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By M. D. Cooper

FOr the purpose of obtaining some first-hand data in regard to the shooting clown of coal in bituminous 'nines, it was the writer's good fortune to be employed as a shot-firer for almost one year. In all, 6,020 shots were fired by him during this period. All of the work was clone in what is known as the South Main section of the No. 2 Mine of the Ellsworth Collieries Co., Ellsworth, Pa., a subsidiary of the Lackawanna Steel Co. Position of Shot-firing in the Cycle of Operations The established practice of the Ellsworth Collieries Co. calls first for the undercutting of the coal by electric chain machines across the face of the entry or room. This is followed by replacing any posts removed by the machine-runners, or the setting of new posts or timber, as may be required. After this has been done the machine cuttings are loaded into cars. Then the coal is spragged, and a shot hole drilled to the depth of the undercut. Next in order, the shot-firer loads the hole and fires the charge. The working place is then cleaned up, timbered if necessary, the sides and face squared up, and loose material taken down. The face is again ready to be undercut.

Jan 1, 1917

By P. R. Bradley

This paper gives a brief history of the mining and milling operations in the Juneau gold belt, and a general description of the geology of the district, followed by a suggestive discussion of the general problem of sampling gold ores and a detailed description of the mining methods used in the Alaska Juneau mine. The paper indicates that variations in assaying ore similar to that from the gold belt are unavoidable on account of the erratic distribution of the gold. A caving system that accepts dilution was adopted for the Alaska Juneau mine; the ore is sorted and the final mill feed has nearly twice the assay value of the ore trammed. THE property of the Alaska Juneau Gold Mining Co., covering the Juneau gold belt for over a mile in length, consists of 136 claims and 24 mill sites; these are near Juneau, Alaska, in what is known as the Harris mining district.

Jan 3, 1924

By Frederic H. Wright

The secondary metals industry might well be defined as the group of remelters, smelters, refiners, and manufacturers that convert scrap metals or residues to commercial forms. In this industry, scrap metals and residues are processed to pro- duce refined metals, ingot alloys, fabricated shapes, and chemical products. Secondary metal is defined as metal recovered from commercial scrap, that is, scrap that has entered the processor's plant in scrap form. Metal recovered by a manufacturer from "home scrap" generated in his own plant is not considered to be secondary, because it represents part of the original stock that simply requires additional treatment before emerging as a finished product. In any economic study, a basic point of measurement must be chosen, and in the case of secondary metals, the melting pot or its counterpart represents the stage in which metal is converted from scrap to some more usable form. Beyond this point there is often no means to distinguish between secondary metal recovered from scrap and virgin metal produced directly from ore. In the last fifteen or twenty years the secondary metals industry has grown to major importance. Some consumers distrust secondary metals, but frequently this distrust serves only to prove an inability to keep up with the times. A rapidly decreasing number of manufacturers like to boast that they use only virgin metals, but a little investigation would show them that more than one third of all

Jan 1, 1943

By Nathaniel Hen

IN the United States, in the 2 1/2 years since the rescinding of the wartime order closing gold mines, conditions have not yet returned to normal. Shortages of man power have prevented some mines from operating at all, and most of those in operation are still at reduced capacity. This fact, combined with shortages of materials, the high cost of supplies and labor, high tax rates, and a fixed price for the product have made the past years rather rough ones for gold producers. In foreign countries conditions are rather similar. In Canada several new mines are coming into production and some others are enlarging. Costs have not increased as much as in the United States and gold production is being encouraged. Recently a bonus of 20 per cent on increased production has been proposed. In South Africa, where gold mining is of major importance in the national economy the industry is also in a favored position with government; new discoveries of major importance there will markedly increase the gold output. Demand for labor is rap-

