Search Documents

"No true conception of the Park City mining district can be obtained without first giving consideration to the part it has played as a consistent producer of mineral wealth. Its position in this regard is almost unique in the annals of a lead silver camp. For over fifty years it has been a continuous producer of lead and silver and for twenty years it has added to the world's supply of zinc. Few camps with its productive history are so little known to the mining fraternity for the reason that its life has never been punctuated by periods of ""boom"" which serve to attract general attention, neither has it been the field of operation for promoters who temporarily focus attention upon their scene of action. Its history is one of legitimate mining operations. These were at first carried on by a number of smaller companies. A period of consolidation followed and at the present time the entire production of the camp is in the hands of two major companies and one smaller company. These are flanked by a number of prospecting properties, which are at this time actively engaged in the search for ores and later events will doubtless put some of them in the producing class.A technical discussion of the ore occurrence and mining operations in the camp will be the subject of a paper to be read before this meeting of the Institute. The mission of this article is to supply a ""Baedeker"" where Baedeker is lacking.The town of Park City is a typical, up-to-date, western mining camp which owes its existence as a town of 4,500 inhabitants solely to the mining industry. The camp is located 7,000 feet above sea level, thirty-two miles east of Salt Lake City. It is situated on the Victory Highway seven miles from its junction with the Lincoln Highway and has the benefit of excellent automobile communication with the metropolis of the state. Both the Denver and Rio Grande and the Union Pacific Railroads give daily train service to the camp and effectively solve the transportation problems of the mining companies."

Jan 1, 1925

By Frank Foote, E. R. Jette

Precision lattice-constant measurements have been widely used in the study of cubic solid solutions but as yet have been rarely applied to noncubic solid solutions. (See, however, references I and 2.) With the high precision at present attainable in the measurement of lattice constants, the X-ray method should be readily applicable to noncubic solid solutions. In the work reported here, hexagonal close-packed magnesium was used as the solvent and either lead, bismuth or gold as the solute. In the magnesium-lead and magnesium-bismuth systems the a and c lattice constants were determined as a function of composition, densities were calculated from these lattice-constant data, these theoretical densities were compared with those directly measured and the solid solubility limit was determined on quenched specimens over a considerable range of temperature. In the magnesium-gold system, the solid solubility is very small but we have obtained an indirect check on the solubility limit previously reported. Materials and Preparation oF the Alloys The magnesium used was obtained from the Aluminum Company of America and was 99.987 per cent pure. Impurities as reported On the label were: Fe, Al, 0'004 per cent; Si, 0.009 per cent; Zn, trace; Cu, Pb, nil. The bismuth was Merck's analytical grade, minimum purity 99.95 per cent. Maximum impurities as listed on the label were: Fe, 0.008 per cent; Pb, 0.010 per cent; Ag, 0.010 per cent; Cu, 0.005 per cent; Sn, 0.003 per cent; Sb, 0.00; As, 0.000; S, 0.01 per cent. The gold was purified by double precipitation with sulphur dioxide. The lattice constants of these three metals have been previously reported.3 The lead used was test lead, silver free and with a maximum of 0.10 per cent heavy metal impurities. The lattice constant 01 this lead has been measured and found to be 4.94057 ± 0.00016 at 25°C. The alloys were prepared by melting together weighed amounts of the constituent metals in magnesia-lined alundum crucibles under an atmosphere of hydrogen purified by passing over magnesium heated to 500°C. The magnesia lining prevented contamination 01 the alloys with aluminum. Vacuum melting could not be used because of the volatility of magnesium. A high-frequency induction furnace was used for the melting operation and the stirring action of the current resulted in thorough mixing of the constituents. The melts were allowed to freeze in the crucible, the ingots obtained weighed about 10 grams. An extremely thin white film formed on the surface of the melts, sometimes covering only a part of the exposed surface. The ingots were filed clean, placed in small iror crucibles with close-fitting lids and indi. vidually sealed into Pyrex glass tubes Before sealing off, the tubes were alter

