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By Dolf W. Fieldman

Most recently the geologic setting of the mineral deposits in the Silver Cliff district is described by William M. Sharp in ?Geologic Map of the Silver Cliff and Rosita Volcanic Centers, Custer County, Colorado?, (U. S. G. S. Map I- 1081). The discussion will relate only to the southern half of the Silver Cliff volcanic center and differences in geologic interpretation, which are largely structural, will be pointed out as they arise. Only the manganese/silver zone of the Kate Area will be discussed in detail.

Jan 1, 1980

By L. A. Roe

The year 1867 marks the first year of commercial production of phosphate rock in the United States. South Carolina produced almost all of the domestic output of mineral phosphate until phosphate mining began in Florida in 1888. During the period 1868 to 1949 the total marketed production of domestic phosphate rock was about 186 million long tons of which 71.5 percent was produced in Florida, 18 percent in Tennessee and 7 percent in South Carolina (1). From 1949 through 1960, Florida phosphate rock production has ranged Prom 71 to 77 percent of the total domestic production. Since three-fourths of the domestic phosphate production is from the Florida field, and since most of the phosphate from the Tennessee and Western fields is not processed, but used directly as electric furnace burden, this paper will concern itself almost entirely with water requirements for mining and processing ore from Florida. Figure 1 summarizes phosphate rock production for Florida vs. total United States production over the period 1947-1960.

Jan 1, 1962

By Morris Loshinsky, George Ziegler

NEW ROUTES - 63rd STREET CROSSTOWN The New Route construction along East 63rd Street in Manhattan began in 1969 with the East River tunnel connecting Manhattan and Queens. The 63rd Street Line, once in Queens, is planned to connect to another new route called the Queens By Pass or Super Express (See Exhibit 1) which would connect to the Queens Boulevard Line at Forest Hills. The purpose of the Queens By Pass was to alleviate subway congestion to and from the Borough of Queens, whose population had rapidly expanded during and after World War II. The existing Queens Boulevard subway lines (the "E" and the "F" trains) are almost filled to capacity at their terminal stations with passengers from Long Island. Passengers boarding trains enroute from the local Queens stations have difficulty boarding crowded trains, and, at times, cannot board the trains. The New Routes, thus, were to give additional train capacity into Manhattan and thereby relieve the crowded conditions along the Queens Boulevard corridor. PROFILE - METHOD OF CONSTRUCTION The portion of the New Route passing east-west under East 63rd Street on Manhattan (See Exhibit 2) had to snake beneath intersecting structures running north and south, such as the Con Rail tracks below Park Avenue and the 80 ft deep Lexington Avenue Express track structure along Lexington Avenue. Further, the Lexington Avenue Local tracks are in a separate structure which has a high profile close to the street surface. Therefore the 63rd

Jan 1, 1981

By Leslie E. Apodaca

INTRODTUCTION The use of spiral concentrators for processing fine coal particles is an old idea that has recently gained acceptance in the 11.S. coal industry. It was not onti1 the Australian Minerals Industry developed a spiral concentrator specifically for separating coal from ash in the latter 1970's and early 1980's that spiral concentrators were seriously considered as viable equipment for processing fine coal. The Wright Coal Spiral was introduced in 1980, the Mineral Deposits Limited Mark 10 Coal Spiral was introduced in 1982, and the Vickers Wyong Coal Spiral was introduced in the latter part of 1984. Each spiral design was different and utilized constant profile troughs, constant pitch troughs, compound profile troughs, and various splitter arrangements. Mineral Deposits Limited has combined the best features of the compound profile trough and constant pitch trough with critically-placed splitters to develop the MDL LD4 spiral concentrator which is a truly efficient coal washing spiral. This spiral concentrator was introduced into the U.S. Coal Industry in 1987. Recently, Mineral Engineering Technology of the United Kingdom and Multotec of South Africa have introduced their own coal spiral designs. Spiral concentrators were first installed in fine coal processing circuits in the Australian, South African, and Canadian Coal Industries in the early 1980's and in the U.S. Coal Industry in 1985. SPIRAL CONCENTRATOR SEPARATION PROCESS The separation process that occurs within the spiral concentrator trough is very complex, as it is a combination of three gravity separation processes. When the coal slurry first enters the spiral trough, each coal and ash particle and the water is subjected to centrifugal forces. These forces cause the water, light coal particles, fine heavy ash particles, and medium middlings particles to the outer vertical portion of the spiral trough. The coarse ash particles and the coarse middling particles remain on the inside of the spiral trough. The center or transitional area of the trough contains a mixture of middlings particles and near-gravity material that is present in the slurry, as shown in Figure 1. At the same time the coal and ash particles are suhjected to centrifugal forces, the trough design (both profile and pitch) causes the particles to be subjected to flowing film and stratified bed separations. The combination of these three separations, whose efficiency is dictated by the spiral troogh design, will effect the separation of the lighter coal particles from the heavier ash and middlings particles. As the slurry flows down the spiral, the profile and pitch design of the trough will counteract the centrifugal forces on the fine, heavy ash particles and fine middlings particles and cause them to migrate from the vertical portion of the trough to the center or inner portion of the trough. At the same time, any heavy particles trapped in the transitional area of the trough will be forced to migrate to the inner edge of the trough and any coal particles will be forced to migrate to the outer edge of the trough. SPIRAL SPLI'TTEP ARRANGEMENT The critical placement of splitters along the inner edge of the trough for removal of the heavy ash particles as the slurry flows down the trough further enhances the separation of the coal particles. At the bottom of the spiral trough are product splitters arranged to make a final separation of the slurry stream into clean coal, middlings, and refuse products.

