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By I. R. Kramer

In his technical note entitled "Specimen Temperature During Electropolishing of Aluminum Crystals" Dr. Nakada 1 reported that the temperature of his aluminum specimen increased 65°C when it was polished electrolytically; he therefore concluded that the temperature of the specimens used in our work (Nakada's Refs. 4 and 5) similarly increased by this amount. From this he further concluded that the change in plastic-flow characteristics associated with the removal of the surface by electropolishing during deformation were due solely to a temperature effect. We believe that these conclusions are not justified. It is, of course, realized that the amount of the temperature increase is associated with the total heat transfer of the entire system, including the efficiency of the stirring action, heat flow through the grip on the specimen, and so forth. Of great importance is the type of electrolyte used for polishing. For example, in Dr. Nakada's experiment a methanol-perchloric acid solution was used. This solution has a relatively low conductivity and for the current densities of 0.3 amp per sq cm the electrical input appears to be 30 to 40 w. In our research a methanol-nitric acid solution was employed and for the size of specimen employed by Dr. Nakada the power never exceeded 7 w. There are major differences in his test apparatus which also appear to affect the temperature rise. In our case a steel specimen holder was used in order to provide a good heat sink and conduction path. The cathode was a coiled aluminum tube through which a coolant was passed to provide additional cooling capacity near the specimen. The stirrer was placed in a position to obtain maximum cooling efficiency. On the other hand Dr. Nakada used a teflon grip to support the specimen at one end only and a flat copper cathode, thus providing a much less efficient heat sink as compared with the metal grips used in our studies. The relationship between current density and the temperature increase for two sizes of aluminum crystals tested in our tensile apparatus is shown in Fig. 1. The temperature measurements were determined from a thermocouple spot-welded to the surface of the specimen. The thermocouple was protected from the acid by means of a thin film of stop-off lacquer which covered just the outer surface of the thermocouple junction. Whereas Dr. Nakada reported a time delay of 8 min to obtain thermal equilibrium, our temperature change occurred in less than 15 sec. This emphasizes the importance of the heat transfer in the entire system. However, readings were taken over a period in excess of 5 min to assure thermal equilibrium. The data given in Fig. 1 were also confirmed by determining the thermal expansion of the specimen in a sensitive creep apparatus. As may be seen, for the smaller specimen the increase in temperature is 8°C for a current density of 1.5 amp per sq in. The majority of our data on the effects of surface removal on the plastic behavior of aluminum were obtained at current-density values at or below this value. Above 1.5 amp per sq in. the temperature rise is uncertain; for under certain conditions, especially in the vicinity of 2 amp per sq in., the anode can become polarized and the current flow is erratic. This condition is easily recognized because wide fluctuations in the creep and stress-strain data make it virtually impossible to obtain reliable results, a condition which was always avoided in our work. The temperature increase for the larger specimen is less than that of the smaller specimens below a current density of 1.5 amp per sq in. At a current density of 2 amp per sq in. the temperature increased 13°C. The above temperature data are in accord with observations made during creep experiments. Using a transducer capable of detecting strain in the order of 10 -6, temperature changes in excess of 8°C were not detected when the current density was increased to as high a value as 1.5 amp per sq in. Finally we wish to point out that our experimental data cannot be explained solely in terms of a heat effect. For example in Fig. 1 of Ref. 2, the change in slope of Stage II as a function of the rate of re-

Jan 1, 1965

By William E. Ford, Edward Salisbury Dana

I. Anhydrous Chlorides, Bromides, Iodides; Fluorides. II. OxycMorides ; Oxyfluorides. III. Hydrous Chlorides; Hydrous Fluorides. The Fourth Class includes the haloids, that is, the compounds with the halogen elements, chlorine, bromine, iodine, and also the less closely related fluorine.

