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By Randolph C. Specht

A two year study was made of the waste disposal of the pebble rock phosphate industry. Solid slimes are impounded in large settling areas and the process water is re-used. Clear effluent was not found to be toxic to fish or animal life in field tests or in controlled experiments. Survey: The pebble rock phosphate mining and washing operations in Florida (fig. 1) are along the river basins of the Alafia to the west and the Peace to the east. The elevation of the area varies between 40 and 170 ft above sea level. Effluents from the operations find their way into one of the two river systems (fig. 2), the Peace River which flows into Charlotte Harbor and the Alafia into Tampa Bay, both along the Gulf of Mexico. There are no major industries along these rivers below the phosphate operations. On the Peace River, the town of Arcadia, approximately 50 miles below the phosphate operations, obtains its water from the river. No other communities along the rivers use them as a source of water supply. Small communities, farms, and ranches are located along the rivers and both rivers drain vast swamp areas. Complaints had been received at the office of the Chief Sanitary Engineer, of the Florida State Board of Health,' that both rivers were turbid at various times and that fishing in the Alafia River was "not as good as it used to be." Tests made by another agency on the dissolved oxygen content of the Alafia River revealed that the oxygen content, at times, was comparatively low.= However, it was not shown that the phosphate wastes had any effect upon the oxygen content of the stream. The river waters are normally brown in color due to drainage from vast swamp areas and are very shallow, from 2 to 6 ft in depth. Turbid waters have been noted in streams coming from the present phosphate operations and also from streams along which there are no operations at the present time. It was learned from "old timers" that, when many more companies than at present were operating along both the Alafia and Peace Rivers forty or fifty years ago, no attention was paid to prohibiting the disposal of slimes along the river basins. During dry periods now in some of the river swamps where drainage ditches have been dug, it is indicated clearly that phosphate slimes were disposed of directly into the river swamps for many years past. Places have been observed where there were alternating strata of phosphate mud, leaf mold, and quartz sand. The former practice of indiscriminate disposal of wastes accounts for some turbidity, particularly after heavy rains and washouts and during clearing of land and digging of drainage ditches. During a six months' period in which a large tract of land was being cleared and drainage ditches dug, a small stream (Six Mile Creek), which previously had been clear, showed a turbidity of 600 ppm and remained turbid until the clearing was completed; after which the stream again flowed clear. An interview with the operator of the municipal water plant, which is about 50 miles below the phosphate operations on the Peace River and which used this river as a source of supply, revealed that there had been no taste in the water for the past ten years, other than that occasionally encountered from increased growth of algae. The operations of each of the cooperating com-

Jan 1, 1951

By Randolph C. Specht

A two year study was made of the waste disposal of the pebble rock phosphate industry. Solid slimes are impounded in large settling areas and the process water is re-used. Clear effluent was not found to be toxic to fish or animal life in field tests or in controlled experiments. Survey: The pebble rock phosphate mining and washing operations in Florida (fig. 1) are along the river basins of the Alafia to the west and the Peace to the east. The elevation of the area varies between 40 and 170 ft above sea level. Effluents from the operations find their way into one of the two river systems (fig. 2), the Peace River which flows into Charlotte Harbor and the Alafia into Tampa Bay, both along the Gulf of Mexico. There are no major industries along these rivers below the phosphate operations. On the Peace River, the town of Arcadia, approximately 50 miles below the phosphate operations, obtains its water from the river. No other communities along the rivers use them as a source of water supply. Small communities, farms, and ranches are located along the rivers and both rivers drain vast swamp areas. Complaints had been received at the office of the Chief Sanitary Engineer, of the Florida State Board of Health,' that both rivers were turbid at various times and that fishing in the Alafia River was "not as good as it used to be." Tests made by another agency on the dissolved oxygen content of the Alafia River revealed that the oxygen content, at times, was comparatively low.= However, it was not shown that the phosphate wastes had any effect upon the oxygen content of the stream. The river waters are normally brown in color due to drainage from vast swamp areas and are very shallow, from 2 to 6 ft in depth. Turbid waters have been noted in streams coming from the present phosphate operations and also from streams along which there are no operations at the present time. It was learned from "old timers" that, when many more companies than at present were operating along both the Alafia and Peace Rivers forty or fifty years ago, no attention was paid to prohibiting the disposal of slimes along the river basins. During dry periods now in some of the river swamps where drainage ditches have been dug, it is indicated clearly that phosphate slimes were disposed of directly into the river swamps for many years past. Places have been observed where there were alternating strata of phosphate mud, leaf mold, and quartz sand. The former practice of indiscriminate disposal of wastes accounts for some turbidity, particularly after heavy rains and washouts and during clearing of land and digging of drainage ditches. During a six months' period in which a large tract of land was being cleared and drainage ditches dug, a small stream (Six Mile Creek), which previously had been clear, showed a turbidity of 600 ppm and remained turbid until the clearing was completed; after which the stream again flowed clear. An interview with the operator of the municipal water plant, which is about 50 miles below the phosphate operations on the Peace River and which used this river as a source of supply, revealed that there had been no taste in the water for the past ten years, other than that occasionally encountered from increased growth of algae. The operations of each of the cooperating com-

