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By Raymond Mancha

The use of blower fans and tubina- for auxiliary face ventilation is a somewhat controversial subject. Most authorities agree upon the advantages of this system over the maintenance of line brattice for dead-end ventilation. They also recognize the system's disadvantages. However, there is considerable disagreement as to the proper relation of the advantages to the disadvantages. It is the purpose of this report to present the opinions of four authorities of diversified occupation and permit the reader to form his own opinions on the subject. ORsErvers Carel Robinson is a mining engineer consultant of wide repute, who has a background of operating experience. Thomas G. Fear is a mine operator whose present position is that of chief engineer for the Hanna Coal Co. at St. Clairsville, Ohio. E. H. Denny is chief of the Coal Mine Inspection Division of the U. S. Bureau of Mines, and is a very able engineer whose past experience well qualifies him to appraise this problem. Cloyd M. Smith, editor of the periodical Mechanization, is a ventilation consultant. For a number of years he was a member of the Mining Department of the University of Illinois and has studied mine ventilation for many years. It is Mr. Robinson,s opinion that closely spaced breakthroughs, although conducive to low gas accumulation past the last open crosscut during the driving of entries, are difficult to maintain and are constant Sources of fugitive air. Jute or canvas brattice is suitable for entry driving with

Jan 1, 1944

By George W. Maynard

At the Pittsburg meeting of the Institute, May, 1879, I made the first announcement in America of the results obtained by Sidney Gilchrist Thomas and Percy C. Gilchrist, in their efforts to eliminate phosphorus in the manufacture of steel in the Bessemer converter and the open-hearth furnace.' The first published statement in an American newspaper was a reprint of the first Thomas-Gilchrist paper,which I sent to J. C. Bayles, at that time the editor. At the suggestion of many friends who were present at the Pittsburg meeting, and others who are cognizant of the beginnings of the process in the United States, and for the information of the younger generation of the iron and steel fraternity, I have thought it eminently proper that the history of the process in detail should be given where I made the first announcement and where the process has had its largest development. During my residence in England, from April, 1873, to February, 1879, and as a member of the Iron and Steel Institute since 1874, I was present at many of its meetings during those years. At nearly every meeting the burden of discussion was the question of the use of pig-iron containing phosphorus in the manufacture of steel by the Bessemer or the open-hearth process. In my biographical notice of Thomas: read at the New york meeting of the Institute, February, 1885, I show. that the working-out of the process was not a hap-hazard or accidental inspiration, but the culmination of many years of investigation of experiments and theories which had been carried on aid advanced by chemists and metallurgists at home and abroad.

Jan 1, 1911

By C. Upthegrove

DURING the past year considerable work dealing with physical properties of cartridge brass was done at the University of Michigan in cooperation with the Ordnance Department of the U. S. Army. This paper gives some of the data bearing on the effect of the anneal, previous to the final reduction or rolling, on the physical properties, particularly the hardness. Various phases of the subject of physical properties of cartridge brass have been presented by different investigators. Mathewson and Phillips1 refer to the work of Grard, in 1909, as the first systematic presentation of the relation between temperature-and time of anneal; changing of physical properties and microstructure, and the previous reduction by cold rolling. They discuss the relation between time and temperature of anneal and the previous reduction by cold rolling also; the relation between physical properties and grain size of annealed brass. The degree of deformation previous to the annealing was found to determine the temperature at which recrystallization and corresponding changes in physical properties would take place. Bassett and Davis,2 in establishing the relation between grain size and Brinell hardness; found the hardness for low-temperature annealing to be dependent on the previous degree of reduction, while for anneals above a certain temperature the hardness after the anneal was independent of the degree of reduction. Actual differences in hardness, due to the degree of reduction, disappear only on annealing at 600° C. or above; though the differences for metal subjected to different degrees of reduction and annealed at temperatures between 350° and 600° C. were found to be relatively small. In their determination of the relationship of grain size to Brinell hardness, Bassett

