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By J. D. Corbett

Mining geophysics in 1967 continued to expand with greater application in the exploration and development of mineral deposits. Moreover, geophysical activity increased without the particular emphasis of a Pine Point or Timmins discovery to spur interest. This trend is expected to continue through 1968 as geophysics more and more becomes an integral part of a mineral exploration program. This past year saw the "little black box" of the old-fashioned "doodlebugger" pushed further into the background, replaced by increasingly sensitive equipment of sophisticated design. The trend also is away from the one man geophysical operation wherein the same individual is responsible for the development, design and operation of the field gear, the planning and execution of a survey and analyzing and interpreting the data. In today's technology a staff of specialists, electronics engineers, mathematicians, physicists-to name but a few- are required to back up the exploration geophysicist in the development of new methods and techniques, in the reduction of the voluminous amount of field data and in the interpretation of the anomalies which can be enhanced by various high-speed computer techniques. Obviously a full back-up staff of these varied abilities is impractical to most exploration companies. However, the equivalent function is provided to the lone staff geophysicist by the many competent geophysical contractors and individual consultants.

Jan 2, 1968

By Franklin Bache

There seems to be in the public mind, and even in the minds of some coal-operators not experienced in mines subject to dust-explosions, a feeling that there has been somet-hing mysterious at the bottom of a number of recent American colliery-exploaions. It has been declared in cases of accidents in mines regarded as particularly well equipped, in which every preventive precaution was said to have been taken, that the explosions were incomprehensible, and resulted from causes beyond the present knowledge of the practical coal-operator. But it is safe to say that no explosion has taken place which could not be explained by reasons well understood by most operators. The U. S. Geological Survey Testing Laboratory, recently inaugurated at Pittsburg for the reported purpose of investigating scientifically the matter of explosions in mines, will discover no new explanation of explosions. It can, however, co-ordinate the previous investigations of similar boards in England and on the Continent; and it may do a vast amount of good by promulgating widely, and in a form comprehensible to the most unlettered miner, certain facts and obvious deductions that cannot but have an effect in reducing the number and extent of the mine-disasters which, in the last few years, have been so terrible in frequency and magnitude.

Jan 1, 1910

By Lawrence Addicks

Discussion of the paper of LAWRENCE ADDICKS, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 104, August, 1915, pp. 1471 to 1484. L. D. RICKETTS, New York, N. Y.--In the Southwest we have stored up millions of tons of tailings in which the copper exists partly as sulphide and partly in an oxidized condition. Mr. Addicks' first paper suggests a, likely process for the treatment of such material. His second paper 1 deals with the recovery of copper from clear solutions of notable strength, and such solutions may come from the sulphating roast or direct from the leaching of completely oxidized copper ores of which vast deposits are known to exist. What strikes me particularly about the latter paper is the keen perception shown and the clear manner in which the writer has attacked the fundamental principles of the process. He calls your attention to the fact that ferrous sulphate is necessary in the electrolyte and is an ideal depolarizer; that sulphurous acid must be, used to reduce the ferric sulphate produced and thus prevent re-solution of copper at the cathode; that mechanical agitation in the cell, in order to bring the ferrous sulphate in contact with the anode and the copper in contact with the cathode, is essential to efficient work; that lead anodes are

Jan 12, 1915

By J. Howard Boyce

INTRODUCTION The Tsumeb Mine is situated in the northern part of South West Africa, approximately 335 air miles north-east of the port of Walvis Bay on the Atlantic Coast, and 240 air miles north of Windhoek, the capital of South west Africa. The mine came into operation in the early 1900's and has operated continuously since then except during the two world warm and the depression years of the thirties, Tsumeb Corporation purchased the property in 1947, installed a new plat, and ham built a modern tom. In addition to the concentrator which began operations in 1948, a copper smelter was started in 1962 and a lead smelter in 1963, Tonnage of ore treated in the concentrator has varied through the years, reaching a maximum of 70,000 tons per month with a current mined tonnage of approximately 50,000 tons per month. Copper concentrates, lead concentrates and zinc concentrates are produced, and for a number of years the production of a germanium enriched concentrate was an important feature of the operation, Both copper and lead concentrates are smelted in Tsumeb, while the zinc concentrates are shipped overseas. Ore change, and the installation of the smelters in Tsumeb have necessitated modifications in the concentrator operation. This paper will describe current plant practice in some detail and will touch briefly on the techniques used from 1954 to

