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By Richard C. Timberlake

The disposal of phosphatic clays has presented a problem to the phosphate industry since the mining of phosphate rock first began in Polk County. As the flotation process was introduced in the late 1920's the problem of clay disposal was increased significantly since clay is present in proportionally greater quantities in reserves yielding flotation concentrates. Because of their physical character and the tremendous surface area per unit volume, these clays have the characteristic of retaining large volumes of water as they are slurried during processing. The disposal of clay and the recovery of a portion of the water require settling areas with a capacity ranging up to 2 cu ft for each cubic foot of phosphate matrix mined. According to a recent study by the Bureau of Mines, the average cost for disposal of these wastes is 24.5[c] per ton of product. This is a major cost of phosphate rock production.

Jan 12, 1969

By Kenneth K. Humphreys, J. W. Leonard, T. S. Spicer

INTRODUCTION Reasons for Thermal Drying The continuing increase in the percentage of - '/4 in. ( -6.3 mm) coal produced as a result of the increased use of mechanical mining methods has, over the years, tended to shift considerable portions of the work of producing salable coal to the fine coal cleaning section of the preparation

Jan 1, 1979

Regulation of the Coal Industry. BY HOWARD N EAVENSON (Tech Pub 711, also Trans, vol 119 3400 words) A review of conditions in the bituminous coal industry during the last 15 years and of the attempts to remedy them through Appa¬lachian Coals, Inc, and through the NRA The lack of any provision in the so-called "Guffey" law for conservation of our coal supplies is pointed out and the efforts at regulation of the English coal industry are described Assuming that some regulation of the industry is necessary to maintain reasonable working and living conditions and that Federal control by compulsion will not be possible, the requirements for regulation

Jan 1, 1937

By H. C. Stumpf, L. A. Willey, V. L. Fink

Very few studies of the aluminum-sodium system have been reported. Heycock and Neville1 were unable to detect any solubility of sodium in liquid aluminum. Mathewson2 prepared an equilibrium diagram consisting of two horizontal lines at the melting points of the two metals. He was unable to detect solubility at either end of the system. Scheuer3 first developed a method for the chemical determination of sodium in aluminum and then studied the solubility of sodium in liquid aluminum. His method involved heating aluminum with excess sodium under hydrogen until the two liquids were at equilibrium, chilling the melt, and analyzing the aluminum-rich layer. He reported the solubility to be 0.10 pct sodium at 700°C, 0.115 pct at 750°C, and 0.128 pct at 800°C. This paper on the aluminum-sodium system is the twenty-first in a series from the Aluminum Research Laboratories describing equilibrium relations in aluminum alloy systems. Materials The alloys for this investigation were prepared from electrolytically refined aluminum (99.99 pct) and sodium of reagent quality conforming to specifications of the American Chemical Society. Chemical analysis of the aluminum showed the fol- lowing impurities: 0.002 pct Si, 0.002 pct Fe, 0.002 pct Cu, <0.001 pct Mn, 0.002 pct Mg and 0.001 pct Na. The sodium content of all alloys was determined by either chemical or spectro-graphic standard procedures5 No. IIA and No. SI I respectively. Determination of Miscibilitv The boundary of the miscibility gap was determined by a modification of the method of Scheuer3 and of that used by Henry and Cordiano. As finally developed the method was as follows: A fused alumina crucible 25 mm id with 75 mm depth and 1.5 mm wall thickness was placed on the bottom of a container made from a 4-in. length of 1 1/2-in. iron pipe and pipe caps. ?&apos;he space around the sides of the crucible was filled with 40 mesh crystalline alun-dum. A charge of 60 g of aluminum and 10 to 15 g of sodium was placed in the crucible, the sodium first being trimmed and rinsed with iso-pentane to remove kerosene. The container was tightly capped, filled with argon (99.6 pct pure), and heated to the desired temperature (between 670 and 800°C). A positive pressure of argon (about 8 mm of mercury) was maintained through a small pipe to the upper cap. After soaking for from 2 to 5 hr, the container was quenched by directing a stream of water onto the base, so that solidification of the aluminum-rich layer was rapid and essentially unidirectional. Analyses were made on drillings taken from the bottom of the ingots after machining off the surface layers. Pre-

