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By Janet Briggs, Michael Vertes, J. F. Shirley, R. E. Cutherbertson, Alexander Sutulov, J. D. Vincent

Molybdenum, the 42nd element in the periodic table, is now a very important metal in industry of the United States and the world. Chemically, it is a very complex element having valences of 0, +2, +3, +4, +5, and +6, and can exist as a mixture of these valences in many compounds. It was discovered and separated by Scheele in 1778. At the present time, molybdenite is the only important commercial source of molybdenum. Molybdenum occurs in some 12-14 different recognized minerals, but practically all of the production is molybde¬nite. As late as 1915, it was considered a rare metal. Germany made extensive use of it during the first world war, which resulted in the establishment of a molybdenum industry in the United States at Cli¬max, Colo., in 1917. It was not until the mid-1920s when its introduc¬tion to steelmaking developed for the US automobile industry that the metal gained important acceptance. The first notable example was the Willis-Saint Claire automobile introduced in 1921 by C. Harold Willis, formerly chief metallurgist for Ford Motor Co. Molybdenum has also been produced in the US from wulfenite (PbMoO4) from Arizona and Nevada, and a small amount of molyb¬denite was produced up to the early 1970s as a coproduct from two molybdenum-bismuth mines in Quebec, Canada. The first byproduct production of molybdenite from a copper con¬centrating operation was achieved at Cananea, Sonora, Mexico, and was followed shortly by the Utah division of Kennecott Copper Co. in the mid-1930s. This section of the Handbook is divided into four main subdivi¬sions: Chapter 2, which deals with the concentration and recovery of molybdenite from primary molybdenum ores; Chapter 3, which deals with the recovery and separation of molybdenite as a byproduct from copper production; Chapter 4, which deals with the conversion practices employed for converting molybdenite to the oxide or metal form; and Chapter 5, which covers the uses of molybdenum in steel¬making, chemicals, pigments, lubrication, catalysts, etc. The Free World molybdenum production, for the past eight years from all sources, is shown in Table 1. 2. Primary Molybdenite Ores General In 1978 there were four primary molybdenite recovery plants in operation: Climax, Endako, Quests, and Henderson. For over half a century the Climax mine has been by far the largest and most important source of molybdenum in the world. During the early 1970s a few primary molybdenite mines in British Columbia were shut down due to adverse economical conditions. The largest of these was British Columbia Molybdenum, formerly owned by Kennecott Copper Corp. The Climax plant and operations are described in detail and the opera¬tions of the other plants are summarized following a general discussion of recovering molybdenite from primarily molybdenite ores. Recovery of molybdenite as a byproduct will be taken up in Chapter 3. Geology Molybdenite production from mines in which it is the sole or preponderantly important mineral is confined to ore bodies in granites or igneous-type rocks or pegmatite dikes. More than one state of mineralization is sometimes present as at Climax, York, Hardy, and Questa. In the case of Climax, important byproduct recovery of tung¬sten, tin, pyrite, and monazite is also attained. The molybdenite is commonly disseminated very finely in the siliceous granitic gangue but does occur in stringers and blebs in silicified mineral solution channels. Treatment of Primary Molybdenum Ores All primary molybdenum ores are low in molybdenite, the content ranging from less than 0.20% MoS2 to a high of about 0.40% MoS2. A high resistance to grinding is a common ore characteristic combined with a habit of very fine dissemination of molybdenite in the siliceous portion of the ore. Because of low MoS2 content, high hardness, and fine dissemination of molybdenite in primary ores, it has been necessary to develop a special mill treatment which yields an accepta¬ble recovery at a reasonably low milling cost. Essentially, the treatment consists of intensive rougher flotation at a relatively coarse grind with production of a low grade rougher froth containing a substantial percentage of the molybdenite in the form of low grade middling particles, followed with multistage regrinding to liberate the locked molybdenite and several stages of flotation cleaning to produce a finished grade concentrate. Rougher flotation on pulp ground to ap¬proximately 35 mesh is common practice, even if complete liberation of molybdenite from siliceous gangue may require regrinding to 200 mesh. The flotation of middling particles with a very low content of molybdenite in the rougher flotation step has been made possible by the application of a combination of reagents first developed at the Climax mill and used with some modification in the treatment of all primary molybdenum ores. The reagents commonly employed and their functions in flotation are:

