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By Fred A. Anderson, George B. Wallace, Edward J. Slebir

As the reservoir rises behind an arch dam, it presses the arch into the canyon walls and valley floor. To compute the stresses, deflections, and arch reactions, it is necessary to know how much the rock deforms under the combined loads of gravity, temperature, and water. Under sustained loading for a period of time, the rock continues to deform or "creep" slightly, causing changes in the stresses and shape of the arch. Under reduced loading, the elastic arch tends to resume its unstrained position and it is important to know that the rock will follow it and maintain tight contact along the abutment. It is, therefore, important to know the "set" characteristic of the rock. Past attempts to define load-deformation properties of rock, including creep and set, have largely l been limited to laboratory test of intact cores and in-situ jacking test utilizing bearing plates 2 to 3 ft in diam. In both cases, a uniaxial load has been applied to a volume of rock too small to fully reflect the influence of cracks, joint systems, foliation, and other inherent weaknesses within the rock mass. This chapter describes a large radial jacking test which more nearly duplicates the action of an arch dam by penetrating the load deep into the rock mass, bringing into play more of the factors which contribute to prototype deformation. Results obtained from the large radial test are compared with those from smaller uniaxial test. DESCRIPTION OF RADIAL TEST The radial jacking test described in this chapter was performed in an adit off of an exploratory tunnel driven into a proposed dam abutment

Jan 1, 1972

By H. V. Fairbanks

This report covers a study of three different methods for drying ultrafine coals by sound waves. Ultrafine material is classified as coal which passes through a 100-mesh sieve. During the investigations, it was found that the addition of acoustic radiation to the drying of ultrafine coal is effective in increasing the rate of drying; the effect of acoustic radiation to improve drying decreases with an increase in the temperature of the system; the drying rate increased 10-40% when acoustic radiation was introduced into a rotary kiln but was dependent upon the environmental conditions; the application of vertical vibrations to multi-tiered drying screens increased the rate of moisture removal ten times over that obtained in the rotary kiln; the formation of coal balls in any of the drier systems retards the rate of drying; the higher the initial moisture content of the coal the greater the amount of coal balls formed.

Jan 1, 1970

By Frank C. Schader

JOHN CARTER ANDERSON, Kingman, Ariz. (communication to the Secretary *).-From an extended study of the Oatman and Secret Pass districts of Mohave County, Arizona, I believe that the genesis of the ore deposits, in most cases, is directly connected with rhyolitic intrusions later than the Tertiary flows; and that the developments of, the future will prove these intrusives to be the primary source of the ore. In support of this opinion I will instance the Wilhelm-Eclipse dike in Secret Pass and the Murdock, Nellie, Black Range dike and ledge in the southern part of the Oatman district. The Wilhelm-Eclipse dike is a very fine-grained light-colored siliceous rhyolite dike with a strike of N.45W. traversing the full length of the Secret Pass district about midway between two major faults which mark the easterly and westerly boundaries of the district. These faults .have lifted the block between so that erosion has exposed the pre-Cam-

Jan 4, 1917

By G. W. Josephson

GRANULAR mineral products used primarily to form a protective and decorative coating on the weather surface of composition roofing are called "granules," "roofing granules," or "slate." The latter term is a relic of the early days of the industry, when crushed slate was the dominant type of granule in use. Asphalt roofing is made by saturating and then coating a continuous strip of felt with specially compounded asphalts. Granules are embedded in the hot asphalt on the top of the sheet, and mica or talc is dusted on the back. After passing through press rolls, the strip is looped on a conveyor for cooling and then cut into shingles or packaged as roll roofing. HISTORICAL DEVELOPMENT Although the durability and protective qualities of asphalt and tar have been known since the earliest days of recorded history, it was not until 1780 that the first forerunner of present-day composition roofing was developed.' Large-scale expansion of the industry has taken place since 1900. At first the process consisted simply of dipping sheets of burlap or other fabric into a tank of molten tar or asphalt. The long strip of roofing was rolled up, for convenient handling, and the early experimenters soon found that it was necessary to dust the surface of their new "roll roofing" with some kind of material that would prevent the tarred surfaces from sticking together. Any finely divided, low-priced local material like sand or fine gravel served this purpose and from its application the roofing-granule industry grew. As time went on, other characteristics of a properly applied mineral surfacing were recognized. As with wooden shingles, tar and asphalt can be ignited by flying embers from nearby fires. It was found that by in- creasing the largest particle size to the maximum that could be success- fully embedded and by properly controlling the amount of smaller fractions retained in the grade, so as to cover the asphalt completely, a high degree of resistance to fire was attained.

