Four-stage Countercurrent Extraction Research Articles

PRELIMINARY STUDY ON SEPARATION OF RARE EARTH METALS FROM LEACH SOLUTION OF DISCARDED FLUORESCENT POWDER BY SOLVENT EXTRACTION

Discarded fluorescent lamps were considered as hazardous waste in Vietnam (code is 160106). However, its composition contained valuable rare earth metals, which can be recycled and recovered by leaching and solvent extraction processes. The present study sought to define the conditions of separation for rare earth elementals (REEs) from acid leach solution by solvent extraction using PC88A. The acid leach solution was obtained from leaching of fluorescent powder. Efficiencies on REEs extractions as functions of pH levels, extractant concentration, O/A ratio, metal concentration were investigated. For pH values greater than 0.0 and less than 1.0, the orders of the yields extraction were determined: yttrium > terbium > europium > aluminum and calcium. The best separation circuit included four-stage counter current extraction for yttrium separation with 20 %v/v PC88A in kerosene (O/A = 1/1, room temperature, 20 min of contact, pH of 0.38) and stripping step with 3 M HCl acid (O/A = 1/1, room temperature, 30 min of contact). After yttrium separation, the leach solution was extracted at pH of 0.98 in the same other conditions with two-stage counter current extraction to recover terbium and europium group. The final recovery from leach liquor was higher than 98 % and the grade of the final product was 94.2 % (for yttrium) and 93.8 % (for terbium and europium group).

Rapid selective extraction of V(V) from leaching solution using annular centrifugal contactors and stripping for NH4VO3

Abstract The efficient and rapid selective extraction of V(V) from leaching solution with sulfated primary amine N1923 was demonstrated. In the single-stage extraction using annular centrifugal contactor (ACC), the influence of the total flow and the speed rotor on extraction percentage of V(V) was investigated using central composite design (CCD), and the results of experimental conditions were analyzed by analysis of variance. The current concentrations of V(V) and Cr(VI) in leaching solution were 23.70g/L and 1.52g/L, respectively. 99.6% of vanadium was extracted and separated from the aqueous solution by employing four-stage countercurrent extraction with annular centrifugal contactors (ACCs). The total contact/resident time of the two phases was 4.8 min, and the separation factor of V(V) and Cr(VI) was 273.9. The two metals in leaching solution can be separated primarily, and then 23.61g/L V(V) and 0.72g/L Cr(VI) in loaded organic phase can be further separated by the stripping. The NH4VO3 with purity of 99.7% was obtained by two steps of separations and studied by the analyses of XRD, SEM and particle size distribution (PSD). The reactions of extraction and stripping in the separation processes were investigated in order to establish a firm conclusion.

Solvent Extraction of Molybdenum (VI) from Hydrochloric Acid Leach Solutions Using P507. Part I: Extraction and Mechanism

ABSTRACTThe extractant 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507) was used to selectively extract molybdenum (VI) from the hydrochloric acid leach solution of molybdenite after roasting with lime. The effects of solution acidity, organic composition, extractant concentration, impurity concentration, temperature and phase volume ratio on the separation of molybdenum (VI) over impurities of iron (III), aluminum, silicon and phosphorus were investigated. The increase in solution acidity resulted in the depolymerization of molybdenum heteropolyanions and , and the formation of molybdenum cations of . The saturated loading capacity of molybdenum (VI) with 30% (v/v) P507 in sulfonated kerosene reached 44.5 g/L. More than 99.8% of the molybdenum (VI) was extracted in a four-stage counter current extraction using an organic system consisting of 30% (v/v) P507 and 70% (v/v) sulfonated kerosene and a hydrochloric acid leach solution containing 14.8 g/L Mo(VI) and 1.73 mol/L H+ with an A/O ratio of 2.86/1 at room temperature for 7 min, while the extraction of iron(III) and phosphorus was only 1.02% and 2.96%, respectively. The separation factor of molybdenum and impurities was in the range of 104.31 ~ 105.89. The extracted molybdenum (VI) species of Mo2O5A2·2HA in the loaded organic solution was identified by the combination of the slope and saturation methods, and further proved by the FTIR spectral analysis.

Direct solvent extraction of molybdenum(VI) from sulfuric acid leach solutions using PC-88A

The extractant 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) was used to directly extract molybdenum(VI) from high sulfuric acid leach solutions containing 3mol/L H+. The effects of extractant concentration, solution acidity and type of stripping reagent on the recovery of molybdenum(VI) were investigated. The saturated loading capacity of molybdenum(VI) with 40% PC-88A in sulfonated kerosene was 60g/L. More than 98.7% of the molybdenum(VI) was extracted in a four-stage counter current extraction using an organic system consisting of 40% PC-88A and 60% sulfonated kerosene and a feed containing 17.3g/L Mo(VI) and 157.3g/L H2SO4 with an A/O ratio of 3/1 at 20°C for 5min. The extracted molybdenum(VI) species of Mo2O5(HA2)2 in loaded organic solutions were identified by the combination of slope and saturation methods, and further proved by FTIR spectral analysis. The stripping of molybdenum(VI) was completed in a two-stage counter current stripping using 6mol/L of NH3 with an A/O ratio of 1/1.5 at 30°C for 5min. The concentration of molybdenum(VI) in the strip liquor reached as high as 146g/L.

