Effect of the value of x in NH4F·xHF on the digestion of plasma-dissociated zircon

Abstract

Ammonium acid fluoride (NH 4 F·xHF) has been identified as an alternative fluorinating agent for zircon, and may provide a method by which a wide variety of anhydrous metal fluorides can be synthesized. Data on the kinetics of the reaction of NH 4 F·xHF with plasma-dissociated zircon, combined with the thermodynamic parameters, are essential for the development of an industrial process for the production of a precursor for the manufacture of zirconium metal, viz. anhydrous ZrF 4 . The reaction yields (NH 4 ) 3 ZrF 7(s) and (NH 4 ) 2 SiF 6(s) , the latter forming volatile products at relatively low temperatures, affording easy separation of silicon from the zirconium compound.Another useful aspect of the process is the possibility of recycling, since the ammonia and hydrogen fluoride in the waste stream can be recombined, making them available for re-use as the acid fluoride. It was found that the reaction constant k'' varies exponentially with temperature at a set value of x, but linearly with changes in x at a set temperature. The activation energy for the digestion is between 20 and 47 kJ.mol -1 for the values of x investigated.

Lithium extraction from Zimbabwean petalite using ammonium bifluoride

“…'n Aantal artikels oor die oplossing van silikaatverbindings in ABF is reeds gepubliseer (Andreev et al, 2007a, Andreev et al, 2007b, Du Plessis et al, 2016, Nel et al, 2011, Nhlabathi et al, 2012, Retief et al, 2014 Suurroostereksperimente is uitgevoer tussen 100 °C en 300 °C, met roosterperiodes tussen 15 min en 45 min, 'n suuroormaat tussen 0 % en 20 %, loogroerspoed tussen 100 rpm en 400 rpm, die vas-vloeiverhouding tussen 0.05 g mL -1 en 0.13 g mL -1 , en die loogperiode tussen 10 min en 40 min.…”

A novel low‐energy approach to leucoxene concentrate desiliconization by ammonium bifluoride solutions

“…A literature review showed that ammonium fluorides can be considered as the main reagents for processing chemically stable oxides and other oxygen-containing compounds. Well known is the use of a melt of ammonium fluorides as a reagent for processing the most chemically stable oxygen-containing compounds and also minerals (tantalite, 11 laterite, 12 monazite, 13 spodumene, 14 trinitite, 15,16 zircon, [17][18][19][20][21][22] ilmenite, 23 titanomagnetite, 24,25 polymetallic slags, 26 etc.) and pure oxides (plutonium dioxide, 27 thorium dioxide, 28 lanthanum, neodium and gadolinium, 29 etc.).…”

Magnesium Oxide Production by Plasma Chemical Conversion from Fluorine-Containing Industrial Waste

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