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By Jim Sundal

Primary steel manufacturers using electric arc furnaces generate one of the largest hazardous waste streams nationwide. The waste stream, known as electric arc furnace dust, is a listed hazardous waste with the designation K061. Oregon Steel Mills, Inc., (OSM) of Portland, Oregon, has implemented a process known as Glassificationn, which uses KO61 as an ingredient in an onsite recycling process. Because OSM was able to demonstrate that the Glassificationm recycling process beneficially uses all toxic constituents in the electric arc furnace dust and that the recycling process produces marketable products, the process is not subject to Resource Conservation and Recovery Act (RCRA) permit requirements. The marketable products manufactured using Glassificationn include roofing granules, ceramic glazes and colorants, abrasive blasting media and, more recently, synthetic slag fluidizers. The purpose of this paper is to identify the regulatory issues for recycling hazardous waste and demonstrate that OSM glass frit is effective as a slag fluidizer in primary steel manufacturing.

Jan 1, 1994

By Zheng-qi Guo, De-qing Zhu, Feng Zhang, Jian Pan

Iron mainly exists as the magnetite and fayalite, while copper is primarily dispersed in the form of fine matte particles in the copper slag, which is difficult to recover by conventional separation techniques. In this paper, the feasibility of an integrated technological route to improve beneficiation of copper and iron components from copper slag through the modification of molten slag was investigated, and the results shows that: the copper grade of rougher copper concentrate was increased from 6.43 to 11.04%, iron recovery from magnetic separation was increased significantly from 32.40 to 63.36%, and other evaluation indexes were changed slightly, in comparison with unmodified copper slag. Meanwhile, the grains of the target minerals in the modified slag grew considerably to a mean size >50 lm after slow cooling. Ultimately, the beneficiation efficiency of copper and iron was improved because of the ease with which the target minerals were liberated.

Mar 1, 2017

By Christoph Zschiesche

Managing complex material streams within a lead smelting/reduction process has a long history at Aurubis. After modernization of the secondary lead smelter in 1991, Aurubis operates an electric furnace and a Peirce Smith converter to process complex secondary materials. This process links the copper and the lead metallurgy allowing Aurubis to properly combine primary and secondary process lines to optimize the processing of complex raw materials and smelter intermediates. However, combination of copper and lead metallurgy processing requires a continuous evaluation as raw material quality and composition varies. This paper describes Aurubis lead smelter processing and provides some fundamental considerations to optimize the lead processing, in particular with aspects related to speiss formation

By SM Rao

Nuclear Fuel Complex (NFC ) , Hyderabad (IN DIA ) , is engaged in the manufacture of nuclear fuel assemblies and zircaloy structural components required for the Indian nuclear power reactors. The production of zirconium oxide, sponge and zircaloy materials through chemical and hydro - metallurgical processes generates many effluents containing valuable zirconium and hafnium . This paper deals with the various processes such as multiple crystalization, phosphate precipitation, ion-exchanges amine solvent extraction etc, for the treatment of these effluents and subsequent recovery of valuable zirconium and hafnium .

Jan 1, 1992

By I. Gaballah

Cadmium is toxic to plant, animals and humans. The council directive of the European Communities No 8315 13lEEC has fixed an upper limit of 200 ppb for the release of cadmium in industrial effluents. The conventional method of neutralization/prccipitation ( NIP ) is inefficient to reach this limit. The objective of this study is to test the efficiency of the trees modified bark to remove cadmium cations from industrial effluents after the conventional treatment by NIP. Laboratory scale tests with synthetic solutions show that the cadmium removal depends upon pH and initial concentration. About 99.9 %, 99 % and 96 % of the metal are removed from synthetic solutions containing 10, 100 and 1000 ppm respectively. Pilot plant trials ( 1 m3 ) with an industrial effluent bearing about 500 ppb of cadmium lead to the almost complete elimination of the cadmium ( final concentration is lower than the analytical detection limits < 20 ppb ).

