Search Documents

By P. J. G. du Toit

Coal has been mined by hydraulic means in various countries, i.e., the hydraulic excavation as well as the hydraulic transportation of coal has been practiced. The hydraulic breaking (excavating) of the coal dealt with in this report is done with a monitor directing a continuous jet of water against the coal, pressures of the water fed to the monitor range from 1500 to 2500 psi at 1000 to 2100 gallons per minute Transportation of the coal from the face is by fluming if a gradient exists in excess of 2 or, when a favorable gradient does not exist, the coal is pumped from the face by various types of pumps which can also provide a means of hoisting the coal to a higher elevation as required. This report presents: 1.) preliminary design and systems specifications of a demonstration miner (referred to in this report as a hydrominer), 2.) mining configurations showing good promise for typical U.S. thick coal seams in three seam pitch categories, (0° - 7° = Flat, 8° - 250 = Moderately pitching, 26° - 90° = Steeply pitching), along with cost and performance analyses for each system, 3.) a definition of a test program that will provide sufficient engineering data for the design of a water jet cutting head adequate to cut coal in those typical U.S. thick coal seams The cost analysis data showed hydraulic methods to be economically competitive with present thick seam raining methods. It was also obvious from studies of thick seam methods that the hydromonitor coal breaking techniques are more effective in removing most of the coal with its long reach of 60 ft. (or more), is a safer mining system, and produces very low coal-dust content in the air (usually less than 0.25 to 0.5 mg/cubic meter). It is recommended that the USBM sponsor a full fledged continuation of the hydraulic mining program: (a) lab, test, (b) preliminary field test, (c) full scale mine section demonstration.

Jan 1, 1977

By I. L. Bell

The ironmasters of America had asked the Iron and Steel Institute to visit the USA. The Council decided it was not possible to accept, but Mr. Bell visited; this is an account of his trip. Topics covered include transport, charcoal, coal measures, coal, anthracite, bituminous coal, flux, magnetic iron ore, specular iron ore, limonite, red hematite, clay ironstone, black band ironstone, smelting works, blast furnaces of Pennsylvania, Lake Champlain furnaces, Lake Superior furnaces, Cleveland furnaces, Pittsburg furnaces, Missouri furnaces, and those of the southern states. He goes on to describe Catalan hearths, malleable iron works, Bessemer works, the Blair steel process, and labour.

Jan 12, 1875

By C. S. Samis, D. P. Seraphim

In the presence of oxygen, galena is oxidized in an aqueous medium containing ammonium acetate in accordance with the following reaction: PbS + 1/2 0, + 2 NH~Ac -» PbAc, + So + 2 NH: + H2O. This reaction was studied in an autoclave under oxygen pressure by polarographic measurement of the concentration of lead ion in solution. Oxidation rate is parabolic. The reaction products are lead acetote and elemental sulfur, the latter forming a film on the galena crystal. Reaction kinetics appear to be determined by the diffusion of lead from the galena phase to the solution interface through the film of sulfur. RECENT applications of pressure leaching on a commercial scale have emphasized the metallurgical importance of the oxidation of sulfide minerals in aqueous media by oxygen under pressure. Research experience has shown that sulfates, thio-nates, and metal oxides are the products of humid oxidation of sulfide minerals in basic solutions. The metal oxides may be solubilized in the presence of a complexing ion.' Certain oxide minerals are also amenable to treatment by this type of oxidation.' Several kinetic studies have been made of reactions of this type. Stenhouse' found that pyrite (FeS?) oxidized in a sodium hydroxide solution to produce a soluble sulfate and an insoluble layer of iron oxide and that the kinetics of the reaction were controlled by oxygen diffusion through the oxide layer. Andersen' studied the oxidation of galena (PbS) in a sodium hydroxide solution under oxygen pressure. He found the lead and sulfur to be simultaneously oxidized to produce plum bite ions and sulfate ions, and that the reaction rate was proportional to the surface area of the galena. The kinetics appeared to be determined by the reaction of oxygen and water with the galena surface. In each of the above reactions the metal and sulfur components of the mineral were oxidized simultaneously and at equal rates. In the present study the alkaline medium has been replaced by an approximately neutral solution of ammonium acetate in which lead sulfate is soluble. Under the conditions no sulfate was produced and no sulfur could be detected in the solution. The metal component of the mineral was solubilized and the liberated sulfur remained as a film of elemental sulfur on the surface of the galena crystal. A kinetic study of this reaction was undertaken to establish the kinetic mechanism and to determine the rate controlling step. Specific reaction rates were determined by oxidizing crystals of galena of measured surface areas in an autoclave maintained at the desired temperature and oxygen pressure. The rate of reaction was followed by measuring the concentration of lead in the ammonium acetate solution with a cathode ray polarograph, employing stationary platinum electrodes incorporated in the autoclave. Experimental Materials and Equipment Crystals of galena obtained from Violamac Mines, Retallack, B. C., were selected for oxidation because

