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By D. P. R. Smyth

The limestone reef reservoir at Swan Hills consists essentially of a "buildup" of successively smaller atoll-like layers. Precipitation of calcium carbonate within the lagoonal area of each layer essentially kept pace with growth of the outer organic lattice. Within the reef mass, six de-positional environments characterized by specific suites of fossils (or fossil fragments) and associated limestone textures are recognized as follows: ( 1) Aerated moderately agitated water of normal marine salinity (widespread shelf or submerged reef-built platform). Thamnopora-type corals, Amphipora, "pancake" stroma-toporoids, crinoids, articulate bra-chiopods, rare rugose cup corals, and ostracods occurs in light gray-buff skeletal microgranular limestone of low permeability. (2) Semi-stagnant quiet water of normal marine salinity (leeward side of reef). Crinoids, articulate brachio-pods, rare thamnopora-type corals, Amphipora, pancake and bulbous stromatoporoids, rugose cup corals, ostracods and gastropods occur in impermeable dark brown argillaceous skeletal calcilutite with thin black bituminous shale beds and rare dark chert nodules.

Jan 1, 1961

By Donna lynne Anderson

This report documents the status of a laser-based underground guidance system for tracking and controlling the movements of underground mobile mining equipment. This research is part of a multiple project effort at the U.S. Bureau of Mines to increase mine safety and efficiency by developing technology for computer-assisted mining. Guidance systems, which can track and control the movements of underground mining equipment, are essential during computer-assisted mining operations. A continuous mining machine at the Bureau's surface test facility served as the test-bed for initial development and experimentation of this guidance system. Subsequently, a continuous mining machine in an underground mine served as the platform for in-mine experimentation. The first section of this report includes details of the laser sensors, communication network, and computer hardware. The next section includes experimental results, which show the system capable of accurately tracking and controlling the tram maneuvers of a continuous miner underground. The final section discusses conclusions and recommendations.

Jan 1, 2010

By Y. Zedan

Cutting fluids play important roles during machining, including the reduction of friction and temperature. Using a cutting fluid, however, degrades the quality of the environment and increases machining costs. The aim of the present research work is to study the effect of cutting fluids and their interactions with cutting parameters on the quality of holes during the drilling of 6061-T6 aluminum alloys. The lubrication types and modes investigated are dry machining, flood lubricant machining and minimum quantity lubrication machining (MQL), while the part quality criteria include the surface finish, the dimensional accuracy, and burr forms and sizes. A scanning electron microscope (SEM) was used to investigate the formation of built-up edges (BUE) in the drill flutes as well as the surface texture of drilled holes. It was found that dry machining and MQL machining can produce parts having quality levels comparable to those obtained in wet machining, when using the optimal cutting conditions.

Jan 1, 2011

By Elimame Elaloui, Kais Elghniji, Constantin Virlan, Aurel Pui, Chaima Ouled Amor

Separation and identification of minerals composing the Tunisian silica sands have been conducted by acid etching and hot filtration/sedimentation (HFS) without affecting the quartz component. It was found that the hot acid etching process is an effective method to separate quartz and clay minerals in the silica sand. The SEM micrographs of the silica sand show rough surface and some cracks with irregular shapes. The surface becomes clean and smooth after acid etching process. After chemical dissolution, the clay minerals were recovered by hot filtration following by sedimentation at low temperature. FT-IR, EDS maps, and secondary electron (SE) analyses of separated clay minerals reveal the presence of Fe2O3, montmorillonite, and kaolinite minerals. The LIBS analysis of clay minerals shows the presence of Al, Fe, Ca, Al, and Mg. The sequential etching process can be introduced in the purification methods as an effective way to separate quartz from clay minerals.

Jul 29, 2020

By Bruce Vandre

Jan 1, 1985

By Phyllis A. Lyday

Jan 1, 1985

By Sue W. Wells, James J. Moore, Stephen D. Lynch, R. Hunter White

This paper describes the products and services that Phelps Dodge Corporation desires from solvent extraction reagent suppliers and the partnering relationship that Phelps Dodge wishes to develop with these suppliers. Product topics include: 1) manufacturing concerns, 2) product and process quality control reporting and 3) reagent customizing to meet individual plant needs. Service subjects include distribution, delivery time, emergency re-supply, terms, and tailoring technical support. The partnering relationship discussion reviews mutual benefits, communications, reliability, cross-functional teams for problem solving and developing new opportunities, and long-term commitment.

