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By A. Sobhy

Froth flotation is a widely used, cost effective coal cleaning process. However, its high process efficiency is limited to a narrow particle size range between approximately 50 to 600 µm for coal and 10 to 100 µm for minerals. Beyond this range, the efficiency of froth flotation decreases sharply, especially for difficult-to-float coal fines of weak hydrophobicity (e.g., oxidized coal). This study was aimed at enhancing recovery of an Illinois fine coal sample using a flotation column featuring a hydrodynamic cavitation nanobubble generator. Nanobubbles that are mostly smaller than 1 µm can be formed selectively on hydrophobic coal particles from dissolved air in fine coal slurry. Results indicate that combustible recovery of a -150 µm coal was increased by 5-50% for different size fractions in presence of nanobubbles, depending on process operating conditions. Other major advantages of the nanobubble flotation process include lower collector dosage and air consumption since nanobubbles are produced from air naturally dissolved in water and they act as a secondary collector on particle surfaces, thereby resulting in considerably lower operating costs. Key words: Cavitation; coal; froth flotation; nanobubble.

Feb 27, 2013

By John H. Soule

Although known since 1902 , the Capitan iron deposits have not been mined mainly because of the low grade of the ore . A small amount of exploratory work carried on at an early date was reported . C. E. Johnson , district engineer of the Bureau of lines for New, Mexico , visited this propert , and as a result of preliminary sampling and mapping by the Bureau3/ and the Federal Géological Survey , an exploratory project was conducted during March , April , and liay 1944. Further mapping and logging of the vagon -drill samples was done by V. C. Kelly , geologist , of the Survey .

Mar 1, 1947

By B. J. Breen, C. S. Mogg

Considerable borehole investigation work has been completed at a proposed site at Sellafield in Cumbria, supplemented by seismic surveys, other geophysical sensing and geological mapping. The focussing of investigation on the rock mass itself will be achieved by means of the planned underground rock characterisation facility, giving access to depths of about 800 m in the strong, low-permeability basement rocks of the Borrowdale Volcanic Group. Characterisation work undertaken during the sinking phase and interaction with continuing surface-based exploration and monitoring should permit a firmer assessment of the long-term safety of a repository. Key considerations in the choice of a design for the repository include the waste handling method, underground inlet cell, underground vaults, vault environment and environmental effects

Aug 1, 1994

By M. Abdellatif

Keywords: Magnesium, pyrometallurgy, Mintek Samples of crude magnesium produced by the Mintek Thermal Magnesium Process were refined in two stages. The first stage consisted of co-melting of batches of the crude metal and MgCl2-KCl flux (cleaning), followed by stirring at 30 rpm for 30 minutes and settling of the sludge (mixture of molten salt and solid impurities) from the magnesium melt. The operating temperature was 680?730°C. Most of the contained calcium and significant proportions of iron and silicon were transferred into the sludge phase, which left a metal containing, on average, 950 ppm Si, 470 ppm Fe, and 230 ppm Ca. In the second stage, small-scale refining tests were conducted on cleaned samples from the first stage, as well as on crude magnesium. FeCl3 was used as the refining agent. These tests were carried out at 715?760°C with various amounts of the refining agent. The refined metal was suitable for the production of various magnesium alloys, particularly AZ91D.

Jan 1, 2006

Sulphuric acid leaching at atmospheric pressure of a number of Australian nickeliferous laterites was examined in detail. The results obtained indicate that nickel can be extracted from these ores, although the conditions required to achieve about 90 per cent extraction vary widely. These differences in reactivity can be related to the types of nickel-bearing minerals present.Nickel is more readily extracted from nickel-bearing clays such as chlorite, than it is from nickel-containing goethite.The results clearly show the problems associated with the processing of complex ores such as the nickeliferous laterites, and they indicate the need for complete characterization of each deposit.

