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By C. E. Jordan

Abstract. The U.S. Department of the Interior, Bureau of Mines, as part of its effort to maintain an adequate supply of minerals and metals to meet national economic and strategic needs, is conducting research on the pneumatic recovery of coarse mica. A system of crushers, screens, and zigzag air classifiers is used to concentrate coarse liberated mica particles from mica ore and from the waste tailings of abandoned mica operations. The plus 0.21-millimeter-size mica is effectively recovered by this method. The mica concentrates produced contain over 90 percent mica. The method recovered up to 78 percent of the mica in the samples. As a dry concentration method, the pneumatic-beneficiation technique may be advantageous in areas of limited water resource.

Jan 1, 1980

"The Mine Haul Road Optimization Alliance is an Australian industry-academia collaboration which has been developed to support mine haul road operators by fully integrating mine road design research solutions with industry end-user service providers to design, assess, implement and monitor the various equipment, materials and road management strategies required to optimize the safety, environmental and economic performance of a haul road. Initially, a broad overview of the university-industry collaborative landscape is presented, following which the current situation in the Australian mining sector is reviewed both nationally, and on a country-wide basis, internationally. This insight places realization of a collaboration between Curtin University Western Australian School of Mines Mining Engineering and Metallurgical Engineering (WASM ME2) and the Haul Road Optimization Alliance (HROA) industry members into context of opportunity. Following an overview of the HROA collaborative structure, aims and objectives, it is shown how academia and industry can collaborate to deliver a more robust solution to mine haul road design, performance or management needs, especially where integrated solutions are needed. Critically in this approach, implementation and monitoring data provided by industry and service-providers alike forms the foundation on which to develop research knowledge and innovation that is more responsive to the end-user requirements, typically represented by ‘early goals’ and implementable solutions. The paper concludes with examples of how the alliance collaborations work in practice to deliver improved mine haul road designs and optimized operational performance, together with the mechanisms used to ensure industry needs are met through focused, end-user driven research and integrated solutions implementation."

Jan 1, 2016

By R. A. Matuszak

Throughout the history of power excavating machines, engineers have continuously tried to shape the main drive speed-torque characteristics to provide an optimum performance from each main motion. Selection of prime mover for the various motions has been the subject of many engineering studies and most forms of energy conversion have been tried. A new form of electrical power conversion looms on the horizon' as the most optimum yet. Controlled frequency operation of a squirrel cage induction motor increases the reliability of the most reliable form of energy conversion (electrical) found thus far and at the same time improves the performance characteristics.

Jan 1, 1977

By Steve Karl

"The global underground construction and tunneling industry is in pretty good shape. Billions are being spent in shoring up aging infrastructure in the United States and other places, and new underground projects are being put out for bid.With each new project, comes new equipment, technology and tunneling methods. So it is incumbent on tunneling professionals to constantly improve their knowledge of the profession. This is where spending a few days with other underground construction professionals can assist the tunneler in keeping up.Every two years, tunnelers and underground construction engineers, contractors, suppliers, designers and owners from around the world gather for the Rapid Excavation Tunneling Congress (RETC). The 2017 conference was held in June in San Diego, CA. The UCA of SME puts on the conference.This years’ RETC attracted 1,400 attendees. The accompanying sold-out exhibit totaled 188 service and equipment suppliers. In addition, the conference had the UCA of SME bookstore, where the new History of Tunneling in the United States book was introduced. And a short course on tunnel rehabilitation was featured.Technical programmingRETC 2017 featured nearly 100 technical presentations. Topics covered the breadth of the global underground construction industry. Here is a sampling of a few. The proceedings from the conference is available from SME, 303-948-4200, www.smenet.org.Accomplishing extraordinary tasks as a machine supplier for Metro Doha: The construction of the Metro Doha in the State of Qatar established a modern, safe, efficient and integrated public transportation network. Upon final completion of multiple phases, the network will comprise four metro lines with a length of 216 km (83 miles) and 100 stations. Phase one comprises 112 km (43 miles of underground tunnels (56 km or 22 miles of twin-tube tunnels). Twenty-one earth pressure balance tunnel boring machines (TBM) were deployed by the four different joint ventures. The project was initiated, managed and supervised by the owner, Transport Authority Qatar Rail.Phase two of the Doha Metro will start upon the completion of Phase One in 2019 (Qatar Vision 2030). The owner placed full faith in the manufacturer’s abilities to deliver equipment of high quality, state of the art standards within the given time frame. This paper focused on the manufacturer’s scope of delivery and on the supplier’s high standards of quality in production, logistics and services."

