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By George S. Rice

GROUND movement from mining, whether it be for coal, metal, industrial minerals, or .oil, will always present many difficult problems. These are especially serious when valuable surface improvements may be badly damaged. The mine itself, if mining methods are not suitable to the formation, is subject to heavy falls of the main roof in the working places; and with certain structural conditions the movements may cause in coal mines disastrous bumps and outbursts of gas, and in deep metal mines rock bursts. In open-cut work rock and earth slides may result. Absolute prevention of ground movement from mining is impossible unless large pillars are left unmined,

Jan 1, 1937

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 AIME AIME

AN unusual interest in the question of orienting the young college man in the mineral industry was shown in a well-attended session* of the Engineering Education Committee on Monday afternoon. About seventy-five employers and educators of mining engineers were present and took part in the discussions.

Jan 1, 1929

By J. R. Linney

THE Eastern magnetite industry has not failed in its contribution to the war program during the past year. Man-power shortage was the critical problem in maintaining production and for the last half of the year, owing to lack of man power, it was necessary for some mines to change from seven to six days per week schedule. At Cornwall, Pa., the mine operated by the Bethlehem Steel Co. produced approximately 2,000,000 tons of crude ore and 1,200,000 tons of iron ore concentrates, a decrease of about 10 per-cent compared with the previous year. Railroad haulage in the open-pit at this mine was discontinued, being replaced by Mack trucks of approximately 30 tons' capacity. At the Mt. Hope mine in New Jersey, the Warren Foundry and Pipe Corp. produced about 195,000 long tons of crude ore obtaining 70.000 long tons of lump ore and 35,800 long tons of concentrates. An additional 24,500 long tons of concentrates was produced from a stock pile of 47.000 long tons of crude ore accumulated during the latter half of 1943, following the fire in their old dry mill. All of this material was handled through their Brown

Jan 1, 1945

By E. C. Houston

The phosphate ores mined in middle Tennessee typically consist of granular rock phosphate particles disseminated in a clayey matrix. In the TVA plant near Columbia, Tenn., the phosphate ore is mined, made into a slurry with the addition of a small amount of sodium hydroxide as dispersant, and treated in a hydroseparator to remove minus 10 micron material. The hydro-separator underflow, comprising a rough concentrate, is transported by pipeline to the plant; the hydro-separator overflow, comprising a tailing, is flocculated by addition of calcium sulphate and is discharged to settling ponds at a rate of about 1400 gpm. Sedimentation in the ponds produces a clarified effluent, which may be recycled for use as process water or discharged to surface drainage. This method of tailing treatment is not entirely satisfactory since poor sedimentation characteristics of the tailing result in poor ultimate utilization of pond storage volume.

Jan 1, 1949

By D. Harrington

ALTHOUGH statistical data are not at hand to justify definite statements as to progress in health, and safety in the mining and allied industries during 1935, it now appears probable that in both coal mining and in metal- mining the rate of accident occurrence as well as the absolute number of accidents will show slight increases for the year. Much: of the responsibility for this increase lies with the large number of relatively. small mines that have more or less recently come into existence, partly because of 'the lack of opportunity for work in the larger mines for large numbers of unemployed miners, and partly due to increased prices for some of the mineral products, especially gold. In general, the larger long-established nines show downward accident trends and this is decidedly encouraging as it shows that where mines are operated with real efficiency, mining can be done in relative safety.

Jan 1, 1936

By AIME AIME

THE sixteenth annual meeting of the Woman's Aux¬iliary, A. I. M. E., was held Tuesday morning, Feb. 16, at the Engineering Societies Building. The meeting was well attended, there being 99 registered from the metropolitan area and 78 from the sections throughout the United States. Mrs. Sharpless, the secretary, read the minutes of the annual meeting held a year ago, after which Mrs. Bassett, the president, gave her address of welcome. Mrs. Bassett said in part: "I would like, at this time, to welcome you all to this, our sixteenth annual meeting, and to express my appreciation to all the national officers and members of the board of directors for their loyal support and for the excellent work done by the chairmen of sections and their members. It is with much pleasure that I look back upon my visits with the sections in Washington, Arizona, Northern and Southern California, Chicago, Colorado, Western Pennsylvania and Utah before I assumed the office of president. During the last year I have much enjoyed meeting with the sections in Boston, Washington and New York. It is our duty to see that the achievement for 1932 be equal to that of the year that has just passed."

