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According to the previous research, it is found that the thickness of cover is mostly less than 100 m for highwall mining system. However, for most of the Chinese surface coal mines, the mining depth is over 150 m; on the other hand, the shovel-truck is the most common mining technology. As a result, a lot of residual coal will be remained around end-walls. Considering these facts, the calculated methodology of highwall mining system under thick cover is presented in this paper. Meanwhile, numerical simulation of highwall mining system under thick cover was carried out. The outcome shows that the calculated methodology for pillar stability of highwall mining system under thick cover presented in this paper is acceptable. In other words, the highwall mining system is feasible to extract the residual coal around end-walls in Chinese surface coal mines. Thus, not only coal recovery ratio can be improved, but also can increase the production life of surface coal mines in China.

Jan 1, 2012

By F. Habashi

The phosphate fertilizer industry is at present based mainly on the use of sulfuric acid. This technology results in the generation of large amounts of radioactive gypsum that represents disposal and environmental problems. Also it involves the use of expensive reactors for acidification that necessitates the frequent replacing the damaged agitators. Applying hydrometallurgical techniques such as in-situ, heap, or vat leaching to phosphate processing could solve these problems. In this case, however, nitric acid must be used and dicalcium phosphate (40% P2O5) may be obtained as a final product. It is insoluble in water but soluble in citric acid and is an excellent fertilizer. This technology does not interfere with uranium recovery if desired. In addition it permits the recovery of rare earths which are otherwise lost in the gypsum.

Jan 1, 2011

Automation in underground mining enhances safety and leads to economic efficiency. In the past many efforts have been made on the automation of longwall shearer operation. With respect to the ultimate goal of automation, ie self controlled operation, coal bed boundary detection is one of the key problems. For longwall human labor is necessary in order to detect the exact position of the coal seam to be excavated. The authors present a sensor concept based on infrared technology and pattern recognition which will solve this problem. The very harsh underground conditions set high demands on the implemented sensors. The combination of infrared sensors and powerful processing algorithms is part of the innovative concept for automation of the new Eickhoff Bergbautechnik GmbH SL 750 shearer loader. The multi-sensor automation system EiControlPlus which is designed for the complete detection of the machine environment fills in the gap in the coal-excavation automation by building a recognition system that turns the shearer loader into an 'intelligent machine' which is capable of detecting the correct position of the seam to be excavated and thus enables human-free coal mining.

Dec 6, 2010

By J. E. Tiffany, J. J. McKitterick

"IntroductionThe Bureau of Mines is investigating the fundamental factors in breaking down coal at the face, which govern the production of lump coal in typical mines working, different coal beds. Tiffany and Nelson in 1923-21 conducted tests on methods of blasting and use of different explosives, in a mine working the Pittsburgh bed in Pennsylvania. They determined come of these factors quantitatively, and compared their results with those obtained when the regular mine practice was followed.Results of Previous InvestigationThe tests by Tiffany and Nelson showed that the use of the cartridge of smaller diameter than that used in mine practice, resulted in an increase of 5 per cent in the amount of lump coal passing over a 1-1/4-inch bar screen, with a reduction of 32 per cent by weight in amount of explosive required. On the other hand, they found that on reducing the weight of charge 20 per cent, and using the cartridge of larger diameter, the round would not throw down the coal satisfactorily.Experiments with ""snubbing"" showed a similar improvement in quantity of lump coal, end the coal that was blasted rolled forward into the working place. however, in recent tests at another mine where the coal Lad different physical characteristics, snubbing did not always result in the coal rolling forward, on account of clinging to the ribs, and was not found to be an advantage. Therein the writers of this paper recommend that tests be made before deciding upon the adoption of snubbing in a particular mine."

Aug 1, 1925

By Gerald E. H. Verbeek

As the number of driven concrete piles with Embedded Data Collectors increases, it has become possible to compare the widely used Beta Method to assess pile damage (using the change of pile impedance) with the so-called Measured Pile Integrity (MPI) method (a combination of two approaches using both the change of pile impedance and the change in pile pre-stress levels). After a brief introduction of both methods, this paper presents the outcome of that comparison based on data from more than 400 concrete piles driven in Florida, which brings into question the reliability of any damage assessment method based solely on the change of pile impedance (such as the Beta Method), especially to detect damage near the pile toe. Moreover the paper demonstrates the need to re-assess the damage classification used for the Beta Method as well as the use of Pile Driving Analysis (PDA) to detect pile toe damage.

