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By Lars Rossemyr, Terkel Rosenqvist

The equilibrium Mn + 2 IiCl = MnCl2(g) + H2 has been studied at 1090°C for pure manganese and for Mn-Si alloys. For this reoction a standard free energy of Fo1363, = - 19,700 i 300 col ioas found. Combined with other thermal data, the standard free energy of the reaction Mn(s, ß) + Cl2 = MnCl2(g) was derived: Fo=- 56,140 + 9.78 T log T - 40.10 T For the formation of the various manganese silicides the following free energies were obtained. 5 Mn + 3 Si - M1z5Si3 ?F°1363 = -41,500 i 1500 cal Mn + Si - h.lnSi ?F°1363= -10,000 i 500 cnl Mn + 2 Si = MnSiz ?F°1363= -11,500 ± 500 cal In the search for a method suitable for the study of thermodynamic properties of certain alloy systems, it was found that the heterogeneous equilibrium between the alloy and a gas mixture consisting of hydrogen chloride, hydrogen, and volatile metal chlorides has considerable advantages. In addition to giving thermodynamic information about the alloys, such measurements may be used to derive thermodynamic data for the volatile metal chloride itself. The present paper gives some results which were obtained for manganese silicides and manganous chloride. Similar studies are presently being carried out for the iron silicides. The phase diagram of the Mn-Si system is rather well known,' but no information exists to the authors' knowledge about the thermodynamic properties of manganese silicides or about the chemical activities in molten Mn-Si alloys. At elevated temperature, manganese may react with hydrogen chloride according to the equation: Mn(s, ß ) + 2 HC1 = MnC1, (g ) + H2 [ 1] with the equilibrium constant The value of K, may be determined from measurements of the gas composition in equilibrium with pure manganese. When this value is used in connection with measurements on manganese alloys, the chemical activity of manganese in the alloy may be derived. Initial calculations showed that around 1000" to 1200°C the equilibrium constant K1 has a value of a few thousand, i.e., the reaction is shifted far to the right. In order to study this rather unbalanced gas composition, a flow method was used in two slightly different modifications. For all experiments with manganese silicides and for some experiments with pure manganese the apparatus shown on Fig. 1 was used. A bed of the metal or alloy was placed in a tube furnace. The refractory tube had an internal diameter of 14 mm and the bed was 75 mm long. Electrolytic manganese of high purity and silicon, 99.95 pct Si, were used as raw materials. All alloys were prepared by melting weighed amounts of the elements in a high frequency induction furnace in argon atmosphere. The melting was done in a silica crucible which was placed inside a graphite shell. The alloys were crushed to - 10 +40 mesh and analyzed chemically. Also, for the pure elements, the same size fraction was used. A controlled gas mixture of purified hydrogen and from 3 to 12 pct HC1 was passed through the bed where it reacted with manganese according to Eq. [I]. The volatile manganese chloride was collected in a condenser placed in the cooler part of the furnace tube. The gas mixture before and after the furnace was sampled and analyzed by absorption of

Jan 1, 1962

By Charles Prasky

ABOUT five years ago the Bureau of Mines began a study, at Minneapolis, of the various methods for beneficiating the low-grade manganese deposits of the Cuyuna range. Several samples of green carbonate slate from the Cuyuna range, containing about 7 pct Mn and about 28 pct Fe, were obtained for this study. The component minerals in the carbonate slate formation were so intimately associated that mineral dressing methods were not suitable for concentrating manganese to a ferrograde product. Although upgrading of manganese and iron minerals has been effected by flotation methods, it appears that manganese cannot be separated from iron except by chemical means. Because the flotation studies at Minneapolis were carried out simultaneously with the hydrometallurgical studies, only crude slate was available for process testing. An important economic consideration in selecting any one of the several chemical methods proposed for recovering ferrograde manganese is the availability of the chemical reagent. Fortunately, large tonnages of sulfur are available on the Cuyuna range in low-grade pyrite and pyrrhotite deposits that are readily concentrated by flotation to a suitable feed for a sulfide roasting furnace as indicated by a Bureau of Mines investigation in 195 0-1951.1 The roasted residue from the sulfide concentrates is a potential source of marketable iron oxide. Therefore, if these sulfide deposits were employed in recovering manganese, utilization of two heretofore unused mineral deposits would be accomplished. Laboratory investigations of several proposed leaching processes were made as a preliminary step in the investigation of hydrometallurgical methods for the treatment of Cuyuna carbonate slate using sulfur as a chemical reagent. From results obtained in the laboratory tests, these leaching processes did not appear entirely suitable for treating Cuyuna carbonate slate. The method developed at the North Central Experiment Station and selected for a more intensive pilot-plant investigation has been termed the differential high-temperature sulfatizing process. Essentially, this sulfatizing process consists of the following steps, described in the order in which the small-scale pilot-plant investigations were made. The first and perhaps most significant step in the process consists of a sulfate roast. Carbonate slate is roasted in an atmosphere of sulfur dioxide gas and air. The overall chemical reaction for converting manganese carbonate to a sulfate at a high temperature in a sulfur dioxide atmosphere follows MnCO8 + SO2 + 1/2 0, = MnSO4 + CO2 (H077°O = —64,180 cal per g mol) .' The need for concentrated sulfuric acid is avoided. Fine grinding is not essential. Removal of carbon dioxide from the slate during roasting produces a more porous structure and permits easier permeation by the sulfatizing gas mixture. The temperature limits for this conversion of manganese have been established as 600" and 850°C. Iron sulfate is unstable and is not formed at these temperatures; phosphorus is not converted to a water-soluble form; and polythionates are not formed. The second step in the process consists simply of a water leach of the sulfatized product. Manganese sulfate in the sulfatized product is dissolved in water. Iron, phosphorus, and calcium remain in the leach residue as water-insoluble products. The third and final step consists of the recovery of ferrograde manganese oxide from manganese sulfate leach solution. Water is evaporated from the leach solution, and impure monohydrate crystals of manganese sulfate are recovered. The moist crystals are formed into pellets or extrusions and thermally decomposed to produce a ferrograde manganese

