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By F. L. Grammer

The analyses given in Table I. were made several years ago at my request at a plant using Lake ores. They are of two furnaces, one making basic, the other Bessemer pig— they gave 6 casts each in 24 hr., also two flushes of cinder between each cast. They are offered simply for the sake of reference as, so far as I know, it is unusual to find so frequent full analyses made and none are on record. The variations in manganese-content in the first and second flushes on the basic furnace are interesting, if no more than a freak—the first flush being invariably higher in manganese. The iron-content of the two slags from an average of 12 flushes shows: Basic. Bessemer. Per Cent. Per Cent. Total iron...................................... 2.85 1.70 Combined iron................................ 0.72 0.52 Free iron....................................... 2.13 1.18 The greater iron-loss in the basic slag, while known, has never heretofore been so clearly set forth. This may modify the arrangement for handling slag; heretofore usually determined by proximity of the dumping-heap. If a nearby heap is used on contiguous territory, in the past, tilting molten-slag pots were used. If the Pittsburg flood-records for 30 years are a fair criterion the government regulations were inadequate, and molten slag was dumped in such a manner as to throttle the Monongahela at the time of the spring thaws. At Pittsburg the slag, where it is carried to a distance, is frequently granulated in pits and then removed in cars to which it is conveyed by clam-shell buckets. This practice is also quite customary where the slag is intended for the manufacture of slag cement. The production of 500 tons of cast-iron daily means about 300 tons of- slag and at 2.113 per cent. equals 6.4 tons

Jan 1, 1914

By James Douglas

I had the good fortune to visit the Stockholm Exposition just before its close in October last, and to get a glimpse of the methods used in Sweden in making the wonderful steel and iron for which its furnaces are so famous. My time and opportunities for observation were limited, but some points which I noted may be worth bringing to the notice of the Institute. The Exposition itself was confined to the natural and artificial products of Scanclinavia, and therefore iron and steel held a very prominent place in it. There was a complete collection of the rocks and ores of the Peninsula made by the Geological Survey; and every iron-mine of note exhibited a glass model of its workings, as well as classified specimens, accompaniecl by thorough analyses of the ores. Another feature of interest was the display of models of the old mining-machinery, in the invention and introduction of which Sweden led the way, and of the old and new surveying-instruments and compasses devised for the exploration of the Swedish iron-ore bodies, all of which are more or less magnetic. The magnetometric collection and exhibit of methods of operation made by Prof. Nordestrijm were supremely instructive. The larger metallurgical works, such as those of the Kopparberg and Sandvik companies, exhibited their wares in separate pavilions, in which crude and manufactured objects were arranged most eflectively and tastefully; while the smaller companies erected in the Industrial Arts Building trophies, every one of which was an object of beauty. One was struck on all sides by the fine asthetic feeling exhibited in the ingenious installation of materials and objects not easily lending themselves to artistic treatment. Hammers, picks and drill-steel were grouped into mural designs which it was a delight to look at.

Jan 1, 1899

By Andrew Torok, Thomas D. Thompson

Research efforts have not developed techniques for the complete desulfurization of coal that is needed to reduce air pollution caused by burning coal and to reduce the sulfur in metallurgical coke. Sulfur in coal occurs in three forms and of these, the pyritic sulfur occurs as discrete mineral particles and, at least theoretically, should be subject to physical rejection. Pyrite occurring in hard rock mining is concentrated by froth flotation; therefore, the possibility of removal of pyrite from coal by flotation does exist. With this possibility in mind, the flotation and adsorption characteristics of ore and coal-pyrite were compared while using potassium ethyl xanthate as the collector.

Jan 1, 1973

PAUL D. FOOTE AND T. R. HARRISON, Washington, D. C. (written discussion *).-There are several methods for measuring the internal resistance of a battery, the line resistance in a circuit containing an e.m.f., or the true value of this e.m.f. The writers, however, were the first to em-ploy a simple principle whereby the total resistance of the circuit is ad-justed to a preassigned value for which the scale of the millivoltmeter is graduated, the only e.m.f. employed being that of the source measured. One of the simplest forms of these instruments is described on page 2842, September Bulletin. In papers now in the press we have described some twenty modifications of this simple design but all operating upon the same fundamentally new principle. The instrument devised by Mr. . Porter is of this general type but, unlike the designs we have recom-mended, is open to serious objections.