Jan 1, 1985

Tokyo Metropolitan Government designs the stormwater storage plans in underground, as a measure of flood control in completed urban district and improvement of combined sewarage system. This time, introducing those plans, we report about IKEJIRI and SIN-KOMAZAWA STORAGE TRUNK LINEs design and construction. They are located in Meguro river basin of the Morigasaki drainage area. Both storage trunk lines have capacity to store 15O,000m3 of stormwater. They are in use for countermeasure of flood till Meguro river's strengthening (intensity 50 mm/h) is ended. And after the strengthening, they will be in use for improvement of river water quality, through the storage of combined sewage and first runoff, which, otherwise overflows weirs and flows to river in a rainy day. These storage trunk line's full length is about 5700m. Boring diameter 66140 mm (f = 2672m) and 47800 mm (I = 2866m) of these tunnels are constructed by Mechanical Shield tunnelling method. And boring diameter 3600 mm x 4000 mm (R = 180m) is constructed by NATM tunnelling method. We began works in 1983, and have a mind to complete in 1987.

Jan 1, 1987

By R. L. Garrett

The quality of mineral additives used 1n a drilling fluid (mud) can dramatically affect the fluid's properties and the overall cost of drilling an oil or gas well. The principally used minerals are bentonite, barite, barite/hematite blends and hematite alone. The high specific gravity minerals, barite and hematite, are used to increase drilling fluid density. Bentonite clay is used to increase drilling fluid viscosity, gel strength and to provide a low permeability filter cake. A multi-million dollar investment in a well and the safety of the personnel on the drilling rig can depend on how effectively these mud additives perform with other constituents in the mud. This paper points out effects caused by small amounts of certain carbonate and sulfide mineral impurities in barite or hematite and how polymeric extender additives in bentonites contribute to unpredictable behavior of a mud. Effects like these are the reason why oil companies who use these materials sometimes set their own quality standards beyond those already specified in API Spec. 13A. Also discussed in this paper are the current standardization activities in API Committee 13 on these minerals.

Jan 1, 1986

By Fawcett M

Pine Creek Goldfields Limited (PCG) is rehabilitating the Enterprise Pit to an aquatic habitat and potential water resource. This paper discusses the development and implementation of that plan. Pine Creek Goldfields Ltd's Enterprise Mine is located approximately 230 km south of Darwin. Open cut mining of the orebody commenced in 1985 and continued for eight years with 14 million m3 of ore and overburden extracted. Geochemical testing of exposed rock types in the pit has demonstrated a propensity to produce acid, and dissolved metals. A plan of management has been developed and implemented to minimise the risk of acid formation and improve the overall water quality in the final void. In developing the plan prime consideration was given to reducing the potential for pit water to impact upon the regional groundwater. An interception system was constructed on Pine Creek to divert approximately 9 km2 of upper catchment into the northern end of the Pit. Construction of the diversion system was completed in December 1993 and a comprehensive surface and groundwater monitoring program initiated. The monitoring program and associated studies are also discussed.