Jan 1, 1948

Jan 1, 1956

By W. K. Tony Seiler

Further development of mechanical boring machines for hard and abrasive rocks will be effected by the development of more efficient rock cutting tools or the evolution of entirely new rock excavating principles. Presently the cutting tools suitable for extremely hard rocks and successfully and economically used with raise and tunnel boring machines are tungsten carbide insert big hole cutters. This paper explains the design, rock cutting principles, and actual boring operations to illustrate the capabilities and applications of tungsten carbide (TC) insert cutters. While the rate of borehole advance may fall short of the rapid excavating results achieved with soft rock boring machines, the cutter described in this paper may prove to be the most suitable tool in hard rock excavation for many years to come. DEFINITION OF HARD ROCK Existing bored excavations in hard abrasive rocks are proof of the economic application of new methods and mechanical rock boring in the mining industry. Most of the experience in cutting hard to extremely hard rocks has been gained in raise boring where relatively short and small diameter openings are bored. This poses a lesser risk regarding cutter cost than a long and large diameter tunnel and has therefore promoted the testing of various cutter products. Many types of rocks and geologic conditions were en- countered and actual test data was recorded in materials of up to 100,000 psi uniaxial compressive strength. To clarify the term hard to extremely hard, a 1970 interpretation of rock strength which was recently used is adopted and expanded in this paper.

Jan 1, 1971

By J. J. Scott

INTRODUCTION Rock mechanics theory needs to be applied to solve ground control problems, but in the final analysis the mining method and equipment which is used will be those which solve problems in a practical manner. Equipment and its inherent productivity and safety as supplied as "off the shelf" items by manufacturers often dictate the size of mine openings. Operators may tolerate falls of ground and associated hazards if productivity and safety problems are not too severe. In this whole process the costs of mining finally dictates just what system will be employed and what equipment will be used. True solutions to ground control problems sometimes require that the mine operator step back and totally rethink his problems. The true cost of accidents are often missed and hidden in overhead costs. Losses in production and accompanying profit are not fully considered, false economics, such as using inappropriate roof support devices, are undertaken at times when using the most expensive devices to totally eliminate accidents may be the best overall solution. Automation to remove the worker from the hazard area is often over- looked as the initial capitol expense to apply it may be high. Cooperation between mine engineers, mine operators, safety personnel, equipment suppliers, and government inspectors, both state and federal, is required to reach workable solutions that best meet the goals of all parties.

Jan 1, 1983

By Charles Reed

WITH the increasing importance of clay in drilling operations which demand more precise and exacting control over its behavior, there has come the realization that most of our present methods of control over many of its important properties still represent more of an art than a science. Such a situation with respect to a material of such industrial significance is unfortunate, and naturally many investigations have been conducted to improve our knowledge. In general, these investigations have revealed the complex nature of clay behavior and while sometimes they may not have seemed to contribute directly to a solution of the field operator's problems they have been of inestimable importance in bringing to light the broad fundamental scientific principles upon which must be based any effective working theory correlating the known facts of clay behavior and predicting profitable new lines of attack for its improvement.

Jan 1, 1938

By J. M. Gaines, C. H. Herty, M. W. Lightner, H. Freeman

Few subjects have attracted the attention of metallurgists more than oxygen in steel. From the days of Mushet and Ledebur interest in this subject has been increasing, and as additional knowledge has become available, the problem has naturally grown more complex. Instead of using the simple term "oxygen" we now distinguish between iron oxide, silicates of various kinds, oxysulfides, oxygen as gas and oxygen in solid solution in steel. There are five general methods for determining oxides in steel: hydrogen reduction; vacuum fusion; various wet-extraction methods, including electrolytic methods; methods depending on volatilization of the iron away from the oxides; and metallographic methods. For oxygen in solid steel each of these methods has both advantages and disadvantages. The hydrogen-reduction method is of no use on steels above about 0.20 per cent. carbon;' furthermore, it gives only FeO and possibly some MnO. The vacuum-fusion method2 is expensive and gives total oxygen, with the exception of some A12O3, and does not differentiate between the various oxides in which the oxygen exists. Most of the wet extraction methods3 give only the more insoluble oxides SiO2 and A12O3, though the iodine method gives MnO to an uncertain degree (information that may be more misleading than no information

