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This excellent paper by Dr. Colombo parallels quite closely the bench and pilot work done by the Hanna Research Laboratory on the Mesabi oxidized taconites. Because of the vast reserves and future ore requirements the need to perfect the selective flocculation-flotation process becomes very necessary. The selective flocculation process is a very efficient method of desliming, leaving a fairly clean, upgraded product for flotation. However, one of the problems that we have encountered in this process was some very fine, -2 micron liberated goethite in the slimes that did not flocculate. The complete slime removal is not necessary. We remove slimes to the extent of about 5% of the iron units. However, on difficult treating ores we would remove more slimes. The reclaimed water from our pilot plant has a turbidity of about 1000-3000 ppm. We can obtain lower turbidity water but to do this would involve additional lime as a tailing flocculant and we would run the risk of flocculating the entire ground pulp in the selective flocculation process because of the increased Ca level in the water. We have about seven different geological ore types out of 17 recognizable ore types that are treatable. All of these ore types require different degrees of dispersion and grinding which is a problem. The use of acrylic acid polymers as a selective flocculant has been patented by the American Cyanamid Co. This will-have to be

Jan 1, 1979

GEO. F. COMSTOCK,* Niagara Falls, N. Y. (written discussion?).¬A study of this paper raises a question on which it is hoped Mr. Stork will throw more light; that is, why does an oxygen content generated on poor melting conditions have a deleterious effect on the properties of the iron, while an oxygen content generated by the oxidation of steel scrap in the cupola is beneficial to the strength and chilling ability? In each case the oxygen is absorbed at the same time and place in the process of melting and it is by no means clear why the superiority of semisteel should be assigned solely to its oxygen absorption, when oxygen absorbed without the steel addition is admitted to be injurious. It is not apparent why oxygen caused to be absorbed by the steel addition should not pro-duce the effects of burning, sluggishness, slag inclusions, gas occlusions, etc., the same as oxygen absorbed by the iron in the cupola for any other reason, and it would seen that other factors to which he has not given sufficient emphasis must enter into the author's results. To an impartial reader of this paper, who was most favorably inclined toward J. E. Johnson, Jr.'s theory of the improvement of cast iron by oxygen, the discrepancy in the author's reasoning or statements is difficult to accept, and it is hoped that an explanation will appear in the final discussion.

Jan 11, 1919

By B. J. Dotson, P. N. McCreery, R. L. Slobod, James W. Spurlock

A core sample porosity-check program is described. A number of laboratories participated in the investigation. which comprised measuring the porosities of ten selected natural and synthetic core samples. Each laboratory employed its own method (or methods) of measurement. These included Boyle's Law, water-saturation. and organic liquid-saturation methods. Brief descriptions of each method employed are given. In general, the measured values of porosity were in reasonably good agreement. The average deviation of porosity from the mean or average values for the group of samples was ±0.5 porosity per cent. The results of these measurements are compiled and presented in graphical form. INTRODUCTION The total hulk volume of a porous sample is derived from the sum of two volumes, the void or pore volume and the solid* or grain volume. The porosity fraction of the sample ia defined as the ratio of the void volume to the bulk volume. Multiplication of this ratio by 100 converts it to per cent porosity. Distinction is made here between total porosity and effective porosity. The former includes all void space, both interconnected and isolated, while the latter includes only those voids which are interconnected. This investigation deals only with the effective porosity.* Numerous cases had been noticed in which there appeared to be appreciable discrepancies in the results of porosity determinations on core samples. Differences of as much as 10 to 15 porosity per cent had been reported from different sources

Jan 1, 1951

By P. N. McCreery, R. L. Slobod, B. J. Dotson, James W. Spurlock

A core sample porosity-check program is described. A number of laboratories participated in the investigation. which comprised measuring the porosities of ten selected natural and synthetic core samples. Each laboratory employed its own method (or methods) of measurement. These included Boyle's Law, water-saturation. and organic liquid-saturation methods. Brief descriptions of each method employed are given. In general, the measured values of porosity were in reasonably good agreement. The average deviation of porosity from the mean or average values for the group of samples was ±0.5 porosity per cent. The results of these measurements are compiled and presented in graphical form. INTRODUCTION The total hulk volume of a porous sample is derived from the sum of two volumes, the void or pore volume and the solid* or grain volume. The porosity fraction of the sample ia defined as the ratio of the void volume to the bulk volume. Multiplication of this ratio by 100 converts it to per cent porosity. Distinction is made here between total porosity and effective porosity. The former includes all void space, both interconnected and isolated, while the latter includes only those voids which are interconnected. This investigation deals only with the effective porosity.* Numerous cases had been noticed in which there appeared to be appreciable discrepancies in the results of porosity determinations on core samples. Differences of as much as 10 to 15 porosity per cent had been reported from different sources