Jan 1, 1949

By R. B. Tippin, J. S. Browning

The feasibility of multistage heavy liquid cyclone beneficiation of spodumene was successfully demonstrated in this investigation. The indicated recovery for the multistage circuits was mathematically estimated as continuous test runs would be necessary to determine the true influence of a middlings recycle. In the three-stage circuit, both the concentrate analysis and spodumene recovery exceeded 90%. The two-stage circuits were unable to simultaneously yield an acceptable produce with a satisfactory recovery. With the Nation's growing industrial mineral requirements, the U.S. Bureau of Mines has undertaken the task of investigating new mineral dressing techniques and improving the existing concentrating methods of ore beneficiation. One such project is the gravity concentration of minerals using heavy liquid separation (HLS).1-3 Heavy liquid separation is based on the simple principle that a material, whose specific gravity is less than the density of a solution, will float on top of the liquid and a material with a greater specific gravity will sink. Heavy liquid separation techniques were developed in the laboratory over half a century ago but the process has yet to be commercially adopted. In the past, commercial operations have failed because of numerous problems.4 Industrial interest has recently been reactivated because of engineering advances. The number and quality of the heavy liquids suitable for mineral processing has increased while the cost has sharply dropped. New and improved liquid recovery systems5,6 are under consideration with present emphasis on 1) solvent extraction, 2) thermo-evaporation, and 3) water washing. The toxicity of the heavy liquids7 presents a problem, but throughout the chemical and mining industries, many similar hazardous materials are safely handled. A distinct advantage of using heavy liquids is its ability to provide a near perfect separation of fine-sized mineral particles even when the specific gravities are close. Effective separations have been made on minerals down to 200 mesh and with a density

Jan 1, 1968

By J. H. Frye, D. L. McElroy, E. E. Stansbury

The rates of growth of pearlite in high-purity Fe-C alloys have been measured as a function of the transformation temperature. These and other data have been correlated in terms of a derived rate equation. Activation energies for the growth were found to be 24,200 cal per mol of austenite for the 0.78 pct C alloy and 27,600 cal per mol for the 0.93 pct C alloy. Theoretical implications are discussed. AN excellent review of the the theoretical and experimental studies on the mechanism and kinetics of the eutectoid reaction has been presented recently by Mehl and Dube.' They have pointed out that these investigations have followed two lines of approach: 1—experimental studies and derivations of expressions for the overall transformation characteristics, and 2—derivation of expressions for the nucleation and growth rates in terms of fundamental processes. Investigations of the latter type have been concerned for the most part with the nature of the growth at the austenite-pearlite interface in plain carbon and alloy eutectoid steels. They discuss two theories of the rate of growth of pearlite from aus-tenite—those of Brandt and of Zener. Both derive rate equations which are based on the assumption that carbon diffusion is the controlling mechanism. Mehl and Dube,' Zener,2 and Brandts. " have attempted to calculate growth rates by use of these equations together with thermodynamic and diffusion data. The results are encouraging, but agreement is not so good as to constitute verification of the theories. Furthermore, it Is not clear how these equations are to be used to study the effect of alloying elements which apparently exert little influence on carbon diffusion, but markedly decrease growth rates. It is not clear whether or not the addition to iron of an alloying element which does not diffuse during transformation can alter the rate of growth of body-centered from face-centered cubic iron. That it can greatly decrease the overall transformation rate has

