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By H. A. Bourne, E. L. Haden, D. R. Reichmuth

A circumferential-toothed bit with novel tooth form gave improved penetration performance. In this design the exterior flank of all teeth were vertical when in rolling contact with the hole bottom. Rock chips were generated by the interior flank of the tooth displacing the rock inwardly and downslope toward the center of the hole. A unique two-cone laboratory bit assembly enabled evaluation of numerous cone and tooth configurations. Some of the variables investigated, in addition to weight on bit, rotary speed and rock type, were tooth interference, percent tooth, hole bottom angle, attack angle and relief angle. Most tests were conducted dry on a brittle synthetic sandsone or a ductile quarried limestone. Tooth configurations were found to be more significant in the ductile material. This was attributed to the deeper tooth penetration before rock failure. These studies showed that the attack angle (angle beween interior flank of the tooth and rock surface) was the controlling variable; changing the tooth configuration from the assymetric or semi-wedge to the more conventional symmetric or wedge form reduced penetration performance; and penetration performance of circumferential-type cutters was directly proportional to rotary speeds up to 200 rpm. INTRODUCTION Much of the published literature on rock-chisel interactions describe experiments wherein symmetrical wedges are vertically loaded or impacted against a smooth rock surface.1-6 are is usually taken to insure that the indentation is not made near the edge of the rock specimen less erroneous data be obtained. The literature describes relatively few studies in which the investigator deliberately attempted to take advantage of an edge or free surface. In contrast, anyone who chips ice or breaks up a concrete sidewalk almost always works near an edge. Chisel "indexing," which has been considered by some investigator1,2,6,7 makes limited application of an edge or free surface. Probably the best documented investigation into applying this idea to drilling was that of Drilling Research Inc. at Battelle Memorial Institute.' Their "annular wing" percussion bit consisted of paired asymmetric chisels oriented so as to produce and move chips to the center of the hole. They predicted that the lowest energy requirement for chip generation would be achieved with a stepped hole bottom having a median angle of 45" to the horizontal. Results from limited tests showed that approximately 50 percent of the rock fragments were large and semi-circular in shape, as would be expected by a chisel impact near an edge. The remaining 50 percent were fine chips produced by the chisels in re-establishing the steps or ledges. Initial penetration rates with this bit were high, but they rapidly decreased. This was the result of excessive tooth wear caused by the constant friction on the gauge surfaces. The basic idea — circumferentially placed asymmetric chisels — still appears to have merit. If the concept could be applied to a rolling cutter bit, two of the shortcomings of the fixed chisel design could be overcome: (1) reduction in tooth friction, and (2) greatly increased cutter surface. Adapting asymmetric chisels to cutters rolling on an inclined hole bottom is restricted by bit geometry. The basic elements of roller rock-bit construction prevents the practical attainment of a 45" hole bottom angle. Nonetheless, experimentally it was considered desirable to investigate the influence of hole bottom angle to at least 40". This paper describes the laboratory studies conducted in evaluating the circumferential-toothed roller cutter rock bit. EXPERIMENTAL APPARATUS AND PROCEDURE BIT ASSEMBLY The cost of constructing a sufficient number of conventional three-cone rock bits to investigate circumferential cutter performance was prohibitive. Instead, a novel two-cone laboratory assembly which used an external bearing system was designed and constructed. The external bearings made it possible to alter the journal bearing angles and thus allow a wide flexibility in cutter configuration. Fig. 1 shows the laboratory bit assembly, the various bearing mount plates and the appropriate roller cutters for drilling shallow holes having hole bottom angles of 0, 10, 20, 30 or 40". The bit was limited to a drilling depth of 1 1/2 in. at the gauge teeth and a hole diameter of 43/4 in. This more or less intermediate size bit was chosen because it gave a more realistic match between bit teeth and the rock than would a microbit. Also, the rock sample size required was convenient and easy to obtain. CIRCUMFERENTIAL CUTTERS The tooth configuration used in our initial studies is shown in the upper half of Fig. 2. All cutters used in this series had the same tooth form — 43" included tooth angle, 2" positive relief angle and a horizontal tooth flat width of 1/32 in. Each cone cuts alternate rows except for the gauge row. The row-to-row spacing in view was 1/4 in. Static loading tests conducted earlier with asymmetrical chisels had been used to establish this spacing. These tests showed energy requirements for chip production increasing rapidly as the distances to the edge increased beyond

