Search Documents

By William H. Peterson

How is the Government's oil import control program doing? In July 1954 Mr, Eisenhower established the Cabinet Committee on Energy Supplies and Resources Policy. On July 29, 1957, the Administration imposed "voluntary" company oil import quotas on American oil importers to maintain "a healthy domestic (oil) production industry" and safeguard "national security." On March 10, 1959 the President by proclamation made the voluntary program mandatory. But study of the program in practice shows that it is not working out as expected and-that there is some doubt that its aims and other related Administration purposes are being achieved. Take the Administration's anti-inflation policy. To be sure, the President apparently recognized in his March 10th proclamation that in restricting cheap imported oil in favor of more expensive-domestic oil he was making the inflation fight that much harder, for he called for Government surveillance of domestic oil prices to prevent them from getting out of hard, And indeed while domestic crude oil prices have not risen appreciably during 1959 neither have they fallen appreciably (although there has been some price weakness in the past few weeks).

Jan 1, 1960

By O. A. Velasquez, A. R. Kumar

"Dust generated on underground mechanized coal mining faces is a health and safety hazard. Continuous miners deployed underground usually have an integrated flooded-bed dust scrubber mounted onto the machine that arrests the generated dust from close to the face and cleanses the air around it. However, the impingement screen might get clogged depending on the coal seam being worked. This necessitates the cleaning of the screen which in turn, reduces the overall availability of the scrubber and, hence the continuous miner. A novel non-clogging screen has been developed at the Department of Mining Engineering, University of Kentucky. The proposed impingement screen is built up of three individual aluminum screen units 1.5 mm thick and separated by 3 and 2 mm respectively. The screens have long vertical slits measuring 6 mm. A water spray continuously keeps the screen wet and provides for the filter element to arrest the dust particles. The slits force the dust-laden air to make sharp turns. The dust particles cannot change directions rapidly, impact one of the three screens and are separated out based on their momentum. Preliminary computational fluid dynamics (CFD) models have indicated significant cleaning efficiencies in the respirable range at the expense of much lower pressure drops. Results indicated by CFD models and supported by laboratory experiments have been discussed in this paper.ACKNOWLEDGEMENT The authors acknowledge the National Institute for Occupational Safety and Health (NIOSH) for funding this research. Dr. Thomas Novak, Professor of Mining Engineering, is also acknowledged for his continued support and encouragement. INTRODUCTION Continuous miners are ubiquitous in coal mining around the world. The miners are operated against bling headings, ensuring adequate flow of air at the face could be difficult. The minimum requirement of ventilation airflow quantities at those coal faces are legislated to dilute dust generated to harmless levels. New dust rules promulgated recently have further called for lower exposure levels of personnel working underground (Courtney) (MSHA, 2014) (NIOSH, 2010). Water sprays are also installed at strategic locations and serve as powerful air-movers. The sprays capture some amount of dust generated while cutting. In addition to this, usually, all continuous miners are equipped with a flooded-bed dust scrubber as shown in Figure 1 to capture the dust from close to the extraction drum (Chao & De-sheng, 2000) (Wala, Vytla, Huang, & Taylor, 2008) (Organiscak & Beck, 2010)."

Jan 1, 2018

By C. Clark, R. Pakalnis, B. Seymour, L. Martin, R. Jacksha, M. Stepan, M. Roworth, C. Caceres

The National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop safe practices for the use of shotcrete as ground support in underground mines, particularly mines operating in weak host rock. As part of this research, a rugged, portable direct tensile test system was developed for measuring shotcrete adhesion strength in underground mines. During the development of this test system, more than 185 direct tensile tests were conducted with a common, commercially available macro-synthetic fiber-reinforced shotcrete that was applied to concrete test panels using a dry mix process and machinery. The average bond strength of the shotcrete to the concrete substrate typically increased as a function of the shotcrete’s curing age, ranging from 0.44 MPa (64 psi) after one day of curing to 1.58 MPa (229 psi) after 90 days of curing. Adhesion strength increased markedly between one and three days of curing, reflecting a similar trend of increasing shotcrete tensile strength with curing time. This robust direct tensile test system can improve mine safety by providing a reliable means of measuring shotcrete adhesion strength and also supplying important information about the quality of the applied shotcrete and the competency of the underlying rock.

