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By Enrique Monge

Para resolver la crisis de combustible por la que atraviesa el Perú, se requiere reemplazar gradualmente el petróleo de consumo nacional por carbón mineral de los yacimientos del Santa, Oyón o Huayday. En ese sentido, el presente texto señala el tratamiento adecuado para la explotación del carbón a través de conocer el comportamiento de los carbones en los procesos de lavado, pulverización, briquetaje combustión, coquificación y gasificación. Para efectuar dichos estudios se recomienda la creación de un Instituto de Investigación Experimental, financiado por el Estado y por la industria -petrolera y carbonera, que opere en forma independiente, resolviendo cada uno de los numerosos problemas que afectan el tratamiento de los carbones como la liberación y separación de granos; expansión de carbón; fusibilidad de cenizas; combustibilidad y reactividad; rendimiento de gases; temperaturas de combustión; coquificación y gasificación; presión y exceso de aire para combustión; plasticidad, aglutinación y aglomeración de carbón, impermeabilidad, coherencia y resistencia de briquetas; etc

Jul 1, 1959

By James R. Evans

Orange County, adjacent to the populous and industrialized Los Angeles area, is the fastest growing county in California and is second only to Los Angeles County in total population (figure 1). In addition to an equable climate and a burgeoning economy, there is room in Orange County for growth and expansion. Growth over the past decade has resulted in rapid development of industrial tracts, housing areas, and shopping and commercial centers, mostly in former agricultural areas. The value of new building in 1972 was a record amount-over I billion dollars (figure 2). Problems relating to the proper direction of growth are the concern of both government and the private sector. The intelligent and efficient use of areas to be developed requires planning for the conservation and protection of the County's natural beauty and for the orderly development of natural resources. The availability of sand and gravel, which is used in many phases of construction, will be a major controlling factor in the future of the County.

Jan 1, 1974

By A. I. A. Salama, M. W. Mikhail

"The existing methods of block diagram manipulation and vanishing variable for flowsheet simplification used in coal and mineral processing circuit evaluation and optimization cannot be easily implemented on digital computer.The signal flowgraph technique is proposed to represent and simplify determination of the relationship between intermediate or end variable and the feed in the flowsheet. Typical and existing circuits are used to demonstrate the application of the proposed technique which can easily be implemented on digital computers.IntroductionRecently there has been much interest in the analysis and optimization of coal and mineral processing circuits to assist in the pre diction of coal and mineral processing plant performance. The block diagram and the vanishing variable were introduced and utilized in the analysis of plant flowsheet. Although the block diagram approach is useful, it requires manual manipulation of the circuit block diagram which may present difficulties in the situation of complex circuits. Moreover, it may not be easy to implement on a digital computer.In this paper, the signal flowgraph technique is proposed to represent the circuit flowsheet and to simplify the determination of relationships between intermediate or end variables (fractional mass) and the feed for any coal and for any mineral processing circuit comprising size and density separators. These relationships are utilized in the analysis and/or optimization of the circuit. The proposed technique is illustrated by considering typical and existing circuits."

Jan 1, 1987

United Engineering Trustees, Inc James L Head, '55, E C Meagher, '56, Gail F Moul¬ton, '57 Advisory Committee to Real Estate Committee Cleveland Dodge, Herbert Hoover, Paul D Merica The Engineering Foundation W M Peirce, '56, A M Gaudin, '58 Research Procedure Committee A M Gaudin, March '54 Engineering Societies Library Board Frank T Sisco, '54, E M Wise, '56, James L Head, ex officio Engineering Societies Personnel Service Board of Directors E J Kennedy, Jr, E H Robie

Jan 1, 1954

By H. W. Gudenau, R. S. Chatty, W. Wenzel, M. Ponthenkandath

During several experimental programs conducted at the Institute of Ferrous Metallurgy, Technical University, Aachen, whisker formation was observed when iron ores were reduced at low as well as at high temperatures. Thus, in an attempt to find the reason for the volume change taking place during reduction, iron whisker growth was observed. Whisker growth appears to be one of the important reasons for the swelling of pellets. One set of experimental observations determined that when iron forms as needles rather than as a crust on the surface of oxide, the pellets became very porous. In related experiments, the beneficiation of finely disseminated iron ores, in which the metallic iron is separated from the gangue in granular or nodular form, was achieved by a reduction-concentration method. In this process, which is conducted at sufficiently high temperatures, oxide whisker growth, resulting from the formation of volatile suboxides and a gas transport mechanism, plays a vital role in the joint deposition of SiO, and iron from the vapor stage.