Jan 5, 1922

By Stuart E. Buckley, C. R. Hocott

The viscosity of the oil in the reservoir is one of the properties that influence its movement through the sand to producing wells. Measurements of viscosity, therefore, are pertinent to problems associated with well behavior and with the estimation of recoveries, and afford an indirect means for partial evaluation of various methods of controlling reservoir behavior. The effect of dissolved gases on the viscosity of crude oil has been determined,ls2 but no data have been published on the viscosity of representative samples of reservoir oils. This paper describes a simple instrument that has been used to determine the viscosities of a number of subsurface oil samples at the temperatures and pressures existing in the reservoirs, and presents the results of the determinations for typical fields. Construction oF the Apparatus The principal requirements of any instrument used for the examination of subsurface samples are that it be strong and simple both in design and in method of operation. Accuracy beyond that of the degree of reproducibility of subsurface Sam-~les from various wells in a reservoir or exceeding that of the common measure-merits of reservoir temperatures and Pressures is not required. Because of the expense of procuring subsurface samples, it is necessary also that the instrument operate on a relatively small fraction of a sample, leaving the remainder for other tests, and that there be few or no failures of the equipment to cause undue delay or loss of a sample. After preliminary experiments with a falling bullet, the results of which were not satisfactory, a simple viscosimeter was built of the rolling ball type first proposed by Flowers3 and later used by several investiga-tor. 5.8 The apparatus consists essentially of a removable, accurately bored cylindrical barrel of 1/4-in. nominal internal diameter, 8 in. long, in which a closely fitting steel ball rolls through the oil with the barrel inclined at a definite angle. The ball makes contact at one end of the barrel with ail insulated electrode, closing an electrical circuit, which actuates a buzzer. The meas-urements consist essentially in determining the time required for the ball to travel the length of the barrel. The details of the construction are shown in Fig. I. The barrel in which the ball rolls was made from a section of 25-caliber blank rifle barrel, specially bored to an exact uniform diameter and polished. The barrel slides snugly into a hole bored in a solid stainless-steel cylinder, an upper external shoulder of the barrel compressing a small spring, and is held in place by a hollow nut. The spring prevents the barrel from seating against the bottom of the bored hole in the cylinder, while narrow external longitudinal slots in the barrel permit fluid to flow around it and through the bottom. The upper part of the recess in the steel cylinder is enlarged to form a tapered chamber, which acts as a reservoir for the oil and affords space for agitation to ensure

Jan 1, 1941

By C. R. Hocott, Stuart E. Buckley

The viscosity of the oil in the reservoir is one of the properties that influence its movement through the sand to producing wells. Measurements of viscosity, therefore, are pertinent to problems associated with well behavior and with the estimation of recoveries, and afford an indirect means for partial evaluation of various methods of controlling reservoir behavior. The effect of dissolved gases on the viscosity of crude oil has been determined,ls2 but no data have been published on the viscosity of representative samples of reservoir oils. This paper describes a simple instrument that has been used to determine the viscosities of a number of subsurface oil samples at the temperatures and pressures existing in the reservoirs, and presents the results of the determinations for typical fields. Construction oF the Apparatus The principal requirements of any instrument used for the examination of subsurface samples are that it be strong and simple both in design and in method of operation. Accuracy beyond that of the degree of reproducibility of subsurface Sam-~les from various wells in a reservoir or exceeding that of the common measure-merits of reservoir temperatures and Pressures is not required. Because of the expense of procuring subsurface samples, it is necessary also that the instrument operate on a relatively small fraction of a sample, leaving the remainder for other tests, and that there be few or no failures of the equipment to cause undue delay or loss of a sample. After preliminary experiments with a falling bullet, the results of which were not satisfactory, a simple viscosimeter was built of the rolling ball type first proposed by Flowers3 and later used by several investiga-tor. 5.8 The apparatus consists essentially of a removable, accurately bored cylindrical barrel of 1/4-in. nominal internal diameter, 8 in. long, in which a closely fitting steel ball rolls through the oil with the barrel inclined at a definite angle. The ball makes contact at one end of the barrel with ail insulated electrode, closing an electrical circuit, which actuates a buzzer. The meas-urements consist essentially in determining the time required for the ball to travel the length of the barrel. The details of the construction are shown in Fig. I. The barrel in which the ball rolls was made from a section of 25-caliber blank rifle barrel, specially bored to an exact uniform diameter and polished. The barrel slides snugly into a hole bored in a solid stainless-steel cylinder, an upper external shoulder of the barrel compressing a small spring, and is held in place by a hollow nut. The spring prevents the barrel from seating against the bottom of the bored hole in the cylinder, while narrow external longitudinal slots in the barrel permit fluid to flow around it and through the bottom. The upper part of the recess in the steel cylinder is enlarged to form a tapered chamber, which acts as a reservoir for the oil and affords space for agitation to ensure

