Search Documents

By C. W. Hill, G. P. Luckey

In a previous article1 preliminary experiments were described, indicating the possibilities of a quantitative spectroscopic method for the determination of small amounts of lead in copper, which would be accurate and rapid, and could be carried out in the refining plant by one not skilled in chemical analysis. The present paper deals with the development of the method in the factory, giving the details of apparatus and its standardization, and presenting a comparison of the accuracy of the method with that of the standard electrolytic determination. (For variations and other applications of the method, the reader is referred to the first article.) A carefully weighed sample (0.4 gm.) of the copper to be tested is placed in a cavity in a graphite positive electrode. An arc capable of

Jan 1, 1919

By F. M. Hamilton, H. F. Ameen

Results of a laboratory investigation of some sintering variables are presented. The effect on physical properties of mix component variation and rate of cooling of the sinter is illustrated by crush and tumbler test results and data of reducibility tests and microscopic examination of sinters are shown. The results of using solid additions in the mix to improve bed permeability are given. SOME of the variables encountered in the sintering of iron ores and their effect on sinter properties have been investigated at the Jones and Laughlin Ore Research Laboratory in Michigan. Ores requiring agglomeration before blast furnace utilization may be classed as coarse, intermediate or fine. Coarse iron ore is considered similar to a — 1/4-in. Mesabi wash ore containing some 95 pct of its particles between 94 in. and 100-mesh. Intermediate iron ore is considered similar to our New York State magnetic concentrates in which all the particles are — 20-mesh and about 60 pct are +100-mesh. Fine ores are considered as being at least 100 pct —100-mesh. This paper will deal only with the two coarser classifications. Most of the work has been done in a small experimental batch unit previously described in an AIME1 paper. Results being obtained form a basis for present and future trials in production sinter plants. It is expected that new production units that may be added in the future will benefit from laboratory studies. In general, the results reported here are obtained by laboratory study, but it is Experimental Sinter Machine: The laboratory sinter machine employed in the work consists of a chamber with 1 sq ft of grate area. It is mounted on

Jan 1, 1951

By H. F. Ameen, F. M. Hamilton

Results of a laboratory investigation of some sintering variables are presented. The effect on physical properties of mix component variation and rate of cooling of the sinter is illustrated by crush and tumbler test results and data of reducibility tests and microscopic examination of sinters are shown. The results of using solid additions in the mix to improve bed permeability are given. SOME of the variables encountered in the sintering of iron ores and their effect on sinter properties have been investigated at the Jones and Laughlin Ore Research Laboratory in Michigan. Ores requiring agglomeration before blast furnace utilization may be classed as coarse, intermediate or fine. Coarse iron ore is considered similar to a — 1/4-in. Mesabi wash ore containing some 95 pct of its particles between 94 in. and 100-mesh. Intermediate iron ore is considered similar to our New York State magnetic concentrates in which all the particles are — 20-mesh and about 60 pct are +100-mesh. Fine ores are considered as being at least 100 pct —100-mesh. This paper will deal only with the two coarser classifications. Most of the work has been done in a small experimental batch unit previously described in an AIME1 paper. Results being obtained form a basis for present and future trials in production sinter plants. It is expected that new production units that may be added in the future will benefit from laboratory studies. In general, the results reported here are obtained by laboratory study, but it is Experimental Sinter Machine: The laboratory sinter machine employed in the work consists of a chamber with 1 sq ft of grate area. It is mounted on

Jan 1, 1951

By Edwin B. Douglas

The Blackbird mine is owned by Calera Mining Co., subsidiary of Howe Sound Co. The mine is located in the Salmon National Forest, Lemhi County, Idaho, about 22 miles west of Salmon and 220 miles north of Pocatello. The thought of producing cobalt from a prospect that offered excellent opportunities stimulated everyone connected with this project. But as time went on, it was found that every phase of the development presented unusual difficulties.