Jan 1, 1994

By Ari JokiIaakso

Three different sulphidic raw materials were treated in a laboratory scale laminar flow fur-nace simulating suspension smelting conditions. The materials were a pure chalcopyrite concentrate, a high-antimony concentrate (tetrahedritic), and crushed copper mattes. The gas preheating temperatures were 500 -1 100°C ana the atmospheres ranged from N2 to N2 -75 % O2, Two particle size fractions were used for the concentrates with x = 20 -38 um and x = 62 -74 um, and three for the granulated copper mattes with x < 37 um, x = 62 -88 um, and x = 125 -177 um. Scanning electron microscopy combined with energy dispersive analysis and backscattered electron analysis was used for determining the morphology and the mineralogy of the reacted particles. Fragmentation of the particles were observed in all materials during the flash oxidation, the conditions depending on the iron and sulphur content and the original particle size fraction of the material. The melting and/or reaction stages of the particles in different conditions were studied from powder samples. Polished sections were examined in order to follow the development of porosity and the mineralogy of the particles.

Jan 1, 1989

By Jussi Vaamol

A commercial CFD-code was used to solve isothermal flow fields of gas and liquid in a Peirce-Smith converter. The model was validated with a 1/4 scale water model, and parametric study. Limits of the modeling technique used were recognized, but calculated results indicate that the present model predicts the general flow field with reasonable accuracy. The model was used to examine general flow conditions in an industrial scale PS-converter. Typical scaling factors of physical models were also evaluated with the aid of predicted bubble distribution, patterns of the flow fields and magnitude of flow velocities. The numerical simulations were found to open new viewpoints to the fluid dynamic related phenomena in the PS-process.

Jan 1, 1998

Halide media are considered as suitable alternatives to cyanide for extracting gold and have received much attention lately. The extraction of gold by iodide-iodine mixture has been patented and briefly studied without much attention given to the fundamental aspects of this process. This paper reports recent studies on the kinetics of gold extraction in iodide media, using hypochlorite, iodine and hydrogen peroxide oxidants. The kinetics of dissolution was found to be dependent on the solution pH, reagent concentration and most importantly the iodide- oxidant molar ratio. Without proper control, the gold surface can be passivated due to the formation of solid products. Thermodynamic modelling was carried out to determine the equilibria governing the dissolution process. The formation of AuI solid was also identified as a possible product during the dissolution.

Jan 1, 1992

By Steven M. Puricelli

Sulfuric acid plants associated with smelters, have historically been an overworked and often neglected pollution control device. They could do little more than manage the wide fluctuations in gas flow and SO2 strength from the smelter. With the introduction of flash smelting, the picture began to change, but the fluctuating batch converters continued to dictate acid plant design. More recently, the commercial use of continuous converting processes utilizing high levels of oxygen enrichment has dramatically upgraded the SO2 strength and stabilized the gas flow to the acid plant. The SO2 gas now issues continuously and at concentrations that allow for compact and, cost effective acid plants. Relieved of the burden of excessive dilution air, the heats of reaction can also be recovered as medium pressure steam and used to drive a generator, making the acid plant a net producer of power and a valuable asset to balance sheets. This concept was put into practice at the Kennecott Utah Copper Corporation smelter modernization project, located in Salt Lake City, Utah. The new acid plant, which was commissioned in June of 1995, is a sophisticated, low environmental impact, energy producing plant, worthy of review. This paper examines the key features of this acid plant, such as controlling its tail gas, by catalysis alone, to an environmentally friendly, 100 ppm of SO2, while feeding the acid plant converter with an efficient 14% SO2. The acid plant is also a prudent steward of energy resources, recovering 220,000 lb/hr of 140 psig steam from process heat which is used to generate a substantial 20 MW of gross power. Also discussed will be some of the ongoing issues, such as handling of selenium and fluorine in the gas cleaning sections, as well as a review of some. of the problems that were identified and resolved. Today&apos;s modem acid plants, by necessity, are becoming a producer of quality, valuable products, making the acid plant an asset and not a liability. Plants like Kennecott are already gaining wider acceptance and are expected to be the vision of the future.