Jan 1, 1949

By W. F. James, Richard Murphy, S. N. Kesten, A. H. Lang

The paper is a summary of information on Canadian deposits of uranium and thorium up to the end of 1948, prepared by geologists of Eldorado Mining and Refining Ltd. and by the specialist on uranium deposits for the Geological Survey of Canada. The paper contains a history of Canadian uranium and thorium discoveries, a working classification of the deposits, fairly detailed descriptions of the Eldorado mine and of properties in northern Saskatchewan, and shorter accounts of several other discoveries.

Jan 2, 1950

By L. W. Kempf, R. S. Archer

The binary aluminum-silicon alloys have certain characteristic advantages which are now well known, and these alloys have come into considerable use during the past several years.&apos; Their field of application has been limited to a certain extent, however, by their low yield point and hardness, low endurance limit, and relatively poor machining characteristics. These properties are improved by the addition of copper, and the ternary aluminum-silicon-copper alloys constitute an important class. The addition of copper decreases the corrosion resistance of the aluminum-silicon alloys and increases specific gravity. Magnesium is a hardening addition which seems to have relatively little effect on corrosion resistance, and which, of course, reduces specific gravity. The object of the work described in this paper was the development of alloys and heat treatments for the production of sand castings and permanent-mold castings having substantially all the advantages of the binary aluminum-silicon alloys together with mechanical properties improved to a degree permitting wider application. Constitution of Alloys Magnesium and silicon combine in aluminum alloys as the compound Mg2Si, which forms a binary system with aluminum. In alloys containing an excess of silicon over that required to form the compound, solidification ends with the freezing at 1022&apos; F. (550&apos; C.) of a ternary eutectic of aluminum, Mg²Si, and silicon. Judging from the horizontal projection of the liquidus surface as given by Hanson and Gayler,² this ternary eut,ectic contains about 13 per cent. silicon and 6 per cent. magnesium. All of the alloys discussed here contain excess silicon, so it

Jan 1, 1931

By W. N. Marchant, P. T. Brooks, P. B. Altringer, R. O. Dannenberg

The US Department of the Interior, Bureau of Mines conducted laboratory tests to devise a process for recovering a marketable grade of tungsten from the brine of Searles Lake, Calif. The brine contains only 56 ppm W (70ppm WO3). Using ion exchange resins synthesized by USBM chemists, 98% of the tungsten was extracted from the brine and 92% of the tungsten was recovered as a marketable iron-tungsten concentrate containing 44% tungsten as tungsten trioxide. Although major technical problems have largely been resolved, research is progressing to escalate testing in a process research unit to provide more reliable data for an economic appraisal

