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The Library of the above-named Societies is open from 9 A.M. to 10 P.M., except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and the publications of - scientific and technical societies members of the Institute, with few exceptions, are forced to spend a portion of their time 'in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render - valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish genera1 information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 10, 1916

By S. C. Schaeker, A. W. Schlechten, A. H. Larson

PARRAVANO and Malquori' studied the equilibrium of H2S-Hz with molybdenum and its lowest sulfide which they believed to be MoS2. Mc Cabe' has shown that its composition is actually Mo2S3 and determined its dissociation pressure by means of Knud-sen effusion measurements. Stubbles and Richard- son3 have recently studied the equilibrium of gas mixtures of H2S-HZ with the two-phase solid mixtures of Mo-MozS3 and Mo2S3-MoS2. The latter investigators found that M02s3 deviated slightly from the stoichiometric composition, but they did not determine the homogeneous region of the disulfide phase. Morimoto and Kullerud, studied the Mo-S system by quenching, microscope, and X-ray methods and concluded that the disulfide is stoichiometric. The present investigation was concerned with the measurement of the sulfur vapor pressure variation with composition at 1100°C in the homogeneous region of "MoS2". These measurements were made by reacting: 1) molybdenum powder (99.97 pct Moj with sulfur vapor, and 2) MoS1.g9 (formed by reaction of Mo + H2S) with sulfur vapor in a quartz capsule. Conditions were controlled to form an equilibrated phase within the homogeneous region of the disulfide. The quartz capsule was sealed off initially under a vacuum and the residual gases were gettered by titanium powder contained in one end of the capsule. A mixture of Mo + S or MOS,., + S was in the other end. The section containing the titanium powder was heated for 24 hr at 700°C and then removed by flame sealing. The end of the capsule containing the charge was then heated to 1100°C. The other end of the capsule was maintained at a temperature which would produce the desired sulfur pressure in the capsule (liquid sulfur distilled from the charge mixture was retained in this end). After equilibration, the capsule was removed from the heating assembly and rapidly air-cooled. It is assumed that equality existed between the total sulfur pressures (PT) in the two ends of the capsule and not between the partial pressures of the different molecular species (S, SZ, Three separately controlled heating elements were used to maintain the proper temperature gradient over the length (approximately 12 in.) of the capsule. A thermocouple-Wheelco "Capacitrol" system was used for temperature control of the two end heating elements within 2"C. The center heating element was controlled directly by a " Power -stat". Separate controlling and measuring thermocouples were used for both end heating elements. Pt-Pt(l0 pct Rh) thermocouples were used for 1100°C and Chromel-Alumel thermocouples were used for lower-temperature control and measurement of the assembly. Silver foil was wrapped around the end of the capsule containing the liquid sulfur to insure a constant temperature zone. The thermal gradient over the entire length of the capsule was measured to: 1) ascertain that the length of the constant temperature zone of the liquid-sulfur end and the sulfide end was sufficient, and 2) ascertain that the liquid-sulfur zone was the zone of lowest temperature. The data obtained in this investigation are shown in Fig. 1 and Table I. The total sulfur pressure (PT) and p(S2) were calculated from the data of Braune et UZ.~ The compositions of the equilibrated disul-