By John B. Myers

VERMICULITE is a name used to describe micaceous material that exfoliates when heated. It is hydrated magnesium-aluminum-iron silicate. The chemical composition, color, physical appearance, and degree of exfoliation vary. COMPOSITION, PROPERTIES, AND ORIGIN Vermiculite has the characteristic micaceous structure of basal cleavage and readily splits into thin laminae, which are soft, pliable, and inelastic. The monoclinic crystal faces are often marked by triangular lines at 60° and 120°. Hardness is 1.5; specific gravity, 2.2-2.7; luster pearly to greasy; colors, amber, bronze, reddish brown, dark green, and black. Feel is soapy, particularly when wet. When heated it exfoliates by expanding at right angles to the cleavage into long wormlike pieces (the name vermiculite is from the Latin veamiculari, to breed worms). This important characteristic of expansion is believed to be a mechanical separation of the layers when the contained water is converted into steam. Warping of the unit layers may also contribute to the expansion. The increase in bulk volume of commercially prepared material is 8 to 12 times but individual flakes may increase in size more than this. Pure vermiculite is a distinct mineral and has the structural formula (OH), (Mg,Fe)3 (Si,Al,Fe)4 010.4H20. It rarely occurs in this pure form, but generally as a mixed mineral of varying structure. One explanation is that the mixed material is composed of unit layers of inter-stratified pure vermiculite and biotite. The essential difference between the two is that unit cell structure of vermiculite contains a layer of water molecules whereas the biotite cell contains potassium instead of the water. The water content of the mixed vermiculite is less than that of pure vermiculite but more than that of biotite. Pure biotite does not expand when heated. If the proportion of biotite layers in a vermiculite is too high it will adversely affect the degree of exfoliation. Within a given deposit, the great mass of material may approach a definite com-position with local areas of greater biotite content. It is not uncommon to find also small pockets of pure biotite but these are generally segre-

Jan 1, 1949

By Donald E. Garrett

The processing of brines from Searles Lake, California, yields one of the world's largest supplies of borax and boron chemicals, second probably only to the massive deposit at Boron, California. Two companies produce from this deposit, the American Potash & Chemical Corp. and the West End Chemical Co., a division of the Stauffer Chemical Co. Two processes are employed in recovering borax from the brines; one is used by both companies and consists of carbonating the brine to form sodium bicarbonate, removing this, and then cooling the liquor to crystallize a crop of borax. Only American Potash uses the second process, evaporating the brine to concentrate it and remove (crystallize) much of its NaCl, Na2CO3, Na2SO4, and NaLi2PO4 content, quick cooling the remaining liquor to remove KCI, and then seeding the filtrate to remove borax. Both methods will be briefly described. Searles Lake is a large evaporite body formed during the most recent two Sierra Nevada ice stages, the Tahoe and the Tioga. Runoff waters from the Sierra Nevada Mountains collected in the large Owens Valley drainage basin and from there overflowed into the Indian Wells basin and then into Searles Lake. In each Lake, evaporation took place. To a large extent the Owens and Indian Wells lakes acted as settling basins, for much of the mud, and insoluble calcium and magnesium precipitates were deposited there. Recent volcanic activity in the mountains to the north and east of Owens Lake had scattered considerable mineral-rich volcanic ash and debris throughout the drainage area, and several hot springs were formed that contained boron and other salts. The present flow rate and concentration of several springs, and the known age of at least the Tioga zone, can fairly well account for all of the boron present in Owens and Searles Lakes.1 The tungsten content can be accounted for in a similar manner.2 Most of the salts thus originally present in the fresh water runoff-from ice, snow, and rain-accompanying these two ice stages were ultimately deposited in Searles Lake. During the Tahoe period, from 25 to 40 ft of massive, mixed salts were deposited, along with six interspersed layers of mud (four inches to two feet thick) representing comparatively brief interglacial periods. Before the final desiccation of the lake, from 10 to 14 ft of new mud was deposited, representing the Tioga stage. The crystals subsequently deposited were from 70 to 90 ft thick, and form the present lake surface. The extent of the salt body is about 34 square miles, of which 12 square miles are exposed salt; the remaining area is covered by recent alluvial deposits (chiefly mud). The present lake is generally dry on the surface but floods to a shallow depth following heavy rains. The crystal body of both zones consists of continuous clusters of salts, and the voids between crystals (about 45 pct of the total volume) are occupied by brine. The level of this brine never recedes more than several inches below the salt surface. The brine pumped to the plants for processing is generally saturated with all of the solid phases present in that area, and thus is a complex mixture containing about 35 pct solids (see Table 3). The brine composition varies somewhat at different areas of the lake and from upper to lower structures, so wells are drilled in the areas and to the depths desired. A casing is cemented in the hole to within a short distance from the bottom, and pumps with about 14-ft suctions are mounted on the casing to pump the brine into the plants. The evaporation process of the American Potash & Chemical Corp. treats upper structure brine, evaporating all of the water from

