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By H. B. Charmbury, D. R. Mitchell

Everyone in the coal industry from top management to the preparation engineer is vitally interterested in recovering as much salable coal as possible from the run-of-mine product. Coal losses from a preparation plant occur in the solid refuse material being discharged from the plant and in the bleed-off slurry from the water circuit. The refuse is generally hauled from the plant in solid form by trucks, conveyors, or aerial trams to the refuse or culm banks or it may be crushed and transported by hydraulic methods to refuse ponds or dams. The loss of coal in refuse material and the extent of this problem has been covered in another paver.' The loss of salable coal in the plant bleed-off slurry is one of the water circuit problems in coal preparation plants. Slurries originate at various places in the processing circuits and are usually disposed of by transportation to waste ponds known as slurry ponds. Even though the combustible material discharged as slurry and refuse from the plant is labeled a loss, the loss must only be considered temporary. There is a tendency at the present time to examine refuse and slurry losses and to reprocess these materials to recover valuable coal. Slurries from eight bituminous coal preparation plants in central and western Pennsylvania have been sampled and examined to determine the amount of recoverable coal in each. Examinations of the samples were made to determine the tons per hour of solids and the gallons per minute of water in the slurry; the size, ash, and sulfur analyses of the solids; and the sink-float characteristics of the larger solids. The extreme fines (—325 mesh material) from one of the samples has been examined further to determine the micron size fractions as well as the ash and sulfur content of the micron sizes. Collection of the Samples: Field trips were made to each of the plants where samples were obtained and discussions held with the preparation engineer prior to sampling. The flowsheet of the plant operation was studied and a time-period selected to obtain a representative sample. At least 20 1-gal samples of total plant bleed-off suspensions were collected at each plant in increments over designated periods belived to be typical of the plant flow Three of the samples were obtained from plants in the Pittsburgh area. Each plant supplied information on the capacity, operating time, type of cleaning equipment used, water and material balances, and auxiliary equipment. From the time required to collect given amounts of slurry and from the amount of solids in the slurry, total solids discharges from the plant were calculated and compared with the plant flow. Ash and sulfur analyses of the total solids were also checked, at some plants, with company figures. In all cases where checks could be made there was reasonable agreement between company figures and those reported here. Analysis of the Slurries: Representative fractions of properly agitated samples were examined in the laboratory to determine the specific gravities of the slurries. The solids and water were separated by filtration to check the weight of each so that the percent of solids in the pulp could be determined. From the resulting data, presented in Table I, it may be seen that the percent solids in the slurries ranges from 2.8 to 39.0 and the amount of solids from 2.61 to 45.61 tph. Size Analysis of Solids: Representative fractions of the slurries were permitted to settle and the clear water was removed by siphoning. The solids were then wet-screened at 28, 35, 48, 65, 100, 150, 200 and 325 mesh. Results of the size analyses are presented in Table 11. These results indicate the extreme variation of sizes and in most cases the degree of fineness of the solids. The amount of —325 mesh ranges from 22.5 to 84.5 pct and the amount of+200 mesh from 8.3 to 69.1 pct.

Jan 1, 1961

By H. L. Miaw, A. M. Gaudin, D. W. Fuerstenau

A quantitative method for evaluating density of slime coatings has been developed and applied to formation of iron oxide slime coatings on quartz and on corundum. Slime coating density is related to flotation recovery and to properties of the electrical double layer at mineral surfaces. IN spite of considerable study, the nature of slime coatings in flotation is still not completely understood. However, phenomena that control floc-culation and dispersion of colloidal systems are now interpreted in terms of electrical double layers.",' Colloids will flocculate even though the particles carry the same charge, but when two dispersed colloids of opposite charge are mixed. flocculation ensues even more rapidly. Analogous phenomena seem responsible for slime coating on minerals in flotation systems. To shed new light on the issue it was considered desirable to devise a tool that would measure slime coatings. The usual method has been to examine photographs of presumably representative surfaces, after. an intervening washing in running water. But such an examination is non-quantitative, and the changes in chemical environment represented by the washing may have removed the slime coatings that existed during flotation. To provide the possibility for a correlation with electrical double layer phenomena, the experiments were made with quartz, corundum, and iron oxide, for which elec-trokinetic data are available.'-" Since the properties of the electrical double layers of these oxides depend on the pH of the solution, pH will be the most important variable. Furthermore, because the zero point of charge for silica, iron oxide, and alumina occurs at pH 3.7, 8, and 9.5, respectively, the relative charge on the slime and mineral can be changed over wide ranges. Because of its practical importance in quartz flotation, iron oxide powder was chosen as the slime. Also, its uniform composition, contrasting color, and ease of analysis make experimentation simple. In this investigation, correlation was sought between the effect on flotation recovery of slime addition and slime coating density. Materials and Methods Details are available in a thesis by Miaw." The quartz was selected from pure Brazilian crystalline quartz, crushed, sized (65/150 mesh) acid-cleaned, washed, and stored in conductivity water. The corundum (synthetic alumina of high purity prepared by Linde Co., Chicago) was crushed, sized (65/100 mesh) deslimed, boiled in nitric acid, washed, and stored in conductivity water. The iron oxide slime, reagent-grade ferric oxide (—400 mesh) from Allied Chemical & Dye Corp., was heated to 160°C, cooled, and stored in a vacuum desiccator. In the electron microscope the slime particles appeared to be about 0.3µ in size, but their large specific surface (87,900 cm per g, by gas-adsorption method, using krypton) suggests that the actual particles are smaller than 0.3r. Had they been perfect nonporous spheres, they would have had a diameter of 0.13µ.