Jan 1, 1970

By Henry S. Poole

This field is geologically of much interest. It is small, hut with some seams of unusual thickness, the main one being as much as thirty-eight feet thick. The quality of the seams, as also of the associated beds of shale and sandstone, in several instances changes to a remarkable degree within short, distances. The strata dip at inclinations that carry the coal to depths of 3000 feet or more; heavy faults cut up the district, and the New Glasgow conglomerate, of disputed age, separates it from the Upper Carboniferous measures, in which no seams of workable thickness are known. This coal-field offers to the geologist much ground for study and peculation. The commercial value of the field is affected by its restricted area, the varied quality of its coal, and its advantageous position in the mainland, with railway connection and home markets, offset by the physical difficulties which make the cost of production high. It has been so long a habit with us to speak of our resources of coal as boundless, that any adverse comments, or insinuations that avoidable loss in working is a national loss, hare hitherto fallen on idle ears. While it is not my purpose to underrate the riches we do possess, yet I deem that no good end is served by echoing exaggerated estimates which encourage a national indifference to wasteful

Jan 1, 1886

By F. C. Schrader, Alfred H. Brooks

Last fall (1899) we had the good fortune to be able to spend a few weeks in the new placer gold-mining region of Alaska, which is known as the Nome region. Cape Nome, after which the region has been named, and which forms the southeastern corner of the Nome Mining District, is an unimportant promontory on the southern coast of the Seward Peninsula (see map, Fig. 1). The name Seward has recently been given to the great peninsula which forms the northwestern extremity of Alaska. To the north of it is the Arctic ocean, to the south Bering sea, while its wesbernmost extremity, Cape Prince of Wales, is separated from the Asiatic coast by the Bering straits. The coast line of the peninsula is of a cuspate character, consisting of a succession of sandy, crescent-shaped beaches and rocky headlands. The interior has been but little explored; but we know that it is comparatively rugged, the higher mountain peaks rising probably from 4000 to 5000 feet in elevation. The mountains have an easterly and westerly trend, and the water-shed between the two oceans probably nearly bisects the peninsula. At Golofnin bay, the southeastern part of the Seward peninsula, some spruce is found, but to the west the region is entirely timberless, except for a sparse growth of stunted

Jan 1, 1901

By Richard B. Greenwalt

INTRODUCTION Direct reduction of iron ores has unquestionably become established as an important step in the worldwide steelmaking industry. The history of this development has been long and fraught with difficulty. In 1800, Champlain suggested the direct reduction concept using carbon and a shallow hearth vessel. Roughly 100 years later, Jones attempted a commercial process using carbon and producer gas in a rotary kiln. During the early years of this century, numerous attempts were made to start commercial direct reduction plants using such processes as Hoganas, Wiberg, Krupp-Renn, and others. Most of these were short lived, being abandoned due to a variety of technical and economical factors. Today, however, a new generation of direct reduction processes has emerged. We enter 1977 with at least 40 commercial plants in operation using 15 processes in 14 countries. These plants have combined total annual capacity of roughly 10 million tonnes of direct reduced product. Many articles have been written, and projections made, concerning the future growth potential for direct reduction. As is al- ways the case with projections, the numbers vary, but the outlook does not. Anyone who participated in the years of effort that have gone into this field of endeavor should be excited and justly rewarded by noting the shape of the curve in Figure 1.

Jan 1, 1977

THE Institute assembled in the Hall of the Boston Natural History Society on Tuesday evening. Dr. T. Sterry Hunt, of the Boston Institute of Technology, after a brief address of welcome to the Institute, read an introductory paper on the Geognostical History of the Metals. President Raymond responded to the welcome of Dr. Hunt. The following names were then presented to the Institute, with the recommendation of the Council, for election: Adams, J. M., . . . . . . Silver City, Idaho. Daggett, Ellsworth,. . . . . Salt Lake City, Utah. Geist, Alfred W., . . . . . Boston, Mass. Hays, Dr. S. Dana, . . . . . Boston, Mass. Heinrich, Oswald J., . . . . Midlothian, Va. Johnson, J., . . . . . . Braidwood, Ill. Leckie, Robert G., . . . . . Actonvale, Canada. Lyman, Edward, . . . . ' . Troy, N. Y. Maltby, William, . . . . . Braidwood, Ill. Nichols, Lyman, Jr., . . . . Bbton, Mass. Ordway, Prof. J. M., . . . . Boston, Muss. Rand, Theodore D , . . . . . Philadelphia, Pa. Richards, Prof. Robert H., . . . Boston, Mass. Roclrwell, Prof. Alfred P., . . . Boston, Mass. Roepper, Charles W ., . . . . Bethlehem, Pa. Schulz, A. von, . . . . . Central City, Colorado. Singer, William F., . . . . Pittsburgh, Pa. Spillsbury, E. G., . . . . . New York. Wells, Calvin, . . . . . . Pittsburgh, Pa. The session concluded with the reading and discussion of a paper, by Henry Engelmann, On the Mines and Ores of the Little Cottonwood Canyon, Utah. The second session was held on Wednesday morning, when the following papers were presented : On the Midlothian Coal Mines, by Oswald J. Heinrich. On the Probable Existence of Microscopic Diamonds in California, by Prof. Benjamin Silliman.

