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By R. J. Gray

Oxidation of coal can best be described as a process of deterioration, since most of the uses of coal, such as for fuel and by-product chemical and coke production, are adversely affected by coal oxidation, and the inclusion of oxidized coal in most coal products detracts from their value. There are probably many mechanisms of coal oxidation, and the ways oxygen molecules combine as complexes with coal macromolecules to form new substances have been dealt with and speculated upon by many workers1)* but are not dealt with in the present work. This study deals with tests and methods of detecting oxidized coal, with particular emphasis on the microscopically discernible changes that accompany the chemical and physical changes that affect the technological properties of coal during oxidation.

Jan 1, 1974

By McGuirk. C. H.

The Port of Conneaut, long regarded as a leader in advanced bulk material handling technology, recently incorporated into its existing facility a new, multi-million dollar coal transfer-storage system. While the basic principles of conveyorized bulk material handling remain unchanged in the new system, design modifications such as rotary dumping of railroad cars, automated car feed to dumper, belt rip detection for conveyor belting, bucket wheel continuous production, and other innovations make The Pittsburgh and Conneaut Dock Company's complex worthy of classification as the "Port of Tomorrow - Today". The Pittsburgh & Conneaut Dock Company, the "Port of Tomorrow - Today", 1s a bulk materials storage and transfer facility located on Lake Erie, 68 miles east of Cleveland, 30 miles west of Erie, PA., and 138 miles north of Pittsburgh. Figure 1 shows an aerial view of the facility. It is designed to handle over 25 million tons per year of metallurgical and steam coals, direct shipping ore, fine ores, concentrates, pellets, limestone, and dolomite. Inbound shipments of iron ore and limestone are received from Minnesota, Michigan, Labrador, and Quebec. Coal arrives from Pennsylvania, Ohio, Virginia, West Virginia, and Maryland. Rail service is provided by the Bessemer & Lake Erie Railroad Company.

Jan 1, 1980

By R. Day

Nahcolite is a naturally occurring sodium bicarbonate mineral found principally in the Piceance Creek Basin of northwest Colorado. An 8-m thick nahcolite bed, 610 m below the surface, is the target of this first commercial nahcolite mine. A chamber and pillar mining system is developed by solution mining parallel 8-m tall by 18-m wide by 450-m cavities initiated along horizontally drilled holes. Hot water leaching, cooling crystallization and flash drying is the process. The sodium bicarbonate product is consumed by the baking, animal feed, industrial and acid rain abatement markets. A project overview, emphasizing the combination of horizontal drilling and solution mining technologies, will be presented.

Jan 1, 1994

By Clément F. Bernier

One of the chief sources of the world's supply of asbestos lies in a belt of ultrabasic rocks which runs northeastward through an area called the Eastern Townships, south of the St. Lawrence River in the Province of Québec. The productive portion of this belt extends from the town of Asbestos in the south, for a distance of some 9,5 km to beyond the village of East-Broughton. The first discovery of asbestos in this region was made in 1874. Only crude fibre was produced until 1888 when the first mill was erected near the town of Black Lake. Since the inception of the industry, almost 100 years ago, no less than 100 different compa¬nies have been formed and 46 different mines have been operated. There are presently 5 active companies in the area providing direct employment for 4100 workers, down from 6000 during the seventies.

Jan 1, 1984

Mine design and selection of ore processing capacity depend upon a correct estimate of the grade-tonnage distribution. The estimate must reflect what can be recovered and processed. The McCoy/Cove operation in central Nevada, USA, is a gold and silver mine. Case studies of recoverable reserve estimation for gold and silver were made using multiple indicator kriging and the log-affine variance correction. From this model, the grade-tonnage distribution was constructed. Optimal pits were generated by utilizing the distribution, and the results were compared with the pit generated by ordinary kriging. Studies indicate that the proposed method for multi-metal recoverable reserve estimation is more accurate than ordinary kriging in terms of both tons and the grade. Using recoverable reserves for mine design will maximize global recovery of mineral resources.

