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By N. Mungan, F. W. Smith, J. L. Thompson

Adsorption of polymers and transport, rheology and oil recovery efficiency of their solutions were studied in the laboratory to evaluate the use of polymers in waterflood-ing. While a tenfold mobility reduction was obtained with polymer concentrations as low as 0.05 per cent by weight, the mobility reduction depended on the type of polymer, molecular weight, salinity and pH of water, crude oil and capillary properties of the porous media. Choice of a suitable polymer and a workable concentration will have to be tailored for each application. Little reduction in the residual oil saturation can be expected from polymer flooding. Improvement in the volumetric sweep efficiency is possible hut the extent of the improvement can best be evaluated by properly designed field testing. Some aspects of the field use of polymer floods are discussed. INTRODUCTION Waterflooding is a simple, inexpensive secondary recovery method and is being used widely. Innumerable laboratory studies have been made to unravel the fundamentals of the displacement of oil by water and to find the ways of most efficient oil recovery. These studies and a great many field case histories have revealed that the prime cause of poor oil recovery is the inefficient and incomplete sweep of reservoir volume by the injected water. Sweep efficiency is affected by many factors of which the mobility ratio is an important one. Mobility ratio M is defined here as the ratio of water to oil mobilities: M = (k»/y,r)/(k,JJJJ........(1) In Eq. I, the permeabilities are the effective permeabilities and depend on fluid saturations and, hence, change during the different depletion stages in a flood. A wide practice is to use the effective water permeability at residual oil saturation and the effective oil permeability at interstitial water saturation in Eq. 1. If the mobility ratio is greater than one, the mobility ratio is unfavorable and water, being more mobile than oil, would finger through the oil zone resulting in poor oil recovery efficiency. If the mobility ratio is favorable (one or less) the displacement of oil by water occurs more or less in a pistonlike fashion. In some waterfloods. the mobility ratio is unfavorable and any additives by which the mobility of water can be decreased would favor more efficient oil recovery. The thing to bear in mind, however, is whether or not the improvement in oil recovery is sufficient to more than pay out the cost of the additives needed. For example, materials like sugars, alcohols and glycerine reduce water mobility by thickening the water, but the cost of material requirement precludes any field application. For an additive to be useful in water-flooding, it must bring about a large reduction in water mobility at low concentrations; it must be adsorbed only negligibly; and it must not completely plug up the formation. Some synthetic organic polymers have shown promise of meeting these requirements and have been used in the field.'-W owever, no in-depth studies of the rheological, adsorption and oil displacement characteristics of polymer solutions have been reported. The present work is a study of these properties. EXPERIMENTAL In this work, concentrations are given on a weight per volume basis; 0.5 per cent concentration means 0.5 gm of polymer is dissolved in enough water (or NaCl solution) to make 100 ml. A bactericide, usually 0.1 to 0.2 per cent by volume of 38 per cent formaldehyde solution, was used in the polymer solutions. The NaCl solution was 30,000 ppm. Some properties of the polymers studied are given in Table I. Physical properties of all cores used are in Table 2. Flow behavior of polymer solutions was studied by three consecutive flow tests in cores. First, water (or brine) was injected at constant rate of about 1 ft/D to obtain the water mobility. Then, filtered polymer solution (prepared in water or brine) was flowed through the core. Since the rate was constant, increase in the pressure drop across the core reflects decrease in the mobility. Finally, the core was flooded with water (or brine) to study recovery of mobility. The Alundum cores which were used in

Jan 1, 1967

By R. Bakish, M. A. Badiali, N. W. Kirshenbaum

One pound of ultra pul-e molybdenum has been produced containing both metallic and nonmetallic impuvities close to or less than the limits of detection. various purification methods were investigated; althouglz the use of move than one purification step was consideved, it was found that a single, caefully-controlled sublimation of MoCl5 yielded a highly puvified product without prior treatment or recourse to repeated sublimation. Hydrogen reduction of MoC1, to metal was attempted at atmospheric pressure; however, reduced pressure was necessary to obtain substantial yields. The tubular deposits of metal were consolidated into bulk fovm by electron beam melting undev high vacuum yielding a very low gas content. Boblems involved in monitoring the puvity of these materials and analytical results obtained are also presented. THE pronounced effect of even trace amounts of impurities upon fundamental properties of materials is well known to metallurgists and solid-state physicists. Consequently, groups interested in basic studies of metals have in recent years immensely stimulated the preparation and production of numerous ultra-pure metals. Increased demand by scientists for these high purity materials has necessitated development of facilities to prepare them in significant quantities; the procedures reported here were devised to produce significant quantities of ultra-pure molybdenum. Previous work performed in the field of vapor phase purification and hydrogen reduction of several other refractory metal chlorides had demonstrated valuable techniques applicable to molybdenum.' Various purification and reduction steps were individually investigated. Those procedures which showed the most favorable results with respect both to attainment of high purity and to ease of operation were then incorporated in the process utilized to produce the metal.' STARTING MATERIALS It is well known that because of differences in volatility, chlorides may be separated by fractional distillation. It was presumed that distillation of molybdenum pentachloride offered a simple and straightforward method of purification due to its relatively low boiling point. Alternatively, sublimation of the solid chloride also appeared feasible since MoC15 has both a reasonably narrow temperature range in which it exists as a liquid (a property typical of refractory metal chlorides) and a low enthalpy of sublimation. Pertinent thermochemical data of MoC15 are given in Table I. It should be noted that this compound must be handled with care as it is extremely hygroscopic. Anhydrous MoC15 was obtained from the A Metal Climax Co. METHODS OF PURIFYING MOLYBDENUM PENTACHLORIDE Distillation. It was expected that distillation methods, while affording an efficient purification, would prove simple to control and would have a higher production rate than sublimation processes. Also considered was the possibility of effecting a high degree of purification by using both these volatilization methods in conjunction—possibly a distillation followed by sublimation of the solidified condensate. Distillation of MoC15 was investigated using a single stage distillation column packed with chemically resistant glass beads. Heating coils were wound around the column and collection tube (condenser). As-received MoCl5 was charged into a flask connected with the column using a side loading arm under an argon flow. After the column and condenser were brought to about 270" and 210°C, respectively, the apparatus was lowered until the flask was fully immersed in a constant temperature fused salt bath maintained at about 285 °C. Distillation was continued for about 10 or 15 min until 50 to 70 g of distillate had been collected. Analyses of these distillations indicated that several elements, e.g., Cu, Fe, Ni, Cr, and Mg, were lowered in quantity although not all were removed to the same extent. The occurrence of Na, B, Si, and A1 in the distillates appeared to be due to contamination, possibly from corrosion of the pyrex glass. An improved distillation system of larger capacity and longer distilling column was built. Improvements were effected in lowering the amounts of such impurities as B, Mn, Ni, Na, Mg, Cr, Cu, and Fe. These studies were pursued concomitantly with efforts to purify by sublimation; it was subsequently found that although improvements in purity were obtained by distillation, sublimation processes were simpler to control and effected a high degree of purity.