Jan 1, 1964

By R. W. Armstrong, P. C. Jindal

WE should like to point out that Hu and cline.1 in their study of the recrystallization of titanium, have obtained data which appear very important for accurately determining the dependence of hardness on grain size for this material. It has been proposed2,3 that the macrohardness. H. of a poly crystalline material should depend on its average grain diameter, l. in accordance with the relationship: H =H0 + kHl-1/2 [1] where Ho and kH are experimental constants. This relationship follows from the hardness dependence on yield stress or flow stress4 and. thence. the Hall-Petch stress-grain size relations.5'6 Fig. 1 shows the Diamond Pyramid Hardness. Dph. values vs the reciprocal square root of the average diameter of the recrystallized grains, taken from the titanium data reported by Hu and Cline. The data in this figure give a linear relationship for the hardness over a wider range of grain diameters than anyone has previously measured. The data are not linear, for example. on an I-1 or l-1/3 scale. At the very large grain sizes the data are in reasonable agreement with measurements earlier reported by Holden, Ogden, and Jaffee.7 For the grain sizes smaller than 1 µ, which correspond in Fig. 1 to hardness values greater than 150, the material was reported as not being completely recrystallized and, therefore, these data appear less meaningful as far as the hardness dependence on grain size is concerned. However. it has been suggested by other investigators that deformed materials exhibit strengthening due to an effective grain size refinement even in the unrecrys-tallized condition.8-10 Also. Hu and Cline have shown that a change in texture occurs for titanium during the recrystallization process and. especially. following it. The influence of this texture change on the hardness-grain size relation would be expected to be less than that reflected in the unidirectional stress-strain behavior, even for an hcp material. because of the actual combined stress system which applies for the hardness test. For, at least, certain combined stresses, average values of the orientation factors should still occur in the stress-grain size analysis of a material exhibiting a preferred orientation.' We previously suggested3 that the experimental constants. H0 and kH. from the Meyer hardness-grain size relation should be correlated with the Hall-Petch constants, uoy and ky.5,6 Our recent study" of the Hall-Petch relation and the hardness-grain size results which obtain for a number of polycrystalline materials shows that: The inequality [2] is explained by noting that the hardness should be correlated. perhaps, with the flow stress at some value of strain, as suggested by Dugdale,12 and. also, that the influence of strain on the Hall-Petch relation is to increase uo and not change k very much." Normally. Dph values and Brinell hardness values are nearly equivalent to each other and to the Meyer hardness number. For the case of titanium, then. the inequality [2] may be evaluated using the experimental values of ao = 8.0 kg per sq mm and ky = 1.3 kg per mm3/2 obtained from the experiment of Guard.6,13 Thus, (Ho/uo) = 12 and (kH/k3) = 1.3. This research has been supported at the University of Maryland through the Center of Materials Research by the Advanced Research Projects Agency of the U.S. Government.

Jan 1, 1969

By Richard A. Conkling

A shale layer, buried beneath two or three thousand feet of strata, in some instances, will upon folding become thicker in the synelines and thinner on top of the anticlines. This can be accounted for, in part, by the stretching on the crests of the fold and the compressing in the troughs; but this will by no means account for all of it, as is shown in the example herein set forth. It is my firm belief that the rest of the thickness is due to flow. What causes the movement, however, does not concern us here, SO long as there is movement, for this article purposes to show its effect upon the producing area of different sands. It is the author's hope, in this way, to drop a hint or two that may be valuable to the oil geologist, in making estimates of future productions and values of oil properties. An example will be given from property in the famous Gushing Pool in northeastern Oklahoma, where the author has had occasion to make a detailed study before recommending some property to his company, and has then been able to watch the results of this work. The author never mapped the surface structure in this pool, as this had been done by Frank Buttram when he was with the Oklahoma Geological Survey. We are using, therefore, a section of his map in this article for our surface contours. The main east dip comes farther east than this section shows. From the 10-ft. contours in Fig. 1, it will be seen that the surface folding is very slight, but in the contour map of the Bartlesville sand (Fig. 2), which was the greatest producing sand, we see much more complex folding. It seems that the folding becomes greater with the depth. Folding may have started in Middle Pennsylvanian times and continued through the Upper Pennsylvanian which is found at the surface. This may, or may not, have been the cause of the increase of folding with depth. However, the fact that mostly concerns us is the interval of shale between the Bartlesville sand and the Tucker sand. The Tucker is the next productive sand below the Bartlesville. Not enough wells have been drilled to the Tucker sand to make a contour map of it, but

Jan 1, 1917

By C. N. Schuette

THE producers of this liquid metal call it quicksilver, while the consumer generally refers to it as mercury. It is one of he seven metals that were known to the ancients. These seven were gold, silver, iron, copper, quicksilver, lead, and tin. Other metals were sometimes accidentally alloyed with some of these, but it was not until 1490 that antimony, for example, was discovered and identified as a separate metal. It is not surprising that quicksilver should have been known in ancient or even in prehistoric times, as globules of the native metal often occur in the outcrops of the ore. Furthermore, the first man to build a fire on an outcropping of quicksilver ore would probably have found globules of quicksilver in the cold ashes of his fire after it burned out. The inability to pick up the globules with the fingers would excite interest and an attempt to gather it in shells or gourds to be exhibited and traded. The ore of quicksilver is the red sulfide, cinnabar, which has been mined and used as the pigment vermilion since before the beginning of written history. In recorded history, quicksilver is first mentioned in documents by Aristotle, 384-322 B.C. Theophrastus, in 315 B.C., credited the Athenian, Callias, with the invention of methods to beneficiate cinnabar in 415 B.C. In China also there are records antedating Christ which mention both vermilion paint and the fluid metal. From these early records, it seems certain that not only was cinnabar used as a pigment in those days but also that the metal was reduced from the ore and was used for amalgamation, for gilding, and for medicinal purposes. Quicksilver mining and metal-

