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The Empire IV expansion is on schedule for completion in January 1980; Hibbing Taconite's 2.7 million ltpy* expansion should be finished late in 1979; and Reserve Mining's tailing disposal project is on target for April 1980. Erie Mining Co., the first to bring 170-ton haulage trucks to the Mesabi Range, reports excellent operating results, and Inland Steel expects to produce 80% of its pellets in 1979 using coal rather than oil. One Michigan mine has so many inspectors that it has hired a school bus to transport them around the operation; and a contractor reports that mine construction projects of the future may require the training of 15,000 workers. All of this was covered at the 52nd Annual Minnesota Section AIME Meeting and the 40th University of Minnesota Mining Symposium, a joint event held each January in Duluth.

Jan 3, 1979

At Black Lake, Quebec, Lake Asbestos of Quebec Ltd., a wholly-owned subsidiary of American Smelting and Refining Co., has opened a $36-million mining and milling operation which will produce about 100,000 tons of asbestos fiber a year and add 7 pct to the Free World's supply. The orebody once lay beneath Black Lake, and readying the ore deposit for open pit mining meant removing about 37 million cu yd of overburden- 30 million cu yd by dredging and pumping, and 7 million by power shovels and trucks. The enormous amount of material to be dredged, control of drainage during dredging, the need to cope with drainage problems in the area and to provide for flood control to replace the regulating effect of the lake, posed unusual engineering challenges and required tremendous capital investment.

Jan 1, 1959

By Henry Leidheiser, Melvin C. Jr. Hobson

The rate of formation of the intermetallic compound, indium antimonide, at the interface between iudium and antimony at 100°C is greatly increased when a composite electrode of indium electrode -posited on antimony is made the cathode in an electrolytic cell. The amount of indium antimonide formed during electrolytic treatment at constant potential appeared to he proportional to the square root of time, but the scatter of the data, particularly at long times, makes it impossible to state this conclzlsi1:ely. The rate constant for the electrochemical synthesis was estimated to he 1.5 x 10-12 sq cm per sec. A similar- set of experiments was conducted in the absence of an applied potential but under otherwise similar conditions. The rate constant lor the thermal synthesis was less than 2 x 10-14 sq cm per, sec, at least two orders of magnitude less than obtained during electrolytic treatment. In a series of electrochemical studies it was observed that intermetallic compounds formed on the surface of polarized electrodes.1'2 The possibility of using this technique for the electrochemical preparation of intermetallic compounds was investigated and subsequently applied to the synthesis of the semiconducting III-V compounds. Gallium antimonide, indium arsenide. indium antimonide, and indium bismuthide were successfully formed by electrodepositing the Group III element from a boiling acid solution onto an electrode made of the Group V element. The following kinetic studies were undertaken on indium antimonide to obtain quantitative information on the rate of formation of this representative III-V compound under a potential gradient. EXPERIMENTAL The electrolytic cell for these experiments was a modified, three-neck, round-bottom, 500-ml distillation flask. Sealed into the side of the flask was a Luggin probe which monitored the surface of the working electrode and extended out of the flask to a small reservoir containing a saturated calomel electrode. The counter electrode was platinum. The three electrodes were connected to a Wenking po-tentiostat which maintained a preselected constant potential near the surface of the working electrode with reference to a saturated calomel electrode. All potentials noted in this paper are with reference to a saturated calomel electrode at 45° ± 5°C. The potential and the current were both monitored using Sargent Model MR recorders. The antimony electrodes were cast in graphite molds to form spheres about 15 mm in diameter with a shank 6 mm in diameter and 10 mm long. A heavy copper wire (12B & S gage) was soldered to this shank. Collodion was applied for protection to the shank and the connecting part of the copper lead. A snug-fitting O-ring was slipped over the shank and the electrode was then fitted into a teflon holder such that only the spherical portion was exposed. The electrode surfaces were cleaned and chemically polished prior to assembly and introduction into the electrolyte by etching in a modified CP-4 solution (50 parts glacial acetic acid, 10 parts concentrated nitric acid, 2 parts 48 pct hydrofluoric acid). The electrolyte was 10-2 M In+3 in 1 MH2So4 and its temperature was held constant by refluxing. The reflux condenser was open to the atmosphere and no temperature correction was made for changes in barometric pressure. The indium concentration in the electrolyte was checked from time to time by the analytical method outlined below for the determination of the amount of indium antimonide formed electrochemically. A schematic of the recorded potential is shown in Fig. 1. At point A the antimony electrode was introduced into the cell and the open-circuit potential recorded. At point B the potentiostat, preset at the desired potential, was switched on. It was switched off at point C and the potential fell to the open-circuit value of the electrodeposited indium. The

Jan 1, 1965

By A. L. Holmes

Significant technologic advances were made in open pit mining during 1973. The industry faced mounting problems on one front where expansion of stripping activities encountered enlarged public resistance and on another where manpower and materials were in short supply. These challenges, along with the challenge and opportunity to meet the increased demand for mining products including materials for energy production, placed a premium on technical developments and their application. The demands on technology also included the providing of facilities and methods to economically extract minerals from deposits of lower grade, lesser accessibility, and where other uses of land approached the value of its minerals. Detection of Failures in Slope Walls The Bureau of Mines has undertaken research directed towards providing a mine operator with the opportunity to take corrective action before a potential slide becomes a problem.