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Mine Superintendent or Manager. Age 34, graduate mining engineer. Thirteen years' practical mining experience in Canada and United States holding responsible executive positions, mining engineer and mine superintendent. Experience in iron, gold, copper, and pyrite mining. Best references, can go anywhere but prefer location in Canada. At present engaged but desire change. Minimum salary $3600. A-2845. Manager or Superintendent for producing mine or new development. Institute member, 25 years' experience, mining, wet concentration, construction and examination. A-1173. Mining and Metallurgical Engineer. Technical graduate, 11 years' practical experience principally with copper mining, milling, smelting, and electrolytic refining, now holding an engineering executive position, wishes to change to place of more responsibility and opportunity. A-3785. Engineer with 11 years' experience in mining, civil, and industrial engineering, desires to become connected with a strong organization requiring services of thoroughly trained man. Graduated from University in 1909, now employed, having been with present organization nearly 7 years. Available about Sept. 15. A-4071. Metallurgical Engineer, age 31, married, A. M. and Ch. E.; 7 years' teaching and industrial experience, of which 3 ½ have been with electric furnaces. Desires position in investigative or executive work. Minimum salary $3000. A-4176.

Jan 9, 1919

The following is an incomplete list of members and guests who' called at Institute headquarters during the period Mar. 10, 1918 to Apr. 10, 1918. W. Sinclair Brown, Lebong Donok, Sumatra. F. Laroque, Roodepoort, Transvaal. H. B. Catlin, Syracuse, N. Y. A. H. Means, Camp Upton. A. R. Chambers, New Glasgow, Nova Scotia. J. H. Miles, Nome, Alaska. W. M. Corse, Buffalo, N. 1 . Harvey S. Mudd, Washington, D. C. George C. Crossley, Toms River, N. J. Henry Noyes, Melbourne, Aust. F. A. Dalburg, Montoursville, Pa. C. L. Petzel, Camp Upton. Kuno Doerr, El Paso, Tex. J. L. Schueler, Peoria, I11. V. E. Edwards, Worcester, Mass. J. G. Scrugham, Reno, Nev. H. F. E. Gamm, Rutherford, N. J. Frank M. Smith, East Helena, Mont. J. W. Gerhard, St. Louis, Mo. W. G. Swart, Duluth, Minn. Julius H. Gillis, Sudbury, Ont., Canada. A. L. Sweetser, Boston, Mass. S. J. Gormly, Guayacan, Chile. W. N. Thayer, Cincinnati, Ohio. Fletcher Hamilton, San Francisco, Cal. Felix E. Wormser, Cornucopia, Ore. Dorsey A. Lyon, Washington,. D. C. John B. Arnold has opened offices at 606 Lyceum Bldg., Duluth, Minn. E. E. Barker, formerly mine superintendent with the Chile Exploration Company at Chuquicamata, Chile, has resigned his position to become superintendent of mines for the Cerro de Pasco Copper Corporation at Cerro de Pasco, Peru.