Jan 1, 1930

By Paul L. Russell

Of the potential applications of nuclear explosives to mining, excavation is perhaps the most obvious and the best understood, and probably the most practical for use in the near future. Large quantities of rock and earth can be moved by proper emplacement of nuclear explosives, but economic and practical relationship must be determined between the known capabilities of nuclear explosives and the required excavating to remove overburden. On an energy yield basis, even the cheapest of the present commercial explosives cost more than the most expensive nuclear explosive. Comparing the energy yield of a megaton thermonuclear device with the yield of TNT shows that one energy yield per dollar is 400 times greater for the thermonuclear device. However, small-yield nuclear devices (a few 10's of kilotons yield) are less efficient blasting materials than chemical explosives, with the result that the heat of explosion is utilized less effectively. While only 1 lb of conventional explosive is required to excavate 1 cu yd of rock, or about 2 million cu yd per kiloton, nuclear devices excavate from 100,000 to 300,000 cu yd per kiloton. This changes the economic situation, and it is thus apparent that nuclear explosives are cheaper only for the large explosions.

Jan 6, 1964

By D. C. Anderson

Utah Construction & Mining Co.'s Lucky Mc mine is one of the major uranium producers in the United States. It is located near the geographic center of Wyoming in Fremont County. The climate is middle-latitude steppe, with an average annual precipitation amount of 10 in.; the temperature varies from 40º below zero to 100º above. The land surface is moundlike, rolling terrain, with sparse grass and sagebrush. The northern slopes of the higher ridges support a scattering of juniper and pi[n]ion growth. DISCOVERY The discovery was made by Neil E. McNeice, of Riverton, Wyo., on Sept. 13, 1953. After prospecting the area and staking a few claims, McNeice reported his findings to geologists of the Atomic Energy Commission (AEC), who immediately began preliminary studies of the numerous surface uranium exposures of the district. The discovery received widespread publicity, resulting in an intensive search for uranium throughout the region ; thousands of claims were staked. The AEC drilled several shallow holes near the discovery outcrop. Assays of cuttings from these holes confirmed the presence of a low-grade, oxidized uranium deposit. McNeice and his partner, L. A. Morfeld, tried to start a mining operation but were plagued by a lack of capital and technical know-how. They sought assistance from a Salt-Lake-City-based mining firm, the New Park Mining Co., engaged in underground base-metal mining in the Park City district of Utah. After a period of negotiations, New Park initiated activities that led to the forming of the original Lucky Mc Uranium Corp. The company started limited development drilling and mining operations in the summer of 1954, with the first ore production being shipped by truck to the Vitro mill in Salt Lake City. The mining

Jan 1, 1969

By William Fink

ALTHOUGH age-hardening in an aluminum-base alloy containing magnesium was observed by Alfred Wilm1 as early as 1911, it was not until 1919 that a theory of the mechanism of age-hardening was proposed. Merica, Waltenberg and Scott,2 studying the age-hardening character-istics of Duralumin at the National Bureau of Standards, came to the conclusion that age-hardening of this alloy is caused by the precipitation of CuAl2, which is less soluble at the aging temperature than at the solu¬tion heat-treating temperature. It was postulated that the initially precipitated particles were of fine colloidal dimensions but that they gradually grew in size. Maximum hardness was assumed to be attained when the particles reached a critical size. This theory was at first received skeptically, since it was a widely accepted view at that time that the solid solution state should represent the hardest state of an alloy. Shortly thereafter, Jeffries and Archer proposed their well-known "slip interference theory."3 They suggested that age-hardening was accomplished by the precipitated particles acting as keys interfering with slip along crystallographic glide planes. They showed that this mechanical theory led directly to the assumption that maximum harden-ing would be produced by particles of a critical size, which they suggested would have a diameter approximately 10 times that of the aluminum atom. This contribution amplified and explained so rationally the age-hardening theory of Merica, Waltenberg and Scott that wide accept-ance resulted.

