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By Frederick Laist

(Butte Meeting, August; 1913.) WHILE remodeling No. 1 section of the concentrator at the Washoe Reduction Works of the Anaconda Copper Mining Co. during the summer of 1912, for the purpose of ascertaining what additional metal recoveries could be made by improvements in concentration practice which had been developed by the staff of the Boston & Montana Reduction Department, at Great Falls, it was deemed advisable to carry on some experiments on the -treatment of the regular mill tailings by roasting and leaching, to see whether the losses of metal values might not be still further decreased. In the course of these experiments about 5,000 tons of tailings were roasted, and of the resulting calcine about 200 tons were leached. The results were so satisfactory that it was, decided to continue the work on a larger scale, particularly as regards the leaching end of the process, and construction work on an 80-ton roasting and leaching plant was accordingly commenced during the latter part of February, 1913, and is being pushed as rapidly as possible. 80-Ton Leaching Plant. This plant will consist of one 20-ft. roasting furnace of the MacDougall type, specially adapted to the work of roasting for leaching; two leaching tanks, 32 ft. in diameter by 12 ft. deep, together with the necessary solution tanks, air lifts, precipitating launders, etc. It has been decided to precipitate the copper from solution on scrap iron, so as not to hamper the roasting and leaching departments by any weakness that might develop in the precipitating department. It is, however, the intention to experiment with a number of different methods of precipitation; for example, by electrolysis and by hydrogen sulphide.

Jan 7, 1913

By Milton H. Fies

Although pig iron from iron ore and red cedar charcoal preceded the mining of coal by many years, for tradition says that Alabama iron was used to shoe the horses of Andrew Jackson's soldiers, coal was not produced until 1830. In that year, coal was mined in Tuscaloosa County, in the vicinity of what is now the University of Alabama, and shipped on flat boats (obviously during the wet season, for there were many shoals) down the Warrior River to Mobile. About that time, the first railroad, the Decatur & Tecumseh, was being constructed in northern Alabama to overcome the obstructions to freight traffic caused by the now well-known Muscle Shoals in the Tennessee River. This railroad was patterned after a railroad at Mauch Chunk, Pa., which was used for hauling anthracite from the Panther Creek valley. The Alabama railroad, which required about four years to complete, was 46 miles long and was used solely for the transportation of cotton. Although it was a failure, it demonstrated the practicability of the undertaking, and the succeeding railroads, which were begun in 1834, 1848, 1852, and 1853, added immeasurably to the development of the coal resources of the state. Between the years 1830 and 1860, practically all the coal mined in the state was dug from the outcrop near the river or from the river beds, and shipped by boat to Mobile. Transporting coal down the Warrior River was an undertaking of great risk, required much skill, and frequently had heavy losses. It is recorded that this coal was sold to the gas company in Mobile in 1844; it was most likely mined from the Black Creek Seam. In 1914, on the completion of Lock 17, the Warrior River became a navigable stream from 9 miles above Cordova, Ala., to Mobile and offers a great opportunity for the future development of the coal resources of the state. Coke for foundry use was first made in Alabama in 1855. It was 21 years later, however, in 1876, that pig iron was made from Alabama ore with Alabama coal.

Jan 1, 1925

By John Campbell

An approximate theoretical model is proposed to quantitatively predict freezing ranges Tf and hydrostatic tensions P developed within solidifying binary alloys, allowing for a certain amount of diffusion of solute in the solid during solidification. The maxima in ATf and AP as functions of composition are shorn to occur at smaller solute concentrations than would be expected from the equilibrium diagram, and are found to correspond closely to experimentally observed maxima in microporosity. THE freezing range of simple binary alloys appears to have been little studied, except for certain indirect observations on the defects, particularly microporosity and hot tearing, arising in long freezing range materials. Two theories relating to the freezing range of alloys and its effect upon porosity are reasonably well established, and appear to have been held in isolation from each other: a) From purely equilibrium considerations early researchers expected that an increase in solute content of an alloy should increase the freezing range (defined here as the equilibrium freezing range ?Tf = Tl-Ts where TL and Ts are the liquidus and solidus temperatures, respectively) and thereby increase the width of the pasty zone for a given set of conditions. This in turn should increase the difficulty of feeding the residual liquid through the dendrite mesh to compensate for the contraction on solidification, and consequently tend to increase the observed amount of porosity. From qualitative observations on steels Czikel1 reports an increase in porosity with increasing carbon content up to 0.46 pct C. More careful measurements by Whittenberger and Rhines2 on fourteen different alloy systems showed an approximately linear relation between ?Tf and pct porosity (although unfortunately the precise experimental data is not given). b) Conversely however, other authors3"5 propose that porosity is reduced by the presence of increased amounts of eutectic present at the final solidification temperature. Lees7 and Bochvar6 claim that the hot tearing of alloys is similarly reduced. Scheuer8 has put forward a theory to explain this effect, Fig. 1. The argument is basically that solidification progresses on a plane front through a relatively open dendrite network and is thus (the argument is not developed more explicitly) easier to feed. One would expect effect a) to operate at low solute contents, and b) to be important at higher solute contents, so that at some critical composition a max-

