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By C. L. Karr

The efficient management of the distribution of goods and services is important throughout the minerals industry. From the scheduling of processing plant operations, to the routing of work crews in mines, to the planning of product development, vast amounts of time, energy, and money are wasted due to poor planning and scheduling. Thus, the U.S. Bureau of Mines is investigating computational algorithms that can be used to minimize the economic losses related to scheduling and allocating resources. Although there is commercial software available for tackling many scheduling problems, there has been little relief provided for solving the difficult traveling salesman with time windows problem (TSTW). The TSTW problem is a "derivative" of the classic traveling salesman problem, and can be used to minimize the distance traveled by vehicles or personnel to visit all points on a tour, with the additional constraint that each point on the tour must be visited within a specified time window. This paper is a survey of published work in which genetic algorithms have been used to efficiently solve the traveling salesman problem and its more difficult derivative, the TSTW problem. A genetic algorithm is a search algorithm based on the mechanics of natural genetics, and has been used to solve a broad spectrum of engineering optimization problems. Results indicate that the versatility, searching power, and simplicity of genetic algorithms can be used to provide substantial improvement in the area of scheduling and resource allocation.

Jan 1, 1994

By Douglas N. Kendall

There are three definite steps in the making of a mining industry in any country. These are as follows: Step A - Geological Mapping This step covers the basic geological mapping of the country at scales of 1/250, 000 up to l/50, 000. This step eliminates territory and directs the exploration teams to the areas of potential interest. Step B Prospecting This step includes all phases from detailed geology through geophysics and drilling up to the point of proving that an economic ore body exists. Step C - Mine Development This is the expensive step, involving the creation of the mine, including shaft-sinking, ore treatment plant, etc.

Jan 1, 1963

The ever-increasing power (and decreasing cost) of computers has opened up substantial oppor¬tunities for 'Vision'-based systems in both on-line and off-line control. This paper reviews image analysis applications in use at the Julius Kruttschnitt Mineral Research Centre (JKMRC) for: •blast and mill feed size monitoring; •AG/SAG mill model-based control; •mineral liberation; and •froth flotation control. The SPLIT™ image analysis system is being used to estimate muck pile and ROM feed sizings. AG/SAG mill feed sizing is being used in a dynamic model for mill control. A new generation mineral liberation analyzer has been developed with Philips Electron Optics. The Philips-JKMRC mineral liberation analyzer offers a substantial improvement in resolution and speed over previous developments. While on-line liberation control continues to be something of a pipe dream, measuring liberation "one shift behind" is now feasible. A robust instrument has been developed to measure flotation froth bubble size and velocity. The instrument also derives a parameter that allows different froth textures to be distinguished. The instrument has been used for on-line control in coal and sulfide flotation. For coal froth, an online ash estimate has been achieved at one site and is being tested at other sites. Overall, image analysis is finding many applications in mineral processing and control.

