Search Documents

By Baokuan Li, Qiang Wang, Zhu He

"A mathematical model has been developed to investigate the magnetohydrodynamic (MHD), thermal, and solidified behavior in electroslag remelting process. Based on the finite volume method, a multiphase coupling MHD approach is employed to investigate the droplet formation as well as movement in molten slag under the action of an alternating current. The VOF formulation is adopted for interface tracking. The electrical potential method is adopted for the electric current and magnetic field. The Electromagnetic force and Joule heating are recalculated at each time step and then is implemented in the momentum and energy equations as a source term, respectively. Moreover, solidification of the metal is described by an enthalpy-based formulation, while the mushy zone is treated as a porous medium with porosity equal to the liquid fraction. The model is used to investigate the effect of electrode tip shape on MHD, thermal, and solidified behavior and provide valuable information.IntroductionElectroslag remelting (ESR) process has been used widely to produce high-performance alloys dedicated to critical application, such as hot work tool steels, nickel base alloys, the manufacture of components in aerospace and landbased turbines, etc. Figure 1 shows a schematic diagram of ESR process including a consumable electrode, a molten slag pool, a liquid metal pool, a solidified ingot, and a water-cooled mold. Alternating or direct current flows from the electrode to the water-cooled baseplate through the high resistivity calcium-fluoride-based molten slag which result in Joule heating and Electromagnetic force (EMF). Part of the Joule heating melts the electrode and the droplets travel through the slag and accumulate the liquid metal pool. The electrode is continuously advanced into the slag as it melts to build up an ingot of improved structure and composition by controlled solidification and chemical refinement. The metallurgical properties of the remelted ingot are really related to the solidification structure, which strongly depends on magnetohydrodynamic, thermal, and solidified behavior in the molten slag, liquid metal pool, and mushy zone."

Jan 1, 2014

By W. C. Holliman

This report on the characteristics of commercial aviation gasolines presents compilations of inspection test data furnished on their products by manufacturers of commercial grades of aviation gasoline, and special data obtained in Bureau of Mines laboratories on samples of these gasolines. Data and physical samples for the survey were submitted by 15 manufacturers on 18 grade 80, 21 grade 91/98, 22 grade 100/130, and 10 grade 115/145 aviation fuels.

Jan 1, 1948

By Qiang Guo, Zongliang Zuo, Mengqi Wei, Qingbo Yu, Qin Qin

Activated carbons, derived from waste ion-exchange resin by CO2 physical activation, were applied to separate CO2 from flue gas against global warming. The BET specific surface areas of activated carbons at different activation temperatures and times were investigated. The CO2 adsorption capacity was tested under non-isothermal and isothermal conditions. The experimental results show that when keeping the activation temperature constant, the specific surface area increases firstly and then decreases with increasing activation time. For the given activation time, the specific surface area rises firstly and then declines with increasing activation temperature. The adsorption capacity decreases with increasing temperature. The maximum adsorption capacity is 51.46 mg/g under the condition of 298 K and pure CO2. Fractional order kinetic model is the best one to describe the kinetics of CO2 adsorption. The activated carbons show the potential to be an effective adsorbent for the removal of CO2 from flue gas.

Mar 1, 2018

By T. Egleston

AT the Dover meeting of the Institute, Mr. F. A. Canfield showed some of the members a machine which he had invented for dressing mineralogical and geological specimens, which he has since modified and brought to such a high state of perfection, that after having used it for several months in preparing specimens for the cabinet of the

Jan 1, 1876

By T. Egleston

At the Dover meeting of the Institute, Mr. F. A. Canfield showed some of the members a machine which he had invented for dressing mineralogical and geological specimens, which he has since modified and brought to such a high state of perfection, that after having used it for several months in preparing specimens for the cabinet of the

By T. W. Martin

The use of conveyors in large, open pit mines and their drawbacks are discussed. Technological developments such as long distance conveyors capable of handling large rocks are explored. The development and testing by the Bureau of Mines of a prototype crib and cable conveyor for handling large rocks are discussed, and possible modifications of the concept for a production model are examined.

