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By JOHN R. HEBERGER, MAHIYAR F. NASARWANJI, Jonisha P. Pollard, Lydia M. Kocher

nt in the mining industry, and identifying factors associated with these injuries is critical for developing prevention efforts. This study identifies nonfatal injury incidence rates, nature of injury, work activities, glove usage, and sources of hand and finger injuries in the U.S. mining industry, as reported to the Mine Safety and Health Administration (MSHA) from 2011 to 2017. Hand and finger injuries occur at a rate of 6.53 per 1,000 full-time employees, which is nearly double the rate of the next highest affected body part, the back. Most of the hand and finger injuries were classified as cuts/lacerations/punctures (53 percent) followed by bone fractures/chips (26 percent). Materials handling and maintenance/repair were common activities at the time of the incident with miscellaneous metals — such as pipe, wire and guarding — and hand tools as the primary sources of hand and finger injury. Although the information on glove use was limited, leather gloves were most often worn when an injury occurred.

By Ted DePooter, Mun Wei Leong, Chad Frederick

Downtown Bellevue Tunnel (DBT) is part of Sound Transit’s $3.7 billion, 14-mile light rail transit system from downtown Seattle, across Lake Washington, to the cities of Mercer Island, Bellevue, and Redmond. The tunnel was the first Sound Transit East Link project and posed significant construction risk. This paper discusses implementation of design changes to the soft ground tunneling method, implementation of several technologies such as the use macro-synthetic fiber initial shotcrete lining, use of spray-applied waterproofing, and use of shotcrete for the final tunnel lining. These efforts allowed for significant time and cost savings to the project.

Jun 13, 2021

By L. J. Habegger

This paper considers the potential water quality impacts of future energy scenarios which project an approximate doubling of coal utilization from 1975 to 1985. The major impacts estimated for coal extraction are related to effluents from unregulated activities (reclaimed areas prior to stable vegetation) and pollutants (e.g., metals and ammonia). Where applicable, the EPA effluent guidelines to be in effect by 1983 reduce the impact of individual sources to low levels. For example, total suspended solids and acidic discharges are to be regulated to levels generally below recommended water quality standards for receiving streams. However, implementation of these guidelines, particularly for coal extraction, has not been demonstrated on a wide scale. Water quality is not expected to be a major constraining factor for increasing capacity of coal fired utility and industrial boilers. Water quality control has not been demonstrated on a commercial scale for coal conversion to synfuels, but adequate control technologies appear to be feasible.

Jan 1, 1978

By K. J. Shoop

Coal-fired power plants in the U. S. produce approximately 20 million metric tons of Hue-gas desulfurization sludge every year. The sludge mainly consists of calcium sulfite and calcium sulfate. This can be converted to synthetic gypsum, which in principle could be a marketable commodity. However, many Hue-gas scrubbers produce sludges that do not meet the quality requirements of the gypsum industry, and so their sludges must be landfilled as a waste. If a suitable method can be developed for removing certain objectionable impurities from the sludge, it will then be possible to market the material instead of landfilling it. A sludge from a natural-oxidation scrubber was characterized, and the main contaminant was found to be calcium carbonate from unreacted limestone. Based on the particle size and the characteristics of the material, froth flotation was considered as a method for purifying the material. Since no flotation studies have ever been carried out to separate calcium carbonate particles from calcium sulfite or calcium sulfate particles, it was first necessary to select a suitable collecting reagent. Based on Zeta-potential studies, the most suitable reagent was found to be an octadecylamine-octadecylguanidine complex. Results are presented for flotation of calcium carbonate from scrubber sludge using this reagent, in a reverse-flotation process. The best results were obtained when the sludge was first pre-cleaned using a water-only cyclone to remove unfloatable coarse limestone, followed by froth flotation to remove fine limestone.

Jan 1, 1998

By Alexander Karim

This paper reviews the growth pattern in bauxite and alumina production, and primary aluminum smelting through 1980. Because the alumina and primary metal are intermediate products of the major integrated aluminum companies, it is not possible to determine their production costs. The costs indicated in this paper are order of magnitude costs based on published figures and the market price of these products. The conclusions in this paper indicate the general pattern of growth in the aluminum industry and are not meant to be a substitute for the feasibility and economic studies that are needed for individual bauxite mining, alumina refining and aluminum smelting projects.

