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By Roger Malmström, H. Heden, Kjell Lidin

INTRODUCTION LKAB was formed at the turn of the century when the railways between the ore fields and harbors were built. The mines are situated north of the Arctic Circle in Sweden. Kiirunavaara is the largest mine, with a pro¬duction capacity of approximately 30 Mt/a. Malm¬berget has a capacity of about 12 Mt/ a. Both are under¬ground mines. Svappavaara, the only opencast mine currently in operation, has a capacity of about 4.5 Mt/a. The ore harbors are at Narvik for the Kiruna and Svappavaara mines and at Lulea for the Malmberget mine (see Fig. 1). Production in the form of finished products is shown in Fig. 2a, b, c, and d. Due to poor ore markets in re¬cent years, production and shipments have been cut back, but there was a positive swing in 1978. LKAB has been 96% state-owned since 1957. In addition to the iron mines in northern Sweden, LKAB has subsidiaries in central Sweden which produce sulfide ores, quartz sand, and uranium (Fig. 3). The mining methods employed are opencast bench stoping at Svappavaara and sublevel caving at Kiirunavaara and Malmberget. GEOLOGY The Kiirunavaara ore body is 4000 m long and av¬erages about 90 m wide, with variations in width from a few meters to around 150 m. The ore has been ex¬plored by deep drilling down to about 1000 m, but mag¬netic measurements indicate a depth of at least 1500 m. The Kiirunavaara ore is oriented in a north-northeasterly direction with a number of ores in the boundaries be¬tween the wall rock types. The ore in Kiirunavaara is mainly a fine-grained magnetite with a varying content of fine-grained apatite. The apatite content of the ore decreases with increasing depth. The other ores are all apatite-bearing and a couple are hematite ores (Fig. 4a, b). The ores are sedimentary, tilted, and tectonically de¬formed. They have a lateral dip of 0.87 to 1.2 rad (50 to 70°). The contacts between ore and wall rock are distinct and sharp, but both the hanging wall and the footwall are brecciated and impregnated with magnetite. The footwall of the Kiirunavaara ore consists of syenite porphyry with a low quartz content and rela¬tively good strength; the hanging wall consists of quartz porphyry. Both types are known as Kiruna porphyries. The ore at the boundary with the hanging wall is often rich in kaolin. There are a few veins of syenite porphyry running through the ore, which has a few major faults (Fig. 4c, d). There are two sharply delineated ore grades in Kiirunavaara: low phosphorus ore with less than 0.1 % phosphorus (about one-third of the ore) and high phos¬phorus ore with greater than 0.5% phosphorus. The iron content is 67% in the low phosphorus ore and 60% in the high phosphorus ore. These ore types are sold as different grades and so are kept separate during mining. MINING AT KIIRUNAVAARA The Kiirunavaara and Luossavaara ores were first mined using opencast bench stoping in 1902. When mining costs rose owing to higher waste removal, under¬ground methods were adopted. In the mid-1950s, the ores were still being mined on the surface at the same

Jan 1, 1982

By Ben Sosewitz

The subject of rapid excavation tunneling is one that is extremely important to the people in the Metropolitan area of Chicago. My personal observation is that it is also extremely important to the urban communities around the U.S., to many local and state governments, and to the public officials who are deeply concerned about state affairs and taxes. The Metropolitan Chicago area is in fact, (as are 40 other major urban areas in the U.S.) confronted at the present time with a very serious combined sewer overflow, drainage and pollution problem which accounts for an estimated 40% of the pollutional load on its waterway system. In response to this the District has to date spent some seven millions of dollars in an attempt to find the most economical solution available for the elimination of this problem. This study included extensive investigations of the geological strata, the quantity and quality of storm runoff to be dealt with, and the various methods of storage and treatment available. It has considered solving the overflow problem by a concept involving a series of tunnels, rock tunnels, shafts and storage areas which will collect, retain and subsequently treat that portion of the combined sewer overflow which can be handled in the most cost-effective and economical way, consistent with following the federal and state standards - with which we at the present time agree in principle.

Jan 1, 1997

By F. Habashi

The Republic of South Africa is a heterogeneous mixture of Black Africans, Afrikaans, British, Indians, Malayans, French Huguenots, and many others from Europe and Asia. A decisive date in its recent history is the collapse of the Apartheid Regime in 1994. For a metallurgist, South Africa is the country of diamonds, gold, platinum, and many other metals. In 1887 Cecil Rhodes (1853-1902) was able to take control of the De Beers Mining Company after the discovery of diamonds at Kimberly in 1866. It was there where the so-called School of Mines was inaugurated in 1896.