Jan 5, 1918

Attention! Engineers! Geologists! Here is your Opportunity to be of Professional Service The war has interrupted the supply of many minerals, which were normally imported. In view of present transportation conditions, a serious shortage exists in certain materials and will soon develop in others. Some immediate action is imperative. The first thing is to take a careful inventory of American resources. We must know where the ore deposits are, what has hitherto hindered their utilization, what methods must be used, and what equipment will be needed if an emergency demands their rapid development. Many properties must be re-examined from a new point of view, that of present necessity rather than of normal profit. When the shortage is realized, the preliminary steps for relief should have been completed. It is a necessary and patriotic form of mineral insurance. Will you have a part in it? Do not forget that these are war times, and that what may have been valueless a year ago may be a "life-saver" now; an abandoned copper prospect of 1913 might make a successful pyrite mine in 1917. We are fighting an autocratic enemy who knows his resources to the last pound, and uses them with most efficient organization. We have no Kaiser, so each of us must do his share to put our Government in the same situation. The Government needs your facts.

Jan 8, 1917

By Robert Hunt

(New York Meeting, February, 1913.) I HAVE frequently stated that while the chemical composition of steel is important, yet even greater importance is connected with the mechanical and heat treatment of the metal. During the past year I encountered such a positive example of that fact that I deem it worth putting upon record. A prominent railway system divided an order for open-hearth steel rails between two steel works, both of which are under the control of the one corporation; giving to one about 18,000 tons, and to the other 7,500 tons of the same section and to be made under the same specifications. The rolling results obtained in the two mills varied so widely that a study of the figures is intensely interesting and serves to illustrate the advantages obtained by careful ingot casting, and, quite as pertinently, the possible benefits of careful subsequent heating and rolling with moderate reductions in the rolling process. The smaller order was rolled complete in four installments during the same months that the larger order was being made in six separate installments; but, to permit of exact comparisons, the totals of the four installments (completing the order with the mill which I will call A) are given with the totals of the first four installments of the larger order, made by the mill designated as B. These rolling results are:

Jan 5, 1913

By A. P. Herring, S. F. Ravitz

Manganese dioxide reacts with sulfur dioxide solution in the absence of oxygen to form manganous ion and dithionate ion, together with a small amount of sulfate ion. The effects of SO, concentration, hydrogen ion concentration, stirring speed, and temperature on the rate of the reaction were studied. If it is assumed that undissociated SO2 molecules react rapidly with MnO, at active surface sites and that bisulfite ions react slowly, an equation can be derived that satisfactorily represents the observed reaction rates. For solutions in which the reaction with undissociated SO2 predominates, reaction rates and activation energies estimated from diffusion theory agree well with those found experimentally. Manganese dioxide dissolves readily in aqueous solutions of sulfur dioxide. The nature of the dissolution reaction was first investigated by Gay-Lussac and welter1 in 1819; they identified a new oxysulfur radical, the dithionate ion, S2O6, as one of the reaction products. Since then, the reaction has become a standard method of preparing dithionates in the laboratory and one of the more promising methods of leaching manganese from low-grade ores. In the "dithionate process" developed by the U.S. Bureau of Mines2,3, manganese-dioxide ore is suspended in a solution of calcium dithionate and leached with gas containing sulfur dioxide. The manganese is dissolved and the sulfur dioxide is oxidized according to the reactions:

Jan 1, 1965

By E. P. Shea

The Anaconda Co.'s Geological Department at Butte, Mont., was started early in the Company's history because of litigation involving vein ownership and extralateral rights. The problems, some of which were resolved in courts, were many because of the large number of veins and lode locations. Defensive action was required to prove ownership and protect against illegal exploitation of the downward and extra-lateral extensions of the ore bodies. In many cases it was necessary to define the outcrop of the vein and to show that its apex was within the boundaries of the lode claim. Exhibits illustrating geology were needed to present the cases clearly, and these could be made only after careful inspection and mapping of the underground workings by competent geologists. Also, The Anaconda Co. was one of the first companies to recognize the worth of skilled mining geologists and the value of accurate records in the search for new ore. The department was organized in 1900 by H. V. Winchell who, with D. W. Brunton, worked out the methods. Reno Sales was Chief Geologist from 1906 until 1948 when he was succeeded by V. D. Perry, the present Chief Geologist. Under their direction, F. A. Linforth, M. H. Gidel, C. H. Steele, E. P. Shea, C. C. Goddard, Jr., and W. A. O'Brien enlarged the scope of the work and improved the technique.