Jan 1, 1968

By P. J. Cook

Comminution is one of the fundamentals of mineral processing, requiring large expenditures to be made on capital equipment, installation, power and maintenance. The trend toward lower grades and higher operating costs, mean mining operations are becoming increasingly marginal. The challenge is to improve and more importantly, utilize crushing and milling technologies that provide for reduced capital and operating costs whilst providing increased unit efficiencies. The Svedala Barmac Autogenous Crushing Mill presents such an opportunity by providing many of the cost savings and production increases required by its ability to produce a finer mill feed size and realize reduced energy consumption. This paper briefly describes the operation of the Svedala Barmac Autogenous Crushing Mill and reviews its benefits towards improving the efficiency of crushing and milling operations.

Jan 1, 1999

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

By Kai Wang, Chao Xu, Qiang Fu, Tong Yang, Chunyu Zhao, Wei Zhao

The stress of a coal seam is an important factor that affects the permeability of the coal seam and then affects the coalbed methane (CBM) drainage. In China, adjacent coal seam mining is an important method to reduce stress, which increases the permeability of the coal seam. However, in the process of mining adjacent coal seams, many coal pillars remain, which causes stress concentrations and results in a decrease in permeability. Therefore, it is important to study the influence of coal pillars on the stress of adjacent layers and its distribution and evolution in the floor rock. This paper took the Shendong Baode Coal Mine as a case study and investigated the influence of the coal pillar on the stress and permeability of coal seam #11. The results show that under a coal pillar, the relationship between the vertical stress of different floor depths and the width of the coal pillar can be divided into a negative correlation zone, transition zone, and positive correlation zone. The change in the coal pillar width does not affect the pressure relief range or the degree of pressure relief in the adjacent coal seams below the goaf. The field measurements show that after the mining of panel #81,505, the permeability coefficient of coal seam #11 under the goaf increased from 0.1434 to 26.3545 m2/( MPa2*d), increasing 182.7 times, and the drainage mixing volume of boreholes #1 and #2 increased from 1.24 to 1.52 m3/ min. While the permeability coefficient of coal seam #11 from 12.5 m in the coal pillar has only increased by 2.6 times, the drainage volume of boreholes #3 and #4 did not change significantly.

Nov 19, 2022

By C. J. Pritchard

Controlled recirculation of ventilation air in underground metal and nonmetal mines has the potential to improve airflow and the health and safety of miners when implemented properly. Previous research by Robinson, Marks, Cecala and others concluded that the success of a district recirculation system is predicated upon an adequate supply of fresh air and the use of a reliable monitoring system for safe operation. This recent research also showed that contaminant levels will not exceed pre-recirculation levels, and that district recirculation can improve the dilution of face contaminants, especially methane gas. To illustrate the process of implementing controlled recirculation and also to promote and give guidance to mine operators in consideration of this tool to improve mine airflow, Office of Mine Safety and Health Research (OMSHR) researchers acquired baseline airflow and contaminant data from a multi-level room-and-pillar nonmetal mine and used commercial ventilation network software to simulate base case conditions and recirculation of mine air. Mine return air baseline contaminants of dust and diesel particulate matter were at lower levels than intake air, providing the potential for improved face air quality. A ventilation model implementing controlled recirculation was developed and analyzed, showing an increase in air quantity at the face, improved intake air quality, and contaminant exposure levels below those set by statutory requirements. These results, along with conclusions reached by previous researchers, provide the basis for examining the safe and effective implementation of controlled recirculation in metal and nonmetal underground mines using this mine as an example.

By M. J. Allan, D. J. Barratt

This paper reviews current testing methods for sizing autogenom and semiautogenom mills in the North American context with comments on the necessity for test work and requirements for different circuits and equipment selection. The economics of testing and the value received are discussed.

