| 摘要 |
Leachability of the V content is reduced by initial contact with a polyvalent metal water soluble salt in the presence of water. The salt forms an acidic soln. which forms hydroxide, oxide or hydrated oxide insoluble at pH5. The metal ions in the salt have a valence of at least 3 or are divalent ions oxidisable to a higher valency. The salt cation is Fe(II), Fe(III), Sn(II), Sn(IV), Ti(IV), Zr(IV), Al(III), trivalent rare metal and/or quadrivalent rare earth metal. The anion in sulphate, nitrate or chloride. The pH of the mixt. is increased to at least 7 by welding a Ca-, Mg- or Na-base.
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