Jan 1, 1953

By Claude H. P. Lupis, John F. Elliott

The classic Siez~erts' technique has been employed to determine the solubility of oxygen in liquid pure silver and the effect on the oxygen solubility of solute metal additions to liquid silver. The results indicate that oxygen deviates slightly from Sieverts' law in pure silver as = 3.9. Gold, platinum, md palladium decrease the solubility of oxygen in silver. First-order free energy, enthalpy, md entropy interaction coefficients are determined from the data. An important aspect in the establishment of the formalisms to be applied to represent the thermody-namic behavior of components of solutions is the accuracy of the experimentally determined thermody-namic properties. Wagner developed the first-order free energy interaction coefficient.' Recent papers2'3 extend the treatment formally to other thermodynamic properties and define the second- and higher-order interaction coefficients. A current communication4 considers in some depth the requirements and limitations imposed because of experimental error on the use of several formalisms now under active consideration in the field. This communication reports the results of an experimental study of the behavior of oxygen in liquid silver alloys that was carried out concurrently with the development of Refs. 2 and 3 with the hope of providing sufficiently precise information so that enthalpy and entropy interaction coefficients could be determined. THE EXPERIMENTS The Sieverts technique was employed using an improved design of the reaction bulb over that developed originally by Humbert5 and subsequently improved by pehlke6 and Weinstein.7 The Vycor reaction bulb as shown in Fig. 1 was air-cooled and contained a port for the thermocouple angling off to one side and a vertical port for connections to the gas supply and

Jan 1, 1969

The first meeting of the Naval Consulting Board was held at the office of the Secretary of the Navy, Washington, D. C., on Oct. 6, 1915. The Board organized by electing Thomas A. Edison, Chairman, Peter Cooper Hewitt, First Vice-Chairman, William L. Saunders, Second Vice-Chairman, and Thomas. Robins, Secretary. All of these officers are members of the American Institute of Mining Engineers. The other members of the Board are given below, and those who are members of the Institute are marked with an asterisk: *W. R. WHITNEY MATTHEW B. SELLERS. L. H. BAEKELAND. HUDSON MAXIM. FRANK JULIAN SPRAGUE. HOWARD T. COFFIN. BENJAMIN C. LAMME. ANDREW J. RIKER. R. S. WOODWARD. HENRY A. WISE WOOD ARTHUR GORDON WEBSTER. ELMER A. SPERRY. A. M. HUNT. *BENJAMIN B. THAYER. ALFRED CRAVEN. *J. W. RICHARDS. *SPENCER MILLER. *LAWRENCE ADDICKS. WILLIAM LE Roy EMMETT.

Jan 12, 1915

By AIME AIME

Air transport supplants the old methods. The 3-piece canoe fits in the plane and likewise makes possible not a bad division of labor over a 5-mile portage

Jan 1, 1933

By C. H. Hitchcock

A brief resiclence in Virginia hasenabled me to examine some of its crystalline strata, and a few hints, concerning their correspondence with similar rocks elsewhere, may be of service to those who are studying them. In comparing the crystalline rocks of Virginin and New England, we may first recall the similarity of their geographical position. They constitute a continuous belt, being traceable through the Highlands of New York and yew Jersey, Southeastern Pennsylvania, in the counties of Bucks, Montgomery, Philadelphia, Delaware, and Chester, and Marylund. Thus the Green Mountains of Vermont and the White Mountains of New Hampshire seen] to be topographically continuous with the Blue Ridge and Midland districts of Virginia. This tract of country has been termed the Atlantic area in distinction from the Appalachian territory, whose eastern limit is the great, Lower Silurian limestone valley extending from the St. Lawrence and Champlain valleys to Alabama. The Appalachian formations were studied by the brothers Rogers, forty years since, and found to refit, unconformably upon the western flank of the Blue Ridge, the oldest of the series adjoining the gneisses, followed westerly by the other Palseozoic members in a regular ascending order, to which numercial designations were applied—Number 1 being the Cambrian, Number 2 the Lower Silurian Iimeqtones, etc?. In Vermont the same conclusion Was presented in the State reports: the Green Mountains were said to possess the anticlinal structure, and to underlie the quartzites and limestones. Inasmuch as this Atlantic area is' topgraphically continuous from the Middle to the Northern States, and is unconformably overlaid upon the west side by the same succession of strata, the presumption ii very strong that the history of bath sections has been the same, and that the entire area is of Eozoic age. Cross sections, in both districts, illustrate the existence of gigantic overturns, causing the strata of 'the Appalachian region to dip to wards the Atlantic gneisses. To the beginner it would appearthat tile Silurian group must dip beneath the crystallines, and hence many of the geologists in the beginning of the study of the stratigraphy of this easters border of the continent believed that