Jan 1, 1958

By E. N. Cameron

GRAPHITE has been included in U. S. lists of strategic minerals since the problem of mineral deficiencies was revealed during World War I. Since 1918 the domestic graphite industry has led a precarious existence, and there has been much uncertainty as to the amounts of usable graphite of various grades that would be available from domestic sources in time of emergency. In 1950-1951 therefore, the writer, assisted by Paul L. Weis, undertook a review of domestic graphite sources for the U. S. Geological Survey.' The conclusions of this study are presented here, with a discussion of some technologic and politico-economic factors bearing upon the problem. Uses of Graphite: Natural graphite as marketed exhibits a wide range of properties, which determine the uses to which it is put. The most essential uses are in the manufacture of crucibles and related refractory articles, in lubricants and packing materials, and in the manufacture of batteries, foundry facings, pencils, and carbon brushes. Numerous specifications covering the mineral in its various applications must be met by producers and processors of graphite. The problem of supply is therefore not simply one of procuring a sufficient total tonnage, but the more difficult problem of procuring enough of each different grade to meet foreseeable needs. The amount of graphite required by American industry is not large. Ordinarily only a few thousand tons of strategic grades are consumed annually, yet the elimination of this small tonnage would have serious effects in several industries. Strategic Graphite: Since World War I, 60 to 100 pct of the country's annual supply of graphite has been furnished from imports. At present, natural amorphous graphite for use in pencils and batteries is produced largely from American-owned mines in Mexico. Graphite for foundry facings is obtained from a number of sources. Neither grade is a serious problem. High purity graphite for carbon brushes and for pencil leads, however, is imported, largely from Ceylon, in the form of amorphous lump graphite. Most of the flake graphite used for crucibles and related refractory articles is likewise imported, largely from Madagascar, and much of the lubricant and packing grade graphite used by industry is obtained from the same source. The strateg'ic grades of graphite are therefore amorphous lump of the Ceylon type, crucible flake, and flake suitable for lubricants and packing. Ceylon lump and Madagascar flake have for many years been accepted as standard by domestic consumers of graphite, and various essential manufacturing processes are geared to the use of graphite from these sources. Ceylon graphite as marketed is classified into several grades based on particle size and purity. Processing methods are said to be simple, but the products marketed are carefully graded and are consistent in their characteristics, an important matter to the consumer. Nearly all the graphite produced in Ceylon is from veins. Resources are reported to be large, labor is cheap, production costs are low, and world competition is slight—factors accounting for the commercial success of the graphite mining industry in Ceylon. Madagascar is reported to have deposits of the Ceylon type, but its output consists almost entirely of flake. Madagascar graphite as received in the U. S. is further processed by importing organizations, and a large number of grades are produced to meet industry requirements, especially those for crucible flake and for lubricant and packing grade flake. Madagascar crucible flake as marketed is noted for coarseness, uniformity, toughness, clean-

