Dissolution behavior of calcium tungstate in oxalic acid solutions

Kalpakli, Ahmet Orkun; İlhan, Sedat; Kahruman, Cem; Yusufoğlu, İbrahim

doi:10.1016/j.hydromet.2012.04.014

Cited by 55 publications

(16 citation statements)

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“…The reagents used in this work were analytically pure, lime was prepared from calcium hydroxide by roasting at 1273 K for 2.0 h. Artificial scheelite was first precipitated by the reaction of sodium tungstate solution and calcium chloride solution [19], the obtained precipitate was then washed, dried and calcined at 1273 K for 2.0 h. The scheelite concentrate and natural mixed concentrate of scheelite and wolframite used in this study were provided by JiangXi Rare Metals Tungsten Holdings Group Co., Ltd., China. Their chemical compositions and X-ray diffraction (XRD) patterns are shown in Table 1 and Fig.…”

Section: Methodsmentioning

confidence: 99%

Ca3WO6 prepared by roasting tungsten-containing materials and its leaching performance

Zhou

et al. 2015

International Journal of Refractory Metals and Hard Materials

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Section: Methodsmentioning

confidence: 99%

Ca3WO6 prepared by roasting tungsten-containing materials and its leaching performance

Zhou

et al. 2015

International Journal of Refractory Metals and Hard Materials

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“…9, the rate constants k 1,0 and k 0,0 and the activation energies E 1 and E o were calculated as 6961?15 cm s 21 and 1122?93 mol cm 22 s 21 and 45?7 and 63?8 kJ mol 21 respectively. Equation (27) was obtained by putting all kinetic data in equation (24). Equation (27) ) was calculated according to equation (30) using known C CW and X W and shown in diagrams as empty circle (Fig.…”

Section: Derivation Of the Dissolution Rate Equation And Determinatiomentioning

confidence: 99%

“…Equation (27) was obtained by putting all kinetic data in equation (24). Equation (27) ) was calculated according to equation (30) using known C CW and X W and shown in diagrams as empty circle (Fig. 10).…”

Section: Derivation Of the Dissolution Rate Equation And Determinatiomentioning

confidence: 99%

“…For experimental conditions in which CaC 2 O 4 H 2 O protective layer was not effective C CW versus t diagrams were plotted using equation (40), C HW versus t diagrams were plotted with C HW values calculated by equation (30) and n W versus t diagrams were also plotted using equation (28). X W values were calculated using equation (27) which was used in equations (28) and (30). These diagrams were constructed for all experiments in which CaC 2 O 4 H 2 O protective layer was not effective, but to avoid repetition only three of them were shown in Fig.…”

Section: Derivation Of the Dissolution Rate Equation And Determinatiomentioning

confidence: 99%

“…1. Details of the experimental set up were given by Kalpakli et al 27 H 2 C 2 O 4 solution (1 L) was heated to reaction temperature and then 3 g CaWO 4 was added to solution. The leaching reaction was carried out under isothermal conditions for 3 h. Samples were taken from the reactor at certain time intervals for the quantitative determination of tungstate and calcium by ICP-OES (Spectro Ciros Vision).…”

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Kinetic investigation of dissolution of CaWO₄in oxalic acid solution

