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By Kikuo Matsui

Standing supports such as steel arches or square work supports along with the necessary struts and lagging have been traditionally employed in the longwall gateroads of the Japanese underground coal mines. Miike Colliery has newly introduced the interpanel-pillar mining system and the strata bolting system in gateroads to raise productivity levels and reduce operating costs. The Department of Mining Engineering, Kyushu University, in cooperation with the Miike Colliery and the Coal Mining Research Center, Japan (CMRCJ), has been conducting research into the optimum design of strata bolting as a primary support system in longwall gateroads. This paper presents a brief overview of the current state of strata bolting technique being applied in longwall gateroads at the Miike Colliery and discusses some problems in employing bolting.

Jan 1, 1993

By Thomas M. Barczak

Wood cribs are used extensively to stabilize mine openings by providing resistance to deflections of the immediate roof and floor and by supporting the weight of unstable rock masses. While the unit costs of these supports are relatively low, their extensive use results in significant costs to coal mining. The Bureau of Mines has developed a model that computes the load capacity of wood cribs as a function of the displacement of the crib structure induced by mine roof and floor convergence. This permits comparison of the loading characteristics of various crib constructions and enables systems to be designed with consideration of the load conditions imposed by the mine environment. The design method matches the stiffness, strength, and stability of the crib structure with expected rock mass behavior to determine a crib design and employment spacing that will provide the lowest cost support.

Jan 1, 1993

By William P. Blake

It is scarcely necessary to point out the important functions of water in the mining operations of man, especially in the State of California, where sluicing and hydraulic mining have been practiced on such a grand scale as to arouse the opposition of the agricultural interests. But the role which water and ice have played in mining or excavating on their own account is not so apparent. The alluvions of existing rivers, and the higher gravel-beds left by ancient streams, are doubtless the result of running water; but how far these gravelly materials owe their origin primarily as rocky debris and fragments of veins to glacial erosion, it is difficult .to determine. Yet we see on every side in our higher mountains unmistakable evidences of the cutting, crushing and eroding effects of glacial ice. We note that mountain-summits have been reduced in height and shaped into rounded and dome-like summits. We know that the general contour of the hills of New England, of the Highlands of the Hudson, and of the mountains of northern New Jersey, is due to glacial carving. The same is true of the Laurentian hills of Canada and of the mountains of all northern regions. And we recognize in the vast deposits of so-called " drift," which are spread out over the surface of the northern States, the chips and debris from the glacial workshops. Thus we cannot avoid the conclusion that there was an enormous amount of cutting and excavating in glacial times, and that vast quantities of veinmaterial and of ores and metals must have been liberated by ice-action.

Jan 1, 1900

By I J. Holland

Located in North West Queensland, XstrataÆs Mount Isa Copper Operations (MICO) is one of the largest underground mines in Australia with annual production exceeding six million tonnes of ore with average copper grades of three per cent. As at 30 June 2006, the Ore Reserve inventory totalled 87 Mt, with annual diamond drilling planned at >40 000 m in order to convert existing resources and test and define exploration targets. The role of the geology department within MICO is to collect, interpret and communicate relevant geological information to ensure the optimal extraction of ore. Routine underground inspections across multiple ore sources are undertaken and the information derived is then distributed to a range of professionals, operational personnel and management. The information is a æreal-timeÆ geological view for the stakeholders. Ongoing data collection and interpretation has developed a strong geological input to all mine planning processes within MICO. This has created strong synergies between mine planning professionals and a throughput benefit has been seen all the way to the concentrator. The MICO geological framework also provides avenues for a geological focus away from short-term production requirements, and as a result significant orebody scale observations and patterns have been realised that have led to an increase in the accuracy of geological and resource models. This has provided practical benefits for short-term scheduling and production, whilst enabling the realisation of long-term benefits that have a strong potential to increase the volume and value of the MICO resource. This paper will discuss the various mine geology contributions at MICO and illustrate some examples where mine geological input from graduate level has added significant value to the MICO business.

