Search Documents

By S. Korman, S. B. Tuwiner

Chalcocite flotation is affected by agitation intensity during conditioning. Sodium sulphide in minute quantity may activate or depress, depending on conditions. Oxygen is a depressant while oxygen and sulphide neutralize each other by re-action at the mineral surface. Diffusion across a stagnant film at the surface governs reaction rates, while film thickness is reduced upon increase of agitation intensity.

Jan 2, 1950

By J. B. Mackintosh

THE present note is intended as an addition to my previous communication on the volumetric determination of manganese, read at the Roanoke meeting," it having been suggested that the circumstances under which my experiments had been conducted, were essentially different from those met with in the analysis of irons. The method used in these experiments is the same in all its details as that described in the paper referred to. I have made seven experiments in all: two of these were in duplicate on half a gramme of a sample of spiegel dissolved in hydrochloric acid; one was on the same amount of spiegel with the addition of 25 C.C. of a standard solution of potassium permanganate; one was on the same amount of spiegel with the addition of 35 C.C. permanganate and much organic matter, viz., one drop of castor-oil, two or three drops of coal-tar benzol arid of gasolene (petroleum), about ten of alcohol, portions of starch and of sugar about the size of a small pea, and about half an inch of a common match cut into shavings. This organic matter was added to the manganese solution after the hydrochloric acid had been replaced by nitric, and the solution was heated until the wood-shavings had disappeared. The fifth experiment was made by dissolving half a gramme of spiegel alone in nitric acid; the sixth by dissolving half a gramme of spiegel in nitric acid with the addition of 25 C.C. potassium permanganate, some oxalic acid, half an inch of a match, one filter-paper 7 cm. in diameter, and two drops each of castor-oil and turpentine; and the seventh experiment by dissolving half a gramme of spiegel in hydrochloric acid and adding 35 C.C. permanganate, without however taking the precaution to evaporate off all the excess of hydrochloric acid. Under these circumstances, one would expect that if organic matter exercises any influence on the determination, it would be plainly evident in the results obtained. But the accompanying table of results

Jan 1, 1885

By C. H. Wayman, D. W. Fuerstenau

THE gas phase is one of the indispensible ingredients in flotation operations. Flotation depends on the collision of an air bubble and a mineral particle in a pulp and their ability to remain in contact long enough for adherence to take place. Before it is possible to understand the mechanics of air bubble-mineral particle encounter, it is necessary to learn more about the nature of bubbles themselves before collision with a mineral particle has taken place. To date, little work has been done on air bubbles in flotation systems. In 1945 Fahrenwald1 presented a study of the role of frothers on air bubbles and on aeration in flotation, and recently Wark and Sutherland2 discussed the work of Rosenberg3 in relation to flotation. The research reported in this present article was undertaken to investigate systematically the effect of bubble size and the concentration of certain reagents on the terminal velocity, shape, path, and drag coefficient of single bubbles in distilled water. Most of the work is concerned with the effect of a-terpineol on bubble motion in water, but studies were made with potassium chloride, potassium hydroxide, potassium ethyl xanthate, and potassium amyl xanthate.

Jan 6, 1958

By John Gross

A SURVEY of the status of ore dressing in 19231 placed particular stress on the need of research in the crushing and grinding of ore, especially on the need for a method of measuring the surface of the products obtained in crushing and grinding, and for fundamental data on the law of crushing, in order that intelligent conclusions may be drawn from actual crushing or grinding experiments. There has been no satisfactory means of determining the surface of crushed products. The results have been judged entirely by the amount of the various sizes produced, based on sieve sizing for particles above 74 microns in size and on microscopic measurement or elutriation for particles below 74 microns, a method which could give only a general idea of what had been accomplished. The fact that the long controversy between the followers of Kick and of Rittinger has resulted in no accepted conclusion is evidence of the need for fundamental data on the crushing law.