Jan 9, 2017

By Pratama Mochamad Rizki, Andika Satya

High-risk area in open-pit mining should always be monitored by the operational supervisor because of its nature. One of this type is the soft soil dump area. Due to the unstable bearing capacity of the soil, it’s highly possible for us to find cracks in the area. This paper aims to build computer vision which able to detect truck’s distance from safe limit allowed during dumping activity. The system will warn the truck’s driver if the truck has crossed that predetermined safe limit.

Jun 25, 2023

By S. S. Klima, H. Jiang, T. W. Beck, Y. Zheng

Researchers at NIOSH’s Pittsburgh Mining Research Division (PMRD) performed comparative testing of six different water sprays at pressures ranging from 689 kPa (100 psi) to 6,895 kPa (1,000 psi) in a 14.5-m3 (512-ft3) confined dust chamber. Testing was conducted to determine the effect of various pressures on each spray’s respirable coal dust knockdown ability. It is known that higher water pressures are typically preferred for lowering airborne dust concentrations, but it was important to determine at what pressure range the dust knockdown ability of each spray plateaus or reaches its minimum dust concentration. Results from this testing showed that several sprays saw up to 100% decrease in dust concentrations during the five-minute water spray testing period, with some occurring well below the maximum 6,895 kPa (1,000 psi) spray pressure.

Feb 1, 2023

By T. S. Golosinski

Use of contractors to excavate, load and haul mined material is widespread in Australia. It is also becoming a common practice in many other countries. The paper reviews current practices in Australian contract mining. Various types of contracts are reviewed, including partnering arrangements and alliancing between the contractor and the mine owner. Applicability of various types of contracts to specific mining situations is discussed, as is their impact on overall mine performance

Jan 1, 1998

By R. J. Gray

Oxidation of coal can best be described as a process of deterioration, since most of the uses of coal, such as for fuel and by-product chemical and coke production, are adversely affected by coal oxidation, and the inclusion of oxidized coal in most coal products detracts from their value. There are probably many mechanisms of coal oxidation, and the ways oxygen molecules combine as complexes with coal macromolecules to form new substances have been dealt with and speculated upon by many workers1)* but are not dealt with in the present work. This study deals with tests and methods of detecting oxidized coal, with particular emphasis on the microscopically discernible changes that accompany the chemical and physical changes that affect the technological properties of coal during oxidation.

Jan 1, 1974

By Günther M. Volkmann

"INTRODUCTION The construction of the BAB 44 motorway between Kassel and Herleshausen (both Germany) is an important part of the trans-European road network. After its completion, the A 44 will permit an efficient connection of the Benelux States in the West and Poland in the East. In the section between Eschenstruth and Hessisch Lichtenau the Hirschhagen Tunnel is constructed with a length of 4.1km. Most sections of the tunnel are situated in weak ground conditions. Hence a combination of face bolts with spiles (short forepoling) or pipe umbrellas (long forepoling) additionally support the tunnel heading on a regular basis This article will focus on the application of a newly developed method to connect the pipe umbrella support, which is mostly installed by conventional drilling machines nowadays. The installation method limits the outer diameter to a maximum of 168mm and a pipe wall thickness of 12.5mm because workers must be able to handle pipes and its drill steel. Typically these pipes are connected with threads that create a weak link in the support system so during the last decade alternative connection systems were developed to overcome this disadvantage. One of these alternative coupling systems is the so called Squeezed Connection, which will be explained in this article followed by a discussion of its advantages and disadvantages regarding technical specifications, construction time, and safety issues. THE HIRSCHHAGEN HIGHWAY TUNNEL The German highway A 44 directs from Aachen through the Ruhrgebiet to Kassel (all Germany) and it is extended to Herleshausen (Germany). The new section connects the A 7 to the A 4 after completion. This upgrades the east-west highway connection starting at the Benelux Union and heading to Poland so it is an important part of the trans-European road network. The newly constructed section has a total length of approximately 63 km and comprises 13 tunnels. All tunnels are constructed as double tube tunnels with 2 lanes and emergency sidewalks on both sides and 14 emergency cross passages. The Tunnel Hirschhagen starts in the north of Eschenstruth and ends near Hessisch Lichtenau (Figure 1). The length of the northern tube is 4,147 m and that one of the southern tube is 4,204 m. So it is the longest tunnel of the A 44 and the second longest highway tunnel in Germany when it is put into operation. On its alignment it crosses underground the Losse valley with the state road 7, the streetcar Kassel-Hessisch Lichtenau and the Losse stream. The cover above crown varies from 10 m to 95m and it is the lowest when crossing the Losse stream."