Jan 1, 1960

By J. R. Dolegowski, W. S. Jensen, S. M. Olafson, W. H. Champion, G. A. Kordosky

The use of pH control in solvent extraction circuits to aid in metal separation, concentration, and purification is an extremely useful technique applicable to a wide range of solutions. This paper discusses the technique in general and then gives examples of its use in extraction stages, wash and/or scrub stages, and in stripping stages, to effect the desired metal separation, concentration, and purification. Specific examples cited include Cu-Ni, Cu-Zn, and U-Mo separations using commercially available liquid ion exchange reagents.

Jan 1, 1982

By F. J. Plecity, J. T. Michalak, W. C. Leslie

W. M. Williams (McGill University)-The authors are to be congratulated on completing this detailed investigation of recrystallization behavior. The present writer has recently completed some research at the University of Toronto on the recrystallization and grain growth behavior of a number of "pure" irons, and he would like to take issue with the authors' contention that recrystallization cannot be followed by means of hardness measurements. Two series of specimens of Ferrovac E, a com- mercially available iron, were annealed to complete recrystallization at 525" and 620" C, measurements being made both of Rockwell hardness and of volume percent recrystallized as a function of annealing time. Good correlation was found between these two quantities and, following the earlier practice of Cook and Richards for copper, hardness measurements were used in an extensive investigation of recrystallization. No anomalous behavior was observed as a result of this practice. Specimens which showed complete softening always showed, (metallographically and by X-rays), completely re-crystallized structures. These observations do not, of course, detract in the least from the results of the work under discus-

Jan 1, 1962

By John V. Beall

Cutting costs and increasing safety with new ideas is the byword with The Cleveland-Cliffs Iron Co. on the Marquette Range in Michigan. Among the new ideas being tried out are mechanical shaft mucking, prefabricated lagging to replace timber poles, Carset bits in shaft sinking, and rubber tired guide wheels on the ore skips. Plans are being made to stockpile ore with conveyor belts during the winter. In sinking the Mather "B" Shaft a 3/8-yd clamshell-type bucket is used for mucking. The clamshell is opened and closed by means of a verticallymounted hydraulic ram actuated by 5000 psi oil pressure. An Ingersoll Rand-type hoist is used to raise and lower the clamshell. The hoist is controlled by one member of the crew on the floor of the shaft. When the bucket is raised, the men swing it over the muck pile to the desired position and then it is lowered on to the broken rock. The 1400-lb weight of the bucket causes it to sink into the broken rock and it digs as the ram closes the bucket. The hydraulic ram is operated by a man on the lowest shaft steel set who controls a specially designed oil pump which supplies oil pressure. The clamshell is emptied.