Jan 1, 2000

By M. Li, W. R. Reed, J. P. Rider, J. D. Potts

"The National Institute for Occupational Safety and Health (NIOSH) has recently developed a series of validated models utilizing computational fluid dynamics (CFD) to study the effects of air-blocking shelves on airflows and respirable dust distribution associated with medium-sized surface blasthole drill shrouds as part of a dry dust collector system. Using validated CFD models, three different air-blocking shelves were included in this study: a 15.2-cm (6-in.) wide shelf; a 7.6-cm (3-in.) wide shelf; and a 7.6-cm (3-in.) wide shelf at four different shelf heights. In addition, the dust-collector-to-bailing airflow ratios of 1.75:1, 1.5:1, 1.25:1, and 1:1 were evaluated for the 15.2-cm (6-in.) wide air-blocking shelf. This paper describes the methodology used to develop the CFD models. The effects of air-blocking shelves and dust-collector-to-bailing airflow ratios were identified by the study, and problem regions were revealed under certain conditions. The simulation results could be used for future development of dust control methods, particularly to address respirable silica dust, for a surface mine blasthole drill shroud.INTRODUCTION Surface blasthole drilling can generate considerable amounts of respirable silica dust. These high dust concentrations can be exacerbated by the high silica content as drilling cuts through silica-bearing materials such as sandstone and shale, causing overexposures for miners to respirable silica dust. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is often fatal. A review of the Mine Safety and Health Administration (MSHA) respirable silica dust sample database from 2010 to 2016 for metal/nonmetal mining shows the following overexposure rates for occupations related to blasthole drilling: • 14.1% of rotary air drillers were overexposed to respirable silica dust (22 out of 156 samples) • 5.8% of rotary drillers were overexposed to respirable silica dust (9 out of 155 samples) • 7.3% of drill helpers were overexposed to respirable silica dust (3 out of 41 samples) • 7.5% of blaster/shotfirer were overexposed to respirable silica dust (3 out of 40 samples) Of significant interest is an x-ray surveillance study recently completed under the NIOSH Enhanced Coal Workers’ Health Surveillance Program (ECWHSP). This program offered free chest radiographs to surface coal miners in 16 states. Pneumoconiosis was found among 2.0% of the 2,328 screened miners with at least 1 year of mining tenure. Twelve miners had radiographic changes consistent with progressive massive fibrosis, and 9 of these 12 miners reported no underground mining tenure. All but 1 of the 9 miners worked at occupations that were in the vicinity of blasthole drilling, either as a driller, blaster, or blast crew member [1]."

Jan 1, 2018

By M. Li, W. R. Reed, J. P. Rider, J. D. Potts

The National Institute for Occupational Safety and Health (NIOSH) has recently developed a series of validated models utilizing computational fluid dynamics (CFD) to study the effects of air-blocking shelves on airflows and respirable dust distribution associated with medium-sized surface blasthole drill shrouds as part of a dry dust collector system. Using validated CFD models, three different air-blocking shelves were included in this study: a 15.2-cm (6-in.) wide shelf; a 7.6-cm (3-in.) wide shelf; and a 7.6-cm (3-in.) wide shelf at four different shelf heights. In addition, the dust-collector-to-bailing airflow ratios of 1.75:1, 1.5:1, 1.25:1, and 1:1 were evaluated for the 15.2-cm (6-in.) wide air-blocking shelf. This paper describes the methodology used to develop the CFD models. The effects of air-blocking shelves and dust-collector-to-bailing airflow ratios were identified by the study, and problem regions were revealed under certain conditions. The simulation results could be used for future development of dust control methods, particularly to address respirable silica dust, for a surface mine blasthole drill shroud. INTRODUCTION Surface blasthole drilling can generate considerable amounts of respirable silica dust. These high dust concentrations can be exacerbated by the high silica content as drilling cuts through silica-bearing materials such as sandstone and shale, causing overexposures for miners to respirable silica dust. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is often fatal. A review of the Mine Safety and Health Administration (MSHA) respirable silica dust sample database from 2010 to 2016 for metal/nonmetal mining shows the following overexposure rates for occupations related to blasthole drilling: • 14.1% of rotary air drillers were overexposed to respirable silica dust (22 out of 156 samples) • 5.8% of rotary drillers were overexposed to respirable silica dust (9 out of 155 samples) • 7.3% of drill helpers were overexposed to respirable silica dust (3 out of 41 samples) • 7.5% of blaster/shotfirer were overexposed to respirable silica dust (3 out of 40 samples) Of significant interest is an x-ray surveillance study recently completed under the NIOSH Enhanced Coal Workers’ Health Surveillance Program (ECWHSP). This program offered free chest radiographs to surface coal miners in 16 states. Pneumoconiosis was found among 2.0% of the 2,328 screened miners with at least 1 year of mining tenure. Twelve miners had radiographic changes consistent with progressive massive fibrosis, and 9 of these 12 miners reported no underground mining tenure. All but 1 of the 9 miners worked at occupations that were in the vicinity of blasthole drilling, either as a driller, blaster, or blast crew member [1].