Jan 1, 2010

By Alessandro Boscaro, Daniele Martinelli, Cristina Gabriela Oñate Salazar, Daniele Peila, Carmine Todaro

"The wear phenomenon in TBM machines is not a simple issue, as many parameters are playing an important role on the consumption of the tools during a tunnel excavation. The action of the wear due to the contact with the soil can occur on the excavation tools, on the cutterhead, in the excavating chamber and on the screw conveyor. The test developed at the Laboratory “Tunnelling and Underground Space Center” of the Politecnico di Torino is aimed to reproduce the interaction between the tools and the excavated material, simulating the excavation conditions in terms of soil conditioning and water content. The test, which is not standardized, is studied to evaluate the wear in a global point of view. The present work starts by testing the influence of the use of chemical agents during the conditioning phase on the drop of the wear phenomenon, in terms of metal weight loss. 1. INTRODUCTION The wear phenomenon of the excavation tools used in TBM tunneling machines is playing recently a major role in the design stage of full-section tunnels in both soils and rocks. Concerning EPB excavation technology, the main issue regarding productivity is the wear of its components (Peila et al.,2012), which increases the so called dead time in the whole process. The friction generated between the components and the ground causes the consumption of the tools and other metallic components in contact with the ground, described as primary and secondary wear by Nielsen et al. (2006a). This leads to downtime, with risky and complicated maintenance operations (Peila and Schulkins, 2009), as occurred in recent tunneling works in Liguria (Italy). The study of this argument in granular soils is very delicate, as it encloses not only the properties of the excavation tools, but also the characteristics of the ground to be excavated (hardness, mineralogy composition, shape and dimension of the particles and moisture content). The penetration mechanism is based on the scraping of the ground, by mean of cutting tools, with its consequent consumption. Concerning the rocks, the excavation principle is characterized by crushing the rock mass matrix by applying high compressive stresses through cutting disks. In such a way, to avoid frequent downtimes and their consequent economic losses, it is very important to study this subject and therefore understand and forecast the durability of the components, in order to try to maximize the productivity of the machine by reducing the frequency of maintenance stoppings."

Jan 1, 2016

By A. Pezzuto

"Pipes are used on mine sites in a variety of applications including transport of slurry, conveying clean and processing water, and in mine dewatering. Mine waters and slurries can cause pipe wear and failures via several mechanisms (or combinations thereof) such as abrasion, scaling, and corrosion. Polyethylene (PE) pipe materials have grown in popularity over the past several decades due to their chemical and mechanical properties (e.g., inertness, flexibility, relatively low density) and low cost. While PE is generally resistant to corrosion, it is subject to abrasion. To combat this, a novel, rubber-like liner is in development. In addition to comprehensive abrasion testing, however, the liner must be evaluated to see how it performs under other conditions. Here, a brief field study is described that tested PE pipes with the new liner against traditional PE pipes to specifically assess mineral scale buildup. The study was conducted in the Reiche Zeche study mine in Freiberg, Germany in six different locations with varying water qualities and flow conditions. INTRODUCTION Water and slurry conveyance are major operations on and around mine and mill sites, from mine dewatering, to tailings transport, to water treatment processes. Conveyance systems in such applications can include great lengths of pipe materials along with pumps and monitoring instruments, and thus represent significant capital investments. Due to the variability of the physical and chemical properties of water and slurries, pipe materials are subject to a wide range of conditions. These can cause pipe wear and eventually failure leading to serious economic, environmental and social, consequences. While pressure-induced pipe failures (e.g., ruptures or ""bursts”) can be immediate, most failure mechanisms involve gradual processes. Scaling and sedimentation can present major problems for pipe systems conveying highly mineralized waters. Sedimentation generally refers to the deposition of suspended solids, such as sand, clay, silt, or organic matter onto pipe surfaces. This phenomenon can occur due to a decrease in water velocity or particle collisions with the pipe wall. Scaling, on the other hand, commonly refers to the deposition of precipitated mineral salts (including oxides and hydroxides) onto pipe surfaces. Mine waters often have extremely high ion concentrations (i.e., high dissolved solids content) due to their interaction with enormous surface areas of minerals, which are exposed during mining and processing operations (Brown and Barley, 2002). As these waters are transported, slight changes in temperature, pressure or chemistry (e.g., pH or ORP) can cause instability with respect to ion solubility such that salt precipitation begins to occur. “Seed” crystals can rapidly grow and attach to pipes, either due to local surface phenomenon near the pipe wall (e.g., which can promote coagulation) or sedimentation of the precipitated solid. Whether due to suspended or precipitated solids, as the solids begin to stick to pipe walls, “aging” or hardening processes can commence; and the build-up of scale can become self-perpetuating as the scale itself provides an attractive “nucleus” for further attachment of particles or crystal growth (Muryanto et al., 2014). Over time, scale-buildup reduces the effective pipe diameter, which can ultimately result in decreased flow velocity, clogging and, in some instances, bursting (Dirany et al., 2016)."

