Carlo Adamoli
Process for the extration of bases of rare elements contained in ores and rocks

Pagina 13

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5. In a cyclic process for the extraction of bases of rare elements of the group consisting of thorium, tantalum, caesium, niobium, zirconium, germanium, scandium, beryllium and lithium, contained in relatively small proportions in silicated minerals, the steps consisting of crushing the mineral, mixing it in a paste with a metal fluoride not easily soluble in water, and an aqueous solution containing nitric acid and an excess of a water soluble alkali-metal nitrate, heating said paste at a low temperature to form a water soluble salt of the metal of the said fluoride, expelling from the paste the liquid containing the said water soluble salt, briquetting the paste and heating it to a high temperature to form water soluble fluorine compound of the rare element to be extracted, lixiviating the reaction product, separating therefrom a solution containing the fluorine compound of the rare element and at least a part of the initial alkali-metal nitrate, electrolyzing said solution to precipitate the rare element in the form of an insoluble hydroxide, separating said precipitate, regenerating from the residual liquid and from the liquid expelled from the first named paste the not easily water soluble metal fluoride, the nitric acid and the water soluble alkali-metal nitrate, and returning them into the cycle.

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