Jan 1, 2011

By Willemijn Husslage

Tata Steel Group At a glance ? Part of the Tata Group ?Tata Steel Group: ?Fortune 500 company ?Top 10 global steel producer ?Annual crude steel capacity of 28 million tonnes ?More than 80,000 employees ?Manufacturing operations in 26 countries across 5 continents ?Serving customers all across the globe ?Turnover 2009-10: $22.8 billion

May 1, 2011

By K. Meyer

"INTRODUCTIONThe David Bell Mine Concentrator started production in April 1985. A staff of twenty-seven people operate and maintain the concentrator. The crew is grouped into the following main areas.16 Operators6 Assaying/Metallurgy/Refining/Clerical4 Maintenance people2 SupervisionOperating highlights of the following unit processes will be discussed in detail:Screening and ThickeningPre-aeration and CyanidationCarbon-In-Pulp Gold AdsorptionCarbon Handling andGold RecoveryFor a complete description of the concentrator, refer to the papers by: (1) C.V. Sibbald, Teck-Corona's Hemlo Mill, October 1984, (2) R.A. Ford, The David Bell Mine at Hemlo, From Exploration to Production, November 1987. For operating details of the grinding circuit and effluent treatment plant refer to papers by: (3) T.G. Smith, SAG Mill Experience at The David Bell Mine, October 1988, ( 4) AN. Veltmeyer, The Effluent Treatment Plant of The David Bell Mine, January 1989.TRASH AND CARBON SCREENSTrash ScreenThe vibrating trash screen is inclined at 5 degrees and is clad with a 28 mesh stainless steel cloth which is changed monthly during the SAG mill liner replacement/inspection shut down. Other screen openings and configurations have been tried and the screen has been by-passed to change the cloth ""on the fly"". These attempts resulted in fibres (usually wood) to report to #1 Carbon-In-Pulp (CIP) tank, where the fibres are trapped in the CIP launder screens, and downstream carbon handling screens causing serious blinding problems. The trash screen in a Carbon-In-Pulp (CIP) or Carbon-In-Leach (CIL) gold mill removes fibres before they:are reground in the ball millsaturate with gold bearing leach solutionplug launder screens in CIP or CIL tanksplug carbon circuit pipe screenstherefore the trash screen is best placed ahead of the thickener."

Jan 1, 1989

By R. L. Grayson, J. R. Warneke

The mining industry has searched for a message that will resonate with the public while focusing on the industry’s positive contributions to society. Thus far environmental groups remain unconvinced, and the public is still largely uninformed. In the authors’ opinion, a number of recent events and experiences have converged to help shape a more effective public communication on mining’s important role. This paper presents a fresh and cogent perspective on coal’s role in sustaining society by anchoring the message in a transparent material flow analysis that links coal’s impacts across a broad range of social and environmental aspects.

Jan 1, 2006

By Martin Murenbeeld

Outlook: Nine Bullish Arguments 1. Global fiscal and monetary reflation: PIIGS, US, etc. 2. Global imbalances: the dollar must decline 3. Global FX reserves are ?excessive?: diversification 4. Central bank attitudes to gold: now positive 5. Gold is not in a bubble: room to rise 6. Mine supply is flat: ?peak? gold? 7. Investment demand: long-run uptrend 8. Commodity price cycle: many years to run 9. Geopolitical environment: positive

May 1, 2010

By M. B. Wechsler

An analysis is developed for determining the maximum loading, as well as the potential uplift of the piles on bridge pier foundations. There are considered piers supported on two through seven rows of piles, and related to two simply supported collinear superstructures of any structural material. The study leads to different types of influence lines for various load combinations. For load combinations containing vertical loads only, the related influence lines are similar to those as for the bending moments of a virtual span covering the two actual spans, as well as the gap between the two superstructures; and, in this case, the heavier loads should be positioned in the vicinity of the pier. While, in the case when vertical loads are acting together with hori­zontal forces, the related influence lines will indicate where the heavier live loads should be positioned. And they will also indicate on which portions of the spans the live load should be avoided.

