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By James R. Russell

Rock bolts are commonly used to support and stabilize the rock around excavated openings. The assumption is made that the less competent rock near the surface can be supported by bolting it to more competent rock away from the surface. Naturally, a rock bolt can be no more effective than its anchoring mechanism which induces a stress field into the surrounding rock. Details of various types of bolts have been described e1sewhere.l The purpose of the present investigation is to study the stress distribution around an expansion-type rock bolt anchor, using the theory of elasticity. The elastic stress distribution provides some insight into the behavior of rock bolt anchors which may eventually lead to improved designs. Very little information is available on the induced stress field which is rather complex; consequently, photoelastic techniques have been used to obtain a qualitative picture of the stress ditribution.2 The present work provides quantitative information on the stress field induced by an idealized distribution of surface tractions, provided that the assumptions of the linear theory of elasticity are approximately satisfied. FORMULATION OF THE PROBLEM Consider an elastic region which extends to infinity and contains a circular cylindrical hole as shown in Fig. 1. The hole is assumed to be the bolt hole and the surface tractions shown are assumed to be caused by an idealized rock bolt anchor. The relationship between the idealized

Jan 1, 1972

By Arch J. Alexander

This paper is a resume of a study undertaken by the West Virginia Department of Mines. The underlying and direct causes of accidents are determined in each occupational group. Then from this study, accident prevention courses, visual and written, are to be taken to the various working groups in the mines. THE causes of accidents in West Virginia mines follow the main pattern of coal industry accidents in the United States—falls of roof, ribs and face, 56 pct; from haulage, 25 to 30 pet; blasting, 3 pet; electrocutions, 3 pct; explosions, 2 pct; and other causes, about 10 pct. To arrive at some satisfactory conclusions regarding causes and prevention of mine accidents, the Department of Mines has made a study of all mine accidents, from 1945 to 1948, inclusive. During the last two years of this period, we did not have a major explosion, one that took the lives of as many as five men. The direct cause of these accidents is apparent in the reports but we who are making a close study into their frequency think that the virus lies much deeper, and we want to suggest an underlying cause. The rapid growth of the coal industry in West Virginia, the largest producer of bituminous coal, has resulted in a demand for manpower which probably has never been equaled in mining history. At the turn of the century, West Virginia had 24,635 men employed in and about her mines, and they produced 21,153,341 tons of coal a year. In 1948, there were 125,669 men employed, and coal production for the year was 168,589,033 tons, an average increase of 35 pct for each year since 1900. Over 100,000,000 tons of this increase were mined in the southern counties of the state. A safety analyst might read into the history of this development an underlying cause for accident occurrence. He might say that in such a vast, rapid development the available supply of trained miners became exhausted and that young, inexperienced men were employed in the mines by the thousands. Being unacquainted with the hazards of mining, it would be only natural for these young men to be injured or killed in too great a number. This assumption would not be borne out by the records. Men were not injured or killed in disproportionate numbers during their first years in a mine. The only reason we can give is that, during these years, they possessed an attribute of safety—CAUTION—to a much greater degree than in the years following. The coal companies in West Virginia that have been operating over a number of years have a nucleus of employees who have been with them ten, twenty, thirty, and forty years; many of them having gained all of their mining experience with one company. Their habits of work have been