Jan 1, 1932

By AIME AIME

LAST month we published (p. 440) the first half of the L discussion by O. E. Kiessling of the paper on copper by Mr. Vogelstein that appeared in the same-issue, but lack of space made it necessary to hold the remainder for this number. Mr. Kiessling now asks to have the last " sentence of the part already published revised to the form given in the first sentence which follows, and also asks that the two parts, though necessarily published separately, be read together, as a mistaken impression may be derived from the first Dart unless it is read in connection with the statement of the Bureau of Mines policy respecting secondary metals which is here published. .

Jan 1, 1931

By Scott Turner

AS IN OTHER lines of engineering, progress in mining was influenced during 1931 by the world-wide economic depression. Low-metal prices ? resulted in active efforts to reduce production costs of base-metal mines. Probably the chief factors in reducing costs were the greater efficiency of labor, due to better relations between management and workmen, to the scarcity of jobs, reduced wages in most base-metal mines, and to lower overhead expenses secured by drastic economies. The use of mechanical equipment continued to increase, due to more efficient designs and a better practical understanding of the applicability of such equipment to requirements. With one exception, there were no startling innovations in stoping methods, but there was notable progress in the better adaptation of mining methods. In the United States, no large new base-metal or silver mines came into production during the year. At a number of mines, output was curtailed, and operations were discontinued at several important producers. On the other hand world-wide interest in gold was stimulated, as evidenced by increased output from producing mines, the reopening of some old properties, and intensive prospecting for new deposits. Mining methods at several gold mines in the United States and Canada were modified or changed to obtain a higher extraction of ore or to meet the need for additional support of the mine workings at depth. Permanent record of improvements in mining practices has been made during the year by the Federal Government; the industry thus has available for its use more detailed information than ever before. This work was done through cooperation of the mining companies and their representatives with the United States Bureau of Mines, whereby many papers descriptive of practices and costs at individual mines have been published. The Bureau's program of describing methods and costs at the more important mines (those producing in excess of $100,000 annually) is nearly completed, but papers will be issued concerning such additional mines as may possess particular interest because of novel methods, exceptional conditions or operating results, and others to supplement reports already issued. In this way, an interesting record of the results of changing conditions, or innovations in methods, will be made available.

Jan 1, 1932

By W. L. Zeigler

DURING the middle 1880s, shortly after the discovery of silver-lead ores in the Coeur d'Alene district of northern Idaho, it became apparent that concentration of the ores would be necessary to obtain a profitable product. Too much siliceous material was present for direct smelting, and the majority of the ores found at depth were too low in metallic content for economic smelting processes at the time. As the ores occurred in quartzite shear zones with siderite and quartz gangue, a large quantity of waste material was present in all the mines. As the galena was not finely disseminated, this made possible relatively good extraction of the argentiferous galena by coarse concentration. The first concentrators consisted mainly of coarse crushing, screening and jigging, principally by Harz jigs, the slimes being treated on buddies. Later Wilfley tables took the place of sand jigs and vanners superseded the buddies. Because of the marketing conditions, no attempt was made until 1900 to effect a recovery on the zinc minerals present, which were found associated in varying amounts with the galena. All through this period, the greater part of the production was obtained from mines containing ore assaying high in lead and low in zinc. Parts of some ore bodies would be reversed in this respect, so that ores high in zinc were left intact. During the decade after 1910, several important mines, The Success and The Interstate Callahan, containing ores high in zinc, were put into operation and were a material aid in the needed zinc production during World War I. Gravity concentration by jigs and tables was used during this period, with bulk flotation increasing in popularity for the treatment of the fine material that had already been treated by ordinary slime concentrating machinery. No extra fine grinding for flotation concentration was thought profitable at the time. TAILINGS DISCHARGED INTO STREAMS From the start of mining and milling operations in this district until 1904, no attempt was made by the various mills in the upper district to impound or stack their tailings. They discharged them directly into the adjacent creeks or streams, to be carried away by high water. The Bunker Hill and Sullivan and the Last Chance mines, both in the relatively flat valley of the district, stacked huge piles of the coarse jig tailings on the near-by river bottom. Rain and snowfall are heavy in the Coeur d'Alene district, as it is on the heavily timbered Pacific slope of the Bitter Root Mountains. A heavy runoff occurs every spring and there is an occasional flood of disastrous proportions when warm "Chinook" winds accompanied by rain