Jan 1, 1959

By AIME AIME

SECOND only to the February Annual Meeting of the Institute are the Regional and Divisional meetings held in the fall of each year. Six such gatherings are scheduled in the next the months, with something likely to interest every member of the Institute. A brief résumé of the programs follows. Regional Meeting Vancouver T HE regional meeting of the Institute will be held at Vancouver, Sept. 13 to 20, in conjunction with the annual western meeting of the Canadian Institute of Mining and Metallurgy. The pro gram appeared on page 350 of MINING AND METALLURGY for July and-proof of careful preparation-a month later re- quires no correction and little elaboration. On the technical side there are few changes. A new item on the Wednesday morning program is the paper, "Investigation of Residential-type Stokers," by H. F. Yancey, supervising engineer, Northwest Experiment Station. U. S. Bureau of Mines, Seattle. As to entertainment the meeting is taking on some most pleasurable aspects. Two notable excursions have been arranged.

Jan 1, 1937

By AIME AIME

THE Iron and Steel and Institute of Metals Divisions will meet jointly at the Statler Hotel, Detroit, Oct. 4 and 5, during the Metal Congress, Oct. 2-6. The Wire Association, the American Welding Society and the American Society for Steel Treating, together with the two Divisions of the Institute, constitute the Congress this year, and each body offers an interesting technical program. The National Metal Exposition will, as usual, be held concurrently. Visiting metallurgists will find themselves engaged in a bit of research not listed in the program-a time study of how best to exploit in a few days both the Congress and all that the place of meeting has to offer. For Detroit, the beautiful "City of the Straits," is third in rank industrially in the United States, and its great manufacturing plants offer much of metallurgical interest. This is especially true of the automobile plants which will be open to members of the various societies during the week of the Congress.

Jan 1, 1933

By E. Northcott, I. M. LeBaron

Before describing the electrostatic processing of feldspar, it might be well to review some of the basic definitions and terminology of feldspars. The feldspar minerals constitute a group of alumino-silicates of potassium, sodium, and calcium. Barium feldspar sometimes occurs naturally but is very rare. Hardness varies between 6 and 6.5 and specific gravity between 2.5 and 2.8. Color is generally white or pale shades of red, yellow, or green. The approximate chemical composition of the principal feldspars is given in Table I. The albite (sodium aluminum silicate) and an-

Jan 1, 1959

By Sherwin F. Kelly

One of the most succinct and illuminating perspectives of the field of geophysical exploration to appear in recent years is an article by E. A. Eckhardt, in the magazine Geophysics for October 1949. Although his review covers the year 1948, many of the data presented are apropos to a review of 1949, and form a pertinent background for a consideration of current progress. He presents charts of the world-wide distribution of gravimeter and seismograph activity in oil exploration, which show that surveys in the United States accounted for practically 68%; of all gravity work and 80%; of all seismic activity. Canada ranked second, with a proportion of roughly 6%, in each case; South America accounted for about the same percentage of seismic work, and double that amount for gravity surveys. Within the United States, Texas and Louisiana were the scenes of the greatest activity, both claiming about 60% of all surveys by each method.

Jan 1, 1950

By AIME AIME

DOUBT in anyone's mind that this is the age of metals, industrially speaking, could easily have been dispelled by attending the National Metal Congress in Chicago, Sept. 22 to 26. Iron, copper and aluminum; zinc, lead and nickel, often alloyed with each other or with some of a dozen minor metals, make the materials without which the modern world could not run. Science, pure and applied, is doing marvels in finding new mixtures, new alloys to meet new needs; in developing new means of rolling, fabricating, casting and welding metals cheaply-and effectively. These and related matters were the subject of 100 papers presented at 33 seperate sessions of the organizations that participated in the congress.

