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By A. D. Zunkel

Increasing amounts of electric arc furnace dust (EAFD) are being generated worldwide as more steel is produced from electric furnace melting of galvanized steel scrap. In most countries, the management of this material is a costly technical, economic, and legal problem for minimill steelmakers. Many technologies and processes are being developed and implemented worldwide to manage this material to recover contained zinc, lead, and iron values and render it nonhazardous. These processes are pyrometallurgical, hydrometallurgical, or hybrid in nature. Some produce zinc oxide, some zinc metal, some lead metal, and some lead cement. Some are successful, some have failed, many are dormant. or abandoned, and others continue to be developed and emerge. This paper updates the current status of 20-30 processes in various stages of commercial application and development used worldwide to manage EAFD and recover its nonferrous, particularly zinc and lead, and ferrous values.

Jan 1, 2000

By Fujio Ishii

The deoxidation of liquid nickel and nickel binary alloys with silicon has been determined at temperatures between 1500°C and 1650°C using quartz crucibles in order to investigate the deoxidation of nickel based alloys. The equilibrium constant of the deoxidation reaction in liquid nickel and the effects of the different alloying elements such as chromium, molybdenum, tungsten, iron, cobalt and coppcr on the activity coefficient of oxygen in liquid nickel have been established.

Jan 1, 1993

By A. J. Schindler, F-P Sawyer, T. Logan, M. L. Shutey-McCann, R. M. Perry

"Test work on biooxidation pretreatment of low-grade refractory gold ores has been ongoing at Newmont Gold Company since 1988, including laboratory testing and pilot biooxidation heaps (360 to 23,000 tonne). Metallurgical results of the biooxidation process utilizing Thiobacillus ferrooxidans (T. ferrooxiddans) have culminated in the design, construction, and operation of a biooxidation demonstration facility. The facility has processed 708,000 tonnes of refractory ore, using a batched process with separate pads for biooxidation and ammonium thiosulfate gold extraction. Siliceous sulfidic refractory (SSR) and carbonaceous sulfidic refractory (CSR) ores are treated separately during biooxidation pretreatment unit operation. Following biooxidation, the ores are neutralization with lime and placed on oxide leach pads or stacked on the ammonium thiosulfate leach pad. Gold is leached with either cyanide for SSR ores or ammonium thiosulfate for preg-robbing CSR ores.This paper will only address the biooxidation pretreatment process of the SSR and CSR ores.AcknowledgmentsThe authors appreciate the cooperation and approval of Newmont Gold Company Carlin Operations management for its support and permission to publish this paper. The paper draws on efforts and assistance of the following people and several others which are to many to list who participated over the past five years in bringing this project to its fruition: Dr. James A. Brierley, Chief Microbiologist, Newmont Metallurgical Services; Dr. Rong-Yu Wan, Metallurgical Manager, Newmont Metallurgical Services."

Jan 1, 1997

By Xiang Lan

A strain of Thiobacillus ferruuxidans No. 8 was isolated from the acidic mine water of an arsenopyrite deposit, South China. It has been found from the experimental results that the growth of bacteria was inhibited by flotation agents. The order of toxic effect of different flotation agents on the growth of Thiobacillus ferrooxidans is ethyl xanthate > butyat ammonium aerofloat > butyl xanthate ? isobutyt xauthate >? flother No. 2 oil. The bioteaching treatment of arsenic and antimony-bearing gold concentrate in Longshan mine, Hunan province, China, was influenced considerably by the presence of flotation agents. The possible causes of the influence of flotation agents were discussed and an improved method was suggested.

Jan 1, 1991

By C. J. Beyke

In recent years recycling of household batteries has received increasing attention, primarily for environmental reasons. This article reviews the major battery types and some of the technologies available to recycle them. It also discusses issues such as collection and sorting which are related to battery recycling in the United States. Finally, results from research being conducted by the U.S. Bureau of Mines on the reclamation of nickel-metal hydride, alkaline, and zinc-carbon batteries are presented.

