TY - JOUR ID - 1378 TI - Mechanical activation of phosphate concentrates to enhance dissolution efficiency of rare earth elements from a kinetic viewpoint JO - Journal of Mining and Environment JA - JME LA - en SN - 2251-8592 AU - Shadi Naghadeh, H. AU - Abdollahy, M. AU - Khodadadi Darban, A. AU - Pourghahramani, P. AD - Mining Engineering Department, Tarbiat Modares University, Tehran, Iran AD - Mining Engineering Faculty, Sahand University of Technology, Tabriz, Iran Y1 - 2019 PY - 2019 VL - 10 IS - 2 SP - 373 EP - 388 KW - Esfordi Phosphate Concentrate KW - Rare Earth Elements KW - Mechanical Activation KW - Leaching DO - 10.22044/jme.2019.7658.1620 N2 - The Esfordi phosphate concentrate mainly contains fluorapatite, monazite, and xenotime as rare earth element (REE) minerals, accounting for 1.5% of rare earth metals. The monazite and xenotime minerals are refractory and their decomposition is only possible at high temperatures. Thus mechanical activation was used in the present work for this purpose. After 90 minutes of mechanical activation, the X-ray amorphization phase and the maximum BET surface area were increased to 93.4% and 8.4 m2/g, respectively. The Williamson-Hall plot indicated that the crystallite size was decreased and the lattice strain was increased as a function of the milling intensity. A volume-weighted crystallite size of 64 nm and a lattice strain of 0.9% were achieved from the mechanically activated sample for 90 minutes. The leaching efficiency of REEs with 32% nitric acid at 85 °C was increased from 25% for the initial sample to about 95% for the activated samples. The first stage reaction rate constants for La, Nd, and Ce were increased from 8 × 10-7, 9 × 10-7,and 6 × 10-7 for the initial sample to 1.3 × 10-3, 9 × 10-4, and 7 × 10-4 for the mechanically activated samples at 60 °C, respectively. Also the apparent activation energy for La, Nd, and Ce for the initial sample was found to be about 210, 231, and 229 kJ/mol, which were decreased to 120, 91, and 80 kJ/mol, respectively, after 20 minutes of mechanical activation in an argon atmosphere. The results obtained suggested mechanical activation as an appropriate pre-treatment method for dissolution of REEs from phosphate concentrates containing refractory REE minerals at a lower cost and a higher recovery rate. UR - https://jme.shahroodut.ac.ir/article_1378.html L1 - https://jme.shahroodut.ac.ir/article_1378_db12d3174f8b9f0ad2b9b5592d97b2ab.pdf ER -