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By T. C. Canter

Technological change is continually affecting the mining industry and the many papers being presented at this meeting reflect this fact. I fully agree that miners must remain fully cognizant of technology that can change mining costs and therefore your competitive marketplace. Despite the embrace of new technology and effective mine management techniques, the mining enterprise may not realize increased net income if the structure of the minerals marketplace is not understood. An important segment of the marketing structure for minerals is transportation. Transportation costs per ton can be much greater than the mining costs per ton and may accordingly overshadow hard earned gains in productivity. Change is greatly affecting the transportation industry but the change is driven more by governmental policy than technology. Although some technological advances are occurring in the bulk transportation business, the changes I want to address arise from policy. Policy changes have come from legislation in the 1970's culminating with the Staggers Act of 1980 and ensuing Interstate Commerce Commission decisions.

Jan 1, 1985

By T. J. Fenner

Surface and underground mining operations are often hindered by unknown tunnels and stopes and the precise locations of adjacent workings. Mine safety and planning are adversely affected especially in previously undermined areas where historical records are incomplete or non-existent. The results of several Ground Penetrating Radar (GPR) studies for the detection of known mine tunnels in underground coal; salt, and gold mines are presented. A case study to locate unknown, abandoned mine workings at a surface gold mine successfully located all workings to a depth of 11 meters.

Jan 1, 1992

By James F. McConnell

Federal and State sulfur oxide emission and ambient air quality regulations have been implemented to fulfill the requirements of the Federal Clean Air Act Amendments of 1970. Primary and secondary air quality standards have been established at levels considered necessary to assure the protection of the health and welfare of the public. Standards of performance under this Act have been established to control the rate of sulfur oxide emissions from individual sources so as to protect and to improve the quality of the Nation's air. The new source standards of performance were made rigorous for large coal burning stationary sources. This has had a severe impact on the electric utilities that operate the coal fired steam electric plants which are the largest consumers of the Nation's coal production. States have taken different approaches in State Implementation Plans (SIPS) as approved by the Federal Environmental Protection Agency. Some states, such as Pennsylvania, have chosen to permit moderate SO2 emission rates from existing sources which are not in critical air basins. All are required to meet primary and secondary air quality standards and to limit sulfur oxide emissions from new large stationary sources to a minimum of 1.2 LBS of S02/MMBTU fired. This re- quires a fuel sulfur percentage of about 0.7 for a 12,000 BTU/lb coal. In an effort to develop strategies and technologies to conform to performance standards while continuing and hopefully expanding the utilization of the Nation's coal supply, the electric utilities, the Federal and State regulatory agencies, and other industries and government agencies are considering several alternatives. 1. Natural low sulfur coal 2. Flue gas desulfurization - (FGD) non-regenerative and regenerative 3. Coal gasification 4. Liquefaction and solvent refined coal 5. Fluidized bed combustion 6. Chemical coal cleaning 7. Physical coal cleaning Of these options, only the first and the last can be considered to be widely used in full commercial practice at this time. FGD has certainly demonstrated technical and operating feasibility and is close to being in full commercial practice but it remains to be seen if the large systems under construction are economically and environmentally optimum.

Jan 1, 1975

By Liming Yuan, Wei Tang, RICHARD THOMAS, JOHN SOLES

Lithium-ion (Li-ion) battery pack fires pose great hazards to the safety and health of miners. A detailed experimental study has been conducted at the National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Mining Research Division (PMRD) to investigate the effectiveness of different fire suppression systems on Li-ion battery pack fire extinguishment. Tests were conducted in a well-ventilated container. Two sizes of battery packs (12 V and 24 V) were heated by heater strips to trigger thermal runaway and fire. Water mist with different flow rates, ABC powder, type D dry chemical, and water mist with F500 additives were used as the fire suppression agents. Multiple thermocouples were installed on the battery packs to measure the temperature evolution during the tests. The results indicate that the water mist with F500 additives is the most effective suppressant among the agents tested. Dry chemicals, however, do quench the fire for a moment, but cannot prevent re-ignition of the battery since they do not provide enough cooling. The findings of this paper can be used to develop safer battery fire suppression techniques in mining environments.