Jan 1, 1957

By Robert A. Rapp, Jan E. Verfurth

From the measurement of internal-oxidation band widths in Ag-In and Cu-A1 alloys, products for the solubility No and the diffusivity Do of oxygen in silver and apparent NODo products in copper have been obtained over a range of temperature. The NODO products for silver are in agreement with the product of the individually determined No and Do values of Eichenauer and Müller. Although interstitial diffusion of oxygen in silver is expected, the temperature-independent factor Do of the diffusion coefficient does not agree well with the theory of Wert and Zener. For Cu-A1 alloys internal oxidation does not follow the expression derived for ideal kinetics, since the apparent NODo product calculated from internal-oxidation measurements is a function of the alloy content in the specimen. Thus, unequivocal values for No or DO or even the product NODO in copper are not available from the literature. RELIABLE values for the saturation solubility NO and diffusivity DO of oxygen in fcc metals are lacking and difficult to determine, partially because internal-friction measurements are not applicable. Permeability experiments and Sieverts7-type adsorption -desorption methods3 have met with difficulty; however, Eichenauer and Müller4 have recently reported on the solubility and diffusivity of oxygen in silver as determined by the latter technique . Rhines, Johnson, and Anderson,5 and independently Meijering and Druyvesteyn,' introduced the possibility of deriving values for the product NODO in a metal from measurements of the widths of internal-oxidation zones (subscales) formed during the internal oxidation of alloys. In addition to these authors, several other investigators7-9 have made such measurements in various silver and copper alloys at various temperatures, mostly using me- chanically polished specimen surfaces. The purpose of this investigation was to determine over a range of temperature the calculated products NODO in silver and copper from systematic measurements of the widths of internally oxidized zones in Ag-In and Cu-A1 alloys, using specimens with electro-etched surfaces. Consider the internal oxidation of a dilute solid-solution alloy in which the base metal is not oxidized. If diffusion of oxygen is the rate-controlling step, then the depth 5 of the internal-oxidation zone is given by where y is a dimensionless parameter and t the oxidation time. Based on the solution of the diffusion equation, wagnerl0 has shown that under certain conditions several mathematical simplifications may be used in the evaluation of y, so that Eq. [I] may be expressed for the case that y « 1, and y(Do/DB) 1, where N(so)the is the equilibrium solubility (mole fraction) of oxygen in the solvent metal for the given oxidizing atmosphere, is the mole fraction of the solute metal in the bulk alloy, 4 is the diffusivity of the solute in the base metal, and v is the ratio of oxygen atoms to solute atoms in the precipitated oxide BO,. Rearranging Eq. [2] Maak' has derived an expression analogous to Eq. [3] for the case that an external-oxide scale, in addition to an internal-oxidation zone, is formed. For this combined external and internal oxidation for the case that 5/2 where 5 is the distance of the internal-oxidation front from the original external s.urface, and X is the distance of the external oxide/metal interface from the original external interface. The function F is defined by the expression

Jan 1, 1964

By Paul Weir

During the past decade, methods of producing bituminous coal in the state of Illinois, which ranks third in production among the states in which bituminous coal is mined, have undergone great changes. From less than one million tons in 1923, the strip-mine production has gradually increased to a high of 11,725,870 tons in 1937. From a negligible amount prior to 1927, the amount of coal mechanically loaded underground had increased to a high of 28,374,362 tons in 1937. The amount manually loaded in 1937 reached a low of 12,332,023 tons. In this same year, this state ranked first in strip-mine production, also in mechanically loaded production. For this reason a study of the influence of mechanization on location of production in Illinois may be helpful in anticipating what may happen in other producing states. The reason for the changes in methods lies in the differences in costs of production. The Bureau of Research and Statistics of the National Bituminous Coal Commission has made public the following costs of production by various methods in the state of Illinois (district 10) for the last nine months of 1937: all mines, $1.7602 per ton; strip mines, $1.4319; mechanical loading mines, $1.7457; hand loading mines, $2.1793; all underground mines, $1.8703. These are weighted averages for the entire district. Inasmuch as production in 1937 was reported from 58 counties scattered over two-thirds of the area of the state and from five different seams varying in thickness from less than 3 ft. to as much as 12 ft., it is apparent that the location of production must be influenced by the extent of mechanization possible in the various producing counties. SHIFT in Production The term "mechanization" is commonly used to designate the coal-loading operation. However, in a broader sense it embraces the use of any and all mechanical and electrical equipment on the surface and underground. Strip mining is an intensive form of mechanization. The mechanical cleaning of coal is a form of mechanization. Cutting machines and motor haulage likewise are forms of mechanization, hence

Jan 1, 1940

By Paul Weir

During the past decade, methods of producing bituminous coal in the state of Illinois, which ranks third in production among the states in which bituminous coal is mined, have undergone great changes. From less than one million tons in 1923, the strip-mine production has gradually increased to a high of 11,725,870 tons in 1937. From a negligible amount prior to 1927, the amount of coal mechanically loaded underground had increased to a high of 28,374,362 tons in 1937. The amount manually loaded in 1937 reached a low of 12,332,023 tons. In this same year, this state ranked first in strip-mine production, also in mechanically loaded production. For this reason a study of the influence of mechanization on location of production in Illinois may be helpful in anticipating what may happen in other producing states. The reason for the changes in methods lies in the differences in costs of production. The Bureau of Research and Statistics of the National Bituminous Coal Commission has made public the following costs of production by various methods in the state of Illinois (district 10) for the last nine months of 1937: all mines, $1.7602 per ton; strip mines, $1.4319; mechanical loading mines, $1.7457; hand loading mines, $2.1793; all underground mines, $1.8703. These are weighted averages for the entire district. Inasmuch as production in 1937 was reported from 58 counties scattered over two-thirds of the area of the state and from five different seams varying in thickness from less than 3 ft. to as much as 12 ft., it is apparent that the location of production must be influenced by the extent of mechanization possible in the various producing counties. SHIFT in Production The term "mechanization" is commonly used to designate the coal-loading operation. However, in a broader sense it embraces the use of any and all mechanical and electrical equipment on the surface and underground. Strip mining is an intensive form of mechanization. The mechanical cleaning of coal is a form of mechanization. Cutting machines and motor haulage likewise are forms of mechanization, hence