Jan 1, 1980

By I. Fatt, D. N. Saraf

A method is described for measuring two- and three-phase relative permeabilities in sandstones or sand packs using a nuclear magnetic resonance (NMR) technique to determine fluid saturations. Two- and three-phase relative permeabilities have been determined on Boise sandstone using the NMR technique of saturation measurement. Three-phase relative permeability to water was found to depend only on the water saturation, whereas three-phase permeability to oil depended on both the water and oil saturations. Relative permeability to gas in three-phase flow was found to depend only on the total liquid saturation. INTRODUCTION Three-phase relative permeabilities are extremely useful in calculating field performance for reservoirs being produced by simultaneous water and gas drives. Three-phase relative permeability data are also needed for analyzing solution gas-drive reservoirs which are partially depleted and are being produced by water drive. Some thermal recovery processes involve three-phase flow which require three-phase relative permeability data for predicting reservoir behavior. Unfortunately, three-phase relative permeability measurements have rarely been made. Also, because of the scarcity of three-phase data, it has not been possible to date to relate other measured rock characteristics to the relative permeabilities with a great certainty. Leverett and Lewis,l Reid2 and Snell3 have reported three-phase relative permeability data on unconsolidated sands. Leverett and Lewis used ring electrodes spaced along the length of the sand sample to measure the resistivity of the sample which was assumed to be monotonically related to brine saturation. Gas saturation was determined from pressure-volume measurements. Oil saturation was obtained by material balance on the cell containing the sand sample. This method is involved and time consuming. Another difficulty arises from the fact that the resistivity of the sand is a function not only of saturation of brine but also of the distribution and saturation history of the brine in the pore spaces. Reid2 used a gamma ray absorption technique for measuring liquid saturation. This method has the disadvantage that total liquid saturation rather than oil or brine saturation is all that can be measured and still another method is required to determine the saturations of individual components. snel13 used a neutron bombardment method which also required a separate determination of the individual component saturations. Caudle et al.4 measured three-phase relative permeability on consolidated sandstones using vacuum distillation for determining fluid saturations. Distillation after each reading makes this technique very lengthy and time consuming. Corey et a1. 5 and Naar and Wygal 6 measured three-phase relative permeability on sandstones by the capillary-pressure method. Semipermeable diaphragm assemblies were used at each end of the core specimen to keep the water phase in the core. Gravimetric methods were used to determine fluid saturations. Sarem7 recently reported an unsteady-state method for measuring three-phase relative permeability on sandstones. This method is an extension of Welge&apos;s method8 for measuring two-phase relative permeability. Although Sarem&apos;s method is simple and comparatively fast, the assumptions involved may oversimplify the problem. Sarem&apos;s assumption, that in all rocks relative permeability to each fluid will depend only on the saturation of that fluid, seems to be rather unrealistic. Neglecting capillary effects at the end of the core is also a weak assumption. Donaldson and dean9 measured three-phase relative permeability using a method similar to Sarem&apos;s.

