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By Lidong Teng, Seshadri Seetharaman, Aida Abbasalizadeh

0In the present paper, the feasibility of the recovery of dysprosium from spent Nd-Fe- B magnets containing approximately 9 wt% Dy was investigated by using molten salt process. The salt bath consisted of a mixture of NaCl-KCl-LiCl corresponding to the ternary eutectic composition. AlCl3 was used as a chlorinating agent in order to enable an efficient dissolution of metal in the molten salt phase in the salt bath. The metal chloride which is formed as the result of chemical reaction between the metal in magnet and AlCl3, is subsequently subjected to electrolysis in order to be deposited on the cathode. Graphite rods were dipped in the salt bath as electrodes and alumina crucibles were used as the containers for the electrolytic cells.

Jan 1, 2014

By Keith E. Forrester

This paper presents results of bench scale laboratory evaluation of a processes developed by FESI and Brookhaven National Laboratories for the extraction and recovery of Pb and other heavy metals from incinerator ash which was subsequently modified by FESI for the extraction and recovery of Pb from soils excavated from a FESI client scrap yard and battery breaking operation facility. The specific waste matrix presented within the paper is a battery acid contaminated surficial soil at 0" to 12" depth. The extraction method was found to be highly successful on the bench scale in generating a final post-extracted soil matrix which passed TCLP Pb regulatory limits and retained minimal Pb after aggressive extraction application. The paper findings at this time are brief, as a majority of the research results are currently being compiled and additional efforts are underway based upon initial screening findings.

Jan 1, 1995

By K. A. Natarajan

Microbe-mineral interactions in the leaching of complex sulfides are discussed with respect to (a) role of galvanic interactions in selective dissolution, (b) bacterial attachment to sulfide mineral substrates and (c) the utility of specially adapted metal tolerant bacterial strains. Experimental results obtained in the leaching of two types of complex sulfides, namely, a lead-zinc-copper sulfide and a copper-nickel sulfide are illustrated.

Jan 1, 1985

By F. M. Doyle, K. Sreenivasarao

Copper and cadmium metal has been recovered from dilute (3 X 10-4 mol/dm3 ) chloride solutions by ion flotation with dodecysulfate, followed by electrolysis. This approach should facilitate treatment of effluents too dilute for effective direct electrolysis. . The adsorption density of metal dodecylsulfate complexes on bubble surfaces was estimated from surface, tension data, and compared well with experimentally-observed metal removal kinetics, and ultimate recoveries. Copper and cadmium were recovered by electrolyzing the foamate, using steel wool cathodes and a graphite anode. The stability constants of the copper and cadmium dodecysulfate complexes are estimated, and used to analyze the thermodynamics of electrolysis. Dodecysulfate was unaffected by the electrolysis process, and hence could be recycled to ion flotation. A conceptual flowsheet for an overall effluent-treatment process is presented.

Jan 1, 1997

By Józef Czernecki

The Polish copper concentrates are characterised by low content of sulphur and iron. At KGHM Polska Miedz S.A. two copper production technologies are in use. The shaft furnace process is used at the Legnica Copper Smelter and the Glogów I Copper Smelter. A single-stage direct to blister Outokumpu flash smelting process is used at the- Glogów II Copper Smelter. Melting copper concentrates in the shaft furnaces is carried out in a reducing atmosphere and the product obtained is a matte. Instead, a result of melting copper concentrates by an oxidising flash process blister copper of a quality similar to that of converter copper is obtained. The annual copper production at KGHM Polska Miedz S.A. exceeds 450,000 tons. Another important metal is silver produced from slimes from copper electrolysis (about 1000 t/y). Moreover, such metals as Pb, Ni, Se, As, Au and other precious metals, including Pt and Pd, are recovered from various semiproducts. This paper presents technological flow sheet of the copper production in plants using the shaft furnaces and in another plant in which a single-state flash process is applied. Characteristics of products, methods of their utilisation, main parameters of particular technological operations, and advantages and shortcomings of the solution applied are presented. There are also discussed: the natural environment protection as well as directions of the KGHM Polska Miedz S.A. plants modernisation.

