Microwave digestion of zircon with ammonium acid fluoride: Derivation of kinetic parameters from non-isothermal reaction data

Abstract

Zircon is notoriously inert. Aggressive processing methods such as alkaline fusion are conventionally used to extract zirconium values from the mineral. In this study results are presented with respect to microwave digestion of zircon using ammonium acid fluoride (NH 4 F·1.5HF). Two distinct experimental methods were used. In the first method the reaction was followed in the temperature range 100 to 200 ºC, for a full reaction period of 60 minutes at each temperature. The second method comprised successive digestion periods interrupted by washing and re-introduction of fresh acid fluoride at a series of reaction temperatures varying between 120 and 240 °C. Complete digestion was achieved with the latter technique. The kinetics is shown to be controlled by product-layer diffusion. The two data sets were combined to derive consistent temperature-dependent kinetic parameters. A facile numerical technique for extracting these parameters from the experimental data is used.

Lithium extraction from Zimbabwean petalite using ammonium bifluoride

“…Nel et al (2011) en Du Plessis et al (2016 beskryf die reaksie tussen plasmagedissosieerde sirkoon en ABF sowel as ammoniumsuurfluoried (NH4•xHF, met x>2), en ontleed onderskeidelik die kinetika en die effek van die hoeveelheid HF inhoud. Nhlabathi et al (2012) brei hierdie werk uit en verfyn die kinetika van Nel et al (2011).…”

“…'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.).…”

Microwave Dehydration Modelling of Tincalconite

“…Previous microwave studies published in literature about especially minerals were examined [8][9][10][11][12][13][14][15][16][17][18][19]. Microwave dehydration behavior on different types of minerals such as goethite, boric acid, ilmenite, inderite, colemanite and ulexite was studied in the literature [8][9][10][11][12][13][14][15][16][17][18][19]. Thamsebi et al studied different microwave output power levels were used to analyze drying kinetic of coal in this experiment [8].…”