By Kun Li, Alex Simkovich

The rate of dissolution of alumina in carbon-saturated liquid iron has been studied experimentally in a system where alumina was in the form of a cylindrical rod immersed in an iron bath contained in a graphite crucible. Data obtained consisted of the concentrations of aluminum in the melt as a function of time. In the case of static experiments, the data are shown to agree with theoretical prdictions based on the diffusion of aluminum.. The rate of dissolution was greatly increased by the rotation of the alumina rod. It is concluded that the diffusion of aluminum from the alumina/metal interface is the rate-controlling step. In the past, thermodynamic investigations of systems encountered in ferrous process metallurgy have received widespread attention. More recently, considerable work has been devoted to the study of kinetics associated with these systems in an effort to determine their rate controlling mechanisms. The alumina-iron system is of great importance in ferrous metallurgy. Yet information concerning kinetics of reaction in this system is seriously limited. The present study was made in order to establish the rate-controlling step for dissolution of solid alumina in liquid iron. LITERATURE REVIEW A number of papers concerning dissolution of solid metals in liquid metals have been reported in the literat~re. Generally, for these simple systems, dissolution is controlled by mass transfer of the dissolving species. Complex systems involving dissolution of solid metal carbides and oxides in liquid metals and slags have been studied to a much lesser extent. Skolnick5,6 reported on the reaction between liquid cobalt and poly-crystalline cylinders of tungsten carbide, in which the cylinders were dissolved while being rotated about their longitudinal axes at various speeds and temperatures. As a result of unexpected preferential grain boundary attack by the liquid cobalt, large errors in the measured dissolution rates occurred because of loss of tungsten carbide grains to the liquid cobalt. Nevertheless, it was possible to establish that the liquid Co-W carbide reaction was not controlled by mass transfer. In a similar approach, cooper7 was able to show that artificial sapphire rods, (alumina single crystals) dissolving in lime-alumina-silica slags obeyed a mechanism of mass transfer control. Here, again, the rods were rotated at various speeds and temperatures, and the process was followed as a function of these variables. Forster and Knacke8 took a practical approach to reaction between slags and refractories. By blowing argon through refractory cylinders of silica, silli-manite, or dolomite and directing the gas to rise along the slag-refractory interface, it was possible to increase the rate of mass transfer. Although the method was admittedly crude, it nevertheless permitted an evaluation of the relative stabilities of refractories with respect to slag attack. Data were interpreted on the basis of mass transfer control. EXPERIMENTAL TECHNIQUE Apparatus. An illustration of the apparatus used in this study is shown in Fig. 1. The furnace consisted of a Morganite recrystallized alumina tube wound with a molybdenum coil. A secondary molybdenum heater was mounted around the upper half of the primary coil to aid in controlling the thermal gradient within the furnace. The primary heater tube was 3 in. in ID and 30 in. long. A reducing mixture of 95 pct N and 5 pct H was maintained around the heating elements. Thermal insulation was provided by alumina powder. The chamber within the primary combustion tube contained a boron nitride block near the top to assist in controlling the thermal gradient to the furnace and also to provide a bearing surface for the rotating graphite shaft. The outside diameter of the graphite shaft was $ in. A separate threaded graphite specimen holder was screwed into the end of the shaft. The holder contained a tapered hole drilled into the end to guide the oxide specimens as they were pressed into it for mounting. Additional guidance for the rotating graphite shaft was furnished by a water-cooled bronze bushing attached to the top of the furnace. A steel clamp was fastened to the upper end of the graphite shaft and rested on a thrust bearing; the shaft and clamp were driven by a dc motor through a set of gears. Two O-rings located immediately above the bronze bushing maintained a gas-tight seal about the graphite shaft. The lower half of the alumina tube housed the crucible and charge, which were placed on a 3/4-in. diam movable alumina support tube. With this arrangement, charges could be inserted into or removed from the furnace while the hot zone was maintained at or above 1000°C. To control the temperature of the furnace, the thermocouple was mounted inside the support tube and in contact with the crucible bottom. Stray electric fields in the furnace were of sufficient intensity to cause erratic indications by the thermocouple. By enclosing the thermocouple protection tube in a molybdenum sheath and grounding this shield, the problem was eliminated. Output of the thermocouple went to an automatic continuous balance controller. Procedure. A typical run was as follows. First, electrolytic iron was premelted in graphite crucibles and cast into graphite molds with the same configura-

Jan 1, 1970

By Herbert Hoover

THE time has arrived in our national development when we must have- a definite national- program in the development of our great engineering problems. Our rail and water transport, our water supplies for irrigation, our reclamation, the provision of future&apos; fuel resources, the development and distribution of electrical power, all &apos;cry out for some broad-visioned national guidance. We must create a national engineering sense of provision for the nation as a whole. If we are to develop this national sense of engineering wand its relations to our great human problems, it must receive the advocacy of such institutions as this. We, together with our sister engineering societies, represent the engineers of the United States. It is our duty as citizens to give voice to those critical matters of national policy which our daily contact with this, the fundamentally constructive profession, illuminates to us. Just as our medical associations voice the necessity of -safeguards to national health; as the bar associations of safeguards to our judiciary, so the engineers should exert themselves in our national engineering policies. We have none; but we need some, or the next generation will face a lower instead of a higher standard of living than ours.

Jan 1, 1920

By A. Filers

IN a former paper on Western Smelting Works, I mentioned the great difficulty of obtaining accurate information in regard to the economy of the processes in practice ; and to-day, although nearly two years have elapsed since my former paper was written, I am sorry to say that very little improvement has taken place in the keeping of accounts, and in the direction of a more systematic management in the majority of these works. But I am quite certain that by this time even the most sanguine furnace managers must have become convinced, from the experience of the last year, that somewhere in their processes there are enormous losses. Rates for the purchase of ores in 1873 were not as high as they were in former years in certain parts of the country ; labor was no higher than formerly ; the demand for unparted lead was good throughout the year, with the only exception of the time of the panic, in the fall of 1873; yet there are, of between 40 and 50 works, not more than two or three in Utah and Nevada to-day, that have paid a reasonable interest on the capital invested.

