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By C. Zhou, J. Srednicki

Electronic systems have been increasingly used in underground mines to improve mine safety. These electronic systems emit electromagnetic (EM) energy which can adversely impact the performance of other electronic systems nearby and thus should be characterized. Researchers at the National Institute for Occupational Safety and Health (NIOSH) characterized the magnetic fields emitted from devices that can potentially interfere with the performance of proximity detection systems (PDSs) and compared the emission levels of these devices to the susceptibility of PDSs. In this paper, we present our measurement results pertaining to this effort. Particularly, magnetic fields emitted from the different orientations of a powered air purifying respirator (PAPR) and two lite trackers are evaluated based on the RE101 protocol specified in the MIL-STD-461G standard. The results show that both devices emit strong magnetic fields which strongly depend on the orientation of the devices. At some frequencies, the maximum emission levels from the two devices exceed both the emission limit given in MIL-STD-461G and the maximum magnetic fields that a PDS can withstand without a failure. The results and findings in this paper can help the mining industry better understand electromagnetic interference (EMI) underground and provide critical scientific data that support mining-specific recommendations to address EMI-related challenges.

Feb 1, 2023

By Zhian Liang, Xiong Huang, Weixin Wu, Lifeng Cui, Zhuanhua Wei, Guoyao Li, Xiao Ni, Junrong Wang, Shuiping Zhong

ZJ 201 (modified starch) is a non-toxic, odorless, and biodegradable polymeric depressant, which selectively depressed galena in batch flotation tests while chalcopyrite was not significantly affected. In a plant trial, copper-lead separation was successful for the first time without using dichromate. Moreover, the plant process could be changed to sequential Cu-Pb flotation using ZJ 201 for higher grade lead concentrate. A copper concentrate was obtained with a Cu grade of 24.91% and a Pb grade of 5.11%, which recovered 76.6% of the copper from the original ore; a lead concentrate was also obtained with a Pb grade of 21.90% and a Cu grade of 5.31%, which recovered 52.6% of the lead. In addition to the effective copper-lead separation observed in the plant trial, another improvement observed is that gold was recovered mostly in copper concentrate, which could be sold for higher prices. Au grade reached 230.64 g/t, and its recovery reached 65.8% in the copper concentrate. Au grade in lead concentrate was only 18.90 g/t.

Aug 27, 2021

By John S. Wakeman

The initial step in the pelletizing of iron ores is the production of green balls. The importance of this step cannot be overemphasized as the physical quality of the green balls has a very significant effect on the subsequent induration process, regardless of the type of the indurating equipment employed. The ability of the green balls to withstand the rigors of handling, distribution, compaction and drying will have an effect on the degree of success of any pelletizing operation. Many factors affect the physical quality of the green balls including the prior processing of the iron ore, the characteristics of the balling feed and the type and quality of the binder used (if any). When working on the development of a new project or studying an existing operation, it is often desirable to determine what effect variations in these factors will have on green ball quality. It is generally impractical to make these determinations on a commercial, or even pilot plant scale, especially when the number of variables to be studied is large. Because of this, many organizations have developed batch techniques for producing green balls to enable them to perform such investigations with a minimum of time and expense. The batch balling method is at best, only an approximation of commercial balling systems. Many practitioners employ the use of pre-formed seed pellets to initiate a batch run. Thus, the growth mechanism encountered in any experiment is essentially snowballing. Unless an instability is introduced into a balling test (such as an excessive initial feed rate or an unusual feed material characteristic) the growth mechanism of coalescence is not present to a significant extent nor is it desirable. In a continuous operation, both mechanisms are present and necessary to sustaining the system. The batch balling technique thus produces pellets in an idealized manner and cannot be used to directly predict commercial green ball qualities. A general relationship does exist however, and the procedure is fairly sensitive to variations in test parameters. Although many refinements to this technique have been introduced over the years, batch balling is still essentially an art and subject to "operator effect". Therefore, to assure consistant and reliable results, skilled technicians who carefully adhere to established practice must be utilized.

