Study on the Preparation Kinetics of Hydrofluoric Acid Using Fluorite and Concentrated Sulfuric Acid
The reaction mechanism and kinetic law of utilizing associated fluorite in conjunction with concentrated sulfuric acid were elucidated to address the technical challenge of hydrofluoric acid production.At different liquid-solid molar ratios and temperatures,the conversion rate of single fluorite and associated fluorite when reacting with concentrated sulfuric acid to produce hydrofluoric acid was investigated.The optimal conditions for single fluorite were a liquid-solid molar ratio of 1.25∶1 at 200℃,and the conversion rate was 97.5%,while,a liquid-solid molar ratio of 1.50∶1 and 200℃were found as the optimized conditions for the associated fluorite,and the conversion rate was 84.5%.The reaction between single fluorite and concentrated sulfuric acid followed the interfacial chemical reaction control model,whereas the reaction between associated fluorite and concentrated sulfuric acid followed the diffusion control model.In addition,the SEM tests showed a serious agglomeration phenomenon,a dense passivation layer of calcium sulfate was formed during the reaction between associated fluorite and concentrated sulfuric acid,impeding the contact between unreacted core and sulfuric acids.This study therefore provides scientific foundation on producing anhydrous hydrofluoric acid using associated fluorite.
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