Jan 1, 1930

By Nelson P. Hulst

COMMITTEES. DULUTH.-Nelson P. Hulst, Chairman; J. B. Adams, W. C. Agnew, M. H. Alworth, C. W. Andrews, R. Angst, William R. Appleby, C. E. Bailey, G. G. Barnum, E. F. Bradt, Mylie Bunnell, George L. Cheesebrough, Peter Christen¬sen, F. A. Cokefair, T. F. Cole, C. A. Congdon, N. Cowling, George H. Crosby, M. D. Cullum, C. d'Autremont, Jr., H. L. Dresser, C. T. Fairbairn. Walter Fitch, F. L. Gilbert, J. T. Hale, G. G. Hartley, E. B. Hawkins, M. S. Hawkins, J. H. Hearding, Louis Hill, L. J. Hopkins, F. E. House, J. C. Hunter, 0. D. Kinney, J. W. Kreitter, E. J. Longyear, Alexander McDougal, W. A. McGonagle, A. M. Marshall, W. N. Merriam, T. D. Merrill, John Millan, P. Mitchell, Clarence Moore, Hon. Page Morris, C. H. Munger, Henry Nolte, W. J. Olcott, A. L. Ordean, Thomas Owens, F. A. Patrick, H. M. Peyton; D. M. Philbin, Capt. Charles Potter (U. S. A.), L. W. Powell, Harry Roberts, Louis Rouchleau, George A. St. Clair, J. U. Sebenius, Joseph Sellwood, Amos Shepherd, W. B. Silvey, George Spencer, George C. Stone, H. B. Sturtevant, George D. Swift, Kirby Thomas, C. D. Thompson, A. D. Thomson, G. A. Tomlinson, Charles Trezona, R. R. Trezona, Maj. J. H. Upham, Charles Van Barneveld, W. W. Walker, J. L. Washburn, A. C. Weirs, H. J. Wessinger, A. B. Wolvin, Dwight E. Woodbridge. HOUGHTON.-W. E. Parnall, Chairman; W. D. Calverley, Secretary; W. B. Anderson, L. S. Austin, Jacob Baer, William Bath, F. J. Bawden., Simon Beahan, John Been, C. H. Benedict, Walter Bloomfield, S. H. Brady, Samuel Brady, Henry Brett, A. L. Burgan, F. I. Cairns, W. H. Cake, Arthur L. Carnahan, William Carpenter, Phillip Carroll, John J. Case, T. L. Chadbourne, W. A. Childs, B. F. Chynoweth, Captain James Chynoweth, H. P. Clausen, F. G. Coggin, H. D. Conant, J. B. Cooper, J. R. Cooper, John Cuddihy, Thomas Cummings, Robert Davidson, J. B. Dee, J. R. Dee, T. S. Dee, Theodore Dengler, M. M. Dennis, Captain Thomas Dennis,. F. W. Denton, A. D. Edwards, R. M. Edwards, C. S. Fales, Daniel Fisher, Henry Fisher, James Fisher, A. L. Floeter, Frank H. Getchell, M. C. Getchell, W. M. Gibson, W. M. Gilliland, James G. Glanville, George Goodale, H. S. Goodell, A. R. Gray, Edward Grierson, Homer Guck, H. D. Haddock, Captain Josiah Hall, John L. Harris, Captain S. B. Har¬ris, Enos Harrold, F. William Hartmann, George L. Heath, C. M. Hoar, Thomas Hoatson, 0. P. Hood, Captain Thomas Hooper, Captain Joshua D. Husking, Dr. L. L. Hubbard, Arno Jaelinig, E. D. Johnson, G. A. Koenig, Edward Koepel, C. H. Krause, R. H. Leach, A. W. Leonard, James MacNaughton, Edward McCormick, Thomas McDonald, R. T. McKeever, F. W. McNair, James McRae, John Mackey, John C. Mann, Major G. A. Marr, Captain Thomas Maslin, Harry Mercer, James Merton, Michael Messner, William F. Miller, Captain J. Milligan, Dr. J. W. Moore, Charles H. Moss, H. F. Nickerson, Charles L. Noetzel, P. H. Paine, John Penrose, Captain John Pentecost, Graham Pope, R. C. Pryor, James Ramsay, J. T. Reeder, Allen F. Rees, J. H. Rice, W. G. Rice, James