Jan 1, 1971

By L. Barry Phelps

The application of an open-pit Materials Handling Simulator (OPMHS) to analyze mine planning and scheduling problems in large surface mines is discussed. The mine chosen for this application employed a large stripping dragline working in tandem with a shovel-truck haulback system for removing overburden. Large bottom-dump trucks were employed behind a coal loading shovel to transport the exposed coal out of the pit. Specifically, the current operations and the recommendations for short term and long term improvements were simulated on OPMHS. The effects of changing the operating parameters of the equipment on the total system were evaluated. Several alternatives were also studied for the best use of the existing equipment if the current operating parameters could not be improved upon. The results of the application are discussed.

Jan 1, 1978

By Xin Zhou, Huilin Jia, Xiaofei Liu, Jinxin Wang, Zifeng Meng, Zinan Du, Hui Xie, Guihang Jiang

The change of gas emission or concentration level at the working face is one of the main precursor characteristics of coal and gas outburst. At present, coal and gas outburst monitoring and early warning are mainly based on whether it exceeds the limit and its change law. However, the gas concentration level is affected by factors such as coal seam gas content, permeability, and mining process, and the change law is complex to recognize manually. In this paper, the response characteristics of gas concentration level in the mining process are analyzed and revealed, and a bidirectional long short-term memory model is established. The change characteristics of the gas concentration level in the mining and non-mining processes are studied and recognized. The results show that the change law of gas concentration in the mining process has apparent periodicity and trapezoidal volatility. The proposed intelligent recognition method based on the bidirectional long short-term memory neural network can automatically recognize the underground mining and non-mining processes, and the recognition accuracy achieves 97.7% . The research can significantly help improve the level of coal mine safety management and the accuracy of early warning of coal and gas outburst.

Apr 29, 2023

Improvements in computer technology and associated software have allowed the improvement and development of more advanced ventilation modeling software packages including those that have the ability to simulate the effects of a mine fire on the ventilation system in terms of heat, smoke and gas distribution. This ability has real applications for the mining industry in terms of emergency planning, training and response. The primary focus of this paper will be the benefits to training programs that this type of software can provide to all types of training for various personnel, from the newly hired inexperienced miner, mine rescue, atmospheric monitoring personnel and emergency evacuation drills. The results of the simulations can then be used to give miner?s more detailed information on what types of conditions they may face based on the type and location of the fire and the program itself can be used to manipulate the ventilation system in a way that emergency response personnel may (i.e. tear down stoppings to reduce airflow to the fire area) and see the effects in real-time.

Jan 1, 2012

By B. W. Lawrence

Shaft alignment requirements are consistently met using conventional shaft sinking methods. Little attention has been given to achieving similar alignment accuracies using rotary drilled shaft methods. Alignment of these shafts is difficult to control and guarantee. Bare shafts and shafts that use drum hoisting systems can accept some deviation. However, combining drilled shafts with Koepe hoist installations presents new accuracy requirements for drilled shafts. This paper describes the importance of verticality with practical examples, and discusses various methods of measuring verticality and their respective limitations.

Jan 1, 1989

By Jürgen. F. Brune, CLAIRE STREBINGER, ADITYA JUGANDA, Gregory E. Bogin Jr

The abstract highlights the risk of methane gas explosions in underground coal mines and the potential of computational fluid dynamics (CFD) modeling to simulate such events and assess their impact on mine ventilation. The study focuses on developing CFD models for large-scale explosions in longwall mines, specifically simulating methane gas explosions resulting from face ignition during coal cutting. The research demonstrates the integration of a combustion model into a longwall mine ventilation model and shows how the availability of explosive gas mixtures significantly affects flame propagation and explosion pressure.

