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By W. Gong

Their outstanding thermal stability and high energy product make Sm(Co,Fe,Cu,Zr),-type alloys attractive for advanced applications. The near net-shape production of Sm(Co,Fe,Cu,Zr), bonded magnets make them potentially superior to any magnets made by sintering. Although pioneering work done by Shimoda et al. and other investigators provide insights on the proper compositions and process control of this alloy system, additional work is still necessary to improve our understanding of alloy behavior at various processing stages and to increase the production yield during powder processing. In this paper we report on the development of anisotropic Sm(Co,Fe,Cu,Zr), alloy powders for the bonded magnet application. Our focus is on the development of a moderate coercivity powder requiring a relatively low magnetizing field to charge the magnets to their optimum Br, Hci and BHmax. The magnetic properties are related to the evolution of the microstructure at various processing stages and the average particle size and size distribution of powders.

Jan 1, 1997

By Annette Revet

Aluminum fluxes have been used for the remelting of secondary aluminum since the beginning of the recycling industry. During the last sixty years, a number of fluxes have been designed, researched and tested at the laboratory and plant scale. Fluxes are primarily a mixture of potassium chloride and sodium chloride with the addition of some other chloride and fluoride containing salts. The conventional Mining methods of potassium chloride and sodium chloride yield products that are not high in purity without costly reprocessing or additional refining. In 1993, Kalium Chemicals, Ltd. began supplying flux mixtures to the aluminum industry. Kalium produces potassium chloride and sodium chloride which are mined and refined by a patented solution-mining process. The salts produced by this process are high in purity with lower concentrations of iron oxide, sulfates, and other impurities. This paper will present the different mining methods used in the production of sodium chloride and potassium chloride. The paper Will address how these mining methods affect the purity of the final product as well as the effect of purity on the performance of the fluxing salt.

Jan 1, 1995

By A. P. Paiva

With the aim of establishing a valuable alternative to the conventional methods, studies regarding the recovery of precious metals by solvent extraction have been increasing over the past few years. In this work, the selectivity of extraction presented by Cyanex 471X toward silver is investigated. Simulated chloride solutions considering contents of iron and copper usually present in actual leaching practice were used. The characterization of the aqueous solutions - in terms of the multiple equilibria established by the chlorocomplexes of the different metals and their relation to the total chloride concentration of the base-electrolyte - was successfully carried out by cyclic voltammetry. The results obtained support the important contribution of the electrochemical techniques for the understanding of the overall extraction phenomena.

Jan 1, 1994

By G. Bjorling

After complete dissolution of chalcopyrite concentrate in sulphuric acid in presence of nitric acid the excess of the latter is expelled by a surplus of concentrate and the last traces of nitrate removed in the mother liquor after crystallization of the copper and iron sulphates. Zinc accumulates in the mother liquor from which it can be removed by solvent extraction of zinc sulphate as a pair of ions. After dissolution of the sulphate crystals in water the neutral solution is oxidized in an autoclave at 140°C where iron sulphate is thermally hydrolyzed; the iron-free solution is taken to copper electrowinning and the cell acid after partial evaporation recirculated with the mother liquor to the leaching circuit. Total recovery of copper is about 96%; other metals like zinc and iron are concentrated in industrially usable products. At a copper price of about 70 c/lb, the method appears to be profitable also in a small unit.