Jan 1, 1951

By P. W. Guild

DURING 1956 the application of geology and related scientific disciplines to the search for new mineral deposits went forward on an ever widening front. Spurred on by record-breaking consumption of many of the established commodities and new uses for minerals and metals that were hardly known a few years ago, the profession is figuratively leaving no stone unturned in the effort to insure that adequate raw material supplies will be avail- able for the future. More money was spent and more people were engaged along more lines of research than ever before. A huge project to map much of the Canadian Shield area by photogeologic methods stands at one extreme; application of isotope ratios to ore finding stands at the other; between them the more traditional techniques are being increasingly refined. In the Fiftieth Anniversary volume of Economic Geology, published late in 1955, Alan Bateman sketches the development of fundamental concepts as recorded in the pages of the journal over the first five decades. An additional 24 review articles cover individual aspects of the field and constitute a base for further advances.

Jan 2, 1957

By G. B. Sazuyer

DEVELOPMENTS respecting beryllium during the past year have been sufficient to center attention on it as likely to be the most important of any of the chemical elements that have recently found a place for themselves in technical industry. This importance is only potential, however, largely because adequate supplies of beryllium ore will be necessary. The beryllium industry will be only as great as the mines which support it. To find and develop large mines will be the problem. Chief of the immediate commercial developments in the United States is beryllium-copper and its espousal by Anaconda and Riverside even at present high prices. According to the pamphlets of these companies, it ap¬pears that beryllium is to copper nearly what carbon is to iron. When one considers that the tensile strength of pure copper is about 33,000 lb. per sq. in., but that the addition of 1.5 to 2.5 per cent of beryllium produces a heat-treatable alloy with a maximum tensile strength of 220,000 lb. or over, the analogy to carbon and iron is made strikingly, clear. Striking among the properties of beryllium-copper is its resistance to fatigue, claimed to be equal or superior to that of spring steel. It needs little imagination to foresee a great industry for this alloy alone.

Jan 1, 1934

By Alfred R. Powell

Late in 1944 a group of petroleum and coal technologists was organized in Washington under the sponsorship of the Petroleum Administration for War and the U. S. Bureau of Mines. This group, known as the Technical Oil Mission, was placed under the authority of the Technical Industrial Intelligence Committee of the Joint Chiefs of Staff, which was then promoting the organization of other missions to be sent to Germany to obtain technical information regarding various industries in that country. The objective of the Tehnical oil Mission was to obtain technical data on German production of synthetic oil from coal and all other commercial practices and research projects connected with the oil industry. The primary purpose was to obtain such data as were immediately essential to assist the war against Germany and Japan, with secondary emphasis on technical information that would assist American industry after the end of the war. since oil-production facilities in Germany and the occupied countries controlled by Germany were the top targets for strategic bombing, the Technical Oil Mission was the first group under the Technical Induslrial Intelligence Com,mittee to enter Germany. A few members of the group flew to London in February 1945 and the majority of the remainder followed in March. In London they were joined by an equal number of British investigators and the combined mission was then sent into Germany under the authority of the Combined Intelligence Objectives Subcommittee (CIOS). A summary of the more important information gained by this combined British and American mission is presented below. German Oil Production The oil available to Germany, both natural and synthetic, and including production from occupied countries, reached a peak in late 1943 and early 1944 Production at this time was at the rate of 1,200,000 metric tons Per month, equivalent to 100,000,000 bbl. per year, or about 7 per cent of the wartime production in the United States. Of this production, jo per cent was crude oil from Romania and Hungary, 12 Per cent was crude oil from Germany itself, including Austria, 9 per cent cumprised coal-carbonization products, that is, tar and light oil, and only the remaining 29 per cent was synthetic liquid fuel made from coal or tar. Synthetic liquid fuel made in Germany was equivalent therefore to less than 2 per cent of wartime production of crude oil in the United States. The success of the strategic bombing campaign against German oil-production facilities is demonstrated by the fact that by September 1944 the Ploesti fields of Romania and much of the syrlthetic oil production had been eliminated, so that the amount of oil available to the German war machine was only 25 per Cent of the peak qualltity mentioned above. By early 1945, when the combined British and American oil mission was entering

