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By R. J. Stevens

THE Roan Antelope Smelter commenced operations in October, 1931. As originally designed, its equipment consisted of one reverberatory furnace, 120 X 25 ft, two Peirce-Smith converters 12 X 20 ft, and one straight line casting machine. Since that time the following additions have been made: One reverberatory furnace 120 ft X 28 ft (1934) One reverberatory furnace 95 ft X 28 ft (1943) Two 12 X 20 ft Peirce-Smith converters (1934 and 1938) One 13 X 30 ft holding furnace 6 (1938) One straight line casting machine and 2 ladle tilting quadrants (1934) The metallurgy of the smelting process is comparatively simple. However, there are several features of operation which are uncommon to most copper smelters: (1) The high grade of concentrate treated; this has always been about 50 pct copper. (2) The high flux burden on the charge. This is necessary because of the deficiency of bases'in the concentrate and the high alumina content of the concentrate. (3) The frequent necessity of adding coal to the furnace charge to control the matte grade. (4) The high grade of matte produced. This has led' to unusual converter problems. From the commencement of operations, the ore mined has come from the Roan Basin orebody. The concentrate produced from this ore consists mainly of chalcocite and shale with small proportions of other copper minerals. As mining operations extend to the Roan Extension orebody, the proportions of bornite and chalcopyrite in the concentrate will increase with a corresponding decrease in the copper content of the concentrate. Because of the concentrate grade the capacity of the reverberatory . furnaces in terms of tons of copper produced per ton of coal burned is high.. This ratio is usually over 2.2, and on especially favourable runs has reached 2.6. Reference to Table , shows that the iron content of the concentrate is unusually low. Only part of this iron is available for slag formation, the balance going to the matte. To make up this deficiency in bases, limerock is added to the furnace charge. This flux ensures a slag that is of the correct silicate degree, is sufficiently fluid, of low specific gravity, and it counteracts the thickening effect of the alumina present. An ample supply of flux is obtainable from Ndola, 2 2 miles distant by rail. Although the reverberatory slag has a high copper content, the slag fall is low and the copper loss in the slag now rarely exceeds 1.0 pct of the total copper charged. The blister copper shipped is of such purity that only one fire refining operation has been necessary to produce a wirebar with properties comparable to electrolytic copper. Bismuth has always been the most troublesome impurity and consequently the problem of its control in the finished product has been of prime importance. Practically none is removed in the reverberatory furnace. The bulk of the elimina-

Jan 1, 1947

Following closely Marcona Corp.'s announcement of its new Marconaflo process for transporting mineral slurries by ship (see pp. 96-97, Sept. 1969 [ ]), Midland-Ross Corp. (M-R) now heralds its metallized iron pellet process which supplements Oregon Steel Mills1 (Oregon Steel) new Portland, Ore., plant. Harry J. Bolwell, president of M-R describes the company's M-R Pellet as "the most exciting advance in steelmaking in a decade, one which will profoundly affect the industry." In fact, other knowledgeable industry spokesmen believe that with these developments the mini-steel plant era is now here and that this technical development along with the Marconaflo process will revolutionize iron ore shipments and steelmaking. The M-R president predicts that electric furnaces can account for 20% of the annual U.S. steel production by 1975, compared with 14% at the present time because of these developments.

Jan 12, 1969

By J. F. Abel, F. T. Lee

Subsidence is controlled by a complex com¬bination of mining and geologic factors. For example, a compilation of worldwide data shows that, as the percentage of shale in the overlying rock mass decreases and the amount of sandstone increases, the angle of draw (and the area affected by subsidence) decreases. Limestone in the over¬burden appears to cause a more than twofold decrease in the angle of draw compared to a like amount of sandstone. Increased amounts of sandstone were accompanied by a greater surface subsidence relative to the mining height. The total thickness of overburden did not appear to influence the subsidence magnitude above super-critical panels. The greater the thickness extracted, the smaller percentage of that thickness shows up at the surface as subsidence. The greater the percent of the seam extracted, the greater the subsidence reaching the surface. The maximum subsidence above room-and-pillar panels de¬pends on the pillar height and minimum width as well as the other factors listed.

