ZrSiO4 + 5NaOH + 3H2O ⇄ Na[Zr(H2O)3(OH)5] + Na4SiO4
Zirconium(IV) orthosilicate react with sodium hydroxide and water to produce pentahydroxotriaquazirconate(IV) sodium and sodium orthosilicate. This reaction takes place at a temperature near 400°C and an overpressure.