Jan 1, 1973

By M. Didyk

The final objective of a mine ventilation project is to find a way of supplying the working faces with the necessary quantity of air to dilute all the possible air contaminants to safe limits and to maintain the temperature, humidity and oxygen content within desirable limits. To accomplish the aforesaid, decisions have to be made at early stages of planning and design of a mining operation. That is, ventilation and mine planning are closely related and interdependent, and experience has proved that improvisation as related to mine environment is rarely optimal in ventilation engineering. Mine management should be concerned with two general aspects of ventilation problems. The first is related to the statuatory requirements which are usually the minimum standards that have to be maintained. During the last two decades, mining laws have become increasingly stringent and management of operating mines had to face the effects of these externalities. In some cases these required either a production rate reduction or additional mine development. The second aspect that management should not overlook is the technical and economical importance of mine ventilation on the overall mining cost. In coal mining it is necessary to move, on an average, five tons of air through the mine for each ton of coal produced. The power cost incurred is perhaps the single most important direct cost assigned to ventilation but it is not the only one. Other costs that should be considered include the supervisory labor cost, fan depreciation and maintenance, doors, stoppings and regulators construction cost and maintenance, the additional mine airways development and maintenance because of ventilation requirements. That is,

Jan 1, 1977

By T. H. Chuang, Y. Y. Shiue

"Rapid whisker growth was significantly alleviated in a Sn-58Bi alloy doped with 0.5 wt.% La. Experimental results showed that many thin, plate-form intermetallic phases appeared in the solder matrix. The absence of tin whiskers was correlated to the shape effect of RE-containing intermetallic plates. After reflowing, Cu6Sn5 intermetallic compounds appeared at the solder/pad interfaces of Sn-58Bi and Sn-58Bi- 0.5La packages with OSP pads, which grow linearly during the aging at 75 and 100? for various times ranging from 100 to 1000 h. In addition, the interfacial intermetallics layers in Sn-58Bi-0.5La solder joints were also observed thinner than those in undoped Sn-58Bi joints. However, RE-containing interfacial intermetallic compounds in Sn-58Bi-0.5La solder joints led to lower bonding strengths in both ball shear tests (0.4 mm/s) and high speed ball shear tests (2000 mm/s). All the reflowed and aged solder joints of both packages were ruptured through the solder balls indicating brittle characteristic INTRODUCTIONIt has been widely reported that solder alloys doped with rare earth (RE) elements reveal many beneficial effects, such as higher strength, lower melting point, improved wettability, and longer creep life (Wu et al., 2004; Ma et al., 2002; Chen et al., 2002). In addition, Dudek et al. reported that the alloying with 0.5 wt.% La in Sn-3.8Ag-0.7Cu solders resulted in an increase of rupture strain, up to 150% over undoped solders (Dudek et al., 2006). However, Chuang and Yen observed that a large amount of long, fiber-shaped tin whiskers were extruded out of the oxidized CeSn3 intermetallic clusters in the matrix of a Sn-3Ag-0.5Cu-0.5Ce solder air-stored at room temperature for several days (Chuang & Yen, 2006). Furthermore, many coarse hillocks appeared around the CeSn3 clusters in the RE-doped alloy after storage in an air furnace at 150? for several minutes. Chuang proposed a mechanism for the phenomenon of rapid whisker growth, which the predominate oxidation of CeSn3 intermetallics in Sn-3Ag-0.5Cu-0.5Ce solders induced compressive stress and extruded the tin atoms out of the specimen in the form of tin whiskers (Chuang, 2007). However, further investigation showed that Sn-9Zn-0.5Ce solders, after long term exposure at room temperature and 150?, were immune to the whisker growth; the immunity was attributed to the refining of the CeSn3 intermetallic phase in the alloy (Chuang & Lin, 2008). The inhibition of tin whiskers through the refining of rare earth containing intermetallics was further observed in Sn-3Ag- 0.5Cu-0.5Ce solders doped with 0.5 wt. Zn (Chuang & Lin, 2009). In addition to the size effect, the thin plate shape of intermetallic compounds was also shown in this study to inhibit the whisker growth on the surface of Sn-58Bi-0.5La solders."

