Process for the post-treatment of titanium dioxide pigments
AssigneeSocieta' Italiana Resine S.I.R. S.p.A.
InventorsLuigi Piccolo, Benedetto Calcagno, Emilio Bossi
Life of this patent
Estimating the term…
Abstract
Titanium dioxide is post-treated by flowing it in a tubular zone as a suspension in a stream of carrier gas, injecting a gaseous stream of halides of Si, Ti and Al in said stream and then steam in the resulting mixture, once the latter is homogenized.
Claims14
A method for the post-treatment of titanium dioxide pigments, which comprises flowing in an elongated tubular reaction zone a suspension of subdivided particlces of titanium dioxide of a size from about 0.1 to 1 micron in a stream of carrier gas in which particle concentration is from 5 to 50 Kg per m.sup.3 of carrier gas at a temperature of from 100.degree. to 250.degree. C, injecting into said stream at one or more points along said tubular reaction zone a gaseous flow of one or more halides selected from the group consisting of the halides of aluminum, silicon and titanium in an overall amount corresponding to from 1 to 20% by weight, calculated as oxides, with respect to the feed in titanium dioxide, and injecting, downstream of each point of injection of said gaseous flow at a distance from the latter sufficient to allow the homogenization of the resulting mixture therein, a flow of steam in said mixture in an amount of from the stoichiometric value required for the transformation into hydroxides of said halides injected at said point to 50% in excess with respect to said stoichiometric value.
A method for the post-treatment of titanium dioxide pigments, which comprises flowing in an elongated tubular reaction zone a suspension of subdivided particles of titanium dioxide in a stream of carrier gas at a temperature of from 100.degree. to 250.degree. C, injecting into said stream at one or more points along said tubular reaction zone a gaseous flow of one or more halides selected from the group consisting of the halides of aluminum, silicon and titanium in an overall amount corresponding to from 1 to 20% by weight, calculated as oxides, with respect to the feed in titanium dioxide, and injecting, downstream of each point of injection of said gaseous flow at a distance from the latter sufficient to allow the homogenization of the resulting mixture therein, a flow of steam in said mixture in an amount of from the stoichiometric value required for the transformation into hydroxides of said halides injected at said point to 50% in excess with respect to said stoichiometric value.
Dependencies are inferred from the claim text.