Jan 1, 1984

By A. R. Calawa, T. C. Harman, M. Finn, P. Youtz

A study has been made of the growing, annealing, and diffusion parameters in PbSe, Pb1-ySnySe, and Pb1-xSnxTe. Single crystals of these materials have been grown using the Bridgman technique. For all of the above materials the as-grown crystals are p type with high carrier densities. To reduce the carrier concentration and increase the carrier mobility, the samples are annealed either isothermally or by a two-zone method. From isothermal anneals, the liquidus-solidus boundary on the metal-rich side of the stoichiometric composition has been obtained for some alloys of Pb1-xSnxTe and on both the metal- and seleniunz-rich sides for PbSe and alloys of Pbl-ySnySe. In Pbo.935 Sno.065 Se carrier concentrations as low as 5 x1016 Cm-3 and mobilities as high as 44,000 sq cm v-1 sec-1 at 77°K have been obtained. Inter diffusion parameters mere also studied. The ddiffusion experiments mere identical to the isothermal or two-zone annealing experiments except that the samples were removed prior to complete equilibration. The resulting p-n junction depths were determined by sectioning and thermal probing. Inter diffusion coefficients for various temperatures were calculated for both PbSe and Pb0.93Sn0.0,Se. RECENTLY, there has been considerable interest in the PbTe-SnTe and PbSe-SnSe alloys with the rock salt crystal structure. The unusual feature of these systems is the variation of energy gap EG with composition. Several investigations1-3 have shown that EG for the lead chalcogenides decreases as the tin content increases, goes through zero, and then increases again with further increase in tin content. The possibility of obtaining an arbitrary energy gap by selecting the composition is an especially attractive feature of these alloys for applications involving long-wavelength infrared detectors and lasers. In addition, some unusual magneto-optical, galvanomagnetic, and thermomag-netic effects should occur for alloys with low band gaps. If uncompensated low carrier density crystals can be obtained, then a small carrier effective mass, a large dielectric constant, and the resultant high carrier mobility should yield enormous effects at low temperature in a magnetic field. The relative variation of the energy gap with pressure should also be very large for these low gap materials. The primary purpose of this paper is to provide some information concerning the preparation of low carrier concentra- tion, high carrier mobility, and homogeneous single crystals with a predetermined alloy composition. I) DETERMINATION OF ALLOY COMPOSITIONS In all of the work described in this paper, the composition of lead and tin chalcogenides in the alloys was determined by electron microprobe analysis. Separate X-ray spectrometers are used to make simultaneous intensity measurements of the Pb La1 and Sn La1 lines emitted by the sample under excitation by a beam of 25 kev electrons focused to a spot about 2 µm in diam. These intensities are compared to the intensities of the same lines emitted by standards under the same conditions. The standards used are the terminal compounds of each pseudobinary system, i.e., PbTe and SnTe for Pbl-xSnxTe alloys, PbSe and SnSe for Pbl-ySnySe alloys. The composition of the sample is then obtained from theoretical calibration curves which relate the weight fractions of lead and tin in the alloy to the measured ratios of X-ray intensities for the sample and the standards. The lead and tin calibration curves for each alloy system were calculated by using corrections for backscattered electrons,4 ionization,5 and absorption,6 and assuming that the atom fraction of tellurium or selenium in the sample and standards is exactly +. Results obtained by using the microprobe are in good agreement with those obtained by wet chemical analysis. II) CRYSTAL GROWTH FROM THE VAPOR Early work on the vapor growth of PbSe was carried out by Prior.7 He used small chips of Bridgman-grown single crystals as the source material and frequently converted the whole charge of a few grams into one crystal. In the present work, vapor growth occurred using a metal-rich or chalcogenide-rich two-phased alloy powder as the source material. Small, nearly stoichiometric crystals are formed on the walls of the quartz tube. The procedure will now be described in detail. Initially, a 100-g charge containing (metal)o.51(chalco-genide)o 49 proportions or (metal)o.49(chalcogenide)o. 51 proportions of the as-received elements in chunk form are placed in a fused silica ampoule. After the ampoule is loaded, it is evacuated with a diffusion pump and sealed. The sealed ampoule is placed in the center of a vertical resistance furnace. The region containing the ampoule is heated to about 50°C above the liquidus temper-ature for the particular composition used. After about one-half hour at temperature, the elements are reacted and the molten material homogenized. The ampoule is quenched in water. The quenched ingot is crushed to a coarse powder for vapor growth experiments and to a fine powder for the isothermal annealing experiments which are discussed in a later section. Vapor growth experiments were carried out using the powdered, metal-rich or chalcogenide-rich alloys

Jan 1, 1969

By Sherwin F. Kelly

Twenty five years of exploration has shown that the "geophysical dollar" is worth $1780 in the Orange Free State, $1488 on the Witwatersrand, $85 in Sweden, $28,000 in the Transvaal and $3500 or more in the U.S.

