Search Documents

By T. Gouri Charan

Indian coals, which are of Gondwana origin, contain high amounts of mineral matter, wherein the extraneous material was intimately mixed in the coal matrix during the formation stage, causing a high level of impurity in the run-of-mine (ROM) material. These coals possess difficult to very difficult washability characteristics. Beneficiation of high-ash non-coking coals of India has become the prerequisite for improving the overall economics and efficiency of power generation. The use of dry cleaning systems in India for beneficiation of non-coking coals has gaining renewed interest recently. The benefit of the dry beneficiation process is to exploit the given resources while providing a more reliable and consistent quality fuel with a low operating cost. M/S Allmineral has introduced a technique for the dry beneficiation of coal, which is being tried in India for the treatment of high-ash non-coking coals. The first commercial air jig of 50 t/hr capacity was installed and commissioned to beneficiate high-ash coals of 40 x 5 mm feed with an ash content of 40%; a clean coal product of 33% ash was produced and is being used for a sponge iron plant.

Jan 1, 2011

By Sotiris N. Kamenopoulos, Zach Agioutantis

Rare earth elements (REEs) are considered critical minerals for industrial and defense sectors. REEs are not as rare as the word “rare” portrays; yet, the exploitable and/or profitable deposits of REEs may be found only in certain geographical areas. The political and social conditions characterizing these areas may not always be in favor of mining operations. These conditions are imposing the need for extra consideration on the geopolitical constraints prior to any decision-making and before any mining project begins. This study assesses the risk related to mining projects for areas that feature REE deposits based on a geopolitical viewpoint. Probable ranking differences between the current assessment and a 2015 assessment are discussed. The comparative indicators used and the appraisal procedure applied in this comparison are based on a number of different geopolitical indicators. Several ranking changes occurred between 2015 and 2019.

By T. L. Barone, J. R. Patts, L. D. Patts, S. J. Janisko

"Controlling float coal dust in underground coal mines before dispersal into the general airstream can reduce the risk of mine explosions while potentially achieving a more effective and efficient use of rock dust. A prototype flooded-bed scrubber was evaluated for float coal dust control in the return of a continuous miner section. The scrubber was installed inline between the face ventilation tubing and an exhausting auxiliary fan. Airborne and deposited dust mass measurements were collected over three days at set distances from the fan exhaust to assess changes in float coal dust levels in the return due to operation of the scrubber. Mass-based measurements were collected on a per-cut basis and normalized on the basis of per ton mined by the continuous miner. The results show that average float coal dust levels measured under baseline conditions were reduced by more than 90 percent when operating the scrubber. IntroductionAirborne coal dust is a byproduct of coal production, and engineering controls exist to deal with both the respirable dust health hazard as well as the float dust explosion safety hazard. Float coal dust, smaller than 75 µm (0.003 in.) in size, can deposit throughout mine entries and propagate explosions that had been initially fueled by methane gas. The inertization of float coal dust with rock dust helps prevent a potential secondary float coal dust explosion, but a preferable course of action is to significantly reduce the hazard by removing float coal dust from the airstream before it has the opportunity to deposit on the mine’s surfaces.Since 1970, disasters due to explosions in underground coal mines have caused 201 deaths in the U.S. mining industry, including 29 deaths in a single mine explosion in 2010 (Wade, 2010; U.S. Mine Safety and Health Administration, 2015). The U.S. National Institute for Occupational Safety and Health (NIOSH) had initiated a fiveyear research project that aims to investigate methods and technologies to reduce the potential for secondary coal dust explosions by the purposeful capture and/or suppression of float coal dust prior to its deposition on the mine roof, rib and floor (NIOSH, 2013). The project aims to evaluate the efficiency of methods to reduce longwall and belt airway float dust in the general airstream as well as methods to capture it at or near the source. Prioritization is given to longwall sections given the amount of coal produced relative to continuous miner sections, but the research is open to technologies that may be adapted from one method of mining to another."