Jan 1, 1957

By H. Richard Eisenbeis, Donna M. Watkins

Many technical professionals (tp)* desire to occupy upper level management positions. But career paths for most scientists and engineers do not extend beyond their specific disciplines. This is unfortunate. Our technical frontiers are expanding so rapdily that it is difficult, if not impossible, to make sound top management decisions without understanding the technical complexities involved. Technical professionals often are not considered for upper level management positions because they lack the managerial and interpersonal skills necessary to become successful administrators. You've heard this before, but a key component of these skills is the ability to communicate. Technical professionals are often unable to communicate as well as they should with nontechnical professionals and nonprofessionals within the organizations that employ them. Communication is important for managerial success Communication is the network of interactions whereby knowledge and understanding are conveyed from one social set to another (Flippo and Munsinger, 1982). In order to be successful, managers must not only be "good" communicators, they must be "effective" communicators as well. Good communication occurs when managers are able to formulate and transmit their messages in such a way that they are received and understood. Effective communication goes one step further: It occurs when recipients accept messages as legitimate and respond to these messages in the manner desired. Before promotion into upper level positions, managers must have developed organizational skills (planning, decision making, organizing, and controlling) and interpersonal skills (directing, influencing, and motivating). Applying these skills effectively is difficult without a highly refined ability to communicate. Effective communication, then, is basic to managerial success. Nowhere, perhaps, has the importance of being able to communicate effectively been emphasized more than in Mintzberg's landmark study of managerial roles (Mintzberg, 1973). Mintzberg's results indicate that executives typically averaged 36 written and 16 verbal contacts a day. These contacts were both important and trivial. They generally occurred in a random manner. Time spent on each varied. Scheduled meetings averaged over an hour. Desk work, telephone calls, and unscheduled meetings required an average of 15 minutes or less. Why technical professionals have difficulty communicating Three reasons why technical professionals do not communicate well are: • The work motivational patterns and personal attitudes of technical professionals are not conducive to effective communication. • Students in technical professions are not encouraged by educational institutions to develop their communication skills. • Organizations do not insist that all technical professionals be able to communicate in the language of business. The work motivational patterns of most technical professionals are indicative of internals and high achievers (Hunt, Salisbury, and Whittington, 1968). As internals, they believe they control their own destinies. As high achievers, they believe that task accomplishment is a primary indicator of success. To ensure a task is completed in the manner desired, tp's attempt to structure and define work situations so they alone are responsible for results. TPs consider the task accomplished when they, and perhaps other tp's, are satisfied with the results. From the tp's perspective, the task may have been completed. From a communication standpoint, two other factors may apply. First, solving the problem required very little interaction (and thus, communication) with others. Second, the tp's, considering the task accomplished, have little concern for how their "technical" answers will be translated to nontechnical persons needing

Jan 8, 1987

By James P. Stewart

This case history describes the engineering design and construction for the Contractor of a 35-ft-deep excavation for an 800-square-foot addition to an existing sewage pump station. The site posed unexpected geotechnical complications that included deep gravelly soil, a history of local construction difficulties, groundwater consisting of heavy salt brine, and the need to underpin the existing pump station. The project took an interesting twist when the Owner issued a change order limiting the dewatering discharge to a fraction of that required to lower the water table. This documents the interesting circumstances of this job and documents the unusual subsurface conditions in the Syracuse, NY Lakefront area.

Jan 1, 2003

By McLeod RL

The Tolukuma gold-silver prospect is located approximately 100km N of Port Moresby in the Central Province of Papua New Guinea (PNG). Epithermal "adularia-sericite" style mineralisation crops out over 1200m within an en echelon quartz veined zone 1 to lOm wide. At a 4g/t cut-off grade, a geological resource of approximately 1.47Mt @ 13.77g/t Au is indicated from 38 diamond drill holes completed since discovery by Newmont Pty Ltd in September 1986. At a regional scale, Tolukuma miner- alisation appears localised in a dilatant zone at the intersection of a 1150 magnetic structure, and the western margin of a N-S trending graben which is filled by a Pliocene volcanic complex contemporaneous with the Mt Davidson Volcanics 30km to the W. A l0km diameter circular Landsat feature, which may reflect magma emplacement at depth, occurs immediately N of Tolukuma and nearby mineralisation. Mineralisation at Tolukuma occurs in sub-vertical quartz veins at, or adjacent to the faulted contact between Pliocene basic and intermediate volcanics/intrusives, and quartz mica schists and phyllites of the Cretaceous Kagi Metamorphics. Most veins display evidence of multiple episodes of brecciation and textures indicative of cyclic boiling, including crustiform rhythmic banding and quartz pseudomorphs after platy calcite.