Jan 1, 1984

By P. A. Boeck

(San Francisco Meeting, September, 1915) THE thermal insulation of high-temperature equipment for industrial purposes is a subject that has not received from engineers and designers the attention its importance deserves. This may be attributed to a number of causes: In the first place, heat flow is a rather difficult factor to measure under the working conditions of an industrial furnace, and until the comparatively recent introduction into certain operations of the heat balance sheet, with a systematic attempt to account for the discrepancies in the totals, the various causes of heat losses and the reasons for their existence were not brought to light. Moreover, such rapid advancement and radical changes in the design of equipment, especially in metallurgical lines, have occurred that practice has apparently outdistanced the theory of design. In the modern tendency toward greatly increased size of units, effort has seemingly been made to utilize the heat of fuel gases without proper. attention having been paid to conserving heat energy and confining it strictly to the points of maximum activity. The systematic study of the thermal properties of structural materials, which is being carried out by various government bureaus and also by a number of technical societies, is forming the basis for more intelligent and consistent work in the economically important subject of prevention of fuel waste.

Jan 8, 1915

By Veerendra Singh, NILAMADHABA SAHU, ARIJIT BISWAS

Manganese alloys are important raw materials for steelmaking. However, selective mining of high-grade manganese ore resources has resulted in a scarcity of these high-grade Mn ores (Mn: >42; Mn/Fe: >5). The present research work is carried out to explore a new smelting reduction process to produce high-Mn/Fe syntheticMn ore from low-grade ferruginous manganese ores. Representative samples of low-grade ores (Mn: 25–30%; Mn/Fe: ~1) were collected and smelting reduction studies were carried out using variable smelting power (20–30 kWh), carbon rate (10–20% of ore) and slag basicity (0.1–0.3) to produce high-MnO slag and manganese pig iron. Studies have shown that different-grade high-MnO slags (MnO: 38.57–58.24%; Mn/Fe: >15) and manganese pigs (Mn: 5.16–24%) can be produced at optimum process conditions. The high-MnO slag can be used as synthetic ore for the ferroalloy production process. The developed process is capable to effectively segregate the iron and manganese in the metal and slag, respectively. The optimum Mn and Fe separation (>95%) was achieved by smelting of 10 kg Mn ore batch in a 50-kVA electric arc furnace using 30 kWh smelting power and 0.16 kg of coke. The slag basicity was maintained at 0.3 and the optimum slag SiO2 was ~30%. The studies indicated that the upgrading of low-grade ferruginous manganese ores is a promising solution for achieving high-Mn/Fe-ratio synthetic ores for ferroalloy production. It can help the manganese alloy industry to overcome challenges associated with the scarcity of high-Mn/Fe-ratio Mn ores and efficient utilization of low-grade resources.

Aug 3, 2020

By Jameel Menashi

A process has been developed for recovering the refractory metal values contained in mixed secondary source materials such as contaminated grinding wastes, oxides and sludges. The wastes are calcined with sodium carbonate in air to convert the refractory metals to water soluble Na2CrO4, Na3V04, Na2Mo04 and Na2W04. The base metals, Fe, Ni, Co and Cu, are converted to water insoluble oxides. An aqueous leach of the calcine effectively separates the refractory metals from the insoluble base metals. Co, Ni and Cu can be recovered from the oxidic residue by conventional processing methods. The leach solution is purified and then treated to recover the refractory metals as Cr203, NH4VO3, (NH4)6Mo7024?4H2O and H2WO4. The purity of the products is sufficient for their use in many metallurgical applications. The Na+ values in the leach solution are recovered as Na2CO3(or NaHC03) and are recycled to the calcination step. It is shown that the process can accommodate a wide range of feed compositions and generates a minimum of aqueous effluents.