Jan 1, 1995

By H. Shang

The materials science and metallurgical engineering communities have expended enonnous resources in developing high fidelity process models. Exploiting these Models for Predictive Optimization (MPO) and Control (MPC) is a new frontier in Materials Process Engineering that will lead to exceptional process perfonnance. This paper will begin with a short survey of the development of high quality process models available in the literature and a discussion of how these could be used to improve process operation. A summary of the current "state-of-the-art" in process automation technologies and the traditional framework in which these technologies are deployed will be presented. An illustration of the use of MPO in process design and operations will be presented for the continuous casting of steel. In addition, a simple run-out table simulation will be used to demonstrate the power of the MPC technique.

Jan 1, 2003

By Zeyun Cai, Gaoyang Song, Bo Song, Yuhou Yang

In this research, super gravity field was introduced in the solidification process of high carbon steel. The experimental results show that the solidification structure of Fe–1 wt% C steel can be largely refined by applying super gravity at the cooling rate of 10 °C/min. Both the primary and secondary dendrite length was markedly reduced. In addition, the eutectic structure in the inter-dendrite was also refined with the obvious reduce of eutectic space. However, the macro-segregation of C along the direction of super gravity was caused with higher weight percent at the upper area than that at the bottom of the sample. The mechanism of solidification structure refinement and the C macro-segregation of Fe–1 wt% C steel in super gravity field were also discussed in this paper.

Mar 1, 2017

By Xiaodi Huang, Matthew Andriese, Zheng Zhang, Jiann-Yang Hwang, Zhiwei Peng

"A simplified finite-difference time-domain (FDTD) algorithm for modeling microwave propagation in magnetic dielectric materials was developed and employed to study the microwave dissipation in magnetite. Heat transfer during microwave heating of magnetite was subsequently investigated by solving heat transfer differential equation using explicit finite-difference (EFD) method. It is observed that temperature of magnetite surface increases rapidly in the first minute due to the rapid strength decays in both electric and magnetic fields within a short distance along the path of microwave dissipation. A temperature peak, initially formed at the surface of the sample slab, migrates inward as heating time extends and microwave power increases.IntroductionAs one of primary materials in iron and steel industry, magnetite exhibits excellent microwave absorption capability, which leads to great energy conservation in microwave assisted steelmaking [1,2]. The fast temperature increase in microwave heating of magnetite can be attributed to both dielectric and magnetic losses [2]. Although much experimental work has confirmed this observation, detailed computational studies for modeling of microwave field dissipation in magnetite at commonly used frequencies, such as 915 MHz, has not been well addressed [1,3].Finite-difference time-domain (FDTD) method is widely used in computational electrodynamics modeling to simulate the dynamics of electromagnetic wave scattering from various media [4,5]. This approach requires modeling algorithm to be formulated with integration of specific characteristics of each medium. An extensive literature survey indicates that current formulations are only suitable for modeling electromagnetic waves propagating in normal dielectric lossy materials [5,6]. Since magnetite is a magnetic dielectric material in which both dielectric and magnetic properties contribute to the heating process under microwave irradiation, a specific algorithm should be developed for the simulation."

Jan 1, 2012

By Jin Yu, Fang-Qiu Zu, Yun Xi, Li-Na Mao

"According to the behaviors of resistivity-temperature of Cu-Sb70 melt, which suggests a partly reversible temperature-induced liquid structure transitions (LST) could occur in this alloy, in this paper, we investigated the dependence of solidification on the liquid state. Both resistivity and temperature were measured to track solidification process. The results show that the nucleating undercooling of the melt which experienced the LST increased and the solidified time decreased. Meanwhile, the solidified microstructures refined evidently, with the microscopic pattern of primary phase changes from disordered pillarlike dendrites into homotaxic ones. Moreover, it is verified that the microstructures would be different if the reversible part of the LST was restrained. The new phenomena and results reflected in this paper suggest that grasping the rules of melt structure change with temperature before material processing will give help for controlling the solidification more effectively and finally resulting in more ideal microstructures.IntroductionThe structure and quality of liquid alloys have a direct and important influence on the structure, performance and quality of the solidified ones. In recent years with in-depth study of liquid structure, researchers have found that some liquid structure transitions (LST) could occur on dependence of the temperature or pressure [1-5]. And the article [6] reported that a pressure-induced reversible LST was found in liquid triphenyl phosphite, which further confirmed the authenticity of the existence of the LST. Furthermore, in our earlier studies of Sn-based melts using resistivity method, some abnormal structure changes induced by temperature have been found at hundreds of degrees above liqiudus, and these LSTs are partly reversible[7]. This phenomenon has been discussed and it is suggested that the reversible LST in Sn-based melts are related to the short-range ordering (SRO) structures of Sn, which are tetrahedron structure with covalent bonding. However, does this reversible LST exist in other melts too?"