Jan 2, 1974

By Alton B. Cook, G. B. Spencer, F. P. Bobrowski

In estimating production gas/oil ratios and oil recoveries from reservoirs containing highly volatile oils it is highly important to include condensate that may be recovered from the gas produced from the reservoir. The volume of the hydrocarbon liquid condensed from the production of the solution gas that has been liberated. in some reservoirs may equal or even exceed the volume of recoverable stock-tank oil as estimated by present methods. The usual procedure1, 2, 3 in estimating future reservoir performance includes use of relative permeability data of the reservoir rock to gas and oil and includes material-balance calculations utilizing data on the volume of the reservoir fluids, oil and gas production and reservoir pressure decline, and data on the physical properties of the initial reservoir fluids. The inaccuracy in the procedure results from the false assumption that all of the free or liberated gas that enters the well bore of reservoirs containing highly volatile oils remains in the gaseous phase as it is produced. This paper presents a method for estimating future reservoir performance and oil recoveries based on special labora. tory analyses of reservoir-oil samples and recognition of the additional volume of hydrocarbon liquid that will be recovered at various stages of depletion from a solution.gas.drive reservoir. The method also includes calculations of the volume and composition of the hydrocarbon liquids that can be recovered by processing the produced gas in a natural-gasoline plant. The development of the method resulted from a study of laboratory analyses of reservoir samples and of field data obtained from two reservoirs containing oil of the highly velatile type. Relatively high pressures and temperatures prevail in oil reservoirs discovered at the greater depths of present-day drilling. The contained fluids may have high saturation -Dressures and large volumes of gas in solution. The oils and gases under these conditions may be almost identical in compositions and densities.4,5 Also, engineers have noted that, for a number of oil reservoirs and especially the deeper reservoirs, the API gravity of the stock-tank oil increaees as the production gas/oil ratios increase. They attributed this increase in API gravity of the stock-tank oil to the formation of condensate as the liberated gas in the reservoir is being produced. SOURCE OF DATA FOR CALCULATIONS Subsurface oil samples and well-test data were obtained from the E. Constantin-Lambert Well No. 1 in the Elk City Field, Okla., to demonstrate the need for and a method of calculating future reservoir performance when consideration is given to the recoverable hydrocarbon liquid from the production of solution gas that has been or will be liberated in a reservoir. The Lambert well is located in C, SW 1/4, SW 1/4, Set- 18, T-l0-N, R-20-W, Washita County, Okla. At the time of completion it was on the east edge of the development and Was producing from conglomerate through 30 perforations in the 5 1/2-in. casing at a depth of 9,859 to 9,864 ft. The well Was completed on July 9, 1949, and subsurface oil samples were obtained July 29 and August 1, 1949. Production gas/oil ratio data were obtained during the operation in series of two Separators at high and low-pressures of 314 and 44 psia, respectively, and at an average temperature of approximately 60°F. The flowing bottom-hole pressure at the time of sampling was 3,934 psis. The static bottom-hole pressure was not obtained at the time of sampling, as the well could not be shut in long enough for testing because gas produced from the well was used for fuel at an offset drilling well. However, the initial reservoir pressure was calculated to be 4,364 psia from knowledge of pressure gradients in other wells in the field and the depth of the casing perforations in the Lambert NO. 1 well.