Jan 1, 2007

By H. D. Hoskold

It was not for the purpose of asserting any superior knowledge or authority, but simply of clearing up, in greater detail, some points casually mentioned in Mr. Scott's able paper, that the writer entered, some two years ago, into the discussion which that paper initiated. In such matters there is always room for differences of judgment, as well as for additional data, which may modify or complete the conclusions even of the best authorities. Those who are immersed in the duties of practical administration or work in the field, and who, being remote from the great scientific national libraries, are obliged to rely on their private collections, and to supplement them by their recollections of earlier studies, labor under special disadvantages in such a discussion; and it must be to the scientific and engineering world a matter for gratitude that Mr. Lyman has been willing to give the benefit of his advantages in this respect. Mr. Lyman would, however, doubtless at once disclaim the conclusion that his masterly summary constitutes " the last word " on this subject, and welcome further evidence, comment and criticism, such as the various contributors may continue to offer. This, therefore, is the motive, and must be the excuse, of the introduction by the writer of the following observations. The Miners' Dial.—Many years since, the writer employed a miners' dial, older in type than Fig. 12,* but without any attached spirit-level, made by Thomas Jones, a pupil of the great Ramsden. Jones was one of the old London makers and opticians, and enjoyed great reputation for accuracy in the con-

Jan 1, 1902

By Hugh S. Spence

THE use of natural feldspathic rocks, as opposed to straight feldspar, for ceramic purposes is not new. "Cornwall stone," a semi-kaolinized granite containing fluorite, has long been used by the English pottery trade instead of feldspar, and "Carolina stone," a similar rock, is now being offered to the American trade. A recent report of the U. S. Bureau of Mines states that trachyte, a glassy volcanic rock, is being used in California instead of feldspar in ceramic bodies. In Germany, phonolite and basalt have been investigated, and possibly also used, as ceramic raw materials, and extensive research has been conducted in Russia in recent years looking to the utilization of the immense bodies of nepheline syenite of the Kola Peninsula, which is the host rock of the apatite deposits now being exploited on a large scale in the Murmansk region; the nepheline is recovered as a by-product of the concentration of the apatite. Long used principally as a raw material for the pottery and allied industries, where, in bodies, glazes, enamels, etc., it serves as a fluxing ingredient and forms, on firing, a glassy bond with the more refractory clay, flint and coloring particles, feldspar has been finding ever increasing employment in glass. In 1936, over half of the nearly quarter of a million tons of feldspar sold in the United States went to the glass trade. Its usefulness for this purpose is due to the resistance to thermal shock which it imparts to glass products, particularly bottles, containers and tableware, because of its alumina content, which averages from 16 to 20 per cent. Active search has been made on the American continent during the past few years for other minerals of feldspathoid type, with comparable or higher alumina content, that may be suitable for glass and other ceramic purposes. One of the most important results of this work has been the delimiting in central Ontario of large bodies of nepheline syenite of excellent ceramic grade.

Jan 1, 1938

By D. K. Crampton

The object of this work was to obtain and correlate information on effect of internal stress in variously drawn tubes on several properties. Also, a simple approximate method of comparing types of stress distribution in such variously drawn tubes was sought. There is also included some work on comparison of single and polycrystalline materials and effect of different types of operation and preferred orientation. Preparation of Material A series of tubes was drawn to study the effect of the type and degree of final reduction on various physical properties and the approximate distribution of stress intensity across the tube wall. The material used all came from a single heat of 70-30 brass melted in a regular production Ajax-Wyatt induction furnace. The analysis of the metal as cast was: copper, 70.36 per cent; lead, 0.04; iron, 0.02; zinc, balance. The material was cast in "shells" with 4 in. outside diameter and in. wall thickness. It was drawn part way down according to the usual standard mill schedule and then by suitable individual schedules to finish by a variety of types and degrees of drawing to the same final cases in every instance; namely, 0.750 in. outside diameter by 0.080 in. wall thickness. The exact final draws, together with the percentage area reductions, diameter reductions and gage reductions are given in Table 1. In fabricating these tubes, rather unusual precautions were observed to insure the elimination of ail variables not under immediate study. All intermediate anneals were carried out at about 1200" F. down to the so-called "cut-in size"; namely, 17/16 by 3/16 in. From this point on, all anneals were made at from 1050' to 1100" F. The greatest care was used all through to have the tubes as free from minor surface defects as possible. When such defects were visible on intermediate sizes they were carefully filed out. On the final draw to 3/4-in diameter the die was aligned with the greatest possible precision in order to insure as straight a tube as possible

