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By S. R. Zimmerley, John Gross

The method of measurement of surface on quartz particles was given in a previous paper.' With such a method the relation of surface produced in crushing quartz can be compared to the work in crushing without recourse to sieve sizing or microscopic measurement. In crushing, the work input must be known with a fair degree of accuracy. With crushers, rolls, ball mills, and similar apparatus the measurement of the work in crushing is subject to possible errors, due to friction in the transmission as well as in the machine itself. Moreover, relatively large quantities of material must be crushed to get an average figure. In the selection of a method of crushing, simplicity in design and operation was desired and this was most readily obtained by the use of a free-falling body. A description of the apparatus embodying this principle is given herewith. The Crushing Device The apparatus used is shown in Fig. 1 and in cross-section in Fig. 2. The material to be crushed is placed in the crushing chamber C in the steel mortar M. The mortar is 3 in. dia. by 3 in. high. Two mortars are used, one having a crushing chamber 1 in. dia. by 36 in. deep, with a capacity of 4 g. of quartz, the other having a crushing chamber 1 1/2-in. dia. by % in. deep, with a capacity of 12 g. of quartz. The position of the mortar is adjusted by means of three centering screws A. The steel plunger P, which fits neatly into the chamber, is placed on top of the material to be crushed. Plungers of different lengths were tried and as they were found to give practically identical results the length adopted was equal to the depth of -the chamber. The mortar rests on a solid steel base B but is separated therefrom

Jan 1, 1930

By Philip Henry

THERE is a difference of opinion among engineers on the subject of depreciation in general, and still more on its application to any given case. The committee which was appointed by the American Society of Civil Engineers to make a report on Valuation of Public Utilities, states "There is no subject connected with valuation about which there are more diverse views than those relating to depreciation;" and in the discussion which took place upon the presentation of the preliminary report of this committee in January, 1914, that part of the report dealing with depreciation called forth more discussion than any other. From this discussion it was evident that the word " depreciation" was not always used in the same sense, so it is quite important that some definition be adopted. As this paper relates to the proper method of treating depreciation by corporations or individuals operating oil properties, both of which must make a return of annual net income to the government in connection with the income tax, it will be in order to adopt the definition of the Internal Revenue Bureau. Under date of Mar. 29, 1910, the Commissioner of Internal Revenue of the Treasury Department stated "Deduction on account of depreciation of property must be based on lifetime of property, its cost, value and use." Again, on Form 1035, "Return of Annual Net Income" for miscellaneous corporations (Section 2, Act of Congress approved Oct. 3, 1913), a deduction from gross income is allowed for "Total amount of depreciation for the year." This item is defined more particularly as follows: "The amount claimed under Item No. 5 (b) for depreciation should be such an amount as measures the loss which the corporation actually sustains during the year in the value of buildings, machinery, and such other property as is subject to depreciation on account of wear and tear, exhaustion, or obsolescence. The amount taken credit for on this account in order to be allowable should be so entered on the books as to constitute a liability against the assets of the corporation. The amount claimed under this item should not cover losses in the value of stocks and bonds. Decrease in the book value of securities owned, so far as such decrease represents a decline in the actual value of such securities, should be deducted under item 5 (a) of the return.

Jan 1, 1915

By J. Tarwater

The torsional testing of cylindrical medium-carbon steel specimens, heat treated to a high strength level, revealed a stress-strain relationship that was dependent on the direction of torsional plastic pre-strain. This Bauschinger effect was observed in prestrained specimens both with and without subsequent elevated-temperature strain aging. Yield stresses in strain-aged specimens exceeded those of simply prestrained specimens and the difference in stress was greater when the prestrain direction opposed the test direction. This behavior is discussed in terms of the classical dislocation pile-up using Cottrell's equation, A plastically prestrained strain-hardenable member, loaded in a direction opposite to the direction of prestrain, produces a stress-strain relationship differing appreciably from the curve representing reloading in the prestrain direction. This phenomenon, referred to as the Bauschinger effect, will be discussed in terms of the stress differences ob- served at a specified strain. The effect, dating back to the 1880's, was first attributed to grain boundary stresses. When later work revealed that the effect was also present in single crystals, revised theories attributed the diminished applied reverse stress to assistance from internal long-range stresses. These stresses have been associated with dislocation pile-ups or with dislocation arrays having analogous stress patterns. The stress patterns are subject to alteration by interaction with interstitial solute atoms and acceleration of the interaction may be accomplished with elevated-temperature strain aging. As discussed herein, the interaction showed a directional effect with regard to the applied stresses necessary for small plastic strains. Aside from the rigorous Bauschinger stress-strai relationship, which compares prestrained members, it is interesting to compare the stress-strain curve of a member being prestrained with that of a prestrained member being reverse loaded. For small strains which are a fraction of the prestrain deformation, the applied stresses of the reverse reloaded member are smaller. However, as the reverse strain approaches the prestrain value, the stresses approach equivalence. It has been reported1 that the stress required to return a prestrained specimen to its initial "zero" position generally exceeds the prestrain stress because of the work hardening occurring on potential slip systems during prestrain.