Jan 1, 1989

Objective The main purpose of this video is to teach mine rescue personnel certain aspects of rescue work that are not traditionally taught. These include the strain caused by working continually under adverse conditions; the "survivor guilt" that occurs from being spared the fate of one's deceased cohorts; and the posttraumatic stress that may be experienced during the sometimes lengthy task of recovering the victims' bodies. Background On November 20, 1968, an explosion rocked the Farmington No. 9 Mine in northern West Virginia (figure 1). The explosion killed 78 of 99 miners who were working in the mine, including all but one member of the mine's rescue team. Some 30 years after the event, researchers from the NIOSH Pittsburgh Research Laboratory (PRL) conducted a video interview with Danny Kuhn (figure 2), the only Farmington No. 9 mine rescue team member who was not working that day and who did not die in the explosion. According to the Mine Safety and Health Administration (MSHA), there are about 80 underground coal mine rescue teams in the United States, and according to the National Mining Association, there are more than 850 underground coal mines. This represents a significant decrease in both over the past decade. The low number of rescue teams is a concern because serious incidents, though fewer, still happen, and if a disaster occurs, there will be fewer rescue teams to respond. This would result in an increased need to use available human resources very efficiently. Much training to prepare these rescue teams still takes the form of what educators call "teaching to the test." In other words, teams practice in order to win mine rescue contests. This test-oriented approach has traditionally been augmented by interactions with others who have responded to real situations or by participating in actual incidents. Given few incidents and fewer rescue teams from whom to derive enrichment, the preparation of coal mine rescue personnel becomes a problem. Recently, more emphasis has been placed on active learning, such as working out problems in smoke. These sessions more nearly simulate the actual conditions that today's team members might rarely encounter. To properly prepare and retain the current coal mine rescue personnel who are left in the workforce, it is necessary not only to offer such hands-on experience, but also to replace the learning narratives that once were passed from team to team. The present video is intended to contribute in that capacity. Approach NIOSH researchers first learned of Mr. Kuhn in the fall of1998. Mr. Kuhn was contacted and agreed to an interview. An oral history interview was conducted with Mr. Kuhn in early November1998. After reviewing the videotape of the interview, researchers determined the content to be so rich as to warrant a second interview in a more formal setting. The second interview was done in early December 1998. During this interview, Mr. Kuhn spent about 2 hours describing the Farmington disaster, including the workplace climate leading up to the explosion, the events that took place in the 10 days after the explosion, and the nearly 10-year effort to safely and successfully recover most of the victims' bodies. The videotape of the second oral history interview with Danny Kuhn was reviewed and edited by NIOSH researchers for content. Careful attention was used to ensure that valuable information was presented, but within a reasonable timeframe. A detailed map of the Farmington No. 9 Mine was edited into the final video and used to highlight critical features as they were being described by Mr. Kuhn. Results and Accomplishments A 60-minute videotape and instructor's guide for use in safety training or other settings was completed. The target audience consists of all those who work in underground coal mines. This training video will help safety instructors better prepare mine rescue team members for the situations that they will encounter when engaging in extended rescue and recovery work. As a result of this expectations training, team members will be more likely to serve their

Mar 1, 2002

By R. Bruce Ferguson

"IntroductionThe Beaverlodge Operation of Eldorado Nuclear Limited is a uranium property located near the north shore of Lake Athabasca about 7 miles from Uranium City, Saskatchewan.The mill is a 2000 tpd carbonate leach operation producing a high grade yellowcake concentrate.The Lamella Thickener was purchased to replace a 55 foot conventional unit which had deteriorated beyond repair. The cost of the unit was considerably lower than for a conventional unit, installation was much simpler and the unit is much more compact allowing it to be installed in the mill basement and be insulated completely.The unit was sized according to the results of tests performed both by the supplier and Beaverlodge engineering staff. The supplier guaranteed overflow clarities of less than 100 ppm suspended solids. The Lamella thickener was developed by A. Johnson Co. of Stockholm, Sweden, is manufactured under license by Parkson Corporation of Ft. Lauderdale, Florida and is distributed in Canada by A. Johnson Co. of Montreal."

