Separation and recovery of Pd(II) and Pt(II) from cyanide liquors of Pd-Pt flotation concentrate via solvent extraction

Abstract

BACKGROUND Thus far, separation and recovery of Pd(CN)42‐ and Pt(CN)42‐ from cyanide liquors have not been reported. In this study, the process of co‐extracting and separating Pd(II) and Pt(II) over Fe(III), Cu(I), Co(III), and Ni(I) from alkaline cyanide liquors was investigated. RESULTS The results showed that almost all Pd(II) and Pt(II) (>98.0%) could be simultaneously extracted by phenoxyethyl dimethyl palmitylammonium bromide (PDPB), whereas Fe(III), Cu(I), Co(III), and Ni(I) was below 3.0% under optimum conditions. Furthermore, Pd(CN)42‐ and Pt(CN)42‐ were separated and recovered by the two‐step stripping process. First, Pd(CN)42‐ in mixed organic phase was stripped by a 2.0 mol L−1 ammonium thiocyanate solution. The stripping percentage of Pd(CN)42‐ was >98%, whereas the stripped Pt(CN)42‐ was below 1%. Second, more than 97.5% Pt(CN)42‐ in the loaded organic phase could be stripped using 1.0 mol L−1 thiodiglycol solution. Recovery ratios for both Pd(II) and Pt(II) were above 95%. The organic phase could be reused for at least 6 cycles of extraction–stripping processes. The mechanisms of extraction reaction were deduced to be ion‐association mechanisms. CONCLUSION The process could be applied for extracting and separating palladium and platinum from the cyanide leaching liquor of the flotation concentrate. © 2016 Society of Chemical Industry

Novel poly(aniline-co-3-amino-4-methoxybenzoic acid) copolymer for the separation and recovery of Pd(ii) from the leaching liquor of automotive catalysts

“…PtCl 6 2À tends to combine with fewer water molecules to constitute a smaller hydration shell, which is favorable for ion-pair formation. [37][38][39][40] Therefore, the adsorption percentage of RhCl 6 3À would be lower than that of PtCl 6…”

Extraction of Palladium(II) from Hydrochloric Acid Solutions by Solvent Extraction with Mixtures Containing Either Cyanex 301 or LIX 63

“…The concentration of Pd in the loaded mixture phase was 97 mg/L. In general, thiocyanate and thiosulfate ions are soft ligands and are usually employed as the stripping agents of Pd(II) [4,7]. Further, Pd(II) can be quantitatively stripped by acidic aqueous solutions containing thiourea [17].…”

“…Because the consumption of Pd increases each year, the recovery of this metal from either ores or secondary resources is essential. Several methods are used in the separation of Pd(II) from the leaching solutions of HCl or HNO 3 , such as precipitation [3], ion exchange [2,4], and solvent extraction [5][6][7][8][9][10][11][12]. Among these methods, solvent extraction is suitable for the separation of platinum group metals (PGMs) because of its high selectivity and the purity of metals thus obtained [9].…”

Extraction of Palladium(II) from Hydrochloric Acid Solutions by Solvent Extraction with Cationic Mixtures

“…From the Table 3, the enhancement coefficient in mixture of LIX 63 and organophosphorous extractants was less than 1. Therefore, addition of Cyanex 272/PC 88A/D2EHPA into [4,7]. Further, Pd(II) could be quantitatively stripped by acidic aqueous solutions containing thiourea [17].…”

“…Since the consumption of Pd increases each year, the recovery of this metal from either ores or secondary resources is important. Several methods are used in the separation of Pd(II) from the leaching solutions of HCl or HNO3, such as precipitation [3], ion exchange [2,4], and solvent extraction [5][6][7][8][9][10][11][12]. Among these methods, solvent extraction is suitable for the separation of platinum group metals (PGMs) due to its high selectivity and the purity of metals thus obtained [9].…”