Jan 1, 1963

By John S. Johnson

The purpose of this article is to describe several types of borehole lining in common use, and especially to offer a relatively new means of reducing the expense of maintaining boreholes where they are subjected to corrosive action of water flowing either inside or outside of their casing. In the Anthracite region of Pennsylvania, boreholes are used for many purposes, the principal ones being: openings between the surface and underground workings through which are passed steam, water and compressed-air lines, ropeways from surface hoists to underground rope haulages, conduits for electric power and signal lines, water-discharge lines from underground pumping stations, and inlets to mine workings for flushing material. Linings for Boreholes The inadequacy of steel pipe for use in boreholes has long been recognized. Various substitute materials have been tried, including screw-joint cast-iron pipe (Fig. I). Cast-iron pipe, while very effective as a discharge line for acid water (mine water) being pumped to the surface, is not so effective when serving as a conduit for silt and crushed rock being flushed underground for filling mine voids. Terra cotta pipe (Fig. 2) has been used in boreholes, and lasts a long time if the glazed inner surface of the pipe remains intact. Its installation in a borehole is very difficult and is recommended only where it is certain that there will be no subsidence of the surrounding territory. Accessibility in order properly to join each section of the pipe is essential to a satisfactory job. In large water holes, where it is possible to lower a man into the hole for sealing the joints of the pipe, glazed terra cotta pipe has been used successfully for delivering mine water from pumps in the mines. For large holes used for flushing refuse into mine workings where the surface wash is shallow, standard paving brick have been used to form a tube through the wash to the bedrock. These brick are laid radially, backed by common brick and cobbles laid in cement. It is obvious that the shaft through the wash must be large enough to permit a man to work in it. The flushing material is carried through bare rock from the juncture at bedrock to the openings underground. This plan has been used particularly where a cast-iron surface line is laid upon the surface to carry the flushing material from the breaker to the hole, and down the hole continuously, with no opening to the air at the top of the hole, thereby eliminating the necessity of an attendant at this point (Fig. 3). Another similar type of borehole lining is constructed of hexagonal pieces of vitrified brick (Fig. 4). This type requires a steel drive pipe through the surface wash large enough to provide a finished tube of the desired size surrounded by a brick wall about 4 in. thick. The special bricks are laid in cement, six to a circle, around a lubricated pipe used as a form, and lowered in sections inside the large drive pipe; the bottom section is seated in a socket drilled in the solid rock, having the same inside

Jan 1, 1942

By John S. Johnson

The purpose of this article is to describe several types of borehole lining in common use, and especially to offer a relatively new means of reducing the expense of maintaining boreholes where they are subjected to corrosive action of water flowing either inside or outside of their casing. In the Anthracite region of Pennsylvania, boreholes are used for many purposes, the principal ones being: openings between the surface and underground workings through which are passed steam, water and compressed-air lines, ropeways from surface hoists to underground rope haulages, conduits for electric power and signal lines, water-discharge lines from underground pumping stations, and inlets to mine workings for flushing material. Linings for Boreholes The inadequacy of steel pipe for use in boreholes has long been recognized. Various substitute materials have been tried, including screw-joint cast-iron pipe (Fig. I). Cast-iron pipe, while very effective as a discharge line for acid water (mine water) being pumped to the surface, is not so effective when serving as a conduit for silt and crushed rock being flushed underground for filling mine voids. Terra cotta pipe (Fig. 2) has been used in boreholes, and lasts a long time if the glazed inner surface of the pipe remains intact. Its installation in a borehole is very difficult and is recommended only where it is certain that there will be no subsidence of the surrounding territory. Accessibility in order properly to join each section of the pipe is essential to a satisfactory job. In large water holes, where it is possible to lower a man into the hole for sealing the joints of the pipe, glazed terra cotta pipe has been used successfully for delivering mine water from pumps in the mines. For large holes used for flushing refuse into mine workings where the surface wash is shallow, standard paving brick have been used to form a tube through the wash to the bedrock. These brick are laid radially, backed by common brick and cobbles laid in cement. It is obvious that the shaft through the wash must be large enough to permit a man to work in it. The flushing material is carried through bare rock from the juncture at bedrock to the openings underground. This plan has been used particularly where a cast-iron surface line is laid upon the surface to carry the flushing material from the breaker to the hole, and down the hole continuously, with no opening to the air at the top of the hole, thereby eliminating the necessity of an attendant at this point (Fig. 3). Another similar type of borehole lining is constructed of hexagonal pieces of vitrified brick (Fig. 4). This type requires a steel drive pipe through the surface wash large enough to provide a finished tube of the desired size surrounded by a brick wall about 4 in. thick. The special bricks are laid in cement, six to a circle, around a lubricated pipe used as a form, and lowered in sections inside the large drive pipe; the bottom section is seated in a socket drilled in the solid rock, having the same inside

Jan 1, 1942

By Douglas A. Karvonen

INTRODUCTION Although the economy in the Province of Saskatchewan has historically been agriculturally oriented, a major source of wealth has been realized through natural resources such as petroleum and natural gas, coal and uranium and since the 1960's - potash. Potash or potassium chloride, in the form in which it is presently produced in Saskatchewan, is used primarily as fertilizer, a source of potassium, one of three essential elements required for healthy plant growth, with about 5% of production sold to the chemical industry for use in such products as soap and liquid detergent, glass and ceramics, textiles and some pharmaceuticals. Saskatchewan is estimated to have approximately 40% of known world potash reserves and its ten active mines account for some 25% of annual world production. POTASH CORPORATION OF SASKATCHEWAN In an effort to guarantee a fair and lasting economic benefit to the Province of Saskatchewan, the Potash Corporation of Saskatchewan (PCS) was created on February 4, 1975 through an Order-in-Council under the Crown Corporation's Act and later on April 1, 1976, the Potash Corporation Act provided for its continuation. PCS was given the mandate to acquire ownership of a significant portion of the potash mining capacity in Saskatchewan and to establish an organization capable of operating the facilities, marketing the product, and conducting all of the other activities necessary for a successful corporation competing in the world potash industry. The corporation is the largest potash producing and selling organization in the Western World - or third largest in the world. (See also Figure 1). PCS through its wholly-owned subsidiary, PCS Mining, has acquired a whole or partial interest in five geographically distinct producing properties or divisions, representing today more than 40% of Saskatchewan's potash producing capacity. The acquisition of each division was followed by a program designed to exploit and maximize the particular opportunities at each minesite for increased production. To that end, PCS Mining has taken an active lead in expanding to meet future demand and has implemented expansion programs at all properties except for its Esterhazy Division where it has a long-term processing agreement with International Minerals & Chemical Corporation (Canada) Limited. Through its wholly-owned subsidiaries, PCS Mining, PCS Sales and PCS Transport, this provincial crown corporation has the ability to operate as a producer and marketer of Saskatchewan's potash. In certain instances PCS, the parent company, assists in the financing of various projects undertaken by the subsidiaries and in other cases the subsidiary involved arranges its own financing. POTASH RESERVES As a background to the specific issue of financing, it is helpful to describe briefly the nature of the deposit which supports the industry - our collateral, if you like. The potash beds underlying Saskatchewan are sedimentary rock deposits formed by the gradual evaporation of an inland sea during the Middle Devonian period roughly 400 million years ago. Now known as the Prairie Evaporite, this formation stretches from North Dakota and Northeast Montana through Southern Saskatchewan into North-Central Alberta. These beds lie at mining depths ranging from 950 - 1000m (3,000 ft) below the surface, where conventional mining methods can be used, and to 1,650m (5,000 ft), where solution mining must be