Dec 1, 2016

By K. Darcovich

The wettabilities of agglomerates made from coals of several different ranks were measured by the adhesion technique. Oil levels from 0 to 10% by weight were used. As was expected, it was found that higher-rank coals are more easily oil-wetted and that the surface properties of the agglomerates correlate with agglomeration recovery and ash removal data.

Jan 1, 1992

By Sumit Kumar Hota, Asadi Srinivasa Reddy, Ashok Kumar, Ashish Agrawal, Surajit Sinha, Chandra Sekhar, Tanay Ray

In the current operational facility, due to the absence of pellet pot facility, a novel technique is developed wherein the pellets with different chemistries prepared in the laboratory are fired in an induration machine by placing them inside the Inconel baskets. In the present work, an attempt is made to optimize the pellet chemistry by developing 2 different flux pellets, viz., low basicity (B2: CaO/ SiO2 = 0.3) pellets and high basicity (B2 = 0.9) pellets, and further the effects of basicity on pellet properties, viz., cold compressive strength, porosity, swelling index, reducibility index, and softening and melting temperature, are studied. It has been found through the multiple operational trials that increasing the basicity of pellets from 0.3 to 0.9 results into improving the pellet strength, reducibility and softening and melting characteristics. Moreover, it is observed that the swelling index of pellets is reduced by adding 2% MgO to both low and high basicity pellets that could be attributed to the formation of high melting point slag in pellets. The operational trial has resulted into producing pellets that exhibit a combination of desired mechanical strength, improved swelling, and reducibility index and possess better softening–melting behavior among all the chemistries studied.

May 24, 2022

By Dan Witkowsky

In an increasingly environmentally conscious world, mining's importance to society has often been misunderstood and even maligned by the public. Extreme and impractical ideas have often been presented to children because of the lack of accurate, timely resource materials available to educators. In the late 1960s. two mining engineers, S.P. "Pi" Warren and C.L. "Lindy" Barker, became aware of this situation. They proposed to develop a summer field course to provide a factual overview of the minerals industry for teachers. The pair believed that teachers could become better informed to educate students, and future generations, about mining. These two Colorado Mining Association (CMA) members felt that such a course could reduce much of the misunderstanding about this vital industry. This could be done by providing a balanced perspective of mining, not only for kindergarten-through-grade-12 teachers, but also for the students they would be teaching during their careers. Students who better understood the minerals industry could better formulate an unbiased view of it. The course would seek recognized authorities from industry, academia and government who would lecture in their respective fields of expertise. The course would provide a total concept of the coal, aggregate, metals and industrial minerals industries. It would include geology, geophysics, exploration, mining, processing, marketing, product applications, economic, mining history, careers, and environmental responsiblity. When possible, site visits would permit educators to view operations and to meet the men and women who are industry leaders. Teachers would pay a small tuition fee. The balance of the program expenses for each teacher would be paid through scholarships provided by industry and individuals. The "total concept" idea obtained the support of the minerals industry. The support of CMA's Education Committee and the Colorado School of Mines (CSM) was obtained in 1968. Colorado's Commission on Higher Education approved teacher recertification credits through CSM's Office of Special Progams and Continuing Education for those successfully completing the program. The first six-week series of classes presenting the total concept of the indus¬try was held at CSM in 1969. In 1977, the CMA Education Foundation Inc. (CMAEF) was established as a Colorado nonprofit corporation. The "Total Concept of the Mining Industry" (Total Concept) course was placed under its sponsorship. CMAEF is dedicated toward this continuing education program (Table 1). In 1994, the course was streamlined to four-weeks for six hours recertification credit.

Jan 1, 1997

By D. J. Beeby

California's Surface Mining and Reclamation Act (SMARA) was passed in 1975 to identify and protect mineral resources in areas of high land use conflict and ensure reclamation of mined lands. Under SMARA, aggregate resource availability is quantified and compared to forecasted demand in specific market regions. Fifteen regions studied thus far cover 51,800 km2 (20,000 sq miles) and contain 45 Gt (50 billion st) of high-quality aggregate resources that have been legally designated as "regionally significant," providing a measure of protection previously unavailable. SMARA reports and state testimony at local hearings have supplied objective information and helped reduce conflict in mine permitting decisions.