Jan 12, 1919

By T. S. Lundy, J. Askill

J. Askill and T. S. Lundy (Oak Ridge National Laboratory)—Moore has proposed a simple correlation between the activation energy for solute diffusion in fee metals and the atomic volume of the diffusing species using both tracer and chemical-diffusion data. The first point we wish to make is that it is wrong to attempt such correlations without separating the two types of data. Activation energies obtained using tracer techniques cannot, in general, be directly compared with those obtained from chemical-diffusion experiments. A knowledge of the variations of chemical potentials with composition is necessary and chemical-diffusion data must be corrected for such variations, even for dilute alloys, before a comparison is possible. Secondly, for nickel, iron, aluminum, and lead, Moore neglected a number of recently published works, e.g., Al26 and Mn54 in aluminum,46 cr51 in nickel,47 and Fe55 in iron.48 These and others should have been used. If one considers only the tracer diffusion data, there is left no simple correlation of the type proposed by Moore. For example, in the case of solute diffusion in aluminum the only reliable tracer data listed by Moore are for zinc and aluminum. The nickel, cobalt, and iron data of Agarwala49 are representative of near-surface diffusion-not bulk diffusion. In conclusion we suggest that for tracer diffusion data in these fee metals there is no justification for proposing any simple correlation of activation energy with atomic volume using the limited data that are presently available. R. H. Moore (author's reply)—The writer has proposed a simple correlation which is useful in estimating the internal consistency of diffusion data. The accuracy of the correlation is, of course, a function of the number of data available. Lundy and Askill take issue with the writer's decision to include data for the systems: nickel, iron, aluminum, and lead, taking the view that the data are insufficient to establish the correlation. The writer agrees that the data are insufficient and has cau- tioned the reader that the correlation is tentative in these instances. Inclusion of these systems is justified by the interesting trends the correlation reveals. For example, the distinction between interstitial and substitutional diffusion may be clearly established, Figs. 4 and 6, and the behavior of transition elements and nontransition elements is indicated to parallel the behavior illustrated by the silver and copper systems. Lundy and Askill have singled out the aluminum system for special criticism. The writer chose to discuss the data for diffusion of iron, nickel, and cobalt in aluminum in the terms used by the original authors9 and has included the comments of Balluffi.l0 The writer did not intend the reader to conclude that data for these elements should correlate with data for the nontransition elements as Lundy and Askill have evidently assumed. Iron, nickel, and cobalt form intermetallic compounds with aluminum, so the activity coefficients of these elements may be expected to deviate markedly from unity. This may account for the low frequency factors observed by Hirano.9 The nontransition elements, on the other hand, yield relatively simple phase diagrams with no evidence for intermetallic compound formation as in the case of iron, nickel, and cobalt. In dilute solution, Henry's law should be closely obeyed, the activity coefficients should not deviate markedly from unity, and the effect on the activation energy should not be large. The accuracy of the correlation applied to these systems will improve as the data is extended. It does not seem unreasonable to conclude that its extension should be encouraged.

