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ALTHOUGH it might seem more fitting to discuss this subject in the Ninth Book in connection with the smelting of iron where I had thought to treat of it in detail, this process of making steel appears to be almost a branch of the above chapter on iron itself; hence I did not wish to separate these two so far that they might seem to be [18v] different things. Therefore I wish to write of it here and to tell you that steel is nothing other than iron, well purified by means of art and given a more perfect elemental mixture and quality by the great decoction of the fire than it had before. By the attraction of some suitable substances in the things that are added to it, its natural dryness is mollified by a certain amount of moisture and it becomes whiter and more dense so that it seems almost to have been removed from its original nature. Finally, when its pores have been well dilated and softened by the strong fire and the heat has been driven out of them by the violence of the coldness of the

Jan 1, 1942

Jan 1, 1917

By J. B. Novak

The program describes preventive maintenance practices and controls applicable in situations where maintenance actions are triggered primarily by breakdown or part failure and specification and documentation of detailed maintenance practices are minimal or nonexistent. The presentation describes requirements of organization structure, program administration, implementation and operation, type of benefits expected, and actual benefits derived in selected areas. The principle objectives of the program are to provide quick, inexpensive, and effective controls over maintenance practices and requirements and to establish a nucleus of controls that subsequently can be expanded to cover all maintenance activities.

Jan 1, 1973

By R. O. Burt

The economics of recovering slimes by gravity concentration, except in a few highly specialized cases, was hampered by the lack of suit- able high capacity equipment. However, in the last decade increasing cost of power and reagents, coupled with the development of high capacity units, has led to a reappraisal of the benefits of slime gravity concentration. This paper seeks to analyze the merits of gravity concentration, and the constraints placed upon it by the laws of motion. It traces the recent developments of unit processes, and their application to a wide range of minerals. The economics of gravity concentration are also discussed.

Jan 1, 1980

By William J. Potter

The current financial environment differs markedly from past commodity price expansions, which have benefited the mining industry. Deregulation, financial innovation, and the globalization of capital markets in the 1980s have altered financing and investing patterns. Investment bankers and smart money within the industry have recognized the alterations and trends that facilitate fee revenue and profitable growth. This paper profiles transactions exemplifying change and documents financing techniques or instruments that have developed during the past half decade, emphasizing equity in the global marketplace.

Jan 1, 1990

By Dirk van Zyl

The paper describes the construction of a clay pad in Southern California. The pad consisted of a mixture of in situ soil and imported clay products. The paper summarizes design considerations. Laboratory permeability tests performed on samples removed from the pad formed part of the quality control requirement of the State of California Water Quality Control Board. The paper presents statistical analysis of the data (about 70 permeability tests in total) and their significance in controlling seepage losses. The results obtained from an investigation of the first pad-area after completion of the leach cycle are presented and discussed. Results from visual observations and laboratory tests are presented.

Jan 1, 1984

By E. D. Gardner

In 1954, the first year the award was conferred, Fred Searles, Jr., remarked, "The earlier years are the easiest." In this, the second year, it was easy to choose the outstanding mining engineer. Our conferee this year has been destined to mine. He comes from pioneer stock, and though a son of the American Revolution he is most proud that all four of his grandparents came to the Jordan River Valley of Utah the "first summer," which all Utahns will recognize as 1847. At the time of discovery of high-grade ore in Bingham, his grandfather, Archibald Gardner, had a crew of men getting out saw timber in the area. The first claim staked in Bingham Canyon was named the Jordan, and Bishop Gardner was the colocator of the claim as well as the man to record it.