Jan 1, 1941

By C. F. Park

Hog Mountain is in the north central part of Tallapoosa County, Alabama, about 13 miles northeast from Alexander City. The Hog Mountain Mining and Milling Co. controls 1658 acres of land and is the only company operating in the district. The principal mine workings are in sections 10 and 15, T.24N., R.22E. The region has been visited by geologists many times, has been briefly described in several papers,' and mentioned in many others. No detailed map of the mine or vicinity has been published. The field work for this report was started in March, 1934, as part of the Public Works reemployment program. About a month and a half was spent mapping both the surface and underground geology. The mine owners and operators have cooperated in every way possible to facilitate the work. N. 0. Johnson, the mine engineer, E. W. Ellsworth, J. E. McCoy and J. G. Englebert have acted as assistants for part of the work. The University of Alabama and the State Geologist's office have aided materially by permitting free use of their libraries and laboratory equipment. Geography Hog Mountain forms a conspicuous ridge that rises to a height of a little more than 1000 ft. above sea level, and about 400 to 500 ft. above the adjacent country. The ridge is composed of granitoid intrusive rock and silicified schist that are more resistant to erosion than the surrounding softer schist. The topography of the area around the ridge is gently rolling and is typical of the subdued forms of the deeply eroded Southern

Jan 1, 1935

By C. F. Park

Hog Mountain is in the north central part of Tallapoosa County, Alabama, about 13 miles northeast from Alexander City. The Hog Mountain Mining and Milling Co. controls 1658 acres of land and is the only company operating in the district. The principal mine workings are in sections 10 and 15, T.24N., R.22E. The region has been visited by geologists many times, has been briefly described in several papers,' and mentioned in many others. No detailed map of the mine or vicinity has been published. The field work for this report was started in March, 1934, as part of the Public Works reemployment program. About a month and a half was spent mapping both the surface and underground geology. The mine owners and operators have cooperated in every way possible to facilitate the work. N. 0. Johnson, the mine engineer, E. W. Ellsworth, J. E. McCoy and J. G. Englebert have acted as assistants for part of the work. The University of Alabama and the State Geologist's office have aided materially by permitting free use of their libraries and laboratory equipment. Geography Hog Mountain forms a conspicuous ridge that rises to a height of a little more than 1000 ft. above sea level, and about 400 to 500 ft. above the adjacent country. The ridge is composed of granitoid intrusive rock and silicified schist that are more resistant to erosion than the surrounding softer schist. The topography of the area around the ridge is gently rolling and is typical of the subdued forms of the deeply eroded Southern

Jan 1, 1935

Hog Mountain is in the north central part of Tallapoosa County, Alabama, about 13 miles northeast from Alexander City. The Hog Mountain Mining and Milling Co. controls 1658 acres of land and is the only company operating in the district. The principal mine workings are in sections 10 and 15, T.24N., R.22E. The region has been visited by geologists many times, has been briefly described in several papers,' and mentioned in many others. No detailed map of the mine or vicinity has been published. The field work for this report was started in March, 1934, as part of the Public Works reemployment program. About a month and a half was spent mapping both the surface and underground geology. The mine owners and operators have cooperated in every way possible to facilitate the work. N. 0. Johnson, the mine engineer, E. W. Ellsworth, J. E. McCoy and J. G. Englebert have acted as assistants for part of the work. The University of Alabama and the State Geologist's office have aided materially by permitting free use of their libraries and laboratory equipment. Geography Hog Mountain forms a conspicuous ridge that rises to a height of a little more than 1000 ft. above sea level, and about 400 to 500 ft. above the adjacent country. The ridge is composed of granitoid intrusive rock and silicified schist that are more resistant to erosion than the surrounding softer schist. The topography of the area around the ridge is gently rolling and is typical of the subdued forms of the deeply eroded Southern