Jan 1, 1963

By Wayne E. Glenn

A centennial meeting should be a time to take stock, to evaluate performance, to plan ahead. It is like a line in a televised commercial that goes, "You've come a long way to get where you've got to today." And no less should be said of the mining and energy industries. We have come a long way. A hundred years ago when AIME was founded, this country produced 23 million tons of bituminous coal and 5.2 million bbl of oil. The figures in 1970 were about 580 million tons of coal and 4.1 billion bbl of oil. In spite of such accomplishments, serious and compelling voices are heard in the land - doubting sincerity, questioning corporate structures, and challenging ethics. Those doubts are raised in one part of Washington at the same time that other sections of the Capitol are asking us to produce more energy in order to keep up with population growth, emerging nations, and new technologies. Those of us in the fuel or energy business frequently talk about the race for energy. The question is, can we develop enough energy fast enough to outdistance our present and increasing demands? Recently I heard of an incident that - in an odd way - caused me to think of the energy race. The incident involved a sky-diver who jumped from an airplane without a parachute. He was handed a chute in mid-air by a sky-diving companion. He put it on, opened it, and landed safely. In a way, it seems to me that our society is hurtling through space and that it needs some help from the energy industries to land safely. We're doing our best, but under some rather difficult conditions. Because of illegal strikes and work stoppages the coal parachute is snarled a bit. The cut in percentage depletion and other tax changes have put some holes in the oil parachute. And the gas ´'chute has been in trouble for some time because of unrealistic controls on producer prices. The irony of the situation is that some of the very people who have been taking potshots at the energy parachutes for a long time are the ones who are complaining loudest now because the 'chutes are not functioning the way they could. The safety of the entire nation can depend on the energy industries.

Jan 1, 1971

By McDowell Graves, Joseph Jensen, W. D. Goold, M. L. Gwin

During the present year the Santa Fe Springs field has proved to be the most important oil field under development in the United States. Its production will exceed that of any other field. Without it, production within the United States would have been almost in even balance with consumption. The field has forced to the fore and compelled, more than any other single factor, serious consideration of the need of conserving the gas resources of the State of California. It has also contributed much to the development of new drilling equipment and important features in petroleum engineering, and has required the development of a new cement for use in deep wells because of high temperatures. It is the only oil field in the country where wells 8000 ft. deep have become so common that they are no longer given special attention. The field covers a little less than 1400 acres of land. In it 196 producing deep-zone wells have already been drilled since August, 1928, and 224 wells are still drilling. More wells may be drilled. This indicates that probably more than 450 wells will be drilled in the present campaign. In hardly a year's time it has caused the outlay of nearly $50,000,000 for drilling, and within the year 1929 it will have returned practically an equal amount of revenue. In contrast to conditions during 1923, when this field was once before an important and disturbing factor, the California oil industry has not been forced to refinance to meet the situation presented by such a large production of oil. There has been practically no unit selling and no stock selling, nor any unnecessary development far beyond the limits of the field. Production is now about 275,000 bbl. per day and gives every promisc of remaining at this figure or increasing to nearly 300,000 bbl. Six months from now the field should still be capable of producing more than 200,000 bbl. per day. Obviously, the need for conserving gas that would be blown to the air, incident to the production of so large a volume of oil, represents a problem in conservation deserving of the most serious attention of the oil industry and of the State of California.