Jan 1, 1947

By Alfred R. Powell

Late in 1944 a group of petroleum and coal technologists was organized in Washington under the sponsorship of the Petroleum Administration for War and the U. S. Bureau of Mines. This group, known as the Technical Oil Mission, was placed under the authority of the Technical Industrial Intelligence Committee of the Joint Chiefs of Staff, which was then promoting the organization of other missions to be sent to Germany to obtain technical information regarding various industries in that country. The objective of the Tehnical oil Mission was to obtain technical data on German production of synthetic oil from coal and all other commercial practices and research projects connected with the oil industry. The primary purpose was to obtain such data as were immediately essential to assist the war against Germany and Japan, with secondary emphasis on technical information that would assist American industry after the end of the war. since oil-production facilities in Germany and the occupied countries controlled by Germany were the top targets for strategic bombing, the Technical Oil Mission was the first group under the Technical Induslrial Intelligence Com,mittee to enter Germany. A few members of the group flew to London in February 1945 and the majority of the remainder followed in March. In London they were joined by an equal number of British investigators and the combined mission was then sent into Germany under the authority of the Combined Intelligence Objectives Subcommittee (CIOS). A summary of the more important information gained by this combined British and American mission is presented below. German Oil Production The oil available to Germany, both natural and synthetic, and including production from occupied countries, reached a peak in late 1943 and early 1944 Production at this time was at the rate of 1,200,000 metric tons Per month, equivalent to 100,000,000 bbl. per year, or about 7 per cent of the wartime production in the United States. Of this production, jo per cent was crude oil from Romania and Hungary, 12 Per cent was crude oil from Germany itself, including Austria, 9 per cent cumprised coal-carbonization products, that is, tar and light oil, and only the remaining 29 per cent was synthetic liquid fuel made from coal or tar. Synthetic liquid fuel made in Germany was equivalent therefore to less than 2 per cent of wartime production of crude oil in the United States. The success of the strategic bombing campaign against German oil-production facilities is demonstrated by the fact that by September 1944 the Ploesti fields of Romania and much of the syrlthetic oil production had been eliminated, so that the amount of oil available to the German war machine was only 25 per Cent of the peak qualltity mentioned above. By early 1945, when the combined British and American oil mission was entering

Jan 1, 1947

By O. E. Palasvirta

Close examination of most so-called new processes in mineral dressing reveals that they were conceived and developed a long time ago. High-intensity magnetic separation is no exception. Although its application in iron ore beneficiation seems new, in Germany the process has been commercially successful for almost two decades. High-intensity separators have long been standard equipment in the glass sand industry; they have also been used in concentrating some of the more unusual paramagnetic minerals. The basic features of an induced-rotor, high-intensity magnetic separator were described by Désiré Korda in Paris in 1905,1 and many patents have since been issued for improvements on the original design. Fig. 1 shows the basic design of an induced-rotor separator. Several U. S. manufacturers have been supplying induced-rotor separators for many years, but these are all devices of relatively low capacity, not suitable for treating such low-cost commodities as iron ore. On the other hand, two German manufacturers are offering induced-rotor separators of high capacity, both proven in the field.

Jan 12, 1959

By John K. Hammes, Stanley D. Michaelson

Generally, the mining costs reported for the large open-pit operations in the United States and South America lie within the range of $0.20 to $0.30 per ton of material moved. (These operations have strip- ping ratios ranging from 1.5 to 4.0.) Productivities for the larger North American properties are in excess of 200 tons of material per man shift, while those for the South American operations are less than 200 tons per man shift. The most significant variations in cost are in the categories of haulage and general mine cost. Haulage costs vary, as expected, according to the mine elevation, pit profile, crusher location, and accessibility of a dump area, and general cost variations depend largely on the overhead cost items included in this category. Drilling and Blasting Practice The majority of open-pit copper mine production drilling is performed by rotary drills. Hole diameter varies from 6 in. to 12 in., with 9-in. holes being most common, and penetration rates vary from 35 ft to 60 ft per hour.

Jan 1, 1968

By J. B. Cheatham

An analysis of indexing is given for an idealized plastic rock. Indexing refers to chipping from a bit tooth to a previously formed crater. A method is indicated for computing the dependence of chip size and shape as well as force on the tooth for various tooth shapes as a function of crater configuration and distance to the previous crater. Pressure on the tooth is found to vary with depth of penetration after a critical depth has been reached. Damp sand model experiments indicate that simple solutions using linear and logarithmic spiral slip-line fields for Coulomb plastic materials give reasonable approximations to the failure patterns. Both idealized roller cone bits and fixed blade or drag bits are considered, and methods are presented for approximating the force on the bit and the chip volume when the rock is subjected to sufficiently high pressure to behave plastically. One of the primary objectives of drilling research investigations is to develop theoretical equations which can be used to predict the behavior of rock under drilling loading conditions. Since rocks usually fail in a brittle manner at atmospheric conditions, much current research is directed to studies of the brittle failure of rock under the action of drilling too1s. 1,2 The results of triaxial test on rocks indicate that both rock strength and ductility increase at high confining pressures.3 Recent results from single bit-tooth indentation experiments on dry rocks indicate that the transition from brittle to ductile failure under a bit tooth can occur at pressures sufficiently low to be of interest in oil well drilling.4 Single bit tooth experiments and analyses are not directly applicable to the drilling process since one of the important facets in drilling is the interaction between a bit-tooth and the previously formed crater. This interaction is referred to as indexing.' The purpose of the present paper is to indicate how plasticity theory can be applied to the analysis of indexing for plastic rock. Drag bit or fixed-blade drilling is considered and a discussion is given of the drilling action of an idealized roller cone bit. Results of simple experimental studies using a damp sand model are given as a method of visualizing the failure patterns in rocks under high confining pressures. These results are compared with plasticity theory using simple solutions based on linear and logarithmic spiral slip-lines. Discontinuous stress fields are proposed for drag bit drilling based upon the soil mechanics analysis of Shields. SINGLE BIT TOOTH RESULTS Single bit tooth indentation experiments using dry rocks under pressures from 0 to 5000 psi have indicated a correlation between the shape of a force-displacement curve and the nature of the rock failure beneath the tool.4 Continuous linear curves are in-

