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By William G. Pariseau

A plasticity theory for anisotropic geologic media has been applied to the problem of quasi-static wedge penetration of rock under confining pressure. Numerical evaluation of the governing system of stress equations in the transversely isotropic and orthotropic cases using representative material properties shows that the consequences of initial anisotropy for the penetration process are by no means trivial. In the transversely isotropic case, a threefold increase in the vertical force required for penetration to a unit depth occurs as the inclination of the axes of anisotropy are rotated through 90° with respect to the penetration path. The horizontal force required varies from zero to a maximum at approximately 60° then back to zero as the axes of anisotropy are rotated. The maximum is of the order of magnitude of the force required in the isotropic case. Similar results are observed in the orthotropic case. Practical aspects of the post-elastic phenomena associated with anisotropic rock indentation within the context of drilling problems include: bit yaw, hole deviation and bending stresses in the drill rod, all of which vary with strata dip but which can be quantitatively evaluated given the bit geometry, interface friction and rock properties. In a broader context, the analysis reveals the necessity for well conceived experimental work and sound theoretical research concerning post-elastic behavior of geologic media as a function of confining pressure, the effects of induced anisotropy, and the variation of strength parameters with loading path changes in the post-elastic range.

Jan 1, 1971

By G. H. Billings

THERE exists an unconfirmed opinion among many ironmasters that the combination of a small quantity of manganese, chromium, titanium, tungsten, aluminium, nickel, and some of the metalloids with iron has a beneficial effect upon the quality. And the impression prevails in some localities that the excellence of steel greatly depends upon the influence of some of these elements. But as the recorded experiments are so meagrely described, and made under such various conditions, the student in search of information upon the subject is somewhat bewildered by the contradiction of the opinions expressed. Observing some interesting phenomena while experimenting with an alloy of iron, copper, and nickel, I was led to determine the effect of some of the metals upon iron as free from contamination by other elements as it is possible to procure in prac¬tice, in order that the result of an alloy of an individual metal with iron might be more closely studied ; for it is almost an impossibility to determine the influence of a small amount of one element upon a metal combined with a large amount of another, and the mere presence of another sometimes makes this difficult. And as most of the experiments recorded upon this subject have been made with iron containing sufficient carbon and other elements to interfere with the effect of that metal the influence of which it was desired to observe, I have endeavored to avoid these sources of error as far as practicable. In determining the specific gravity of the alloys in these ex-

Jan 1, 1877

By C. E. Capes

A number of novel but increasingly-important methods of size enlargement in liquid systems are reviewed. These techniques use relatively strong bonding and specialized equipment to form dense and substantially permanent agglomerates directly from particles in liquid suspension. In addition to separation of particles from suspensions, these methods have other broad objectives, including the production of granular (often spherical) materials, displacement of suspending liquid from the product and the selective agglomeration of one or more components of a multi-particle mixture. The underlying principles of the methods discussed include agglomeration by immiscible liquid wetting and by polymeric flocculants. Other procedures to produce granular, free-flowing products based on dispersion and solidification in liquids are also noted briefly. Applications in a variety of fine particle systems are considered with emphasis on minerals and fuels beneficiation and on waste treatment.

Jan 1, 1980

By Ahmad Saberian

Five salt samples 20 to 40 cm tall, sealed on all sides except one, were exposed to a series of dissolution tests in various brine solutions and at different temperatures. Solvents were in the 50 to 96% saturation range and the temperatures varied between 40°F and 150°F. The collected dissolution data sets for vertical salt surfaces were analyzed and three were selected to be used for developing a general relation. After various curve fitting efforts, an empirical relation for salt dissolution rate as a function of brine temperature and salinity was developed.

Jan 1, 1985

By Sylvia Whitehead, G. M. Schwartz, J. N. Gundersen

Sylvia Whitehead (Petrologist, The Broken Hill Propriety Co. Ltd., Melbourne, Australia) — Examination of thin sections of jaspilites from numerous banded iron formations in Australia has revealed no evidence to suggest that silicate minerals have formed by reaction between magnetite and silica. Textural relations indicate that part of the magnetite crystallized very early in the history of the rocks, probably during diagenesis, and remained stable under conditions of metamorphism altering only to hematite or limonite under conditions of oxidation and weathering. Many jaspilites also contain later magnetite which is almost certainly of metamorphic origin. Wherever magnetite is present in quartz rich bands containing little or no silicate or carbonate, it is very fine grained and occurs generally as isolated, well formed octahedral crystals or as small crystalline aggregates. These show no evidence of corrosion or reaction with the quartz even in rocks where adjacent bands contain silicate minerals of moderate to high metamorphic grade. Concerning the silicate minerals, it is reasonably certain that bands of very fine grained stilpnomelane