Jan 1, 1985

By Nicholas J. Grant, David S. Bloom

An investigation of the Cr-Ni system has revealed that there exists a eutectoid transformation at about 1180°C. 'The transformation in chromium implied by the eutectoid reaction was detected at about 100°C below its melting point. Associated with the eutectoid transformation, a metastable transition structure has been found. THE Cr-Ni phase diagram is shown in current literature to be a simple eutectic system in which the high chromium end of the diagram is incompletely determined, Fig. 1. The last investigation of this system was undertaken in 1936.' Because of limitations in metal purity, especially of chromium, and temperature measuring techniques, the diagram should be accepted with some reservations, as was indicated by Hansen.V or examwle.-, the wresence of the compound Cr²Ni, with a tetragonal structure," remains unverified and incompatible with the simple eutectic diagram. The work reported here began because of discrepancies that appeared in experimental studies in the binary alloys Cr-Ni and in the ternary system Cr-Mo-Ni. The existing binary Cr-Ni diagram failed to provide a complete explanation of observations made by microscope, X-ray, and thermal analyses. Experimental Methods The materials employed were of a higher degree of purity than were available to previous investigators. The Mond nickel used had a nominal purity of 99.87 pct, while the electrolytic chromium analyzed 99.03 pct with the major impurity being 0.5 to 0.7 pct oxygen with some iron. All alloys were melted in a vacuum furnace to remove dissolved gases, sufficient carbon was added to the charge to combine with all the oxygen as CO. Final analysis determined the carbon as about 0.02 pct and the oxygen around 0.06 pct or slightly more. Stabilized zirconia crucibles and thermocouple protection tips were used throughout and contributed no detectable impurity to the melts, as long as the oxygen in the chromium was kept low. Heats averaged about 250 g, which permitted about 2 in. of the thermocouple protection tips to be submerged. The temperature drop across the thermocouple protection tip was determined to be about 3°C, a minor source of error. The alloys, after removal from the vacuum furnace, were placed in a furnace operating in a purified argon atmosphere for the thermal analyses. An- nealed wolfram-molybdenum thermocouples provided the primary means of temperature determination, though a Pt-Pt-10 pct Rh couple was employed for a check when possible. A sensitive, high-speed Leeds and Northrup Speedomax recording potentiometer indicated the thermocouple output. X-ray diffraction patterns were obtained primarily on a Norelco unit, which permitted diffraction angles only up to 45" (28 = 90"). In general, either rotated or stationary solid samples were used, because it later evolved that many samples were susceptible to transformation resulting from the cold working involved in pulverizing. It was also noted that rotating a sample sometimes suppressed weak lines, so, usually, samples were not rotated. Later a high temperature camera was adapted for use at temperatures up to 1400 °C on the Norelco unit utilizing both solid and powdered samples. Unless otherwise noted, all X-ray patterns were made with a chromium tube and a vanadium filter. Further-

Jan 1, 1952

By Louise Barton Freeman, Iley B. Browning, Coleman D. Hunter

During 1942, production of oil in Kentucky reached a total of 4,169,163 bbl. of which 1,807,809 bbl. came from eastern Kentucky. This was more than a million barrels less than in 1941, owing partly to the low price of crude oil, which almost eliminated wildcatting, and partly to spacing regulations, which limited the number of wells drilled in small, shallow pools where the pressures are not sufficient to maintain maximum recovery in widely spaced wells. In eastern Kentucky much of the oil was produced from outliers of the Mauch Chunk series at the disconformable contact of the Mississippian and Pennsylvanian. Although wells producing from this horizon, known as the Maxon, are sprinkled over the entire area, the greatest concentrations are in Martin, Floyd, Knott and Pike Counties. A new 30 to 40-bbl. well has been completed in this formation in ,Pike County, where the carbon ratio is so high that ordinarily oil would not be expected. Pike County is one of the largest producers of Maxon gas, and the offset well to this oil well produced gas. Of the 412 gas wells drilled in Pike County, 12.2 per cent produced gas from the Maxon horizon. During 1942, the old Menifee " Cornif-erous" field, the Mariba-Denniston field, was redrilled between old wells, and although it did not produce any large amount of oil it did contribute 2018 bbl. In the oldest oil field in eastern Kentucky, the Ragland pool, operators are cleaning out abandoned wells and are using this oil for fuel oil. There is a possibility that some of this may be used in the future as distilled fuel oil. Eight wells were completed in 1942 in the Jackson County gas field. The development of Jackson County, which was started in 1934 and in which commercial quantities of gas were encountered at a depth of 1100 to 1200 ft., has become of importance in 1942 with the completion of eight wells, making a total of 24 commercial producing wells with an average rock pressure of 140 lb. At this time the gas is not being marketed. In the last year it has been found that these wells, which produce from the Niagaran dolomite ("Cornif-erous"), respond to acidizing and the production has been thus greatly increased. There has been less development in Estill and Lee Counties than for several years. Two wells were drilled in Greenup County, one of which had a show of oil in the Berea sandstone. One deep test, drilled by the Owens-Libbey-Owens Co. in Lawrence County, was dry. This well was drilled to a depth of 4975 ft. into the top of the Clinton shale sequence. Of the 202 wells completed in Floyd, Martin, Knott and Pike Counties, 187 were gas wells, 3 oil wells and 12 dry holes. In Floyd County 66 per cent of the gas production was from the Devonian-Mis-sissippian black shales, 53 per cent in Martin, 79 per cent in Knott and 65 per cent in Pike. This is probably the largest continuous gas field east of the Mississippi

