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By A. U. Seybolt, F. J. Norton

A standard technique for heat treating small metallurgical samples where no appreciable contamination from the atmosphere can be tolerated is that of sealing small samples in evacuated fused-silica tubes. Since vitreous silica is relatively impervious to diffusion of gases, even at temperatures approaching the devitrification range, around 1100°C, this simple procedure has been very widely adopted as a standard technique in metallurgical research. Many workers have recognized that, with metals of fairly high reactivity, insulation from direct contact with the SiOz envelope is desirable in order to avoid displacement reactions of the type M + SOz-- MOz + Si(in M). It is not so generally known, however, that the 'rate of permeation of oxygen from the air through the SiOz enclosure at tem-

Jan 1, 1964

By M. Lastra, A. Cruz, J. Menacho

The use of phosphates was studied as a way of purifying acidic copper leach solutions for direct electrowinning. The addition of 2.5 gpl phosphorus to plant solutions originally containing 6.25 gpl Fe (III) at pH 2 0 reduced the iron concentration by one half. Under identical conditions, but without phosphorous additions, the iron concentration was reduced by less than 1 gpl. Any residual phosphorous had no undesirable impact on electrowinning. The concentration ratio of Fe (III) to phosphorous which provides maximum iron elimination was determined. Higher ratios bring about a redissolution of the iron precipitate. Several ways of controlling iron with phosphates are discussed. These take advantages of more rapid and complete iron precipitation at lower pH levels.

Jan 1, 1980

By Andrew W. Jenike

An efficient storage plant contains a known available volume of bulk solid, and feeds it at the required time, the prescribed rate and without degradation of the product. A storage bin may also perform other functions, such as blending different grades, degasifying aerated powders and isolating different gaseous media. A contact bed of particles flowing by gravity in counter-current with a gas or liquid may be used as a continuous reactor. In order to design an efficient storage plant or contact-bed reactor, it is necessary to be aware of the problems which can arise in flow and storage. The typical problems are no flow, erratic flow, flushing, insufficient flow, lack of designed capacity, segregation, degradation of the product and level control.

Jan 5, 1968

By J. E. Campbell, G. D. Calkins, N. M. Ewbank, M. Pobereskin, A. Wesner

GRINDING for size reduction affects the economics of many processes and products. It is essential as the first step in many industrial processes and is also a finishing step for materials with properties depending on particle size, such as talc, cement, and silica sand. Intermediate and fine grinding are vital operations in the U. S. cement industry, which is producing more than 250 million bbl of cement per year.1 Wear of the grinding media is a large part of the grinding operation cost. Problems encountered in grinding cement are so complex that evaluation of efficiency and economy of grinding media is difficult.2 It has been especially difficult to evaluate the relative effectiveness of different types of balls because there are no good testing techniques.

Jan 12, 1957

By William S. Springer

A NEW preparation plant has been put in operation to treat coal from the recently opened Concord mine, located about 15 miles west of Birmingham, Ala., by the Tennessee Coal, Iron & Railroad Co., a U. S. Steel subsidiary. The mine produces metallurgical grade coking coal from the American seam for use as coke in the company's blast furnaces at the Fairfield and Enseley works. The capacity of the operation is 1000 tons of run-of-mine per hr, approximately half of which is delivered to the by-product coke plant at Fairfield after beneficiation to metallurgical grade. The remaining portion of the mine run is rock and refuse removed during preparation. No boiler coal or other fuels are produced by this mine.

Jan 12, 1950

By Douglas W. Fuerstenau, Kalanadh V. S. Sastry

Mathematical considerations of green ball growth in a balling device by the mechanisms of layering new feed onto seed or recycle pellets are presented. An experimental procedure was developed for investigating the agglomerate growth by layering in which the addition of feed to a batch of seed pellets was made cyclically. Using this procedure, the layering growth mode under partial feed consumption and no seed generation conditions was investigated experimentally in a laboratory balling drum as a function of such operating variables as moisture content of the material, feed rate, and the size distribution of the seed pellets. The experimental results were analyzed in the context of the model equations and the layering growth constant was estimated as a function of the operating variables.

Jan 1, 1978

By William C. Peters

The experiences of exploration crews with mineral land acquisition could be graphed to show a correlation with the natural law that everything tends to become more so. A single step, such as that of taking a series of deep soil samples, is sometimes delayed until some sense can be made from floating unpatented claims which are obscure in orientation as well as position-placer claims, overlapping lode claims, location posts with empty Prince Albert cans and claims with no apparent assessment work for ten years. Add to this some patented claims without monuments, a state or federal withdrawal area which may or may not invalidate preexisting claims, a loosely defined tunnel site, and some ranchers who understandably resent the separation of surface rights from mineral rights.

