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By Tanai Marin

Modelling of pyrometallurgical processes can become extremely challenging when the process involves complex chemical reactions, phase change, multiphase flows, heat and mass transfer and fluid flow. Traditionally modelling involving complex thermodynamic equilibrium and thermochemistry are treated separately from problems in which transport phenomena are dominant, such as CFD and heat transfer studies. The separation is also necessary due to the lack of modelling tools that can effectively couple both solution thermodynamic and transport phenomena or even multiphysics problems. However, there are, quite often, problems in high temperature process metallurgy in which it is not possible to simplify this two modelling approaches. Typical cases of this are for example, the modelling of slag freezing on furnace walls (electric or flash furnaces) to create a protective layer in front of the refractories hot wall, the formation of build up from the matte or metal phases at the hearth of the furnace, calcine smelting from charging piles into slag phase, etc. The problem is even more challenging in nonferrous pyrometallurgy as most, if not all, of the condense phases are highly non ideal solutions involving several components and exhibiting complex crystallization paths and miscibility gaps, such as the Fe-Ni-Cu-S matte, FeO-Fe2O3-SiO2, FeO-MgO-SiO2 slags, etc. In this paper, an approach to model coupled problems involving multiphysics and solution thermodynamic is presented. The approach consists in developing in-house a library containing the Gibbs energy minimization routines and using the local equilibrium concept for process modelling from a multiphysics commercial software (COMSOL). Simple test cases, such as building a non-ideal binary phase diagram on a CFD package is presented, the limitations and of other classic approaches such as equilibrium or Scheil cooling are discussed and compared to this model.

Jan 1, 2015

By H. O. Seigel, J. C. Gingerich, E. O. Köstlin

"To satisfy their continuing need to replenish or expand their ore reserves, mining companies are faced with the dilemma of arriving at a proper balance between the dual avenues of discovery through in-house exploration and of acquisition of properties that are relatively proven or are even in production. The returns from exploration activities may be spectacular, but are unpredictable. The allure of an acquisition lies in its promise of quick and risk-reduced addition to reserves. However, it is historically clear that quantum increments in shareholders’ values have arisen primarily through major exploration discoveries, rather than through major late-stage acquisitions. Late-stage acquisitions can prove highly profitable, sometimes based upon the planned use of superior mining or metallurgical technology, but more often occur as the result of unexpected windfalls. At the other extreme, they can become expensive failures through inadequate due diligence, or unforeseeable factors.Citing numerous case histories and industry statistics, it is concluded that a judicious combination of both exploration activity and the acquisition of prospects is the most advantageous strategy for adding new ore reserves. A skilled exploration staff is essential for success, be it through exploration discoveries or through opportunistic acquisitions, preferably at their early stages. In the future, it is anticipated that there will be fewer opportunities for acquisition because of reduced funding for junior exploration companies, leading to increased competition and higher costs for fewer properties, both in the advanced exploration and mining stages."

Jan 1, 2002

By E. C. Lane

This paper is the first part of a report giving the results of the Bureau of Mines' twenty-third semiannual survey of motor gasoline marketed in the United States. A companion report, Part II, is in preparation and will give a more detailed discussion of the whole survey. Results of the determination of copper-strip corrosion, color, sulphur content, copper-dish evaporation residue, and gum content as given by the Bureau of Mines steam-oven method will be presented in the second paper, which will also include the prevailing retail price and the tax at the time the sample was taken. This paper deals specifically with data relative to gravity, Reid vapor pressure,5 and distillation (method 100.13).6 The samples tested were divided into "competitive-price gasolines" and "premium-price motor fuels," a method of presentation that was begun with the twenty-second semiannual survey.7 A total of 312 samples were collected from service station pumps in 20 cities throughout the United States. Of this number of samples, 207 were "competitive-price gasolines" and 105 were "premium-price motor fuels." All of the samples were collected in March, 1931, and analyzed at the Petroleum Experiment Station of the United States Bureau of Miner at Bartlesville, Okla.