Jan 1, 1997

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

Lithium-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. Lithium-ion batteries can go through a thermal runaway under different abuse conditions including thermal abuse, mechanical abuse, and electrical abuse, leading to a fire or explosion. The NIOSH Mining program is conducting research to prevent and respond to lithium-ion battery fires for 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 powder, and water mist for lithium iron phosphate battery pack fires. The effects of activation time and release time of the water mist system on the suppression of lithium-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.

Feb 17, 2024

By James N. L. Lukanuski

Three porphyry copper districts in southern Arizona are partly overlain by post-ore fanglomerates which share certain physical and petrologic characteris¬tics and which may comprise a distinct and significant class of rock. These units are the Locomotive fanglomerate of Ajo, the Helmet fanglomerate of Twin Buttes-Mission-Pima, and the Cloudburst formation of San Manuel-Kalamazoo, termed "Locomotive-type fanglomerates" herein. Post-ore units at Poston Butte and Lakeshore, Arizona, and Sar Chesmeh, Iran, also appear to fit this class. "Locomotive-type fanglomerates" are composed of poorly sorted conglomerates, lenticular sandstone beds, andesitic to rhyolitic flows and tuffs, and unique monothologic landslide breccias. They contain fragments of holyokeite - - a rare oligoclase lava of porcellaneous appearance. Their basal contacts are considered to be depositional and overlapping, sometimes complicated by later low-angle faulting. They arc quite different than the younger Cila, Pantano, and most "Whitetail" alluvial beds, and the older Amole, Recreation, Claflin Ranch, etc. elastics; in particular they are thinner and less widespread. Their ages are Eocene to late Oligocene. "Locomotive-type fanglomerates" may be genetically related to porphyry coppers as products of subsequent differentiation and volcanism, and sedimentation in short-lived basins of restricted area and extreme relief. They might be utilized as reconnaissance guides to target areas and as structural guides within target areas in the southwestern U.S., Northern Mexico, and elsewhere.

Jan 1, 1975

By James J. Scott

Shale formations are the Nemesis of the Mining Engineer. Shales react to changes in environment in the most unusual and unpredictable manner. Increase in temperature may cause spalling, increase moisture and compression induced fractures may occur, and if a full face is exposed it may deteriorate due to atmospheric exposure. Combine only small amounts of shale in layered fashion with hard brittle competent rock and the whole structure may be fractured and fail due to stresses generated in and around the shale. In this paper the author will discuss failure mechanisms encountered under various field conditions and remedial action which may be employed by the engineer.

Jan 1, 1969

By Osvaldo A. Bascur

Most mining and metallurgical plants have developed predictive maintenance policies based on statistical analysis and special techniques, like vibration analysis, oil and lube analysis for critical equipment. Process control strategies have also been installed in several metallurgical sites. These control strategies require instrumentation maintenance from local personnel. The availability of real time and process history to identify the most critical part of the processing system from mechanical integrity is a must for global plant optimization. Specialized performance control monitoring algorithms are required to justify their existence and contribution to the bottom line. Emerging technologies are combining these techniques into a single total plant system. Tools are required to assist in troubleshooting and adapting these process control instruments and strategies. The key is the plant equipment and process control availability and utilization rather than just maintenance.