Jan 1, 1951

By F. P. Bobrowski, G. B. Spencer, Alton B. Cook

In estimating production gas/oil ratios and oil recoveries from reservoirs containing highly volatile oils it is highly important to include condensate that may be recovered from the gas produced from the reservoir. The volume of the hydrocarbon liquid condensed from the production of the solution gas that has been liberated. in some reservoirs may equal or even exceed the volume of recoverable stock-tank oil as estimated by present methods. The usual procedure1, 2, 3 in estimating future reservoir performance includes use of relative permeability data of the reservoir rock to gas and oil and includes material-balance calculations utilizing data on the volume of the reservoir fluids, oil and gas production and reservoir pressure decline, and data on the physical properties of the initial reservoir fluids. The inaccuracy in the procedure results from the false assumption that all of the free or liberated gas that enters the well bore of reservoirs containing highly volatile oils remains in the gaseous phase as it is produced. This paper presents a method for estimating future reservoir performance and oil recoveries based on special labora. tory analyses of reservoir-oil samples and recognition of the additional volume of hydrocarbon liquid that will be recovered at various stages of depletion from a solution.gas.drive reservoir. The method also includes calculations of the volume and composition of the hydrocarbon liquids that can be recovered by processing the produced gas in a natural-gasoline plant. The development of the method resulted from a study of laboratory analyses of reservoir samples and of field data obtained from two reservoirs containing oil of the highly velatile type. Relatively high pressures and temperatures prevail in oil reservoirs discovered at the greater depths of present-day drilling. The contained fluids may have high saturation -Dressures and large volumes of gas in solution. The oils and gases under these conditions may be almost identical in compositions and densities.4,5 Also, engineers have noted that, for a number of oil reservoirs and especially the deeper reservoirs, the API gravity of the stock-tank oil increaees as the production gas/oil ratios increase. They attributed this increase in API gravity of the stock-tank oil to the formation of condensate as the liberated gas in the reservoir is being produced. SOURCE OF DATA FOR CALCULATIONS Subsurface oil samples and well-test data were obtained from the E. Constantin-Lambert Well No. 1 in the Elk City Field, Okla., to demonstrate the need for and a method of calculating future reservoir performance when consideration is given to the recoverable hydrocarbon liquid from the production of solution gas that has been or will be liberated in a reservoir. The Lambert well is located in C, SW 1/4, SW 1/4, Set- 18, T-l0-N, R-20-W, Washita County, Okla. At the time of completion it was on the east edge of the development and Was producing from conglomerate through 30 perforations in the 5 1/2-in. casing at a depth of 9,859 to 9,864 ft. The well Was completed on July 9, 1949, and subsurface oil samples were obtained July 29 and August 1, 1949. Production gas/oil ratio data were obtained during the operation in series of two Separators at high and low-pressures of 314 and 44 psia, respectively, and at an average temperature of approximately 60°F. The flowing bottom-hole pressure at the time of sampling was 3,934 psis. The static bottom-hole pressure was not obtained at the time of sampling, as the well could not be shut in long enough for testing because gas produced from the well was used for fuel at an offset drilling well. However, the initial reservoir pressure was calculated to be 4,364 psia from knowledge of pressure gradients in other wells in the field and the depth of the casing perforations in the Lambert NO. 1 well.

Jan 1, 1951

By H. Landssberg

Subsidence caused by mining operations has been a matter of interest for the mining engineer for just 111 years, since the Belgian committee for study of subsidence in the city of Liege submitted its first report in 1825. This interest is fairly expressed in the enormous amount of literature that has since appeared on this subject. A bibliography, probably far from being complete, which preceded this study as a preliminary survey, comprises more than 800 titles. In spite of this fact the problem remains today as acute as it has ever been. The questions of as good a recovery as possible of the national resources, the safety of the operations, and the protection of private and public property are the important angles from which to look at the problem. The Problem To systematize an investigation regarding the effects of mine excavations two different aspects have to be dealt with: (1) the subsidence of the immediate roof above the workings, affecting the safety of the workers and the progress and efficiency of the operations; (2) the subsidence of the surface, which is also, from the point of time, the second event. The immense importance of surface subsidence as regards the impairment of surface structures of every kind in a mining area is self-evident. Both effects result from reactions of the strata overlying the excavations and they depend mainly on the extent of the excavations and the structure and geological condition of the strata. It has been stressed repeatedly, in this country principally by G. S. Ricel,† that for the understanding of the phenomenon of subsidence accurate surveys are the most urgent necessity. In the past, however, at least in the normal course of mining operations, these surveys have been very crude. The control of the roof in the mine is left to the observation of the behavior of the timber, warning cracks and sounds in roof and walls and to the general judgment and experience of the worker and his supervisors. In any given case this may or may not be sufficient to prevent fatalities but certainly it does not give any accurate information as to what is happening in roof and strata. On the surface, principally in endangered areas, surveys have been conducted more frequently, but also in this case usually weeks or even