Jan 1, 1931

By T. D. Hackett

Multislice mining methods were analyzed by the U.S. Bureau of Mines to determine their application to western United States thick coal seams; ground control, geology, and costs were considered. Multislice mining is used in widely varying seam conditions worldwide, including flat seams too thick to mine in a single pass, pitching thick seams, and seams containing a rock parting. Longwall multislice methods predominate, but room-and-pillar variants also exist. The initial use of the method in western seams is planned at a deep Colorado mine where a rock parting will be used to separate two slices mined by longwall. Ground control and spontaneous combustion are major hazards associated with multislice mining. A well-consolidated upper slice gob can reduce ground control problems and provide a seal against spontaneous combustion. Geologic analysis indicates that the consolidation of the gob depends on the composition of the upper slice roof, the presence of water, and sufficient overburden pressure. A geologically competent intermediate rock parting can also reduce ground control problems and seal against spontaneous combustion. To compete in western coal markets, the cost of multislice mining must be within the range of normal longwall costs. Analysis indicates that multislice operating costs should be within this range, and that multislice mining costs decrease as panel width increases. Relatively wide (600 to 800 ft) panels also provide increased coal recovery.

Jan 1, 1990

By Viswanadham B. V. S., Babu K. V

Wind energy is one of the most economical renewable energy sources. In order to support wind turbines onshore or offshore open-ended monopile foundations are widely used. Unlike conventional structures, wind turbine foundations experience a large magnitude of lateral loads in the order of 20 % to 30% of total vertical loads. The presence of soft clayey layers at shallow depth along the coastal region, offers lesser lateral load resistance to monopile foundations. One option to enhance lateral load capacity is by introducing fins to the outer surface of the monopiles. Studies pertaining to lateral load response of finned piles in clayey soils are very sparse. This paper presents some of the numerical model studies on the lateral load response of monopiles and finned piles in soft and stiff clay. In the present study, three-dimensional finite element analyses were performed on monopiles as well as finned piles. Analyses were performed in clay with different consistency varying from soft to stiff. Pile material is mild steel for all analyses. The pile section modeled as linear elastic material whereas soil was modeled as Mohr – Coulomb constitutive model with non-associated flow rule. Monopiles and finned piles having four and eight fins with different fin sizes and configurations are considered during the analyses. Finned piles advantage over monopiles to resist lateral load is highlighted in the present study. The results have shown that fins are effective to enhance the lateral load carrying capacity of monopiles and also it reduces the bending moment in monopiles for a given design load.

Sep 1, 2022

By G. A. Brady

Laboratory tests were conducted to determine the technical feasibility of separating anthracite particles from a water-anthracite slurry by atomizing the water and removing the resulting mist in an air current. Products containing 21 percent or less moisture were obtained from slurries made with minus 60-mesh anthracite. Typical recoveries ranged between 67 and 79 percent of the feed when the slurries were atomized in air currents with velocities below 70 ft/min.

Jan 1, 1967

By D. T. Iseley, A. L. Atta-alla

INTRODUCTION The extension project of the East Line Subway of Atlanta's subway network includes the construction of two single track transit tunnels under Interstate Highway 285. The project will be in DeKalb County, Georgia. The length, width, and height of each tunnel are 54.25, 6.3, and 7.2 m (178, 21, and 23 ft) respectively. The ground cover above the tunnel crown ranges from 1.5 to 3.25 m (5 to 11 ft). A soil pillar about 5.5 m (18 ft) wide will remain between the tunnels. The construction of each tunnel includes (i) installation of 21 steel soil support pipes of 75 cm (30 in) diameter, (ii) jet grouting 15 soil cement shafts of 60 cm (24 in) diameter in the soil under the pipes, (iii) contact grouting behind the tunnel lining and between soil support pipes and pavement, (iv) excavation of soil inside the soil support arch, and (v) installation of steel pile foundation, steel sets, and permanent tunnel lining of cast-in-place concrete, all as shown on the cross section in Fig. 1. The soil profile can be described from top to bottom as cement/asphalt concrete pavement, a fill layer consisting mostly of stiff sandy silt/firm silty sand, a residual soil layer consisting mostly of silty sand/sandy silt, partially weathered rock, and solid rock.

