Search Documents

By Joseph F. Shirley

A froth flotation plant to recover byproduct molybdenite must be designed specifically for the selected separation process and the type of ore being treated. However, some general rules concerning byproduct molybdenite plant design can be suggested that would be valid for most processes. The term byproduct molybdenite in this paper is limited to the recovery of molybdenite from copper porphyry ores, which essentially amounts to selectively separating molybdenite from copper and iron sulfide concentrates. In addition, most of the discussions would apply only to the almost universally used approach of floating the molybdenite and depressing the copper and iron sulfide minerals. Thickener It is considered essential that the feed to a byproduct molybdenite plant be thickened prior to being treated for molybdenite recovery for the following reasons: 1) Thickening allows the rougher and any preconditioning stages to be operated consistently at the optimum percent solids. 2) Generally, the size of equipment used for pretreatment and the rougher flotation is considerably smaller and less expensive than if the copper flotation concentrates were treated directly. 3) The removal of as much water as practical by thickening removes flotation reagents added in the copper flotation circuit, especially frother which can be quite troublesome in a byproduct molybdenite plant. Although thickening of the molybdenite plant feed has long been recognized as necessary to optimum metallurigcal results, very often this area has been designed poorly. The thickener should be sized so that it can produce a consistent thickened product containing 60 to 65% solids without the use of flocculants. Some plants are only able to thicken to 45 to 50% solids consistently while other plants let the percent solids vary from 45 to 60% over a 24-hr period. While the former is more desirable than the latter, in many cases better metallurgical results could be obtained if the percent solids could be held consistently close to 60%. Probably the simplest and most satisfactory system of handling the thickener underflow is to spigot it into a sump, using a sphincter type valve for the orifice, controlled by a density meter. Another satisfactory approach is to use an ODS type pump to meter the underflow. There are other methods of handling thickener underflow which work satisfactorily as long as the amount of copper concentrates entering the thickener is relatively uniform. However, they often fail to operate satisfactorily when there are large fluctuations in the thickener feed rate due to fluctuations in ore tonnage and/or copper grade. If the percent solids in the plant feed could be held close to 65%. There is the possibility the molybdenite plant tailing would not have to be thickened prior to the copper filter plant. This means that the molybdenite rougher float would have to be conducted at 45 to 50% solids with all the cleaner tailings returned to the rougher for dilution. Admittedly, in some situations this approach would be impossible, but if capital or plant area is limited, it should be considered.

Jan 1, 1981

Report of the Americanization Society, New York Section During the past two months the Americanization Committee has held social meetings of various kinds for foreign-born women, as a preliminary to future effort along the lines of Americanization work. At the same time, a thorough investigation was made as to the work being done in New York by organizations devoted to this interest. The committee will be very glad to help any other committees being formed, in mining centers, with advice and information that has been gathered together as to classes and meetings of all kinds best suited to the needs of a foreign-born population. The work has been so extensively taken up in New York that for the present it would seem to be, for this committee, the most profitable and interesting work to continue the social meetings and to undertake the care of one or more immigrant families, to be friend and adviser in joy and sorrow, work and play, and in this way do some fundamental Americanization work. Respectfully submitted, LAURA G. BURGER, Chairman.

Jan 6, 1918

By Nicklaus Heil, L. D. Clark

As political tensions in African and Asian mineral producing regions increase, the orientation of Latin America's economic development assumes importance not only in the U.S. hemispheric policy but also in our mineral-based economy. Latin America as a mineral supply source has been confronted with regional, political and economic problems which may, at best, have limited further investment and, at worst, have suggested possible repudiation of existing investments. Historically, the mining industry has provided a basis for the national economies of Bolivia, Chile and Peru, and recently the governments of these countries have sought to force increased development of the industry through new and somewhat revolutionary mineral legislation. The extent to which the mineral industries are intended to finance economic development is uncertain and the influence of this legislation on economic freedom and incentive for foreign and domestic investment is a matter for some thought. Two facts are outstanding: first, mining, at present, provides approximately 80% of the foreign exchange in Chile and Bolivia and 42% of that in Peru and, second, existing tax revenues are insufficient to finance a developing economy.