Jan 1, 1991

By Panagiota Tsolis-Katagas, Basilios Tsikouras, Tassos A. Grammatikopoulos, C. Katagas

"Mineralogical techniques including microscopic methods, reflected and transmitted light microscopy, Cathodoluminescence (CL) and Scanning Electron Microscopy equipped with an Energy Dispersive Spectrometer (SEM-EDS), are useful in determining the quality of industrial minerals. They are essential for studying ores and metallurgical products including the evaluation of physical characteristics of the mineral, paragenetic relationships, associations with possible deleterious contaminants (e.g., sulphides), spatial distribution within the ore zones and liberation characteristics. The methods are inexpensive, and provide quick identification and distinction among the industrial minerals and the gangue minerals in a section. Additionally, SEM is necessary to reveal complex textural sequences and 3-D measurements of minerals and quick semi-quantitative analysis.Common analytical methods include Electron Microprobe Analyses (EMPA) and Whole Rock Analysis (WRA) (commonly with XRF and ICP) for major and trace elements. The EMPA analyses of industrial minerals provide information on the purity of the analyzed grains as opposed to the bulk chemical analyses that may be misleading due to contamination by other associated common “gangue” minerals. These techniques have been implemented for the case studies of wollastonite, V-magnetite and muscovite. Therefore, these methods can provide extremely useful information and lead to the implementation of a successful pilot-testing programme.MINERALOGICAL EVALUATION OF DEPOSITSDespite their considerable and increasing economic importance, industrial mineral deposits have traditionally been neglected by economic geologists, and are only rarely the subject of the detailed analysis widely lavished on metallic mineralization. Moreover, in that they generally represent concentrations of “normal” rock-forming minerals, albeit commonly with particular textural and/or geochemical features, they have tended to fall between the mainstream of petrogenetic studies and mineral deposit research (Grammatikopoulos 1999). For many industrial minerals, little attention has been paid to the factors responsible for their local concentration as large and high-grade bodies. This comparative neglect has particularly been the case for minerals such as talc and wollastonite, widespread in metamorphic rocks, in which they are reasonably interpreted as components of assemblages derived, respectively, from pelitic sediments, ultramafic igneous rocks and siliceous limestones."

Jan 1, 2003

By B. P. Nutter, M. Lebourg, J. A. McAlister

The Multi-Flow Evaluator (MFE) is a new system of tools providing an original approach in drill-stem testing. It improves control during the testing operation and gives a more accurate evaluation of the fluid recovered while providing additional pressure information for reservoir analysis. The tools are operated entirely by up and down motion of the drill stem. This up and down operation provides a positive means of control and offers easily observed surface indications of tool operating position. An unlimited number of shut-in and flow periods may be taken with this tool while in the hole. The key to the success of the MFE system of tools is the safety seal packer. Until this development, operation of the tools by up and down motion only had proven unreliable. The success ratio of the MFE now exceeds the ratio achieved by conventional tools. The equipment includes a 2,750-cc chamber in which a representative sample of the flowing formation fluid is trapped at the end of the last flow period and brought to the surface under pressure. The sample can be evaluated at the wellsite or transferred under pressure for laboratory analysis. The sampling feature of the tool allows a sample to be obtained from a reservoir which has suffered minimum influence from production. A representative sample can be obtained for laboratory or empirical analysis by employing a testing technique to minimize drawdown during flow periods. Interpretation methods to take advantage of this additional information are presented and supported by actual field examples. INTRODUCTlON The Multi-Flow Evaluator (MFE) represents the most recent technical advance in formation testing. Drill-stem testing techniques prior to the MFE have been limited in three areas—(1) operaiion, (2) recovery analysis, and (3) reservoir analysis. The tools in the MFE system allow maximum control during testing and provide test information superior to that obtainable with conventional tools. The system of tools and the operation procedures are described to illustrate the mechanical advantages over present tools. Methods of pressure build-up and fluid