Jan 1, 1905

By B. H. Caudle, L. G. Loncarie

Pilot flooding is one method of evaluating a proposed secondary recovery project. However, the amount and rate of oil recovery from an unconfined pilot area is not usually the same as from an equal area in a large-scale flood. This is true because fluids are free to move across the boundary of a pilot area. The result is that some of the oil produced in a pilot flood may come from outside the designated area and some of the displaced oil may leave the pilot area completely. This paper presents the results of fluid-flow model studies on a five-spot pilot flood. Mobility ratios between 0.1 and to have been studied. The effects of changing the ratio of injection to withdrawal rates are shown. INTRODUCTION A small-scale field test, or pilot flood, is an accepted method for evaluating the applicability of a secondary recovery operation and the economic potential of that operation for a reservoir. The pilot flood is carried on in the same manner, with the same injected materials and at the same pressures as would be used were the secondary recovery program to be expanded to a larger area of the field or to the entire field. If the reservoir fluid and reservoir rock properties are the same in the pilot area as in the rest of the reservoir, the production, injection and other pertinent data associated with the pilot test will represent and measure what should be expected from a full-scale development of this secondary recovery program. There is one major exception which, unfortunately, has been overlooked by many and which has been awaiting quantitative definition. This is the sweep-out pattern the reservoir engineer must use in interpreting the pilot flood and in extrapolating it to the full-scale development. The sweep-out area in a pilot flood is not contained within the five-spot pattern. Further, there is oil flow into and/or out of the five-spot during a pilot test. Thus, production data from pilots must be interpreted with this different flow system and sweep pattern in mind. We have studied the sweep-out pattern that will exist for some conditions of operation of pilot flooding a single five-spot (four injection wells and one producer). In our study, reported here, we have assumed that the reservoir is relatively homogeneous and of uniform thickness in the pilot area. The results of this study en-able the engineer to predict the recovery, injection requirements and project life for a full-scale operation from the pilot flooding data. The effects of various injection to withdrawal-rate ratios and mobility ratios in a relatively gas-free (10 per cent pore volume or less) system are shown. Experimental Method The technique used in this study was the same as that for the X-ray shadowgraph studies of sweep-out pattern efficiencies.' The model of the pilot and surrounding area was made from a uniform packing of round-grain sand consolidated with an epoxy resin. Fig. 1 shows the relation between the model and the pilot area. Only one-eighth of the pilot area had to be represented in the model because we assumed equal injec-

By N. A. D. Parlee, M. M. A. El-Naggar, G. 8. Horsley

The apparatus was of a modified Sieverts type1&apos;2 with a reaction tube designed to function also as the cell component of an oxygen pressure gage. The reaction tube assembly is shown in Fig. 1 and described in Table I. The main body is a 1-in.-OD 15 mol pct calcia-stabilized zirconia tube. The ground-glass joint, g, the male part of which carried a prism for optical pyrometer use, was connected to the remainder of the Sieverts apparatus. The calibration of the cell (at its 1000°K operating temperature) for internal oxygen pressures (PO2in) in the range 0.2 to 10 9 atm was made against internal air pressures measured by mercury manometer and McLeod gage. At very low po2in values down to l<Tn atm the performance was checked by comparing pQ calculated from electromotive force measurement when the apparatus was filled with a) pure CO gas and b) a CO-CO2 mixture of the ratio CO-CO2 = 1:0.398, with Po, values calculated from the equilibrium constants of the following reactions at 1000°K:

Jan 1, 1968

By F. C. Canney

Geochemical prospecting seeks hidden mineral deposits by sampling for variations in the chemical composition of naturally occurring materials. Usually the samples are of soils and other products of weathering and erosion-surface materials extremely susceptible to contamination by human activities. Except when a survey is conducted well away from populated areas, contamination is an ever-present hazard. The program&apos;s success is particularly endangered when the contaminants are the elements sought; if these occur erratically throughout an area, spurious anomalies completely unrelated to mineralized areas can be formed. Evenly distributed contamination can be dangerous too, if it raises the background to such a level that true anomalies can no longer be easily detected. Suppose, for ex- ample, that in an area where the lead background is 20 parts per million the soil over a lead vein contains 1000 ppm of lead. Here the contrast would be 50 to 1, which is very satisfactory for geochemical surveying. Now if 1000 ppm of lead from some source were added evenly to the soil in this area, the contrast would be reduced to about 2 to 1, and the anomaly would no longer be readily detectable because a threshold of significance twice the value of the background is the minimum generally used for interpreting geochemical data.

