Dispersion-Free Solvent Extraction and Stripping of Gold Cyanide with LIX79 Using Hollow Fiber Contactors:  Optimization and Modeling

Abstract

This paper reports experimental data on hollow fiber dispersion-free membrane extraction (DFSX) of gold(I) from alkaline cyanide media using microporous hydrophobic polypropylene hollow fiber contactor. A recently developed new solvent extraction reagent, namely, LIX79 (Henkel Corporation), was employed as an extractant. The DFSX operation was carried out with 12% LIX79 in n-heptane by passing alkaline feed containing gold through the tube side and organic extractant through the shell side. Extraction studies were performed under different hydrodynamic conditions and mass correlations for the tube and shell side were presented for cocurrent and countercurrent flow conditions. A model is presented that identifies the different ratecontrolling steps under various chemical and hydrodynamic experimental conditions in feed, organic, and membrane phases. The mass-transfer resistance resulting from a chemical extraction reaction at the surface was observed to be dominant during the entire extraction process. The validity of this model was evaluated with experimental data and found to tie in well with theoretical values. It was possible to separate and concentrate Au(I) (up to 400 mg/L) in the presence of other metal cyanide salts such as Fe(II), Cu(I), Ni(II), Ag(I), and Zn(II) (NaCN ) 1000 mg/L) by employing this technique. The stripping of gold from LIX79 was accomplished efficiently by using NaOH, which flowed through the tube side (11.11 cm 3 /s) and the organic was passed through the shell side at (6.94 cm 3 /s).

Au(I) extraction by LIX-79/n-heptane using the pseudo-emulsion-based hollow-fiber strip dispersion (PEHFSD) technique

“…On the basis of previous studies performed, an aliphatic diluent, n-heptane, was selected as the diluent for the PEHFSD system [17][18][19]. Details of the hollow-fiber module and hollowfiber membrane characteristics are listed elsewhere [2].…”

“…(17) indicates that the local value of the total resistance is a sum of the local value of the total resistance is a sum of the local values of the individual resistances. Therefore, in the right hand side of Eq.…”

Treatment of Stainless Steel Rinse Waters Using Non-Dispersive Extraction and Strip Dispersion Membrane Technology

“…where D m (averaging 10 −6 cm 2 /s) is the diffusion coefficient in the organic phase [42][43][44], ε (0.3) is the membrane porosity, τ (3) is the membrane tortuosity, d m (3 × 10 −2 cm) is the membrane thickness, and d lm is the log mean diameter of the hollow fibre. Then, the calculated value of k m is 3.0 × 10 −5 cm/s.…”

“…The effective diffusion coefficient of the metals-DP8R complexes across the membrane phase can be calculated as [43,45]:…”

Pseudo-emulsion based hollow fiber with strip dispersion pertraction of iron(III) using (PJMTH+)2(SO42−) ionic liquid as carrier

“…Considering and approximate value of 10 −5 cm 2 s −1 for D a [29][30][31], then the k a value calculated from the above equation, at v a of 1.1 cm s −1 , was 1.0 × 10 −3 cm s −1 . This value is in order with typical mass transfer coefficients in aqueous solutions [32], and is greater than the average overall mass transfer coefficient K value 1.7 × 10 −4 cm s −1 , obtained from experimental data in Table 5.…”