Search Documents

By A. C. Stevenson

THE hoisting equipment selected for use at the Hecla mine in 1907 was one of the first Ilgner type Ward-Leonard controlled hoists put into ser- vice. Development of the Hecla below the 2000-ft. level, which is the ultimate depth of the old equipment, and the additional service required by the "Star," necessitated additional hoisting capacity. It will be our endeavor to give j70u a brief summary of the engineering which determined the selection of the new equipment. The engineer in making his decision as to size, speed, etc., must .make a duty study approximating as closely &s possible the actual opePating conditions which will eventually result. Primarily, it is necessary to know what work must be done. The amount of material which must be hoisted under the maximum condition, as well as its distribution from the various levels of the mine was carefully studied by the mining engineering department, as the ore reserves, their relative-position and the probable method of working them had to be considered. The final figures reached, taking into consideration four different operating conditions, were, in tons per day, as follows:

Jan 1, 1930

By Thamiris Auxiliadora Gonçalves Martins, Karen Espina Gomes, Amilton Barbosa Botelho Junior

The present work aims at the synthesis of nanoparticles of copper by chemical reduction in microwave oven. The solution used comes from the selective copper precipitation of the lateritic nickel leachate. The copper solution (20mL) was placed in a beaker, and 2mL of 100g/L ascorbic acid and 20mL of 20g/L sodium citrate were added in that order and at room temperature. The pH of the mixture was corrected with 1M sulfuric acid or 2M sodium hydroxide. Then the mixture was placed in a microwave oven. The effect of pH, time and microwave power were evaluated. The morphology, composition and size of the particles were verified in Scanning Electron Microscopy with Energy Dispersion Spectroscopy (SEM/EDS). Results showed that the particles formed had no nanometric size. This may have occurred because the reducing action of ascorbic acid together with sodium citrate generates a very rapid reduction rate, which makes it impossible to form particles on a gauge scale. Particles synthesized at pH 4, after 4 minutes of reaction with 1000W of power presented particles with spherical morphology and only copper in the composition.

Oct 3, 2019

By W. N. Roberts

Hadfielcl steel has been studied by transmission electron microscopy to determine the microsl.rtic-ture of the cold-worked material, which has been a subject of controversy for many years. The presence of fcc deformation twins in specimens deformed in tension, by hamnzering, and by explosive -shock loading at room temperature lzas been established by electron diffraction. No evidence of a mar tensite was detected in any of the speciwens. Small amounts of E martensite were idenLified in the hamnleved specimens. DESPITE numerous researches on Hadfield steel since its discovery in 1882, there is still disagreement on the nature of transformations in the cold-worked material. Collette el al.,' using X-ray and electron diffraction, have found evidence for stacking faults, E martensite, and a martensite in Hadfield steel deformed in tension at room temperature. Nishiyama and Simizu,' using electron microscopy, have found stacking faults and E martensite in hammered Hadfield steel. White and Honeycombe have concluded from X-ray diffraction that Hadfield steel remains fully austenitic even after severe cold work at -196 Previous work by the author, indicating the presence of a, martensite in deformed Hadfield steel, was in error due to a faulty interpretation of the electron-diffraction patterns. Various workers,5'7 over the years, have speculated on the presence of deformation twins in Hadfield steel, largely from such circumstantial evidence as the persistence of slip bands with repeated polishing and etching, the presence of serrations in the stress-strain curve, and the absence of evidence of a martensite by X-ray measurements. The advent of electron-transmission microscopy and se- lected-area diffraction has made possible the positive identification of fine deformation twinning. PROCEDURE For tensile tests, standard ASTM specimens of 2-in. gage length, ground from 0.12-in. Hadfield steel sheet, were solution-treated at 1050°C for 30 min in a salt bath, to avoid decarburization, and water-quenched. The grain size was about 0.01 sq mm. Chemical analysis of the steel after heat

Jan 1, 1964

By Paul Downing

When was the last time the documents and paperwork were cleaned out of the glove boxes, door pockets, under the seats and above the visors in your company vehicles? Insurance cards that expired three years ago and vehicle registrations from 1999 through 2003, for instance, don’t do any good and just take up space

