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By A. S. Usmani

The flow associated with the pouring of molten metal into moulds has been modelled on the basis of certain simplifying assumptions. A finite element based Navier-Stokes equation solver has been used to analyse the flow. The velocities obtained from the Navier-Stokes equation solver are used to advect a pseudo-concentration function for modelling the fluid front. A simple problem with a known analytical solution is solved first to test the model. Subsequently, several more examples with varied geometrical configurations are modelled, including one with curved flow boundaries.

Jan 1, 1992

By Youliang He

Twin-roll casting is an integrated casting and rolling process that involves the continuous solidification of a melt and the plastic deformation of the solidified metal between two rotating rolls. Computer modeling is a valuable tool to help engineers understand the metallurgical process during twin-roll casting. However, commercially available software can only model either the fluid flow/heat transfer of the melt or the plastic deformation of the solid, but not both. In this study, an object-oriented finite element program was developed to simulate the steady-state fluid flow, solidification and plastic deformation of an A7,31 magnesium alloy in a horizontal twin-roll caster. The melt, the mush zone and the solid were treated as a generalized Newtonian flow in an Eulerian reference frame and different constitutive equations were employed to describe the material behaviours. The effect of operational parameters on the solidification process was discussed based on the simulation results.

Jan 1, 2010

By A. F. Giamei, F. Landis, M. O. Duffy, R. J. Mador

"The directional solidification of complex advanced gas turbine airfoils must be carried out without the nucleation of undesirable grains and with minimal shrinkage. Such problems are typically eliminated by using a number of mold design and process iterations. A more efficient approach is envisioned where a solidification model is generated and utilized to accelerate process development. Towards this end, the directional solidification (DS) of simple geometrical shapes in a crystal grower apparatus has been simulated with MARC finite element nonlinear thermal analyses.The finite element models of cylindrical (2D) and rectangular (3D) cross-section bars in the DS environment are presented. Temperature dependent properties, the impact of latent heat of fusion and a time-dependent radiation boundary condition constitute the more salient features of the MARC models. Solidification zone thermal behavior is predicted during the withdrawal transient for the specific case of nickel based superalloys grown in ceramic shell molds. Comparisons of analytical results with experiments demonstrate notable prediction accuracy. INTRODUCTIONSingle crystal and uni-directional crystal turbine blades require tightly controlled conditions if metallurgically and mechanically acceptable parts are to be produced. Gated blade geometry and process parameters must be precisely determined if incorrect grain structure, orientation and shrinkage are to be avoided. Since purely experimental development programs designed to evaluate these parameters can be excessively costly and time-consuming, an effort combining engineering analysis and verification by experiment has been initiated at Pratt & Whitney. Comparison of analytical predictions and measured data for geometries simpler than a turbine blade, namely cylindrical and rectangular bars, comprised the initial stage of this effort. Subsequent tasks involve modeling geometries of increasing complexity and ultimately the simulation of the directional solidification of the turbine blade, shown schematically in Figure 1. This paper summarizes the results of the initial stage of the effort."

Jan 1, 1986

By U .. C. Rojas, J .. C. Gomez

"Fire Refined Copper (EI Teniente Three Stars) has been produced at Caletones Smelter of Codelco Chile since almost the beginning of its operations.Due to changing features of the copper market, together with the targets on technical efficiency and productivity, it has become more and more relevant for copper industry to reach both, good final product quality and a proper environmental control.At present, copper refining process at Caletones Smelter takes place in two cylindrical tilting furnaces, where solid fluxes are injected through horizontal tuyeres into the molten bath. (Fig. N2 1)Solid reagents are pneumatically conveyed and injected into the liquid copper bath attaining excellent solid - liquid contact, so the impurities removal efficiencies are found to be high. Same injection tuyeres are used to introduce both oxidising agent (normal air) and reducing agent (reformed gas) into the molten bath. Air or nitrogen is used as conveying gas for solid reagents, depending on the process stage.This pap~r gives a fundamental description of the process and industrial results related to the injection of blend of sodium and calcium carbonates to remove arsenic and antimony, silica and granulated reverberatory slag to remove lead and a mixture of calcium carbonate and mineral coal to reduce the selenium content of the fire refined copper."