Jan 1, 1994

By Michael S. Wieland

The work-principle method was developed for theoretically resolving toxic fumes from non-ideal charge formulations. The whole description of a wanted process refers to macroscopic changes resulting from removing and imposing constraints that work one at a time to chronologically render trajectory terminal (key) states. The trajectory resolution utilizes a thermodynamic quasi-potential or negative work function, and numeric results require some appropriate standard thermodynamic (equilibrium) reaction code TDRC. The underlying method is unable to restrict reactions, tailor the work output or resolve states within the trajectory transitions, so the trajectory terminology is used somewhat figuratively. The work-principle model has the working fluid (reaction material) interacting with a tremendous reservoir (chamber air and walls), while forecasting the work performed upon a mechanical agent.

Jan 1, 1998

Jan 1, 1938

Reduce permanent hearing losses to bulldozer operators. Approach Two types of noise control packages have been developed, that can be readily fabricated and installed into bulldozers by mine personnel. How It Works Both of the noise control packages reduce the noise exposure of the operator by two techniques, blocking the noise paths or absorbing the sound before it reaches the operator. Both airborne noise paths and noise paths through the machine are blocked. One noise control package is designed for bulldozers having ROPS (Roll Over Protection System), but no cab. The other package is designed for bulldozers having ROPS

Jan 1, 1981

A major Brazilian iron ore producer, SA Minerayao da Trindade (Samitri), has recently completed modifications at two operations which involve the use of Derrick high frequency vibrating screens. Details of these modifications are presented, together with a review of product quality improvements.

Jan 1, 1997

By Nathanael Wagner Sales Morais

Os aços maraging tem grande importância tecnológica devido sua aplicação nas industrias aeroespacial e nuclear. Uma das aplicações para esse material é a fabricação de cilindros de alta resistência pelo processo de estampagem profunda, logo o conhecimento da textura cristalográfica torna-se fundamental. Este trabalho investigou o efeito da laminação à frio seguida por um recozimento sobre a microestrutura, textura e anisotropia plástica no aço maraging 350. A anisotropia foi medida pelo cálculo dos coeficientes de Lankford e dos coeficientes de anisotropia normal (Rm) e planar (?R). Os resultados mostraram o aumento na deformação a frio gera um aumento na intensidade da fibra acompanhada de um aumento no valor de Rm. As análises metalográficas mostram que maiores reduções induzem à um precipitação intermetálica após o recozimento.

Aug 8, 2018

By Barry Welch, Kai Grjotheim

"The capital intensive nature of the present process for aluminium smelting, the low productivity per unit reactor, and pressure to reduce the electdcal energy demand have motivated the search for an alternative process. Optional routes include carbo-thennal reduction of alumina (using an alloy phase immediate), chlorination followed by electrolysis of aluminium chloride, and electrolytic decomposition of alumina using inert electrodes. Materials performance and reactor design constraints have been a major limitation for alternatives. However parallel research has led to considerable advances in the process efficiencies and scale of both the Bayer process and the Hall-Heroult cells.Future development of alternatives is dependent on breakthroughs in Materials Science such as the development of stable conducting anodes and stable wettable cathode materials. However if successful it is probable that some spin-offs will be retrofitted to existing cells. Therefore the basic Hall-Heroult technology will continue as the dominant process for at least the next half century.IntroductionThe present Bayer/Hall-Heroult process for production of aluminium is just over 100 years old. Frequently, during the century of its technological development questions have been raised as to whether it is the ideal route for metal production. The questioning was particularly intense in the period between the mid-1950s and the mid-1060s when the limitations of the Hall-Heroult electrolytic stage were evident. Then the cells were only 30 to 35 % efficient with respect to the utilisation of the hydro-electricity (requiring 16 18 kWh/kg, thus making it strongly dependent on cheap electrical energy), while the size of cells being installed were 80 to 130 kA. Hence the process was capital intensive, the productivity per reactor volume low, and the process was labour intensive (requiring about 15 man hours per tonne of aluminium). In addition, the use of pitches for Soderberg anodes and the fluoride electrolyte were creating problems through emission. At that time material science had paid little attention to the manufacture and use of carbonaceous materials or the development of alternatives that were corrosion resistant to cryolite or liquid aluminium. Hence cell lives were short - typically 600 to 1000 days - thus adding to operating costs. Thus the grass over the fence, as foreseen in 1960s vintage crystal balls appeared much greener for alternative processes."