Jan 5, 1967

By D. E. Wolfson, D. A. Reynolds, F. W. Smith

IN 1948 the U. S. Bureau of Mines began a three- phase program to evaluate the extent and quality of U. S. coking coal: 1) a factual appraisal of known recoverable reserves in beds of mineable thickness, 2) a study of preparation characteristics, and 3) a study of carbonization properties. A previous paper presented the methods used in assessing reserves.' Although this investigation is only partly completed, data on coking properties of the Pittsburgh district coals are now available. The results are presented in this article. When coals are selected for manufacture of metallurgical coke more factors must be considered than for any other major use, as no basic industry requires coal of such high quality and uniformity. This is particularly true in the Pittsburgh district, where blast furnace practice is based on use of cokes from high quality coals. Although it is true that inferior coals are carbonized in other industrial areas, both here and abroad, the Pittsburgh coals are the best economically obtainable in the required tonnages, even though they are not the most desirable for metallurgical use.

Jan 3, 1957

By Eugene Guccione

One of the world's most respected scientists, Dr. Hans A. Bethe (see box) has concluded that if anything can solve the energy crisis, it will be coal and uranium. "It is an illusion to think that we can solve our problem by energy conservation alone. For the next few years, conservation must play a very important role, but at the same time, we must see and develop all our alternative energy sources," he said. In his series of five lectures on the energy crisis, given at the University of Utah while he was visiting professor there during February 1974, Dr. Bethe examined all the existing and newly proposed energy sources. He very quickly ruled out solar power, wind power, and tidal power. Solar power, he said, would be 3% to 4 times more expensive than nuclear energy and would only make sense in tropical areas; wind power, which could at best produce one-tenth as much energy as solar, is "for the birds;" and tidal power, which can be exploited in only a very few coastal locations, is "for the fish."

Jan 5, 1975

By T. T. Read

FOR the second time the Mineral Industry Education Division opened the sessions at the Annual Meeting by gathering at the Engineering Woman's Club, Sunday at 3 p. in., and, in spite of the informality of the hour, with a good attendance of representative men in the educational field. The chairman of the Division, Thomas T. Read, after briefly reviewing some of the more significant events of the past year, introduced H. P. Hammond, professor of civil engineering, Brooklyn Polytechnic Institute, a leading figure in the project of the Engineers' Council for Professional Development for accrediting engineering schools. Prof. Hammond made it clear that the project is not to rate engineering schools but to accredit them; not to arrange them in order of excellence, but to segregate them into two groups, those that are entitled to recognition as genuine engineering schools, and those that are not. About thirty schools in the whole country will presumably fall into the latter class; they are typified by an unnamed institution where the teacher of mathematics bears the title of Professor of Civil Engineering and the man who teaches chemistry that of Professor of Chemical Engineering, and having no engineering instruction except some elementary surveying, but still claiming in its catalogue to be an engineering college. While everyone would like to avoid the necessity of accrediting engineering colleges, it cannot be avoided, since the University of the State of New York, and several other agencies, are already doing it. If it cannot be avoided it is best that it should be done by a qualified agency set up by the national engineering societies, so that the results may command respect and general acceptance. It is for this reason, and this alone, that the accrediting committee of the E. C. P. D. has been set up. It is now ready to begin its task, and during-the coming year it will accredit the schools in two of the seven geographical districts into which the country has been divided, beginning with New England and the Mid-Atlantic States.

Jan 1, 1935

By Myron K. Rodgers

In rock- or ore-crushing tests all data, in order to be valuable for study and comparison, should be obtained and tabulated under conditions as uniform as possible. The results of many such tests have no value for comparison, because of incomplete data and the lack of uniform conditiops, screens and scale of sizing, etc. The purpose of this paper is to suggest a form of standard specifications which may be developed by the Milling Committee and approved by the A. I. M. E. for rock-crushing tests. It is not intended to discuss any theories of rock crushing. Reports of rock-crushing tests should include the following details: 1. Description of the machine employed (jaw or gyratory crushers, rolls, stamps,tube mills, Chilean mills, etc.), 2. Method and material (timber, concrete, etc.) of foundation. Much power is dissipated in the vibration of poor foundations. 3. Locality from which the rock or ore was obtaincd, and geological, mineralogical, and physical characters of the material. 4. The power consumption of the machine running with no load and with full load, the unit of power being 1 hp. per 24 hr, 5. The capacity of the machine in tons (of 2000 Ib.) per 24 hr. 6. The duty in tons per horsepower-day. 7. The screen analysis of feed and product by the proposed A. I. M. E. standard screen scale. On the foregoing statement, the following remarlrs are offered. Toughness of Rock Table P shows the relative crushing duty of the same machine on three different characters of rock, all other crushing conditions being the same. This table indicates that the specific resistance of the rock to crushing, may affect the crushing duty of a unit of power as much as 300 per cent. Perhaps this quality may be called toughness. It is not a function of hardness only. For comparison of tests, rocks should be divided into

Jan 1, 1916

1. Healthy and active Local Section organizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local. Sections should be recognized and stim¬ulated by appropriation of funds from the Institute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character, of meetings held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A . standing Committee on Local Section Appropriations, consisting of one past chairman of a Local Section, one member of the Institute's Executive Committee, and one member of the Finance Committee, shall be appointed by the President and shall pass upon requests for appropriations and authorize payments within bounds of the budget. The committee will be guided by the principles herein outlined, always having in mind the vital importance of healthy, active sections to the welfare of the Institute as a whole.