Jan 1, 1951

By Frank M. Randall

The Buick mill is located at the site of the old Buick general store, approximately 4 miles south of Bixby, Missouri on route KK. It is a part of the operations in the area now called the "New Lead Belt". The ore body lies at an elevation of 270 feet above sea level, and is fairly flat lying, becoming slightly deeper toward the south. The mineralization is due to the secondary deposition of galena, sphalerite, chalcopyrite, pyrite, calcite, dolomite and some localized drusy quartz in a country rock of dolomitic limestone. The galena is fairly coarse grained with some large crystaline structure, and some oxidized surfaces. The sphalerite is fine grained- small crystals containing Cd (about 0.7%) and Ag (about 10 oz per ton) in solid solution. The chalcopyrite is fine grained, fine crystals that are sometimes massive in nature. The mine plan is a modified room and pillar system. Broken ore at the mine face will be transported to several different ore passes by rubber tired load-haul-dump units. Ore passes will drop the ore to a rail haulage level some 90 feet below the mining level where bottom dump cars will deliver it to a 42 in. Nordberg gyratory crusher. Two 12 ton capacity skips in balance carry the ore some 1,200 feet to the surface. The hoist is equipped with automatic controls for loading, hoisting and unloading.

Jan 1, 1970

By Victor Lenher

The interest shown recently in selenium and tellurium has brought many requests for an assembling of the analytical chemistry of these two elements. The intention of this paper is to discuss all of the chemical principles utilized in the detection and quantitative determination of these elements, as well as to describe the works methods actually followed by producers of tellurium and selenium in the United States. These methods have been furnished by S. Skowronski of the Raritan Copper Works, H. D. Greenwood of the United States Metals Refining Co., F. F. Colcord of the U. S. S. Lead Refinery, and E. W. Rouse and A. E. Hall of the American Smelting and Refining Company. Occurrence Selenium is found associated with sulfur, to which in many respects it is quite similar. Occasionally deposits of native sulfur, notably those in the Lipari Islands, Kilauea, and Japan, show a red-brown coloration, I which is readily distinguished from that of other sulfur; this red-brown * sulfur contains a small amount of selenium. Not infrequently, the , sulfides of the heavy metals are accompanied by selenium and tellurium, • presumably as selenides and tellurides. The Scandinavian pyrite, which is one of the large sources of European sulfuric acid, when roasted has fur- - nished a large part of the selenium that has come to the United States; it I was in flue dust from the roasting of Scandinavian pyrites that the element was discovered by Berzelius in 1817. Greek and Spanish pyrites also

Jan 1, 1923

By Victor Lenher

The interest shown recently in selenium and tellurium has brought many requests for an assembling of the analytical chemistry of these two elements. The intention of this paper is to discuss all of the chemical principles utilized in the detection and quantitative determination of these elements, as well as to describe the works methods actually followed by producers of tellurium and selenium in the United States. These methods have been furnished by S. Skowronski of the Raritan Copper Works, H. D. Greenwood of the United States Metals Refining Co., F. F. Colcord of the U. S. S. Lead Refinery, and E. W. Rouse and A. E. Hall of the American Smelting and Refining Company. Occurrence Selenium is found associated with sulfur, to which in many respects it is quite similar. Occasionally deposits of native sulfur, notably those in the Lipari Islands, Kilauea, and Japan, show a red-brown coloration, I which is readily distinguished from that of other sulfur; this red-brown * sulfur contains a small amount of selenium. Not infrequently, the , sulfides of the heavy metals are accompanied by selenium and tellurium, • presumably as selenides and tellurides. The Scandinavian pyrite, which is one of the large sources of European sulfuric acid, when roasted has fur- - nished a large part of the selenium that has come to the United States; it I was in flue dust from the roasting of Scandinavian pyrites that the element was discovered by Berzelius in 1817. Greek and Spanish pyrites also