Ultrasonic Assisted Multistage Countercurrent Extraction of Ginsenosides from <i>Panax quiquefolium</i> L.

Ultrasonic assisted multistage countercurrent extraction technique of ginsenosides Rb1, Rb2, Rc, Rd, Re, Rg1, and Rg2 from Panax quiquefolium L. was developed in this paper. It provides the analytic technique to determine simultaneously the seven major ginsenosides. The effects of ethanol concentration, ratio of liquid to solid, extraction temperature and extraction time on the extraction yields of the seven ginsenosides and total ginsenosides from Panax quiquefolium L.were investigated. The optimal process condition of ultrasonic assisted four-stage countercurrent extraction (4-UAMSCCE) was found using orthogonal array experimental design technique: 70% (v/v) ethanol solution, liquid: solid ratio of 10 ml/g, extraction temperature 45°C and extraction time 30 min. Under optimum process condition, the extraction efficiency of 4-UAMSCCE had been compared with those of conventional techniques including heat distillation extraction (HDE), ultrasonic assisted extraction (UAE), four-stage countercurrent extraction (4-MSCCE). Results show that the 4-UAMSCCE offers the highest ginsenosides extraction rate and considerable savings in time, energy and solvent consumption.

Improving Jatropha curcas seed protein recovery by using counter current multistage extraction

Jatropha curcas seed press cake contains 23 wt% proteins (dry basis). Due to the toxic compounds in Jatropha, we will use the proteins for non-food applications. Related to non-food applications, an efficient protein extraction to obtain a high protein recovery and high protein concentration with good protein functional properties is required. To achieve this, we conducted protein extractions at room temperature by using different solvents at various solvent to solid ratios and performed multistage counter current extraction to improve protein recovery and protein concentration. We obtained the highest protein recovery of 82% by using 0.055 M NaOH at solvent to solid ratio of 10 g/g after four-stage counter current extraction. By using 0.055 M NaOH extraction at lower solvent to solid ratio of 4 g/g, protein recovery was 35% after one-stage extraction and improved up to 71% with a high protein concentration of 63 mg/mL after four-stage counter current extraction. The highest amount of protein was precipitated from crude extracts at pH 4–5.5 and resulted on precipitate with protein content of 70%. The multistage counter current extraction did not influence Jatropha seed protein molecular weight distributions, which were within the range of 3–98 kDa.

Recovery palladium, gold and platinum from hydrochloric acid solution using 2-hydroxy-4-sec-octanoyl diphenyl-ketoxime

The selective extraction of Pd(II) over Au(III) and Pt(IV) as well as subsequently selective extraction of Au(III) over Pt(IV) from hydrochloric acid (HCl) solution were achieved by using 2-hydroxy-4-sec-octanoyl diphenyl-ketoxime diluted in kerosene as extractant. The typical composition of solution used for the present study contains Pd: 5.95 g/L, Au: 5.42 g/L and Pt: 10.23 g/L. Pd(II) is extracted into organic phase quantitatively after three-stage counter-current extraction operation with extraction percentage >99.9% at pH 2. At a higher HCl concentration (5 M), Au(III) is effectively extracted into organic phase from the resulting raffinate by four-stage counter-current extraction operation. On the other hand, stripping of Pd(II) from loaded organic phase needs high acid solution while the stripping of Au(III) can be achieved at pH 2. Four-stage stripping with 6 M HCl at O:A = 2:1 yielded >99.9% Pd(II) stripping efficiency and four stages stripping with 0.01 M HCl at O:A phase ratio of 2:1 performed >99.9% Au(III) stripping efficiency. The resulting solutions for each metal, after the corresponding process such as precipitation or reduction, can be used for yielding metal powder with the purity better than 99.99%. A complete process flow sheet for the separation and recovery of Pd(II), Au(III) and Pt(IV) is established based on the present investigation.

Computer modelling of the solvent extraction of iron by versatic acid from aluminium nitrate solutions

The development of a chemically based computer model of the extraction of ferric iron from concentrated aluminium nitrate solutions by Versatic 10 is outlined. The model uses previously determined equilibrium constants to calculate the distribution of iron in the various metal complexes present in the organic phase, together with empirical relationships for the pH changes occurring in the aqueous phase during extraction. A mean error of ±13% was found between computer predicted and experimentally determined organic phase iron concentrations for a four-stage counter-current extraction system. It is concluded that iron extraction by Versatic 10 is a technically feasible method of achieving aluminium nitrate with a sufficiently low iron content to enable the production of smelter grade alumina.