Jan 1, 1922

By H. W. Johnson

DURING part of the year 1932, conditions at the plant of the Inland Steel Co. made possible the collection of data on two of the variables of blast-furnace operation, between which we observed an interesting correlation. The variation in percentage of coke ash in the coke seemed to be reflected in the variations in percentage of silicon and sulfur present in the iron. This subject is of particular interest during this period of low production because of its effect on quality and cost of pig iron. The consumers of pig iron are now more exacting in their requirements. Formerly 0.050 per cent sulfur was considered satisfactory; now many foundries and steel plants insist on iron under 0.030 per cent sulfur and expect it to average 0.025 per cent sulfur. To attempt to produce iron so low in sulfur and still have reasonably good furnace operation means that everything possible must be done to minimize all variations. This subject is also directly connected with the cost of producing iron. A blast furnace operates most economically and efficiently in rather narrow limits and so any variable that has range enough to disturb regular operation must be moderated. The importance of regularity is accepted and the methods followed to eliminate variations in materials such as coke and iron ore are recognized as indispensable. Uniformity of Ore and Variations in Coke Ash The delivering of uniform cargoes of well mixed ore to the blast furnace involves much handling and expense, but it is accepted that the trouble and expenditure are justified. After the ore reaches the dock, further mixing is assured by spreading ore in thin layers, preventing segregation by keeping piles level, variations in digging, and the use of several bins for one ore. And finally, the fact that the furnace burden generally contains three or more ores, together with several miscellaneous materials, eliminates the possibility of ill effects due to variations in any one. Thus, much effort is made to insure a uniform ore. But a variation in the percentage of silicon in ore is less detrimental than a variation in the percentage of ash in coke. The former affects

Jan 1, 1933

By J. M. Floyd

The theory, construction and applications of oxygen sensors employing high-temperature electro- chemical cells with solid electrolytes are briefly reviewed. The application of disposable probes to measurement of the oxygen potential in matte and slag baths in tin, copper, and nickel smelting operations is described. Examples discussed include end-point determination in smelting and slag-cleaning operations, pilot-scale investigations of process chemistry to assist in the development of smelting strategies, and measurements in operating smelters to improve the efficiency of operation.

Jan 1, 1984

Jan 1, 1941

By John Tabor, R. B. Spivey

INTRODUCTION Shafts have been sunk in a number of ways. By and large, however, most have been sunk by drill, blast, muck, and slip form methods. Most methods have provided satisfactory means of completion. The major drawbacks to the conventional methods have been: (1) un- reliable cost estimates for completion; (2) unreliable rates of progress; and (3) unreliable integrity of the shaft lining. Recently , engineering design studies have been done that strongly indicate, that, by the use of existing proven technology, shafts can be completed faster, more cheaply, safer, and with a better lining that has been possible using conventional methods. THE METHOD The alternate method utilizes the techniques of big hole drilling, shield excavator tunnelling, and pre-cast concrete lining. Big Hole Drilling - Drilled shafts have been completed for several years and I don't intend to address the technology, only to point out the use of drilled shafts is an alternate method of shaft sinking. Ideally, in a multi-shaft mine, the first shaft would be blind bored and cased to a size, whereby it can handle the muck from the excavation of subsequent shafts. It should be an 8' to 10' completed diameter. The cost of such a shaft in sedimentary formations compares favorably with a conventional shaft. However, it is much faster. For additional shafts, the role of the drill is to complete small holes (3' to 4') to the desired horizon. This is merely a hole to allow slashing to a larger size with easier muck removal from an underground drift connected to the previously drilled shaft. The smaller holes, just as the larger one, should be cased and grouted into place so as to assure a smooth open hole. SHIELD EXCAVATOR Theory and History - Tunnelling Shields have been in common use for several decades, and steam powered shields were used in England over 100 years ago. The purpose of the shield is to provide temporary ground support, protect personnel during operation, and to house the excavating equipment. The excavating equipment approach has varied from attempts at a continuous or semi-continuous boring machine, the tunnel mole, to a mechanical or hydraulic digging arm. The shield may or may not be an active digging element. If not active, the boring tool or cutter is advanced ahead of the shield to full diameter and then the shield is moved up to the cutter, or the shield advances along with the cutter. If active, the cutter opens a conical free face, and the shield is either jacked forward so that the leading edge spalls rock to the free face or poling plates are thrust forward to spall to the free face. In either approach, various methods of muck removal are incorporated into the shield. These may be gathering arms, conveyors, or with moles, hydraulic transport, where the cuttings are sufficiently fine. The efficiency of the muck removal system is critical as excavation is rapid and the system could easily become muck-bound. Application to Shaft Sinking- Technically, the use of a shield to sink vertical shafts is no different than a tunnelling operation. It is, in fact, less complex in most respects. Muck and water removal are difficult in a blind-driven shaft. However, where an underground opening is available for handling muck and water, rapid shield sinking is possible, using a pilot hole for muck and water to fall through and be removed from below. The Tabor Mining Shield is basically a caisson approach, whereby, the ground is only seen at the face or bottom. It does have hydraulic jacks to force it downward and has segmented cutting edges which allows forepoling ahead of the shield. The hydraulic excavator allows mining in the center of the face around the previously drilled hole with the forepoling segments slabbing to this free face. First, the drilled hole is cased and grouted. The machine is a tube with an excavator. The work cycle is as follows: (1) The casing and grout are cut at predetermined intervals by shaped charges. (2) The casing is crushed by the excavator, removed from the hole and hoisted to the surface. (3) The excavator then rips out a face around the hole by digging the formation in tension and breaking the pieces

