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By K. J. Stanaway

Concentrations of minerals between 3.5 and 5 specific gravity such as ilmenite, rutile and zircon in large accumulations of sand constitute "heavy mineral" placers. Two fundamentally different modes of formation characterize "trap" and "bed" placer variants. Smaller and generally higher grade trap placers form during sediment erosion or reworking. Because of their smaller size, they rarely yield economic heavy mineral deposits. They become economic, either if they contain more valuable "heavies" such as gold, or, if they occur within or near much larger but lower grade bed placers. Bed placers form during sediment accumulation episodes in any environment and lithofacies where mineral supply and fluid dynamics are favorable. Three heavy mineral deposits are discussed to illustrate bed placer geology and how trap placers occur with and relate to them.

Jan 1, 1991

By Sidney A. Suhler

The persistent requirement for methods and equipment capable of detecting hazardous anomalies in advance of underground mining has led to the development by the U.S. Bureau of Mines of a directional radar probe. The probe operates from boreholes drilled from the surface into the underground region to be mined. The engineering model radar was completed in early 1982 and field demonstration tests were performed in May of that year at a selected coal mine. Preliminary in-situ electromagnetic tests were performed at several candidate coal mines to evaluate the radio-frequency characteristics of the coal. A coal mine in New Mexico was selected on the basis of low EM propagation losses in the coal and the presence of an extensive coal seam displacing fault as a radar target. The borehole radar was operated in two vertical boreholes which intersected the coal seam at approximately 25 and 40 feet from the fault interface. Radar reflections from the coal/ rock interface were detected in both tests. Underground tests in a horizontal borehole in the coal were less successful because of interfering reflections. Additional borehole-to-borehole tests were performed with a separate ground penetrating electromagnetic system to obtain radar range calibration data. The coal was found to be bounded by very lossy roof and floor sandstone and shale while propagation through the coal seam was obtained at distances up to 175 feet between test boreholes. Coal seam continuity was indicated by the hole-to-hole experiments through a section of the seam previously thought to be completely cut off by the fault.

Jan 1, 1983

By L. Schlink

Impacted waters, often complex, are created in mining which at some point in the mine life cycle will need to be attended. The simplest and most cost effective method of handling impacted water is to reuse it as makeup water for operations. At the end of mine life, operational reuse will not be an option and the impacted water will require treatment to achieve alternative reuse goals. Conventional mine impacted water treatment is successful in removing unwanted constituents but create brine and sludge that may require special handling or additional treatment, resulting in additional liabilities and costs. Freeport-McMoRan Copper & Gold has taken an approach to water treatment that focuses on transformation not concentration. The Water Treatment Test Facility located at Sierrita Mine has three test plants that are piloting the mine impacted water transformation process. Two plants have been designed for the removal of calcium and sulfate with products of gypsum and sulfur. The third plant removes metals from process water and transforms them into marketable metal sulfides. The transformation, rather than concentration, of mine impacted water solutes greatly reduce long term risks.

Feb 23, 2014

By Todd Burchett

Mining engineers spend countless hours and resources when designing a new underground coal mine. Their primary objective is to design the safest and most efficient operating mine with regards to coal production. A key variable often overlooked in this design stage is the slope conveyor. Typically, a slope conveyor is expected to operate with a 98-percent or higher availability. However, too often little effort is put forth by the mining engineer to optimize its design. Coal companies will rely on engineering, procurement, construction and management (EPCM) companies for the preliminary design, because the slope conveyor will be considered part of the surface material handling processes. This preliminary design will be used when soliciting quotations for the slope conveyor. Unfortunately, EPCMs may not have enough expertise with conveyors to optimize the design. This expertise is available with an original equipment manufacture (OEM) of conveyors, which ultimately may be responsible for supplying the slope conveyor. Each OEM will provide a bid package that represents what it considers to be the optimal design.

Jan 1, 2013

By G. Folmo

Allis Mineral Systems' GRATE-CAR agglomeration/induration/reduction process is currently being operated to process ilmenite at Tinfos Titan & Iron KS in Tyssedal, Norway. In this process, balled ilmenite concentrate is fed to a traveling grate where pellets are dried and preheated, using fully oxidized kiln exhaust gas. Hot preheated, semi-indurated pellets are fed directly to a ported kiln where reduction of the ilmenite's iron oxide fraction occurs in the presence of lump coal. The reduced pellet sand coal char are discharged from the kiln to an indirect rotary drum cooler. Cooled pellets and char are screened and magnetically separated prior to their further processing in a downstream smelting operation. The pellets are melted and the titanium dioxide and iron are separated. Operation commenced in late 1986.