Jan 1, 2024

By Johann Steynberg

The design and construction of a Concentrator based on initial pilot plant work is rarely perfect. Palabora's plant was no exception although the basic objective to produce copper in a safely conservative manner was certainly achieved in a profitable manner. identification of the metallurgical and mechanical deficiencies of the plant through operating experience and a better concept of the minerology of the orebody enabled the development of a more efficient process both in terms of the metallurgical performance and cost effectiveness. To maintain and improve this level of efficiency, continuous inspection and revision of the plant metallurgy and engineering standards is required. In this presentation a few of the investigations and changes are described: 1.0 Alternative methods to restrict and eliminate the detrimental effect of critical size material on the performance of an autogenous mill. 2.0 An analysis of the environmental condi¬tions in Palabora's grinding circuit and the introduction of high chrome balls as grinding media. 3.0 The role of magnetite in the beneficiation process at Palabora. 1.0 Alternative methods to restrict and eliminate the detrimental effect of critical size material on the performance of an autogenous mill.

Jan 1, 1985

By Liming Yuan, Isaac Zlochower, RICHARD THOMAS, Thomas H. Dubaniewicz, Teresa Barone

Mining vehicle manufacturers are developing lithium-ion (Li-ion) battery electric vehicles as an alternative to diesel-powered vehicles. In gassy underground mines, explosion-proof enclosures are commonly used to enclose electrical ignition sources to prevent propagation of an internal methane (CH4)-air explosion to a surrounding explosive atmosphere. Li-ion batteries can create pressurized explosions within sealed enclosures due to thermal runaway. Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) measured thermal-runaway pressures of lithium iron phosphate (LFP) cells as a function of free space within sealed enclosures and observed an inverse power relationship. A well-confined cell produced 4260 psia (294 bar) of pressure during a thermal runaway, far exceeding minimum pressure containment specifications for conventional explosion-proof enclosures. Results indicate that adding enough free space surrounding LFP cells can reduce thermal-runaway pressures to levels below that expected for CH4-air ignitions. Measured thermal-runaway temperatures were below the minimum autoignition temperature of CH4-air.

By Yi Luo, Jian Yang, YUJIA LIAN

Scale physical models, constructed according to the principle of similarity theory, are widely used to simulate the mining disturbances to surrounding strata and to evaluate the effectiveness of implemented ground-control techniques. This technique has also been used for studying mining-induced surface and subsurface subsidence. The movements of the observation points installed on the physical model at different mining stages are currently measured using a total station, which is time consuming and inaccurate, especially on small-scale models.

By Allister McLeod

Coal is expected to play a major role in energy supply in the next 20 years. Oil is a convenient and still reasonably abundant fuel. However, its major sources of supply are regions where there is nervousness about political stability. Uranium is a more efficient fuel - but there is a continuing community apprehension regarding its use. What coal may lack in efficiency, it makes up in long term availability and competitive overall cost. Moreover, diversity of source ensures stable long-term supply. In this way, a major role for coal in the world energy scene is assured. Cyclical considerations aside, demand for coal will increase significantly and it will meet a substantial share of new energy demand, replacing oil and gas in major industrial and electric utility markets. By around the year 2000, coal's share of world energy could reach 30% and rival oil as the largest single source of energy.

Jan 1, 1982

By A. Podlesny, E. N. Rubinstein, J. J. Sammarco, B. Demich

Roof bolting typically follows the extraction of a commodity to help keep the roof from collapsing. During 2004 to 2013, roof bolter operators had the highest number of machinery-related injuries, accounting for 64.7 percent, at underground coal mines. This paper analyzes U.S. roof bolter fatal and nonfatal lost-time injury data at underground work locations for all commodities from 2004 through 2013 and determines risk indices for six roof bolting tasks. For fatal and nonfatal incidences combined, the roof bolting tasks in order of the highest to lowest risk index were bolting, handling of materials, setting the temporary roof support (TRS), drilling, tramming, and traversing. For fatalities, the roof bolting tasks in order of the highest to lowest risk index were handling of materials, setting the TRS, bolting, drilling, traversing, and tramming. Age was found to be a significant factor. Severity of injury, indicated by days lost, was found to increase with increasing age as well as with increasing experience, largely due to the confounding of age and experience. The operation of the roof bolting machine used in underground mining should be a research priority given the high frequency and severity of incidents. The results also suggest that temporal factors may exist, so additional research is warranted to better understand these factors and potentially develop interventions. This research provides a datadriven foundation from which future research can be conducted for safety interventions to reduce the frequency and severity of incidences involving the roof bolter activities of bolting, handling of materials, and setting the TRS.