Jan 1, 1970

By R. L. Grunes, F. K. Kies, C. D&apos, Antonio

THE several studies concerned with the annealing of thin nickel films have largely been restricted to films of a single thickness.1-4 It is well-known, however, that both physical and mechanical properties depend upon film thickness.5, 6 The strength-thickness relations found in vapor-deposited nickel films in the annealed and as-deposited states, as an example, are at least partially due to the density and arrangement of imperfections within the films.7, 8 For these reasons, the annealing characteristics of thin nickel films as a function of thickness were investigated. Electrical resistance was chosen to monitor annealing behavior since resistance changes are partially dependent upon defect structure. In addition, the equations predicting film resistivity as a function of thickness are already available.9, 10 Further advantages afforded by electrical-resistance measurements are its adaption to continuous readings during annealing and its relative simplicity. Nickel films were vapor-deposited, at average rates of 60Å per sec, on Vycor substrates held at room temperature in vacuums of about 10-5 torr. Afterwards, deposition-thickness measurements were made using a multiple-beam interferometric technique. A more detailed description of deposition procedures and the interferometer appear elsewhere.7, 8 The four-probe method was employed in measuring electrical resistance since this technique measures film resistance without contributions from lead wires and contacts. Resistance measurements were made before, during, and after annealing to temperatures of 700°C under vacuums of approximately 10-4 torr. Measurements were made every 25°C or more often when necessitated by unusual resistance changes. Cooling and heating rates were maintained at approximately 5°C per min. Typical resistivity vs temperature curves are shown in Figs. 1 through 4. It is apparent from these

Jan 1, 1965

THE Institute of Metals Division opened its series of meetings by a session* on lead, R. S. Dean be-ing in the chair and G. 0. Hiers acting as vice-chairman. A large and representative audience listened to the papers in the abstract and contributed an inter-esting and fruitful discussion. The main points of these papers and discussion are given below: In the absence of Carl E. Swartz, the summary and conclusions of his paper, "A Study of the Lead-Tin-Cadmium System with Reference to Their Use as Solders," were read. Swartz investigated a number of alloys in the lead-tin-cadmium system and prepared a diagram representing the solidification ranges of these alloys. He also made tensile strength tests of joints made with these alloys, and compared these with joints made with ordinary lead-tin solder. The tests showed solders containing cadmium were equally strong as the lead-tin series and that the cadmium alloys were suit-able in other respects for use as solders. In general, solders of the composition near to the ternary lead-tin-cadmium eutectic appeared to be the best for most soldering work although compositions widely differing are desirable for special purposes. The lead-tin-cad-mium solders are finding a market particularly in the fields requiring lower solidification temperatures than common solders. Mr. Darby opened the discussion and asked whether it was a fact that the lead-tin-cadmium solders were more useful than ordinary solders on galvanized and tin-plated sheet. C. Smith said he thought it to be a fact that galvanized sheet was more easily soldered by the lead-tin-cadmium solders than common lead-tin-solder. Continuing, Mr. Smith showed lantern slides of his own investigation of the thermal diagram and recommended the 70 per cent lead, 20 per cent cadmium, and 10 per cent tin for general employment. He thought the author did not differentiate between wetting and alloying and pointed out that wetting was more a ques-tion of the flux than the metal. In some cases a definite alloy was formed by soldering and in some no evidences of alloying were found. Illustrating the former case he showed slides and demonstrated that failures always took place longitudinal with the brittle compound alloy and transversely across the solder itself.