Jan 1, 1949

By P. C. Claspy, P. H. Smakula

The electro-optic coefficients of LiNbO, and KTao.,5Nboe3,O3 (KTN) have been experimentally determined at the HeNe laser wavelengths of 0.6328, 1.15, and 3.39 µ. The coefficients were calculated fronz the retardation induced by an applied electric field. The retardations were measured by observing one or move transmission maxima and minima as a function of the applied field, and by measuring the retardation directly with a Babinet-Soleil compensator. The values obtained agree quite well with those previo~lsly reported by others. Extinction ratios as high as 3000:l have been observed. Resistivities and Curie temperatures have also been measured. Light-induced optical inhornogeneities in LiNbO, repovted by others have been observed. CONSIDERABLE interest has recently been shown in the electro-optic properties of LiNb03 (Refs. 1 and 2) and KTN.3, 4 These crystals have a number of advantages over such well-known materials as KDP. These advantages include: 1) the infrared transmission of KTN and LiNb03 extends to 5 p whereas that of KDP cuts off at 1.5 p ; 2) driving voltages required for modulators using these materials are considerably lower than those required for KDP. After first discussing some theoretical considerations of the electro-optic effect, we will report the results of measurements of the dc electro-optic coefficients of these materials at wavelengths of 0.6328, 1.15, and 3.39 p. THEORY The generalized equation for the electro-optic effect can be written: Although lattice polarization is the fundamental variable, rather than the applied electric field, we follow the convention of expressing the linear electro-optic effect in terms of the applied field. For LiNbO the quadratic terms are negligible. Since KTN has a center of symmetry the rijk tensor is 0. After applying the usual symmetry considerations and index contractions,* the rijk and gijkl tensors can be expressed as follows: LiNbOaT If field directions are now chosen, the change in refractive index and the angle between the induced optic axes and the crystallographic axes can be found. The induced rotations of the principal axes of the index ellipsoid for fields in principal crystallographic directions are given in Table I. Since KTN is initially isotropic, the principal axes in the zero-field condition are parallel to the crystallographic axes. The induced retardations are given in Table 11. EXPERIMENTAL We obtained the various electro-optic coefficients by measuring the induced retardation as a function of

Jan 1, 1968

By Francois E. Heuze

INTRODUCTION Rock slope stability typically is governed by the geological discontinuities. This stability can be improved by drainage, unloading, adjustment in slope orientation, adjustment in slope angle, and also by reinforcement such as bolts or tendons. This paper addresses the modeling of bolt reinforcement in rock slopes. Most geological discontinuities such as joints have rough surfaces; they dilate during shear displacement. Their shear strength is characterized by two envelopes (Fig. 1); the peak envelope is distinct from the residual envelope when the joints can dilate. If the dilation is restrained transversely, such as with bolts, the normal stress will increase and the joint strength also will increase. It has been demonstrated that this increase may be considerable (Obert et al., 1976). The new normal stress at peak strength is a com- posite function of the properties of the rock mass and of the steel (Heuze, 1979). Hence, the dilation and its resultant effects on joint shear strength must be included in the analysis and design of the reinforcement. We present a model which can be used to perform such an analysis. Early studies of rock reinforcement in mining and civil applications (Lang, 1957 - Panek, 1962 - Osen and Parsons, 1966 - Lang, 19721, did not consider the specific effects of bolts on joint shear strength. In 1973, Heuze and Goodman reported direct shear tests on rough sandstone joints with bolts perpendicular to the joint plane (Fig. 2). The peak shear strength of such joints was greatly in excess of the shear strength of the unbolted joints. The excess