Jan 1, 2012

By Bigdy D. N

The paper describes a system for providing mine management with a continuous indication of the effectivness of longwall coalface powered supports in controlling roof-to-floor convergence. The system comprises on-face instrumentation monitoring convergence and support leg circuit pressures, a means of transmitting the output of that instrumentation to the surface for collection, and software which presents both a condensed analysis for rapid review of the current state, and extended analyses from which remedial action can be recommended if a problem is identified. The results of a field trial are presented showing that meaningful results can be obtained.

Jan 1, 1988

In 1993, the United States' economy grew at a rate of about 3%. The Gross Domestic Product rose to $6.4 trillion. With more than 258 million people - 599,000 in mining including petroleum - the United States has more than 100 million dwelling units and more than 190 million licensed motor vehicles. New private housing starts rose 7% to 1.3 million units, new car production fell 3% to 5.5 million units and truck and bus production rose 21 % to 4.9 million units. The rate of inflation was under 3% and the prime rate of interest 6%. The Producer Price Index (1982 = 100) was unchanged from 1992 for fuels and re¬lated products and power at 80 and met¬als and metal products at 119, while chemicals and allied products rose 2% to 128 and non-metallic mineral prod¬ucts rose 2% to 120. The merchandise trade deficit rose 27% to $116 billion.

Jan 1, 1994

By Walter L. Maxson, Fred C. Bond

THIS paper is a continuation of two earlier papers, l, 2 and presents new data on the grindability of various ores and other materials-the results of several years of intermittent research work on the nature of grinding and interpretation of test results. It is divided into five parts: 1. The tabulated results of several hundred grindability tests on a wide variety of ores. 2. A method of correcting screen analyses and calculating from them the surface and other properties. 3. A description of a new method of measuring the "surface energy" of an ore by pendulum impact tests. 4. Test results. 5. A general discussion of the test results and their application to grinding problems. 1. GRINDABILITY OF VARIOUS ORES This part is a continuation of the paper listed as reference No. 1. The method of testing is described in detail in that paper. The sample to be tested is crushed to all through 6 mesh in rolls set at x6-in. opening in closed circuit with a screen. Of this sample 700 C.C. is ground dry in a laboratory ball mill under constant conditions of mill speed and ball charge in closed circuit with a screen of the desired size at 250 per cent circulating load. The mill is cylindrical, 12 by 12 in., and rotates at 70 r.p.m. It contains a charge of 285 iron balls weighing 20,125 grams and ranging from 1 ½ to ¾ in. in diameter. Each test is continued for a sufficient number of periods to establish equilibrium at 250 per cent circulating load, or until the composition of the circulating load is constant for successive periods. Tests are conducted at the mesh size to which the ore is to be ground in practice, and the results are expressed as the net production in grams of screen undersize per revolution of the mill. This is designated as the

Jan 1, 1938

By Eiki Ono, Atsushi Yamatodani, Shigeru Sunagawa, Yasushi Takasaki, Atsushi Shibayama, Yasunori Higuchi