Jan 1, 1988

An incremental-analysis-based stope design and cutoff grade calculation method was developed for an underground metal mine project. Traditional stope design methods are typically very time consuming and lack consistency and accuracy by manually drawing stope shapes. For quick reserve calculation and economic analysis, a new method named "3D incremental analysis based stope design" was created for mine-wide stope designs. The key idea of this method is to replace engineers' manual checking of each incremental ring with one calculation of all the rings, and to build the final stope shape with the maximum values. This process was realized through a 3D ring grid setup and proper naming conventions for rapid calculations. With this unique but practical method, multiple options for a mine design were completed within a short time before the final selection of optimal cutoff grade and best stope designs for the project.

Jan 1, 2012

By Eduardo Pimenta de Melo, Rambabu Pothina, Rajive Ganguli

Sensors are everywhere in the mining industry, with sensor information being used to monitor and operate processes. Therefore, when sensor information is wrong, economic losses can occur. Unfortunately, sensor errors are usually not detected till they become large. This is problematic as most calibrate their sensors no more than once a year (Beamex, n.d.). Using principles of data mining, where all relevant information is tapped to glean hidden information, Pothina [8] designed an algorithm to detect errors in temperature sensors in gold stripping circuit in Pogo mine, Alaska. This paper continued his work by analyzing the behavior of the algorithm on baseline data and testing the algorithm in new data and under more rigorous conditions. It also made a change to the algorithm. The modified algorithm performed very well in the new data. It also worked well under the new error conditions. Three types of errors were seeded, a fixed additive error (+ 2%), a fixed subtractive error (− 2%), and a noisy, normally distributed error, with a mean value of + 2%. Artificially seeded errors were detected within about 20 gold stripping cycles. Inherent bias in operation impacted algorithm performance by increasing the number of cycles needed to detect errors. This paper reinforced Pothina’s [8] conclusion that when data mining approach is used, sensor errors can be detected even when they are pretty low. Significant economic losses can thus be minimized.

By Franco Oboni, Iain G. Bruce

The design of tailings containment structures relies on well-understood engineering methods being applied consistently. Unfortunately, not all facilities are designed or managed to the same level of competency. To standardize procedures, the Mining Association of Canada (MAC, 1998) prepared a “Guide to Tailings Management.” It recommended review of designs and an assessment of the risks associated with tailings impoundments be implemented during all phases of amine life. This paper describes how the quantitative risk assessment (QRA) process can be used to define risks associated with the design, construction and operation of a tailings management facility. And it discusses how, once the risk tolerability curves (RTC) are defined for a project, they can assist the risk management (RM) process.

Jan 1, 2002

By Gus L. Maciula

Although I will briefly review the current status of coal slurry pipeline technology, I wish to make it clear that this is not a technical paper. It is intended instead to review the current situation on energy resources and requirements, and the environmental, political and economic considerations that mandate a serious consideration of Slurry pipelines as a viable mode of coal transportation into the Georgia and Florida markets. In order to more fully appreciate our current energy situation, it will be helpful to go back a few years and review the evolution of our so-called energy "problem." It was about two decades ago that the first and only major natural gas transmission pipeline was built into the State of Florida by Florida Gas Company. This line was conceived and implemented during a time when gas was plentiful and cheap, and it appeared at that time that unlimited gas reserves were continually being discovered, thus assuring the availability of a clean, cheap fuel and the ,viability of the pipeline system. One of the major factors justifying the original pipeline construction as well as subsequent expansions was a series of long-term commitments under which Florida Gas transported natural gas owned by electric utilities for use as boiler fuel. Thus for the past 20 years Florida industry, commerce, and domestic fuel requirements have been met either directly or indirectly through clean, cheap natural gas which would not have been otherwise available without the pipeline system.