Jan 6, 1951

By C. E. Coleman, D. Hardie, A. E. Wraith

A photoguaplric method of measuring crack velocities has been applied to an examilzation of- the effect of hydrogen on the impact properties of zirconium. Results indicate that the crack in hydrided zirconit travels at about 26 m per sec whereas that in the uacuum -annealed is dependent on the speed of the hammer. RECENT work on the effect of hydrogen on zirconium reveals that when hydrided zirconium is tested in slow bending the crack producing failure can be unstable. The mode of fracture seems to involve the crack linking up broken hydrides by a ductile mechanism in the zirconium matrix.2" In order to compare the fracture of zirconium with that of other metals which show unstable crack propagation, notably steel, the rate of the crack spread must be known. As the methods previously used for measuring crack growth are either unsuitable for the present work5-'' or very costly," a simple technique has been devised in which the maximum crack velocity is derived from a series of crack position-time measurements. EXPERIMENTAL PROCEDURE The experimental arrangement is shown schematically in Fig. 1. The flash unit12 was triggered when the Charpy hammer touched the specimen and the 6-psec flash of the lamp delayed by a preselected time interval in the range 100psec to 10 msec. The camera was left on open shutter during the test. From direct measurement on a calibrated photographic print, Fig. 2, the position of the crack and the specimen was found at a known time after impact and, from a series of such tests using an appropriate range of flash-delay times, the crack velocity was estimated. Preliminary experiments were carried out on mild steel above and below its transition temperature. Vacuum-annealed zirconium, and zirconium hydrided to 100 ppm H were then tested at 20" and 150°C. For comparison, Zr-2.6 pct Nb alloy (in the 0 + transformed /3 condition), vacuum-annealed or hydrided to 100 ppm H, was tested at 20 C. The chemical analyses of these materials are given in Table I. For the high-temperature tests a fine chromel-alumel thermocouple was spot-welded onto each specimen close to the notch. The test piece was heated up to 200°C to allow enough time for preparing the apparatus while the specimen cooled to the testing tem- perature. It was assumed that the specimen cooled uniformly. The accuracy of the flash-delay time was better than i2 pct i 5 psec. The crack length was taken as its maximum distance traveled normal to the length axis of the specimen. Errors in these measurements arise as a result of the uncertainty in the location of the crack tip and the difficulty in defining the exact position of the crack starting point. The latter was due to the bonding and large amounts of deformation at the hammer contact point, especially in the vacuum-annealed specimens tested at 150°C. The maximum error in the measurements was however estimated to be about 5 pct. DISCUSSION OF RESULTS From the trial experiments using mild steel above its transition temperature it can be seen from the plot of crack length against time after impact, Fig. 3. that a reasonable estimate of the maximum crack velocity at the surface of the specimen may be made. Other features of note are the initiation time before the crack is first seen and the slowing down period

Jan 1, 1967

New York Meets first Wednesday after first Tuesday of each month. J. E. JOHNSON, JR., Chairman EDGAR RICHARD, Vice-Chairman D M LIDDELL Secretary, 7 Wall St.. New York. N. Y. C. A. BORN, Treasurer JOHN V. N. DORR LEWIS W. FRANCIS Boston Meets first Monday of each winter month. R. L. AGASSIZ, Chairman JAMES G. CARLETON. Vice-Chairman E. E. BUGBEE Secretary-Treasurer, Mass. Inst. of Technology, Cambridge, Mass. W. E. C. EUSTIS G. A. PACKARD Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY, Chairman OSCAR LACHMUND, Vice-Chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. STANLY A. EASTON S. SHEDD

Jan 12, 1917

New York Meets first Wednesday after first Tuesday of each month. DAVID H. BROWNE, Chairman: PERCY E. BARBOUR, Vice-Chairman. A. D. BEERS, Secretary, 55. Wall St., New York, N. Y. C. A. BOHN, Treasurer. JOHN V. N. DORR, LEWIS W. FRANCIS. Boston Meets first Monday of each winter month. W. E. C. EUSTIS, Chairman. R. L. AGASSIZ, Vice-Chairman. E. E. BUGBEE, Secretary-Treasurer, Mass. Inst. of Technology, Boston, Mass. ALBERT SAUVEUR, H. L. SMYTH. Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY, Chairman. OSCAR LACHMUND, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane; Wash. STANLY A. EASTON, S. SHEDD.

Jan 1, 1917

In 1934 the Southern Experiment Station of the U.S. Bureau of Mines in. cooperation with the University of Alabama began an investiga-tion of the availability of kyanite ores as a source of raw material for the manufacture of refractories. Under this program, gravity concentration and flotation tests have been made on two varieties of Georgia kyanite ore, mica schist and massive. Most of the attention has been directed to the mica schist ores, as they are more widely distributed and seem to offer greater economic possibilities than the massive ores. It is evident that the preparation of kyanite for use as a refractory material involves other considerations than the mere elimination of impurities. A concentration process that eliminates impurities satisfactorily may have to be followed by some additional treatment, since the final product must be of a coarse-ness and size ratio that will make it suitable for refractories manufacture. So far in the investigation at the Southern Experiment Station of the U.S. Bureau of Mines only the concentration problem has been considered, and this paper is intended as an interim report.