Jan 1, 1936

By H. Landssberg

Subsidence caused by mining operations has been a matter of interest for the mining engineer for just 111 years, since the Belgian committee for study of subsidence in the city of Liege submitted its first report in 1825. This interest is fairly expressed in the enormous amount of literature that has since appeared on this subject. A bibliography, probably far from being complete, which preceded this study as a preliminary survey, comprises more than 800 titles. In spite of this fact the problem remains today as acute as it has ever been. The questions of as good a recovery as possible of the national resources, the safety of the operations, and the protection of private and public property are the important angles from which to look at the problem. The Problem To systematize an investigation regarding the effects of mine excavations two different aspects have to be dealt with: (1) the subsidence of the immediate roof above the workings, affecting the safety of the workers and the progress and efficiency of the operations; (2) the subsidence of the surface, which is also, from the point of time, the second event. The immense importance of surface subsidence as regards the impairment of surface structures of every kind in a mining area is self-evident. Both effects result from reactions of the strata overlying the excavations and they depend mainly on the extent of the excavations and the structure and geological condition of the strata. It has been stressed repeatedly, in this country principally by G. S. Ricel,† that for the understanding of the phenomenon of subsidence accurate surveys are the most urgent necessity. In the past, however, at least in the normal course of mining operations, these surveys have been very crude. The control of the roof in the mine is left to the observation of the behavior of the timber, warning cracks and sounds in roof and walls and to the general judgment and experience of the worker and his supervisors. In any given case this may or may not be sufficient to prevent fatalities but certainly it does not give any accurate information as to what is happening in roof and strata. On the surface, principally in endangered areas, surveys have been conducted more frequently, but also in this case usually weeks or even

Jan 1, 1936

By R. S. Shoemaker, F. W. McQuiston

SOUTH AFRICAN MILLING PRACTICE All modern South African gold plants operate primarily on the principle of exposing the gold particles in the ore by fine grinding and then cyaniding the total pulp. Although there are minor variations and occasional depart- ures from established practices among the fifty gold mines in South Africa, the normal plant operations proceed as follows. After removal of waste rock by hand sorting (15Y0 on average) the ore is crushed in cone crushers to minus 1/2 inch and then ground to approximately 75% minus 200 mesh by milling with either rod, ball or pebble mills as primary units and pebble mills for the secondary grind. Classification in both circuits is almost invariably conducted with 20" cyclones of 30" or larger diameter. Gravity concentration in the milling circuit followed by barrel amalgamation of the concentrates is practiced in 70Y0 of the plants, particularly where the ore grade is high. A slightly better overall recovery is obtained than with direct cyanidation, but additional handling is involved. Johnson cylinder s , plane tables or belt concentrators, all lined with suitable types of molded rubber riffles, are used for this purpose. At all mines, cyanidation is the main process, usually conducted by continuous treatment in Pachuca tanks and pulp separation with rotary drum filters. Cyanide solutions contain about 0.0 1570 NaCN and require a protective alkalinity of 0.02070 CaO. Precipitation of the gold from cyanide solution is exclusively by zinc dust and lead nitrate using the Merrill-Crowe system in conjunction with Stellar pressure filters. The zinc precipitate is smelted, generally after a preliminary concentration by sulfuric acid, in electric furnaces, mostly submerged arc types, with a silica and borax flux, yield- ing a bullion of 8870 gold, 9% silver, and 370 base metals. The gold content of the ore varies between 0.20 and 1.0 oz Troy per short ton and extraction efficiency ranges from 9570 to 9870. In general, 4070 of the gold output is recovered by amalgamation and 6070 by cyanidation; but in some cases, it is entirely by cyanidation. Flotation has not been adopted for gold extraction as it has not proved as efficient as cyanidation. It is, however, often applied to ores containing higher than 1% sulfur for the recovery of pyrite for sulfuric acid production. On the eastern side of the Witwaters rand Basin, "run-of -mine milling” was introduced in 1960 and in three of the four mills in this area both sorting and crushing have been eliminated. The ore received from the shafts is conveyed to storage silos and then fed by Williamson automatic feed controllers to pebble mills ranging from 12 to 14 feet diameter, and 16 to 20 feet long. The pebble mills operate in closed circuit with 42 inch cyclones and the slime produced is thickened and cyanided in the conventional manner. No selective

