OICC Press Iranian Journal of Earth Sciences 2228-785X 15 4 2023 10 01 The petrology and geochemistry of Sorkheh-Dizaj intrusive rocks in northern Zanjan and its effects on recovery of LREE from tailingby digestion-water leaching processes, Iran 248 263 10.30495/ijes.2023.1936911.1639 EN Ahmad Adib Department of Petroleum and Mining Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran. Esmaeil Rahimi Department of Petroleum and Mining Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran. Journal Article 2023 10 01 Magnetite-apatite mineralization in Tarom Mountains at the western part of Alborz-Azerbaijan belt originated from quartz monzonite magma and belongs to high K calc-alkaline, showing a post-collision tectonic environment. The negative trend from LREEs to HREEs is consistent with the spider pattern of the subduction areas. In this article, the recovery of the rare-earth elements (REEs) from apatite flotation concentrate by acid leaching and digestion-water leaching were studied. The total amount of LREEs in the tailings sample is between 1500 - 2600 ppm. The most frequent elements are Ce, La, Nd, and Y. Among them Ce is the most abundant and La is the least.. The maximum LREEs recovery with the sulfuric acid leaching was62% with experimental parameters of 12 M acid concentration, 4 h leaching time, 25℃ heat, and a liquid to solid ratio (L/S) of 1:5. under optimal parameters of (220℃), (3 h), and L/S (1:2), the digesting with sulfuric acid resulted to the recovery of La, Ce, Nd, and Y with 93.92%, 92.22%, 92.04%, and 91.00%, respectively. similarity, the best conditions at water leaching process, are the leaching time of 5 h, at 80℃, and L/S of 1:10 for La, Ce, Nd, and Y recovery are respectively 89.50%, 88.45%, 92.20%, and 94.0%.