Mar 1, 1956

By GEORGE D. RAMSAY

ABOUT three miles west of Fontana San Bernardino County, California, and fifty miles east of Los Angeles, the Kaiser Co., Inc., has built an integrated steel plant. By integrated, I mean that from its wholly owned iron ore and coal supply, the Kaiser Co. is producing in its own mills iron and steel products. Pig iron to meet the West Coast needs has been produced at Fontana since Jan. 1, 1943; steel ingots were first poured there May 14, 1943; and steel plate for ships was first rolled Aug. 15, just sixteen months after ground was broken. Briefly, the plant consists of: (I) Two batteries of by-product coke ovens, totalling ninety ovens, carbonizing about 1740 tons of coal per day at capacity; with by-product facilities for the production of tar, ammonia, and ammonium suIphate, light oil distillates, and tar distillates. (2) One blast furnace producing at

Jan 1, 1944

By C. O. Lee, R. H. Feierabend, Z. W. Bartlett

DESPITE the fact that American brimstone production has increased 2 times since the prewar period 1935-1939, the demand for sulphur exceeds the supply. To alleviate this situation efforts are being made to increase the production of sulphur and bring the shortage to an end. The most important developments are being undertaken on the Gulf Coast. One new brimstone mine has been put into operation and three others are being developed. These projects are expected to account for a large part of the additional sulphur production now anticipated for the free world.'.' Except for a small amount of byproduct sulphur from sour natural gas and refinery gases, American brimstone is produced by the same process devised by Frasch 60 years ago, consisting essentially of the injection of superheated water at about 325°F into sulphur-bearing formations through wells which are drilled from the surface by standard oilfield methods. Sulphur deposits vary in depth from a few hundred feet to 2500 ft from the surface; in a typical deposit the sulphur occurs as crystalline aggregates in porous limestone and gypsum in concentrations varying from 5 to 40 pct, the thickness of the formation ranging from a few feet to several hundred.3 The deposits are usually surrounded by formations impermeable to the flow of hot water, the top and sides being enclosed by impermeable sediments and the bottom by dense impermeable anhydrite. As the hot water leaves the well bore, it percolates through the formation and transmits its heat to the rock and sulphur. When the sulphur reaches 240°F it melts, separates from the rock, and flows through the hot channels downward to the bottom of the well. Here it is freed from incoming water and from formation water, which saturates the porous rock, by gravity separation, liquid sulphur being 1.8 times as heavy as water. It then is pumped to the surface in a relatively pure state, 99.5 pct or better. Chief contaminants are organic impurities, such as petroleum residues, which are soluble in sulphur and tend to discolor it.' Sixteen deposits of commercial magnitude have been discovered in the Gulf Coast area. Five of these deposits have been depleted and abandoned with production totalling more than 26,886,000 tons. Eight properties are operating and have produced 65,875,-000 tons to Jan. 1, 1952, for a total Frasch-type production of 92,761,000 tons. Three new deposits are under development. Aforementioned deposits are listed in Table I. Each of these deposits has been found in the cap-rock overlying shallow intrusive salt plugs or domes and buried in several hundred to as much as 2500 ft of sediments. All salt domes do .not contain sulphur; only 16 sulphur deposits have been found in a total of 231 salt domes which are known to exist in the Gulf Coastal states of Texas, Louisiana, Mississippi, and Alabama. Ten of the salt domes lie in the Gulf of Mexico offshore from the Texas and Louisiana coasts. Additional offshore domes may be found, but their value as a sulphur potential is questionable owing to the great hazard and high cost that can be visualized at these exposed locations where depths of water reach 50 ft. Marsh operations of Freeport Sulphur Co. are in the southeast section of Louisiana. In general, the country is low, flat, relatively uninhabited marshland broken by many shallow lakes and bayous which extend for irregular distances inland. Geologically, the coastal area is of sedimentary origin, having been built up gradually under the sea by deposition of material carried down by large streams to their deltas. Offshore bars were formed enclosing