Jan 1, 1947

By Thomas Leonard Watson

SULPHIDE ore-bodies of more or less lenticular shape occurring in metamorphic crystalline schists, gneisses, and. slates, and conforming closely in strike and usually in dip to the inclosing rock, have been recognized and described along the, Atlantic seaboard from Quebec to Alabama. The ore-bodies do not entirely conform, in all cases, to the structure of the inclosing schists, but they sometimes cut across the foliation in dip, though conforming more closely with the direction of strike. In composition the principal sulphide mineral is usually pyrite or pyrrhotite; or both, accompanied by copper, frequently gold, and almost always some sphalerite and galenite. Other. metallic ores are, so far as these sulphide bodies have been investigated, less common; silver is not uncommon, and in some of the pyrrhotite masses nickel is present in quantity sufficient to be commercially valuable. Cobalt frequently accompanies .the nickel, usually in smaller amount, and the two vary much in relative proportion. Quartz and calcite are probably the most common of the, non-metallic minerals. A number of silicate minerals are frequent representatives in one place or another; garnet, amphibole, biotite, pyroxene, zoisite and others. The sulphide bodies of Virginia, comprising both pyrite and pyrrhotite, are among the most extensive along the Atlantic seaboard. Among the pyrite bodies may be mentioned the well-known and extensively worked mines of Louisa and Prince William, counties, located on' the main pyrite belt (A, Fig. 1) of the middle and northern, eastern Piedmont region in Virginia, and among the pyrrhotite bodies is the famous " Great Gossan Lead "(B, Fig. 1) of the Floyd-Carroll-Graysou coun-

Sep 1, 1907

By D. M. McFarland

IN mining, quarrying, and construction, drilling and blasting have an important influence on the operations that follow. If the fragmentation of material being disrupted is inadequate, loading and transportation equipment will not operate at or near full capacity. Any operator faced with this difficulty should not be satisfied until he is convinced by a careful study of his methods of drilling and blasting that no improvement can be made. Rock in a certain quarry in Ohio seemed to defy any grade of explosive or means of detonation that the explosives industry had to offer. The average result of a blast was that a great part of the burden would be pushed out from the face in a number of large sections that would jokingly be referred to as "boxcars." These were no credit to the explosives man and a costly problem for the quarry company. Such blocks retard shovel operation as they have to be uncovered and subjected to secondary drilling and blasting which, if extensive, is an expensive operation. It was an attempt to improve the fragmentation obtained in primary blasts that led to the development of milli-second-delay electric blasting caps. The reasoning that prompted the trial was that even with wide spacing of the drill holes it seemed that the burden was separated too quickly from the face by the cutting action of the explosives from hole to hole. If the time of firing of the holes could be regulated so that

Jan 1, 1948

By H. C. Weed

THE Inspiration Consolidated Copper Co., located in the Globe-Miami district at Inspiration, Ariz., became a producer of copper in 1915. From 1915 until 1948, 116,278,000 tons of ore were produced from underground workings by the block-caving system of mining. In April 1948, open-pit ore production from portions of the ore body was started and earlier plans for block-caving in these areas were abandoned. The change was due to economic conditions.