Jan 1, 1882

William B. Phillips, Birmingham, Ala.: The questions raised by Messrs. Wilkens and Nitze are in the highest degree interesting to owners of low-grade iron-ores, aizd no less so to blast-furnace managers. If it can be shown that ores heretofore considered worthless can be brought within the limit of economic use, many large and readily accessible deposits may come into market on the one hand, while on the other the possible increase in the output of the furnace per ton of ore used will prove of advantage to the iron-maker. It cannot, of course, be claimed that this process has been employed on a working-scale with respect to iron-ores, and in so far as concerns results on a large scale no one is any wiser than his fellow. Granting that the results obtained in an experimental way (and certainly the experiments were conducted with a great deal of care) can be attained in practice, we would still be facing the question, what it would cost to get them. In the absence of any specific data, we have to fall back on general principles, helped along, as far as possible, by indications afforded by the experiments. I must confess that as regards the Clinton ores, which I have studied to some extent, I am not sanguine of making a ton of 53 to 54 per cent. concentrates from less than 1.75 tons of 40 per cent. raw ore. It may be possible to get the iron in the heads to 56 to 57 per cent., but the lesser richness of the middlings will probably reduce this to 53 to 54 per cent. in the salable stuff. As the authors remark, it is not worth while to discuss the concentration of the better grades of " soft" Clinton ore; for the price at which they are now delivered at the furnaces, and the comparatively limited amount now remaining, render their concentration unadvisable. If it is to succeed in the Birmingham district, the process must be applied to the low-grade soft and hard ores now con-

Jan 1, 1897

By Robert J. Evans

An in-seam tester, which is a hydraulically activated single-pick instrument to measure and record pick cutting forces, was designed and fabricated to establish criteria necessary for the design and development of a water-jet-assisted rotary drum cutting system using moderate-pressure jets (3,000 to 10,000 psi). Data are presented for cutting trials in a simulated coal block and underground in the Pittsburgh coal seam for water-jet assist and dry cutting. Data analysis indicates that water-jet assist significantly reduces pick forces.

Jan 1, 1984

By Robert E. Hochscheid

The subject article appears in the February, 1978, edition of Mining Engineering, and on page 190 carries the statement, "As most operators know, in a Water-Only cyclone, ability to adjust the vortex finder is quite important due to the sensitivity of this type of operations to variance in feed conditions and having to take them apart to make this adjustment is always a nuisance." Our experience as a manufacturer and supplier of Water Only cyclones does not agree with the above statement, and we offer the following brief discussion. Our company finds that the sensitivity of the Water-Only cyclone is a function of the fineness of the coal being washed, with the sensitivity to vortex finder length being greatest for coals coarser than 3/4-in. and virtually insensitive to raw coal finer than 1 mm. For coals finer than 1 mm, we find that we can use the shortest standard vortex finder in either our 10- or 15- in. Water Only cyclone without exception. For coals 5/8-in. x 1 mm ceramic vortex finders of fixed length have been satisfactory in all cases following an initial testing period in which the length was determined. Coals coarser that 5/8-in. are more sensitive to the vortex finder length, and two installations handling coals coarser than 1-in. continued to experiment with vortex finders of various lengths long after the initial startup period. For coals of all sizes, final adjustment of product quality has been achieved by determining the optimum size of apex orifice, which is accessible and readily changed, if necessary. Comments above assume no unusual change in the coal being washed or the required quality of clean coal.

Jan 1, 1979

By D. E. Norquist, J. E. Moeller

The results of wear on marked balls, 4, 31/2, 3, and 2 in. diam are given. All balls were forged steel of practically the same chemical analysis and hardness. The results indicate that balls in a given mill for a given length of time will have equal diameter losses, regardless of size.