Jan 1, 1963

By Sam Rosenblum

The anomaly ratio is obtained by dividing the analyzed value of an element by the anomaly threshold value of the element. The sum of anomaly ratios for all anomaly elements in a sample may be compared with similar sums for other samples, so that samples having the greatest anomaly- ratio totals can be recognized easily. In partial or full suites of ore elements the we of anomaly ratios is more meaningful than use of analyzed value because the ratios quickly indicate how use of analyzed values because the ratios quickly indicate how anomalous some elements are, and call attention to samples and

Jan 1, 1982

By Donald W. Mitchell

MINE operators have a choice of several classifications of mechanical loaders. Within each classification there are many types and makes available. Table I lists loaders on which manufacturing data as to operating characteristics are available. This paper discusses the conditions met in a mine as they affect these characteristics. It is assumed that management will provide satisfactory engineering, supervision, power, maintenance, loader service within a concentration of workings, and a balanced working cycle served by balanced production equipment. These are factors which affect the optimum operational efficiency of a loader. The conditions which determine loader choice are:

Jan 5, 1951

By R. W. Braund

THE Tracy mine is within the corporate limits of Negaunee, Mich. The tract of land comprising the Tracy group lies on the east end of the Marquette Iron Range between adjoining mined-out properties on the north and south. Since acquiring the Tracy lands in 1921, Jones & Laughlin Steel Corp. has completed about 115,- 000 ft of surface diamond drilling, partially outlining five orebodies. Now that mining has started, one or more underground drills are in constant operation to obtain information that will aid mine development planning. Some 20,000 ft of underground drilling have been completed to date.

Jan 1, 1958

By Alvin L. Langstaff, Harold D. Raymond

The design of entry systems and mining panels in room-and-pillar oil shale mines seeks to optimize extraction while ensuring both short- and long-term stability of mine openings. Important criteria for optimization include the definition of allowable roof spans and minimum pillar dimensions. Factors considered pertinent to the design of roof spans and pillars are discussed in this paper. They include, but are not limited to, physical properties and grade of the oil shale, depth of burial, presence and frequency of partings and joints and adverse effects of blasting. Also discussed briefly are some of the ventilation and production considerations in mine design.

Jan 1, 1984

By Paul B. Barton

Unconventional mineral deposits are those that differ significantly from productive deposits in mineralogy, grade, or geologic setting. Thus, the initial representatives of each deposit type are, by definition, “unconventional” until they are exploited. The “unconventional” status changes to "conventional" because of economic shifts (e.g., bulk silver ores), because of technological innovations (e.g., froth flotation), or simply through the recognition of, and production from, novel mineral concentrations. Heretofore the discovery of new deposit types has been almost entirely accidental, but the long- established concept of the geochemical cycle provides a nearly untouched opportunity and challenge for the application of geochemistry in predicting novel, potentially economic, mineral concentrations.

Jan 1, 1983

OFFICIAL Washington is gravely concerned over the adverse military situation caused by the all-out intervention of the Chinese Communists in Korea. What the policies of the United Nations and the United States will be in the new crisis is unknown. However, Stuart Symington, chairman of the NSRB, set the general pattern for mobilization in the near future when he said that this country would move from a "light gray to a dark gray mobilization." The implications of accelerated mobilization for the mining industry are particularly apparent with respect to the manpower situation. Revised policies recently initiated for the recall of reservists may be abrogated, in which case key personnel in the mining industry may face calls to active duty with insufficient consideration given to their indispensability to national defense in their present positions.

Jan 1, 1951

By S. E. Craig

Jen Inc., operator of the Cord mine, in the Big Indian district of San Juan County, Utah, has a contract with a milling company that provides a small bonus for proper grading and preparation of uranium ores shipped. To obtain maximum returns on this contract very close grading is required with settlements made on individual lots, which vary from 250 to 300 tons. Another feature of the contract, and one that is rather unique in this country, is that the ore is sold over truck scales at the mine. Grade is determined at the buyer's sample plant. It is necessary to take a moisture sample of each truckload shipped for ac- curate weighing and this is done by the representative of the buyer, using facilities supplied by Jen Inc. The sample is hardly more than a grab sample and includes only the finer and smaller pieces of the ore shipped.