Jan 1, 1970

By W. E. Newberry

The Aspen Mining District is situated at the eastern edge of the system of stratified rocks of western Colorado, where this edge meets the ridge of metamorphic granite which divides the State into two unequal parts. In following the valley of the Roaring Fork westward from the continental divide towards Aspen, one passes through a country of granite and gneiss, with no sedimentary rocks until the town is nearly reached. At this point the Cambrian quartzites first make their appearance, lying on the granites, with a dip of from 30' to 45 to the northwest. Beyond these quartzites and conformably upon them lie dolomites, limestones, shales, porphyries and sandstones, gradually flattening in general dip as one proceeds westward, but much disturbed by local foldings and faultings.

Jan 1, 1890

I have attended these meetings, every year, since 1926 and have served on both the Pittsburgh and the National Executive Committees, so that I am fully aware - of the ruling of this organization regarding, "No Papers by Vendors". Since I am now classified as a VENDOR, I wish to express my sincere appreciation for the invitation to formally discuss these very interesting papers --all of which herald the coming of an entirely new era in the manufacture of quality steels. I also appreciate the references by Mr. Mosser and Dr. Swinkels to my first paper on the oxygen probe which was presented at the meeting of this group, here in Chicago, in 1966 and was subsequently published in the NOH Proceedings of that year. (1)

Jan 1, 1972

The recent dedication of Magma Copper Co.'s San Manuel, Ariz., electrolytic copper refinery and rod casting plant marks the culmination of a three year, $250 million expansion-modernization program. The new facilities will eventually permit an annual production of 200,000 tons of marketable copper for direct sale to fabricators. The Newmont Mining Corp. subsidiary will produce and market continuous cast 5/16 in. copper redraw rod, full plate cathode copper and sheared cathode plate under its own brand name. Among the four largest in the nation, the new refinery and plant, was built at a cost of $34 million and will be fully automated. In addition, all materials used in the plant will be recycled and no waste, discard or emissions will occur.

Jan 3, 1972

By Fred D. DeVaney

Probably no ferrous metallurgical process has ever found such ready acceptance and rapid expansion as the pelletizing of iron ores. The process was first commercialized in the early 1950's and since then it has grown to the point where the amount of material pelletized worldwide will approach 100 million tons in 1971. The term agglomeration is used to describe any process by which fine material is formed into larger shapes or agglomerates and includes, in addition to pelletizing, such processes as sintering and briquetting. Sintering cannot be used to efficiently agglomerate iron materials containing a high percentage of 100-mesh fines but the method has been widely used over many decades for agglomerating flue dust, mill scale and iron ore finer than 3/8 in.

Jan 1, 1971

By J. M. Karpinski, F. P. White, R. L. Stone

By means of laboratory balling tests and a procedure for determining bentonite concentration in a green ball, the present study revealed that the bentonite savings by mulling concentrate and bentonite prior to balling was sufficient to warrant installation of a full-size unit in a pellet plant. On the basis of this work, a muller was put on stream at Bethlehem Steel Corp.'s Cornwall pellet plant in June 1969, and has operated continuously since then. Plant tests showed that the use of the muller resulted in bentonite savings of about 50% without any loss of green, dry, and fired ball quality. Virtually no maintenance problems have been encountered. This information is important to future pelletizing operations both from the standpoint of product quality and economics.

Jan 1, 1972

By Rixford A. Beals

It has been observed with considerable accuracy that if the major U. S. mines were moved to Mexico tomorrow, many of them would be losing money. But the companies would continue to operate, losses or not, because they would have to. And some of the newest and most promising low grade ore projects in the U. S. would never have "gotten off the ground" had they faced the equivalent of the mining taxes now in effect in Mexico. No one of the various mining taxes in Mexico seems prohibitive by itself. Taken together, on the balance sheet, however, the picture changes. Production and export taxes alone take from 20 to 40 pct of the gross product value for base and precious metals.

