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By AIME

SUPPLEMENTING surveys of the engineering profession regarding salaries and advancement, based upon data from individual engineers, a survey through a questionnaire to employers of engineers has recently been made by a subcommittee of the Engineers Joint Council's Committee on the Economic Status of the Engineer. Its object was to learn directly from employers their attitudes and policies pertaining to the selection, training, placement, advancement, guidance, and professional activities of engineering graduate employes. The questionnaire was sent in May 1946 to 174 employers of engineers, including colleges. Replies were received from 104 employers in nineteen fields of industry, who employ about 2,000,000 persons, about 40,000 of whom are engineers. The following general observations are based on the questionnaires returned. Who Are Hired? Of the co-operators 96 per cent employ cadet engineers directly upon graduation from engineering schools, but only 4 per cent recruit their engineering staffs exclusively from the new graduates. About 43 per cent hire more than half of their new engineer employes after one or more years' experience with other employers. This is evidently a matter of necessity or expediency rather than preference, because more than sixty per cent of those reporting indicate that they prefer to hire the new graduate.

Jan 1, 1947

By Stanley W. Ivosevic

The South-Central Osa Peninsula produced around 30,000 kg (100,000 troy oz) of gold since prehistoric times. Gold freed by erosion from quartz lodes in the Mesozoic Nicoya ophiolite complex was reconcentrated through three generations of Quaternary sedimentary deposits. Resultant gold placers grade upward from 1 g/m3 (0.03 troy oz/m3) and are of moderate size.

Jan 1, 1980

James GayleY, New Pork City (communication to the Secretary*) :—The main thing that is sought after in this matter is that all purcliases shall be made by analysis. This is done already in special lines, as in the manufacture of various grades of steel in which phosphorus, silicon and sulphur are specified within narrow limits, and I quite agree with Mr. Cook that specifications, which are over-rigid in unessential particulars, should be avoided, as they defeat their own purpose because unreasonable requirements permitting no variation are practically not fulfilled, and it is impossible to specify grade

Jan 1, 1905

By B. M. Larsen, K. Heindlhofer

Jan 1, 1945

By Herty, C. H.

Three distinct processes take place during the conversion of iron ore to steel. First: the raw ore is reduced to metallic iron in the blast furnace and during this reduction certain constituents are dissolved in the iron, either through the solution of a solid into a liquid phase, as in the case of carbon, or by reduction of an oxide existing in the slag to the metallic element of that oxide, with subsequent solution of the metallic element in the iron. Thus by the process of solution and reduction, a pig iron results which contains about 4 per cent carbon, 1 per cent silicon, 1 to 2 per cent manganese, 0.1 to 0.4 per cent phosphorus, and 0.03 to 0.10 per cent sulfur. To obtain a sufficient yield of iron from the ore it is necessary that the reducing process be carried as far as possible, with the result that the impurities mentioned accompany the reduced iron. Second: to convert this iron into steel it is necessary to oxidize a part of the iron in eliminating the impurities to the extent desired for the particular product being made. In eliminating these impurities by oxidation a certain amount of iron oxide (FeO) dissolves in the steel. This dissolved FeO reacts with the metalloids, except sulfur, and to eliminate them to the desired extent it is necessary to leave a considerable amount of FeO in the metal. The reaction of iron oxide with silicon, manganese, and phosphorus results in the formation of the oxides of these elements. The oxides enter the slag and the extent of elimination of the elements depends on certain equilibria between the slag and the metal. The reaction of FeO with carbon results in the formation of the gases CO and CO, which, after saturating the metal, pass into the furnace gases. Third: after the iron has been purified to the desired extent as far as the elements listed are concerned, it is necessary to deoxidize the bath to remove the FeO, which is the vital factor in gas formation as the steel solidifies.