Jan 1, 1994

By Harold L. Gibson, David H. Watkinson

"Volcanogenic massive sulphide deposits of the Noranda Camp cur throughout the Noranda Shield Volcano but are concentrated and along the margins of the Noranda Cauldron. The deposits are realized along synvolcanic faults that also accommodated subsince and controlled the location of eruptive centres. Deposits within e 3 000 m thick Mine Sequence formed during a period of active volcanism and subsidence coinciding with the onset of two cauldron subsidence cycles. The Noranda Cauldron was a restricted site of 10malously high heat flow and structural permeability that favoured e development of a high-temperature hydrothermal system. Metals may have been derived from leaching of aquifer rocks by convecting a water or directly from a shallow underlying magma chamber, now presented by the Plavrian Pluton, that was at its highest position !thin the crust during cauldron subsidence. The deposits formed rough a combination of sulphide precipitation from exhaled fluid td replacement at and below the seafloor in a manner analogous to ose on the modern seafloor.RESUMESi les dépôts de sulfures massifs volcano gènes du camp minier de ~uyn-Noranda sont présents dans les différentes parties du volcanluclier de Noranda, ils se trouvent concentres toutefois, en plus ·and nombre, sur le pourtour de la caldeira (cauldron) de Noranda. ~s dépôts sont localises le long des failles synvolcaniques qui ont cilite la subsidence et contrôle la position des centres d’éruption.~dépôts situes dans la séquence des mines (3 000 m d’épaisseur) sont formes durant un épisode d' activité volcanique et de subsiden qui coïncide avec l' amorce de deux cycles d' affaissement de la rldera (cauldron) de Noranda. Celle-ci Jut le site exclusif d’unflux : chaleur anormalement élevé et d’une perméabilité d’origine cucturale qui ont favorise le développement d’un système hydrothermal a haute température. Les métaux proviennent soit directement d’une chambre magmatique situee afaible profondeur, so it d’un lessivage des roches de l’aquifère par l’eau de mer circulant par convection. Cette chambre magmatique, représentée maintenant par le pluton de Flavrian, se trouvait à son niveau le plus élevé dans la croute au moment de l’affaissement de la caldeira (cauldron). Les dépôts se sont constitués par un mecanisme combinant remplacement et précipitation de sulfures à partir des fluides exhalatifs, au niveau ou au-dessous du plancher océanique, de la même manière que se forment de nos jours, les dépôts de sulfures massifs au fond des océans."

Jan 1, 1990

By F. G. BREYER

ZINC metallurgists continue to follow with keen interest reports of successful results from the continuous retort plants at Palmerton, Pa., and Meadowbrook. W. Va. The new process had already demonstrated its ability to reduce the lead content of the metal and to effect savings in labor and fuel. The past year has shown that the retorts themselves can he built to last long enough so that the retort cost per ton of metal is lower than in past practice with small horizontal re- torts. A number of the latest type of retorts are reported to have been in continuous operation for over 18 months without a failure and are said to be still in good condition. This seems a complete answer to the last question which remained before continuous zinc smelting could he pronounced commercially practicable.

Jan 1, 1932

By Qiang Ji, Richard L. Sanford

A laboratory-scale microcomputer-based autonomous excavation system has been developed that moves a pile of fragmented rock to a designated location using a shovel attachment on a robot arm. Navigation and excavation sub- systems interactively direct a robot excavator to move the shovel to the rock pile, intelligently load its bucket using a video camera, and dump the rocks to a designated area. Although research was conducted on a laboratory scale model, the system can serve as the basis for further work on a full-scale, robust excavation system.

Jan 1, 1993

By James R. Evans

Forecasting demand is an art as well as a science, and much personal judgment is required. National forecasts made for sand and gravel, crushed stone, and/or aggregate may be misleading or unhelpful locally. This is because of significant variation in demand within different geographic and/or political areas in the US, and/or the use of an inadequate data base and forecasting methodology. The best forecasts may be made for local or regional market areas, irrespective of geographic or political boundaries, provided a proper data base is available.1 The Bureau of Mines compiles detailed statistics on commodities sold or used in the construction industries and, therefore, is in an advantageous position to make national aggregate demand forecasts. Definitions of some terms used in this presentation are necessary before proceeding.

Jan 1, 1980

By David B. Reger

The value of carbon ratios in determining the boundaries of possible oil deposits appears to have passed the hypothetical stage. The theory that the ratio of fixed carbon in pure coals is an invariable index of incipient metamorphism in both surface and underground rocks and that it may be applied in defining the limits of petroleum, advanced by David White,' has been received with keen interest by many petroleum geologists. Detailed isocarb maps have been prepared of the Pennsylvanian area of North Texas and Eastern Oklahoma by M. L. Fuller.² A similar map of the coal-bearing area of West Virginia is given here. An isocarb3 is a line showing an equal fixed-carbon percentage, pure coal basis; the term has been proposed by David White to supersede a less expressive nomenclature. The term carbon ratio is applied to the pereentage of carbon in pure coal after water and ash have been eliminated. As a comparatively small number of analyses have been made on this basis, it is usually necessary to compute the ratio by dividing the fixed carbon of the proximate analysis by the sum of the fixed carbon and volatile matter of the same analysis. Many thousands of proximate analyses have been made by the West Virginia Geological Survey, covering nearly every county in which coal is found. Numerous others have been made by the U. S. Geological Survey and the U. S. Bureau of Mines, but as uniformity of results is best secured by adhering to one set of analyses, the tests of the West Virginia Survey have been cxclusively used.