Jan 1, 1987

By MATTHEW HART, THOMAS BAMFORD, Kamran Esmaeili, MICHAL KOWALCZYK, FILIP MEDINAC

Improved haul-road conditions can have a positive impact on mine operations, resulting in heightened safety, productivity gains, longer tire life and lower maintenance costs. For these reasons, a monitoring program is required to ensure the operational efficiency of the haul roads. Currently, at Bald Mountain Mine, monthly site severity studies, ad hoc inspections by frontline supervisors or operator feedback reporting are used to assess road conditions. These methods are subjective and provide low temporal resolution data. This case study presents novel unmanned aerial vehicle (UAV) technologies, applied on a critical section of haul road at Bald Mountain, to showcase the potential for monitoring haul roads. The results show that orthophotos and digital elevation models can be used to assess the road smoothness condition and to check the road design compliance. Moreover, the aerial mapping allows detection of surface water, rock spillage and potholes on the road that can be quickly repaired/removed by the dedicated road maintenance team.

By Meng Wang

"In this study, multiple methods that include geological surveying, laboratory studies, and numerical modeling have been used to study the deformation characteristics of a “deep inclined rock roadway with weak planes” (DIRRWP). Failure of the DIRRWP was found to be triggered initially by the shearing of the rock near the weak plane. The movement of the failed rock resulted in reduced confinement of the deeper rocks, and causing the failure of the supporting units and the severe deformation of the surrounding rocks. Hence, it is concluded that DIRRWP stability is affected predominantly by rocks near the weak plane. Corresponding control strategies for DIRRWP deformation were proposed: (1) greater support intensity is necessary to maintain the stability of the whole DIRRWP; (2) additional support is needed for rocks near the weak plane to reduce the potential of failure; (3) to increase the bearing capacity of the floor strata, as the floor needs to be supported; and (4) a supplementary support technique should be considered for cases of large deformation. The case study presented here indicates that the proposed control strategies can significantly reduce the potential of failure in rocks near the weak plane, thus preventing severe deformation of the DIRRWP.INTRODUCTIONAs shallow seams are mined out, the cover depths in most Chinese coalmines have become increasingly greater. Deep cover in a coalmine is considered to occur when the cover depth exceeds 800 m (Sun, Chen, and Miao, 2018). The loading and failure behavior of rocks in a deep cover setting are quite different from those in a shallow cover setting owing to the increase in in-situ stress, temperature, and hyperosmosis (Lobanova, 2008; Zhang et al., 2013). For instance, experience shows that bulking and dilating deformation in deep roadways is much greater than that which occurs in shallow roadways (Hou and Yang, 2018; Zhang et al., 2016). In addition, anisotropic behavior and thickness deviation of coal measure rocks, combined with the appearance of weak planes (e.g., faults, joints, and coal cleats) in coal and/or rocks, can significantly affect the stability of an underground roadway (Ghazvinian et al., 2013; Sun, Chen, and Miao, 2018). The presence of weak planes can significantly complicate displacement and stress transmission in nearby rocks. Additionally, tensile, compressive, and/or shearing failure in rocks near weak planes can be easily caused by high in-situ stresses in deep roadways; such failures may lead to further severe deformation of the surrounding rocks, resulting in roof falls and rib spalling (Kamata and Mashimo 2001; Wu, Ohnishi, and Nishiyama, 2004). A typical failure of the so-called “deep inclined rock roadway with weak planes” (DIRRWP) is shown in Figure 1. Severe deformation can be found near the weak plane. In this study, a plane or thin layer of rock/coal parting that can significantly reduce the strength of the surrounding rocks—and thus affect roadway stability—is defined as the weak plane."