Jan 1, 1953

By C. O. Lee, Z. W. Bartlett, R. H. Feierabend

DESPITE the fact that American brimstone production has increased 2 times since the prewar period 1935-1939, the demand for sulphur exceeds the supply. To alleviate this situation efforts are being made to increase the production of sulphur and bring the shortage to an end. The most important developments are being undertaken on the Gulf Coast. One new brimstone mine has been put into operation and three others are being developed. These projects are expected to account for a large part of the additional sulphur production now anticipated for the free world.'.' Except for a small amount of byproduct sulphur from sour natural gas and refinery gases, American brimstone is produced by the same process devised by Frasch 60 years ago, consisting essentially of the injection of superheated water at about 325°F into sulphur-bearing formations through wells which are drilled from the surface by standard oilfield methods. Sulphur deposits vary in depth from a few hundred feet to 2500 ft from the surface; in a typical deposit the sulphur occurs as crystalline aggregates in porous limestone and gypsum in concentrations varying from 5 to 40 pct, the thickness of the formation ranging from a few feet to several hundred.3 The deposits are usually surrounded by formations impermeable to the flow of hot water, the top and sides being enclosed by impermeable sediments and the bottom by dense impermeable anhydrite. As the hot water leaves the well bore, it percolates through the formation and transmits its heat to the rock and sulphur. When the sulphur reaches 240°F it melts, separates from the rock, and flows through the hot channels downward to the bottom of the well. Here it is freed from incoming water and from formation water, which saturates the porous rock, by gravity separation, liquid sulphur being 1.8 times as heavy as water. It then is pumped to the surface in a relatively pure state, 99.5 pct or better. Chief contaminants are organic impurities, such as petroleum residues, which are soluble in sulphur and tend to discolor it.' Sixteen deposits of commercial magnitude have been discovered in the Gulf Coast area. Five of these deposits have been depleted and abandoned with production totalling more than 26,886,000 tons. Eight properties are operating and have produced 65,875,-000 tons to Jan. 1, 1952, for a total Frasch-type production of 92,761,000 tons. Three new deposits are under development. Aforementioned deposits are listed in Table I. Each of these deposits has been found in the cap-rock overlying shallow intrusive salt plugs or domes and buried in several hundred to as much as 2500 ft of sediments. All salt domes do .not contain sulphur; only 16 sulphur deposits have been found in a total of 231 salt domes which are known to exist in the Gulf Coastal states of Texas, Louisiana, Mississippi, and Alabama. Ten of the salt domes lie in the Gulf of Mexico offshore from the Texas and Louisiana coasts. Additional offshore domes may be found, but their value as a sulphur potential is questionable owing to the great hazard and high cost that can be visualized at these exposed locations where depths of water reach 50 ft. Marsh operations of Freeport Sulphur Co. are in the southeast section of Louisiana. In general, the country is low, flat, relatively uninhabited marshland broken by many shallow lakes and bayous which extend for irregular distances inland. Geologically, the coastal area is of sedimentary origin, having been built up gradually under the sea by deposition of material carried down by large streams to their deltas. Offshore bars were formed enclosing

Jan 1, 1953

By C. Hirayama

THIS investigation was undertaken to determine some of the factors contributing to the embrittle-ment of glass-coated silver wire on heat treatment. The materials used in this investigation were 22 and 23 AWG silver wires obtained from Handy and Harman as "fine quality, soft temper." A wet analysis of one sample showed 99.8 pct Ag. The 23-gage wire was covered with a double layer (2.5 mils thick) of electrical grade fiber glass (aluminum borosilicate glass containing a relatively high concentration of calcium, and a very small amount of

Jan 1, 1960

By W. W. Stephens, W. J. Kroll, H. P. Holmes

THE only two methods for producing commercial quantities of malleable zirconium, up to now, have been using magnesium reduction of the anhydrous chloride under a neutral gas, and using purification of raw zirconium by the iodide dissociation method on a hot filament. The purity of the metal obtained by the latter process is about the same as that resulting from the chloride reduction, with the exception of the oxygen content, which may be about 0.05 pct lower in the iodide metal. Even traces of oxygen have a strong hardening effect on zirconium. Since, in the iodide process, the impurities, Si, Al, Fe, Ni, and Mg in the raw zirconium used, are carried over, it would appear uneconomical to use this method of refining solely to eliminate the traces of oxygen, unless very soft metal is desired. One important step to improve the iodide method, namely, dissociating pure iodide made from carbide and recycling the iodine, which would change this refining process into a method for extracting zirconium from the ore, has not yet been made. The Bureau of Mines, by using the chloride reduction, wanted to produce quantities of a reasonably pure and malleable metal at low cost for large-scale industrial use. This aim has been achieved, and a pilot plant permitting production of 600 lb of malleable zirconium per week will be described (fig. 1). Briefly, the Bureau of Mines process consists of reducing purified gaseous anhydrous zirconium chloride with fused magnesium under a noble-gas atmosphere. The reaction product, magnesium chloride, and any excess magnesium metal present are removed from the sponge zirconium in the next step by fusion and evaporation in a good vacuum at about 925°C. In this process, care is taken to keep air out of contact with the hot metal, which otherwise would contaminate the product with oxygen and nitrogen. Both these impurities embrittle zirconium even when present in an amount as low as 0.1 pct. A number of previous reports1-3 describe the method and the various improvements that finally led to a workable process. The major steps made were the production of large quantities of carbide, which is the raw material for producing the chloride, its chlorination with reasonable efficiencies, and the elimination of iron trichloride contained in the raw chloride, as well as that of the zirconium oxide which is always present in this product. The physical nature of the anhydrous chloride, which sublimes at 331°C at atmospheric pressure and melts at 420°C under a pressure of 25 atm, made it necessary to provide a special safety device on the purification and reduction vessels in the form of a lead-alloy seal, permitting escape of excess gases if pressure tended to build up. The main difficulties encountered in the reduction and in the following step, salt separation in a vacuum at elevated temperature, were caused by the material from which the reaction pot was constructed—iron. This metal reacts with zirconium at about 940°C with formation of a eutectic. The last step, salt separation by evaporation of the magnesium and magnesium chloride in a vacuum, is quite unconventional and has not been used before on such a scale. It is only due to the improved construction of high-vacuum pumps, especially oil-diffusion pumps, that such a method could be used. The various steps of the Bureau of Mines process, as described in the general outline above, may be summarized as follows: (1) production of the carbide, (2) chlorination of the carbide, (3) purification of the raw chloride, (4) reduction of the pure chloride with fused magnesium, (5) separation of excess magnesium and magnesium chloride in vacuum at elevated temperature, and (6) melting of the sponge obtained. Production of Carbide The arc furnace, described in a previous report,' was improved both to reduce the graphite consumption caused by the burning of the bottom plates and to concentrate the heat in order to obtain better power efficiency. This was achieved by providing the bottom with graphite plates entirely embedded in refractory bricks, the contact with the current being made with three water-cooled copper plugs. Figs. 2 and 3 show the arrangement. The crucible, made

