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Gangue-cemented paste backfill (GCPB), is a well-established green mining technology and significantly improves the recovery rate of mineral resources, prevents mine dynamic disasters, reduces surface subsidence, and consumes a considerable amount of solid waste. The addition of an early strength agent as an additive in cement-based materials provides several security, technical, and economic advantages. In this study, the early strength agent on the early age (3, 7 and 28 days) strength of GCPB is evaluated experimentally. The GCPB specimens have an initial sodium sulfate early strength agent concentration of 0%, 1%, 2%, 3%, and 4%, and the obtained samples were analyzed by testing for uniaxial compressive strength (UCS) and scanning electron microscopy (SEM). The test results show that the UCS of the GCPB specimens with sodium sulfate is much higher than that of the blank specimens. When cured for 3 days and 7 days, the strength of GCPB with 2% sodium sulfate increased the most, by 131% and 116% respectively. When cured for 28 days, the strength of GCPB with 1% sodium sulfate increased by 135%. Scanning electron microscopy (SEM) results showed that the GCPB with 1% and 2% sodium sulfate had better internal structure compactness, thicker acicular crystals, and more flocs. As a kind of early strength agent, sodium sulfate can react with calcium hydroxide to generate calcium dihydrate sulfate and then react with calcium aluminate; the hydration product (C3A) quickly generates calcium sulfoaluminate hydrate (AFt) needle-shaped crystals, forming an early skeleton and improving the early strength.

Jan 7, 2020

The Department of Health and Human Services (HHS), National Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health Research (OMSHR), with the assistance of cooperating underground mining operations and state agencies, has conducted research exploring devices and technologies that could be used to assist miners navigating through smoke and dust resulting from a fire or explosion. Recent events in mines confirm that smoke and dust can enter and contaminate mine escapeways creating an atmosphere with severely reduced visibility. This reduced visibility results in substantially increased escape times, possible disorientation or confusion, and increased stress levels, and may prevent evacuation altogether. Tools or devices that assist miners in navigating through smoke-filled areas void of lifelines could make the difference in successful escape from the mine. This paper presents the results of OMSHR research to identify and evaluate tools and devices that could provide meaningful information to evacuating miners in areas with limited visibility and without the benefit of a lifeline.

Jan 1, 2011

By Duane A. Smith

Horace Tabor. No 19th century Colorado mining man is better known but, unfortunately, probably less understood. He is little appreciated for his significant contributions to the industry and the state. A century ago, Tabor was headline news. The legend today, however, has become so all pervasive and so interwoven with fact that the two are hard to separate. For example, he never told Baby Doe on his death bed to hang on to the Matchless mine. Yet this has emerged as staple Tabor fare. So much attention has been focused on his matrimonial triangle that it overshadows the man. Symbol of mining's reward Tabor traveled west in the 1859 Pike's Peak gold rush. In the next generation, he came to symbolize the rewards mining might lavish on an individual. The Leadville Daily Herald (Sept. 10, 1882) could write, without exaggeration, that "the extent which the mining industry of Colorado is under obligation to Tabor cannot be easily estimated - what he has done for Leadville and Denver is patent to all." It had not come easily, nor had Tabor started out a success. His early placer mining at Payne's Bar, near present-day Idaho Springs, CO, had turned no fortune. So in 1860, he, his wife Augusta, and son went south to Colorado City, then over Ute Pass and up the Arkansas Valley to Oro City. Arriving soon after the initial discovery, Tabor staked a good claim. With a sharp eye, he and Augusta broadened their base by establishing a store. Both mining and business would pay dividends in the following years. By the season's end, though, Oro City was already declining. Always on the lookout for a richer district, Tabor and his family moved the next year across the mountains to promising Buckskin Joe. The familiar pattern followed, with the store and post office being the center of their attention. Mining investment and management now replaced the earlier physical panning and sluice operating. Seven years later, the Tabors abandoned Buckskin Joe and returned to Oro City. It had moved up California Gulch to be near the district's best mine, the Printer Boy. Middle class was not enough Middle class respectability, plus a steady income, was the Tabor's by the 1870s; fine as far as it went. But it proved far from the fortune Horace had always been seeking. Oro City languished in the backwash of Colorado mining and Tabor seemed like many men who had drifted around the Territory following the ebb and flow of mining. His faithful wife Augusta had been a steady factor in the success the family achieved. She helped year after year to operate the store and post office. Not simply the happy-go-lucky individual he has often been portrayed, Tabor was a hard working businessman/mine owner. An R. G. Dun and Company agent evaluated him in 1876 "Net worth $23,200. Is a very shrewd businessman and not liable to lose money, has a good chance to make money as he had no competition." Leadville: Tabor's silverlined-fortune After all those years on the Colorado mining frontier, in 1877, Lake County's wealthiest and most respected merchant made another move. It was short in distance, only 4 km (2.5 miles) down California Gulch, then a little north to a new mining camp. This new camp, soon named Leadville, gave birth to the Tabor fortune and legend. Middle-aged (Horace was 47), the Tabors once more set up their general store and found themselves in the midst of the open¬ing of a new district. This time silver beckoned and not the gold that had brought them West 18 years before.

