Adsorption behaviour of sodium hexametaphosphate on pyrochlore and calcite

作者：Ni X; Liu Q^*

来源：Canadian Metallurgical Quarterly, 2013, 52(4): 473-478.

DOI：10.1179/1879139513Y.0000000088

• Hexametaphosphate
• Calcite
• Niobium oxide
• Rare earth oxide
• Hydroxamic acid

FTIR, XPS and zeta potential measurements were performed on pyrochlore and calcite to study the adsorption mechanisms of sodium hexametaphosphate (NaHMP). While no hexametaphosphate could be detected on the FTIR spectra of NaHMP treated pyrochlore or calcite, the observed chemical shifts of the binding energies of Ca 2p(5/2) (0.25 eV) and P 2p (0.20 eV) electrons indicated that the hexametaphosphate groups formed a complex with calcium on calcite. The complex seemed soluble in water leaving a low concentration of its residue on calcite surface after water washing, thus undetectable by FTIR. The binding energy shifts of Nb 3d(5/2) (0.13 eV) and Ca 2p(5/2) (0.10 eV) electrons on NaHMP-treated pyrochlore were within instrumental resolution, therefore, NaHMP was not strongly bound to pyrochlore. The zeta potentials of pyrochlore and calcite were both lowered in the presence of NaHMP. However, for pyrochlore, the zeta potential drop occurred mainly in the acidic pH range, while the drop for calcite was independent of pH, indicating possible chemisorption of NaHMP on calcite. The work explained the selective depressive function of NaHMP in the hydroxamic acid flotation of carbonatite niobium ores.

• 出版日期2013-10