Jan 2, 1959

By J. J. Jonas, G. Gagnon

SHG zinc was extruded in the temperature range 110" to 350°C and the strain rate range 0.05 to 5 sec-1 The strain rate/flow stress/temperature results were analyzed using a power sinh stress relationship. When temperature changes due to the heat of deformation and to heat losses are neglected, the exponent of the sinh function of the stress is 5.6, and the apparent activation energy of deformation is 28 kcal per mole. When these changes are taken into account, the exponent decreases to 4.7 and the activation energy to 23 + 2 kcal per mole. The corrected stress exponent and activation energy are in very good agreement with published values obtained from creep experiments, and suggest that the hot extrusion of zinc is controlled by a mechanism involving self-diffusion. When the extrusion and creep data are compared using a Zener-Hollomon parameter and either a sinh or an exponential stress term, an appreciable offset is observed, which may be due to the difference in impurity content. For a given set of extrusion conditions the ram speed, maximum pressure, and initial temperature can also be correlated using a Zener-Hollomon parameter and a sinh pressure term. THE deformation of metals at temperatures over about one-half the absolute melting temperature has been extensively studied at creep strain rates. By contrast, relatively little work has been carried out on the behavior of metals at hot working strain rates. Most of the latter investigations have been performed using simulative methods, such as hot torsion and hot compression, in which the friction conditions and temperature rise during deformation may differ appreciably from those existing under industrial conditions. Recently, however, Wong and Jonas1 used a scaled-down industrial process to determine the stress and temperature dependence of the strain rate during the extrusion of aluminum. In such tests, the effects of friction and adiabatic heating are closer to those produced in industrial operations. Also, with regard to the testing of materials of limited ductility such as zinc, hot compression and hot torsion do not permit the attainment of true strains as large as the deformations usually applied commercially. The present study was undertaken to investigate the extrusion behavior of Special High Grade (SHG) zinc. The detailed objectives were: 1) to establish the stress and temperature dependence of the strain rate with and without a consideration of adiabatic heating, 2) to study the pressure and temperature dependence of the ram speed, and 3) to investigate the microstruc- tural changes occurring during the deformation. The last aspect of the investigation will be covered in a separate paper. The treatment described below differs from that of Wong and Jonas in that the adiabatic temperature rise during deformation is taken into account, and the calculation of the mean equivalent strain rate is based on the redundant as well as on the homogeneous work. EXPERIMENTAL PROCEDURE Rods from two shipments of continuously cast SHG zinc* were used in the investigation. The composition *Supplied by courtesy of Cominco Ltd. range of the impurities present, as given by the supplier, was: Pb: 0.0013 to 0.0023 pct, Fe: 0.001 pct max Cd: 0.0001 to 0.0006 pct, Cu: 0.0002 to 0.0005 pct, Ti: 0.0001 pct max; thus, by balance, zinc valued from 99.9963 to 99.9966 pct. The as-received rods were machined into billets having a nominal diameter of 1.56 in. and a nominal length of 1½ in.; longer billets up to 4 in. in length, were also used to investigate special aspects. The as-machined rods were annealed at 400°C for 24 hr and slowly cooled. This treatment produced a columnar grain structure, with a grain size of about $ by 2½ cm which was appreciably larger than the as-cast one. A 150-ton, direct extrusion, vertical press was used. Ram displacement and force were recorded continuously against time. A constant flow control valve permitted the maintenance of a range of preselected ram speeds up to in. per sec. The selected speed was held constant, irrespective of the required force, as long as the load developed was below the maximum available. Strain gages were used to determine the force; the gages were calibrated before and after each testing period with a 200,000-lb capacity load cell. Further details of the experimental equipment can be found in Ref. 2. The billets were preheated for 90 min in the extrusion container, which was well insulated so as to minimize temperature gradients. This period was sufficient for the billet to reach a uniform temperature at all temperatures between 110" and 350°C. A square-shoulder die having a 0.290-in. diam central hole was used. The extrusion ratio was 30 to 1. This is equivalent to a reduction in area of 96.7 pct, an elongation of 2900 pct, and a true strain of 3.4. The ram speed was varied over two orders of magnitude from 0.0027 to 0.26 in. per sec. The ram was water-cooled during most of the tests, although some experiments were conducted with a preheated, uncooled ram. All extrusions were run without lubricant, which resulted in conditions of sticking friction. EXPERIMENTAL RESULTS Stress Dependence of the Strain Rate Neglecting Adiabatic Heating. The maximum force required to extrude is given in Table 1 for each of the five initial

Jan 1, 1970

By AIME AIME

Annual net production of crude oil from the Anglo-Iranian, Oil Company&apos;s fields in Iran for the years 1940 through 1945 amounted to: YEAR TOTAL PRODUCTION (Long Tons) 1940 8,626,639 1941 6,605,320 1942 9,399,231 1943 9,705,769 1944 13,274,243 1945 16,835,000 (preliminary figure) All developed fields were on almost continuous production throughout the war, though their operation naturally was hampered by war conditions, which affected particularly supplies of equipment.