Jan 1, 1875

Electro-mechanical actuator, self-protected for mechanical and electrical overload, is developed by RACO. Tubular housing consists of squirrel cage motor with hollow rotor shaft and inner threads in the rotor. Features stroke distance of 2-72 in. and wide range of trust (20 lb-10 tons). (100) Agglomeration systems, offered by Ferro-Tech, incorporate pelletizing, briquetting and extrusion systems to agglomerate materials too fine to convey, load or feed to a process. Equipment includes disc and drum pelletizers, briquetter presses, compactors, extruders, pugmills and mixers, dryers, coolers, feeders and conveyors. (101)

Jan 9, 1973

By M. A. Torcaso, P. Raimondi

To study mass transport in systems simulating oil recovery processes, different porous media were saturated with a mobile (carrier phase) and a stationary phase. Slugs of carrier phase containing a small amount of solute were displaced with pure carrier phase. By analogy to the chromato-graphic processes, the velocity of the solute can be predicted from a knowledge of the partition coefficient and the saturation provided that equilibrium between the two phases exists. Equilibrium was found to exist for different porous media, solutes and rates. The conditions were varied over the range normally encountered in the laboratory and in the field. The longitudinal dispersion of a solute undergoing interphase mass transfer was also investigated. INTRODUCTION The production of hydrocarbons by gas cycling, enriched gas drive and C02 or alcohol displacement involves, among other factors, relative motion between two phases and compounds, hereafter called solute, which are soluble in both phases. The solute is carried forward by the faster flowing phase at a lower velocity than the average velocity of that phase. Retardation of the solute is caused by chromatographic absorption and desorption in the slower flowing phase and by the degree of departure from equilibrium. At equilibrium the concentration of solute in the two phases can be related by the equation* CSw = K Cso ,............(1) where C, and C are the concentration of solute in the aqueous and oleic phases respectively and K is the equilibrium ratio, or partition coefficient. Displacement theories must contain an explicit assumption with regard to equilibrium, i.e., whether the compositions can be related by Eq. 1. The existance of equilibrium depends, in general, on the relative velocity between the phases. Unfortunately, other factors such as gravity segregation and viscous fingering, also depend on velocity. For this reason, whenever effects of rate on displacement were observed,2-4 it was practically impossible to discern what caused them — lack of equilibrium or the factors mentioned above. Equilibrium between phases has been the subject of extensive studies in fields such as extraction or chroma to graphy. It has received only small attention in flow through the type of porous media encountered in oil production.5 For this reason a method was developed which makes it possible to study the movement of a solute as it is affected by rate, type of porous media, partition coefficient and carrier phase, but in the absence of segregation or fingering. The information obtained enables one to determine when the assumption of equilibrium can be made. Briefly, the method consists of (1) saturating the core with a mobile and an immobile phase, (2) injecting a slug made up of the same fluid as the mobile phase and a small concentration of mutually soluble solute, (3) measuring the lag and the peak height of the slug at arrival and (4) correlating these variables with fluid properties such as partition coefficient and mixing constants of the medium. PROPOSED MECHANISM The principles of chromatography are combined with the equation of longitudinal mixing to predict the velocity of a solute slug compared to the bulk velocity and the peak height of a slug.6-9 The equation so obtained is valid under equilibrium conditions only. Therefore, a comparison between experimental and predicted results will give a measure of departure from equilibrium. This work was done with either the oleic or the aqueous phase being immobile. For simplicity, the following development is based on the case where the oleic phase is immobile. However, the treatment is the same in either case.