Jan 1, 1984

By Stephen C. Tadolini

The U.S. Bureau of Mines conducted a laboratory investigation designed to evaluate the stress and deformation characteristics of fully grouted roof bolts subjected to various magnitudes of end loadings. The experiment and subsequent analysis were completed, utilizing axial deformation data obtained -ultrasonically from forty-one 4-ft, grade 40 roof bolts, with a total of 132 measurement locations along the lengths of the bolts. The ultrasonic measurement instrumentation used in this investigation allowed for elongation measurements without requiring extensive bolt modifications. The results indicate that approximately 39 pct o{ the applied end load dissipated within the first 3.4 in of the bolts. However, only 3 pct of the applied load was realized beyond 28 in of the grout column. Data are presented individually for every 6-in increment of bolt length, and analysis was performed using statistical, nonlinear equations developed for 5,000 and 8,000 lb loading conditions.

Jan 1, 1990

By G. H. Lair, B. J. Langford, S. H. Rockwood

Volumetric reservoir analysis is dependent upon a firm relationship between porosity, connate water, and net pay. Capillary presswe data on core samples interrelate these three factors. It is shown that other reservoir problems may be resolved: (I) whether water production is indigenous or extraneous to the oil producing interval, (2) an oil-water contact is being approached, and (3) whether the oil-water contact is remotely situated. INTRODUCTION Volumetric analysis of carbonate reservoirs challenges the ingenuity of the reservoir engineer due to an absence of data on the minimum oil-bearing and oil-producing pores of a given reservoir rock. Many studies with this as the ultimate objective are available on the physical characteristics and fluid-flow behaviors of the carbonate reservoir. Some of these publications are: Hassler, Brunner and Deahl's1 study of the role of capillarity in oil production; Jan Law's' and A. C. Bulnes3 statistical treatment of core analysis data; Chalkley's method4,5 or estimating specific surface areas and porosity; Walter Rose's9 report on porosity, reserves, and recovery; Archie's78 tex-tural classification of carbonate rocks; Stewart and Spurlock's9 large core analysis; Purcell'sl0 mercury injection method in studying capillary pressure phenomena; Stewart, Craig, and Morse's" model multiple-phase flow test in investigating the relative permeability effect; and Fatt's12 illumi-nating network model of porous me-dia. The present study shows that the static reservoir parameters of porosity, connate water, and net productive thickness may be interrelated by utilizing a statistical arrangement of mercury capillary pressure data in addition to routine core analysis. This report summarizes the techniques that are followed to obtain these relations which are applicable to carbonate and sandstone reservoirs that do not contain clays. Capillary pressure statistical studies may be extended to include clay-bearing rocks by utilizing water capillary pressure data. POROSITY It is necessary that the laboratory determine the porosity value that includes the pores that are filled with hydrocarbons and water in the reservoir. This is the reservoir's total porosity. When true total porosity values are not available, correlations between porosity and capillary pressure characteristics lose their significance since they cannot be related through oil-base mud core data to the porosity and connate water values found in reservoirs. Methods used to obtain reliable porosity data will not be discussed; however, care should be exercised in selecting samples for measurement. In homogeneously porous formations, small core plugs sampled frequently will furnish adequate information. Where heterogeneity, particularly vugginess, is present, large-core porosity data may be required; in such reservoirs a suite of capillary pressure samples may be selected from small plugs. CAPILLARY PRESSURE Capillary pressure data provide a method for relating two carbonate reservoir parameters, porosity and connate water saturation, which in turn permit delineation of productive rock types necessary for selecting the third parameter, productive thickness. Specific applications of capillary pressure data to petroleum reservoirs were suggested by Archie8 and Pur-cell."' Their work demonstrated that in preferentially water-wet rock, porc