Jan 1, 1923

By R. G. Davies, R. H. Richman

Several techniques, X-ray diffraction, transmission electron microscopy, conventional, metallography, and mechanical property measurements are combined to investigate decomposition in the suPersaturated solid solution Fe-27 at. pct Be. The following sequence of structures for aging temperatures below 400°C is established: massive short-range order, pseudo-FeBe (L2o) order, Fe3Be (DU3) order, sinusoidal modulation of composition, general or continuous precipitation, and discontinuous or cellular precipitation. In addition to this sequence itself, several features of the individual stages are noteworthy; for example, when coherent modulations occur, their development is parallel to (100) everywhere in the specimen apparently without incubation, and both the wavelength and the composition amplitude of the modulations increase with aging time. Two types of discontinuous reaction are observed, depending upon the aging temperature. At low temperatures (<550°C) the boundary-nucleated variety of discontinuous precipitate predominates; but at higher temperatures (>600°C) the crystallographic variety occurs instead. Hardness and flow-stress measurements clearly reflect the quoted structure sequence. Some qualitative aspects of the structure changes and of the relationship between mechanical properties and structure are discussed. BERYLLIUM in solid solution markedly strengthens iron.&apos;" A recent study demonstrated that not only were supersaturated single crystals of Fe-27 at. pct Be very strong, but they deformed primarily by mechanical twinning.3 Such behavior, coupled with the decrease in solid solubility of beryllium in a Fe from about 33 at. pct at 1165°C to about 10 at. pct at 500°C4 as shown in Fig. 1, leads naturally to questions about property changes with aging in this system. In 1929 roll,1 and later Seljesater and Rogers,5 reported that useful increases in strength could be obtained by aging quenched Fe-Be alloys, but it was not until quite recently that any of the details of precipitation in these alloys were studied. Richman6 observed that both an Fe3Be superlattice (with a DO3 crystal structure the same as Fe3A1, illustrated in Fig. 2) and a modulated structure preceded the appearance of a discrete second phase in the 20 at. pct Be composition. Here, a modulated structure refers to a periodic composition fluctuation within one crystal, while its lattice remains coherent. Subsequent work on a Fe-Be alloys by Heubner7 and von Heimendahl and Heubner8 confirmed the existence of the modulated structure, although only an FeBe (L20) ordered structure was detected (also shown in Fig. 2). Both Rich-man and Heubner corroborated the large increases in hardness during aging reported earlier, but other mechanical properties were not examined. Since modulated systems are encountered relatively infrequently, the influence of coherent modulation upon mechanical properties is not well-known. With the accumulation of information about age-hardening systems, it has become clear that many precipitation reactions cannot always be described by the concept of heterogeneous nucleation at some lattice discontinuity followed by diffusional growth. Rather, complex sequences involving prior "preparation" of the matrix are quite common; that is, a transition structure occurs in the parent phase, instead of in some "nucleus" form. Delineation of such subtle sequences appears to be a worthwhile step toward the understanding of solid-state precipitation. Since not many structural progressions of comparable nature have been reported, the objectives of the present survey are to identify and elucidate the various

