| 摘要 |
<p>A process for extracting rare-earth elements from phosphate ore while the said ore is being treated to produce phosphoric acid or fertilizer involves mixing the finely divided ore with phosphoric acid, which is present in excess for producing monocalcium phosphate, causing it to decompose by heating it until the liquid phase of the resulting sludge is in a state close to the equilibrium solubility state of calcium, and subsequently separating out from the sludge the solid residue containing the compounds of calcium and rare-earth elements. Separation of the solid residue from the sludge starts as soon as the particles consisting mainly of phosphate compounds of calcium attain a size at least ten times greater than that of the particles containing predominantly rare-earth compounds; the solid residue is separated into coarse-dispersion and fine-dispersion fractions, and the fine-dispersion fraction containing the particles formed predominantly from rare-earth compounds is drawn off and serves as a concentrate of rare-earth ccompounds.</p> |