Jan 1, 1975

By Stanley J. LeFond, Langtry E. Lynd

Elemental titanium has become famous as a space age metal, because of its high strength/ weight ratio and resistance to corrosion. However, the major use is in the form of titanium dioxide pigment, which because of its whiteness, high refractive index, and resulting light-scattering ability, is unequaled for whitening paints, paper, rubber, plastics, and other materials. A relatively minor use is in welding rod coatings, in the form of the mineral rutile. United States consumption of titanium dioxide in concentrates for these applications in 1982 was as follows: pigments, 630,000 st; titanium metal, 31,000 st; and welding rod coatings, 5,000 st. The only commercially important titanium ore minerals at the present time are ilmenite and its alteration products, and rutile. Titanium was discovered by Gregor in 1790, as a white oxide which he recovered from menaccanite, a variety of ilmenite occurring as a black sand near Falmouth, Cornwall. Barksdale (1966) stated that the fundamental chemical reactions on which the present day titanium industry is based were known before 1800, although it was not until 1918 that these pigments were available commercially on the American market. Pings (1972) outlined the early history of the titanium industry in the United States, referring to the work of Guise (1964) and others: Mining of titanium minerals in the United States began sometime between 1880 and 1900, in Chester County, Pennsylvania. Small quantities of rutile were also produced during that time in North Carolina and Georgia. In 1901 rutile was mined from a deposit near Roseland, VA, and was used in making titanium chemicals and for coloring ceramics. Ilmenite in the deposit was produced as a separate item in 1913, and rutile and ilmenite were obtained from this deposit through 1921. The mining of titanium bearing beach sands began in 1916 near Mineral City and Pablo Beach, FL, for the purpose of making titanium tetrachloride to be used in tracer bullets, flares, and smokescreens. The titanium pigment industry was founded in 1918. By 1928 a large part of the domestic production of rutile, ilmenite, and zircon came from Florida. However production ceased in 1929 in Florida with the mining of newly discovered deposits in Virginia which were mined until 1968. The discovery of new deposits in Florida, and the development of better mining and concentrating methods for low-grade sands, led to a return of activities in this area. The large deposits near Tahawus, NY. were brought into production in 1942 by National Lead Co. (now NL Industries, Inc.), and by 1949 this company was the leading producer of ilmenite in the world. In 1948 the extensive deposits of ilmenite and ilmenite-bearing iron ores were discovered in eastern Quebec. The large Trail Ridge sand deposit in Florida was discovered by E. I. du Pont de Nemours & Co., Inc. geologists in cooperation with the US

Jan 1, 1983

By S. P. Kinney

Sulfur has been one of the most troublesome elements encountered since the earliest days of iron smelting, and this problem will become of increasing importance as the higher sulfur coke is used, because of the rapidly diminishing supply of low-sulfur coals suitable for the manufacture of metallurgical coke. The deleterious effect of sulfur in iron and steel is well known; therefore, except in special cases, it is desirable to make the iron produced by the blast furnace as low in sulfur as possible. Sulfur enters the furnace in all of the raw materials, but principally in the coke. It comes out of the blast furnace distributed between the iron and the slag; very little passes out of the furnace with the gases. The mechanism of the reactions that cause the sulfur of the coke to pass into the slag and iron has not been studied to any great extent, although the character of the end products, and the conditions controlling the distribution of the sulfur between the iron and slag, are fairly well known. In the iron, the sulfur occurs as ferrous sulfide; or manganese sulfide in case of iron high in manganese. In the slag, the sulfur is present mostly as calcium sulfide. The presence of free sulfur1 and sulfates in blast-furnace slags is to be accounted for on the basis of oxidation of the calcium sulfide after the slag is tapped. The generally accepted reaction for the relation between the ferrous sulfide in the iron and in the coke, and the calcium sulfide in the slag, is that given by Howe? FeS + CaO + CDFe + CaS + CO

Jan 1, 1923

By S. P. Kinney

Sulfur has been one of the most troublesome elements encountered since the earliest days of iron smelting, and this problem will become of increasing importance as the higher sulfur coke is used, because of the rapidly diminishing supply of low-sulfur coals suitable for the manufacture of metallurgical coke. The deleterious effect of sulfur in iron and steel is well known; therefore, except in special cases, it is desirable to make the iron produced by the blast furnace as low in sulfur as possible. Sulfur enters the furnace in all of the raw materials, but principally in the coke. It comes out of the blast furnace distributed between the iron and the slag; very little passes out of the furnace with the gases. The mechanism of the reactions that cause the sulfur of the coke to pass into the slag and iron has not been studied to any great extent, although the character of the end products, and the conditions controlling the distribution of the sulfur between the iron and slag, are fairly well known. In the iron, the sulfur occurs as ferrous sulfide; or manganese sulfide in case of iron high in manganese. In the slag, the sulfur is present mostly as calcium sulfide. The presence of free sulfur1 and sulfates in blast-furnace slags is to be accounted for on the basis of oxidation of the calcium sulfide after the slag is tapped. The generally accepted reaction for the relation between the ferrous sulfide in the iron and in the coke, and the calcium sulfide in the slag, is that given by Howe? FeS + CaO + CDFe + CaS + CO