Jan 1, 1921

By David C. Scott

Between 1990 and 1991, the Bureau of Mines studied the mineral resources of the Kaibab National Forest to appraise the resources present and to determine the types of deposits, and their location. The study included a comprehensive literature search and a limited amount of field investigation of minerals and mining activity in and near the Forest. Small amounts of copper with lesser amounts of gold and silver have been produced from limestone-hosted, strata-bound deposits in the North Kaibab and Tusayan Ranger Districts. In addition to these small metallic deposits, volcanic cinders, pumice, flagstone, and sand and gravel have been quarried in the Chalendar and Williams Ranger Districts. At least ten uranium-mineralized breccia pipes have been identified in the Tusayan Ranger District, One of these, the Canyon pipe, contains a high-grade uranium ore body with associated silver, copper, lead, vanadium, and zinc. The mine permit for the Canyon pipe has been approved and the mine shaft head frame erected.

Jan 1, 1992

By Luis Carrera Naranjo

El presente texto señala la topografía, geología regional, estratigrafía, fisiografía, caracteres morfológicos, mineralógicos y genéticos, y la clasificación según su proceso de formación del yacimiento de la región Morococha. La topografía de esta región es variada y rica en cuanto formaciones geológicas se refiere, dado sus orígenes y edades respectivas. Su estratigrafía comprende una columna geológica, la cual está compuesta por rocas sedimentarias, y extrusivas que van desde el periodo Cuaternario hasta el Terciario. Las formaciones encontradas en la región son las filitas excelsior, volcánicas Catalina, formación Mitu, calizas Potosí, formación Santo Toribio-Buena Ventura, formación Machay, las capars rojas de Casapalca, la diorita de Anticona y monzonita cuarcífera de Morococha. Asimismo tiene dos sistemas de fallas: longitudinal y transversal. Las especies metalíferas de mayor abundancia son: la pirita, tenantita, tetrahedrita, chalcopirita, enargíta, blenda, magnetíta y galena. Mientras que las de menor abundancia son: estefanita, especularita, phrotita, marcasita y muy raramente: aíkenita; burnonita, cubanita, jamesonita, luzonita y molibdenita. Finalmente, entre las características estructurales de depósito tenemos: las vetas y los mantos, considerando entre los mantos algunos subtipos o variedades estructurales. También existe una tercera clase de estructura de depósitos minerales, que son lo que están constítuídos por varios depósitos agrupados en forma localizada y se conocen como el "0re -Clusters" o "Archipiélago".