Jan 1, 1978

By G. van Aswegen

The geometry and morphology of a set of low-angle fractures around a stope in a deep Witwatersrand gold mine are explained in terms of extension fractures forming under variable conditions of stress. Primary extension fractures (E1) form some distance ahead of an advancing stope along the s1, s2 plane. With stope advance, a couple of these fractures end up in a stress regime conducive to transpressional shear and a secondary set of extension fractures(E2) is formed at a high angle to the primary fractures. i.e. at a low angle to the stope. As the E2 fractures are undermined, they migrate into a stress regime of transtensional shear and a third set of extension fractures (E3) may develop between E2 fractures. These have sigmoidal shapes, being parallel to the E2 fractures at the E2 discontinuity where s3 is negative, and curved through the un-fractured rock between E2 fractures where s3 is positive at the instant of fracturing. The fractures all display fractographic features characteristic of dynamic extension failure with striae indicative of the direction of rupture propagation and the local, instantaneous orientation of s1.

Jan 1, 2012

By Sam X. Yao

The underwater concrete technology has historically evolved largely through a trial-and-error process of constructing marine works. Many outstanding examples exist of high quality concrete placed underwater. However, failures also occurred and led to excessive cost and/or schedule overruns. These failures were largely due to improper concrete mix design or improper placement. The problems may have occurred because proper underwater concrete construction techniques and experience have not been widely disseminated. This section focuses on technical issues of underwater concrete mix design, concrete production and placement, and quality control.

Jan 1, 2013

By Steinar L. Ellefmo, Fredrik Søreide

"The Norwegian University of Science and Technology (NTNU) and Nordic Ocean Resources AS, with support from Statoil ASA have carried out a project reviewing the knowledge about seabed mineral resources in Norway to identify and prioritize needs for further research and development.A special focus area in the project has been to increase the knowledge of possible massive sulfide mineralizations along the Mid-Atlantic Ridge. This Ridge is a subsea mountain range which separates the Eurasian and the North American continental plates. In this area, seafloor massive sulphides (SMS) are formed from the volcanic and hydrothermal activities along the Ridge. A large part of the North-Atlantic Mid-Atlantic Ridge between Jan Mayen and Spitsbergen is located on the Norwegian shelf.Analysis and interpretations of multibeam data have been carried out by NTNU in cooperation with the Russian Institute for Geology and Mineral Resources of the Oceans in order to disclose relevant areas for the formation of SMS deposits. This analysis has identified several promising areas."

Sep 1, 2014

By C. J. Roos

Ground-engaging tools are used to prevent damage to the main components of earth-moving equipment. These tools consist of everything from shovel teeth to replaceable drill bits to dozer wear plates. The costs of these "consumable" items are increasing with the costs of raw materials. This project developed a tool to be used by Newmont Mining Corp. to predict the consumption of excavator teeth at a particular mine site. This paper presents the results of the Montana Tech research project in which an equation was developed to predict excavator teeth consumption based on production rates and rock properties.

Jan 1, 2010

By Robert B. Bittner

Large diameter piles (2 to 3 m diameter, both driven and drilled) are being used more frequently by designers of bridge foundations. The use of these large piles allows the pile cap to be positioned off the bottom but usually still below water. Conventional cofferdams as shown in Figure 1 below are not suited to this type of pile cap. However, float-in cofferdams offer a viable alternative. This paper describes the float-in cofferdam system, its initial development for use on the Bath-Woolwich Bridge in Maine and its most recent application on the new Carquinez Bridge in California.

Jan 1, 2013

By Julian Wills

The Candrill was developed with Soredem as a one-operator rockdrill for Canadian narrow vein mining. It provides the benefits of increased drilling rates, lower noise and vibration, mass reduction of 20% and system cost saving. The Candrill is to be commercialised at the end of 2001 together with a stoper drill through Parts Headquarters, Novatek's Canadian agent. The Candrill or pneumatic drills may be further exploited using a simple mechanised drilling system to further reduce operator labour, improve drilling speeds by up to 50% and to enhance drilling accuracy. Novatek's drilling system for simple mechanisation in gold and platinum mines is integrated with roof supports, can operate in stope widths as low as 800 mm and has resulted in labour savings of 50%, improved advances per blast of 20 to 50% and improved operator safety and ergonomics.