Jan 1, 2019

By H. Huang, J. C. Wu, C. H. Xie, Y. Q. Xue, Z. H. Zhang

Two- and three-dimensional groundwater flow models for dewatering in an opencast mine are presented. The models focus on solving special problems using numerical simulations of the opencast mine. These special problems include the drying up of the aquifer, the movement of the model boundary and the prediction of the residual head. These models are used to describe the decline of groumdwater levels in the Yuanbaoshan Opencast Coal Mine and its neighboring area during the drainage period. The simulated values agree very well with the field data. There have been several successful examples of numerical simulation for predicting the mine dewatering rate in an opencast mine. However, The hydrogeological conditions for the Yuanbaoshan Opencast Coal Mine are rather complex, and the total average flow rate is very high at 4.676 x 105 m3/d (1.65 x 107 cu ft/day). In this paper, a two-dimensional groundwater flow model in a large area is developed to solve the problems mentioned above by simulating regional drawdowns of the groundwater level during the drainage period, and a three-dimensional flow model is developed to simulate the residual head near the open-pit bench.

Jan 1, 1998

By H. D. Sharma

INTRODUCTION Uranium mill tailings, by-products from the mining and milling of uranium oxide contain all decay products of uranium-238, uranium-235 and all the Th-232. The ore containing all daughter products of the parents U-238, U-235 and Th-232 is ground to approximately 50% under 200 mesh particle size and after extraction of uranium, the residue, described as tailings, is discharged into natural depressions confined by dams. These deposition sites are referred to as tailings ponds. Tailings ponds are located in two mining districts, Bancroft and Elliot Lake in the Province of Ontario, Canada. Some parts of tailings ponds are dry up to a depth of several meters, whereas other parts have a water table very close to the surface and still others are covered with water. The extent to which the daughters of uranium isotopes are in equilibrium with the parents U-238 and U-235 is dependent on the age of the deposit in which uranium occurs and the extent to which the decay products are removed by geochemical processes. In the mining district of Bancroft, the deposit is known to be approximately 1 billion years old, whereas in Elliot Lake, the deposit is considered to be approximately 2 billion years old. The ratio of radiogenic lead isotopes Pb-206 and Pb-207, can provide some estimates concerning the age of the deposits. If the tailings are not affected by geochemical processes, the tailings would contain all the daughters of the 4n+2 and 4n+3 series in equilibrium concentrations. The equilibrium activities of some members of the 4n+2 series are calculated in Table 1. [ ] The amount of radiogenic stable lead isotopes depends on the age of the ore deposits. If the deposit in each district is of the same age, a definite relationship is expected with respect to the activity of Pb-210 and the radiogenic stable isotopes. Approximately 33 million tons of the tailings have been deposited in the early 1960's, approximately 20 years ago. During this period of storage, the segregation of uranium daughters, like radium, the diffusion of gaseous product, Rn-222, and removal of precursors by geochemical processes, can cause dis-equilibrium. Earlier work concerned with the uptake of Ra-226 and Pb-210 by plants (Kalin and Sharma, 1981), indicated that the concentrations of Pb-210,in samples of the tailings taken, were lower than the expected equilibrium. The diffusion of radon from a variety of matrices has been studied (Tanner, 1964). It has been shown that the diffusion coefficient is dependent on the particle size in which its precursor is present, the moisture content and the surface conditions. The direct measurement of radon concentrations in the environment near the ponds is dependent on the metereological conditions. Kramer, Schroeder and Evans, 1964, have examined the variations in the concentration of radon near the ground level with respect to atmospheric variables, such as changes in barometric pressure, precipitation, wind velocities, thermal atmospheric instability. It is difficult to relate the total release of radon from the ponds to the atmosphere over an extended period. Our measurements of Pb-210 and total lead on tailings samples taken from 16 sites indicate that the ratios of the activity of Pb-210 to the mass of total lead can provide parameters which are helpful in the estimation of the total amount of radon and its decay products diffusing from the tailings ponds. In this paper, we present the results of measurements of activities of Ra-226, Pb-210 and total lead in samples from various ponds situated in both mining districts. The measurements were confined to samples taken at 0-25 cm depth from the surface.

