Mathematical modeling for facilitated transport of Ge(IV) through supported liquid membrane containing Alamine 336

A mathematical model was developed for the germanium facilitated transport from a medium containing tartaric acid using Alamine 336 as a carrier. Modeling was carried out based on the extraction constant (Kext) obtained from the liquid-liquid extraction (LLX) modeling. The LLX data was achieved from experiments with conditions being Alamine 336 concentrations of 0.1-10 %v/v from a solution containing about 1.378 mmol/L Ge (100 mg/L) and tartaric acid as an anionic complexant. The LLX model was attained using the equilibrium-based procedure and fitted to extraction experimental data for various carrier concentrations. This model presented an accurate extraction constant (Kext=0.02) used in the facilitated transport modeling. The flat sheet supported liquid membrane (FSSLM) experiments were conducted in the condition of 1.378 mmol/L Ge (100 mg/L), tartaric acid concertation of 2.760 mmol/L, 1 M HCl as a stripping phase and various Alamine 336 concentrations in the range of 0 to 35 %v/v. The FSSLM model was developed according to the Fick’s law, the diffusional transport, and equilibrium equations. According to the model, mass transfer and diffusion coefficients for various concentrations of the carrier were found. In addition, the calculated and experimental values had a good correlation with together showing the validity of the model. This model can be used in the further process simulation such as hollow fiber SLMs.Peer ReviewedPostprint (author's final draft

2012, 425−439 Physicochemical Problems of Mineral Processing

Abstract. Leaching with sulfuric and hydrochloric acids for upgrading titanium slag obtained from the Qara-aghaj ilmenite concentrate to a high grade titanium dioxide (TiO 2 ) was studied. The titanium slag containing 72.7% TiO 2 and 7.8% Fe 2 O 3 was leached at varying solid/liquid (S/L) ratio, particle size, leaching time and acid concentration. The optimum amount of S/L ratio, particle size, acid concentration and leaching time using both acids were determined as 1:4, -100 m, 8% and 2 h. Under optimum conditions, by using sulfuric acid, a titanium dioxide concentrate with 86.8% TiO 2 and 1.87% Fe 2 O 3 was produced, while employing hydrochloric acid resulted in a concentrate containing 91% TiO 2 and 0.61% Fe 2 O 3 . The titanium dioxide concentrate prepared with hydrochloric acid, having acicular texture and by means of elongated separate particles; has less impurities than the one produced by sulfuric acid. The results demonstrate that hydrochloric acid dissolution of titanium slag and removing some impurities such as SiO 2 and MgO provide a product with good quality is prepared which is suitable as raw material for TiO 2 pigment production through the chloride process

Germanium transport across supported liquid membrane with Cyanex 923: Mathematical modeling

A mathematical model was developed to monitor the facilitated transport of germanium(IV) from oxalic acid solutions through a flat sheet supported liquid membrane (FSSLM) containing four trialkylphosphine oxides (Cyanex 923). The FSSLM modeling was based on the extraction constant (Kext) calculated from the liquid-liquid extraction (LLX) modeling. The LLX model presented a reliable calculation of the extraction constant (Kex= 2.057×103 L/mol4). The FSSLM model was solved using Matlab® software according to extraction constant, Fick's law, and diffusional principles. The model predicts the overall mass transfer coefficient (Korg) to be 3.84 cm/s. Using this value, diffusion coefficients (Dm) for various Cyanex 923 concentrations of 0.126, 0.252, 0.378, 0.505, 0.631 and 0.757 mol/L are found to be 8.50×10-4, 4.30×10-4, 1.87×10-4, 5.87×10-5, 2.57×10-5, 2.09×10-5 cm2/s, respectively. The results show that the diffusion rate of the current study is approximately more than that of similar FSSLM systems containing Cyanex 923 used to transport various metals. The modeling values are in good agreement with the experimental data, showing the good reliability of the mathematical model.Peer ReviewedPostprint (author's final draft

Non-dispersive selective extraction of germanium from fly ash leachates using membrane-based processes

Non-dispersive selective extraction of Ge(IV) tartrates was carried out from simulated fly ash solutions containing heavy metals through supported liquid membranes (SLM). The optimum transport was obtained using a PTFE membrane containing Alamine 336 5%v/v in the condition of tartaric acid 2.76 mmol/L and HCl 1 mol/L in feed and strip phases, respectively. Under this condition, a hollow fiber (HF) SLM experiment was conducted. The results showed that this system could transport germanium from the feed to the strip phase so much faster than the flat sheet (FS) SLM system. The rate of transport through HFSLMs is comparable to dispersive extractions.Peer ReviewedPostprint (author's final draft

Non-dispersive extraction of ge(IV) from aqueous solutions by cyanex 923: Transport and modeling studies