Jan 1, 1940

By H. M. Warrren

IN the past, steam engines were used in practically all cases for driving the machinery, in and about an anthracite breaker, and hence little or no accurate data were available as to the power requirements for starting and operating the individual machines, which make up the complete equipment. It was impossible to segregate the power necessary to drive each individual machine, first, because the equipment was driven in groups, and second, because it was impracticable to obtain graphic, integrated, or instantaneous records of the horsepower used. As a result of these conditions, it was found, when individual electric motors were applied to the various machines, that more accurate and complete data were needed in order to provide motors of the proper power and design for the particular services to be rendered. In order to obtain the desired information, the writers made and collected a number of tests, from time to time, on the individual motor drives in- electrically operated breakers, and as these tests have been of great value, it occurred to them that a paper giving the results might be of service to other engineers interested in similar installations. Table I shows the .results of these tests. All the motors tested were of the three-phase, 60-cycle, 440-volt, induction, squirrel-cage type, except a few, which, on account of size and starting conditions, were of the wound-rotor type. The instruments used in making these tests were: An integrating watt-hour meter, a graphic ammeter, and a graphic voltmeter. These instruments were connected in each motor circuit, and a record of a day's run of 9 hours was obtained from each machine. From these tests, the running light load, the average all-clay load, and the instantaneous peak readings in amperes, volts, and kilowatt input, were obtained. By means of the characteristic curves obtained from these motors at the factory, the power factor, the efficiency, and the horsepower output were calculated for each particular test. Starting tests were made by the brake-arm method, in which the torque in pounds was measured directly on a spring balance.

Jan 2, 1916

By H. Landsberg

IN a previous report1 it was pointed out that a successful attack on roof troubles has to be preceded by extensive scouting. As Lord Kelvin once said, scientific progress can be made only if accurate data are available: "unless you measure, you do not know.? THE CONVERGENCE RECORDER For the observation of roof movements in mines the convergence recorder has shown that it will enable us to get some of the necessary information. Results with convergence recorders were first published by Winstanley and other English investigators for rapidly moving longwall faces. In their investigations the speed of work and the heavy over-burden produced a considerable amount of absolute values of convergence in a short time. Under the conditions frequently encountered in our investigations in Central Pennsylvania, under shallow, overburden and in mines with slowly proceeding extraction, the movements observed were much less in absolute value, for an equal interval of time. This was partly because the mines in which our studies were carried on frequently had idle days, sometimes four or five in succession. Therefore continuous records were not employed and a simple convergence gauge was built. In its first models, it consisted only of two telescoping tubes pressed against roof and floor by a coil spring. At the side of the lower tube a rule divided into 1/-mm. divisions was fixed and a knife-edge, which was attached to the upper tube, was slid over the scale in case of convergence between roof and floor. While the larger motions could be read on this device, it seemed to be desirable to increase the accuracy by inserting between the two tubes a dial meter reading in 1/1000 in. Such a gauge was first built in April 1937 and installed for experimental purposes in a bituminous coal mine in Pennsylvania (Fig. 1). It was read at least once daily, 24 hr. apart, and if feasible at shorter intervals. After several months of experience it can be said that this type of gauge answers the scientific as well as the practical needs. It is easier to handle than the recorder; no clock is used, there are no pen troubles. The price of

Jan 1, 1938

By H. Landsberg

In a previous report1 it was pointed out that a successful attack on roof troubles has to be preceded by extensive scouting. As Lord Kelvin once said, scientific progress can be made only if accurate data are available: "unless you measure, you do not know." The Convergence Recorder For the observation of roof movements in mines the convergence recorder has shown that it will enable us to get some of the necessary information. Results with convergence recorders were first published by Winstanley and other English investigators for rapidly moving longwall faces. In their investigations the speed of work and the heavy overburden produced a considerable amount of absolute values of convergence in a short time. Under the conditions frequently encountered in our investigations in Central Pennsylvania, under shallow, overburden and in mines with slowly proceeding extraction, the movements observed were much less in absolute value, for an equal interval of time. This mas partly because the mines in which our studies were carried on frequently had idle days, sometimes four or five in succession. Therefore continuous records were not employed and a simple convergence gauge was built. In its first models, it consisted only of two telescoping tubes pressed against roof and floor by a coil spring. At the side of the lower tube a rule divided into 1/2-mm. divisions mas fixed and a knife-edge, which was attached to the upper tube, mas slid over the scale in case of convergence between roof and floor. While the larger motions could be read on this device, it seemed to be desirable to increase the accuracy by inserting between the two tubes a dial meter reading in 1/1000 in. Such a gauge was first built in April 1937 and installed for experimental purposes in a bituminous coal mine in Pennsylvania (Fig. I). It was read at least once daily, 24 hr. apart, and if feasible at shorter intervals. After several months of experience it can be said that this type of gauge answers the scientific as well as the practical needs. It is easier to handle than the recorder; no clock is used, there are no pen troubles. The price of