Jan 1, 1936

AARONS, J. BOYD; Major. AGNEW, FRANK VANS. ALLEN, HERMAN H., Private, D Co., 8th Reserve Engineers. AMBLER, HARRY A., Second Training Camp,, Ft. Sheridan, Ill. BAINS, THOMAS M., JR., Major, Engineer Officers' Reserve Corps. BANKS, H. R., Lieutenant, Canadian Engineers, B. E. F. BARBOUR, PERCY E., Deputy' Supt. (Captain), New York State Troopers; Captain, 22d Regiment, N. Y. N. G. BARLING, H. B., 1st Lieutenant, Engineer Officers' Reserve Corps. BARRETT, LESLIE P., Lieutenant, A. E. F., France. (Unattached.) BENSEL, J. A., Major, Engineers' Reserve Corps. BIGELOW, BRAXTON, Royal Engineers, B. E. F. BLOOMFIELD, E. C., Lieutenant. BORROW, F. K. BOWLES, MARTIN F., 2d Lieutenant of Infantry, Camp Funston, Kans.

Jan 11, 1917

New York Meets first Wednesday after first Tuesday of each month. J. E. JOHNSON, Jr., Chairman EDGAR RICKARD; Vice-Chairman D. M LIDDELL, Secretary, 7 Wall St., New York, N. Y. C. A. BORN, Treasurer JOHN V. N. DORR - LEWIS W. FRANCIS Boston Meets first Monday of each winter month. R. L. AGASSIZ, Chairman JAMES G. CARLETON, Vice-Chairman E. E. BUGBEE Secretary-Treasurer, -Mass. Inst. of Technology. Cambridge, Mass. W. E. C. EUSTIS G. A. PACKARD Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY, Chairman OSCAR LACHMUND. Vice-Chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, P. 0. Drawer 2154, Spokane, Wash. STANLY A. EASTON S. SHEDD

Jan 1, 1918

By J. V. Richards

(Canal Zone Meeting, November, 1910,) THE Altar district, State of Sonora, Mexico, is for the most part a desert with but little rain-fall and few running streams. On account of this scarcity of water it is necessary for the natives to " dry-wash" the placer-gravel, and the object of the present paper is to describe some of the more common Mexican dry-washing devices. My observations were confined to a property known as Las Palomas placers, 15 miles from the Gulf of California and about 150 miles south of the United States border; a brief description of which property may be of interest as illustrating what is, perhaps, a typical Sonora dry placer. It is said that as long as a century ago the Yaqui Indians discovered rich cement-gravel, known as argo masa, at Las Palomas, and that there has been a more or less steady production of gold from the property ever since. The argo masa is a fairly-coarse gravel, the pebbles being quite firmly held together with a lime cement. Gold is scattered through this cement in particles ranging from fine specks to pieces several grams in weight, and occasional large nuggets are encountered. The contents vary so widely that it is difficult to estimate the average value, but returns of from $10 to $50 per cubic yard are common, and it is doubtful if the Indians considered anything less than from $4 to $5 a yard as "pay dirt." This argo masa occurs in channels varying in thickness from a few inches to several feet, and in width up to 300 ft.. These channels are continuous and are probably ancient stream-beds. They are for the most part covered with an over-burden of a more recent gravel, varying from 30 to 50 ft. thick, and the fact that this over-burden contains values as high as $1.50 per cubic yard, and yet was not worked by the Indians, shows that their idea of what constituted pay-ground was high.

Apr 1, 1911

New York Meets first Wednesday after first Tuesday of each month. DAVID H. BROWNE, Chairman. PERCY E. BARBOUR, Vice-Chairman A. D. BEERS, Secretary, 55 Wall St., New York, N. Y. C. A. BOHN, Treasurer. JOHN V. N. DORR, LEWIS W. FRANCIS. Boston Meets first Monday of each winter month. W. E. C. EUSTIS, Chairman. R. L. AGASSIZ, Vice-Chairman. E. E. BUGBEE, Secretary-Treasurer, Mass. Inst. of Technology, Boston, Mass. ALBERT SAUVEUR, H. L. SMYTH. Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY, Chairman. OSCAR LACHMUND, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. STANLY A. EASTON, S. SHEDD.