Jan 1, 1989

By Ben Hayes, Michael Ryjevski

The Palm Jumeirah is the smallest of the three Palm Islands (Palm Jumeirah, Palm Jebel Ali and Palm Deira). It is located on the Jumeirah coastal area of the emirate of Dubai, in the United Arab Emirates (UAE). The unique man made island is built in the shape of a date palm tree and consists of a trunk, a crown, 17 fronds and a surrounding crescent island that will form a breakwater. The Jumeirah Palm Island is primarily are treat and residential area for living, relaxation, and leisure. It will contain themed boutique hotels, three types of villas, shoreline apartment buildings, beaches, marinas, restaurants, cafes and a variety of retail outlets.

Jan 1, 2007

By R. Fernando

"The Office of Mine Safety and Health Research (NIOSH-OMSHR) currently is leading an effort in the development of the next-generation self-escape apparatus as part of the research imperative directed by the MINER Act of 2006. A multifaceted contract program over the past 3 years delivered key components and base breathing modules to form the basis for developing backpack and vest-style versions of dockable self-contained (closed-circuit) self-escape respirators with hoods (CCMERs). This paper outlines the current status in developing the CCMER that incorporates a docking and switch-over valve (DSOV) for seamless transfer from one breathing device to another, and a hood with an inner mask and speech diaphragm (HMC) for ease of donning, ease of use, and communication ability. Three versions of the CCMER are being pursued, namely: the CCMER-B, which can be worn as a backpack and incorporates the features of a miner’s belt; the CCMER-V, which is worn similar to a miner’s vest and attaches to a miner’s belt; and the CCMER-C, a breathing module cached along the escape route that can be docked to the -B and -V versions. Human factors considerations are a key element in the CCMER design, as it is to be continually worn by the miner while underground, and must be readily accessible for deployment when needed. The CCMERs are designed to be capable of being certified to 42 CFR part 84 standards, including sub-part O for mine use, and to meet MSHA permissibility regulations for use in underground mines. They are sized for sufficient oxygen capacities (Cap 2 and Cap 3 as defined in sub-part O) to yield a duration that is of practical use in a mine escape scenario. INTRODUCTION The National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) is leading the development of self-escape apparatuses to provide breathing gas to mining personnel operating in the event of an emergency in various capacities underground in environments containing hazardous gas components. The Mine Improvement and New Emergency Response Act of 2006 (also known as the MINER Act) and input from the mining community called for the need to move Self-Contained Self-Rescuer (SCSR) technology to a next-generation status. In response to this need, NIOSH’s Office of Mine Safety and Health Research (OMSHR) established a strategic plan to develop key components and devices with help from external experts knowledgeable in breathing apparatus designs. The US Navy was identified as a key expert in this field through its extensive experience in diving apparatus and life support systems, and development work commenced through Inter-Agency Agreements with OMSHR. A contracts program was also launched with industry experts specializing in this field. This paper outlines the current status in developing the Next-Generation Closed-Circuit Mine Escape Respirators (CCMERs) that could be used for surviving and escaping from a mine following an emergency that renders the mine atmosphere irrespirable."