Jan 1, 1958

By H. Alzraiee

Traditional planning methods such as CPM and PERT have been useful tools to manage construction projects. However, the underlying model of these traditional methods often seems to fail to represent real projects as they tend to assume no interrelationship between project components. In reality, project components have complex dynamic feedback process that requires modeling of inherent uncertainty in the execution of these projects. Nevertheless, this dynamic nature and uncertainty have not been explicitly addressed by traditional planning methods. Project failure can be attributed to poor representation of the inner and outer aspects of operations that are responsible for project dynamics. Uncontrollable external forces are often cited but the real cause may be internal such as the feedback process among components of the project. An alternative perspective is offered in this paper through system dynamics (SD) that accounts for the feedback process and discrete event simulation (DES) for modeling the uncertainty. The proposed method utilizes SD method for modeling project dynamics and DES method coupled with CPM network for operational details and uncertainty, respectively. A case study that involves preparing engineering drawings in a design office is used to demonstrate the use of the developed method and to highlight its capabilities. Modeling the dynamic dimension is expected to enhance planning and scheduling of construction operations and to provide a better understanding of the impact of various internal and external factors on project schedule and productivity performance.

Aug 1, 2013

By Donald W. Breck

Zeolites were first recognized as a new group of minerals by Cronstedt with the discovery of stilbite in 1756. The word zeolite was coined from the two Greek words meaning "to boil" and "a stone" because of the loss of water when heated in the mineralogist's blow pipe. (1) In 1845 it was discovered that certain soils have the power of retaining ammonium Salts. (2) These were the first ion exchange experiments. Later it was discovered that it was the hydrated silicates in the soil that produced this phenomenon and several years later a paper was published dealing with the action of dilute salt solutions on silicates which showed that this base exchange principal, which we now call cation exchange, is reversible. The quantitative cation exchange behavior of zeolite minerals, such as chabazite, was studied. As a result any aluminosilicate which exhibited the property of ion exchange was referred to as a "zeolite;" even today the term has been applied to clay minerals as well as synthetic organic ion exchange resins.

Jan 1, 1973

By P Dowd, A Adeli, C Xu, X Emery

Geometallurgical modelling is increasingly being incorporated into mineral resource modelling and estimation as a means of increasing efficiency, decreasing operating costs and reducing risk in mining operations. Traditional geostatistical workflows for geometallurgical modelling face several difficulties, in particular, related to the non-additivity of process response variables, to highly heterotopic data sets and/or to preferential sampling designs, all of which may explain why most attempts to estimate geometallurgical response variables from assay data and mineralogy are still based on statistics and machine learning. The aim of the work presented here is to demonstrate the applicability of geostatistics to estimate copper recovery from copper sulfide ores at the Prominent Hill Iron Oxide Copper-Gold (IOCG) deposit in Australia. As recovery is non-additive, the preferred workflow is the joint estimation of the masses of metal in the feed and in the concentrate, both of which are additive variables. While the mass of metal in the feed can be estimated from abundant online assay analyses, the mass of metal in the concentrate can only be estimated from a very limited number of laboratory-scale batch flotation tests. Traditional approaches to estimating the masses of metal in the feed and in the concentrate, such as simple and ordinary co-kriging, are described and discussed. A modified version of co-kriging is introduced, which incorporates linear relationships between the mean values of the input variables, in addition to a spatial correlation model. Co-kriging with related means is shown to outperform traditional simple and ordinary co-kriging in terms of precision, accuracy and consistency of the estimates, and offers a practical and efficient tool to deal with highly heterotopic and preferential sampling designs.