Jan 1, 1938

By Jose M. Sobral

The approximate production of petroleum in the various fields and for the country as a whole is shown in the following table, the figures for the later months of the year being estimated. Among the developments of the year may be mentioned the finding by the Standard Oil Co. of a small production, about 6290 bbl., at Aguas Blancas in the Province of Salta near the Bolivian border, and of about 88,000 bbl. at Lomitas, near Tartagal in the same province. The Government (Yaciementos Petroliferos Fiscales) in the last four months of the year also obtained about 6290 bbl, from Quebrada Galarce. .The oil found in Salta is of good grade and while the quantity is small great hopes of larger production are entertained. Approximate Total Argentine Production for 1928 Barrels Barrels Comodoro Rivadavia............................... 8,165,615 Plaza Huincul..................................... 783,514 8,949,129 Distribution of Production Government, Comodoro Rivadavia................... 5,165,159 Government, Plaza Huincul......................... 306,166 5,471,325 Private, Comodoro Rivadavia....................... 3,000,456" Private, Plaza Huincul............................. 477,348b 3,477,804 a The companies represented are Astra, 649,474 bbl.; Oriente, 42,237; Ferrocar-rilera, 1,337,380; Comp. Indust. y Comm., 609,092, Solano, 64,158; Diadema, 298,114. b Standard Oil Co. and a few smaller companies, Exploratory drilling has also been conducted around the Comodoro Rivadavia field. The Government is drilling at Vuela del Senguer south of Colonia Sarmiento and about 200 km. west of the main field hut the prospect of success is not as yet large. The country around Castillo, where the Royal Dutch Co. has property, is regarded more favorably. perhaps the most interesting event of the year was the discovery of a productive horizon at Comodoro Rivadavia about 200 m. below that previously exploited. This new horizon was found by the Ferrocarrilera Co. at 769 m. in its well No. 81, the previous yield for this

Jan 1, 1929

F. G. SMITH, Waterbury, Conn.-I would like to ask whether small amounts of iron give the maximum resistance at a low temperature, and if the large amounts of iron raise the temperature at which the maximum resistance occurs? That is, with a small amount of iron, will a maximum be at, say, 10°? F. E. BASH.-With the small amount of iron, the maximum is at a lower temperature, and with the increase of iron, the maximum increases; it seems to come to a maximum and then decrease; that is, increasing the iron up to a certain value increases the temperature at which there is a maximum of resistance, and any increase of iron beyond that value will start decreasing this temperature. With 2 per cent. of iron, the maximum is lower than for 1.5 per cent. which was the value that we found to be satisfactory. F. L. DRIVER,* Jr., Harrison, N. J.-I would like to ask what chance there is of the instrument companies getting together and deciding on standards for both manganin and constantan? We make both of these alloys in this country and we find that each one of the instrument com-panies who buy these materials require different standards of specific electrical resistance and thermal e.m.f. For instance, some of our cus-tomers require an electrical resistance in manganin or therlo of 240 ohms per circular mil foot and others require it with a specific electrical resist-ance of 270 ohms per circular mil foot. They buy these alloys in relatively small quantities so that it means much extra melting and supervision when making up small quantities for each consumer. If something could be. clone to eliminate this, it would be a benefit to the instrument com-panies, who could secure their material more cheaply, and to the manu-facturers, who would not have to spend so much time and effort in special manufacturing.

