Abstract: Taking alkaline zirconium residue as the research object, different phosphorus containing materials were used to stabilize Uranium in alkaline zirconium residue, with the aim to analyze the stabilization effects and mechanisms. The result shows that among several phosphorus containing materials used in the experiment, Ca(H₂PO₄)₂, KH₂PO₄, CaHPO₄, and Ca₃(PO₄)₂ can all achieve stabilization effects, while Ca(H₂PO₄)₂ and KH₂PO₄ having the best stabilization effect on Uranium, with stabilization efficiency of 98.35% and 99.59%, respectively. K₂HPO₄ can promote Uranium activation leaching in alkaline zirconium residue, which is related to the generation of HCO₃^- in alkaline conditions. The stabilization principle of Ca(H₂PO₄)₂ and KH₂PO₄ is to promote the transition from carbonate bound state and organic bound state Uranium to residual state. The stabilization effect is greatly affected by the acidity and alkalinity of the environment, and acidic conditions are more conducive to its stabilization. The stabilizing effect of Ca(H₂PO₄)₂ and KH₂PO₄ on Uranium in alkaline zirconium residue is positively correlated with the dosage. The optimal dosage of Ca(H₂PO₄)₂ and KH₂PO₄ is 1.2%, After stabilization, the proportion of residual state Uranium is about 98.6%. HCO₃^- is the main factor affecting the long-term stability of Uranium. Within about 90 days, HCO₃^- can cause the stable Uranium in alkaline zirconium residue to leach out again. Ca(H₂PO₄)₂ and KH₂PO₄ can effectively inhibit the activation leaching of U in alkaline zircon residue by HCO₃^-, and the inhibitory effect of Ca(H₂PO₄)₂ is better than that of KH₂PO₄.

Key words: alkaline zirconium residue, phosphorus containing materials, Uranium, stabilization, HCO₃^-