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By Thomas P. Battle

Ilmenite (iron titanate) is the source of over 90% of all the titanium produced in the world today. At some point during production of titanium dioxide or titanium metal the iron impurity must be removed. Too often it becomes a waste instead of a product. DuPont and MINPRO have developed a solid-state process which separates the iron and titanium components of ilmenite into different high-purity powders, which can be separated using conventional mineral processing techniques. The main reactor in this process is a unique high-temperature ball mill, where the iron segregates from the ilmenite lattice with the assistance of catalytic quantities of He\. The results of lab, pilot plant, theoretical, and scale-up studies are presented and discussed.

Jan 1, 1996

By Richard P. Roberts

This paper will discuss the methods for the cooling of aluminum melting furnace? dross .and their impact on the environment. Also discussed will be a case history of an AROS Dross Processor installation, which is designed to maximize the recovery of metal content of the dross in a manner which is not only environmentally cleaner, but which also prepares the output in such a way as to facilitate downstream processes. Handling of the discharged material will be discussed in regards to the recycling of the preserved metal content and deposition of the unusable-materials.

Jan 1, 1992

By Isıl Kerti, Sibel Daglılar, Sinem Yıldırım

In this study, effect of rolling and coiling temperature in thermo mechanical controlled process (TMCP), on the microstructure and mechanical properties of dual phase (DP) steel according to martensite volume fraction (MVF) rate was investigated. By using various finishing mill exit temperature and cooling conditions that is controlled laminar cooling system, the microstructural evolution of coil improves the mechanical properties with lower costs and higher productivities, in comparison to the heat treatment after rolling. The main part of the paper contains the result of tensile, yield and microstructure properties of DP600 steel produced on hot strip rolling plant and run- out table line. The results show that a higher MVF and an increasing cooling rate after the last deformation raised strength of the DP600 steel. The yield strength and ultimate tensile strength increase by decreasing coiling temperature.

Jan 1, 2015

By Xuan Cheng

The electrochemistry of sulfide mineral flotation is reviewed with particular emphasis on galvanic interaction among minerals and grinding media, and its relevance to flotation of complex sulfide ores is discussed. Surface alteration due to galvanic interactions among chalcopyrite, pyrrhotite and mild steel is analyzed in terms of voltammetric and chronoamperometric studies on individual minerals and through galvanic current measurements in 2- and 3- electrode combinations. The results are related to laboratory flotation behaviors of chalcopyrite-pyrrhotite mixtures simulating copper-nickel bearing Duluth gabbro.

Jan 1, 1993

By John R. FitzPatrick

The separation and purification of uranium from either nitric acid or hydrochloric acid media tan be accomplished by using either solvent extraction or ion-exchange. Over the past two years at Los Alamos, emerging programs are focused on recapturing the expertise required to do limited, small-quantity processing of enriched uranium. During this period of time, we have been investigating ion-exchange as a method for extraction/purification of uranium from acidic media. In addition, waste stream polishing is associated with this effort in order to achieve more complete removal of the uranium prior to recycle of the acid. Extraction chromatography has been demonstrated' to further polish the uranium from both nitric and hydrochloric acid media thus allowing for a more complete recovery of the actinide material and creation of less waste during the processing steps. We will discuss contact experiments for evaluation of eleven different resins for uranium removal from nitric acid, the evaluation (again by contact experiments) of uranium elution from the ion-exchange media by various chemicals, and small-scale experiments for the removal of 235U from nitric acid. Larger-scale (100-gram) flow experiments using depleted uranium, were done after the small-scale evaluation Of the selected resin. A discussion is also included concerning the shortcomings of the contact experiments and how the flow experiments were modified in order to overcome these problems. We will also discuss the application of ion-exchange for some specific process needs at Los Alamos Contact experiments were used to evaluate some commercially available solvent-impregnated resins in addition to evaluation of several resins of this type synthesized in our laboratory. These experiments' involved both nitric and hydrochloric acid media. The data from these experiments will be used to determine the column size and' amount of resin required to polish the waste stream produced by the ion-exchange process described above. Small-scale flow experiments will be described and data given on the mass balances achieved using this two step process. Future work for evaluation of new ion-exchange and solvent-impregnated resins as well as the search for new eluants will be discussed. Other future experiments for both processes, including large-scale experiments, will be discussed in detail.