Jan 1, 1987

By A. Noble

"A supply of sustainably sourced rare earth elements (REEs) is critical for several high-tech industries, renewable energy technologies, and defense applications. Recent studies have shown that REEs exist in coal and coal combustion byproducts at elevated concentrations and in quantities that could meet domestic demand. Despite these promising findings, declines in rare earth prices, volatile commodity markets, and challenging geo-metallurgical conditions have jeopardized this potentially valuable REE resource. While the dilute REE concentrations inherently necessitate low-cost separation technologies, the ultimately operating cost threshold for economic extraction must be based on commodity price projections and market demand. In this paper, the micro-pricing principle is used to develop a rigorous economic model assessing the inherent value of REEs in coal materials. This model is based upon basket pricing of individual elemental oxides, and elemental distributions of coal samples from various basins. These results may be used to assess the economic viability of potential REE concentration and refining technologies INTRODUCTION Recent efforts by US Department of Energy (DOE) and the National Energy Technology Laboratory (NETL) have suggested that rare earth elements (REEs) may exist in coal and coal byproducts at concentrations suitable for economic extraction and processing. While the knowledge of REE occurrence in coal material dates back over 50 years, recent supply restrictions and material criticality considerations have prompted a national interest to establish a sustainable domestic supply of REEs. REEs are not “rare” in the sense of crustal abundance; however, few natural processes lead to concentrated ore deposits. As a result, the elevated concentrations found in coal material may provide a potentially promising resource for these materials. While the term “rare earths” is often used to describe a singular concept, the 15 rare earth elements actually have varying and sometimes contrasting scarcity and cost profiles. Various authors have proposed classification systems to provide information on REE criticality (e.g. Seredin and Dai, 2012, Zhang et al., 2015). The most straightforward classification is provided on the basis of geochemistry with designations for “light”, “medium” and “heavy” rare earths. Light rare earths (those to the left of the periodic table: Ce, Pr, Nd, and Sm) tend to be more common and less valuable when compared to their medium (Eu, Gd, Tb, Dy, and Y) and heavy (Ho, Er, Tm, Yb, and Lu) counterparts. While light rare earths are often found in traditional ore deposits at economic concentrations, the heavier rare earths are almost exclusively found as ion-absorbed clays (Seredin and Dai, 2012)."

Jan 1, 2016

By I. Mikov

Established in the 60-ies, the Zlatna Panega quarry is a cement raw materials quarry supplying 95% of the needs of the Zlatna Panega Cement Plant with limestone, marl and other silica-aluminates. The two major types of raw materials are formed by accordingly dipping strata of Upper Jurassic limestones and lower Cretaceous marls. Between them there is a ?transition-zone? or ?contact-zone? of a high-silica content layer, about 5-m thick, defined as ?flint? by investigations including spot sampling throughout the quarry. For many years this ?contact-zone? layer was neglected due its negligible thickness. Further, with the increasing demand on the quality of the raw materials feed to the Plant and the focus on variability of the chemical and mineralogical components, it was decided not to mine any of the parts of the quarry contaminated by this material, for about three years. The latter had an impact on the availability of operating benches that could result in a substantial decrease in the total recoverable re-serves of Zlatna Panega, particularly with respect to marls. There were considerations for resorting to a partial, selective excavation of the quarry pit with a reduced lifetime for the lime-stones and re-opening of an other (currently in-active) marl quarry at a distance of 6 Km from the Plant. The Quarry Team of the Zlatna Panega quarry was assigned to study the problem. The ?contact? layer was duly confirmed with systematic geological (including mineralogy) studies, statistical analysis of available data, surface sampling and shallow exploration drills, resulted into distinguishing a third type of reserves and their credible subsurface delineation by means of geological 3-D modeling and quarry design. A new quarry design was finally elaborated with a view of providing flexibility in mining, utilization of the total volume of all available reserves and maximizing the mine life of Zlatna Panega quarry. An industrial test took place in December 2005, by using the contaminated parts of the quarry (co-mining of the ?contact-zone? materials) at a contribution of 15-20% in the raw materials mix, as dictated by their contribution in the total recoverable resources of the quarry. The purpose was to investigate the viability of this solution ? in line with improved quarry planning ? without compromising the quality of cement production and the efficiency of Plant Operations. Results were overall successful.