Jan 1, 1930

By John Shelton

ONE of the heaviest burdens uselessly cast by our mineral land laws upon the holder of the title conveyed by a patent from the United States is due to the provision excepting known veins from land patented as placer. In many instances the expense of defending such titles from the assaults of the owners of lode locations made upon the theory that the veins so located were known to exist at the date of the placer application for patent has exceeded many times the value of the land in question. Neither the lapse of time, however long after the issuance of the patent nor repeated adjudications by the courts serve to quiet such titles or to prevent them from being questioned. In the passage of laws providing for the acquisition of title to the mineral lands of the United States, Congress provided that the title to known veins should not pass from the United States by a patent based upon a placer location. As construed by the courts, the law (Sec. 2333 R.S.U.S.) provides that the applicant for a patent upon a placer claim may, if any vein of sufficient value to justify the expenditure of money in its development is known by him to exist within the boundaries thereof, include in his patent application an application for patent upon the vein as a lode claim; and failure to do so is to be deemed a conclusive declaration that the applicant makes no claim to the vein nor to an area of surface ground extending for 25 ft. (7.6 m.) on each side of its middle or center. As to such vein and, such area of enclosing surface ground under the circumstances stated, the title remains in, the United States notwithstanding the issuance of a patent that purports to convey the entire surface of a described area and everything beneath it, excepting only the segments of veins the apices of which lie outside of such area. Such known veins with such area of enclosing surface ground are, of course, at any time, so long as they remain unlocated, subject to location and appropriation in the same manner as other veins upon the public domain. The history of the operation of this law in one district will serve to illustrate its effect generally throughout the mining regions of the United States. In the Butte district, the mineral that first attracted the atten-

Jan 8, 1919

By Peter N. Calder, Alan Bauer

INTRODUCTION One of the most important decisions involved in the design of an open pit mine is the selection of a slope angle. Despite this fact, engineering procedures have developed slowly in this field. Only recently have the instruments and know-how become available to undertake a design based on sound engineering principles. The effect of blasting on open pit slope stability is one aspect in which the state of the art has not developed fully. These effects include: a) the effects of the ground motion associated with blast waves on slope stability, and b) the fracturing of rock in the vicinity of slopes caused by blast waves. Natural rock jointing plays an important role in both of these. SUMMARY OF BLASTING EFFECTS In recent years there has been a trend to larger sizes of blast holes in open pits to the extent that today 9% in. and 12% in. diam. holes are the most common. The reasons for this have been economic. Larger machines are more efficient and produce at a lower overall cost per ton. As the size of blast holes have increased, so have the other factors associated with blasting. Bench heights have increased, the tons/ft. of hole yield has risen significantly and the explosive load per hole has increased. Quite naturally the rupture radius for a single blast hole has increased along with the vibration level produced per blast hole. Open pit blasting operations can result in two types of unwanted damage: 1. Damage to structures, such as buildings, dams and slopes by ground vibrations initiated by the blast. 2. Fracturing of ground beyond the planned excavation limits. Let us first consider item one. Vibration effects are determined by the type of blast which is fired and the type of medium through which the blast wave is being transmitted. They are strongly influenced by the weight of charge per hole, the number of holes per delay, the distance from the shot point, the mode of initiation, the point of interest relative to the blast, etc.

Jan 1, 1971

INTRODUCTION It has been impossible for the student, the practicing engineer, and the geologist to find all of the essential elements of mineral appraisal and mineral economic analysis in a single text. Indeed, the most recent texts on mine evaluation are over 20 years old. Many of the basic principles of mine sampling and evaluation have not changed over the ensuing years, but with the advent of the digital computer the entire scope of mineral evaluation has been expanded to encompass superior techniques that heretofore were not possible when using manual methods. The old manual methods for ore reserve computations and the techniques for assignment of area of influence to drill-hole samples are now as antiquated as the Model-T Ford. With the computer making possible solutions that had not been practicable in terms of time and effort, it is important for the practicing explorationist and mining engineer to understand many of the new concepts and principles that can be applied with the resolving power of the computer. Many practicing mineral industry professionals have been disappointed by certain computer programs and thus have some reservations about computers being able to solve their very real problems. Often the gap between the practicing engineer and the ivory tower theoretician applying modern computer techniques is too broad to be bridged with scattered, fragmented publications. PURPOSE AND SCOPE OF TEXT It is the intent of this book to update and to unify a great many scattered reference works used in the mineral industry today. The ensuing pages are addressed both to the professional already working in the mineral industry who needs information on computerized methods as well as to the serious student seeking to grasp the fundamentals and modern techniques of mineral appraisal and feasibility. These techniques are based on sound mathematical principles and theory, with the computer as a tool-but a very essential tool-for the solution of the problems involved. The computer can be of value only if it is programmed by those having sufficient expertise to use its inherent problem-solving capability, and the output is interpreted by those who are sufficiently acquainted with its operation to understand the data it produces. In the pages that follow the author intends to outline in considerable detail all the essen-

