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By Bashir Ahmed, Fred D. Wright

Numerous investigators have studied the various factors that influence the ultimate strength of model mine pillars, such as ratio of height-to-least width; restraint or friction on the top and bottom; 1,2 the effect of stress distribution in pillars on their strength;3 and the scaling factors involved in applying the results of model pillars to full-scale pillars. However, the load-bearing capacity of pillars after initial failure does not appear to have been investigated. Yet many mines employ methods in which small pillars or pillar remnants are left systematically; these pillars crush as mining progresses and, of necessity, affect the behavior of surrounding rock even after initial failure. The effect of such crushed or crushing pillars depends largely on their load-deformation characteristics. This chapter presents the results of a preliminary investigation to determine the load-deformation characteristics of a few model mine pillars to and beyond initial failure. Various investigators have also studied the elastic and viscoelastic behavior of mine structures. In such studies, computers are frequently employed to obtain numerical results by the finite difference or finite element methods. It would be entirely feasible to write a program that would approximate the load-deformation characteristics of pillars to and beyond the crushing stage if these characteristics were known. More accurate information on the induced stresses and deformations in overlying strata and on surface subsidence could be obtained, information which should result in better strata control by enabling the engineer to calculate more accurately the effects of changes in pillar spacing, size, and shape.

Jan 1, 1972

By Raymond E. Riethmann, Beuford M. Bunnell

The spiral classifier was originally developed for closed circuit grinding It has since been applied very successfully to other classification duties where a two-product size split is required. Inherent operational qualities of this classifier make it ideally suited for sizing, washing, or dewatering materials such as ores, phosphate rock, sands, coal, oyster shells, solar and potash salts. Operating characteristics, flexible design and guidelines for proper application are presented.

Jan 1, 1978

By Vytas Svalbonas

Sophisticated computer analysis methods such as finite elements, finite differences, and numerical integration have become tools in the mineral processing industry for design of large mill shells. While use of such methods allows the analyst-designer to take new freedom with his designed structure, there are also pitfalls and dangers which must be recognized for the proper use of such sophisticated tools. One of the worst of these is treating any computer answers as "gospel truth." The present paper discusses the knowledge required by the analyst-designer for proper use of computer analysis, as well as explaining to the layman how to identify questionable areas in such structural analyses.

Jan 1, 1980

The 118th meeting of the Institute was under the auspices of the Institute of Metals Division and the Iron and Steel Section, and was held at Milwaukee, Wis. The opening session was a joint meeting with the American Foundrymen's Association and the American Malleable Castings Association, and was presided over by Benjamin D. Fuller, President of the American Foundrymen's Association. At this time Hon. Emanuel

Jan 12, 1918

By S. C. Sun, D. R. Mitchell

Experiments show that ores such as tungsten and tin, which slime excessively, can be deslimed and upgraded by ultrasonics. The method proposed depends primarily upon the stratifying and peptizing action caused when high frequency sound waves are propagated upward through ore pulp in a cylinder tube. Stratifying and peptizing are somewhat hindered by the accumulating action, which embodies additional effects of reflection and refraction.

Jun 1, 1956

By F. W. Miller

Prior to the Civil War, there were several small charcoal furnaces for smelting the brown limonite ore that is found, in comparatively small bodies, throughout the central and north-central portions of the state. During the Civil War, these furnaces furnished charcoal iron to the Confederate Government. No attention was paid to the large bodies of lime-bearing hematite ore that now supplies the bulk of the ore used in the various blast-furnace plants of this district until the latter part of the 19th century. Red Mountain, which is the southernmost and one of the smaller ranges of the Appalachian Chain, lying immediately south of the Birmingham and Bessemer, is the principal source of this ore. The orebody outcrops on the northern face, extends through the mountain, and underlies Shades Valley on the southern side. When it was found that these ores could be worked satisfactorily in the blast furnaces, there was a comparatively rapid growth in the blastfurnace industry in the Birmingham district. As these ores are far more refractory than the limonite ores, this blast-furnace development was accompanied by the construction of beehive ovens to carbonize the coal, in order to supply the necessary fuel. The state's production of beehive coke in 1880 was 60,781 tons; ten years later this had increased to 1,072,942 tons; and, in 1897 the production had reached 1,443,017 tons. In 1898, the first byproduct oven built in the state was put in operation. This plant consisted of 120 horizontal-flue Semet-Solvay ovens, three flues in height by thirty flues in length with an average width of 16 in. The plant was constructed by the Semet-Solvay Co., for the Tennessee Coal, Iron & Railroad Co., and was located adjacent to the blast-furnace plant of that company at Ensley. Coal was delivered from the Pratt mines, by gravity tracks, directly into bins of the ovens after having