Jan 1, 1967

By James H. Courtright, Kenyon Richard

SILVER Bell is situated 35 airline miles northwest of Tucson, Ariz., in a small, rugged range rising above the extensive alluvial plains of this desert region. Its geographical relation to other porphyry copper deposits of the Southwest is shown on the inset map in the lower left corner of Fig. 1. The climate is semi-arid. Altitudes range within 2000 and 4000 ft. Opening of the Boot mine, later known as the Mammoth, in 1865 was the first event of note in the district&apos;s history. Oxidized copper ores containing minor silver-lead values were mined from replacement deposits in garnetized limestone and treated in local smelters. Copper production had approached 45 million pounds by 1909 when the disseminated copper possibilities in igneous rocks were recognized. Extensive churn drill exploration carried out during the next three years resulted in partial delineation of two copper sulphide deposits, the Oxide and El Tiro. Although the then submarginal tenor discouraged exploitation of these disseminated deposits, selective mining of orebodies in the sedimentary rocks continued intermittently until 1930, providing a production total of about 100 million pounds of copper. The American Smelting & Refining Co. began exploratory and check drilling in 1948 and subsequently made plans for mining and milling the Oxide and El Tiro orebodies at the rate of 7500 tons per day. Production began in 1954 at a rate of about 18,000 tons of copper annually. Formations ranging in age from Pre-Cambrian to Recent are exposed in the Silver Bell vicinity. The more erosion-resistant of these, Paleozoic limestone and Tertiary volcanics, predominate in the scattered peaks and ridges comprising the Silver Bell mountains. The porphyry copper deposits are located along the southwest flank of these mountains in hydrothermally altered igneous rocks. These are principally intrusives which cut Cretaceous and older sediments and are considered to be components of the Laramide Revolution. For three-fourths of its length the zone of alteration strikes west-northwest, Fig. 1. There now is no single structure that accounts for this alignment. However, indirect evidence suggests that a fault representing a line of profound structural weakness existed in this position prior to the advent of Laramide intrusive activity. This line will be referred to as the major structure. It was obliterated by the Laramide intrusive bodies but exerted a degree of control on their emplacement, as evidenced by their shapes and positions. The influence of fault structures on the shapes of intrusives in other porphyry copper districts has been noted by Butler and Wilson&apos; and by others. As shown on the inset map on Fig. 2, a fault of parallel trend and considerable displacement lies to the north. This fault is now marked by a line of small Laramide intrusive bodies. To the south is a third fault of large displacement. Evidence of its age in relation to the Laramide intrusions and mineralization is not recognized, but its conformance in strike with the other two major faults is significant. These three breaks establish a pronounced trend of regional faulting. They are high-angle, and the southerly one may be reverse, Stratigraphic separations on these faults are of the order of several thousand feet. The local Paleozoic section is about 4000 ft thick. It is composed predominantly of limestone with a basal quartzite member. The Cretaceous section appears to exceed 5000 ft. Conglomerates, red shales, and arkosic sandstones (the youngest) characterize the three principal members. Intrusion of alaskite marked the beginning of Laramide igneous activity. It was emplaced as an elongate stock with one side closely conforming to the major structure line throughout a distance of nearly 4 miles. The alaskite was at one time regarded as a thrust block of pre-Cambrian rock&apos;; however, its intrusive relationship and consequent post-Paleozoic age has been established by inclusions of limestone found in outcrops north of El Tiro. The next event was the intrusion of a large stock of dacite porphyry into Paleozoic sediments and alaskite. The stock was some 3 miles wide and at least 6 miles long in a northwesterly direction. It was sharply confined along its southwest side by the major structure line. A number of large pendants of moderately folded Paleozoic sediments occur within and along its southwest edge. Thus the inferred, original major fault between Paleozoic and Cretaceous sediments became a contact between alaskite and Paleozoic sediments and then a contact between dacite porphyry and alaskite. Andesite porphyry may have been intruded later than the dacite porphyry, but relationships are not clear; it may be simply a facies of the latter. The intrusive activity was at this stage interrupted by an interval of erosion. The erosion surface probably was rugged, as there were local accumulations of coarse, angular conglomerate. Subsequently a series of volcanic flows and pyroclastics several thousand feet thick was deposited. A similar unconformity has been recognized elsewhere in the Southwest, particularly in the Patagonia Mountains near the Flux mine some 75 miles southeasterly. Here, as at Silver Bell, volcanics were deposited on an erosion surface cut in Cretaceous and older sediments which had been intruded by alaskite. Though no evidence is offered that closely defines the age of this unconformity, and proper analysis of the problem is beyond the scope of this paper, it is

Jan 1, 1955

By AIME AIME

LEADING off the Thursday morning session on Non-metallics was C. E. Heinrichs&apos; paper, "Phosphate Flotation, Its Place in the Technology and Economics of the Phosphate Industry." Mr. Heinrichs also presented a closely related paper, "Milling Methods and Costs at the No. 2 Concentrator of the Phosphate Recovery Corporation," by H. S. Martin. The first of the papers points out the great significance of flotation to the phosphate industry, inasmuch as flotation practically doubles the potential recovery, thereby decreasing production costs and increasing reserves materially. The second paper describes three such plants, two of which are in Florida, the third being at Wales, Tenn. Operating characteristics and costs are reviewed. Answering inquiries from the floor, Mr. Heinrichs said that the adoption of a new parallel-shell dryer, from 60 to 80 ft. long, instead of the old single-shell countercurrent dryer, had increased the unit drying capacity over 300 per cent and had reduced the drying cost to less than 25c. per long ton of dried product. The initial moisture is from 15 to 18 per cent and the final about 2 per cent.