Jan 1, 1999

By Laurentiu Nastac

"Two advanced control solidification technologies were studied in this article to improve the quality of the cast ingots as well as to control the solidification structure evolution during the plasma arc melting (PAM) processing of Ti-6-4 ingots: (i) electromagnetic stirring (EMS), and (ii) ultrasonic treatment (UST). The developed EMS modeling approach is based on the numerical solution of Maxwell's equations, fluid flow, and heat transfer equations, and mesoscopic modeling of the grain structure. The UST analysis tool is capable to model acoustic streaming and cavitation. It is used in this work to study ingot solidification under the presence of ultrasound. Predictions of the macrostructure, GET formation and primary dendrite arm spacing for PAM Ti-6-4 ingots processed with and without EMS or UST were discussed.1. IntroductionTitanium (Ti) alloys are melted, refined and cast into ingots through plasma arc cold hearth melting (PAM), electron beam cold hearth melting (EBM) and vacuum arc remelting (VAR) for jet engine applications. Process modeling has become a viable tool to optimize the PAM, EBM, and VAR processes. A comprehensive modeling approach to simulate ingot solidification phenomena in primary melting and secondary remelting processes of Ti alloys would include models for macroscopic mass transfer, heat transfer, fluid flow, acoustic, electromagnetic and species transport. The approach should also include microscopic models to predict the evolution of grain structure in solidifying ingots in conjunction with electromagnetic stirring (EMS) and ultrasonic stirring (UST)."

Jan 1, 2012

By Tatsuki Uzawa, Takashi Nagai

The consumption of Nd and Dy is increasing dramatically because of an exceptionally high demand for Nd-Fe-B-(Dy) magnets and a significant amount of the magnets are wasted. It is important to develop a recycle process the elements from the wasted magnets. In this study, Nd and Dy were extracted from the magnets by silver at high temperature. Nd can be extracted more than 70 % by silver. However, Dy is extracted only 25 % in the same experimental condition.

Jan 1, 2014

By Ana Bohé

Nowadays, Gas-solid processes are widely used in the industry. The chloration and carbochlorination of metallic compounds are some of this kind of non catalitic heterogeneous reactions. In particular those related with extractive metallurgy of refractory elements (Zr, Ti, Nb, Ta, RE, etc). The development of materials to be used in reactors at elevated temperatures and with high corrosion performance, enhance the application of this kind of processes. Although they are currently carried out in the production of many comodities, the mechanism of most of them are yet not well understood. The present work is a deep discussion on the most important aspects to take into account for determining the mechanism of gas- solid reaction, and those criteria fulfil in this analysis were applied to chlorination and carbochlorination examples. The microstructural characteristic of solids, the mass and heat transfer phenomenon, the adsorption and desorption of gaseous species on active surface, surface diffusion processes and chemical elementary steps, which are the mainly contributions to the mechanism of these reactions were analysed. Furthermore, the effect of them on the reactivity of solids and the control step of the reactions were determined. The application of catalitic mathematical models to this kind of reaction and the modification for the better interpretation of experimental results is also undertaken. The most appropriate experimental procedures for following these reactions and the microstructural characterization techniques needed to be use in each case, there limits and applicability are also indicated.

