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By D. E. Norquist, J. E. Moeller

The results of wear on marked balls, 4, 31/2, 3, and 2 in. diam are given. All balls were forged steel of practically the same chemical analysis and hardness. The results indicate that balls in a given mill for a given length of time will have equal diameter losses, regardless of size. IN order to determine the relative wear rates of several sizes of grinding balls, groups of 4, 31/2, 3, and 2 in. balls were marked individually and were charged, all at the same time, into each of two production mills grinding copper ore. The remainder, and vast majority, of the ball charge consisted of 2 in. diam, and smaller, white, cast iron balls. The original weight of each test ball was determined and recorded. Some of each group of test balls were recovered from the mills periodically, individually reidentified, and reweighed. The test balls were recovered during regular maintenance shutdowns, at approximately thirty-day intervals, so as to avoid disrupting operations. As soon as the weights had been recorded, each marked ball was recharged into the mill from which it had been taken. The test units were mechanically the same and theoretically received equal tonnages of feed. All of the test balls were of forged, alloy steel composition with only slight variations in chemistry that would not be expected to affect the physical properties. All were heat treated in the same manner to produce a high hardness, as equal as possible for all sizes and as uniform as possible from surface to center. Generally speaking, the hardness of the portion worn from the balls during the test ranged from 62 to 65 Rockwell C. The microstructure was, therefore, predominately martensitic. The method of marking the test balls consisted of forming a small, round hole, 3/16 or 1/4 in. diam, into the center of each test ball with a Thomas Metal Master disintegrator, which produces a hole in fully hardened steel without affecting the hardness of the surrounding metal. After the hole was formed, each test ball was individually weighed to the nearest gram and the weight was recorded. The balls were grouped as to size and each group assigned a code letter. The individual balls within the various groups were then assigned a number. A small copper disc was stenciled on one side with the group letter and on the other side with the individual ball number and dropped into the hole in the corresponding test ball. The hole was then plugged with a low-melting-point metal alloy, which could be melted out in boiling water. Half of the test balls in each group were charged into one mill and the other half into another mill, so that all test balls in each mill would be subject to, as nearly as possible, identical conditions for an equal length of time. Previous testing had indicated that the wear rates on balls of different sizes could not be accurately compared if weight loss, or percentage weight loss, were used as a basis for comparison. Fig. 1 is a graphic record of the average weight loss for each size group in mill No. 1, and it becomes readily apparent that the larger balls lose substantially more weight in a given length of time. Fig. 2 is a graphic record of the average percentage weight loss for each size group in mill No. 1, illustrating that the smaller balls definitely lose a greater percentage of their original weight in a given length of time. It was, therefore, decided to convert the actual weights of the test balls to diameter and follow the diameter losses periodically to see if the wear rates

Jan 1, 1951

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 John L. Ryon

Experimentation with ammonium nitrate fuel oil mixtures at three under-ground salt mines revealed its excellent applications at those properties. The author relates the present blasting practice used at these mines by the International Salt Co.

Jan 4, 1961

By Edward Wisser

The environment of an ore body is taken to mean not only its physical surroundings but every factor, passive or active, that conditioned the ore shoot, saving only the original composition of the solutions that formed the shoot. Collection of data related to the shape and characteristics of veins should be followed by correlation of the data and the formulation of generalizations regarding ore formation. The nature of the criteria used in arriving at these generalizations is discussed. Certain of the criteria, when used with an understanding of their underlying causes, become "ore-guides." In the course of his study the geologist must not confine himself to the immediate surroundings of the veins, but should attempt to work out the geologic history of events culminating in the crucial epoch for any mining district, the period of mineralization. The work may involve study of features far removed from the veins and related to them only indirectly. It commonly means thorough study of the geology of the entire region surrounding the ore deposits. The following question has been suggested for discussion: "Are there any criteria by which one can determine when mining operations have reached the roots of an ore deposit?" The question deals less with the roots of a particular ore body than with the lower limit of the vertical range within which ore bodies may be expected. It concerns a critical line upon the longitudinal vertical projection of a vein.† Below this line it is useless to look for ore shoots; above the line exploration below the bottoms of individual ore shoots may be justified. Can we learn to determine the position of such a line? In some multivein districts the line for any given vein may be approximated by simple interpolation or extrapolation. Where this is possiblc the bottoms of the lowest ore shoots in the various veins are points on an imaginary, gently rolling surface. The trace of this surface upon the vein is our critical line for that vein. The imaginary surface rolls so gently that it may be projected from two or more known veins to an unexplored vein near by. Here is a criterion for the bottoming of ore that has nothing to do with changes in the appearance of the vein in question; it rests solely on the depth at which the ore bottomed in adjacent veins. The method is not applicable in districts only slightly explored in depth, nor where the lower limit of the ore-bearing horizons