Jan 1, 1933

By J. D. Miller

The authors have summarized the state-of-the-art in the kaolin clay industry very well. In some instances the problems which they have identified are common to all fine particle separations and in other cases the problems are unique to the kaolin clay industry itself. General areas of research which may be common to other systems and which deserve continued investigation at a higher level of support include: 1) Establishment of the relationship between flotation response and clay structure/composition. 2) Determination of temperature effects in the separation of fine particles. 3) Evaluation of the effect of bubble size on the quality of fine particle separation. The first two areas would require basic surface chemistry studies including microflotation, electrokinetics, adsorption density measurements, and microcalorimetry. The last area would be oriented toward the mechanics of bubble-particle attachment. Regarding the first area, the authors alluded to this research need by commenting on the variation in separation observed from one deposit to another. It seems that a detailed study characterizing the flotation response of various clay types with respect to structure and compositional features would be of considerable value. For example, I understand, that D. W. Fuerstenau&apos;s group has recently been successful in characterization, with respect to structure, of some silicate mineral types--chain, sheet and framework silicates. A similar study should be initiated in which the flotation behavior of various clay minerals kaolinite, halloysite, montmorillonite

Jan 1, 1979

The Institute assembled in the room of the Board of Trade, Mercantile Library Building, on Tuesday evening, May 20th, at 8 o&apos;clock P.M, Hon. W. D. Kelley made an address of welcome to the Institute, which was responded to by President Raymond. The Council reported, through the President, that the Institute had during&apos; the past year, held three meetings, in New York, Pittsburgh, and Boston. Thirty-nine papers of great professional value had been read, and sixty-nine members and twenty-four associates added to the Institute. The finances of the Institute were in good condition, the report of the Treasurer, Mr. T. D. Rand, showing a balance on hand of $1569.74. The report was accepted. Prof. L. Gruner, of Paris, France, and Prof. Peter von Tunner, of Leoben, Austria, having been proposed by ten members of the Institute, and approved by the Council, were unanimously elected honorary members. The Council reported the names of the following gentlemen, with recommendation for election as members or associates. They were unanimously elected. *Barker, Prof. G. F.,.....Philadelphia, Pa. Chalfant, John W.,.....Pittsburgh, Pa. *Crawford, John J.,.....Philadelphia, Pa. *Crusius, O. H.,.Columbus, Ohio. Dibble, Theo. Hoyt,.....Pottsville, Pa. Everson, John,. Pittsburgh, Pa. Field, Robt. P.,.Philadelphia, Pa. *Fisher, F. A.,.Bristol, Tenn. *Fleming, W. E.,.Pioche, Nev. *Harden, E. B ,..Philadelphia, Pa. *Harding, G. E.,.New York. Hartshorne, J.,..&apos;Philadelphia, Pa. Haupt, H., Jr.,.Philadelphia, Pa.

Annual Meeting, Philadelphia May, 1873 THE Institute assembled in the room of the Board of Trade, Mercantile Library Building, on Tuesday evening, May 20th, at 8 o&apos;clock P.M, Hon. W. D. Kelley made an address of welcome to the Institute, which was responded to by President Raymond. The Council reported, through the President, that the Institute had during the past year, held three meetings, in New York, Pittsburgh, and Boston. Thirty-nine papers of great professional value had been read, and sixty-nine members and twenty-four associates added to the Institute. The finances of the Institute were in good condition, the report of the Treasurer, Mr. T. D. Rand, showing a balance on hand of $1569.74. The report was accepted. Prof. L. Gruner, of Paris, France, and Prof. Peter von Tunner, of Leoben, Austria, having been proposed by ten members of the Institute, and approved by the Council, were unanimously elected honorary members. The Council reported the names of the following gentlemen, with recommendation for election as members or associates. They were unanimously elected. *Barker, Prof. G. F., - Philadelphia, Pa. †Chalfant, John W., - Pittsburgh, Pa. *Crawford, John J., - Philadelphia, Pa. *Crasius, O. H., - Columbus, Ohio. †Dibble, Theo. Hoyt, - Pottsville, Pa. †Everson, John, - Pittsburgh, Pa. †Field, Robt. P., - Philadelphia, Pa. *Fisher, F. A., - Bristol, Tenn. *Fleming, W. E., - Pioche, Nev. *Harden, E. B, - Philadelphia, Pa. *Harding, G. E., - New York. †Hartshorne, J., - Philadelphia, Pa. †Haupt, H., Jr., - Philadelphia, Pa. * Members. † Associates.