Jan 1, 2016

By J. A. Cole

The mill project at Lone Tree was commissioned in October, 1993, followed by the commissioning of the autoclave pressure oxidation circuit in February, 1994. Discussion of the first year of milling operations at Lone Tree is presented. The mill is currently operating above the design rate of 2,267 mt/d (2,500 st/d). Both phases of the start-up were essentially trouble free. The few problems that were encountered and the respective solutions are addressed.

Jan 1, 1995

By O. E. Wheeler

The use of the walking dragline as a stripping tool has increased dramatically in the past two decades. The reasons for its increased popularity and some historical background on its introduction into the mines are given in a recent paper by Learmont. (l)* The history need not be recounted here except to show the trend to longer booms which has accompanied the growth in machine size. Figure 1 shows the change in maximum operating radius on Bucyrus-Erie machines which has occurred over the years and Figure 2 shows the corresponding change in maximum boom lengths. Reference 1 also presents some of the reasons for expecting this trend to longer booms to continue. There are many design parameters affected by the increase in boom lengths; swing power, hoist and drag rope lengths, and drum capacity, to list just a few. The purpose of this paper is to discuss only the structural implications of using longer booms. As in the design of any structure, the various facets of boom design are interrelated and a process of optimization between them must be worked out either by evolution or by conscious iterative effort. The decisions we have reached about such things as material selection, structural arrangement, and applicable criteria, have not come into being overnight but represent instead many years of design experience and a fair amount of recent concentrated analytical effort. In the following pages an attempt will be made to first, state those decisions, second, explain how we arrived at that particular result; and third, describe what we expect future developments to be which might influence us to change those decisions.

Jan 1, 1976

By Ching L. Wu, Joseph Penzien

An analytical procedure is presented for evaluating the stresses in linings of bored tunnels caused by kinematic soil-lining interaction. Three cases of interaction as produced by the following conditions are treated: (1) relaxation of in situ soil stresses near a lining following its installation; (2) overburden pressure at the soil surface; and (3) free-field soil response resulting from an earthquake. Non-dimensional formulas and graphs resulting from parametric studies are presented for practical tunnel design applications. The procedure is applied separately to a steel lining and a concrete lining for a site located at the lower end of Market Street in San Francisco through which a BART (Bay Area Rapid Transit)tunnel passes.

Jan 1, 1997

By K. S. Mortensen

The softwall mining system is a novel, new method of mining mineral deposits in soft, shallow, nonrock ground conditions. This method can mine the ore layer without substantially disturbing the existing overburden. The softwall mining system consists of machinery that is hydraulically controlled and powered, that can be buried (or used on the surface) to extract the ore or mineral from a layered deposit. The method is essentially an application of the longwall mining concept, modified for loose overburden and ore conditions, combined with hydraulic mining.

Jan 1, 2003

By Eric M. Hill, Daniel E. Walsh, Hsing K. Lin, John T. Hollow

The Fort Knox Mine is located in Alaska’s interior where the average ambient air temperatures range from -24°C in January to 16°C in July. The mill processes a free milling gold ore utilizing both a gravity recovery circuit and conventional cyanide leach/carbon-in-pulp circuits. Plant slurry temperature cycles seasonally and allows for a unique opportunity to measure the impact temperature has on gold leach kinetics, carbon adsorption efficiency and cyanide destruction reactions. Mathematical models have been developed to accurately predict actual mill performance. This paper describes the development of the models and presents data that allow for a better understanding of the impact of circuit operating temperature on process efficiencies.

Jan 1, 2005

By D. Brosnahan, J. Gathje

Newmont Metallurgical Services (NMS) recently acquired a Scanning Electron Microscope (SEM) with a JKMRC/FEI Mineral Liberation Analyzer (MLA). With the MLA software package, raw particle image and X-ray data can be converted into particle mineral maps and bulk and liberation data can then be calculated for minerals of interest. This type of quantitative mineralogical data can then be used for a wide variety of applications. Ore characterization with MLA can be carried out for existing or processing plants in development. MLA characterization of laboratory test products provides valuable liberation information that assists the research metallurgist in better planning and developing process treatment options for various ore types. This paper describes the use of MLA characterization in a copper flotation test program where the use of various testing options for arsenic depression was being evaluated.