Jan 1, 2012

By Maria K. Kojo

The interaction between various slags and a nickel concentrate containing pyrite, pentlandite, and violarite were investigated by submerging concentrate pellets in molten slags. The slags were contained in MgO-A12O3 spinel crucibles. The slag oxidizes the iron sulfides in the concentrate, resulting in a nickel matte. The amount of S02 gas formed during reaction was measured to determine the oxidation reactivity of the slags. The experimental variables included temperature, the ferric/ferrous ratio of slag, and other slag properties such as the FeO/SiO2 ratio and the MgO and NiO contents. The reactivity of the slag depended in a complex manner on its oxidizing power, viscosity, and interfacial tension. The slag composition for the greatest reactivity was determined to be Fe3+/Fe2+ = 0.3, Fe/SiO2 = 1.3, and % MgO = 2. This slag, however, caused substantial foaming. Increasing the MgO content to 10% or replacing it by 5% MgO + 8% NiO eliminated at a slight decrease in reactivity. The implications of the findings from this work in the bath smelting of nickel sulfide concentrates are discussed.

Jan 1, 1995

By Kenneth N. Pike

The need to comply with environmental regulations and increase production has resulted in modifications to the East Penn blast furnace operation. Changes made include furnace design modifications, closed loop water cooling with heat recovery, automated weighing and charging, automated tuyere punching, ammonia scrubbing of tail gases and improved metal and slag handling to minimize environmental impact. These changes have resulted in a marked increase in yearly production and compliance with many of the air, water and solid waste regulations.

Jan 1, 1990

By R. G. Reddy

To better understand the behavior of bacterial-mineral interfacial reactions, a thermodynamic model based on the- studies of bacteria adhesion on mineral surfaces has been evaluated. The bacteria adhesion to the mineral surface would be increased by l ' d1;1creasing the change in Gibbs free energy of adhesion and it would be reduced if the change in Gibbs free energy of adhesion of the system is increased. From the combination -of Young's equation and equation of state, the change in Gibbs free energy of adhesion -for bacterium-mineral system- was calculated. Influence of liquid surface tension, mineral surface tension on the change in Gibbs free energy of adhesion and consequently bacteria behavior on mineral systems- has been discussed.

Jan 1, 1991

By Baozhong Zhao

Laboratory experiments have been conducted on the removal of As, Sb and Bi from molten copper by SF 6 injection. The results showed that the impurities can be removed by SF6 injection in the? sequence of Sb >As >,Bi and the rate of Bi removal is affected significantly by the concentration levels of As and Sb in the copper melt. Analysis of the experimental data indicates that the impurity removal process is under chemical reaction control rather than by mass transfer of impurity through the molten copper phase. On the basis of experimental results, a kinetic model was developed and the order of chemical reaction and the volumetric chemical reaction rate coefficients of impurity removal were determined.

Jan 1, 1996

The presence of clay adversely affects the floatability of copper and molybdenum during processing porphyry copper/molybdenum ores. In addition, reagent consumptions are much higher than when treating clay-free ores. Ores containing kaoline, brammollite, illite and montmorillonite were examined in the laboratory to determine how clay minerals affect the floatability of copper and molybdenum, and to find a possible solution to alleviate the harmful effect of clay slimes. It was demonstrated that the presence of clay mostly affects floatability of coarse and middling particles, and reduces selectivity. The results of the research work showed that there may be several possible ways of reducing the detrimental affects of clay slimes on flotation, some of which include a) use of alternative flowsheets, b) flotation at reduced pulp density, and c) the use of special frothers. The applicability of the findings in plant practice are discussed.