Jan 1, 1981

By M. E. Smith

Chile is the world's largest copper producer and as such sets the standard of practice in copper SX/EW design. The authors summarize the liner systems used at many of Chile's major copper producers both operating and planned. The evolution in the state of the art is also discussed, considering both economic factors and Chile's burgeoning environmentalism.

Jan 1, 1994

By G. M. L. Robinson

The Clean Water Act, as administered by the Environmental Protection Agency, has mandated industry, government and the public to comply with potentially conflicting and vague water quality statutes, regulations and guidelines. Universal regulatory strategies have been developed which have introduced and have created regulatory, compliance and institutional conflicts. Conflicts have been created because National water quality performance goals and design standards are vague, and, in many cases, cannot be scientifically justified. Because of regulatory technical requirements to define background and environmentally impacted water quality characteristics, the ability to achieve regulatory compliance is difficult. Difficult issues requiring resolutions includes but are not limited to site specific surface and ground water quality classification systems, water quality standards and guidelines, point and non point pollution sources etc. Because of these statutory and regulatory complexities, a confrontational regulatory system has been created as it relates to: - defining performance criteria in relation to design criteria; - resolving water quality statistical compliance conflicts; - defining laboratory precision requirements; - determining background groundwater characteristics; and - locating a representative point of compliance. Because of these complex regulatory issues, the ability to balance goals, needs and economics has not been achieved or in many cases has not been attempted, without legal intervention. A few examples illustrating where water and waste management compliance conflicts have been experienced.

Jan 1, 1992

By Daniel Lum

The limestone resources of Hawaii are derived chiefly from emerged fringing coral reef and coastal dune deposits of Pleistocene age. These deposits are most abundant on the island of Oahu and other older islands and least abundant on the island of Hawaii, the youngest. Their origin and depositional environment were influenced by glacio-eustatic rising and falling of sea levels during Pleistocene time. Dredged reef limestone deposits from two deep-water harbor projects have provided additional resources. Limestone uses include cement and lime manufacturing, concrete sand and aggregate, mad base material, beach sand replenishment, agricultural lime and golf course construction.

Jan 1, 1982

By Paul Mitchell, Amy Wheaton, James Rybock

Acid rock drainage (ARD) represents one of the most intractable problems faced by the non-ferrous metal and coal mining sectors, and the creation in the recent past of a number of high-level national and international initiatives reflects the growing concerns of industry, government and other stakeholder groups. ARD is certainly considered one of the most serious environmental impacts caused by mining and the industry's greatest environment-related technical challenge. Additionally, the global depletion of non-acid generating oxide ore deposits and the increasing dominance of sulphide ores means that the potential for ARD incidents will continue to increase. Once initiated, the cycle of chemically and biologically mediated and catalysed reactions leading to ARD generation is difficult to stop. While there is evidence to suggest that the degree of contamination of ARD will decrease rapidly within a relatively short timeframe (Wood et al., 1999), experience in historic mining regions of the world indicates that the problem may persist for centuries at certain sites. Current best practice in dealing with ARD puts the emphasis on prediction and prevention, planned from the outset of the operation and integrated with each phase of the mine site life cycle. The elements that constitute best practice are becoming more clearly defined and as this process of clarification continues industry will undoubtedly accelerate the process of best practice implementation, burying at last the image of mining as a despoiler and polluter of landscapes, an image based on past, rather than current, practices. However, it is equally clear that despite the best efforts of industry and regulators, many sites will continue to generate ARD during operation and following closure - in many cases, a legacy of ARD has been derived from operational and strategic decisions made decades ago, before the risks and impacts of the self-sustaining cycle of ARD generation were properly understood. Add to this ARD generation from poorly managed operations and from historic and abandoned sites, and it becomes clear that the treatment of ARD will be required for the foreseeable future to protect water quality, and ecosystem and human health.