Jan 1, 1988

By R. Neumann, O. Gomes, S. Gaydardzhiev

"Phosphorus in iron ores is considered as a deleterious component to iron making reflecting in cold shortness of the produced steel. The present study investigates the phosphorus migration pattern resulting from thermal treatment of an oolitic-type iron concentrate with and without additives. To this end focused mineralogical and microscopic observations were performed. The results have shown that roasting with alkaline additive drives phosphorus outside the hematite hosting mineral, however it remains evenly distributed inside the volume of the oolites. It penetrates inside the newly formed cementing phases of Al- Na-Si-Fe-type and also fills the interstices between the crystals. Other than phosphorus, aluminum, calcium and iron tend also to migrate towards the amorphous-type cementing phase. Finally, the possibilities for P removal by means of magnetic separation and acid leaching of the roasted concentrate were evaluated. The obtained final product presents a standard iron concentrate suitable for steelmaking with its phosphorous being dropped from 0.71% to 0.05% and iron grade of a nearly 66% being reached. INTRODUCTIONSignificant proven reserves of iron ores are still not exploitable due to lack of an economically viable and efficient technology for removal of phosphorus. Among them are the oolitic iron ores with high phosphorus which are estimated to nearly 377 billion tons (Hernandez et al., 2012). Phosphorus is a deleterious component giving a cold shortness to steel and often is penalized if exceeding 0.07%. Most of the high-P iron ores are considered refractory since phosphorus is finely disseminated and is evenly met as phosphate groups inclusions inside the limonite structure. Studies on inclusion of phosphorus in artificially synthesized goethite have shown that it is adsorbed as [HPO4]2- groups bridging the adjacent iron ions (Parfit et al., 1975). The high-phos iron ore originating from Lisakovsk deposit, Kazakhstan presents a similar mineralogical issue because the quantity of P, met as solid solution, is substantially higher than the one in P-containing minerals. A potential reason for that is the ore body formation process from the slow deposition of iron-rich precipitates together with clastic erosional sediments in rivers. There is significant quartz and clays inside and around the oolites. The deposit contains about 1.7 billion tons of measured and indicated reserves at 35–41% iron and 1.1 billion tons of inferred ore have been delineated possessing nearly the same chemical composition (Golubovskaya, 2003; Kokal et al., 2003)."

Jan 1, 2016

By A. Noble

"In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. Alternatively, the organic efficiency parameter does consider process economics; however, it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach is introduced which reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure which reflects a better use of performance data. INTRODUCTION Partition curves are commonly used in the characterization, evaluation, and simulation of various physical separators. In mineral processing, partition curve analysis is routinely applied to hydrocyclones, screens, and density separators. Graphically, the partition curve depicts the recovery of particles as a function of a physical property on which the separation is based (e.g. particle density, size, magnetic susceptibility, etc.). Given the probabilistic nature of many real separators, the partition curve often exhibits a characteristic “S” shape (Fig. 1), similar to a cumulative normal distribution. Other geometric features of the curve are also depicted in Fig. 1, including the high and low closeout (or bypass) values, the midpoint slope, and the separation cut point (property value with 50% recovery). Partition curve analysis was originally proposed to evaluate coal washability (Tromp, 1937). Given the limited computational resources at the time, the analytical methods relied heavily on graphical construction and interpretation of the curve. Owing to the simplicity of the calculation and interpretation, many of these graphical approaches are still widely used for performance analysis today. The most common calculations are based on the slope of the partition curve at the midpoint. Increased slopes correspond to enhanced separation performance, since a perfect separation exhibits a stepwise transition from 0 to 1 at the desired cut point (i.e. an infinitely large slope). One common formulation of this slope, the Ecart Probable (Ep), is derived by evaluating the slope between the 25% and 75% recovery points:"