Jan 1, 1946

By W. Hurst

The authors of this paper, in substituting values in a material balance equation associated with a gas reserve and a water drive, cannot find sustainment of what the gas in place should be; therefore, their conclusion is that this type of problem dealing with gas reservoirs is insoluble. They have introduced the word, "cybernetics," based on the work of Norbert Wiener, that further extends this line of reasoning, namely, to the effect that the system is a "black box", and that the gas reservoir and aquifer can take on infinite aspects &apos;based upon their past performance, to quote the authors. The inference is that this black box is an unknown. which permits in computer programming to subscribe as many variables as possible to observe by adjustment of one to another those combinations of conditions that fit field behavior. This may satisfy those in this discipline whose dedication is to programming, but to the others this is a comparison to the rationalization of the combinational results of the throwing of dice—a probability procedure. In reservoir engineering we are more direct. We learn from the examination of individual we&apos;ll and field data exactly what is in this black box. I now come to the impasse that has confronted these authors in their machine calculations. In this I have reproduced from their own production data (Tables 1 and 2 of their paper) pressure vs cumulative gas produced. shown as Figs. D-1 through D-5. A perusal of any of these five plots, for the corresponding fields in the Po Valley, shows the straight-line relation of pressure vs gas produced, evidencing pressure depletion. The point I make is that in their fundamental production data, there is no variance from a straight line that can support a water drive.

By R. M. Kuralt

CONCESSION from the Chilean government granting the company use of the Rio Salado water stipulates that a minimum of 35,000 metric tons of such salty water must be diverted from the Salado daily, and be disposed of in a manner not to contaminate the Rio Loa to the east of its confluence with the Rio San Salvador at Chacance, Fig. 1. Consequently, the selection of a suitable site for the sulphide plant tailing disposal had the additional problem of the disposal of excess brackish waters. Studies of the terrain in the area directly to the south of the plant indicated that construction of tailing ponds would be costly, and generally unsatisfactory due to excessive slope of the ground, lack of flanking hills, danger of raising the groundwater level thus causing springs along the Antofagasta-Bolivia railroad; and the possibility of creating a dust nuisance at the plant site or at Calama due to blowing sands. Further to the southwest the San Salvador river canyon offered some possibilities and surveys were made at sites A to D, inclusive, Fig. 1. Here again costly dams would have been necessary to impound the tremendous quantity of tailing produced by the new plant, and provision would have to be made to handle a considerable flow of water through the disposal area to the west of the Rio Opache. Additional surveys were made in the area to the southeast of the plant which brought to light the existence of a natural basin of about 14 1/2 square miles, flanked by low-lying hills, and requiring only the most rudimentary dams to close the outlets at the western end. It has been estimated that the Salar de Talabre, as this basin is called, has the ultimate storage capacity of 1 billion tons of tailing with dam heights of only 60 ft. Pipe Line Layout After the decision had been reached to use the Salar de Talabre for the main disposal area various methods were considered for transporting the tailing from the 300 ft diam thickeners to the disposal site, 17.7 miles away. The first plan was to construct a. concrete launder on a 11 pct grade but a survey of this grade line indicated it would not lead directly into the Salar but would terminate somewhat to the north, and from that point on the slope would be considerably less than 1 pct along a natural watercourse. A slope of 2 pct or even 2 ¼ pct in such a rough watercourse or ditch is the ideal, judging from the success of operations at Cananea. Since a simple ditch is the most economical vehicle for the transportation of tailing, it was decided to use one with a 2 ¼ pct grade for as much of the distance as was possible with the existing terrain and to construct a concrete headbox, or forebay, at the terminus of the ditch to supply a steel pipe line leading the rest of the way into the Salar. Referring to the maps of the Chuquicamata area outlining the tailing disposal system, Figs. 1 and 2, one can trace the flow of the tailing from the thickeners to the Salar as follows: The 8-in. spigot pipes from the thickeners (1) discharge into a concrete sump feeding a concrete launder with a 2 pct slope. The launder carries the tailing into a concrete junction box (2) located south of the sulphide plant. The purpose of the junction box is to provide emergency facilities for diverting the tailing flow from the main disposal area to the emergency area. It also provides a junction point for the launder from the sulphide plant&apos;s future east extension. The box is fitted with a pair of radial gates controlling flow into the main tailing ditch (6) or the emergency ditch (3) which terminates on the pampa. All ditches are of the same cross section, namely 4 ft wide at the bottom with 1 : 1 side slopes and with a minimum depth of 21/2 ft. Where the nature of the ground demands it, the ditches are lined with stone rubble. The overflow from the plant&apos;s 10 million gal reservoir (4) is led into the main tailing ditch by way of a spillway ditch (5). The main ditch terminates in a trashscreen fitted, concrete forebay (7) which serves as a headbox for a 24 in. O.D. x 3/8 in. wall, Dresser coupled, steel pipe (10) and a 12 in. x 8-gage spiral welded, wedge-lock coupled, steel pipe (8). The forebay is fitted with two compartments, one for each pipe, and flow into each is controlled by radial gates. Each compartment is fitted with a 6-in. drain pipe controlled by a rubber pinch valve. To protect the forebay from the abrasive effects of the tailing, the sides of the compartments will be lined with old