Jan 1, 1999

By Randall C. Divito, Craig R. Eckdahl, Bruce D. Wagener, Joseph Klejwa

The existing Central City Tunnel was built primarily in the 1930s with a small portion as old as the 1880s. It conveys stormwater in downtown Minneapolis. It is a 4,400-ft long tunnel located 80 feet underground. The Central City Tunnel has experienced surcharging and surface overflows during heavy rainfall events. This paper presents the details of tunnel and shaft design for the new Central City Parallel Tunnel to mitigate the overflows. The design considered hydraulics and geotechnical engineering for the structural geologic conditions including the weak Saint Peter Sandstone and overlying strong Platteville Limestone. Ground conditions resulted in tunnel designs including large flat-back box tunnels and unique cathedral-shaped tunnel sections.

Jun 13, 2023

By Gary L. Nelson

An overview is provided of Franklin Industrial Minerals mica mine and plant operations located near Velarde, New Mexico. Operated by Franklin Industrial Minerals since July of 1990, several process and product modifications have been developed and instituted to improve the operation. In addition to a brief history of site operations, descriptions of the mining, beneficiation, delamination grinding, and product classification processes are reviewed. Supportive topics discussed include equipment modifications and improvements, product application diversification, and specific product characterization. Also reviewed are the key areas of safety, environmental responsibility, and programs pertaining to process quality control and product quality assurance.

Jan 1, 1994

By Jonathan M. Pachter

The Bailey mining complex is located in Greene County, PA in the valley of Talley Run, a small stream tributary to the Enlow Fork of Wheeling Creek as shown on the location map insert found on Figure 1. The Bailey complex includes two Pittsburgh No. 8 Seam deep mines (Bailey and Bailey #2), a coal preparation plant, and two refuse areas (for disposal of coarse and fine processing waste). Clean coal is shipped from the complex via a 24.15 km (15 mile) rail spur, which connects to the Monongahela Railroad in Waynesburg, PA. In early 1981, Consolidation Coal Company (Consol) began a permitting effort aimed at beginning construction of Bailey, the largest underground coal mining complex to be built to date in the United States. Construction of the Bailey Mine began in December, 1981, less than six (6) months following the first application submittal. Clean coal was produced by the Bailey Preparation Plant in September, 1984. Effective project planning, including early formulation of a project planning team, identification of "red flag" issues, innovative responses to environmental questions and development of environmentally sound project designs, all contributed to the relatively quick permitting at Bailey.

Jan 1, 1985

By J. H. Desautels

The modern coal mining industry is subject to a vast array of regulations affecting virtually all aspects of its operations. Probably the most significant over-sight role involves the Office of Surface Mining Reclamation and Enforcement (OSH) established by the Surface Mining Control and Reclamation Act, or SHCRA.1 Although complying and coping with SHCRA can be difficult for coal operators, this complex regulatory process has helped insulate the industry from ongoing efforts to extend regulation under the Resource Conservation and Recovery Act, or RCRA, 2 to aspects of the mining industry in general. The Environ-mental Protection Agency (EPA) has struggled with regulation of mining wastes under RCRA since the mid-1970's, but RCRA itself places most coal mining wastes firmly under the control of OSH and SHCRA. Despite the general exemption from RCRA regulation for waste materials that result from extraction and processing of coal itself, there may be circumstances under which coal mining operators could find themselves subject to regulation under RCRA or a number of other statutes administered by EPA. This paper will review briefly the history of mine waste regulation under RCRA, as well as touch on the policy decisions that led to the exemptions from RCRA regulation. The paper will summarize coal waste requirements under SHCRA, and also will review what operations at coal mines need to be controlled, in order to avoid potential liability under RCRA. In addition, it will mention requirements under other federal laws, including CERCLA, or the "Superfund" law,3 and describe how they may impose restrictions or liability on coal operations for waste or other materials commonly found at surface and underground coal mines.