Jan 1, 2010

By Stanley Noss

One need be neither an historian nor technologist to recognize that activi¬ties related to the conversion of coal to other usable energy forms have been active for nearly fifty years. The degree of such activity and its evolution to significant commercial proportions has, however, fluctuated widely with world circumstance. For the past decade there has existed both a consistent technology evolution effort in classic R & D proportions, and a mainstream commercial acti¬vity but in rather modest proportions when viewed from the vantage point of world energy needs. But the chain of events wherein it became increasingly obvious that we were in energy trouble irrespective of world politics, spurred alternative energy source activities in the fossil fuels areas. The oil embargo of 1973-1974 made the obvious even more so and provided additional emphasis for the need of such alternatives. Yet the preponderance of these added expenditures and activities (with one notable exception which is the subject of this discussion) has been focused on the intended identification of the best or ultimate process by means of analytical and modest empirical means, whereas our circumstance dictates a bold, higher-risk effort to prove the viability of coal conversion as an industry on a real-time, real-size, real-economics basis. With such proof on hand, industry demands in all related areas will provide the stimulus, motivation and environment for all processes. There is both need and room for many who will compete for a meaningful segment of this new industry which can grow at a rate never seen before in our growth history. The single program in the world today oriented specifically toward the goal of proof of industry viability is the Energy Research and Development Administration's CBF (clean boiler fuels) Program for which COALCON is proud to be the prime contractor.

Jan 1, 1976

By G. E. S. Valadao, J. D. Miller, C. L. Lin

Filtration is an important solid liquid separation technology employed widely in the mineral processing industries. The effectiveness of the filtration operation can be influenced by numerous variables, related to the particulate phase, the slurry rheology and the equipment. The classical approach for analysis is based on Darcy's law. Knowledge of the cake poremicro structure and its correlation to macroscopic cake properties is required to model the filtration operation from a fundamental point of view. Since cake formation seems to occur randomly, a 3D Monte Carlo method was used to simulate cake formation. The configuration for simulation was a space with width of 500 m, length of 500 m and height of 4000 m. Size distributions of five different industrial products whose particle size distributions follow the Rosin Rammler distribution function were used. The particle shape was assumed to be spherical. The simulated cake structures were described in terms of volume porosity (volume of pore space per unit volume of cake) and surface porosity (area of pore space per unit area of a cross section). The results indicate: 1) it is possible to simulate 3D packing, which mimics cake structure, using the Monte Carlo method,2) segregation phenomena occurs during simulated cake formation, 3) the values of calculated porosity for simulated samples B, C, D, and E were lower than those determined for corresponding industrial products Br, Cr, Dr, and Er, and 4)some structures of simulated samples seem to correlate with laboratory leaf test data obtained for different products from plant operations.

Jan 1, 1999

By Albert Ruiz

The 2,250-MW, coal-fired Navajo Generating Station located in Page, AZ draws water from Lake Powell using submersible pumps installed in five inclined shafts. Drought threatens to lower the reservoir to below the existing intakes. A system of new steel-lined intake shafts located on the same site was required for uninterrupted plant operation. The small size of the site, and the need to keep the existing system in operation, required detailed designs and placed significant limitations on construction equipment and activities. The Navajo Sandstone that forms the near vertical shoreline of the reservoir is 98 percent very fine grained quartz, highly abrasive and contains highly fractured intervals that presented numerous challenges to drilling the new 152-m (500-ft) deep, 109-cm (43-in.) diameter intake shafts inclined 23° to 26° from vertical. Spatial constraints, submersible pump design and operational criteria required that each shaft have a unique inclination and orientation and hit a small breakout target located 76 m (250 ft) under water. Sophisticated drilling equipment and techniques as well as state of the practice downhole survey technology and methods were used to make adjustments and maintain drilling accuracy with less than 1 percent deviation. Environmental requirements mandated water as the drilling fluid and grout was not allowed in to the lake under any circumstances. The shafts were videotaped and the breakout locations were examined using an underwater remotely operated vehicle (ROV) to verify shaft locations and rock conditions, and to guide placement of pneumatic packers to ensure grout did not transmit to the lake during the steel liner installation. In anticipation of the invasion of quagga mussels, the shaft design included an allowance for a chemical dosing system and a copper-rich alloy at the exposed portions of the steel liner.