Jan 1, 2019

By W. H. Pomroy

Spontaneous combustion fires in deep metal mines, through relatively infrequent, are nonetheless cause for considerable concern because they pose a direct threat to the safety of miners and are quite disruptive to mine operations. They often occur in remote, inactive, or abandoned sectors of a mine where access for firefighting is difficult or impossible. Over half of all noncoal mine fires that last more than 24 hours are caused by spontaneous combustion. The most common means of fire control for spontaneous combustion fires is sealing and/or Flooding the affected zone. This process is never easy, but it is made especially difficult (and hazardous) if the fire grows in size and intensity to the point where underground fire- fighting crews must wear self-contained breathing apparatus owing to mine air contamination. The Bureau of Mines has developed and in-mine tested a mineworthy fire detection system capable of sensing the earliest traces of spontaneous combustion, thus enabling mine personnel to initiate fire control operations before hazardous atmospheres are created. This paper discusses system design within the context of the harsh mine environment, and describes laboratory and in-mine performance tests of prototype equipment.

Jan 1, 1985

By E. Westman

Geographic Information Systems (GIS) are becoming a more commonly used tool for resource estimation as they provide not only a database management platform, but also the graphical capabilities to visualize resource characteristics. Interpolation methods used commonly in these resource studies do not typically provide a quantitative answer to the question: "How accurate is the estimate?" By comparing localized measurements at several locations to the interpolated thickness distribution used in a resource estimate, a quantitative analysis of accuracy can be obtained. The technique is demonstrated with a case study from Central Appalachia.

Jan 1, 1999

By E. J. Wasp

An upsurge of interest in slurry pipelines to move coal from Wyoming, Montana, and Colorado to markets in the southwest, west, midwest and northwest has recently developed. Specific pipelines have been proposed to serve these markets; the routes of these lines are depicted in Exhibit I. It is, therefore, timely to discuss some technical aspects of the terminal facilities for these western coal pipelines. The discussion will be based on experience with the Ohio and Black Mesa pipelines as well as detailed planning and testing for a proposed 1,000-mile system from Wyoming to the middle south area. The economics of the pipeline terminal processes are heavily depend¬ent on site, type of process used, and other specifics of the situation. However, the following approximate breakdown of costs for a 1,000 mile, large capacity pipeline will be useful for orientation purposes. [Water supply 4 Coal cleaning 5 Feed preparation 10 Slurry transportation 72 Dewatering terminal 9 100%]

Jan 1, 1976

New developments in the pipe conveyor and belt are advanced to address the growth in the capacity, length and complexity of pipe conveyor systems. Improved belt construction can offer better stability during horizontal curves and resistance to twist. Low rolling resistance rubber compound can significantly lower the power consumption and belt tension, producing capital and operation cost savings. Dynamic analysis, when used to analyze the conveyor?s starting and stopping behavior, can improve the design and reliability of long overland pipe conveyor systems. For these three aspects, technical backgrounds and field installations as examples are discussed in this paper.

Jan 1, 2012

By F. M. Benavides

This paper presents recent developments in federal environmental regulations, which in the view of the author, affect mining and the mineral processing industries. This is a summary of activities by the administration, congress and regulatory agencies during 1990. The information presented is a recap from material published. The emphasis is given to Air Quality regulations, although other environmental concerns are reviewed.

Jan 1, 1991

By X. Nie

A new one-step process was developed to completely eliminate iron and directly obtain pure Ni, Co, and Cu chloride catholyte from nickel rich matte by low temperature (400 0c) chlorination roasting of Ni, Co, and Cu with HCl and leaching with water (PH 7). The effects of roasting temperature, time, oxygen potential and HCI addition and leaching temperature, pH, H2S04 addition and residue sulphur on the recovery of metals and purity of leaching solution were investigated. More than 99 % of Ni and Co and 95 % of Cu in the matte was directly extracted into the solution while 99.995 % of Fe remained in the residue. The iron concentration in the leaching solution was less than 3.6 X 10-5 mol/L.