Jan 1, 1935

By C. F. Park

Hog Mountain is in the north central part of Tallapoosa County, Alabama, about 13 miles northeast from Alexander City. The Hog Mountain Mining and Milling Co. controls 1658 acres of land and is the only company operating in the district. The principal mine workings are in sections 10 and 15, T.24N., R.22E. The region has been visited by geologists many times, has been briefly described in several papers,' and mentioned in many others. No detailed map of the mine or vicinity has been published. The field work for this report was started in March, 1934, as part of the Public Works reemployment program. About a month and a half was spent mapping both the surface and underground geology. The mine owners and operators have cooperated in every way possible to facilitate the work. N. 0. Johnson, the mine engineer, E. W. Ellsworth, J. E. McCoy and J. G. Englebert have acted as assistants for part of the work. The University of Alabama and the State Geologist's office have aided materially by permitting free use of their libraries and laboratory equipment. Geography Hog Mountain forms a conspicuous ridge that rises to a height of a little more than 1000 ft. above sea level, and about 400 to 500 ft. above the adjacent country. The ridge is composed of granitoid intrusive rock and silicified schist that are more resistant to erosion than the surrounding softer schist. The topography of the area around the ridge is gently rolling and is typical of the subdued forms of the deeply eroded Southern

Jan 1, 1935

By Paul C. Ragland, P. Geoffrey Feiss

The Piedmont province of the southern Appalachians is the focus of interest for many exploration geologists. In the past, only those deposits with significant surface exposure were exploited. Thus, few deposits have been found and relatively little exploration has been conducted in recent years. Modern geochemical and geophysical techniques can alleviate this problem of concentrating on exposed ore bodies by allowing us to "look through" the soil and saprolite to detect the presence of significant mineralization at depth. This paper will attempt to evaluate the feasibility and effectiveness of several geochemical exploration techniques in the Piedmont province of Cabarrus and Stanly counties, N.C. The area chosen for study is shown in Fig. 1, lying almost wholly within the Mt. Pleasant quadrangle, N.C. The area is on the eastern boundary between the Charlotte belt, a zone of plutonic and intermediate grade metamorphic rocks, and the Carolina Slate belt, a series of complexly interbedded volcanic and sedimentary rocks of predominantly low metamorphic grade. The area is considered to be an early Paleozoic active, continental margin. 1 As is typical of most of the piedmont, outcrop is sparse. Figure 2 is a sketch map of the general geology of the area under study, showing the Charlotte belt rocks in the north-western quadrant and slate belt rocks to the east. Within the area are a number of old mines and prospects, the most famous of which are the Furniss and Phoenix mines in Cabarrus County. All are reported to have contained Au and Cu. Ag and Pb were reported from some. A summary of the deposits is given in Table 1.

Jan 6, 1979

By Philip H. Nelson, Richard Lingle

Vibrating wire stressmeters (VWS's) and borehole deformation gages (BDG) were deployed in two in-situ heater experiments at Stripa, Sweden to determine the thermally induced stress changes in the rock mass. The heater experiments ran for 18 months, including a six- month cool-down period after the heaters were turned off. Gages were installed in both horizontal and vertical boreholes and were subjected to temperatures ranging from 10°C to 120°C, depending upon the distance of a gage from the central heater. Most gages operated in a moist environment because groundwater flowed into many of the instrument boreholes during the experiments Of the 36 VWS's installed, six failed. Failures were attributed to corrosion of the vibrating wire due to moisture entering the gage body. Of the 30 BDG's installed at the beginning of the experiments, 22 failed, also as the result of water entering the gage body. Modification and reinstallation of the gages eliminated the problem of water infiltration, but much data from early stages of the experiments was lost due to gage failures. Calibration of the VWS in blocks of Stripa granite showed a lack of repeatability. Variability in calibration results are attributed to seating effects, to variations in the elastic modulus of the rock, and to changes in temperature. These three effects combined to produce an error judged to be approximately ±33% of the stress changes measured at Stripa. In contrast, the major source of error in determining stress with the BDG appears to be the uncertainty in rock modulus and thermal expansion coefficient. Sample calculations based on data acquired near the end of the experiments (during cool-down)