Jan 1, 1941

By Edward Wisser

The environment of an ore body is taken to mean not only its physical surroundings but every factor, passive or active, that conditioned the ore shoot, saving only the original composition of the solutions that formed the shoot. Collection of data related to the shape and characteristics of veins should be followed by correlation of the data and the formulation of generalizations regarding ore formation. The nature of the criteria used in arriving at these generalizations is discussed. Certain of the criteria, when used with an understanding of their underlying causes, become "ore-guides." In the course of his study the geologist must not confine himself to the immediate surroundings of the veins, but should attempt to work out the geologic history of events culminating in the crucial epoch for any mining district, the period of mineralization. The work may involve study of features far removed from the veins and related to them only indirectly. It commonly means thorough study of the geology of the entire region surrounding the ore deposits. The following question has been suggested for discussion: "Are there any criteria by which one can determine when mining operations have reached the roots of an ore deposit?" The question deals less with the roots of a particular ore body than with the lower limit of the vertical range within which ore bodies may be expected. It concerns a critical line upon the longitudinal vertical projection of a vein.† Below this line it is useless to look for ore shoots; above the line exploration below the bottoms of individual ore shoots may be justified. Can we learn to determine the position of such a line? In some multivein districts the line for any given vein may be approximated by simple interpolation or extrapolation. Where this is possiblc the bottoms of the lowest ore shoots in the various veins are points on an imaginary, gently rolling surface. The trace of this surface upon the vein is our critical line for that vein. The imaginary surface rolls so gently that it may be projected from two or more known veins to an unexplored vein near by. Here is a criterion for the bottoming of ore that has nothing to do with changes in the appearance of the vein in question; it rests solely on the depth at which the ore bottomed in adjacent veins. The method is not applicable in districts only slightly explored in depth, nor where the lower limit of the ore-bearing horizons

Jan 1, 1941

By Wendell E. Dunn

INTRODUCTION The early history of the chloride process has been recorded in a chapter of a Bureau of Mines bulletin (9 by one of the inventors of a chloride process, Stewart Croasdale, who is famous for the Pohle- Croasdale Process. The earliest use of chlorine in metallurgy was in 1557 by Bartholome Medina. But apparently even earlier there was knowledge that salt could be used in gold and silver extraction because a treatise, de la Pyrotechnica, published in 1540 in Venice, asserted that silver could be obtained from its ores by a wet salt process. In 1609 a priest, Alonzo Barba, invented a process using a copper vessel and boiling a solution of salt to extract silver chloride ores. The copper vessel was, of course, one of the reactants. This led to the Kronke process introduced in Chile in 1860 which substituted cuprous chloride for the kettle. A major step was taken in Europe in the late 1700's to chloridize roasted silver ores in combination with amalgamation using iron to reduce the silver chloride. By 1843 the Augustan process was introduced. Ores were roasted with salt and leached with a saturated salt solution. The silver chlorides passed into solution from which silver was precipitated by copper. In 1848 sodium or calcium thiosulfate solution of silver chloride was suggested by Dr. John Percy, and the idea was applied in 1856 by Von Patera in Bohemia.

Jan 1, 1983

Jan 1, 1915

By Takuski Stanislaw, Alfons Krawiec

Rock bursting is a particular hazard in the pit-coal mines of Poland due mainly to the physical-mechanical properties of the rock and the geological-tectonic structure of the Upper Silesian Coal Basin. Mining and geophysical methods of predicting and preventing rock bursts are discussed. These include: seismologic methods, various kinds of shock blasting, torpedoing, and injecting water under high pressure.