Jan 1, 1941

By Frank Foote, E. R. Jette

Precision lattice-constant measurements have been widely used in the study of cubic solid solutions but as yet have been rarely applied to noncubic solid solutions. (See, however, references I and 2.) With the high precision at present attainable in the measurement of lattice constants, the X-ray method should be readily applicable to noncubic solid solutions. In the work reported here, hexagonal close-packed magnesium was used as the solvent and either lead, bismuth or gold as the solute. In the magnesium-lead and magnesium-bismuth systems the a and c lattice constants were determined as a function of composition, densities were calculated from these lattice-constant data, these theoretical densities were compared with those directly measured and the solid solubility limit was determined on quenched specimens over a considerable range of temperature. In the magnesium-gold system, the solid solubility is very small but we have obtained an indirect check on the solubility limit previously reported. Materials and Preparation oF the Alloys The magnesium used was obtained from the Aluminum Company of America and was 99.987 per cent pure. Impurities as reported On the label were: Fe, Al, 0'004 per cent; Si, 0.009 per cent; Zn, trace; Cu, Pb, nil. The bismuth was Merck's analytical grade, minimum purity 99.95 per cent. Maximum impurities as listed on the label were: Fe, 0.008 per cent; Pb, 0.010 per cent; Ag, 0.010 per cent; Cu, 0.005 per cent; Sn, 0.003 per cent; Sb, 0.00; As, 0.000; S, 0.01 per cent. The gold was purified by double precipitation with sulphur dioxide. The lattice constants of these three metals have been previously reported.3 The lead used was test lead, silver free and with a maximum of 0.10 per cent heavy metal impurities. The lattice constant 01 this lead has been measured and found to be 4.94057 ± 0.00016 at 25°C. The alloys were prepared by melting together weighed amounts of the constituent metals in magnesia-lined alundum crucibles under an atmosphere of hydrogen purified by passing over magnesium heated to 500°C. The magnesia lining prevented contamination 01 the alloys with aluminum. Vacuum melting could not be used because of the volatility of magnesium. A high-frequency induction furnace was used for the melting operation and the stirring action of the current resulted in thorough mixing of the constituents. The melts were allowed to freeze in the crucible, the ingots obtained weighed about 10 grams. An extremely thin white film formed on the surface of the melts, sometimes covering only a part of the exposed surface. The ingots were filed clean, placed in small iror crucibles with close-fitting lids and indi. vidually sealed into Pyrex glass tubes Before sealing off, the tubes were alter

Jan 1, 1941

POSITIONS VACANT (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) A copper company in Arizona desires a young engineer to assist the superintendent and take charge of the surveying, sampling and assaying. A graduate mining engineer with a few years' experience in mine surveying and sampling preferred. Salary, $125 to start. No. 10. A company in Quebec desires a metallurgist familiar with copper smelting to remodel an old plant and carry on experimental work to determine whether its ore can be smelted profitably in the district. No. 11. A foundry making a specialty of medium and light weight. steel castings of high grade waists a competent man as assistant manager capable of taking complete charge of production in the absence of the general manager. No. 12.

Jan 3, 1914

Planning for a surface coal mine includes selecting the best means and equipment for uncovering the coal, loading it, and transporting it to the preparation plant. The machines and methods that will ensure optimum production will depend upon the location and characteristics of the seam to be mined. Stripping Techniques The choice of stripping units is influenced primarily by the system of mining, such as contour or out-crop mining as contrasted to mining in a region of rolling terrain with relatively flat upland surfaces. Factors such as the life of the mining operations production requirements, types of overburden, local and regional dip of coal, and land reclamation are other important considerations.