Jan 1, 1996

By A. Korbel

The progress in understanding the nature of strain localization in metallic materials and in particular the understanding of the role of external (deformation conditions) and internal (material substructure) factors in the development of the tendency toward concentration of plastic flow within transgranular shear bands was the background of the concept given in the title. Following this idea, the practical possibility of replacing the homogeneous in a micro scale mode of deformation by transgrasnular shear bands gives a chance to change the arrangement of the dislocation substructure in the material from that typical for homogeneous deformation into long wavelength (transgranular), pseudo-periodic dislocation walls. The presence or formation of such a substructure in a thermodynamically unstable matrix may result in the formation of the products of phase transformation along shear bands, giving rise to a composite-like structure. This work is aimed to provide a coherent justification to the concept of Natural-Metal-Matrix Composite and summarizes the results of experimental works in this area.

Jan 1, 1997

By Y. Prévost

The Noranda Continuous Converting Process was commissioned in November 1997 at the Home smelter in Rouyn-Noranda, Quebec, Canada. It has completed over 18 months of successful operation. Excellent team work and technical expertise contributed to achieve targeted production levels and environmental goals after only a few months of operation. The operating results have demonstrated the flexibility of the process in producing blister copper from a variety of copper feed materials including a combination of molten and solid copper matte, reverts and fluxes. This paper describes the startup activities and process optimization tasks performed during the first year of operation of the new Noranda Converter.

Jan 1, 1999

By C. Pereira

Spent nuclear fuel (SNF) can be treated in a molten salt electro refiner for conversion into metal and mineral waste fonns for geologic disposal. The fuel is dissolved in molten chloride salt. Non-transuranic fission products in the molten salt are ion-exchanged into zeolite A, which is subsequently mixed with glass and consolidated. Zeolite was found to be effective in removing fission product cations from the molten salt. Breakthrough of cesium and the alkaline earths occurred more rapidly than was observed for the rare earths. The effluent composition as a function of time is presented, as well as results for the distribution of fission products along the length of the column. Effects of temperature and salt flow rate are also discussed.

Jan 1, 1996

By David Bequette, Ray D. Peterson, Cynthia K. Belt

"With a need to cut production costs in the metals industry, cost savings from energy efficiency improvements are critical. Opportunities can be found by reviewing furnace systems and practices so that the melting and holding processes operate at the highest energy efficiency. Many of the changes can be implemented with a minimum of expense or capital investment. This paper will review several low cost methods to optimize energy efficiency on reverberatory melting or holding furnaces. These five methods (furnace utilization, idle procedures, fire rate, controls, furnace pressure) will be explained and information given to implement these changes. Included are several rules-of-thumb and benchmarks for aluminum reverb furnaces.IntroductionEnergy can be a significant portion of the total manufacturing costs for metals and materials manufacturing involving thermal processing such as heat treating, melting, and high temperature processing. Natural gas prices have dramatically varied over the last few years. While no one can foresee the future, prices are expected to increase from the current low prices. More recently, emphasis is being put on the reduction of greenhouse gases with the potential of additional costs to industry.One of the first steps in an energy management program is to measure the energy usage of the process [1]. The results are typically understood in relation to the mass melted in kWh / mT [BTU / lb]. For the purposes of this paper, furnace energy efficiency is calculated over a month or even a year and thus includes hold times. This efficiency is typically different from the values quoted by furnace manufacturers. Those values are for limited short term tests at highutilization.Once you know the performance for your furnaces, these should be compared to industry benchmarks. For aluminum melt furnaces with cold air burner systems, a benchmark value or goal is 1800-2000 BTU/lb [1160-1290 kWh/mt], though some of the best have reached 1600 BTU/lb [1030 kWh/mt]. Furnaces with regenerative burners can attain 1100-1200 BTU/lb [710- 775 kWh/mt]. There are some designs of multi-chamber furnaces or oxygen furnaces that have improved on these numbers, perhaps as low as 950 BTU/lb [615 kWh/mt]. Typically, as the degree of sophistication and energy efficiency of the furnace increases, so does the cost."