Jan 1, 1978

By Robert L. Marovelli

A recent reorganization placed the health and safety research activities of the Bureau of Mines under a director, Division of Minerals Health and Safety Technology. The new health and safety research organization and its position in the Bureau hierarchy is shown in Table 1.

Jan 11, 1979

By C. H. Loux

THIS paper deals primarily, with the advantages realized from the adoption of methods more suitable than those previously used. The improvements noted include: (1) modification of practice in shrinkage stoping, (2) use of sublevel caving over grizzlies, (3) improved haulage and loading, (4) use of contract wages wherever possible. The Washington mine is on Jonestown Hill, one mile south of Oxford, in northwestern New Jersey. It is producing 16,000 tons of concentrates a month, which are being shipped to the Alan Wood Steel Company's furnaces at Swedeland, Pennsylvania.

Jan 1, 1933

By 000-001-568

August 15th, 1871. THE Institute assembled in Packer Hall of the Lehigh University, the President, Mr. David Thomas, of Catasauqua in the chair. Professor Henry Coppée, President of the Lehigh University, made an address of welcome to the Institute, and placed at its disposal a convenient hall for purposes of meeting. Mr. Thomas tendered his resignation as President of the Institute, as advancing years prevented him from actively participating in its meetings. The Institute declined to accept the resignation, and, on the assurance that active duties would not be expected of him, Mr. Thomas was induced to withdraw it. Invitations were received from Mr. B. C. Webster, President of the Lehigh Zinc Company, to visit the mines and works of the company; from Mr. Charles Brodhead, to visit the Chapman Slate Quarries ; and from the Lehigh Coal and Navigation Company, to visit their works at Summit Hill and Mauch Chunk and the Nesquehoning Tunnel. The Council reported the names of persons already elected in the two classes of members and associates. The following resolutions were passed: Resolved, That a committee of three be appointed, who shall take into consideration the printing and publishing of papers originating with the Institute, and that a uniform system as regards size and execution be adopted. The committee appointed consisted of Messrs. R. W. Raymond, E. B. Coxe, and the Secretary. Resolved, That the Council design and prepare a seal for the Institute at the earliest practicable time. Resolved, That a committee of six, with power to add to its numbers, be appointed to examine into the question of the more economical production of iron in this country. The committee appointed consisted of Messrs. G. W. Maynard,

Jan 1, 1873

By L. Moussoulos

Pyrite concentrates produced at the Olympias mines, Northern Greece, show an unusually high gold and silver content (16-20 and 25-40 ppm respectively), associated with the presence of arsenopyrite; their high As content (5-8%) has hindered their utilization so far. In the present paper a simple and environmentally safe method that permits their complete utilization for the production of SO2 gas, As203, and the recovery of Au and Ag is described. According to this method, the pyrites are subjected to a single-stage oxidizing roasting in a fluid bed reactor. The precious metals, and approximately 45% of the contained As, remain with the cinders, while the rest of the As is removed with the SO2 - bearing gases and can be recovered by suitable treatment. The gases, after further cleaning, can be utilized for the production of sulfuric acid.

Jan 1, 1984

By Alexander B. Morris

In a recent paper on the intermittent injection of gas in gas-lift operations as opposed to continuous injection, Morgan Walker presented a comparative table showing the effect on oil and gas production from the same wells under the two methods of operation.' This table carried a column showing the formational gas-oil ratios under each method, computed by deducting the volume of input gas from the volume of trap gas. During the entire spring and summer of 1928, the present writer had been engaged on some extensive test car tests of rich gas in Glenpool, seeking, primarily, for an explanation of the apparent loss of gasoline during the summer season between the field meters and the plant master meter. Tests at several of the field meters where the richest gas was obtained regularly failed to check with other tests on the same gas made farther along the line, and the difference was not made up by the quantity of drip gasoline collected between the points. In the course of these tests, the final outcome of which is immaterial to the present purpose, an attempt was made to construct a curve representing the relationship between gasoline content of the gas in gallons per thousand cubic feet and the shrinkage in the volume of gas treated as a result of removing the condensible fractions. Such a curve was made, expressed in units of gallons per thousand cubic feet on the abcissa and the ratio vapor volume to liquid volume on the ordinate. This curve is a rectangular hyperbola and shows that 3 gal. of gasoline taken from 1000 cu. ft. of raw gas as a vapor occupied much less space, per gallon, than did 1 gal. of gasoline taken from 1000 cu. ft. of another sample of gas. This is, in general, corroborated by converting to the same units the residue settlement curves prepared by the Tidal Oil Co. and by the Natural Gasoline Manufacturers Assn., though the three curves, when plotted together, occupy entirely different positions on the paper, as shown in Fig. 1. The bearing of all this on Mr. Walker's discussion of gas-lift is this: if the formational gas is to be computed by deducting the input gas from the trap gas, some correction must be made for the vapor volume