Jan 1, 1996

By George P. Demopoulos

In this paper the production and stability of crystalline scorodite (FeAsO4·2H2O) is discussed both on the basis of previously published work as well as recent work performed in our laboratory. The production of scorodite, especially from arsenic-rich and iron-deficient sulphate solutions offers a number of operational advantages such as high arsenic content, stoichiometriciron demand, and excellent dewatering characteristics. In addition to hydrothermal production of scorodite the work done over the last 10 years in our laboratory has determined that it is feasible to produce scorodite by step-wise lime neutralization at 90°C. The atmospheric scorodite possesses the same structural and solubility characteristics with the hydrothermally produced scorodite. Long term equilibration tests (up to 66 weeks) in the pH range 5 to 9 and temperatures from 22 °C to 75 °C revealed scorodite to undergo slow incongruent dissolutionyielding a highly metastable nano-sized 2-line ferrihydrite phase. The equilibrium arsenic concentration with this phase was 0.35, 0.96 and 5.87 mg/L at pH 5, 6, and 7 respectively at 22°C. In the presence of gypsum slightly lower concentrations were measured, this being more pronounced at pH>7. It was tentatively deduced that a Fe-Ca-AsO4 association (in the form of a phase resembling the mineral yukonite) contributes to the lowering of As concentration. Finally thermodynamic calculations determined that scorodite is stable in the presence of ferrihydriteunder oxic conditions up to pH 6.75 at 22 °C or higher pH at lower temperature and gypsum-saturated solutions. Keywords: Scorodite, Crystallization, Arsenic, Solubility, Stability, Precipitation, Disposal, Extraction, Processing, Metals, and Environment.

Jan 1, 2005

By P. Meyers, F. DeSilva, L. Gottlieb

A number of tests looking at lead removal using ion exchange resins of various types from various aqueous streams have been undertaken. The tests focused on strong acid cation (SAC) and weak acid cation 0N AC) resins. It was found that the mechanism of lead removal is partly by lead filtration rather than solely by ion exchange in a large portion of the applications studied. This is not surprising since lead carbonate is essentially insoluble and almost all water supplies contain at least some carbonate alkalinity. Regeneration of lead from exhausted resins containing significant amounts of lead may not be practical in some cases because of the large chemical and waste volumes involved. Since lead, .·along with many other very insoluble metals, is often present as a suspended solid rather than in ionic form, ion exchange is probably not always the best technology for bulk lead removal.

Jan 1, 2000

By S. Sundarraj

The morphological transition between columnar and equiaxed structures is an important solidification phenomenon frequently observed in castings, especially complex parts with varying cross-section, The mechanical properties and the occurrence of defects such as hot tears are strongly dependent on the structure formed in the casting. Hence, it is important to understand the conditions leading to columnar or equiaxed structures. Although extensive work has been done in modeling solidification systems, almost all of the existing models are based on the assumption that the structure formed in the casting is either purely columnar or purely equiaxed. Prediction of the columnar-equiaxed transition (CET) requires a solidification model which accounts for the formation of both columnar and equiaxed structures, along with related microscopic and macroscopic solidification phenomena. In this paper a CET model is presented which: (i) takes account of both columnar and equiaxed structures, (ii) accounts for macroscopic heat transfer coupled with microscopic phenomena such as nucleation, growth and microsegregation, (iii) satisfies solute conservation, and (iv) is easy to implement in commercial finite element and finite difference software. The proposed model predictions of CET have been validated with available experimental results for a uni-directional solidification of an aluminum-copper alloy. A sensitivity analysis has also been carried out to determine the effects of various parameters on the CET model predictions. The model is being extended to other alloy systems and more complex geometries. This work will be published in due course.

Jan 1, 1996

By Louis J. Mittoni

"It is well known that gas injection systems can exhibit a wide range of dynamical behaviours, ranging from linear periodic bubbling through to highly complex turbulent jetting. Recently, it has been observed that an important intermediate regime exists under certain system conditions, where the dynamics are complex in nature yet predictable for short time periods. This paper reviews the evidence to support the above hypothesis, and discusses the invariant quantitative measures such as density, return maps, Lyapunov exponent and dimension which may be used as pattern recognition features in a mOnitoring and control strategy.INTRODUCTIONThere has been a great deal of research on the submerged injection of gases into liquids. This interest is primarily due to the large number of applications in the pyrometallurgical and chemical engineering industries. Gases are typically injected into liquids to achieve goals such as heat and mass transfer, or physical mixing and agitation. Only recently though has the possibility of using the evolution of the gas dynamics as a probe to internal system conditions been raised [1, 2].At very low gas injection rates and small upstream chamber volumes, gas normally disperses in the form of stable bubbles of constant volume [3]. With increases in gas flow rate, the dynamics become more complex, bifurcating into double bubbling, multiple bubbling and complex coalescence behaviour. Irregularities measured in pressuretime series acquired upstream of the injection port under these complex conditions have usually been treated as bothersome noise or contamination to be filtered from the signal and ignored in the analysis. These irregularities, however, may contain physically interesting and useful information on the system from which they were produced if the system may be classified as deterministically chaotic [4]."