Jan 1, 1925

By Y. P. Chugh, R. F. Roethe

Surface coal mining productivity in the US and Illinois has declined since 1969. The US Department of Energy conducted an analysis in 1980 of the causes of declining productivity in different states. This paper presents a detailed analysis of changes in overall productivity and productivity in different functions, such as overburden preparation and stripping, reclamation, and coal handling, from 1970 to 1982. Statisical analysis techniques, including multiple regression were used in the study.

Jan 1, 1985

The Library of the above-named Societies is open from 9 A. M. to 10 P.M., except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information, will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will he sent more promptly and in more usable shape.

Jan 8, 1917

By P. H. Royster

IN a study of the blast-furnace process, the Bureau of Mines has made many experiments for the purpose of determining the exact nature of the combustion of coke in the neighborhood of the tuyeres. Two papers1 presented at a meeting of this Institute discussed somewhat the practical aspects of coke combustibility in its relation to the operation of the blast furnace. In a later paper,2 Sherman and Kinney discussed the possible effect of variations in the combustibility of cokes on the furnace operation, and find that the "reoxidation theory" of Koppers and the "heat concentration theory" of Brassert3 are insufficient to explain the variation in the conduct of different cokes that has been observed by furnace operators. In their report to the D-5 Committee of the American Society for Testing Materials, with which the Bureau of Mines has been cooperating, Perrott and Fieldner4 seem to agree with Sherman and Kinney that, for practical purposes, the nature of the combustion of coke at the tuyeres of any furnace is constant and is affected neither by the physical properties of the coke nor by the nature of the furnace operation. They omit as unimportant any tests on the combustibility of coke from their proposed methods for standard tests on coke. In the last two papers, it is pointed out that performance tests, in which all other factors except coke quality are kept constant, are to be desired and

Jan 3, 1924

By Donald A. Dahlstrom

Stronger Than Armies This editorial by Dr. Dahlstrom is based on his acceptance speech of the 1976 Robert H. Richards Award-Ed. Many public figures are saying that the United States is facing the most critical period in its history, and many of us would agree. But people have always been saying this, and all of them were right. They were right two centuries ago when it took a revolution to give birth to the Republic; and they were right during our Civil War, Pearl Harbor, the Great Depression, etc.

Jan 6, 1976

By A. Tobey Yu

The recent adverse economic climate has added further impetus to the demand for better-grade and lower-cost raw materials, for which increasingly larger quantities of muck are being moved and processed at higher unit labor costs. As a result, the cost impact of handling and shipping has never been as keenly felt by the mining industry as it is today. Thanks to joint innovative efforts by users and manufacturers, new and improved automated bulk-handling systems and devices are now blossoming everywhere to give the mining man the tools he needs to move ore, waste and concentrates more efficiently and economically.

Jan 1, 1970

By N. A. D. Parlee, E. M. Sacris

OXYGEN solubility in liquid silver has been well studied.1-6 It has been established that the solubility follows Sieverts' law reasonably well5'6 up to po2

Jan 1, 1968

By Milton Ohring, Stephen M. Edelglass

THE recently determined coefficients for diffusion of very dilute impurities in aluminum are shown in Table I. Of these data the activation energies for Ag110, cu54, Mn54 and zn85 are clustered about the value of self-diffusion in aluminum; for the remaining

Jan 1, 1970

By L. E. Garner

Aggregate resources should be considered primary factors in urban development. Resource planning is essential because land values, previous construction, or zoning restrictions often preempt exploitation of aggregate deposits within an urban area. Sequential land use practices allow development of area prior to urban development population and aggregate consumption trends in Austin, TX, indicate that substantial quantities of reserves will be lost to future development. Aggregate materials are present in nearby areas. However, a comparison of transportation and reclamation costs indicates that reclaiming land after mineral extraction can be significantly cheaper than transporting materials longer distances.