Jan 1, 1943

By Iley B. Browning, Louise Barton Freeman, Coleman D. Hunter

During 1942, production of oil in Kentucky reached a total of 4,169,163 bbl. of which 1,807,809 bbl. came from eastern Kentucky. This was more than a million barrels less than in 1941, owing partly to the low price of crude oil, which almost eliminated wildcatting, and partly to spacing regulations, which limited the number of wells drilled in small, shallow pools where the pressures are not sufficient to maintain maximum recovery in widely spaced wells. In eastern Kentucky much of the oil was produced from outliers of the Mauch Chunk series at the disconformable contact of the Mississippian and Pennsylvanian. Although wells producing from this horizon, known as the Maxon, are sprinkled over the entire area, the greatest concentrations are in Martin, Floyd, Knott and Pike Counties. A new 30 to 40-bbl. well has been completed in this formation in ,Pike County, where the carbon ratio is so high that ordinarily oil would not be expected. Pike County is one of the largest producers of Maxon gas, and the offset well to this oil well produced gas. Of the 412 gas wells drilled in Pike County, 12.2 per cent produced gas from the Maxon horizon. During 1942, the old Menifee " Cornif-erous" field, the Mariba-Denniston field, was redrilled between old wells, and although it did not produce any large amount of oil it did contribute 2018 bbl. In the oldest oil field in eastern Kentucky, the Ragland pool, operators are cleaning out abandoned wells and are using this oil for fuel oil. There is a possibility that some of this may be used in the future as distilled fuel oil. Eight wells were completed in 1942 in the Jackson County gas field. The development of Jackson County, which was started in 1934 and in which commercial quantities of gas were encountered at a depth of 1100 to 1200 ft., has become of importance in 1942 with the completion of eight wells, making a total of 24 commercial producing wells with an average rock pressure of 140 lb. At this time the gas is not being marketed. In the last year it has been found that these wells, which produce from the Niagaran dolomite ("Cornif-erous"), respond to acidizing and the production has been thus greatly increased. There has been less development in Estill and Lee Counties than for several years. Two wells were drilled in Greenup County, one of which had a show of oil in the Berea sandstone. One deep test, drilled by the Owens-Libbey-Owens Co. in Lawrence County, was dry. This well was drilled to a depth of 4975 ft. into the top of the Clinton shale sequence. Of the 202 wells completed in Floyd, Martin, Knott and Pike Counties, 187 were gas wells, 3 oil wells and 12 dry holes. In Floyd County 66 per cent of the gas production was from the Devonian-Mis-sissippian black shales, 53 per cent in Martin, 79 per cent in Knott and 65 per cent in Pike. This is probably the largest continuous gas field east of the Mississippi

Jan 1, 1943

By J. Trevor Eyton

This paper addresses some of the financial risk hedging mechanisms available to a corporation contemplating entering the mining business at a significant level of investment. The approach which I have adopted is that of a case study relating to the risk hedging aspects of Brascan Limited's acquisition of 46% of Noranda Inc., formerly Noranda Mines Limited, followed by some remarks on options open to mining companies for reducing financial risks. To appreciate the rationale for Brascan committing over (Can.) $800 million to the natural resource sector, some knowledge of Brascan's parent company, Edper Investments Ltd., is required at the outset. Edper Investments, prior to acquiring a 48% interest in Brascan, controlled Trizec Corporation, one of the world's largest property companies. Edper also was involved in the financial services sector through Continental Bank of Canada and Hees International Corporation. For some considerable time prior to Edper's investment in Brascan, Edper felt a need to provide a better balance to its portfolio of property and financial services. Brascan was rich in cash, relatively unleveraged, and with important existing holdings in natural resources and consumer products. The acquisition of a controlling interest in Brascan provided an opportunity to balance Edper's portfolio of property and financial services with world class acquisitions in natural resources, supplemented by consumer products and financial services. The end result of Brascan's activities over the last few years is illustrated by the following analysis of the book value of Brascan's assets at the end of December 1983. [Can.$% Millions _ Natural Resources81748 Consumer Products 654 38 Financial Services 157 9 Other Operations895$1,717100% ] Source: Brascan 1983 Annual Report. The large emphasis on natural resources came about from the fact that for Canadians operating mainly in Canada, natural resources were attractive. We were impressed by Canada's position in the world natural resource industry as illustrated by some of the following statistics: [CommodityCanadian Estimated Production In 1983 As % of World Total Newsprint 30 Potash 21 Uranium 18 Molybdenum 17 Zinc 17 Pulp 16 Nickel 16 Saw Logs 11 Silver 8 Copper 7 Lead 6 Gas 5 Oil3] Source: U.S. Bureau of Mines and Brascan estimates. In addition, the quality of Canada's reserves looked good to us. The polymetallic nature of many of Canada's orebodies offered a hedge against risk relating to any one metal. Put another way, the by-product metal credits offered a net operating cost advantage with respect to many of the metals mined. Our energy costs also appeared to provide Canada's natural resource industries with an advantage. We considered Canadian mining expertise as amongst the world's finest, as were the exploration equipment and technology developed in Canada. In addition, Canada offered a stable political climate and one we knew. Further, we felt the Canadian Government's future role in the industry would, on balance, be benign, partly because the Canadian content of the mining industry was very high in contrast to the petroleum industry. Granted, we could find cheaper sources of copper; however, to do so would involve venturing into regions where country risks were higher.

Jan 1, 1985

By Edward E. Hicke, Charles A. Stickels

The dihedral angle of liquid-lead inclusions in solid nickel has been measured as a function of temperature from 371 to 816 C at zero pressure. and as a function of pressure up to 50,000 psi at 317 and 593 C. Thermodynamic expressions are derived for the temperature and pressure coefficients of interfacial tensions in this system. A method is presented for obtaining relative tempmature and pressure coefficients from dihedral-angle data, and the resulting values are used in conjunction with the thermodynamic relations to calculate excess properties of the solid-liquid interface. Defining the position of the solid-liquid interface by the condition that the excess concentration of lead is zero, the excess concentration of nickel and the excess entropy at the solid-liquid interface are: where y(593) is the interfacial tension of the nickel grain boundary saturated with lead at 593C and zero pressure. These values are considered reliable to within a factor of two. While similar calculations are not possible for the nickel grain boundary, it is shown that the expwimental results imply that the excess concentration of nickel at the boundary and the excess entropy of the boundary are negative. THE temperature and composition dependencies of interfacial tensions in metal systems have been reported by several authors in the last 15 years.'-' No measurements of the effect of pressure on inter- facial tensions in metals have been reported, although measurements made on nonmetallic gas/liquid and liquid/liquid systems suggest that a measurable effect should exist.6-l2 The purpose of these experiments was to determine the influence of temperature and hydrostatic pressure on dihedral angles in the Pb-Ni system. The equilibrium dihedral angle is expressed as a ratio of interfacial tensions by2: where 8 is the dihedral angle, yGB is the Ni-Ni grain boundary tension, and SL is the solid Ni-liquid Pb interfacial tension. Three sets of ex- periments were run to determine: a) the effect of temperature from 371" to 816°C on the dihedral angle at zero pressure; b) the effect of pressure up to 50,000 psi on the dihedral angle at 371° and 593°C. THERMODYNAMICS The properties of interfaces of most direct concern are the interfacial tension, excess concentrations of various components at the interface and the excess entropy of the interface, S°. These quantities are defined following Gibbs. Consider an interface separating phases a and 0. Construct two surfaces C, and C such that all properties of phase a remain uniform up to C, and all properties of phase 0 remain uniform up to C. The region between C, and Cp is the interfacial region. Let a "dividing surface", D, be constructed in the interfacial region such that it passes through all points "similarly situated with respect to the condition of the adjacent matter."l3 Surface D divides the interfacial region into a portion a' adjacent to phase adjacent to phase . Let a closed curve, C, enclose an area A in D. Erect normal lines to D along C; these lines and the surfaces C,, Cp, and D then enclose volumes V and V' in the two halves of the portion of the