Jan 1, 2011

By Hendrick A. D. Kirsten, A. Clayr Alexander

Stillwater Mining Company is currently developing a second underground palladium and platinum mine approximately 21 km (13 miles) west of their existing Nye operation in the Bear tooth Mountains of southern Montana. Portals for the two access tunnels required at the new site were excavated in limestone talus to accommodate4.6 m (15 feet) diameter tunnel boring machines. A review of the technical design, field conditions and construction of the portals is presented.

Jan 1, 2001

By A. Korchevskiy

While Russia continues to be a worldwide leader in asbestos production, the environmental and health status around Russian asbestos mines is not well known and understood, internationally. A literature review was performed to evaluate the potential impact of Russian mining operations on mesothelioma incidence rates in the Ural region where the majority of the asbestos deposits are located. Asbestos that has been mined in this region includes chrysotile, crocidolite, and anthophyllite forms. The Nicholson-Peto (1986) model was applied to published exposure data and mesothelioma mortality statistics in different cities and villages of the Ural region to estimate mesothelioma potency factors (KM) for the various associated fiber types. It was demonstrated that mesothelioma potency factors, as determined by Berman and Crump (2008), could be used to predict mesothelioma risks of non-occupationally exposed individuals in locations where either pure chrysotile, or both crocidolite and chrysotile, are mined and milled. A mesothelioma potency factor was calculated for anthophyllite that appeared to be higher than expected based on previously published studies. The highest incidence of mesothelioma was identified in a community close to a crocidolite mine. The study confirms the validity of utilizing current risk models for non-occupationally exposed populations near asbestos mining activities where asbestos exposures are relatively low and provides methods of characterizing mesothelioma risk in the former Soviet republics (FSRs).

Feb 27, 2013

By David L. Veith

As the basis for the State of Minnesota's Regional Copper-Nickel Study environmental evaluation, hypothetical mine models were developed ranging in ore capacity from 5.35 to 20.00 x 106 mtpy. Open pit and underground mining operations were defined utilizing conventional methods of ore extraction. Processing of the copper-nickel sulfide material involved conventional bulk flotation of the valuable minerals, with maximum water recycle And tailing disposal. Flash smelting and electrolytic refining of the concentrate resulted in 0.10 x 106 mtpy copper plus nickel metal, plus associated cobalt and precious metals. Variations in model parameters allowed environmental trade-offs to be identified.

Jan 1, 1980

By Derek J. Penrice

The Caltrain Downtown Extension (DTX) project will extend commuter and future statewide high-speed rail service into the Transbay Transit Center, which will be located in the business district in downtown San Francisco. The DTX project includes 1.5 miles of underground construction, comprising complex sections of mined and cut-and-cover tunnel. As part of the DTX preliminary engineering process, development of appropriate contracting practices, including contract packaging, procurement methods and contract terms for the underground construction, has been initiated. This paper provides a summary of the evaluations undertaken, preliminary conclusions reached, and proposed next steps to promote industry interest and maximize bid competition.

By R. K. Jade

Although several studies in combining and bifurcating flows in two-way junctions and splits are reported, deviations persist in the estimated shock loss coefficients (SLCs). Due to their complex nature, more work has to be done to be able to correctly predict flow losses at these locations. In two-way splits, the flow at bifurcation is known to be characterized mainly by two recirculating zones in the downstream branches, whereas, in a junction one recirculating zone is observed immediately downstream of the main branch. The relative flow rate in the branches (quantity ratios) is treated as the only parameter defining the losses at these locations. However, the effect of wall roughness, if any, on SLCs becomes important for mine ventilation. This paper presents the critical determinants of shock losses at splits and junctions at varying quantity ratios. The flow at 90º split and junction was examined both experimentally and numerically for Reynolds number in the range of 1.0×104 to 1.6×105. With a well designed laboratory setup, using precision instruments, velocity and pressure measurements were carried out, by using two scales of wall roughness. 3D numerical simulations for these experiments were conducted by using ANSYS CFX modeling tool. CFD simulations yielded results that are reasonably close to experiments, providing high degree of satisfaction in numerically predicting losses across the splits and junctions. However, comparisons of these numerical simulation results with existing literature standards showed significant under-estimation of shock losses by the standard literature by as much as 50%. A clear rise in the magnitude of shock losses was noted in both the approaches, with increased wall roughness. Based on the current studies, predictor equations incorporating quantity ratios are developed for accurate estimation of shock losses. Further investigations on roughness are needed, before one is able to incorporate wall roughness into the prediction of SLC.