Jan 10, 1958

By J. E. Campbell, H. E. Parkinson, Y. P. Chugh

Miner-bolters, which combine mining and bolting functions into a single machine, are being developed by the US Department of Energy to improve production and productivity in coal mining operations. The authors have been studying possible production gains from the use of the Joy automated miner-bolter (AMB) in mine development using the computer simulation model "UGMHS" developed by the Pennsylvania State University. In a recent paper (Chugh, Campbell, and Parkinson, 1979) the authors discussed justification for the development of miner- bolter machines, assumptions and analytical procedures used in computer simulation, cutting, and bolting cycle times for an AMB, and production potential of AMB in four and five entry mine development sections. The effects of available operating time, haulage capacity, bolt installation time, and flush and staggered entry layouts on production potential of AMB were also discussed. In all cases, the production potential of AMB was compared to a full face continuous miner and an independent dual-boom roof bolter operating in a similar mine layout. Present Study In this study, the production potential of the Joy AMB in three and six entry layouts is presented. A three entry mine layout represents development entries in a longwall panel. A six entry layout represents development of main and submain entries in longwall mine development. Flush and staggered entries were considered in both layouts. The assumptions and analytical procedures used in this study were similar to those in the earlier study and are not presented in this paper. Only the results of the studies are presented here.

Jan 1, 1984

By D. C. Jones

The term "coal-mine mechanization" is definable in several ways. In its general application it can mean the use of machines instead of manpower in each of the various mining activities necessary for the production of coal—so that under this definition a mine that uses mechanical coal cutters could be classed as a mechanized mine. Common usage, however, insists that a mechanized mine is one in which machines are used for the entire process of mining or extraction and transportation of the coal. For the purpose of this paper, then, the second definition of "coal-mine mechanization" will be used, and practices employed in mines where the greater part of the production is obtained through the use of mechanical loaders and conveyors will form the basis for this discussion. Physical Contact Hazards If we were to group all the hazards that accompany the use of mechanized equipment in a mine, the predominant class would be that which, for want of a better name, might be termed the "physical contact" hazards; that is, all the sources of danger that lead to accidents through physical contact of workmen with machines. A survey of accidents in a group of mechanized mines indicated that this class of hazards may be responsible for more than half the number of accidents in mechanized mining. For example, of 21 mining-machine accidents at one mine, 14 were of the physical contact type; of 14 loading-machine accidents at the same mine, 8 were the result of physical contact. Certain of these hazards are controllable through the use of guards— a guard over the cutting-machine bits when the machine is being trammed from place to place, or a chain or some similar locking device around the cutter chain, so that an accidental blow or push against the bit control will not cause the cutter chain to move. Other hazards, such as the possibility of a loader operator having his foot crushed by a crawler tread, or a brakeman being hit by a loader boom swung too far to one side while a car is being loaded, might be subject to control through the use of guard devices, but the reduction or elimination of all physical contact hazards by such methods does not appear feasible. Every accident of the physical contact type should he investigated to discover whether guards could have prevented it, but often the only way in which to combat these hazards will be through the awakened consciousness of each workman as to the danger that exists if he indulges in unsafe practices. A good approach to control of accidents in any mine is the establishment of a set of safety rules or operating rules. The intent of such rules is to provide guides far the workmen to follow in the operation of equipment. Frequently the workmen have no regard for such rules, and observance is obtained only through compulsion on the part of management. An interesting development in connection with-the formation of safety rules occurred during a training program for employees in the