Jan 1, 1965

The following advertisements show the contemporary view of the value of coal on a tract, usually as compared with farming advantages of several kinds. Fayette Gazette and Union Advertiser, February 10, 1798: "For Sale in Washington twp., Fayette Co., 211 acres of land whereon is a good new grist merchant mill, a good stone dam, and a house for the miller, about two acres of bottom, cleared and fenced, an excellent coal bank and saw-mill seat unimproved." Pittsburgh Gazette, March 19 and 26, 1802: Ads. offering for sale two properties, one of 38 acres, "together with a Coal Pitt and Lime Quarry, lying on the Monongahela side of Grant's Hill, and within one mile and a half of Pittsburgh," and the other two tracts of 700 acres on "Racoon creek, contiguous to which is a valuable limestone quarry, and a quarry of building stone, also plenty of stone coal." Pittsburgh Gazette, Oct. 8, 1802: A farm between Pittsburgh and Greensburg "with house, barn and a Smith shop-also, a fine sugar camp, and a Coal Bank within sight of the house," was offered for sale. The Farmers Register, Greensburg, Pa., March 13, 1802: An advertisement of a "plantation, six miles from Greensburg, there are two coal banks on it, one at each end of the place." The Commonwealth, Pittsburgh, Aug. 4,1805: A number of lots were laid off on Saw Mill Run, nearly opposite the first opening made on the Pittsburgh seam. They were from two to twenty acres each "and a great quantity of Limestone and stone coal." Pittsburgh Gazette, Aug. 9, Sept. 6, Sept. 27, Oct. 4, 1811; The Commonwealth, Aug. 19, 1811: Five tracts were advertised that contained coal. One had "fine springs and an inexhaustible mine of coal;" one, "excellent sugar camps, coal banks and limestone and a good mill seat;" one, "good sugar camps, an excellent coal bank and an elegant seat for a distillery;" another, a tract of 45,000 acres in Allegheny and Butler Counties affording "stone coal and iron ore, and seats for water works;" and the last a tract on Beck's Run, four miles from Pittsburgh "and a coal pit opened about one fourth of a mile from the river." The Mercury, Pittsburgh, April 8, Jan. 14, Feb. 11, 1813; Pittsburgh Gazette, April 16, Dec. 3, 1813: These tracts were advertised during the year in the vicinity of the city. One had "a good sugar camp, woodland and plenty of coal;" another, "a sugar camp and a coal bank on the premises;" while the others were "well timbered or well watered and had excellent stone coal." The Mercury, Pittsburgh, Feb. 2, 1814: A farm was offered for sale on the headwaters of Robinson's Run, in Washington County, four miles from Burgettstown, containing 60 acres, "a young bearing orchard,... a coal bank and a good sugar camp." Genius of Liberty and Fayette Advertiser, Uniontown, Pa., March 2, 1814, carried an advertisement of a sale of lots in the new town of Perriopolis; "the quantity and quality of the clay, sand and salt licks, near the premises, together with the timber and abundance of .stone coals The town of Perriopolis was situated upon a . farm at one time belonging to Washington.

Jan 1, 1942

By J. D. Forrester, Erich Sarapuu, T. C. Cheasley

RANKING high in the nation's wealth of natural resources, readily available liquid and gaseous hydrocarbons are nevertheless falling steadily in supply, while industrial requirements for hydro- carbon compounds are greater today than during the peak period of World War II. Theoretically, several processes will increase the future supply of liquid and gaseous fuels, but the practical application of these methods depends on two controlling factors: 1-that enough carbon- bearing material be available to warrant industrial exploitation, and 2-that the given process be physically, chemically, and economically applicable. With regard to the first factor, the Western Hemisphere is fortunately well supplied, see Table I.

Jan 9, 1954

By M. D. Curran

AS applied to coal, the term processing is subject to many interpretations. To some it means preparation of coal for the market by mechanical means such as crushing, sizing, washing, or treating with oil or chemicals to eliminate dust or improve combustion quality. To others it means conversion of the coal to other commodities as in carbonization to produce coke and by- products, or to liquids by application of the hydrogenation process. I prefer to classify the various forms of mechanical treatment under the heading of beneficiation and apply the term processing to those methods of treatment that destroy the coal sub- stance through distillation or hydrogenation.

Jan 1, 1939

By AIME AIME

A PAPER recently presented before the Anthracite Section of the A. I. M. E. by S. J. Phil- lips, Mine Inspector, Fifth Anthracite District, Department of Mines of Pennsylvania, covering the water hazards in the anthracite coal mines of the Lackawanna River Valley, was especially timely because the conditions there are duplicated to a large extent in the Wyoming Valley, which is traversed by the Susquehanna River with its many large tributary streams. Also, in the southern anthracite field, where there are a number of large creeks, similar pumping problems and mine water hazards will in time be presented if mining is continued to its conclusion.