Jan 8, 1950

By Daniel R. Shawe

Large tabular beryllium deposits in waterlaid rhyolitic tuff at Spor Mountain, Utah, contain the world's largest known resources of beryllium (as bertrandite). The district also has produced fluorspar and uranium. The largest beryllium deposit is about 2.5 miles long, and known deposits contain many million tons of material with at least 0.5 per cent BeO. The beryllium-bearing tuff (Pliocene?) underlies topaz-bearing rhyolite ( Pliocene?) that contains unusually high amounts of beryllium, fluorine, and uranium, and overlies other volcanic rocks (Pliocene? or Micocene?) and marine carbonate and elastic rocks ( Paleozoic). The deposits occur in hydrothermally altered tuff only where it contains abundant carbonate pebbles eroded from the Paleozoic rocks and where the tuff was deposited as thick layers in now-buried paleovalleys. Basin and Range faults, thrust fa ults, and possibly strike-slip faults formed in this part of the Basin and Range province during the late Tertiary, and volcanic rocks were extruded. Beryllium mineralization probably occurred during this episode. Undoubtedly the beryllium deposits are related genetically to the topaz-bearing rhyolite, but the details of their genesis are not certain and probably are complex. Beryllium deposits are close to major faults, and locally the beryllium is concentrated at faults, indicating fault control of mineralization. Some elements in the deposits, such as lithium, however, are evenly distributed in certain Luff beds and perhaps were introduced prior to faulting. Still other elements, such as manganese and lead, were concentrated in the beryllium deposits and subsequently were leached along late fractures, indicating a period of metal redistribution following mineralization.

Jan 1, 1968

By W. J. Babyak

The habit planes for hydride precipitation in large grains of alpha zirconium and Zircaloy-4 were determined in specimens containing 161 and 136 ppm hydrogen, respectively. In zirconium, the hydride platelets precipitated on various pyramidal planes inclined to the basal plane at angles ranging from 10 to 50 deg and 75 to 90 deg. Hydrides were most frequent at inclinations of about 20 deg and 90 deg. In Zircaloy-4, hydride plates were inclined to the basal plane at angles vanging from 5 to 25 deg with the predominant inclinatioiz equal to 12 deg; no platelets were found near the prism plane position. In both zircoinium and Zir-caloy-4, hydrides were principally, but not exclusively, parallel to (1011) type planes. When the Zircaloy-4 gmins were subjected to tension stresses of 12,100 psi and 19,400 psi during hydride precipitation, the hydride habit was unchanged except that precipitation favored those habit planes which were inore nearly perpendicular to the stress direction. The stress-orientatioiz effect increased with the magnitude of the stress. THE hydride habit plane in a zirconium has been determined by several investigators. Langeron and Lehr1 in 1956 found platelets parallel to (1010) slip planes. In 1962, Westlake and Fisher2 confirmed these findings and showed that hydride precipitation on twin planes, as reported by Kunz and Bibb,3 was probably due to incomplete removal of worked metal from specimen surfaces. Secondary habit planes, ( 1011) and (1015), were also found by Westlake and Fisher under particular charging conditions where a hydride layer may have existed at the hydrogenation temperature. Most recently, walters4 and westlake5 again observed the (1010) habit exclusively in zirconium. Louthan and hgermans have reported that hydrides precipitate on various ( 101l ) and (112l) planes positioned 31.5 to 90 deg to the basal plane in Zircaloy-2. The present investigation was concerned with the hydride habit in Zircaloy-4 in relation to that in zirconium and the possible change in habit when precipitation occurs under stress. The latter consideration was prompted by the stress-orientation phenomenon originally reported by Marshall and Louthan.7, 8 I) EXPERIMENTAL Materials and Specimens. Chemical analyses of all materials are given in Table I. The zirconium specimen was a 1 by 4 in. section cut from wrought crystal bar that was hot-rolled at 790°C to 0.300 in. and cold-rolled to a final thickness of 0.095 in. All surfaces were mechanically polished and then chemically polished with a solution of H2O, HNO3, and HF (10:10:l by volume) prior to annealing. Grains as long as 0.25 in. were grown by thermally cycling the specimen three times (in 10-5 mm Hg vacuum) between 825" and 1000°C at approximately 125°C per hr. The specimen was isothermally annealed at 825°C for 24, 40, and 120 hr after each cy-