Jan 1, 1923

By J. F. Smith, J. R. Ogren, N. J. Magnani

The uapor pressrcres of magnesium over binary alloys of magnesium with twelve of the yare-earth eletnetzts have been measured by the Knudsen effuion method in the temperature range 675° to 910°K. These vapor-pressure measurments were combined with data concerning the tevtrlitzul magnesium solubility and the vapor pressure of pure magnesinm to evaluale the standuvd free energies of pluase jormation. These free-etzergy values indicate that the CsCl structures of the heacy rave earths tend to be somewhat less stable than those of the light rare earths. This dif-]eying- behaviov covrelates with differences which have been obsevz~ed in other alloy systetns wherein a phuse appeurs, disappeavs, or changes crystal stvucture as the atomic number of the rare-earth com-ponent is changed. This behauior also appears to correlate with the struclurul rariations within the rare-earth elements themselves, and it is speculated that cariations in the spatial extent of the 4f orbitals are responsihle. STUDIES of the phase relationships and crystal structures in the binary systems between rare-earth metals (lanthanons) and magnesium are extensive but far from complete. However, the currently available information1-10 does produce a rather interesting pattern. This is illustrated in Table I. If one excludes europium and ytterbium from consideration because of their generally atypical behavior, it can be seen from the table that the phase relationships in the magnesium-rich regions show a distinctly different pattern for the lighter lanthanons as compared to the heavier lanthanons. For the lighter lanthanons, LnMg2 phases occur from lanthanum to gadolinium with the cubic MgCu2 structure, LnMg3 phases occur from lanthanum to terbium with the BiLi3 structure, and magnesium-rich phases occur from lanthanum to gadolinium with stoi-chiometries between Ln5Mg42 and LnMg12. In contrast, for the heavier lanthanons, those LnMg2 structures which have been examined have the hexagonal MgZn2 structure, LnMg3 phases have not been observed beyond terbium, and the magnesium-rich phases occur with the a manganese structure near a stoichiometry of Ln5MgZ4. The heavy lanthanon-magnesium systems thus appear to be analogous to the Y-Mg system""2 wherein YMg has the CsCl structure, YMg2 has the MgZn2 structure, and the region Y4Mgz5-Y5Mg24 has the a manganese structure, and no other intermediate phases are observed. Similarity in alloying behavior between yttrium and the heavy lanthanons occurs commonly, and on this basis it seems likely that LnMg2 phases will be found with the MgZn2 structure in the binary systems of dysprosium, thulium, and lutetium with magnesium when the appropriate investigations are made. In the case of the magnesium-rich phases of the lighter lanthanons, only the Ce-Mg phase relationships have been investigated thoroughly and in detail, and until similar investigations are made for the other systems there will remain questions as to which magnesium-rich stoichiometries represent equilibrium phases and what systematic variations occur in the sequence from lanthanum to gadolinium. Thus the data in Table I show that only the LnMg phases occur with the same crystallographic structure throughout the sequence from lanthanum to lutetium. It was speculated that the relative stability of these LnMg phases might vary from one lanthanon to the next in such a way as to presage the differences which occur among the more magnesium-rich lanthanon-magnesium phases. On this basis the present investigation of the thermodynamics of phase formation was Gndertaken for the LnMg phases. PROCEDURE AND RESULTS A generalized phase diagram for the lanthanon-rich portion of a lanthanon-magnesium alloy system is shown in Fig. 1 where ß represents a high-temperature bcc

Jan 1, 1968

By L. D. Tracy

On Aug. 5 and 6,1918, and Mar. 26, 1919, the writer made an investigation of the mine-water neutralizing plant at the Calumet mine of the H. C. Frick Coke Co. The object of this plant is to develop a process of treating the water pumped from the mines so that it may be rendered suitable for use at the power plants of the mines and also at the coke ovens; at the same time, eventually producing a byproduct which will have enough commercial value to provide a sufficient revenue to place the plant on a self-sustaining basis. The Calumet mine is situated in Mt. Pleasant Township, Westmoreland County, Pa., on a branch of the southwest branch of the Pittsburgh Division of the Pennsylvania Railroad. It is about 6 mi. (9 km.) southeast of Greensburg, the county seat of Westmoreland County. The coal, which is the Pittsburg or Connellsville seam, lies at a depth of about 200 ft. (60 m.) and is brought to the surface by means of a shaft. The output of the mine averages 200,000 tons of coal annually, all of which is made into coke, either at the ovens, at the mine, or at byproduct ovens. There are 260 coke ovens at the mine. The continued development of the coal fields of Pennsylvania and the increased use of electric power in the operation of the mines has brought the problem of an increased water supply for the plants to the attention of the coal operators. This is especially true in the Connellsville coking region, where large quantities of water are used in quenching the coke at the ovens. Many of the streams receive the drainage from the mines; and as this water is highly acid and contains sulfur in various forms, some method of treatment is necessary to render it suitable for use at the plants of the mines. With this end in view, the H. C. Prick Coke Co., about 4 years ago, installed at its Calumet mine a plant for experimental purposes, in an endeavor to develop a process that would provide a maximum amount of suitable water at a minimum cost. From a purely technical point of view, the result of these experiments has been encouraging. The company is now endeavoring to place the plant on a commercial basis.