Jan 1, 2007

By D. L. Murr, J. R. Jensen

Testing was conducted on a Minnesota Iron Ore concentrate with Cook Clay as a binder using compressive sheer mixing to enhance the performance of the agglomeration mechanism. The testing was conducted on a bench scale at the Midland Research Center the summer of 2004. Results of the test program will be presented that shows the impact of compressive sheer mixing had on the strength achieve in a green ball.

Jan 1, 2006

By Richard Weinstein, Richard Snoby

There are many advantages to upgrading coal with dry jigging technology. The most obvious is the lack of process water, which eliminates the need for fines dewatering and slurry confinement. Dry jigging eliminates the clean coal moisture penalty associated with wet processing. Particulate emissions are virtually nonexistent due to inclusions of fabric dust collectors on all modern dry jig plants. Because of the environmentally friendly nature of dry jig plants, installation permits are often measured in days, not months. There has also been a fundamental advance in dry jigging efficiency. All of these advantages have renewed the coal industry’s interest in dry jigging. But air jigging is not right for every application. There are limitations due to particle size, particle shape, moisture and near gravity content. This article explores the evolution of dry jigging. It reviews parameters important for determining the suitability of dry jigging. It also compares historical performance data as measured by imperfection, against results from modern dry jigging technology. The article also presents data from modern dry jig installations.

Jan 1, 2007

By Adeyemi Adesina, Subhabrata Mishra, Syed Mohammed Mustakim, Malaya Kumar Jena, Shaswat Kumar Das

Utilization of low-grade manganese ore adopting the carbothermic reduction roasting process is a proven method to produce high-grade manganese ore. To minimize industrial waste and protect the environment, gas cleaning plant sludge (GCPS), which is a solid waste from steel industries, was employed as a reductant to perform the reduction roasting process. The optimum conditions to carry out reduction roasting of the low-grade manganese ore were found to be: a roasting temperature of 950 °C, a residence time of 2 h, 40% GCPS as reductant, and magnetic separation at 5000 G for a manganese ore size of –10 mm. A lowgrade manganese ore comprising Mn grade 31.27% and Fe grade 19.78% having a Mn/Fe ratio of 1.58 containing a high silica content of 26.48% was used for the carbothermic reduction roasting having mineral phases of pyrolusite (MnO2) and hematite (Fe2O3) as found from XRD. The gangue minerals were separated during the magnetic separation, and the upgraded product was obtained, which reached a maximum value of TMn 49.5% with RMn 76.55% and TFe 62.19% with RFe 42.51%. In the study, activated charcoal (AC) was also taken as a reductant for comparative analysis; the experimental results revealed that GPCS performed better than that of the AC, showing potential to be used as a reductant in metallurgical industries. However, the resultedMn/Fe ratio was very low for the reduced sample; therefore, it can be used for smelting along with high-grade manganese ores as a feed.