Jan 3, 1917

New York Meets first Wednesday after first Tuesday of each month. DAVID H. BROWNS, Chairman. PERCY E. BARBOUR, Vice-Chairman A. D. BEERS, Secretary, 55 Wall St., New York, N. Y. C. A. BOHN, Treasurer. JOHN V. N. DORR, LEWIS W. FRANCIS. Boston Meets first Monday of each winter month. W. E. C. EUSTIS, Chairman. R. L. AGASSIZ, Vice-Chairman: E. E. BUGBEE, Secretary-Treasurer, Mass. Inst. of Technology, Boston, Mass. ALBERT SAUVEUR, H. L. SMYTH. Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY, Chairman. OSCAR LACHMUND, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. STANLY A. EASTON, S. SHEDD.

Jan 2, 1917

By Kun Li, Alex Simkovich

The rate of dissolution of alumina in carbon-saturated liquid iron has been studied experimentally in a system where alumina was in the form of a cylindrical rod immersed in an iron bath contained in a graphite crucible. Data obtained consisted of the concentrations of aluminum in the melt as a function of time. In the case of static experiments, the data are shown to agree with theoretical prdictions based on the diffusion of aluminum.. The rate of dissolution was greatly increased by the rotation of the alumina rod. It is concluded that the diffusion of aluminum from the alumina/metal interface is the rate-controlling step. In the past, thermodynamic investigations of systems encountered in ferrous process metallurgy have received widespread attention. More recently, considerable work has been devoted to the study of kinetics associated with these systems in an effort to determine their rate controlling mechanisms. The alumina-iron system is of great importance in ferrous metallurgy. Yet information concerning kinetics of reaction in this system is seriously limited. The present study was made in order to establish the rate-controlling step for dissolution of solid alumina in liquid iron. LITERATURE REVIEW A number of papers concerning dissolution of solid metals in liquid metals have been reported in the literat~re. Generally, for these simple systems, dissolution is controlled by mass transfer of the dissolving species. Complex systems involving dissolution of solid metal carbides and oxides in liquid metals and slags have been studied to a much lesser extent. Skolnick5,6 reported on the reaction between liquid cobalt and poly-crystalline cylinders of tungsten carbide, in which the cylinders were dissolved while being rotated about their longitudinal axes at various speeds and temperatures. As a result of unexpected preferential grain boundary attack by the liquid cobalt, large errors in the measured dissolution rates occurred because of loss of tungsten carbide grains to the liquid cobalt. Nevertheless, it was possible to establish that the liquid Co-W carbide reaction was not controlled by mass transfer. In a similar approach, cooper7 was able to show that artificial sapphire rods, (alumina single crystals) dissolving in lime-alumina-silica slags obeyed a mechanism of mass transfer control. Here, again, the rods were rotated at various speeds and temperatures, and the process was followed as a function of these variables. Forster and Knacke8 took a practical approach to reaction between slags and refractories. By blowing argon through refractory cylinders of silica, silli-manite, or dolomite and directing the gas to rise along the slag-refractory interface, it was possible to increase the rate of mass transfer. Although the method was admittedly crude, it nevertheless permitted an evaluation of the relative stabilities of refractories with respect to slag attack. Data were interpreted on the basis of mass transfer control. EXPERIMENTAL TECHNIQUE Apparatus. An illustration of the apparatus used in this study is shown in Fig. 1. The furnace consisted of a Morganite recrystallized alumina tube wound with a molybdenum coil. A secondary molybdenum heater was mounted around the upper half of the primary coil to aid in controlling the thermal gradient within the furnace. The primary heater tube was 3 in. in ID and 30 in. long. A reducing mixture of 95 pct N and 5 pct H was maintained around the heating elements. Thermal insulation was provided by alumina powder. The chamber within the primary combustion tube contained a boron nitride block near the top to assist in controlling the thermal gradient to the furnace and also to provide a bearing surface for the rotating graphite shaft. The outside diameter of the graphite shaft was $ in. A separate threaded graphite specimen holder was screwed into the end of the shaft. The holder contained a tapered hole drilled into the end to guide the oxide specimens as they were pressed into it for mounting. Additional guidance for the rotating graphite shaft was furnished by a water-cooled bronze bushing attached to the top of the furnace. A steel clamp was fastened to the upper end of the graphite shaft and rested on a thrust bearing; the shaft and clamp were driven by a dc motor through a set of gears. Two O-rings located immediately above the bronze bushing maintained a gas-tight seal about the graphite shaft. The lower half of the alumina tube housed the crucible and charge, which were placed on a 3/4-in. diam movable alumina support tube. With this arrangement, charges could be inserted into or removed from the furnace while the hot zone was maintained at or above 1000°C. To control the temperature of the furnace, the thermocouple was mounted inside the support tube and in contact with the crucible bottom. Stray electric fields in the furnace were of sufficient intensity to cause erratic indications by the thermocouple. By enclosing the thermocouple protection tube in a molybdenum sheath and grounding this shield, the problem was eliminated. Output of the thermocouple went to an automatic continuous balance controller. Procedure. A typical run was as follows. First, electrolytic iron was premelted in graphite crucibles and cast into graphite molds with the same configura-