Jan 1, 1992

By E. Stemn

Incident investigation is of utmost importance in most high-risk industries. This study was undertaken to study the content of past investigation reports to determine the effectiveness of the incident investigations. The study uses a semi-quantitative method to assess the effectiveness of incident investigations in the Ghanaian mining industry by evaluating the quality of past investigation reports. The assessment tool consists of 5 elements with several indicators and rating scales for assessing the quality of an investigation report as a measure of the effectiveness of the investigation. The method was applied to 304 investigation reports of 3 Ghanaian large-scale gold mines, and the results correlated with incidence rates of the mines to determine if any relationship existed. The results showed that the mines differ significantly in the quality of their investigation reports, suggesting differences in the effectiveness of their investigations. In addition, the incidence rates of the mines negatively correlated with some elements of the assessment tool. In general, the method was found useful and revealed areas where improvement is needed. INTRODUCTION The importance of learning from incidents is well documented in the literature. For instance, some scholars regard learning from incidents as important for improving safety [1,2]. Thus, many organisations spend considerable resources in identifying lessons from incidents and subsequently on the process of improvement that follows the identification of lessons. It is therefore important for such organisations to determine the effectiveness of their learning from incidents processes, in order to identify specific areas where improvements are needed, so that interventions can be as specific as possible. The learning from incidents process models the plan-act-check-do approach of management systems, often consisting of four major stages, namely; data collection and incident analysis, planning interventions, implementing interventions and follow-ups and evaluation [3,2]. The investigating and analysis of incidents have been regarded as one of the vital stages of the learning process since it is the stage where lessons are identified [3,2,4]. It has also been noted elsewhere in the literature that results of the previous stage of the learning process are important for the next stage [3]. For example, ineffective incident analyses could result in the planning of ineffective remedial measures. One of the primary aims of incident investigations is to identify lessons from previous incidents which when implemented can prevent future recurrences or minimise the effects of future incidents. There is thus the need for organisations to assess the quality of their investigations periodically since it is one of the means they adopt to improve safety and the quality of remedial measures to some extent depends on the effectiveness of the investigations. Although previous studies [5,2] have assessed the effectiveness of the learning process, and some aspects of the learning process, such as incidents reporting, there is less focus on the effectiveness of incident investigations. The research described in this paper was therefore conducted to contribute to this gap, focusing more closely on incident investigation reports.

Jan 1, 2019

By R. Shields

"Hard rock mines move large volumes of material, which can cause the conveyors that are essential to this movement to suffer lots of problems, including carryback, spillage, dust and belt wander. Many of these issues are created at the transfer points where the belts are loaded.This article provides an overview of the latest transfer point systems that incorporate safety and serviceability by design as well as a report on recent projects. One project is the Conveyor B Transfer at the Coeur Rochester silver mine near Lovelock, NV. Here, performance was improved with the installation of belt support cradles, engineered chute walls with external wear liner, and a compact dust collector. A second project is the improvement of belt support idlers and skirtboard sealing in a long loading zone of a conveyor under the concentrator at an Arizona copper mine.The importance of transfer pointsConveyors are essential in mine material handling. Their performance will often make the difference in mine productivity and profitability. A key to conveyor performance is the transfer points where the conveyor belt is loaded and discharges. At these transfer points, many of the problems encountered with the conveyor system are created.The problems that arise at the transfer stations include off-center and segregated loading, mistracking, blockages and plugging. And there are a variety of problems originating with fugitive material — cargo released in the form of carryback, spillage or airborne dust — that are created or exacerbated in the transfer points. These fugitive materials turn into other conveyor-related problems, including shortened component life, unplanned outages for conveyor maintenance, unexpectedly high labor costs for maintenance and cleanup, worker health and safety problems and issues with community relations. The U.S. Mine Safety and Health Administration estimates that 85 percent of conveyor maintenance is a result of fugitive material at conveyor transfer points.Technologies to improve transfer pointsA number of techniques to improve the performance of conveyor transfer points have been developed. They include:"