Jan 1, 1951

By D. J. Oswald, J. G. Ziegler

It is of common knowledge that loading within a grinding mill, whether ball, rod, pebble, or autogenous, is directly related to the lubrication back pressure developed between the mill journal and bearing shoe during mill operation. The merits of both forced-feed and gravitational-feed bearing lubrication methods are discussed with particular emphasis directed toward their applicability to continuous grinding mill inventory control. Data obtained from wet grinding mill applications in the cement and mining industries is presented to more clearly define the influence of such variables as feed consistency, slurry viscosity, mill retention, bearing oil temperature, grind fineness, and grinding media wear on the measured journal lubrication back pressure during automatic mill feed control. Finally, various grinding mill control schemes for maintaining constant mill loading and consequently optimizing mill operating efficiency are discussed and evaluated as to their advantages and/or disadvantages.

Jan 1, 1974

By David K. Hylbert

This study investigated roof falls in room-and-pillar drift coal mines in eastern Kentucky and utilized geologic methods for predicting roof conditions in advance of mining. In the Highsplint mine, the roof was classified in four categories or conditions: Condition A and B (Laminated Shale); Condition C (Rolling Sandstone with Shale in Pockets); and Condition D (Zone of Major Sandstone Roll(s)). Structure contour and isopach maps of the Darby coal bed and associated immediate roof rocks were wed to project axial trends of the sandstone roof. Trend mapping in the mine and on outcrop provided more detailed control for roof projections.

Jan 12, 1978

By A. D. Zunkel, A. H. Larson

Equilibrium antimony contents of pb-sb alloys in contact with PbO-Sb2O3 slags containing less than 45 mole pct Sb203 uleve determined at 650', 700°, and 750°C in an inert atmosphere. In this ten~pevature range, the antimony contmzt of the alloy increased with increasing temperature at all slag compositions. The PbO-Sb203 phase diagram below 28 mole pct Sb2O3 was determined by thermal analysis and by application of a log sbZ4/y$b0 us plot determined from the equilibrium-activity data. The resulting phase diagram showed a eutectic at a temperature of 604°C and a comfiosition of 21.6 mole pct Sb2O, with a maximum terminal solid solubility of Sb203 in PbO of 5.6 mole pct. These results are compared with existing data in the literature. In the past three decades, only a small amount of experimental work has been done on the slag-metal equilibria in the Pb-PbO-SbaO3 or the analogous arsenic and tin systems. These systems are important in commercial lead-refining processes such as softening and dross fuming since it is impurities such as antimony, arsenic, and tin in lead bullion and Sb2O3, As2O3, and SnOz in lead drosses which must be re-

Jan 1, 1968

By Ole Singstad

THE legislatures of New York and New Jersey, determined in 1919 that a vehicular tunnel should be built under the Hudson River. On July 1, 1919, an engineering staff was organized with the late Clifford M. Holland as chief engineer, and this staff was given a number of problems to solve, such as location, size, type of tunnel, method of construction, method of ventilation and cost. After a period of preliminary investigations and studies it was decided to build the tunnel at Canal St., New York, connecting 12th St., Jersey City. This is the center of the heaviest traffic across the Hudson River. It was also decided to build two tunnels-one for west-bound traffic and one for east-bound traffic-the tunnels to be of cast iron, built up of segments and bolted together, each tunnel to have a roadway 20 ft. wide and a clear heat room of 13 ft., 6 in. This is to provide for two lines of vehicles in each direction. The tunnels have an exterior diameter of 29 ft., 6 in. The interior lining is of concrete, the sidewalls tiled with a vitreous white tile and the roadways paved with granite block. The entrances and exits at both ends are separated by two blocks so as to reduce traffic congestion.