Mar 27, 2022

By H. M. King

A combination of chemical, statistical, geographic, and microscopic analyses reveal that sulfur in West Virginia coals is extremely variable in both form and abundance. Coals in southern West Virginia typically contain less than 1% total sulfur with organic sulfur being the dominant species. Northern West Virginia coals average about 2% total sulfur, mainly contributed by sulfur minerals. In addition to these regional trends, significant variations in sulfur form and abundance exist both vertically and laterally within individual seams. On both regional and local scales, the pyritic sulfur component can vary significantly in mineralogy, particle shape, maceral association, and particle size.

Jan 1, 1986

In this paper, a number of novel hypotheses that provide a fresh perspective on the characterization of strata movements associated with longwall mining are developed by analyzing subsidence measurements with an influence- function-based computer program. With this influence-function technique, easily obtained surface displacements can be used to determine some of the complicated, expensive, and difficult to measure movements of the immediate roof strata in a longwall panel. The primary hypothesis developed by this analysis proposes the existence of an area of partial roof caving near the edge of a panel called the "edge effect." A second hypothesis, interrelated with the first, promotes the importance of the effect of gate-entry closure on the observed strata movements. Both the primary edge effect hypothesis and the secondary hypothesis concerning gate-entry closure are justified and quantified in an extensive analysis of surface subsidence that uses supporting information from related theories, design criteria and insitu measurements. Next, the edge effect and the gate closure hypotheses are extended further and used to provide an explanation of the complex subsidence interaction of adjacent longwall panels in what is termed a "redisturbed" effect. Finally, in the conclusions of this paper, the importance of accurately understanding these longwall strata movements for proper subsidence prediction or gate design is stressed.

Jan 1, 1986

By J. F. Brune

This is a shortened version of the paper ?The Methane-Air Explosion Hazard Within Coal Mine Gobs published in the 2013 volume of SME Transactions (Brune, 2013). This paper analyzes the explosion hazard resulting from the formation of methane-air mixtures in the mined-out gobs of underground longwall coal mines. Evidence from numerous mine explosions suggests that explosive methane zones can form within longwall gobs. Explosions and fires resulting from these methane accumulations have led to severe and fatal injuries to the miners, including the explosion of the Upper Big Branch mine in West Virginia, where 29 miners lost their lives. The paper also reviews current research on numerical modeling of gas flows in longwall gobs and outlines how targeted injection of nitrogen into gobs can effectively reduce the volume of such explosive methane zones. The paper concludes that comprehensive monitoring of gas compositions along the accessible fringes of the gobs along with inertization, improved ventilation schemes and further research are necessary to control this explosion hazard and make mining operations safe.

Feb 23, 2014

By M. S. Celik

The principal impurities in some feldspar ores are titanium and iron which impart color and in turn degrade the quality of the ore. The mineralogical investigations indicate that titanium element originates from mainly rutile with small amounts of sphene. Conventionally, fatty acids and particularly sodium oleate are extensively used in the flotation of colored minerals from feldspar ores with reasonable success. In this study, new reagents, oleoyl sarcosine and hydroxamate have been used to float colored impurities before and after magnetic separation. Oleoyl sarcosine is found to exhibit better results compared to fatty acids and hydroxamate. The mechanism of the action is elaborated on the basis of experimental data.

Jan 1, 1999

By R. Stefanko

Rock bolting as a method of support continues to increase with applications in many other industries in addition to mining. Nevertheless, with nearly 55,000,000 roof bolts installed in coal mines alone last year, this remains as the single greatest use. While bolts have frequently supported ground where conventional timbering could not, there are relatively few design criteria; and trial-and-error procedures prevail. Furthermore, development of suitable instrumentation that is simple to install and readout, sensitive, durable, reliable, safe and economical in evaluating the effectiveness of a bolt over long periods of time lags behind. Therefore, the pull test continues to be the most popular method of evaluating the applicability of a certain type of roof bolt under specific installation conditions. At Penn State in the Department of Mining, research has been conducted for a number of years to measure bleedoff in carefully controlled laboratory experiments as well as in underground investigations.1,2,3,4 Unfortunately, most of the instrumentation developed has been primarily suitable only for research purposes, not possessing all of the aforementioned characteristics desirable for routine underground use. Other groups also have met with restricted success. Therefore, while relatively crude, the torque wrench continues to remain as the most widely used load measuring device. While both field and laboratory tests continue to be conducted, analytical analyses are attempted to discover the more important design parameters in order that more efficient anchorage might be devised.