Jan 1, 1994

By A. P. Schissler

2013 has seen metals, industrial minerals, and coal all reduce in price due to market and geo-political factors. Many companies are taking write-downs to recalibrate their reserves and have enacted focused cost reduction programs. The public domain includes statements where companies have operating cost reduction goals in the $500 million range. Zero-base staffing & budget analysis is a means to achieve optimal employment and cost levels for a given level of production. The method involves measuring the work to be done similar to Lean. Lean is a method to review each step of production and remove anything that doesn?t add value or is necessary to complete finished goods. Zero-base methodology has been applied to mines worldwide producing realistic and sustainable levels of staffing and costs based on the quantity of work. The objective of this paper is to provide the framework of zero-basing with examples of application.

Feb 23, 2014

By Friedrich Steinhäusler

RADON SOURCES AND CONTROL MEASURES IN THE MINING ENVIRONMENT Most of the contamination of the mine atmosphere by radon 222 is due to radon emanating from solid or fractured ore surfaces of walls, roof and floor. Also radon gas emanates from broken ore either from storage in backfilled mined-out areas as applied in e.g. shrinkage stopping methods or from ore spillage along intake airways mainly due to the use of trackless haulage. To a lesser extent water itself can represent an additional source of radon, which emanates into air from open drainage ditches or seepages along intake airways. The contribution from water can be controlled effectively by isolating the water from the primary intake air system, e.g. by diverting the water through pipes and/or sealing of seepages by grouting. However, control of radon emanating from rock surfaces creates a major technical problem with significant impact on the economic aspects of mining operations, if adequate radiological conditions must be maintained. Basically this can be achieved by suppressing the emanation process itself, confining already emanated radon or by removal of radon from the mine atmosphere. Extensive research has been carried out on the rate of radon emanation as a function of barometric pressure changes (Pohl-Rüling and Pohl, 1969). It could be shown that the radon supply consists of a permanent and variable component. The former results from the surface of the rock and depends mainly on the emanating fraction of its radium 226 content; the latter originates from within the rocks and is a function of the suction effect of decreasing barometric pressure, rock porosity and fissures. The practical application of this barometric pump effect for depressing the rate of radon emanation, e.g. by pressurizing the mine atmosphere, is limited due to high costs for providing a sink for absorption of radon and air as well as lack of permeability in most uranium ore bodies (Schroeder et al., 1966). Mine air cleaning by removal of radon can be achieved with the use of cryogenic methods, chemical removal, adsorption into charcoal beds, use of a gas centrifuge or general ventilation techniques. Technical problems have so far prevented the application of any of these methods other than ventilation. It is common practice to use the age-of-air concept, i.e. fresh air is delivered to the worker as directly as possible and removed quickly afterwards thereby maintaining the air "young". Engineering principles for quantity distribution of air through underground working areas are straightforward for general mining situations where radon constitutes an environmental contamination problem. However, in cases of high uranium ore content this concept may result in high costs with regard to installation and energy requirements for effecting both frequent air changes as well as sufficient heating of the air in cold seasons. Taking into account that the investment in ventilation systems is a major cofactor for the overall ore production costs this can be a limiting and decisive component in the assessment of the economic feasibility of specific mining operations and mineral reserves in general. Effective control of the radon flux from the rock surface prevents the initial contamination of the mine air with radon directly at the source. A radon diffusion barrier for practical application in mining requirements should fulfill the following requirements: - reduction of radon emanation rate by at least an order of magnitude - high mechanical strength - ease of sealant application onto surface to be coated - water resistant - low fire hazard - resistant to temperature changes encountered in mines - high cost efficiency in relation to exposure reduction achieved (direct and indirect costs) - low degree of maintenance. In the past several materials have been tested as sealants for controlling the emanation of radon from surfaces of rock and building materials. Epoxy paints reduce radon emanation rate only by a factor of 2 to 6 (Auxier et al., 1974; Eichholz et al., 1980; Keith Consulting Engineers, 1980). Although it is possible to prevent the escape of more than 99 % of the radon to the environment with gel seals over 80 mm thick (Bedrosian et al., 1974), practical applicability is very limited. Multilayer coatings of epoxy resins with various additives require meticulous preparation and flawless application of seamless four-layer coatings in four days to impede radon diffusion (Culot et al., 1976), otherwise results from this method have not been totally satisfactory (Leung, 1978). Aluminium foil laminated with polyethylene and paper on each side is under test as radon barrier but results are not available yet (Ericson, 1980). However, this method has the inherent disadvantage that possible malfunctioning electrical installations can cause fire or electrical shock through the sealant. Polyurethane foam coatings have been used on stoppings as very effective sealants. It does, however, represent a potential danger of spontaneous ignition and it is expensive (Rock, 1975). Thus, there is still need for a material which has similar properties as outlined above. In the following results are reported from investigations on the suitability of various materials as radon diffusion barriers.