Jan 1, 2016

By C. RAMADINI, F. NURJAMAN, A. SHOFI, B. SUHARNO

In this work, the selective reduction of lateritic nickel ore was carried out using sodium sulfate, sodium carbonate, and sodium chloride as additives. The 5 wt% of anthracite coal, which contains 60.35% of fixed carbon and 1.9% of sulfur, was used as a reductant. All raw materials were mixed homogenously prior to the pelletization process into 10–15 mm of diameter. The reduction process was carried out to 50 g of pellets at 950 °C, 1050 °C, and 1150 °C for 60 min in a muffle furnace at atmospheric pressure. It continued with a wet magnetic separation process to separate ferronickel (concentrates) and impurities (tailings). Iron and nickel grade analysis was performed using XRF, while phase transformation and microstructure were analyzed with XRD and SEM–EDS. The results showed that the sodium sulfate was superior, resulting in the highest nickel grade in concentrate, i.e., 15.06%. The sulfidation mechanism, which could inhibit the metallization of iron, effectively increased the nickel grade in concentrate than decomposition of carbonate and chloridization process. The sulfur content in the reductant also influenced the selective reduction process. It promotes more sulfidation of iron, thus increasing the nickel grade in concentrate.

Jul 7, 2021

By Richard A. Thomas, Liming Yuan, Wei Tang, JOHN SOLES

Lithium-ion (Li-ion) battery applications are increasing for battery-powered vehicles because of their high energy density and expected long cycle life. With the development of battery-powered vehicles, fire and explosion hazards associated with lithium-ion batteries are a safety issue that needs to be addressed. Li-ion batteries can go through a thermal runaway under different abuse conditions, including thermal, mechanical and electrical abuse, leading to a fire or explosion. The National Institute for Occupational Safety and Health (NIOSH) mining program is conducting research to prevent and respond to lithium-ion battery fires in battery-electric vehicles in the mining industry. In this study, experiments were conducted to investigate the effectiveness of different suppression systems including dry chemical, Class D extinguishing powder and water mist for lithium-iron-phosphate (LFP) battery pack fires. The effects of activation time and release time of the water-mist system on the suppression of the LFP battery (a type of Li-ion battery) fires were studied. The results of this study may be helpful for developing strategic firefighting and response plans for battery-powered vehicles used in mining.

Aug 1, 2024

By Frank A. Jerabek

Problems of mine backfilling and fill material deposited underground, the characteristics and relationship between the deposited fill material and overlying ground, and the practical applications and limitations of hydraulic backfilling as ground support are discussed. A great variety of materials ranging from coal washery refuse to concentrator tailings is used as hydraulic fill. Some materials will solidify and cement; others will resemble quicksand, Hydraulic fill as ground support is more efficient in inclined mine openings than in horizontal mine openings, where it cannot be placed tightly to the back. This and other deficiencies of hydraulic backfilling led to the development of pneumatic stowing. Research work in hydraulic backfilling at the Pennsylvania State University is also discussed. This research work includes the investigation of segregation in the discharged fill slurry, the quantity of solids escaping in the drain liquid, the relationship of escaping solids to slurry concentration and discharge rate, and the compressibility of fine fill material.

Jan 1, 1965

By Stephen Utter

One function of mining is to supply oil shale of the required grade and characteristics to surface retorts. The mining methods must he safe, efficient, and environmentally acceptable. Although the Bureau of Mines no longer conducts research on methods of mining fossil fuels, including oil shale, its many years of activity in that field resulted in a significant body of findings. This article summarizes some of these findings, with respect to oil shale mining. The large areal extent of Green River formation oil shales and the diversity of geologic, hydrologic, topographic, and other conditions, preclude the use of any one single mining and waste management technique. Instead, in most instances, methods and equipment will be chosen to meet site-specific conditions. Such methods include conventional surface mining (open-pit and strip), underground mining (room-and-pillar, sublevel stoping, caving) and in situ extraction (true in situ from surface drill holes and modified in situ from underground retorts containing rubblized oil shale). Combination or hybrid systems may prove suitable. Both surface and underground backfilling of spent shale waste may be practiced. Tremendous amounts of oil shale must be mined, processed, and the waste shale properly disposed of in order to meet projected industry production goals. For example, about 1.4 tons of oil shale averaging 117 L of shale oil per ton are required to produce one bbl of oil. A plant with a daily production of 8 dam' (50 000 bbl) of oil would thus require some 68 kt of raw shale daily. This is more than the average daily production from any underground mining operation.

Jan 1, 1981

By Anthony Iannacchione, Tim Miller, Nicole Evanek

The Subtropolis Mine is a room-and-pillar mine extracting the Vanport Limestone near Petersburg, OH. In February 2018, mine management began implementing a new mine layout to better control the negative effects of excessive levels of horizontal stress. Almost immediately, the conditions in the headings improved. Conversely, and as expected, stress-related damage was concentrated within crosscuts. Over the last 18 months, the mine operator has diligently experimented with different techniques/methods to lessen the impact of the instabilities in the outby crosscuts. The range of controls used by the mine operator include angled crosscuts, crosscut offsets, increased distance between crosscuts, arched crosscuts, cable-bolted crosscuts, altered blasting pattern, and windows. A window is used to resist roof deformation by leaving a strong brow of roof rock within the crosscuts.