Jan 1, 1939

Cobriza can only be described as the Machu Picchu of the mining business. This relatively new mine of the Cerro de Pasco Corp. in Peru, subsidiary of The Cerro Corp., was put on stream in December 1967. The best way to get there is to go in the company's HelioCourier with pilot Paco Perez. The plane is mostly engine and the pilot is without nerves. The trip starts at an elevation of 12,000 ft at La Oroya and ends at the Cobriza air strip near the top of the Continental Divide at 14,200 ft. Perez says this is the highest air strip in the world. The flight is made at an altibude below many of the peaks and it is easy to pick out the Inca Trail which follows the ridge line of the top of the Andes. Inca ruins are also visible from the aircraft. The drainage pattern, with a surprising number of lakes and rivers, can be seen and so, too, can a great deal of structural geology and numerous agricultural settlements dotting the altiplano. Cobriza is in the monta[n]a on the east side of the Andes, which is characterized by tropical climate and vegetation, an abrupt change from the frosty mountain atmosphere. The mountainsides are precipitous and the bottoms of the steep valleys are channels for roaring rivers. Such is the setting of Cobriza, above the swift cataracts of the Mantaro, benched out precariously at about 8700 ft elevation. The mountains rise in majestic splendor and the sun comes up late and sets at 3: 30 on winter afternoons. One of the lowest of the Cerro de Pasco camps, it is the most remote.

Jan 11, 1969

By Frederick A. Mumpton

For more than 200 years zeolites have been familiar minerals to geologists and mining engineers as minor, but ubiquitous constituents in vugs and fractures of most basalt and traprock formations. More than 35 different species have been recognized including several, such as chabazite, erionite, mordenite, and faujasite, whose adsorption properties rival those of many synthetic molecular sieves. Igneous occurrences of this type have never been mined on a commercial scale; they are generally small and low grade, and they commonly contain as many as four zeolite minerals, along with small quantities of calcite, quartz, and other silicate minerals. Their economic beneficiation to monomineralic zeolite products has also not been achieved and, for the most part, industrial applications of zeolites have relied primarily on synthetic molecular sieves that were crystallized from hydrous aluminosilicate gels. During the middle 1950s, when Union Carbide Corp. and other groups were developing processes and markets for their fledgling synthetic zeolite businesses, natural zeolites

Jan 1, 1983

By Morris M. Fine, Norwood B. Melcher

As a raw material, prereduced pellets can be considered symptomatic of the quiet revolution taking place in the quality and grade of blast furnace burdens for the past decade. In 1954, the average analysis of ores from U.S. ranges in the Great Lakes area was 50.86% Fe (natural), 10.22% SiO2, and 10.90% moisture; ten years later, the average was 56.67% Fe (natural), 8.13% SiO2, and 6.17% moisture. The advance in Canada was even more pronounced in a lesser number of years. In 1957 the average product of Canadian ore-producing areas was 51.62% Fe (natural), 8.59% Si02, and 8.02% moisture; in 1964, the average grade was 59.59% Fe (natural), 6.27% SiO2, and 3.94% moisture.2 These dramatic data are testimony to the giant strides made in iron ore improvement, and the next logical step is prereduction. Prereduction can well be considered as a beneficiation step in which oxygen is the gangue. Since the ultimate objective of milling and smelting is iron metal, non-metallic constitutents in general, whether oxygen or silica, are contaminants. The past and continuing attack aimed at lowering the silica content of concentrates is succeeding. One need only thumb through the Grade Name listings of the American Iron Ore AssociationVo note that virtually all commercial pellets contain less than 8% silica, many are lower than 6%, and a few below 45%. With natural technical evolution, it is expected "many" rather than "few" will ultimately be in the last category and further mechanical concentration will have reached the point of diminishing returns. At this level, oxygen would constitute the only major diluent worthy of attack.