Jan 1, 1999

By Varadajan Seshadri

The increase in production of continuous casting machines requires long ladle sequences without interruption. Very often the production schedule has to accommodate a variety of steel grades. In such cases downgrading may be inevitable. Models must be made available to study the alternatives that would make possible mixing of steels in the tundish but minimizing the losses due to downgrading the slabs. Physical modeling was used to evaluate the influence of variables such as internal geometry of the tundish, presence of turbulence inhibitors, depth of ladle long nozzle, weight of steel in the tundish, steel throughput upon the tundish transition curve. Expressions for minimum residence time and transition period have been determined. Mixing-transition is allowed to continue inside the liquid pool in the mold and the final solute distribution in a given cross section is captured by a solidification model. The result is a map of the transition in the final product.

Jan 1, 2006

By Jacqueline JAlexander

Two of the most important phenomena which govern the continuous casting process and determine the quality of the product are the fluid flow and the heat transfer. Steel flows into the mold through the ports of a bifurcated submerged entry nozzle (SEN), which directs the jet to the mold narrow faces where the superheat contained is dissipated on the solidifying shell. Many important aspects of the fluid flow in the mold are transient and difficult to control. However, the time-averaged flow pattern in the mold is greatly influenced by the nozzle geometry, the submergence depth and the mold dimensions. The aim of this work is to analyze the relationship between the heat transfer and the fluid flow pattern inside the mold using the CFD technique at several operating conditions.

Jan 1, 2009

By Yongzhong Xiao, Tiejun Chun, Jian Pan, Deqing Zhu

"An innovative process of reverse floatation-direct reduction-low intensity magnetic separation was developed to effectively beneficiate the superfine run-of-mine (ROM) ore mined from Hunan Province, China. Mineralogy was measured that the ROM ore is of superfine low grade hematite ore type, assaying 27.2wt%Fetotal and with main valuable minerals of hematite occurring at size between 3 to 5µm. The upgrading results show that the final iron concentrate, assaying 88.3wt%Fe total and 94.5% metallization degree was obtained at an overall iron recovery of 69.9% under the following conditions: rough concentration by grinding of ROM up to 88.7% passing 0.074 mm and reverse flotation at pH=9.4, 100 g/t starch and 200 g/t dodecylamine (DDA), and coal reducing the rough concentrate pellets containing 12% calcium containing complex additive at 1200 oC for 120 min, and finally magnetic separation of the reduced pellets by grinding up to 89.2% passing 0.043 mm at 0.08 T field intensity.IntroductionWith the rapid development of iron and steel industry in China, there has been a soaring demand for iron ores in the past decade. The imports of iron ores have increased from 148 million ton in 2003 to 628 million ton in 2009 [1]. Iron making industries increasingly demand for high grade raw materials to improve product quality and reduce operation cost. However, availability of high grade natural ores is limited and enrichment of lower grade ores is necessary to meet the demand. Therefore, large quantities of superfine low grade iron resources are necessary to utilize in China at the moment."