Jan 1, 2015

By J. Herbst, J. Groppo, A. Noble, R. Q. Honaker

"Coal and coal byproducts produced annually contain enough rare earth elements (REEs) to meet current U.S. demand. The REEs exist in the form of minerals, ion-exchanged elements associated with clays and chemically bonded elements within the organic coal matrix. Researchers at three universities have collaborated to evaluate the effectiveness of existing physical and chemical concentration processes for the recovery of the REEs. The efforts have found that physical separation processes can increase the total REE content in the thickener underflow material collected from a Central Appalachian coal cleaning facility from around 300 ppm to values greater than 17,500 ppm on an ash basis. On the other hand, leaching was effective in recovering REEs from coarse middlings materials collected from multiple coal basins as indicated by recovery values exceeding 80%. Based on material characterization data and process evaluations conducted for several potential feed coal sources, economic recovery of the REEs will require byproduct production of both clean coal and REE concentrate using a process flowsheet that is unique for each source. INTRODUCTION Recent studies initiated by NETL showed that U.S. coals contain significant amounts of rare earth elements (REEs), suggesting that rare earth minerals (REMs) and/or REEs can be produced as byproducts [1]. According to the report, the richest source of REEs is the Central Appalachian coal. At present, there are 208 coal preparation plants located in the region (WV, KY, PA, VA, AL, TN) with a capacity of 166,495 tons/hr or more than 1 billion tons annually [2]. If only a portion of these plants are retrofitted with advanced separation processes, the U.S. coal industry can become a significant producer of RE minerals as byproducts. An inherent advantage of becoming a byproduct producer of REEs is that no mining cost needs to be part of the product cost. Other researchers have also shown that coal can be a significant source of REEs. The average sum of the rare earth plus yttrium (REY) concentration of the world coal is approximately 68.5 ppm, which is lower than the corresponding upper crustal concentration (UCC) (168.4 ppm). However, the average REY content of the mineral matter in the world (404 ppm) and U.S. coals (517 ppm) are 3 times higher than the average UCC. Some of the mineral matter in Russian and Chinese coals have REY concentrations in the range of 0.68 to 2.03% and contain a better source of higher value REYs than many primary rare earth deposits [3]."

Jan 1, 2017

By Philip W. Holland

The U.S. Bureau of Mines has designed and built an inexpensive, weatherproof, temperature-controlled cabinet to provide temporary housing for analytical instrumentation. The cabinet consists of an inverted Styrofoam ice chest, an electric fan for air circulation, and a proportional temperature controller equipped with a thermistor sensor and a light bulb as the heater. The cabinet provides a constant-temperature environment for a moisture analyzer and a strip chart recorder when outside temperatures range from -SO to 21° c.

Jan 1, 1993

By Greg Wyartt

"At an Australian iron ore open-cut mine, 129 separate blast patterns (consisting of 38.5 million tonnes /42.4 million US tons, equaling 28% of annual blasted tonnes) were initiated using electronic detonators. 87 patterns were designed as per site methodology using ‘vectorial’ initiation timing sequences (blast direction and relief specified only), while the remaining 42 patterns were designed with interactive initiation timing sequences - hole by hole sequencing based on the measured site specific primary shock wave (P-wave) velocity and distance between blast-holes. The intention of this project was primarily to reduce material size presented to the crushing circuit, and also to determine if productivity benefits could be obtained by the use of interactive timing."

Jan 1, 2017

By C. W. Whitten

Solis from an abandoned Pb battery processing facility were characterized prior to the selection of the extraction technique. Reflected light microscopy and electron beam methods were used to locate Pb-bearing phases and to quantify the compositions of the phases. It was found that the soils are composed primarily of quartz and feldspars with minor amounts of iron and titanium oxides. Lead is primarily present as an oxide or sulfate that is associated with the silicate minerals. Specific phases identified were PbO; Pb02; cerrusite, PbCO3; angleslte, PbSO4; galena, PbS; and magnetoplumbite, 2PbO3Fe2O3; or plumboferrite PbO2Fe2O3?

Jan 1, 1989

By Robert K. Koch

The Bureau of Mines investigated separating HF from HF-SiF4-H2O mixtures by passing the mixed gases through a sodium fluoride slurry in an airlift scrubber and forming a mixed precipitate of NaHF2 and Na2SiF6. The oven-dried precipitate was thermally dissociated in two stages. The first stage was carried out at 400° C and dissociated NaHF2 to NaF and HF. Condensation and analysis of the evolved HF proved it to be 97 to 99 weight-percent HF containing 0.79 to 0.99 weight-percent H2O and 10 to 93 ppm silicon. The second stage was carried out at 700° C and dissociated Na2SiF6 to NaF (for recycle) and SiF4. The quantity of HF recovered from gaseous HF-H2O-air mixtures decreased with increasing relative H2O concentrations. Air was beneficial when scrubbing extremely dilute wet HF gases. At HF partial pressures of 0.24 and 0.013 mm Hg in the scrubber entrance gases, HF partial pressures of 6.2 x 10-4 and 9 x 10-6 mm Hg were obtained, respectively, in the scrubber exit gases. Scrubber efficiencies were 99.7 and 99.3 percent.

Jan 1, 1966