Jan 1, 1966

By John Birkinbine

For two pears past the Warwick Furnace, at Pottstown, Pa., has attracted attention by the remarkable work done in it, and a statement giving details of its operation and the unexpectedly short biast of 1880 will be acceptable to every member who studies blastfurnace practice. There are so many interesting features in connection with this blast, and so touch to be learned from investigating it, that the results of &apos; thorough examination are offered to the Institute sans theories. In collecting the information, the courtesy of the various officers of the Warwick Iron Company was of material advantage, every facility for investigation being extended and an inspection of records being kindly permitted. In the following description these authoritative data are given in full where practicable, without making the paper too prolix, and the

Jan 1, 1881

By Herbert Clark Hoover, Lou Henry Hoover

THE third book has explained the various and manifold varieties of veins and stringers. This fourth book will deal with mining areas and the method of delimiting them, and will then pass on to the officials who are connected with mining affairs&apos;. Now the miner, if the vein he has uncovered is to his liking, first of all goes to the Bergmeister to request to be granted a right to mine, this official&apos;s special function and office being to adjudicate in respect of the mines. And so to the first man who has discovered the vein the Bergmeister awards the head meer, and to others the remaining meers, in the order in which each makes his application. The size of a meer is measured by fathoms, which for miners are reckoned at six feet each. The length, in fact, is that of a man&apos;s extended arms and hands measured across his chest ; but different peoples assign to it different lengths,

Jan 1, 1950

By E. A. Lucero, H. E. Robbins, T. H. Dudley

EL Salvador mine of Andes Copper Mining Co., E subsidiary of Anaconda Co., is in northern Chile about 18 miles north of Potrerillos, 7825 ft above sea level. Initial production is planned for the first half of 1959. Plant capacity will be 30,000 tpd, and there are 308,835,000 tons of proven ore reserves, averaging 1.49 pct Cu. The Inca adit is being driven as part of the mine-to-mill haulageway. Because of the overburden it is planned to mine the deposit by block caving. Ore will be dropped from upper gathering levels through ore passes to the Inca adit, through which it will be transported out of the mine to the primary crushing plant located a half mile from the portal.

Jan 3, 1958

By J. M. Cases

Study of the normal interaction between flotation collectors and the silicates through measurement of the electrokinetic potential carried out by the streaming potential and flotation recovery methods indicates that the interaction is wholly 07 partly of electrostatic origin. In some cases, it partly consists of the chemical affinity of the polar head of the collector for the active surface sites. Reagents composed of a polar head and a paraffinic chain and forming micelles in solution were used as flotation collectors. They are sodium dodecylsulfate (anionic collector) and dode-cylammonium chloride (cationic collector). The adsorption isotherms on biotite of alkylamine chloride having 10 to 18 carbon atoms in their chain all show a sharp change in slope relevant to the condensation of alkylammonium ions into bidimensional phase.1-1 Condensation is possible because of the relative homogeneity of the adsorbing surface and of the very strong lateral binding forces through Van der Waals type bonds in the adsorption layer. The different isotherms are seen to coincide when, instead of the equilibrium concentration, the under-saturation ?µ = kT In C/C, is plotted in abscissa, C representing the concentration of the solution with which the adsorbed layer is in equilibrium and C, the saturation concentration of micelles in solution or. critical micellar concentration. More particularly, the undersaturation ?,u1*, corresponding to a surface coverage 6 of 0.5, is equal to Since silicates immersed in aqueous solutions show a surface charge which is a function of pH, it is of primary importance to study the influence of this parameter on the adsorption of collector ions acting as Strong electrolytes in the pH range where they are utilized. The aim of this present paper is to determine by studying electrokinetic phenomena and recovery curves effectuated with a cationic collector and a anionic collector, the nature of the normal adsorbate-adsorbent interaction. Tables 1 and 2 sum up part of the results previously obtained&apos;H11 for the determination of the point of zero charge of the silicate studied by the streaming potential method. Throughout the remainder of this paper, the surface charge will be considered positive for all values of pH below the point