Jan 6, 1950

By J. W. Spretnak, V. Kandarpa

Stress -induced ordering of carbon atoms is studied in a series of Fe-Mn-C alloys. A prominent peak is found in the vicinity of 280°C at frequencies of the order of 1.0 cps, with an associated activation energy of 37 kcal per mole. The height of the peak is linearly rekzted to the concentration of carbon in solution. The distortion of octahedral holes by manganese atoms appears to be predominant over carbon-carbon pair interactions. RELAXATION by stress-induced ordering of point defects is expected whenever the introduction of these point defects produces distortions which have a lower symmetry than that of the lattice. Under zero stress, the isolated point defects occupy the crystallographic-ally equivalent positions in the lattice, as these represent states of equal energy. However, if the defect sites are asymmetric, application of an uniaxial stress will split the energy states, and a redistribution of the defects among various states will take place. This is the case of the internal friction peak called the Snoek peak,1 resulting from isolated interstitials in bcc metals. The interstitial sites in this case have tetragonal symmetry. In the case of fcc and hcp lattices, such an effect is not expected from isolated point defects because of the symmetrical nature of the interstitial sites. However, internal friction peaks arising from interstitial diffusion have been reported both in hcp2,3 and fcc4-8 lattices. These peaks are often explained on the basis of stress-induced ordering of interstitial solutes, caused by the deviation of interstitial sites from their cubic symmetry through the presence of nearby defects. In the case of fcc lattices, evidence for interactions of both the substitutional-interstitial4,6,13 and interstitial-interstitial types5'798'14 have been presented by various investigators. The purpose of the present investigation was to study the internal friction peak attributed to the diffusion of interstitial carbon atoms in high purity austenitic manganese steels and to account for the peak in the light of the existing models. MATERIALS The Fe-Mn-C alloys used in the present investigation were made in two different ways, designated as Type I and Type 11. Type I alloys were made from high purity Fe-Mn alloys obtained in the form of 0.04- in.-diam wires from Materials Research Corporation, Orangeburg, N.Y. These alloys were carburized to different levels using gas mixtures of H2 and CH4 at 1000°C. Type I1 alloys were made in this laboratory starting with zone refined iron, spectrographically pure manganese, and spectrographically pure carbon. They were melted in an argon arc melting furnace and drawn into 0.04-in.-diam wires. All the wires were annealed at about 900°C for 3 hr prior to the internal friction experiments. After the measurements of internal friction, the phases in the samples were identified by X-ray diffraction and the carbon determined by the combustion method. EXPERIMENTAL PROCEDURE In the present work, a classical Ke-type pendulum was used. The details of the equipment were described previously by D. T. Peters.9 Dry helium at 40 torr was used in all the experiments. The internal friction, measured as the logarithmic decrement of the torsion amplitude of vibration was determined as a function of temperature, from ambient to about 500°C. The background internal friction was assumed to have the form of the exponential of the inverse temperature and was subtracted from the raw data. The height of the peak was measured at the position of the maximum in the plot of the internal friction versus temperature. The activation energies of the peaks were measured by the peak shift method. The internal friction values for an alloy were obtained as a function of temperature at different frequencies of vibration. The position of the peak changes with frequency, the higher the frequency the higher the peak temperature. The activation energy of the process associated with the peak is obtained using the formula

Jan 1, 1970

By Roshan B. Bhappu, Thomas J. Lien

The DYNA WHIRLPOOL Processor (DWP) is a cylindrical dynamic heavy media vessel. It is used to beneficiate fine ore sizes from one and one-half inches in diameter down to 65-mesh. Process units available treat up to 80 tons per hour. Units can be manifolded for higher capacity plants. Finely ground magnetite and ferrosilicon are used for media. , Installed capital costs are from $4,000 to $6,000 per ton hour of feed. Operating costs are from $0.30 to $0.50 per ton of feed. The DWP is used to beneficiate metallic and non-metallic ores and coal. The OCC Vessel is a static heavy media separator used to beneficiate coarse ore up to six inches in diameter and auto scrap. Process units available treat up to 300 tons per hour.