Jan 1, 2006

By Tuula Mäkinen

In 1959 Outokumpu started up an integrated nickel smelter and refinery at Harjavalta. The flash smelting ? Peirce-Smith converting route was applied, and the high-grade converter matte was further refined to nickel cathodes by leaching and electrowinning. In 1995 the production capacity was increased from 17 000 mtpa to 52 000 mtpa, based on the Direct Outokumpu Nickel Smelting Process. The additional refinery capacity is based on hydrogen pressure reduction, producing nickel powder and briquettes. The smelting operation is currently part of Boliden Group and the nickel refinery part of OM Group. In the DON technology, high-grade nickel matte with low iron content is produced in the flash smelting furnace directly without subsequent converting. The metal values in the smelting slag are recovered in an electric furnace as an iron containing Ni-matte. The mattes produced differ from the conventional nickel mattes in many respects, and therefore focused R&D efforts have been made in order to cope with their melting points, fluidities and settling properties. When developing and operating metallurgical processes it is crucial to manage and control the characteristics of the products as well as by-products generated in different steps of the process chain. The low melting points of the high-grade nickel mattes produced in the DON furnace, particularly those low in copper, have pointed out challenges in the furnace design, in particular in the hearth and its thermal engineering. Also key issues of the DON technology are smelting of high-magnesia concentrates, the recoveries of nickel and copper, as well as those of PGM`s and cobalt. These factors can be affected by a proper selection of the process concept, and the operational conditions in the processing vessels. This paper deals with the experience of the DON technology gained over the first ten years of operation, including the significant environmental impacts. Selected results of the thermo-dynamic modelling of DON and EF mattes and high-magnesia slags are reviewed, with the reference to the mattes produced. Also the design principles of the FSF and EF will be discussed.

Jan 1, 2006

By D. N. Collins

A sampling program was conducted in which both spoon and isokinetic sampling techniques were used to collect samples from the reaction shaft. The samples were then characterised by chemical, XRD and mineralogical analysis. Further information was acquired by measuring the oxygen potential and temperature at the bottom of the shaft using disposable probes. Comparison of the results of the two sampling methods showed that the spoon samples were devoid of material less than 25 m. Sulfur analyses on the samples provided information on the extent of reaction, plume shape and recirculation patterns. Disposable probe measurements showed the measurable particle temperatures ranged from 1150 to 1700 °C and that the material falling into the bath had a normalised oxygen potential similar to the slag. These latter measurements combined with the sulphur elimination and mineralogical analyses provided further information on the extent of reaction and enabled the reaction sequence to be ascertained.

Jan 1, 1999

By Iris Filzwieser

The secondary copper producer, Montanwerke Brixlegg AG (Austria), produces 73 000 tonnes of cathodic copper per year using ISA tankhouse technology. METTOP GmbH (Austria) evaluated the different anode qualities from the plant with relation to the current efficiency and specific energy consumption. Parameters including the chemical and physical anode quality, current and current density distribution at each cathode, voltage, and distance between each cathode and anode were examined. In addition, the temperature, chemical analysis, and conductivity of the electrolyte was determined for each investigated cell, as well as the anode weight, anode scrap, cathode sheet, and short circuits. Metallographic analysis was also performed on selected dendrites. The investigations resulted in specific improvements in the tankhouse process including the level of anode impurities, and future projects are planned for further tankhouse optimization.

Jan 1, 2006

By M. J. Collins, L. C. Trytten, K. R. Buban, I. M. Masters

Both pressure leaching of zinc concentrate, in an autoclave, and atmospheric leaching, in stirred tanks, have been employed in the expansion of zinc production at plants employing roast-leach-electrowin technology. These direct leaching methods result in the conversion of the sulphur in the feed to the elemental form, rather than to sulphur dioxide, decoupling zinc production from acid production. Atmospheric and pressure leaching methods are also readily implemented over a wide range of production rates. In choosing the best technology for expansion, capital and operating costs, zinc recovery, byproduct quality and the compatibility of recycle streams with the existing refinery must be compared. Leach testwork with several zinc concentrates using both methods has been performed by Dynatec. Recent results are presented, along with a discussion of their implications for process selection.

