The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring spee...The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.展开更多
An acidic mixture of sulfuric and fluosilicic acid(H_(2)SO_(4)+H_(2)SiF_(6))was employed as lixiviant to enhance leaching of lithium from lepidolite.The H_(2)SiF_(6) was obtained as a byproduct of anhydrous hydrofluor...An acidic mixture of sulfuric and fluosilicic acid(H_(2)SO_(4)+H_(2)SiF_(6))was employed as lixiviant to enhance leaching of lithium from lepidolite.The H_(2)SiF_(6) was obtained as a byproduct of anhydrous hydrofluoric acid production,aiming to provide HF molecules.It was found that the HF molecules were the main reaction component and played a key role in strengthening the dissolution of lepidolite.Different factors,including mass ratio of ore/H_(2)SO_(4)/H_(2)SiF_(6),concentrations of H_(2)SO_(4) and H_(2)SiF_(6),leaching temperatures(40−80℃)and time(15−75 min),were investigated.Moreover,an efficient tubular reactor was employed to improve this acid leaching system.Under the optimal conditions(ore/H_(2)SO_(4)/H_(2)SiF_(6) mass ratio of 1:0.8:1.6,80 wt.% H_(2)SO_(4),15 wt.% H_(2)SiF_(6),80℃,15 min),97.9% of Li,96.4% of K,97.6% of Rb,96.7% of Cs and 81.4% of Al(mass fraction)were leached.Additionally,a two-step thermal process was proposed to remove fluorine of leaching slurry.This acid treatment using an acidic mixture of H_(2)SO_(4) and H_(2)SiF_(6) in a continuous tubular reactor shows potential as an alternative process to extract lithium from lepidolite.展开更多
文摘The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.
基金the financial supports from Natural Science Foundation of Henan,China(No.212300410278)Henan Provincial Key Research and Development Program,China(No.212102310371)+1 种基金Henan Postdoctoral Foundation,China(No.202002020)China Postdoctoral Science Foundation(No.2020M682353).
文摘An acidic mixture of sulfuric and fluosilicic acid(H_(2)SO_(4)+H_(2)SiF_(6))was employed as lixiviant to enhance leaching of lithium from lepidolite.The H_(2)SiF_(6) was obtained as a byproduct of anhydrous hydrofluoric acid production,aiming to provide HF molecules.It was found that the HF molecules were the main reaction component and played a key role in strengthening the dissolution of lepidolite.Different factors,including mass ratio of ore/H_(2)SO_(4)/H_(2)SiF_(6),concentrations of H_(2)SO_(4) and H_(2)SiF_(6),leaching temperatures(40−80℃)and time(15−75 min),were investigated.Moreover,an efficient tubular reactor was employed to improve this acid leaching system.Under the optimal conditions(ore/H_(2)SO_(4)/H_(2)SiF_(6) mass ratio of 1:0.8:1.6,80 wt.% H_(2)SO_(4),15 wt.% H_(2)SiF_(6),80℃,15 min),97.9% of Li,96.4% of K,97.6% of Rb,96.7% of Cs and 81.4% of Al(mass fraction)were leached.Additionally,a two-step thermal process was proposed to remove fluorine of leaching slurry.This acid treatment using an acidic mixture of H_(2)SO_(4) and H_(2)SiF_(6) in a continuous tubular reactor shows potential as an alternative process to extract lithium from lepidolite.