Jan 1, 1928

Six hundred miles inland from Australia's east coast Port of Townsville in Queensland's sea of rock and spinifex lies Mount Isa. The town, as in most mining towns, is dominated by its mine and the mine in turn is dominated by its 503 ft copper smelter stack. This candy and white painted stack is a striking introduction to one of the world's greatest copper producing mines and a town where people of over 40 different nationalities live remote but well. Mount Isa Mines Limited is surging into the ranks of' the world's great mines on the momentum of a relentless push begun in 1956. It is as if the time lost in the lean years of the past should be caught up in a hurry.

Jan 10, 1964

By M. E. Volin, D. W. Fuerstenau, A. L. Mular

This paper presents the results of an investigation of the effect of feed size on the integral rate at which feed material is dry ground in a laboratory rod mill. The data are interpreted in terms of the Gaudin-Meloy distribution equation. The equation, Mo — Mt/t = Aoxo r-1, is found to hold for feed sizes smaller than some critical size or for grinding times larger than some critical time. It is shown that a feed grindability is related to this critical size, which appears to be the transition between predominately impact and predominately attrition grinding. Detailed research on feed size effects in comminution has been rather limited. Gaudin1 ground single-sieve fractions of quartz for extended time periods (four hours) in a laboratory ball mill. His work, which was designed to study the nature of size distributions, showed that there is a critical feed size above which comminution occurs primarily by attrition. For his system, the critical size was about 2-mm when using 22-mm balls. In a more recent investigation2 single-sieve fractions of quartz were ground in a laboratory rod mill for constant time periods (15 min) to determine how feed size affects the grindability of the material. This work showed that grindability is essentially independent of feed size in the rod mill after this moderately long grinding period. To further clarify this observation, a study in which feed size and grinding times are varied over a fairly wide range, and particularly, a study of the dependence of the integral rate of grinding on feed size during the initial stages of rod milling is necessary. For an analysis of such data, it is desirable to use a parameter which is very sensitive to change during the initial grinding period when reduction ratios are

Jan 1, 1964

By Nichols J. Grant, Bill C. Geissen

In low temperature phase diagrams, liquidus curves below about 1500°C are relatively easily established, e.g., by thermal analysis or separation of coexisting solid and liquid phases, followed by chemical analysis. Experimental difficulties increase considerably at higher temperatures and in systems involving more reactive metals. Although there are now thermocouples available for use from 1600" to 2400°c, as summarized by Caldwell,' the need for frequent calibration, aging, and contamination problems, and unavailability of suitable protection tubes has sharply limited their use at higher temperatures. Many of the high melt- ing metals are found to react with refractory oxides. TO avoid such problems, a frequently used procedure is the diffusion and saturation method, as described by Spedding et a1.' for the system La-C. This technique involves the annealing of one metal or a suitable alloy in a crucible of the other element at a temperature above the melting point, followed by chemical analysis of the center of the melt, after equilibrium is established. Further, if an alloy system is to be investigated employing the electron microbeam probe, and calibration charts have been established, it may be possible to measure the alloy concentration at the center of a cored as-cast structure, and to conclude from this points on the liquidus curve in a manner similar to the one to be described. It is known that in phases with a broad homogeneity range the rapidly cooled, cored, as-cast structure of an alloy presents concentrations having different lattice constants; this spread of lattice constant values contributes to the broadened lines of a powder pattern for the as-cast condition. The region of the crystal which is first to solidify will then correspond to the edge of the lines if the change of the lattice parameters with concentration is monotonous. In the course of the determination of the Ta-Tr phase diagram,3 it became evident that such behavior made it possible to construct the

Jan 1, 1963

By L. P. Teas

The main facts brought out by the study of the blende-bearing ores examined are as follows: 1. Chalcopyrite as minute triangular or rectangular dots, or as

Jan 1, 1918

By Charles Morgan

AN increased demand for brown iron ore in the Birmingham district during the past 18 months has caused renewed activity both in prospecting and mining these ores. In recent years the production in Alabama has ranged from 41,559 tons in 1932 to 639,351 tons in 1928. During the last 9 years about 83 per cent of the total brown ore produced in the United States has come from Alabama (Tables 1 and 2). PROSPECTING Two methods of prospecting are used in this district: (1) test pits, (2) churn-drilling. Usually there is certain quite definite information on an area to be prospected; some of the indications are float ore such as small gravel or small and large boulders known as "dornicks" scattered over the surface, and ore exposed by erosion in gulleys and ravines, which have cut or eroded through the overburden. Often these natural erosions furnish an indication of the thickness of the ore and to some extent of the area of the ore body.