Jan 1, 1978

By S. Page, R. Bhaskar

The development is described of a real-time tracer gas sensing system for use in fell-scale laboratory studies of air flow behavior around mining machines. A semiconductor sintered tin-dioxide gas sensor is used for gas analyses. A data acquisition and analyses software specific to the sensor characteristics was also developed as part of the system. The system permits the study of transient behavior and assists in obtaining a better understanding of the movement of air around mining machines and in the study of the effect of potential airflow modification devices on the dust exposure of face personnel. It seeks to replace the current method of using a centralized infrared gas analyzer that polls several sampling points using an array of solenoid valves and gas line purgers. The polling results in a significant time lapse between the first and the last set of readings. The system described in this paper has the advantages of real-time sampling and safe operation.

Jan 1, 1992

By William C. Peters

"A large proportion of the earth's surface is blanketed by young sedimentary formations and by recent lava flows. How many Guanajuatos lie concealed beneath the rhyolitic capping of the Sierra Madre of Mexico? How many Kirkland Lakes are under the drift cover of the Canadian Shield? How many Wilunas are still hidden by the alluvium of the desert of Western Australia? How many ore deposits lurk underneath the basalt-covered plateaus of the Columbia River region? If erosion at Goldfield, Nevada, had stopped 100 feet higher, probably no ore would have been exposed. How many Goldfields are still awaiting discovery?" --Hugh Exton McKinstry, 1948

Jan 1, 1969

By P. Jonsén

Understanding mill charge motion is important. In the charge, the centre of gravity is shifted from the rotational centre of the mill system, and its motion is induced by rotation of the mill, while at the same time the charge creates a torque into the mill system. Breakage of ore particles and wear of liners/ball media are closely linked to the motion. To study these phenomena in a physically correct manner, numerical models for different parts of the mill system are needed. Validations of such models are scarce, because of the difficulty to measure in a tumbling mill. Experimental measurements in a lab mill were done for diverse load cases: varying feed materials, mill fillings, mill speeds and pulp liquids. The mill is set up to directly measure the charge-induced torque. The accuracy is good with relative uncertainty smaller than ±2% for relevant load cases. A full three dimensional numerical model of the whole mill is used to predict induced torque. Agreement between predicted and measured torque at steady-state is good. In addition, the model can accurately predict the mill start-up behavior for torque and mill power. This proves that the model is physically correct, and can be used for full-scale mills.

Feb 27, 2013

By W. A. Crosby, A. Bauer

The recent increase in size of open-pit mining operations has resulted in major improvements in efficiency that are beneficial to the mining industry. Higher bench heights, larger diameter blast-holes, and more powerful explosives have played an important part in reducing mining costs. These measures have, however, resulted in increased energy concentrations in the blast area, which can result in severe backbreak problems for final pit walls. If backbreak is not controlled, a decrease in the overall pit slope angle will ultimately be necessary, and consequences, such as decreased recoverable ore reserves and increased waste-to-ore ratios, will result. Greater amounts of loose face rock will be produced, and planned safety berms will be less effective or nonexistent. Hazardous working conditions can also result. Remedial measures, such as scaling large areas and using wire mesh or other artificial support, are very expensive and difficult to implement. There must be a trade-off between the money saved by using larger blasts, and the time spent to maintain pit wall quality. The best approach is to control blasting effects so the inherent strength of pit walls is not destroyed. Presplit and trim blasting are two control blasting techniques used to accomplish this. Both techniques are designed to create a low explosive energy concentration per unit of wall area at the perimeter of the pit. Energy concentration of the main production blast must also be controlled to avoid damaging the final pit wall. A low-energy concentration at the final wall can be obtained by decoupling charges, decking charges, using less powerful explosives, decreasing blasthole diameters, and changing the burden and spacing. Rock properties-fragmentation and the final state of the pit wall-influence the success of a blast. The most important properties to consider are: in situ rock strength, and the nature, frequency, and orientation of structural features. Since these variables cannot be controlled, they must be evaluated by suitable field tests, and then a control blast can be designed using controllable variables, such as spacing, burden, and hole diameter, so the blast will be successful for appropriate rock conditions. One main thrust of this article is to show how control blasts can be successfully designed for larger hole sizes, up to 381-mm-diam. While efforts to produce a good control blast in shovel/truck pits have been ongoing for some time, recent use of a modified presplit technique in dragline operations has helped reduce water problems, improve safety, and increase dragline productivity in a number of surface coal mines. This article presents examples on designing and using presplit and trim blasting for large hole operations in both shovel/truck and dragline mines. Presplit Blasting As introduction to presplit blasting, Fig. 1 illustrates a typical presplit blast layout using 102 mm-diam presplit holes for 381¬mm-diam production holes. For this type of blast, presplit holes would normally be drilled first, ahead of main production holes. The choice can then be made between loading and firing the presplit line or infilling the main blast. In the latter case, the presplit line would be fired instantaneously 100-150 milliseconds before the main blast. As shown in the figure, the presplit line is formed ahead of the main