Jan 1, 1983

By A. D. K. Laird, C. A. Johnson

Drag coefficients for a cylinder being towed through water at constant velocity and also at constant linear acceleration were measured. Drag coefficients for constant velocity towing showed reasonable agreement with previous results. The drag coefficients found for constant acceleration showed little correlation with either the magnitude of the acceleration or the value of the modulus AD/V2 and tended to be slightly lower than those for constant velocity. INTRODUCTION For the design of offshore structures, wave forces acting on immersed cylinders are of importance. Several investigations have been made of these forces and of how they can be predicted from wave theories. A paper by Crooke' summarizes much of the work already done. More recent research by the Wave Research Laboratory at the University of California, Berkeley, has added much to the body of data collected under ocean wave conditions, but has not found a reliable method of force prediction from basic theories of wave motion. The present investigation is part of a long-range program to collect data with which to test current and future theories and correlations. The immediate objective was to measure drag forces on a circular cylinder subjected to linear accelerations over the range of Reynolds numbers between l04 and 105 where the drag coefficient was a constant for constant velocities. In particular, the effect of constant acceleration from rest and from uniform motion was to be investigated. The effect of acceleration may be evaluated in terms of drag coefficients. A useful resistance coefficient, C, is defined by the equation for total drag force, D, exerted by the fluid on the cylinder. DT =CSp V2/2.........(1) The coefficient C may be plotted as a function of the parameter AD/V2. Here D is the diameter and S is the projected area of the cylinder. The acceleration and velocity are A and V. The mass density of the fluid is p. An alternate drag coefficient, C, corresponds to the total force of the fluid opposing the motion minus the virtual mass force. This drag coefficient, arising from the velocity of the fluid, may be compared with that for the same cylinder in uniform motion. The similarities and differences between this coefficient as calculated for accelerated and for steady motion are of interest in the inverse process of predicting drag forces on cylinders under arbitrary conditions. One serious difficulty in this method is the specification of the virtual mass which depends also on the flow picture about the cylinder.1 EXPERIMENTAL EQUIPMENT The experiment was performed in the combination wave and towing tank at the Engineering Field Station of the University of California. The tank is 200 ft long, 8 ft wide, and 6 ft deep. The tow carriage is externally propelled by a cable, and the velocity of the carriage is maintained essentially constant by means of an am-plidyne. For the purpose of the present investigation, the speed control of the amplidyne was modified by inserting a linear speed control rheostat, which was rotated at a constant speed by a small d-c motor equipped with a slip-clutch. Accelerations which were constant over a reasonable length of time were thus produced. The magnitude of the acceleration depended upon the speed of the d-c motor and the limiting speed of the carriage. Data were obtained for a range of accelerations of 2 to 10 ft/sec,2 and a range of velocities of 2 to 15 ft/sec. An accelerometer (Statham Type C-2-350) with a range of ±2g was attached to the carriage and connected to a Brush analyzer and penmotor. A continuous coil of wire with 10 turns/ft wound around a fixed wooden form extending for a distance of 40 ft along the length of the tank was connected by an electrical contact mounted on the carriage to a Brush analyzer and penmotor, to give the time-position history for each run. The test cylinder was machined from solid aluminum alloy, 17-ST. to a diameter of 1.250 in., and could be

Jan 1, 1957

By Paul Weaver

DURING 1932 the amount of geophysical surveying carried out as a part of oil-field development in¬creased, particularly in the Gulf Coast of Texas and Louisiana. Here the most intensive geophysical activity was displayed in the discovery of domes and prospects several years ago, after which there was a period of relative inactivity. This year many of the leases required development and geophysical methods were used to obtain pictures of the detailed structures. These were almost exclusively gravity and reflection-seismograph surveys and for the first time this latter method was generally used by oil operators to construct subsurface contours. The total number of geophysical troops in this territory increased from 16 to 40 during the year.

Jan 1, 1933

By Robert Glass Cleland

[PHELPS DODGE COPPER PRODUCTS CORPORATION OFFICE, 40 WALL STREET, NEW YORK 5, N. Y. OFFICERS Whipple Jacobs President Howard T. Brinton Vice-President Edgar P. Dunlaevy Vice-President Weightman Edwards Vice-President S. Allan Jacobs Vice-President]