Jan 1, 1965

By Arthur E. Focke

IF a metallurgist employed in an industry producing mechanical parts or assemblies wishes to make the most of his opportunities he will be concerned with every use of metals in that industry. He will not only take part in the testing and treating of the metals used but will assist in their selection and study their behavior in processing and in service. In addition, he will attempt to develop an understanding of the problems involved in the use of the metals in all plant tools and equipment. Metallurgists that follow this course will soon recognize that frequently too little thought is given to the effect of the design of parts on the way the metal in them is expected to behave in service. He will come to realize that changes in the design of a part will often be much more useful than changes in the hardness, strength, composition, or structure of the metals used in them. Does this mean that a metallurgist is out of place in these industries and that he should leave the field to others or be content to fill only a minor role?

Jan 1, 1947

By M. F. McCarty, R. S. Olson

New organic flocculants of high-molecular weight are replacing lime, glue, and starch in liquid-solid separation. Of these synthetic materials, poly-acrylamides are outstanding. Polyacrylamides form a class of compounds varying widely in composition and activity. Separan 2610, one of the first of these flocculants' released to the mining industry in 1954, is described' as a high-molecular weight polymer of acrylamide with or without a copolymer material and with some replacement of amide by carboxylic groups. MECHANISM OF FLOCCULATION In practice, flocculation makes solids settle faster and filter better. But two opposing factors control it. The random motion that causes particles to collide favors Van der Waals' forces, which hold the particles together. The effect of zeta potential opposes this contact, and particles are mutually repelled. Flocculation can be achieved by reducing the magnitude of the zeta potential; this is the mechanism of flocculation by lime addition. The way in which polyacrylamides accomplish flocculation is not fully understood, but the action is undoubtedly comp1ex and probably varies considerably depending on the system. To begin with, the active groups of these compounds have an extremely high affinity for solid surfaces, probably by hydrogen bonding." Initially some active groups of the molecule attach themselves to the solids with a large portion of the molecule extending into the solution. Two particles can become tied together by long flocculant molecules in the following ways—by bonding between the active groups of two flocculant molecules on different particles, or by an extended molecule from one particle attaching itself directly to the surface of the other particles." These flocculant bridges prevent the particles from moving apart through random motion, but when such motion moves them together other active groups on the flocculant bridge bond to the solids, holding them in the closer position. This process is repeated until the particles are close together. Although bridging is probably a major flocculation mechanism, it is not the only phenomenon involved. Relatively neutral acrylamide flocculants reduce the magnitude of the zeta potential by increasing the viscosity of solution in the immediate vicinity of the solid surface which contains the mobile counter ions of the double layer. In other words, it moves the shear surface which bounds the zeta potential out into the solution containing counter ions which tend to neutralize the zeta potential. This effect is probably more pronounced during the initial adsorption period, before the flocculant molecules are pulled close to the solid. In some cases the slight charge of the polyacry-lamide molecule tends to neutralize a zeta potential. However, this is not a primary flocculation mechanism, as evidenced by the fact that the polyacrylamides will flocculate solids with either positive or negative zeta potential. Adsorption of polyacrylamide flocculants by a solid is substantially an irreversible reaction. Since the flocculant molecule is attached to the particle surface by many active groups of high bonding strength, desorption would require the simultaneous breaking of many bonds—an unlikely occurrence. UNIQUE PROPERTIES The irreversible adsorption of certain polyacrylamides, the flocculant's high affinity for solid surfaces and its rapid adsorption make it effective, but these unique properties require special techniques to achieve maximum flocculation. If flocculants of this type are added to a pulp as a relatively concentrated solution, the solids in the