Jan 1, 1996

At its Copper Cliff Smelter, Inco Limited processes a bulk copper-nickel concentrate in two Inco oxygen flash furnaces. The furnace matte is converted to low iron matte for further processing, and the molten converter slag is recycled to the flash furnaces. The flash furnace slag is discarded. Natural gas or coke supplies a minor proportion of the process heat requirements, thus limiting the flash furnace matte grade to the target 45% CuNiCo. Coke addition to the furnace offers a potential means of establishing a reducing barrier on the surface of the molten bath. Such a practice would be conducive to producing sulfur deficient (partially metallized) matte. At the same iron content, the iron activity of sulfur deficient matte is higher than that of regular matte. A supernatant coke barrier could, therefore, be expected to lead to higher nickel and cobalt recoveries, reduction or even elimination of magnetite furnace bottom build-up and increased sulfur elimination as SO2 in the flash furnace. Preliminary experiments were conducted in a mini plant flash furnace to investigate the effect on process metallurgy of the suggested modified scheme. This paper presents the experimental results and discusses key aspects of the possible operation of the Inco flash furnace with a coke barrier separating the freeboard from the molten bath.

Jan 1, 2003

By Katri Avarmaa

Aluminum and copper are large volume metals in electronic appliances, while tin and indium exist as common minor elements. All of these non-ferrous metals are aimed to be separated and recycled from the end-of-life electronics into non-ferrous scrap fraction(s), and further through pyrometallurgical and/or hydrometallurgical processes to pure metals. Depending on the mechanical pre-treatment processes, aluminum and copper liberation from each other varies. This study focuses on the influence of alumina on indium and tin distributions between copper alloy and iron silicate slags with 0, 9 and ∼16 wt% of Al2O3. The experiments were executed with an equilibration-quenching-EPMA technique in an oxygen pressure range of 10−10–10−5 atm at 1300 °C. The metal-slag distribution coefficient of indium remains constant as a function of alumina in slag, while that of tin increases. Therefore, aluminum in feed or alumina addition to the slag improves the recovery of tin into copper. Nevertheless, oxygen pressure has clearly more significant influence on the behavior of both the metals in the smelting conditions.

By B. Garcia-Egocheaga, J. Rutten, N. Goicoechea, U. Meurer, Mager K., W. Saage, Simonettim F.

Because of the increasing use of zinc as an active and passive anticorrosion agent for steel, leading to constantly growing return rates of galvanized steel components, especially through the automotive industry, major Electric Arc Furnace (EAF) flue dust amounts with higher zinc contents will accumulate in future. Landfilling of steel plant flue dusts is no longer allowable for ecological reasons. These dusts are classified as hazardous by law. Waelz technology is safe and reliable. The range .of treatable feed materials has been extended by process modifications and state-of-the-art offgas technology. Waelz oxide, the product, is delivered to metal smelters for zinc production and the byproduct, Waelz slag, can be used in road construction. Despite the fact that Waelz technology is among the best available techniques (BAT), it is continuously being optimized further with respect to energy input, product and offgas quality in order to comply with the ever more stringent environmental regulations. However, if these flue-dusts are treated, the loops between the steel and the zinc industry can be closed by reusing recovered zinc which in tum leads to savings in natural resources and a more reasonable use of landfills.

Jan 1, 2000

By C. M. Iheagwara

An overview of the scope and ramifications of scrap recycling in the Nigerian metallurgical industries has been presented in this paper. The modern state-of-the-art processing techniques and the operational strategies employed in the recycling plants are discussed. Optimization techniques for cost effective recycling operations are highlighted. As new units within existing metallurgical plants and new metal working plants approach commercial operations, expansion of existing recycling plants and the emergence of new ones have been showing to hold the key to their profitability from the raw material standpoint. The present economic predicament of the entire industrial sub-sector, lack of sufficient foreign exchange to procure new machineries and the emergence of a maintenance culture have triggered a phenomenal increase in the number of spin-off industries which depend on metal recycling activities. This, it is argued, widens the horizon for scrap processing/recycling.