Jan 1, 1952

Discussion of the paper of G. P. Hulst, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 92, August, 1914, pp. 1865 to 1871. L. S. AUSTIN, Salt Lake City, Utah.-One question that I would like to ask is in regard to the sampling kettle which stands beside the softening furnace. How is the sample taken or melted? G. P. HULST.-The sampling kettles in question are of 45 tons capacity and are fired with coal. The lead bullion comes in on a high line in car-load lots of 30 to 40 tons. The entire lot is trucked from car, weighed over scales and thrown into the sampling kettle, which has been previously cleaned. The kettle is fired and the bullion melted, then heated up until no frozen bullion' remains in the .bottom or adheres to the sides of the kettle. The kettle is scraped clean, sides and bottom, and the wet dross is skimmed Doff clean into molds. The kettle is stirred thoroughly during the period in which 24 to 30 samples of approximately ½ assay ton are taken. These samples are taken in a long-hand loci iron mold, providing for taking six to eight "gumdrops." The mold is inserted and heated to the same temperature as the molten metal, and gumdrops are clipped out and cooled in the mold by dipping 'the bottom of. the mold into Water. The samples should be free from fins. The gumdrops represent the contents of the kettle, and in assaying, they should not be clipped, but weighed up and the result computed. The dross bars are weighed and sawed according to old hammer and punch sample template. The sawdust represents a sample of the dross. In eases of high gold in the bullion there is a slight correction in the assay. This method of sampling was developed at the Omaha plant of the American Smelting & Refining Co., W. T.. Page, Manager, in 1903 or 1904, for adjusting differences in checking smelter sampling. L. S. AUSTIN.-The base bullion which you treat is very clean. It has been remelted, and skimmed before shipment. How rapidly can you get it through the softening furnace, and how does it compare with ordinary base bullion? G. P. HULST.-Twenty-four hours is the softening limit on these charges. In other words, it is charged into the furnace, heated up, and the first and second skimmings are taken off, and it goes into the kettle the next day; that is, 24 hr. elapse from the time the bullion is charged to the time it is in the kettle. L. S. AUSTIN.-It seems to be a long time to hold such a pure bullion. I suppose, though, it comes around conveniently so that you have a time for all the other operations of refining. Isn't that the case? MR. HULST.-Every refinery is based on those principles.

Jan 11, 1914

By J. W. Gwinn

THE underground haulage system in the lead-silver mine of the-Bunker Hill & Sullivan Co., situated at Kellogg, Idaho, is the most extensive in the Coeur d'Alène district, comprising about 35,000 ft. of tunnels, drifts, and cross-cuts where locomotive haulage is in use. The main working adit, known as the Kellogg tunnel, or No. 9 level, is approximately 10,000 ft. in length from the portal to the main working shaft and extends beyond that about 4,500 ft. in each of two directions. On this level all the ore from the Bunker Hill & Sullivan, the Sierra Nevada Consolidated, and the Caledonia Mining Co. an average of 44,600 tons per month-is hauled to the mills, located a short distance from the portal. Electric haulage by the trolley-type locomotive is used on this level throughout. Below this level, at intervals of 200 ft. vertically, are five other working levels (Nos. 10, 11, 12, 13, and 14); and the total haulage distance on these, where electric locomotives are used, is approximately 16,000 ft. No. 13 level has but recently been opened up and is not working-to capacity; while the main cross-cut on No. 14 has just been started, and has no need of power haulage. Of the four levels equipped with electric haulage, Nos. 11, 12, and 13 have storage-battery locomotives, and No. 10 still retains the trolley type by reason of the small and decreasing tonnage produced.