By Joseph W. Leonard

Much progress has been made in the application of geostatistics to hard rock ore deposits.1,2,3 4,8 Progress in the application of geostatistics to coal deposits has developed over a period of time out of hard rock technology.5,7 Exploratory drilling in many hard rock deposits is frequently significantly more productive than exploratory drilling in coal deposits. For example, hundreds of feet of drilling and/or many drill setups are frequently necessary to obtain a few samples from a typical 4 to 6 foot thick coal seam. With hard rock deposits, which are frequently thick or volumetric, less drilling dead work is involved in sampling the deposit. To produce a variogram, which is the basic element needed for geostatistical analysis, a few well positioned holes drilled into a hard rock deposit where the core(s) can be divided into many sections can produce a detailed variogram. To produce a similar type variogram in coal, it is necessary to drill many dozens of holes with much of the core length consisting of overburden data which is frequently of only secondary importance. To apply geostatistics to coal, not only are many separate sample sites needed, but frequently a problem exists in that the interval distance between samples cannot be controlled with the ease that hard rock drilling intervals can be controlled where it is only necessary to cut core segments according to some preassigned interval of distance. Because the uses of existing coal deposit samples are frequently handicapped by irregular sample distances and lack of sampling density along certain directions needed for the development of variograms, the application of geostatistics to coal deposits frequently does not proceed with the same efficiency and rapidity as when these techniques are applied to ore deposits. Grid-fitting was developed by the writers, as a logical and evolutionary improvement over the long and successful application of geostatistics to coal seams.6,9 Grid-fitting combines the trending of variance as well as other aspects of probability theory to optimize informational yields from the commonly less productive data derived from coal exploratory programs. Grid-fitting is basically a technique where a hypothesis involving numerous grid patterns, where each pattern is of a given geometry, size and direction is repeatedly matched against actual sample data to determine which match results in the closest fit of the hypothesis to the data. To determine the closest fit, a special index known as a selectivity index was developed. The selectivity index is basically the product of the mean and variance of the variances contained within each of the grids. hence, if SI is the selectivity index then [SI = Xs E (S i - Xs) /N] where [X]s is the mean of individual grid variances Si2 for any pattern of given geometry, direction and size.

Jan 1, 1984

By C. Roos

Tradicionalmente en la industria minera, el flujo principal del proceso funcional para la evaluación de recursos y reservas procede de geólogos que elaboran el modelo geológico, de allí a los geólogos que hacen la estimación de los recursos (los modeladores) quienes estiman los grados, y a los ingenieros de mina que desarrollan el diseño de la mina y su calendario. La interfaz entre estas tres disciplinas no está siempre exenta de baches. Las presunciones hechas durante una etapa del proceso no siempre son comunicadas a los demás, a pesar que la mayoría de las empresas mineras tienen procedimientos y protocolos establecidos para promover la comunicación a lo largo de las distintas disciplinas. Estos procedimientos no siempre logran su propósito debido a una variedad de razones que incluyen restricciones de tiempo, no tener disponible a las personas apropiadas, o a una falta de entendimiento de lo que las otras disciplinas requieren, y el proceso de traspaso puede degenerar en el envío de archivos a la siguiente disciplina en el flujo de proceso. Este artículo se ocupa de la interfaz entre la estimación del recurso y las disciplinas de la ingeniería de minas y el esquema de algunas de las presunciones comunes hechas al generar un modelo del recurso y los riesgos que los ingenieros podrían correr al elevar los grados de corte, optimizar calendarios o realizar predicciones. Los casos de estudio presentados se centran en depósitos de oro a cielo abierto, pero los conceptos deben ser aplicables a toda la industria. Aquí también proveemos un resumen de preguntas clave y recomendaciones.

Jan 1, 2014

By V. Gall

The three-dimensional finite element technique combined with the progressive failure approach was utilized to simulate stress distributions in a mine section which occur in response to a longwall mining operation. Due to the availability of the Cray supercomputer, a large-scale three-dimensional finite element model was developed for the analysis. The Hoek-Brown failure criterion, which describes a realistic behavior of rock masses, was used for the simulation of progressive failure. A comparison of calculated and monitored stresses in the mine has shown that the model gives a good representation of stresses in the mine structure.