Jan 1, 1938

By Walter B. M. Davidson

Phosphorus is one of the elements having the widest distribu tion, and phosphoric acid plays an important part in the composition of the crust of the earth. It is allied in various chemical combina- tions with many bases, of which lime, alumina and iron are the most common. It is difficult to state in what chemical combination phosphoric acid predominates in the crust of the earth, for while phosphate of lime, as the mineral which is sought for and found in deposits of economic value is the most familiar, it is probable that the phosphates of alumina and iron are the most usual forms in which phosphoric acid exists in all soils not essentially calcareous. It has been shown by thousands of analyses that all fertile soils contain from a trace to 0.5 per cent. of phosphoric acid. All limestones, dolomites and chalks contain it in proportions which, though usually small, are large enough to make careful analysis necessary in the selection of limestone as flux for iron-smelting. It is generally Trenton limestones that are found best for this purpose, the more recent strata being more phosphatic. In some places phosphoric acid replaces carbonic acid, and the limestone or chalk becomes phos phatic to a large degree, or sometimes pure phosphate of lime. The waters of the ocean, from very early periods, have contained phosphoric acid. Different analyses show varying contents; it is asserted that some portions of the Gulf Stream are more phos phatic than the surrounding waters of the Atlantic. Many springs, usually from limestone regions, contain soluble phosphates in vary ing quantities. I think it safe to assert that phosphorus is nearly the most widely and evenly distributed element on the surface of the earth, and probably the most subdivided. This can be readily understood when the important part which phosphoric acid plays and has played in the vital cosmos is taken into consideration. Phosphorus was on the earth in gaseous, liquid or solid form before the dawn of life, and since then all animal and vegetable creation have combined with the

Jan 1, 1893

By H. Landsberg

In a previous report1 it was pointed out that a successful attack on roof troubles has to be preceded by extensive scouting. As Lord Kelvin once said, scientific progress can be made only if accurate data are available: "unless you measure, you do not know." The Convergence Recorder For the observation of roof movements in mines the convergence recorder has shown that it will enable us to get some of the necessary information. Results with convergence recorders were first published by Winstanley and other English investigators for rapidly moving longwall faces. In their investigations the speed of work and the heavy overburden produced a considerable amount of absolute values of convergence in a short time. Under the conditions frequently encountered in our investigations in Central Pennsylvania, under shallow, overburden and in mines with slowly proceeding extraction, the movements observed were much less in absolute value, for an equal interval of time. This mas partly because the mines in which our studies were carried on frequently had idle days, sometimes four or five in succession. Therefore continuous records were not employed and a simple convergence gauge was built. In its first models, it consisted only of two telescoping tubes pressed against roof and floor by a coil spring. At the side of the lower tube a rule divided into 1/2-mm. divisions mas fixed and a knife-edge, which was attached to the upper tube, mas slid over the scale in case of convergence between roof and floor. While the larger motions could be read on this device, it seemed to be desirable to increase the accuracy by inserting between the two tubes a dial meter reading in 1/1000 in. Such a gauge was first built in April 1937 and installed for experimental purposes in a bituminous coal mine in Pennsylvania (Fig. I). It was read at least once daily, 24 hr. apart, and if feasible at shorter intervals. After several months of experience it can be said that this type of gauge answers the scientific as well as the practical needs. It is easier to handle than the recorder; no clock is used, there are no pen troubles. The price of