Jan 1, 1954

By N. D. Gerald

The mathematical analysis, which is an essential part of this paper, has revealed the interesting fact that contrary to the opinions of many, determinate and measurable economic factors are largely responsible for the price of crude oil. It should, however, be well understood that the results of this analysis are applicable, without qualification, only to the particular period and market studied. There are certain peculiarities of the petroleum industry which make the consideration of its economics very difficult, and at times practically impossible. Noneconomic factors often become highly important and have serious economic effects, which make unqualified predictions based on economic data extremely hazardous and ill advised. However, in spite of the attendant difficulties there are many problems, especially in price analysis, to which approximate solutions must be made for the proper guidance of public and private policy, but their limitations should be kept clearly in mind. An understanding of the nature of prices is of fundamental importance for a number of purposes. Measurement of the motivating factors giving rise to trends and other price movements is essential to forecasting for the intelligent engineering and financial administration of the industry. The fixing of prices, maintenance of an intelligent industrial dictatorship, or the making of other industrial adjustments, demand, for success, an accurate understanding of their probable consequences. The establishment of a system of equitable relations within an industry, or between industries, by methods other than the natural competitive ones, requires a thorough knowledge of the price structures and the nature and trends of the normal and basic prices of their products. This research has shown that in this case, even though the statistical records are only fair, quantitative economics offers a direct and satisfactory approach to the problems of economic consequences dependent on the reactions of mass intelligence. A consideration of commodity prices naturally leads to costs. The true cost of petroleum is so complex and elusive that its accurate deter-

Jan 1, 1934

By AIME

To be born in the East, reared and educated in the West, to do graduate work in Germany, leading to the doctorate in metallurgy, and to wind up-for the time being at least-in the Middle West as head of one of the outstanding mining and engineering schools of the country, is a unique career. Curtis Laws Wilson, dean (and in most respects, president) of Missouri School of Mines and Metallurgy at Rolla, is a native of Baltimore. He came to Anaconda in 1918 and in due course was graduated from Montana School of Mines, with an exceptional record. In 1921, after experience in metallurgical research at Anaconda, he became instructor in metallurgy at his alma mater. Because of his ability as a teacher, he rose rapidly to head of the department after special work at Columbia in 1923-24. In 1927, Wilson was granted leave of absence to study physical metallurgy under the great Tammen at Goettingen, and returned with his doctorate to his work at Montana School of Mines. His major metallurgical interest was then in age-hardening of copper alloys. Also after his return to Montana Mines, Wilson started

Jan 1, 1948

By John Mathews

IT is twenty years since the writer made his first molybdenum steels and others were making them commercially five years earlier but the prevailing opinion seems to be that molybdenum steels are new; from time to time the daily press speaks of important discoveries in Europe and intimates that American steel makers have much to learn in regard to alloy steels. The earlier experiments were largely confined to the use of relatively high percentages of molybdenum in tool steels and permanent magnet steels. Recent developments deal with the types of alloy structural steels used for airplane, automobile, and other engineering requirements; in these, the molybdenum content is usually less than 1 per cent. The earlier types generally have been unsuccessful commercially, but the newer types of steels are becoming of increasing importance. The war showed our dependence on foreign sources for alloying metals; molybdenum alone is widely distributed in the United States and seemingly abundant. Many deposits are not now of commercial interest, owing to location and relatively small amount of ore available, but other deposits are being developed and a stable source of supply seems well assured. In tool and magnet steels, it was early found that 1 part of molybdenum was equivalent to from 2 to 2.5 parts of tungsten. The permanent magnet steels investigated by Madame Curie,1 in 1898, contained from 3.36 to 4.05 per cent. molybdenum; in 1902, Dr. E. L. French and the writer thoroughly tested steels containing from 2:0 to 4.0 per cent. These steels gave satisfactory tests for permanence, but were low in residual density and much more sensitive to hardening than the corresponding tungsten products. We discontinued work with them, therefore, and have no advice that such steels have been used commercially here or abroad.