Jan 1, 1982

By A. K. Sinha, K. M. Sinha

Several studies concluded by various agencies (Coal Outlook, 1982; Malhotra, 1977) indicate that both the national and international markets for utility coal, which have been growing in recent years due to the uncertainties in petroleum supplies, will continue to grow in the foreseeable future. The areas where the Gemand for utility coal is projected to increase sub- stantially lie close to the midwestern coal fields, in the southeastern US, and in western Europe. Illinois has all the elements necessary to become an important exporter of thermal coal (Library of Con- gress, 1981) provided the coal is desulfurized to meet the environmental restrictions. Because of its high energy content, Illinois Basin coal, if desulfurized, has great potential for competing in the utility markets both nationally and internationally. Sulfur in coal occurs in organic and inorganic forms. The inorganic sulfur in Illinois coal is almost exclusively pyrite. The pyrite can be liberated by grinding and removed from the coal by such techniques as froth flotation. The Illinois Basin coals reportedly contain (Gluskoter and Simon, 1968) an average of 3.57% sulfur. Out of this, 2.06% is pyritic, 0.08% is sulfate, and 1.46% is organic sulfur.

Jan 1, 1986

The following list contains the names of members whose death notices have been printed in MINING AND MDTALLURY from April 5. 1944 through March 15. 1945, Biographical sketches published in MINING AND METALLURGY are indicated in the last two columns. [ ]

Jan 1, 1946

Jan 1, 1959

DISCUSSION, T. B. King and H. H. Kellogg, Chairmen Philipp Gross (Fulmer Research Institute Ltd., Stoke Poges, England)—As pointed out by the author, any better agreement between experimental and calculated

Jan 1, 1956

References are in all cases to the earliest known editions. In the few cases where the first edition has been unavailable for consultation, the particular one studied is indicated. English translations are included when known, but not others. [ ]

Jan 1, 1942

By E. Werchowsky

FOR over four years, since the revolution of 1917, Russia has been cut off from the Western world. Political and general economical reforms have attracted the attention of the public and business world, but mining men have had no information as to the situation in their branch of industry, as various articles which have appeared in the European and American press gave little information as to actual conditions in our country. When the Soviet system of government was estab-lished and private ownership abolished, it affected the FIG. 1.-ORGANIZATION OF THE COUNCIL OF MINES. mining industry very little at first. The power of the Soviets did not affect the Ural provinces nor Ukraine or Asiatic Russia (Siberia, Turkestan, etc.) during 1918 and 1919, and, as is well known, the mineral wealth of the republic lies within those boundaries. In the Ural Mountains are copper, gold, and platinum; in Siberia, silver, lead, zinc, and gold, and the coal deposits in Koushetz district; in Ukraine, there are the coal fields of Donetz and the iron mines of Krivvy Rog, and silver, lead, zinc, copper, oil, etc. in the Cauca-sus. The mineral resources of Central Russia are the coal fields of Moscow (low-grade and brown coal), turf deposits, iron mines in Tula and Kalonga provinces, and quarries of granite and other building materials.