Jan 1, 1937

By W. R. Ingalls

During the last two years, and especially during the last six months, a number of important articles upon the new methods for the desulphurization of galena have been published in the technical periodicals, particularly in the Engineering and Mining Journal and in Metallurgie. I proposed for these methods the type-name of " lime-roasting " of galena as a convenient metallurgical classification,'and this term has found some acceptance. The articles referred to have shown the great practical importance of these new processes, and the general recognition of their metallurgical and commercial value which has already been accorded to them. It is my present purpose to review broadly the changes developed by them in the metallurgy of lead, in which connection it is necessary to refer briefly to the previous state of the art.

Jan 1, 1907

By E. I. Larsen, F. R. Hensel

According to statements by Guertler1 Smith and Hamilton were the first to study the copper-titanium alloys, but owing to the presence of large amounts of impurities their data are inconclusive. M. A. Hunter and I. W. Bacon later investigated the electrical conductivity and the temperature coefficients at room temperature. The present writers reported their results2 in November, 1930. Recently Kroll published data on copper-titanium alloys3 which agree closely with those obtained by the authors. Material Tested The titanium used was in the form of square sintered rods, the analysis of which runs as follows: titanium, 95.4 per cent; silicon, 0.7; iron,l.8; aluminum, 1.4; copper, 0.1; manganese, 0.05. The ingots were prepared in a high-frequency induction furnace in air atmosphere. Their analyses are given in Table 1. Up to 5 per cent titanium the alloys could be forged. Above that amount they were red short and broke up easily. Owing to their rapid absorption of nitrogen and oxygen from the air, the alloys with the higher amounts of titanium tend to form surface films which greatly increase the casting difficulties, especially when small masses of metal are handled. It was, however, possible to prepare sound ingots up to 25 per cent titanium. Thermal and X-ray Investigation The cooling curves of some of the alloys are plotted in Fig. 1, and R tentative diagram constructed from these data is given in Fig. 2. From this it is evident that the solid solubility of copper for titanium is approxi-mately 4 to 5 weight per cent titanium at 878" C., which is the eutectic temperature. The melting point of copper is lowered gradually by adding

Jan 1, 1932

By A. C. Dorenfeld

ORES of the Mammoth mining district, some 45 miles northeast of Tucson, Arizona, are treated by Mammoth-St. Anthony, Ltd. The ores now treated come from a complex system of veins and faults, comprising three mines, in close proximity: The Mohawk, Mammoth and Collins. The ore treated in the past was oxide ore, which contains economic amounts of gold, silver, lead, molybdenum, and vanadium (as wulfenite and vanadanite). The lead-zinc sulphide ore has never been treated before. THE ORE The sulphide ore contains galena, sphalerite, marmatite, pyrite and some chalcopyrite, covellite, chalcocite and bornite, as well as small amounts of gold and silver. The value of the ore is principally in the lead and zinc content. The lead-zinc sulphides are substantially liberated at a minus 65-mesh grind. However, a large part of the chalcopyrite and other copper minerals is not freed, but remains as pin points on the sphalerite. Economically, the copper is unimportant. The gangue is a rhyolite granite, with very little limestone. There is no molybdenum or vanadium in the sulphide ore. HISTORY OF SULPHIDE TREATMENT Test work on samples of the sulphide ore was conducted by several equipment companies, the Arizona Bureau of Mines and the company's laboratory. Results of this test work indicated that for some reason, which at the time could not be explained, recoveries would be only about 65 per cent lead and 50 per cent zinc. Not-withstanding this, because of the nation's need for metals, the management built a 150-ton treatment plant. The mill was started in June 1942. During December 1942, using the standard method of treating lead-zinc ore, the monthly results were as shown in Table 1. These results were poor. Too much lead was in the zinc concentrate, and too much zinc in the lead concentrate. [ ] It should be noted here that prior to December attempts were made to depress the sphalerite with large and varied amounts of cyanide, zinc sulphate, and sodium sulphite with poor results.

