard

This paper reports the results of the field demonstration campaign of a new process for removing and destroying ammonia from mining/ metallurgical effluent solutions. The 50-day campaign was carried out at a uranium plant in Saskatchewan, Canada. The process was developed by adapting and integrating two well established technologies: zeolite adsorption/ elution to extract the ammonia from the effluent stream and to produce a concentrated ammonia eluate; and conversion of the ammonia in the eluate to innocuous nitrogen by applying bacterial nitrification-denitrification (NH3 = > NO3 - => N2). The data show that reasonable target criteria were met, under very challenging operating conditions. Problem areas and possible causes for poor performance are identified. Preliminary and generic cost estimates of the process are also presented.

Jan 1, 2003