Carlo Adamoli
Process for the extration of bases of rare elements contained in ores and rocks
Pagina 6
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The liquid of the lixiviatlon is then introduced into the cathodic compartment of an electrolyzer for potassium chloride of the mercury type, in which zirconium hydrate precipitates. The reaction which is produced between the solution and the potassium cation is as follows:
The obtained precipitate is then recovered in a fllter-press, while the liquid, which is formed of a mixture of fluorinated and chlorinated potassium salts, Is mixed in the large vessel in which the solution of magnesium and potassium s,alts which has been expelled from the paste has been formerly collected. The magnesium fluoride is then re-formed In this vessel by precipitation and separated by decantation and then conveyed to the first phase of the operation. The reaction which takes place between both solutions is as follows:
The liquid which has been decanted and separated from the magnesium fluoride is concentrated until it contains from 30 to 32% of potassium chloride; half of this concentrated solution is Introduced into the reaction chamber of the mercury electrolyzer for a fresh operation, while the chlorine which has been converted into hydrochloric acid In an apparatus of the Deacon type is introduced with the other half of the above mentioned concentrated solution Into the pressure mixer C, in order to re-form the salt-acid solution of the first treatment. The conversion in the apparatus of Deacon is the known conversion:
If the precipitation, according to the reaction which has been cited in the first place, is performed by caustic potash which has been previously obtained in the electrolyzer, the above mentioned conversion can be replaced by a direct synthesis starting from the hydrogen and the chlorine which are developed on the anode and on the cathode, whereby the hydrochloric acid which is necessary can be obtained. There is thus neither a consumption of fluoride nor a consumption of salts nor of acid, with the exception of the losses in the apparatus; the cycle of operations is entirely closed, simple and economical, and the zirconium hydrate which is produced contains about 3.1 to 3.2 kg. of ZrO2.H2O. |
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