Jan 1, 1993

By Robert L. Sundeen, Richard V. Wenberg

INTRODUCTION Shotcrete can be defined as spray-applied concrete with a maximum size aggregate in excess of 9.5 mm (0.375 in.). The concept evolved from guniting, which uses smaller aggregate and generally produces concrete with poorer physical properties. The larger aggregate used in shotcrete requires less water in the mix, while offering larger bonding surfaces, thus imparting greater tensile and compressive strengths. TYPES OF MACHINES Two basic designs of shotcrete machines in general use are the wet or prehydrated zero slump and low slump type, and the dry or nozzle hydrated machines. Fig. 1 shows a typical zero-slump machine in a con¬figuration commonly used for small-volume require¬ments. The prehydrated zero-slump machine mixes exactly proportioned batches in a sealed pressurized chamber. "Slugs" of hydrated shotcrete mix and com¬pressed air are sent through a distribution hose to the nozzle where the wet mix emerges as a spray. The spray is directed onto the rock surface by the nozzle operator. The low-slump machine is similar, except that a thick slurry mix of aggregate is delivered throughout the distribution hose to the nozzle. Fig. 2 shows a typical low-slump shotcrete machine used in moderate-volume applications. The nozzle-hydrated shotcrete machine accepts a premixed "dry" (4 to 6% moisture) batch of aggregate and cement. A constant feed of this mix is directed by compressed air through the distribution hose to the nozzle. At the nozzle, water for hydration is introduced into the emerging spray. The hydrated mixture is di¬rected onto the rock surface by the nozzle operator. Fig. 3 shows a typical dry-mix machine. The major difference between the two basic machine designs is the consistency of the shotcrete quality. Pre¬hydrated machines have high degrees of consistency and produce high-strength concrete, resulting from their ability to produce exact mixtures of zero or low-slump concrete within the machine. Nozzle-hydrated machines tend to produce poorer quality concrete because of the difficulty in controlling the water content at the nozzle. Water input essentially is an art. As such it is not precise, and the shotcrete produced is of variable quality. MATERIALS HANDLING Materials handling presents a problem to either type of shotcrete machine. At times considerable quantities

Jan 1, 1982

Industry and regulatory agencies have requested guidance on safe blasting near transmission pipelines. The US Bureau of Mines (USBM) and Amax Coal Co. studied surface coal mine overburden blasting near four steel and one PVC pipeline of 15 to 51 cm-diam (6-20 in.-diam), monitoring vibration, strain and pressure. Unlike tests of small blasts simulating construction, these were up to 1 t (2200lbs) per delay in 31-cm (12-in.) blastholes. Worst-case comparisons showed that 12.7 cm/sec (5 in./s) blasting vibrations produced strains about one fourth that of pressurization and 10% to 18% of the ultimate tensile strength. No failures occurred from blasting as close as 15 m (50 ft), which produced vibrations over 60 cm/sec (24 in./s).

Jan 1, 1995

By Terry L. Logan, Arfon H. Jones, James C. Seccombe

Deeply buried coal seams [greater than 3000 ft (914 m)] are difficult and sometimes hazardous to test and complete due to coal sloughing, formation pressure anomalies and coal fine generation. Data collected while stimulating two deep coalbed methane wells located at the Gas Research Institute/Resource Enter¬prises, Inc. "Deep Coal Sean Project" test site in the Piceance Basin, Colorado, is presented in this paper. A single thick coal seam was completed openhole in each well. Core data, reservoir data, in-situ stress measurements, and pre-stimulation calibration test data were collected at the site to use in the design of the fracture stimulation treatments for both wells. A nitrogen foam fracture fluid treatment was selected for the first well and a linear gelled water for the second well. Treatment pressures were monitored with a downhole quartz pressure transducer. Atypically high treating pressures were observed, possibly indicating coal fines plugging at the fracture tip or increase in fluid viscosity caused by interaction of the generated coal fines with the fracturefl uid. In addition, a comprehensive fracture diagnostic effort was employed during the fracturing of the second well; namely, triaxial borehole seismic, seismic televiewer, hydraulic impedance monitoring, gamma ray log (in conjunction with radioactive additives in the sand), and temperature log. The results indicate a vertical fracture was created parallel to the face cleat as expected.