Jan 8, 1926

By O. J. Huber, P. D. Frost, H. A. Robinson

URANIUM is a (ß-stabilizing, eutectoid-forming element when alloyed with titanium. Udy and Boulger1 have reported that an alloy of 48.6 pet uranium in titanium retains ß-phase when quenched from the ß-region, while compositions of approximately 30 pet uranium transform to martensite during such quenching. Since the eutectoid reaction is rather sluggish, titanium-uranium alloys should be capable of being strengthened by the ß — a trans-

Jan 1, 1959

By F. L. Holderreed

A choosy in what they would smelt. The furnace charge had to be coarse, and it had to be rich. They discarded fines in excess of about 1/10 the total weight. They wanted 10% copper content and fussed about anything with as low as 5%. They concentrated the copper content of the charge as much as they could by prior selection. They roasted off enough sulfur to further enrich the copper content of the succeeding fall of matte (a melt of cuprous and ferrous sulfides or Cu2S.FeS). Then they desulfurized the iron and fluxed it by carefully adding silica (quartz, not silicates) for a slag of lower density than the cuprous sulfide (Cu2S or white metal). After skimming off the slag, they further desulfurized the white metal by blowing the molten bath with compressed air. The result was blister copper. Yesterday Their techniques and furnaces? Some experimented with mechanically rabbled roasters, but their standard roasting practice was burning coarse sulfide ore in 250-ton heaps. These heaps, approximately 24 x 24 x 6 ft, were burned for about 75 days down to 6-10% sulfur. The turnaround time for a given roasting position was 100 days. Assuming the base was a hearth, the calculated rate of treatment was on the order of 0.004 tpd per sq ft.

Jan 1, 1971

By E. P. Chapman

In May 1957 a diamond drill hole intersected 40 ft of magnetite and chalcopyrite assaying 2.55% copper and 51.6% iron on the claims of Craigmont Mines Ltd. near Merritt, southern British Columbia. The subsequent drilling indicated the presence of a multi-million ton orebody averaging over 2% copper and 18% iron, the latter present for the most part as magnetite and specular hematite in approximately equal proportions. This orebody, although under shallow cover at its eastern extremity, did not come to the surface and the early drilling was done on the basis of strong coinciding magnetic and geochemical anomalies. After 4 ½ years of intensive exploration and development the property was put into production in September 1961. The new ultramodern concentrator has a design capacity of 4000 tpd but is consistently treating well over this amount. Production is currently coming from that portion of the deposit which is amenable to open-pit mining methods. By mid-1958 information regarding the importance of the Craigmont find became fairly wide- spread, and exploration in the Merritt area was greatly intensified. Numerous magnetic and geochemical anomalies have been tested by drilling with notable lack of success. Detailed geological studies of the deposit and of the area have been made by Government agencies and by private companies and such studies are continuing. Many types of geophysical methods have been employed over the Craigmont deposit in an effort to develop knowledge which would assist in the search for similar mineral concentrations in the environment in which it occurs. This paper will discuss the results of the various geophysical surveys in relation to geological conditions and ore outlines insofar as they are now known.

Jan 7, 1962

[Trans. No. Place Date Vol. Page 1. Wilkes-Barre, Pa May, '71.. 1 3 2. Bethlehem, I's Aug., '71.. 110 3. Troy, N. Y Nov., '71.. 113 4. Philadelphia, PaFeb., '72.. 117 5. New York, N. YMay, '72120 6. Pittsburgh, Pa Oct., '72.. 125 7. Boston, MassFeb., '73.. 128 8. Philadelphia, Pa.*May, '73.. 23 9. Easton, PaOct., '73.. 27 10. New York, N. Y Feb., '74211] [ ]