"During metallurgical processing of non-ferrous metals, smelting residue (inc. smelter slag, flue gas and so on) is inevitably generated as secondary product.In this research, some experimental feasibilities were investigated to recover/remove Cu and As from the residue. Primarily, the removal of As and volatilized materials from the residue was examined by pyrometallurgical treatment (dry-process). In the second stage after treating the residue with a dry-process, leaching and solvent extraction as hydrometallurgical treatments (wet-process) were also investigated by using H2SO4 solution as a two stage leaching treatment, to dissolve various metals from the leach residue. Then, solvent extraction was examined by using LIX-84I as an extractant to recover and separate Cu from impurities from the final (2nd) leached solution. For the leaching stages, the removal of 90 % As and the leaching rate of 85 % Cu could be achieved by 0.25 mol/l and 1.0 mol/l H2SO4 solution, respectively. On the other hand, the extraction of over 90 % Cu and stripping was carried out by solvent extraction. 1. IntroductionIn metallurgical process for non-ferrous metals, smelting residue (inc. smelter slag, flue gas and so on) is inevitably generated as secondary product, i.e., flue dust, slug and so on. The smelting residue includes some useful metals and undesired toxic materials; Cu, Pb, Ca and As, etc.In Japan there is one undisclosed place stockpiled with 10,000 ton of smelting residue from abandoned smelters about 25 years ago. Therefore it is necessary to reduce the residual amount for space and environmental protection including water treatment by separating and removing toxic materials."

Jan 1, 2008

EXECUTIVE COMMITTEES OF LOCAL SECTIONS New York, L. W. FRANCIS, Chairman, WILLARD S. MORSE, Vice-Chairman. THOMAS T. READ, Secretary, Woolworth Bldg., New York, N. Y. P. A. MOSMAN, Treasurer. LOUIS D. HUNTOON. WILLIAM A. POMEROY. Boston HENRY L. SMYTH, Chairman. ALFRED C. LANE, Vice-Chairman. AUGUSTUS H. EUSTIS, Secretary-Treasurer, 131 State St., Boston, Mass. ROBERT H. RICHARDS, ALBERT SAUVEUR. Columbia FRANK A. ROSS Chairman. RUSH J: WHITE, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. FREDERIC KEFFER FRANCIS A. THOMSON,

Jan 2, 1915

By P. C. Chaubal

The overall kinetics of oxidation of single partic1es of chalcopyrite have been studied for temperatures up to 1273 K. The experiments were conducted in a stationary bed reactor using a non-isothermal technique. Any mass and heat transfer effects on the kinetics of oxidation were eliminated by using a high-enough gas flowrate. Up to temperatures of 873 K, pore-bl1ocking kinetics were applicable, whereas above 873 K, power-law kinetics gave a satisfactory fit of the data. The activation energy was 215 kJ/mol below 754 Kand 23.7 kJ/mol above 1,060 K. Predominance area diagrams were constructed at various temperatures and used in conjunction with X-ray analyses of partially oxidized samples to determine the intermediate phases formed during the reaction. The analysi1s also provides a justification for the kinetic models used. The results indicate that the reaction rate is first order with respect to oxygen concentration and inversely proportional to the square of the particle size throughout the ranges of temperature studied.

Jan 1, 1985

A. W. TRACY' AND D. H. THOMPSON (presented in written form).-Messrs. Ed¬munds, Anderson and Waring are to be commended for their excellent work in so painstakingly reducing to constants, the variables believed to be associated with these types of stress corrosion. An ammonia stress-cracking apparatus similar in many respects to the one described has been assembled. Certain aspects of its construction may be of interest. Tensile loading of the specimens, which are usually Y8-in. diameter wires, is accomplished by springs acting in compression in compact, portable, tubular assemblies weighing less than 10 lb. The lower end of each assembly contains the test specimen and is passed into the test chamber for exposure to the moist ammoniacal atmosphere. There is considerable convenience in being able to load the specimens in a portable unit, which may be warmed to prevent condensation, and then thrust instantaneously into the test chamber. Spring loading obviates the use of weights, but it has the disadvantage of allowing some relaxation of the load if the specimen elongates during corrosion. The maximum loss in load found so far was 20 per cent. The air supplied to the test chamber is humidified by passing it through thermo¬statically controlled water. The air is dispersed into fine bubbles by being forced through a porous ceramic filter at the bottom of a tank containing about 10 liters of water. The temperature of the water is controlled independently of the tempera¬ture of the test chamber. Thus, with the