Jan 4, 1955

By S. A. Lever, R. Hultgren

The solidus is usually the least satisfactorily determined portion of a phase diagram. Cooling curves, which succeed well with the liquidus, show the solidus inaccurately or not at all because of segregation which occurs during freezing. Heating curves of carefully homogenized alloys might be expected to indicate accurately the solidus, but they are seldom used. Dynamic methods involving heating or cooling are never completely satisfactory because of uncertainty as to whether equilibrium is attained. A static method in which the specimen may be allowed hours, days, or even weeks to attain equilibrium is to be preferred. In a static method a solid solution, for example, is first made thoroughly homogeneous, then heated to successively higher temperatures. After sufficient time at each temperature to assure equilibrium, some property is measured which should alter strikingly when melting begins. Microscopic examination can be used to detect the beginning of melting, but the method is tedious since the specimen must be quenched, sectioned, polished, and etched before each examination. Of all the physical properties which change on melting, electrical resistance is probably the most satisfactory to measure. The measurement may be made while the specimen is at temperature without damage to the specimen. It may be repeated indefinitely to ascertain when equilibrium has been achieved. Measurements may be made on a single specimen over the whole range of temperature. Most metals approximately double their resistance on melting. Since an accuracy of a few tenths of a percent is easy to achieve, the method is highly sensitive to the beginning of melting. In spite of these advantages, which have been perceived for a long time,l,2 a reasonable search of the literature has failed to reveal a single case in which the method has been satisfactorily applied in practice to the determination of solidus temperatures. The use of electrical resistance measurements appears to have been confined in practice to changes in the solid state. In the work described in the following pages we have applied the electrical resistance method to the solidus of the lead-tin system. We have found the method to be convenient, reproducible, and highly sensitive. We chose the lead-tin system because it leads to few technical difficulties. Furthermore, a number of determinations of solidus have been made in this system by various methods and results could be checked against them. However, all published results are not in good agreement with one another, so this work should help in determining the solidus more precisely. The Lead-tin Diagram Because of its commercial importance, there have been numerous investigations of the lead-tin diagram. The results of the most recent work on the solidus are indicated in Fig 7, as well as the results of the present work. The works of Honda and Abe3 and of Stockdale4 agree fairly well with each other and with the present work. Jeffery's5 data indicate the solidus to be about 50°C lower. Honda and Abe3 used differential thermal analysis on both heating and cooling cycles. Stockdale4 used the microscopic method and also differential heating curves. Stockdale's results were about 4" higher than those of Honda and Abe at low tin contents and lower at higher tin contents. These results also agree with those of Rosen-hain and Tucker.= Jeffery5 used electrical resistance measurements of the alloy as it was being heated or cooled. Apparently he did not attain equilibrium as his results are about 40°C lower than those of Stockdale4 or Honda and Abe.3 MATERIALS AND METHODS The lead and tin used were of high purity. They were supplied by the American Smelting and Refining Co., who gave the following analyses: Lead: silver, 0.0016 oz per ton; copper, 0.0008 pct; cadmium, 0.0007 pct; zinc, 0.0002 pct; arsenic, 0.0003 pct; antimony, 0.0002 pct; bismuth, 0.0005 pct; tin, 0.0001 pct; iron, 0.0020 pct; lead (by difference), 99.995 pct. Tin: antimony, 0.037 pct; arsenic, 0.020 pct; bismuth, 0.004 pct; cadmium, trace; copper, 0.025 pct; iron, 0.004 pct; lead, 0.020 pct; nickel and cobalt, 0.005 pct; silver, 0.0005 pct; sulphur, 0.005 pct; tin (by .-difference). 99.88 pct. One hundred grams of metal with the desired proportions of lead and tin was weighed out to the nearest one-tenth of a milligram. The mixture was placed in a silica crucible, covered with charcoal, and melted in a reducing atmosphere in a gas-fired furnace. The alloy was well stirred. Chemical analysis of two of the alloys checked closely with the weighed portions. The compositions of the remainder of the alloys were taken directly from the weighings, without chemical analysis.

Jan 1, 1950

By H. F. Ameen, F. M. Hamilton

Results of a laboratory investigation of some sintering variables are presented. The effect on physical properties of mix component variation and rate of cooling of the sinter is illustrated by crush and tumbler test results and data of reducibility tests and microscopic examination of sinters are shown. The results of using solid additions in the mix to improve bed permeability are given.