Jan 1, 2016

By Ingo Kaundinya

"INTRODUCTION Tunnels are important elements of the German federal road network which have to cope with an increasing traffic load especially of heavy goods vehicles. In order to ensure a high availability and safety level for these key infrastructures, big efforts are required by owners and operators in order to keep all infrastructures up to date. This mainly relates to current European regulations regarding tunnel safety (Directive 2004/54/EG) [1] and their national implementation, which must be fulfilled by many existing tunnels. In this context the German Federal Government spends more than 1.1 billion € for the structural and operational retrofitting of more than 120 existing road tunnels. As many of these projects have recently been finished or are still under progress, experiences and best practices could be reported. After the description of current requirements in national standards regarding structural fire protection, the paper gives an example for an upgrade of a tunnel’s fire protection by installing an additional fire protection system, which is a quite costly measure. Another possibility to fulfill current requirements regarding structural fire protection could be the numerical proof of sufficient bearing capacity of a structure. The influence of different fire loads and fire durations on the bearing capacity of typical road tunnel structures have been investigated in a research project funded by the German Federal Ministry of Transport (BMVI) and coordinated by the Federal Highway Research Institute (BASt). The results of this research project have been used to define a procedure how to investigate existing tunnels regarding structural fire protection. Finally, the research results have also been the basis for a current update of national standards for tunnel construction. REQUIREMENTS REGARDING STRUCTURAL FIRE PROTECTION The structural fire protection design of road tunnels is usually based on temperature-time curves of exposure to fire, for simplicity called ""fire curves"". The fire development after fire growth is illustrated with fire curves. Fire curves can be subdivided into a heating-up phase, a fully developed fire phase, and if applicable, into a cooling-off phase (cf. Figure 1). During the fully developed fire, the fire remains at a certain temperature level."

Jan 1, 2016

By J. Platt

Debate over acid rain legislation has presented a moving target for coal and utility company planners attempting to figure out how legislation will affect their business environment. In spite of disagreement among experts, the prospect for continued change, and persistent --perhaps even growing --uncertainty, a great deal has been learned about coal market dynamics. This paper reviews progress and describes some of the major problems and controversies.

Jan 1, 1990

By Stephen LaBrooy, David Muir

Gold ores in the geologically more recent rocks are often associated with copper minerals which pose problems of high reagent consumption with conventional cyanidation practice. Many examples exist in northern Australia, Indonesia, Papua­New Guinea, Chile, and Brazil where, despite various treatment options (LaBrooy, 1992), the processing of oxide and transition ores is uneconomic either for copper or gold recovery. Hence, there is a need for a reagent which is selective for gold without leaching copper minerals. The ammonia-cyanide system appears to meet this criterion (Muir et al, 1989; LaBrooy et al, 1991; Costello et al, 1992; Hayes and Corrans, 1992) but it has proven difficult to optimise and apply to a variety of ores due to differences in the mineralogy and reactivity of ores and a lack of understanding of how the system works. Recent work on the mechanism, however, (Muir et al, 1993) has thrown a new light on the problem which should allow better process control. Ammonia­cyanide mixtures behave neither like free cyanide nor free ammonia and too much of either reagent in the mixture is detrimental. The key to the process is understanding how ammonia enhances gold extraction yet inhibits copper extraction in an essentially cyanide environment.

Jan 1, 1993

By Russell Frith

The entire subject area of micro-seismic events due to stored strain energy, as distinct from gas-driven coal outbursts, can be readily sub-divided into firstly events with their energy source from within the coal seam (termed “bursts”) and secondly, event with their energy source outside of the coal seam in either the overburden and/or floor strata. The reason for sub-dividing micro-seismic events in this manner is that if the causation mechanisms and associated geotechnical conditions are materially different, then effective pre-mining predictions and subsequent operational controls may also differ. Attempting to explain a multitude of micro-seismic event types without consideration of varying source mechanisms will inevitably lead to inadequate causal explanations and effective controls.