Jan 1, 1970

By F. L. Bosqui

Discussion of the paper of F. L. Bosqui, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 101, May, 1915, pp. 997 to 1033. H. A. WHITE, Springs, Transvaal (communication to the Secretary*). -It is, as the author points out in his valuable paper, a, fact, that in many plants the "trommel washings" are allowed to become eyesores, but the simpler system of pumping the entire product direct to the tube-mill circuit will avoid the extra expense of separation and small-scale treatment when one considers the relative distance of the points and the proportionately small amount of water. It is a matter of record that in stamp batteries the increase of weight has been developed concurrently with the increased use of tube mills, but independently and on its own merits. The satisfactory duty, excellent running time, and freedom from breakages in the newer mills, such as the Modder Deep, with 2,000-1b. stamps, will probably go far in removing some of the conservative prejudices mentioned by Mr. Bosqui. The success of the City Deep trial of the Nissen stamp cannot be entirely attributed to better feed distribution and discharge effects (published experiments on two-face discharge mortar boxes showed no advantages). Attention is directed to the treatment costs given by the author both before and after the increased capacity resulting from the addition of 16 Nissen stamps at Modder B. It will be observed that the only item of cost resisting the tendency to reduction caused by increased tonnage is that of milling, which has risen 1.3c. With reference to the provision for amalgamation in the new plans, it seems obvious that a great loss of head would be eliminated by passing the tube cone overflow over a separate top series of plates; three at the top and three at the bottom will effect the maximum amalgamation. This plan is followed at the Princess Estate and Gold Mining Co., Ltd., Modderfontein Deep Levels, Ltd., and Geduld Proprietary. Mines, Ltd., but elsewhere reliance is placed upon ample cone capacity and the underflow only is passed over three plates after going through the tube mill, while the overflow is passed direct to the cyanide works; both methods avoid the largely unnecessary elevation of considerable quantities of water, fine sand and slime involved in Mr. Bosqui's scheme.