Jan 1, 1971

By N. R. Pillai, T. R. Anantharaman

THE striking alterations in the constitution and structure of cast A1-Si alloys brought about by addition of small quantities of some elements, particularly sodium, have been extensively investigated. Many theories&apos; have also been propounded to explain this so-called lLmodification" process, but their main concern has been more to throw light on the action of sodium than to arrive at general criteria underlying this interesting as well as intriguing phenomenon. Such theories have generally dealt with one or more, but not all, factors that seem to have a direct or indirect influence on the cast structure of A1-Si alloys, e.g.., formation of ternary eutectic, removal of oxides, hydroxides, and so forth, by fluxing, morphological changes in silicon, and inhibition of growth of silicon grains through colloidal action, compound formation, preferential adsorption, or reduction of surface tension. Kim and Heine2 were the first to study the modification of A1-Si alloys in a systematic as well as comprehensive manner and to list the important characteristics of a satisfactory modifier. According to them, an important property of the modifying element is its capacity to form a stable compound with silicon in the appropriate temperature range. Other subsidiary requirements are that the element should get adequately dispersed in the melt at the inoculating temperature and also must not form stable compounds with aluminum. The alkali elements, with the exception of lithium, fulfill these requirements most satisfactorily and have been shown to be successful modifiers by these workers. Sodium is the most effective of these and seems to be in a class by itself for various reasons noted by earlier investigators.37 None of the other elements tried by Kim and Heine, viz., Mg, Ca, Cd, Zn, In, Pb, P, As, Bi, S, and Se, showed any significant modifying action. We wish to report here briefly on substantial modifications in cast eutectic A1-Si alloys brought about by some V group elements, which do not comply with the Kim-Heine requirements. Aluminum and silicon used in the present work were indigenous and had purities of 99.8 and 99.5 pct, re-

Jan 1, 1969

CHARLES CATLETT, Staunton, Va. (communication to the Secretary*). -I hesitate to discuss in general terms a paper such as Mr. Wysor&apos;s, which bears evidence of so much careful and detailed investigation, yet it is the broad possibilities which his paper presents that are really attractive and his cautious conservatism may make us unappreciative of these possibilities. Mr. Wysor calls attention to the fact that the iron-ore mixture which he uses, carrying 0.28 per cent. of potash, is probably above the average. No doubt this is true, but on the other hand it may be very much less than the mixture at some blast furnaces or very much less than would be the case with special mixtures bearing the question of potash in mind. Unfortunately, iron ores are not ordinarily examined for potash, and with the ordinary analyst there is opportunity for very considerable error in the determination. The 10th Census gives 270 complete analyses of iron ore, on the accuracy of which we may rely. Of these, there are 21, or 8 per cent., that carry more potash than Mr. Wysor&apos;s mixture; 14 of these carry approximately twice as much, or more; eight carry approximately three times as much, or more; three carry approximately five times as much; one carries over seven times as much. It may be worth while to take some of the ores that are known to be high in potash and consider the possibilities in the light of Mr. Wysor&apos;s investigations.

Jan 5, 1917

By James J. Olson, Richard A. Dick

Blasting practices have shown a recent trend toward larger blastholes and larger burdens and spacings, although some operators, after reconsidering the situation have gone back to smaller blasthole sizes. The greater pull-down capabilities of larger drill rigs and the greater bearing strength of large diameter drill bits give penetration rates for large diameter blastholes approaching, and sometimes exceeding, penetration rates for smaller holes. In practically all cases, large diameter holes can be drilled more quickly and cheaply, based on volume of hole, than small diameter holes. The industry&apos;s shift to dry blasting agents and slurries, products which perform more dependably and efficiently in larger diameters, gives an additional advantage to larger boreholes.

Jan 3, 1972