Precipitation of sodium silicofluoride (Na2SiF6) and cryolite (Na3AlF6) from HF/HCl leach liquors of alumino-silicates

Kumar, Manoj; Babu, M. Nani; Mankhand, T R; Pandey, B.D.

doi:10.1016/j.hydromet.2010.05.014

Cited by 41 publications

(25 citation statements)

References 3 publications

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“…The rate of reaction is proportional to the concentration of HF molecules adsorbed at surface lattice bonds. Kumar et al (2010) reported precipitation of Na 2 SiF 6 and Na 3 AlF 6 from leach liquors by dissolution of low grade molybdenite ore with HCl/HF. They proposed the recovery of these compounds by increasing the pH of the solution with Na 2 CO 3 .…”

Section: Metalurgia E Materiaismentioning

confidence: 99%

“…Furthermore, it was established that the precipitate in step 1 (hieratite) solid has a purity of 98.8% and the compound obtained in step 2 (cryolite) has a purity of 89.3%. Kumar et al, 2010 obtained a precipitate of Na 2 SiF 6 (malladrite) and Na 3 AlF 6 (cryolite) from the leach liquors of low-grade molybdenite containing alumino-silicates. The near complete recovery of Na 2 SiF 6 and the cryolite was found to be contaminated with sodium ferric-fluoride and recovery about 95%.…”

Section: Hydrometallurgical Extraction Of Al and Si From Kaolinitic Cmentioning

confidence: 99%

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Hydrometallurgical extraction of Al and Si from kaolinitic clays

et al. 2017

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Herein is presented the results of a study on the hydrometallurgic extraction and recovery of aluminum and silicon by leaching of kaolinitic clays with HF. The studied extraction parameters were: temperature, reaction time, solid/liquid ratio, concentration, and precipitating agent mass. In the leaching process, mineral dissolutions near 100% were obtained when working at 348 K, solid/liquid ratio 2% w/v, HF 12% v/v, for 120 minutes. The HF leach liquor generated from the dissolution of kaolinitic clays contains H 2 SiF 6 and H 3 AlF 6 . Studies were conducted to recover the two valuable fluorides as K 2 SiF 6 and Na 3 AlF 6 by precipitation with alkaline salts from the leach liquor. Phases of precipitated fluorides were identified by XRD and surface morphology by SEM. The purity of the K 2 SiF 6 precipitate was 98.8%, whereas for Na 3 AlF 6 , it was 89.3%. Also, both synthesized solids are of high commercial value due to their industrial applications.

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Section: Metalurgia E Materiaismentioning

confidence: 99%

Section: Hydrometallurgical Extraction Of Al and Si From Kaolinitic Cmentioning

confidence: 99%

Hydrometallurgical extraction of Al and Si from kaolinitic clays

et al. 2017

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“…In this case, lithium was precipitated as LiF, evaporating the solutions above the solubility product constant (Ksp) of LiF [16,17,[19][20][21][22][23]. The recovery efficiency of each element was calculated by gravimetric analysis.…”

Section: Recovery Assaysmentioning

confidence: 99%

“…This indicates that the Si, which was not recovered in the previous step, was precipitated as Na 2 SiF 6 in amounts below the detection limit of XRD. For further purification the solid can be washed with solutions at different pH values [20]. The achieved recovery percentage of Al was 95%.…”

Section: Recovery Of Lithium As Lifmentioning

confidence: 99%

Recovery Process of Li, Al and Si from Lepidolite by Leaching with HF

et al. 2017

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This work describes the development of a new process for the recovery of Li, Al and Si along with the proposal of a flow sheet for the precipitation of those metals. The developed process is comprised of lepidolite acid digestion with hydrofluoric acid, and the subsequent precipitation of the metals present in the leach liquor. The leaching operational parameters studied were: reaction time, temperature and HF concentration. The experimental results indicate that the optimal conditions to achieve a Li extraction higher than 90% were: solid-liquid ratio, 1.82% (w/v); temperature, 123 • C; HF concentration, 7% (v/v); stirring speed, 330 rpm; and reaction time, 120 min. Al and Si can be recovered as Na 3 AlF 6 and K 2 SiF 6 . LiF was separated from the leach liquor during water evaporation, with recovery values of 92%.

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“…The remaining acidity is mainly due to excess of HF used for leaching. However, anions such as SiF 6 2-, SnF 6 2-, AlF 6 3-and FeF 6 3-come from strong acids (reactions 3, 4, 5 and 8), 35,57 thus also contributing to the acidity of the leachate.…”

Section: General Aspectsmentioning

confidence: 99%

Recovery of Lead and Noble Metals After Processing Printed Circuit Boards From Cell Phones by Leaching With Mixtures Containing Hydrogen Fluoride

Silva¹,

Corrêa²,

Gismonti³

et al. 2018

Quim. Nova

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This work examines the leaching of printed circuit boards (PCBs) from cell phones in aqueous solutions containing HF + H 2 O 2 or HF + NaClO under mild experimental conditions. The PCBs were not ground but were previously treated with 6 mol L -1 NaOH at 50 o C for 1 h to remove their soldering mask. , respectively. The processing of the solid residue is also described in detail. It was leached with water at ~90 o C followed by HNO 3aq. at 25 o C. Lead, palladium and silver were recovered in this order, leaving gold as final solid. After 1 h at [35][36][37][38][39][40] o C, 5 mol L -1 HF + 0.3 mol L -1 NaClO mixtures leached the base metals, copper, gold and palladium. Gold was recovered by liquid-liquid extraction with methyl isobutyl ketone. Silver precipitated as chloride. This salt was isolated by leaching with NH 3aq . Loss of fluoride ions (as HF) was below 0.5 wt.% after leaching and handling the solid residue.

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Precipitation of sodium silicofluoride (Na2SiF6) and cryolite (Na3AlF6) from HF/HCl leach liquors of alumino-silicates

Cited by 41 publications

References 3 publications

Hydrometallurgical extraction of Al and Si from kaolinitic clays

Hydrometallurgical extraction of Al and Si from kaolinitic clays

Recovery Process of Li, Al and Si from Lepidolite by Leaching with HF

Recovery of Lead and Noble Metals After Processing Printed Circuit Boards From Cell Phones by Leaching With Mixtures Containing Hydrogen Fluoride

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