Jan 1, 2010

By Serge Lavoie

Alcan's Guillaume-Tremblay plant, located in Jonquiere, Quebec, has been in operation since 1990. This was the first plasma dross processing plant ever built. In addition to the use of the plasma heating technology, Guillaume-Tremblay has other unique features making it a modern and efficient dross processing facility. This paper presents a general overview of the practical experience at the Guillaume-Tremblay plant. In particular, the utilization of plasma heating in industrial conditions, the metallurgical performance, the unique dross handling system, the control and information management system and the reclaiming of the by-products will be discussed. Finally, the use of the plasma process for salty dross will be addressed' briefly.

Jan 1, 1995

By J. W. Matousek

In the flash smelting of copper sulfide concentrates, the course of reactions from the burner tip, through flame "burn-out" (the point of oxygen depletion), to settled matte and slag is of particular interest in understanding the mechanisms of the process. Numerous reaction sets can be proposed to describe the chemical changes that might be taking place, but from outside the furnace no one set offers an obvious advantage in explaining the actual processes involved. Only a combination of mathematical modeling and flame and bath sampling can achieve this result. This paper shows that flash smelting, while still reasonably orderly, is a more complex process than suggested by the technical literature.

Jan 1, 1993

By M. A. Llavona

In Spain, as in many countries, the gold content of jewellery must be officially hallmarked. The official methods of assay are gravimetnc cupellation (a method which is highly accurate but both time and sample consuming), potentiometry, gravimetry and volumetry. In this paper, a procedure for measuring gold by flame atomic absorption in jewellery samples is described. The method is based on the acid digestion of a 40 mg sample. The quantity of aqua regia necessary for dissolving the gold, the ideal weight of a sample in order that the error may be minimal, the effect of the acids employed, the type of material used for its storage, and the necessity of employing a buffer to avoid the ionization of the solution are described. The method proposed is simple, highly accurate and causes little damage to the jewellery.

Jan 1, 1999

By W. G. Davenport

The flash furnace is used for smelting concentrate to (i) high-Cu matte and (ii) molten metallic copper. It is also used for converting solidified/crushed matte to molten metallic copper. This is flash converting. It consists (Table 20.1, Fig. 20.1) of: (a)tapping molten 65 to 72% Cu matte from a flash smelting furnace (b) granulating the molten matte to ?1/2 mm particles in a 103 m3/hour water torrent (c) crushing the granulated matte to 50 µm in a vertical roller mill (d)drying the crushed matte (e) feeding the dry particulate matte to a second flash furnace for oxidation converting to molten copper. In 2000, flash converting is being used by Kennecott Utah Copper (George, et al; 1995; Newman et al, 1998, 1999a,b). A second installation is being designed for the Chuquicamata smelter (www.outokumpu.com [October 12, 2000]), The potential uses of flash converting are: (a) as the second half of a flash smelting/flash converting coppermaking sequence (b) as a continuous converting alternative to batch submerged tuyere converting. This chapter uses our flash furnace matrix to determine the %O2-in-blast, industrial oxygen and oil requirements for converting solidified 65% and 72% Cu matte to molten copper. It then discusses choice of feed matte grade and other aspects of the process.

Jan 1, 2001

In the new flowsheet for Inco Limited's S02, Abatement Project at the Copper Cliff, Ontario operations, a copper/nickel sulphide flotation concentrate will be flash smelted, then converted to Bessemer matte. As in current practice, this will be slow-cooled and separated into components by magnetic separation and flotation. The copper content will emerge as a chalcocite concentrate (impure Cu2S), containing some nickel. This copper sulphide will be converted to copper metal.

Jan 1, 1993

By Elli Miettinen, Markku Lahtinen, Ilkka Kojo

"The recent trends of decreasing energy consumption and environmental emissions and utilization of economies of scale are strong drivers favoring continuous copper converting processes. Flash Converting benefits from low off-gas volumes and low investment and operational costs for off-gas treatment. Separate matte and blister furnaces allow the adaptation to concentrate quality changes and flexibility in layout and maintenance.The stationary blister copper bath in Flash Converting furnace is less aggressive to the furnace linings than agitated processes, resulting in low refractory consumption, long campaign life and high on-line availability.Copper Flash Converting has been successfully applied in Kennecott with a campaign life now exceeding five years. A second FCF was started at Xiangguang Copper in China in 2007. The process itself is proven, as its features are similar to those in FSF, Direct-to-Blister and Direct Outotec Nickel Flash Smelting (DON), with one significant difference: it is the easiest of all to operate.The paper presents differences between continuous Flash Converting and conventional converting based on recent experiences and studies."