Jan 1, 1992

By Jr. Langhans, J. S. McPartland

"The presence of zinc in cyanide solutions is generally thought to not have an adverse effect on precious metal recovery or recovery rate by heap leach processing. However, analytical interferences of zinc in solution can cause problems in accurately determining and controlling cyanide concentration in the leach solution, leading to increased cyanide consumption. Analytical methods and the chemistry of cyanide in the presence of zinc are reviewed. The effects of solution pH and zinc concentration on the free cyanide determination were evaluated in detail. Use of the standard silver nitrate titration and a modified titration method for controlling cyanide concentration during heap leaching were investigated experimentally. The practical implications of cyanide heap leaching in the presence of cyanide soluble zinc minerals are discussed.IntroductionThe presence of zinc in precious metal cyanidation circuits is not uncommon. Zinc can be introduced into cyanide leach solutions through dissolution of various zinc minerals1>, or through the use of a Merrill Crowe (zinc precipitation) circuit. Zinc minerals typically occur infrequently and in low concentration in gold ores, but are more abundant in silver ores. Merrill Crowe systems are most commonly employed for recovery of precious metals from solution for relatively high silver ores. It is desirable to control the amount of dissolved zinc in a cyanidation circuit for several reasons. Excessive zinc build-up in cyanide leach solution can, under certain circumstances, inhibit precious metal dissolution and adversely affect solution recovery systems. Additionally, high zinc concentrations can lead to excessive in-process cyanide inventories and potentially, to higher cyanide consumption"

Jan 1, 1999

By S. Kang, D. G. C. Robertson

Slag cleaning furnaces require extensive wall cooling because they involve the use of a superheated slag bath. This is in direct contrast to smelting furnaces, where the wall is usually (but not always) protected by "banks" of solid charge. In order to understand the heat transfer and flow in slag cleaning furnaces a number of model studies have been carried out using molten wax to simulate the slag. Wax is a good model fluid because, like slag, it has a high Prandtl number. Wax models cannot simulate the behavior close to the electrodes (DC arc or AC submerged), but they can and do give a good simulation of the flow and heat transfer at the wall. An understanding of these phenomena is of great importance for the design of cooling panels in the walls of the furnace. Since superheated molten slag will eventually wear away any refractory bricks over time, the wall cooling must be designed to form a frozen layer of slag, referred to as a "freeze lining". The heat flux density (Q/A) required to do this is given by Q/A = h* ?T, where h is the heat transfer coefficient in the slag phase at the wall, and Li T is the superheat (bulk slag temperature - liquidus temperature). Both Q/A and h vary greatly with position and both are usually a maximum at the slag line. In the experimental work, molten wax baths were heated by block heaters to provide similar energy densities to those encountered in commercial slag cleaning furnaces. This procedure was considered to be valid since most of the electrical energy into a furnace bath is dissipated as heat. Gas stirring was used to simulate the gas evolved at the electrode in real furnaces - the quantity of this gas could be estimated from a knowledge of electrode consumption. The similarity criterion was equal gas flow per unit area of surface, in model and prototype. Heat transfer coefficients were measured in the models as a function of power density, gas stirring, superheat, etc., and could be related to the full-scale operations by the use of dimensional analysis.

Jan 1, 1999

By C. Isaac Garcia, Sihai Jiao, Anthony J. DeArdo

"A practical model based on the Hill analysis has been developed to calculate the Lankford value of interstitial free (IF) steels and its distribution in different rolling directions, by considering only a few selected texture components. The Texture Intensity Ratio (TIR), i.e. (111 ) /(100), was used in the model to describe texture. By using the new TIR parameter, the texture-based prediction models can be used more easily to predict the Lankford value in a rather straightforward way.IntroductionThe deep drawing capacity of sheet steels is generally indicated by the Lankford value, which is mainly determined by the texture in steels1. Traditionally, various models derived from the Taylor model are employed to calculate the Lankford value from the texture2-4. In such models, the plastic deformation of steel is assumed to be the result of the slip of dislocations in certain slip systems, i.e., by either pencil glide or restraint glide. The slip direction is the <111> direction. In the case of pencil glide, the slip is thought to be possible in all crystal planes with the <111> crystal direction. Assuming the material is elongated in the X1-direction by d n and compressed in the X2 and x3-direction by qd n and (l-q)d n, respectively, corresponding to a deformation tensor"