Jan 3, 1928

By Derek J. Fray, John Chipman

THE solubility of graphite in y-iron has been determined by several workers'12 with reasonable agreement. With the increasing use of more complex steels, it is necessary to understand more fully the thermodynamics of the austenite phase. The activity of carbon in a number of alloys is known but the maximum solu- bility of graphite has only been measured by Sohnchen and piwowarsky3 for Fe-Ni and Fe-Si alloys. Recently, Chipman and Brush reviewed the published data on the activity of carbon in binary and ternary austenite and also obtained expressions for calculating the solubility of graphite in Fe-Ni, Fe-Co, and Fe-Si alloys. On comparing the theoretically derived solubilities with the limited results of Sahnchen and Piwowarsky, it was found that the agreement for Fe-C-Si was excellent but there was considerable discrepancy for Fe-C-Ni and no data for Fe-C-Co. It was therefore decided to measure the solubility of graphite in a series of Fe-Ni and Fe-Co alloys. The alloy samples were made up by induction melting a high-purity master alloy under an inert atmosphere in an alumina crucible and drawing the molten metal into four-bore alumina tubes. Using this technique, it was possible to form alloy rods approximately 2 in. long and 1/18 in. in diam. Sixteen lengths of fine rod could be made without solidifying the master alloy. These were then allowed to cool under the inert atmosphere before being sectioned. The samples were packed in a graphite crucible with spectroscopic graphite powder, together with a piece of pure iron foil. Dry hydrogen, which had been saturated with isopropyl alcohol at room temperature, was passed over the crucible at 1000°C for 72 hr. At the end of the 72 hr argon displaced hydrogen in the reaction tube and the crucible was quickly pushed to the water-cooled end. The samples were thoroughly cleaned of the adhering graphite and analyzed. The pure iron samples always contained 1.5 0.02 pct C, which compares favorably with the data of smith2 and

Jan 1, 1970

By George C. Branner

STATE geological surveys have had an interesting development in this country. They first appeared more than a hundred years ago. The fact that they have persisted and are now an important part of most state governments indicates the basic need for state departments con-cerned with mineral problems. The number of state surveys in 1941 (43) is at an all-time high, as is the aggre¬gate appropriation for their support for the fiscal year 1940-'41 ($1,600,708). The first surveys, those of North and South Carolina (see Fig. 1), made their appearance in 1820-'30, but neither survived that period. During the next two decades surveys were created in twenty states, but only three survived. In fact, it was not until the decade 1900-'10, when eighteen surveys were created and only five abolished, that these agencies became firmly established.

Jan 1, 1941

By L. Michael Kaas

The mineral industries are striving to expand their use of the computer's ability to process exploration, geologic, and mining data. Digital plotting programs and devices are continuing to gain wider use for lowering the cost and the time required to produce many types of maps and cross-sections commonly used by mining companies. Mineral engineers and geologists will soon be using a new tool, computer graphics, to greatly facilitate the use of computers to solve a large number of industry problems. By means of cathode-ray-tube (CRT) displays, an engineer can search large files of geologic data; display elevation contours, geologic structures, and ore grades; construct geologic and mining cross-sections; and compute tonnages for mining plans or ore reserve estimates. Examples of both digital plotting and cathode-ray-tube problem solving approaches are discussed in this paper.

Jan 1, 1969

By Donald C. Myntti

Modern open-pit mining can be described as a capital-, labor-and energy-intensive, large-scale, mechanized, and highly repetitive bulk material preparation and handling operation, with emphasis on the word "mechanized." In hard rock, this generally means shovels loading blasted materials into haulage units for transport to processing plants, stockpiles, or waste dumps. Mine management deals with several primary concerns on a daily basis; e.g.: Will any serious accidents and labor problems occur today, and will the tonnage targets be met considering the physical condition of the equipment? The latter subject will be discussed from a maintenance perspective. A successful, progressive heavy equipment maintenance program that protects company assets involves many elements. They include: •Proper equipment selection and procurement •Well-trained and motivated workforce •Good shop facilities •Preventive maintenance (PM) program •Warehouse support •Operations-maintenance department cooperation •Meaningful paperwork