Jan 10, 1967

IN NOVEMBER 1933 I had the pleasure of receiving an autographed copy of a small brochure entitled "Birth of the Porphyry Coppers." The author, James Colquhoun, a distinguished British mining engineer, had been the dominant figure in the Arizona Copper Company, Limited, which, until its acquisition by the Phelps Dodge Corporation in 1921, had been the principal producer of copper in the Morenci district. In addition to the highly productive Humboldt and Longfellow mines it owned the Clay property, which, of course, has now become Arizona's No. 1 copper mine. Except for Utah Copper it is the premier Porphyry copper enterprise in the United States. Mr. Colquhoun's little volume was inspired by THE PORPHYRY COPPERS which had appeared early that year. In a most courteous and friendly way he adduces data to show that "we (Arizona Copper Company Limited) were successfully treating low-grade porphyry ores in quantity for at least four years (1901 to 19W) before the Utah Copper Company did anything at all." This last remark is based on the figures in THE PORPHYRY COPPERS showing that Utah's first production came from the Copperton pilot plant in 1905. Mr. Colquhoun traces the story of Morenci beginning in 1883 when he first arrived there. He tells how the rich self-fluxing ores (containing lime- stone, silica, and iron in proportion to permit direct smelting to produce black copper) were gradually exhausted. High-grade siliceous ore could be mixed in limited quantity with the self-fluxing ores; and oxidized ores were leached to contribute substantially to the production of the district. But

Jan 1, 1957

By Nelson Severinghaus

Following the end of hostilities of World War 11, a resurgence of industrial and home building has given impetus to the use of many products of the stone industry. Shortage and high prices of some building materials such as lumber have aided wider acceptance of materials such as concrete products which have been relatively plentiful and which have not risen so rapidly in price. Ingredients for many of these substituting materials come from the stone industries, often from by-products of stone operations. Most of the tonnage of the stone industry in the State of Georgia comes from granite and marble. There are extensive dimension stone operations in granite in the Elberton and in the Lithonia areas. Building and monumental marble from the Tate area has been used throughout the country. Cutting operations in both types of stone have their by-products in faulty blocks and in spalls. In the State there are three large crushed-stone plants utilizing granite, One near Camak, One near Lithonia and one at Stockbridge. All have had excess fines Or in in the past but this excess is largely disappearing with development of new uses. At times this "waste" has amounted to as much as 20 pct of the stone quarried. Handling Of this large tonnage from point of screening out to storage piles presented a costly problem and large areas were taken up by the piles. Crushed 'tone is generally sold with a a narrow margin Of price over cost, so any elimination of disposal cost or increase of income by marketing of by-products is highly desirable. By-products of Granite Dimension Stone It sometimes becomes difficult to differentiate between main product and byproduct. In the cutting of granite dimension stone in the Lithonia district of Georgia, a considerable quantity of remnants of Uneven shape and size is produced. The larger of these pieces have long found use as building rubble, particularly for retaining walls and building foundations (Fig I), They are broken down to one man size by plug drilling and wedging and by hammer. In recent times, demand for this former by-product has grown so that quarries have been opened for the production of rubble as a main product. Local masons have attained skill in using these irregular shapes to form economical and attractive walls. Areas such as Elberton, Georgia, which do not have a large building market nearby, tend to accumulate piles of large pieces of reject stone. When a road job or other local construction offers a quantity market for crushed stone, a portable crusher works this material down to crushed aggregate. Spalls and finer chips from granite stone-cutting operations have generally found their way into crushers and thence to the many uses for crushed aggregate. One company near Lithonia started marketing the smaller by-product crushed sizes for chicken grit about ten years ago. This use has grown to nation-wide distribution and the tonnage is now so great that they have opened a large quarry with