Jan 1, 1916

By E. F. Reed

CONSIDERABLE deep hole prospect drilling has been done in the last few years in the Globe-Miami mining district about 70 miles east of Phoenix, Arizona, and in the San Manuel-Tiger area about 50 miles south of the Globe-Miami region. More than 205,000 ft of churn drilling have been completed by the San Manuel Copper Corp. at their property in the Old Hat Mining District in southern Pinal County. The deepest hole on this property is 2850 ft; there are 49 holes deeper than 2000 ft. At the adjoining Houghton property of the Anaconda Copper Mining Co., where only one hole reached 2000-ft depth, there were 27,472 ft of churn drilling and 3436 ft of diamond drilling. Three churn drill holes were deepened by diamond drilling methods. Near Miami in the Globe-Miami district the Amico Mining Corp. drilled four holes by combined churn and rotary drilling methods, the total amounting to 13,879 ft, of which 2256 ft were drilled with a portable rotary rig. In the same district, besides doing a large amount of shallow prospect drilling, the Miami Copper Co. drilled two holes of 2560 and 3787 ft, respectively, which were completed by churn drilling methods. The rocks encountered in drilling at San Manuel and Tiger are described by Steele and Rubly in their paper on the San Manuel Prospect' and by Chapman in a report on the San Manuel Copper Deposit.' The rocks are well-consolidated Gila conglomerate, quartz monzonite, and monzonite porphyry. In some places these formations stand very well while being drilled, and three holes were drilled without casing, the deepest of which was 2200 ft. In other holes faulted and fractured ground made drilling difficult. In the Globe-Miami district the deep drilling was done in the down-faulted block of Gila conglomerate east of the Miami fault and in the underlying Pinal schist. The geology of this area is described by Ranaome. In the Amico holes the conglomerate varied from material consisting entirely of granite boulders and fragments to a rock made up of schist fragments in a sandy matrix; in the Miami Copper Co. holes there were more granite boulders and the material was poorly consolidated. Drilling was much more difficult and expensive in the Miami area than in the San Manuel district, mainly because of the depth of the holes and the formations drilled. All the deep hole prospecting described in this paper was done with portable rigs. The churn drill rigs were of several types, of which the Bucyrus-Erie were the most popular. Bucyrus-Erie 28L, 29W, and 36L rigs were used on some of the deeper holes on the San Manuel property. A few Fort Worth spudder types were tried, and the deepest hole at San Manuel was drilled with a Fort Worth Jumbo H. The spudder type is considerably larger than most other rigs used on this work and required a larger location site. The spudders were belt-driven machines with separate power units, and time required for setting up and moving was much longer than with the more portable drills. All the churn drilling was done by contractors or with machinery leased from them. A few of the contractors had complete equipment, including most of the necessary fishing tools. Unusual and special fishing tools were obtainable from the supply companies in the oil fields of New Mexico or in the Los Angeles area. Most of the contractors used equipment with standard API tool joints, so that much of it was interchangeable. Failure of tool joints is one of the principal causes of fishing jobs. It can be minimized if the joints are kept to the API specifications and the proper sized joints are used in the various holes. The minimum sizes that should be used with various bits are as follows: 12-in. and larger bits, 4x5-in. tool joints; 10-in. bits, 3Y4x41/4-in. tool joints; 8-in. bits, 23/4x 3 3/4-in. tool joints; 6-in. bits, 21/4x31/4-in. tool joints; 4-in. bits, 15/ix25/s-in. tool joints. Two rotary drill rigs were tried at San Manuel on the same hole, and a portable rotary drill rig was used on the Amico drilling for test coring the formation and for drilling in holes 3 and 4. Rotary drilling differs from churn drilling or cable tool drilling in that the bit is revolved by a string of drill pipe and the cuttings are removed from the hole by a thin solution of mud pumped through the drill pipe. The principal parts of a rotary rig are the power unit, a rotating table to revolve the drill pipe, hoists to raise and lower the pipe and to handle casing, and a pumping system to circulate the drilling liquid. The rig used on the Amico property at Miami was mounted on a truck. The larger rig used on the San Manuel property was hauled by several trucks and had separate turntable and pumping units. Diamond drill coring equipment was used successfully with the rotary rig in the holes on the Amico property. To allow for 2-in. drill pipe with tool joints, 31/2-in. core barrels and bits were used. With the standard 31h-in. core barrel there was considerable difficulty in maintaining circulation with mud, so a barrel was designed with a smaller inner tube and a broad-faced bit. This allowed coarser material to circulate between the barrels. Rock bits of 5 to 37/8 in. were used with the rotary rig for drilling between core runs. Diamond drill equipment is much lighter than churn drill tools, so that fishing tools can usually be obtained from supply houses by air express when needed. Three churn drill holes on the Houghton property at Tiger were deepened by diamond drilling with Longyear UG Straitline gasoline-driven machines. The open churn drill hole was cased with 21h-in. black pipe. In deep hole churn drilling, casing is one of the most important items, especially in drilling in un-consolidated material like the formations drilled by