Jan 1, 2009

By W. G. Davenport

This chapter demonstrates how our matrices can be used for controlling a flash furnace. Specifically, it shows how we can determine the adjustments in industrial oxygen, air, oil and flux input rates that will; (a) correctly alter product temperatures and compositions to newly targeted values (b), maintain set-point product temperatures and compositions with varying feed compositions and feed rates. It also discusses corrective actions that might be taken when furnace temperature and matte grade unexpectedly change.

Jan 1, 2001

By W. G. Davenport

A flash furnace can be run many different ways. It can, for example, be operated with: (a) highly 02"enriched, ambient temperature blast and no fossil fuel (b) considerable fossil fuel and hot, slightly Or enriched blast. It can also produce different grades of matte. With all these possibilities, the flash furnace operator can benefit from any technique that will indicate the 'best' way to operate his furnace. One such technique is Excel's 'Solver'optimizationroutine#. This chapter shows how our matrices and Excers optimization.abllity can be used to optimize a flash furnace operation. The chapter sets three optimization goals: (a) minimum industrial oxygen + oil cost, $ per tonne of concentrate (b) maximum smelting rate, tonnes of concentrate per hour (c) maximum profit, $ per hour.

Jan 1, 2001

By Nickolas J. Themelis

The flash oxidation and smelting of mineral sulfides is a very prominent metallurgical achievement of the second part of this century. Its initial industrial implementation owes much to the work of Petri Bryk, in Finland, and Paul Queneau, in Canada. However, attempts to develop flash reduction pro- cesses, such as the reduction of iron oxide concentrates with hydrogen, have not yet been successful. The author, on the basis of experimental studies on both kinds of flash reaction systems, examines the respective rate controlling phenomena and the relative rates of flash oxidation and flash reduction.

Jan 1, 1993

By Yousef Mohassab, Hong Yong Sohn, Mohamed Elzohiery

As part of the development of a novel flash ironmaking process at the University of Utah, a labscale flash reactor was used to produce iron directly from iron oxide concentrate. This work tested the feasibility of the novel flash ironmaking process using the partial combustion of hydrogen as fuel and reductant. In this flash reactor, the energy required to reduce concentrate particles was obtained from the internal combustion of hydrogen and oxygen with complementary energy from electrical resistance heating to compensate for the heat loss. After the reaction shaft was electrically pre-heated, hydrogen and oxygen streams produced a non-premixed flame inside the reaction shaft. Various conditions such as flame configuration, flame power, positions of concentrate feeding ports, excess hydrogen amount and residence time were tested. More than 90% reduction of magnetite or hematite was achieved at temperatures as low as 1175 oC with < 100% excess hydrogen in <10 s of residence time.

Jan 1, 2016

By C. E. Dodson

Conventionally hydrometallurgical recovery processes from sulphide concentrates include roasting, leaching, precipitation, impurity removal and zinc electrowinning. The use of the novel (yet commercially proven in other mineral and metallurgical industries) TORBED process reactor for the flash roasting of sulphides will be proposed. The potential advantages in its application will be discussed including very fine particle processing capability, lower cost smaller roasters, waste minimization, improved leaching efficiency and overall process simplification.

Jan 1, 1999

By W. G. Davenport

Flash smelting is used. mainly for making molten Cu-rich matte* from fine Cu-Fe-S** flotation concentrates. It blows dried concentrate particles into a hot fumace, surrounds them with 01-rich gas and allows them to react. The results are: (a) partial oxidation of Fe and S from the concentrate (b) generation of heat (c) melting of the oxidized particles to form molten Cu-rich matte, ~65% Cu and Cu-barren slag, ~1 % Cu. The melted particles fall to the hearth of the flash furnace where they fonn matte and slag layers, The matte is tapped from the furnace and oxidation-converted to metallic copper. The slag is skimmed, treated for Cu recovery then stockpiled or sold. Figures 1.1 and 1.2 show industrial flash furnaces and the position of flash smelting in the coppermaking flowsheet. ,Fig. 1.3 shows the locations of flash furnaces around the world.

Jan 1, 2001