Jan 1, 2017

By Billy W. Parks

This paper reports on the first 2 years in operation of a special-purpose coal handling rig which provides blending, temperature reduction, and continuous, automatic mechanical sampling as part of midstream barge to ship coal transfers. Briefly reviewing some of the characteristics of coal handling peculiar to midstream transfers, the paper discusses how the most beneficial aspects of midstreaming were enhanced through the design of this blending and sampling rig.

Jan 1, 1986

By John Matthews

During 1982 and 1983, it became increasingly clear that North River No. 1 Mine would have to buy a set of replacement longwall shields. Despite extensive efforts to make improvements, the shields that were in place at that time were incapable of holding the roof. North River Energy had limited experience in specifying and acquiring longwall roof supports, but a great deal of experience with our conditions and needs. We there- fore compiled a shield evaluation method that uniquely responded to our situation. The resulting system emphasized teamwork among operating, maintenance and engineering personnel. The charge from management was threefold: select shields to support maximum expected loads, optimize face operations, and pay attention to detail. Final selection was made objectively, based on all available information. We chose a 5516 KN (620 tons) support with a minimum yield load density of 760 KN/m2 (7.9 tons/ft2). This paper reviews our process of specification, design, prototype testing, and fabrication, and offers some relevant suggestions.

Jan 1, 1986

By B. W. Firth

Increasing depth in vertical mine shafts penalises conventional hoists in at least four distinct ways: rope weight becomes limiting; travel time increases; the obstruction of ventilation becomes more serious; and with friction drives, rope wear due to torque is aggravated. Travel speed is limited by instability of poorly sprung conveyances on inaccurately aligned flexible rails, and also by the cost of installed power to meet an inherently peaky demand. These problems call for a review of existing designs, firstly in respect of the furniture (Buntons and guides) obstructing the air flow, and secondly in regard to the hoist running in the shaft.

Jan 1, 1969

By A. D. Davis

The Bear Butte Creek watershed, in the northern Black Hills of South Dakota, shows the effects of past mining activities in the form of dissolved metals and arsenic in stream water. Bear Butte Creek, during normal flow periods, loses all of its discharge to sinkholes that recharge the Madison Limestone aquifer. This work focused on the geochemical transport and fate of arsenic and on understanding ground-water flow conditions in the Madison aquifer through development of a three-dimensional ground-water flow model that was coupled to a geographic information system (GIS). Stream sampling and discharge measurements helped determine sinkhole losses and loading rates. Column laboratory tests provided data on arsenic adsorption and the mixing of stream water with aquifer water, which also was simulated with the geochemical models, pHREEQE and NETPATH. The models and GIS can be updated with new information and will be useful in managing the water quality of the Madison aquifer.