Jan 1, 2006

By Ahmet Tezcan, Zeki M. Dogan, Yalçin Kaytaz

Autogenous grinding in Turkey was first applied to quartzite where the mill is grate discharge type with an internal diameter of 2.99 m, having a length of 3.20 m and a capacity of as to 11.0 tons per hour. The second autogenous grinding was applied to a copper ore at Murgul Cakmakkaya Flotation plant of (KBI) Black Sea Copper Works having three mills 26 feet in diameter and 10 feet in length in close circuit with hydrocyclones. Recently, alterations were made in grinding circust by adding pebble mills. Furthermore, rubber liners and lifter bars were introduced pebble extractor and classifier were new features in the primary mills and circulating load was reduced by 20-50 tons per hour. At the end of these charges, capacity of each mill line was increased to 48 tons per hour with a full capacity of more than 9000 tons per day. Thirdly, autogenous grinding has been executed successfully on the slags of Samsun Smelting Plant of (KBI) Black Sea Copper Works with a mill of 20 feet in diameter and 6 feet on length having pebble mill following autogenous grinding.

Jan 1, 1992

By Paul R. Wieber

This paper describes the U. S. Energy Research and Development Administration's (ERDA) program to develop in situ coal conversion processes, especially gasification, he potential of this technology, the technical directions being explored, and the program strategy to carry the process concepts toward commercialization are emphasized. The geographic location of the U. S. coal resources and a market analysis are described. Commercially successful in situ coal processes could add over a trillion tons of coal to the U. S. coal reserves. The economics of these processes is compared with surface gasification independent studies show this process to be 25Z cheaper than surface gasification for Western coals. The major projects are briefly described. The Linked Vertical Well process is in the lost advanced stage and shows great promise. The last test produced a low-Btu gas averaging 171 Btu per standard cubic foot for average pro¬duction rates of 5.5 million standard cubic feet per day. The other projects are Packed Bed, Longwall Generator, and Steeply Dipping Beds.

Jan 1, 1977

By David L. Giles

The Lime Creek* ore body in northwestern British Columbia is one of the few commercial primary stockwork-type molybdenite deposits in North America. Others include the Climax, Urad-Henderson, Questa, and Endako ore bodies. They are mined on a low grade-high tonnage basis, and are open pit operations except for Climax and Urad-Henderson. Much recent geochemical research on both porphyry copper and stockwork MoS2 deposits has been concerned with dating of micas related to the mineralization and associated igneous rocks. The results appear to show that mineralization and the predominant magmatic events of the deposit are indistinguishable in age (1-5), except where dating has been in sufficient detail to resolve the analytical overlap (6). At Lime Creek, geologic information shows that the Main granodiorite, the major intrusive and dominant host rock for MoS2 mineralization, was emplaced and had solidified sometime prior to the introduction of MoS2. The first MoS2 episode is intimately related to localized bodies of kalialaskite which clearly intrude the older stock. K-Ar dating was undertaken to clarify the age relations between Lime Creek plutonism and the apparently younger hydrothermal event that began with kalialaskite.

Jan 1, 1975

By Verya Nasri, Behrouz Esmaeilkhanian, Mohammad Motallebi

Réseau Express Métropolitain (REM) is the new Light Rail Transit (LRT) network of Montreal, Canada. This new LRT network uses a century-old Mont Royal Tunnel (MRT) to connect Downtown Montreal to the north side of the Island of Montreal by passing through Mount Royal Mountain. This railway double track horseshoe tunnel is approximately 5 km (3.1 mi.) long, 8.8 m (29 ft.) wide and 5.5 m (18 ft.) high, with a constant 0.6% grade. Due to different geological characteristics of the surrounding ground, varied from hard rock to soft soil, different cross sections and excavation methods were adopted for construction of this tunnel. In order to use MRT in the modern transit system, the tunnel needed to be inspected, rehabilitated and be compliant to the recent safety standards. This paper presents a summary of history and characteristics of the existing tunnel plus the implemented steps to upgrade the tunnel. It includes the details of the structural inspection and rehabilitation methods of the tunnel. Further, this paper summarizes the procedures for the space proong, construction of the separation center wall, and the tunnel enlargement. It also describes parts of complications encountered during the construction and solutions implemented to tackle these issues.