Jan 2, 1921

By Alan J. Strauss

The Group IV elements germanium, tin, and lead form nine 1:1 compounds with the Group VI elements sulfur, selenium, and tellurium. This paper reviews the properties of the pseudobinary solid solutions formed by these compounds, including the extent of mutual solid solubility, temperature-composition phase diagrams, transport properties, deviations from stoichiometry, optical properties, and energy band structure. Particular emphasis is placed on the Pbl-xSnxTe and Pb1-xSn,Se alloys with rocksalt structure, because of current interest in these malerials for generating and detecting infrared ,radiation. ThE Group IV elements germanium, tin, and lead form nine 1:1 compounds with the Group VI elements sulfur, selenium, and tellurium. Some of the physical and electronic properties of these compounds, including their melting points1-8 and energy gaps,4'9-12 are listed in Table I. Four compounds (SnTe, PbS, PbSe, and PbTe) have the cubic rocksalt (Bl) structure. At room temperature GeTe has a rhombohedra1 structure closely related to the B1 structure, into which it is transformed at about 400°C. Four compounds (GeS, GeSe, SnS, and SnSe) have the orthorhombic B29 structure. In samples which have not been intentionally doped with impurities, the electrical conductivity is due primarily to electrons or holes produced by the ionization of donor or acceptor lattice defects associated with deviations from stoichiometry. Undoped samples of PbS, PbSe, and PbTe may be either n type or p type, depending on whether they contain excess lead or an excess of the Group VI element, respectively, but only p-type samples of the other compounds have been reported. This paper will review the properties of the pseudo-binary solid solutions formed by the nine 1:l compounds. The topics to be considered include the extent of mutual solid solubility, temperature-composition phase diagrams, transport properties, deviations from stoichiometry, optical properties, and band structure. Particular emphasis will be placed on the Pb]-xSnxTe and Pbl-xSnxSe alloys with B1 structure, which are promising materials for generating and detecting infrared radiation in the 8 to 14 µm atmospheric window and beyond. MUTUAL SOLID SOLUBILITY The extent of mutual solid solubility in the pseudo-binary systems has been investigated for fourteen of the eighteen ternary systems (in which the two terminal compounds have a common element) and for nine of the eighteen quaternary systems. In most cases, X-ray diffraction measurements made at room temperature were used to determine the structure and lattice parameter(s) of the phase(s) present in samples of various compositions prepared by freezing from the melt. In many investigations, including the extensive studies of Krebs and co-workers,13'14 the samples were annealed at elevated temperatures before X-ray measurements were made. In some cases, metallographic examination and thermal analysis have also been employed. The results for the ternary and quaternary systems are summarized in Tables II and III, respectively. (The original references should be consulted for the annealing temperatures.) The solubility of one compound in the other is at least 5 mol pct in all cases, and is often much larger. Complete solid solubility has been observed in all systems so far investigated in which the terminal compounds have the same structure, although in the PbS-PbTe system complete solubility is limited to elevated temperatures. Thus complete solid solubility occurs in five systems where both compounds have the B1 structure (SnTe-PbTe, PbS-PbSe, PbS-PbTe at temperatures above 805°C, PbSe-PbTe, and SnTe-PbSe) and in three where both compounds have the B29 structure (GeS-SnS. GeSe-~n~e-, and SnS-SnSe), as well as in two involving GeTe and a compound with B1 structure (GeTe-SnTe and GeTe-PbTe). On the basis of thermal analysis data, complete solid solubility at sufficiently high temperatures has also been reported for the GeSe-GeTe2 and SnS- pbS22 systems. This seems unlikely, however,

Jan 1, 1969

By K. L. Woodruff

The first step in processing municipal solid waste (MSW), principally household waste, for resource recovery is usually shredding. A trommel has been investigated as a step to precede shredding. This way abrasive inorganic materials, such as stones and metals, would be removed prior to shredding, thus lowering the amount of feed and hence maintenance on the shredder. In addition, friable materials such as glass would be removed in large pieces, rather than pulverized too mall to process for recovery. The utility of a trommel for these purposes was investigated on a pilot scale using a unit 9 ft diam by 10 ft long with 4-in. square clear openings. Experimental results indicate that up to approximately half of the MSW may be removed as -4-in. material prior to shredding. The -4-in. fraction contains approximately 70% of the metals and 95% of the glass present in the MSW feed to the unit. Scale-up and cost information necessary for the design of a 60 to 70 tph unit is developed.

Jan 1, 1977

By Claus Guenter Goetzeil

(New York Meeting, February, 1937) The object of this investigation was to determine whether silver alloys could be used instead of the currently employed insert of high-expansion Average Coefficient per Deg. C. over Range 20° to 200° C. Pure aluminum..................................... 24.6 X 10-6 Cast low-expansion Si-Cu-Ni-A1 piston alloy............ 20.0 X 10-6 High-expansion austenitic Cu-Ni cast iron.............. 19.3 X 10-6 Cast steel (0.25-0.35 C, 0.40-1.0 Mn).................. 12.6 X 10-6 Cast iron (3.15 total C, 2.16 Si)....................... 12.8 X 10-6 Pure silver.......................................... 18.9 X 10-6 austenitic ferronickel alloy, to reduce the wear of ring grooves in light metal pistons. A typical example of a piston containing a ferronickel insert is shown in Fig. 1. The high coefficient of expansion of silver made it worthy of consideration, while the small size of the insert would render its use feasible in Germany as an emergency measure. The coefficients of linear expansion of several metals and ailoys are as shown in the table above. Obviously the melting point of the insert must be high enough to prevent it from melting when the light alloy is cast around it. This imposes a lower limit of about 850" C. for the solidus of the silver alloy. Pure silver melts at about 961" C., so that the tolerable depression in the solidus is rather small. To avoid deformation of the insert during use a Brinell hardness number of at least 60 appears necessary.