Jan 1, 1951

By Arch J. Alexander

This paper is a resume of a study undertaken by the West Virginia Department of Mines. The underlying and direct causes of accidents are determined in each occupational group. Then from this study, accident prevention courses, visual and written, are to be taken to the various working groups in the mines. THE causes of accidents in West Virginia mines follow the main pattern of coal industry accidents in the United States—falls of roof, ribs and face, 56 pct; from haulage, 25 to 30 pet; blasting, 3 pet; electrocutions, 3 pct; explosions, 2 pct; and other causes, about 10 pct. To arrive at some satisfactory conclusions regarding causes and prevention of mine accidents, the Department of Mines has made a study of all mine accidents, from 1945 to 1948, inclusive. During the last two years of this period, we did not have a major explosion, one that took the lives of as many as five men. The direct cause of these accidents is apparent in the reports but we who are making a close study into their frequency think that the virus lies much deeper, and we want to suggest an underlying cause. The rapid growth of the coal industry in West Virginia, the largest producer of bituminous coal, has resulted in a demand for manpower which probably has never been equaled in mining history. At the turn of the century, West Virginia had 24,635 men employed in and about her mines, and they produced 21,153,341 tons of coal a year. In 1948, there were 125,669 men employed, and coal production for the year was 168,589,033 tons, an average increase of 35 pct for each year since 1900. Over 100,000,000 tons of this increase were mined in the southern counties of the state. A safety analyst might read into the history of this development an underlying cause for accident occurrence. He might say that in such a vast, rapid development the available supply of trained miners became exhausted and that young, inexperienced men were employed in the mines by the thousands. Being unacquainted with the hazards of mining, it would be only natural for these young men to be injured or killed in too great a number. This assumption would not be borne out by the records. Men were not injured or killed in disproportionate numbers during their first years in a mine. The only reason we can give is that, during these years, they possessed an attribute of safety—CAUTION—to a much greater degree than in the years following. The coal companies in West Virginia that have been operating over a number of years have a nucleus of employees who have been with them ten, twenty, thirty, and forty years; many of them having gained all of their mining experience with one company. Their habits of work have been

Jan 1, 1951

By T&apos Ke, ing-sui

THE subject of recrystallization and grain growth has been much studied and the literature on this subject is numerous. Such studies have been mostly carried out by metallographic examination of X ray methods. Since recrystallization and grain growth involve elementary atomic processes, their mechanism can best be elucidated by a study of some properties which can be readily traced back in terms of such atomic processes. Prior to a detailed quantitative study, however, it is necessary to explore first the possibility and practicability of utilizing any particular property for obtaining the desired information. We have pointed out in a preceding article' that the internal friction of cold-worked metals is extremely high during recrystallization and it drops abru~tlv once the recrystallization is complete. ~reviois work has also shown that the viscosity of grain boundaries in a recrystallized specimen at a given temperature is raised by grain growth.' It seems thus that the measurements of internal friction may furnish a useful tool for the study of the mechanism of recrystallization and grain growth in terms of elementary atomic processes. The purpose of this paper is to report results of a study along this line. We will demonstrate that the internal friction method does give results in agreement with those furnished by conventional metallographic examinations. Once such a correlation has been established, we will be in a position to take further steps to achieve new information which cannot be achieved by conventional methods. The measurements of internal friction were made using apparatus and procedures similar to those used in the preceding article. All the measurements were made under such a small stress level that the internal friction is independent of stress level. The frequency of vibration is, unless mentioned otherwise, about one cycle per second in all cases. Internal Friction and Recrystallization Complete Recrystallization Temperature: Fig. 1 shows the internal friction curve during annealing of a few metals: aluminum, alpha brass and iron. These curves were determined in the following manner. In the curve for aluminum, internal friction measurements were performed upon. 99.991 aluminum subjected to 95 pct reduction area. The internal friction was first measured at room temperature. The specimen was then annealed at 50°C

Jan 1, 1951

By Russell S. Sage

THE electric motor has steadily replaced the steam and air engine for use in mine hoists, until today a new installation with other than electric drive is a rarity. Much existing steam-driven equipment has been changed over to electric drive. Driving power has grown in capacity since the initial electric unit rated 10 hp installed at Aspen, Colorado, in 1888, to 3000 hp and 4000 hp in the United States, and to 5500 hp in Canada-the largest in the Western Hemisphere. Electric installations now total in the thousands of units, a growth largely made possible by the development of large central electric-power stations and the extension of electric-power service to more mining areas.