Jan 1, 1976

By Daniel Adolfsson, Ryan Robinson, Fenwei Su, Jelena Blagojevic

"Cold bonded briquetting of steel plant by-products has proven to be a viable recycling alternative concerning technology, economy and environment in both the traditional blast furnace route and the direct reduction process. A critical parameter in cold bonded briquettes is the type and amount of binder used during production. The binder material must meet certain quality requirements concerning low and high temperature strength, chemistry and economy. Currently, SSAB Tunnplåt uses ordinary Portland cement (OPC) as binder in their cold bonded briquettes. In order to improve binder quality and possibly decrease OPC dependency, a binder feasibility study has been conducted concerning an internal by-product, ladle slag, as a supplement and/or partial substitute for OPC. Several characterization techniques have been used to study the behaviour of ladle slag, these include: XRD, XRF, SEM, glass content analysis, calorimetric analysis, particle size distribution and thermochemical stability considerations concerning the CaO-Al2O3-SiO2 system.IntroductionRecently, a project was initiated at SSAB Tunnplåt AB, in Sweden, which aimed at reducing the amount of ordinary Portland cement (OPC) as hydraulic binder in cold bonded briquettes by partly replacing it with ladle slag. OPC is traditionally used within civil engineering, and widely accepted as a hydraulic binder in a number of different applications. OPC consists of four major crystalline phases, i.e. C3S, C2S, C3A and C4AF. Tricalcium aluminate as well as the ferrite phase in OPC reacts very quickly with water, for this reason gypsum is added to the clinker in order to retard these reactions. The fact that gypsum is present in the system limits the recycling of briquettes to the BOF, since the presence of gypsum during steelmaking results in a significant amount of sulphur emissions. The latter along with the expense that follows, makes it worthwhile to consider alternatives for OPC as binder in cold bonded briquettes."

Jan 1, 2008

By Steve Johnston, Mowafak Al-Jassim, Fei Yan, Omar Sidelkheir, Alain Blosse, Katherine Zaunbrecher

"Imaging techniques are applied to multi-crystalline silicon wafers and solar cells throughout the production process. Photoluminescence imaging, both band-to-band and defect-band, is used to characterize defects and wafer quality at all process steps. These steps include bricks sawn from ingots, wafer sawing, cleaning and texturing, emitter diffusion, edge isolation and glass removal, anti-reflective coating/passivation, and metallization of finished cells. Bricks, wafers, and cells can be imaged at a rate commensurate with in-line measurement, giving spatial information to characterize quality and defect content. Photoluminescence images on silicon bricks can be correlated to lifetime measured by photoconductive decay and could be used for high-resolution characterization of material before wafers are cut. The defect areas in as-cut wafers are compared to imaging results from electroluminescence and lock-in thermography, and cell parameters of near-neighbor finished cells, showing correlations to efficiency, open-circuit voltage, and short-circuit current.IntroductionImaging techniques can rapidly characterize material quality and defect density. Photoluminescence (PL) imaging can be applied to silicon from the brick level to all wafer process steps [1-8]. At the brick level, material thickness allows for measurement and correlation to lifetime where surface recombination effects are minimized [6, 7]. At the as-cut wafer level where thin unpassivated wafers prevent accurate lifetime assessment due to surfaces, defects can still be categorized and quantified to predict finished cell performance [3-5]. Defect regions can be identified by recombination-limited band-to-band PL or by defect-band emission [9-12]."

Jan 1, 2012

By William A. Hockings

Methods for the measurement of liberation of finely ground iron ores are described. The general method consists of separating a sample of the ground ore into a number of size fractions, followed by measuring the liberation of each fraction. The size separation has been done using electro-formed screens of 20-, 10-and 5-micrometer apertures, and also by air elutriation. Liberation (i.e., the distribution of compositions of individual particles) has been measured by optical microscopy. A computer pro-gram was used to adjust the raw count data so that it agrees with the chemical analyses of the size fractions. Various ways of presenting the results are given, and Some applications of the results to flotation processing are discussed.

Jan 1, 1981

By John Hollow

The Fort Knox Mine is an open-pit operation, located in Alaska, which started commercial production in March 1997. A conventional Mill processes 38,000 tpd of a low grade (1.0 g/t Au) free milling gold ore with a low sulphide component (below 1%). Gold production (11% from gravity and 89% from cyanidation) exceeds 400,000 ounces per year. Short retention time (20h), low temperature (7oC) and low grade make high leaching kinetics critical for the performance of the process. In April 2001, the treatment of True North ore, which represented 14.4% of the mill throughput and contained more sulphide in the form of pyrite, arsenopyrite and stibnite, resulted in a substantial drop in the average gold extraction from 87% to 72.6%. Laboratory investigations indicated that the addition of lead nitrate increased gold extraction to 91.7%. Further investigations were initiated to determine the leaching parameters and the nature of the problem. Subsequently, a lead nitrate addition scheme was implemented at the Fort Knox Mill that resulted in 2002 gold production being in excess of 31,000 ounces higher than that estimated for the non-lead nitrate reagent scheme. This paper presents the results of laboratory investigations and modifications in plant operating practices.