Jan 1, 1980

By Henry Hibbard

THE process of making washed metal now followed is in principle that described by Holley before this Institute in 1879, as the Krupp washing process. Sir Lowthian Bell also experimented extensively in England during 1877 and 1878 on refining iron and joined his interest with Krupp, the process being often referred to as the Bell-Krupp process. The only plant in this country now operating this process is that of the Brier Hill Steel Co., Youngstown, Ohio. This process may be considered as the sole survivor of the numerous methods conceived for refining crude iron, when the removal of phosphorus from steel-making material was the great desideratum affecting large districts. The east coast of England and all northern Germany, the homes of Bell and Krupp, respectively, could at that time make steel only from imported ores. These processes were in use or in various stages of development 40 years ago and all except the Bell-Krupp received their quietus from the development of the basic steel processes, both pneumatic and open hearth. The aim of the early refining processes was, first, the removal of the silicon; which could be clone on a sand bottom, and later, the removal of the phosphorus, requiring a bottom which would give or permit a basic slag. The incidental advantages of increased yield and small fuel consumption were not generally recognized or considered; the aim of the later. operations was the saving of the difference in value between low and high phosphorus irons, as well as hastening the removal of the metalloids. The chemistry of the washing process follows in part that of the puddling process, and indeed washing might, be considered as the first half of puddling, since all the non-ferrous elements of the crude iron, except the carbon, are eliminated and the iron is maintained molten until cast. In puddling, the iron loses its carbon as well, and because of that, its fusion point rises above the hearth temperature; it freezes into a pasty malleable form, and is worked at once by squeezer, hammer, or rolls.

Jan 12, 1915

By David Moskowitz, Ira Binder, Robert Steinitz

THE hard refractory borides of the transition elements of the 4th, 5th, and 6th groups of the Periodic System have been the subject of a number of recent investigations.'-' It is well known now that most of these elements form several different borides, and Kiessling8 has summarized the rules which govern to some extent the arrangements of the boron atoms in the various structures. Melting points of a few borides have been published." The systems Fe-B, Ni-B, and Co-B have been reported," but, as these borides are rather low melting, they are outside of the groups of boron compounds considered here. Brewer' has tested the stability of various borides and estimated a number of eutectic temperatures between different borides, but in no case was the complete system of a transition metal and boron investigated. The phase diagram becomes of special importance if the preparation of the borides from the elements in powdered form is considered; the lowest eutectic temperature will determine the first appearance of a liquid phase. Also, the knowledge of high temperature phases, if they exist, is important for the preparation of bodies from these borides by hot pressing or sintering. During the investigation of various metal borides,7 it was found that there were more boride phases existing in the Mo-B system than reported by Kiessling." They occur, however, only at temperatures above 1500°C and were, therefore, not found by him. This led to a study of the equilibrium diagram of the Mo-B system. ranging from 0 to 25 pct B and from room temperature to the liquidus. Part of this investigation was reported during the "Research in Progress" session at the 1952 Annual Meeting of the AIME.11 Raw Materials and Preparation of the Borides The raw materials used were commercial molybdenum and boron powder, both supplied by the Molybdenum Corp. of America. The molybdenum powder was 99+ pct pure? while the boron powder contained about 83 to 85 pct B. A large percentage of the impurities in this powder was oxygen, with the rest formed by iron, calcium, and unknown substances. The low purity of the boron used was, however, not considered detrimental to the final product, as most of the impurities evaporated at the high temperatures at which the borides were formed. The final product always had a minimum purity of 96 to 98 pct (figured as molybdenum and boron), with carbon, iron, and probably oxygen being the remaining products. Carbon is usually present as graphite. The chemical analyses always confirmed the compositions which corresponded to the crystallographic structures as determined by X-ray diffraction, and the boron content of the finished product agreed closely with that of the starting mixture; no boron was lost during the boride preparation. The chemical analysis methods employed for molybdenum and boron were previously described by Blumenthal.12,13 The powders were mixed by hand in the desired proportions, compressed at room temperature under low pressure, and then heated under hydrogen to about 1500" to 1700°C in a graphite crucible to form the borides. Usually, the three well-known borides Mo,B, MOB, and Mo,B,, which are stable at room temperatures, were prepared in this way, and all other compositions were made by mixing these borides in various ratios or by the addition of molybdenum or boron powders for the very low or very high boron contents. Preparation of two-phase compositions directly from the elemental powders was tried only occasionally to check whether equilibrium could be reached in this way. Experimental Procedures The stable borides were mixed in the desired ratios and heated under hydrogen in graphite crucibles to various temperatures. The well insulated crucibles were heated in a high frequency induction furnace. Special care was taken to obtain exact temperature measurement, which proved much more difficult than originally anticipated. It is believed that individual temperature measurements have an error of less than ±25ºC, while melting or transformation temperatures are accurate within ±50°C. The temperatures were measured with an optical pyrometer which was aimed at the closed end of a graphite tube extending down into the crucible. close to the samples. Attempts to measure directly through the hydrogen exit stack failed. The crucible arrangement is shown in Fig. 1. Heating was done at a slow rate to be sure that the temperature inside the crucible was uniform. The specimens were kept at the final temperature for about 30 min. For the investigation of high temperature phases, some samples were quenched. They were heated, without atmosphere protection, in a very small graphite crucible which could be rapidly removed from the high frequency coil, and dropped into water. These quenched samples were afterwards annealed to establish the equilibrium at lower temperatures. The melting points or the positions of the solidus and liquidus lines were determined by heating the specimens to various temperatures and examining them at room temperature for evidence of a liquid phase. These results were checked later on by thermal arrest curves, especially to determine the exact position of the eutectic temperature line. For this purpose about 200 g of the boride were melted in a graphite crucible, in an arrangement similar to Fig. 1. Slow cooling was assured by very good