Jan 3, 1961

By Hendon R. Johnston

In the Tennessee Valley Authority's program of investigation and treatment of foundations for major structures, many chert, or flint, bodies have been encountered during the diamond-drilling operations. These chert bodies occur most frequently in the Knox dolomite and

Jan 1, 1948

By Hendon R. Johnston

In the Tennessee Valley Authority's program of investigation and treatment of foundations for major structures, many chert, or flint, bodies have been encountered during the diamond-drilling operations. These chert bodies occur most frequently in the Knox dolomite and

Jan 1, 1948

Elected Died 1895 *ABBOTT, AI ATTHUR 1908 1882 *ABBOTT, ARTHUR V 1906 1905 * ABE, MASAYOSHI 1909 1903 * ADAMS, CHARLES C. 1905 1906 * ADAMS, JOHN C. 1913 1905 * ADAMS, WILLAMS 1909 1903 * ADAMS, W. EDWARDS 1910 1884 *ADDY, MATTHEW 1896 1906 * AFFLECK, WILLIAM A. 1911 1889 * AKERS, WILLIAMS A. 1906 1905 * ALABASTER, RUPPERT C. 1911 1899 * ALBERGER, LOUIS R. 1911 1894 *ALLEN R B 1896 1905 * ALLEN, R. SCOTT 1906 1874 * AMIOT, H. 1892 1886 *AMSLER, CARL 1894 1898 ** ANDRSON, JOHN W 1905 1895 *ÅNGSTROM, CARL 1901 1887 * ARCHBALD, JAMES 1910 1900 * ARLETT, GEORGE H 1906 1895 *ARMSTRONG, JOHN F 1898 1882 *ARNOLDS, HUGO 1886 1875 *ASHBURNER, CHARLES A 1889 1872 *ASIIBURNER, WILLIAM 1887 1883 *ATKINS, C M , JR 1885

Jan 1, 1917

By O. Mellgren, A. M. Gaudin, P. L. De Bruyn

The adsorption density of ethyl xanthate on pyrite was determined as a function of xanthate concentration. Surface preparation of the mineral appears to have asafunctionsome effect on the subsequent adsorption process, A monolayer of xanthate on the surface is exceeded only in presence of oxygen. The effect of OH- , HS- (and x and CN- S=)and on the amount of xanthate adsorbed was investigated. Competition between OH- and X- (xanthate) ions for specific adsorption sites is indicated over a wide pH range. IN the flotation of sulfide ores, xanthates are most commonly used to prepare the surface of the mineral to be floated so that attachment to air takes place. The quantity of agent required to make the mineral hydrophobic is usually very small, of the order of 0.1 to 0.25 lb per ton of mineral. Details of the mechanism of pyrite collection are for the most part unsettled. Adsorption of collector has long been believed to involve an ion exchange mechanism as demonstrated for galena' and for chalcocite.2 In the work on chal-cocite it was also demonstrated that a film of xanthate radicals unleachable in solvents that dissolve alkali xanthates, copper xanthate, or dixanthogen was formed at the surface of the mineral. The unleachable product increased with increasing addition of xanthate up to a maximum corresponding to an oriented monolayer of xanthate radicals. Pyrite is extremely floatable with xanthate if its surface is fresh.9 ut the floatability decreases rapidly as oxide coatings increase in abundance. Pyrite shows zero contact angle when in contact with ethyl xanthate solution at pH higher than about 10.5;4 at neutrality, a contact angle of 60" is obtained at a reagent concentration of 25 mg per liter. Alkali sulfides and cyanides are pyrite depressants. In this study of pyrite collection the writers have sought to relate measured xanthate adsorption to the method used in preparing pyrite, to the presence or absence of oxygen, to concentration of hydroxyl, hydrosulfide, sulfide, and cyanide ions. The principal experimental tool has been radioanalysis," " using xanthatcx marked with sulfur 35. Experimental Materials Pyrite: Unlike most sulfides, pyrite is a poly-sulfide. The structure given by Bragg7 resembles that of sodium chloride, the iron atoms corresponding to the position of sodium and pairs of sulfur atoms corresponding to the position of chlorine. The edge of the unit cell in pyrite is 5.40 A and in halite 5.63 A. The S-S distance in pyrite is 2.10 A; the Fe-S distance, 3.50 A: and the Fe-Fe distance, 3.82 A. Natural pyrite from Park City, Utah, was used in this investigation. Pyrite 1 was obtained by hand picking pure crystals. Pyrite 2 and Pyrite 3 were obtained from finer textured crystalline material containing inclusions of silicates. The same cleaning technique was utilized for the preparation of Pyrite 2 and Pyrite 3, whereas a different cleaning technique was used for Pyrite 1. Pyrite 1 was prepared as follows: The crystals were ground in a porcelain ball mill and the 200/400 mesh fraction was separated by wet screening with distilled water, followed by washing for 1 hr with deoxygenated distilled water acidified with sulfuric acid to pH 1.5. The acid was removed by rinsing with deoxygenated distilled water on a filter until a pH of 6.0 was reached in the effluent. This filtration was carried out under nitrogen. The sample was then dried in a desiccator under nitrogen. The period of time for which this pyrite sample was in contact with water containing oxygen was about 4 hr. The specific surface as determined by the BET gas adsorption method was 582 cm2 per g. Final material assayed 53.12 pct sulfur and 46.5 pct iron (theoretical, for FeS,: S, 53.45 pct; Fe, 46.55 pct). After crushing, Pyrite 2 and Pyrite 3 were washed with 1 M HCl. rinsed, and fed to a laboratory shakinq table to remove the small amount of silicates. The concentrate obtained was ground in a laboratory steel ball mill. The 200/400 mesh fraction was separated by classification in a Richards hindered settling tube. This fraction was then given a final wash with 0.1 M HCl and deoxygenated water was filtered through the sample. The final effluent showed a conductivity equivalent to that of a solution having a salt concentration of 0.3 ppm. Aqueous hydrogen sulfide solution was then added to the sampln (about 100 ml saturated H,S solution to about 1000 g pyrite under a few hundred milliliters of water) which was stored wet under nitrogen. The sample stored in this manner showed no indication of formation of iron oxides, whereas iron oxides appeared