Jan 1, 1952

By Nicholas J. Grant, H. C. Chang

TRANSCRYSTALLINE fracture surfaces of the cleavage type have been examined by microscopy and X-rays for several metals.&apos; These investigations revealed that the fractured surfaces were not flat and invariably had cleavage and other deformation markings on them. On the other hand, the study of inter crystalline fracture surfaces has been limited. Perryman, in a recently published paper on the inter crystalline fracture of ß-brasses,&apos; found that a thin layer of heavily deformed metal was invariably associated with these surfaces. Furthermore, the thickness of this layer was found to depend on the orientation of the grain boundary surface with respect to the applied stress. The mechanisms of grain boundary sliding and intercrystalline fracture have been presented in two previous papers,which described certain aspects of the deformation of a 20 pct Zn-A1 alloy. It is the purpose of this paper to present some observations on the structure of intercrystalline fracture surfaces and to correlate the structure of such surfaces with the mechanism of intercrystalline fracture. Experimental Techniques—The high purity 20 pct Zn-Al alloy was generously supplied by the Research Laboratories of the Aluminum Co. of America. Two sizes of specimen were used; the first had two parallel flat surfaces of dimensions 1x0.17x0.09 in. and the second was round with a 0.25 in. diam. A grain diameter of 1 to 3 mm was obtained by annealing the specimens at 1000°F for 24 hr. The specimens were then air cooled. The specimens were subjected to creep at 500°F and 2300 psi. The rupture times ranged from % to 3 hr, with one room temperature tensile test. It has been mentioned previous1y" that the intercrystalline fracture surfaces of this alloy, when tested under the conditions given above, are sharply defined. In the optical examination of the fracture surfaces, whenever possible, magnifications of at least X250 were used. The locations of the regions examined, both optically and by X-rays, were selected to give several fracture surface orientations with respect to the stress axis and to the specimen surfaces. This was possible for the X-ray studies since the grain diameters were large compared to the X-ray beam. A film to specimen distance of 3 cm, a 1 mm pinhole and Cr radiation were used for the Laue back reflection pictures.

Jan 1, 1957

By A. M. Khan, I. Fatt

A new type of steady-state thermal conductivity apparatus is presented and described. Results of measurements on Berea sandstone, Solehofen limestone, Bandera sandstone and Bakelite are presented. The measurements were made in a two-hour period at temperatures up to 80C and axial stress to 125 bars. Results show that the thermoelectric heat pump and tbermistor-controlled electric heater can be used in a steady-state apparatus for measuring thermal conductivity of mck. Steady-state is reached within two hours. With Urethane foam insulation, not more than 3 per cent of heat is lost by radial flaw. The apparatus can be used as a comparator or for absolute thermal conductivity determinations. INTRODUCTION Calculations of heat flow through the earth, both for scientific purposes and engineering design, require thermal-conductivity data on rock. However, the high variability of rock often makes handbook thermal-conductivity data of little value. For engineering purposes in particular, it is desirable to have measured data on samples of the rock mass under study. Laboratory methods for measuring thermal conductivity of rock use either time-dependent1-3 or steady - state temperatures .4,5 The time -dependent (transient) techniques give thermal diffusivity from which thermal conductivity can be calculated if the specific heat and density of the sample is known. Most transient techniques require lengthy and involved sample preparation. Also, the accuracy tends to be low. Steady-state techniques are more exact and are the most commonly used. The steady-state methods, however, also have their difficulties. A long time is often required to reach steady state, troubles have been encountered in establishing good thermal contact between the heating and cooling elements and the rock sample, and unaccounted-for heat losses are difficult to prevent. In this paper we present a description of a new type of steady-state thermal conductivity apparatus. With it, measurements have been made in two hours at temperatures up to 80C and axial stress to 125 bars. Sample preparation is simple and no thermal conductivity standard is needed.6 APPARATUS Our steady-state apparatus is an improvement . over the conduction pile used by Zierfuss and van der vliet4 and Somerton.5 A linear heat flux is established through a conduction pile consisting of the rock sample and a standard material of known thermal conductivity in series. The thermal conductivity of the sample is calculated from the ratio of the temperature drop across the sample