Jan 1, 1990

By B. W. Cavender

Innovative mining and metallurgical operating techniques or processes can be identified and developed by systematically analyzing change as it occurs within the mine, plant, technology, or industry. Sources of change to be monitored for innovative opportunities include unexpected successes or failures, incongruities between perceived and actual events, process needs, changes in perceptions, and the development of new knowledge. Innovation can be effectively organized, practiced, and managed. The perception of change as an opportunity rather than a threat is mandatory, as is the systematic measurement of innovative performance. Innovation is enhanced by specifically-designed policies regarding organizational structure and staffing, daily management practices, and compensation and incentives.

Jan 1, 1994

By L. Valentik

Many attempts have been made during the last forty years to evaluate the performance of gravity separation equipment, that is, the effectiveness with which light and heavy particles are separated. The most comprehensive treatment of the subject was made at the 1st International Conference on Coal Preparation held in Paris (1950) by Cerchar. The methods suggested by the Conference were accepted and very widely used in the last 25 years. This paper discusses an improved method of evaluation in the light of the now accepted standard presentation. The float and sink analysis of the product is presented on a Gaussian distribution curve, resulting in an easier visualization of the inherent difficulties of separation. The ogives of the distribution curve are then plotted, giving a quantitative measure of the deviation from perfect separation as an error distance instead of an error area. Illustrations of the new method are given both for gravel and for coal preparation, but the concept is valid and applicable to other types of minerals which are separated by gravity methods.

Jan 1, 1968

By B. Kyslinger

"In underground mining, machine design is predominantly dictated by mine conditions and individual customer desires. In partnership with Foresight Energy, J. H. Fletcher & Company was tasked to design and manufacture a new roof bolting machine with six independent drilling apparatus on board capable of drilling and bolting the roof and ribs with material handling. This is the first Fletcher® six head machine to be designed and built for the mines in the United States. The machine is intended to work in the Illinois Coal Basin. The objective was to produce a machine capable of drilling and installing six bolts simultaneously with a limited number of operators. The goal of the mine is to decrease the time to bolt a cut to improve the safety level of the current roof bolting method, improve efficiency and to improve the bottom line cost of entry development. The customer wanted four mast feed drills at the front of the machine dedicated to installing roof bolts and then another two mast feed drills behind them dedicated to rib bolts. This dictated the requirement of latched controls, which would allow the operator to start drilling one hole and then latch the controls to be able to move on to the next. To accomplish this, we developed a unique hydraulic latch circuit to maintain operator safety and compliance. Guarding was added to prevent an operator from coming into accidental contact with a latched drill. The result of the design is a machine with a single platform and six independent masts with drillheads: four masts strictly for drilling and installing roof bolts on the front of the platform and then two masts on the back of the platform for rib bolts. The feed and rotation controls at each operator’s station include a latch control for drilling. The latch control will allow the operator to lock in the feed and rotation once the hole has been collared, allowing the operator to move on to the next hole. The rear of the machine is equipped with material handling. There are two material pods with winch controls as well as a mesh rack that includes mesh lift, mesh tilt and mesh sump. The six-head roof bolter allows fewer operators to drill and install roof and rib bolts, which in turn lowers the miners’ roof exposure per cut. This design reduces the operator’s exposure from the inherent pinch points and rotary hazards once he has engaged the latch drilling. Therefore the machine will help to decrease the time to bolt a cut, improving productivity while enhancing the ability to operate the machine safely. INTRODUCTION When mining underground it is necessary to support the roof quickly to prevent it from collapsing after an area has been mined. Since the 1950s, the primary method for supporting the roof has been the installation of roof bolts. Roof bolting is one of the most basic functions yet one of the dangerous jobs in the underground mining operation (1). The Mine Safety and Health Administration’s (MSHA) Health and Safety Accident Classification injury database showed an average of 660 roof bolter operator accidents per year over a 5-year period (1999-2003) (2). The numbers show that roof bolting is the most hazardous machine-related job in underground mining. It represents 39 percent of all machine-related accidents in underground coal mines. In 1993, the U.S. Bureau of Mines conducted a study that has shown the activity of drilling as the most hazardous job task performed by a roof bolter operator, accounting for 31 percent of all roof bolting injuries (3). Almost half (46%) of these drilling injuries were due to falling rocks or coal from the roof. All of these injuries occurred under supported roof. The majority of these injuries (about 99%) are not caused by a major roof collapse but from falls of smaller rock from the immediate roof. This type of roof failure has also been termed “skin fall.”"

Jan 1, 2017