Jan 8, 1922

By Bob J. Rawicki

TYPES OF WET DUST COLLECTORS Basically, there are two types of wettype dust collectors. One is mechanical, incorporating pumps, motors, fans, sprays, filters, or flooded beds. These come in many forms, but their operating principle is basically the same. The screen or flooded bed is wetted by a series of sprays. Polluted air is drawn in through a fan; here the dust particles impinge on the screen and are flushed off into a settlement tank. The air then passes through spray eliminators to the atmosphere. A great deal of time and money has been spent developing this type of collector. In laboratory tests where clean water at constant pressure, air at constant volume, and dust at low but constant mass to volume were applied, these collectors gave high percentage dust collection efficiencies. Theoretically and technically, they are very good. In practice, however, under rugged mining conditions where there are no constants, and dust load, particle size, water pressure, and volume of air vary with time, their efficiency varies dramatically. Some of the most common problems are: 1. clogging of screens 2. blocking of nozzles 3. replacement. of damaged pump stators Any of the above result in loss of air flow and dust collection efficiency. Generally, there are so many mechanical moving parts, something is always breaking down. This type of collector is very expensive in parts and labor to maintain. The second type of dust collector, which I personally developed, with the help of the British National Coal Board of Great Britain, has none of the above mentioned problems and it works on a completely different principle. My collector, the Mark III Precipitaire Wet-Type Dust Collector, (an improved version of previously successful models) has no internal moving parts, no flooded beds, screens, spray nozzles, etc. It is highly efficient - 99.8% efficiency on total collected dust and 97% on respirable dust. The pressure drop through the collector is constant, hence, air flow remains constant. There is no maintenance expenditure, be it labor or parts. The only maintenance that there is, is desludging. This, of course, varies with the dust load. With a low dust load, desludqinq may only be required every 4 weeks, but this is a very simple operation that can be handled by unskilled men and it takes only a very short time. My collector is powered by a ventilation fan that is placed on the clean air side for a longer fan and motor life. Dust is extracted solely by water action. The collector's operating principle is: Dust laden air is drawn in along ducting into a tapered scrubber section, shaped to create a self-induced curtain of water. This action washes the dust particles from the air and the collected dust settles into the bottom of the tank. Cleaned air is then exhausted via a series of spray eliminators where it is completely dried and on into the atmosphere. These collectors have been sold in Great Britain, to the National Coal Board, and throughout Europe. They have been working very well for many years now. GENERAL APPLICATIONS Dust is very dangerous; silicosis and black lung kill and disable many workers each year. Many of the mine explosions can be attributed to coal dust. By the use and application of dust collectors, these deaths and disasters can be avoided. There really is no excuse. However good and efficient a dust collector may be, it's positioning and installation arrangement is critical. The collector may remove 99% of dust supplied to it, but it takes the skill and experience of a dust control engineer to design and fit ducting, hoods, etc. to remove polluted air at source and deliver it to the collector. In some cases this is very simple; in the case of longwall machines, it is very difficult. In general, dust collectors should be used to collect dust at every point of dust generation. I have noted a great reliance on dilution as a means of dust control. I personally think this is a dangerous and unreliable method. As mines become deeper and the use of larger and more productive equipment becomes more common, reliance on dilution will be impossible and dust collectors will be essential.

Jan 1, 1982

By C. G. McLachlan

Laboratory flotation tests carried out on massive sulphide ores may not be reproduced in plant practice, and when this occurs the discrepancy can be the result of differences between laboratory and plant grinding. Results of parallel flotation tests are given to support this contention, and data show how tailing losses are affected in corresponding size zones.

Jan 4, 1951

By J. J. Gilman

Examination showed that characteristic cleavage step patterns are observed on the cleavage surfaces of undeformed, slipped, bent, twinned, compressed, and indented zinc crystals; and the effect of temperature is discussed. Dimples were seen to produce cleavage steps in a treelike pattern in otherwise undeformed crystals. The steps seem to originate when cracks intersect screw dislocations. IT has been known for a long time that the path of fracture in polycrystals may be discontinuous (see Jaffe, Reed, and Mannl for review). Recently, Kies, Sullivan, and Irwin2 have proposed, and given evidence, that crack propagation is discontinuous within individual crystals as well. Other evidence has been given by Low.' When discontinuous cracks within a crystal join together to make a macrocrack, the lamellae between each set of two cracks are torn somewhere, forming small cliffs. These cliffs appear as lines when the cleavage surface is observed microscopically.4,5 The lines have been called vein, tree, and riverlike markings by various authors, and they have sometimes been mistaken for fissures. The descriptive term cleavage steps is used in this paper. Cleavage steps vary in height over a wide range of values, from molecular dimensionsG to lor. and larger. Kies, Sullivan, and Irwin,2 as well as George,' have shown that the gross cleavage step patterns for plastics, polycrystalline metals, and for mono-crystals are sometimes similar. Thus, they depend mostly on the mechanical variables that prevail during cleavage and are relatively insensitive to the structure of the material. For example, parabolic markings2,7,8 sometimes result when cracks open up ahead of, and not coplanar with, the main crack front. If the advance crack has the same velocity as the main crack, their intersection line is a parabola, otherwise it is a hyperbola or an ellipse. The patterns are strongly affected by differences in crack velocities. This results in chevron patterns which point to the place of origin of the main crack. It is the purpose of this paper to demonstrate the existence of a mechanism of cleavage step formation which is a continuous rather than a discontinuous process. Also, certain characteristic step patterns are described, and the strong effect of temperature is shown. The specimens were zinc monocrystals (grown from 99.999+ pct pure metal). These were cleaved at room temperature and at — 196°C. Results and Discussion Cleavage step patterns are highly variable from point to point on a given specimen, as well as from one specimen to another. Although the patterns shown in the photographs are typical, they have been selected for graphic illustration. Figs. la and lb compare undeformed crystals that were cleaved at —196 °C and room temperature, respectively. Cleavage at room temperature (Fig. lb) resulted in a higher density of high steps (dark black lines) and enhanced the visibility of the fine background markings. Deformation by simple slip caused no marked change in the step patterns until the glide strain reached about 1.0. But, as Fig. lc shows, the density of high cleavage steps was greatly increased by large glide strains. Corrugations lying perpendicular to the slip direction may also be seen in Fig. lc. These are caused by deformation bands. The cleavage resistance of the crystal of Fig. lc was very high compared to undeformed crystals (estimated by the force on a needle required for cleavage). Striking and varied cleavage step patterns were observed on bent crystals. Two characteristic patterns that were observed on crystals bent at 25°C, and cleaved by reverse bending at —196°C, are shown in Figs. 2a and 2b. The first, Fig. 2a, consists of V-shaped lines similar to the parabolas of other materials2,7 Fig. 2b shows a pattern that is the equivalent of Fig. la, consisting of faint background lines with a few higher step markings. Cleavage of bent crystals at room temperature resulted in Figs. 2c and 2d. Now, the cleavage step lines show a strong tendency to follow one of two perpendicular paths. In Fig. 2c (bent once), many of the cleavage step components that lie parallel to the bend axis are assembled into irregular lines. In Fig. 2d (bent twice), the cleavage steps again tend to consist of two perpendicular components, but neither of the components is assembled into lines. Also, the step density is higher.