Jan 1, 1933

By L. J. Murphy

The production of crude oil in the United States is exceeding consumption by one-quarter million barrels per day and, with the possibilities of West Texas, this condition of overproduction, unless controlled, is likely to continue for some time. The resulting low price of oil has caused the operator to observe closely his lease operating costs. The installation of more efficient and reliable machinery has followed and it can well be said that the art of producing oil is on the threshold of a new era. In this advancement electricity has played a leading part. This paper covers only the problem of electricity as applied to lease operation and does not consider other phases of the industry, such as drilling and pipe-line pumping, in which electric power has been utilized economically. In considering electrification of pumping wells, the first question the operator asks is whether or not his costs will be reduced and the second question is whether or not the production will be increased. The third question, although in effect it is closely allied to the first, is the cost of power. The last question can be answered only after a thorough analysis of operating conditions and a study of the power rates prevailing in the particular field under consideration. Within the past few years, the power companies have realized the desirability of a steady 24-hr, pumping load, have made their rates for oil-field service particularly attractive, and in general have shown splendid cooperation in assisting the oil companies in the satisfactory application of electric power to their leases. When everything is taken into consideration, the first cost is practically the same for electric drive as for gas engines when pumping on the beam with individual motors. This cost, at prevailing prices, should aver-age approximately $2200 to $2400 per installation when using 15 to 35-hp., two-speed pumping equipment, including motor and control, countershaft, motor house, belt, installation charges, and a prorated portion of the cost of transmission lines and transformers for serving a number of wells. Since there is practically no difference in the cost of the two installations, it is evident that electricity, to justify its consideration, must have a lower operating cost or produce more oil.

Jan 1, 1928

By Jeffrey W. Lin, Jonathan D. Abbott, Patrick R. Bowden, Tyson J. Plitt

Pentolite is a class of high explosives containing trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN) with PETN content typically ranging from 40 to 60 wt%. Manufacture involves melting TNT, 80 °C, followed by addition of PETN and trace ingredients to form a homogeneous mixture. Once a mix is ready to be poured, several factors can influence the behavior of the finished product including how long the mix has been at temperature and cooling rate. After the manufacturing process has been completed, storage conditions combined with manufacturing conditions may cause physical changes. Two such changes explored were exudation, liquid exuding from solid boosters, and ratchet growth, irreversible volumetric expansion. Exudation is principally caused by excess water in the process. Ratchet growth is a common phenomenon of nitroaromatic compounds such as TNT where time and temperature fluctuations can cause materials to increase volume, simultaneously decreasing density. Although neither phenomenon affects common attributes such as sensitivity, performance, and shelf-life, both can cause issues in storage and handling. In this study pentolite was cast into various forms under different manufacturing conditions and evaluated over several months of controlled storage conditions including ambient, temperature cycling and elevated isothermal. Subjective and objective measurements were made throughout the evaluation period with the aim to determine the preferred storage methodology.