Jan 1, 1948

By Nelson Severinghaus

Following the end of hostilities of World War 11, a resurgence of industrial and home building has given impetus to the use of many products of the stone industry. Shortage and high prices of some building materials such as lumber have aided wider acceptance of materials such as concrete products which have been relatively plentiful and which have not risen so rapidly in price. Ingredients for many of these substituting materials come from the stone industries, often from by-products of stone operations. Most of the tonnage of the stone industry in the State of Georgia comes from granite and marble. There are extensive dimension stone operations in granite in the Elberton and in the Lithonia areas. Building and monumental marble from the Tate area has been used throughout the country. Cutting operations in both types of stone have their by-products in faulty blocks and in spalls. In the State there are three large crushed-stone plants utilizing granite, One near Camak, One near Lithonia and one at Stockbridge. All have had excess fines Or in in the past but this excess is largely disappearing with development of new uses. At times this "waste" has amounted to as much as 20 pct of the stone quarried. Handling Of this large tonnage from point of screening out to storage piles presented a costly problem and large areas were taken up by the piles. Crushed 'tone is generally sold with a a narrow margin Of price over cost, so any elimination of disposal cost or increase of income by marketing of by-products is highly desirable. By-products of Granite Dimension Stone It sometimes becomes difficult to differentiate between main product and byproduct. In the cutting of granite dimension stone in the Lithonia district of Georgia, a considerable quantity of remnants of Uneven shape and size is produced. The larger of these pieces have long found use as building rubble, particularly for retaining walls and building foundations (Fig I), They are broken down to one man size by plug drilling and wedging and by hammer. In recent times, demand for this former by-product has grown so that quarries have been opened for the production of rubble as a main product. Local masons have attained skill in using these irregular shapes to form economical and attractive walls. Areas such as Elberton, Georgia, which do not have a large building market nearby, tend to accumulate piles of large pieces of reject stone. When a road job or other local construction offers a quantity market for crushed stone, a portable crusher works this material down to crushed aggregate. Spalls and finer chips from granite stone-cutting operations have generally found their way into crushers and thence to the many uses for crushed aggregate. One company near Lithonia started marketing the smaller by-product crushed sizes for chicken grit about ten years ago. This use has grown to nation-wide distribution and the tonnage is now so great that they have opened a large quarry with

Jan 1, 1948

By Thomas Robins

About six years ago the writer had occasion to visit a large magnetic iron-ore concentrating-plant, and then saw for the first time rubber belts employed for conveying-purposes. These belts were from 20 inches to 30 inches in width, and some of them were as long as 500 feet between centers. When I spoke of the enormous amount of material they handled with a small expenditure of power, the superintendent assented, but at the same time complained that although he bought the best quality of belts, the abrasion of the ore wore them out very rapidly, causing continually very large bills for repairs and renewals. On close examination several interesting points were discovered :

Jan 1, 1897

By John A. Church

When, in 1879,I examined the mines of the Tombstone Mill and Mining Company, at Tombstone, Arizona, I found a bed of tailings containing 12,000 tons, which had a value of 9 to 12 ounces of silver per ton and some gold. The ore had been amalgamated in pans, in which each charge had been ground for four hours, having been pre viously stamped through rough-punched screens, which gave a pro duct varying from 1-100th to 1-20th of an inch, according to the state of wear of the screen. It was certain that a large proportion of the tailings must be in fine slimes, and the question of recovering their value was difficult. Even now the concentration of slimes is . an unwelcome task, and at that day very little was known about it. Nevertheless, after considering the results of a test by repanning the tailings, I advised the company to concentrate and smelt, although they had to face the difficulty of making a smelting-product from slimes containing only 3 per cent. of lead. Limestone was abundant enough, but no iron suitable for flux was to be had for hundreds of miles. One of the company's claims con tained an argeutiferous manganese-ore, which gave but poor results by amalgamation. This was one reason for recommending smelt ing ; for if manganese would play the part of a precipitant, as iron does, the company could smelt by combining two of its silver ores, without other flux than the small amount of lime that might be needed. At that time no smelter had ventured to trust manga nese as a precipitant, though large quantities of this ore containing silver were bought and used by custom-smelters, who looked upon the manganese solely as a basic flux for silica. I believe that no other furnace has been obliged to trust this metal, and that the man ganese practice of Tombstone remains unique among the records of smelting lead-ores in the shaft-furnace. The bright side of the problem was given by the fact that the mines were shallow and that the enterprise would at least begin with oxidized ores. The tailings contained about 85 per cent. of silica,