Jan 2, 1982

By K. A. Lewandowski

Binders have been suggested as an aid for agglomeration to improve copper recovery in heap leaching operations. However, it has not been established if the use of binders would negatively affect the solvent extraction process, which is used to purify the pregnant leach solution from the heaps and remove any contaminants. Such negative effects would lead to an increase in processing costs or a decreased in copper production. The controlled studies reported here have shown that some binders (a polyacrylamide and a waste treatment additive) did not interfere with the solvent extraction process. Other binders (a polyvinyl acetate emulsion and tall oil pitch) negatively impacted copper solvent extraction and, therefore, should not be used in copper heap leaching plants.

Jan 1, 2009

By D. Olsen, S. Cole, J. Strid, G. Colzani

This paper focuses on the underground tunnel work at the Hollywood Water Quality Improvement Project (HWQIP) in Los Angeles, CA. The HWQIP is being constructed to provide a water distribution system to bypass the existing Hollywood Reservoir System, which supplies drinking water for 500,000 people. The major project features include, a 2.9-meter diameter 1,829 meter long bypass tunnel, a 1.8-meterdiameter 366 meter long utility tunnel, 3 jack and bore tunnels, two 136 million liters underground circumferentially wrapped pre-stressed concrete water storage tanks, associated piping, and mechanical facilities. The physical project location coupled with strong community involvement and stringent environmental concerns was a considerable driving force for this project located in the Cahuenga Pass area of the Hollywood Hills north of Los Angeles, CA.

Jan 1, 2001

By N. Arbiter, C. C. Harris

The economic advantages of large diameter ball mills can be compromised by unexpected capacity limiting conditions. These arise because media rotational flow to ore axial flow ratios, and the number of mill revolutions that ore is subjected to during residence, are both inversely proportional to mill diameter. Because of this, mixing efficiency and grinding kinetics may decrease and become capacity limiting when mill diameters reach a critical range. There are two possible scale-up problems involved in the design and use of mineral processing machinery: • Selecting the size and operating conditions for available larger equipment, to insure that operating results will match those obtained with smaller units; or •Extending the size ranges of equipment beyond existing limits. Previous research at Columbia University into flotation machine hydrodynamics has demonstrated the importance in scale-up of internal flow relationships; these perform a similar role in grinding (Arbiter and Harris, 1980).

Jan 1, 1982

By Arthur B. Steiker

Digital simulation was used to model a proposed underground' train system. The trains are to haul ore from numerous loading points beneath the production area of the mine to a central underground dump location, and then return to the mine. The purpose of the simulation was to aid mine engineers in studying various alternatives and configurations regarding track layout, crusher (dump point) specifications, dispatch procedures, fleet size, and train length, among others. The simulation' model can also be used to study the same aspects of existing haulage systems. To accommodate a wide and initially unknown range of system designs, a modular model structure was developed with major components devoted to track routing, train movement, loading process, dumping process, and dispatch. Key statistics tabulated were number of trains dumped during a simulated week, queueing delays in the mine and at the crusher, crusher utilization, cycle time, and percent of time for each: activity (loading, moving, dumping, etc.). The simulation results were instrumental in identifying a train system design which would reduce queueing delays and meet production goals with a minimum of trains and track mileage.