Jan 3, 1978

By AIME AIME

ON April 7 the twentieth national Open-hearth Conference of the A.I.M.E. will be held in Birming¬ham, Ala., in conjunction with a meeting of the Committee on Blast Furnaces and Raw Materials. At least 300 engineers and operators are expected to attend. Birmingham, the industrial city and iron, and steel center of the South, has been called the "Magic City." Men actively engaged in business in Birmingham today have seen practically every building in the business district erected, have witnessed the establishment of every existing industry, and have hunted birds cm the site now one of the busiest corners of the business district. Incorporated as a town in 1871, the city today has a population of more than 380,000 in its metropolitan area. It is

Jan 1, 1937

By Wheeler O. North

The United Eastern Mining Co.'s property is in the Oatman, Gold Roads mining district of Mohave County, Ariz. The mine and mill are 26 mi. (41.8 km.) southwest of Kingman, the nearest railway connection. The ore consists of a mixture of calcite and quartz with some andesite. The values, which are mainly gold, alloyed with approximately 34 per cent., by weight, of silver, are extremely fine so that fine grinding is a most important factor in extraction. The milling process, briefly, consists of single-stage, coarse-crushing, two-stage ball milling in cyanide solution, followed by combined mechanical and air agitation, and by straight counter-current decantation. The Merrill zinc-dust precipitation method is used to recover the values, and is preceded by the Crowe vacuum treatment of the solution. The most notable features of the plant are the absence of filters, and the use of short peb mills loaded with steel balls, for fine grinding. As originally designed, the capacity of the mill was to be 200 tons per day, although the grinding end was to be capable of handling double that amount. By adding extra agitators and thickeners and by some alterations to the grinding end, the daily capacity has been raised to 285 tons. This, it is hoped, may be increased to 300 tons during the warm months of the present year. Tonnage Milled per Day 1917 average....... 234; maximum month.... 272; minimum month..... 146 1918 average....... 253; maximum month,... 276; minimum month..... 217 As this article primarily deals with plant operations, those interested in the mechanical description are referred to the article by Mr. Otto Wartenweiler,1 the designing engineer, which gives the details and costs of design and construction. The following changes have been made since that article was published: Two special simplex Dorr classifiers have been substituted for the two duplex Callow screens and bucket elevator, which classified the Marcy discharge and returned the oversize for regrinding. Three Dorr

Jan 1, 1920

By M. Garfinkle

LITERATURE data1'3 have suggested that the resolved shear stress necessary to initiate slip in a particular slip system in tungsten single crystals is strongly dependent on the tensile orientation of the crystals. This orientation dependence is contrary to the critical resolved shear stress criterion. Because the Schmid factors for slip on particular {110}( I l l), {112}(Ill), or {123}(111) slip systems in a (100) oriented tungsten crystal are virtually identical to the respective Schmid factors for a (110) oriented crystal, slip should initiate on the same system in both orientations, independent of the values of the critical resolved shear stresses. Thus, it would be expected that, for a critical resolved shear stress model to hold, the proportional-limit stress for these two orientations must be similar. The expectation of similar proportional -limit stresses has not been borne out by reported experimental observations. Rose et nl.' reported that the proportional-limit stress for crystals near the (110) orientation was 92,000 psi, approximately three times that of (100) oriented crystals (31,000 psi). Garlick and probst2 reported greater than a fourfold difference. Most recently, Beardmore and ~ull~ examined tungsten crystals with orientations along the edge of the standard stereographic triangle and showed a gradual increase in proportional-limit stress from 28,000 psi for the (100) orientation to 93,000 psi for the (110) orientation. Again, the difference was more than threefold. As has been emphasized by these investigators, the apparent gross variation of proportional-limit stress with orientation precludes any meaningful analysis of slip mechanics using a simple critical resolved shear stress relation. The purpose of the present communication is to report that, by use of refined strain-measuring techniques, the proportional-limit stresses for the (100) and (110) orientations are quite similar. Obviously, to determine accurately the value of the proportional-limit stress, which is by definition the stress at which nonlinear stress-strain behavior first occurs, the method of measuring strain must be capable of high accuracy. The investigators cited used as the measured elongation the crosshead displacement of the tensile machine. This method, however, introduces extraneous strain contributions from the load train. Because these extraneous contributions are considerable in the initial portions of loading (as has been well-documented in the literature) the proportional-limit stress measurement, dependent on the deviation of a line from linearity, can be significantly affected. During the course of a recent study, room-temperature strain was measured directly on several (100)-and (110)-oriented tensile specimens axially oriented within 5 deg of the desired direction. Each specimen was fitted with two foil strain gages mounted on opposite sides of the 0.08-in.-diam reduced section. The tensile specimens were loaded at a crosshead speed of 0.01 in. per min on an Instron Universal Testing Machine. Strain was monitored through an external bridge circuit in which the specimen strain gages comprised two arms. The bridge output was recorded against the applied load. A strain of 2 x 10"" could be readily detected by this method. Some specimens were subjected to conventional loading while the load for others was cycled between zero and continually increasing values until the first deviation from linearity was observed. The results of these methods were similar, and the stress at which nonlinear behavior occurred was considered the proportional-limit stress. The proportional-limit stresses measured in this study are approximately 5000 and 6500 psi for the ( 100) - and ( 110) -oriented crystals, respectively, a range of values almost a magnitude less than those reported previously. Representative curves are presented in Fig. 1. Because of the nature of the measurements made, the point of departure of a line from linearity is often debatable. While the load-strain curve for the (100) -oriented crystals made a relatively abrupt deviation from linearity, the curve for the (110) -oriented crystal was more gradual, so that the actual point of tangency may be at a lower load than reported. Thus, the difference in values for the proportional-

