Reactions of Oxides of Some 3d Elements with Ammonium Hydrogen Difluoride

Калинников, В. Т.; Nesterov, D. P.; Макаров, Д. В.; Steshin, E. A.; Тихомирова, Е. Л.

doi:10.1023/b:rjac.0000031269.89784.b6

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“…Recently, the ammonium bifluoride (ABF, NH 4 F•HF) has attracted appreciable attention as a potential fluorination agent for the extraction of transition and refractory metals. ABF belongs to the group of strong fluorination agents, having a reactivity closer to that of fluorine and/or hydrofluoric acid [24][25][26]. This salt is known to present the least hazardous form of HF in terms of transport and handling.…”

Section: Introductionmentioning

confidence: 99%

Extraction of Ta and Nb from a Coltan Bearing Ore by Means of Ammonium Bifluoride Fluorination and Sulfuric Acid Leaching

et al. 2021

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A novel approach for Ta and Nb extraction consisting of the pre-treatment of a coltan-bearing ore with an ammonium bifluoride sub-molten salt and subsequent acid leaching has been studied. The effects from ore granulometry, ammonium bifluoride (ABF) to ore mass ratio, temperature and duration of fluorination on the degree of Ta and Nb extraction were examined. The ABF to ore ratio and process temperature were found to have the most pronounced impact on extraction efficiency. The following optimal process conditions were determined: ore granulometric fraction (−75 + 45 µm), ABF-ore (5/1), fluorination temperature (200 °C) and fluorination time (2.5 h). Maintaining these parameters enabled about 94% of Ta and 95% of Nb to be brought into solution during the sulfuric-acid-leaching stage. A comparison of the proposed method with previously reported studies suggests that due to the effects of mechanical agitation and the recirculation of the HF-containing gaseous phase back into the process, the dosage rate of ABF at the fluorination stage could be reduced significantly without sacrificing the overall recovery of Ta and Nb. In such a way, the approach could offer added environmental benefits since release of fluoride-containing effluents into the environment could be limited.

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Section: Introductionmentioning

confidence: 99%