Jan 1, 1874

By M. D. Voegele, C. Fairhurst

INTRODUCTION A computer study of excavation support loads in tunnels and other excavations in discontinuous rock masses was undertaken with the distinct element method introduced by Cundall (1971). In the distinct element method the rock mass is modeled as a composition of individual blocks of rock defined by the joint planes. Normal and shear deformation laws are ascribed to the joint surfaces; the blocks of rock themselves are considered to be rigid. The particular version of the program utilized in this study ran a mini computer and used inter, active techniques for the input of geometrical data such as joint orientation and spacing and subsequent display of rock mass deformation and other data. Two major aspects of the behavior of excavations in jointed rock masses are examined in this paper: i) the behavior of unsupported excavations in rock masses with varying joint configuration, joint properties and in situ stress fields; and ii) the modification of the behavior of similar excavations when support is provided. In the latter case the excavation behavior was examined through the use of ground reaction curves. THE DISTINCT ELEMENT METHOD The Distinct Element method introduced by Cundall (1971) is a computer based analysis that simulates the behavior of a system of discrete, semi-rigid rock blocks. Block interactions are governed by realistic friction and stiffness laws; each block may undergo unlimited displacement and rotation while progressive failure is modeled.

Jan 1, 1982

By Arthur Taggart

SOME years ago, A. M. Gaudin and one of the authors published a paper showing removal of tar acids from solution by sulfides preferentially as compared to gangues (specifically by galena as compared to quartz).1 The underlying phenomenon was classed as adsorption, and the paper went on to develop the general thesis that so far as water-soluble frothing and collecting agents in flotation are concerned, the phenomenon of adsorption is one of controlling importance. Adsorption was defined in that paper as "a process of rearrangement of a system, which results in establishing a difference in concentration, as between the interfacial layers and the bulk of the phases, of a substance or substances initially uniformly dispersed in one or several of the phases." The paper went on to develop the relation between adsorption and surface energy according to Gibbs&apos; equation (which may be thrown into the form U/c = KdT/dc, where U = excess concentration in surface layer, c = concentration, T = surface tension, and K is a constant), and pointed out that, according to this equation, degree of adsorption and change in surface tension vary directly. The present paper offers a somewhat different definition for the term adsorption; and sets up, in sweeping terms, the generalization that simple chemical reaction underlies the functioning of the flotation reagents which control mineral collection, when these reagents are soluble in and act from solution in the water of the pulp.

Jan 1, 1930

Henry M. Parks, director of the Oregon. Bureau of Mines and Geology, has supplied the following information regarding a recent discovery .of manganese ore in Jefferson County, Oregon, about seventeen miles southeast of the railroad at Eagle Point, a station on the P. & E. Railway. The occurrence is about five miles southeast of Lake Creek Post Office and near the confluence of Lost Creek with the south fork of Little Butte Creek. The manganese ore occurs as psilomelane and pyrolusite, disseminated through a flat bed of volcanic tuff breccia; at a point where the bed was penetrated by a churn drill hole, the thickness of the ore-bearing stratum was 30 ft. Development thus far has consisted of open-cuts, one of which exposes a face about 40 ft. high and 75 ft. broad. Other smaller open-cuts have followed the bed for a. distance of 400 yards. The nodules of manganese mineral vary from a maximum of 25 to 50, lb. down to the size of beans and others as small as mustard seed. These grains, when clean, average from 55 to 58 per cent. manganese. A 12-ft. groove sample in the face of the main open-cut yielded 14.86 per cent. manganese. The peculiar occurrence of the manganese nodules should present but slight difficulty in concentration. A small experimental mill was built last winter, comprising gyratory crusher, rolls, and jigs, which,