Jan 1, 1936

By Colin Fink

TANTALUM and columbium occur together in tantalite and columbite ores, which may be considered as ferrotantalate (FeTa206), with part of the iron and tantalum replaced by manganese and columbium respectively, the general formula, therefore, becoming (Fe, Mn)O.(Ta, Cb)205. The ratio of tantalum to columbium is not fixed; the amount of tantalum may vary from one-third to three times that of columbium. Minerals having a high content of tantalum are called tantalite, while those possessing larger amounts of columbium are classified as columbite ores. These minerals are found in pegmatites and often occur in veins associated with cassiterite and wolframite, and may contain small amounts of tin, tungsten, titanium and silica.1

Jan 1, 1931

By H. M. Chance

THE present value of most coal properties resides largely in the coal remaining to be mined, which thus constitutes the most important asset. The object of this paper is to discuss methods commonly used in computing the value of mineable coal. To distinguish clearly between such coal values and the values of other property, the several kinds of property values may be divided into classes; this is necessary to avoid unintentional omissions of items of importance. VALUE OF COAL RESERVES Judicial decisions prescribe, and appraisers commonly accept, current sales value as the preferred means for determining the value of transferable property. With few exceptions a property is worth the sum that can be realized from its sale by a willing seller to a willing buyer, a sale in which compulsion urges neither party, and between whom there is no community of interest to fix a value; or it is worth at least as much as a responsible buyer will offer for it. Actual sales of like property or bids from responsible buyers for the property, or for substantially like property, are the best established methods for determining values. Only in the absence of such sales or bids can valuations by other methods be entertained, and only for reasons of weight can sales values be set aside. Sales of coal in the ground, as customarily carried out through lease, under royalty agreements, are therefore the most trustworthy means available for determining the value of coal reserves.

Jan 6, 1926

By Earl Ingerson

BORE surfaces of used guns commonly show a pattern of cracks in various degrees of development. It has been suggested that these cracks may aid erosion by providing channelways for the gases, eventually leading to the tearing out of blocks of metal. Under the general studies of gun erosion conducted at the Geophysical Laboratory it appeared desirable to consider this factor, and to determine the resistance to surface cracking offered by gun steel and by various other materials that might be used in the bores of guns. METHOD AND APPARATUS In order to make such a determination it is necessary to have (I) an arrangement in which the surface to be studied can be subjected to conditions similar to those in a gun with respect to temperature, pressure (developed by explosion gases), composition of the gases and length of time the surface is exposed to the gases; and (2) a specimen that can be examined readily after any number of shots, and then fired again, if necessary. The first of these conditions can be met by using an explosion vessel designed by H. S. Roberts of the Geophysical Laboratory. Fig I shows a cross section of the apparatus. The "gun" G from which the charge is fired is made from the receiver of a caliber 0.30 army rifle, M1903, and the charges are prepared in caliber 0.30 cartridge cases. The test specimen S is held in place by a cone-shaped plug P and by a steel ,bridge B which is bolted to the outside of the explosion vessel on either side of the section shown. The plug, in turn, is held in place by a screw collar C. Maximum pressure is controlled by a brass rupture disk R. Part of the explosion gases flow past the two flat areas on S. st the two flat areas on S. Temperature and composition of gases, and the time before the rupture disk breaks, can be controlled by amount and kind of powder used, and pressure can be controlled by using rupture disks of different thickness. While the explosion vessel used was not designed so that temperature and pressure could be measured, in other vessels of closely similar size and shape containing proportionate charges of the same kind of powder as that used for standard testing procedure, values of 2700°K and 5000 psi were obtained. Since the orifices past the flat areas on the plug are small compared to the rupture disk hole (1:16), most of the gas goes out through the rupture disk when it breaks. The amount that goes by the plug depends on (I) the pressure attained before the rupture disk breaks and (2) the time it takes for this pressure to be built UP. The second condition (examination at will after any firing) is met by using for specimens short rods that have flat areas ground on opposite sides. These flat

Jan 1, 1947

By F. T. Davis

Many contributors have added to the fund of knowledge in the basic sciences related to mineral dressing during the past year. During 1964, the French edition of the Proceedings of the VIth International Mineral Processing Congress together with discussions was printed. Also, complete Preprints of papers delivered at the VIIth IMPC were published in September1. Over a third of the papers presented at VIIth IMPC dealt with fundamentals. COMMINUTION It has been postulated by Ponceleta that flaws need not exist before a stress is applied but rather the flaws are created at the tip of a propagating crack at a stress well below the theoretical breaking stress.