Jan 11, 2017

By Q. Xu

The adsorption behavior of gold in ammoniacal solutions on to activated carbon has been studied. The gold loading capacity of the activated carbon used in the system and the recovery efficiency by the adsorption were examined. The parameters affecting the adsorption of gold on to activated carbon included temperature, agitation speed, concentration of 'cation and anion as well as that of ammonia. It was found that the maximum gold loading on activated carbon used was about 10 kg of gold per ton of carbon. The recovery of gold by the adsorption from ammoniacal solutions was dependent upon the initial gold concentration in the solution. A recovery of 98% of gold was obtained on to the activated carbon under experimental conditions after 120 hour adsorption. It was also found that the initial adsorption rate was relatively fast compared to the whole period of the adsorption. The apparent activation energy for the adsorption was measured to be 15.8 kJ/mol. It was believed that the kinetics of gold adsorption on activated carbon was controlled by pore diffusion.

Jan 1, 1995

By Sharanappa Yalal, Rakesh Kumar Khali

"Himalayan geology poses the most challenging ground conditions almost anywhere in the world, one of the reasons thereof is their evolution as the youngest mountain chains. They are demonstratively rising faster than any mountain elsewhere. The composition is also younger, and consequently less well consolidated than the other older fold belts. This is consistent with the fact that they constitute one of the most active of the plate margin zones rising at a rate that is almost double the Andes, which is in turn three times that of the Alps. Thus, stress conditions (Magnitude and variations) can potentially be more extreme and adverse on a Himalayan tunneling project. Tunnel excavation under the Himalayan Mountains will pose significantly more challenges than an equal length and equal cover drive almost anywhere in the world. These in-depth-tunneling difficulties through high mountainous terrains have posed major challenges for application of traditional drill and blast (D&B) and NATM methods. Handling such adverse geology at any depth is always problematic and generally leads, if not adequately foreseen, to the significant tunneling delays. The author wants to highlight the challenges faced and on the spot solutions adopted while executing most prestigious 273Km long Udhampur –Srinagar- Baramula Rail Link Project (USBRL) in the Himalayas in the state of Jammu & Kashmir, India. The main focus of the paper is on main stretch of USBRL Project i.e. T-80 (India’s 2nd longest railway tunnel & 3rd longest in Asia) where the team of the author has recently completed a 11.2 Km long tunnel and where the train track has gone operational from Qazigund to Banihal. The construction of this stretch posed several challenges akin to highly adverse geological conditions. Executing on -the -spot solutions, the project has been completed successfully. 1.0 INTRODUCTION Construction of Udhampur-Srinagar-Baramulla Broad gauge railway line is one of the Mega projects undertaken by Indian Railways to establish a dependable transportation in the state of Jammu and Kashmir. In engineering terminology, it is a challenging project negotiating breakthroughs against the complex Himalayan geology. The Project which has been operational over last 12 years , stretch by stretch, is in advance stage of construction . The purpose of the prestigious project is to connect the Kashmir valley to the mainland of the state of the country. On the date owing to the hurdles of the tuff terrain, the transport of this part is totally dependent on the surface transport, i.e., through a road which connects NH-1A from Delhi to Srinagar. The altitude of the region varies from 500.00 to 1700.00, ranging through Udhampur to Katra - Reasi –Sangaldan- Banihal-Quazikund-Ananthnag-Srinagar-and Baramulla. The main features of this project are its Pirpanjal Tunnel and T-48 & 49 tunnels which cover the maximum length of tunneling through thick hostile geological conditions, the total length being 138km. Details of Pirpanjal tunnels are shown in Figure-1."