Jul 20, 1960

By T. P. Papazoglou, N. A. D. Parlee, W. C. Phelps

HE high vapor pressures of metals such as lead, calcium, lithium, bismuth, and magnesium at steel-making temperatures present experimental problems which have thus far rendered it almost impossible to obtain really reliable data for their solubilities in liquid iron. Many investigators have attempted to equilibrate liquid iron in the same crucible with the undissolved liquid phase of such volatile metals. The published results,l-6 although useful, are often questionable on the grounds of not being obtained under true equilibrium conditions. Such information is not always of practical value in any case since the equilibrium vapor pressure is often several atmospheres and steel is not currently made at these pressures. Solubility measurements at lower partial pressures (< 1 atm) appeared to be more practical and easier to make. These data could be used to calculate solubilities at other pressures where Henry&apos;s Law is obeyed, and to estimate solubilities under other conditions of temperature and pressure with useful accuracy. This note outlines the development of a general technique for the measurement of solubilities in systems of this kind. The method involves equilibration of the high-boiling metal at known temperatures with the vapors of a low-boiling metal at known partial pressures. Analyses of quenched samples provide vapor pressure-solubility data and make calculations of alloy thermodynamics possible. The principle involved is similar to the closed-system diffusion-transport method which is difficult to apply with most high-melting liquid metals like iron, due to closure problems. A two-zone horizontal (molybdenum wire element) tube furnace, Fig. 1, provides two constant-temperature zones in a reaction tuve (3/4 in. ID by 1 in. OD by 36 in.). A high-boiling metal sample, 9, introduced in the higher-temperature zone, is maintained at temperature T1, and a volatile metal sample, 7, in the lower-temperature zone, is held at T2. A stream of argon with 10 pct hydrogen is passed via flowmeters, 1, and mixing-drying towers, 2 and 3. through the reaction tube at a favorable flowrate and acts as a carrier gas which entrains vapor from the volatile liquid metal at a specific constant partial pressure. The gas mixture passes through a system of constrictions, 6 and 8, to the higher-temperature zone, establishes intimate contact with the high-boiling liquid sample, 9, and exits through a small condenser tube. The entire system is at (nearly) atmospheric pressure and the volume of carrier gas passed is measured with a wet gas meter. When the high-boiling sample attains equilibrium with the vapor phase, both samples are removed and quenched. Analysis of the high-boiling sample for solute content reveals its solubility for the low-boiling metal at a vapor pressure calculated from carrier-gas volume and either a) weight loss of volatile metal or 6) weight gain of high-boiling sample plus condenser (which collects the undissolved vapors). To test the capabilities of the method, liquid silver at 1403&apos;C was equilibrated with lead vapor at various partial pressures. The relatively simple Pb-Ag system was particularly suitable for uncovering experimental problems and providing the first step toward investigations with more volatile metals and more difficult combinations.

Jan 1, 1965

By D. G. Klaren, E. F. de Boer

Self-cleaning fluidized bed heat exchangers have demonstrated unparalleled performance internationally for the implementation of indirect heat transfer in severely fouling fluid environments. The ingenious configuration of recirculated cleaning particles through the tubes of vertical shell and tube heat exchangers provides the ability to solve any problems that arise as a consequence of tube-side fouling during indirect heat transfer to process fluids or slurries. In most cases, the cleaning particles consist of chopped metal wire, however other process-specific materials have been used. In addition to the mitigation of fouling effects, a number of other significant benefits for slurry heating are afforded by the mode of operation of the self-cleaning fluidized bed heat exchangers. Increased turbulence at the slurry/tube interface is imparted by the action of the fluidised particles, resulting in very high heat transfers at relatively low liquid velocities. Furthermore, given the thixotropic nature of most process slurries, the action of the fluidised particles imparts additional shear to the process slurry, resulting in shear thinning effects with a consequent reduction in pressure drop and enhancement of heat transfer across the heat exchanger. The benefits provided by the self-cleaning fluidized bed heat exchanger make it the ideal option for the indirect heating of laterite nickel slurry for High-Pressure-Acid-Leach (HPAL) plants. This article explains the principle and application of the self-cleaning fluidized bed heat exchanger technology for the processing of laterite nickel and cobalt slurries in HPAL plants. It also presents an elegant method to revamp existing direct heated laterite nickel and cobalt processing plants into an indirect heated configuration employing self-cleaning fluidized bed heat exchangers.

Jan 1, 2004

By Dwayne D. Tannant

This paper presents a new mining concept for oil sands called ?hydraulic underground mining of oil sands? or HUMOS. While this mining method is still at the conceptual stage it has great promise to allow extraction of bitumen from areas that are currently uneconomical or technically infeasible using surface mining or steam assisted gravity drainage. HUMOS is founded on a combination of recently proven technologies such as directional drilling, water jet cutting of oil sands, slurry transportation, cold water extraction of bitumen, and thickened tailings. One key component in the mining concept is the caving of oil sands and the creation of an underground cavern. Scaled-down physical models will be designed and built to demonstrate water jet cutting, cave development, and insitu primary bitumen separation. These will be used as a &apos;proof of concept&apos;. On-going research will establish and prioritize issues that need to be resolved, outline key areas where further research is needed, foster establishment of research teams to divide and conquer the important questions, and create framework for future coordinated research efforts.