Jan 2, 1915

By F. O. Garrabrant

POWER is furnished to the Climax Molybdenum Co. by the Public Service Co. of Colorado over two 100,000-volt line to a bank of three 3333-kva. Transformers 100/13.8 kv. These transformers arc so designed that with the addition of forced cooling their capacity may be increased 33 1/3 per cent at 12,000-ft. altitude. Under present conditions, these transformers are operated at 140 per cent of their rating with forced air cooling. On the secondary side of this bank there is a 15-kv., 1200- amp. Westinghouse oil circuit breaker provided with automatic reclosing relays allowing three successive short circuits before lockout. From this breaker 13.8-kv. power is transmitted to a central switching station (Fig. I) where all circuits radiate to the different operations of the property. Each circuit is protected by a 23-kv., 600-amp. oil circuit breaker with by-pass and isolating disconnecting switches. MINE Power at 13.8 kv. enters the mine through a ventilation raise over a three-conductor, size 1-0 varnished cambric insulated, leaded, steel-wire armored cable, insulated from 17 kv. This power is received and distributed through one switching station and four underground substations, shown in Fig. 2. No. 370 substation (Fig. 3) contains three 250-kva, 13,800/440-volt, single-phase Pyranol transformers protected on the high-voltage side by a 600-amp. manually operated oil circuit breaker. This station serves 20 slusher-hoist motors, a 45-kw., three-phase, 220-volt electric furnace, a Massco hot miller for tempering and milling Timken detachable bits and a hoist with 175-hp. motor on the No. 3 development shaft. Also at this shaft are three pumps. One two-stage pump, 1200 gal, per min., 100-ft. head, 3600 r.p.m., driven by a 150-hp. motor, is at the bottom of the shaft. Two deep-well pumps, 500 gal. per min., 500-ft. head, are at the collar of the shaft. Under normal operation the one pumping 1200 gal. per min. is controlled by a float switch to take care of the water. If this pump fails, or if its capacity is insufficient, the first 500-gal. pump is automatically started, and if still more capacity is needed the second 500-gal. pump automatically starts. Time delay relays are provided on the deep-well pumps, so that if power fails the column will have time to drain before the pumps restart. On failure of any of these, an alarm is sounded in the train dispatcher's office, so that mechanics can be sent to ascertain the cause of failure and make repairs. The cable from No. 370 substation is run to the switching station, in which are four15-kv., 600-amp. direct-current solenoid-operated oil circuit breakers. The current for operating and tripping is furnished by a 125-volt storage battery. All breakers are operated from the switchboard in the compressor room. One circuit from this switching station goes to the

Jan 1, 1944

Prof. H. S. Munroe, New York City : In his reference to cop per-dressing at Lake Superior, p. 325, Mr. Douglas says that " the .. concentration .. . has been carried out with greatest financial economy,... I do not say with the greatest economy of min eral." And again, on p. 344, referring to the same, " it would not pay to reduce the quantity treated, and increase hand-labor, in order to save a few hundredths of one per cent. of copper." Mr. Douglas probably has in mind the fact that the copper lost is all included copper, locked op in grains of sand. To save this, the rock must be crushed finer. If the mesh of the stamp-screens be reduced, the stamps will crush less; and thus we shall have to reduce the quantity treated in the mill per day, while the labor re mains the same per day, or is increased per ton, as he says. Submitting to the loss of copper, however, is not the only solution of the difficulty. A large quantity of rich sand is now collected by the jigs, and it would be easy to save so much of this material that the escaping sands would be quite poor. What is wanted at Lake Superior, and at many dressing-works in this country, is an efficient crushing-machine to treat the sands thus collected. Abroad, we have the Heberle machine and the Schranz mill for this purpose, the latter being the more successful. The Heberle grinder was tried at the Calumet and Hecla mill for crush ing these rich sands, with what success I do not know. I should like to ask Mr. Douglas if we have no American crushing-machine that will reduce jig-sands to a fine state of division

Jan 1, 1894

By V. Annamalai, J. B. Hiskey, L. E. Murr

The kinetics of copper cementation on rotating disks of body and tear-top beverage can aluminum alloys were studied as a function of temperature and copper ion concentration. Both alloys followed the two-step kinetic regions, an initially slow rate followed by an enhanced rate. Experimental activation energy determinations (9.04 to 19.62 kJ/mol) indicated that ionic diffusion controlled the reaction mechanism between 20° and 60°C. At low temperatures (< 20°C), the system appeared to be controlled by the presence of an aluminum oxide surface film. The results of this study showed that cementation kinetics for the beverage can aluminum alloys are similar to those for pure aluminum. It was also found that the chemical removal of the oxide layer is less important for the alloys than /or the pure aluminum system. The characteristics of the resultant copper deposits were studied under a scanning electron microscope, and the reaction kinetics seemed to depend strongly on the nature and morphology of the deposits. In addition, maximum rates occurred when the deposit structures were fine feathery dendrites.