Jan 1, 1981

By Andrea Biagi, Elisa Comis, Gianluca Bella, Enrico De Panicis, Guido Barbieri, Matteo Giani

The Sotra Link Project is a major infrastructure project in Norway involving the design, construction, financing and maintenance of several underground and surface structures between Sotra island and the city of Bergen, among them 23 tunnel portals, 12.5 km of tunnels and a 900 m long suspension bridge. This paper describes the benefits in applying a Building Information Modelling (BIM) approach to tunnelling, from Early Design to the Detail Design Phase. The BIM application to the Sotra Link Project resulted in several improvements, such as efficient handling of clashes and inconsistencies, deeper understanding of effective design choices (reduction of errors), more efficient communication between designers, enhanced control of project quantities and costs. The advantages of the BIM approach during the ongoing Construction Phase are also explained.

Jun 23, 2024

By A. J. Kwitowski

Remote control for mining machines ordinarily means the operator is not seated on the machine, but is located within direct view of the machine and work area Thus, remote control operators are exposed to the hazards of roof/rib falls and dust/methane explosions. The U.S. Bureau of Mines has developed a method to disassociate remote operators from these hazards. Off-board, computer-based "tele-operational" systems are utilized that station the operators one-hundred meters or more distant from the working faces. Details are provided for tele-operated systems for thin-seam extraction and haulage equipment in highwall and deep, room-and-pillar coal mines.

Jan 1, 1992

By Simon Strong, Tim Brown, Luis Ignacio Sanz Vivanco

"One of the most significant technical and practical challenges facing the tunnel construction team on the Legacy Way road tunnel project in Brisbane, Australia was how to erect the pre-stressed precast concrete slabs to form the smoke duct in the tunnel boring machine (TBM) tunnels. An essential part of the tunnel ventilation system, the smoke duct, extends the full length of the 4.6km long twin, two lane tunnels. The vast majority of the tunnels (approx. 4.3km) were constructed using two 12.4m diameter double shield TBMs. The refurbished Herrenknecht machines broke several world records on the way to completing the tunnel excavation works in just over nine months. With the excavation complete the focus turned to solving the complex civil tunnel fit out challenges. A key component of the civil fit out of the tunnels was constructing the smoke duct in the TBM tunnels which was designed as a precast solution. The slabs which each measure 8.62m long by 2.0m wide by 200mm thick and weigh close to 9 tonne need to be erected above cast in situ corbels whilst other tunnel finishing works continue. The space proofing clearance offered by the design to the support corbels below and the precast segmental lining above was in the order of only 100mm. This paper details the events of how the Transcity JV tunnel fit out team, comprising some of Europe and Australia’s leading tunnel construction specialists, drew upon the global strengths of the existing JV member companies and the global reach of leading TBM manufacturer Herrenknecht to develop an innovative system to solve this challenging problem. This globetrotting story, which starts in Australia, visits Europe and mainland China before returning to Brisbane where it all began."

Jan 1, 2016