Jan 1, 2003

By Zhijing Zhang

Sodium borosilicate is the basic composition of coating materials, Vycor and Pyrex glasses. In the present study, viscosities of Na2O-Si02-B2O3 ternary melts were measured under various compositions and temperatures. Experiments were carried out using rotary viscometer and graphite components. Our experimental results were compared with those in literature. Based on present experimental results, the previous structure based viscosity model was modified. The predicted viscosity results are in excellent agreement with the present experimental data in the temperature range with molten state samples. The fitting ranges of the model cover the composition of XB2O3 from 0.1 to 0.6 combined with xSio2 / xNa2O = 0.5, 1,2 and 5 respectively.

Jan 1, 1998

By Laurent Cohen

Since the 1970s, Solvent Extraction (SX) in hydrometallurgical processes has been a key enabling technology in the production of high-purity metals. Examples include copper, rare earth oxides, uranium, cobalt and nickel. Notwithstanding incremental improvements in extractant formulations, few breakthroughs can be recounted in this industry outside of the initial amine-, oxime- or phosphine-based reagent chemistries. However, the advent of lithium-ion batteries and their stringent requirements for critical materials (lithium, cobalt and nickel) offer new challenges and opportunities for SX. Solvay recently introduced a new extractant for lithium, CYANEX® 936, and developed unique modeling software capabilities in cobalt/nickel separation using CYANEX® 272, zinc SX using DEHPA® and rare earth separations using CYANEX® 572. This paper discusses trends in SX and provides insight on processing of critical materials essential to energy sources. It also summarizes the technical and economic benefits based on extractant selection and advances in modeling.

By Sebastiaan Peelman

NdFeB permanent magnets are the best available magnets used in many technology applications. However, at their end-of-life (EoL) most of magnets and the contained REEs are lost during the recycling of the bulk metals. The REEs are classified as the most critical raw materials in the European Union, and recycling of REEs from EoL products will reduce their criticality and contribute to the sustainability of REE. Various technological routes have been reported, but most of the methods are effective for highly concentrated magnets or magnet scrap, which is greatly dependent on expensive pre-dismantling processes. This paper presents various innovative metallurgical solutions to the effective REE recovery from current industrial practice for WEEE recycling, including the ferrous scrap from WEEE shredder products and shredder residues from computer hard disk drives. Both hydrometallurgical and combined hydro- and pyrometallurgical REE recovery routes are developed after demagnetization and physical upgrading.

By K. S. Kawatra

In recent years, there have been several efforts to develop binder mixtures for iron ore pelletization. Some efforts have been fruitful, while others have encountered failure. For example, adding corn starch to bentonite is effective, while adding fly ash to bentonite is not. When binders are made with fly ash, a pozzolanic reaction occurs, but no such reaction occurs when bentonite and corn starch are used together. The authors analyzed which binders can be mixed, and which binders will succeed. The authors confirmed this analysis with several laboratory and plant studies. This paper presents this critical analysis, along with various combinations of binders for making Iron Ore Pellets.

By Jay R. Hitchings

A technique that enables excellent color photograph production from black and white negatives of electron microprobe x-ray images is described in this paper. The photographs are made by superimposing one, two or three negatives of black and white x-ray images individually through assigned primary color filters directly onto color print paper. When used to examine metallurgical or geological microstructures, the resulting color photograph provides detailed, qualitative information about spatial arrangements, elemental associations and relative concentrations of at least three elements. The technique is simple and straightforward, requiring only standard darkroom equipment. The use of color to display or present complicated microprobe data also allows a non-technical reader or audience to better understand the data.

Jan 1, 1981

By M. Giralico

Optimized mixer settler designs will now handle flows of over 25,000 GPM. The size and expense of the equipment hamper experimental settler optimization efforts. Computational Fluid Dynamics (CFD) is a timely and predictable tool for settler design development. In the past, CFD has been used to evaluate only the flow field in pumped and auxiliary tanks. A similar numerical analysis is used to evaluate settler flow and phase separation. Phase separation is analyzed using multiple species for the aqueous and organic phase. Experimental validation shows good agreement between the computational and experimental solutions in both flow field and phase separation. The computational model is used to show performance differences between various choices of settler geometry, liquid depth, with variable flow rates. Understanding the differences allows the development of optimized settler designs. System improvements are predicted to lower entrainment levels further and/or allow new smaller footprint designs. This paper focuses on the major design components of the settler and how future technological advances will lead to further improvements in their design. LIGHTNIN?s new designs will handle tomorrow?s production requirements, while maximizing profits.