Jan 1, 1968

By P. Rama Rao, D. H. Sastry, T. R. Anantharaman

Deformation (a) and twin (a') stacking-fault densities in cold - wor ked filings of fcc silver alloys containing 2, 4, and 6 wt pct Sb have been estimated from Debye-Scherrer peak shifts and asymmetries, respectively. Evidence has been obtained for a possible strain-induced transformation in a two-phase alloy containing 9.0 zut pct Sb. Using Fourier analysis of X-ray line profiles, the effective particle sizes and root mean square strains have been determined for the three fcc alloys in the cold-worked condition. The values of the compound fault probability 0.5a + a') evaluated from peak shifts and asymmetries are in reasonable apeement with those derived from peak broadening. COLD work of fcc metals may produce both deformation and twin (also called growth) stacking faults, which can be detected and quantitatively estimated by X-ray diffraction techniques.' In addition to peak broadening, deformation faults produce a shift in peak positions and twin faults an asymmetry of the Debye-Scherrer reflections. Besides stacking faults, a reduction in the size of coherently diffracting domains and distortion within these also broaden the powder reflections of deformed fcc metals and alloys. Fourier analysis' of peak shapes provides quantitative infor- mation about the effective domain sizes, lattice strains, and also the compound fault probability (1.5a + a'), where a and a' represent deformation-and growth-fault density, respectively. The Paterson method2 for determination of a from peak shifts, the warren3 or wagner4 method for evaluation of a' from peak asymmetries, and the Fourier analysis for quantitative estimates of all the contributory causes of peak broadening have, in the course of the last decade, been extensively applied to obtain data for a number of deformed fcc metals and alloys. One of the useful results of earlier measurements of a in several solid solutions is a correlation between a and the solute valence as well as electron concentration per atom (p) in alloy systems based on a particular solvent. The work of Smallman and westmacott5 on Cu-Zn, Cu-A1, and Cu-Sn, of Foley, Cahn, and ~aynor' on Cu-Si and Cu-Ge, and of Rama Rao and Anantharaman7 on Cu-Si and Cu-Sb has revealed a common trend in the increase of a with p and also a with valency of the solute. Cahn and Davies' and Ad-ler and wagnerg have observed similar trends for silver alloys containing cadmium, indium, and tin. Data on a for silver alloys with a pentavalent solute element are not, however, available. It is primarily to fill this need that the present investigation on Ag-Sb alloys was undertaken. Utilizing the Patersonand Warren methods, values of a and a', respectively, have been determined in three silver alloys containing 2, 4, and 6 wt pct Sb. By Fourier analysis of the broadening of Debye-Scherrer peaks, effective particle sizes, lattice strains, and the compound fault probability (1.5a +a') have also been evaluated.

Jan 1, 1967

By H. R. Peiffer

The increase in electrical resistivity, ?pT,at 78°K was measured as a function of elongation, E, at 78°K for a 2 pct (approximately) by weight finely divided alumina in silver material. The amount of increase in electrical resistivity (?pT) is a function of the amount of alumina present and can be represented by: ?pT = cen where c and n are constants. The constant c increases and the exponent n decreases with increasing alumina content. Approximately 33 pct of the resistivity increase is recovered upon annealing at room temperature. RECENTLY, dispersed phase alloys' have shown promise for use at elevated temperatures. These materials have a high creep resistance, a high-temperature strength considerably above that of the pure matrix, and a high electrical conductivity. These materials also show other properties such as retardation of re crystallization and resistance to flow even above the melting point of the matrix.' It is believed that high-temperature creep is retarded in these materials because the dispersed phase blocks the motion of dislocations. According to schoeck3 and also Weertman,4 the rate controlling process is the climb of dislocations around the dispersed phase particles. Any mechanical property of these materials, or any other material for that matter, can be explained on the basis of defect structures and their interrelations. It would certainly be interesting to learn something about the effect of a dispersed phase on dislocation densities and also their effect on point defect concentrations following cold work. This is the purpose of the research discussed herein. The method used was the measurement of the electrical resistivity as a function of elongation at low temperatures. This scheme has already been applied to the studies of pure metals.5 Electrical resistivity measurements conducted on pure metals such as copper, silver, gold, and so forth, have indicated that defects such as vacancies and dislocations are formed during deformation.5 It has been shown by van Bueren6 that the resistivity change, ?p, should increase with elongation, E, according to the following relation: Ap=Al/2 + B£3/2 where A and B are constants of the system; ?p is in µ? cm. The first term refers to the amount of resistivity change associated with line defects and the second term with the change associated with point defects. A later calculation yielded exponents of 3/4 and 5/4, respectively.6 Manintveld7 has shown that the resistivity of copper increases with strain according to a 3/2 power law, whereas van Bueren has shown that the resistivity of silver increases according to a 5/4 power law. Assuming then that van Bueren's calculations are correct, it appears that line defects contribute very little to the electrical resistivity. There is some doubt, however, as to the validity of van Bueren's expressions for all cubic metals.' In fact, the data on copper and silver are not conclusive. In this in-