Jan 2, 1965

By William H. Spice

The area on which oil and gas development is reported covers 30 counties, which are included in the Texas Railroad Commission's District No. I. This area not only includes the old established Balcones fault-line group of producing fields but also includes the southwest extension of this trend and some of the deeper Wilcox (Eocene) exploratory development. (Fig. J.) In the old Balcones fault-line zone, three new fields were discovered during 1941. These fields are comparatively small, producing from Dale limestone or Austin chalk. No new fields were discovered during the year in the Edwards (Lower Cretaceous) limestone horizon. One new shallow field was discovered in the Reklaw (Eocene) sand horizon and, in the southwestern part of the district, one oil field and one gas field were discovered in the Navarro (Upper Cretaceous) sand horizon. An extremely important extension was made to the one producing Wilcox (Eocene) field of the district in the Washburn Ranch field of La Salle County. The district produced 6,650,357 bbl. during 1941, which was a 12 per cent decrease under production for 1940. Approximately 4,954,000 bbl. of this total production was produced by the three Edwards limestone fields, Luling, Salt Flat and Darst Creek, the remaining production coming from the other 43 active fields in the district. In all, 3694 wells were producing at the end of 1941, compared with 3559 wells at the end of the previous year. During the year, 139 new producing wells were completed and 29 wells were abandoned in the producing fields. The increase in producing wells represents an increase in new wells over abandonments in these fields, together with a decrease in wells temporarily shut down as of the end of 1941. The majority of production drilling was carried on in the following fields; Bee Creek, Chicon Lake, Elm Creek, Gas Ridge, Pearsall and Tenney Creek. Approximately 250 wells were drilled during 1941, of which 110 were exploratory wells completed as failures throughout the district. Considerable exploratory work was continued during 1941 along the Wilcox trend. Geophysical work employing various types of geophysical methods and leasing activity was continued along this trend, particularly by the major companies. The significance of this activity is apparent from the successful extension and development in the Washburn field of La Salle County, where several well-developed gas-and-oil producing horizons have been developed in the lower Wilcox section between 5100 and 5600 ft. as noted in the following paragraphs. Continued exploratory activity along this general trend as far as present conditions will permit is predicted for 1942. New Fields Elgin Field, Bastrop County.—No. I-A Hiram Walker, Marts and Beaven, Inc., discovery well of the Elgin field, was com pleted on Apr. 22, 1941, in broken Austin chalk from 2820 to 2840 ft., pumping 105 bbl. per day, 36.8°A.P.I. gravity. The well apparently is producing from a crevice in