Jan 1, 1982

By Hans Werner, Gunnar Almgren

An overview of the first Swedish Research mine at Mt Luossavaara, Kiruna, Sweden, is given, including its background, objective , program and expected results. The Research mine involves the spending of approximately US$ 32 Million over a five year period of which 30% are financed by the Swedish Government and remaining 70% by income from ore sales. The main objective will be to develop an underground mining system based on rock mechanical pre-investigations and blast hole stoping using big holes. The research program will include the following main components:

Jan 1, 1981

By Eugene Guccione

For at least 10 years, various industry people had warned about the alarming decline in the nation's oil and gas reserves. Then, in October 1973, the Organization of Petroleum Exporting Countries launched an oil embargo and sharply increased crude oil prices. Suddenly, everybody discovered the "energy crisis." In November 1973, former President Nixon advocated a Project Independence program so that ". . . by 1980 we shall be able to meet America's energy needs from America's own energy resources."

Jan 5, 1975

By A. C. Rand

The invention to be described in this paper is the work of Frederic A. Halsey, Engineer for the Rand Drill Company, of New York, and its use mill abridge the notable wastefulness of power of the striking rock-drill, and, at the same time, increase its capacity for work. That the older type of rock-drill is wasteful in power, is generally admitted; the cause being the use of steam* without expansion, arid the "cushion" of the blow, by the incoming steam upon the lower † end of the piston before the cutting tool strikes the rock.

Jan 1, 1885

By R. J. C. Tait

INTRODUCTION Process Control at the Ecstall Concentrator begins in the open pit at the Kidd Creek Mine. While this paper, naturally, emphasizes the instrumental and technical features of the Process Control system within the concentrator itself, it would not be complete without some mention of the selective mining methods and grade control practices at the mine, and of certain features of plant design, which are simple, but highly effective, elements of the Process Control system. The success of the entire Process Control system, from pit to concentrate load-out, owes much to the high degree of cooperation and mutual understanding among all the operating departments at Ecstall Mining Limited and to the willingness of management to accept, from the start, an overall control philosophy based upon the inter-dependence of mining and metallurgical operations. INFLUENCES OF MINERALOGY AND METALLURGY ON MINE PLANNING AND PLANT DESIGN Mineralogically, the Kidd Creek ores are fine grained and mostly very complex. Because of complex mineral associations and extensive inter-locking, very fine grinding and regrinding of middling fractions are necessary and selective flotation requires a very delicate touch. Four separate concentrates are made for shipment to copper, lead and zinc smelters. The Process Control system is tailored to the metallurgical objectives of maximum recoveries of copper, lead, zinc and silver into concentrates of optimum quality, for maximum economic returns. For example, zinc and lead in copper con-

Jan 1, 1970

The volumes of Transactions, which are published annually, contain the list of officers, rules, etc., the Proceedings, and the papers revised for final publication. (In this revision, after the preliminary publication, authors are permitted to use the largest liberty; and the changes and additions made in papers are sometimes important. It should be borne in mind by those who study or quote a paper in the preliminary edition, that they may not have in that form the ultimate and deliberate expression of the author's views. It should be added, however, that in the majority of cases there are no important changes.) These volumes are for sale as follows, in paper covers:

Jan 1, 1910

What do you think are the major problems that the mining industry is facing? While I don't have any intensive knowledge of the various problems that plague our industry, I know that they are all part and parcel of a more complex and fundamental question: What must we do to make mineral extraction successful, safe, and profitable? Obviously, as mining people, we must continue to expand our technical know-how and to make better use of it. In today's context, however, that is not enough. We must also improve the "public image" of the mining industry. Why? Because the key word in the term "public image" is: the public. Many people in our country and in Congress, for instance, are against strip mining-and some are even against underground mining. Pressures from the public, from voters, have affected past, present, and new legislation. And government controls can be a major problem in any industry, let alone mining. At first, people ask government to intervene, act, or resolve problems, even in management and labor contract negotiations. But later, after Washington gets involved, there are clashes between departments and personalities, and eventually there is resentment against the interference with mining operations or our daily lives.

Jan 3, 1975