Jan 1, 1962

By Fred W. Stiefel

THIS paper covers the operation and maintenance of Diesel locomotives underground on a portion of the Delaware River Aqueduct.[t] This part of the tunnel is 15 miles long, with shafts 14 ft. in diameter spaced about 5 miles apart. These shafts (2, 2a and 3) are 825 ft., 1551 and 840 ft. deep, respectively. The grade of the tunnel is almost level, except for the 12,100 ft. north of shaft 2, which has a grade of 2.31 per cent. The tunnel is circular, 17 to 19 ft. in diameter. It lies at a depth of 400 ft. below sea level, with a maximum over-burden of 2400 feet. The tunnel driving was carried on in six headings, using 15 storage-battery locomotives, each of 13 gross tons and having a maximum speed of 8 miles per hour. The longest haul was 3 miles, which proved to be the maximum distance for which storage-battery locomotives could be employed economically for the amount of material to be moved. One locomotive was used for switching cars at each heading, one for switching cars at the bottom of each shaft and one on the main-line haul from the heading to the shaft. The maximum amount of material hoisted in one shaft from two headings when 104 ft. of tunnel was driven in 24 hr. was 1000 cu. yd., or about 2000 tons of rock in place. The total quantity excavated was 750,000 cu. yd. (1,500,000 tons of rock). The tunnel-lining operations using concrete presented a problem of hauling a maximum distance of 5 miles in the tunnel. The concrete-placing equipment had a capacity of about 2000 cu. yd., or 4000 tons in 24 hours. Experience had shown that storage-battery equipment could not handle this quantity of material within the time required at the distance of 5 miles. Trolley-locomotive haulage was considered dangerous and expensive, and would cause interference because transmission equipment would be required. Therefore the performance of Diesel locomotives of 160 hp., with a speed of 18 miles per hour, in comparison with that of other types of locomotives, was studied. CHOICE OF LOCOMOTIVES In deciding upon the type of locomotive to be used for the 5-mile haul, four alternatives were considered, as follows: I. To purchase additional storage-battery locomotives with the necessary batteries over the 6 locomotives and 12 batteries available. 2. To convert the existing battery locomotives to the trolley type. 3. To purchase new trolley locomotives. 4. To purchase Diesel locomotives. PROPOSITION No. I The 90-hp. storage-battery locomotives available (each weighing about 12 tons), when hauling a load of 64 tons, with a drawbar pull of about 1900 lb. on a level track, developed a speed of 8 miles per hour and could make five round trips in 8 hr. with a