Jan 1, 1895

By AIME AIME

A COMMITTEE, representing a number of the larger oil companies in California, met in San Francisco on Nov. 12, 1919, for the purpose of discussing the depletion deductions to be allowed in computing the Federal income taxes under the Internal Revenue Act of 1918. It was the general sense of the committee that a system based on sound engineering principles should be formulated for estimating the value of oil properties, so that better and more uniform results might be obtained by the various companies in filing their returns with the' Bureau of Internal Revenue. A subcommittee, consisting of five petroleum engineers, was thereupon appointed to collect information and draft a report. The committee consisted of G. C. Gester, Carl H. Beal, J. H. G. Wolf, E. G. Gaylord, and E. D. Nolan; this report is the work of that subcommittee.

Jan 1, 1920

By James E. Howard

AT the request of the Council of the Institute, I have the honor to submit the following remarks upon the Program of Tests under which the current work of the Watertown Arsenal Testing Laboratory is carried on, which comprises, among other items, the tests of steel ingot metal and derivative shapes. The intended scope of the tests may be illustrated by extracts from the descriptive part of the program as submitted by the Laboratory under date of April 17, 1907, and subsequently approved by the Chief of Ordnance, U. S. A. Under Item 1, Ingot Metal-Open hearth, acid and basic; Bessemer, acid and basic; crucible; fluid compressed and uncompressed-descriptive remarks were made as follows ; " A thorough, fundamental inquiry into the physical properties of steel necessarily begins with the ingot metal. Investigations, having for their object the improvement of steels, should also begin with the ingot. A knowledge of the ingot structure is essential for judging of the subsequent behavior or appearance of the metal. Under ordinary conditions, so little information is obtained from the ingot in individual cases that practically none of importance is acquired. These remarks have particular reference to the state of physical and structural soundness of the steel. Questions of chemical composition, segregation, piping and the grosser cavities have frequently been given attention. Defects of continuity of structure, which manifest themselves in the working; of the metal, and at the final stages cause distrust in the finished forging, have generally been neglected. ? The range in physical properties in a given composition of metal, as shown in Tests of Metals, 1902 and 1903, is very great. Tests are there found which, when the results are

Mar 1, 1908

In accordance with the usual custom, manuscripts to be presented at the next meeting of the Institute must be in the hands of the, Secretary before July 1, 1917. Manuscripts to be properly distributed in advance of the meeting must be in the hands of the Secretary before June 1, 1917. At the last meeting of the Institute 45 papers were presented, and 42 of them were actively discussed. This experience makes us believe that advance distribution is the best possible means of getting a good discussion of papers and of securing for them the interest of the members of the profession. It will be impossible, however, to give the papers proper distribution if they bare not received before June 1, 1917.

Jan 4, 1917

By John D. Ridge

For mining geologists, the most important trends during 1962 have been the increased concentration of the exploratory activities of American mining companies in the United States and Canada and the greater use of the combined techniques of geology, geophysics and geochemistry in searches over larger areas for wider varieties of metals and minerals. The principal reasons for these changes in approach have been the deterioration of the political-economic climate in many areas of the globe of equal or greater geologic promise and the realization that modern exploration is most efficiently and economically conducted through the use of all available means of detecting ores in areas sufficiently large to raise to a maximum the chances of success. The attitude of certain major U.S. metal-producing companies can be shown by the officially ex- pressed positions of their principal officers. Early in 1962, Clyde E. Weed, Chairman of the Board of Anaconda, remarked that "because of unsettled conditions and disruptive influences in many of the copper-producing areas of the world, it is imperative that domestic copper-producing capacity be improved and made as efficient as possible in order to meet consumer demands at reasonably stable prices." In November, Robert G. Page, President of Phelps Dodge, pointed out that his company is not only concentrating most of its exploratory effort on this continent but is also increasing the number of metals for which it is searching. Frank R. Milliken, President of Kennecott, recently said that "most of our exploration money is going into the northern part of the Western Hemisphere."