Jan 1, 1938

By I. J. Gardescu

The production of petroleum in Rumania in 1932 totaled 52,560,000 bbl., an increase of 6.8 per cent over 1931. The average daily production rose from 123,000 bbl. at the beginning of the year to 173,000 bbl. at the end of the year, the production in the Gura-Ocnitzei field rising from 38,800 to 80,700 bbl. per day. This increase was due to competitive development during which time the percentage of total production of the various operating companies remained practically unchanged. Chief producers were: Concordia, 30.3 per cent; Unirea, 21.6; Romano-Americana, 13.5; Steaua Romana, 8.3. Boldesti, where production of the previous year was practically doubled, would have produced far greater quantities were it not for the fact that both Astra Romana and Romano-Americana curtailed drilling operations. Of the total daily production of 21,800 bbl. a day, the Astra Romana, Steaua Romana and Romana Americana, produced respectively 67, 25 and 8 per cent. The Moreni field showed a sudden drop in production from the preceding year, due primarily to reduced drilling activities. Its production of only 21,000 bbl. a day removes it from first position for the first time in many years. All the other fields showed a decrease in production, except Ochiuri, 3 miles west of Gura-Ocnitzei, and Ceptura, 12 miles east of Boldesti. Drilling1 During the first nine months of 1932, 116 wells were completed, 8 of which were dry holes. The Meotian (lower Pliocene) is the producing horizon in 73, the Dacian (upper Pliocene) in 31, and the Oligocene in 4 of the completed wells. Three of the Oligocene wells were drilled in the Bacau district and one at Grausor, near Campina. In addition, 47 wells were drilling on Oct. 1,1932. Of the total completions and drilling wells, 92 per cent employed rotary for a footage of 98.5 per cent of the total drilled. Power for rotary drilling was furnished to 105 wells by steam, to 38 by electricity, and to one by gasoline.

Jan 1, 1933

By K. A. Lambert

In the Anthracite Region there are considerable areas where the original mining was done 50 or more years ago. In this original mining, the pillars that were left proved inadequate in size for the support of the roof, which has since collapsed as a result of squeezes, and completely filled the original openings. In an endeavor to recover the coal which remains in the pillars in such areas, the reopening cost for development, as well as for pillar recovery, has been excessive in many instances. Various methods have been tried out with a view to lowering the cost, in order that the greatest possible percentage of recovery of the reserve tonnage may be realized economically. Ordinary hand mining necessitates the driving of development road 10 ft. wide in the clear between timber legs, with 6 ft. of clearance over the rail to accommodate mine cars; collars or crossbars on the timber sets have been difficult to maintain in these openings in the heavily caved condition, especially in beds where the overburden is great,. Numerous failures have occurred on these development road timbers because of roof movement resulting from removal of pillars. The actual removal of pillars from this development work has been costly because full-width openings for transporting mine cars to the face have to be maintained by cleaning caved material from alongside the pillars, or skipping up along the pillars where pillars of sufficient width are found. Shaker-chute Methods A method of developing such caved conditions and recovering pillars tributary to this development, utilizing shaker chutes, is being tried out with considerable success at Loree colliery. An outline of the chute and apparatus is shown in Fig. 1, which indicates the location of pillars and caved material. The cost of both labor and material required in the recovery of such coal is considerably less than by ordinary hand methods. In order to try out this method of mining a location was chosen where a tightly caved area had been developed by ordinary hand methods to within 300 ft. of the property line. The original bed height was 12 ft., with an overburden of 325 ft., but on account of the squeezes which

Jan 1, 1931

By E. M. Norris

In the summer of 1917 it was decided to fireproof the main Tramway hoisting shaft of the Anaconda Copper Mining Co. at Butte, Mont. The shaft has three hoisting compartments and one pump compartment; it is timbered with 12 by 12-in. (30.5 by 30.5-cm.) fir timber, and is 2475 ft. (754 m.) deep. Subsidence and displacement of the surrounding country rock had produced exceedingly heavy ground, and had carried the shaft out of line, in several places, by as much as 2 ft. (0.6 m.) displacement. Constant repairing and realigning of the timbers had been necessary in order to maintain clearance for the cages. The most feasible method of fireproofing, therefore, seemed to be to cover the timbers with a coat of concrete applied with the cement gun. The cement gun, which is operated by compressed air at ordinary mine pressures, feeds a mixture of sand and cement through a hose to a nozzle having a water connection. The mortar in fluid form is thus sprayed upon the prepared surface in thin layers, which can be built up to any desired thickness. The cement gun can be set up at any convenient point; satisfactory results have been obtained with the nozzle a distance of 500 ft. (152 m.) from the gun. The shaft was thoroughly overhauled and the timbers put in the best possible state of repair. Between the 1000 and the 1400 levels, much loose ground lay against the shaft timbers on the north side; this was breast-boarded back and a 30-in. (76-cm.) reinforced-concrete retaining wall was erected, leaving a space of 12 in. (30.5 cm.) outside the shaft timbers to allow for future movements of the ground. For convenience in handling men and materials, it was arranged to concrete the auxiliary hoisting-cage compartment and the pump compartment first, using the cages of the main hoist to serve the cementing crews. The auxiliary cage was then available while the remainder of the shaft was being concreted. A tight partition of 2-in. (5.08-cm.) plank was erected between the auxiliary and the adjoining hoisting compartments, for better protection of men riding on the cages. The application of concrete made this