Jan 1, 2016

By Phil Rice, Mohammed Nasim, Richard Flanagan

"The Gateway Trans-Hudson Partnership (GTHP), a joint venture of WSP USA, Inc., AECOM USA, Inc, and STV Incorporated, is providing preliminary engineering services to Amtrak for the Hudson Tunnel project as well as supporting the NEPA process for getting the record of decision (ROD). This preliminary engineering design effort by GTHP includes geotechnical exploration and laboratory testing, design of structures, tunnel contract packaging and procurement planning.The Hudson Tunnel Project includes the construction of a new Hudson River Tunnel system and rehabilitation of the existing North River Tunnel. The new tunnel system will be constructed south of the existing North River Tunnel, from North Bergen under the Palisades to Hoboken in New Jersey, below the Hudson River, and connecting directly to Penn Station in New York (Fig. 1). The tunnel system is configured as two single-track tubes, intermediate ventilation shafts and cross passages in compliance with NFPA- 130 requirements. The adjacent surface alignment west of the Palisades will be constructed on viaducts, embankment and retained fills. The existing North River Tunnel (Fig. 2) consists of two single-track, electrified rail tunnels extending from tunnel portals in North Bergen, New Jersey to Penn Station in New York. Completed in 1910 by the Pennsylvania Railroad, the tunnel opened at the same time as Penn Station and the four, single-track, East River tunnels that connect Penn Station to Queens and onto Long Island and New England, respectively. Both tunnels in the existing North River Tunnel were inundated with brackish river water during Superstorm Sandy (Fig. 3), resulting in the cancellation of all Amtrak and NJ Transit service into New York City for five days. After the brackish water was removed from the tunnels, the residual chlorides and sulfates have had on-going detrimental impacts on the interior concrete and rail systems."

Sep 1, 2019

Dynamic permeability is a significant hydrologic condition associated with in-situ leaching at the Cyprus Casa Grande operations. Several factors contribute to changes in the permeability conditions. They are: 1) hydraulically induced fracture development, 2) geochemical changes during leaching in the rock matrix, and 3) changes in the relative degree of saturation of the deposit. Dynamic permeability conditions were evaluated using available pressure and flow rates from the 58 injection and recovery wells obtained over one year period. A finite element, 2-D hydrologic model called INVERT which is designed to estimate aquifer parameters under transient and steady state flow conditions was used for the investigation. The permeability conditions during 7 different steady state intervals throughout the one year time frame were determined. The results confirm that big changes in permeability occur as a function of time as well as a function of injection pressure condition.

Jan 1, 1991

By Vittorio Manassero, Antonello de Risi, Filippo Cavuoto

"This paper deals with an innovative mechanized method to bore and simultaneously line circular shafts, adopted in the Naples Metro project for the installation of 10 vertical shafts for ventilation purposes. With this method, excavation of shafts is carried out under a positive head of stabilizing fluid by a milling machine, temporarily set at the bottom of a permanent lining made of precast reinforced concrete segment rings. The debris is evacuated by inverse fluid circulation. The shafts in Naples are 4.5 m I.D., from 34 to 44 m deep and they are all located downtown in a highly urbanized area. They were bored and installed into volcanic soils under a hydrostatic head of up to 30 m. Displacements and groundwater level were constantly monitored to keep control of the effects on the surrounding buildings and utilities. INTRODUCTIONThe extension of Metro Line 1 in Naples (Italy) from the previous terminal of Piazza Dante to Piazza Garibaldi is also called the “low stretch”. Most of it runs along the coastline, encompassing the historical city center, the Greek-Roman Neapolis. The Metro Line crosses under densely urbanized areas for the whole way (Figure 1). It runs beneath Via Toledo, which follows the layout of the ancient Aragonese walls. The first station (Toledo) is located halfway along this street. Then, after a wide bend, the line reaches Piazza Municipio, where the second station is located. From there, the line moves along the axis of Via Depretis and Corso Umberto I, where the stations Università and Duomo are situated. The fifth station is in Piazza Garibaldi and the end of the stretch is located at the Naples Business Center. The twin single track tunnels were bored into volcanic tuff by TBM. This design choice simplified by far the construction of the tunnels and reduced to practically zero the interactions between tunnelling and surface buildings and utilities. Nevertheless, this choice entailed that the line had to be located at depths to the order of 35-45m below ground level and 30-35m below the water table. At each tunnel segment between stations, a pair of ventilation chambers were constructed (10 in total). Each ventilation chamber is connected to one TBM tunnel by a vertical shaft and a horizontal drift at the base of the shaft. The shafts, in addition to tunnel ventilation, provide a safety access/escape."

Jan 1, 2016

By M. Rodgers

Dow Water & Process Solutions (DW&PS) was approached by ASARCO Inc. to attempt to recover cobalt and copper from their copper solvent extraction (SX) raffinate. Cobalt is added to many copper electrowinning tankhouses to help to prevent lead electrode corrosion. With cobalt?s high price this can be a large expense. ASARCO has ore that contains a small amount of naturally occurring cobalt. Currently they have no way of capturing this high value metal from their leach or raffinate streams. DW&PS has some chelating resin technologies that should be able to help solve this problem.

