Abstract
This study explores the synthesis of sorption-active phosphate materials from manganese ore enrichment tailings of the Zhairem deposit. The initial tailings, predominantly composed of calcite (76.4 %), quartz (16.4 %), and braunite, were characterized by XRD and EPMA. Acid-thermal treatment with phosphoric acid followed by calcination at 200-800°C yielded calcium - manganese phosphate materials. Phase transformations were monitored via XRD, showing formation of crystalline phosphates at 200 - 600°C and a glassy phase at 800°C. The product synthesized at 600°C demonstrated the lowest water solubility (9.91 %), highest pore volume (0.175 cm³ g-1), and optimal sorption capacity for Ni2+ (0.2934 mg-eq g-1), which increased to 0.4697 mg-eq g-1 after 0.4 wt. % of HCl activation. The enhanced performance is attributed to the formation of low-solubility polyphosphates and well-developed porous structures. SEM confirmed porous morphology at 600°C and denser, glassy structure at 800°C. The synthesized material showed no toxic elements such as Pb, Cd, or As, making it suitable for environmental applications. The findings indicate that Zhairem tailings are a promising raw material for producing effective sorbents for heavy metal removal, especially after acid activation. The optimal product is the calcium-manganese phosphate synthesized at 600°C.