Jan 1, 1980

By R. S. Dean

PROCESSES for the direct production of iron and steel from ores are hardy perennials, and new processes and revivals of old ones are continually being brought to the attention of the investing public if not to the attention of metallurgists. Direct production of iron and steel is so simple that it offers a fertile field for the promoter. Unfortunately in this way direct processes have acquired a bad name, not always deserved, with conservative capitalists and metallurgists. Direct processes cannot, except in special instances, be looked upon as a substitute for any single operation in present iron and steel practice but must be considered, as one link in an entirely new chain of metallurgical process from ore to finished steel. Thus it is, in my opinion, inadvisable to consider the use of sponge-iron processes as a means of treating ore of ordinary blast-furnace grade to produce open-hearth feed. In time I think it will be found equally inadvisable to smelt iron-ore concentrates in the blast furnace.

Jan 1, 1935

By H. W. Gillett

CLYDE WILLIAMS has reminded me that in the fall of 1929, gave, in MINING AND METALLURGY, an account of the hopes and aspirations of Battelle Memorial Institute, which was then just swinging into initial operation; and that therein I remarked that B.M.I. should stand, as well, for Better Metallurgical Industries, since helping to better them was the Institute&apos;s aim. So he has suggested that some of the betterments of the past fifteen years might well be listed. A yearly summary of progress comes pretty close to the ultimate in futility, for everything proved of value in that year had its inception in earlier years, and everything really new has still to be proved. Plenty of things hailed as wonderful achievements for that year, by some enthusiasts invited to contribute to the summary, turn out in later years to be inglorious flops. But over a decade and a half, betterments that are really such become self-evident, and recounting some of them can be done without guesswork or wishful thinking. An inventory of what was known and utilized in 1929 compared to what is now known and used is not too hard to make. Perhaps the most clear-cut picture of what is known and used at a certain date is drawn by the handbooks, textbooks, and equipment catalogs of that date, with scientific periodical literature forecasting what knowledge may later be used when it is verified and assimilated. The tools available for production or for research limit the application of old and the finding of new knowledge.

Jan 1, 1945

By E. W. Lithgow, E. G. Williams, R. R. Holbrook, B. R. Wilson

The mineralogy and geochemistry of Pennsylvanian shales and underclays were studied to determine their suitability for lightweight aggregate and refractory ladle brick. Eighty percent of the variation in bloating of shales and clays was explained by the variation of Si02, A1203, and fluxes (Fe203, MgO, CaO, Na20, and K20); 60% by variation in quartz, kaolinite, illite, and chlorite. The best bloating was exhibited by marine shales, whereas freshwater shales and underclays experienced little or no expansion. Regional paleogeographic maps o f Pottsville and Allegheny shales permit bloating to be geographically predicted. It was found that clays meeting the specifications for refractory ladle bricks were obtained from underclays having over 34.5% mica, over 40% kaolinite and less than 15% quartz. Underclays of this composition are confined to the lower Allegheney outcropping along the near-margins of the coal basin. The best clay is that underlying the Lower Kittanning coal. Porosity of the first fired brick was found to be inversely correlated with reheat expansion.

Jan 1, 1975

Papers published by the Institute are issued in a variety of forms MINING TECHNOLOGY, issued every other month, contains the TECHNICAL PUBLICATIONS on Metal Mining, Minerals Beneficiation (milling and concentration), Industrial Minerals (nonmetallic) and Mining Geology, Mining Administration, and Geophysics papers relating to Metal Mining (A, B, H, I, K, L ) METALS TECHNOLOGY, issued eight times a year, contains the TECHNICAL PUBLICATIONS of the Iron and Steel Division and the Institute of Metals Division, and once or twice during the year those on Non-ferrous Metallurgy (reduction and refining of nonferrous metals) (C, E, and D ) PETROLEUM TECHNOLOGY, issued every other month, contains the TECHNICAL PUBLICATIONS of the Petroleum Division, together with Geophysics papers relating to -the finding of Petroleum (G, L ) COAL TECHNOLOGY, issued four times a year, contains the TECHNICAL PUBLICATIONS of the Coal Division (F ) MINERAL INDUSTRY EDUCATION DIVISION papers appear in a TECHNOLOGY according to classification of subject matter DISCUSSIONS appear in the respective TECHNOLOGY as available MINING AND METALLURGY is the monthly magazine, which contains papers of general interest and news of the membership

Jan 1, 1952