May 1, 2001

By August E. Vandale

I speak to you today on the subject assigned to me, "Subsidence - a Real or Imaginary Problem", as a representative of Consolidation Coal Company (a wholly owned subsidiary of Continental Oil Company). The information I relate to you is our experience in the Pittsburgh Coal Company Division of Consol and covers the Pennsylvania properties and mines with particular emphasis on the mines in the south- western portion of the State or in the immediate vicinity of Pittsburgh, Pa. Mining of Freeport and Pittsburgh seams of coal in the Pittsburgh vicinity dates back over one hundred years. Consol, or its predecessor, Pittsburgh Coal Company, has been actively engaged in mining in the area since Pittsburgh Coal Company was organized in 1900. Pittsburgh, Pennsylvania came into prominence as the Steel City largely because of the vast reserves of high grade metallurgical coal readily available in the immediate vicinity and also because of its favorable river transportation. Early in the 1900&apos;s we operated over 100 small coal mines, with operations located in the Counties of Allegheny, Fayette, Washington, Westmoreland. We have also operated mines in Somerset and Greene Counties. Titles in Pennsylvania can be in three estates: (1) title in fee, (2) title to the mineral, (3) mining rights permitting the removal and extraction of the mineral with or without waiver of surface damage. Consol has over the years acquired good legal title to the coal lands purchased from individual farm owners, with good broad mining rights, and in 98% or more of its title has a complete waiver of surface damage or the right to subside the surface land. In the early days of our Company, individual coal farms were purchased from land owners. Many of these titles severed the coal estate from the in fee title and good mining rights with waiver of surface were conveyed in the original severance deed. Thus, minable coal reserves were put together by the purchase of the coal under many individual farms in an area. In the early years, the mines practiced hand dug mining - later going to mechanical cutting with hand loading of the coal. Systems used were entry driving with room and rib panels. We have practiced full recovery mining as far as practical during the years of hand loading, as well as in the later years when the mines were mechanized. Mining system layouts, methods and procedures have changed from time to time to keep pace with improved mining machinery and new inovations, such as roof bolting and rubber tired haulage.

Jan 1, 1967

By Byoung Whie Lee

In order to investigate the change in surface energy as a function of cold work ad environment, the contact angles between a liquid and the surface of elec-tropolislzed aluminum with various degrees of cold work were measured. Specinlens cut from aluminum rod (99.99 pct Al) were annealed at 600°C for 24 hr and then cold compressed parallel to the drawing di-rectzon of the rod in increments of approximately 10 pcl from 0 to 70 pct. The sections, taken transversely to the drawing direction, were mechanically and electro chemically polished. Contact angles between the sessile drop of distilled water, glycerin, and glycol and the specimen surface were measured optically. The differences in interfacial energy were calculated from the contact angle data. The effects of chemical washing and surface roughness of the specimen on the contact angle were also studied. The liquid contact angle was a linear function of the degree of cold working (D) ad changed markedly with differed liquids. THE plastic deformation of polycrystalline metals induces a preferred orientation in crystal structure. A preferred orientation changes the atomic density of a metal surface. This change in surface atomic density brings about the changes in surface interactions of the metals."&apos; Also, the plastic deformation of metals raises the internal energy by increasing the stored energy.&apos; Consequently, the total Helmholtz free energy of the metal increases and, in turn, the surface free energy of the metal. In order to study the effect of plastic deformation on solid surface phenomena, the liquid contact angle of a sessile drop made on cold compressed and elec-trochemically polished aluminum was measured. The preferred orientation in aluminum, due to uniaxial compression, is known to be [110] direction parallel to the compression axis. However, this description is only a first approximation of a rather complex orientation. In actuality, half the crystallites are more than 10 deg from this orientation, regardless of the amount of compression." For randomly oriented fcc crystals, the average surface atomic density can be calculated as follows: The number of atoms in a unit volume is 4/a3, where a is a lattice constant. Hence, the number of atoms per unit surface area is about (4/a3)2/3 = 2.52/a2 However, when the preferred orientation took place along [110] direction, the surface atomic density is as follows: The area of (110) plane of a unit cell, considering ridges and valleys, is BYOUNG WHlE LEE, Member AIME, is Research Metallurgist, Atomic Energy Research Institute of the Republic of Korea, Seoul, Korea. Manuscript submitted May 29, 1968. IMD 2 x J2- a x Ga = 6a2 Since this plane contains 4 atoms, the surface atomic density is 4i6a2 = 2.3/a2 Upon changing from random to preferred orientations, the surface atomic density decreases about 10 pct. The increase in the stored energy and the change in surface atomic density due to plastic deformation would certainly alter the surface tension of a metal. EXPERIMENT High purity aluminum rod of 6-mm diam (99.99 pct Al, obtained from Johnson, Matthey & Co., Ltd, London, England) was cut into sections approximately 1 cm long. The transverse cross section was mechanically polished. Then, the specimens were annealed in air at 600°C for 24 hr. Thus, eight annealed specimens were uniaxially compressed at room temperature from 0 to 70 pct of cold working with an increment of 10 pct. The extent of cold working was determined by the percentage of reduction in axial length to the original length. The specimens were further polished mechanically and, then, electrochemically with the Modern Battelle Type 1 electropolishing solution with a current density of 0.3 to 0.4 amp per sq cm and an electrode potential of 8 to 12 v at the solution temperature of 78" to 82°C for approxirr~ately 5 min. The Modern Whlte Diffusing Screen \t/ --------------- re Goniometer for Mercury Lamp ^-^ Sessile Drop ¦=• Condenser c=> Microscope l_*~_i bJ Mlcromster Filer with Protmcter Fig. 1—Schematic diagram of apparatus set-up for liquid contact angle measurement.

