Strontium Extraction from the Geo-environment

Strontium, a highly reactive alkaline earth metal, is very stable in natural occurrence minerals; however, the mobility of its isotope ⁹⁰Sr produced from the nuclear fallout is one of the deadly fission products. Celestite, SrSO_4, is the most important primary source of it following the exploitation via either the black ash or direct leach process. For which, the illustration of the thermal and aqueous chemistry of strontium is very crucial. In the case of ⁹⁰Sr, its separation from the other radionuclide, most specifically over the ¹³⁷Cs from the high-level waste (HLW) of fission products, is vital, converting the HLW to low-level waste (LLW). Liquid-liquid (solvent) extraction technology has been widely accepted for the efficient separation and recovery of strontium from the fission products, as the radionuclide already remains in its soluble form therein the waste solution. Interaction strategy between the metal ion and dipole from the donor atom of crown ether is prominently being used, whereas the poorly hydrated anions of dicarbollide, a boron cluster with a π-bonded trivalent cobalt ion, form ion-pair neutral compounds in the extraction process. In this chapter, the extraction processes of strontium from both natural mineral and synthetic source of the waste fission solution are being discussed, which includes the process technology, adopted techniques behind the technology, crucial points, and key parameters.