Jan 1, 1953

By Ralph H. Sweetser

To control the slag in an iron blast furnace is to control the quality of the pig iron produced (and to a certain extent the tonnage), and to control the whole operation of the furnace itself, including a large part of the cost of production. The character of the slag is the determining factor in the character of the pig iron as to the controllable limits of sulfur, silicon, and, to a certain extent, the manganese; it has an influence on the proportions of combined and graphitic carbons.

Jan 1, 1935

By E. T. Clymer

It has been the custom, from the earliest time, to grade pig-iron by the appearance of the fracture; and although, since the pneumatic and open-hearth methods of steel-making have come into existence, chemistry has been called to the assistance of the steelmaker in selecting material for his use, the consumers of forge- and more especially of foundry-iron, still rely almost entirely, as they did a hundred years ago, on the appearance of the fracture of the pig to guide them in the choice of iron. To this rule, however, each year sees more exceptions; and there are now many foundry-men

Jan 1, 1893

By Salim Akhtar

The operation of a mineral processing plant with a complex flowsheet is represented by a mathematical operator. Such a representation permits a quantitative evaluation and monitoring of the separation processes in different sections of a processing plant, and gives an overall separation efficiency of the plant.

Jan 1, 1975

COMMITTEES Committee on Arrangements DAVID H. BROWNE, Chairman BRADLEY STOUGHTON, Vice-Chairman LAWRENCE ADDICKS BURR A. ROBINSON PERCY E. BARBOUR E. MALTBY SHIPP GEORGE D. BARRON JOSEPH STRUTHERS J. V. N.. DORR E. B. STURGIS J. R.. FINLAY T. T. READ Louis D. HUNTOON R. H. VAIL

Jan 4, 1916

By Jasper Whiting

It is well known that there is no better indication of the working of a blast-furnace than is ,given by analyses of its gases; yet although many indiviclual analyses have been made, there is, I think, no

Jan 1, 1892

By H. R. Hoffman

SINCE slag is a necessary product of the reactive oxygen additions necessary to the present-clay quality steelmaking, the study of the control of its volume is being attempted. With other varying factors that may affect the volume of slag kept as nearly constant as possible, the object of this investigation is to determine what effect the one factor of varying the amounts of iron-ore additions and the time of the additions may have upon the volume of slag in producing an acid electric steel heat.

Jan 1, 1947

All manuscripts intended for presentation at the February meeting of the Institute must be in the hands of the Secretary of the Institute not later than Monday, Nov. 23, 1914. This is the date at which the manuscript must be in the hands of the Secretary, and is not the mailing date upon which it leaves the author's hands. In case manuscripts are sent to members of Technical Committees, they must be in the hands of the Technical Committee a sufficient time in advance of Nov. 23 so that they may be in the hands of the Secretary on the date indicated.

Jan 10, 1914

By Charles O. Thomson

When a wire rod of iron or of steel is immersed in a hot solution of common salt, allowed to remain long enough to bring the metal to the temperature of the brine, and withdrawn, the surface of the rod is irregularly covered with a deposit of crystals of salt. These crystals adhere to the cod with great firmnes, in consequence, doubtless, of a thin film of ferric hydrate, which is formed between them and the rod as the water dries off. The rod can now be reduced, by successive passes through a dic or draw-plate, without any

Jan 1, 1881

By O. Vartiainen, R. T. Hukki

A preliminary investigation of the collecting effects of various fatty acids in tall oil has led to a conclusion that the collecting power of fatty acids used in flotation increases with increasing unsaturation of the hydrocarbon chain, Linoleic acid was found to be an excellent collector for oxide minerals.

Jan 8, 1953

Jan 1, 1939