Jan 8, 1918

By E. J. Roberts, E. B. Fitch

Most classifiers in use today are, in function, settling pools. A fluid suspension of particles is passed through a pool at such a rate that only a fraction of the particles-the coarser fraction-has time to settle out of suspension. The rest are carried on out of the pool as overflow. The most fundamental way in which such classifiers differ is in the mechanism used to remove the settled particles from the pool. The particles may gravitate from the pool, as in the various sand cones, or they may be conveyed mechanically from the pool by drags, spirals, or reciprocating rakes. The mechanism of settling pool classification and its limitations are discussed. A method for calculating countercurrent classifications is presented. The practical validity of the calculation method has been confirmed through 20 years of use within The Dorr Co. During this time it has been used on diverse feeds and has been checked against many types of settling pool classifiers, with close agreement in nearly every case. Excellent elimination of third critical mesh particles and finer ones may be obtained in a countercurrent classifications series where all stages separate at the same mesh, but elimination of first and second criticals is inherently limited. Spectacular elimination of all criticals may be obtained by arranging successive stages to classify at successively coarser mesh. Improvement in elimination is obtained at the cost of an increased internal recirculation, but this may be tolerable in many cases.

Nov 1, 1956

By Robert Corcoran, George Wiener

A study of the orientations and microstructure of 3 pct Si Fe alloys after deformation and recrystallization has been made. The components found after deformation agreed with recently published work on single crystals, being primarily (001) [110], (111) [110], and (111) {112}. A pronounced effect of temperature of recrystalliza-tion was found on microstructure and orientation. Low temperature recrystallization was interpreted in terms of low angle boundaries which resulted in the retention of a large amount of the deformation texture. High temperature recrystallization was interpreted in terms of high angle boundaries which gave rise to new components. No simple angular relation between the deformation and high temperature recrystalliza-tion textures could be detected. DEFORMATION and recrystallization behavior of 3 pct Si-Fe has been the subject of scientific investigation for many years. The fact that it is a single phase body-centered-cubic alloy from room temperature to the melting point permits study over a wide range of temperature without the complications of phase transformations. There is an important commercial interest in this material as well, since it is widely used in the electrical industry. In the present work the deformation and recrystallization behavior of poly crystal line silicon iron has been studied with the primary purpose of evaluating the effect of a second phase impurity on both processes as well as the effect of temperature on the recrystallization characteristics. With regard to deformation, the emphasis has been placed on a study of the crys-

Jan 1, 1957

George E. Collins, Nacoochee, Ga. (communication to the Secretary): The results tabulated below were obtained at the Reynolds mill, White county, Ga. They were noted, not with a view to investigating the point discussed by Mr. Clark, but in course of a test on a working scale to determine the com parative saving from a given free-milling ore on copper and silvered plates respectively. In every case the bullion assayed was the result of a separate clean-up on a considerable quantity of ore. The ore varied widely in grade and in other respects, but the runs bracketed in the table were made at the same time, in adjoining batteries, and on similar types of ore. In a * Result modified by the addition to the bullion-shipment of a little impure bullion left over from previous clean-ups.. On these occasions, the strips of copper were removed from the tables, and: their lower surfaces were cleaned. Hence the higher yield reported.

Jan 1, 1900

By E. H. Sellards

ON Oct. 9, 1929, a sink formed in the Sour Lake salt dome oil field in Texas, and on Oct. 12 a second smaller sink formed at the north margin of the first. The purpose of this paper is to give such observations as it has been possible to make on the earth movement incident to this subsidence. Sour Lake salt dome is typical of the salt domes of the Gulf Coastal Plain of Texas. Structurally the dome is a plug of salt which rises to within 900 ft. or less of the surface. Above the salt is a cap rock consisting of anhydrite with more or less calcium carbonate. The salt plug, as contoured on the cap rock, is circular in outline with, however, some appreciable irregularities. Overlying the cap rock are relatively uncompacted sediments consisting of sand, clay and gumbo.. At the crest of the dome these deposits are no more than 700 or 800 ft. thick. However, the sides of the dome are steep, and the sediments thicken rapidly away from the crest. The sink formed about 1500 ft. northeast of the crest of the dome where the sediments overlying the cap rock are from 1000 to 1200 ft. thick. The cavity permitting the subsidence was quite certainly either in the cap rock or in the salt below the cap rock, so that the sink was formed by the caving of as much as 1000 or 1200 ft. of earth.

Jan 1, 1930