Jan 1, 1967

By Arthur F. Taggart

MR. CHAIRMAN: Congratulations! Your four-ring milling show this year was a dandy. It cleared our minds, for a few hours at least, of what Hitler, Hirohito, the New Deal, and the tribe in the Treasury are trying to do to strangle American enterprise. We mustn't forget this, but it's a relief to get our thoughts away from it occasionally. GRINDING-There was a further contribution to the excellent work that the Allis-Chalmers laboratory staff has been doing for the grinding fraternity in compiling-and publishing-a carefully quantitative list of comparative resistances of ores and other materials to comminution (T.P. 1579, Bond-Maxson). A diagnostic accuracy of ± 10 per cent was claimed for estimates based on these figures. Are they really that good? How about some of you men in the field writing M&M about it?

Jan 1, 1943

By T. N. McVay, E. E. Creitz

Rather large amounts of titanium minerals and some zircon and monazite are being recovered from dune sands about I. miles west of Jacksonville Beach, Fla. The Mining Branch of the Bureau of Mines, Southern Experiment station, has been interested in developing additional large deposits of similar sands in other areas of Florida. The results of a field study have been published1 concerning the sands occurring on Trail Ridge which runs north and south about 30 miles southwest of Jacksonville. This investigation was undertaken in order to identify the opaque titanium minerals occurring in Trail Ridge and because of the economic importance of Florida titanium minerals. Nature of the Problem The minerals present in the heavy fractions (sp gr > 2.94) of the sands are principally opaque minerals; staurolite, zircon, sillimanite, tourmaline, kyanite, rutile, a small amount of corundum, traces of the zinc spinel gahnite and garnet. Epidote, monazite, hornblende and ti-tanite are present in other dune sands but these minerals were not noted in the samples collected on Trail Ridge. All of the minerals except those which are opaque can be readily identified by the usual petrographic methods. However, Opaque minerals cannot be examined satisfactorily by transmitted light. Polished sections of the opaque-mineral grains were examined but these sections did not furnish useful information. Consequently, it was necessary to use means other than the usual petrographic methods to identify them. Previous Investigations of Heavy Minerals in Florida Sands Martens2 has described the heavy minerals in the Florida beach sands and has classified the opaque minerals as ilmenite with minor amounts of leucoxene. Miller3 studied a number of sands collected by Ross and Mertie in Florida. He states that the material from the Florida beach and dune sands that commonly has been called ilmenite has essentially the chemical composition of the material that has been called arizonite.4 The x ray diffraction patterns of several samples indicated that the supposed ilmenite is essentially amorphous, with only weak lines corresponding to ilmenite, and hence the material is unlike the type of arizonite from Arizona. Opaque Titanium Minerals Rutile is essentially titanium dioxide. However, as pointed out by Dana,5 important amounts of Fe+2 and Fe+3 as well as Cb and Ta are reported in some analyses.