Jan 1, 1969

By Xuchen Fan, Chenyang Zhou, Yuemin Zhao, Liang Dong, Chenlong Duan

A gas–solid fluidized bed using magnetite particles is an effective methodology for coal beneficiation in the field of dry coal cleaning. Broadening the size range of magnetite used in the bed decreases medium preparation cost. In this study, a tapered fluidized bed was used to investigate a magnetite particle size range of −0.5 + 0.074 mm. The results showed that a tapered fluidized bed effectively strengthens mixing of magnetite with a wide size range (−0.5 + 0.074 mm). The results of beneficiation experiments indicated that with increasing tapered angle, separation efficiency increased and then decreased. The highest separation efficiency was obtained at a tapered angle of 10°. The optimal results showed that the ash content of the concentrate decreased from 31.82% to 12.33% with a probable error of 0.11, which indicated that a tapered fluidized bed was efficient to improve fine coal beneficiation performance.

By David G. Kidd

The principles of Ore Sorting in general and photometric sorting in particular are discussed with detailed reference to the Model 16 machine. The operating principles and design of the Model 16 are discussed and a case study presented to demonstrate the use of sorters to process an industrial mineral. In addition, an economic study is presented, to highlight the benefits of ore sorting, by evaluating the increased revenue that can be achieved using an ore sorter to process a particular ore body.

Jan 1, 1983

By Miles L. Silberman

Three major suites of igneous rocks were erupted in the Great Basin in middle and late Cenozoic time. The first, most likely, resulted from sub- duction of a Pacific plate (Farallon plate) beneath the North American plate, resulting in eruption of andesitic rocks in the northern Great Basin between 42 and 43 m.y. ago. Between 34 and 17 m.y. ago, igneous activity migrated to the southwest, largely as eruption of volumincus rhyolite-quartz latite ash-flow sheets, ending about 17 a.y. ago with the onset of crustal extension and north-south-trending Basin and Range (rift) faulting. The second volcanic suite erupted between 17 and 8 m.y. ago in the northern Great Basin; is mostly basaltic or bimodal basalt-rhyolite. The third volcanic suite consists of andesitic and rhyolitic lavas and some basalt erupted between about 22 to 6 m.y. ago in the western Great Basin along the northwest-trending Walker Lane fault zone. Hydrothermal ore deposits are associated with all suites of igneous rocks, but the largest production has come from mines associated with andesitic rocks of the third (western Great Basin) suite. The oldest (34 to 42 m.y.) andesitic rocks (first suite) of the northern Great Basin have produced some large deposits; slightly younger silicic rocks of this suite are mostly barren. Many small ore deposits are associated with the 17- to 8-m.y.-old basalts (second suite) of northern Nevada.

Jan 1, 1976

By W. Missildine, J. K. Hrica, I. Benbourenane, T. J. Orr, J. L. Bellanca

Each year, haul truck accidents account for a large portion of mining injuries and fatalities. To better understand why these accidents continue to occur, researchers from the National Institute for Occupational Safety and Health (NIOSH) utilized a cognitive task analysis methodology to identify the user requirements of surface haul truck operators and assess differences in perceptions between operators, managers, health and safety professionals, trainers, and maintenance personnel. Additionally, researchers used the critical decision method to focus on better understanding the cognitive demands, decision-making, and problem solving during nonroutine incidents. The preliminary results of this study identify and explore themes within the broad categories of hazards, skills & expertise, and training and provide detailed accounts of nonroutine incidents such as near-misses, loss of control, and collisions. These accounts reveal insights into operator decision making and event progressions that can then be used to build more realistic training scenarios and address hidden hazards and root causes of these incidents. These results, along with potential solutions offered by study participants, can inform future research and help identify creative interventions that can be used by mine operators to address haul truck safety issues