Jan 1, 1949

Jan 1, 1946

By H. Engelmann

THE very extensive development of a brown coal formation, in the region of the Rocky Mountains, is well known to all of you. The existence of these coals was known years ago, but they were of no practical importance until within a few years, when the mineral wealth of that country began to be developed and railroads were built. As their qualities became better known, their adaptability to domestic manufacturing and metallurgical purposes was more appreciated. They are still much undervalued, although they are mined at some points on a very extensive scale. A large portion of this coal formation is of cretaceous age, while it appears to extend into the tertiary epoch; but whatever difference there may be in the ages of these coals of different localities, they all have some common characteristics which distinguish them from our Eastern stone coals of the

Jan 1, 1876

By H. Engelmann

The very extensive development of a brown coal formation, in the region of the Rocky Mountains, is well known to all of yon. The existence of these coals was known years ago, but they were of no practical importance until within a few years, when the mineral wealth of that country began to be developed and railroads were built. As their qualities became better known, their adaptability to domestic manufacturing and metallurgical purposes was more appreciated. They are still much undervalued, although they are mined at some points on a very extensive scale. A large portion of this coal formation is of cretaceous age, while it appears to extend into the tertiary epoch; but whatever difference there may be in the ages of these coals of different localities, they all have some common characteristics which distinguish them from our Eastern stone coals of the

By AIME AIME

LIFE will not be difficult for those who attend the fall meeting of the Petroleum Division at the Conoco Club, Ponca City, Okla., Sept. 30-Oct. 1. An attractive program to appeal to oil company executives and lawyers, as well as technologists, has been arranged and the Continental Oil Co. has contributed for the occasion the buildings, grounds and facilities of the club. E. 0. Bennett, Continental Oil Co., Ponca City, is chairman of the arrangements committee, and reservations for rooms and trips, requests for information, etc., should be sent to him.

Jan 1, 1932

AN extremely successful meeting, under the joint auspices of the Ohio Section and the Iron and Steel Committee, was held at Cleveland on April 19 and 20, about one-half of those in attendance being from the Cleveland district and the other half from a distance. The morning session on April 19, C. K. Leith presiding, was opened by the presentation of the ad-dress of which an excerpt is printed on the opposite page. In the subsequent discussion R. A. Allen pointed out that the meeting had not been called "to blow the lid off the tariff" since that is only one of the many problems connected with the wisest utilization of man-ganese, and it was the purpose of this meeting to con-sider all those interdependent problems. The purpose of the tariff was to develop an adequate domestic sup-ply, and that result had not been accomplished. An-other important problem, linked with the tariff, is the need for assuring, while we are at peace, an adequate war supply of manganese, and at present this country has no such policy. D. F. Hewett said that his 3-months' trip in Europe last summer had impressed him with the fact that England had once been in the position United States now is in, of being the principal world's producer of all the more important minerals and with a declining reserve had gone on a free-trade basis. No one pointed out that, with the exception of tin, the present relative position of England is due more to an increase in pro-duction in other countries, rather than to a decrease of domestic production. J. Sharshall Grasty referred to recent development work-in Virginia where of 30 per cent easily concen-trated manganese ore about 300,000 tons has been blocked out and possible and probable ore amounting to 700,000 tons more is indicated.

Jan 5, 1927

By Kefton H. Teague

Attempts to locate domestic supplies of sillimanite have been un- successful until recently. This paper describes recent discoveries of sillimanite-bearing schists in the Southeastern States, with emphasis on geology of the deposits, mineral composition, origin, and reserves. Statements concerning possible methods of mining, milling, and utilization of sillimanite are given. Results from refractory tests on a laboratory scale are summarized.