Transport process of germanium from an aqueous solution containing oxalic acid and 100 mg/L Ge was studied. Cyanex 923 immobilized in a polytetrafluoroethylene membrane was employed as a carrier in a flat-sheet supported liquid membrane (FSSLM) system. The speciation of the germanium ion in the oxalic acid medium and related diagrams were applied to study the transport of germanium. The effective parameters such as oxalic acid, carrier concentration, and strip reagent composition were evaluated in this study. Based on the experimental data, the oxalic acid and carrier concentrations of 0.075 mol/L and 20% v/v were the condition in which the efficient germanium transport was achieved, respectively. The concentration range of 0.04–0.1 mol/L was selected for sodium hydroxide (NaOH) as a strip reagent providing the best efficiency to transport germanium through the supported liquid membrane (SLM) system. Furthermore, the permeation model was obtained to calculate the mass transfer resistance of the membrane (¿m) and feed (¿f) phases. According to the results, the values of 1 and 1345 s/cm were found for ¿m and ¿f, respectivelyPeer ReviewedPostprint (published version

Removal of Ni and Cd ions from aqueous solution using iron dust-zeolite composite: analysis by thermodynamic, kinetic and isotherm studies

To examine the effectiveness of iron dust-zeolite composite as an adsorbent for the removal of heavy metal ions from aqueous solutions, the adsorption isotherms, the kinetic, thermodynamic and optimum conditions such as initial concentration, pH, contact time, adsorbent dosage and competitive adsorption conditions of heavy metals were investigated. The characterization of the composite was characterized via FTIR, SEM, XRF and XRD methods. Kinetic results on the removal of heavy metal ions from aqueous solutions have been well described by the pseudo-second-order model. The adsorption data for Cd and Ni ions were fitted well with the Langmuir and Freundlich isotherm models, respectively. The maximum adsorption capacities of iron dust-zeolite for Cd and Ni ions were equal to 78.125 and 76.33 mg/g, respectively. The thermodynamic parameters such as enthalpy, entropy and free energy of adsorption of metal ions were determined. It was found that the process is endothermic, favorable and spontaneous. The competitive adsorption ability of heavy metal ions in the binary system on the composite showed that Cd ions had a synergistic effect on the adsorption of Ni and Ni ions had the negative effect on Cd adsorption

Role of dissolved mineral species in selective flotation of smithsonite from quartz using oleate as collector

Quartz is, in most cases, the major gangue mineral found in the zinc oxide ores. Although it possesses a negative surface charge at pH 9. quartz nevertheless, reports to the concentrate with Zn in oleate flotation. In this study, it was found that quartz can be activated with Zn(II) and Pb(II) and floated with oleate in the pH regions of 9-11.5 and 6.5-10.5, respectively. In these pH regions, zinc and lead hydroxides are the stable species, and can be adsorbed on the negatively surface charge of quartz by adsorbing/precipitating. Therefore, the adsorption of the oleate on the activated quartz surface was being made possible. Furthermore, the effects of sodium silicate, sodium sulfide, sodium hexametaphosphate (SH), sodium fluoride, carboxymethylcellulose (CMC), and starch as depressants of dissolved Zn(II) and Pb(II) were also studied. The CMC was a quite adequate depressant without having adverse effect on smithsonite flotation. In order to probe the validity of the findings, zeta potential and real flotation experiments were also carried out successfully. (C) 2012 Elsevier B.V. All rights reserved

A review of zinc oxide mineral beneficiation using flotation method

In recent years, extraction of zinc from low-grade mining tailings of oxidized zinc has been a matter of discussion. This is a material which can be processed by flotation and acid-leaching methods. Owing to the similarities in the physicochemical and surface chemistry of the constituent minerals, separation of zinc oxide minerals from their gangues by flotation is an extremely complex process. It appears that selective leaching is a promising method for the beneficiation of this type of ore. However, with the high consumption of leaching acid, the treatment of low-grade oxidized zinc ores by hydrometallurgical methods is expensive and complex. Hence, it is best to pre-concentrate low-grade oxidized zinc by flotation and then to employ hydrometallurgical methods. This paper presents a critical review on the zinc oxide mineral flotation technique. In this paper, the various flotation methods of zinc oxide minerals which have been proposed in the literature have been detailed with the aim of identifying the important factors involved in the flotation process. The various aspects of recovery of zinc from these minerals are also dealt with here. The literature indicates that the collector type, sulfidizing agent, pH regulator, depressants and dispersants types, temperature, solid pulp concentration, and desliming are important parameters in the process. The range and optimum values of these parameters, as also the adsorption mechanism, together with the resultant flotation of the zinc oxide minerals reported in the literature are summarized and highlighted in the paper. This review presents a comprehensive scientific guide to the effectiveness of flotation strategy. (C) 2013 Elsevier B.V. All rights reserved