Home – Home – Jornals – Chemistry for Sustainable Development 2018 number 2

The causes and ways of reducing losses of zirconium and other rare elements with silica residues upon acid treatment of eudialite concentrate, i.e. a raw source of zirconium, hafnium, and rare earth elements of the middle and yttrium groups, were explored. Metals distribution was examined during acid treatment with 2 mass % solutions of nitric and sulphuric acids in the presence of sulphocationite. It was found that decomposition of the eudialite, the main Zr-containing mineral, proceeded entirely. Herewith, losses of zirconium and other rare elements with silica residues formed during nitric acid and sulphuric acid processing of eudialite concentrate are mainly related to their ingress to silica gels. Rare elements are present therein as bridges of hydrated silica-based polymers that are bridge-coupled by hydroxyl (olation) or oxygen (oxyolation). As demonstrated, zirconium and other elements may be additionally derived by acid treatment. Their losses with silica residues may be reduced during eudialite concentrate decomposition in the presence of sulphocationite with sol production in the initial stage.