Jan 1, 1930

By Jose M. Sobral

The approximate production of petroleum in the various fields and for the country as a whole is shown in the following table, the figures for the later months of the year being estimated. Among the developments of the year may be mentioned the finding by the Standard Oil Co. of a small production, about 6290 bbl., at Aguas Blancas in the Province of Salta near the Bolivian border, and of about 88,000 bbl. at Lomitas, near Tartagal in the same province. The Government (Yaciementos Petroliferos Fiscales) in the last four months of the year also obtained about 6290 bbl, from Quebrada Galarce. .The oil found in Salta is of good grade and while the quantity is small great hopes of larger production are entertained. Approximate Total Argentine Production for 1928 Barrels Barrels Comodoro Rivadavia............................... 8,165,615 Plaza Huincul..................................... 783,514 8,949,129 Distribution of Production Government, Comodoro Rivadavia................... 5,165,159 Government, Plaza Huincul......................... 306,166 5,471,325 Private, Comodoro Rivadavia....................... 3,000,456" Private, Plaza Huincul............................. 477,348b 3,477,804 a The companies represented are Astra, 649,474 bbl.; Oriente, 42,237; Ferrocar-rilera, 1,337,380; Comp. Indust. y Comm., 609,092, Solano, 64,158; Diadema, 298,114. b Standard Oil Co. and a few smaller companies, Exploratory drilling has also been conducted around the Comodoro Rivadavia field. The Government is drilling at Vuela del Senguer south of Colonia Sarmiento and about 200 km. west of the main field hut the prospect of success is not as yet large. The country around Castillo, where the Royal Dutch Co. has property, is regarded more favorably. perhaps the most interesting event of the year was the discovery of a productive horizon at Comodoro Rivadavia about 200 m. below that previously exploited. This new horizon was found by the Ferrocarrilera Co. at 769 m. in its well No. 81, the previous yield for this

Jan 1, 1929

By Richard Klimpel

In this paper various formulae are developed which can be used to estimate stream flow rates or weight ratios given information on the stream components. The type and level of experimental error present in the stream component analyses does have an important bearing on the numerical values (and reliability) of the weight ratios calculated by the various formulae. A simple but theoretically sound method is shown for selecting appropriate estimation formulae for any given engineering operation. The derived formulae are applied to sets of experimental classification data for illustration purposes.

Jan 1, 1980

At the meeting of the Board of Directors the following resolution was passed: "The members of the Board of Directors of the American Institute of Mining Engineers desire: to place on record their appreciation of the very great generosity of one of their colleagues and a member of the Board, George D. Barron, expressed in his gift of $5000 to relieve the financial stringency caused by the unusual expenditures of the Institute for war work and the remission of dues of those members on active service." By-Law VIII. was amended to make a slight change in District No. 5. The report of the Auditing Committee was accepted. Tellers were appointed to: count the ballots on officers and on the proposed amendment. The proposed budget for the year 1919 was presented. The following resolution re Secretary Emeritus Rossiter W. Raymond, which had been prepared, by request, by Dr. A. R. Ledoux was then unanimously adopted. "The Board of Directors of the American Institute of Mining Engineers would place upon its minutes its profound sense of loss and sorrow in the death of Rossiter Worthington Raymond, Ph. D., LL. D., Secretary Emeritus of the Institute. Both as one of its founders and as its Sec-retary for 27 years, his was the guiding spirit of the Institute for more than a generation. "During the greater part of this long period, it might almost have been said that the Institute was Dr. Raymond-and Dr. Raymond the Institute. When with the progress of growth and development, great changes were introduced, Dr. Raymond acquiesced in these in spite of some misgivings, such as those with which a father might contemplate the emergence of his child from the careful supervision of the home; but as Secretary Emeritus for the past eight years, lie was always ready with valuable advice and helpful suggestion.

