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Utilising fluorosilicic acid for zeolite prodn. - by converting to sodium fluoride and mixing by=product sodium silicate with sodium aluminate under hydrothermal crystallisation conditions
Utilising fluorosilicic acid for zeolite prodn. - by converting to sodium fluoride and mixing by=product sodium silicate with sodium aluminate under hydrothermal crystallisation conditions
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机译：利用氟硅酸生产沸石。 -通过转化为氟化钠并在水热结晶条件下将副产物硅酸钠与铝酸钠混合
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摘要
Process for valorising fluosilicic acid (I) by converting it to NaF, characterised in that the Na silicate soln. obtd. as by-prod. in the prodn. of NaF is mixed with a soln. of Na aluminate in the presence of excess NaOH and the mixt. is subjected to hydrothermal crystallisation to form a zeolite which is sepd. from the mother liquor. Pref. the solns. are mixed at atmos. pressure and at 85-95 deg.C and are allowed to mature at this temp. for 4-8 hrs. Pref. sufficient NaOH is added to give a pH of over 13. Pref. part of the mother liquor obtd. by recovery of the zeolite is used to make the zeolite-forming soln. The NaF is made by reacting the (I) with NaOH or with Na2CO3 in the presence of NaOH. Process allows valorisation of (I) formed e.g. as by-prod. in the prodn. of phosphoric acid, to give useful crystalline zeolite product and without forming excessive amts. of effluent liquors which are difficult to dispose of.
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