Jan 7, 1966

By Shosei Serata, Bruce Gardner

A system of three new field instruments has been developed to measure, in situ, the three basic classes of geomechanical parameters: material properties, stress state, and creep deformation. The significance of this development is that it represents a successful adaptation of recent computer technology to underground rock mechanics work, opening up new possibilities in underground mining methods. The system was developed to meet the application requirements of the stress control method of mining, a method which is based on the actual geomechanical conditions of the underground, rather than upon conventional linear-elastic, idealizations of ground conditions. These instruments enable in situ measurement not only of elastic, but also post-elastic, yielding, and failure conditions of geological materials, establishing the stress control method on a truly scientific foundation. In order to evaluate the present status of this field instrumentation system, case examples of underground mine openings designed with the stress control method are reviewed and analyzed, in terms of the effectiveness of the three instruments for informing and guiding the site-specific application of stress control design.

Jan 1, 1984

Jan 1, 1915

By J. S. Fulton

Those who live in steel-mill towns are so accustomed to the sight of flames spouting from the mouth of a Bessemer vessel that they seldom pause to think of the amazing process behind it. Actually cold air is being blown through a hot liquid and, instead of cooling it, raises the temperature of the liquid. When coffee is too hot to drink, we know that blowing on it will cool it, so it was no wonder that when Henry Bessemer (or William Kelly, as your patriotism chooses) first proposed this cycle of steel production, he was considered mad. When Bessemer and Kelly started their investigations around 1852, there was not much practical knowledge of metallurgy and, in consequence, there was wide variation in the product made by their process. It was appreciated that the silicon, carbon and iron were all potential fuels, but not until Mushet discovered the beneficial effects of having manganese in the pig iron did the process really become commercial. Bessemer's patent of 1855 covered a crucibleful of liquid iron into which a refractory tuyere was lowered and the blow started. Since that time virtually every conceivable form of vessel, bottom arrangemerit, tuyere size and location have been suggested or tried. There have been stationary vessels with fixed bottoms, that were side, top or bottom blown; tilting vessels with two sets of side tuyeres at different elevations; vessels like a three-compartmerit septic tank; vessels of a cylindrical form supported on the long axis with tuyeres along the side submerged by a partial rotation of the vessel (this type continues in copper refineries); portable vessels to make the blow in a ladle over a mold in a foundry; a combination of a cupola and converter in one shell, and various other arrangements. But in all these experiments, compressed air for the blast was presupposed and there was little discussion of the quantity or quality of the air delivered to the tuyeres. At one time or another various practices that now are forgotten have been tried or suggested: for instance, the use of inert gas at the end of the blow; the addition of fuel to the blast; the use of hot-blast stoves; the drying of the air to a minimum moisture in the blast. Except in the last-named method little attention was paid to the quality or quantity of the air blown. Phases Of the many Papers published On various phases of the Bessemer process, nearly '7' according to one bibliography, Over go per 'ent were concerned with the metallurgical phase and less than '0 per cent discussed various sections of the pneumatic phase. Since the two phases are coincidental, apparently nine times as much thought has been given to the result as has been given to One of the causes of the Bessemer process. IS it not possible that if more attention had been paid to the pneumatics so many papers would not have had to be written on the troubles in the metallurgical phase? A study of published papers and conversation