Jan 1, 1997

By R. Kramer, A. Habibi

"Diesel Particulate Matter (DPM) measurements were taken at Tronox’s Westvaco Trona mine in Wyoming. Both shift-average and real-time monitoring using Elf pumps and Airtec analyzers, were used. The mine’s underground transportation fleet consists of more than 250 diesel-powered vehicles. A vehicle monitoring log tracked fleet usage during the test; logged data consisted of vehicle type, direction of travel, and time. The log was used in analysis to determine the DPM spread rate, of normally operating equipment, in the different entries with respect to vehicle location. Airflow velocity measurements at the stations were taken during the survey. The survey results also identified vehicles with higher emission rates. An ECOM gas and a MAHA DPM analyzer, both located in the mine’s underground emission shop, were used to obtain various vehicle emission rates. The correlation of the workshop and field measurements was investigated with regard to the machine activity, fuel usage and atmospheric conditions. The results were used to identify and execute a ventilation project to reroute 45% of diesel shop air back to intake entries, by interlocking an automated door and a regulator. The result is reduced DPM downstream. INTRODUCTION DPM has been classified as a potential occupational carcinogen by the National Institute for Occupational Safety and Health (NIOSH).The Mine Safety and Health Administration (MSHA) rule governing DPM exposures in metal and nonmetal mines cites total carbon (TC), a summation of elemental carbon (EC) and organic carbon (OC) obtained by NIOSH Method 5040, as a surrogate for determining DPM exposures (Noll, 2006). MSHA personnel use the 1973 sampling criteria outlined by the American Conference of Government Industrial Hygienists (ACGIH) for collecting compliance-based respirable and inhalation samples in metal/nonmetal mines. Instrumentation developments are allowing improved real time monitoring of ventilation parameters. DPM is within the aerodynamic particle size range of the samplers used for respirable and inhalable dust measurements. If a sampler used by MSHA to collect inhalable or respirable dust samples in underground metal/nonmetal mines was used to collect DPM, both the DPM and mine ore dust would accumulate on the sample filter (Noll, 2006). To comply with the requirement and lower the DPM exposure, mines are implementing a variety of control technologies such as emission based maintenance programs where adjustments or repairs are performed on the vehicles (McGinn, 2000)."

Jan 1, 2016

By S. E. Valji

Clay slurries are normally dewatered using flocculents like sulfuric acid or aluminum sulfate. This type of flocculation is based on the electrolytic mechanism. For certain clay dewatering applications, this method of flocculation is unsatisfactory. Flocculation, based on the bridging mechanism, using organic polymers has been utilized to overcome such problem situations. This method of flocculation offers solutions not possible by previous methods. Normally these flocculents are used to assist dewatering. In this case, not only is dewatering promoted, but also further processing is assisted by a change in the dilatant character of the filter cake that is formed. Discharge of filter cake is easier, extrusion of filter cake on to conveyor dryer is possible or improved, and heat transfer and drying rates of the extruded filter cake are substantially higher. Both natural and synthetic organic polymers have been utilized for this purpose. Selection, application techniques, and economics are described.

Jan 1, 1965

By Richard Campbell, MEHMET KIZIL, Ismet Canbulat, Serkan Saydam

The design and effectiveness of ground consolidation to regain stability of longwall faces vary widely and are often based predominantly on-site precedence or what were considered successful applications at other sites in similar situations. Little is known regarding product migration characteristics or change in rockmass conditions as a result of the application of consolidation chemicals. This paper presents the in-situ testing rationale designed and implemented recently across several longwall operations in the Bowen Basin, Queensland, Australia to provide quantitative measurement of the actual zone of influence of various resin injection products. Product migra- tion was physically measured by monitoring the change in rockmass temperature as a result of the exothermic chemical reaction of the various strata consolidation chemicals used. In conjunction with strata coring and Lugeon transmissivity testing pre- and post-injection to characterise the improvement in rockmass conditions due to consolidation product injection. The results of the testing programme, migration measurements, and rockmass assessment are presented, along with a discussion on how site- based Rock Mechanics Engineers can incorporate the data into the design of strata consolidation plans.

Jun 25, 2024

By M. Misra

The dissolution of mercury during gold cyanidation is the cause of many environmental, health and processing problems. A study was undertaken to find a suitable reagent for the removal of mercury bearing complexes from the leach liquor. Removal of mercury from synthetic solutions and process water from a gold mine was investigated using sodium sulfide, sodium and potassium dimethyl dithiocarbamates as precipitating reagents. The results have shown that efficient mercury removal could be achieved by addition of potassium dimethyl dithiocarbamate (KDTC), by formation of stable mercury compounds. The resultant mercury-potassium dimethyl dithiocarbamate precipitates are stable under present plant operating conditions and do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is also possible to stabilize the mercury in the heap during cyanidation by adding dimethyl dithiocarbomate.