Jan 7, 1950

Jan 1, 1944

HARRY B. BARREN Harry B. Barren, born in Cleveland, Ohio, May 31, 1888, died in Indiana Harbor, Ind., on Mar. 18, 1918. After graduating from the Case School of. Applied Science of Cleveland, class of 1910, he spent a year at the Youngstown, Ohio, plant of the Carnegie Steel Co. and the following two years with the National Tube Co. in Lorraine, Ohio. In 1913, he went to Indiana Harbor as assistant superintendent of the blast furnaces of the Inland Steel Co. Four months later, he was made superintendent. On Feb. 11, 1914, he was married to Miss Anna E. Jones in Cleveland and is survived by his widow and two sons, and by his parents Mr. and Mrs. H. A. Barren, of Cleveland, and a brother Kenneth, a lieutenant in the 309th Engineers, stationed at Camp Taylor, Louisville, Ky. CHAS. H. JOHNSON Charles Harmany Johnson died Dec. 10, 1918, at his home in New Castle, Pa., after an illness of more than four weeks brought about by a complete nervous collapse. He was born near Clinton, Lawrence Co. Pa., July 9, 1870, a son of George W. and Elizabeth A. Johnson. His parents moved to New Castle when he was two years old, where he attended the public schools of New Castle. He then attended Allegheny College, and later Massachusetts Institute of Technology where he graduated as a mining engineer. For a year and a half after completing his work at Boston he was connected with the Mesaba Ore Range in Minnesota, and then returned to New Castle and became associated with his father in the operation of the old sheet mill, which was converted into a tin mill and later sold to the American Sheet and Tin Plate Co. Since that time he has been actively engaged with his father in the limestone business and other industries. At the time of his death Mr. Johnson was general manager of the Pittsburg Limestone Co., the G. W. Johnson Limestone Co., the Lawrence Limestone Co., the Keystone Limestone Co., and the Mahoning Limestone Co., all of which have quarries in Lawrence, Butler, Blair and Armstrong counties and also in Maryland and West Virginia. He was president of the Johnson Bronze Co., the National Stone Co., and the

Jan 3, 1919

By Edward Sayre

IN shaft sinking for coal mines, the cost item greatly influences the method adopted. This holds true especially when soft material must be traversed. The average life of a coal mine is short. This is clue either to the limited area of the coal basin or to the great expense of maintenance and haulage underground when the entries are extended a considerable distance from the hoisting shaft. Therefore, the engineer in opening a coal mine is confronted with the fact that the cost must be kept within certain bounds else the venture will prove unprofitable. For this reason he may be prohibited from adopting certain safe, but expensive, methods that are used in sinking caissons for foundations, driving transportation tunnels, or other work of permanent construction. A common method of sinking through difficult ground employs the aid of a steel shoe pushed ahead of the shaft timbers. Another is the drop-shaft method. These two methods were used in sinking the main shaft and the air shaft of the Eagle No. 3 mine, at Des Moines, Ia., and the following data show the relative success and cost of the two methods of sinking under the same conditions. A drill log of the material to be penetrated was as follows (see Plate 1, Fig. .1)

Jan 9, 1916

By J. B. Hiskey

Heap leaching has in recent years been established as an important processing alternative for gold and silver. Currently, heap leaching accounts for about 25% of primary mine produced gold and 10% of primary silver. This paper reviews gold and silver heap leaching practice and surveys major operations in the United States.

Jan 1, 1984

By J. C. Savins, G. C. Wallick, W. R. Foster

The dual differentiation-integration method of rbeological analysis is applied to Couette flow. Using machine processing techniques, a spectrum of characteristic derivative functions for a variety of ideal Generalized Newtonian and viscoplastic models has been developed; As for the case of Poiseuille flow the functions for Generalized Newtonian models as a class are strikingly different from the corresponding functions for the class of viscoplastic models. It is shown that this dual scheme of analysis is a highly sensitive analytic method for dotermining the applicable range if a rbeoloaical model. The unique characteristics of this function in the case of viscoplastics may lead to a more precise detection and evaluation of the yield point or yield stress in these materials. INTRODUCTION It has been shown 1,2 that the dual differentiation-integration method of analysis is a discriminating and flexible method for interpreting flow behavior and determining the applicable range of a particular model from Poiseuille flow experiments. In the preceding paper3 the basic equations governing the Couette flow experiment were reviewed and the significance of changes in boundary conditions on data analysis in the case of the viscoplaaic discussed. In this paper the dual method of analysis is applied to Couette flow using the suites of rheological models considered previously.

By W. L. Freyberger

In a study of the kinetics of flotation of coal, employing a single-cell continuous flotation system, Jowett and Safvi1 pointed out that it was experimentally impossible to float all of the coal which could be floated in a batch tests. On the other hand, deBruyn and Modi, in a discussion of their paper, suggested that under certain conditions the recovery of floatable material from a similar one-cell continuous system would have been 100%.2 Both of these pairs of authors make the assumption that a state of perfect mixing exist in the flotation cell. This assumption, usually made by investigators studying flotation kinetics in a continuous system, has been confirmed experimentally on several occasions. The work is summarized by Arbiter and Harris.3 It is the purpose of this note to demonstrate that, for conditions of perfect mixing, one of two conditions exist: 1) the recovery of floatable material is 100%, and the flotation is infinitely fast, or 2) the recovery of floatable material must be less than 100%. This theorem can be proved simply in the following manner: 1) If recovery, R, of the floatable material is 100%, the concentration in the tailing must be zero. This follows from the definition of recovery as