Jan 1, 1922

By William Plank

IN PAST YEARS, engineering educators and others have been able to study the problems relating to en-gineering education in the United States with only inadequate and, frequently, inaccurate data at their command. For the first time there is now available fairly full and accurate information on this subject, gathered and compiled by the Board of Investigation and Coordination of the Society for the Promotion of Engineering Education. This board, of which W. E. Wickenden is the director, has for the past four years been carrying out fact-finding investigations into "the objects of engineering education and the fitness of the present day curriculum," under a grant of funds from the Carnegie Corporation of New York. Twelve bulle-tins have already been published by the board and others are in the process of preparation. The studies made, thus far, have been of the various phases of engineering education in general as well as of the major branches of engineering. Within the past year. the board has completed a study of mining engi-neering education by means of a questionnaire sent to members of the Institute. A special committee, con-sisting of Charles E. Locke, Allen H. Rogers and the writer, cooperated with the board in drafting certain parts of the questionnaire and in selecting the mailing list. Similar studies have been made through the mem-bers of the four other national societies. The results of these studies have been published only in mimeo-graphed form, therefore, in order to place the data before the members of the Institute an incomplete sum-mary of the replies to the A. I. M. E. questionnaire is here given. The full report will be available for distri-bution at the annual meeting in February. The questionnaire was sent to 306 members of the Institute, a proportion about equal to the proportion of the membership of the other national societies can-vassed; 152 members replied to the questionnaire, 55 per cent of whom had received college degrees in some branch of engineering connected with the mineral in-dustry. Forty-seven educational institutions were rep-resented in the replies. Seventeen different positions were held by the members who replied, with 24 con-sulting engineers at the head of the list, 20 managers, 16 superintendents, 11 presidents, 10 professors, 6 deans, and others.

Jan 1, 1928

By C. W. Spencer, J. Singer

A PARTIAL phase diagram for the As-Te system is given in Hansen.' The only compound reported is As2Te3, melting at 362°C. Stoichiometric quantities of reagent-grade elements were reacted in evacuated quartz and directionally cooled. The resulting ingot consisted of very thin threadlike crystals from which only very small single-crystal fragments were isolated. A powder diffraction diagram disclosed nonisomorphism with the analogous V-VI compounds insofar as these have been reported; Sb2S3, As2S3, Bi,S,, and Bi2Te3 data in the ASTM index of powder patterns, together with the single-crystal data on Sb2Se3,2 were used for the com- parison with the observed spacings. Single-crystal data confirmed the uniqueness of the As2Te3 structure. Single-crystal Weissenberg diagrams have so far yielded the following data: As2Te3 is monoclinic, space group C-m (OkO data still lacking), a = 14.4A, b = 4.05A, C = 9.92A, ß = 97". The cell volume is about 5802. The set of isomorphous ortho-rhombic cells of Sb2Se3, Sb2S3, and Bi2S, are apparently related to As,Te, in having one lattice constant close to 4.0 and with cell volumes as large as 540A8. Assuming Z = 4 for As2Te3 also, the density is calculated as 6.1 which agrees well with a roughly determined value of 6.0. A complete structure analysis is under way.

Jan 1, 1956

By W. K. Tony Seiler

Further development of mechanical boring machines for hard and abrasive rocks will be effected by the development of more efficient rock cutting tools or the evolution of entirely new rock excavating principles. Presently the cutting tools suitable for extremely hard rocks and successfully and economically used with raise and tunnel boring machines are tungsten carbide insert big hole cutters. This paper explains the design, rock cutting principles, and actual boring operations to illustrate the capabilities and applications of tungsten carbide (TC) insert cutters. While the rate of borehole advance may fall short of the rapid excavating results achieved with soft rock boring machines, the cutter described in this paper may prove to be the most suitable tool in hard rock excavation for many years to come. DEFINITION OF HARD ROCK Existing bored excavations in hard abrasive rocks are proof of the economic application of new methods and mechanical rock boring in the mining industry. Most of the experience in cutting hard to extremely hard rocks has been gained in raise boring where relatively short and small diameter openings are bored. This poses a lesser risk regarding cutter cost than a long and large diameter tunnel and has therefore promoted the testing of various cutter products. Many types of rocks and geologic conditions were en- countered and actual test data was recorded in materials of up to 100,000 psi uniaxial compressive strength. To clarify the term hard to extremely hard, a 1970 interpretation of rock strength which was recently used is adopted and expanded in this paper.