Jan 12, 1919

By T. S. Lundy, F. R. Winslow

DIFFUSION coefficients of Hf181 in the high-tem-perature bcc phase of reactor-grade hafnium were determined at temperatures of 1795° to 1995°C by standard lathe-sectioning techniques. The temperature dependence of the data may be described by an Arrhenius-type expression for this limited temperature interval. However, hafnium is classed with the "anomalous" bcc metals zirconium, titanium, and y uranium by the low values of Do and Q observed in this study. The hafnium metal was received as 1/2-in.-diameter crystal bar. Analyses by the Analytical Chemistry Division of Oak Ridge National Laboratory showed the major impurity to be zirconium— about 2.1 pct. The total interstitial content was about 225 ppm with 190 ppm of this oxygen. The Hf"' was supplied as HfC12 in HC1 solution by the Isotopes Division of Oak Ridge National Laboratory. The hafnium bar was cut into disk-shaped specimens 3/8 in. long. One of the flat faces of each specimen was metallographically treated and then the isotope was deposited by vacuum evaporation from a tungsten filament. A 3 by 3 in. NaI (Tl) crystal with a single-channel analyzer was used for counting y rays with energies of 0.3 to 0.7 Mev. The as-deposited layers of isotope had counting rates of about 200 counts per sec. Specimens were annealed in argon in a tantalum resistance furnace. Temperatures were measured with a microoptical pyrometer calibrated for the particular furnace sighting conditions. All sectioning was done by standard lathe techniques. Section weights were determined on a semimicrobalance. A density of 12.5 g per cu cm was used in determinations of section thicknesses. Activities associated with the various sections were measured and the penetration data were treated using the computer code by winslow.' In all cases, except for specimens annealed at temperatures below 1795°C, normal Gaussian penetration behavior resulted. At lower temperatures, plots of In A(x) vs x2 were nonlinear [~(x) = relative activity at a distance x from the

Jan 1, 1965

By E. L. Davis

There have been many attempts to devise formulas for flowing efficiency and flow friction of oil-gas mixtures in oil-well flow tubes. Actually, however, flowing efficiency is rarely any real concern of the oil producer and flow-friction formulas contain so many unknown variables as to be of little, if any value. The production engineer is generally concerned with producing as much oil as possible with a minimum expense per barrel, and with the lowest possible net gas-oil ratio. These ends frequently are opposed to each other and the gas-oil ratio usually is sacrificed. In competitive operations, such as in town-lot fields, high current production is the sole interest. In conservative operation the greatest possible amount of oil obviously should be produced by natural flow unless the net formation gas-oil ratio can be improved by circulating gas. In practice this condition frequently exists. It would be a great advantage if the flowing condition of a well could be analyzed to determine the best possible producing status. Anticipating the death of a well so that gas-lift could be started immediately after the death, or preferably before, would save both production and expense. Frequently it happens that circulating gas fails to help a flowing well, or will not flow it after it has stopped flowing naturally. A knowledge of the laws governing flow would save considerable expense in testing such cases. A predetermination of probable pressures and amounts of circulating gas needed to flow wells and give best possible producing conditions would help in designing compressor installations. The optimum producing status of an oil well generally may be obtained by the conditions that subject the producing formations to the least possible back-pressure. This pressure is made up of the weight of the fluid column, frictional resistance to flow and the reaction from the acceleration of the fluid mass. A mathematical calculation of these components to arrive at a condition giving a minimum summation is impractical. Formulas would be complex and the results untrustworthy because it is impossible to assign proper values to the many variables involved.

Jan 1, 1931

By Paul D. Merica, L. J. Gurevich

In connection with other investigations on the properties and characteristics of chilled-iron car wheels, the question as to the best range of annealing temperatures was raised. Chilled-iron wheels are cast with a chill against the tread and the inside of the flange, the remainder being in sand. The composition of the metal is so chosen that under these conditions the trcad and inside of the flange will show white iron to a depth of from 5/8 to in. (15 to 22 mm.), the remainder of the wheel becoming graph itized or gray. In order to relieve the stresses set up during cooling under such drastic conditions, the wheels are stripped from the mold, while still red hot, piled in a soaking pit, and allowed to cool very slowly from their temperature at stripping. Obviously the most suitable temperature for this annealing is the highest at which no formation of graphite occurs within the white tread and at which the wheels can be stripped from the molds. Inasmuch as no direct determinations have been made of the temperatures at which the formation of graphite takes place in white iron of compositions used in car wheels upon annealing, it was considered worth while to determine these temperatures as a means of establishing the maximum temperatures at which the annealing of the wheels may be carried out. In the course of this work, some incidental observations were made which are of interest in connection with the theory of graphitization in whitc iron. The literature on the subject of the formation of graphite both during cooling at casting and upon annealing is very extensive and can be best studied by reference to a comprehensive discussion of the subject by Hatfie1d.l Perhaps the most important contributions of previous investigation are the following: 1. Whether a given mass of molten iron becomes white, mottled, or gay upon casting, depends on its composition and its rate of cooling through the temperature range of solidification and immediately below. 2. The more rapid the rate of cooling, the less is the extent of graphitization.