Jan 1, 1982

By P. Bolsaitis, L. Skolnick

Vapor pressures of silver over ternary alloys of six different copper to gold ratios have been measured by means of the Knudsen effusion technique. The data obtained in the temperature range of 1330° to 1375° have been used to estimate the integral excess free energies of the ternary alloys and the activities of copper and gold. The results compare favorably to the predictions based on the electron cell model of alloys recently formulated by the authors. THE orifice effusion method for measuring vapor pressures of materials in condensed phases was first introduced by knudsen, and has since been used extensively for the determination of thermodynamic properties of condensed phases. The basis of the measurement is the effusion, through a small orifice, of vapor in equilibrium with a condensed phase. Assuming free molecular flow into high vacuum, the vapor pressure, P (in mm Hg), of the effusing species is calculated from the following equation:' where w (g) is the weight of effusing species lost during a run, t (sec) the time length of the run, A, (sq cm) the area of the effusion orifice, T ("K) the temperature at which the run is conducted, M the molecular weight of the effusing species, and k the Clausing factor, a constant that corrects for deviations from free molecular flow caused by the finite thickness of the orifice walls.17 The determination of partial and integral thermodynamic variables from vapor pressure data of ternary alloys is possible only if the vapor pressures of all but one component are negligible or can be esti-

Jan 1, 1969

By E. H. Burdick

The difficulties inherent in table concentration operations as applied to gold, silver, lead and zinc ores, are accentuated in the scheelite mill, which has a flowsheet that is similar in general principles. The narrow "spread" in the specific gravity between scheelite and the usual gangue in which it occurs often makes its clean separation extremely difficult and in some cases impracticable. The problem is further complicated by the extreme friability of the mineral and its inordinate tendency to "slime," particularly where fine grinding is necessary and wet grinding methods are employed. The physical aspect of the occurrence of scheelite in the ores, the kind and character of the rock in which the mineral is present, its hardness, friability and the specific gravity of its constituents, as well as like characteristics of the associated minerals— pyrite, pyrrhotite, sphalerite, and others, all have a bearing on the successful milling of crude ores and the production of a concentrate that is marketable with minimum price penalty or none at all. Most tungsten deposits are considered low grade when the limiting factor of low percentage recovery by gravity methods is borne in mind. The great majority of deposits developed or in process of development carry from 0.4 to 1.0 per cent tungstic oxide. Ore carrying I per cent is considered good grade; 0.7 to 0.8 per cent, fair, and below that figure, low grade. Steady mill feed averaging upward of I .o per cent WO3 is exceptional. Inasmuch as buying specifications demand a 60 per cent W03 content, the mineral content of the ores as mined must be concentrated to at least that degree. A few companies have constructed chemical plants for the treatment of their complex concentrates and low-grade flotation product, but the smaller operator must rely on table concentration, borrowing the tools and to a large extent the methods of his predecessors in the gold, silver, lead and zinc mills. Whether these are the best tools and methods that can be devised is an open question. Except in rare instances, table concentration, however carefully conducted, does not yield a satisfactory final recovery of the mineral content in headings as indicated by chemical determinations of tungstic oxide content. A saving of 60 to 65 per cent is considered fair, and an average 80 per cent recovery, exceptional. Each scheelite ore body is a separate problem. Details of handling that give best results in one case may not be successfully operative at a property on the same contact zone and but a short distance removed. Supplementary treatment of tailings by flotation may be successful in producing a low-grade concentrate of around 15 per cent W03, which is adapted to further treatment chemically at a given property and entirely unsuccessful at another. This problem constitutes another of the unanswered questions. The following paragraphs relate solely to the beneficiation of scheelite ores by table concentration and supplementary methods.