Jan 1, 2001

By Sevinc Yildirim, Cigdem Oruclus

"Metal-Porous Silicon (PS) based structures dipped in water show the direct hydrogen fuel cell behavior. The effect of the thickness of the cupper (Cu) film on the electrical properties of direct hydrogen fuel cell is studied by fabricating Cu/Porous Silicon/n-Silicon/Indium structures. PS samples were produced electrochemical etching of n-type single crystalline silicon with a resistivity of 1,25 Ocm and (111) orientation. The thin films of Cu with different thickness between 200 and 600 nm were deposited on PS surface by electron-beam technique. Investigation of the effect of Cu layer on the performance of the structure indicates that the performance parameters such as open circuit voltage (Voc) and short circuit current (Isc) strongly depend on the Cu layer thickness. It was observed that the divice with an 350 nm Cu layer exhibits the highest open circuit voltage (0,5 V), short circuit current (0,01 mA) and power density (10 W.m-2).IntroductionHydrogen is the most attractive and ultimate candidate for a future fuel and an energy carrier. Hydrogen is recognized as the environmentally desirable clean fuel of the future since it can be used directly in different types of hydrogen fuel cells [1]. In the past years, the rise in portable electronics requires the development of miniature fuel cells compatible with standard silicon micro fabrication technology. Most silicon micro-fuel cells have used the polyperfluo-rosulfonic acid membranes (Nafion R) as a proton exchange membranes (PEM) that is not really integrated with standard micro fabrication techniques [2-5]. The composite materials such as inorganicorganic hybrid materials (Nafion-silica, Nafion-borosiloxane etc) are next generation of proton conducting membrane [4-8]. But, fuel cells run on pure hydrogen gas, which can be produced with other energy resources. Hydrogen smallest atom and thus the H2 gas can leak easiliy. The application of hydrogen for power sources has been greatly restrained due to the lack of safe and convenient generation and storage methods.A kind of hydrogen fuel cells Metal-PS-Si structures used as an energy water directly. There is no need pure hydrogen. Cu-PS-Si Schottky-type fuel cells with as proton-conducting membrane and the thin-film cupper catalist and water as fuel, which are interesting for fabrication of lowcost miniature fuel cells. Generation of the open-circuit voltage and short-circuit current has been observed by Cu-PS-Si structure dipping in different hydrogen-containing solution."

Jan 1, 2014

By Y. Wang, L. Liu, G. Xu, Y. Lv J. Sheng H. Zhang

In order to increase the service life of large scale coke dry quenching furnaces, the damage mechanism of lining was investigated, and the structure and properties of lining refractories used in cooling section were researched. The results showed that the abrasive wear volume of lining bricks at one fourth height section under skew tunnel was smaller than other sections. The wear loss of mullite brick and dense clay brick used in the lining of cooling section were respectively 8.02 cm3 and 11.65 cm3 in fifteen minutes. The mullite brick was laid with clay brick alternatively. By the different wear rate, the surface of lining was rough and uneven in the later service life, and short brick was easily dropped from lining. During the service, the basis wore off more easily than the aggregate. It is necessary to improve the wear resistance property, which will increase the service life of cooling section’s lining for coke dry quenching furnaces.

Jan 1, 2016

By Lei Wang, Jianjun Wang, Lingen Luo, Zhengbang Li

Dearsenication in molten steel was studied by adding Ca-Fe Alloy-based arsenic removal agent. In order to improve the utilization rate of Calcium Iron Alloy and improve arsenic removal ratio, [O] is less than 0.0005% and [S] is less than 0.0035%, Al is added into the molten steel. In the processes of adding CaO-Al2O3 based alkalinity slag for arsenic removing in molten steel (initial arsenic content is 0.0080%), arsenic removal ratio reaches 50% when Ca-Fe Alloy addition amount is 18%. During the arsenic removal experiment, adding Rare Earth promotes the arsenic removal reaction and makes the arsenic removal more effectively.

Jan 1, 2015

By C. Takano

The integrated iron and steelmaking industry generates large amounts and many types of solid dusts and sludge, at different phases of the production. Within these are: sludge of the Blast Furnace; coke fines; fine and coarse fractions from oxygen converters; sludge from water treatment at rolling mill unit; and others. In this paper the above dusts and sludge were physically and chemically characterized. The obtained results allowed defining self-reducing pellets using these materials. The high temperature behavior of the pellets were evaluated. Good results, with no decrepitation and swelling, and high yield of reduction, show that it is feasible to recycle them, as self-reducing pellets, in oxygen steelmaking converter.

Jan 1, 2001