Jan 1, 1925

By S. L. Couling, G. W. Pearsall

MOTT and Hainesl have summarized the available techniques for the examination of aluminum and some anisotropic metals under polarized light. Many of these techniques are rather complicated and cumbersome. This note presents a simplified procedure for using polarized light to obtain information about the crystallographic orientation of any particular grain in a magnesium alloy. Since other hexagonal metals are more anisotropic than magnesium, similar methods might well be applied to them. Ernst and Laves2 produced a double-refracting layer on magnesium alloy specimens by SuCCeSSiVe etches in solutions of perchloric acid in alcohol, magnesium perchlorate in perchloric acid and alcohol, and calcium and magnesium carbonates in water. They examined their specimens under polarized light and were able to determine the direction of the hexagonal axis in any particular grain from a measurement of the extinction behavior of that grain. The disadvantages of their technique were the complexity of the etching procedure and the explosive hazard of the perchloric acid-alcohol solutions. Results equivalent to those of Ernst and Laves were obtained in this investigation after etching specimens for 6 to 8 sec in an acetic picral solution containing 100 parts 6 pct picral, 10 parts distilled water and. 5 parts acetic acid. A. similar etch has been used by George3 in earlier metallographic

Jan 1, 1958

By N. H. Harrison, J. K. Rodgers, S. Regier

This paper presents comparisons of data obtained from a laboratory reservoir study and from a calculated behavior prediction with the actual production history of a condensate reservoir. A small non-commercial discovery was depleted under closely controlled conditions and the well fluids were sampled at frequent intervals. Data on the reservoir and production variables were accumulated on a fixed schedule. A laboratory reservoir study war made using the initial well fluid samples as charging stock. The production procedures and operating conditions were held constant throughout the study wherever possible and in general paralleled the field work. The well fluid compositions and the cumulative recoveries ar a function of the reservoir pressure were also calculated using conventional flash vaporization procedures and equilibrium constants. Comparisons based on the composition of the well fluid show good agreement, the laboratory study agreeing within experimental accuracy with the field work and the calculated data comparing equally well. The gas-oil ratios are also in good agreement, but with somewhat greater deviations at the higher pressures. In the overall picture, it is believed that a model st,~tiy can predict within experimental accuracy the production history of a condensate reservoir. Better equilibrium constants for the heavier hydrocarbons are needed in order to attain improved composition accuracy by calculation. INTRODUCTION In Aug., 1955, a gas condensate well was completed in San Juan County, Utah, that was initially thought capable of good commercial production. These conclusions were derived principally from core data and electric logs, which indicated good permeability, porosity and gas content. However, after the usual series of potential tests it was found that the reservoir pressure had declined some 22 per cent, and it was obvious that the zone tapped was but a small pocket or trap. It became apparent that, with a controlled depletion of a small reservoir, a unique opportunity was available to compare laboratory and calculated studies with an actual field depletion and to further the present knowledge of condensate reservoirs. FIELD WORK The Coalbed Canyon Well No. 1 was conventionally completed in the Paradox limestone formation to a total depth of 5,912 ft. The producing zone from 5,762 to 5,806 ft was perforated with four jet shots per ft. The wellhead and field equipment were also conventional, the major items consisting of a two-pass indirect fired line heater, a high- and a low-pressure separator with the necessary controls and accessories, gas meters, back-pressure regulators, flare stacks and condensate stock tanks. The initial testing of this well con-sisted of a series of flow potential and pressure build-up tests during which some 30 MMcf of gas was produced. The reservoir pressure declined from an estimated 2,300 to 1,782 psig during this period, from which it was concluded that the reservoir was very small. In order to approach steady-state conditions in the reservoir and so provide optimum conditions for making comparisons, the field depletion was programmed to approach, if possible, constant production conditions. Bi-hourly readings were taken of the tubing pressure, the pressure and temperature of the separators, oil and gas rates, and other pertinent operating data. The gas rate, as indicated by the orifice meter, was held constant by the adjustment of the choke in the line heater. The temperature of the first stage separator was held constant by adjustment of the line heater jacket temperature. Practical considerations of production made the maintenance oi a constant gas rate impossible. The test started with a gas rate of 4 MMcf/D and a separator pressure of 250 psig. This rate was maintained until the choke was fully opened. The gas rate then declined with the falling tubing pressure and production was continued until the rate was about 2

By C. E. Birchenall, J. R. Stubbles

ThE equilibrium between lead, lead sulfide (PbS), and atmospheres of H2 and H2S has been determined previously by Jellinek and Deubel,' and SudO.' Blbem and Kroger3,4 used Jellinek's data to calculate the sulfur dissociation pressures of PbS crystals (of

Jan 1, 1960