A Process for the Separation of Noble Metals from HCl Liquor Containing Gold(III), Palladium(II), Platinum(IV), Rhodium(III), and Iridium(IV) by Solvent Extraction

Abstract

The demand for noble metals is increasing, owing to their excellent chemical and physical properties. In order to meet the demand, the recovery of noble metals with high purity from diverse secondary resources, which contain small amounts of noble metals, is of immense value. In this work, the possibility of the separation of Au(III), Pd(II), Pt(IV), Rh(III), and Ir(IV) by solvent extraction from a synthetic HCl solution is investigated. Only Au(III) was selectively extracted by Cyanex 272 in the HCl concentration range from 0.5 M to 9 M, leaving the other metal ions in the raffinate. The loaded Au(III) in Cyanex 272 was efficiently stripped by (NH2)2CS. The other four noble metals were sequentially separated on the basis of the procedures reported in the previous work. The mass balance showed that about 98% of each metal, except Pt(IV), was recovered by the proposed process. An efficient process for the recovery of the five noble metal ions from the HCl leaching solution of secondary resources containing these metals can be developed.

Review on the Comparison of the Chemical Reactivity of Cyanex 272, Cyanex 301 and Cyanex 302 for Their Application to Metal Separation from Acid Media

“…By contrast, Cyanex 272 contains oxygen which is considered to be a hard base and thus is less attractive to Pd(II). Au(III) was selectively extracted by Cyanex 272 in the HCl concentration range of 0.5 to 9 M, whereas Pd(II), Pt(IV), Rh(III) and Ir(IV) are not extracted at all [3]. Cyanex 301 was employed to separate Pd(II) over Pt(IV) from hydrochloric acid solutions [33].…”

“…The advantages of Cyanex extractants over other extractants are a high loading capacity and selectivity from diverse aqueous medium. For example, the bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) is effective in the selective extraction of cobalt and nickel from sulfate and chloride media as well as gold and rare earth elements [2][3][4]. Cyanex 301 (the main constituent is bis(2,4,4-trimethylpentyl) dithiophosphinic acid) is suitable for extracting zinc and other heavy metals, including platinum group metals [2,5,6].…”

Insight into the Liquid–Liquid Extraction System AuCl4−/HCl/A327H+Cl− Ionic Liquid/Toluene

“…Among these, gold is significant due to both its color, and its sales price and profit potential. Thus, the separation and recovery of this precious metal, from any of the above materials, has attracted wide interest, and different separation technologies have been proposed for this task: adsorption [1,2], ion exchange [3], liquid membranes [4,5], and liquid-liquid extraction using ethers [6][7][8], amides [9], amines [10], ionic liquids [11] or phosphonic acid derivatives [12].…”

Insight the Liquid-Liquid Extraction System AuCl4-/HCl/A327H+Cl- Ionic Liquid/Toluene

“…Including under the term of valuable items, electronic wastes, jewelry scraps, and similar products are of interest because they contained metals, and among them, gold pointed out not only by its bright but also, due to its price, in terms of money or profits. Thus, the separation and recovery of this precious metal, from any of the above materials, focuses a wide interest, whereas different separation technologies are proposed for this task: adsorption [1,2], ion exchange [3], liquid membranes [4,5] and liquid-liquid extraction using ethers [6][7][8], amides [9], amines [10], ionic liquids [11] or phosphinic acid derivatives [12].…”