Jan 1, 1975

By G. Deschênes

Following a successful investigation on the Central Zone sample, a cyanidation study was conducted on an ore sample from the AD-MW Zone of Clarence Stream Property, owned by Freewest Resources Canada, to develop a leaching strategy to extract gold. At a grade of 6.48 g/t, gold is present in the forms of aurostibite, free gold and electrum. The ore contains 4.3% berthierite/gudmundite, 1.3% pyrrhotite, 0.7% pyrite, 0.07% stibnite and 0.9% arsenopyrite. Similar to the Central Zone, the extraction of gold from the AD-MW Zone can be performed at atmospheric pressure, pH 10.5 and with a low concentration of cyanide. The grind size had no effect on gold extraction between a P80 of 28 to 71 µm. The oxygen and cyanide requirement significantly increased with a ?ner grind. Consequently, a very close control of cyanide addition is required to minimize passivation of gold. Lead nitrate, added in the pretreatment, increased the extraction of gold by 2.3%. Leaching at pH < 10 improved gold extraction but increased the cyanide consumption by 5%. Passivation of gold occurred when the pretreatment was longer than 2 hours. A longer pretreatment reduced the cyanide consumption by 5%. Mineralogical characterization of the leach residue with no gravity pretreatment prior to leaching indicated the presence of unleached gold grains and passivated gold grains. Removal of coarse gold by gravity increased the extraction by 2.8% (leach residue at 0.74 g/t Au). Increasing the DO to 16 ppm or the lead nitrate from 500 to 1,000 g/t increased the overall gold extraction to 90.4% (leach residue at 0.62 g/t), which is the maximum gold extraction obtained. The leaching parameters were 800 ppm NaCN, DO 16 ppm and pH 10.5 for a duration of 120 hours. The associated cyanide consumption was 4.0 kg/t. Gold leaching was not sensitive to cyanide concentration. Reducing the cyanide concentration to 250 ppm resulted in a gold extraction of 89.5% with a cyanide consumption of 2.6 kg/t.

Jan 1, 2009

By Scales PJ, Ralston J

Fine coal particles have been examined with respect to dustiness and its connection with various physical and chemical properties. It appears that a given coal will tend to be dusty ifthe moisture content is low and if the inert maceral content and overall rank are high. The hydrophobicity ofa coking coal (Young-Wallsend) and a steaming coal (Blair Athol) was examined in detail by a dynamic contact angle technique. The YoungWallsend coal had a higher contact angle, on average, than the Blair Athol sample. This result has important implications for dust suppression and associated processes.

Jan 1, 1986

By Emerson de Andrade Monteiro

As ligas de titânio ao Nióbio apresentam grande potencial de desenvolvimento graças a excelentes combinações de propriedades. O tratamento termomecânico a elas conferido é importante para atingir as propriedades desejadas. O presente estudo tem como objetivo avaliar o efeito da conformação mecânica nas propriedades da liga Ti42Nb forjada a frio com 80% de encruamento e seguido de envelhecimento. Foram realizados ensaios de tração, medidas de dureza, metalografia e microscopia das superfícies de fratura. Foi possível observar que a liga Ti42Nb apresentou maior dureza e consequentemente maior resistência após o envelhecimento.

Aug 16, 2017

By Catherine T. Aimone-Martin, Meyers Joseph A.

A new strain-based criteria is being adopted for rock blasting in New York City (NYC). This criteria is based on several years of research involving vibration measurements of tall structures during blasting within several feet from buildings designated historic and Landmarked. This research has demonstrated that tall, heavy structures show little upper-structure vibratory response during hard-rock, urban blasting carried out in NYC. The Fire Department of New York City (FDNY) permits rock blasting and regulated limits for ground vibrations using the U.S. Bureau of Mines (USBM) safe blasting criteria. However, these regulations are often superseded by a 0.5 in/s (12.7 mm/s) limit imposed by the New York City Department of Buildings for historic and Landmarked buildings that are adjacent to the majority of blasting projects in the City. This onerous limit is often exceeded resulting in frequent stop work orders that increase the cost and time of rock excavation projects. The

Jan 1, 2019

By Gustavo Armijo

Slippery and unstable working platforms spoiled not only by natural weather conditions but also by the effects of the construction process (drilling mud, grout slurry) are among the main sources of hazards. Due to this fact a set of recommendations for execution and maintenance of working platforms are presented in this paper, which is based on a study on this subject that is being carried out by AETESS, the Spanish Federation of Geotechnical Contractors. The main objective of this paper is to establish the basis for the right execution and maintenance of working platforms for geotechnical jobs with the idea of increasing safety and productivity. All the aspects involved in working platform safety are analyzed: ground and equipment characteristics, geometric conditions and working platform maintenance. From this analysis a set of general requirements is proposed together with the necessary specific controls before and after the equipment arrival to the job site. In order to facilitate this analysis some flow charts and tables and specific appendixes for each geotechnical technique are included.