Jan 1, 1942

By Fred W. Stiefel

This paper covers the operation and maintenance of Diesel locomotives underground on a portion of the Delaware River Aqueduct. † This part of the tunnel is 15 miles long, with shafts 14 ft. in diameter spaced about 5 miles apart. These shafts (2, 2a and 3) are 825 ft., 1551 and 840 ft. deep, respectively. The grade of the tunnel is almost level, except for the 12,100 ft. north of shaft 2, which has a grade of 2.31 per cent. The tunnel is circular, 17 to 19 ft. in diameter. It lies at a depth of 400 ft. below sea level, with a maximum overburden of 2400 feet. The tunnel driving was carried on in six headings, using 15 storage-battery locomotives, each of 13 gross tons and having a maximum speed of 8 miles per hour. The longest haul was 3 miles, which proved to be the maximum distance for which storage-battery locomotives could be employed economically for the amount of material to be moved. One locomotive was used for switching cars at each heading, one for switching cars at the bottom of each shaft and one on the main-line haul from the heading to the shaft. The maximum amount of material hoisted in one shaft from two headings when 104 ft. of tunnel was driven in 24 hr. was 1000 cu. yd., or about 2000 tons of rock in place. The total quantity excavated was 750,000 cu. yd. (1,500,000 tons of rock). The tunnel-lining operations using concrete presented a problem of hading a maximum distance of 5 miles in the tunnel. The concrete-placing equipment had a capacity of about 2000 CU. yd., or 4000 tons in 24 hours. Experience had shown that storage-battery equipment could not handle this quantity of material within the time required at the distance of 5 miles. Trolley-locomotive haulage was considered dangerous and expensive, and would cause interference because transmission equipment would be required. Therefore the performance of Diesel locomotives of 160 hp., with a speed of 18 miles per hour, in comparison with that of other types of locomotives, was studied. Choice of Locomotives In deciding upon the type of locomotive to be used for the 5-mile haul, four alternatives were considered, as follows: I. To purchase additional storage-battery locomotives with the necessary batteries over the 6 locomotives and 12 batteries available. 2. To convert the existing battery locomotives to the trolley type. 3. To purchase new trolley locomotives. 4. To purchase Diesel locomotives. Proposition No. i The 90-hp. storage-battery locomotives the (each weighing about 12 tons), when hauling a load of 64 tons, with a drawbar pull of about 1900 lb. on a level track, developed a speed of 8 miles per hour and could make five round trips in 8 hr. with a

Jan 1, 1943

By Fred W. Stiefel

This paper covers the operation and maintenance of Diesel locomotives underground on a portion of the Delaware River Aqueduct. † This part of the tunnel is 15 miles long, with shafts 14 ft. in diameter spaced about 5 miles apart. These shafts (2, 2a and 3) are 825 ft., 1551 and 840 ft. deep, respectively. The grade of the tunnel is almost level, except for the 12,100 ft. north of shaft 2, which has a grade of 2.31 per cent. The tunnel is circular, 17 to 19 ft. in diameter. It lies at a depth of 400 ft. below sea level, with a maximum overburden of 2400 feet. The tunnel driving was carried on in six headings, using 15 storage-battery locomotives, each of 13 gross tons and having a maximum speed of 8 miles per hour. The longest haul was 3 miles, which proved to be the maximum distance for which storage-battery locomotives could be employed economically for the amount of material to be moved. One locomotive was used for switching cars at each heading, one for switching cars at the bottom of each shaft and one on the main-line haul from the heading to the shaft. The maximum amount of material hoisted in one shaft from two headings when 104 ft. of tunnel was driven in 24 hr. was 1000 cu. yd., or about 2000 tons of rock in place. The total quantity excavated was 750,000 cu. yd. (1,500,000 tons of rock). The tunnel-lining operations using concrete presented a problem of hading a maximum distance of 5 miles in the tunnel. The concrete-placing equipment had a capacity of about 2000 CU. yd., or 4000 tons in 24 hours. Experience had shown that storage-battery equipment could not handle this quantity of material within the time required at the distance of 5 miles. Trolley-locomotive haulage was considered dangerous and expensive, and would cause interference because transmission equipment would be required. Therefore the performance of Diesel locomotives of 160 hp., with a speed of 18 miles per hour, in comparison with that of other types of locomotives, was studied. Choice of Locomotives In deciding upon the type of locomotive to be used for the 5-mile haul, four alternatives were considered, as follows: I. To purchase additional storage-battery locomotives with the necessary batteries over the 6 locomotives and 12 batteries available. 2. To convert the existing battery locomotives to the trolley type. 3. To purchase new trolley locomotives. 4. To purchase Diesel locomotives. Proposition No. i The 90-hp. storage-battery locomotives the (each weighing about 12 tons), when hauling a load of 64 tons, with a drawbar pull of about 1900 lb. on a level track, developed a speed of 8 miles per hour and could make five round trips in 8 hr. with a

Jan 1, 1943