Jan 1, 2009

By T. Hudaverdi

Several studies have been conducted on blastability and prediction of fragmentation. The term blastability is used to refer the susceptibility of the rock to blasting and is closely related to fragmentation. Parameters that determine fragmentation by blasting may be divided into two groups. The first group consists of blasting design parameters. The blast design parameters are controllable parameters and determined by the explosive engineers. The burden, spacing between holes, bench height, drillhole diameter, stemming height and explosive density are all design parameters. The second group consists of rock mass parameters that are referred to as uncontrollable parameters. The uncontrollable parameters are physical and mechanical properties of rock and rock mass structure. The strength, modulus of elasticity, density of rock, number of joint sets, joint orientation and joint spacing are among uncontrollable parameters. The rock mass parameters and blast design parameters should be considered together to explain fragmentation process. In this study, a blast database was accumulated to use for multivariate analysis. The blast database contains the blasts performed near Istanbul region quarries and the blasts that were preformed in various mines in the world by the blasting researchers. The cluster analysis was used to separate the blast data into different similarity groups. Group memberships were analyzed and checked by the discriminant analysis. Then, the multivariate regression analysis was used to develop a prediction equation for blast fragmentation for each group. Finally, a validation of the suggested models was performed for various mines. The model comprises blast design parameters, mechanical properties of rock and rock mass structure.

Jan 1, 2011

By N. Chow

The recovery of manganese from lower grade resources has been studied for a number of years. Of key importance of prior work, was the discovery that higher valent manganese resource can be readily leached with sulfurous acid. This eliminates the need for high temperature reduction roasting that is conventionally used in processing high grade material. High temperature roasting is energy intensive, emits a large amount of carbon dioxide, and would not be economical for processing lower grade material. While the prior work provides important information to extract manganese from lower grade resources, the production of unwanted by-products, and high water and energy usage has limited its commercial use. This paper describes the results from laboratory work that demonstrate solutions to problems, which to this point preclude commercial development. Preliminary mass and energy balances show that a significant opportunity exists in producing manganese with this hydrometallurgical scheme in a low cost, environmentally friendly manner. Emphasis of the work is on low water use, low overall energy use and economic destruction of unwanted by-products.

Jan 1, 2011

By M. J. Hrebar

A study was conducted to evaluate the applicability of large wheel loaders (Cat 994 class) as primary loading equipment in open pit iron ore operations. Field visits were made to taconite and gold mines that used large wheel loaders. Data were gathered on loader selection rationale; operating and maintenance experience; and production, availability, and cost information. Brief time studies were conducted to indicate machine performance and utilization. The paper summarizes the field data and includes economic comparisons of wheel loaders versus cable shovels in an iron ore application.

Jan 1, 1996

By M. J. Gilbey

Cross passageways between adjacent tunnels in passenger rail or transit systems may be used during train fire emergencies to evacuate passengers to points of safety in the non-incident tunnel. Rescue trains can be brought into the non-incident tunnel to remove passengers to expedite evacuation times as compared to walking along bench walls to the nearest egress stairs. In cases of multiple train emergencies, the required ventilation capacities can result in high pressure differences between the incident and non-incident tunnels. These pressure differences can make it difficult or impossible for a normal person to open doors of a cross passageway between adjacent tunnels. If opened, the velocity of the airflow through an open cross passageway can reach levels high enough to impede passenger evacuation. This paper describes the analysis of this problem for a sample rail tunnel. A ventilation concept that mitigates the problems of high cross passageway door opening forces and high velocities through open cross passageways is presented.

Jan 1, 2009

By Susan P. Taite, Alain R. Charest, Peter D. Lewis

The El Sauzal deposit is a classic, high sulfidation, epithermal gold system located in the southwestern Chihuahua state of Mexico (Fig. 1). A Francisco Gold geologist discovered the prospect in1995. El Sauzal was encountered as a result of an extensive grassroots exploration program in the rugged, dissected volcanic terrains of the Sierra Madre Occidental, around the historical Batopilas silver camp. At El Sauzal, high grade gold is hosted within a series of more permeable, low-dipping, lithic and fine-grained dacitic rocks of early Tertiaryage. The mineralization appears tobe structurally and lithologically controlled. The alteration characteristics are typical of a high sulfidation system, including kaolinite, illite, alunite, dickite and pyrophyllite.