Jan 1, 2008

The Mine Safety and Health Administration (MSHA) has conducted studies to evaluate dust control technologies on deep cut continuous mining sections. These surveys have been conducted in different mines using various mining methods, face ventilation systems and dust control systems. The surveys typically consist of respirable dust sampling combined with a time study of mining activities. Measurements of dust control and operational parameters are also made. Critical elements identified for controlling respirable dust in deep cut mining systems include controlling intake dust, dust collector capacity, face ventilation quantities and velocities, positioning of workers, work practices and selection of equipment. This paper discusses how the dust surveys are conducted in deep cut mining sections and how these surveys are used to identify specific dust generating sources.

Jan 1, 1999

By Morris Cohen

This paper deals with the calculation of the composition of the infinitesimal trace of alloy that transfers from the liquid to the solid state at each temperature during the equilibrium solidification of a binary solid solution, and which thereby enables the compositions of the coexisting liquid and solid phases to follow along the liquidus and solidus lines respectively during the cooling. A general expression for the composition (S) of the liquid-to-solid transfer at each temperature has been derived S - ZLXL(XL - P) + Zsxs(P - XS) ZL(xL - P) + Zs(P - XS) where ZL and Zs are the slopes of the liquidus and solidus lines at the given temperature, XL and xs are the composi-tions of the stable liquid and solid phases at the same temperature, and P is the composition of the alloy under considera-tion. The S equation is valid for the process of equilibrium heating as well as cooling, and may be applied to vapor-to-liquid, vapor-to-solid, liquid-to-liquid, and solid-to-solid transfers if the corresponding equilibrium diagrams are known.

Jan 1, 1940

By P. Wynblatt, J. E. Dorn

The effect of strain rate, temperature, and interstitial impurity concentration on the flow stress was investigated in a poly crystalline Fe-2 pct Mn alloy. The temperature dependence of the flow stress was found to be independent of the interstitial impurity concentration, removal of interstitials merely decreasing the atherma1 stress level. Below 160%, the large temperature dependence of the flow stress was interpreted in terms of the Dorn-Rajnak theory of the Peierls mechanism of plastic deformation. Above 160"K, some other thermally activated intrinsic meckanisln seems to be operating. The strong temperature dependence of the flow stress of bcc iron at low temperatures has been studied by numerous investigators and interpreted in terms of several different thermally activated dislocation mechanisms. The following mechanisms have been proposed: a) interaction of dislocations with interstitial impurity atoms1 or with solute atoms in general; b) interaction of dislocations with clusters of impurity atoms;3 c) resistance to the motion of dislocations due to jogs on screw dislocations;* d) resistance to the motion of dislocations due to the Snoeck effect;' and e) interaction of dislocations with the intrinsic resistance of the bcc lattice or Peierls "hills". In previous work: it was found that the plastic behavior of polycrystalline iron containing 2 wt pct Mn (and 100 ppm C + N) is in good agreement with predictions based on the Peierls mechanismlo from 77" to 160°K whereas from 160" to about 370°K another as yet unidentified thermally activated mechanism is operative. The purpose of the present investigation was to determine the effect of interstitial impurities on the temperature dependence of the flow stress, by purifying the previously investigated alloy with respect to interstitial impurities. The investigation revealed that removal of the interstitial impurities to a level that eliminated Cottrell locking and the Portevin-LeChatelier effect (i.e., serrations in the stress-strain curve due to dynamic strain aging) affects neither the strong temperature dependence of the flow stress at low temperatures nor the general characteristics of the higher-temperature behavior. Such purification, however, lowered the athermal yield stress. I) EXPERIMENTAL PROCEDURE AND RESULTS The material used in this investigation consisted of an Fe-2 wt pct Mn alloy having the following additional elements present: 0.004 pct C, 0.006 pct N, 0.05 pct 0, 0.004 pct S, 0.003 pct P, and 0.001 pct Si. This was the same material as that studied in the previous investigation and will henceforth be referred to as the "impure material". The as received -jr by 2 in. hot-rolled bars were cold-rolled to 0.08-in. thickness, recrys-tallized under argon for 30 min at 80O0C, and further cold-rolled to 0.053-in. thickness. Flat tensile specimens 3 in. wide having a 1.625-in.-long gage section were machined from the sheet and then purified. The first stage of purification consisted of holding the specimens at 850°C for 24 hr in a stream of hydrogen saturated with water vapor at room temperature. Material prepared in this fashion will subsequently be referred to as "wet hydrogen purified material". It has been estimated that this type of treatment reduces the carbon content of iron to less than 5 ppm.' The second stage of purification consisted of holding the specimens in a closed system through which hydrogen was circulated past the heated specimens as well as a zirconium hydride getter. The specimens were held at 850°C and the getter at 800°C. The process was continued for 212 hr. The starting material for this process was wet hydrogen purified material. Material prepared in this manner will be referred to as "ZrHz purified material". The technique used was substantially the same as that described by Stein et al.' who have shown that the carbon level at the end of the process is reduced to about 5 parts per billion. The mean grain size of the three materials was found to be -60 C( for the impure material and -160p for the wet hydrogen and ZrHz purified materials. All tensile testing was carried out on an Instron Testing Machine either in controlled-temperature baths or at fixed-point baths such as boiling liquid nitrogen, and so forth. When fixed points were used the temperature was kept constant to better than *1°C whereas in all other tests the temperature variation was less than *2°C. Test of Purity. It was not possible to determine the purity achieved at each stage of the purification because the resulting level of interstitial impurities was near or below the limit of sensitivity of standard analytical techniques. It was possible, however, to obtain a qualitative measure of the extent of purification from the appearance of the stress-strain curves for the three materials. Fig. 1 shows the stress-strain curves for the three different materials tested at 300°K. It can be seen that the effect of wet hydrogen