Jan 1, 1960

By K. G. Davis

Dilute alloys of silver and of thallium in tin have been solidijzed unidirectionally under controlled conditions, to study the segregation associated with a cellular interface under conditions where both thermal and solute convection are present. Autoradiography and radioactive tracer counting techniques were combined with electron-probe microanalysis to study both macro- and microsegregation. It was found that, for concentrations giving only small amounts of constitutional supercooling, cell formation had little effect on the macroscopic distribution of solute along the specimen. At higher concentrations the effective distribution coefficient was higher than that expected for a smooth interface. Node spacing was independent of initial solute content at lower concentrations, becoming greater as keff increased. Silver content at the segregation nodes of silver in tin alloys was independent of initial concentration and considerably in excess of the eutectic composition. SINCE the investigation of cell formation at advancing solid-liquid interfaces by Rutter and Chalmers,' a large volume of work has been dedicated to the determination of solidification conditions under which a planar interface will break down into cellular form. Early experiments were explained satisfactorily by the concept of constitutional supercooling,2 but, due to poor measurement of temperature gradients in the liquid, lack of accurate data on liquid diffusion and equilibrium distribution coefficients, and uncertainty about the effects of thermal and solute convection, these experiments cannot be used as proof for the theory. More recent work, however, has shown that under conditions where convection is eliminated or can be ignored good correlation is observed.3,4 Investigations into segregation at cell caps5 and at cell nodes6-'' have been made, but no measurements appear to have been done on the overall, macroscopic segregation down a unidirectionally solidified rod of material which has solidified with a cellular substructure. This has practical importance in casting, where regions of material with cellular substructure are often encountered, and also in zone refining where the thermal conditions necessary for a planar interface are unattainable. Further, as will be shown, the macroscopic segregation can give information on the following question. Granted that a cellular solid-liquid interface develops from a planar one when the conditions for constitutional supercooling are exceeded, how much supercooling is present after the cells have formed? EXPERIMENTAL PROCEDURE AND RESULTS Specimen Preparation. Specimens 25 cm long with a square cross section 0.6 by 0.6 cm were grown in graphite boats by solidification from one end. Alloy compositions are given in Table I. Two specimens of each composition were grown. The tin was 5-9 grade and the silver and thallium both 4-9 grade. Ag110 and Tl204 were used as tracers. Each composition had the same quantity of tracer so that auto radiographs of specimens containing different concentrations of the same element could be easily compared. Thermocouples inserted through the lid of the boat into a dummy specimen showed that, over the first 10 cm of growth, thermal conditions were quite steady, with a rate of interface advance of 5.8 cm per hr and a temperature gradient in the melt ahead of the interface of 3.0°C per cm. The specimens were seeded from tin crystals of a common orientation to eliminate orientation effects. Dilution of the specimen by seed material was minimized by the provision of a narrow neck between specimen and seed crystal. Macrosegregation. After growth, the specimens were sectioned with a spark cutter. The rods of silver alloy were cut into 1-cm lengths and analyzed for Ag110 using a y -ray counter with fixed geometry. The specimens containing thallium were cut into 2-cm lengths and analyzed for T1 204 by taking 13 counts from each end of the cut lengths through an aperture in lead sheet approximately 0.4 cm square. The results are summarized in Figs. 1 and 2. To find the effective distribution coefficient for the silver in tin alloys under smooth interface conditions, the region of substructure at the bottom surface of one of the 10 ppm specimens, see Fig. 3, was removed by spark machining before counting. Autoradiography. For both alloy systems the samples were polished on sections taken alternately parallel and perpendicular to the growth direction, and autoradiographed by placing the polished surfaces in contact with Kodak "Process Ortho" film. Figs. 3 and 4 show the structures revealed. The alloy containing 10 ppm Ag showed substructure only after a few centimeters of growth, and then substructure was limited to a narrow layer at the base. The "speckled" substructure reported previously in this system4 is here clearly seen to be an intermediate stage between planar and cellular interface conditions. The other samples show a remarkable similarity considering

Jan 1, 1969

By B. Thomas Mansbach

INTRODUCTION The Overseas Private Investment Corporation ("OPIC") is a U.S. Government agency mandated to promote the economic development of the less developed countries ("LDCs") by assisting U.S. private investment in the Third World. Generally, investment decisions turn on the optimism or pessimism of the private sector's financial analysis of a project, with market price of product a major unknown in a very chancy set of projections. Discussions with American mineral companies, however, show that, more often than not, in developing country projects it is the political risks of investing in mineral exploration and extraction that pose the most serious deterrent to investment. In several of the projects described here, investments would not have been made if OPIC had not been involved providing support to the project sponsors and their funding sources. Clearly it is not OPIC's business to promote U.S. investment in a project which is not commercially viable, but OPIC's programs can neutralize the political uncertainties which act as disincentives to investment in otherwise commercially viable projects. That is to say, OPIC's programs are designed to reinforce market decisions and not distort them. Although OPIC is an independent agency of the U.S. Government, it is managed by a Board of Directors, the majority of whom come from the private sector. This, coupled with the statutory requirement that it be self-sustaining and operate with due regard for the principles of prudent risk management, requires that it operate on a business-like basis. Although established as a development agency, to the business public OPIC is both an insurance company and a lending institution, with two major programs which are available to U.S. investors in the minerals sector: its political risk insurance program and its finance program. Each has been specially tailored to the meet needs of the mining industry. The insurance program provides coverage against four basic types of political risk: Currency Inconvertibility, Expropriation, loss caused by War, Revolution and Insurrection and Interference with Operations as a result of an act of War, Revolution or Insurrection. Coverage against the risks of Civil Strife can be added to both War, Revolution and Insurrection coverage and Interference with Operations. Inconvertibility coverage provides protection against a deterioration in an investor's ability to convert local currency into U.S. dollars. This deterioration can be the result of either active or passive delays. Active delays consist of a change in exchange laws or regulations that leads to inconvertibility delays of 30 days or more. For example, if the exchange regulations at the time of contract execution allow an investor to transfer earnings equal to 18% of its registered capital per annum and the government of the host country later changes the law to allow conversion of only 12%, the insured would convert the 12% transferable under the new exchange regulations with the government foreign exchange authorities, delivering the remaining 6% to OPIC for conversion at 99% of the then prevailing rate of exchange. (OPIC does not cover devaluation risks.) Upon delivery of the local currency to OPIC, normally at the U.S. Embassy in the project country, the insured's account in the U.S. would be credited with dollars. Delays can also result from what is termed passive blockage, which includes administrative delays of more than 60 days (sometimes longer) caused by the bureaucratic tie-ups or pigeonholding of transfer requests, as well as delays suffered simply because the government of the host country does not have sufficient foreign exchange. The transfer procedure is the same as with active blockage - the local currency is delivered to OPIC in the project country and OPIC provides dollars in the United States at the then prevailing rate of exchange. The second coverage -- Expropriation -protects not only against the loss of the investment due to the well-known risks of expropriation, nationalization or confiscation by the host government, but also against