Jan 1, 2005

Market confidence is on the rise and industry leaders turning toward the vast and diverse region of Latin America are faced with abundant, yet daunting, opportunity. From the iron orebodies of Brazil to the renowned copper mines of northern Chile, drilling teams in Latin America are often faced with abrasive, broken ground. These types of ground conditions tear up coring bits rapidly, making it extremely difficult for even the most seasoned drilling teams to maintain effective productivity. The drilling challenges faced in this rich and opportune region are being met today by advanced coring technology, bringing with it the potential for increased productivity in Latin American mineral exploration.

Jan 3, 2010

Introduction Aggregate mining impacts on water resources are a source of concern to local governments. To evaluate those impacts, the Minnesota Department of Natural Resources conducted a four-year study at three gravel pits (two alluvial and one beach-ridge) and five quarries (flat-lying Paleozoic limestone). This research provides the first comprehensive look at aggregate mining impacts on ground-water systems in Minnesota. The results will be used by government officials making permitting decisions about aggregate operations and by responsible owners of aggregate mines as they plan their operations to avoid conflicts with neighbors and with resources dependent on ground water and surface water. Natural aggregate (crushed stone, sand, and gravel) is a vital part of our economic infrastructure in Minnesota. Aggregate is used for road and bridge construction and in a variety of building materials. In 2003, the value of construction sand and gravel and crushed stone in Minnesota was approximately $245,000,000. As Minnesota’s economy continues to expand, the demand for aggregate will continue to grow. Sand and gravel pits are located in every county in Minnesota. In 1990, the Minnesota Department of Natural Resources, Division of Minerals (DNR Minerals), estimated the number of active and inactive operations at 1500 with the view that this number was likely too low. Quarries for mining limestone, dolomite, sandstone, and hard rock (granite and quartzite) are found in 34 counties. A 1990 DNR Minerals inventory found 165 active operations, 88 percent of which were limestone quarries (Nelson and others, 1990). That same inventory counted 1,367 inactive operations, 70 percent of which were limestone quarries. Aggregate mining is an extractive use of resources: mining alters the landscape and its natural hydrologic system. When a new pit or quarry is proposed or when an existing operation needs to expand, local governments and citizens typically have many questions about the impacts mining might have. Local governments, which are responsible for reviewing these operations, rarely have the budgets to hire experts to evaluate potential impacts of quarry and gravel pit proposals. The Minnesota Legislature’s Aggregate Resources Task Force identified that local government units (LGUs) often lack the expertise to assess ground-water models (Southwick and others, 2000).

Jan 1, 2007

By S. Underwood

The tracer gas method of conducting ventilation surveys is a means of determining air quantity in underground mines with knowledge of the concentration of the tracer in the atmosphere and the flow rate at which the tracer is being released. The technique is useful in inaccessible areas of underground mines and areas where traditional point measurement of velocity is not practical. Sulfur hexafluoride (SF6) is the industry standard tracer(Kennedy 1987) used in underground mines because it is safe, stable, and not naturally occurring in the mine environment. The implementation of a second tracer will increase the versatility of the tracer gas technique allowing for simultaneous releases for the study of interrelated ventilation circuits, and for conducting multiple experiments in less time. This paper will detail the selection of perfluoromethylcyclohexane (PMCH) as a novel tracer with sensitivity, physical properties, and analysis characteristics similar to SF6. Methods for the release of liquid PMCH into underground mines will be recommended, and the vulnerabilities of sample loss due to condensation of vapor PMCH will be explored. Finally, the benefits and implications of using PMCH as a second tracer will be discussed.

Jan 1, 2012

Basic parameters affecting the stability of foams have been studied. We used the thin film pressure balance (TFPB) technique of Scheludko and Exerowa (1959) to measure the surface forces in foam films stabilized with various frothers such as pentanol, octanol, MIBC, and PPG. The results were compared with the froth stabilities measured using the shake tests and the film elasticity calculated using the model developed by Wang and Yoon (2006). It was found that the froth stability is controlled by both film elasticity and surface forces (or disjoining pressure), the relative contributions from each changing with frother concentration and type.

Jan 1, 2006