Jan 1, 1957

By A. S. Richardson

AIR conditioning, or air cooling, for the improvement of ventilation in the Butte mines has come into increasing use during the past 10 years. In part, the methods practiced have been described in previous publications of the Institute, but some improvements on earlier methods have been made and a number of new features have been developed. This paper is presented as a record of progress made, and for the sake of completeness describes all general features of the work. The need for air conditioning in the ventilation of mines in the district arises from the fact that the temperature of the ground and mine water has shown a very great increase with increase in mining depth, and has now reached a maximum of slightly over 130ºF. The most difficult part of the ventilation problem is the maintenance of temperature and humidity of a satisfactory standard in the working places, especially on the lower levels. Although ordinary ventilation is adequate to maintain good conditions in most of the working places it is subject to a number of limitations at great depth. Most important among these limitations is that with increase in depth the air becomes heated before it reaches the working places, both by compression from increase in atmospheric pressure and by heat transferred to it from rock at high temperature, so that its capacity for lowering temperatures is greatly reduced before it reaches the operating zone. Increasing depth of mining also increases the distance traveled by the air in its passage through the mine, and this causes a corresponding increase in resistance to air flow, so that there is greater difficulty in maintaining even the same volume in circulation. Thus, in the face of a demand that the ventilating system have a very much greater capacity to remove heat from the mine, the tendency is for that capacity to diminish. The only evident alternatives were (I) the opening of additional air shafts to increase the volume of air in circulation, (2) an extension of the existing system that would be subject to the same limitations, or (3) the adoption of an entirely different method such as air cooling. Fortunately for an economic solution of the problem, the mean annual temperature of the surface atmosphere at Butte is about 40°F., with very low relative humidity in summer, so that there is unlimited natural cooling power at a temperature range adaptable to air-conditioning methods. METHODS Two similar methods of air conditioning are used, as necessitated by service requirements and dependent upon the equipment available. In one, which is the more important and has the greater cooling capacity, water is circulated in a closed circuit, and, alternately, first absorbs heat from warm mine air and then dissipates it in the surface atmosphere by cooling at a cooling tower. The second

Jan 1, 1941

By AIME AIME

The first session, held Tuesday evening, February 23, in North Sheffield Hall, was called to order by Louis V. Pirsson, Chairman of the Local Committee, who introduced Prof. Russell H. Chittenden, Dean of the Sheffield Scientific School of Yale University. Professor Chittenden, in behalf of the Governing Board, felicitated the Institute on its visit to New Haven, and cordially welcomed the members and guests to the University and the city. Dr. James Douglas, who presided at the meeting, responded in behalf of the Institute. The Secretary announced that, upon the proposal of many members, the unanimous report of the Committee on Membership, and .the unanimous recommendation of the Council, the following members had been unanimously elected by the Board of Directors Honorary Members in the American Institute of Mining Engineers Prof. Richard Beck, of Freiberg, Saxony, in recognition of his distinguished service to technical literature, and the cordial

Apr 1, 1909

By George Otis Smith

A YEAR ago, ,at the Institute's dinner, I closed my A remarks with the words: "The scientist devotes his life to the advancement of learning; the engineer gives his to the advancement of living." May 1 begin tonight where I left off then and speak first of the distinction between science and engineering? This difference is a difference both in purpose and in method: it is the sharp contrast between theory and practice; it marks the broad gap between dream and attainment. Sometimes it happens that the investigator is also the builder and applies what he discovers, yet the distinction between science and engineering serves to point out the broad dependence of the engineer upon his brother the scientist. You remember .the old - saying that "where there is no vision the people perish" translate this into modern experience and we may say that "where there is no science, the engineer fails."

Jan 1, 1929

By F. T. Davis

Many contributors have added to the fund of knowledge in the basic sciences related to mineral dressing during the past year. During 1964, the French edition of the Proceedings of the VIth International Mineral Processing Congress together with discussions was printed. Also, complete Preprints of papers delivered at the VIIth IMPC were published in September1. Over a third of the papers presented at VIIth IMPC dealt with fundamentals. COMMINUTION It has been postulated by Ponceleta that flaws need not exist before a stress is applied but rather the flaws are created at the tip of a propagating crack at a stress well below the theoretical breaking stress.

Jan 2, 1965

By Paul Weir

FOR the first time in 1938, bituminous coal production for the week ending Nov. 19 surpassed that of the corresponding week in 1937, and indexes of industrial activity indicated the possibility that the remaining weeks of 1938 would run ahead of the corresponding weeks of the preceding year. But regardless of this year-end pickup, total production in 1938 was approximately 25 per cent less than in 1937. The estimate of 340 million tons for 1938 places the bituminous industry slightly above the production level of 1933 and approximately 10 per cent above the modem low of 1932. Anthracite production is not subject to the same extent as is bituminous coal to fluctuations arising out of the rate of industrial activity, hence the decline from 1937 has not been so great being approximately 14 per cent under 1937. The estimate for 1938 production is approximately 45 million tons, but this represents the lowest level reached in the last fifty years with the possible exception of several strike years.