Jan 1, 1978

By Clarence Linville

FULTON1 says: "Speiss is an artificial arsenide of iron containing smaller amounts of other metals. In constitution it is similar to a matte except that arsenic replaces sulfur." For the purposes of this paper it will be necessary to broaden the definition, and I propose the following: Speiss is an artificial mixture of arsenides, of which arsenide of iron may be taken as a type, but iron may be replaced in part or wholly by other metals (such as copper, nickel, cobalt, lead and zinc) and the arsenic may be replaced in part or wholly by antimony. In addition to antimony and arsenic, speisses often contain sulfur. Speisses usually also contain both silver and gold. Table 1 illustrates the variations that may be encountered. TABLE 1.-Speiss Analyses

Jan 5, 1925

By Felicia F. Peng

The computer graphic routines and digital simulation program of coal cleaning circuits have been developed in the Mineral Processing Engineering Department, West Virginia University. The functions of the program include computing, tabulation and graphing of 1) washability characteristics of raw coals, 2) blending, 3) Tromp distribution curves for two washer types-- water only and dense medium, 4) predicting the functional relationship of yield and qualities of clean coal product in individual and overall coal cleaning circuits in coal preparation plant, and 5) determining the optimal clean coal yield based on the market and environmental specifications. Amdahl 470 V/7A digital computer, Tektronic 4025 graphic terminal and Tektronix 4663 digital plotter with Fortran IV are used to achieve the goals. The simulation with the aid of graphic routine program of coal cleaning circuits is a useful tool for coal preparation engineers in evaluating the feasibility of proposed flowsheets, in investigating the effect of a modification in a unit operation of an existing plant, in analyzing the off-line optimization, and in comparing the alternative circuit control strategies. The coal cleaning process simulation with graphic routine can contribute greatly to the decision making processes of preparation plant design.

Jan 1, 1983

By E. J. Hall

(Butte Meeting, August, 1913.) THE iron-nail method of assaying has been used for a number of years, but has not met with the approval of all assayers. The method possesses advantages which may be given as follows : (1) no preliminary treatment is required ; (2) a lead button of proper size can be obtained (3) it is economical. On, the other hand, it has its disadvantages, which may be summed up as follows: (1) it is not applicable to ores containing large amounts of impurities other than sulphur, as practically all the base metals will contaminate the lead button ; (2) the slag is unsatisfactory in the larger number of fusions; (3) the method was known to give low silver results under certain conditions and the gold results were questionable. It was with the idea of determining the extent of this latter disadvantage that the following investigation was undertaken. It is well known that the fusion obtained in the lend assay is far more satisfactory than that in the " nails method " for gold and silver. The principal difference in the charges as a class is the presence of considerable reducing agent in the lead charge, and a limited oxidizing action in the nails charge, due to PbO. The possibility of improving the nails fusion by simulating the lead charge was the reason for using argol in some tests, even though there were reasons for expecting this would have -au objectionable effect on the results.

Jan 6, 1913

By R. J. Mechin

IN the early part of 1934, the St. Joseph Lead Co. purchased from the Kadco Corporation three dust-removal units, two suitable for raise work, and the other for drifting operations. The equipment was installed at the Balmat mine, in St. Lawrence County, New York. The Kadco dust-control system can be briefly described as one in which hoods, through which the drill steel is drawn, control the dust at the drill hole, the dust is conveyed through rubber hose or pipe to a collector, where it is removed from the air stream, and the air is then available for recircula-tion in the working place. As during the last few years a number of studies had been completed for the purpose of determining whether or not the dust was effectively removed by the Kadco system, and as the dust counts taken in these tests apparently indicate that it was, the St. Joseph Lead Co. was only inter-ested in obtaining data to show the efficiency of drilling, expressed in terms of minutes per foot drilled, when -using Kadco equipment, in comparison with the former method of drilling dry in a raise and drilling wet in a drift. Comparative dust counts were taken at Balmat, however, by the Metropolitan Life Insurance Co. to show the difference in the dust content of the air in which the operators worked when drilling dry, wet, or with the Kadco equipment.

Jan 1, 1935

An experiment substituting pneumatic crawler drills for large-diameter rotary rigs in overburden stripping operations has indicated significant bit cost savings for Perry and Hylton Coal Co., Beckley, W. Va. The test was conducted in the Egeria Mountains (part of the Appalachian Range), where about 30 m (100 ft) of overburden consisting of hard, seamy sandstone and shale must be removed to recover a 560-mm (22-in.) vein. Perry and Hylton operates ten surface mines and is presently developing three more for start-up in the near future. The company follows a progressive policy toward ecological concerns, incorporating a self-imposed systematic mining and reclamation program for mined lands which leaves the landscape in a suitable condition for further development by local communities.

Jan 6, 1976