Jan 1, 1943

By E. H. Burdick

The difficulties inherent in table concentration operations as applied to gold, silver, lead and zinc ores, are accentuated in the scheelite mill, which has a flowsheet that is similar in general principles. The narrow "spread" in the specific gravity between scheelite and the usual gangue in which it occurs often makes its clean separation extremely difficult and in some cases impracticable. The problem is further complicated by the extreme friability of the mineral and its inordinate tendency to "slime," particularly where fine grinding is necessary and wet grinding methods are employed. The physical aspect of the occurrence of scheelite in the ores, the kind and character of the rock in which the mineral is present, its hardness, friability and the specific gravity of its constituents, as well as like characteristics of the associated minerals— pyrite, pyrrhotite, sphalerite, and others, all have a bearing on the successful milling of crude ores and the production of a concentrate that is marketable with minimum price penalty or none at all. Most tungsten deposits are considered low grade when the limiting factor of low percentage recovery by gravity methods is borne in mind. The great majority of deposits developed or in process of development carry from 0.4 to 1.0 per cent tungstic oxide. Ore carrying I per cent is considered good grade; 0.7 to 0.8 per cent, fair, and below that figure, low grade. Steady mill feed averaging upward of I .o per cent WO3 is exceptional. Inasmuch as buying specifications demand a 60 per cent W03 content, the mineral content of the ores as mined must be concentrated to at least that degree. A few companies have constructed chemical plants for the treatment of their complex concentrates and low-grade flotation product, but the smaller operator must rely on table concentration, borrowing the tools and to a large extent the methods of his predecessors in the gold, silver, lead and zinc mills. Whether these are the best tools and methods that can be devised is an open question. Except in rare instances, table concentration, however carefully conducted, does not yield a satisfactory final recovery of the mineral content in headings as indicated by chemical determinations of tungstic oxide content. A saving of 60 to 65 per cent is considered fair, and an average 80 per cent recovery, exceptional. Each scheelite ore body is a separate problem. Details of handling that give best results in one case may not be successfully operative at a property on the same contact zone and but a short distance removed. Supplementary treatment of tailings by flotation may be successful in producing a low-grade concentrate of around 15 per cent W03, which is adapted to further treatment chemically at a given property and entirely unsuccessful at another. This problem constitutes another of the unanswered questions. The following paragraphs relate solely to the beneficiation of scheelite ores by table concentration and supplementary methods.

Jan 1, 1943

By P. Eadington

I feel sure that the apparent anomolies between his findings and ours arise as a result of the different experimental methods used. The modem oxygen electrode method he used is sensitive to nano moles of oxygen uptake whereas the method we used was only sensitive to micro moles at best. Furthermore, our experimental method did not permit measurements to be made in the first ten to fifteen minutes of reaction, the very time he is observing. Direct comparison of his data to ours is made difficult because of not knowing the specific area of the samples he used. However, we found that precipitation of PbS using sodium sulphide gave rise to samples of area approximately 30 m2 g - 1. Noticing the rapid decline in oxidation rate over ten minutes, as reported in Table 1, one can conclude that we could not measure the rate after ten minutes using our method. Taking the above area I estimate that at these rates only a small fraction of surface would be oxidised in a period of hours. I can only conclude that at some point a change in oxidation mechanisms occurs giving rise to a much faster rate such as we observed. Finally, I would like to comment on the apparent inertness of the homogeneously precipitated lead sulphide sample 11. This method of preparation we found to give specific areas of 20 to 30 times less than other methods and this would account for the very low oxidation rate.

Jan 1, 1982

By O. W. Simmons, L. W. Eastwood, C. M. Craighead

The results of a preliminary study of 113 ternary titanium-base alloys are described. The compositions investigated were as follows: 1. Ternary titanium-carbon alloys containing copper, silicon, vanadium, chromium, manganese, iron, or cobalt. 2. Ternary titanium-nitrogen alloys containing chromium. 3. Ternary titanium-chromium alloys containing additions of vanadium, molybdenum, tungsten, cobalt, or nickel. 4. Ternary titanium-manganese alloys containing additions of silicon, chromium, tungsten, or iron. Tensile properties, minimum bend radii, hardnesses, response to heat treatment and aging treatment, and phase relationships for these alloys were determined. THIS is the second in a series of papers describing some of the results of the exploratory work on titanium alloys being conducted at Battelle Memorial Institute for the Wright-Patterson Air Force Base. The work with the binary alloy systems has been described in a previous publication.' This paper describes ternary titanium-base alloys as follows: 1. Ternary titanium-carbon alloys containing copper, silicon, vanadium, chromium, manganese, iron, or cobalt. 2. Ternary titanium-nitrogen alloys containing chromium. 3. Ternary titanium-chromium alloys containing additions of vanadium, molybdenum, tungsten, cobalt, or nickel. 4. Ternary titanium-manganese alloys containing additions of silicon, chromium, tungsten, or iron. As the preparation and fabrication of the 0.5-Ib experimental titanium alloy ingots to 14-ga sheet, as well as the methods of testing used in this work, have been described in the first paper of this series, Titanium Binary Alloys, no further discussion of these techniques will be given. Ternary Alloys Containing Carbon The following alloys of titanium, containing carbon and one other metal, were investigated: 1. 0.25 pct carbon; 1, 2.5, and 5 pct copper. 2. 0.25 pct carbon; 1, 2, and 3 pct silicon. 3. 0.25 pct carbon; 1, 2.5, and 5 pct vanadium. 4. 0.25 pct carbon; 2.5, 3.5, 5, 10, and 15 pct chromium. 5. 0.5 pct carbon; 2.5, 3.5, and 5 pct chromium. 6. 0.25 pct carbon; 1, 1.75, 2.5, 3.5, 5, 7.5, and 10 pct manganese. 7. 0.5 pct carbon; 1.75, 2.5, 3.5, 5, 7.5, and 10 pct manganese. 8. 0.25 pct carbon; 0.25, 0.5, 1, and 2 pct iron. 9. 0.25 pct carbon; 1, 2, and 3 pct cobalt.