Jan 1, 2010

By O. Ditsele

Coal plays an important role in the energy needs of the World. Given its wide abundance and low cost, coal use is bound to increase with the growing energy demand. Despite its importance, there are growing concerns over coal?s environmental burdens, especially its contribution to greenhouse gas emissions. To ensure sustainable extraction and use of coal, opportunities for minimizing potential impacts from coal have to be identified and exploited. Whilst extensive work has been done on life cycle assessment of coal use, especially in electricity generation which uses the bulk of coal produced, there has been limited work focusing specifically on coal mining. This study aims to estimate the cradle-to-gate life cycle climate change impacts of coal from a surface coal mine in the United States. The study employs general principles of ISO standards for LCA.

Jan 1, 2010

By J. A. Bleeck

A discourse on the relationship between industrial minerals and paper production, concentrating on high grade, ultra fine ground calcium carbonate (mean particle size less than 2 microns) and precipitated calcium carbonate. The scope of the paper encompasses four basic areas relevant to the topic: 1. A tutorial overview of the papermaking process with an examination of various industrial mineral components in that process; 2. A discussion of basic technological topics pertinent to the utilization of carbonate in paper with emphasis on the relative aspect. Of natural ground calcium carbonate (GCC) and synthetic precipitated calcium carbonate (PCC); 3. An overview of paper and carbonate market, in both the United State, and Europe with emphasis on (a) current status and future growth trend. Of such market., and (b) discussion of the major influences on growth and development of such market.; and 4. Identification and discussion regarding the principal producers in calcium carbonate markets serving the paper indu.try in Europe and North America.

Jan 1, 1993

By Saul J. Escalera

Mechanisms involved in the depression of the sulfides: pyrite, chalcopyrite, galena and sphalerite with potassium permanganate have been investigated. Flotation tests were conducted using potassium amyl xanthate, Z-6, and pine oil in the absence and presence of potassium permanganate at around pH = 6. 5 naturally yielded by the sulfides in the pulp. On the basis of crystal chemistry considerations, the amount of xanthate adsorbed by the sulfides depends on the amount of sulfur and metal ions present on the surface; thus, the avidity of the sulfides for xanthate should increase in the order: sphalerite C chalcopyrite 4 galena 4 pyrite, and the ease of depression response to the permanganate action should be in the same order. Depression of the sulfides in the system occurs primarily due to the removal of the collector ions by the permanganate ions to form manganese dioxide and dixanthogen according to the reaction: 3 M(RX)2 + 2 Mn04 + 4 H20 2 ? MnO2 + 3(RX-XR) + 3 M+2 8OH where M represents the metal ion, RX the xanthate ion and (RX-XR) the dixanthogen molecule. Results seem to indicate that the permanganate ions play a triple role in the system: (1) they convert xanthate ions into dixanthogen, (2) they further oxidize the mineral surface and (3) if present in excess, they may oxidize the xanthate beyond the dixanthogen stage with the formation of CO2, H20 and SO4. All sulfides, except for chalcopyrite, showed a depression response in the order predicted regardless of the order of addition of xanthate and permanganate reagents. Chalcopyrite did not depress as easily; this behavior may be due to the avidity of the colloidal MnO2 to adsorb Cu+2 ions on its surface, this would destabilize the colloid making it coalesce with the formation of a layer of precipitated MnO2 on the surface of the mineral. The presence of this layer would prevent further action of the permanganate ions on chalcopyrite.