Jan 1, 1941

By James O. Lewis

Gravity drainage is the self-propulsion of oil downward in the reservoir rock. Under favorable natural and operational conditions, it has been found to effect recoveries comparable to water displacement. With modern technical knowledge, the operator can often make a choice between dissolved gas drive, water drive and gravity drainage as the principal recovery agent in a reservoir. It is desirable that the opeator be able to determine which of the three agents will be most effective under each set of conditions. So far, gravity drainage has received less consideration than the other two. In this paper. an endeavor is made to set forth some of the principles of gravity drainage, to point out the types of reservoirs favorable for it, and to show how it may be applied in them. Field examples are described and discussed. Introduction Since early in the history of the oil industry, it has been recognized that gravity is one of the three important natural forces for expelling oil from the reservoir rock. As knowledge of the technology of oil recovery progressed, ideas changed with respect to the relative importance of the three forces and with respect to the manners in which they functioned. For a time, disproportionate emphasis was placed on the importance and function of gas and the need for conserving gas pressures. More recently, disproportionate emphasis has been placed on encroaching edge water. Only lately has there been evidence that the function and importance of gravity was to receive due consideration. Study of this neglected phase of oil recovery is needed to round out our knowledge of reservoir behaviors and to gain a balanced viewpoint of the interplay of forces that may operate in varying importance in reservoirs. The purpose of this paper is to discuss mainly in a qualitative way, the functions of gravity, to present some concrete instances where it has been important and to raise some questions that should be investigated further. Oil-recovery Agents The important natural agents for effecting oil recovery that may be originally available in a reservoir are gas, both dissolved in the oil and free in gas caps, encroaching edge water and gravity. Each of these agents can act in a dual capacity—physically to overcome the surface energies that hold the oil within the pores and mechanically to overcome viscous . resistance and to propel the oil through the porous reservoir rock to the wells. Advancing edge water displaces the oil from the pores and lifts it updip to structurally lower wells. Gravity drains the oil from the pores and flows it downdip to the wells. Gas displaces oil from the pores, entrains it in the gas stream and flows it to the wells, but gas in solution also affects the physical properties of the oil and thus can influence oil recovery by the other agents, whether or not the mechanical energy in the gas is utilized. Of the two functions of these agents, the more important is the ability to dis-

Jan 1, 1944

By James O. Lewis

Gravity drainage is the self-propulsion of oil downward in the reservoir rock. Under favorable natural and operational conditions, it has been found to effect recoveries comparable to water displacement. With modern technical knowledge, the operator can often make a choice between dissolved gas drive, water drive and gravity drainage as the principal recovery agent in a reservoir. It is desirable that the opeator be able to determine which of the three agents will be most effective under each set of conditions. So far, gravity drainage has received less consideration than the other two. In this paper. an endeavor is made to set forth some of the principles of gravity drainage, to point out the types of reservoirs favorable for it, and to show how it may be applied in them. Field examples are described and discussed. Introduction Since early in the history of the oil industry, it has been recognized that gravity is one of the three important natural forces for expelling oil from the reservoir rock. As knowledge of the technology of oil recovery progressed, ideas changed with respect to the relative importance of the three forces and with respect to the manners in which they functioned. For a time, disproportionate emphasis was placed on the importance and function of gas and the need for conserving gas pressures. More recently, disproportionate emphasis has been placed on encroaching edge water. Only lately has there been evidence that the function and importance of gravity was to receive due consideration. Study of this neglected phase of oil recovery is needed to round out our knowledge of reservoir behaviors and to gain a balanced viewpoint of the interplay of forces that may operate in varying importance in reservoirs. The purpose of this paper is to discuss mainly in a qualitative way, the functions of gravity, to present some concrete instances where it has been important and to raise some questions that should be investigated further. Oil-recovery Agents The important natural agents for effecting oil recovery that may be originally available in a reservoir are gas, both dissolved in the oil and free in gas caps, encroaching edge water and gravity. Each of these agents can act in a dual capacity—physically to overcome the surface energies that hold the oil within the pores and mechanically to overcome viscous . resistance and to propel the oil through the porous reservoir rock to the wells. Advancing edge water displaces the oil from the pores and lifts it updip to structurally lower wells. Gravity drains the oil from the pores and flows it downdip to the wells. Gas displaces oil from the pores, entrains it in the gas stream and flows it to the wells, but gas in solution also affects the physical properties of the oil and thus can influence oil recovery by the other agents, whether or not the mechanical energy in the gas is utilized. Of the two functions of these agents, the more important is the ability to dis-

Jan 1, 1944