Jan 12, 1950

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Jan 2, 1968

By Bernard E. Weichman

The oil shales of the Green River formation were deposited in an inland lake which contained abundant plant and animal life. A high percentage of sodium bicarbonate existed in the lower water layers. Digestion of the kerogen-rich mud accumulating on the lake floor lowered the pH of the interstitial waters and precipitated the sodium minerals dawsonite and nahcolite in the kerogen-rich mud. After about five million years of existence, uplift of land areas around the lake caused an influx of clastic sediments which filled up the lake. Continued tectionics gently folded the basin and caused fracturing of the kerogen-lean oil shale. Nahcolite existing in the fractured lean oil shale was dissolved by subsurface waters leaving a tremendous aquifer in a portion of the oil shale. The extent and porosity of the "Leached zone" aquifer is dependent upon the percent of kerogen and nahcolite originally deposited in the oil shale.

Jan 1, 1975

By A. Sauveur

In an important paper on The Critical Ranges of Pure Iron presented at May, 1913, meeting of the Iron and Steel Institute…

Jan 1, 1915

By Charteris A. Stewart

The following scanty notes on the Roumanian oil-region may serve as an introduction to more detailed future study and description. The Roumanian oil-belt follows the outer edge of the sweep of the Carpathian mountains, and may, in a broad sense, be regarded as a prolongation of the Galician belt. It is distributed over a tract of country from 300 to 400 miles in length, with a width of from 15 to 20 miles, and is believed to cover an area of at least 20,000 hectares (49,420 acres). The governmerit claims that 16,000 to 17,000 hectares of its land is petroliferous. The primary deposits of petroleum arc considered to be in the Paleogene (Oligocene) and the Neogene (the salines of the Miocene) formations. Most of the other repositories, especially those of Muntenie, are only secondary, the petroleum there having been introduced by the orogenic movements which raised the Carpathian mountains. The oil-field has been divided by the Roumanian Survey into two regions, the Flysch and the Sub-carpathian, as is shown in the accompanying sketch-map, Fig. 1. So far as is yet known, practically all the seepages and productive pits and wells are situated on anticlinals. Those which outcrop in the Flysch region (called Paleogene anticlinals), as indicated in the sketch-map, Fig. 1,are : Solontz,

Jan 1, 1907

By R. P. Carreker, R. L. Fullman, J. C. Fisher

THE existence of the phase TiAg has not been reported previously. Other investigators have denied the existence of compounds in the Ti-Ag system.13' However, phases of equi-atomic proportion have been reported by Raub, et al.' in the (similar) systems of titanium with gold and copper and zir- conium with silver. Raub's work indicated that titanium and silver are immiscible in the liquid state. No evidence of this was found although a very wide melting range exists which makes the preparation of homogeneous alloys difficult. TiAg is apparently formed by a peritectic reaction between /3

Jan 1, 1954

By W. E. Horst

During the past few years of operation at Kings Mountain, N. C., full-scale flotation has generally yielded poorer metallurgical results than those obtained in the laboratory or pilot plant. After 2 min in each size of Denver flotation machine in the spodumene rougher circuit, pilot recovery (41.7 pct) was almost three times that of the plant (13.6 pet) and about twice that of the laboratory (21.0 pet). Pilot and commercial plant data are based on continuous operation, and laboratory results on batch testing of rougher performance. The ore is a pegmatite containing spodumene, feldspar, quartz, mica, and amphibolite. Data were accumulated to evaluate the scale-up relationships between laboratory, pilot plant, and plant flotation cells. Flotation rate constants and dimensional analysis were used to define the relationship existing between flotation behavior and scale of operation.