Jan 1, 1956

By W. D. MOTTER

THE following brief description of the status of operations of the Chile Exploration Co. at Chuquicamata, Chile; and of the plant as it exists today, points out the-great progress that has been made since the initiation of prospect drilling in 1912. During the 11 years which have elapsed since then, a group of small mines, eking out a 'precarious existence, has been consolidated into one large operating property,, taking high rank among the world's producers of copper. After a drilling campaign followed by a construction period, the plant first started operations in 1915. Since then production has been gradually increased, as world conditions permitted, until the present status has been reached.

Jan 1, 1924

By Robert W. Coughlin

Pulverized coal has been introduced at the anode where it is oxidized during the electrowinning of metals from their aqueous solutions This substitutes an electrochemical reaction between coal and water for the usual oxygen-evolving half-cell reaction at the anode, with the result that overall cell potential is significantly lowered and the consumption of electrical energy is correspondingly reduced. Experimental results are reported for electrowinning copper as an example of this novel modification of the electrowinning process in this example, the use of coal lowered the consumption of electricity by two-thirds of the requirement of the conventional process When the potential electrical energy of the coal consumed is considered the new, coal-assisted process consumes about 45% less energy, and the energy costs (combined costs of coal and electricity) are reduced by about 50%.

Jan 1, 1981

By C. A. Heiland

WITH seventeen papers submitted. and thirteen presented in three sessions, the geophysicists had a most successful meeting at New York in February. The first paper on Monday morning dealt with the location of a diabase dike near Chapel Hill, N. C., by magnetic and resistivity methods. The magnetic indications were pronounced directly over the dike. whereas the anomalies of apparent resistivity were less distinct and displaced away from the dike. In the second paper, Professor Keys reported on the results obtained with four different methods of depth calculation on known portions of the Falconbridge

Jan 1, 1937

By Geo. W. Bain

PRODUCERS of building stone have had to seek new and attractive uses for their output to supplement the diminished orders for standard products. Lunar is the direct result of the need of new outlets for marble and is. probably the most ingenious and attractive type to reach the market in a quarter of a century. It is a highly translucent stone which retains the same glistening sparkle in transmitted light that marble exhibits by incident rays. This sparkle sets it apart entirely from translucencies made of glass or even onyx, alabaster, and the distinctive exceedingly fine textured calcite marbles produced in Alabama and quarried formerly in northern Vermont and Quebec.

Jan 1, 1936

By A. Dubnie

Three periods of major activity have led to the development of the present mineral industry in northern Canada. At the turn of the century, placer gold was discovered in the Yukon Territory and production has been continued to the present day. In the late 1920's and early 1930's, vigorous aircraft- aided exploration resulted in the discovery and production of radium at Port Radium on the southern shore of Great Bear Lake and of gold at Yellowknife on the north shore of Great Slave Lake. During this period, oil was discovered at Norman Wells. Present mineral production is today largely derived from deposits which have been developed in the 1950's. Among these are the re-opened deposits of United Keno Hill, uranium deposits at Uranium City, natural gas resources from the Peace River gas area, nickel-copper deposits at Lynn Lake and Rankin Inlet, and the Cassiar Asbestos deposits at McDame Mountain.

Jan 5, 1961