Jan 1, 1982

By George W. Bain

Deposits of metals in only slightly disturbed strata have been attributed to sedimentation processes contemporary with deposition of the strata. Recently this origin has been extended' to a greater variety' of deposits and local enrichment has been attributed to selective remobilization of metallic minerals in the host stratum. Effects attending metallization and deformation, and exact age' of the metallization are compiled to establish the sequence of events in ore deposit histories in order to clarify importance of remobilization within a formation relative to introduction from an outside source into an fav¬orable host. The pertinence respectively of deposit; origin and geometry to the work of the mining geologist is reviewed. Dwarf faunas in the Clinton iron ore, Tully pyrite bed and Rammelsberg deposit, indicate abnormal metal ions in the sedimentary environment. Slight¬ly disturbed strata are host rocks in the Swedish Kolm, Timna, Kupferschieffer, and White Pine deposit; the latter two have ore only in conjunction with tectonic structures.

Jan 1, 1966

By R. A. Metz, Willard C. Lacy

Rather than attempting to present a summary of the many and highly varied papers that have been presented at this symposium on sampling and grade control, I will attempt to extract the general philosophy of analysis and approach, and attempt to identify the trend of future developments. First, the term "sampling" is used with its broadest connotations. A sample consists of a representative portion of a larger mass, and must represent the mass not only in the grade of contained metals or minerals, but also in all other respects in terms of mineralogy and mineral quality (1, 5), deleterious materials, recoverability of economic components, physical behavior, geophysical response (1), and even archaeological and environmental aspects (7, 11). The sample must be taken from a locality and in such a manner and quantity that it is representative of the larger rock mass. This calls for complete and accurate geological control and an understanding of the nature and distribution of the contained chemical and physical elements and a record of the effectiveness of the different sampling methods. Second, value of a given mass of ore material is based upon its profitability - the difference between recoverable value and costs to achieve recovery, beneficiation and sale. There is a strong movement in mining geology control toward more complete analysis in determining cutoff grades and in grade control, as illustrated by the kriging of metallurgical recovery factors as well as grade at the Mercur Mine (8). To achieve a "profitability factor" as a guide for economic mining practice requires further integration of: 1) the value of contained metal or mineral, 2) percentage recovery of values, 3) dilution of ore with waste rock, 4) addition to, or loss of value as a consequence of by-product materials or deleterious components, 5) cost of producing a saleable product plus minimum profit to justify the effort (cutoff), and 6) cost of land restoration (7, 11). All these parameters vary with the rock type, rock structure, mineralogy, depth, geometry, mining and metallurgical methods, but they must be sampled and analyzed if sampling and grade control are to reflect profitability. A wide variety of deposits has been presented at this symposium; each deposit with its own problems and special solutions. Deposits containing high unit-value components, e.g. precious metals and diamonds, present special problems in the obtaining of accurate samples and generally require statistical analysis control methods or may disregard or modify occasional high or occasional low values, based upon experience (12). Grade control may be accurate for the long term but may vary for the short term. Bulk sampling is always essential. Deposits containing metals or minerals with low unit value are very sensitive to transport costs, and they are often very sensitive to small amounts of deleterious components or differences in physical or chemical behavior. Problems of sampling and grade control change with the genetic type of deposit, with the stage of deposit development and with the size of the information base. Precious metal epithermal deposits (2, 6, 8), because of rapid vertical zonation and erratic lateral distribution of values, have always been difficult to evaluate and maintain grade control and ore reserves. On the other hand, evaluation and grade control are relatively easy in bulk-lowgrade deposits (4, 13). However, these deposits generally have a low margin of profit and are sensitive to mining and beneficiaton costs, price fluctuations and political costs. Industrial mineral deposits (5) often must be evaluated on the basis of their behavior, rather than by chemical analysis. Environmental impact generally increases with the scale of the operation, but certain elements or minerals have especially high impact effects (7, 11). In the exploration phase there is no production control of sampling procedures and careful geological observations are particularly essential. The greatest number of problems is related to the oxidized outcrop where the chemical environment of the ore body has changed and the contained values may have been enriched, depleted or values left unchanged (2, 6). Present evidence suggests that gold values may be very mobile under certain conditions (2, 6) and stable under others. Everything must be sampled in detail. Principal values and by-product or deleterious elements may vary dependent upon their position within the soil profile. Such factors as geomorphic position, erosion rate, vegetation, climate, etc., may affect the interpretation (1, 3). During the development phase it is equally easy to overtest, to have "paralysis by analysis," as to undertest (3, 6). Bulk samplng and testing are