Jan 1, 1970

By Arthur Aracely de Araujo Alves, Joelson Inacio Dantas Teixeira, Flanelson Maciel Monteiro, Carlos Vinicios Galdino de Melo, Pedro Henrique Medeiros Câmara, André Luiz Moura dos Santos, Kleison Barbosa Cândido da Silva

A argila é uma matéria prima com diversas finalidades na indústria. Entre as principais características desse material, destaca-se por ser terrosa, de granulometria fina, e suscetível à moldagem em função da consistência plástica que adquire em presença de certa quantidade de água. No caso do revestimento cerâmico, estes podem ser classificados de acordo com características do processo, propriedades tecnológicas e aplicações. A cor de queima do suporte é um fator de grande importância tecnológica e classifica os revestimentos em produtos de cor vermelha e produtos de cor branca. Contudo, este trabalho tem como objetivo o estudo das propriedades tecnológicas de uma argila de coloração branca, oriunda da cidade de Vera Cruz/RN que é localizada na microrregião do agreste potiguar, a fim de analisar suas propriedades tecnológicas e indicar sua viabilidade econômica. Para tanto, os corpos de prova foram confeccionados por pressão uniaxial, usando uma prensa hidráulica com uma pressão de 21 MPa. As amostras foram sinterizadas em um forno tipo mufla nas temperaturas de 900°C, 1000°C e 1100°C, com taxa de aquecimento de 10 °C/min e isoterma de 60 minutos. As propriedades tecnológicas das amostras foram analisas usando os ensaios de retração linear (RL%), massa específica aparente (MEA), absorção de água (AA%), perda ao fogo (PF%) e porosidade aparente (PA%). A composição química da argila foi analisada através da fluorescência de raios-X (FRX). Ao final do processo observou-se que a argila pode ser usada para compor massas cerâmicas, especialmente pela sua coloração clara, todavia os valores dos ensaios de AA% e PA% foram elevados o que demostra que o material necessita de outros componentes mineralógicos para ser usado industrial, especialmente na indústria de revestimentos.

Mar 1, 2019

B. C. MADDEN, JR.2-My comments have no connection with any particular paper; however, since we have talked of stress-corrosion cracking of aircraft parts, cartridge cases? coffee urns, bridge wire, etc., I feel I must mention the apparent significance of this symposium being held in Philadelphia, where perhaps the most famous stress-corrosion crack exists-that of the Liberty Bell. This noon I took advantage of an opportunity to see the Liberty Bell; I commend it to your attention. CHAIRMAN C. S. Cole 3That is true, the illustrations close at hand are the ones we often overlook.

