The preparation and characterisation of hydroxycancrinite-type zeolite from the effluent produced from the hydrometallurgical upgrade of iron ore

• A novel approach towards effluent valorisation from iron ore was proposed. • Hydroxycancrinite-type zeolite was produced using hydrothermal crystallisation. • The produced cancrinite product had a Si/Al ratio of 1.43. • The synthesised material was mesoporous, showing good adsorption properties. • Crystallisation kinetics followed the first-order Avrami kinetic model. Iron ore often contains impurities such as aluminium, silicon, and phosphorus, which degrade its quality. To enhance the iron ore's quality, it is crucial to remove these gangue elements. One effective method for their removal is caustic leaching. However, this process produces an effluent of sodium aluminium silicate with significant phosphate ions. In this work, an attempt has been made to successfully synthesise hydroxycancrinite-type zeolite from the effluent produced from the hydrometallurgical upgrade of iron ore. The effect of various operating conditions, such as crystallisation temperature, time and alkalinity, on the crystallisation process was investigated. The study found that temperature and time play crucial roles in the formation of cancrinite in high-alkaline solutions. The final products were characterised using various techniques, including powder X-ray diffraction, scanning electron microscopy, elemental analyses, Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) surface area measurements and particle size analysis. The Si/Al ratio observed in the product framework is roughly 1.43. XRD and FESEM data confirm that well-crystallised cancrinite-type zeolite was synthesised at 160°C and above 24h of crystallisation temperature and time, respectively. N 2 adsorption-desorption analysis of all products confirms the mesoporous properties, with a surface area of 48.96 m²/g and a pore volume of 0.4 cm³/g, and a pore diameter of 14nm for the 24-h crystallised product, indicating the properties of a good adsorbent. Crystallisation kinetics was studied using the Avrami equation, and it was found that the crystallisation process at 160°C is first order, having a rate constant of 2*10 -2 (h- 1 ).