Jan 1, 1937

A national budget system, which engineers have long regarded as essential to the proper conduct of our fiscal affairs is at last being seriously considered by. Congress and seems likely to be adopted in some form. Several, bills and joint resolutions have already- been introduced but the measure that seems how to attract the 'most attention is H. R. 1201 introduced by. Representative Good, Chairman of the House Committee on Appropriations. This ,bill provides for the creation of a Bureau of the Budget in the office of the President, to which full information shall be furnished by all Departments and other Governmental agencies concerning powers, duties, financial transactions, business method's, etc. A change, is made in the fiscal regulations in that the Departments shall hereafter submit their fiscal estimates to the President instead of to the Secretary of the Treasury, while the latter official shall submit estimates of the public revenues and the condition of the Treasury. Two budgets are, provided for:, The first, or regular, budget shall contain a balanced statement of the resources and liabilities of the Government and the revenues and expenditures, actual or estimated as the case may be, for the preceding, current, and ensuing fiscal years. The President is further, authorized to submit his recommendations as' to how the heeds of the Government should be met, and such further data regarding the financial affairs of the, Government as he deems proper. The second or alternative budget shall make known the essential facts regarding the condition of the Treasury and what, in the opinion of the President. are the revenue, and expenditure needs for the ensuing fiscal year, to be prepared in such form as the President shall deem most appropriate. The bill' abolishes-the offices. of Comptroller of the Treasury and all -the Auditors for the several Departments, and substitutes therefore an Accounting Department, an establishment independent of the Executive Departments, under the direction of newly created officer to be known as the "Comptroller General of the United States" whose powers shall comprise all those now conferred on the Comptroller of the Treasury and the several Auditors and, in addition thereto, the investigation at the seat of Government or elsewhere of all matters relating to the receipt or disbursement of public funds, concerning which report shall be made to Congress at the beginning of each regular session, containing recommendations concerning the legislation deemed necessary to the accurate rendition and settlement of accounts.

Jan 8, 1919

By G. St. J. Perrott

A study of certain fundamental characteristics of liquid-oxygen explosives has been made. A discussion is given of the factors affecting the life of the cartridge and the relation between explosive strength and oxygen content. The explosive properties of L.O.X. cartridges packed with a variety of lampblacks, gas blacks, and other materials have been experimentally determined by means of the ballistic pendulum, Bichel gage, and measurement of the rate of detonation. DURING the past year, the Bureau of Mines has carried on an investigation of liquid-oxygen explosives (L.O.X.) to supplement the work described in previous publications.' The present paper gives results of the first part of this work, which was a laboratory investigation of the properties of typical combustibles used in L.O.X., and the relation of these properties to the absorption and retention of oxygen by the explosives and their explosive characteristics. No attempt will be made to describe the development of liquid-oxygen explosives, because this phase of the subject has been well covered. The L.O.X. cartridge consists of a paper wrapper filled with an absorbent combustible material that is saturated with liquid oxygen by soaking it therein. After saturation, the cartridge is removed from the liquid and fired with fuse and cap, or electric detonator, in a manner

Jan 12, 1924

By Paul A. Farrar, Louis P. Stone, Harold Margolin

The Ti-Mo-0 system was investigated in the region 0 to 45 wt pet Mo and 0 to 10 wt pet 0, from 600° to 1400°C. Solidus data are also presented. Isothermal sections at 700°, 900°, 1100°, and 1300°C, and vertical sections at 1 and 28 wt pet Mo, and 1 and 10 wt pet 0 are included. STUDY of the Ti-Mo-0 system has been carried out as part of a general study of titanium phase diagrams. The binary Ti-Mo system has been investigated in whole or in part by several investigators.1-8 It was found that molybdenum and ß-tita-nium form a complete series of solid solutions and that the ß/a + ß transus is depressed to below 600°C at approximately 30 pet Mo.* The Ti-O system has been investigated partially or fully in the range 0 to 30 pet 0 by several investigators." Extensive solubility of oxygen occurs in the field. While a is