Jan 21, 2025

Any project carries a number of challenges and risks. Inappropriate design, poor project management, time, industrial disputation and capital over runs are all areas which can impact on a project cash flows and return on investment. In the resource Industry you have the added complexity and risk of geology which is difficult to predict and sometimes unforgiving. The Dartbrook Mine was designed and constructed as a high output longwall mine and has overcome a number of hurdles to produce over 2.3 million tonnes for the first year of operation. A number of problems were encountered during construction which resulted in the inseam development being delayed for six months. Dartbrook people have demonstrated they can manage adversity and produce world class results. The mine has been through a very steep learning curve during 1997 and with this experience behind the mine is now producing at an annualised rate of 3.4 MTPA.

Jan 1, 1998

By Jesus A. Pascual de Blas

After 30 years of development and introduction, electronic initiation systems are now well established in blasting applications, both mining, quarrying and civil works. In terms of blast technology, it could be considered that timing is the new challenge: how to define the most appropriate sequence to improve fragmentation, reduce vibrations, avoid dilution, eliminate damage… Some classic tools have been updated and adapted to the new scenario, and are giving us good performance; on the other hand, others should be considered obsolete, given the accuracy of electronic initiation systems has exposed these tools to incoherent conclusions. Besides, other tools have appeared and are in use, providing new approaches to old issues. Additionally, not only the technical side has to be considered: safety, security, economics are well present in daily blasting activity and affect to the final decision: are electronic initiation systems the right answer to my blast?

Jan 1, 2019

By C. G. Janes, N. Finkelstein, L. M. Jr. Johnson

In May, 1966, the General Services Administration (GSA) announced a program to encourage additional domestic production of copper in the interest of national security. Upon learning of the copper production expansion program, Duval Corporation entered into negotiations with GSA for development of the Sierrita copper-molybdenum property under the program. Agreements between the GSA and Duval Sierrita Corporation, a wholly owned subsidiary of Duval Corporation, were concluded in 1967, with the Sierrita Concentrator beginning operation in 1970 at a designed capacity of 72,000 STPD. Subsequent additions and modifications have expanded capacity to 90,000 STPD. This property, located approximately 20 miles south of Tucson, Arizona, represents an investment including working capital of about $200 million. These funds were provided from an $83 million loan from GSA, repayable in copper valued at 38 cents per pound, $48.75 million of bank loans subject to U. S. Government V- loan guarantees, and Company capital contributions. Current general operating statistics for the concentrator are listed below: Ore Grade 0.32% Cu., 0.030% Mo. Daily Tons Milled 90,000 STPD Annual Copper Production 94,600 Tons Annual Molybdenum Production 15,000,000 Lbs. Annual Silver Production 1,135,000 Ounces

Jan 1, 1976

By Howard L. Hartman

There is reason to believe that ventilation systems so far devised for use with continuous mining machines fall far short of success. This is vividly demonstrated to anyone who has observed in a continuous miner section the localized ignitions of pockets of gas and the generation of dense clouds of dust by the cutting head of the machine. The alarming frequency with which major ignitions and disasters continue to occur in modern mechanical mining and the rise in incidence of pneumoconiosis serve as reminders that our ventilation systems are far from achieving the ultimate in providing protection from either short-term explosions or long- term dust diseases, both of which take lives. Human safety is the main concern in ventilation. But in this day of high-priced labor, let us not forget human comfort, either, for this is a major factor in motivation toward high productivity. The failure or inadequacy of most mine ventilation systems in providing the kind of working conditions at the face that are conducive to productive as well as safe operation is an indictment of our environ- mental control program in mining generally.