Jan 1, 2000

By Robert T. Oxnard

"EXECUTIVE SUMMARYThe history of Refractory Recycling indicates there was little recycling until the 1950s. Energy incentives were the primary reason for the beginnings of a recycling effort by the refractory brick manufacturers. Quality benefits quickly became evident and fewer rejects were the result. Today, economic factors including higher valued raw materials and increased competition are the driving forces of refractory recycling.There are some success stories in refractory recycling but we have a long way to go. Few incentives, quality concerns, relatively cheap energy, comparatively lax government regulations, inexpensive landfills and inexpensive substitutes make recycling a difficult choice for many companies. Marketing advantages such as ISO 14000, eliminating multiple audits and reduced liability exposure can tip the scales toward recycling viability. Increasingly, the ideological philosophy of a company, a desire to minimize environmental impact and develop favorable public and other interested party perceptions can drive recycling and waste minimization efforts.Recycled materials can be more trouble ""up front"" and harder to ""manage"" due to their suspect quality. However, due to their nearly inexhaustible supply and the fact that once developed, they constantly contribute to the bottom line, they are certain to be the materials of the future. Waste refractory materials will likely see the same bright future as the steel scrap yards and slag piles of yesterday. In hindsight, we will realize that now was the perfect time to prepare and plan for the bright future of refractory recycling."

Jan 1, 2000

By Jing Zhang, Chenguang Bai, Fusheng Pan

"The microstructure and hot deformation behaviour of an Er-modified Mg-Zn-Ai alloy were evaluated. The results showed that the addition of rare-earth Er changed the morphology of the quasi-continuous grain boundary networked eutectic compound to globular particles. Moreover, a self-strengthening effect was identified for the alloy, which determined its deformation behavior. After hot extrusion, the yield strength and elongation to failure of the Mg-Zn-AI-Re alloy at 200°C were increased by 105% and 120%, respectively, due to an emerged dynamic precipitation strengthening mechanism.IntroductionMagnesium alloys are attracting increasing attention for applications in automobile, electronic devices and hand tools for weight reduction and higher fuel efficiency, because of their lightweight and a high specific strength. However, application of Mg is still very limited. The largest applications are still those non load-bearing castings used at room temperature, such as box case, housing, and covering. One of the main reasons is the inadequate absolute strength both at room temperature and elevated temperatures (> 100°C) of the commercially used AZ, AM series alloys, due to the incoherent interface between the secondary phase y-Mg17AI12 and Mg matrix, as well as the low thermal-stability of the y phase [1]. Besides, the heat-resistant magnesium alloys which contain rare earth (Re) as the main alloying element are very expensive. The other reason is their poor deformability. The key solution is therefore to develop low-cost heat -resistant wrought alloys."

Jan 1, 2012

By H. Forrest

Lead smelting at Cookson Industrial Materials was formerly carried out using a combination of Blast and Reverberatory Furnaces. In the late 70' s these furnaces were replaced by two 20 tonne capacity Rotary Furnaces. This furnace type has proved to be more flexible in the range of feedstock that can be processed, including lead drosses, battery plate and even whole batteries. High rates of production have been achieved whilst attaining a good level of environmental control. The majority of the sulphur in the feedstock can be fixed by use of appropriate fluxes.

Jan 1, 1990

By G. Roderick Eggert

Material criticality reflects the degree to which a raw material is both necessary and subject to supply-chain risks. This study compares the criticality of selected raw materials from the differing perspectives of the manufacturing sectors of China, the European Union, Japan and the United States.