Jan 1, 1998

By T. Plikas, L. H. Gunnewiek, L. Oshinowo

"Electric furnace smelting is one of the principal unit operations for ferroalloy production, and increased process intensity, improved availability, minimal maintenance and a longer campaign life are common objectives for electric furnace operation in order to obtain favourable economics of production. Furnace designers have continued to develop innovative solutions, e.g., furnace cooling systems, that have allowed these objectives to be realised and CFD modelling plays a key role in the design process. Enhanced understanding of the energy transfer process in the furnace and the ability to develop, evaluate and optimize components of the crucible design to match process requirements are the key motivators for modelling.This paper provides an overview of recent applications of CFD to the design of electric furnaces. The aim is to illustrate what can be done, and identify areas where further work is needed in this field. Examples include furnace bath simulation, crucible cooling system design, taphole design, baking of Soderberg electrodes, off-gas systems, and fume control and building ventilation. It is argued that the trend is for numerical models to become more encompassing while at the same time more accessible, and therefore further improvements in furnace design will be realised with continued and well validated modelling efforts.IntroductionOne of the main processing steps in ferroalloy production is the smelting of ore in electric furnaces. The three-electrode, AC submerged arc furnace is most prevalent method for smelting in the industry, with shielded-arc and DC plasma arc furnaces achieving limited application (1,2). Commercial furnaces range in size from a few megawatts to more than eighty megawatts of supplied power, and operate with the objective of maximising the return on capital invested. Maximising productivity and energy efficiency are two pathways to achieving this objective, through process intensification, increased availability, minimal maintenance, and increased campaign life for the furnace and associated equipment. Concurrently, the need to reduce the environmental impact of metal production by controlling the emission of particulate emissions, greenhouse gases, and other harmful by-products must also be met."

Jan 1, 2004

By G. S. Victorovich

Technical progress in primary smelting has changed the face of the copper industry in the years since the Second World War. Much of this change has resulted from a wide acceptance of flash smelting technology. In addition, research has been directed toward devising converting processes to replace conventional Peirce-Smith converting technology. One major thrust has involved a revival of the old " ", idea of oxygen flash converting of comminuted mattes. This paper reviews the 60-year history of flash converting. Particular attention is paid to Inco&apos;s investigations into the processing of white metal containing significant amounts of nickel and, in some cases, iron. Thermodynamic analysis and laboratory experimental results are presented which throw light on the behaviour of nickel and other salient features of flash converting. The possible role of oxygen flash converting in the copper pyrometallurgy of the future is briefly discussed vis-a-vis direct production of copper.

Jan 1, 1993

By Xiao-hui Fan, Xu-ling Chen, Zhi-yuan Yu1, Guanghui Li, Min Gan, Yun-song Huang, Tao Jiang

Compared with the traditional de-NOx processes by cleaning the waste gas, a new approach for reducing the formation of NOx during sintering process is proposed. Since more than 90vol% of NOx comes from the fuel combustion, the influence of sintering coke breeze pretreated by CO(NH2)2 additive on the NOx emission is researched. As adding CO(NH2)2, the reduction agents (NHi) are generated during the pyrolysis of CO(NH2)2, which reinforce the NOx reduction, And the appropriate content of CO(NH2)2 is 1.0 mass% of coke breeze.

Jan 1, 2015

By K. Alibhai

Greek laterites, which generally had nickel concentrations of < 1 %, are amenable to chemical leaching,. although there is considerable variability in the ease of leaching with different ore types. With low grade ores(< 1 % Ni content); >70% of the nickel was leached in columns with a strong selectivity for nickel over iron. Heterotrophic microbially assisted leaching could be a viable alternative to classical hydrometallurgical and/or pyrometallurgical techniques, with a very high recovery (greater than 80% ) being found with some of these mineral microbial interactions. Critic acid was probably the effective chelating agent.

Jan 1, 1991

By Kota Nakashima

Residues from titanium smelting tend to contain scandium. The scandiumis discarded because no suitable process exists for its recovery from the residue. Valuable-metal recovery from discharged residue is critical for environmental conservation and to achieve a sustainable society. Since 2015, JXNippon Mining&Metals has been developing a process for scandium recovery from the residue of a titaniumsmelting process. The process consists of the following steps: scandium concentrating by classification or neutralization, selective scandium leaching, impurity removal by neutralization, solvent extraction of scandium by using D2EHPA, purification, and roasting. We optimized the above steps to achieve an effective process to obtain scandium oxide (Sc2O3). In this paper, we introduce results from the bench-scale test of the scandium recovery flowsheet developed by JX Nippon Mining & Metals.

By Omid Marzoughi

Chromium has a wide range of applications, including as an alloy addition in various steels and also as a corrosion resistance coating. Carbothermal reduction of chromite ore (FeCr2O4) in a submerged arc furnace is an important industrial process for extracting chromium, but the energy consumption is excessive. It is suggested that one area for future research is the low temperature carbothermic solid state reduction of chromite to produce an intermediate product, which can subsequently be upgraded to ferrochromium. In this regard, a thermodynamic model has been developed to investigate this process and the effects of temperature, carbon additions and ore composition on the recovery of chromium and the grade of the ferrochromium, have been studied. Further development of the model may allow it to be applied to the simulation of other processes for the recovery of chromium from chromite ores.

