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By Alan D. Smith

Mine roof fall characteristics of 250 falls in 5 different room-and-pillar coal mines, located in Pike, Martin, and Floyd counties, were investigated to determine the relationship of selected parameters associated with roof failure and the assumed condition of the mine roof before failure. The selected parameters used in the study included: presence of cracks and water before the occurrence of fall, sloughing of coal ribs, floor heave condition, type of roof support (resin or mechanical anchor bolts), distance to coal face, and time of occurrence of fall after initial coal extraction. In addition, research hypotheses, utilizing multiple linear regression techniques, were generated to test the relationship among the selected parameters and mine roof condition. The results indicated that the vast majority of falls portrayed some presence of water before the actual fall, occurred in less than 30 weeks after initial coal excavation, located usually greater than 30 meters from nearest coal face, gave evidence of cracks in mine roof before occurrence of fall, generally portrayed a good roof condition before the fall, showed presence of sloughing of coal ribs, and gave no occurrence of floor heave before occurrence of fall. In terms of the characteristics of the original support systems in the mine roof falls studied, most roofs were either supported by mechanical-anchor bolts or resin or full-column bolts; very rarely did the roof appear to fail if supported by posts or cribs. A detail inspection of the hypothesis and model comparison results gave supporting evidence that the condition of the roof is not dependent on the usual indicators of potential failure, such as presence of cracks and moisture. In fact, in most cases of mine roof failure, the immediate roof condition was rated as good or better, which gives little or no indication of pending failure and collapse. Hence, a combination of factors that are not easily accessible to measurement, are the dominant factors in the determination of roof fall-potential areas.

Jan 1, 1984

By Fred Beasley

METALLURGISTS have, in the past ten years, overcome many difficulties of high zinc in lead blast-furnace slags. This problem was brought to the front at the close of the late war, by the price obtained for lead and the high cost of labor, fuel, and flux. The Port Pirie plant of the Broken Hill Associated Smelters, Australia, early in 1919 had increased the zinc oxide in its blast-furnace slags from 13.5 to 20 per cent., at the same time reducing the iron oxide in the slag from 33.5 to 25.6 per cent. These results were obtained by the following proceduret the addition of granulated slag to the roaster charge, 10 to 12 per cent., improved conditions of the crushing and mixing and roasting of the constituents of the sinter. By experiments and improve-ments the practice at this plant has developed a normal slag that carries 22 per cent. zinc oxide, and at times runs as high as 33 per cent. zinc oxide, with only slight furnace trouble. The granulated slag is used not, only as a diluent to the sulfur in the roaster charge, but also on account of its value as a slag-forming material and on account of the physical properties it imparts to the finished sinter. The ore is mixed with flux and given a double roast. All the first roasting is by sintering with the Dwight & Lloyd machines. The final roasting is performed partly by Dwight & Lloyd machines and partly by H. & H. pots. The charge to the blast furnaces consists chiefly of the final sinter, slag shells, siliceous and non-bearing sulfur, lead ores. High blast and ore columns are the practice. The greatest care is taken to obtain in the final sinter as low a sulfur content as possible.

Jan 2, 1925

By A. L. Holley

THE intention of this paper is not to discuss this important subject in all its bearings, but merely to point out why mechanical tests of steel, as ordinarily made, are not, alone, of any special value to engineers-certainly not to general mechanical engineers. The agents of the Barrow Hematite Steel Company, one of the largest and most successful Bessemer establishments in England, have recently distributed a report, made by Sir William Fairbairn,

Jan 1, 1874

POSITIONS VACANT (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) Superintendent for iron mine operated on the sub-level and caving system. Small output, moderate salary. Location, Southern State. No. 45. Chemist to sample and analyze iron ore. Experience in other branches not essential. Location, Southern State. No. 46. ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introducd by members.) Experienced mine superintendent desires position. Several years' experience in practical management of mining and development work. Has also practiced ass consulting engineer and is thoroughly experienced in the examination and development of mining properties. Mexican experience. Will go anywhere for reliable concern. Salary moderate. References. No. 254. Member, mechanical superintendent, wants position. Has had 12 years' experience as master mechanic of smelting plants in United States and Mexico. Also superintendent of shops doing marine, mining, and general contracting work. . Experienced in manufacture of mining tools and equipment. Up to the minute in copper, lead, and zinc smelting. Has learned a learned a great deal, can forget much, and has the inclination and ability to learn more. Best of references. No. 255.

Jan 10, 1915

By William R. Taylor

This paper reviews the mining and related legislation history of in situ uranium mining in southwest Texas with emphasis on the last five years. It also reviews the current regulatory process and some of the more critical concerns and concepts relative to containment and restoration of in situ mines.