Jan 11, 1958

By C. D. Broadbent

Open pit blasting can be a low cost routine or a high cost bottleneck depending on geology, environment and the operator's ability to master site conditions. Because blasting is a repetitive operation, there should be ample opportunity to optimize the process; but ordinarily this optimization is rarely achieved and then only if conditions remain consistent and predictable. Often, however, and particularly with porphyry coppers, hidden differences in rock characteristics nullify the operator's best efforts. At a porphyry copper deposit being mined by Kennecott Copper Corporation, all of the following rock types occur; oxidized and fresh porphyry, altered and silicified limestone, explosion breccia, rhyolite, sandstone, shale and several others. The units can cover large areas or be limited to a few tens of feet in maximum dimension. They are rarely visible on the bench surface and often do not show up in the bench slope. Even though the blastability of these rocks varies substantially, a generally-uniform blasting pattern was formerly used with disappointing results. Secondary blasting was often required and high bottoms occurred frequently, overblasting wasted drilling time, and explosives caused excessive throw.

Jan 4, 1974

By A. B. Fly

Borehole mining combines the principles of hydraulic mining, slurry mucking and rotary drilling. The borehole is drilled with conventional equipment and is cased down to the top of the mining zone. The borehole mining tool is comprised of the kelly-swivel assembly, multiple drill-pipe sections, and the jet-pump barrel assembly as shown in Fig. 1. The kelly swivel is fitted with a bail to support the mining tool. The kelly drive bushing engages the rotary table to allow the rotation of the mining tool while it is being operated. The jet-pump barrel assembly is comprised of the sidewall jet nozzles, the jet-pump assembly, the suction screen, and the tricone rock bit. Clean fluid is pumped at high pressure through the kelly hose to the high-pressure swivel on the mining tool. The high-pressure pipe conducts the fluid down to the sidewall jet nozzles, the pump jet nozzle, and the tricone rock bit. The sidewall jet streams cut the formation and wash the cuttings down to the rock bit. High-pressure fluid issues from the water courses to clean the bit and to agitate the cuttings. Rotation of the mining tool causes the rock bit to grind any oversize material enough to permit its passage through the suction screen. High- pressure fluid issues from the pump jet nozzle to provide the lift needed to pump the slurry to the surface. The slurry is discharged into the settling pits where the cuttings are deposited and the clean fluid is returned to the suction of the high-pressure pump.

Jan 3, 1969

By G. R. St. Pierre, L. M. Adelsberg, R. Speiser

OXIDE platelets have been observed'-3 in oxidized tantalum adjacent to the metal-oxide interface, Fig. 1. The origin and identity of the platelets are important with respect to the proposal of an acceptable mechanism of tantalum oxidation. At reaction temperatures below 750°C, it has been established that the platelets

Jan 1, 1967

By Milton H. Fies

THE Alabama Power Co. operates its Gorgas mine in Walker County, Ala., immediately adjacent to its steam plant. The coal mine property consists of some 19,000 acres of fee and mineral ownership lands, and all of the production from the mine-approximately 2500 tons per day-is utilized at the company's adjoining steam plant. The company is presently considering the purchase of additional acreage adjoining its present holdings which acquisition will almost double its reserves. The coal is transported from the mine over a short railroad spur in the company's own equipment, either directly to one of the large plants at Gorgas or to a storage pile. The longest haul is about 1 1/4 miles.

Jan 12, 1950

By C. Edward Capes

Fine particles in liquid suspension can be agglomerated by a number of mechanisms. Well-known methods include the addition of electrolyte to reduce the zeta potential and allow mutual adhesion arid the use of polymeric flocculants to bridge between the particles. A more recent technique, "spherical Agglomeration", is the subject of this paper. The process involves the addition of a second liquid which is immiscible with the suspending liquid and preferentially wets the particles to cause particle adhesion by capillary liquid bridges. Progress in the application of spherical agglomeration to a number of distinct technological fields is reviewed in this paper. The areas of interest include the formation of dense, highly spherical agglomerates, the separation of solids from suspension and the fractionation of complex, multi-component solids mixtures, such as ores. Some of the more interesting recent applications in the energy and environmental fields, such as the beneficiation of' coal and tar sands, are highlighted.

Jan 1, 1977