Jan 1, 2006

This paper outlines the complete failure of the U.S. in status and relevance in Rare Earth Oxides (REO). Although rare earth oxides are strategic and critical in their own right, refining these REOs into elements and alloys is even more important for the development of "Green Technologies" and advanced weapons systems. America does not have an active domestic source of rare earth oxides. America does not have any heavy rare earth elemental or alloy capabilities. The magnitude of this failure continues to become more apparent as the manufacture of REO based electronics and magnetic components moves eastward towards China. China has succeeded in outmaneuvering the United States and the world in its quest to control the rare earth oxides, elements and alloys, and the many industries dependent upon REO. What can be done?

Jan 1, 2010

Editor’s note: As usual, the June issue features an industrial minerals review. And some thanks are in order. Thank you to the industrial minerals annual-review editor, to the technical committees chair and vice chairs and to the authors of the individual commodity profiles. Jim Norman of GeoTrans Inc. is the industrial minerals annual-review editor. William Langer, U.S. Geological Survey, is the chair of the SME industrial minerals technical committees and the vice chair of the technical committee for construction materials. Other technical committee vice chairs include: •Lucy McCartan, U.S. Geological Survey, agricultural minerals. •Steve Herron, Oglebay Norton Performance Minerals, ceramics and refractory materials. •Srinivas Veeramasuneni, U.S. Gypsum, chemical raw materials. •Ismail Yildirim, Imerys, fillers and pigments. •Charles Landis, BPM Minerals, sorbents, filters and process aids. •Ray Harris, Wyoming Geological Survey, specialty minerals. Their help makes possible this June industrial minerals issue. On behalf of the readers, the editors thank them

Jan 1, 2004

By R. M. Waterstrat

X-ray diffraction and metallographic examination of binary Mn-rich alloys with Ti revealed the presence of intermediate phases in this system. A binary R phase has been identified and also a phase having an a-Mn type structure. The X-ray pattern of the phase TiMn3 is presented and a tentative phase diagram for the Mn-rich portion of this binary system has been constndcted. MANGANESE-rich alloys with titanium have been subjected to thermal analysis at temperatures down to 1100°C by Hellawell and Hume-Rothery.1 Their results indicate the existence of an intermediate phase TiMn3 in this binary system. This phase appears to coexist with the Laves phase TiMn2, and with terminal solid solutions based on the allotropes of manganese, at least down to 1100°C. The above investigators did not attempt to determine the crystal structure of this phase, however. Since, by analogy to the binary systems Mn-V and Mn-Cr3 one might expect to find a phase in this region of the diagram, it seemed desirable to obtain X-ray diffraction patterns of alloys in the concentration range in question, in order to ascertain whether the sigma phase or related structures occur. EXPERIMENTAL PROCEDURES Alloys were prepared by arc-melting electrolytic manganese and iodide titanium in a water-cooled copper crucible under a helium atmosphere. Excess manganese was added to each melt in order to allow for losses incurred during melting. The alloys were then wrapped in molybdenum foil and sealed in evacuated quartz tubes for annealing at various temperatures, as shown in Table I, followed by quenching in cold water. Although the inside of the tubes showed evidence for some loss of manganese from the specimen during annealing, there was no evidence of any reaction between the specimen and either the molybdenum foil or the quartz tube at these temperatures. It was later found that the manganese loss was considerably reduced by annealing these alloys in sealed quartz tubes containing one atmosphere of purified argon. As an added precaution the surface of each specimen was ground off before crushing the alloys to -270 mesh powder, using a hardened steel mortar and pestle. X-ray powder patterns were obtained using either FeKa or CrKa radiation in an asymmetrical focusing camera, which gave excellent dispersion of the closely spaced lines. Pictures were also obtained using a Debye camera of 5-cm radius which provided data in the angular region not covered by the focusing camera. The alloy specimens were polished and examined metallographically, using an etchant consisting of 60 pct glycerine, 20 pct nitric acid, and 20 pct hydrofluoric acid. The 10-g buttons were in each case broken in half and found to be well-melted and free of any gross segregation. One half of certain alloy buttons was submitted to chemical analysis in the "as-cast" condition. No appreciable change in composition seemed to occur during annealing . RESULTS The X-ray pattern of alloy Ti1.17Mn0.83 was found to agree well with that of the ternary R phase which was first found in the Mo-Cr-Co system,&apos; and re-

Jan 1, 1962