Jan 1, 1991

By P. B. Altringer

Searles Lake, CA, contains the largest known domestic tungsten resource. The brines in this near-dry lake bed, located in the Mojave Desert 130 mi northeast of Los Angeles, contain an estimated 135 MMlb of tungsten. However, the low concentration of tungsten (0.080 g/L W03) in the supersaturated brine makes selective tungsten extraction very difficult. Although many brine chemicals are extracted from the lake, tungsten recovery was an elusive goal prior to Bureau of Mines development of an ion-exchange technique. This publication describes the Bureau process. The following subjects are ad-dressed: ? The Searles Lake tungsten resource. ? General problems associated with tungsten recovery. ? Bureau research objectives. ? Synthesis of ion-exchange resins. ? Development of a two-stage ion-exchange tungsten extraction and concentration procedure. ? Product recovery and purification. ? Economic evaluation. Flowsheets for recovering three products (calcium tungstate, sodium tungstate, and tungstic oxide) are presented and evaluated, as well as a summary of the research effort and potential applications.

Jan 1, 1985

By R. R. Sayers

Although the attention of those interested in diseases peculiar to mining as teen focused recently on one duct disease - silicosis - other respiratory diseases may cause more suffering and economic loss. The increased incidence of these diseases usually is attributed to exposure to abnormal air conditions underground, such as sudden changes from high to low temperatures, excessive dust, and noxious gases. The principal respiratory diseases to which the mine is subject axe bronchitis, influenza and pneumonia, pulmonary tuberculosis, anthracosilicosis, and. silicosis. Although the mortality statistics in some of the tables included in this paper are old they have been corroborated by later, lees complete data Bronchitis Bronchitis is en inflammation of the bronchial tubes due, among other causes, to the inhalation of irritants such as dusts (organic and inorganic). Occupations that entail exposure to atmospheres polluted, by irritating gases carry with them the risk of bronchitis. According to Collie (1), it cannot be distinguished clinically from bronchitis occurring among the general population, and its association with tae inhalation of dust or gases usually is unrecognized.

Jan 1, 1941

By Abegail Endraca, Allan Sebastian, Andrew Raine, Allan Patdu

The project involves the construction of a new aqueduct tunnel by an Earth Pressure Balance TBM tunnel for the Novaliches-Balara Aqueduct No 4 (NBAQ4) project in Metro Manila. It comprises a 7.3 km long and 3.1 m internal diameter tunnel that can deliver up to 1,000 MLD of raw water and the tunnel passes under urban residential and urban populated areas adjacent to and along Commonwealth Avenue. A new reservoir intake structure was constructed in the La Mesa reservoir by a cofferdam and the TBM breakthrough connected the reservoir to the outlet surge shaft structure and the downstream pipe network system connecting to the Balara Water Treatment Plant. The TBM incorporated a double articulated head configuration to allow tight 80 m radius curves to navigate some of the difficult alignment considerations. The alignment passed very close to some existing foundations for MRT7 and needed to clear several tight curves to remain within government land ownership. The project excavated through the local Guadalupe weak rock formations and there was minimal ground movements observed as a result of the work.

Jun 13, 2023

By K. Chattopadhyay

Fluid flows in metallurgical reactors play a vital role on liquid metal cleanliness for both ferrous and non-ferrous metallurgy. Thus, it is absolutely critical to understand different fluid flow mechanisms, and the use of computational methods to model the complex non-isothermal, turbulent, single- and multiphase-flows, has to be appreciated. The present case study emphasizes on controlling the flow of liquid steel in a tundish and enhancing liquid metal cleanliness. CFD modeling was used to build a robust mathematical model, and effects of flow control furniture and non-isothermal conditions were analyzed. The mathematical model was validated against water model experiments. Parameters that were conducive for inclusion removal were identified and implemented in the plant. Some flow control devices could increase inclusion removal to a great extent compared to the existing configurations. In cases, where a hot ladle was poured into a relatively cooler tundish, inclusion removal was better, whereas results were catastrophic in cases where colder liquid was poured from ladle to the tundish. Similar techniques can be applied for other liquid metals including light metals and non-ferrous metals.

Jan 1, 2015

By R. L. Bowron

GROWING use of basic slag in the agricultural industry is of special interest and importance to the iron and steel industry of the Birmingham district, providing an increasing outlet for this by- product. Such use of basic slag was first developed in England about fifty years ago where it soon became wide- spread. About twenty years ago the Tennessee Coal, Iron & R. R. Co. began its production in the United States after exhaustive tests had demonstrated its high value here as in Eng- land. It is particularly valuable on heavy clay and acid soils, improving their physical condition, increasing their alkalinity where that is desirable, and providing soluble phosphate and small amounts of manganese to soils deficient in these respects. Its use in agriculture is growing as its advantages are becoming more widely known.