Jan 1, 1951

By G. R. Rubly, H. J. Steele

LOCATION AND HISTORY THE San Manuel property is in townships 8S and 9S, range 16E, Gila and Salt River Base and Meridan, State of Arizona. This area is in the Old Hat mining district, southern Pinal County, and is about 3;2 miles southwest of the town of Mammoth on the San Pedro River and one mile south of the Mammoth mine at Tiger, Arizona. The property consists of over 150 contiguous lode claims. The Old Hat district was prospected prior to the Civil War, but there was little or no production until 1881.1 The chief producers have been the Mammoth and Mohawk mines, now consolidated and operating as the St. Anthony Mining and Development Co., Ltd. Production to 1936 was $5,200,000, of which 83 pet was gold.2 Since 1940 the production has been chiefly lead and zinc, and some molybdenum and vanadium. There are a few small properties in the vicinity that have produced very minor tonnages of copper ore. In the San Manuel group there are claims which have been held continuously from 1906 to the present time, and at least two churn-drill holes were put down on or near the outcrop in 1917. No logs for these holes are available, but it is assumed that the grade of copper encountered was not sufficient to encourage further exploration. A small amount of ore has been shipped from open cuts on the San Manuel outcrop area, but there is no record of the tonnage or grade. It is estimated that not more than 5o tons were mined. These cuts, plus a few shallow shafts and some short adits indicate limited and unenthusiastic prospecting at San Manuel. In 1942, through the efforts of James M. Douglas, R. B. Giffin, Victor Erickson, and Henry W. Nichols, owners of the San Manuel group, the Reconstruction Finance Corporation and War Production Board authorized the United States Geological Survey to investigate the property, and by their recommendation, the United States Bureau of Mines was authorized to put down a limited number of churn-drill holes. The Bureau of Mines carried on drilling from November 1943 to February 1945. Seventeen holes were drilled, varying from 305 to 1990 ft in depth. The property was brought to the attention of Magma Copper Co. in June I944 and an option agreement was made with the owners. Subsequently, a group of claims lying north of the original group and held by the Apex Lead Vanadium Mining Corp., and a group to the east held by the Quarelli family, were optioned. A drilling program was laid out to conform to the Bureau of Mines pattern, and drilling started in December 1944. San Manuel Copper Corp. was incorporated September 1945, and has carried on the exploration program to the present time. GEOLOGY General The mineralized outcrop, chief copper mineral of which is chrysocolla, is a tri-

Jan 1, 1947

Economic Significance of High-grade Concentrates BY PAUL M TYLER AND CARLE R HAYWARD (Min & Met, Dec, 563 4000 words) Generally pyro¬mctallurgical methods yield a higher recovery but cost more per ton of ore treated Milling methods are inherently cheaper for the reason that they do not involve dissipa¬tion of heat energy in slag formation, ctc It is vaguely realized that the smelter man could do a better job if he were supplied with purer raw materials but hard¬headed mill men have been offered little inducement to do a really good job of cleaning concentrates To do this may involve some sacrifice in percentage yield and in mill capacity and unless there is a compensating saving in freight and smelter charges, it simply is not good business to go beyond a certain point in the way of making clean concentrate Opportunities exist for eliminating one or more steps in the expensive series of processes for recovering various metals, or at least reducing the volume of materials that has to be handled at the most costly steps The beneficiation of nonmetallic minerals likewise affords numerous examples of over-all economies obtainable through more refined methods of mechanical improvement All this leads to the conclusion that perfecting selective processes for isolating pure minerals (e g, galena) virtually free from other sulfides as well as gangue may be productive of industrial economies Conversely, cheapening smelting methods may invade the field of mechanical improvement of ores but, as Kiphng said, that is another story

