Counter Current Simulation Study Research Articles

Cyphos IL 102 assisted liquid-liquid extraction studies and recovery of vanadium from spent catalyst

In this study, Cyphos IL 102 (trihexyl(tetradecyl)phosphonium bromide) diluted in toluene has been explored as an organic phase for the extraction, separation and recovery of V(V) from sulphate medium. The influence of different fundamental extraction variables namely acids and extractant concentration, equilibration time and temperature on the V(V) extraction has been evaluated. Different stripping agents have been studied for back extraction of vanadium. Saturation and recycling capacity of the extractant has also been performed. Partition behavior of other associated metal ions namely Mn(II), Fe(II/III), Al(III), Cr(III), Ti(IV), Mo(VI) and W(VI) were carried out. The extraction data offer conditions for the binary separation of V(V) from associated metal ions with high separation factors. Optimized parameters have been employed for the extraction and recovery of V(V) from spent V2O5 catalyst leach liquor. To find out the number of stages required to achieve quantitative extraction/stripping of vanadium, McCabe-Thiele plots were drawn, which were further verified by counter current simulation studies. In addition, vanadium oxide was synthesised using thermal decomposition and characterized by XRD, FESEM and EDX techniques.

Solvent extraction of praseodymium using different extractants – a synergistic study

ABSTRACTThe extraction of praseodymium was investigated from chloride media using different extractants such as D2EHPA, PC88A, Cyanex 272, Cyanex 921, Cyanex 923, Cyanex 301, Cyanex 302, LIX 84I, LIX 622N, Alamine 336, Aliquat 336 and their mixtures. The synergistic effect of Cyanex 272, Cyanex 921, Cyanex 923, Cyanex 301 and Cyanex 302 were studied with each other. Among all the combinations, the mixtures of Cyanex 921-Cyanex 301 and Cyanex 923-Cyanex 301 showed the synergistic effect on the extraction of praseodymium. Solvent extraction of Pr was carried out with the mixture of 0.5 M Cyanex 301 and 0.5 M Cyanex 923. The McCabe-Thiele diagram indicated the quantitative extraction of Pr in two counter-current stages at an A:O phase ratio of 1:2. The two-stage counter-current simulation study showed 94% of extraction efficiency.

Recycling of Zn-C and Ni-Cd spent batteries using Cyphos IL 104 via hydrometallurgical route

The study suggests hydrometallurgical routes for the recovery of zinc and cadmium from spent battery leachates using a novel extractant Cyphos IL 104 diluted in toluene and synthesis of zinc and cadmium oxides from the loaded organic phases. Leaching is carried out using 5 mol/L HCl and the composition of the leach liquors obtained from Zn-C and Ni-Cd spent batteries in g/L is Zn- 2.400, Mn - 4.870, Fe - 2.655 × 10−3, and Cd- 4.280, Ni- 89.60 × 10−3, Fe- 148.2 × 10−3, Co- 3.765 × 10−3, respectively. McCabe Thiele diagrams are drawn to determine the number of theoretical stages required for the quantitative extraction and stripping of zinc and cadmium and the data has been confirmed by counter current simulation studies. McCabe Thiele diagrams indicate two extraction stages for both zinc and cadmium at A/O = 1/1 and A/O = 3/2, respectively. EDTA (0.1 mol/L) and HNO3 (1.0 mol/L) are used as strippant for zinc and cadmium, respectively. Quantitative stripping of zinc and cadmium requires two and three counter current stripping stages, respectively at O/A = 1/1. Results of counter current extraction and stripping show quantitative recovery (>99%) of zinc and cadmium with high purity. Zinc and cadmium oxides have been synthesized from the loaded organic phase using precipitation followed by thermal decomposition of precursors at 400 °C. Synthesized materials were characterized by XRD, FE-SEM and EDX techniques. Zinc and cadmium oxide particles correspond to hexagonal zincite and cubic monteponite structures, respectively. The average particle size of zinc and cadmium oxides is 43 ± 13 nm and 55 ± 14 nm, respectively. The morphology of zinc and cadmium oxide particles is considered to be globular with particle agglomeration. The proposed methods are selective for zinc and cadmium. Results of present study have been compared with the reported data.

