Chemical kinetics of Rare Earth Element (REE) separation by precipitation method

CHEMICAL KINETICS OF RARE EARTH ELEMENT (REE) SEPARATION BY PRECIPITATION METHOD. REE, are difficult to separate due to their similar properties yet are highly useful especially in advanced material industries. REE purification process uses precipitation is conducted to remove unwanted major elements in the material. This study aims to determine the optimum stirring speed and volume of NH₃(aq) addition, and analyze the order and reaction speed constants in the separation of REE using the precipitation method. The materials used were REOH from monazite sand processing with observed elements is limited to Dy, La, Nd, Ce, and Pr. The precipitation variations used include stirring speed (260–940 rpm) and the addition of NH₃(aq) volume (10–30 mL). The results showed that the optimum condition of stirring speed for La, Ce, and Pr elements was 500 rpm with efficiency values of 79.51 %, 99.76 %, and 98.89 %, while Dy and Nd elements were 640 rpm with efficiency values of 99.97 % and 99.15 %. The optimum NH₃(aq) volume addition condition is 20 mL for Dy, Nd, and Ce elements with efficiency values touching 99.99 % on all three elements, while La and Pr elements at a volume of 30 mL with efficiency values of 99.95 % and 99.97 %. The reaction takes place in the first order reaction in all variations. The effect of stirring speed on reaction constants showed that Dy and La had the highest constants at 640 rpm with values of −4.1x10⁻⁶ min⁻¹ and -7.26x10^{- 4}min⁻¹ respectively, Nd at 500 rpm with −7.24x10⁻⁵min⁻¹, and Ce and Pr at 260 rpm with 1.73x10⁻⁴ and −2.1x10⁻⁵. The effect of NH₃(aq) volume addition on the reaction constants showed that Dy had the highest constant at 20 mL with 1.27x10⁻⁶min⁻¹, La at 30 mL with −2.07x10⁻⁵min⁻¹, and Nd, Pr, and Ce at 25 mL with −1.59x10⁻⁶min⁻¹, 3.12x10⁻⁶min⁻¹, and 2.37x10⁻⁶min⁻¹, respectively.