By David B. George

Kennecott recently completed an $880 million modernization and expansion of its smelter and refinery to process all concentrates from the Bingham Canyon mine. This is the first application of Kennecott-Outokumpu Flash Converting. Molten material movement by overhead cranes is eliminated and high levels of oxygen enrichment result in very low process gas volumes and exceptionally control of sulfur oxide emissions. All existing in-plant hygiene, safety, and environmental regulations will be met and the smelter is positioned for anticipated more stringent future regulations. Sulfur capture is 99.9 percent resulting in sulfur dioxide emissions less than the 112 kg/hr Air Permit limit, making the smelter the cleanest in the world.

Jan 1, 1996

By Autumn Fjeld

The filling and solidification of an industrial scale composite casting has been simulated to investigate the re-melting of the outer shell material during casting. Production of a composite requires a two-step casting process which includes centrifugal casting of a hard outer shell material and subsequent conventional ingot casting of a tough core material into the shell-mold assembly. During casting of the core, a thin layer of the shell material re-melts and mixes with the core material producing a bonding layer of intermediate composition. The present numerical model employs the volume of fluid method and an enthalpy-porosity technique to couple the filling of the core material and re-melting of the shell material. The interface between the two materials is tracked and can be used as a guide to examine the extent of melting and, to some degree, mixing of the two fluids and species diffusion.

Jan 1, 2008

By Michal Stepien, Piotr Palimaka, Stanislaw Pietrzyk

During the steel scrap melting process in an electric arc furnaces, the generated dust may contain a significant amount of zinc. The content of zinc in case of melting galvanized steel scrap is variable and ranges from 15 to 40 wt%. This dust cannot be re-used for the steelmaking process. On the other hand the zinc content is too low to treat the steel dust as a feedstock in pyrometallurgy of zinc. When they are disposed in land fills they have adversely effect the environment. This work presents selected results of research and development of new technology, which was developed in order to utilization steelmaking dust in the sintering process. One of the products (zinc-rich) can be used as a high-quality raw material for production of zinc by pyro- or hydrometallurgical processes. The second one product from the shaft furnace can be used as a feedstock for the steelmaking process.

Mar 1, 2017

By Paul Laforest, Michael Moats, Daniel Majuste

The interaction of anode and electrolyte chemistry in copper electrorefining is complex. This is especially true with regard to the behavior of Group 15 elements (As, Sb, and Bi). To better understand this system, laboratory electrorefining experiments were conducted using commercial anodes with As/(Sb + Bi) molar ratios of 0.54 and 3.8 and an electrolyte collected from a commercial refinery. The effect of adding thiourea during plating was also examined. Twenty-one hour copper deposits were produced in the laboratory to simulate starter sheet production. The mechanical properties of the electrodeposited copper as measured by an industrially relevant empirical bend test and a one-point bend test developed by UFMG are reported. The crystal structures of the samples were also examined.

Mar 1, 2017

By R. R. Beebe

"Laboratory and pilot-scale tests are almost invariably required before metallurgical development can proceed. Difficulties with sampling, as well as with classical chemical and physical scaleups, are normally anticipated and relatively well-understood, but more subjective factors also come into play, including misunderstandings of the operating scheme chosen, wrong ""lessons"" learned from similar operations, failures to handle data appropriately, and even arbitrary intervention by management. The paper examines some of these subjective factors and suggests ways to guard against them. Several anecdotal case studies are used as examples, including when and where to heap leach or to mill specific types of gold ore.When the Romans first exploited the gold-rich gossans at Rio Tinto, they were guided by analyses and tests that delineated the ore deposits, identified the richer portions, and measured the gold recoveries achieved. There is little evidence, however, to suggest that test data were used to develop improved methods of metallurgical extraction. Indeed, it is likely that ores too difficult to treat were simply passed by, at least until improvements in full-scale operations could deal with them. For example, it is not difficult to imagine that an early metallurgist might test a tin ore by placing some in a fire; a smallscale emulation of the method actually used in practice."

Jan 1, 1997