Jan 1, 1920

By W. A. Sweet

The furnace I am now about to describe was designed to obtain and maintain very high temperature. Knowing the cost of the gas furnace that was in successful operation here and abroad, I approached the subject with some misgivings as to my ability to attain anything like success, or even to reach a point of advancement. There seemed to be a field for a furnace of moderate cost for small mills, or where a particular heat was wanted, but the work was not enough to warrant the outlay necessary to build any gas furnace yet brought before the public. The section, Plate V, represents the furnace as I now build it for

By W. A. Sweet

THE furnace I am now about to describe was designed to obtain and maintain very high temperature. Knowing the cost of the gas furnace that was in successful operation here and abroad, I approached the subject with some misgivings as to my ability to attain anything like success, or even to reach a point of advancement. There seemed to be a field for a furnace of moderate cost for small mills, or where a particular heat was wanted, but the work was not enough to warrant the outlay necessary to build any gas furnace yet brought before the public. The section, Plate V, represents the furnace as I now build it for

Jan 1, 1875

By W. A. Forbes

by the combustion of this gas as it reached the air was a familiar sight in the days when open-top furnaces were in vogue. As blast-furnace practice progressed, however, involving the use of hot blast and the development of power from the gas, blast-furnace construction was modified to conserve this gas for heating hot-blast stoves, raising steam under boilers, and various miscellaneous purposes. When the use of blast-furnace gas was extended to the driving of gas engines, the necessity for thoroughly cleaning the gas became apparent., and soon the advantages of also properly cleaning the gas for use in stoves and udder boilers became more fully recognized.

Jan 10, 1913

By E. W. Felegy

THE need for improved mine communication to increase efficiency and to insure greater safety has long been recognized. General and unrestricted communication between all points underground, and between the surface and all points underground, is probably the least advanced phase of the mining industry. An ideal system of mine communication must re- quire no fixed wire installations. The equipment must be small, lightweight, and readily portable, and the power requirements low. A system that can be used not only under normal circumstances but also in an emergency, when the continuity of wires, tracks, and pipelines may be disrupted, must function independently of any aid furnished by standard installations.

Jan 5, 1953

By John E. Caffrey

The Federal Coal Mine Health and Safety Act of 1969, Title III, Interim Mandatory Safety Standards for Underground Coal Mines, is devoted to protection of workmen from hazards of electricity, roof, ribs, fire, and explosions. The Rules and Regulations, promulgated through the Federal Register, provide the criteria by which the law would be administered. Certain aspects of the law involve features that could be summarized under entrapment. These are sections 303 (y)(1), (y)(2) and 317 (f) (4). This paper is intended through the use of the figures to describe how these features of the law affect mine ventilation design, what are the problems, and possible solutions to them.

Jan 1, 1974

By Niles E. Grosvenor

Complex underground mining problems are increasing as mining depths increase. Many of these problems have been solved mainly by unsystematized trial-and-error methods based on individual experiences. This system of solving mining problems has resulted in over-cautiousness whereby a large quantity of our mineral resources are left in the ground, or not enough caution with a resultant failure of the underground opening. From studies made of physical properties of rocks, large volumes of data have been collected as a source of finding correlation among the different physical tests or among certain rock types. Most of these studies have not produced satisfactory results because the investigator usually arrives at the conclusion that the results are too scattered to be reliable. The reasons usually given as the cause of this scatter are that rocks are nonhomogenous and non-isotropic. Similar types of poor correlation that were being obtained from compression tests in the Colorado School of Mines Mining Research Laboratory led to an investigation of a good method of making a simple unidirectional compressive strength test.

Jan 1, 1963

By H. M. Chance M

The following tables have been compiled from the annual reports of the Inspectors of Mines, to determine the percentages of fatal and non-fatal casualties from roof-falls and explosions of fire-damp. As we cannot assume that every accident has teen recorded by the inspectors ; as many casualties terminating fatally after the lapse of a considerable period, are inevitably recorded as " non-fatal;" and as clerical errors may have crept into the compilation,* the figures of these tables cannot be considered absolutely correct, but the summary is sufficiently reliable to show the features I wish to differentiate. Under the heading " Miscellaneous" are included all accidents not directly attributable to explosions of fire-damp, roof-falls or fails of coal. Prominent among the numerous causes included under this head are premature or delayed explosion of blasts, accidental explosion of powder or cartridges, accidents from mine cam, falls in shafts, machine accidents, sliding of loose coal in pitching breasts, suffoca tion by choke-damp, etc., comprising in all 48 per cent. of the total number of casualties.

Jan 1, 1882