Jan 1, 1970

By Amri Priambodo, Ian Leslie, Valérie Laflèche, Agustina Ratnaningrum, Robin Paine, Andrianus Sinaga, Willem de Beer

Freeport Indonesia consists of surface, civil and underground mining areas exposed to numerous geotechnical risks and hazards. PTFI uses various monitoring systems (Micro-Seismic, Firefly Light System, Mira Geoscience machine learning, etc.) to effectively manage these risks. The significant volumes of data from these sensors must be integrated into actionable information to provide the expected risk management. This occurs at the GeoEngineering Integrated Monitoring Centre (GIMC), a centralized department within the GeoEngineering Division, tasked with the responsibility to manage all geotechnical monitoring systems. The main hazard the GIMC is responsible for managing in real time is mine seismicity within the underground mining areas and the potential impacts on safe operations. Seismic system engineers achieve this objective through 24 hours a day and seven days a week operations of the GIMC, providing a centralized point of communication, alerts, evacuations and control during seismic events and emergencies. This paper will describe how the GIMC achieves its goal using reliable procedures and strategies based on detailed Triggered Action Response Plan (TARP), concise communications, novel technologies (FireFly Lighting System), and proven seismic re-entry programs to manage risk within the underground mining operations. The integration of geotechnical monitoring and reporting into a centralized group has improved the effectiveness and management of seismic risks and hazards at PT Freeport Indonesia (PTFI) mining operations.

Apr 26, 2022

By Jamal Rostami, Mark Board, Clayr Alexander, Muthu Vinayak Thyagarajan

In the past several decades, many major equipment manufacturers have ventured into developing new technology for underground hard rock excavation. This includes variety of configurations for full and partial face mobile excavation units. Mining industry prefers machines that can excavate noncircular, flat invert profiles and be able to make tight turns in hard rock. The need to use disc cutters for cutting hard rock has impeded the development of such machines due to the need for gripper system or large mass of a machine to support the force requirements of the disc cutters. Most of the prior attempts have been partially successful and the operations have faced some practical limits and challenges. Among the units that have been successfully used, one can name mobile miner, which was used for rock excavation in some projects. A redesigned mobile miner, called the “Remote Vein Miner,” or RVM, has been developed by Epiroc for underground hard rock mining in Hecla’s Lucky Friday Mine. This equipment potentially opens numerous opportunities for innovation in civil tunneling projects, where the operational flexibility and accessibility of a TBM’s limited tunnel path, design of the profile, and cost are limiting factors. This paper explores the application of the RVM in tunneling projects, its advantages and possible areas of innovation in tunnel planning and design.

Jun 13, 2021

By Augusto Andres Torres Toledo, João Felipe Coimbra Leite Costa, Luciano Nunes Capponi, Diego Machado Marques

Short-term mine planning to open pit requires defining diglines to orientate the excavation geometry. In deposits with multiple chemical variables, it is necessary to have more rigorous control over the feeding of the processing plant. This study analyzes the impact of incorporating multiple chemical variables, the risks generated by geological uncertainty, and the number and starting point locations of shovels in the sequential design of diglines. The objective is to maintain and preserve the low-grade variability, required tonnage, and continuity in sequentially selecting blocks. To achieve this, the probability distribution function of each chemical variable is used while attempting to maintain the ore grades as constant as possible. As it is difficult to maintain multiple elements with low variability simultaneously, the relevance of each chemical variable in the economic benefit is identified. Weights are assigned to signal the importance of each element based on its significance in the recovery process. Several diglines, consisting of sequential blocks, were generated on the same seed point to meet the weekly ore demand. Optimizing the stationarity of multiple chemical variables, accessing and reducing the geological uncertainty performed through geostatistical simulation of grades and transfers functions, considering the number and location of shovels, while meeting the operational restrictions of the selected blocks. The optimized digline with the multiple grades as stationary as possible is retained. The process is illustrated in a phosphate mine. The results show that the proposed method is viable and allows for a quick solution.

Jun 25, 2023

By L. Barnewold, A. Merchiers, M. Pütz, P. Jeschke, M. Dammers

The mining industry faces many difficult challenges, for example, lower ore grades, smaller and deeper deposits, and longer transportation distances. In the past, there have been remarkable innovations in both equipment and the types of mining methods for which it is used, which have resulted in economies of scale. This has led to an increased use of bulk mining methods, like sublevel and block caving, which has increased productivity and reduced costs. Haulage alone plays a major role. Current haulage techniques are a significant cost driver, which account for between 15 and 30% of the overall capital investment (capex) in a mine and are an increasingly part of the operating costs (opex). The paper introduces a simulation tool of main haulage system in underground mining. Therefore, performances and the costs of the three most common underground main haulage systems, rail, truck, and conveyor, are calculated using a developed modeling tool. The tool was applied and validated in a case study carried out with the LKAB Kiruna Mine in northern Sweden.