Jan 1, 2003

By He De-wen

The increasing population and living standard in urban areas, have been accompanied with the growing quantity and composition complexity of rubbish, which are causing well-known social effects of pollution, while rubbish (solid waste) is a recyclable resource. To convert rubbish into useful materials, the essential measure is to carry out sorted collection of rubbish. The preconditions of implementing sorted collection are presented in the paper. 1 Characteristics of rubbish composition and amounts of recyclable contents are basic condition to implement sorted collection. 2 The existing available technologies of recycling, economic benefit from recycling, and disposal scheme of residual rubbish are restrained condition for sorted collection. 3 Public understanding and support to sorted collection are the key to success. 4 The government policies to be favorable for sorted collection is the pledge of success. 5 The establishment of a steady solid waste recycling market is also a guarantee to implement sorted collection continuously. 6 To establish management system of rubbish recycling as soon as possible. Further, the methods and procedure of sorted collection are discussed in detail and beneficial comments and theoretical basis to promote sorted collection of rubbish in urban area are presented; it will contribute reference value to municipal solid waste management.

Jan 1, 2006

By Ana P. Paiva, Marc F. Comella, Sandra S. Reis, Joao N. Reis, M. Soledade Santos

"In this work, the influence of the malonamide structure, acidity of the aqueous phase and diluent on the equilibrium interfacial tension (IT) of N,N'-dimethyl-N,N'-diphenylmalonamide (DMDPHMA) and N,N'-dimethyl-N,N'-dicyclohexylmalonamide (DMDCHMA) in 1,2- dichloroethane (1,2-DCE), and DMDCHMA in toluene, with aqueous HCl, were investigated. IT isotherms were determined using the Du N ouy ring method. Densities of the organic phases were determined, and used to screen solute-diluent interactions. Formation of third phases was never observed; furthermore, ITs increase with the phase separation period, constant values being obtained for separation periods larger than 1000 seconds. Each malonamide interfacial efficiency at the oil/water interface is interpreted in terms of malonamide basicity, diluent polarity and malonamide - hydrochloric acid- diluent interfacial interactions.IntroductionFor several years now, N,N'-tetrasubstituted malonamide derivatives have been extensively investigated as liquid-liquid extraction agents since they were first proposed as the organic components of the DIAMEX process, with the aim of advantageously replacing tributylphosphate in PUREX [1]. Therefore, a significant part of research studies with malonamides appearing in the literature deal with the extraction of major and minor actinides in real or simulated spent nuclear fuels in nitric acid solutions [2]. Under typical experimental process conditions, the tendency shown by some N,N'-tetrasubstituted malonamide derivatives to aggregate in the organic phase, leading in a few cases to the formation of undesirable third phases, has been remarked and consequently thoroughly investigated [3, 4]. The increasing use of chloride streams as hydrometallurgical aqueous feeds is becoming a reality, and this fact is obviously deeply founded on an extensive research carried out to recover value-adding metals from these media. Following this trend, a number of N,N'-tetrasubstituted malonamides have already been screened for the recovery of iron(III) [5, 6] and platinum-group metals [7] from hydrochloric acid solutions. The results obtained are quite promising either in terms of total metal ion recoveries or selectivity patterns achieved. The formation of a third phase when iron(III) was extracted by the tested N,N'-tetrasubstituted malonamide derivatives has never been observed under the adopted experimental conditions, and the extraction data collected would need to be reinterpreted accordingly if any aggregation phenomena involving the considered extraction systems were to take place."