Jan 1, 1949

By Sooi P. Chong

Expansion of concentrator capacity at Iron Ore Company of Canada's Carol Lake plant resulted in a dramatic increase in the production of fines. With iron recovery from the fines running only 18%, Carol Lake engineers initiated an extensive test program which resulted in the installation in July 1977, of a full-scale plant utilizing Reichert cone concentrators. Results to date have indicated a 100% increase in iron recovery from the concentrator's fines product. Carol Lake is located near the western boundary of Labrador, Newfoundland, some 960 km (600 mi) northeast of Montreal. Concentrator operations began in 1962 with a design capacity of 7 million t/y (7.7 million stpy). The bulk of the concentrate was pelletized at a 6 million t/y (6.6 million stpy) pelletizing plant completed in 1963. The remaining concentrate was sold in the international market. The concentrator was first expanded in 1966 to 10 million t/y (11 million stpy) capacity. In 1967, the pellet plant was expanded to match the increase in concentrate production. Sales increases led to a further expansion in 1973. By 1977, more than 40 million tons (44 million st) of crude ore were processed to recover in excess of 17.42 million tons (19 million st) of concentrate and 10.4 million tons (11.5 million st) of pellets.

Jan 12, 1978

COLUMBIA SECTION J. C. HAAS, Chairman W. J. HALL,. Vice-chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, 720 Peyton Bldg., Spokane, Wash. W. H. LINNEY J. F. MCCARTHY At a meeting of the members of Columbia Section, which was held in the Davenport hotel, Spokane, Wash., Jan. 31, 1919, at noon, there were present' about twenty members and guests. The chairman being absent, Mr. Frederick Keffer presided. The Secretary announced the personnel of the executive committee of the section, which is: J. C. Hass, Spokane, Chairman; W. J. Hall, Wallace, Ida., Vice-chairman; S. S. Fowler, Riondel, B. C., Past Chairman; L. K. Armstrong, Spokane, Secretary-Treasurer; R. M. Betts, Cornucopia, Oregon. It was stated that the geological survey and report on Stevens Co., Wash., has been completed and will be printed soon. The geologic survey of Colville Indian reservation, by J. T. Pardee, U. S. G. S., has been published as Bulletin No. 677 and is available for distribution, The Miner's Almanac, Miners Circular No. 24, U. S. Bureau of Mines. is also available upon request. There was considerable discussion on the program for meetings during the year. It was informally agreed that, if agreeable to Coeur d' Alene members, that one meeting should be held in that district, preferably at the time of the annual visit of Institute officials. It was also proposed to hold at least one open-air meeting in Spokane with suitable program. The activities of other sections were noted with favorable comment. In this connection there was much general discussion on the subject of closer relations between the national engineering societies. It was agreed that cooperation was desirable and imperative if the greatest measure of value be realized from the profession. It was not the sense of the members, however, that complete amalgamation is desirable. This expression of local sentiment is to be presented to the Institute

Jan 3, 1919

By H. Kazemi, M. S. Seth

The effects of anisotropy and stratification on flow behavior and production performance of oil and gas wells have been studied by numerous authors.1-3 Lefkovits et al.l studied the performance of totally penetrated, stratified bounded reservoirs with no crossflow. Others have studied a similar problem, but with crossflow; Russell and Prats2 have summarized the findings of these papers. Muskat3 studied the steady-state behavior of liquid flow for a partially penetrating well in an anisotropic system and concluded that the productivity weakly depended on the directional permeability ratios (kz/kr>0.1). Nisle4 used the classical method of point source solution to the diffusivity equation to study the effect of partial penetration on pressure buildup of oil wells in an isotropic system. He found that the theoretical pressure buildup curves consisted of two straight lines, the one at early buildup times having a slope proportional to the flow capacity of the open interval (l-d)k, and the other having a slope proportional to the flow capacity of the entire formation hk,. Later Brons and Marting5 supplemented the findings of Nisle and concluded that partial penetration gave rise to a pseudo damage, which reflected itself as a skin factor in pressure buildup calculations. Using the pseudo skin, they calculated the impairment of productivity of the production wells, which agreed well with the results of Muskat.6 Pizzi et al.,? using an electrical analog of a stratified system, concluded that a high pseudo damage resulted if the reservoir was partially penetrated. Harriss studied the optimum spacing and arrangement of perforations in cased holes. Hantush9 derived an expression for pressure distribution in an unbounded reservoir with restricted flow entry. Seth10 extended Hantush's work to a bounded reservoir. Odehl1 has studied a similar problem for steady-state conditions. The purpose of this work was to investigate: (1) the combined effects of anisotropy, stratification with crossflow, and restricted flow entry on pressure transient analysis of flow and buildup tests, (2) the feasibility of calculating the horizontal permeabilities of intercommunicating stratified systems, and (3) the pressure interference tests in such systems. Theory The partial differential equation governing the isothermal flow of homogeneous fluids of constant compressibility is given by Eq. 1: The initial and the boundary conditions are: 1. The reservoir potential is initially constant, say 4v