Jan 3, 1919

By Colin Fink

TANTALUM and columbium occur together in tantalite and columbite ores, which may be considered as ferrotantalate (FeTa206), with part of the iron and tantalum replaced by manganese and columbium respectively, the general formula, therefore, becoming (Fe, Mn)O.(Ta, Cb)205. The ratio of tantalum to columbium is not fixed; the amount of tantalum may vary from one-third to three times that of columbium. Minerals having a high content of tantalum are called tantalite, while those possessing larger amounts of columbium are classified as columbite ores. These minerals are found in pegmatites and often occur in veins associated with cassiterite and wolframite, and may contain small amounts of tin, tungsten, titanium and silica.1

Jan 1, 1931

By N. E. Norman

During the past few years the underground mining industry and the big hole drilling industry have been involved in a flirtatious courtship, but until recently this courtship did not appear to be taken too seriously by either party. However, many of the promises made by the big hole industry are beginning to come true. Improvements have been made steadily in techniques of mechanical boring of large diameter shafts, raises and tunnels, thus making the big hole industry a more stable partner in the eyes of the mining industry. The mining industry too has made many changes in planning that make mining more attractive to the big hole industry. If there is to be a marriage between big hole drilling and mining, we should certainly take a look at the background of the big hole drilling industry, and examine the three main features of big hole drilling to determine how each applies to mining. Shaft Drilling Since 1950, numerous large diameter shafts have been drilled using rotary drilling techniques. Most of the larger diameter shafts have been drilled for the AEC for underground nuclear testing purposes. However, since 1960 several shafts have also been drilled for various mining companies, particularly in the United States. In 1967, rotary drilling shafts were either completed or in progress at the mining companies listed in Table I.

Jan 6, 1968

By J. W. Downey, A. E. Dwight, R. A. Conner

In a previous paper' we have reported the existence of a number of AB2 Laves phases in which A is a member of the scandium group (including the 1an-

Jan 1, 1967

By E. V. Foran

Among the many newer disclosures that have accompanied the petroleum industry's progressively deeper exploratory drilling is the increased frequency with which the operators are encountering reservoirs of which the products at the time of discovery exist wholly or predominantly in the gas phase. The popular term "distillate pool" is most often used within the industry when referring to this type of reservoir, and in this paper the term is used in that sense. These pools have been observed in many different surroundings. In some places the entire reservoir is filled with the wet gas containing its water-white condensible products in the gas phase but apparently with no dark oil or other hydrocarbon liquids in the reservoir. The 8200-ft. horizon in the Big Lake field in West Texas is a good example of this type. At other places the wet, or distillate-bearing, gas may form a large gas cap directly overlying and in contact with an extensive reserve of dark oil. Oklahoma City, Kettleman Hills, the 8500-ft. horizon in the Big Lake field, and many others are examples of this type. There are also many places in which the wet distillate-bearing gas fills nearly the entire reservoir space, while the dark oil occupies only a narrow, bandlike zone, which marks the boundary of the reservoir along its lowest productive contour. The heavier components of these deep pool gases are generally water white in color, a large portion of which are condensible in a conventional oil and gas separator, when operated under pressures of the order of 400 to 800 Ib. per sq. in. Although the water-white products recovered in the separator sometimes have end points of 650" F. and higher on standard Engler distillation, they occur only in the gas phase in the reservoir. It is entirely possible that even some small amounts of dark colored reservoir components may occur in the gas phase when the temperature is 300" F. and pressures exceed 6000 Ib. per sq. in. Close approaches to these conditions have been encountered in the deepest producing wells. The condensible content of the deep reservoir gases of the many pools that have been tested or produced to date shows a wide variation in both condensible content, per 1000 cu. ft. of gas, and physical character.

Jan 1, 1939