Jan 1, 1997

By C. V. Deutsch, O. Babak

A longstanding problem in geostatistics is that kriging usually assigns significantly greater weights to end samples in strings of data than it does to central samples. These weights are theoretically valid, but suboptimal estimates may result when there are geological trends in the variable near contacts, that is, large weights may be applied to samples that are systematically lower or higher than average. A number of ad-hoc corrections exist, each with pros and cons; none are fully automatic with a well-defined measure of optimality. A new method for estimation in a finite domain is proposed. This method is referred to as finite domain kriging. The method is based on kriging with a successively larger number of data. The total number of relevant data (n) is established, and then n kriging matrices are solved. The first matrix has the closest single data value (n-1 weights are set to zero); the second has the two closest data (n-2 weights are set to zero) and so on. The final matrix has all n data. The kriging weights used for estimation are the average of the weights from the n successive kriging runs. Each kriging run is optimal, yet with different smoothing and a different treatment of data at the end of the strings. The result is a set of weights that does not give undue influence to data values at the end of strings. The methodology is developed with examples. Cross validation shows that finite domain kriging outperforms conventional kriging.

Jan 1, 2009

By Jonq-Keh Lee

This paper deals with the effects of air leakage from intake to return airways through a series of stoppings on the analysis of coal mine ventilation. The mathematical model which assumes continuous leakage along adjoining intake and return airways is reviewed, and a new mathematical approach is presented based upon the concentrated leakage through individual stoppings. The procedure incorporating the new method in the analysis of coal mine ventilation networks is also discussed.

Jan 1, 1984

By Alfred G. Hoyl

The author, in exploring a virgin area vertically in two known ore shoots requiring decline shaft sinking, drifting, crosscutting and diamond drilling, chose to use electric, electric hydraulic, and diesel rubber-tired equipment. A rebuilt hoist, and electric hydraulic shaft shovel (mucker), hydraulic sinking drills, single boom electric hydraulic jumbo, electric hydraulic LHD, and electric hydraulic diamond drill were used successfully. Slides of the equipment and its use are shown. The advantages and disadvantages of the equipment are discussed, together with costs and production.

Jan 1, 1984

By Robert W. Row

Advanced physical coal cleaning processes that are now under development may remove significantly greater fractions of pyritic sulfur and ash than do commercial coal cleaning processes at comparable heating value recoveries. These processes may be useful for reducing sulfur dioxide emissions from electric utilities and other emission sources. However, little work has been done to determine their applicability to any major coal market. The northeastern states of the United States are interested in burning more coal, but with further sulfur dioxide emission restrictions. Their nearest coal sources are relatively high sulfur Northern Appalachian coals. The project discussed in this paper, which is scheduled to be completed in June 1985, has the objective of technically and economically evaluating various coal supply scenarios involving five selected advanced physical coal cleaning processes; and comparing the economics of them with alternative fuel supply options open to the northeastern users.

Jan 1, 1985

By N. Edmonson

A review of the evolution of the North American sulfur market's structure serves to dramatize the kinds of changes that the market is undergoing at the present time. In 1970, the U.S. accounted for 23 percent of world sulfur production. This share has not declined dramatically--to 21 percent in 1993--but the U.S. developed into a substantial net importer of sulfur in the past 25 years. U.S. output was based on large deposits of native sulfur in the western part of the Gulf Coast region with production by the Frasch mining process. Producers of Frasch, or on-purpose sulfur, have historically absorbed cyclical fluctuations in sulfur demand. Two major changes in the North American market from that time to now have been the introduction of increasingly large quantities of by-product sulfur from petroleum refining and natural gas processing operations in the U.S. and Canada, and that Canadian producers have become the marginal supply source for U.S. sulfur consumers.

Jan 1, 1996

By R. H. King

Mine managers need better information to locate new opportunities and then to assess the effect of their decisions. We are developing the Intelligent Decision Support System (IDSS) and its two major modules, the Pattern Recognition System (PRS) and the Knowledge Representation Subsystem (KRS) to automatically provide the information from monitoring system sensors. So far, we have developed and reported on algorithms that automatically produce accurate time-study reports of continuous miner data from kilowatt sensors at the Deserado Mine, and we are extending the system to accept other types of sensor data input. This paper focuses on AI techniques that improve accuracy of the numerical algorithms in the PRS module. Additional AI work for the KRS module is summarized in this paper.