By W. C. Hellyer

The papers in this section provide several examples of the application of Process Mineralogy to metallurgical problems. Any experienced metallurgist could cite numerous other examples when process mineralogy has, or could have, provided data of value in his understanding of metallurgical processes. The data developed by mineralogic techniques may supplement conventional chemical analyses, but cannot be replaced by assays. Mineralogic and chemical analyses each provide different types of information. In order for the process mineralogist to interpret his results in the most useful manner, it is desirable that he should have some knowledge of metallurgical processes. Conversely, the metallurgist should have some knowledge of mineralogic techniques to understand the scope and limitations. Mineralogic examinations are time-consuming and expensive. To ensure the effort is not wasted, and indeed does not generate misleading information, the utmost care must be taken at every stage of sampling and sample preparation. The mineralogist may examine microscopically or by x-ray diffraction a one-gram sample representing a flow of possibly thousands of tons per day through a concentrator. Conditions in a concentrator change continually in response to changes in feed rate, feed characteristics, grind, reagent additions, temperature, circulating loads, etc. Lengthy sampling periods are required to ensure the samples examined are representative of average conditions. The sampling program should be drawn up jointly by the metallurgist and mineralogist. Sampling points should be selected with a view to ease of sample cutting. The sampler should be instructed in the method of cutting the samples, the weight or volume of sample to be taken at each cut, the sampling frequency, and sampling period. The sampling period required depends on the scope of the investigation. For example, if a complete survey is to be made of all final and intermediate products of a flotation concentrator, samples should be cut at not more than two-hour intervals, twenty-four hours per day, for not less than one week. For a more limited investigation of one circuit or one section of a concentrator, 'the sampling frequency could be increased to every hour and the sampling period reduced to one or two days.

Jan 1, 1981

By Norberto Benitez, Christian Ludwig, Simona Regenspurg, Fabian Mendez

"Navarro is the main garbage dump in the city of Cali (Colombia). Operated since the late 1960s it collects about 1.600 tons of waste daily. The environment surrounding Navarro is highly contaminated and the pollutants released by the dump threaten human health in the adjoining neighborhoods. The goal of our project is to identify major pollutants released from the dump and their distribution in the surrounding ecosystem. In a first phase of the sampling and analysis program landfill leachate was collected and screened for heavy metals and for the most common persistent organic pollutants. This allowed us to identify the most relevant compounds on which we focused in a more detailed second phase investigation. These compounds were quantified in the vicinity of the landfill (groundwater, surface water, drinking water and soil) to get information on their mobility and possible pathways into the human body.IntroductionThe usual technique of waste disposal in most developing countries is by landfilling on not -, or not well controlled sites, where people live close by or even on the waste itself. A typical example for this practice is Navarro, the main garbage dump in the city of Cali (Colombia). Operated since the late 1960s it now consists of about 23 million tons of household and industrial waste. The dump is located on a wetland in the riverbed of the Cauca River, the main drinking water source for Cali. Two ponds of unknown permeability located next to the landfill collect a fraction of the waste leachate. During the rainy season, the ponds frequently overflow and drain into the soil (alluvial, loamy sediments) of surrounding sugar cane fields. The environment of Navarro is assumed to be highly polluted and there is evidence that it affects the health of nearby inhabitants. Specifically, the incidence of respiratory diseases was higher among vulnerable individuals (<3 and >50 years old) living in a <3 km perimeter of Navarro as compared with a control group (Solano et al., 2006). Further, a clustering of extremely rare congenital malformations (sirenomelias and cyclops) was observed in a small area during a short time period (<6 months) (Filigrana et al., 2008)."

Jan 1, 2008

By L. N. Ertzeva

The present work is dedicated to investigation of the sulfidizing process of ore pyrrhotite concentrate with recovery of a sulfide material, enriched with non-ferrous metals, and waste pyrite, with downstream separation by a certain beneficiation method.

Jan 1, 2006

By P. M. Pincheira Brown

The widely accepted inverse relationship between copper prices ail stocks, has been commonly used by analysts to explain the behavior of the copper market and to forecast film copper pries. However, empirical data have not shown such a clear relationship between copper prices and stacks. Existing evidence only indicates a weak tong-nut relationship that vanishes in some periods. In this paper a simple comprehensive model is provided which explains both parallel and opposite direction movements between prices and stocks. Former are explained mainly by stocks demand expansions-contractions while the latter are in essence due to increases in the supply curve. Furthermore, econometric estimations are provided, thus giving a powerful tool to forecast and explain price developments of the copper market.

Jan 1, 1999