Jan 1, 1967

By J. G. Donaldson

Nickel containing less than 0.01 percent of total metallic impurities was produced at the Rolla Metallurgy Research Center of the Bureau of Mines by electrodeposition from purified electrolytes. The first report on this research4 described purification of electrolytes by selective precipitation and by liquid-liquid extraction. This second report describes a procedure: or electrodepositing high-purity nickel from electrolytes purified by passing a nickel ammine solution through a column of an ion exchange resin. The nickel electroplated directly from the ammine solution without further treatment; a titanium cathode and two platinum anodes were used. The nickel deposit was dense, smooth, and adherent, and contained less than 0.001 percent each of cobalt, copper, and iron, and spectrographically detectable traces of aluminum, magnesium, and silicon. Nonmetallic impurities in the nickel metal were carbon and sulfur, each present in concentrations of less than 0.01 percent. The results of several experiments planned to purify solid nickel salts by zone refining are also reported. These salts, after purification, were intended for use in preparing electrolytes for deposition of high-purity nickel. Results were not encouraging so that the more promising ion exchange procedure was emphasized chiefly.

Jan 1, 1962

By Charles H. J. Patterson

When coal is deposited on the decks of pneumatic tables, all fine particles clinging to the larger pieces are blown free by the air. Inasmuch as the air retains an appreciable residual velocity after passing through the bed of coal, it is capable of suspending particles of goodly size. This velocity is dissipated gradually and, unless confined, can readily extend beyond the limits of the plant. Today the ideal in the design and operation of pneumatic cleaning plants is not that they be no dustier than the ordinary tipple, but rather that they be as clean as an office or shop. This degree of perfection may not yet have been attained in any commercial plant, but it is not impossible of achievement. Not until recently has the recirculation principle been applied to pneumatic separating plants. In the writer's estimation, it has not yet been proved entirely satisfactory in commercial installations. A serious obstacle lies in the fact that it is practically impossible to provide a truly closed circuit. The air circuits must be interrupted at certain points, if only for the introduction of raw material and for the recovery of the finished product. It is feasible to prevent the escape of polluted air at these points, but this can scarcely be accomplished without admitting additional air into the circuit. These additions of air are cumulative, which necessitates means for emitting to the atmosphere the excess while still carrying its objectionable burden, if provisions are not made for conditioning. If it must be provided at all, conditioning is frequently simpler and more economical if applied to the entire volume of air involved. This procedure eliminates the extra initial cost and operating expense of the closed system. Crane Cheek Experiments The first noteworthy commercial installation of pneumatic equipment was made in 1922, at the Crane Creek plant of the American Coal Co. of Allegheny County, at McComas, W. Va. Six tables for cleaning coal between the limits of and 3 in. comprised the initial installation. Dust was collected by hoods connected by a system of ducts to exhauster fans. In this installation the unit dust burden was small, owing to the removal of fines from the feed by vibrating screens.