Jan 1, 1957

By Shun-ichi Satoh

In the previous paper, the writer indicated that the arc welding of cast iron is practicable only when barium carbonate is used to retard the fusion of electrodes. Later, he tested the effects of 48 other elements, to discover the cause of their retarding action. Wrought-iron bars 33 cm. long and 0.53 cm. dia. were used as electrodes. The chemical analysis of the original electrode is given in Table 1. Table 1.—Analysis of Electrode Per Cent. Carbon.................................................. 0.045 Silicon................................................... 0.028 Manganese....................................... Trace Phosphorus.............................................. 0.047 Sulfur................................................... 0.008 Each of the bars was wound with a twine of asbestos (1 mm. dia., weighing 0.5 g.) and then was coated with a mixture of equal quantities of graphite and carborundum and one of the compounds listed in the second column of Table 2. The method used in coating was as follows: The mixtures were reduced to paste by adding to them a solution of water glass (1:3); they were next put in a glass tube of 8 mm. inner diameter, with funnel-shaped mouth (the same tube shown in the previous paper); then the bars were passed through the tube so that the mixtures were coated on them. The glass tube was used only as a means of making the diameters of all coated bars exactly 8 millimeters. The cast iron was deposited on the steel plates by connecting the electrodes first to the positive and then to the negative pole of the generator. The figures representing the time, voltage, amperes and energy required to melt each electrode are given in Table 2. They are arranged in the order of the atomic weights of the elements contained in the coatings. In Figs. 1 to 4, which show respectively the time, current, voltage and energy required in this operation, the abscissas indicate the atomic weights of the elements contained in the coatings, and the ordinates

Jan 1, 1929

By R. M. Wilhelm

HIGH-TEMPERATURE thermometry,, as treated in this paper, deals with the measurement of temperature in the range 100° to 550° C. The lower limit corresponds to the temperature of boiling water at normal atmospheric pressure, the upper limit is approximately the highest temperature to which mercury in a glass thermometer may be safely subjected.1 In this range., the domains of pyrometry and thermometry overlap somewhat, for high-temperature resistance thermometers and thermocouples generally classed as pyrometers are often used below 550° C. This paper will be confined to high-temperature mercurial thermometers, and indicating and recording thermometers of the vapor pressure, liquid or gas filled, and bimetallic or graphite-metal expansion types, a classification of which is as follows: CLASSIFICATION OF THERMOMETERS GENERAL CLASSIFICATION SUBDIVISIONS Mercury in glass Laboratory- Etched or engraved stems (mercurial) Enclosed scale (Einschlus) Industrial Vapor pressure Indicating and Pressure Liquid filled recording Gas filled Bimetallic Graphite-metal expansion

Jan 9, 1919

Chairman, MRS. JESSE SCOBEY The Foreign War Relief Committee closed its dispensary fund during the past month with a contribution to the American Fund for French Wounded of $1720.51, balance on hand, principal and interest, as a gift from the New York Section of the Woman's Auxiliary for pressing emergency dispensary work in France. The American Fund for French Wounded was authorized to cable this sun at once, in consideration of the fact that their existing dispensaries, including the one established by the New York Section at Briey, were in excellent condition, while their mobile dispensary fund was confronted by the most urgent need for work among the refugees now returning in pitiable condition and in great numbers to certain distressing centers. The committee sewing at Fund headquarters every week has had seven working days, with an enrollment of twenty: The average attendance was ten; largest attendance for any one day, thirteen; smallest attendance, eight. Interest in this activity is growing steadily and it is the intention of the committee to push the work vigorously for the next few weeks.