Recovery of Nd and Pr from NdFeB magnet leachates with bi-functional ionic liquids based on Aliquat 336 and Cyanex 272

The separation of neodymium and praseodymium was carried out from a chloride solution containing the similar composition of NdFeB magnet leach liquor. A comparative study between extractants demonstrated that the extraction efficiency of bi-functional ionic liquids (Bif-ILs) tri octylmethylammonium bis(2,4,4-trimethylpentyl)phosphate (R4NCy) and trioctylmethylammonium di(2-ethylhexyl)phosphate (R4ND) was higher than the conventional extractants such as tri-octyl methyl ammonium chloride (Aliquat 336), bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) and di-2-ethylhexyl phosphoric acid (D2EHPA) under same experimental condition. The extraction efficiency of different extractants for Nd and Pr was in the order: R4NCy>R4ND>Cyanex 272>D2EHPA>Aliquat-336. As the extraction of Nd and Pr was maximum with R4NCy Bif-ILs, the McCabe-Thiele diagram was constructed with R4NCy which showed 2 stages at 1:1 phase ratio. A 2-stage counter current simulation study showed 98.97% Nd and 99.02% Pr extraction. The loaded organic phase was stripped with H2SO4 acid and the stripping efficiencies for Nd and Pr were 98.11% and 98.75%, respectively. The extracted species was found to beMCl3⋅3R4NCy. The thermodynamic parameters were also determined for extraction of Nd and Pr with ionic liquid.

Separation of molybdenum and cobalt from spent catalyst using Cyanex 272 and Cyanex 301

Separation of molybdenum and cobalt from a spent catalyst leach liquor bearing 12.52g/l Mo, 1.74g/l Co and 9.98g/l Al was investigated using solvent extraction technique followed by preparation of metal oxides. Cyanex 272 (bis(2,4,4-trimethylpentyl)phosphinic acid) and Cyanex 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) were used as extractants for molybdenum and cobalt, respectively. The effects of various parameters such as pH, concentration of extractant, A/O ratio and temperature on extraction of Mo and Co were studied. The number of stages required for extraction and stripping were determined from the McCabe–Thiele diagram and confirmed by counter current simulation study. The extracted species for Mo and Co were found to be MoO2A2.H2A2 and CoA2.H2A2, respectively. The thermodynamic parameters such as ΔH, ΔS and ΔG were calculated for molybdenum and cobalt. The enthalpy change (ΔH) values for extraction of molybdenum and cobalt were positive indicating the extraction processes were endothermic. The oxides of molybdenum and cobalt were prepared from the strip solutions of molybdenum and cobalt by crystallization followed by thermal decomposition and the products were characterized by XRD and RAMAN spectra.

Extraction of copper from bacterial leach liquor of a low grade chalcopyrite test heap using LIX 984N-C

Low grade copper ore (ball mill spillage) obtained from Malanjkhand Copper Mine was processed through heap bioleaching at pilot scale. Bioleach liquor (Pregnant Leach Solution) from the heap contains (g/L of) Cu (II) 0.45, Fe (III) 0.838, Zn (II) 0.006, Ni (II) 0.0014, Mn (II) 0.011 and Pb (IV) 0.004. Solvent extraction of copper from Pregnant Leach Solution was carried out using LIX 984N-C. Effect of different operational factors such as equilibrium pH (pHe), extractant concentration, strip solution concentration, phase ratio was examined to optimize the condition for selective and quantitative extraction of copper. Based on the results of extraction as well as stripping isotherm, a 6-cycle counter current simulation study (CCS) was conducted for the conformational study. The extraction of copper was quantitative in 2-stages using 1.5% (v/v) LIX 984N-C at A: O ratio of 1:2 and pHe 1.85. The CCS condition (two stages, phase ratio A:O=1:4) obtained from the stripping isotherm study, further attributes to the enrichment (4 folds) of copper concentration in the strip solution.