Jan 1, 1998

By F. Daviess

A requirement for geological controls during orebody modeling results from the recognition of heterogeneous geological characteristics and/or abrupt variations in orebody geometries. While purely statistical methods are often sufficient for modeling uniform homogeneous deposits, and the only recourse for many that are extremely complex, geological interpretations can be extremely valuable as controls during the modeling process. The advent of relatively inexpensive, sophisticated graphical computer hardware and software has focused considerable attention on the three dimensional visualization capabilities now available to the mining industry. Orebody geometries can be easily imported into many systems as wireframe or solid models, rendered with shading and color, rotated in space, exploded into composite parts, zoomed into and otherwise displayed to awe any audience. The requirements for an initially meaningful, accurate, geological interpretation are sometimes lost when the focus is on an apparently complex, highly resolved end product. Details of the initial data and sensitivities of modeling assumptions are not always sufficiently scrutinized. Software capabilities have extended the geopoetic license into three dimensions. The new tools, while greatly facilitating model construction and rendering, have done little to expedite basic data preparation and analysis. This paper attempts to briefly summarize the purpose and method of the construction of geological controls. The examples selected are from wire­framing and block modeling; application software processes commonly used in the mining industry today.

Jan 1, 1992

By S. C. Termes

As part of an effort to provide basic data on the fundamental scientific and engineering principles of minerals beneficiation, the Bureau of Mines is conducting research on the flocculation of mineral fines. This paper presents results of studies using crosslinked starches containing carboxyl, diethanolamine, iminodiacetic acid, and xanthate groups to flocculate hematite, goethite, chromite, manganrte, pyrolusite, cuprite, and cassiterite fines. The carboxyl and xanthate derivatives flocculated all minerals except cassiterite; the latter was flocculated by only the diethanolamine derivative. The iminodiacetic acid derivative flocculated hematite, goethite, chromite, cuprite, and pryolusite fines. Zeta potential measurements were made to help define the reaction mechanism responsible for flocculation. These measurements indicate that electrostatic attraction probably is not involved, except possibly in the case of the diethano lamine derivative. The separation of hematite from quartz by selective flocculation with chelating cross- linked starches under two pH conditions and with two dispersing agents is described. Best recoveries and grades were found when either the carboxyl or xanthate derivatives was added at the natural pH of the pulp in the absence of a dupersing agent.

Jan 1, 1983

By Stephen W. Denton

Planning a mining operation in Alaska will involve the investigation of many parameters common to mine planning anywhere. However, there are some unique circumstances that must be recognized when one considers development of mining operations in Alaska. This paper will not attempt to provide a blueprint for mine planning in Alaska, but hopefully will provide a better understanding of the truly unique nature of the northern latitudes. Given this understanding, the mine planner can better assess the potential hurdles along the road to a successful mining operation. The regulatory trend towards uniform standards for mining throughout the United States exemplifies the necessity for Alaska to prove its unique position in the natural resources picture. The factors which make Alaska truly different from the "Lower 48" can be summarized by four points 1) Remoteness and Size 2) Seasonable Extremes 3) Geologic Immaturity 4) Vegetation and Wildlife

