Separation of Sc2O3 from Bayan Obo tailings through an innovative roasting method

Abstract

Sc 2 O 3 was successfully extracted and separated from Bayan Obo tailings by a CaCl 2 -reductive carbon powder-combinative roasting method. The optimum process condition was obtained through adjusting specific effect factors. It is found that Sc 2 O 3 with the ratio of 87.51 % is leached out under roasting temperature of 800°C for 2 h through adding 73 % CaCl 2 , and 20 % reductive carbon powder with liquid to solid ratio of 3. Moreover, the specific reaction mechanism during roasting process was investigated by thermogravimetric-differential scanning calorimetry (TG-DSC) and X-ray diffraction (XRD) techniques. The results show that the main phases (SiO 2 , CaF 2 and NaFeSi 2 O 6 ) as well as important phases (LiScSi 2 O 6 , REFCO 3 and REPO 4 ) would turn into new phases (CaFeSiO 4 , Fe, Ca 3 (PO 4 ) 2 , NaCl, RE 2 O 3 and Sc 2 O 3 ) after complicated reactions, which effectively break up the original mineral compositions and activate the existing state of containing scandium matter, consequently facilitating the subsequent hydrochloric acid leaching process.

Efficient Step-by-Step Desorption to Reduce Boron in Brine Lithium Extraction

“…31-0704). Combined with the crystal plane spacing in Table , it could be found that all different samples met d (003) = 2 d (006) , indicating that the layered structure of different Li/Al-LDHs samples was not damaged . In addition, it was worth noting that the interlayer spacing after boron intercalation/deintercalation was correspondingly expanded.…”

“…Combined with the crystal plane spacing in Table 2, it could be found that all different samples met d (003) = 2d (006) , indicating that the layered structure of different Li/Al-LDHs samples was not damaged. 34 In addition, it was worth noting that the interlayer spacing after boron intercalation/deintercalation was correspondingly expanded. When B(OH) 4 − was inserted into the interlayer, d (003) could increase accordingly, which proved its role in expanding the interlayer spacing by replacing Cl − .…”

The Process Mineralogical Characterization of Bayan Obo Rare-Earth Tailings and Density Functional Theory Study of the Occurrence State of Sc

“…Bayan Obo tailing pond, one of the world's largest rare-earth tailing ponds [8], contains tailings generated since the 1960s, at the rate of 386,000 tpa [9][10][11][12]. Currently, the tailing pond covers approximately 12 km 2 and stores approximately 200 million tons of tailings [13][14][15][16][17]. Tailings contain a large amount of iron, rare-earth elements, fluorine, Niobium, and other elements, which are a valuable secondary resource [18][19][20].…”