首页|Wolframite concentrate conversion kinetics and mechanism in hydrochloric acid
Wolframite concentrate conversion kinetics and mechanism in hydrochloric acid
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NSTL
Elsevier
? 2022 Elsevier LtdEfficient conversion of wolframite in acid solution plays a crucial role in exploration of sustainable technology for ammonium paratungstate (APT) production. In this work, the factors influencing wolframite concentration conversion in HCl solution and the conversion mechanism were investigated to establish a kinetics model for the decomposition process. The results indicated that the conversion rate increased significantly with increasing temperature and HCl concentration and reducing particle size, while it was independent of stirring intensity. Scanning electron microscope (SEM) analysis indicated that layered H2WO3 films were formed on the surface of converted particles, and the experimental data was consistent with the shrinking core model. The conversion process was divided into two stages with a transition point of 30 min, the first stage was a surface reaction controlling process while the second stage was a hybrid controlling process. The kinetic rate equations were established as: 1-(1-x)1/3 = 0.19 × C1.60?D?0.81?exp(?40570/RT)?t for the first stage, and 4 × [1-(1-x)1/3] + [1-2x/3-(1-x)2/3] = 1.41 × C0.75?D?0.31?exp(?38160/RT)?t for the second stage. This work contributes to better understanding of wolframite conversion in HCl solution and the development of a cleaner route for APT production.
NSTL
Elsevier
