Leaching of rare earths from Abu Tartur (Egypt) phosphate rock with phosphoric acid

Abstract

The leaching of rare earth elements (REEs) from Egyptian Abu Tartur phosphate rock using phosphoric acid has been examined and was subsequently optimized to better understand if such an approach could be industrially feasible. Preliminary experiments were performed to properly define the design of experiments. Afterward, 24 full factorial design was implemented to optimize the leaching process. Optimum REEs leaching efficiency (96.7 ± 0.9%) was reached with the following conditions: phosphoric acid concentration of 30 wt.-% P2O5, liquid/solid ratio, mL/g, of 5:1, at 20 °C, and 120 min of leaching time. The apparent activation energy of the dissolution of REEs from phosphate rock using the phosphoric acid solution was -19.6 kJ/mol. D2EHPA was subsequently applied as an organic solvent for REEs separation from the acquired leach liquor. REEs stripping and precipitation were conducted, and finally, rare earth oxides with a purity of 88.4% were obtained. The leach liquor was further treated with concentrated sulfuric acid to recover the used phosphoric acid and produce gypsum with a purity of >95% at the same time. A flow diagram for this innovative cleaner production process was developed, and larger-scale experiments are proposed to further understand this promising approach to comprehensive phosphate rock processing.

Potential Future Alternative Resources for Rare Earth Elements: Opportunities and Challenges

“…The REE content in seamount phosphorites is far greater than in continental margin phosphorites [39]. Morocco has the largest phosphate ore reserves in the world with 50 billion tons, followed by China and Egypt with 3.2 and 2.8 billion tons of phosphate ores respectively [65]. Based on the REE concentration data presented in Table 2.…”

“…Initially, people used red mud to make bricks, and in cement production, but its potential to be an alternative resource for REE has been recently realised. During the production of wet phosphoric acid and phosphate fertilizer from phosphate ores, a solid phosphogypsum byproduct is produced to which most of the REE (>80%) in the phosphate ore are transferred [65]. Phosphogypsum can show low levels of radioactivity because of the presence of small amounts of uranium and thorium, but also useful as a valuable REE resource (Table 6).…”

Kinetics of Estonian Phosphate Rock Dissolution in Hydrochloric Acid

“…When a solid contacts a liquid, the following reactions can occur: A(fluid) + B(solid) → fluid products(C) → solid products (D) → fluid and solid products(E) The kinetics of apatite dissolution in strong acids have been studied/examined using mathematical models such as pseudo-homogeneous models [34], the shrinking core model (SCM) [35,36], and the Avrami-Erofeev equation [37,38].…”

Leaching of rare earth elements from phosphate rock using sulfuric acid: Process optimization and kinetic studies

“…Commercial phosphoric acid is mainly produced by wet production process, in which phosphate rock is treated with sulfuric acid to produce liquid phosphoric acid (as a main product) and solid phosphogypsum as a byproduct (Liu et al, 2022). During the wet production process, REEs in the phosphate rock is distributed between the two phases, whereas about 20% exist in the liquid phosphoric acid, while about 80% transferred to the phosphogypsum (Battsengel et al, 2018;Lütke et al, 2022;Roshdy et al, 2023). Accordingly, the recovery of REEs from the phosphate rock will be more effective approach than the recovery of REEs from two phases (phosphoric acid and phosphogypsum).…”

“…Introduced Fanshan phosphate material, China for the phosphoric acid for the leaching of REEs (Wu et al, 2019). Investigated the dissolution of REEs from Abu-Tartur phosphate rock, Egypt (Roshdy et al, 2023).…”