Jan 1, 1953

By E. F. Reed

CONSIDERABLE deep hole prospect drilling has been done in the last few years in the Globe-Miami mining district about 70 miles east of Phoenix, Arizona, and in the San Manuel-Tiger area about 50 miles south of the Globe-Miami region. More than 205,000 ft of churn drilling have been completed by the San Manuel Copper Corp. at their property in the Old Hat Mining District in southern Pinal County. The deepest hole on this property is 2850 ft; there are 49 holes deeper than 2000 ft. At the adjoining Houghton property of the Anaconda Copper Mining Co., where only one hole reached 2000-ft depth, there were 27,472 ft of churn drilling and 3436 ft of diamond drilling. Three churn drill holes were deepened by diamond drilling methods. Near Miami in the Globe-Miami district the Amico Mining Corp. drilled four holes by combined churn and rotary drilling methods, the total amounting to 13,879 ft, of which 2256 ft were drilled with a portable rotary rig. In the same district, besides doing a large amount of shallow prospect drilling, the Miami Copper Co. drilled two holes of 2560 and 3787 ft, respectively, which were completed by churn drilling methods. The rocks encountered in drilling at San Manuel and Tiger are described by Steele and Rubly in their paper on the San Manuel Prospect' and by Chapman in a report on the San Manuel Copper Deposit.' The rocks are well-consolidated Gila conglomerate, quartz monzonite, and monzonite porphyry. In some places these formations stand very well while being drilled, and three holes were drilled without casing, the deepest of which was 2200 ft. In other holes faulted and fractured ground made drilling difficult. In the Globe-Miami district the deep drilling was done in the down-faulted block of Gila conglomerate east of the Miami fault and in the underlying Pinal schist. The geology of this area is described by Ranaome. In the Amico holes the conglomerate varied from material consisting entirely of granite boulders and fragments to a rock made up of schist fragments in a sandy matrix; in the Miami Copper Co. holes there were more granite boulders and the material was poorly consolidated. Drilling was much more difficult and expensive in the Miami area than in the San Manuel district, mainly because of the depth of the holes and the formations drilled. All the deep hole prospecting described in this paper was done with portable rigs. The churn drill rigs were of several types, of which the Bucyrus-Erie were the most popular. Bucyrus-Erie 28L, 29W, and 36L rigs were used on some of the deeper holes on the San Manuel property. A few Fort Worth spudder types were tried, and the deepest hole at San Manuel was drilled with a Fort Worth Jumbo H. The spudder type is considerably larger than most other rigs used on this work and required a larger location site. The spudders were belt-driven machines with separate power units, and time required for setting up and moving was much longer than with the more portable drills. All the churn drilling was done by contractors or with machinery leased from them. A few of the contractors had complete equipment, including most of the necessary fishing tools. Unusual and special fishing tools were obtainable from the supply companies in the oil fields of New Mexico or in the Los Angeles area. Most of the contractors used equipment with standard API tool joints, so that much of it was interchangeable. Failure of tool joints is one of the principal causes of fishing jobs. It can be minimized if the joints are kept to the API specifications and the proper sized joints are used in the various holes. The minimum sizes that should be used with various bits are as follows: 12-in. and larger bits, 4x5-in. tool joints; 10-in. bits, 3Y4x41/4-in. tool joints; 8-in. bits, 23/4x 3 3/4-in. tool joints; 6-in. bits, 21/4x31/4-in. tool joints; 4-in. bits, 15/ix25/s-in. tool joints. Two rotary drill rigs were tried at San Manuel on the same hole, and a portable rotary drill rig was used on the Amico drilling for test coring the formation and for drilling in holes 3 and 4. Rotary drilling differs from churn drilling or cable tool drilling in that the bit is revolved by a string of drill pipe and the cuttings are removed from the hole by a thin solution of mud pumped through the drill pipe. The principal parts of a rotary rig are the power unit, a rotating table to revolve the drill pipe, hoists to raise and lower the pipe and to handle casing, and a pumping system to circulate the drilling liquid. The rig used on the Amico property at Miami was mounted on a truck. The larger rig used on the San Manuel property was hauled by several trucks and had separate turntable and pumping units. Diamond drill coring equipment was used successfully with the rotary rig in the holes on the Amico property. To allow for 2-in. drill pipe with tool joints, 31/2-in. core barrels and bits were used. With the standard 31h-in. core barrel there was considerable difficulty in maintaining circulation with mud, so a barrel was designed with a smaller inner tube and a broad-faced bit. This allowed coarser material to circulate between the barrels. Rock bits of 5 to 37/8 in. were used with the rotary rig for drilling between core runs. Diamond drill equipment is much lighter than churn drill tools, so that fishing tools can usually be obtained from supply houses by air express when needed. Three churn drill holes on the Houghton property at Tiger were deepened by diamond drilling with Longyear UG Straitline gasoline-driven machines. The open churn drill hole was cased with 21h-in. black pipe. In deep hole churn drilling, casing is one of the most important items, especially in drilling in un-consolidated material like the formations drilled by

Jan 1, 1953

New York Meets first Wednesday after first Tuesday of each month. J. E. JOHNSON, JR., Chairman EDGAR RICKARD, Vice-Chairman D. MI. LIDDELL, Secretary, 7 Wall St., New York, N. Y. C. A. BOHN, Treasurer JOHN V. N. DORR LEWIS W. FRANCIS Boston Meets first Monday of each winter month. R. L. AGASSIZ, Chairman JAMES G. CARLETON, Vice-Chairman E. E. BUGBEE Secretary-Treasurer, Mass. Inst. of Technology. Cambridge, Mass. W. E. C. EUSTIS G. A. PACKARD Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY, Chairman OSCAR LACHMUND, Vice-Chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. STANLY A. EASTON S. SHEDD

Jan 8, 1917

By R. P. Smith

THE carbon content of iron-silicon and of iron-manganese alloys at fixed activities of carbon has been reported previously.' It seemed desirable to investigate a system which allows a more extended range of alloy composition within a single phase region. The iron-nickel system is ideal in this respect, in that all alloys from 100 pct Fe to 100 pct Ni are face centered cubic ("austenitic") at 1000 °C. The experimental procedure was similar to that previously described.1,2 The alloys, in the form of pieces about 2 by 2 by 0.2 cm thick, together with a similar specimen of pure iron, were equilibrated with each of a series carbon monoxide-carbon dioxide tnixtures of fixed composition, quenched in the carburizing gas in the top of the furnace and then analyzed for carbon. The carbon content of samples containing more than 0.3 wt pct C was determined by the usual combustion method; those with less carbon

Jan 1, 1961