Jan 1, 1957

By Richard R. Zupp, David A. Stevenson

An experimental method to determine the carbon activity in various solid solutions was developed. Samples of the solid solutions and an Fe-C reference sample were equilibrated with respect to carbon content by annealing them in a Hz-CHI gas mixture in a closed cell. The carbon content of each sample was determined, and the carbon activity was obtained from the carbon content of' the reference sample and well-established data for the dependence of the carbon activity on the carbon content in Fe-C alloys. The influence of vanadium on the activity of carbon in austenitic Fe-C-V alloys at 1000°C was determined by this technique. A general semiempirical correlation was developed to describe the dependence of the activity coefficient of- carbon on the composition of ternary austenitic iron-base alloys containing interstitial carbon and a substitutional solute. The correlation is particularly useful in predicting the partitioning of- carbon between various alloys. THE influence of substitutional solutes on the activity of interstitial solutes in metallic solid solutions is important in the theory of alloy phases. Solid solutions of particular interest are the fcc austenite phases of ternary Fe-C-Z systems, in which carbon is the interstitial solute and Z represents any substitutional solute. Carbon-activity data are also needed in these solid solutions to solve practical problems; the quantitative treatment of diffusion-controlled transformations' is an examvle. Experimental information is available for ternary austenitic solid solutions containing Mn,2 Si,2 and A16 as the substitutional solute. Because qualitative preliminary studies indicated that vanadium appreciably decreases the carbon activity,14 the present investigation was undertaken to determine the influence of vanadium on the activity of carbon in austenite. Although Flender and ever" measured carbon activity over a range of compositions in the Fe-C-V system, they were primarily interested in determining phase boundaries in the ternary system, so most of their measurements were outside the composition range for stability of single-phase austenite. Petrova and Shvartsman' also made limited measurements of the carbon activity in Fe-C-V alloys. The dependence of the carbon activity on the carbon content of an alloy may be determined by passing COCOz or H2-CH4 gas mixtures of carefully measured composition over the alloys, determining their equilibrium carbon content, and utilizing the relevant equilibrium relationships. smith16 used this technique with both CO-COZ and HZ-CH4 gas mixtures to determine the dependence of carbon activity on carbon content in pure Fe-C alloys. His data, which are in good agreement with those of some previous and subsequent investigators,6'17 but not with those of others,lfl'ao are usually considered to be the most reliable. Although the same method can be applied to Fe-C-Z alloys, it is difficult experimentally, because the appropriate gas mixtures are almost pure CO or Hz. A simpler technique is to simultaneously equilibrate the Fe-C-Z alloys and pure Fe-C alloys with the gas mixtures, and then use Smith's data to determine the carbon activity in the pure Fe-C alloy. A number of investigators have employed this technique. others Have used the partitioning of carbon at the interface of a diffusion couple prepared from an Fe-C alloy and a Fe-C-Z alloy. In the present study, a closed-cell method was developed by which carbon was selectively transferred via a gas medium between pure Fe-C alloys and Fe-C-V alloys which were not in physical contact. A similar method was developed independently by Heckler and winchel14 and used to study the Fe-C-Ni system. EXPERIMENTAL METHOD A schematic diagram of the experimental arrangement is shown in Fig. 1. In a typical experiment, a 5-g Fe-C sample was placed in one compartment of a quartz cell, and a 5-g Fe-V sample was placed in each of the other compartments. The cell was evacuated, outgassed, backfilled with approximately 125 Torr of hydrogen, and sealed. After being placed in a fur-