Jan 1, 1937

By M. Dupuis

It has been previously demonstrated [1,2] that using selective collector bar rodding has a big impact on the uniformity of the current density at the top surface of the cathode block and hence on the intensity of the horizontal current in the metal pad, The present study investigates the impact of using selective collector bar rodding on the MHD stability of a 500 kA aluminium electrolysis cell, For this purpose the recently developed MHD package for the aluminium reduction cell time dependent behavior is used.

Jan 1, 2005

By Theodore H. Eyde

In 1971, the Minerals Division of The Superior Oil Company acquired exploration rights to an unpatented claim group in the Superior (Pioneer), Arizona mining district, lying west of the Concentrator fault. This major post-mineral fault displaces the Magma vein-fault, which is mined in the Magma Mine at Superior, Arizona. The Magma vein-fault and the enclosing section of pre-mineral rocks consisting of Paleozoic and younger Precambrian sediments and diabase, is overlain by a thick section of post-mineral rocks, consisting of the Gila conglomerate, the Apache Leap dacite, and the Whitetail conglomerate. Geologic information on the thickness and attitudes of the rocks obtained from previous diamond drilling indicated that the section of post-mineral rocks might be from 3,000 to over 4,010 feet thick in the target area. (Figure 1) The Magma vein-fault is a steeply dipping vein which has produced nearly a billion dollars of copper, zinc, silver, and gold. It has been mined continuously for nearly 10,000 feet along the strike and nearly 5,000, feet vertically down the dip. It ranges from less than a foot to over 50 feet wide and contains sulfide mineralization con¬sisting of pyrite, chalcopyrite, bornite, and chalcocite.

Jan 1, 1973

By H. S. Auvil

[The shrinkage of coke after formation is one of the variables that effects the net expansion of the change in both industrial and test ovens. Various test results5/ have been interpreted as indicating that cokes from certain coals shrink to a marked extent and that other cokes show very little shrinkage; but no comprehensive experimental study of the shrinkage of coke after its formation and of the factors influencing this shrinkage has come to the attention of the authors.]

Jan 1, 1940

By F. S. Thurner

"This paper describes the engineering and construction activities of the ""design-build"" project awarded to the joint venture of Foundation-Comstock-Janin for the construction of the plant and wharf facilities, camp site, power plant and all supporting services. As a member of the Foundation Group of companies at that time, Fenco actecl as consulting and design engineers for the project. Particular emphasis is given to the problems which adversely affected design and construction activities due to prevailing arctic conditions and the remote location of the project. The paper also describes the approach taken in the investigation of the site and soil conditions as well as the selection of the special structures for the 225,000-toncapacity fibre storage building, the wharf structure for 50,000-dwt vessels, and the 1,000-tph-capacity reclaiming and ship-loading facilities . It further covers the logistics problems and the scheduling activities related to the short duration of the shipping season, and the transportation of equipment and mate1•ials by sea as well as by air."

Jan 1, 1976

By I. Druce, C. Li, T. Qu, J. Dong, W. Y. Xinchao, V. Nkuna

CITIC Heavy Industries has a large installed base of grinding equipment throughout Africa in different configurations, including high-pressure grinding rollers with ball mill and semi-autogenous ball crusher. The total installed power of CITIC’s mills exceeds 430 MW. In this paper, we compare several typical grinding circuits of copper in Africa with about 15 kt/d throughput based on ore properties, process selection, equipment sizing, and key equipment capital and operating costs. Actual operating performance is also introduced. The comparison for the following mine sites provides a general reference for the selection of copper grinding circuits with this approximate throughput: Kamoa-Kakula Copper Mine with high-pressure grinding rollers with ball mill circuit, and Deziwa and Sicomine Copper-Cobalt Mines with semi-autogenous ball crusher circuits

Jan 1, 2023

By F. Chiesa

The permanent mould process, which is a favoured process for producing premium quality aluminium casting, is rarely used to produce magnesium alloy parts. This may be attributed different factors such as: the reservation with which the automotive industry considers using magnesium in structural castings; also the relative hot shortness of most magnesium alloys when compared to aluminium A356/357 is another factor. A third reason stems from the fact that the "heat content" of magnesium is much less than that of aluminium, resulting in the difficulty, for a relatively slow process such as permanent mould (versus pressure die casting), to reach a mould dynamic equilibrium temperature sufficiently high to avoid premature freezing and misruns. The present work will address this problem by carrying out controlled cycling of a laboratory mould, poured with aluminium and magnesium alloys. The influence of insulation of the mould and artificial electric heating on the run-in mould temperature will be determined experimentally. A thermal model will be sought for these thermal devices that will allow to predict the thermal behaviour of moulds of different geometry before a single casting is poured. The model will be tested on an industrial casting in a workshop environment.