Jan 1, 1979

MARCEL R. DALY (written discussion+).-I have read with great interest Mr. W . Van Der Gracht's discussion of my paper and I fail to see where his theory contradicts mine on any fundamental point. My contention is that petroliferous accumulations are generally coincident with diastrophic deformations, synchronous with them and essentially a result of them. This implies that the causes which have led to the distortion of the strata, whatever these causes may be (thrusts, torsion, etc.), have also led to the concentration and accumulation of the hydrocarbons existing in the strata at that time. It is in this respect that both set of phenomena may be said to be related in space and in time and that we may speak of an identity of causes. It is evident that no concentration of the hydrocarbons could take place where these hydrocarbons would not exist. But whenever they do so exist, deformation will tend to concentrate them; and whenever they are found to be concentrated (or accumulated) the cause of their accumulation will have to be traced directly to distortion. I have tried to show, in some previous papers,' the probable sequence of such a mechanical process in the simple case of a series of parallel, superposed, horizontal and homogeneous layers, individually uniform in thickness, but variable in composition and resistance; and I have pointed out that the general results so obtained would harmonize with some striking features recognized in the field. But I have also stated that conditions being much more complicated in nature than in the theoretical instance considered above, a complex superposition of effects would. have to be expected as a general rule, though the leading principle would remain the same. Mr. Van der Gracht admits that the motion of the primary oil, when it has been formed, and its accumulation in adequately porous containers, if any, that would be mostly found on the front edge of the original geosynclines, would be due to the action of the mountain-building forces. Our agreement on this point seems to be complete. But Mr. Van der Gracht wants also the formation of the bituminous matter in its primary form to be coincident only with the earliest phase of the uplift, viz., after the slow geanticlinal upheaval has been completed, and the accumulation

Jan 3, 1918

Jan 1, 1923

Jan 1, 1923

By J. S. Ll. Leach, J. B. Cohen, M. B. Bever

IN the work reported here, the heats of formation of a copper-rich Cu-Sn (a) solid solution and of the Cu.Sn (0 phase were measured by tin solution calorimetry. An approximate determination of the heat effect attending the precipitation of 6 from a supersaturated a solid solution was also made.

Jan 1, 1955

The Keweenaw Peninsula in the Upper Peninsula of Michigan is plagued with abandoned prospectors' test pits and mine shafts, the result of exploration and operation of mines for over 100 years. The Fort Wilkins State Park in Keweenaw County alone has three open prospectors' pits within its boundaries, protected by wooden fences and maintained by the (Michigan State Conservation Department as a tourist attraction.

Jan 1, 1967

By Martin F. Milligan

THIS short discussion of the effects of deoxidation on the mechanical properties of cast steels is intended to serve as general introduction to the subject of this afternoon's session. The subject is covered in detail in Mr. Carter's excellent paper. My material has been collected from the works of various investigators, several of whom are present today. For a definition of deoxidation, as applied to steel-furnace melting practice, we can best go to Briggs' book, "The Metallurgy of Steel Castings." Briggs says that deoxidation "includes all the phenomena in the final preparation of steel that would permit it to solidify free from gas cavities and from dissolved oxygen of all kinds." Various practices are used by welters to produce these end results.

Jan 1, 1947

By Burt C. Mariacher

Two AIME sponsored symposia to be held during the year 1970 will examine copper, lead and zinc metallurgy in considerable depth. MBD and the Extractive Metallurgy Division of The Metallurgical Society will participate in both. Thus, the full field of minerals and metals processing including milling, smelting, and refining will be covered. Since these symposia hold special interest to MBD members, it was felt that a useful purpose could be served by devoting this column to a description of what has been arranged for the registrants.

Jan 1, 1970

THE opening session was held on Tuesday evening, October 23d. Mr. J. F. Lewis, on behalf of the local committee of arrangements, made a short address of greeting to the members assembled, and then introduced Gov. A. H. Holley, of Lakeville, Conn. Gov. Holley addressed the Institute as follows : Gentlemen, we give you cordial welcome to a mining, manufacturing, and agricultural country, of which we are not a little proud. We welcome you as an association, and as individuals. We invite you to an inspection of our resources, and to our methods of improving them. We appreciate the results of your efforts in past years, and we anticipate good from your advice and counsel in the future. You are in the vicinity of some of the oldest mining and manufacturing operations in iron in our country. It will be our pleasure to conduct you to a mine which was worked for more than a half century before our country achieved national independence, and to point out to you the spot where the products of this mine were wrought into cannon and shot during the progress of our Revolution. We can show you also a far larger area of mining country than was supposed to exist in this vicinity at that early day. There are, within a radius of thirty miles from this spot, ten mines at least that have been extensively worked, and there are as many more that have been occasionally worked, with a fair degree of success. All the mines that are wrought to any extent produce excellent qualities of iron, while many of them in various combinations produce as good material for the manufacture of steel, car wheels, axles, and many other purposes, as can be found in any country. The old Salisbury iron retains its reputation for tensile strength unsurpassed, when made entirely from the ore of the old mine. The progress that has been made in the development of these mines since the days of the pickaxe, when the product was transported in pounds upon horseback, to those of the steam-engine, which now moves hundreds of tons per day, presents, indeed, a

