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Recovery from Recycling: E-Wastes (Geridönüşümden Kazanmak: E-Atıklar)
In the solvent extraction separation of Platinum Group Metals (PGM) from industrial chloride liquors, the presence of impurity elements may cause processing complications as they tend to coextract. Strip solution contamination may be an obvious occurence as well as buildup in the organic phase and third phase formation. In order to design scrubbing stages for their removal or to avoid coextraction altogether, it is important to have a solid understanding of the chloro-chemistry of the impurity elements. In addition, reviewing the chloride solvent extraction systems previously investigated provides additional information for process design. The review covers the elements Cu, Fe, Ni, Zn, Pb, Sn, Ag, As, Sb, Bi, Se and Te. Most elements exhibit anionic chlorocomplexation in HCl medium at >1.0 M and this is why they extract via an ion-pair formation mechanism with strong basic extractants (amines)as well as weaker ones (TBP, TOPO, 8-hydroxyquinoline)
In this study, physical, chemical and hazardous characteristics of computer printed circuit boards (PCBs) were studied. PCBs manually obtained from end-of-life computers of various brands were subjected to size reduction down to -3.35 mm in two stages of crushing. Size fractions were obtained by dry-sieving and used to determine the liberation size of metals. Furthermore, hazardous characteristics of PCBs were investigated using standard protocols including TCLP (Toxicity Characteristic Leaching Procedure) and SPLP (Synthetic Precipitation Leaching Procedure) tests of US Environmental Agency (USEPA), ASTM D-3987 and EN 12457-2 tests to simulate different environmental scenario. The tests have shown that printed circuit boards can be classified as hazardous wastes. Copper content of PCBs was found to be 15.5 per cent. © (2010) by the Australasian Institute for Mining and Metallurgy (AusIMM).
The efficient recovery of precious and special metals from electronic scrap has significant benefits - economically, environmentally, but also under a resource conservation aspect. The yields of these metals could be substantially improved by higher collection rates, less scrap exports to regions with insufficient recycling structures, and by interface optimisation, as pointed out in this document
A study was made on the dissolution kinetics of metallic copper flat packs using solutions of Cu(II) in a chloride medium which was obtained via reaction between copper sulfate and sodium chloride. The effect of stirring, chloride and Cu(II) concentrations, distribution of Cu(II) chlorocomplexes and temperature were investigated.The leaching data showed the reaction to be under chemical kinetics control, with an activation energy of 28 kJ/mol (7 kcal/mol). Leaching occurred at an apparent order of −1 with respect to the total chloride concentration and an apparent first order with respect to the total copper concentration. The Cu(II) ion was the main active species based on calculation of copper species distribution and the solution kinetics may be interpreted as rate=k[Cu2+]. For ratios of CCl/CCu2+ of less than about 8, a layer of CuCl(s) formed which impeded the solubilization process.
After a brief introduction, describing the domain of Aqueous Processing from both a scientificand an application point of view, the paper embarks to demonstrate how product/process innovation becomes possible through a clear understanding of chemistry. To this end, a broad range of examples of industrial process innovations achieved through an ingenious application of Aqueous Processing are presented. Following that, the paper giveshighlights of some of our own research, exemplifyingthe importance of understanding the chemistry at the ionic scale and at the same time, thinking of the problem/process system as a whole. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier ScienceLtd. All rights reserved.
Résumé
Après une brève introduction décrivant le domaine du traitement aqueux tant due point de vue scientifique que pratique, l'article entreprend de démontrer comment l'innoyation de produit/procédé devient possible par l'intermédiaire d'une compréhension claire de la chimie. À cette fin, on présente une grande variété d'exemples d'innovations de procédé industriel obtenues par une application ingénieuse du traitement aqueux. Après cela, l'article presente les principaux points d'une partie de notre propre recherche, exemplifiant l'importance de la comprehension de la chimie à l'echelle ionique tout en pensant, en meme temps, au système problème/procédé comme un tout. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.
Smoothed tables of the solubility of CuCl in aqueous HCl and aqueous NaCl from 0.01 to 6.0 M and from 0 to 100 °C are presented. Similar tables are given, for 25°C only, for mixtures of HCl and NaCl, and for solutions in aqueous KCl, NH4Cl, CuCl2, and FeCl2. The procedures and parameters necessary for calculation of the solubility at other concentrations and temperatures are given. Simple methods for handling solubility in complex mixtures and in cases where experimental information is scant are discussed.
The speciation, Eh-pH and Eh-log aCl- dependence of Fe(III), Fe(II), Cu(II), Cu(I), Ag(I), Pb(II), Zn(II), Ni(II), As(III), Sb(III), and Bi(III) ions in practical
(high ionic strength) sulfate and chloride solutions are discussed. The emphasis is placed on those ions which form strong
sulfato-, chloro-, and hydroxo-complex species. Measured potentials are compared with potentials calculated from reported
association and stability constants to test the applicability of these constants in nonideal solutions and to characterize
predominant species.
This paper examines in detail the thermodynamics and application of chloride metallurgy for the extraction of precious metals,
such as gold and silver, and platinum-group metals. The advantages with regard to the solubilities of metal ion species and
their reduction potentials in chloride media are discussed with examples. The use of chloride media for the extraction of
platinum-group metals from spent autocatalysts and for the production of high-purity pigment-grade TiO2 and titanium metal from ilmenite feed stocks is discussed in the case studies provided.