Jan 1, 1986

By E. H. Cho, Q. Luo

Pittsburgh No. 8 coal, cleaned by conventional froth flotation, was oxidized in a 2-L Parr stirred bench-top autoclave. Autoclave tests were carried out for up to 5 hrs under the following conditions: 150 to 225ºC, 60 to 500 psi 02 and 15 to 60 g of coal per 600 mL of distilled water. The oxidation of coal was evaluated by measuring the total acidic group formed on the surface of the coal and by measuring the adsorption (under standard conditions) of calcium ion from a solution. The degree of oxidation of the coal increased continuously, without much leveling off, with increasing oxygen pressure. With increasing temperature, the oxidation of the coal increased sharply between 150 to 175ºC and then leveled off above 175 °C. The adsorption of calcium was >3% on coal oxidized under the most favorable conditions. The adsorption of calcium on coal increased sharply with increasing equilibrium pH. The loss in Btu was found to be sensitive to oxidation temperature. This study concluded that the optimum oxidation of coal is achieved over 3 hrs at high oxygen pressures (e.g., 500 psi) at ~170ºC. This study also concluded that, when measured in terms of calcium adsorption, Btu loss and reaction time, the oxidation achieved in an autoclave is far superior to that achieved in a fluidized bed.

Jan 1, 1996

By K. Huttu, A. van Wageningen

"The Kittilä underground mine in northern Finland is extracting one of the largest known gold deposits in Europe. Kittilä achieved commercial production on May 1, 2009, becoming Agnico Eagle’s first mine to open outside of Canada. The Kittilä orebodies were initially mined from two openpits – Suuri and Roura – and underground operations were added in October 2010. The pits were mined out in November 2012, so mining is now entirely underground in the Suuri and Roura deposits. Additional, small openpits will mine any remaining near-surface reserves in the future.The Kittilä Mine is located in the Lapland region of northern Finland, approximately 900 km (560 miles) north of Helsinki and 150 km (93 miles) north of the Arctic Circle. With a mine life estimated through 2034, Kittilä is Agnico’s longest-life mine.The mine’s proven and probable reserves contain 32 Mt (4.7 million oz) at 4.6 g/t (0.13 oz/ st) gold. Ore has been mined from underground since 2010. The original 3 kt/d (3,300 stpd) operation underwent an expansion project to increase the throughput capacity of the mill by 1 kt/d (1,100 stpd), starting by the end of 2014.The region around the Kittilä Mine is underlain by mafic volcanic and sedimentary rocks of the Kittilä Greenstone Belt oriented nearly vertical. This greenstone belt is similar to those hosting Agnico Eagle’s Canadian deposits in Quebec’s Abitibi region and Nunavut. At the contact point between ironrich and magnesium-rich rocks lies a 100- to 200- m (330- to 660-ft) thick structural zone known as the Suurikuusikko Trend. This trend hosts the Kittilä deposit, where multiple mineralized zones have been traced over a strike length of more than 25 km (15 miles).Most of Agnico Eagle’s work has focused on a 4.5-km (2-mile) segment of the Suurikuusikko Trend that hosts the five main zones of the known gold reserves and resources. From south to north they are: Ketola, Etela, Suuri, Roura and Rimpi.The ore at the Kittilä Mine is refractory, making gold extraction relatively difficult because the gold is generally locked inside the two main sulfide minerals – arsenopyrite and arsenic-rich pyrite. Only about 4 percent is very fine-grained “free gold” (not locked in sulfide grains) and easier to extract. Most of this free gold is found in the outer, oxidized or eroded sections of the ore."

Jan 1, 2015