Jan 1, 1985

By Alfred E. Hunt

The technical papers of the last few years give numerous in stances of serious failures by cracking or rupture of soft steel boiler plates, marly of which have satisfactorily passed the rigid inspection and tests required by both Lloyds' Register and the Board of Trade in England. I speak of the inspecting department of Lloyds' and the Board of Trade, for we do not begin to have as systematic and intelligent work regularly done in this country as is done by these institutions in England. Tension-tests of this steel have given from 65,000 to 65,000 pounds per square inch tensile strength, with from 20 to 30 per cent. elongation in 8 inches. Chemical analyses have shown the steel to contain from 0.12 to 0.15 per cent. carbon, from 0.25 to 0.40 per cent. manganese, and from 0.03 to 0.05 per cent. phosphorus. All of these tests are considered normal, and, in the words of one of our members, " boiler-plates with these qualities ought not to fail." There are, however, several causes of failure in soft steel plates which, although the writer does not presume to ascribe to then], or either of them, any particular instance, are still dangerous, and ought to be guarded against much more carefully than in usual present practice. These causes are: 1. The hardening property of all steel. 2. Insufficient work from the ingot to the finished plates. 3. Temporary fiber in certain steels. 4. Internal strains caused by unequal work upon the material. Hardening.-The writer, in a paper read before the Institute in October, 1883," made the statement that soft .steel, no matter how low in carbon, would harden to a certain extent upon being heated red-hot and plunged into water, and that it hardened more when plunged into brine and less when quenched in oil, and gave the results of one experiment, merely as an illustration of many which had all confirmed the statement made. The illustration was a heat of open-hearth steel made by the . writer, of 0.15 per cent. carbon and 0.29 per cent. of manganese, which gave (he following results upon test-pieces from the same 1/4-thick plate.

Jan 1, 1886

By Walter Miller

Crude oil stocks were some 10,000,000 bbl higher on June I, 1947, than at any time during 1946 but the extremely heavy refinery runs the last half of 1947 cut crude inventories to approximately the 1946 closing level of 225,000,000 bbl. Many refiners were seriously short of crude oil during the year. This shortage was reflected in numerous advances in the posted price of crude, justified in part as an incentive for more production but more generally due to competitive bidding. Some purchasers of crude, endeavoring to keep their plants running, resorted to the payment, either directly or indirectly, of premiums above the posted price. Another common practice employed by some suppliers of crude oil was to demand refined products in exchange or trade for their raw material. The refined products picture has darkened in spite of record throughputs. Stocks of gasoline and light and heavy fuel oils were uncomfortably low at the beginning of the year and were in general still lower at the close. The rationing of some products, principally gasoline, to dealers and stations? initiated during the year, gained momentum as stocks continued to diminish. The emphasis placed by the manufacturers of oil-burning equipment on the convenience and economy of heating with oil, together with the tight situation in coal, has developed a tremendous demand for burning oils. Consumption of liquefied petroleum gas for domestic and household fuel had more than doubled in 1946 over 1943, and the demand seems to be limited only by the ability of the equipment builders to furnish necessary storage. transportation, and burning equipment. The supply situation is likely to become more acute in 1948. Demand for petroleum products is being pushed to new heights not only by the unprecedented domestic market but by a sudden and drastic upswing in estimates of military and governmental requirements. Additionally, oil exports are running far below the volume requested, amounting to less than forty percent in a recent quarter, and export licenses are reportedly being approved on the basis of urgent need *only. AX recent White House release sees little likelihood that estimated requirements of the sixteen nations participating in the proposed Marshall Plan can be met in full over its projected life—1948 to 1951. Present demand dictates maintenance of refinery operations at the highest possible level and the Bureau of Mines has forecast daily average crude runs in 1948 of 5,265,000 bbl. The Economics Advisory Committee of the Interstate Oil Compact Commission recently estimated the 1948 demand for petroleum products at nearly 6 pct above 1947. They further estimate daily average crude runs of 5,375,000 bbl in 1948, some 2 pct higher than forecast by the Bureau of Mines. Projected demand exceeds supply to the extent that Capitol Hill is reportedly investigating ways of enabling oil companies to act in concert without danger of antitrust prosecution, such as elimination of crosshauls, pooling of products, and lowering of octane.