Jan 1, 1920

By George H. Ashley

Mining, including quarrying, dates back almost to the dawn of history, beginning almost with the beginning of what we call civilization. State surveys date back about 100 years. Evidently mining flourished for thousands of years before state surveys were thought of. Why should it not continue to flourish without state surveys? First, it may be noted that as mining and civilization were contemporaneous, so state surveys and the science of geology were almost contemporaneous. As recently as 30 years ago the United States mineral laws were interpreted to mean that coal lands in the public domain were only those lands on which workable coal outcropped. The half billion acres of public land underlain by .coal but on which it did not outcrop were treated as homestead lands and open to settlement. Just what did the science of geology do to or for the mining industry? Until geology arose rocks or minerals or ores were where they were found. Their finding might be accidental, or might be the result of deliberate search or prospecting. In open, rocky country, with little or no vegetation, as in parts of the West, prospecting served very well, though at an enormous expenditure of human time and effort, if not money. The old saying that every dollar's worth of gold taken from the earth has cost two dollars may largely be charged to the time value of the usual method of prospecting. Geology changed all that. The science is still young and it still labors under handicaps of immaturity and early errors. Geology, however, has gradually been discovering the relations and conditions under which the several mineral deposits occur. Its elaborate studies of exhausted or nearly exhausted mineral deposits has done for it what human autopsy has done for medicine and surgery. Perhaps in no field is this plainer than in the oil and gas industry. Note might also be made of several important coal fields in England and on the Continent, in which the coal is everywhere deeply buried. Passing over the long period of growth during the past 100 years, geology today is prepared to offer the mining industry: first, a knowledge of the geologic conditions under which most minerals occur and to explore

Jan 1, 1935

By C. R. Dodson, W. T. Cardwell

This paper presents the results of a theoretical and experimental study of the effect of preperforated liners on well productivity. The analysis concerns the rectangular type of slot, either machine or torch cut, which is common in California. Muskatla treated this problem recently in a mathematical analysis of the flow of oil or gas from natural reservoirs into both gun-perforated and slotted liners. This paper presents additional and simplified analytical considerations and conclusions for the slotted liner, the solutions being applicable in the laboratory as well as in the field. An application of the analytical methods to permeability measurements on mounted core samples is given, to show the effects of sealing wax or other obstructions on the end faces of the cores. Results Fig. I 'Ompares the results of some theoretical calculations with the results of electrical analogy experiments performed in the Standard Oil Company of California's Production Technology Laboratory at La Habra, California. Fig. I indicates that the flux into short, "three-dimensional slots" of the relative dimensions encountered in practice is approximately equal to that into full-length, "two-dimensional slots" having the same open fraction of pipe. (The same numbers of slot rows, and the same radius ratio are also implied.) It can be seen from physical considerations that the closeness of this approximation must improve as the ratio of the external radius to the internal radius increases. Therefore, it is possible to calculate the flow into a slotted liner using a simple modification of the Darcy equation: where N is .the number of slot rows and O is the open fraction of the pipe. Fig. 2 shows the results of calculations . using Eq. 28. The most remarkable features of Fig. 2 are the high flux values for very small open fractions of pipe. For instance, with six slot rows and a radius ratio of 500, 74 per cent of the open-hole flux may be obtained with only o.I per cent of pipe Open. Fig. 2 shows that for a given open frac tion of pipe, the flux is greater, the greater

Jan 1, 1945

By George H. Ashley

Mining, including quarrying, dates back almost to the dawn of history, beginning almost with the beginning of what we call civilization. State surveys date back about 100 years. Evidently mining flourished for thousands of years before state surveys were thought of. Why should it not continue to flourish without state surveys? First, it may be noted that as mining and civilization were contemporaneous, so state surveys and the science of geology were almost contemporaneous. As recently as 30 years ago the United States mineral laws were interpreted to mean that coal lands in the public domain were only those lands on which workable coal outcropped. The half billion acres of public land underlain by .coal but on which it did not outcrop were treated as homestead lands and open to settlement. Just what did the science of geology do to or for the mining industry? Until geology arose rocks or minerals or ores were where they were found. Their finding might be accidental, or might be the result of deliberate search or prospecting. In open, rocky country, with little or no vegetation, as in parts of the West, prospecting served very well, though at an enormous expenditure of human time and effort, if not money. The old saying that every dollar's worth of gold taken from the earth has cost two dollars may largely be charged to the time value of the usual method of prospecting. Geology changed all that. The science is still young and it still labors under handicaps of immaturity and early errors. Geology, however, has gradually been discovering the relations and conditions under which the several mineral deposits occur. Its elaborate studies of exhausted or nearly exhausted mineral deposits has done for it what human autopsy has done for medicine and surgery. Perhaps in no field is this plainer than in the oil and gas industry. Note might also be made of several important coal fields in England and on the Continent, in which the coal is everywhere deeply buried. Passing over the long period of growth during the past 100 years, geology today is prepared to offer the mining industry: first, a knowledge of the geologic conditions under which most minerals occur and to explore