Jan 1, 1966

By Charles Pack

Die castings may be defined as metal castings made by forcing molten metal, under pressure, into a metallic mold or die. It is necessary to keep this definition in mind to avoid confusing this process with other permanent-mold casting processes. The fundamental principles of the process have been known and practised many years. The simplest application is embodied in the modern linotype machine in which molten metal (usually tin-lead alloy) is forced under pressure into a metallic mold. The pressure is derived from a piston and cylinder immersed in the molten metal. Progress in the art of die casting may conveniently be divided into three groups: Machine for imparting pressure to the metal, material for the die or mold, casting alloys. The problem of delivering molten metal under pressure into a die is comparatively simple, when dealing with low-fusing-point alloys, as the alloys of lead and tin, but it is much more complicated when dealing with metals of higher fusing points, such as the alloys of zinc, aluminum, and copper. Although the art of die casting is comparatively new and, to a large extent, unknown, the records of the patent office are replete with patents on the subject. Fig. 1 shows the Underwood machine patented in 1902; this is probably one of the first machines designed for the production of commercial die castings. The relation of this machine to the linotype casting machine is clearly apparent. A cylinder and piston are immersed in the molten metal, the application of power to this piston forcing the molten metal, under pressure, into the mold or die. The Doehler machine, Fig. 2, patented in 1907, is based on the same general principles. This machine is used to a large extent at the present time, throughout the United States, for the production of zinc, tin, and lead alloy die castings. In the machine shown in Fig. 3, patented by Doehler in 1910, compressed air is used for forcing the metal into the die. In Fig. 4 is shown another of this type of machine. Here compressed air is applied to the surface of the molten metal to force it into the die. In a machine patented by Chandler in 1914, shown in Fig. 5, the

Jan 1, 1919

By T. A. Rickard

The key-note of good writing, as of good manners, is B natural. Sincerity is the first requisite for effective writing. When a man says what he knows or believes, he is likely to be interesting, because each human being possesses an individuality, a point of view, or a range of sympathy that makes him different from his fellows. To say or to write what you do no6 think, for the mere sake of talking or writing, is a verbal exercise that must be performed with extraordinary skill if it is to be attractive. Affectations are rarely attractive, rarely effective. To be natural is to be yourself, not a poseur; to give the reader the best of yourself, instead of re-warming the baked meats of yesterday. Quotations-which are second-hand thoughts-will serve occasionally when the thing you want to say has been said so well by another that it would be waste of energy to try to say it better; but, as a rule, the utterance of the writer himself is more interesting than the quotation, because the writer brings something of himself to bear on the subject, and for the moment is more in touch with the reader than any dear departed author. Therefore, say things as best you can in your own way, neither in borrowed words nor in the phraseology that mimics another. Write as if you were speaking to a person whom you desire to persuade or convince. You will then write better than you speak, because, in the first place, you can be more deliberate, and, secondly, you can revise what you have written. Speaking and writing are similar mental acts, with a difference: the difference between eating food raw and eating it cooked. Some kinds of food gain nothing by being cooked; likewise some kinds of utterance are not bettered by being written down first; but most expressions of thought, especially

Jan 1, 1931

[JAMES A. BARR Consulting Engineer Mt. Pleasant, Tennessee Washington) D.C. BEHRE DOLBEAR & COMPANY Consulting Mining Engineers and Geologists 11 Broadway New York 4, N. Y. BLANDFORD C. BURGESS Registered Professional Engineer Mining Consultant Monticello, Georgia GLENVILLE A. COLLINS Mining Engineer Uranium examinations Cable "Coins" 210 La Arcada Bldg. Santa Barbara, Calif. COWIN & CO. Mining Engineers and Contractors Consulting Shaft & Slope Sinking Appraisal Mine Development Reports Mine Plant Construction I- 18th St. S. W. B&apos;ham, Ala., Phone 56-5566]

Jan 1, 1952