Jan 1, 1948

By Walter Miller

Crude oil stocks were some 10,000,000 bbl higher on June I, 1947, than at any time during 1946 but the extremely heavy refinery runs the last half of 1947 cut crude inventories to approximately the 1946 closing level of 225,000,000 bbl. Many refiners were seriously short of crude oil during the year. This shortage was reflected in numerous advances in the posted price of crude, justified in part as an incentive for more production but more generally due to competitive bidding. Some purchasers of crude, endeavoring to keep their plants running, resorted to the payment, either directly or indirectly, of premiums above the posted price. Another common practice employed by some suppliers of crude oil was to demand refined products in exchange or trade for their raw material. The refined products picture has darkened in spite of record throughputs. Stocks of gasoline and light and heavy fuel oils were uncomfortably low at the beginning of the year and were in general still lower at the close. The rationing of some products, principally gasoline, to dealers and stations? initiated during the year, gained momentum as stocks continued to diminish. The emphasis placed by the manufacturers of oil-burning equipment on the convenience and economy of heating with oil, together with the tight situation in coal, has developed a tremendous demand for burning oils. Consumption of liquefied petroleum gas for domestic and household fuel had more than doubled in 1946 over 1943, and the demand seems to be limited only by the ability of the equipment builders to furnish necessary storage. transportation, and burning equipment. The supply situation is likely to become more acute in 1948. Demand for petroleum products is being pushed to new heights not only by the unprecedented domestic market but by a sudden and drastic upswing in estimates of military and governmental requirements. Additionally, oil exports are running far below the volume requested, amounting to less than forty percent in a recent quarter, and export licenses are reportedly being approved on the basis of urgent need *only. AX recent White House release sees little likelihood that estimated requirements of the sixteen nations participating in the proposed Marshall Plan can be met in full over its projected life—1948 to 1951. Present demand dictates maintenance of refinery operations at the highest possible level and the Bureau of Mines has forecast daily average crude runs in 1948 of 5,265,000 bbl. The Economics Advisory Committee of the Interstate Oil Compact Commission recently estimated the 1948 demand for petroleum products at nearly 6 pct above 1947. They further estimate daily average crude runs of 5,375,000 bbl in 1948, some 2 pct higher than forecast by the Bureau of Mines. Projected demand exceeds supply to the extent that Capitol Hill is reportedly investigating ways of enabling oil companies to act in concert without danger of antitrust prosecution, such as elimination of crosshauls, pooling of products, and lowering of octane.

Jan 1, 1948

By L. P. Teas

The year 1931 has been one of unusual interest in Gulf Coast petroleum development, not so much because of the number of new prospects discovered, for apparently none of any present distinction have been found, but because of the discovery of so many new oil fields and the proving of so many old prospects. During the year 10 new oil fields have been found on the Coast; five in Louisiana and five in Texas. Two suspected salt domes were proven by the drill. Production dropped from a daily average of 192,000 to 162,670 bbl., or an average of 58 bbl. for each producing well, and active operations from 189 to 119. During 1931 the Coast produced approximately 48,600,000 bbl., or 44 per cent less than in 1930, when 86,500,000 bbl. were produced. The daily return at the beginning of the year was $192,000 and at the end only $126,780, the price having dropped from $1 for A grade and a range of $0.75 to $1.22 for B grade to a price range of 70 to 86c, or an average of 78c $ per barrel at the end of 1931. The average Coastal well produced 17,400 bbl. of oil during 1931. During the year development in the old fields has continued active at Barber's Hill only, although some work is in progress at Humble, Pierce Junction, Refugio and Pettus. Clear Lake is active but the large ownerships will prevent the "boom" type of field. Production is being held fairly steady at Barber's Hill and Pierce Junction, but has declined rapidly during the year at Refugio, Humble, and to a lesser degree at Pettus. The 6000-ft. production at Barber's Hill has shown a decided drop during the year and has not measured up to expectations.