Oct 1, 2001

By R. A. Cattell

Since the return of the Petroleum and Natural Gas Division of the Bureau of Mines to normal peacetime functions following World War II, a coordinated program of oil and gas development and production research has been in prog- ress, and the importance of the problems has been evaluated so that the Bureau can render greater service to the oil and gas industry. Among the problems associated with development and production research, those concerned with efficient utilization of the Nation's reserves of hydro- carbons contained in gas-condensate type reservoirs continue to receive major emphasis. For a number of years an important part of the Bureau's work has been the study of two pressing problems associated with production from such reservoirs; first; an investigation of fluid properties, and the second, finding a means of controlling corrosion. Studies of the characteristics of gas-condensate fluids have resulted in the publication of a number of reports, which cover a broad field. In general they deal with subjects such as the properties of a fluid from a well; development of research equipment, means of combatting corrosion, and the many aspects of gas-condensate engineering. To provide experimental data on relative liquid and gas volumes and critical pressures and temperatures, a windowed cell was constructed that permits ob- servation of the fluid phase while making the tests. Experimentation in the field on the use of inhibitors to control corro- sion of equipment in gas-condensate wells has disclosed that solutions of chromate are effective retardants of corrosion. Engineering field studies of the Carthage and New Hope gas-condensate fields are in progress, and reports on the Sheridan and Lake Creek fields have been completed. Following a plan of making studies of important newly discovered oil fields, the Bureau is investigating the physical properties of reservoir oil

Dec 1, 1948

Ore samples generally require preparation before analysis. Serious problems can occur with contamination degradation and particle size effects. Both grinding element contammation and sample cross contamination havebeen bound to be related to sample hardness and operator technique. For best results with minerals relevant to the steel industry, the use of Siebtechnik-type mills required a combination of careful planning, short grinding periods and intermediate sieving of the sample. The results may be extended to most mineral, rock, and refractory sample preparabons.

Jan 1, 1978

By Lee Ann Gardner

This U.S. Bureau of Mines publication presents a case study of the processes used in permitting the Nome Offshore Placer Project, a gold mining project offshore Nome, Alaska which operated from 1985 through 1990. The mining project, developed by Western Gold Exploration and Mining Company, Limited Partnership (WestGold), used the BIMA, which was at the time the largest bucketline mining vessel in the world, to dredge gold from the ocean floor. This case study reviews the permitting process from the regulators' and industry's perspectives, as well as characterizing the efficiencies and inefficiencies associated with this case. The Federal, State and local laws applicable to the Nome Offshore Placer Project are identified, agency jurisdiction and interagency relationships are explored, and the chronology of the permitting process is examined. The regulatory authorities for both environmental monitoring and post-mining monitoring are delineated. Significant milestones affecting the project and required regulatory submittals are also included. The case study of the Nome Offshore Placer Project is detailed with respect to agency involvement and coordination, approaches to permitting from both the regulators' and developer's perspective, environmental issues, and permit stipulations which were unique to the project. The advantages and disadvantages of these topics are discussed.

Jan 1, 1992

By J Petrolito

"To improve the economic and environmental performance of underground mining operations, it is common practice to return the metallurgical waste material underground as backfill. This is called hydraulic backfill and is used to fill the mined-out areas not exposed to further mining. To provide mechanical support for underground mining a cemented backfill is normally used. Since its introduction, cemented backfill has allowed mining companies to increase their ore extraction and improve working and environmental conditions. However, cemented backfill represents up to 50% to 85% of the mine’s operating cost compared with 5% to 10% for hydraulic backfill.These economic pressures have led mining companies to carry out research into the partial or total replacement of cement using a variety of alternative materials. The materials are generally site-specific materials, readily available, and cost-effective relative to cement. Such investigations have led to reduced cost of many backfill mixes while maintaining, and in some cases improving, the physical properties of cemented backfill. However, in most cases, cement still remains an integral part of any binder combination. This can be attributed to the alternative binders investigated being either non-binding materials or capable of generating only low-strength backfills, except when used in conjunction with cement.This paper provides a historical review of backfilling binder materials and their characteristics. In particular, it reviews the many alternative materials that have been proposed to either partially or fully replace Portland cement as the main binder."