Mar 2, 2022

By A. Hammons

Automated temporary roof support (ATRS) systems have been incorporated into roof bolters since the 1970's. During roof bolting, many injuries have occurred from large pieces of draw rock falling inby the ATRS beam and tipping back into the operator's area. Other injuries have occurred due to smaller, sharp rocks falling onto the operator's hand and arm during initiation of roof bolt drilling. These injuries are attributed to weak immediate roof, sometimes called roof skin failure. Even though ATRS systems support the roof and provide a measure of protection against roof skin failure, additional hazards sometimes do exist immediately inby and outby the supported roof. Design innovations such as the ATRS mounted rocker pad deflector systems have been designed to improve the roof bolter operator safety. This paper will inform the reader of the hazards, machine evolution through different design solutions, and the current state of the art in preventing roof skin failure injuries when roof bolting.

Jan 1, 2009

By E. -R. Niinikoski, M. A. Islam, H. Mischo, G. Barakos, J. Joutsenvaara, G. Meissner

European Union's transition to a low-carbon and digital economy highly depends on securing the strategic autonomy of the Critical Raw Materials (CRMs) supply chain. This paper introduces a European Commission-funded research and innovation action, AGEMERA, which aims to create detailed geological and people's concerns maps to unlock the CRMs potential in Europe. Furthermore, the project will develop educational packages for schools and universities, publish online CRM-related games and news flashes, and arrange public events to ensure a basis for socially accepted and sustainable exploration and mining of CRMs in Europe. 1. IntroductionCritical Raw Materials (CRMs), crucial for shifting to a low-carbon and digital economy, should focus on maintaining Europe's overall supply-demand balance (Birol, 2022). Therefore, to proactively address the surge in demand and ensure the strategic autonomy of European industrial supply chains, the exploration and extraction of CRMs must be scaled out across the continent. Moreover, mobilizing Europe's domestic potential is vital for the EU to become more resilient and to establish open strategic autonomy as the demand for CRMs continues to increase quickly on a global scale (European Commission, 2021). Base metal extraction and mining have a long history in Europe. Nevertheless, CRMs mining projects have shown less success, although these have a lot of potential (Guzik et al., 2021). The main barriers are a lack of investment in mining and exploration, complicated and drawn-out national permitting processes, and low levels of public support (European Commission, 2020). It is necessary to have a vast amount of knowledge and intelligence about CRM's potential and market impact. Novel non-invasive geophysical survey techniques that enable sustainable exploration must be created and used to enhance mineral system models of ore deposits incorporating CRMs. The minerals policy framework significantly influences the mining industry's performance, stability, and sustainability. However, the EU Member States' mineral policy frameworks differ significantly (MINLEX, 2017). In addition, the Fraser Institute Annual Survey of Mining Companies offers concrete information on how managers and executives of mining companies view key policy areas that impact mining activities in the jurisdiction in which they operate or are familiar (Jackson & Green, 2015).

Feb 1, 2023

By S. Potgieter-Vermaak, T. T. Chiweshe, W. Purcell

The advantage of using ammonium phosphate salt as flux is the selective precipitation of chromium(III) compounds, which are considered nontoxic and environmentally friendly. The technique in this paper is determined to have potential to be applied in the metallurgical industry, where it can be used in the beneficiation of chromite mineral ores. The higher chromium contents of chromite ores often require furnaces to run at higher temperatures of above 1,300 °C, which can cause shutdown of the ore processing plant and accumulation of the sticky chrome compounds — including toxic chromium(VI) waste — which are generated as byproducts. The other advantage of this technique is its low to moderate energy consumption compared to existing techniques.