Jun 23, 2024

By Feng Liu

"With seven new applications for plans of work for exploration in the international Seabed Area approved by the Council during its twentieth session of the International Seabed Authority, 26 total approvals have been made by the Council up to date. Among them, three contracts were made with COMRA. On 8 August 2014, China Minmetals Corporation submitted another application to the Authority for approval of a plan of work for exploration for polymetallic nodules in the Area, which is also sponsored by the Government of the People’s Republic of China.China is one of the main contributors to the international seabed regime. The Presentation will describe China’s activities in the Area, such as exploration, technology development, environmental protection and policy making.JIAOLONG is a submersible with capacity of 7000 meters. JIAOLONG’s sea trials were carefully made in 4 years, from 2009 through 2012 and it successfully dove to a depth of 7062m in June 2012 at Mariana trench. A so called "Test Application Phase" started thereafter, and is planned to last for 3-4 years. Two cruises and 4 legs have already been made since then. A wide-range of findings were obtained during dives in South China Sea, and in COMRA’s Exploration Contract Areas for polymetallic nodules and cobalt-rich ferromanganese crusts. This presentation will reveal the colorful findings."

Sep 1, 2014

By J. Sidhom, W. Fourie

"As the mining industry continues to face difficult challenges the need to persistently focus on productivity and utilization of labor and equipment costs will intensify. With these challenges in mind, Joy Global is helping to bring mining performance and analytics to the next level. By evaluating underground haulage, a significant component of the Room and Pillar mining value stream, variables have been identified and sensitivities have been performed to show opportunities to balance and streamline throughput. As a result of applying operational excellence tools to the mining environment, Joy Global is seeking to optimize mining performances by limiting waste, simplifying the process, increasing productivity and machine utilization, as well as removing workers from harm’s way. These days it’s not enough to work harder; mines have to work smarter. Improving efficiency, reducing costs, increasing safety: these are no longer ‘nice to haves’, they are ‘must haves’. Starting with the best products and the right people is a first step, but then what? How do mines take their operations from just OK to being a top performer? By using operational excellence principles aimed at eliminating waste, simplifying processes, automating where possible and removing people from harm’s way. The fundamentals of operational excellence (OpEx) are based upon the DMAIC process, which stands for define, measure, analyze, improve and control. DMAIC is an improvement cycle that helps with, for example, haulage optimization by: defining the issues and problems in the process as well as the areas of improvement; measuring and collecting mining operational data by time study and equipment monitoring system; analyzing through sensitivities and production modelling to determine root causes; then improving the performance and controlling the operation. Joy Global uses Joy OpEx or ‘lean’ principles inside its organization to drive efficiency, but it also helps its customers employ them to achieve new levels of productivity and safety. These same principles can be applied in most situations to streamline processes, improve operations and deliver value. As applied to mining, OpEx is seen as moving the needle on value creation by first identifying the value stream, then analyzing the areas that are not optimized. Once defined, these areas are ‘designed out’ of operational processes to create an automated operational flow. At a US coal mine, Joy Global was brought in to apply Joy OpEx principles to optimize mining and haulage to improve productivity and reduce costs. This multi-phase process started by defining the existing systems challenges to start finding areas for improvement."

Jan 1, 2017

By T. W. West

During the design and construction of a coal preparation facility, there are many items that can cause serious problems if not properly handled in the early stages of a project. These problems can be a detriment to smooth owner/ contractor relationships, the designing of a flow sheet, the selection of equipment, the design of the facility, the maintenance of schedule and budget, and a smooth start-up. It is the purpose of this presentation to identify some of these problems and to suggest steps that can be taken to reduce or eliminate their impact.

Jan 1, 1977

By S. C. Gaillard

Tailings are made of ground rock that is left over from removing valuable minerals. The tailings are usually fine particles that cause environmental issues for storage and disposal. Disposal of tailings is a growing concern, as more tailings are produced from the increasing demand for mined material (ITRC, 2008). This project proposes a way to convert the mine waste to a useful product. Tailings were selected from a South Carolina crushed stone quarry, the products of which are used for road beds, sidewalks, asphalt and driveways. These tailings were processed to generate synthetic aggregates for construction applications. The synthetic aggregate creates a product that could be used for many purposes, including aggregate for sidewalks, driveways, roads and building materials. Testing methods followed the North Carolina Department of Transportation (NCDOT) guidelines for physical testing of coarse natural aggregate, which are sieve analysis, Los Angeles abrasion, absorption, specific gravity and soundness test. The synthetic aggregate produced passed all tests for NCDOT and, in some instances, rated better than a natural aggregate. Using the tailings from the crushed stone and mining industry would convert the waste into a valuable, marketable product.

Jan 1, 2013