Jan 1, 1942

By William H. Spice

The area on which oil and gas development is reported covers 30 counties, which are included in the Texas Railroad Commission's District No. I. This area not only includes the old established Balcones fault-line group of producing fields but also includes the southwest extension of this trend and some of the deeper Wilcox (Eocene) exploratory development. (Fig. J.) In the old Balcones fault-line zone, three new fields were discovered during 1941. These fields are comparatively small, producing from Dale limestone or Austin chalk. No new fields were discovered during the year in the Edwards (Lower Cretaceous) limestone horizon. One new shallow field was discovered in the Reklaw (Eocene) sand horizon and, in the southwestern part of the district, one oil field and one gas field were discovered in the Navarro (Upper Cretaceous) sand horizon. An extremely important extension was made to the one producing Wilcox (Eocene) field of the district in the Washburn Ranch field of La Salle County. The district produced 6,650,357 bbl. during 1941, which was a 12 per cent decrease under production for 1940. Approximately 4,954,000 bbl. of this total production was produced by the three Edwards limestone fields, Luling, Salt Flat and Darst Creek, the remaining production coming from the other 43 active fields in the district. In all, 3694 wells were producing at the end of 1941, compared with 3559 wells at the end of the previous year. During the year, 139 new producing wells were completed and 29 wells were abandoned in the producing fields. The increase in producing wells represents an increase in new wells over abandonments in these fields, together with a decrease in wells temporarily shut down as of the end of 1941. The majority of production drilling was carried on in the following fields; Bee Creek, Chicon Lake, Elm Creek, Gas Ridge, Pearsall and Tenney Creek. Approximately 250 wells were drilled during 1941, of which 110 were exploratory wells completed as failures throughout the district. Considerable exploratory work was continued during 1941 along the Wilcox trend. Geophysical work employing various types of geophysical methods and leasing activity was continued along this trend, particularly by the major companies. The significance of this activity is apparent from the successful extension and development in the Washburn field of La Salle County, where several well-developed gas-and-oil producing horizons have been developed in the lower Wilcox section between 5100 and 5600 ft. as noted in the following paragraphs. Continued exploratory activity along this general trend as far as present conditions will permit is predicted for 1942. New Fields Elgin Field, Bastrop County.—No. I-A Hiram Walker, Marts and Beaven, Inc., discovery well of the Elgin field, was com pleted on Apr. 22, 1941, in broken Austin chalk from 2820 to 2840 ft., pumping 105 bbl. per day, 36.8°A.P.I. gravity. The well apparently is producing from a crevice in

Jan 1, 1942

By E. H. Jr. Dix

OF all the alloying elements used in commercial aluminum alloys, copper stands out as by far the most important, and it is perhaps for this reason that the constitution of the aluminum-copper system has received the attention of a number of experimenters covering a period of approximately 20 years. It would be expected that during this time the equilibrium relations had been thoroughly and exactly worked out. In a general way this is true, but there is a surprising lack of agreement in the details of the high aluminum end of the diagram, particularly in regard to the solid solubility of copper in aluminum, which has been given variously as 2 per cent. to 5 per cent. at the eutectic temperature. The importance of this is much greater than might at first appear to one unfamiliar with modern commercial aluminum alloys. This is true because, with one exception, the susceptibility of the strong alloys to heat treatment depends, in part at least, upon the solid solubility relations of copper in aluminum. In 1919, Merica, Waltenberg, and Freeman1 published the first detailed information on these solubility relations. They found that the solubility of copper decreases with falling temperature from about 4 per cent. at 5.25° C. to about 1 per cent. at 300° C. and is apparently still diminishing at lower temperatures. In 1921 there was published a brief account of the results obtained in the National Physical Laboratory, Teddington, England.2 This laboratory, however, reported that 5 per cent. of copper is soluble in aluminum at 540° C., and that this amount decreases to about 3 per cent. at 20° C.

Jan 2, 1926

By Andrew Button

INTRODUCTION This review deals with the controls exerted by unconformities on the stratigraphic and areal distribution of gold (and uranium) in Precambrian conglomerates. The relations described are drawn mainly from Precambrian basins in southern Africa, particularly the Witwatersrand Basin. The mining industry of South Africa started in earnest with the discovery of diamonds in 1866. Gold was first discovered in 1870, and in March of 1886, two out-of-luck prospectors stumbled across what was to become the world's greatest goldfield, in the vicinity of Johannesburg. George Harrison and George Walker sold their claims for a pittance and were heard of no more. The Witwatersrand goldfield has been in continuous operation since that time, some 150 mines having operated at one time or another. Deep mining technology developed here has allowed operations to proceed to depths approaching 13,000 feet. The Witwatersrand has produced some 55% of all the gold ever mined, and currently produces 60% of the world's supply, some 650,000 kg Au per year. To 1971, the Witwatersrand had produced some $32 billion of gold and $2 billion of uranium (when average prices were less than $35/oz. for Au and $10/lb. for U308). At present prices, the annual Witwatersrand production of close to 700,000 kg would be worth about $10 billion. Uranium was discovered in the Witwatersrand in 1923. In the $15-30/lb. bracket, the basin contains a reasonably assured plus