Jan 1, 1939

By AIME AIME

EITHER the 2300 people who came to the Annual Meeting were in a better frame of mind or they were resigned to their fate, or it was a better meeting than usual. Whatever the reason, at the 1nstitute?s 148th meeting the attendance was better than ever before, things went more smoothly than in some previous years, and complaints appear to have been almost entirely absent. Patience was sometimes reauired but. almost without exception, it was forthcorning the well-known recession seems to have given many members enough leisure time to come to the meeting without depriving them of the tangible wherewithal to come.

Jan 1, 1938

By A. D. Hughes

A relatively small area in Malaya, about 200 miles long by 40 miles wide, is the most important source of tin in the world. Some tin is recovered in other parts of the peninsula. Of the tin mined, 98 pct is recovered from alluvial deposits. From 1935 to 1941 the average annual world production of tin was 190,000 tons. The average annual production from Malaya during the same period was 62,000 tons or about one third of the total. Other producing countries, in order of importance, were the Netherlands East Indies 34,000 tons, Bolivia 30,000, Belgian Congo, Nigeria, Siam, Burma, China, and a few others with smaller amounts. The serious shortage of tin during the war period was due to the fact that the Japanese were occupying Malaya, Netherlands East Indies, Siam, Burma, and China which, together, formerly were producing 65 pct of the world supply.

Jan 1, 1949

By L. K. Eigenbrod, F. Notaro

Enactment of Public Law 91-173 (Federal Coal Mine Health and Safety Act of 1969) has placed new responsibilities on the mining industry. The new law, aimed at eventually solving the problem of pneumoconiosis, sets new respirable dust standards at 2 mg per cu m. Techniques employed to date have been shown to lack total effectiveness in meeting the prescribed standards. Since it is possible that even the new standards will eventually have to be lowered to effectively attack the medical problem, the need for new and more reliable methods of assuring clean respirable air will intensity. This paper presents, in a preliminary manner, both the present technical capability and growth potential of cryogenic technology for supplying miners with clean breathing air. Work with two sizes of prototype supplied-air (cryogenic-liquid) respiratiors in Union Carbide's Fawn Coal mine, will be described. Other potentially fabricable systems will be discussed and a preliminary assessment made of the potential cost of introducing cryogenic air breathing systems in coal mine service.

Jan 1, 1972

By C. A. Stetefeldt

Jan 1, 1895

By Charles A. Stetefeldt

This treatise is the sequel of a paper on "Russell's Improved Process for the Lixiviation of Silver-ores," etc., read at the Chicago meeting, in May, 1884, and published in the Transactions, vol. xiii., page 47. The facts it presents are principally compiled from Mr. Russell's notes on his practical experience gained in various places where the Russell process has been introduced. For a complete understanding of this paper a perusal of my former one is desirable, as can be seen from the frequent references here made to it. All silver-ores that do not carry a large percentage of lead or copper can be treated by Russell's process with success and economy. I do not mean to create the impression that from ores containing considerable quantities of lead and copper a high percentage of the silver cannot be extracted by this process. Such ores, however, will, in many localities, be reduced to better advantage by smelting. In case lead-bearing silver-ores are suitable for concentration, it may be profitable to concentrate the ore by Krom's dry system, obtaining a smelting-product high in lead, and to lixiviate the tailings and the dust. This plan has been adopted in a mill recently erected in Cortez District, Nevada. The dry system of concentration deserves the preference because it delivers the tailings and the dust in a condition ready for chloridizing-roasting. In wet concentration the drying of the tail ings would be expensive, and there would be a considerable loss of silver in slimes. Oxidized ores, containing silver chloride and lead minerals, may be lixiviated after crushing, and the tailings may be concentrated for lead. In this case wet concentration would be most suitable. This has been done at the Old Telegraph Mine, Utah. I would give, however, the preference to dry concentration in all cases which, of course, requires that concentration should precede lixiviation. The Russell process is also adapted to the treatment of tailings resulting from ores which have been worked either by the old

Jan 1, 1887

By W. TRINKS

RAPID progress has been made in the automatic control of open-hearth furnaces in the past few years and many firms today\supply such control apparatus. It is somewhat surprising that so little was heard about open-hearth control up to about, 1928, and that thereafter the practice of automatically controlling open-hearth furnaces spread very rapidly. Before discussing the reasons for this it may be advisable to list the quantities that can be controlled. One of the easiest quantities to be controlled in the open-hearth furnace is pressure. The reasons for controlling it are plain. If there is excess pressure in the furnace, products of combustion leak out around .the .door and through all the cracks in the brick-work. The stability of the piers between the doors is seriously endangered, and front wall repairs become frequent. Furthermore, hot gases are lost that might be usefully employed in heating the checkerwork. If there is a slight vacuum in the furnace, cold air entering through the doors and cracks cools the interior, slowing down the reactions and making it impossible to secure the highest degree of preheat from the checkerwork.