Jan 1, 1967

By R. H. McLean

Jet impingement produces two mechanisms to clean the bottom of a borehole during jet-bit drilling operations. One is an impact-pressure wave in the immediate area of jet impingement. The other is crossflow, which spreads across the bottom away from the pressure wave. Measurements of the vertical distribution of the cross-flow at several positions beneath a 4 3/4-in. tricone jet bit in a laboratory model show that the maximum velocity in the crossflow is directly proportional to the square root of the product of the rate of flow and the velocity of the jets through the nozzles (QV). Other measurements in the laboratory model show that gradients in the impact-pressure wave are directly proportional to the jet QV if the diameters of the nozzles are held constant. Consistency of the basic relationships through changes in the Reynolds numbers of the jets from 31,000 to 93,000 suggests that the laboratory results should be representative of typical flow in field operations having higher Reynolds numbers. Estimates of the impact-pressure waves under conditions other than those in the jet-bit model may be made by comparison with a less complex model—impingement of a jet against an unrestricted flat surface normal to the jet. Equations derived from current jet technology describe the wave in this simple system for a wide range of conditions. INTRODUCTION The efficiency of rotary drilling operations is strongly linked to the efficiency with which cuttings are removed. Cuttings remaining on the bottom of the borehole will impede further penetration by the bit until they are removed. Wasteful regrinding is prevented if the fluid circulated past the bit removes cuttings as rapidly as they are made. Most investigations of bottom-hole cleaning under bits have been concerned with the rate-of-penetration effects of bit type, nozzle configuration, fluid properties, pressure gradients and utilization of hydraulic horsepower. These investigations have shown that drilling muds, weighted to keep the pressure in the borehole greater than in adjacent formations and carrying material which forms a filter cake, apparently plaster cuttings against the bottom, making them difficult to remove. In addition to a demonstration of the factors causing poor cleaning, the most significant result of these previous investigations has been the increased use of jet bits accompanied by better hydraulic programs and better selection of drilling fluids. Undoubtedly, these practices have improved bottom-hole cleaning, but rates of penetration when drilling with muds are still often lower than would be expected with perfect cleaning." Although there is general agreement with the concept that increasing hydraulic energy at a jet bit often increases the rate of penetration by improving cleaning, research workers have differed as to the best criterion for evalyating hydraulics. Some lean toward maximizing the product of the rate of flow and the velocity through the nozzles (QV) others prefer to maximize the hydraulic horsepower at the bit;'"-' "till another says that neither criterion is universally suitable."' This controversy shows that conclusive field evidence has not established the superiority of either of these criteria. Analysis of the fluid flow which cleans the bottom should contribute to resolving the controversy. Impinging jets clean the bottom by creating two mechanisms capable of dislodging cuttings. One is the impact from the momentum of the jet and the other is the flaw parallel to the bottom away from the area of impingement. The impact force appears in the form of a pressure wave on the bottom and, in this paper, is called the impact-pressure wave. The flow parallel to the bottom is called crossflow. Fig. 1 illustrates these two mechanisms. This paper describes crossflow and the impact-pressure wave beneath jet bits and relates them to controllable parameters. Through these relations, criteria for use in designing hydraulics to achieve maximum use of the mechanisms of cleaning are derived. PROPERTIES OF CROSSFLOW CONCEPTS DEVELOPED IN PREVIOUS INVESTIGATIONS Concepts of scavenging the bottom by crossflow have been well discussed by Bobo, et al." They examine the means by which crossflow may create forces on cuttings and conclude that the cleaning action of crossflow can be increased by increasing the velocity of the flow stream close to the bottom. Using boundary layer theory, they indicate that a reduction in the viscosity of the drilling

Jan 1, 1965