Jan 1, 1966

By Qingwei Wang

This study focused on acidic wastewater from producing sulfuric acid system in zinc smelter containing mercury 21.48mg/L, zinc 55.85mg/L, lead 38.50mg/L, copper 1.68mg/L, cadmium 10.25mg/L, As 29.86mg/L treated by biologics. The factors of pH value, the ratio of biologics to mercury, complexing time, hydrolytic time and temperature were studied in this paper. Experimental results indicated that at pH value 10, quantity of biologics to mercury ratio was 16, complexing time 30min, hydrolyzation time 20min, temperature at 40?, concentration of mercury in treated water was removed to 22.15µg/L. At same time heavy metals such as Zn, Pb, Cu, Cd, As was removed by biologics, the remained concentration in treated water was Zn 0.53mg/L, Pb 0.12mg/L, Cu 0.01mg/L, Cd low to 0.01mg/L and As 0.023mg/L. According to EDAX analysis, mercury content in complexing sediment reached 28.49% easily to recycle as raw material and low concentration of heavy metals in hydrolytic sediment easily to dispose and treat.

Jan 1, 2009

By A. K. C. Chan

Recent hotel investment projects in China often involve very tight programmes for design and construction. An example given in this paper involves a 24-storey reinforced concrete hotel tower with 460 bedrooms and a 3-level podium commercial complex. The building is supported by relatively widely spaced columns and shear walls below which 88 number large diameter piers were excavated through fill, silty and bouldery clay on to dolerite and slate at depths between 15 to 3 0m below ground level. Whereas much experience has been accumulated in Hong Kong, hand-excavated pier foundation was only adopted for the first time in Dalian. This paper describes and discusses the various factors influencing the choice of the type and design of the foundation system. The criteria for determining appropriate founding levels are then explained. During installation, revisions to the acceptance procedure were made to cater for local conditions. Emphasis is placed on the role of the geotechnical engineer in making on-site decisions during construction. The advantage of the foundation system in accommodating on-site changes resulting from local complex ground conditions is demonstrated. The pier foundations were successfully completed ahead of programme.

Jan 1, 2010

By Jean Rosaire

?GWIOP Location ?Climate and Physiography ?History ?Geology ?Deposit Types ?Mineralization ?Historical Mineral Resources ?Conclusions and Work Program

May 1, 2007

By Vic Sterner

As cities and towns continue to grow, the need to install sewer, water, gas and other utilities becomes a necessity and the blasting of trenches for these service lines probably constitutes one of the most important forms of blasting in built-up areas. There f o re, understanding how explosives can be safely used in the most efficient manner is of prime importance. The need for protection against flyrock must be emphasized. The first consideration is that all explosive c h a rges should be located well down in the blastholes. The golden rule is to ensure that the depth of top stemming is never less than the burden on the hole. In the case of shallow holes, the minimum depth of stemming should not be less than 18 times the charge diameter, if airblast and flyrock are to be controlled. If there is a doubt, then additional cover and/or blasting mats should be used. Putting too much burden on blastholes is another possible cause of flyrock and raising ground vibration levels. Overburdening of explosive charges will also result in the blastholes not breaking to grade. This in t u rn re q u i res additional drilling of shallow holes down in the trench to achieve grade, thus further increasing the h a z a rd of flyrock .

Jan 1, 2004

Gold was determined directly in eight different mill cyanide solutions, by atomic absorption spectroscopy in an acetylene-air flame. Some of the mill solutions were diluted with water to bring them into the most sensitive absorption region (5-50 p.p.m. Au) whereas those solutions with very low gold content «2 p.p.m.) were concentrated by evaporation.Calcium was complexed with ethylene diamine tetra-acetic acid (EDTA) to avoid the undesirable effect of a precipitate on atomization.When added to standard gold solutions, EDTA had no effect on absorption, nor did any of the impurities common in mill cyanide solutions.Known amounts of gold, ranging from 2 to 30 p.p.m., were added to mill solution'aliquots and recovered to within 100 ± 2·5 per cent. For duplicate determinations under normal worKing conditions, standard deviation was 1·32 p.p.m.Excellent agreement was found between atomic absorption gold values and accurate fire assay values.INTRODUCTIONAtomic absorption spectroscopy has been shown to offer a rapid and accurate method for the determination of trace amounts of a number of metal ions. In the field of primary metallurgy atomic adsorption has been used for routine determinations of lead, copper, silver, zinc, cadmium and iron in a variety of raw materials and intermediate products.The scope of atomic absorption spectroscopy was reviewed recently by Willis (1963).The noble metals silver, gold, platinum, rhodium and palladium were determined by atomic absorption from chloride solutions by Lockyer ·and Hames (1959). In their determination of gold down to 1 p.p.m., they found no interference from the noble metals, nor from considerable excess...