Jan 1, 1932

By J. F. Gormley

Drill pipe, and the connections used to join the pipe together, have had a long history of development and improvement. With the growing use of high tensile-strength pipe, the rotary shouldered connections used to join the lengths of drill pipe have become more critical. Fatigue-type failures of rotary-shouldered connections, or tool joints, have become a cause of much conern to operators and manufacturers. Most fatigue tests on tool joints have been made on the basis of bending moment applied vs number of cycles, rather than on the basis of stress vs cycles. A desire to learn more about the nature of stress in a tool joint due to bending caused a rather intensive experimental study to determine what actually happens to cause fatigue failure. It was known that a tool joint with insufficient make-up torque was subject to early fatigue failure. Therefore, the establishment of the relationship between make-up torque and allowable bending moment would enable a testing engineer to better correlate the results of various tests. The problem of calculating the stress in a tool joint due to an applied bending moment was complicated by: the effect of unknown stress concentrations; the applicability of the well known formula S = Mc/I; and the question of whether to use the combined cross section of the pin and box in calculating the moment of inertia I. TEST EQUIPMENT The test equipment consisted of the following. 1. A lathe modified to act as a fatigue machine for full-size tool joint or drill-collar specimens. 2. An adapter plate bolted to the headstock of the lathe and into which a short adapter was screwed. 3. Tool-joint pins on sections of drill collars bucked into the adapter. 4. A hydraulic load cylinder which rested on the bed of the lathe and applied bending moments to the joints. 5. Paper-backed strain gauges (FAP-12-12, 1/8-in. gauge length and A-5-1, 1/2-in. gauge length). 6. Eastman 910 contact cement for bonding gauges to joint and Epoxylite 222 waterproofing. 7. A 12-position switchbox, SR-4 bridge balancing unit connected to an SR-4 strain indicator to read the gauge output. 8. A four-channel Sanborn recorder, Model 150, was used as the readout instrument for part of the testing. The fatigue machine was well suited as a loading device. Because of the long lever arm available, the change of moment with distance was small; consequently, the vertical shear stress was small, less than 300 psi. Some difficulty was experienced with the hydraulic load cylinder at high bending moments due to leakage. The strain gauge equipment was simple and quite reliable. A 41/2-in. extra hole (E. H.) joint with "as machined" threads and shoulders and a 2 7/8-in. internal flush (I. F.) joint with copper-plated threads and shoulders were selected for testing because of their common usage in the field. In addition, the 4 1/2-in. E. H. was suitable because it had an inside diameter large enough to permit the insertion and accurate positioning of strain gauges without using special jigs, while the 2 7/8-in. I. F. joint required much lower bending loads to cause separation of the shoulders of the joint when made up to the recommended torque. The joints were made to standard API specifications, except for very small bevels on the box and pin shoulders and cylindrical stress-relief grooves added to the pins. Larger bevels would have

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who registered at Institute headquarters during the period Oct. to Nov. 10, 1915: Lester S. Thompson, New York, N. Y. Arthur L. Sweetser, Boston, Mass. William Reed, El Oro, Mexico. Dorsey A. Lyon, Salt Lake City, Utah Heinrich Ries, Ithaca, N. Y. D. W. Blaylock has resigned his position with the St. Joseph Lead Co., Bonne Terre, Mo., and has accepted the position of division engineer for the Big Creek Coal Co., of Chicago, at Harrisburg, Ill. R. B. Lamb announces the removal of his office to Room 1809, 43 Exchange Place, New York, N. Y. C. C. Sanders has taken a bond and lease on the Red Mountain group of 34 mining claims (copper), Patagonia, Ariz., and has commenced extensive development.

Jan 12, 1915

By L. A. Panek

Research on roof bolting has developed significant information with respect to the functions that can be performed by properly installed bolts and the methods that can be used to ensure that effective installation has been achieved. The present paper brings together results that are pertinent to the design of a bolting system for reinforcing horizontally stratified mine roof with vertical bolts. The design approach is based on the use of bolts to decrease the maximum bending stress within an arbitrary sequence of roof strata (see Fig. 2) in which the only loads are the weights of the individual beds. The use of rock bolts to achieve other objectives, such as to stabilize a fractured rock mass on the periphery of a mine opening,3 is excluded from consideration herein. Reinforcing effect of bolts consists of a friction effect and a suspension effect in combination. "Friction effect" refers to reduction of bending in a stratified roof due to clamping action of tensioned bolts, which compress the strata, thereby creating frictional resistance to displacement along planes of stratification. (The flexure of a sequence of strata is necessarily accompanied by horizontal displacement of each bed with respect to its neighbor, along mutual surfaces of contact.) Although the sliding of the beds tends to exert a shearing effect on the bolts, tests show that this has negligible influence on the bending stresses, probably because the bolts are so far apart. "Suspension effect" refers to the transfer of part of the weight of the weaker or thinner strata to one or more thick strata, which occurs when strata with differing tendencies to deflect are constrained to have equal deflection. The term "suspension" is used irrespective of whether the thin strata are above or below the thick strata, because tests show that the supporting effect of the flexurally more rigid roof strata is for practical purposes independent of their position in a bolted sequence of strata. An earlier paper4 dealt with a bolted unit in which all strata had equal flexural rigidity; bolting could develop a friction effect but no suspension effect. The present paper deals primarily with a bolted unit in which all strata do not have equal flexural rigidity, so that bolting can develop both a friction effect and a suspension effect. The reinforcing effect of the bolts was determined by a combination of experimental and theoretical stress analysis.4'6'7 The experimental method consisted of loading a model by rotating it in a centrifuge to simulate the gravity forces exerted about an underground excavation. Models were made from two different limestones, although the results are independent of the material because the elastic constants were taken into account in the data analysis. Electric resistance strain gages were bonded to the highest and lowest members of the bolted unit to determine the outer-fiber bending strains at the center and at the supports. The quantitative results presented herein are based on tests of 56 different models, which included a range of values for the structural parameters. Each model was tested several times, with different combinations of spacing and tension of the bolts. DESIGN EQUATIONS The effects of friction and suspension on the flexure of a bolted stratified roof can be expressed by the following equations, which give the maximum bending stress, the deflection, the friction effect, the suspension effect and the transferred load for any (the i-th) member of the bolted unit in terms of the structural parameters:

Jan 1, 1964