Jan 1, 1971

By M. King Hubbert

DURING the past summer the writer was asked by the Illinois State Geological Survey to make a study of some of its economic geological problems with regard to the applicability of geophysical methods of prospecting to their solution. The following four problems were sug-gested for investigation: (1) the fluorspar area of Southern Illinois, (2) oil structures in the south central part of the state, (3) the lead and zinc-bearing area of northwestern Illinois, and (4) the water supply and gravel deposits of the glacial drift. The prime requirements were to find a means of obtaining a maximum of useful information with a fairly modest outlay of expenditure for technical staff and equipment. The method of procedure adopted was that of making a preliminary study of each of the problems named by means of available office data and published reports with supplementary field reconnaissance where necessary.

Jan 1, 1932

By L. A. Panek, F. D. Wang, M. C. Sun

A method of stability analysis of underground opening by the limiting equilibrium approach is presented. The Coulomb shear failure criterion is employed to find possible fracture surfaces and to evaluate the shear strengths along them. The normal stresses required for the calculation of shear strength, and the shear stresses for the calculation of total shear force along the fracture surfaces, are obtained by the finite-element method of plane-strain analysis. The factor of safety against Coulomb shear failure is calculated as the ratio of the shear strength to the shear force along a fracture surface, similar to the practice in slope stability analysis. Four shapes of openings are analyzed, with three ratios of horizontal lithostatic stress and four coefficients of internal friction. The critical fracture surfaces found by this method of analysis are consistent with the arching of roofs and slabbing of ribs commonly observed.

Jan 1, 1972

By M. T. Hepworth, W. B. Sample

HYDROGEN solubility and linear contraction measurements were made at constant temperature on an alloy of titanium of constant oxygen-to-titanium molal ratio but variable hydrogen content. A cylindrical specimen of titanium (0.25 by 1.6 in.) containing 0.75 at. pct 0 and less than 0.03 at. pct N was cast from a master button of iodide process titanium which had been alloyed with titanium dioxide. Four vacuum fusion analyses, which were made along the length of the cylinder after the hydrogen solubility studies were made, revealed a variation of oxygen content of less than 0.02 at. pct. The specimen was introduced into a quartz furnace tube, annealed and outgassedat 1050"~ for about 1 hr, and then held at 800" * 0.5" for about 30 hr, during which latter time experimental data were taken. The leak rate to the furnace chamber was not sufficient to contaminate the specimen during the run as determined by leak-rate studies and vacuum fusion analyses for oxygen and nitrogen before and after the runs. The furnace chamber was attached to a modified Sieverts apparatus used to introduce measured quantities of purified hydrogen to the specimen. A quartz pushrod transmitted changes in length of the specimen to a Chevenard dilatometer. The push-rod passed through a vacuum grease seal to the dilatometer which amplified motion of the rod by a factor of 319. During hydrogen addition, the pushrod did not contact the specimen. Measured quantities of hydrogen were added to the specimen and equilibrium hydrogen pressures recorded as a function of hydrogen content. The solubility data, which appear in Fig. 1, agree well with a separate investigation made with a different apparatus. The solubility limit of the hcp a phase appears as an abrupt discontinuity in slope at 3.4 at. pct H. The solubility plot has been extended as a dashed line at this discontinuity in order to emphasize the discontinuity. The hydrogen content at which bcc P appears is not clearly defined. An arrow indicates solubility data were taken upon hydrogen addition. Upon reaching the arbitrary maximum hydrogen content of the run, the quartz pushrod was pressed against the specimen in order to record the change in length with hydrogen removal. A pressure of about 100 g per sq cm was required to overcome the friction of the vacuum seal in order to obtain reproducible linear contraction data. The contraction ratio ~2/1", change in length divided by original length, was set equal to zero for the maximum hydrogen content. The relative contraction of the specimen was observed upon removal of hydrogen in the following manner. The system was opened to the pumps for a few seconds and an unknown quantity of hydrogen was removed. The system was then isolated from the pumps by closing a stopcock and allowed to return to equilibrium. When the temperature returned to 800°C, the pressure stabilized, and contraction ceased, measurements of contraction and pressure were made. The hydrogen content of the specimen was then deduced by measuring the equilibrium PIydrogen pressure and referring to the solubility plot. Linear contraction was then plotted against interpolated values of atomic percent hydrogen. The justification for this procedure is the established reversibility of the hydrogen equilibrium.' Uniaxial compression was assumed to have no effect on hydrogen pressure. The isothermal linear contraction data are plotted on Fig. 1. An arrow indicates data were taken upon removal of hydrogen. The solubility limits of the two phase a i /3 region can be identified by discontinuities ill slope of the dilatometric plot at 9.1 and 3.4 at. pct H, agreeing well with other studies.' Dashed extensions of the plots emphasize the discontinuities. Isothermal studies of expansion made upon hydrogen addition gave curves of much smaller slope and less pronounced discontinuities. A uniaxial compressive stress tends to accentuate volume changes in going from the more open bcc phase to the hcp phase.2 Incomplete data on ex-

Jan 1, 1962