Jan 1, 1964

By John T. Galey

A combination of two factors in addition to the current Federal drilling and price regulations reduced by 120 from I942 the number of new wells completed in southwestern Pennsylvania during the year. No new prospective area was found comparable to the Armbrust gas pool, Westmoreland Co., which accounted for a seventh of the last year's drilling, and it is considered doubtful whether, even if such a field had been discovered, the drilling contractors, who have been seriously affected by the manpower shortage, could have drilled many more wells than they did during the year. New wells totaling 445 were completed for a combined footage of over 1,250,000 Dry holes numbered 131 and had a footage of nearly 400,000. Old wells drilled deeper total 55, of which 17 were found nonproductive. Shallow Development Oil Oil completions yielded an initial of only slightly over one hundred barrels from 21 wells for about the same per well average as that of a year ago. However, 65 bbl. of this total came from two wells in two new strikes. The footage drilled of nearly 33,000 gives an average of nearly I00 ft. less per well than a year ago. Two old wells drilled deeper had a combined initial of only 4 bbl. The largest oil well of the year, 40 bbl., was found in the Speechley (U. Dev.) sand at a depth of 3492 ft. in German township, Fayette County. The location is several miles east of the nearest oil production hut as the area that could be occupied by a pool is fairly well delimited by drilling, the extent of this production would not appear to be large. The other notable oil production was found in the Dunkard (Penna.) sand, Cumberland township, Greene County, at a depth of 1065 ft. Here the first well had an initial of g bbl. and the second 25 bbl. However, a third proved dry, and as this area is also delimited by drilling, the pool doubtless will be of small area. Gas Gas completions yielded an initial of slightly over one hundred million cubic feet per day and new wells, totaling 303, account for all but four million of this volume. Old wells drilled deeper, numbering 35, found gas. The per well average in new drilling of approximately 320 M cu. ft. is nearly 165 M cu. ft. less than a year ago and the total footage is slightly over 830,000, which is about a quarter of a million feet less than in 1942. Average rock pressure of new completions is approximately 365 lb. per sq. in. The entire volume of new production is from the Upper Devonian or higher stratigraphic horizons. In Allegheny County, the grestest activity was in Forward and Plum townships. Wells there account for more than one half the completions. One large well was drilled in Forward township and an open flow of 3.623 million cubic feet was found in an old Gantz (U. Dev.) sand area. The top of the sand was encountered

Jan 1, 1944

• Pellets of concentrated iron ore have been smelted in the blast furnace by Armco and the results proved satisfactory. Various percentages of pellet burdens were tried and it has been found that charges up to 70 pct pellets are workable. •In the reorganization of the Department of the Interior, two new assistant secretaries were appointed and the work divided between the four assistant secretaries. C. Girard Davidson will head a division of mineral resources including the Bureau of Mines, Geological Survey, Division of Oil and Gas and Division of Geography. •Germanium, one of the rarest of metals and a wartime strategic material, has been discovered almost in the shadow of the Capitol. The only catch is that the scattered nature of the deposits makes profitable recovery extremely doubtful. Nevertheless, experts have tabbed the concentration in the District of Columbia area the world's second richest known concentration of the element. • Cakes of mica, weighing up to 500 lb, have been formed at the Colorado School of Mines by a new "cool hearth" method. The process avoids use of crucibles and contains the molten mica in a basin of unmelted raw mixture from which the melt was derived. Crystallization takes place in this melting basin which forms a center pool surrounded by a solid cool mass of the unmelted raw mixture. • William 1. Baxter, of the International Economic Research Bureau, predicts a period of deflation because of war-essential restrictions on consumer credit and materials use. He stated; "the recent prosperity was based mainly on the sales boom in autos, homes, and household accessories." •Two subsidiaries of United States Steel have decided to build four new ships immediately to augment iron ore and limestone carrying capacity on the Great Lakes to meet demands created by the national defense emergency. •The Norfolk and Western Railway is making a complete change over to coal to drive its locomotives. •A national roster of scientific personnel similar to the one used in the last war will be established by the Office of Education, by agreement with the National Security Resources Board. The new unit, the National Scientific Register Project, will make studies of the Nation's scientific manpower supply and recommend steps to increase the numbers of skilled personnel where needed. •National Lead Co. will start construction immediately of new facilities at St. Louis, Mo., for production of titanium pigments for paints. Producers of titanium pigments have been under considerable pressure to meet all demands from paint manufacturers, particularly for titanium dioxide. •The basic criteria for deferment of reservists in civilian occupations are (1) the Department of Labor List of Critical Occupations, and (2) the Department of Commerce List of Essential Activities, both of which were announced Aug. 3. Fundamentally, the reservist deferred must be engaged in a critical occupation which is necessary to a highly essential activity, and he will be deferred only until he can be satisfactorily replaced in that occupation. A delay in call to active duty, it was emphasized, may not be considered as an indefinite exemption from military service.