Jan 1, 1945

By George F. Comstock

IT has been reported recently1 that the hardenability and toughness of forging steels may be improved appreciably by the use of complex deoxidizers containing titanium, aluminum, and vanadium. In the light of these results, an investigation of similar deoxidizers containing various hardening and grain-refining elements was proposed. These deoxidizers included three manganese-silicon-aluminum-titanium al- [ ] loys with and without boron and calcium, three titanium-aluminum ferroalloys with vanadium, molybdenum and zirconium, respectively, an aluminum-zirconium ferro-alloy, and plain ferroboron. Their approximate compositions are given in Table I, and the results obtained so far in the investigation of their effects on steel are presented in the later parts of this paper. METHOD OF USING DEOXIDIZERS The deoxidizers listed in Table I were used in three series of 0.40 per cent carbon steels, which were melted in a small basic-lined induction furnace and cast in the form of I7-lb. ingots about 2.75 in. square. The basic charge for each heat was 10 lb. Armco iron and 6 lb. of clean low-carbon sheet-steel scrap. When melted, this charge was deoxidized with 15 grams of ferrosilicon, then about 500 grams of pig iron was added to give the desired carbon content. After the pig iron was dissolved, nickel [ ] shot and high-carbon ferrochromium were added if required, and additions of 80 per cent high-carbon ferromanganese and 50 per cent ferrosilicon were made to provide the proper amounts of those elements. Aluminum was added to every heat 2 min. after the silicon, for grain-size control and preliminary deoxidation. One minute later the special deoxidizer was added to the clean bare surface of the molten steel, and 2 min. afterward the steel was poured into the ingot mold, using a hot-top and pipe-preventing compound after pouring to decrease the depth of the shrinkage cavity. The special deoxidizers were used mostly in the form of about ½ to ¾ -in. lumps,

Jan 1, 1942

By M. Saghaeian, R. Hejazi, H. Abedini

Vertical ring and Pulsating Wet High Intensity Magnetic Separator (VP-WHIMS) is widely used for week magnetic mineral beneficiation or ferrous impurity removal from non-metallic minerals. Because of the complexity of this machine, mathematical modelling of its process is complicated and time consuming. In this paper, artificial neural network (ANN) and response surface methodology (RSM) were applied to evaluate the VP-WHIMS performance and optimize its main operating parameters in beneficiating of the Chadormalu hematite sample. The operational parameters of this magnetic separator are considered as: magnetic field intensity (2500-8500 gauss), pulsating frequency (20-100 %max), ring rotation speed (0.6-4.6 r/min) and slurry concentration (15-35 w/w %). Concentrate grade and recoveries (weight and Fe) are monitored as responses. Centre composite design (CCD) was used for experimental study. Four process variables were set using small CCD. Eight star points (a=±1), eight axial points (a=±2) and five replicates at the centre point (a=0) were chosen as experimental points. In ANN system, the best network topology was obtained as (4-5-3). The weights connection and biases were obtained using batch back propagation (BBP) method for 21 experimental data points. The results indicate that ANN