Jan 1, 1878

The opening session was held on Tuesday evening, October 23d. Mr. J. F. Lewis, on behalf of the local committee of arrange ments, made a short address of greeting to the members assembled, and then introduced Gov. A. H. Holley, of Lakeville, Conn. Gov. Holley addressed the Institute as follows: Gentlemen, we give you cordial welcome to a mining, manufac turing, and agricultural country, of which we are not a little proud. We welcome you as an association, and as individuals. We invite you to an inspection of our resources, and to our methods of im proving them. We appreciate the results of your efforts in past years, and we anticipate good from your advice and counsel in the future. You are in the vicinity of some of the oldest mining and manufacturing operations in iron in our country. It will be our pleasure to conduct you to a mine which was worked for more than a half century before our country achieved national inde pendence, and to point out to you the spot where the products of this mine were wrought into cannon and shot during the progress of our Revolution. We can show you also a far larger area of mining country than was supposed to exist in this vicinity at that early day. There are, within a radius of thirty miles from this spot, ten mines at least that have been extensively worked, and there are as many more that have been occasionally worked, with a fair degree of success. All the mines that are wrought to any extent produce excellent qualities of iron, while many of them in various combinations produce as good material for the manufacture of steel, car wheels, axles, and many other purposes, as can be found in ally country. The old Salisbury iron retains its reputation for tensile strength unsurpassed, when made entirely from the ore of the old mine. The progress that has been made in the development of these mines since the days of the pickaxe, when the product was trans ported in pounds upon horseback, to those of the steam-engine, which now moves hundreds of tons per day, presents, indeed, a

Jan 1, 1879

By Ingersoll Olmsted

These ores are of two classes, Bessemer and non-Bessemer, existing in separate, though adjoining, beds. Both are carbonates, with small admixtures of oxides and other combinations. To prepare them for market they are roasted in kilns, which have already been described by Mr. John Birkinbine at the Troy Meeting, October, 1883 (Trans., xii., 378). Concerning their size, arrangement, etc., I need, therefore, only repeat that they are 60 feet in height; have wrought-iron shells 24 feet in diameter; are lined with fire-brick, and supported by cast-iron mantel and columns.

Jan 1, 1889

By Robert H. Richards

It will hardly be worth while to spend time over the discovery of this mine, how lumps of galena were picked up and brought to town, and how legends were told of an old mine from which Revolutionary bullets were made. This is an entirely new mine, with no evidences of former or ancient workings in its immediate vicinity to guide or attract the prospector. The first pit was opened in May, 1874. In August I made a visit to this pit, which was 6 feet wide in the northwest direction, 12 feet long north 80° east, and 6 feet deep..About 4 tons of a galena carrying gray copper, siderite, and quartz, had been taken from this pit. The lumps were all of them evidently float specimens, and varied from 8 to 12 inches thick, and showed very distinct indica-

By C. Coles, J. A. I. Young, W. A. Wyeth, D. A. Fenton, G. W. Herzog

The reliability of large diameter, high horsepower ball mills is paramount when large production and minimum downtime is required. The 518 x 1706 mm (17 x 56 ft) double compartment ball mill at St. Lawrence Cement Co. has the fist gearless drive built in North America and has the world's largest hydrodynamic bearings currently built and running. The machine has seen three years operation and has met its specifications. The mill wm designed by Aerofall Mills Ltd. and the gearless drive built and designed by the Canadian General Electric Co. The paper discusses the operation of the machine from the mechanical, electrical and process aspects.

Jan 1, 1980

By L. M. Kaas

Maintenance costs comprise a large portion of total operating cost, 30% to 60% of the operating cost dollar not being unusual. Thus even a relatively small percentage reduction in this cost would represent a sizable increase to mining profitability. Mine and mill maintenance management is a complex problem. An effective maintenance manager must study the experiences of the past and make decisions based on that experience. Data Processing equipment-more specifically, the computer-can be an effective and economical tool to simplify the job of maintenance record-keeping and to aid in the formulation of many accurate and timely management reports. These reports will enable improved control to be established over day-to-day practices; permit comparisons of unit and component performance; spotlight inefficient maintenance practices; and further, better, more efficient cost control. The net result can be increased profits through reduction of operating costs.

Jan 12, 1967

By J. C. Norman

Jan 1, 1985

ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, technical graduate, five years' experience as mining engineer and chemist. Actual experience in underground work, surveying, mapping, foreman, etc. Will accept very moderate salary to start with reliable company. Willing to go anywhere. No. 184. Member, technical graduate, with experience as engineer and metallurgist for various copper companies, is open for similar positions. No. 185. Member, specializing in cyanide treatment and cyanide plant construction, with 10 years' experience in Mexico and in the West, desires position. No. 186. Member, technical graduate, first in mining engineering and then in chemistry and metallurgy, Lafayette College; Fellow, School of Mines, Columbia University; special work Royal School of Mines, Freiberg, Saxony, Germany; ten years' experience teaching mining, chemistry, assaying, and metallurgy, desires position as Director of School of Mines or Professor of Metallurgy. No. 187.

Jan 2, 1915