Mar 5, 2021

By Ping Zhang, Shahram Mozaffari, Andreas Ylmefors

The risk associated with mining induced seismicity and the related rock bursts has become one of the major threats to the safety and sustainability of mining at the Kiirunavaara mine. The causes of mining induced seismicity at the Kiirunavaara mine are very complex and have affected our understanding on the source mechanisms of seismicity and further the mitigation of the seismic risk. Detailed analysis of historical mining induced seismicity at the Kiirunavaara mine was conducted. The focus of this analysis was placed on the classification of large seismic events and the evaluation of the influential factors on the classified seismic events. 145 events with local magnitude larger than 1.5 that occurred between January 1, 2011 and March 31, 2021 were analyzed. For this analysis, seismic events located in the hanging wall were not included, as these have not been observed to cause large damages to the mine itself. It was found that the magnitude of the events had good correlation with the stress change in relation to the production location. The seismic events were classified as mining-front associated, ore-pass associated, mining-front and ore-pass associated and others, according to their hypocenter location. Most of the mining-front associated events, concentrated around the production levels and slightly above and below them, generally correlated with shear cracks, and most of them occurred when the ore flow between two production levels started. The numerical modelling showed that slip of the geological discontinuity, due to unclamping between hanging wall and footwall, could be the major causative mechanisms, which further supports this finding. The ore-pass associated events are located close to the ore passes. Large seismic events located between ore passes have the source mechanism of both fault-slip and non-shear, but events located at the outer side of ore passes were all fault-slip type. By checking with the ore pass scanning data, it was concluded that the most of the events located between ore passes could be pillar bursts. An elastic core concept has been then used to define a critical pillar width. The paper is not intended to be prescriptive but rather to initiate discussion of the possible classification of seismic events at the Kiirunavaara mine and to present new perspectives of the causes of the seismicity for improving the present seismic risk management.

Apr 26, 2022

By Charlotte Abena Benyarku, Albert Buabeng, Eric Stemn

The abstract highlights the increasing use of mobile equipment in mining and its contribution to accidents. The research analyzes injury narratives from Ghanaian surface gold mines to understand the involvement of mobile mining equipment in injuries and explore the use of injury narrative data as a human factors tool. The study identified priority human factor issues, such as operating mobile mining equipment, part removal/installation, and the operator's cabin. The use of Sankey diagrams for multivariable analysis effectively identified specific operator-centered issues that warrant further investigation for improved safety interventions.

Mar 29, 2022

By Alfredo Valencia-Toledo

This study delves into the satisfaction levels of indigenous communities in Apurimac-Cusco, Peru, concerning mining activities in their region. Our primary objective is to elucidate the interrelationships among observable variables, which are conceived as linear combinations of multiple factors. Employing the statistical methodology of exploratory factor analysis, we aim to pinpoint the pivotal factors influencing the progress of mining activities in Apurimac-Cusco. Through our analysis, we have identified eight key factors that exert a significant impact on mining’s sustainable development in the area. These factors encompass diverse facets, ranging from the support offered by mining company to communities, environmental considerations, education, economic factors, provision of basic services, transportation and communication, support for social organizations, and social-health-related aspects. This research endeavors to provide a comprehensive understanding of the complex dynamics surrounding mining activity satisfaction among the indigenous population, offering a basis for further exploration and policy development.

Feb 17, 2024

By V. Svalbonas

Presently the U.S. mining industry is very conscious of costs. It is timely, therefore, to review the dominant specifications used in the industry for procuring large size-reduction equipment. These are compared with other specifications and procurement methods, such as ASME and DOD, using the criteria of resulting costs, safety/ quality, and fitness-for-service.

Jan 1, 1987

By D. A. Lee

The selection of control system equipment for a mineral plant is based on several criteria, including opera tor interface, supervisory capabilities, ease of maintenance, ease of programming and configuration, compatibility with auxiliary control equipment, and total cost. The paper discusses the technical evaluation procedure with respect to control system equipment available today.

Jan 1, 1988

By Fred C. Caspall

During the last century the importance of coal as a natural re- source has frequently come to the attention of the general public, but never before nave circumstances combined to focus as much attention on coal as it receives today. There is the ever increasing demand for energy that can be met only by coal consumption, coupled with a growing awareness of man's potential for despoiling his own environment. Society monitors the use of the remaining resources with an increasingly critical eye and, for obvious reasons, surface mining operations tend to draw an unusual amount of public attention. While the surface mine is a successful economic competitor with other uses of the earth's outer skin, one of the unrewarding results of such activity is tile simultaneous destruction of two of our most important resources--the coal seam and the surface soil. In a relative sense the coal seam is a nonreplaceable resource but the surface soil can be restored. Unfortunately, little attention has been given to land reclamation and even less has been devoted to the restoration of a productive surface soil. The research reported in this paper was de- signed to test the relative productivity of newly reclaimed surface mine spoils in western Illinois. The results are preliminary in nature but may aid in the future redevelopment of mine spoil soils in the Illinois Coal Basin.

Jan 1, 1975