Jan 1, 1931

By Grady B. V, Ault A. R, Newman O. M G, Fraser R. J, Malcolm J. McPhersqn

In all electrolytic zinc plants cadmium is removed as an impurity prior to the zinc electrowinning stage of the process. Cadmium metal is the favoured form of this by-product and most plants use an electrolytic route for its production. The formation of dendrites in cadmium electrowinning processes is the major limitation to deposition rates. There is an economic incentive, therefore, to better understand the factors affecting their growth. A technique that has been used by others to examine fundamental aspects of dendrite growth has been applied to industrial strength electrolytes. It involves potentiostatic deposition in a cell containing the electrolyte of interest. The variation in the current with time at a given overpotential allows the determination of the dendritic growth induction time. A method was developed (the Locus method) from the investigation of a set of such potentiostatic curves, obtained over a range of applied overpotentials, that appears to give a measure of electrolyte quality with respect to dendritic growth in galvanostatic deposition. The Locus technique predicts that zinc at industrial concentrations in cadmium electrolytes should have a significant effect on morphology and that deterioration of morphology will occur as the zinc concentration in the electrolyte is increased. This effect is consistent with literature prediction and was shown to relate to a reduction of the diffusion limiting current density. Magnafloc R333 is used as an additive at Pasminco Metals-EZ to control the morphology of cadmium deposits and the Locus method was successful in predicting its dendrite inhibiting properties. A possible mechanism is discussed. This work has opened avenues for future research with respect to a technique that may have an industrial application in electrolyte characterisation and has pointed to a direction in which better understanding of galvanostatic dendritic growth may be found.

Jan 1, 1993

By Gilman Y. Murray

The problems connected with the development of economically acceptable water supplies in arid regions are discussed. The techniques for capture and retention of runoff from infrequent desert storms are described and the major factors involved are emphasized. The exploration and planning for a typical water development in southwest United States is described, including an analysis of capital and operating costs for the proposed system.

Jan 1, 1963

The title of this paper suggests rather a comprehensive survey of the industry, but since it is not possible to do justice to this in a short paper, and, as the bulk of the Australian trade consists of buttwelded tube, the author proposes to deal only with this type.The buttweld process has been praetised for many years and, as the methods of manufacture are not widely known, a brief history of its development may be of interest. Few good reference books in the English language are available, and this reticence may possibly have retarded advancement in manufacture.The earliest method of making ferrous tubes consisted of bending a thin plate or strip to form a "skelp." The "skelp" was then raised to a welding heat and hammerwelded on an internal mandrel on a smith's anvil. Necessity, however, soon produced mechanical methods of making tubes, and, in 1812, an Englishman named Osborn patented machinery for "welding and making barrels of fire-arms and other cylindrical articles." The apparatus was arranged as shown in Fig. 1.The skelp was raised to a welding heat and placed in the swage block "A." A mandrel was then inserted and the tube lapwelded by the action of the tilt hammer.Various modifications of this apparatus quickly followed, to keep pace with the rapidly growing demand and the exigencies of war. These tubes were essentially of short length and mainly used for gun barrels. The advent of coal gas for lighting (patented by Murdoch) created a demand for small tubes of longer length, and necessity, as usual, produced a solution. In 1824 Jas. Russell, from *Works Manager, Stewarts & Lloyds (Australia) Pty. Ltd.