Kalpakli

İlhan

Kahruman

et al. 2013

Canadian Metallurgical Quarterly

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In this study, the effects of stirring speed, temperature, H 2 C 2 O 4 concentration and particle size on the dissolution rate of CaWO 4 in H 2 C 2 O 4 solutions were investigated. CaWO 4 was dissolved in H 2 C 2 O 4 solutions as series parallel type reaction. In the first step which took place according to Langmuir-Hinshelwood Mechanism, H 2 C 2 O 4 was adsorbed as a mobile adsorption layer on the surface of CaWO 4 , reacted to form adsorbed calcium aqua oxalato tungstate (Ca[WO 3 (C 2 O 4 )H 2 O]) intermediate product and the adsorbed Ca[WO 3 (C 2 O 4 )H 2 O] was desorbed into the solution. In the second step, Ca[WO 3 (C 2 O 4 )H 2 O] hydrolysed and formed H 2 WO 4 which reacted with H 2 C 2 O 4 to form hydrogen aqua oxalato tungstate (H 2 [WO 3 (C 2 O 4 )H 2 O]) as end product together with solid CaC 2 O 4 H 2 O. Model kinetic equations were derived which showed the relationships of the fractional conversion of CaWO 4 , the concentration of Ca[WO 3 (C 2 O 4 )H 2 O] and the concentration of H 2 [WO 3 (C 2 O 4 )H 2 O] with time. The diagrams drawn according to the model kinetic equations were in good agreement with the experimentally obtained diagrams (R 2 .0?99). Dans cette é tude, on a examiné les effets de la vitesse d'agitation, de la tempé rature, de la concentration d'H 2 C 2 O 4 et de la taille de particule sur la vitesse de dissolution de CaWO 4 dans des solutions d'H 2 C 2 O 4 . On a dissous le CaWO 4 dans des solutions d'H 2 C 2 O 4 en une ré action de type sé rie-parallè le. Dans la premiè re é tape, qui avait lieu d'aprè s le Mé canisme de LangmuirHinshelwood, l'H 2 C 2 O 4 é tait adsorbé en une couche mobile d'adsorption à la surface du CaWO 4 , ré agissait pour former le produit intermé diaire adsorbé , aqua oxalato tungstate de calcium (Ca[WO 3 (C 2 O 4 )H 2 O]), et ce Ca[WO 3 (C 2 O 4 )H 2 O] adsorbé é tait dé sorbé dans la solution. Dans la seconde é tape, le Ca[WO 3 (C 2 O 4 )H 2 O] é tait hydrolysé et formait l'H 2 WO 4 qui ré agissait avec l'H 2 C 2 O 4 pour former de l'aqua oxalato tungstate d'hydrogè ne (H 2 [WO 3 (C 2 O 4 )H 2 O]) comme produit final avec le CaC 2 O 4 H 2 O solide. On a dé rivé les é quations ciné tiques du modè le, lesquelles montraient les relations de la conversion fractionnelle du CaWO 4 , de la concentration de Ca[WO 3 (C 2 O 4 )H 2 O] et de la concentration d'H 2 [WO 3 (C 2 O 4 )H 2 O] en fonction du temps. Les diagrammes dessiné s d'aprè s les é quations ciné tiques du modè le é taient en bon accord avec les diagrammes obtenus expé rimentalement (R 2 .0?99). List of symbols C concentration CW calcium aqua oxalato tungstate E i activation energy (i50, 1 and 2)HW hydrogen aqua oxalato tungstate k i rate constant (i50, 1, a, -a, d and r) k i,0 frequency factor (i50, 1 and 2) n i mole number n i,0 initial mole number p number of CaWO 4 particle r i reaction rate (i50, 1, 2, a, r and d) r W reaction rate r c radius of solid CaWO

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Investigation of Reaction Stoichiometry of Leaching of Synthetic CaWO₄in H₂C₂O₄Solutions

Kalpakli¹,

İlhan²,

Yusufoğlu³

2014

Characterization of Minerals, Metals, and Materials 2014

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Dissolution behavior of calcium tungstate in oxalic acid solutions

Cited by 55 publications

References 9 publications

Ca3WO6 prepared by roasting tungsten-containing materials and its leaching performance

Ca3WO6 prepared by roasting tungsten-containing materials and its leaching performance

Kinetic investigation of dissolution of CaWO₄in oxalic acid solution

Investigation of Reaction Stoichiometry of Leaching of Synthetic CaWO₄in H₂C₂O₄Solutions

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Dissolution behavior of calcium tungstate in oxalic acid solutions

Cited by 55 publications

References 9 publications

Ca3WO6 prepared by roasting tungsten-containing materials and its leaching performance

Ca3WO6 prepared by roasting tungsten-containing materials and its leaching performance

Kinetic investigation of dissolution of CaWO4in oxalic acid solution

Investigation of Reaction Stoichiometry of Leaching of Synthetic CaWO4in H2C2O4Solutions

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Kinetic investigation of dissolution of CaWO₄in oxalic acid solution

Investigation of Reaction Stoichiometry of Leaching of Synthetic CaWO₄in H₂C₂O₄Solutions