Jan 9, 1950

By John T. Galey

A combination of two factors in addition to the current Federal drilling and price regulations reduced by 120 from I942 the number of new wells completed in southwestern Pennsylvania during the year. No new prospective area was found comparable to the Armbrust gas pool, Westmoreland Co., which accounted for a seventh of the last year's drilling, and it is considered doubtful whether, even if such a field had been discovered, the drilling contractors, who have been seriously affected by the manpower shortage, could have drilled many more wells than they did during the year. New wells totaling 445 were completed for a combined footage of over 1,250,000 Dry holes numbered 131 and had a footage of nearly 400,000. Old wells drilled deeper total 55, of which 17 were found nonproductive. Shallow Development Oil Oil completions yielded an initial of only slightly over one hundred barrels from 21 wells for about the same per well average as that of a year ago. However, 65 bbl. of this total came from two wells in two new strikes. The footage drilled of nearly 33,000 gives an average of nearly I00 ft. less per well than a year ago. Two old wells drilled deeper had a combined initial of only 4 bbl. The largest oil well of the year, 40 bbl., was found in the Speechley (U. Dev.) sand at a depth of 3492 ft. in German township, Fayette County. The location is several miles east of the nearest oil production hut as the area that could be occupied by a pool is fairly well delimited by drilling, the extent of this production would not appear to be large. The other notable oil production was found in the Dunkard (Penna.) sand, Cumberland township, Greene County, at a depth of 1065 ft. Here the first well had an initial of g bbl. and the second 25 bbl. However, a third proved dry, and as this area is also delimited by drilling, the pool doubtless will be of small area. Gas Gas completions yielded an initial of slightly over one hundred million cubic feet per day and new wells, totaling 303, account for all but four million of this volume. Old wells drilled deeper, numbering 35, found gas. The per well average in new drilling of approximately 320 M cu. ft. is nearly 165 M cu. ft. less than a year ago and the total footage is slightly over 830,000, which is about a quarter of a million feet less than in 1942. Average rock pressure of new completions is approximately 365 lb. per sq. in. The entire volume of new production is from the Upper Devonian or higher stratigraphic horizons. In Allegheny County, the grestest activity was in Forward and Plum townships. Wells there account for more than one half the completions. One large well was drilled in Forward township and an open flow of 3.623 million cubic feet was found in an old Gantz (U. Dev.) sand area. The top of the sand was encountered

Jan 1, 1944

By J. P. Hammond, C. J. McHargue

THERE have been no publications on the wire texture, on the cold-rolled sheet texture, nor on the recrystallized sheet texture of vanadium. Since it has a body-centered cubic structure, it would be expected to show strongly preferred orientations such as are found in iron' and molybdenum.' The wire textures of body-centered cubic iron,3 tungsten," molybdenum,5 antalum,6 iobium,6 and brass6 have been found to have [110] directions lying parallel to the wire axis. Wires of iron,' containing 1.95 pct V or 1.95 pct Si,7 and steel8 retain their texture upon recrystallization. Molybdenum9 and tungsttln' wires retain their texture after recrystallization at low temperatures. A [loo] recrystallization texture has been reported for mo1ybdenum9 and for a Fe-Ni alloy (53 atomic pct Ni).10 The cold-rolled sheet texture for iron,' mild steel," and molybdenum chiefly one in which the [110] directions lie parallel to the rolling direction and the (100) planes lie parallel to the rolling plane with a deviation from this position chiefly about the rolling direction as an axis. This paper presents the cold-rolled and the re-crystallized wire textures, and the cold-rolled and the recrystallized sheet textures for vanadium. The results show that the textures in vanadium are not significantly different from those reported for other body-centered cubic metals. The vanadium used in this investigation was the so-called "ductile" vanadium which has a nominal composition within the following limits:12 0, 0.05 to 0.12 pct; H, 0.001 to 0.004; N, 0.02 to 0.04; C, 0.03 to 0.07; and V, 99.8 to 99.9. The wires were formed by rolling annealed rods of 0.280 in. diam to 0.028 in., a reduction in diameter of 90 pct. The wires were then electrolytically etched to 0.005 in. diam and used as such for specimens. Annealed sheet was reduced 95 pct in thickness from 0.100 to 0.005 in. with a two-high, 4-in. diam mill using reductions no greater than 10 pct per pass. In order to avoid temperature effects, the sheet was allowed to cool between passes. X-ray specimens were made in the form of posts from the sheet. The sheet was mounted in a fixture and the edges were polished using metallographic technique. Each edge was alternately polished and etched during the last stages in order that all worked material would be removed. These post specimens were approximately square in cross-section. The specimens to be recrystallized were wrapped in tantalum foil, sealed in evacuated quartz tubes, and annealed at 1600°F. The X-ray data were obtained from transmission shots made with a 0.030 in. pinhole camera, and molybdenum radiation with a zirconium filter inserted between the specimen and film. The grain size was sufficiently small in both the cold-worked and recrystallized material to give satisfactory results with the specimens stationary. In order for the wire texture to be determined, transmission X-ray patterns were taken with the