Jan 1, 2006

By A. R. Farkoosh, K. Korgiopoulos, McGill University, O. Rodop, L. A. Villegas Armenta

"New generation of Al-Mg-Si alloys with thermally stable dispersoids that prevent recrystallization and grain growth during hot deformation are currently used in automotive components requiring good formability. Alloy chemistry controls the phase formation especially age-hardening precipitates, dispersoids, and primary intermetallic which have pronounced effect on grain structure, strength and formability. In this work, thermodynamic calculations have been used to predict the effects of varying levels of Si (0.5-1.5wt%), Mg (0.5-1.5wt%) and Mn (0.1-2.5wt%) on phase selection. Thermodynamic calculations have been performed in equilibrium and non-equilibrium conditions via the FactSage™ software using the FTlite database. Selected compositions have been cast, heat treated, extruded and characterized through scanning electron microscopy with energy dispersive spectroscopy and electron channeling contrast imaging techniques. The calculations showed that at the hot deformation temperature of ~540 oC, exceeding certain Mg and Si levels would lead to retained *-Mg2Si intermetallics and Si particles at the grain boundaries in addition to a-Al-(Mn,Fe)-Si. It was found that retained *-Mg2Si phase which adversely affects formability can be avoided for Si+2Mg levels lower than 2.3wt%. FactSage calculations also showed that increasing Mn from 0.5wt% to 1wt% leads to an increase in the amount of dispersoids (from 1wt% to 2wt%) that can potentially slow down recrystallization and grain growth during hot deformation and improve formability. Calculations at room temperature also show that for an alloy with 0.7wt% Mg, excess Si beyond 0.7 wt% promotes the precipitation of Si clusters in the Al matrix that accelerate natural age-hardening. Results were confirmed by experimental investigation.INTRODUCTIONAluminum alloy 6082 (Al-Mg-Si) is used in the automotive industry because of its high strength, and good weldability (I. J. Polmear, 2006). The alloy is age-hardenable through the precipitation of ß-Mg2Si and its precursors, and the recrystallization is usually inhibited by Mn- and Cr-containing dispersoids formed through high temperature heat treatments (I. Polmear & Couper, 1988). However, it is known that minor changes in alloy chemistry (Mg/Si ratio) can have significant influences on the ductility and formability of these alloys by altering phase selection and the resultant microstructure (Gupta, Lloyd, & Court, 2001; McQueen & Celliers, 1997; Zajac, Hutchinson, Johansson, & Gullman, 1994). For automotive applications where wrought alloys (usually extrusions) are cold-formed to produce suspension components, the chemistry of the alloys and the extruded structure are of crucial importance as they determine the formability at room temperature (Asensio-Lozano, Suárez-Peña, & Vander Voort, 2014). In this study, thermodynamic calculations along with experimental investigations were carried out on the Al-Mg-Si system to understand their phase formation and precipitation hardening as a function of alloy composition."

Jan 1, 2016

By George H. Holmes

This paper is one of a series being prepared by the Minerals Division of the Bureau of Mines on mining and milling methods and practices at various mines in the United States. It describes such methods at the Caselton mine of the Combined Metals Reduction Co. The Caselton mine and mill are in secs. 28 and 29, T. 1 N., R. 67 E., M. D. B. & M., Lincoln County, Nev., about 10 miles by paved highway south- west of Pioche, Nev. (fig. 1). the history of the district and company This circular summarizos operations, describes physical features, labor and living conditions, the geology, ore deposits, and the ore. Prospecting and exploration methods are outlined, and shaft sinking, drifting and crosscutting, and raising are covered under development methods. In the soction on mining mothods, stoping and slushing are discussed, following which are descriptions of underground transportation, hoisting, ventilation, drainage and sampling, and surveying. The surface and crushing plants are described, and milling practices are presented in dotail with explanation of the filter plant and assay office. Safoty practices and the company organization are described in the concluding sections of the circular.

Nov 1, 1950