Jan 1, 1989

By F. W. Brackebusch

A unique machine has been designed for mining narrow veins. The machine, called the NONN, walks on the walls of the stope and carries a boom-mounted hydraulic impact breaker. The concept of walking on the walls allows an existing muck handling system such as LHDs to operate beneath the NOMN. The NOMM has four sets of legs which can be manipulated independently or concurrently to cause the carrier to walk in any direction and to turn sharp corners. The mining rate using the breasting method is targeted to be 25 t/hr.

Jan 1, 1990

By M. P. Neira

In-situ leaching of copper from chalcocite relies on ferric iron concentration in the lixiviant being reduced to ferrous. To re-establish the ferric concentration in solution, ferrous must be re-oxidized. This reaction is slow under normal chemical conditions but it is catalyzed by Thiobacillus ferrooxidans bacteria. BHP Copper's Miami In-situ unit developed a bio-reactor as a method of oxidizing ferrous to ferric. The effects on oxidation of temperature, CO2? oxygen, and air injection flowrate were defined. This paper summarizes the results of ferrous bio-oxidation using plastic column packing and oxide ores as bio-reactors and the leaching results of the bio-reacted lixiviant on chalcocite ores.

Jan 1, 1997

By Robert K. Jones

Filter media can be defined as that material which effects the removal of finely divided solids from a fluid. Thus the removal of dust from air or turbidity from water, for example, can be the result of passing the fluid through a properly supported filter media. Since filtration in one form or another has been practiced since pre¬historic times filter media have been made from an extremely wide variety of materials. Vegetable and synthetic fibers (used loose, or formed into papers, felts or cloth) sand, ground coal, diatomite, perlite, wire cloth, porous metal, and bonded aluminum oxide are among the more important materials used today.

Jan 1, 1961

By P. R. Taylor

Batch leaching experiments have been performed to study the kinetics of galena leaching in fluosilicic acid solutions with oxidants. Variables studied included: fluosilicic acid concentration, oxidant type, oxidant concentration, particle size and leaching temperature. It was found that hydrogen peroxide was the most effective oxidant, compared to the others studied, and the effect of the oxidant concentration on the leaching behavior of galena was very significant. Also, decreasing the particle size and increasing the leaching temperature increased the extraction rate. The initial, apparent activation energy was calculated to be 11.72 kJ/mole (2.8 kcal/mole) and suggested that galena leaching in fluosilicic acid solution, with hydrogen peroxide as an oxidant, may be controlled by fluid film mass transfer initially. The reaction appears to be retarded by the formation of elemental sulfur and the sulfur oxidation becomes a major resistance to the overall leaching reaction.

Jan 1, 1992

By B. K. Mishra

The motion of the charge inside a grinding mill is of considerable practical importance. The dynamics of grinding mills have been the subject of study by a number of workers because it can accurately predict: i) the power drawn by the mill, ii) the distribution of forces inside the mill, and hence the wear rate of balls as well as the liners, and iii) mass transport of milled product through the porous ball charge. Some of the earlier analyses of the motion of a charge of particulate material in a tumbling mill were reported by White (1904), Davis (1919), and Dyer (1945) and have been reviewed by Rose and Sullivan (1958). In these works, frictional force at the wall of the mill and between the colliding balls, and the interaction of different ball trajectories, was not considered. Moreover, it was assumed that the profile of the tumbling charge is independent of the degree of filling, which is generally not true. However, all this work led to the identification of so-called "equilibrium surface" which is the plane that separates the rotating charge into two regions. The inner region is static; here there is no motion relative to the mill shell. The other region is a shear region where either the balls flow down the surface of the charge (cascading motion), or are projected out of the surface and follow approximately parabolic paths (cataracting motion).

Jan 1, 1990