Jan 1, 2005

By Peter Faust, Jeremy Zorne, Timothy Siegel, Diane Fiorelli

Professional sport venue construction follows a very simple rule. Once the decision has been made to move the team to a new place, construction shall begin immediately, so that not more than one or two seasons pass by stuck in the old home. Such tight construction schedules require a different approach than traditional design-bid-build contracts. Design is mostly done on the fly, the construction schedule becomes a main risk factor and an early contractor involvement is desired. As specialty contractors become more and more sophisticated, owners, their construction managers or the general contractor have realized the value of ideas and modern technology they can bring to the table for a successful and fast project completion. Local knowledge and experience in a variety of solutions play a key role in the specialty contractor’s ability to provide added value to the project. This is also true for the specialty foundation contractor, who needs to understand the complexity of such modern structures from its integrate foundation, over the delicate concrete structure to a potentially fancy movable stadium roof. Not to mention all the modern high tech equipment which shall make such a place a great customer experience. His expertise shall enable him to propose the most suitable foundation element for the given ground condition and application. Rather to build what others have designed, his strength is to propose alternate concepts which will be faster and (hopefully) more cost effective. This paper highlights different value engineering (VE) input a specialty foundation contractor had on 3 major sports arena projects in California. Together with the entire team from owner to GC, including the Geotechnical (GEOR) and the Structural Engineer of Record (SEOR), the most efficient and best performing foundation solution can be found every time. But such an approach also requires the open mind of the owner to entertain last minute changes when the permit drawing set has already been submitted for approval.

Jan 1, 2018

By Creelman C. A

With the technique and data obtained in using the blast hole diamond drill for "Removal of Horizontal Level Pillar by means of Blast Hole diamond drilling at New Occidental Gold Mines N.L.," as described in Proceedings No. 133 of 1944, and a series of experiments using the blast hole diamond drill for stoping at New Occidental and New Cobar Mines over the past two years, a benching method of stoping has been developed using 2 inch coring diamond drill bits, resulting in efficient and economical ore extraction in these large ore bodies.During the experimental stages the standard H-inch blast hole was used, but the deflection of the holes, when using this solid bit, either decreased or increased the burden of the hole when it became necessary to drill holes deeper than 45 feet.It was found that after blasting vertical holes deeper than 45 feet, the ore did not break satisfactorily over the full length of the hole; on one occasion as much as 30 feet of bench was left at the bottom of the face, which had to be subsequently re-bored andblasted.As this defect was also noticeable to some extent even when the holes did not deflect, it was then obvious that the explosive had become less sensitive in the lower section of the hole. This was probably brought about by pressure being built up ahead of the detonation wave in H-inch hole, resulting in desensitization of the explosive.Another series of experiments were carried out, using 2-inch solid bits, which enabled a much greater burden on the holes, and the use of primacord for the full length of the hole.This gave satisfactory results regarding breaking and fragmentation, but was uneconomic owing to the excessive consumption of diamonds, and the slow rate of drilling.Further experiments were then carried out using 2-inch coring bits, (Fig. 1) which allowed holes of 90-feet to be bored with little deflection, and proved to be entirely satisfactory as to cost and speed of drilling.