Jan 1, 2011

By Shunli Zhang

Metals recovery from electronic scrap by physical separation may provide an alternative to the current recycling approach, through which halogenated flame retardants can result in hazardous dibenzo-p-dioxins and dibenzo-furans. On the basis of a complete sink-float analysis of personal computer and printed circuit board scrap, and in view of the advantages of dry processes for electronic scrap recycling by mechanical separation, air table separation is prioritized in an attempt to separate metals from plastics and glass involved. In the present paper, theoretical and practical considerations of air table separation have been detailed. It has been shown that air table separation is effective for recovering copper and precious metals from this specific waste stream. With the feed rate of 60 kg per hour, the combined grade and recovery of copper, gold, and silver attainable for the two heavy products produced by the air table used in the present study was shown in the following table:

Jan 1, 1998

By O. G. Yeremin

The Joint Venture "Inter-S" jointly with the Gintsvetmet Institute have developed a technology for manufacturing of sulphoconcrete and sulphoasphalt. The sulphoconcrete manufacturing technology comprises preliminary production of modified sulphur, which is blended in liquid form at a temperature of 120°C with an inert material preheated to the same temperature. The second promising area for the use of sulphur is partial substitution of modified sulphur for more expensive bitumen. The sulphoasphalt manufacturing process comprises preliminary production of a sulphur and bitumen mixture with a sulphur content of 30% to 40%, which is then blended with inert materials using conventional techniques. Sulphoasphalt manufactured at a full-scale plant meets all requirements set to its strength properties for road paving. Technology has been developed for production of high-purity sulphur based on rectification of liquid sulphur in a packed column. A commercial-scale plant with a capacity of up to 15 tonnes per year for production of sulphur with an impurities level of about 110-6 % by mass has been put into operation.

Jan 1, 2006

By M. Rubinstein, N. C. Koon, B. N. Das, V. G. Harris

"Copper and gold - based alloys having giant magnetoresistance properties were produced by melt spinning from arc melted and cast rods. The ribbon width varied between 1 and 2 mm and the ribbon thicknesses were in the range of 30 to 50 11m. The uniform microstructure of the cast rods indicated the composition homogeneity in the starting material. The ribbons showed composition uniformity across the cross section from EDX analysis. However, the spun ribbon microstructure changed from a 'frozen in' region near the wheel side to a nanosize spherically precipitated phase towards the freely frozen surface. The evolution of the microstructure from the spun ribbon state to the annealed ones was studied by optical microscopy, SEM and TEM. The structural information of the spun and annealed specimens was obtained from X - ray, electron diffraction, electron microscopy and ferromagnetic resonance. Magnetoresistance was measured by the four point probe method.IntroductionRecently. Giant Magnetoresistance. GMR. has been observed in sputtered thin films alloys of Ag. Au and Cu with Co and Fe [1. 2. 3]. The sputtered films are produced by condensation of the alloys from the vapor phase. These Ag. Au and Cu alloys are miscible and homogeneous in the vapor and liquid phase (except Ag alloys which exhibit phase separation even in the liquid phase) but immiscible and heterogeneous in the solid phase. In our work we have produced thin ribbons of the Cu and Au alloys about 30 µm thick from the miscible state in liquid phase by rapid solidification melt spinning. The microstructural development of the ribbons was investigated in the as - spun condition and on annealing. The other properties such as magnetization. GMR and Mossbauer Spectroscopy were also investigated in the various microstructural conditions of the ribbons."

Jan 1, 1994

By Yi Feng Shi

The ISASMELT process is a submerged lance smelting technology operating in smelters in Australia, the USA, Belgium, India, Germany, Malaysia and China. Further plants are under construction in Peru and Zambia. Initially developed at Mount Isa Mines, Australia, the technology is marketed by Xstrata Technology to companies around the world. Yunnan Copper Co. Ltd. (YCC) commissioned the first copper ISASMELT furnace in China in 2002. The plant quickly ramped up to design capacity and the first campaign lasted more than 2 years. Now into the second campaign, the furnace is exceeding the original design capacity and YCC has won numerous awards for its contribution to reducing emissions and energy consumption. YCC and Xstrata put great effort into managing the design, construction and commissioning of the smelter. Xstrata?s technology was combined with YCC?s novel management approach. This effort has been repaid in terms of the outstanding performance of the plant since startup. This paper updates the reader on the first few years? operation of the YCC ISASMELT plant and discusses the way in which the technology was transferred, leading to fast rampup and, as a result, enhanced profitability for the operators.

Jan 1, 2006