Jan 1, 1944

By M. Bourgon

The conductivity of liquid copper sulfide has been measured as a function of the mole fraction of sulfur in the melt at three temperatures: 1170°, 1250°, and 1300°C. The results show that a) the conductivity of copper-rich Cu,S is independent of the sulfur pressure in the furnace, and b) the conductivity of sulfur-rich copper sulfide increases rapidly with sulfur pressure. Assuming that the band theory is applicable to liquids leads to the conclusion that copper-rich copper sulfide is an intrinsic semiconductor, in which case electrons act as carriers. The activation energy for conduction in this case has been calculated to be 0.7 ev. On the other hand, sulfur-rich copper sulfide behaves as a p-type semiconductor, positive holes being responsible for conduction. IN order to elucidate the structure of Liquid copper (1) sulfide, Derge, Pound, and Osuchl have studied the electrical conductivity of this compound as a function of temperature. Their results showed that the conductivity is rather high, of the order of 100 ohm" cm", and that the temperature coefficient of conductivity is positive. This high conductivity seemed to indicate electronic rather than ionic conduction. This conclusion was checked further by Derge, Pound, and Yang,2 who measured the current efficiencies of copper sulfide melts at various temperatures. In all cases, the current efficiency was found to be nil, indicating the absence of appreciable ionic contribution to the conduction in

Jan 1, 1958

By P. F. Ahner, Leonidas Petrakis, Fred E. Kiviat

High gradient magnetic separations (HGMS) is a recently developed technique in which magnetic micron-size particles contained in a flowing fluid medium can be extracted from that medium. HGMS is presently utilized on a commercial scale in the kaolin processing and steel industries, and is being investigated for solid-liquid separations in numerous other processes. The performance characteristics of HGMS in the kaolin and steel industries are briefly summarized. A discussion of HGMS performance with respect to solids removal in a coal liquefaction process is presented to illustrate its applicability to difficult solid-liquid separations. Here, the properties of the solids suspended in the liquified coal are such that the HGMS separator achieves over 90% solids removal. The optimization of the HGMS operating parameters to yield these results will be discussed. To further illustrate the potential of HGMS, its performance with respect to the removal of oil and solids (over 98% removal) from a petroleum refinery process water effluent stream will be briefly considered.

Jan 1, 1980

Key elements of open-pit design fixing the ultimate pit limits are stripping ratio, pit slope angle, and grade cutoff. Results of exploratory and development drilling should be reduced to horizontal sections corresponding to level spacing. It is advisable to interpolate the actual drillhole values to a uniformly spaced 50-ft grid system. Vertical sections can be and are used to approximate the fixing of pit limits, but horizontal sections must be used to optimize a pit design. To develop a pit design requires the establishment of the break-even stripping ratio. This ratio is applied only at the surface of the final pit and must not be confused with the over-all ratio, which is always less; otherwise there would be no profit in the operation. The break-even stripping ratio is determined by the formula: [ ]

Jan 10, 1967

By George B. Clark, John W. Brown, Hemendra N. Kalia, Ronald R. Rollins

A new theory for three dimensional collapse of conical liners shows why the two dimensional theory may offer a good approximation. Shaped charge design parameters and rock target properties were investigated to determine their effects on penetration and breakage. Penetration in dolomite is somewhat similar to that in steel, but copper does not have markedly better penetration capabilities than brass. Several metals, liner thicknesses, cone angles and standoff ranges for each were investigated. Effective standoff is greater for aluminum than more dense metals. Optimum geometry appears to approximate that for metal targets. Resistance to penetrations was greatest for a red granite and dense siliceous rocks, and least for dolomite and porous sandstone. Hardness and compressive strength appear to be two important conventional proper- ties. The first order law does not apply to the rocks tested. Dolomite may be drilled with shaped charges, the holes sprung and round blasted successfully.