Jan 1, 1984

By Wei Li

Carbothermic reduction kinetics of ilmenite concentrates catalyzed by sodium chloride and the microwaveabsorbing characteristics of the resulting reductive products were investigated; the reduction degree of the reaction was deduced to be . Results show that the activation energy is 112.03 kJ/ mol when NaCl is used as catalyst, lowering to 23.11 kJ/mol for the final stage activation energy using sodium silicate as a catalyst. There is a sharp change in the reduction rate constant at temperature ranges of 1,223 K - 1,273 K and 1,373 K - 1,423 K. Microwave-absorbing characteristics of reductive products were measured by the method of microwave cavity perturbation. It was found that microwave-absorbing characteristics of reductive products obtained at temperatures of 850° C, 1,100° C and 1,150° C show sharp changes. Through X-ray diffraction (XRD) characterization, it was found that the formation of Fe occurs at a temperature of 900° C during the reduction process of ilmenite concentrate. The decrease of FeTiO3 content results in the decrease of microwave-absorbing characteristics, while the increase of Fe content gives rise to the increase of microwaveabsorbing characteristics. The decreasing trend is larger than the increasing trend, which is the main reason for the sharp changes in the microwave-absorbing characteristics of reductive products at the temperature range of 850° C to 900° C. When the decreasing trend is smaller than the increasing trend, it becomes the main reason for the sharp changes in microwave-absorbing characteristics of reductive products at the temperature range of 1,100° C to 1,150° C. Kinetics results show that sodium chloride can catalyze the carbothermic reduction of ilmenite, and microwave-absorbing characteristic investigations indicate that microwave heating can be used in the carbothermic reduction of ilmenite.

By W. F. Visser

The growing availability of information and data analysis capabilities provides new opportunities for improving the performance of operations. By using real-time measurements and artificial intelligence, it is possible to respond faster to changing conditions, while accurate and timely information permits the rapid evaluation of changes and fast business improvement decisions. This paper presents a blueprint for system alignment, organizational design and management practices to leverage these developments in performance-driven operations management in mining and mineral processing.

Anomalous geologic or stress conditions ahead of the longwall face can cause great harm to both the individual miner and the mining operation as a whole. The U.S. Bureau of Mines has been developing seismic tomography techniques to image the panel ahead of the face. This paper presents the results of a field effort in which a 60-m (200-ft) segment of a longwall panel containing a fault zone was surveyed daily as the face approached. Stress distribution, geologic structure, and dynamic elastic properties within the panel were plotted and compared to static laboratory measurements. The surveys successfully imaged an anomalous stress concentration, likely influenced by the presence of the fault zone. The calculated dynamic physical properties generally agreed with laboratory measurements.

Jan 1, 1995

By Pawan Bharadwaj, Wim Mulder, Thomas Tscharner, Guy Drijkoningen, Rob Jenneskens

"The Earth’s properties, composition and structure ahead of a tunnel boring machine (TBM) should be mapped for hazard assessment during excavation. We study the use of seismic-exploration techniques for this purpose. We focus on a seismic system for soft soils, where shear waves are better and easier to interpret than compressional waves, as has been shown over the last decade. The system is intended to be deployed on the machine’s cutter head, with a few seismic sources and sufficiently many seismic sensors to tackle spatial variability and noise characteristics. An important property of the newly developed system is its ability to process data with very little human interaction. Images need to be available in near real time, without human interactions slowing down the imaging process. This can be achieved by employing Full Waveform Inversion, which minimizes the difference between modeled and observed data. Because this method may suffer from local minima in the cost function if the data lack low-frequency information, we employ a dedicated seismic source that can generate sufficiently low frequencies for the relevant length scales. With data acquired in a number of field settings that mimic realistic TBM configurations, we show that the designed seismic system can successfully look ahead of the TBM and offers a valuable capability to support decision-making during tunnel excavation. INTRODUCTION While excavating a tunnel with a Tunnel Boring Machine (TBM), the geology and the ground conditions along the planned tunnel trajectory need to be investigated in order to safely and efficiently carry out the underground operations. This entails detecting the occurrence of boulders, foundations, pipes and faults, necessary to prevent hazards and time-consuming delays in the tunnel boring operations. In order to facilitate ground prediction ahead of a TBM, techniques as used in seismic exploration can be deployed. Two components common to seismic-exploration techniques are data acquisition and processing, the latter including inversion. We will discuss each of these for the application to tunnel excavation with TBM, in particular for soft soils."

Jan 1, 2016