Jan 1, 1935

By AIME AIME

THE twenty-second annual meeting of the Canadian Mining Institute was held at the King Edward Hotel, Toronto, on Mar. 8, 9, and 10, and was followed on the 11th by an all-day excursion to the International Nickel Refinery at Port Colborne. The meeting was very well attended and dealt with some of the most important matters, both technical and economic, that have ever come before the Canadian Institute. The question of licensing engineers is before the Canadian members as it is before our own in this country and the attitude of the mining engineers across the border is like that of the American mining engineers, opposed to the licensing of the mining. engineer, however they may feel toward the licensing of other branches of the engineering profession. It was well pointed out that such a law, had it been in existence in the last decade or two, would probably have prevented the rapid development of Canada's mines. Whereas one civil engineer can run a line of survey as well as another, perhaps, it is only a question in his case of whether he can or cannot survey. In the case of a mining engineer employed by a man with capital to invest in a development project, unless the man with the money has confidence in the judgment of his engineer the fact that he is a professional man would carry little weight in inducing a large investment toward the development of Canada's resources. It was also pointed out that although the Institute as a whole had not passed on the matter, it would probably be opposed to legislation aiming only for self-interest, but would be heartily in accord with legislation which could be shown to be for the service of the community at large.

Jan 1, 1920

By Herbert Dlaska

The BBU - rotary hearth treats lead concentrates and battery scrap by the roast-reaction process. It corresponds in principle to the long-known Newnam hearth, however its hearth-basin is not straight but curved to a closed ring. In operation this annular hearth is filled with liquid lead and rotates around a central blast-box. The charge, heated to a glowing-red, floats on top of the lead bath, into which air is blown from the blast-box through a horizontal slot-type tuyere. Ore pellets and brown coal are continuously charged onto the reacting mass from two storage bins. Lead is set free by the roasting reactions and trickles through the charge into the lead bath from where it is tapped from time to time. The reacting mass is continuously stirred by a mechanical agitator and backed, by a mechanical shovel, against the water-jacketed wall of the blast-box. The gangue of the charge forms lumps of scorified character, the so-called hearth slag or grey slag, which are discharged from the hearth. The waste gases are collected in a hood and conducted to a baghouse from where the fumes and dust are automatically transported to the pelletizing installation and are recycled with new material. The daily output of lead bullion depends mainly on the lead content of the charge. With lead concentrates containing 74% lead, about 24 tons of lead bullion per day are produced on the hearth at a direct lead recovery of about 89 per cent. Approximately 10 per cent of the lead content of the new material passes into the hearth slag from where it can be recovered in a blast furnace or in a rotary furnace. For small lead smelters the BBU-process represents the most economical way of melting high-grade lead concentrates. The process requires a relatively small capital investment, consumes little fuel, utilizes cheap fuel and is very flexible. Further, of great importance, is the fact that battery scrap can be treated by the BBU-process with very good results.

Jan 1, 1970

In the Philippines, where distances are spoken of in terms off fight time, the Sipalay copper mines are two flight hours southeast of Manila on the island of Negros. After landing at the airport in Bacolod, it is then 170 km (106 milers) by surface transportation to Marinduque Mining and Industrial Corp.'s expanding copper operation. While copper deposits were discovered in the area in 1936-and one mine, the Binulig, began operations soon after-it wasn't until 1956 that stripping at Sipalay and construction of a 4000-t/d (4400-stpd) mill began. The mill went into operation in May 1957, and the first shipment of copper concentrate was made three months later.

Jan 8, 1978

By James A. Commins

Accurate engineering predictions of energy needs for pollution control equipment used in surface mining operations is critically important to sound management selection of control alternatives. This paper will describe a procedure for evaluating two control alternatives with different energy needs. Three steps are involved: an analysis of the pertinent regulations, a determination of the size distribution of the particles being emitted, a calculation of the energy needs and costs of the candidate control systems as a function of these regulations and emission characteristics. The principal air pollutant to be controlled in surface mining operations is particulates, or dust, some of which is already on the material introduced into the primary crusher and other dust which is generated by the various steps in the subsequent processes. The requirement for control stems both from regulations concerning workers at the operating site, and the community surrounding the operations. In order to speak quantitatively about the need for control we will use regulations that pertain in Pennsylvania although it must be borne in mind that such regulations vary according to juristiction.