Jan 1, 1931

Jan 1, 1897

By C. A. Fisher

THE discovery of petroleum in Pennsylvania in 1859 marked the birth of an industry of paramount importance. Spreading from - Oil Creek, this remarkable industry may be said to have embraced the earth in a little more than half a century. Those who made the discovery little realized its deep significance or far reaching influence on our national life. For over sixty years, during which time this nation has created and developed the oil industry to a high state of efficiency and' carried its activities to all parts of the world, we have' at all times been the leaders in the production of crude oil and in the development of its technology. During the unprecedented growth and expanse of the oil industry there has been an increasing dependency of our basic industries on, petroleum, until at present it has become essential to our national existence. To meet the ever increasing demand for petroleum and its products, we have explored, at one time or another, for their oil possibilities, practically all parts of the sedimentary rock area in the United States. Furthermore, detailed surface and, in many places, subsurface studies have been made of all the promising regions; over 640,000 jewells have 'been drilled for. oil since the beginning of the industry; $12,000,000,000 have been spent in this work; seventeen major fields exceeding 100,000 bbl. daily production and more than a thousand minor pools have been opened up, and 8,000,000,000 bbl. 'of oil have been produced, or an amount nearly equal to the estimated future reserves of the United States made in 1921.

Jan 1, 1925

By D. L. H. Forbes

(New York Meeting, February, 1912.) Introduction.. THE application of the cyanide process to complex sulphide ores for the extraction of their bold and silver is no longer a novelty, but, as an example showing modern tendencies in this direction, the following description of the new milling process at the Lucky-Tiger mine is offered: The extraordinary richness of the ore in the upper workings of this mine made any thought of milling in its early hays seen unnecessary. Its location in an almost inaccessible part of the rugged mountains just south of the Arizona boundary-line, and 60 miles from the town of Douglas, made the expense of bringing in machinery and supplies a very serious consideration. But, after the property had been shipping high-grade ore on mule-back for a few years, there remained in the mine a considerable tonnage of vein-matter that was too low in value to ship, but which it was thought could be milled near the mine at a profit. The first milling-experiment consisted in the installation of Nissen stamps in conjunction with concentrating-tables and Frue vanners, but, as the ore from the upper workings contained most of its silver in the form of cerargyrite, this type of mill was not successful. The proximity of the mine to the great copper-concentrating mills of Cananea and Moctezuma naturally made the influence of copper-milling, ideas felt in the company's next installation. At considerable expense a stage-crushing concentrating-mill, with a capacity of 100 tons per day, was built. This mill was modeled along the lines of the most approved practice in copper-concentrators at that time, the main idea being that crushing by stages in rolls was necessary in order to prevent losses from ?sliming." Largely owing to the fact that, when the mill

Aug 1, 1912

By R. E. Grant

THE Cerro de Pasco Railway Co., owned and operated by the Corporation, is a common carrier whose chief functions are transportation of ore and concentrates from the mines at Cerro de Pasco to the smelter in Oroya, and haulage of coal from the coal mines at Goyllarisquisga to the coal washery at Fundicion. Connecting with the Peruvian Central Railway at Oroya, the C. de P. Railway maintains joint, daily freight and passenger service from Lima and the port of Callao to Cerro de Pasco, terminal of the C. de P. main line and gateway to the Huanuco Valley. Extending from Oroya to Cerro de Pasco the main line is a standard-gauge roadbed of 70-lb. rail, 132 km. long with a maximum compensated grade of 2.25 per cent and a curvature of 16°, climbing from an elevation of 12,272 ft. above sea level at Oroya, lowest station on the line, to 14,208 ft. at Cerro de Pasco. The highest point reached by the C. de P. is on the coal branch at Alcacocha where the rails are 14,385 ft. above the sea.

Jan 1, 1945