May 24, 2023

Mechanism Responsible for Flocculation in Poly (N-Isopropylacrylamide) Temperature Responsive Dewatering - Attractive Interaction Forces Induced by Surface Hydrophobicity

Sep 13, 2010

By O. A. Olaseinde

The 2101 lean duplex stainless steel has wide potential application in storage, heat exchangers, and in the oil and gas industries. This work investigates the electrochemical behaviour of 2101 duplex stainless steel with an addition of 0.15 wt% ruthenium, using potentiodynamic techniques in 1M H2SO4 at 25º, 40º, 60º, and 80ºC. The microstructures of samples were characterized using optical metallography and scanning electron microscopy. The results showed that the ruthenium addition moved the corrosion potential of alloy 2101 to a more positive potential. All samples containing ruthenium displayed longer passive regions at 25°C and 80°C compared to those without ruthenium. Alloys without ruthenium had higher critical current density (icrit) values when compared to the alloys with ruthenium. Ruthenium additions decreased the passive current densities and inhibited anodic dissolution. At room temperature the corrosion rate of alloys with ruthenium was lower than these without ruthenium.

Jan 1, 2012

The world's largest steam-driven mine hoist, built by Nordberg Manufacturing Co. a half century ago, has become a major tourist attraction in Michigan's Upper Peninsula. The hoist, designed by company founder Bruno V. Nordberg, is located in the Quincy Mine Number Two, just north of Hancock. Nordberg began construction of the mammoth machine before World War I, but delayed completion until after the war. The hoist became operational in 1920 and continued running until the mine was shut down in 1931.

Jan 9, 1968

By Blamey Stevens

(San Francisco Meeting, October, 1911.) IN this paper, which is a logical extension of my paper, The Laws of Intrusion, 1 the various pressures of emanation and their mechanical causes and effects on the large scale of nature are determined, .and a classification of emanations is deduced therefrom. The Subterranean Sea. The subterranean sea is here defined as the intercommunicating water contained in the trains of pores and fissures of the rocks down to great depths. Whether the actual amount of water constituting this subterranean sea be large or small, does not enter into the present argument, since the static pressure of this water at any particular depth is not a function of the quantity : it involves only the depth and the density of the water. Densities. The total pressure at depths down to 10 or 15 miles is made up of the rock-stresses investigated in my previous papers, and the pressure of the subterranean sea. The latter component must evidently be equal to the weight of a solid column of the overlying water of unit sectional area. As water expands with heat, it should really be necessary to sum the density at every level. A knowledge of the densities of water under a variety of conditions is therefore needed, but does not seem ever to have been ascertained for such combined pressures and temperatures as we have to consider. The specific gravity of water at 28° C. for various pressures up to 400 atmospheres, has been determined by Barus,2 who

Apr 1, 1912

Courses in chemical engineering and metallurgical engineering at the University of Queensland were compared and the main difference was found to be the greater emphasis on the application of chemical engineering fundamentals, particularly chemical thermodynamics, to specific processes in the metallurgy course. This reflects the distinctive features of extractive metallurgical processes which are not common in other chemical engineering processes and which justify the study of extractive metallurgy in its own right. B.Sc. courses in metallurgy provide one way in which the specialist knowledge of extractive metallurgy can be taught. General metallurgy courses are considered to be preferable to those restricted solely to extractive metallurgy since graduates of a general course have a wider choice of employment, while excessive emphasis on extractive metallurgical applications in chemical engineering courses could reduce the non-specific nature of these courses. Postgraduate diploma and higher degree programmes are avenues for non- metallurgists to acquire knowledge of the discipline.

Jan 1, 1984

By C. C. Popoff

The Dunkleberg district is in the Flint Creek Range of the northern Rocky Mountains, about 45 miles northwest of Butte, Mont. Silver - lead and zinc mineralization occurs over an area 4 miles long from north to south and 1 to 2 miles wide from west to east. Ore in appreciable quantity has been produced, mostly from the Forest Rose group of mines in the southern part of the district. The Forest Rose mine was the largest producer of lead and the Wasa mine, a mile farther south, the main producer of zinc. The total output of ore from these properties during World War II was 113,000 tons, or 98.2 percent of the total recorded production of the district. The Wasa mine was examined by a Bureau of Mines engineer2/ in 1944. Subsequent investigations during 1946, 1947, and 1948 included trenching and drilling Fn the Wasa area and examination of the Forest Rose and other mines.

Jan 1, 1953