Jan 1, 1964

Advances in Optical Image Analysis and Textural Classification of Iron Ore Fines

Sep 13, 2010

By F. R. Brotzen, A. R. Troiano, E. L. Harmon

Precipitation processes leading to drastic property changes are a frequent occurrence in titanium alloys containing large amounts of the retained high temperature P phase. In order to establish the kinetics and nature of these precipitation processes, a series of Ti-V alloys was studied. Time-temperature-transformation diqgrams were obtained for 12.5 and 15 pct V-Ti alloys. These diagrams consisted of two intersecting C-shaped curves: one in the high temperature region for the euilibrium transformation P +u+P, and another at lower temperatures depicting the formation of the meta-stable transition phase, o. Presence of the transition phase retarded the precipitation of the equilibrium a phase. Deformation of retained P resulted in the formation of the o phase. Reversion and retrogression phenomena of the transition phase were observed. A negative temperature coefficient of resistance was found in quenched alloys containing from 15 to 20 pct V. CERTAIN titanium-base alloys can be heat treated to produce appreciable changes in properties. For example, remarkably high hardness values may be obtained by aging or isothermal quenching treatments. Most of the information available to date on the hardening of titanium-base alloys has been systematized recently in an article by L. D. Jaffe.' It was pointed out by that author that the hardening was the result of the decomposition of the retained j3 phase to the equilibrium constituents, a and p, and that this decomposition had many of the characteristics of an age-hardening reaction. Recent work by Frost et al.' 3 has contributed much to the fundamental understanding of the hardening mechanism in titanium-base systems. These authors established the presence of a transition phase in the transformation from j3 to a + j3, which they designated o. The transition phase, in their opinion, was at least partially responsible for the hardening and embrittling effects which accompanied low temperature aging. The present investigation of the mechanism and kinetics of the hardening reaction was carried out for the Ti-V system. Ti-V alloys were ideally suited for a study of the decomposition of j3, since age hardening was known to occur readily in this system." Moreover, no intermetallic compounds occur in this system, Fig. 1, thus simplifying the interpretation of the results. Material and Procedure Alloys containing 12.5 and 15 pct V were prepared by Battelle Memorial Institute from iodide titanium furnished by Watertown Arsenal and vanadium of 99.8 pct purity. Ingots of 8 Ib each were prepared by arc melting in an inert atmosphere with a tungsten electrode and water-cooled copper crucible. Each of the ingots was melted once, forged at 1600°, and rolled at 1400°F. Following this, the ingots were remelted, forged, and then rolled to % in. sq bars, which were subsequently grit blasted, pickled, and wire brushed. Another set of alloys containing nominally 17.5 and 20 pct V was produced by the Research Div., New York University. These alloys were arc melted in an inert atmosphere in lots of 20 g each. Heat-Treating Procedure: Whenever feasible, specimens were heat treated in high vacuum resistance furnaces at pressures below 5x10." mm of Hg. Aging and isothermal quenching treatments were generally carried out in salt baths. Specimens were not attacked by the salt, provided the tempera-

Jan 1, 1956

By Jun Han

Coal has been mined in the Kailuan mining area for more than 130 years. The remaining reserves consist of, in large part, coals that would have been considered economically unminable or technically not feasible by the previous generations. Some of the current operations have to resort to overmining because the lower seams had been extracted in the past. This paper deals with the feasibility and proper layout of mining roadways of overmining carried out in the No. 5 seam of Qianjiaying coal mine of Kailuan mining area using numerical and physical simulation. FLAC2D was used to investigate the characteristics of stress and displacement in the overburden after extraction of the lower seams. It also analyzed the proper layouts of gateroads in the upper seams, i.e. locating them in the stress-relief zone of the gob so that their stability can be easily maintained. In addition, a two-dimensional physical model was constructed for investigation of damages to the upper seams due to mining of the lower seams. Finally, based on the results of investigations, proper gateroads layout was designed and successful extraction was implemented for panel 1357 in the No.5 seam.

