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Abstract
A technique is described for the solvent extraction of zirconium. In this method, zirconium has been extracted quantitatively from 0.005 M sodium salicylate solution at pH 2.5 - 3 using 0.01 M triphenylphosphine oxide dissolved in toluene as an extradant. Zirconium has also been recovered quantitatively from 0.2 M potassium thiocyanate solution, but extractions in nitric and hydrochloric acids (as media) were negligible. The resulting extracted metal ion has been stripped with sulfuric acid (0.5 M) and determined with inductively coupled plasma atomic emission spectrometry. This method has been applied successfully to achieve 95% recovery of zirconium from zircon concentrate.
Key words: Zirconium, Solvent extraction, Triphenylphosphine oxide, Thiocyanate, Salicylate
Introduction
Zircon is the most important commercial source of zirconium and its compounds and alloys. Zircon occurs as a common mineral in pegmatites, particularly in syenitic and granitic pegmatites and granites, diorites and gneisses. Zircon, as a heavy mineral very resistant to chemical decomposition and erosion, is concentrated with other heavy resistant minerals in placer deposits, principally in river and beach sands. Large commercial detrital deposits are found in Australia, South Africa, Brazil, Ceylon, India, Madagascar, US A and Egypt. Zircon is commonly associated with other heavy minerals, such as illmenite, magnetite, monazite and rutile (Abdel-Rehim, 1974 a,b; AbdelRehim, 2002 a,b; Abdel-Rehim, 2005; Stanley and Lafond, 1975).
Several methods have been used for the industrial processing of zircon to extract zirconium and produce zirconium dioxide and tetrachloride (Bidaye and Venkatachalan, 1999; Doyle and Duyvesteyn, 1982; Habashi, 1999; Welham, 2000).
Zirconium is used in the nuclear industry, due to its excellent corrosion resistance and low neutron cross-section. Organophosphorus compounds, namely TBP and D2EHPA, have been extensively employed in the solvent extraction studies of Zr (IV). Leviti and Freund (1956) have studied the extraction of Zr (IV) from hydrochloric acid solutions by TBP and suggested that ZrCl4-2S is the extracting species. Solvent extraction studies of Zr (IV) from chloride solutions by TOPO have indicated that the species are extracted into the organic phase as disolvates (Sato, 1982). The extraction behavior of Zr (IV) from aged chloride solutions by di-(2-ethyl hexyl) phosphoric acid (D2EHPA) has been investigated by Biswas and Hayat (2002).
A literature survey in this subject reveals that triocty lamine (TOA) has been used to...