Jan 3, 1919

By W. M. Aubrey

Lying approximately 110 miles east of Toronto, Canada, the Marmora mine produces iron ore with a content of about 40 pct Fe, primarily in the form of magnetite. Operated by the Marmoraton Mining Co., a subsidiary of Bethlehem Steel Co., the orebody is mined by open pit methods. The ore from the pit is crushed, cobbed, ground to -100 mesh, magnetically concentrated to 67 pct iron, and then pelletized in shaft furnaces. The pellets are normally shipped by rail throughout the year from Marmora to Picton on Lake Ontario where they are unloaded and stored. Subsequently, during the navigation season, the pellets are shipped to Bethlehem Steel's Lackawanna plant in Buffalo, New York, for use in the blast furnace. At Marmora, the pellet plant demand and the concentrator output are not usually equal. To counter this problem, surge capacity in the form of storage pits in combination with a 30-ft diam thick¬ener has been provided between the concentrator and the pellet plant. Two sets of controls have been installed on this thickener, one controlling the…

Jan 9, 1960

By C. P. Lawhon, J. P. Simpson, W. M. Evans

Recent efforts to design drilling fluids for increased drifting rates have confirmed some laboratory results of other investigators, but have also produced additional data that should be considered. These data were obtained under controlled test conditions using a microbit drilling machine. Clays and some polymers have previously been reported to cause reduction in drilling rate. Recent data have shown that under laboratory conditions, suspensions of a single day or polymer have sometimes given faster drilling rates than when water was used. Measurements have been made of clay suspensions and polymer suspensions comparing filtration (I) under API conditions, (2) while drilling with temperature of 150F and differential pressure of 1,000 psi and (3) under dynamic conditions after drilling. Some correlation between instanraneous filtration (white drilling) and drilling rate has been observed. INTRODUCTION Several papers have been presented that related drilling fluids to penetration rate. Generally, it was found that a decrease in the solids concentration resulted in significant increases in the drilling rate. Of course, this change also resulted in a decrease in the viscosity of the drilling fluid.' Conclusions from investigations by this laboratory are in agreement. Data have shown that of the simple mud measurements commonly made at the drilling rig (density, plastic viscosity. yield point, API filtrate and total solids), only the density and total solids have a significant relationship to the drilling rate in Berea sandstone when attempting to correlate a single mud property individually.' More recent drilling rate experiments have been designed to study (1) effects of individual clays and polymers on drilling rates in Berea sandstone and Lueders limestone, (2) the relationship between drilling rate and dynamic filtration as measured after drilling and (3) the relationship between drilling rate and dynamic filtration as measured during drilling. Data show that drilling rates are dependent upon type and concentration of particles, type of formation and filtration of the individual fluids while drilling. Mud pressure: pressure of drilling fluid as measured after leaving the drilling chamber (Fig. 1). This is taken to be approximately the mud pressure just past the bit and at the face of the formation. Terrastatic pressure: pressure representing weight of overburden. Formation pressure: pressure of formation fluid as measured at outlet of drilling chamber (Fig. 1). This is taken to be approximately the pressure of fluid in the interstices of the formation. Differential pressure: difference between the mud pressure and formation pressure. LABORATORY EQUIPMENT AND TESTING PROCEDURE The drilling equipment was described in two previous publications."' Main components are a drilling chamber, filter-heater, rotary drive and variable-speed circulating pump. Auxiliary pumps supply pressure boosts for the mud, terrastatic and formation pressures. All equipment is designed for 15,000 psi and 500F. Capacity of the circulating system is approximately 7 gal. The mechanical design was facilitated by moving the rock down onto the bit. Data collected with this design should not differ from that obtained by a normal design where the bit moves into the rock. Drilling fluid is pumped through 50 ft of ID pipe coiled in an oil bath, enters the rotary shaft at a right angle and is pumped through the jets on the bit (Fig. 1). Most of the drilled solids are extracted by a screen mounted in the circulating system on the suction side of the pump. Data reported in this paper were obtained by controlling these parameters: mud pressure, 5,000 psi; formation pressure, 4,000 psi; terrastatic pressure, 5,000 psi; force on bit, 1,000 Ib; formation, Berea sandstone and Lueders limestone; flow rate, 7 gal/rnin; bit, 11/4-in. diameter with two 0.078-in jets; mud temperature. 150F; and rotary speed, 60 rpm. Mud pressure was controlled at 5,000 psi, thus giving a differential pressure of 1,000 psi even though the fluid densities varied. Cores of 3%;-in. diameter and 8 in. long were selected from quarry blocks to provide some control of grain size distribution, permeability and porosity. A 2-in. section was cut off each core and a I -in. diameter plug was taken from this section. Permeability to 5 percent by weight sodium chloride solution was determined and the large cores were