Jan 1, 2009

By S. Iverson

Fall of ground accidents continue to be a source of injury in underground metal mines. MSHA accident statistics indicate that most rock fall accidents occur at a new face where drilling and blasting methods are used. Removing loose rock by scaling is imperative to removing the potential for rock fall injury. Detection of potentially loose rock could improve the scaling process and result in fewer rock falls. Infrared thermal imaging cameras were investigated as far back as 1966 as a tool for loose rock detection. Early on it was clear that sensitivity (e.g. detectable temperature increment) is a key factor in this application. Both pixel resolution and temperature resolution have greatly improved with modern instruments. This paper describes an evaluation of modern infrared thermal imaging camera technology to detect loose rock conditions at six underground metal mines in the western U.S. It was found that thermal images provide a high resolution visual discrimination between loose rock and intact rock. However, detecting loose rock was difficult in cases where the rock and ventilation air were at the same temperature. Loose rock was detected when rock was both warmer and cooler than the ventilation air temperature. Warm rock with cool ventilation air provided the best conditions for detection.

Feb 23, 2014

By J. Härkki, R. Hiltunen

The Akanvaara intrusion (surface area 50-55 km2) in Savukoski, Northern Finland, hosts 23 distinct monocumulate layers of small euhedral chromite crystals enclosed in a silicate matrix. These chromitite layers have been divided into four groups; UC (upper chromitite), ULC (uppermost lower chromitite) LC (lower chromitite) and LLC (lowermost lower chromitite). The driving force for investigating the Akanvaara chromites and their reduction behaviour originated from their very low MgO content and relatively low Al2O3 content, giving them a unique quality which based on thermodynamics should facilitate the reduction. Another interesting feature is the high amount of V2O3 present especially in the upper chromitite. The chromites included in this study are from the UC and ULC layers (24.9 and 22.7 per cent Cr2O3 respectively). To obtain a better understanding of the reduction behaviour of Akanvaara samples in comparison to MgO-bearing chromitites, Kemi chromite from the ferrochrome works in Tornio, Finland, was included in the study as a reference sample. The reduction experiments were isothermal in a temperature range of 1000-1400°C in CO atmosphere. Experiments were also conducted with coke addition in pellets and briquettes in CO/Ar/H2 atmospheres. The results of the reduction experiments complemented with microanalytical research indicate that the Akanvaara chromites do reduce to a higher degree than the Kemi chromite. Although the aim was to characterize the mechanisms of reduction focusing on gas-solid reactions, the nature and amount of the gangue minerals was such that a considerable amount of slag phase was formed, which affected the reduction mechanisms extensively. The structural features together with low MgO and high FeO content in both Akanvaara chromites are important factors resulting in better reducibility than in the Kemi chromite.

Jan 1, 2004

By Jack L. Taylor

As expected from similar crystal structures and favorable atomic size factors, titanium, vanadium, and molybdenum are completely soluble in one another above the transformation temperature of titanium. The fl phase parameters of the continuous solid solution are shown graphically. Limiting compositions for retained fl phase have been determined. VANADIUM and molybdenum both have body-centered-cubic structures at all temperatures and, from the atomic diameter comparison factor, 3.9 pct, would be expected to form a complete series of solid solutions. The existence of complete solubility has been confirmed by work' at the Jet Propulsion Laboratory. Furthermore, vanadium and molybdenum have favorable atomic size factors to form complete binary solid solutions with the B phase, high temperature form of titanium, which also has body-centered-cubic structure. Pietro-kowsky and Duwez' and Hansen et al." have established the existence of the complete series of solutions in these binary systems. It would be logical, therefore, to expect that p-titanium, vanadium, and molybdenum would be completely soluble in one

Jan 1, 1957

By Hamid Maleki

A geotechnical monitoring program has been implemented at Energy West Mining Company for enhancing site-specific evaluation of longwall stress conditions. This program consists of underground measurements at five locations in two neighboring mining districts located in the Hiawatha and Blind Canyon Coal Seams under moderate to deep cover. Within the last five years, additional measurements, including data on recorded seismic events and face conditions, have been incorporated into the data collection program together with detailed geologic mapping of longwall gateroads. In conjunction with the measurement program, the authors have completed detailed boundary-element stress analyses of the mine plans. Models have been calibrated using the data from in-mine instrumentations and then routinely used for evaluation of mine plans at depths approaching 2,600-ft. The work has improved our understanding of load transfer, seismicity and yield pillar performance. It has identified areas of potential increased stress levels at certain longwall face positions and provided guidance to measures that could be considered to mitigate the potential for these increased stress levels.

Jan 1, 2009