Selective solvent extraction of vanadium over iron from a stone coal/black shale acid leach solution by D2EHPA/TBP

A D2EHPA and TBP mixed solvent system diluted with kerosene were used for the selective extraction of vanadium(IV) from iron(II) from an acidic stone coal leach solution that was reduced using sodium sulfite. Extraction studies were carried out under different pH and solvent concentrations, and optimized conditions were determined. The loaded organic was stripped with sulfuric acid. The number of stages required for the extraction and stripping of vanadium were determined from a McCabe-Thiele plot and confirmed by counter-current simulation studies. Results demonstrate that the extraction of vanadium increases as the initial pH and the D2EHPA concentration increases in the organic phase. A six-stage counter-current extraction simulation test was conducted over a period of 40 h at a initial pH of 2.48 with 10% (v/v) D2EHPA and 5% (v/v) TBP mixed extractant and resulted in a vanadium extraction of 97% for the feed solution containing 5.78 g/L V 2O 5 and 10.86 g/L total Fe. The loaded organic phase that contained 5.34 g/L V 2O 5 and 1.0 g/L Fe can be completely stripped by three-stage counter-current stripping with 1.5 mol/L H 2SO 4 at a phase flow ratio of O/A = 5:1 to give a strip solution containing 26.3 g/L V 2O 5 and 0.72 g/L Fe.

Recovery of molybdenum from the sea nodule leach liquor by solvent extraction using Alamine 304-I

Separation and recovery of molybdenum was investigated from the sea nodule leach liquor containing 0.505 kg/m 3 Mo(VI), 0.212 kg/m 3 Fe(III),12.08 kg/m 3 Cu(II), 2.012 kg/m 3 Co(II) and 15.16 kg/m 3 Ni(II). The recovery process was carried out in two key steps: (i) Solvent extraction of Mo(VI) from the leach liquor using Alamine 304-1 dissolved in kerosene and (ii) Preparation of MoO 3 from stripped solution by crystallization followed by thermal decomposition of ammonium polymolybdate crystals. In the solvent extraction study, the effects of several operational factors like contact time, pH, extractant concentration and different stripping reagents were examined to establish suitable conditions for effective extraction and stripping of molybdenum. The number of stages required for extraction and stripping were determined from a McCabe Thiele diagram and confirmed by a counter current simulation study. Enrichment of approximately 6.05 kg/m 3 Mo(VI) into the loaded organic phase was achieved with 10% (v/v) Alamine 304-1, at equilibrium pH 1.62, and A:O = 12:1. The McCabe Thiele diagrams at A:O = 1:16 with 5 M NH 4OH + 2.5 M (NH 4) 2CO 3 showed two theoretical stages needed for quantitative stripping of molybdenum. Ammonium polymolybdate was crystallized from the stripped solution (96.79 kg/m 3 Mo) and molybdenum trioxide was obtained by thermal decomposition at 400 °C with purity of 99.9%.

Separation of iron(III), copper(II) and zinc(II) from a mixed sulphate/chloride solution using TBP, LIX 84I and Cyanex 923

Separation of iron(III), copper(II) and zinc(II) from a mixed sulphate/chloride leach liquor bearing 11.8 kg/m 3 iron, 24.8 kg/m 3 copper, 0.23 kg/m 3 zinc, 3.8 kg/m 3 cobalt, 35.2 kg/m 3 nickel, 176.3 kg/m 3 chloride and 48.9 kg/m 3 sulphate was carried out using solvent extraction. Iron, copper and zinc extraction studies were carried out using TBP, LIX 84I and Cyanex 923 in kerosene, respectively. The extraction studies were carried out for various metal ions at different pH and solvent concentrations and the optimized conditions were determined. The numbers of stages required for extraction and stripping of metal ions were determined from the McCabe–Thiele plot and confirmed from the counter-current simulation studies. Iron loaded TBP, copper loaded LIX 84I and zinc loaded Cyanex 923 were stripped with water, H 2SO 4 and water, respectively. Based on the data a flow sheet for separation of the three metal ions has been provided.