Jan 1, 1945

CHAIRMAN LITTLEJOHN: Some of the members will want to question Mr. Farnham on some of the things he has brought tip, so we will throw the meeting open for discussion. I am quite sure Mr. Farnham will be willing and glad to answer any questions that may be put to him. MR. HOLMAN: I would like to ask Mr. Farnham a question in regard to the Duckbill: How wide a face will it operate without moving the bill? MR. FARNHAM: The Duckbill is a device that was developed in the Union Pacific Mine at Rock Springs, within the last few months, and it is shaped something like, a dustpan, with discharge throat in the rear. They made one seven feet wide and found it was too wide, and the one they are using now is between three and four feet in width. The front section of the conveyor, which attaches to the duckbill, meshes into it to form a sliding section, and the front end of the Duckbill is pushed by the upper segments. I saw one used in a room twenty-four feet wide, and they drew it back after they cleaned out one room and pushed it forward again. MR. HOLMAN: You have no arrangement other than ratchet work? MR. FARNHAM: The ratchet is for forward working and back; the sections are made 12 or 13 feet long, and the stroke of the conveyor automatically works the ratchet; they can ratchet it back; it is a hand device. MR. HOLMAN: They just swing the end of the conveyor across the face to pick up the loose coal? MR. FARNHAM: Yes; they are also planning to use it endwise along the panel face, that and the room work both are quite new in their application, and I do not think the Union Pacific is giving out any results as yet, because the system has not been in use long. MR. HOLMAN: We are planning on putting one in very shortly. MR. HALL: I understand they can swing it over 30 degrees one way or the other, and it goes the same way easily because of the continual jar of the back and forward motion on a 60-degree swing. SECRETARY SHUBART: Take on a comparatively long conveyor, you can get quite a sweep, a large part of the circle. The Duckbill could command quite a large range. For a 12-foot entry, take a four-foot wide advance through the middle of the shot coal, with a 12-foot advance, ratchet back, swing the Duckbill to the rib and repeat; but I do not think they could get as much as 60 degree. on the end of the Duckbill without curving further back. The conveyor is light and not normally set on any permanent foundation. I saw one of Mr. McCarty&apos;s first machines, a rather rudimentary one, clean tip a 12-trot entry, 21 tons of coal, in 16 minutes, three men at the face and one at the loading end. MR. FARNHAM: The average time to clean the entries is about an hour-to clean up good-it wouldn&apos;t take but a short time; that is why they get this record of several cuts a shift. CHAIRMAN LITTLEJOHN: Are there any other questions you would like to ask Mr. Farnham? MR. HOLMAN: We were discussing this entry driving in regard to the entry loader; an entry loader in advance work, just what you have to do to place the jackbars with the sheave-blocks? Do you dig along the ribs after the coal is shot or do you have any other scheme that could be worked out to a good advantage? MR. FARNHAM: This record is a report I have just received from our Chicago office, without the full details, which I have written for. I am sorry I cannot give you the details. This was an Indiana or Pennsylvania mine, near Pocahontas, not the one where they had an accident. I assume they set the jacks ahead and swung and dumped the coal partly out with a scoop and partly by hand, but the application for that for entry driving is entirely new. The reports stated that they anticipated using that as a standard method of entry driving in the future. I will be glad to see that you get a copy of it when I get the report completed. MR. MONAY: Mr. Shubart, did you say they loaded 12 tons in 16 minutes? SECRETARY SHUBART: Twenty-one tons. MR. MONAY: How long did it take to change the machinery out of there

Jan 1, 1926

By Verônica Scarpini Candido

Foi notado que o rejeito originado a partir do beneficiamento do caulim é rico em silico-aluminatos, apresentando assim potencial em processo de adsorção. O presente trabalho consiste em avaliar o potencial adsortivo do rejeito do caulim quimicamente tratado. Foi utilizado o corante de azul de metileno (AM) em solução aquosa para se ter o conhecimento de adsorção do rejeito de caulim in natura e calcinado a 700ºC onde ambos foram submetidos a uma ativação química com H2SO4. Após o equilíbrio da amostra do rejeito do caulim junto ao azul de metileno, suas concentrações foram determinadas por espectrofotometria. Os resultados preliminares comprovam que o rejeito apresenta uma boa capacidade adsortiva para concentração de até 50,00 mg/L de AM, demostrando, potencial para ser utilizado na remoção de corantes em tratamento de afluentes.

Oct 30, 2017