Jan 1, 2014

By James M. Barker, George S. Austin

Stone, one of the oldest building materials, today remains a well-established material throughout the construction industry. The use of natural stone is much less prevalent now than in the past. It is still widely considered to be the most aesthetically pleasing, prestigious, and durable building material. New and re-opened quarries are coming onstream to meet increased demand related to new building technology and increased residential use of stone. CLASSIFICATION No classification can completely eliminate overlap between dimension stone, aggregate, and decorative stone because most stone is multi-purpose. Many used for decorative purposes are not produced specifically for that end use. Rock otherwise considered waste in dimension stone or aggregate quarries can be decorative stone coproducts (Fig. 1). Many uses require a compromise between decorative and structural qualities (Bowles, 1992, written commu¬nication). Shipley (1945) used decorative stone interchangeably with or¬namental stone. Gary et al. (1972) defined decorative stone as that used for architectural decoration, such as mantels, columns, and store fronts, but added that it is sometimes set with silver or gold in jewelry as curio stones. Bates and Jackson (1987) also restricted decorative stone to that used for architectural decoration. Meanings of otherwise identical terms used in the stone industry differ be¬tween geologists, engineers, and quarriers. They often carry a much broader meaning for quarriers and engineers compared to their very specific use by geologists (Makens et al., 1972). Decorative stone, including ornamental stone, is more broadly defined by geologists as any stone used primarily for its color, texture, and general appearance. It is not used primarily for its strength or durability, such as construction stone, or in specific sizes, such as dimension stone. The decorative stone industry uses a much wider range of stone types compared to stone that is dimensioned. Decorative stone usually serves some structural pur¬pose, but is not load-bearing to any great extent. Weak or costly stones serve in decorative, not structural, applications. STATISTICS AND END USES Decorative and dimension stone data are difficult to separate because the US Bureau of Mines keeps statistics only on dimension stone and crushed stone. The value of domestic dimension stone production in 1990, which includes some decorative stone, was about $210 million compared to imports of about $524 million and exports of about $35 million. Production was 1 080 t of which at least one-third was for decorative uses (Taylor, 1992). The principal uses are rough blocks in building construction (23%) and monu¬ments (18%); the remainder is used as ashlar (18%), curbing (12%), and miscellaneous (29%). Major rock types are granite (50%), limestone (30%), sandstone (10%), slate (3%), marble (2%), and other (5%) (Harben, 1990). Crushed stone valued at $5.6 billion was produced in the United States in 1990 by 1700 companies operating 3400 active quarries in 48 states (Tepordei, 1991). About 52% is used in con¬struction, 9% in cement and lime manufacturing, 2% in agricul¬ture, 2% in industrial uses, and 35% for unspecified uses including decorative aggregate. Limestone and dolomite comprise about 71%, granite 14%, and traprock 8% of the stone crushed in the United States. The remaining 7% are, in descending quantity, sandstone, quartzite, miscellaneous rock, marble, shell, calcareous marl, volcanic cinder and scoria, and slate. The basic types of decorative stone are: rough stone, aggregate, cut or dressed stone, and manmade stone [(Table 1)]. Rough Stone Rough stone is used as it is found in nature with very limited processing such as minor hand shaping, edge fitting, and size or quality sorting (Perath, 1992, written communication). This stone type is often marketed locally in relatively small tonnages and includes fieldstone and flagstone. The primary end uses of rough stone are landscaping, edging, paving, or large individual stone landscape or interior accents [(Fig. 2)]. Fieldstone: Fieldstone is picked up or pried out of the ground (gleaned) without extensive quarrying and includes garden or large landscaping boulders (Austin et al., 1990, Hansen, 1969). Boulders and cobbles may be split or roughly trimmed for use in rubble walls and veneers, both interior and exterior. Popular fieldstone rock types include sandstone, basalt, limestone, gneiss, schist, quartzite, and granite, but many others are suitable. Much fieldstone is col¬lected by individuals or small companies because the industry is labor intensive and markets are small. The stone may be sold locally in small quantities from the back of vehicles (Austin et al., 1990). Fieldstone includes many rock types, sizes, and shapes with the only common denominator that it must be set by hand and be durable (Power, 1992, written communication). Moss Rock. Moss rock is fieldstone partially covered by algae, mosses, lichens, and fungi that give the rock an aged and variegated patina (Austin et al., 1990). The plants are supported by moisture and nutrients in the stone. Moss rock is used for landscaping, walls, and fireplaces. Although almost any durable rock can be a moss rock, most are slabby or rounded sandstone and limestone (Fig. 3). Flagstone: Flagstone or flagging consist of thin irregular slabs used for paving, walkways, and wall veneers. Random-shaped flagging is produced widely in the United States. Suitable stone