Jan 1, 1971

By Walter P. Jenney

In the limestone area of Tintic and other mining districts of the Great Basin region of Utah, it has been observed that surface-outcrops of ore occur but seldom, and are mainly confilled to points of relatively low elevation, where the veins cross some basin or ravine. Nowhere does a considerable body of ore outcrop on the tops or high up on the slopes of the hills. Mining operations, on the other hand, have shown that large and continuous ore-deposits frequently occur in depth in the limestone, beneath large masses of barren rock. Such orebodies, when followed upward in the lodes, are found to terminate at well-defined levels, without reaching the surface. Yet the minerals-bearing fissures themselves extend above the top of the ore, being often traceable, though barren of all valuable minerals, for hundreds of feet above the stopes in the mines, and even observable in outcrops at the surface. This abrupt cessation of the ore at a uniform horizon does not appear to be connected with any change in the countryrock adjacent to the lodes. The strata above and below this horizon seem to be in every way equally favorable to ore-deposition. Explorations above it have developed an open-fissured country, barren not only of ore, but also of indications that minerals bearing gold, silver, lead or copper were ever deposited in the strata at that elevation. The height reached by the ore, while usually constant throughout the length of a given lode, may vary in particular sections, from the operation of local causes. Each lode in a district has its own distinct horizon, above which the oredeposits do not extend. Where the ore-bodies are continuous

Jan 1, 1903

By John Birkinbine

The press, trade publications, and special circulars, some elaborately illustrated, have been liberally employed within recent years in this country, to set forth the advantages of various locations as industrial centers, having as a basis the possibility of profitably producing pig-iron at these proposed centers: and special stress has been placed upon opportunities believed to exist at certain points for making iron of a quality suitable for the manufacture of Bessemer steel. The remarkable statements and prophecies made in some of these publications, have suggested the present paper, treating of the influence which location exerts upon the special industries named.

Jan 1, 1893

By R. B. Sosman, J. C. Hostetter

We have shown in the preceding paper that practically all natural oxides of iron contain a determinable percentage of ferrous iron, and in many cases the percentage approaches that in magnetite itself. Some of these oxides are true homogeneous solid solutions. Others are not homogeneous, and can be separated magnetically into fractions. The nature and cause of this inhomogeneity in certain special cases form the subject of the present paper. Magnetic FRactionation of Oxides of Iron The magnetic fractionation of a sample of oxide can be conveniently carried out by powdering the material very fine, and exposing it at various distances from the poles of an electromagnet. The magnet that we used was specially designed1 to give a strong field together with a steep gradient outside of the poles. It is set in a frame, with the pole pieces directed downward. A glass plate can bc adjusted at various distances beneath the poles. If the fine iron oxide powder is placed just beneath the glass plate, successive portions of the powder are picked up by the magnetic attraction and are caught against the glass plate, the most magnetic portions being taken up at the greatest distance from the poles. Some natural oxides can thus be separated into several fractions of different magnetic susceptibilities. Among other natural iron oxides, we examined the powder obtained by crushing some crystals of hematite from Elba.2 We found that

Jan 1, 1918

By AIME AIME

NO other man now on the Institute's Board has a record of long service to his professional society comparable with that of Karl Eilers. He joined in 1888; he was a Councilor as far back as 1909, a Vice-President as early as 1912, and for the last ten years has been continuously a Director and Treasurer. It seems fitting, therefore, that he is the only member of the present Board that is also an Honorary Member of the Institute. Karl Emrich Eilers was born near Marietta, Ohio, Nov. 20,,1865, which makes him 71 years old. Columbia School of Mines gave him his E.M. in 1889, after which

Jan 1, 1937