Jan 1, 1945

By Scott Ellenbecker

The formation in Newmont Mining?s Phoenix Mine near Battle Mountain, NV contains high levels of abrasive quartzite as well as gold, copper and silver. Newmont started mining operations at Phoenix (formerly Battle Mountain Gold) three years ago and the planners knew they were working with a challenging geological formation. But as it turned out, it was more challenging than anticipated. Mine manager Mark Evatz said, ?Anything that touches Phoenix rock wears fast. The rock fights back here.? To contend with the hard conditions, Newmont uses Atlas Copco?s Pit Viper 271 (PV-271) blasthole drill. Because of the hardness of the rock, drilling at Phoenix requires hammer drilling and the mine uses Atlas Copco TD65 hammers with 171 mm (6.75 in.) bits. The mine?s PV-271?s are outfitted with a single 41 m3/min (1450 cfm), 2.4 MPa (350 psi), oil-flooded air compressor. Phoenix has six Atlas Copco PV-271 drill rigs plus an Atlas Copco DML and a DM45 midrange blasthole rig. The mine?s goal is to keep 3.6 Mt (4 million st) of muck in inventory to stay ahead of the shovels and support needed operational flexibility (ore control related). Drilling efficiency has been a continuous point of improvement since operations began at the mine. The single-pass depth capability of 16.5 m (55 ft) on the PV-271 helped with that. Originally, the plans called for 6-m (20-ft) bench heights, supported by 7-m (23-ft) drill depths, and time spent moving from hole to hole was eating up productivity. Drilling on that plan resulted in drilling an average of 14 m/h (47 ft/hour). When depths were changed to 13-m (44-ft) drill depth, supporting blasting of 12-m (40-ft) benches, they were able to use the single pass capacity of the PV-271. Performance increased to more than 18 m/h (60-ft/hour) an hour. Although the drill depth change largely supported the improvement, other aspects of continuous improvement associated with improved knowledge of the Pit Viper drills helped as well.

Jan 1, 2009

By Bryan M. Maybee

The scheduling of underground mining activities is a complex task, in particular because of the requirement to satisfy a large number of constraints. A Schedule Optimization Tool (SOT) for underground mine planning is described, and its use for investigating strategic decisions is illustrated by means of a case study. The main components of SOT include: a genetic algorithm, which searches for optimal schedules; guidance, the application of heuristic rules to guide the genetic algorithm; and sliding, which implements just-in-time development. For the case study, SOT is employed to generate schedules at various ore capacities, accounting for the appropriate financials in each schedule evaluation. The case study finds that preliminary scheduling performed before invoking SOT, intended to provide a good starting point for the search, does not ultimately lead to higher value schedules. Two key uses for SOT are identified. A mine planner can save time by using SOT to produce high-value scheduling alternatives. This process ensures a broader investigation of the value that the deposit can yield. Also, SOT can be used to validate strategic and tactical decisions, by scheduling under alternative scenarios. Both uses produce high value schedules conforming to all imposed resource constraints.

May 1, 2009

By Richard Burt

"In seeking to supply the ever increasing needs for raw materials, the mining industry has been required to develop lower grade resources in increasingly remote regions of the world. This has resulted in the extension of many frontiers, both technologically and geographically.The accent of mineral processing research over the last few decades has been to “do existing things better”. There have been many breakthroughs in equipment and processes; however in general the accent has been to increase capacity of existing unit processes, often by orders of magnitude, or to refine the process itself by basic research and development. This has lead to added sophistication, enabling the process engineer to maintain optimum performance of his equipment while reducing the cost, and the amount of labour needed to operate the plant.While much of the increased requirement for resources is handled by the development of ever larger, lower grade orebodies, a significant portion still comes from the small miner - even the artisanal miner - operating in remote and often politically sensitive parts of the world. For them, innovation and simplicity are the keys, not sophistication.The tension between sophistication and simplicity - or research and reality - is specially evident in the area of gravity concentration of rare metals, such as tin and tantalum. This paper looks at this tension, primarily from the eyes of an operator and seeks to put into perspective the two paradigms."

Jan 1, 1999