Jan 1, 1994

By J. B. Clemmer, F. D. DeVaney, H. A. Doerner

PRODUCTION of magnesium metal in the United States during the past decade has increased from less than 6oo,ooo lb. in 1928 to more than 4,800,000 lb. in 1938.1 The growing industry has stimulated interest in methods of production and in sources of raw material. All of the present domestic production is from brines. However, the availability of large tonnages of magnesite in the state of Washington, together with the possibility of cheap power, have created interest in the utilization of magnesite for the production of magnesium metal as well as for other purposes. Magnesite, the carbonate of magnesium (MgCO3), usually is associated with limestone (CaCO3) and dolomite (MgCO3CaCO3). It occurs in crystalline and microcrystalline (sometimes termed amorphous) forms.2 The more common crystalline mineral is found in various shades of white, gray, yellow and brown, the colors being due to impurities, chiefly iron. Magnesite has a hardness of 3.5 to 4.5 and a specific gravity of 3.0 to 3.1. It forms rhombohedral crystals in the hexagonal system, having a vitreous, pearly luster. The quarries and mines of the Northwest Magnesite Co. near Chewelah, Wash., are large producers of magnesite for refractories. The deposits are extensive, some veins being hundreds of feet wide. The boundaries of the veins are indefinite, and the magnesite is interfingered with dolomite. Calcite, talc, serpentine, quartz and shale are disseminated through the deposits. The quality of the ore cannot be determined by appearance or by simple tests; chemical analysis is required. These features make it difficult to determine the boundaries or total quantity of workable ore.3 Only the higher-grade ores are mined, and a considerable proportion of the magnesite content is discarded by hand-sorting and log-washing methods. After calcining, the sorted product meets the specifications for usual refractory material, as it contains approximately 81 per cent MgO, 7 per cent Si02, 6 per cent CaO and 6 per cent Fe203 + A1203. A sample of the reject material had the following analysis after calcining: 65.4 per cent MgO, 6.3 CaO, 21.1 Si02 and 6.5 R203. The percentage reported as R203 includes compounds whose chlorides are acid-soluble but give precipitates in ammoniacal solution that are ignited and weighed. The more common constituents are Fe203, A1203 and Ti02. The sorted magnesite product is not the best grade, even for refractory purposes, and leaves much to be desired for a reduction process. The rejected material contains a large proportion of magnesite. It is apparent that an effective concentration method would yield a higher recovery and a better product. In general, the refractory grade is not suitably pure for other uses. Recent developments in the production of

Jan 1, 1940

By Marcelo Gagó M.

El presente trabajo señala la factiblidad del método de explotación "Trackless" en la mina Huarón, Pasco a través del sistema de conjunto semi-mecanizado, donde la formación de la unidad de explotación requiere la incorporación de vetas estrechas en arranque selectivo a las vetas anchas. En este sentido, se evalúa la aplicación de vetas con potencias entre 0.40 a 2.80 metros cercanas las unas a las otras, cuya interceptación se sirva de eje, al tiempo que se aproveche de una sola unidad de limpieza.

Oct 14, 1980

By M. J. Ferrante

Relative enthalpies of cuprous iodide (CuI) were measured at the Bureau of Mines to provide thermodynamic data for the advancement of min-eral technology. Enthalpy measurements between 298.15 and 1,396.3 K were made with a copper-block drop calorimeter. The temperatures of transition were measured by differential scanning calorimetry (DSC). Reversible transitions were determined at 643 K with a standard enthalpy of transition [(6Htr)] = 0.74 kca1/mol, at 679 K with a [6Htr = 0.65 kca1/mo1, and at 868 K] with a standard enthalpy of fusion [(6H~) = 1.895 kca1/mol.] Tabulated values are listed at selected temperature increments from 298.15 to 1,600 K for the standard relative enthalpy (HO -H298), heat capacity (CpO), entropy (SO), and Gibbs energy function [-(Go -H298)!T]. The enthalpy data are also given in the form of equations and combined with thermodynamic data from other investigations to derive values of standard entha1pies of formation [(~HfO)], Gibbs energies of formation [(6GfO)], and logarithms of the equilibrium constants of formation (log Kf).

Jan 1, 1987