Process for preparing hydrated alumina consisting essentially of spherical particles by homogeneous precipitation
AssigneeMontedison S.p.A.
InventorsFranco Montino, Giuseppe Spoto
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Abstract
A process for preparing hydrated alumina consisting essentially of spherical particles having a narrow granulometric distribution (polydispersion index dw/dn.ltoreq.2) starting from aqueous solution of aluminum sulphate, the molar ratio SO.sub.4.sup.= /Al.sup.3+ being greater than 1, by homogeneous precipitation in the presence of cationic polyelectrolytes, which are soluble under the reaction conditions and have a mean molecular weight higher than one million and an ionicity, deriving from the cationic groups present in the polyelectrolyte, of at least 3 milliequivalents/gram.
Claims17
In a process for homogeneously precipitating hydrated alumina from an aqueous solution comprising aluminum sulphate having an SO.sub.4 /Al.sup.3+ ratio greater than 1 and compounds capable of releasing hydroxy ions so as to avoid local saturation of hydroxy ions in the solution, said hydrated alumina consisting of spherical particles having a diameter of from 0.06 to 3.0 microns and a polydispersion index dw/dn less than or equal to 2, the improvement that comprises carrying out said precipitation in the presence of cationic polyelectrolytes in concentrations at which no separate solution forms, said cationic polyelectrolytes having a mean molecular weight greater than 1.0.times.10.sup.6 and an ionicity of at least 3 milliequivalents per gram.
Dependencies are inferred from the claim text.