By Judson C. Higgins

The paper addresses changes in surface transportation methods in the Industrial Minerals business starting with history, the changes to present time including such areas as energy costs, improved highways, changes in regulations and deregulation, and attempts to project future transportation trends. Transportation methods such as rail, piggyback, truck and barge are compared, and their impact on Industrial Minerals producer's costs and profits examined. The customer impact on our businesses due to deregulation is also discussed.

Jan 1, 1983

By Cary Hirner, Dan Lopez, Ross Webb, Stephen O’Connell

"Construction of the largest desalinization plant in the Americas has commenced in northern Chile. It is part of a several billion dollar expansion at a copper mine whose operations nearly stopped due to the challenge of securing a reliable source of water from the Pacific Ocean in a safe and environmentally sound manner. This paper discusses the risk management, design and construction of a quadruple chamber intake and outfall shaft, high capacity pump station, three 7m diameter vertically drilled marine shafts and three subsea tunnels constructed through challenging Andean hard-rock geology. The three 2.5m diameter subsea microtunnels are being mined with vertical curves through variable quality rock 30 meters beneath the ocean and retrieved in the wet from the 7m diameter marine shafts. INTRODUCTION AND BACKGROUND The battle for securing the rights to a constant water supply is a worldwide issue and nowhere is that more evident than the Atacama Desert of Chile, the world’s driest place with areas of the desert that have not seen rainfall in recorded history. The Atacama Desert also happens to be home to some of the world’s largest ore deposits which require huge amounts of water to extract and process. What available water there is comes from three main sources: deep seated wells, glacial water from the Andes Mountains, and desalinated water. Vying for water from wells and glacial streams and lakes are numerous agricultural and domestic facilities in the valleys surrounding the Atacama Desert. Environmental regulations and legal rulings have limited the amount of “natural” source water which can be used for mining purposes. Desalination plants are a known solution for combating water scarcity, albeit a costly one. The total estimated cost of constructing this desalination plant is over $3B USD, which will include a 2500lps capacity and an approximately 118km pipeline from the coast up to the mine located in the Andes. The overall scope of the project includes design, procurement, and construction packages for the 2500lps desalination plant including the seawater reverse osmosis plant, water conveyance to the mine, power transmission, the reservoir and the marine works package which forms the basis of this paper. Key components of the underground construction portion of the Marine Works are:"

Jan 1, 2016

By T. G. Rozgonyi

The basic goal of this investigation was to determine the degree of drying of high moisture lignite through the use of high temperature and pressure steam autoclaves. Specific items studied were: a) the effect of lignite particle size, b) steam temperature and pressure required, and c) the time of ahydration. Although removal of sodium, ash, sulfur and other ash-forming minerals was not the goal of this study, basic analysis of effluent water showed organic material and alkalai metal content. Removal of inherent moisture from run-of-mine lignite was tested by lock-feeding the lignite, which was previously sized by screening into 25 kg autoclaves. High pressure, up to 4.053 MPa (588 psi), saturated steam was then introduced into the pressure reactor. Reaction time, pressure, temperature, and depressurization rates were strictly controlled for each reactor test run. Results indicate that about 80% of lignite total moisture was removed, including some of the inherent moisture, yielding a non-oxidized, and thus stable, lignite product. As stated, a side benefit occurred as some reduction of non-combustible portions of the lignite also took place. The conclusion reached as a result of the tests is that the steam-drying process can be successfully applied to reducing moisture in lignite, and may be considered for additional studies on acceleration of the coalification process. On the basis of the data presented, the author believes that lignite can be economically upgraded in steam autoclaves by simultaneously reducing the moisture content by 80 percent and the sulfur content by at least 50 percent. Upgrading the lignite by this method will result in large energy and financial savings.

Jan 1, 1984

By Sadegh Elyasi

TBMand roadheader are two dominating excavation machines in underground tunnelling projects. The performance of these two tunnelling machines has been reviewed and analysed individually by many researchers from multiple points of view. However, there are almost no studies that have made an extensive comparison between these two machines, mostly from financial points of view. The current study is intended to characterize both financial and technical status of these two mechanical tunnelling machines in one of the biggest coal mines in Iran. The main objective of this study is to define the best method and equipment that meets a predefined economic goal, which is mainly to maximize the net present value. To this end, a technical and financial model based on the geomechanical and financial parameters involved in the project has been prepared and the financial part of the project has been carried out by applying COMFAR III financial analysis software. Subsequently, a sensitivity analysis of the model was conducted in order to evaluate the effect of involved parameters on the project. According to the results, a roadheader has better economic justification than a TBM, while the TBM has a better advance rate than the roadheader.