Jan 2, 1955

By Fred C. Bond

IN crushing and grinding the larger particles are more exposed to the work input. They absorb most of the work and protect the smaller neighboring particles from destructive contact with the crushing surfaces or grinding media. The importance of this exposure differential upon the reduction efficiency and product size distribution has long been recognized. Unfortunately, there has heretofore been no direct method of evaluating it, and such indirect methods as observing the slope of the plotted product size distribution line have been used as an indication. In this presentation the Third Theory of Comminution1 has been used, together with the exponential formula for size distribution, to evaluate the exposure ratio and exposure constant and to illustrate examples of their utility in crushing and grinding applications.

Jan 12, 1957

Two 6.17-m-diam (20.25-ft) shafts, said to be the largest ever opened with mechanical raise boring techniques, were completed in May and June 1978, at Monterey Coal Co.'s No. 1 mine near Carlinville, Ill. According to the shaft contractor for the project, Frontier-Kemper Constructors, the openings are 60% greater in cross section than the largest previous raise-bored shaft, which had a diameter of 4.85 m (16 ft). Both vertical shafts are 93 m (305 ft) in total depth, with the upper 28-30 m (90-100 ft) sunk and lined by conventional methods through unconsolidated overburden and the remainder mechanically bored through sedimentary rock. The two shafts will be used for service access as well as to augment ventilation.

Jan 12, 1978

By S. C. Termes, P. E. Richardson, R. L. Wilfong

This paper discusses recent Federal Bureau of Mines research on the selective flocculation of various minerals with insoluble cross-linked starch xanthate (ISX). ISX is insoluble, has a shelf life of more than a year when kept cold, and has a higher molecular weight due to cross-linking than the soluble, non-cross-linked starch xanthate used in previous flocculation studies on nonsulfide minerals. ISX readily flocculates a number of sulfide mineral fines, but no silicious gangue. Floc formation, floc size, and settling rate are dependent on pH. The pH dependence, however, differs for each mineral. Bornite has been selectively flocculated from bornite-quartz mixtures, and the bornite-containing flocs were separated from the unflocculated quartz using decantation and washing procedures.

Jan 1, 1984

By A. Patton

E. T. McCLEARY, Youngstown, Ohio (written discussion).-Perhaps there is no question before the steel manufacturers of America today that causes them more worry than that of maximum production, together with good quality, and Messrs. Patton and Speller have clearly shown in their excellent paper how this may be accomplished. Any operation that tends to uniformity is certainly conducive to good practice, and as the use of roll scale in the converter eliminates to a large extent the variations in temperature due to varying silicon content in the pig iron, it should certainly give a more uniform product. At the plant of The Youngstown Sheet & Tube Co. the use of roll scale was started in the year 1908. A great many tests have been con-

Jan 4, 1917

By Edward Halse

Normal banded structure,* exhibiting bands or layers of mineral symmetrically arranged from the sides to the center of the vein, appears to be by no means common in the Republic of Mexico. When the bands of quartz form interlocking crystals in the center (" comb-structure "), the evidence that the filling has taken place in an open space is complete. This also applies in the case of any mineral the fibers of which are perpendicular to the walls, and which presents here and there, in a central line, cavities or vugs lined with crystals (geodes); but it does not follow that the whole width of the banded vein represents that of the original open fissure. The opening and filling may have been slow and gradual processes, advancing

Jan 1, 1902

By Paul W. Jeran, Vladimir Adamek

Characteristics of surface deformations i.e., sub¬sidence, inclination, curvature and horizontal strains, are evaluated, based on information obtained by direct field measurements over three longwall panels in the Northern Appalachian Coalfield. Surface deformations have been precomputed using Bals' and Knothe's theories. The results have been compared with Bureau of Mines field data to evaluate the applicability of the two theories to the U.S. min¬ing conditions. Measured horizontal movements and the resulting horizontal strains differ as much as 300 percent from precomputed values. Topography has no detectable effect on vertical movements but appears to have substantial effect on the development of horizontal strains. The horizontal deformations computed from our field measurements generally exceed the limits used in other countries to protect surface structures.

Jan 1, 1982

By William Buell

As used in connection with open-hearth or other high-temperature operations, "insulation" refers to a multitude of substances, natural or manufactured, that have the one principal property of preventing the flow of heat by conduction to a greater degree than refractories can prevent it, the principal properties of the latter being resistance to tem-perature and/or chemical action. The term "control" as commonly applied to the mechanization of management functions is inappropriate without qualification, for without some degree of control of every operation we could produce no steel worthy of the name. Although grouped together in this paper, insulation and control in open-hearth furnaces have little, if any, interrelationship, therefore the paper is made up of two distinct parts.

Jan 1, 1935