Jan 1, 1983

By B. R. Palmer, M. C. Fuerstenau

Oxide and silicates respond to flotation with a large number of anionic collectors. These include carboxylates (fatty acids), sulfonates, alkyl sulfates, and certain chelating agents. In contrast to sulfide mineral flotation, relatively long-chained collectors (generally longer than 10 carbons) are required to effect flotation of this group of minerals. The structural formulas of these various anionic collectors are presented in Table 1. Formulas and solubilities of various fatty acids are presented in Table 2. These solubilities are those of the dissolved and undissociated species of the acid, e.g. oleic acid, HOl(aq). Of the compounds listed, oleic acid and abietic acid, which IS a major constituent of talloel, are used most commonly in commercial applications. The usage of these two collectors is related to cost and effectiveness. In addition to their high molecular weights, oleic acid contains a double bond in its hydrocarbon chain, while abietic acid is comprised of aromatic rings containing double bonds. The presence of double bonds increases solubility significantly over that of saturated homologues. Stability of metal-collectors assumes a most significant role in these systems, and the solubility products of various metal carboxylates and sulfonates are listed in Tables 3, 4 and 5. In addition to these properties, strength of the acids of these various anionic collectors is also important. The carboxylic and hydroxamic acids are weak acids whereas sulfonic and alkyl sulfuric acids are strong acids. All of the carboxylic acids fall in the range of pK = 4.7 ± 0.5 ([2]); the pK of hydroxamic acid is around 9 ([3]); and the pK of sulfonic acid is about 1.5 ([4]).

Jan 1, 1976

By Jed H. Mosgrove, Paul M. Budzak

INTRODUCTION Good mine ventilation starts at the drawing board. A coal mine will either be adequately ventilated or not, depending upon how good a job was done in the planning. Poor planning will not only result in inadequate ventilation, but may also lead to low productivity. A mine foreman cannot achieve high productivity while trying to maintain 4.2 m3/s (9000 cfm) of air at his last open crosscut. PLANNING What will provide adequate ventilation? A rule of thumb in laying out a coal mine is to provide enough entries in the main entry system to keep air velocities at 2.5 m/s (500 fpm) or less; at this rate of flow, good ventilation may be expected. The intake and return air courses of a coal mine do not improve with age. Entries will deteriorate, ribs will slough, roof will fall, and clutter will accumulate. The resistance offered to air travel will continue to increase with each passing year. Providing enough airways for the present and the future cannot be emphasized too strongly. In order to better appreciate good planning and bring it into better focus, assume a hypothetical mine has the following features: entries 1.5 m (5 ft) high and 6.1 m (20 ft) wide; one intake and one return entry; the mine development is 4.8 km (3 miles) from the intake and upcast ventilation shafts; and the ventilation requirement is 141.6 m3/s (300,000 cfm). Air travel of 4.8 km (3 miles) into a mine and the same distance back to the fan is not unusual. However, to do so with one intake and one

Jan 1, 1981

By Jed H. Mosgrove, Paul M. Budzak

INTRODUCTION Good mine ventilation starts at the drawing board. A coal mine will either be adequately ventilated or not, depending upon how good a job was done in the planning. Poor planning will not only result in inadequate ventilation, but may also lead to low productivity. A mine foreman cannot achieve high productivity while trying to maintain 4.2 m3/s (9000 cfm) of air at his last open crosscut. PLANNING What will provide adequate ventilation? A rule of thumb in laying out a coal mine is to provide enough entries in the main entry system to keep air velocities at 2.5 m/s (500 fpm) or less; at this rate of flow, good ventilation may be expected. The intake and return air courses of a coal mine do not improve with age. Entries will deteriorate, ribs will slough, roof will fall, and clutter will accumulate. The resistance offered to air travel will continue to increase with each passing year. Providing enough airways for the present and the future cannot be emphasized too strongly. In order to better appreciate good planning and bring it into better focus, assume a hypothetical mine has the following features: entries 1.5 m (5 ft) high and 6.1 m (20 ft) wide; one intake and one return entry; the mine development is 4.8 km (3 miles) from the intake and upcast ventilation shafts; and the ventilation requirement is 141.6 m3/s (300,000 cfm) . Air travel of 4.8 km (3 miles) into a mine and the same distance back to the fan is not unusual. However, to do so with one intake and one

Jan 1, 1981