Jan 1, 1964

By J. R. Thoenek S. L. Windes

The amplitudes and frequencies of vibratiolls of a four-story stucco building were measured by specially developed electrocapacitive seismometers. Records were made on three floor levels with as many as 10 seismometers recording simultancously. Sources of vibration were: (1) an electric motor with unbalanced pulley, maximum speed 1800 r.p.m., maximum centrifugal force 90 lb., (2) truck traffic (both solid and pneumatic tires) moving over inequalities in the street in front of the house, (3) falling weights dropped on the street pavement from different heights, (4) miscellaneous sources, including a man jumping on the floor of the house and slamming doors. Tests were made to determine the natural frequencies of floor and wall panels by varying the speed of the unbalanced motor and by exciting the panels with a single impulse. The vibrations recorded were compared to records of vibrations from quarry blasts and it was observed that the vibrations from truck traffic were comparable to those recorded from quarry blasts and in no instance was there any damage to the building. As the tests were all of a negative character as far as damage was concerned, no index of destruction is formulated. Instead, the records are presented simply as vibration measurements obtained in an ordinary house under typical conditions.

Jan 1, 1940

By J. R. Thoenek S. L. Windes

The amplitudes and frequencies of vibratiolls of a four-story stucco building were measured by specially developed electrocapacitive seismometers. Records were made on three floor levels with as many as 10 seismometers recording simultancously. Sources of vibration were: (1) an electric motor with unbalanced pulley, maximum speed 1800 r.p.m., maximum centrifugal force 90 lb., (2) truck traffic (both solid and pneumatic tires) moving over inequalities in the street in front of the house, (3) falling weights dropped on the street pavement from different heights, (4) miscellaneous sources, including a man jumping on the floor of the house and slamming doors. Tests were made to determine the natural frequencies of floor and wall panels by varying the speed of the unbalanced motor and by exciting the panels with a single impulse. The vibrations recorded were compared to records of vibrations from quarry blasts and it was observed that the vibrations from truck traffic were comparable to those recorded from quarry blasts and in no instance was there any damage to the building. As the tests were all of a negative character as far as damage was concerned, no index of destruction is formulated. Instead, the records are presented simply as vibration measurements obtained in an ordinary house under typical conditions.

Jan 1, 1940

By Thomas Watson

Introduction THE occurrence of zircon in pegmatites of acidic composition is recorded by many observers both in this country and abroad, and they form one of the most important geologic modes of occurrence of the mineral.' As is well known, commercially the most important American locality for zircon is near Zirconia in Henderson County, North Carolina, where many tons of the mineral have been obtained from a kaolinized pegmatite dike 100 ft. wide and traced for 1 ½ miles along the direction of strike N. 50° E. Zircon may be developed in pegmatites as inclusions in the principal rock-forming minerals, chiefly quartz and feldspar, and as a separate megascopic constituent in the form of grains and crystals not exceeding, as a rule, 2 in. in size, and usually smaller. In the Henderson County, North Carolina, pegmatite, zircon occurs in prismatic crystals with pyramidal terminations measuring up to 30 mm. in diameter, associated chiefly with the feldspar. In some of the apatite veins of Canada, which are closely allied to pegmatite dikes, zircon is reported in crystals upward of 6 in. in length and 2 in. 'and more in thickness. Zircon in large masses occurs in Virginia in the well-known pegmatites near Amelia in Amelia County, and near Gouldin in Hanover County. Both localities are in the middle eastern portion of the Piedmont Plateau province, and are separated by a distance of about 40 miles in a northeast-southwest direction. The rocks of both areas, including the pegmatite bodies, are in an advanced stage of decay, and, the hard and moderately fresh rocks are concealed beneath a cover of variable thickness of rock decay derived by the normal processes of weathering. Exposures, there-

Jan 7, 1916