Feb 12, 2021

By E. J. Beckman, R. M. Enick, C. Shi

A novel liquid-liquid separation for the recovery of free or liberated gold from mixtures of fine particles was evaluated. Two inexpensive and environmentally benign fluids were selected for the study, water and carbon dioxide. The separation, which is conducted at 295 K and at the vapor pressure of carbon dioxide (6.0 MPa), is based on differences in wettability between the precious metals and other minerals. Contact-angle results indicated that, in the presence of water and liquid CO2, gold is slightly hydrophobic. The addition of CO2-soluble fluoroalkyl thiols or f uoroetherthiols increased the hydrophobicity of gold exposed to water and CO2 to a greater extent than alkylthiols. Minerals, including quartz, pyrite and magnetite, were hydrophilic. During the separation, an aqueous slurry of fine mineral and gold particles was mixed with liquid carbon dioxide. Pure gold particles (-325 mesh) were found to agglomerate at the H2O-CO2 interface. The minerals tended to remain in the aqueous phase. Despite these promising preliminary results, very poor gold recoveries were obtained when applying the procedure to an Australian gravity concentrate. This was attributed to the native gold particles in the concentrate being either too large, agglomerated in slimes or coated with minerals. Although this particular application was unsuccessful, this water-CO2 biphase technique may be applicable for other separations that require the removal of very fine, hydrophobic particles from an aqueous slurry.

Jan 1, 2000

By Marko Oosthuizen, Charl P. Botha, Lidia Auret, Annelette Malan, Marthie de Leeuw

Flotation performance is affected by upstream disturbances (e.g., mineralogy, water quality, flow rate) and controlled variables (e.g., pulp level and air addition). Process disruptions can lead to undesired conditions, such as pulp overflowing flotation cells (with insignificant/absent froth, and thus no valuable mineral concentration). Early detection and appropriate intervention of pulping events improves concentrator performance. An approach to real time flotation pulping event detection by means of convolutional neural networks is presented, including a case study of the industrial application of this technology on three flotation banks.

Feb 22, 2026

By Linda D. Raedeke

The main platinum-group metal (PGM) deposit in the Stillwater Complex is associated with a stratiform zone formed by magma mixing. In general, the intrusion is a large, layered body of Archean age which formed by repeated magmatic injections in- to a single, large, hypabyssal magma chamber. The Complex is broadly divided into the lower Ultramafic series of olivine ± orthopyroxene rocks (1000-2000 m thick) and the upper Banded series of predominantly plagioclase-rich rocks (24500 m thick). The latter is further divided into Lower, Middle, and Up- per Banded zones. The Ultramafic series, plus most of the Lower and Upper Banded zones formed from repeated injections of an olivine-saturated magma, the rocks accumulating from the floor upward with a crystallization order of olivine, or- thopyroxene, plagioclase, clinopyroxene. The olivine-bearing subzones of the Middle Banded zone formed predominantly from a magma which crystallized in the sequence plagioclase, olivine, clinopyroxene. Olivine-bearing subzone I, with which the PGM mineralization is associated, occurs generally -400 m above the Ultramafic series-Banded series contact. Ore grade mineralization is usually found in plagioclase or plagioclase-olivine cumulates. The platinum-group elements are associated with disseminated base-metal sulfides dominated by the assemblage, pyrrhotite-chalcopyrite-pentlandite. Olivine-bearing subzone I marks an interruption in the crystallization sequence of the Lower Banded zone, with the reappearance of cumulus olivine and an associated change of the crystallization sequence. These changes indicate the addition and mixing of a secondary magma of the same composition as that which later dominated in the formation of the Middle Banded zone. Characteristics associated with mixing include laterally discontinuous but well-developed layers, xenoliths of ultramafic rocks, and sedimentary-type structures such as slum- ping and graded layering. The influx of new magma caused sulfide saturation by one or more of several chemical changes including addition of sulfur, decrease in oxygen fugacity, decrease in FeO, or increase in SiO2. Once an immiscible sulfide liquid was formed, platinum-group elements were scavenged from the magma by the sulfide liquid and segregated.

Jan 1, 2013