Jan 3, 1962

By J. D. Miller, M. Misra

The processing strategy for the effective separation of bitumen from low grade (<l0 weight percent bitumen) Utah tar sands by a hot water process differs significantly from that used for the processing of high grade (> 10 weight percent bitumen) Utah tar sands. Excellent separations (coefficient of separation = 0.9) can be achieved for high grade Utah tar sands by intense hot water digestion followed by a modified froth flotation step. Such a technique is ineffective for low grade tar sands. In order to change the characteristics of the low grade tar sand an attempt was made to enrich the bitumen content of the feed to greater than 10 weight percent by recycle of bitumen concentrate to the digestion stage. However, the quality of the separation was not improved under these circumstances. Similarly feed enrichment by heat treating the low grade feed with recycled concentrate prior to digestion did not improve the separation. More successful separations of low grade Utah tar sands were finally achieved by modification of the viscosity of the low grade bitumen with controlled addition of diluent. These results of the hot water separation tests and variations in the quality of separation are interpreted in terms of the physical properties of the bitumen and the surface bonding forces operative at the bitumen-sand interface.

Jan 1, 1981

By K Ramachandra Rao

Joints, fractures and other structural defects bring anisotropic character Into a rock mass. Conventional methods of blast design In a rock mass consisting phyllites, mica schist etc., which are characterised by the presence of closely spaced, nearly vertical planar Joints, result In formation of large slabs which cannot be handled by the excavation and loading equipment without resorting to secondary blasting. Frequent secondary blasting Is not only expensive but also, Is a source of environmental hazard. Interruption of production cycles frequently, leads to uneconomical mining. This problem could be minimised by designing blasts which produce forces whose components along and across the joints/fracture planes Is lust sufficient to break the rock mass In both directions. Rock mass strength can be assessed from field and Laboratory tests. Projecting structural features with respect to bench orientation on a stereoplot helps In assessing magnitude and direction of force vectors required to fragment the rock mass to the desired size range.

Jan 1, 1995

By Robert S. Dalzell, Ernest A. Curth

Following the introduction of shields to the U.S. longwall mining scene and the steady increase in the number of shield faces during recent years, the occurrence of longwall -ground-control -associated accidents has shown a welcome downward trend. But even though the accident experience is favorable, problems exist. New mining systems, however efficient, have run afoul of roof control. Shield faces have suffered extended stoppages because of roof cavities. Therefore, the Bureau of Mines has reviewed foreign remedial techniques to evaluate their potential for domestic application. Such technology includes cribbing, strain absorbent modules (SAM&apos;S), inflatables, wire meshing, chemical rock stabilization, synthetic foams, and monolithic fills.

Jan 1, 1984

By Will H. Coghill, Fred D. DeVaney

THE coercimeter, as its name implies, is an instrument for measuring the coercive force[+] of magnetic substances. It was developed by Davis and Hartenheim in the Special Studies Section, Metallurgical Division. A detailed description of this apparatus may be found elsewhere.2 The coercive force determinations of magnetic materials are interesting because of the relationship established by Gottschalk,4 who showed a linear relationship between the magnetization coercive force and the specific surface of comminuted particles. The value of this relationship in determining grinding efficiency has been shown by Dean.3 The determination of the surface contained in the subsieve sizes has always been a difficult problem for investigators. They made approximate measurements of the surface of coarse materials by sizing on screens, but for the determination of the surface of the sub- sieve sizes it was necessary to make detailed grain counts or elutriation tests, or to study dissolution rates. The technical literature contains many references to other methods for determining these surfaces, either by some special apparatus or by mathematical calculations based on distribution lines. Many of the methods are long and tedious, and the results of some, at least, are questionable. The turbidimeter gives quick results on ground cement. By using magnetite as the material to be ground, a simple determination of its coercive force by the coercimeter, requiring 10 minutes or less, can be transposed directly and accurately into units of relative surface. This subject has been pursued further by the U. S. Bureau of Mines in cooperation with the Missouri School of Mines and Metallurgy, Rolla, Mo., and the following is a description of the results.

