Novel Membrane-Based Synergistic Metal Extraction and Recovery Processes

Abstract

Individual metal recovery and separation by solvent extraction has been an important technique in pollution control as well as in hydrometallurgical processes. Synergistic extraction and separation of two cations, e.g., Cu(II) and Zn(II), a cation and an anion, e.g., Cu(II) and Cr(VI), and two cations and one anion, such as Cu(II), Zn(II), and Cr(VI), have been demonstrated employing a novel hydrophobic microporous hollow fiber membrane-based (HFM) extraction technique. The extraction selectivity of Cu(II) and Zn(II) by LIX 84 (anti-2-hydroxy-5-nonylacetophenone oxime) and bis(2-ethylhexyl)phosphoric acid (D2EHPA), respectively, in a two-fiber-set HFM extractor is significantly enhanced due to competitive extraction. The efficiencies of extraction of Cu(II) and Cr(VI) by LIX 84 and tri-n-octylamine (TOA), respectively, are increased due to the self-control of the aqueous feed pH. A simplified mathematical model for synergistic extraction of Cu(II) and Zn(II) has been developed. The model predicts the observed extraction and separation performance well. In the novel HFM extractor, the extraction rates of Zn(II) and Cu(II) by D2EHPA and LIX 84, respectively, were controlled by the aqueous and organic boundary layer resistances as well as the interfacial reaction resistances.

Application of Hollow Fiber Membrane Contactors for Catalyst Recovery in the WPO Process

“…The dynamic response of the system is determined by solving a system of differential equations that describe the evolution of the concentration of Cu in the feed, organic, and stripping phases when flowing along the extraction and stripping modules, together with the mass balances for the three tanks considered as ideal stirred vessels. Several references dealing with the mathematical description of metal separation and recovery using NDSX technology are referenced 11–15,18…”

“…Several references dealing with the mathematical description of metal separation and recovery using NDSX technology are referenced. [11][12][13][14][15]18 The assumption of kinetic control of the interfacial reaction shared with mass transfer resistance in the fluid phase circulating through the inner side of the hollow fibers has led to the determination of representative mathematical models for the separation flux and velocity of copper recovery processes. 15,16 However, in this work, as a first attempt, the development of a kinetic model was carried out following the same procedure previously employed by the authors for the recovery of various metallic systems.…”

Kinetic Modeling of Simultaneous Recovery of Metallic Cations and Anions with a Mixture of Extractants in Hollow-Fiber Modules

“…Yang et al used a module containing two sets of hollow fibers to separate and extract Cu 2+ and CrO 4 2-from aqueous solutions. 28 The aqueous phase flowed on the shell side in their experiments. One organic solution containing the acidic extractant LIX84 flowed through the bore of fiber set 1, and the other solution containing the basic extractant tri-n-octylamine flowed in fiber set 2.…”

Integrated membrane process for gold recovery from hydrometallurgical solutions

“…9, and k, is the effective rate of interfacial reaction at the surface: kf, k,, and k, are the mass-transfer coefficients in the aqueous feed, membrane, and the organic solvent, respectively; di, D,, and dl,, respectively, are the internal, external, and logarithmic mean fiber diameters. Equation 9 was derived to estimate the value of k j similar to the methods published in the literature (Yun et al, 1993;Yang et al, 1996Yang et al, , 2000. The first term on the righthand side of Eq.…”