Jan 2, 1963

By AIME AIME

THE Iron and Steel Division and the Institute of Metals Division are laying plans for a rousing meeting the week beginning Sept. 21 in the land of the bean and the cod-at Boston. The two divisions are collaborating with the American Welding Society, the American Society for Steel Treating, and the Iron and Steel Division of the A. S. M. E., to have technical sessions of widespread interest and social affairs that will compare with the best of previous years. In connection with the meetings an exhibition of production and testing equipment, heat-treating equipment, furnaces, welding equipment, and metal products will be held on Commonwealth Pier all week, where those attending may see the latest developments in the field of their own work.

Jan 1, 1931

INTRODUCTION Trade financing is a particularly important component of short-term financing for a minerals company since errors, extra costs, or payment delays/defaults can easily wipe out the profit margin on a particular shipment or can cause problems when arranging purchases of e.g. reagents. It is required to make any minerals operation function and does not have to be cross-border to require proper management. Sources of working capital are as follows: 1. Extended credit terms from suppliers 2. Inventory loans from banks, finance companies 3. Accounts receivable financing or factoring 4. Credit lines or overdraft facilities from banks. TRADE CREDITS These are provided under the familiar terms "net 10 days" or payment due by the "10th day of the following month." Thirty days for payment is usual but longer periods can be negotiated with regular suppliers. Shipment may be made on open account with specified periods for settlement. In the mining industry, a custom smelter gains trade credit by paying for concentrates three months after the month of shipment. INVENTORY LOANS Various forms of inventory finance are provided via "floor-plan" or warehouse financing. A set percentage, usually 60%-80%, of a good-quality, readily saleable inventory item (e.g. bullion, concentrates, ingots) will be provided by a bank or finance company which will usually have security over these products and has a right to inspect the goods from time to time. Legal security will he achieved by warehouse receipts, floating liens, chattel mortgages, trust receipts, or through collateral management service companies. The latter certify control over stock or distribution outlets and often carry insurance against fraud. Costs range around 1.5% - 2.0% p.a. or more plus some fees to cover out-of-pockets or other costs. ACCOUNTS RECEIVABLES Accounts receivable financing is based on the company's generation of satisfactory receivables which are continuously assigned to a bank or finance company ("factoring"). Because of the risks in being able to collect receivables, such as payments to a smelter for its blister copper shipments to a refinery, this form of financing costs as much as 3% - 5% of the debt amount purchased plus an additional charge for processing paperwork. Receivables can be purchased with or without recourse and on a notification or non-notification basis to the client's customer to, respectively, pay the invoice directly to the bank or not. LETTERS OF CREDIT Letters of Credit ("L/C's") are a common feature of international trade finance whereby a bank, at the request of the buyer, issues a written undertaking to an exporter to pay a specified sum of money within a set time on presentation of previously specified documents. This undertaking means that the exporter is no longer relying on the credit standing and integrity of the foreign importer. A dispute about shipment does not otherwise affect the obligation to pay upon presentation of a "clean" set of documents. These documents include the hill of lading and other documentation, often on standard "form" bases. There are a number of conventions and techniques in L/C's such as irrevocable/revocable L/C's, time L/C's, confirmation/advising L/C's and transferable L/C's. These are tools to adjust for the varying risks that the importer will not pay. Other routes where one is comfortable with an importer include documentary sight hills (D/P hill), documentary term bills (D/A bill), and, of course, open account.