Jan 1, 1935

By Hans W. Brodbeck

The main problem in tunneling without the use of explosives lies in the development of tools capable of continuous mechanical destruction of rock, resulting in a fragmentation which lends itself to a smooth, uninterrupted transportation of the broken rock away from the tunnel face. While all moles of U.S. design mainly achieve this by crushing the rock by means of "disk cutters" or "roller bits," a boring system based on the principle of cutting the rock came into being in Europe, whereby the rock is worked in a manner very similar to the milling of metals. For tunneling purposes, this principle was first developed by the late Austrian engineer Wohlmeyer. Between late 1962 and the spring of 1965, the first experimental machine was tested in a German coal mine, working in coal and shale over a distance of some 3000 ft, divided over two runs separated by a period of time to allow for equipment modifications. In 1964, a collaboration was started between Wohlmeyer and the Habegger engineering firm of Thun in Switzerland. The normal Habegger range of equipment consists of aerial ropeways, ski lifts, and certain tool machines, to which in later years have been added monorail passenger-transport systems. One of these was installed as the main mode of transport at the 1967 World Fair in Montreal. After taking over the Wohlmeyer patents, Habegger further developed the original cutting principle, aiming at more robust machines in order to be able to tackle harder rock. A first machine was built and tested at a site near Thun in sandstone averaging 17,000 psi compressive strength and limestone of 25,000 psi. In May 1966 this machine was delivered to Japan for the boring of a pilot tunnel for the Honshu-Hokkaido railway connection under the sea. A second machine, incorporating many improvements based on experience gained with this first mole, was built during 1966 and tested in the same limestone as mentioned previously (25,000 psi), before being installed to bore the head race tunnel of the Julia hydroelectric power scheme near St. Moritz, Switzerland, in the early summer of 1967 (Fig. 1 ) .

Jan 1, 1970

Discussion of the paper of R. H: Sweetser,. presented at the Cleveland meeting, October, 1912, and printed in Bulletin No. 71, November, 1912 pp. 1327 to 1334. See also Bulletin 11 No. 72, December, 1912, pp. 1561, 1562. J. J. HOWARD, Dover, N. J. (communication to the Secretary*) :-No doubt there are as many different methods of starting a blast-furnace as there are men who assume that responsibility. Having blown-in a furnace a few years ago in a manner similar to that outlined by Mr. Sweetser, things went along so well at the start that I had time for a little reflection on what was going on inside the furnace. I saw the wood turned to charcoal practically, and it occurred to me, why should I use wood when I could put in the charcoal in the. first place, and thus save a lot of time, and also eliminate the dangerous gas from the wood, which is the cause of most of the accidents in starting up a furnace. I had a furnace out for repairs and decided to use no cord-wood in blowing in. I put in about a carload of charcoal and used no wood except some shavings and oily waste at each of the tuyeres. The furnace had 16 tuyeres and was 100 by 22 by 14.5 ft. Hot rods were put in each tuyere' and the blast started immediately at 11 a.m. Within 5 mill. the air was all driven out of the stack and the gas lighted of its own. accord at the top of the furnace. It was allowed to burn for 5 min. longer and then the bell was closed and the gas taken to the last stove and the last boiler on the gas-main. It was all clone so quietly that it was hard to realize that the gas was down. The tuyeres were as bright as if the furnace had been in blast for a long time. I have learned since that others have used the same method, but they had not passed the good advice along.

Jan 5, 1913

By George Wendell

THE fact that a symposium on pyrometry is being held under the auspices of the American Institute of Mining and Metallurgical Engineers may very properly be taken as a recognition of the importance of temperature measurements and control in production and in the industries, and of the need for instruction in pyrometry in our schools of engineering. Though there may be general agreement as to the need of some instruction along this line, there will undoubtedly be divergence of opinion as to the amount of time that can be allowed to such instruction, as well as to its character. Those who have given little attention to the complexity of high-temperature measurements will be apt to think that a few simple experiments are all that is required. They fail to distinguish between the artisan, who merely has to learn how to use any piece of apparatus that is installed, and the technically trained man, who must be prepared to assume the responsibility for the supervision and maintenance of the pyrometric equipment, for the calibration of the instruments, and for the solution of any temperature problems that arise. In approaching this subject two questions present themselves: What should be the character of the instruction in pyrometry in an engineering school, and what can be expected of the students who have had this instruction? In brief, it may be said that the aims of a course in pyrometry should be to give: (1) A thorough grounding in the fundamental principles of thermoelectric, resistance, radiation, and optical pyrometry, and of liquid and gas thermometry; (2) practical instruction in the calibration of pyrometers; (3) acquaintance with the errors that are likely to arise and the precautions that must be observed in practice; (4) information regarding the limitations of the various classes of instruments, their relative reliability, and the accuracy attainable with them at different temperatures; (5) acquaintance with the commercial instruments on the market, their construction and relative merits; (6) a knowledge of the chief sources of information relating to the measurement of high and low temperatures. To sum up, the aim should be to turn out resourceful young men familiar with the leading instruments on the

Jan 9, 1919