Jan 1, 1970

By L. W. Pommier, F. B. Brien

In order to determine the ability of cyclones with heavy liquids to preconcentrate ores, a study of the variables which govern the behavior of the solids in the apparatus has been made. To assess the test results, the cyclone products have been examined by sink and float analysis at various specific gravities and the results examined by the Tromp type curves. This analysis has allowed the development of the SG50 unit — specific gravity of the particles, 50% of which goes to overflow and 50% to underflow — rather than the d50 (size) unit used in classification. The results of tests using the closed circuit laboratory cyclone assembly with dry feed samples show the validity of the equation: Results indicate that 83% of the feed may be rejected containing 0.1% Sn. Recoveries in excess of 80% are obtained at a grade of 1.7% Sn from feed samples assaying 0.4% Sn. As water-wetted particles may comprise the plant feed, separate tests were performed to examine the effect of water in the feed material. Results indicate that the entrained water divides into two fractions, one of which is defined as free water and is rejected to the cyclone overflow, the other fraction forms an adhering envelope of water on the ore particles, altering their effective size and density. The presence of the envelope of water on the particles increases the ease with which the heavy liquid can be recovered but decreases the concentration efficiency. It is proposed that the detrimental effect of water in the cyclone may be minimized by using a higher feed pressure cx by the use of surfactants. A higher feed pressure, by increasing shearing forces, would reduce the thickness of the water envelope on the particles. The surfactants, by adsorbing on the particles and producing hydrophobic surfaces, would displace the water envelope and allow the heavy liquids to wet the modified surfaces. In both cases a larger proportion of the entrained water would report to the cyclone overflow as free water, thus minimizing the detrimental effect of water on the concentration efficiency. Additional testing is required on the behavior of water in the system; to determine the optimum particle size for the preconcentration step; to determine final particle size for optimum liberation and subsequent treatment of the products in present plants and to determine the efficiency with which the heavy liquids may be recovered from the products. For many years tin mining in Bolivia has been very important to the economy of the country. In recent years the tin content of the ore reserves has been steadily declining. An improvement in concentration efficiency is highly desirable in order to increase productivity from the present low-grade mine ores and to allow retreatment of the many millions of tons of tailings from past operations, some of which equal the present ores in tin content. A number of investigators have been or at present are working on various phases or approaches to the problem. Gravity concentration is used in Boliva today as it has been in the past to recover tin minerals from the mine ores. An objective of the work reported in this paper was to examine the possibility of treating present low-grade ores and sink-float tailings products, at a relatively coarse grind, in order to produce a higher grade feed material to the present gravity concentration plants. The possibility of using heavy liquids in cyclones to treat large tonnages with a minimum of outlay presented itself and is of particular interest since heavy liquids are now available with physical properties which lend themselves to simple recovery methods. Tests were carried out using a closed circuit laboratory cyclone assembly. It was desirable to determine the value of using the SG50 concept and Tromp curves for analyzing the cyclone concentration test results. The effects of entrained water on the behavior of ore particles in the cyclone were examined. THEORY AND TECHNICAL CONSIDERATIONS Three types of heavy liquids are available: aqueous solutions of very soluble salts, salts or mixtures of