Jan 1, 1953

By E. Miller, K. L. Komarek, M. Ettenberg

The activity of aluminum in solid Co-A1 alloys has been measured by an isopiestic technique between 850° and 1200°C from 45 to 80 at. pct Al. The activity shows a Precipitous decrease around the stoichzornetric composition of CoAl. Free energies of mixing have been calculated over a limited composition range. Considering an antistructure-vacancy defect mechanism, the degree of intrinsic disorder, a , in CoAl was related to the alunminum activity. Excellent agreement between the calculated and experimental activity curves was obtained for a = 1.25 x 10-4. ThERMODYNAMIC properties of solid aluminum-transition metal alloy are being studied in an investigation of disordering in ordered compounds. In a continuing series of investigations, activities of solid Fe-1,' Ni-A1, kd r-A13 alloys have been measured. From the results for Fe-A1 and Ni-A1, the degree of intrinsic disorder for the equiatomic compounds was calculated2 using equations derived by Wagner and chottk. From the results for Cr-A1 the degree of intrinsic disorder was calculated from equations derived by Orr.' In this paper, the results of the study of Co-A1 alloys are described. Published activity data in the Co-A1 system has been limited to liquid alloys at 1600°C.° A heat capacity study7 of stoichiometric CoAl indicated that a second-order phase transformation occurs at 790° C, attributed to an order-disorder reaction. Oelsen and Middel,' employing the calorimetric mixing of pure liquid metals, obtained heats of formation for compositions from 6 to 90 at. pct Co. Heats of formation for 50 and 78 at. pct Co alloys have also been measured by acid solution calrimetr. The Co-A1 phase diagram, as compiled by Hansen and Anderko,lo is in good agreement with more recent X-ray evidence. The method for measuring activities of aluminum in this study is essentially that employed in the studies of the Fe-1,' i-Al, and r-A13 systems. This isopiestic method entails placing cobalt specimens, in a temperature gradient, in a sealed alumina system containing a pure liquid aluminum source of fixed vapor pressure. The specimens are equilibrated, cooled to room temperature, and their final compositions determined. From the measured temperature of the specimens and the known vapor pressure of pure aluminum the activities of aluminum in the alloy can be calculated. EXPERIMENTAL PROCEDURE The cobalt was 3-mil-thick sheet of 99.9 pct purity (herritt Gordon Mines Ltd., anada). The major impurities were 0.1 pct Ni, 0.014 pct C, 0.018 pct Fe, 0.004 pct S, and 0.005 pct Cu. The aluminum metal had a purity of 99.99 pct (Aluminum Corp. of America) and all alumina parts were 99.7 pct A1,O3 (Triangle RR Grade, Morganite Refractories, Inc.) with major impurities 0.05 pct SiOz, 0.1 pct Fe203, 0.2 pct NazO, and 0.05 pCt K20. Runs 1 to 3 were made with annular cobalt specimens (12 mm ID by 21 mm OD) punched from the sheet. The specimens were deburred and degreased in carbon tetrachloride and in acetone. The samples, each weighing about 150 mg, were then positioned along an alumina rod, a in. OD by 14 in. long, separated by alumina spacers, i in. ID by | in. OD by & in. long. The lower end of the rod was placed in a hole drilled in the center of an 80-g aluminum cylinder. This assembly was put into an alumina crucible, 1+ in. ID by 13 in. OD by 3+ in. high, and the position of each sample was measured to within 50.5 mm relative to the bottom of the crucible. An alumina tube, 28.5 mm ID by 35.5 mm OD by 14 in. long, closed at the top, was slipped over the whole assembly, so that it fitted snugly into the bottom crucible. The entire reaction assembly was tied with molybdenum wire and lowered into a mullite tube, closed at the bottom. A quartz thermocouple tube, closed at one end, containing a t/Pt-10 pct Rh thermocouple, calibrated according to the specifications of the National Bureau of standards,'' was placed along the reaction assembly inside the mullite tube. The temperature of each specimen could be determined by gradually raising the thermocouple and measuring the temperature gradient along the reaction assembly. The combined error in temperature measurement and sample position resulted in a total error of Q°C in the recorded temperature of each sample. The mullite tube was sealed at the top by a water-cooled brass head, connected to a conventional glass vacuum system. The aluminum reservoir is heated to its melting point sealing the alumina system containing the samples. During this process the pressure is maintained below 0.01 li Hg. During subsequent heating to establish the proper temperature gradient and throughout the entire run the pressure is maintained below 2 1 Hg by means of a two-stage mechanical pump. Equilibration runs lasted from 4 to 6 weeks and were terminated by air cooling. The temperature of the liquid aluminum reservoir was brought below its melting point in less than 20 min. For runs 4 and 5, alloy buttons with 49 and 69 at. pct A1 were prepared from the initial high-purity metals by arc melting under purified argon. The alloy buttons were comminuted to powder with an alumina mortar and pestle until the powder passed through a 400-mesh screen, particle size 0.0014 in. Portions of this powder weighing between 50 and 200 mg were placed in small alumina trays, 25 by 15 by 5 mm, which were then

Jan 1, 1969

By H. Sigurdson, C. H. Moore

Extensive studies have been carried out on electric furnace and blast furnace slags obtained in the winning of iron from its ores. These slags normally consist of elements of the gangue minerals present in the ores, as well as the added flux materials. In consequence, melts of CaO, MgO, Al2O3 and SiO2 can be considered as representing typical slag compositions. When a slag of this composition cools, it usually crystallizes according to predictions possible from an equilibrium diagram of these constituents, providing the melt is not undercooled to form glass. The melt is either viscous or fluid, depending upon the ratio of binary cations to silica, and crystallizes easily or forms a glass for the same reasons. If the melt is not overheated so that carbides of the metal components of the slag are formed and if the composition of the slag is so adjusted that it has a high fluidity, liquid equilibrium is attained and the slag can be held in a liquid state for extended periods of time. Upon tapping, the slag crystallizes into minerals, the type and proportion of which are determined by the melt composition. Since equilibrium is attained, the holding period is not critical. In melts containing a large increment of titanium, however, the normal slag procedures are not applicable. Titanium, as one of the atomic transition elements, is, at elevated temperatures, capable of being reduced to form metalloid compounds much more readily than the refractory oxides present in normal slags. In consequence, an oxide melt containing titanium never reaches equilibrium in a reducing environment, but continues to shift its composition until cooled. If melts of this nature are cooled and samples submitted to metal-lographic and X ray analysis the course of reaction and crystallization in this type of slag can be determined. Preparation of Slag The slags investigated fell into the system CaO-MgO-TiO2-Al2O3-SiO2 and were produced from ilmenite ores reduced by carbon in an electric furnace. Since the equilibrium series1 and the laboratory smelting of ilmenite2 are described in two of the accompanying papers, detailed description of the smelting procedure is not required here. However, certain essentials must be mentioned. Two types of melts were used to produce slags studied in this investigation. The first series of smelts made to determine proper flux addition were produced in a 4 lb Ajax induction furnace. The charge, consisting of ore with the proper flux addition, was heated in a graphite crucible until fluid, held fluid for a sufficient time period to obtain 1-5 pct FeO content, and poured. Because of the small size of the charge only the final sample of these melts could be examined. In the melts made in the 50 lb arc furnace, however, grab samples taken at 10 min. intervals between time of initial melting and final pouring were available for examination. These samples allowed a much clearer picture of the course of reaction and crystallization. amounts of ferrous oxide and reduced titanium compounds is opaque to transmitted light. Therefore, all petro-graphic studies had to be made on polished slag sections. A representative sample of slag was cut or broken, mounted in a thermosetting plastic, ground flat using 400 grit silicon carbide, the coarse scratches removed with 600 grit silicon carbide and polished on billiard cloth using levigated alumina. Rouge was avoided because of the entrainment of the red particles in pores in the slag, causing a possible confusion with some of the mineral phases. In order to prevent sample projection above the plastic surface red bakelite was used to hold the sample, and backed up with clear lucite. In this manner sample labels could be permanently retained in the mounting. The polished samples were examined on a Bausch and Lomb metallograph at magnifications of 250 X, 500 X, 1000 X and 1800 X. The instrument was equipped for examination of specimens under bright field illumination and with crossed nicols. A magenta tint plate to aid in color tone differentiation was also used. Petrology of Slags In order to determine the composition and mineral relatinos of a previously unreported system petrologically, it is essential that the starting composition, reaction temperature and final composition be known. The chemical composition of the ilmenite ore used in these smelts is given in Table 1, and the complete analysis of a typical high titanium, low iron slag is given in Table 2. In the winning of TiO2 from ilmenite by a smelting process it is necessary to produce a slag which will melt at an economically feasible temperature, remain molten as the iron is removed by reduction, be fluid enough to be readily removed from the furnace, contain a high percentage of TiO2 and a low percentage of reduced titanium com-