Jan 1, 1937

By R. K. Matheson

THE Nivloc mine is 9 miles west of Silver Peak, Esmeralda County, Nevada. It has been operated by Desert Silver, Inc., since the summer of 1937. The cyanide mill treats 19o tons of silver-gold ore per day. In March of this year the main operations were about 2000 ft. west of the main shaft, which served as the downcast air passage for the mine. The mechanical blowers in use were sufficient to ventilate the west end at that time, but it was foreseen that as the mining area was extended ventilation would be an increasingly difficult problem, especially during the summer months. It was decided, therefore, to continue a raise from a point 100 ft. above the highest mining level (440-ft. level) to the surface; a distance of 443 ft. at approximately 65° From this point 40 ft. of drifting would be necessary to connect with a shallow shaft on the surface. (Fig. I.) All the raise was serviced from the 440-ft. level; costs and progress obtained in the initial 100 ft. are included in the following pages. CHOICE OF RAISE A raise in this locality would have four objects: (I) to provide an ample supply of fresh air to the working places; (2) to explore the vein from the highest mining level to the surface; (3) to provide waste fill for stopes in the area, and possibly provide a transfer for waste from the surface; (4) to provide an emergency exit in the west end of the mine. Before the mining of an ore shoot in the eastern part of the mine, a similar raise had been driven for purposes of ventilation and exploration. This raise and subsequent mining showed the vein to be noncommercial for a distance of about 250 ft. below the surface. However, in the area under operation, old surface workings showed occasional values. Thus from a development standpoint the raise was an excellent prospect. The raise chosen was a three-compartment, stulled raise having two chutes and a manway. The manway inside timber measured 4 ft. 8 in. by 4 ft. 6 in.; it carried air and water pipes, a ladderway and a slide for a timber skip. The two chutes would be used for drawing off the muck and the cleaning of the bulkhead, as well as for ore and waste passes, which would be especially useful for lateral exploration from the raise. The fairly large cross section of the raise (6 by 15 ft.) would provide a large quantity of waste for backfilling, and more could be obtained from a glory hole on the surface. TIME SCHEDULE As speed in completing the raise was the main requisite, three shifts were considered, but two shifts were decided upon when it was found that three would necessitate considerably larger fans than those available for clearing the raise. The main diffi-

Jan 1, 1942

The John Fritz Medal was awarded in January, 1916, to Dr. Elihu Thomson, "For -Achievements in Electrical Inventions, in Electrical Engineering, and in Industrial Development, and in Scientific Research." The medal will be presented to Dr. Thomson at a meeting, to be held in Boston on Friday evening, Dec. 8, 1916, in the Central Lecture Hall of the new buildings of the Massachusetts Institute of Technology. The program of the evening will include adresses by John J. Carty, Chairman of the Presentation Committee of the Board of Award, E. W. Rice, Jr., President, General Electric Co., and Dr. Richard C. Maclaurin, President, Massachusetts Institute of Technology. The presentation will be made by Dr. Charles Warren Hunt, Chairman of the Board at the time the award was made, and the ceremonies will conclude with the response of Dr. Thomson. The John Fritz Medal is awarded from time to time for notable scientific or industrial achievement, and was provided for in a fund subscribed in memory of the great engineering pioneer, John Fritz. The award of the medal is made by a permanent board composed of four members from each of four American National Engineering Societies, namely, the American Society of Civil Engineers, the American Society of Mechanical Engineers, the American Institute of Mining Engineers and the American Institute of Electrical Engineers. The members of the 1916 Board are: CHARLES WARREN HUNT, Representing the A. S. C. E., JOHN A.. OCKERSON, GEORGE F. SWAIN, CHARLES D. MARX. JOHN R. FREEMAN, Representing the A. S. M. E., AMBROSE SWASEY, JOHN A. BRASHEAR, FREDERICK R. HUTTON. ALBERT SAUVEUR, Representing the A. I M. E., E. GIBBON SPILSBURY, CHARLES F. RAND, CHRISTOPHER R. CORNING.

Jan 12, 1916