Jan 1, 1985

“IT is decreed by Divine Providence that those who know what they ought to do and then take care to do it properly, for the most part meet ' with good fortune in all. they, undertake; on the other hand, misfortune overtakes the indolent and those who are careless in their work." These are the words of Georgius Agricola. to. those who are engaged in mining, taken from De Re Metallica, Book II, second paragraph. Safety in mining is just that simple, when considered on the basis of the individual. The words imply a .knowledge of what is to be done and how to do it. Armed with this knowledge it is only necessary to proceed with diligence and care to achieve the desired end without personal or financial mishap. Obviously the complication arises in the large company operating numerous mines and the consequent ramifications of company structure embodying management, supervision, engineering, and labor. Agricola stresses later on the importance of supervision and direction by the owners of the mine. We know that this principle is recognized today by the frequency with which the statement is repeated "a safety program must stem from management." People charged with responsibility for safety and management also stress the importance of securing the cooperation of the employees in formulating and carrying . out safe working practices. Safety committees consisting of employees, supervisors, and. representatives of management are recognized as the most practical method of achieving safety consciousness in all levels of mining company organization.

Jan 1, 1952

By Louis Katona

The practical execution of the design for rolling-mills presented by the writer at the Paris meeting* of thc Iron and Steel Institute in 1900 involves the determination of some questions not yet discussed, among which is the determinatioir of the amount of power required to perform the rolling of pieces of iron and steel of given dimensions. It is necessary to know this factor if we would put motors of proper capacity to the respective pairs of rolls, or, rcciprocally, if, having standard motors at our disposal, we would design grooves to suit them. Moreover, this factor is involved in giving right dimensions to every part of the rolls and housings. Expert designers of engines for driving rolling-mills of the present type receive very indefinite directions, such as: that the motor is to drive a light, medium or heavy train; that it must work with fly-wheel or reversing gear; that the number of revolutions per minute should not exceed 40 or 60, and that at a given speed the power developed should be from 100 to 200 H. P., or from 1,000 to 2,500 13. P. It frequently happens, however, that an cngine of 200 H. P. is forced under the circumstances to press or develop as much as 300 H. P., while, on the other hand, the ,1,500-11. P. engine may be rolling-stock which could be worked with a maximum expenditure of 60 to 80 H. P. Of course such variatior~s as these do not permit the best adjustment of parts or the best economy of power and fuel. The design of roll-trains is even more vaguely limited. Every part of a train, from the point where it connects with the engine to the last groove in the rolls, bears evidence that there are no rules for calculating even approximately the dimensions of the main-shafts, couplings, pinions, gears, rolls, trunnions,

Jan 1, 1904

By Martin F. Milligan

THIS short discussion of the effects of deoxidation on the mechanical properties of cast steels is intended to serve as general introduction to the subject of this afternoon's session. The subject is covered in detail in Mr. Carter's excellent paper. My material has been collected from the works of various investigators, several of whom are present today. For a definition of deoxidation, as applied to steel-furnace melting practice, we can best go to Briggs' book, "The Metallurgy of Steel Castings." Briggs says that deoxidation "includes all the phenomena in the final preparation of steel that would permit it to solidify free from gas cavities and from dissolved oxygen of all kinds." Various practices are used by welters to produce these end results.

Jan 1, 1947

By Christopher Haycocks, J. Richard Lucas

The growth of computer and ground control technology in recent years, combined with an urgent demand for low-cost fossil fuels and mineral resources, has set the stage for full-scale utilization of computers in mine planning. Steeply rising production costs and the need to preserve the environment are placing great demands on engineers to improve their mining efficiencies, which can best be accomplished by applying the full capabilities of the computer. Pressure to develop and perfect programs with an immediate potential for improving mine design, reducing mining costs and extending the viable coal reserves of the country has already come to bear in the form of exploding energy requirements, environmental considerations and the visible limitations of other energy sources.

Jan 4, 1973