Jan 1, 1950

By T. A. Rickard

A knowledge of the principles of punctuation is essential to effective and intelligible writing, for the ease and pleasure of the reader, and even his understanding, may depend upon the choice and the placing of punctuation marks. To 'punctuate' is to mark with stops or points; the word comes from the medieval Latin punctuare (punctuatus), which in turn is derived from the Latin punctum, a point. The purpose of punctuation is to show the manner in which the writing is to be understood; to indicate the relations between parts of a sentence and between successive sentences. To some extent "it does for the eye what vocal stress does for the ear", but especially it marks logical relations. Some punctuation marks, such as those indicating admiration, exclamation, and interrogation, are rhetorical as well as grammatical, but most of the common ones are logical, or grammatical. My discussion will be confined to grammatical punctuation in ordinary writing. .'The problem of punctuation in text matter", as George Summey * says, "is to employ words, points, and paragraph breaks in such a way as to achieve at the same time clearness; proper distribution of emphasis, and the desired kind of movement." The criticism of the punctuation of a sentence or of a group of sentences is not final until the context, within the paragraph, is read. A paragraph is a sentence or a group of sentences forming an independent unit of the composition; it represents a unit of thought. A multiplicity of paragraphs produces a choppy effect; 'on the other hand, paragraphs of. excessive length are tiresome, because the belaboring of one unit of thought wearies the reader. The aim should be to

Jan 1, 1931

By CARL B. SNYDER

PERHAPS the most extraordinary thing about business, the trade and production of the country as a whole, is its amazing continuity and growth, its momentum and energy. It goes on year after year, growing steadily, almost without breaks, in spite of every kind of disturbance. We have been grossly deceived into the idea that business is highly variable. We have taken a few things like pig iron, and the like, constructional activity broadly, and imagined that these are a trustworthy measure of trade. Actually they are the worst that we could find. They do not apply to more than 10 per cent or, at the most, possibly 15 per cent of the total of the country's industrial activity. The other 85 or 90 per cent, or even more, goes on growing surely and steadily just like the growth of population and the steady advance in technique, invention, discovery, and improved methods of production Let me give you what seems to me one of the most remarkable examples of this amazing momentum and regularity. You know that 90 per cent or more of the business of the country is done 'by means of checks. About seven-eighths of the total of all checks drawn are reported regularly every week in the newspapers. Let us follow these reports from week to week, just as they come, and plot them up against the correspond- ing weeks of last year, and the year before, and the gear before that, as far back as you would like to go. Take especially the figures for 140 selected cities out- side of New York.

Jan 1, 1929

By HUNTINGTON ADANS

(Wilkes-Barre Meeting, June, 1911.) THE arrangement of a flow of cyanide-pulp through Pachuca tanks in agitation, so as to permit a continuous process, instead of alternate filling, agitation, and emptying, has been proposed by various writers within the last two years, and more particularly by A. T. Grothe, agent for the Brown patents on Pachuca tanks in Mexico. It was first put into practice, I believe, by M. H. Kuryla at the Esperanza mine in El Oro, Mexico. The starting of agitation in Pachuca tanks after filling may offer no serious difficulties with ores which do not settle rapidly in such tall tanks; and the adaptation of the tanks to continuous agitation under such conditions may give simply a somewhat more convenient method of treatment and greater agitation-capacity for a given number of tanks, because of the saving -of time lost in filling and discharging. But in the treatment .of pulp which tends to settle rapidly, as in the cyaniding of concentrates or of the whole pulp of ores containing heavy sulphides, the packing of the slime at the bottom may, cause much trouble. The use of the radial air-pipe attachments near the top of the cone and of the air-valve outside of the air-lift .tube at the bottom may obviate the difficulty to some extent; but the action of the radial air-pipes on the cone-sides is that -of a sand-blast, and their continuous use cuts through the tanks. Moreover, even when these pipes are used, some pulps will pack tightly below them in the cones. Under such conditions the use of Pachuca tanks with intermittent filling and discharging becomes a troublesome process. Time is lost in ,starting agitation; large quantities of compressed air are wasted; pulp is blown over the tank-tops; and not infrequently it may be necessary to dig out the bottoms of tanks by hand. This trouble is the only important one occurring in the use of Pachuca tanks; and, since it is caused by intermittent filling, the .arrangement of a continuous flow of pulp from tank to tank,

Aug 1, 1911

By Pedro L. Lizaur

INTRODUCTION The degree of success of an association between parties in establishing a new venture ultimately depends on three factors: a. the venture's underlying economic strength, which is based on the complementarity of the comparative advantages brought by each party to the negotiating table; b. the ability to reach an agreement which satisfies each party's objectives and constraints; and, c. the capacity to design and implement a funding structure which is consistent with the project economics. A thorough assessment of the venture's profitability and associated risks under alternative technical and economic scenarios is the basis for a sound "go" or "no go" decision. In-depth evaluation of the risks and rewards to each of the parties involved under alternative legal and financial structure must be the foundation for a long lasting "how to go" decision. The allocation of risks and rewards should be consistent with the objectives and constraints of all parties and the sharing mechanisms, established in the contract, should be flexible to assure the long-term stability of the agreement. Rapidly changing economic conditions during the last decade have had a dramatic impact on the envisaged allocation of risks and rewards between host countries and private investors. The effects of these changes, and the fact that the relative strengths of the parties involved may shift during the life of a project (e.g. before and after major capital investments have been made), have forced the renegotiation of a multitude of contracts. Therefore, the present and future stability of an economic agreement would depend not only on the originally designed provisions, but also on provisions which allow for the automatic adjustment of rewards to project sponsors under a variety of future economic situations. A pre-condition for the allocation and quantification of risks and rewards is the definition of standards of measurement used by each of the parties. This is critical in international negotiations when one of the parties represents the national interests of a country. The understanding and use of different standards for the measurement of rewards for risk taken between a government and private enterprise facilitate the negotiation of a satisfactory agreement. This is possible because certain trade-offs between the negotiating parties may have different relative values. STANDARDS OF MEASUREMENT OF REWARDS FOR RISK TAKEN The negotiating process takes a step forward when the parties are able to focus on their interests, explore different alternative solutions and then base results on a set of objective standards. Unfortunately, the parties frequently put more effort into "staking out" and defending positions, than into understanding their intrinsic interests. Moreover, when one party, such as a governemnt owned corporation, represents a country's national interests, the negotiation process increases in complexity. Private firms focus on commercial profitability, using discounted cash flow techniques such as NPV, IRR, or ROE. In contrast, the government is also concerned with the project's impact on the local socio-economic environment. Without entering into a discussion of alternative economic development theories and approaches, there exist several possible measures that could be pragmatically utilized by each party in evaluating the socio-economic impact of a project. The more complete measure is the National Profitability (NP). The NP is a discounted cash flow procedure similar in structure to IRR or NPV but in which the project's financial cash inflows and outflows and discount rates are adjusted to take into consideration the local conditions. The NP is calculated on an unlevered basis and all taxes and duties are removed from the project

Jan 1, 1985