Jan 1, 1964

By J. P. G. Farr, R. Brownsword

THE role of solute segregation in the formation of cellular solidification substructures in tin and its dilute alloys is well-established, see, e.g., Ref. 1. Segregation has been shown to persist during cooling, enabling solidification structures to be studied from sections taken at some distance behind the interface. In the present work, a single crystal of commercial nickel, 99.965 pct, was examined in this way. The crystal was cut from the center of a rod given a single pass in an electron beam floating zone melter. Polished sections of a nickel specimen taken normal to the growth direction showed a very fine precipitate phase, the distribution of which varied over the section. The identification of the phase proved difficult because of the small amount present and the small particle size, about 1 p: but it was shown by probe microanalysis to contain only nickel and oxygen in detectable concentrations and was probably nickel oxide, NiO. Bulk analysis of the material before melting showed there to be only 3 to 4 ppm of oxygen present, thus demonstrating a very considerable segregation concentration effect. In some areas of the section the precipitate formed a discontinuous hexagonal network suggesting decoration of the cellular boundaries known to be present in the sample2 whereas in a restricted region the precipitate formed small clusters. Occasionally it could be seen that the clusters were at the intersections of an hexagonal network of cellular dimension. It was suggested3 that this was the result of enhanced segregation to the cell boundary intersections whereas general cell boundary segregation was insufficient to give a precipitate. Enhanced nodal segregation has since been demonstrated in a number of systems.1, 4-8 The development of a suitable electrolytic etching technique (perchloric acid 20 pct v/v; ethyl alcohol 70 pct; glycerol 10 pct; current below electropolishing plateau; 1 to 2 sec etching) suggested the association of the phase with regions of solute segregation (where ko < 1); in these regions anodic attack produced grooves or depressions. In a study of the variation of solidification substructures with degree of constitutional supercooling, Biloni et a1.&apos; appear to have used standard growth conditions and varied the solute concentration. They were able to produce in a series of individual tin crystals examples of substructure ranging from planar interface through various cellular structures to den- Fig. 1—Electroetched section taken normal to the rod axis; the center of the rod lies to the left and the periphery to the right of the micrograph. The variation of structure across the section is evident. Magnification 60 times. drites. It was possible in the present nickel crystal to observe a continuous range of substructures varying with degree of supercooling across a single section as shown in Fig. 1. Growth rate, 13 mm per min, and temperature gradient were essentially constant; the variation in structure is thought to be due to a radial gradient in solute concentration ahead of the solid interface. The liquid at the interface is likely to have been richer in solute toward the periphery of the zone, the result of curvature of this interface. The type of substructure was seen to vary with increasing constitutional supercooling as follows: a) region free of precipitate. top left, Fig. 1: 6) region of nodal precipitates which became arranged in hexagons on passing from the center of the rod: c) irregular hexagonal cells with incomplete boundary precipitation; d) regular hexagonal cells of decreasing size with complete boundary precipitation. Fig. 2 shows the transition from stage 6 and Fig. 3 shows the structure in stage d. Within stage 0, the range of conditions over which irregularly positioned nodes occur appears to be small and the nodes are soon recognizable as taking up positions at the intersections of an hexagonal network as the supercooling increases.

Jan 1, 1970

By AIME AIME

The Bulletin. As already announced in the January Bulletin, this publication will be issued during the coming year monthly instead of bi-monthly as heretofore. Among other reasons for this change, it is desired to effect thereby the earlier transmission to members of important papers, lists of candidates for membership, and other items of timely information. The New Haven Meeting. As already announced in special circular, the XCVIth meeting of the Institute for the reading and discussion of papers will be held at New Haven, Conn., beginning Feb. 23, 1909. The Secretary of the Local Committee is Prof. J. D. Irving, Box D, Yale Station, New Haven. The program embraces visits to many interesting works in New Haven, Ansonia, Bridgeport, etc. The leading topics for discussion at the sessions will be: The Conservation of Natural Resources; A Sea-Level Canal at Panama; and The Technical Education of Mining Engineers. But papers on other subjects also are announced. A supplementary session of this meeting will be held in New York City, at some time during March, 1909, as a joint session with other national engineering societies, for the further discussion of the subject of The Conservation of Natural Resources. A Pacific Coast Meeting. The XCVIIth meeting will be held on the Pacific Coast, including a visit to the Exposition at Seattle, and various other points en route going or coming, depending upon the route and program finally adopted. More definite information will be announced at the New Haven Meeting, or at the earliest possible date thereafter.

Feb 1, 1909