Jan 1, 1947

By D. C. Jones

The term "coal-mine mechanization" is definable in several ways. In its general application it can mean the use of machines instead of manpower in each of the various mining activities necessary for the production of coal—so that under this definition a mine that uses mechanical coal cutters could be classed as a mechanized mine. Common usage, however, insists that a mechanized mine is one in which machines are used for the entire process of mining or extraction and transportation of the coal. For the purpose of this paper, then, the second definition of "coal-mine mechanization" will be used, and practices employed in mines where the greater part of the production is obtained through the use of mechanical loaders and conveyors will form the basis for this discussion. Physical Contact Hazards If we were to group all the hazards that accompany the use of mechanized equipment in a mine, the predominant class would be that which, for want of a better name, might be termed the "physical contact" hazards; that is, all the sources of danger that lead to accidents through physical contact of workmen with machines. A survey of accidents in a group of mechanized mines indicated that this class of hazards may be responsible for more than half the number of accidents in mechanized mining. For example, of 21 mining-machine accidents at one mine, 14 were of the physical contact type; of 14 loading-machine accidents at the same mine, 8 were the result of physical contact. Certain of these hazards are controllable through the use of guards— a guard over the cutting-machine bits when the machine is being trammed from place to place, or a chain or some similar locking device around the cutter chain, so that an accidental blow or push against the bit control will not cause the cutter chain to move. Other hazards, such as the possibility of a loader operator having his foot crushed by a crawler tread, or a brakeman being hit by a loader boom swung too far to one side while a car is being loaded, might be subject to control through the use of guard devices, but the reduction or elimination of all physical contact hazards by such methods does not appear feasible. Every accident of the physical contact type should he investigated to discover whether guards could have prevented it, but often the only way in which to combat these hazards will be through the awakened consciousness of each workman as to the danger that exists if he indulges in unsafe practices. A good approach to control of accidents in any mine is the establishment of a set of safety rules or operating rules. The intent of such rules is to provide guides far the workmen to follow in the operation of equipment. Frequently the workmen have no regard for such rules, and observance is obtained only through compulsion on the part of management. An interesting development in connection with-the formation of safety rules occurred during a training program for employees in the

Jan 1, 1947

By E. Maltby Shipp

E. MALTBY SHIPP.-It was the intention of the Committee on Safety anti Sanitation to collect information and useful data from the companies having well-organized safety departments and print this in pamphlet form for distribution among the small companies that have no way of employing safety engineers nor have at their disposal these data. Consequently, I took these rules and the general data, especially the rules, went over them a great many times and tried to cut out whatever duplications appeared.

Jan 4, 1917

By George Frederick Kunz

The garnet-district of Bohemia is situated about 60 kilometers northwest of Prague, and is bounded on the north by Meronitz and Trebnice, 12 miles apart, and by Decany and Skan on the south. This region is covered with alluvium resting on the diluvium, which

Jan 1, 1893

By Waldemar Lindgren

CONTENTS. [ ] I. INTRODUCTION. THE precious metals, gold and silver, are the basis of the monetary systems of the world. It is, therefore, natural and inevitable that widespread interest should be manifested in their production and in the various classes of deposits in which they are contained. At times a great scarcity of the precious metals has prevailed; at other times the production has seemed so abnormally large that fears have been entertained regarding their ultimate retention as standards of value. Since most nations have adopted the gold standard, and the remaining ones appear likely to do the same in the near future, the question of available supply of gold for the present and future very naturally arises. This necessarily involves a consideration of the characteristics of the gold-deposits. After the absorption of the gold treasures of the New World by the conquistadores, the gold-placers of Brazil and Russia

Jan 1, 1913

By Thomas M. Tharp

INTRODUCTION Attempts to analyze the stability of slopes, foundations and underground openings in discontinuously jointed rock have generally assumed full joint continuity or ignored the role of stress concentration at the tips of discontinuous joints. The most common approach in rock slopes is to consider a failure plane consisting of coplanar, but discontinuous joints separated by intact rock. The intact rock is assumed to fail in shear as a Mohr- Coulomb material and to contribute a strength component proportional to the fraction of the failure plane that is intact rock (Jennings, 1970). An alternative approach by Stimpson (1978) applies Lajtai's (1969) theory for shear strength of discontinuously jointed rock masses to slopes. Lajtai allows tensile failure in the intact rock of a composite surface. This theory yields lower shear strength than that of Jennings (1970) except in the presence of high normal compression, however it also fails to account for the stress concentration at the tip of a discontinuous joint. For a given slope geometry, stresses increase with slope height, but in both of these models rock mass strength is independent of size. A fracture mechanics analysis shows that particularly for small slopes, rock mass strength decreases with size. A continuous stepped failure surf ace produced by propagation of preexisting joints may develop at lower shear stress than predicted by the Jennings (1970) or Lajtai (1969) models. This fracture mechanics model applied to slopes in competent rock is more realistic in its assumed failure mechanism, and for large slopes more conservative than the Jennings (1970) or Lajtai models (1969).

Jan 1, 1984

By Ed Ramsay

The Kerr Addison process involves the cyanidation, flotation, and roasting of graphitic gold ore. The grinding and treatment section of the present mill has at the present time a capacity of 1400 stpd and the precipitation section has a capacity of 6000 stpd. The grind is maintained at 80%, -200 mesh, and a gold recovery of 92% is obtained in the cyanidation circuit. With flotation and roasting, the overall gold recovery is increased to 98%.

Jan 1, 1978