Jan 1, 2011

By Yusuke Kimura, Ken-ichi Yamaguchi

"Secondary materials have long been processed at the S-furnace of the Mitsubishi continuous copper smelting and converting process at Naoshima Smelter and Refinery. Intensive recycling in the recent years has formed concerns that impurities in the secondary materials may cause drastic changes in the chemical properties of the CL-slag, which is separated from matte in the smelting stage. Among various impurities included in secondary materials, the authors have studied the influences of sodium oxides in the CL-slag because the behavior of sodium oxide has scarcely been studied with respect to the copper smelting slag. The examinations have been applied experimentally on the distribution between slag and matte of arsenic whose acidic characteristics suggest strong affinity to sodium-oxide of basic characteristics in silicate melts. The results have been discussed by thermodynamic evaluations and the results of pyro-tests at the commercial furnace.IntroductionAt Naoshima Smelter and Refinery, the existing line of the Mitsubishi continuous copper smelting and converting process has been operated since 1991. The Mitsubishi Process consists of three furnaces namely the S-, CL- and C-furnace as shown in Figure 1. In the S-furnace, copper concentrate and powdery secondary materials (scraps, sludges, etc) are charged through the top lances with oxygen enriched air. The other secondary materials of lumpy shapes are charged through the chute installed on the furnace roof. Charged materials are smelted by the reaction heat in accordance with the oxidization of copper concentrate. The mixed melt of matte and slag overflows through the launder into the CL-furnace, where the melt is separated into slag and matte by the difference of their specific gravity. Matte is siphoned out and sent to the C-furnace and converted to blister copper continuously. The CL-slag overflows continuously through the slag outlet to be water-granulated. Granulated slag is sold as a raw material used for the cement production and so on. Various secondary materials have been processed at the S-furnace of Naoshima Smelter and Refinery. Intensive recycling in the recent years has formed concerns that the chemical properties of the CL-slag may change drastically due to impurities originating from secondary materials. Among various impurities included in secondary materials, the authors have studied the influence of sodium oxide in the CL-slag because the impact of sodium oxide has scarcely been studied with respect to the copper smelting slag. The examinations have been applied experimentally on the distribution between slag and matte of arsenic whose acidic characteristics suggest strong affinity to sodium-oxide of basic characteristics in silicate melts."

Jan 1, 2012

By Muhamad Firdaus

There is a growing interest in Magnetoelectric (ME) materials in view of both fundamental understanding and novel desirable applications. The application potential for multiferroic materials with the possibility of reversing the magnetization by applying an electric field (or vice versa) is quite promising especially in data storage application. The rare earth ortho-ferrites (REFeO3), such as NdFeO3, have been studied extensively in recent study in the context of discovery of magneto-electric (ME)/multiferroic nature materials. In this paper a potential high temperature recovery of rare earth elements in the form of REFeO3 from waste permanent magnets using direct oxidation in air was investigated. It was found that REFeO3 (NdFeO3) phase can be separated from the other oxide phases by thermal treatment of NdFeB magnet waste at 1100 °C in air atmosphere. The REFeO3 also found to have different physical characteristic (density) from the other layers and can be separated physically. This paper will include a proposed flowsheet to recover Nd as NdFeO3 through powder separation. The technique can be beneficial and favourable for RE recycling and recovery from waste permanent magnets.

By John R. Howell

"SUMMARYThe process of producing a new cast component requires significant design and development by both the design engineer and the foundry engineer. This effort strives to produce a high quality component at minimum cost. To assist in this development, an analysis system, consisting of several computer programs, has been developed to simulate the metal casting process. This system incorporates analytical geometric solid modeling, finite element analysis, results display, and an innovative technique to model the casting mold with surface boundary conditions.The simulation has produced excellent thermal results and work is in progress to develop techniques to enable use of this data in additional analyses to predict porosity and residual stress. Research is required to produce working parametric formulations of material properties. Software development is required to develop good fluid flow analyses for large. 3D models to simulate filling of and convection in molds.Integrating this system of programs is difficult due to proprietary database structures used by software developers. However, an acceptable means has been accomplished' to move data from one program to another. Further software development is required to facilitate this task. INTRODUCTIONThe process of producing a new cast component requires significant design and development by both the design and foundry engineer. This effort strives to produce a high quality, reliable component at minimum cost in a timely manner. The design engineer needs to know the physical and mechanical properites which can be expected in the actual part at critical areas. This will enable him to design a part with minimum material while fulfilling the performance required. The foundry engineer needs to produce a sound, quality casting with a minimal amount of material In risers, the feeding system and machining stock. This must be done with a minimum· investment in tooling and development time and maximum productivity of labor and capital employed. This task Is continually being made more difficult because of increased competition in the marketplace and the use of castings in more severe service. This has strongly influenced the need for high quality castings.The task of developing a new casting is difficult for both the design and foundry engineer. To assist in this development, Deere & Company has been engaged in the development of an analysis system to simulate material processes. A major portion of this program involves simulation of the metal casting process. This analysis system has evolved into a package of computer programs which simulates casting solidification and subsequent cooling through the finite element method"

Jan 1, 1986