Jan 1, 1992

By E. K. C. Chanda

The best use of available reserves to give good metal recoveries relies on short term mine production scheduling.-The aim is usually to produce a plan to guide mining in specific areas that will enable mine operations to deliver the budgeted tonnes and grade to the mill and keep within the long range mine plan. Thus, short term production scheduling is an important aspect of the open pit mine planning function. Since the 60's increased attention has been paid to effective production scheduling as a means of improving the economic viability of existing mines. Hence, mine scheduling scheduling systems have been evolving rapidly during the last two decades. These systems include manual techniques, computer based simulation, mathematical programming and more recently Computer Aided Design (CAD). Some general drawbacks of the current scheduling systems are that firstly, the costs of acquiring and using them are not at all insignificant especially for small to medium sized pits. Secondly, there is an inherent trial-and-error aspect in these systems. Thirdly, they tend to be suited for specific orebody geometries, hence lacking the necessary generality. For instance, the use of computer programs for planning open pits to mine stratiform orebodies raises problems which are not usually met when massive orebodies are considered. There for, a need exists to develop simpler but effective short term pit scheduling procedures suitable for stratiform type orebodies, considering their geometry and geology. This paper describes a PC- based model designed to assist the planning engineer in optimizing the short term production schedule in open pit mines with stratiform orebodies. The model is based on a combination of linear goal programming and deterministic mining simulation. The orebody model is made up of ore and waste mining regions where winning and and/or stripping are taking place. These shovel regions form the basic planning elements in the model. This approach does not require the laborious preparation and use of a regular block model. The computer program consists of main modules: (i) Data capture - processes the raw data into the required format for mine planning. (ii) Precedence mining constraints - checks the status of each shovel .region at the beginning of a given scheduling period with regard to geometrical mining constraints such as undercutting. (ii) LP- Optimization - provides an optimal selection of ore shovel regions which do not violet geometrical constraints for mining in the period, the objective, being to maximize the contained metal equivalent in the blended R-O-M ore and at the same time to minimize deviations in grade and tonnage from the call values. (iv) Post LP-Simulation - enables the user to smooth out the LP solution in order to adjust it to a practically executable plan and simulates mining of ore and waste for the period. Shovel allocation to selected ore and waste shovel regions, unit operations and depletion of reserves are executed in this module. Preliminary testing of the model for monthly production scheduling using data from Nchanga OPen Pit on the Zambian Copperbelt indicates that it can be a useful planning tool and gives acceptable results.

Jan 1, 1992

At the Prospectors and Developers Annual Convention (PDAC) in Toronto, Canada mining and exploration companies of all sizes were on hand to discuss the year that was and those that will be. The following is a look at some of the companies with Canadian operations that were on hand for PDAC 2009. Iamgold Corporation is a leading mid-tier gold mining company producing approximately 31 t (1 million oz) of gold from seven mines on three continents. With record revenues of $870 million ? up 28 percent when compared to 2007 ? the company is focused on growth with a target to reach 56 t (1.8 million oz) gold production by 2012. During 2008, the company acquired the Essakane project in West Africa. The project is fully permitted, under construction and will contribute more than 9.3 t (300,000 oz) of lower cost production by late 2008. Iamgold increased its reserves by 55 percent, to 385 t (12.4 million oz) and its resources in-creased by 16 percent to 821 t (26.4 million oz) in 2008. Going forward, Iamgold has three areas of focus ? West Africa, Guyana Shield and Quebec ? with seven gold operations, five advanced projects and the Niobec niobium mine included. The Rosebel Mine in Suriname is Iamgold?s fl agship property. With measured and indicated resources of 300 t (9.6 million oz), it accounts for 30 percent of Iamgold?s production. Production there was up 20 percent compared with 2007 and further production increases are expected in 2009 and 2010. Mill expansion and optimization increased throughput from 8.9 Mt/a (9.8 million st) to 10 Mt/a (11 million stpy). In West Africa, Iamgold has joint ventures at Sadiola in Mali; Tarkwa in Ghana; Yatela in Mali and Daman in Ghana. Iamgold also has 100 percent ownership of the Mupane gold mine in Botswana and the Doyon gold mine in Quebec, Canada. Also in Quebec, Iamgold has 100 per-cent ownership of the Niobec niobium mine in Quebec. Niobium is used in high strength specialty steels.

Jan 1, 2009