Jan 1, 1975

By Milton H. Fies

The dedication of thin building, establishing a station of the U.S. Bureau of vines at the University of Alabama, bristles with significance and challenges the wisdom and courage of the people of this State. Here is united, in common aim, the Engineering School of our State University, recognized for its competency and usefulness, and the Federal Bureau of Mines. The Bureau is one of the most effective arms of our National Government. It outranks in accomplishment, measured by practical scientific contribution, any like governmental organization in all the other nations. It possesses none of the characteristics of many other bureaus of government which have created popular bias. Here is one Bureau devoid of political suggestion or aim with a personnel zealously devoted to labor in scientific re¬search - an organization marked by practical accomplishment, alleviating many of life's burdens, raking easier life's pathway, and unerringly pointing to life's possibilities.

Jan 1, 1936

By Michael J. Messel

THE critical shortage of asbestos fiber in the world today brings to the foreground the question of locating and developing new deposits. The object of this paper is to discuss some of the more important factors which should be considered in the examination and valuation of a new asbestos enterprise. Some of the more important uses of asbestos fiber are for textiles, heat insulators, building materials, filters and a series of other uses. The properties of this mineral, such as fibrous structure, color, strength, silkiness and flexibility, coupled with resistance to fire, certain chemical action and decay make its application unique for certain industrial uses which consume over 500,000 tons annually. These same unique properties which make this mineral so valuable also make a deposit one of the most difficult to appraise accurately, because of the many undeterminable and varying factors which must be considered before a deposit can properly be termed commercial. The majority of the asbestos fiber today, having the above mentioned properties, is sold by grades which are based on fiber length. Present day fiber prices vary over a wide range from $800 to $225 for crude fibers and $300 to $20.00 per ton for milled grades. For valuation purposes a careful study should be made of existing fiber prices and markets. EXAMINATION OF DEPOSITS In carrying out prospecting and examination of a deposit, considerable caution is required to get the necessary information in the form that will have the most value for the final determination. There are two main classes of asbestos fibers, chrysotile and the amphiboles, the chrysotile being, by far, the most important both in abundance and uses. This paper will stress mainly chrysotile deposits, however, the amphiboles have many important uses, especially amosite and crocidalite. Their valuation presents special problems as other factors may be involved, especially as they are not graded according to any well defined and adopted standard but usually according to the use for which they are being supplied. Most chrysotile deposits occur in two main types of rock, (I) mainly in basic igneous, such as dunite and peridotite, (2) to a lesser extent in sedimentary rocks, such as dolomite and limestone. All of these require a certain degree of metamorphism to be favorable to asbestos formation. Approximately 90 pct of the asbestos deposits are derived from serpentinization of dunite or peridotite, whereby the magnesiumsilicate olivine was altered to hydrous magnesium-silicate serpentine. Under certain favorable geological conditions, this serpentine takes a fibrous form having a definite crystal structure, probably due to molecular rearrangement, and is known as chrysotile. The fiber veins are usually ir-

Jan 1, 1947

By Timothy Fogarty, Gregory Poole, Roger Reeder, David Switz

This project involved the construction of a new pump station and intake structure at an existing water treatment facility. Although the project involved a significant amount of rock removal, the specifications said no blasting.

Jan 1, 2012

By G. R. Smith

Critical and strategic metals are often present in small quantities in low-grade domestic ores. When these ores are leached, the resulting solution usually contains the metals in very dilute quantities. Selective electrowinning from dilute electrolytes was investigated by the Bureau of Mines. A metal deposit containing 84 pct nickel was electrowon from the leach solution of a complex domestic ore bulk flotation concentrate originally containing approximately 2 wt-pct nickel. Key to achieving accelerated deposition rates, in the case of dilute solutions, is the rapid movement of the electrolyte through the electrowinning cell. Pure, synthetic nickel electrolytes were used to establish deposition parameters, and to optimize electrolyte velocity or mass transfer rates. Hydrodynamic and electrodeposition parameters for both the synthetic and leach electrolytes are presented and the experimental research described. Selective electrowinning appears to offer a viable alternative to physical separation methods to obtain separate metal "concentrates" from low-grade ores.

Jan 1, 1983