Jan 1, 1938

By T. M. Berry

FOR the past several years it has been growing practice to install circular shafts at deep mining operations. Several factors have brought this about. Throughout eastern and midwestern coal fields circular shafts have been conventional for many years. Where large bodies of coal are mined, a production shaft may have a life of 20 to 30 years. Quantity production is essential; therefore the shaft must have a large cross-sectional area for larger skips and cages. Mechanical mining has become a necessity if a company is to stay in business today. Continuous mining machines and cutting, loading, and hauling equipment must be taken in and out of the mines. If the access shaft is not large enough there will be expensive dismantling and assembling. This has become a problem at many operations, particularly in the western sections where ore was originally mucked by hand into small cars and hoisted by a skip through a narrow rectangular shaft having small compartments. Mechanical loaders must be dismantled to wheelbarrow size to go into these mines.

Jan 7, 1957

By A. Blackmore, D. Baker, L. Human

"Mechanical mixing equipment is common in a wide variety of mining, metals and process applications, such as hydrometallurgical reactors, solvent extraction, digestors, and tanks for storage of slurry or hydrocarbons. Computational Fluid Dynamics (CFD) has been applied successfully to single-phase mechanical mixing problems for several decades and is established as a reliable design tool. As computational power and CFD codes have improved over the years, there have been significant advances in modelling capabilities including improved models of turbulence, interaction of rotating and stationary components, multiphase flows, and modelling of free surface interfaces, for example. This paper will provide an overview of the application of CFD to mechanical mixing problems. First, it will review the traditional single phase Multiple Reference Frame (MRF) approach and introduce a range of advanced modelling techniques. Three examples of the application of CFD to industrial mixing problems will be given. It will be demonstrated that CFD is an effective tool for reducing technical risk in design, for identifying the root-cause of mixing problems, and testing modifications to existing operations."

Jan 1, 2015

By J. Drenda

The model for methane removal from the workings directly behind an advancing longwall as presented in this paper may be used for U-ventilated cross or length-wise systems of longwall advance, starting from the boundaries of the extraction field. In mines with high methane concentrations, Uventilated longwall extraction from the boundary of the extraction field produces a methane risk. The risk is manifested by a higher methane concentration at the end of the longwall, upper gate and incline. The methane in increasing concentrations, which is emitted mainly from the workings with caved areas, appears towards the end of the longwall and in the upper gate. The graphical model of the longwall provided includes both the workspace of the longwall and the caved area. Based upon a model of the rock distribution in the cave, a ventilation model comprising two standard air splits and large number of crosswise air splits has been constructed. Simulations indicate that if the shearer is not present in the longwall, the air distribution in the caved area is symmetrical. The presence of the shearer, both at the bottom and the top of the longwall, causes an asymmetrical air distribution in the cave, that is the asymmetrical flows in the goaf and longwall workspace and in the inflows and outflow between those regions. This phenomenon causes an increase in methane concentration at the end of the wall and at the upper gate. The methane removal method proposed for workings with a caved area directly behind the advancing U-ventilated longwall, starting from the boundary of the field, consists of the removal of methane-air mixtures from the caved area with the boom pipes. These booms may be of several meters long and may be extended if necessary. The insertion of the boom pipes into the cave towards the end of the longwall and connecting them with the general methane removal system creates negative pressure causing a change in the depression field, which is the aerodynamic potential field in the goaf area around the ends of the boom pipes. This will promote the extraction of the methane-air mixture from voids and the goaf cracks, and the area from which methane is being extracted may extend to the side of the cave. This is a positive phenomenon, which could result in the methane flow from the goaf into the airflow in the longwall workspace decreasing or even stopping. A reduction in the methane flow into the longwall workspace with extractions booms will be advantageous for the production continuity. Based on the floor load model for the rocks in the cave and the methane-removal boom load model, the value of the force required to move the boom behind the advancing wall has been calculated. Strength calculations for the pipe were performed using a finite elements method. The analysis results, as well as the comparison of the pipe material effort to the strength parameters of steel, which can serve as piping material (for the assumed load conditions), lead to a belief that the proposed boom construction satisfies the strength requirements.

Aug 1, 2013