Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
232 words
In the process of reacting sodium silicofluoride having a particle size of less than 250 microns and ammonia in an aqueous medium to produce silica, sodium fluoride and ammonium fluoride, the improvement comprising: a. adding ammonia, in the form of a member selected from the group consisting of free ammonia gas and aqueous ammonium hydroxide having a concentration, calculated as free ammonia, of at least about 7.5 weight percent, at a rate such that the concentration of ammonium hydroxide in the reaction medium is less than about 5 weight percent over a period of at least about 60 minutes, until substantially all the sodium silicofluoride is reacted: b. agitating to a degree greater than that required to disperse sodium fluoride crystals and silica gel of said reaction medium produced in the course of said addition of ammonia and for a period of at least about 20 minutes after completion of said addition of ammonia: c. after completion of the reaction, adding a stoichiometric excess of said ammonia in an amount such that the total ammonium ion concentration consisting of ammonium fluoride and ammonium hydroxide in the reaction medium is more than 7.5 weight percent, calculated as free ammonia; and d. separating sodium fluoride crystals having a particle size of more than 100 microns and silica gel having a particle size of less than 5 microns thus prepared separately from ammonium fluoride solution.
Claim 2
Dependent Claim
232 words
In the process of reacting sodium silicofluoride having a particle size of less than 250 microns and ammonia in an aqueous medium to produce silica, sodium fluoride and ammonium fluoride, the improvement comprising: a. adding ammonia, in the form of a member selected from the group consisting of free ammonia gas and aqueous ammonium hydroxide having a concentration, calculated as free ammonia, of at least about 7.5 weight percent, at a rate such that the concentration of ammonium hydroxide in the reaction medium is less than about 5 weight percent over a period of at least about 60 minutes, until substantially all the sodium silicofluoride is reacted: b. agitating to a degree greater than that required to disperse sodium fluoride crystals and silica gel of said reaction medium produced in the course of said addition of ammonia and for a period of at least about 20 minutes after completion of said addition of ammonia: c. after completion of the reaction, adding a stoichiometric excess of said ammonia in an amount such that the total ammonium ion concentration consisting of ammonium fluoride and ammonium hydroxide in the reaction medium is more than 7.5 weight percent, calculated as free ammonia; and d. separating sodium fluoride crystals having a particle size of more than 100 microns and silica gel having a particle size of less than 5 microns thus prepared separately from ammonium fluoride solution.
Claim 3
Dependent Claim
26 words
The process of claim 1 wherein said member is aqueous ammonium hydroxide having a concentration, calculated as free ammonia, of about 15 to 45 weight percent.
Claim 4
Dependent Claim
53 words
The process of claim 1 wherein said ammonium fluoride is reacted with a member selected from the first group consisting of sodium hydroxide, sodium chloride, and sodium sulfate to produce sodium fluoride and an aqueous solution of the corresponding member selected from the second group consisting ammonium hydroxide, ammonium chloride, and ammonium sulfate.
Claim 5
Dependent Claim
29 words
The process of claim 3 wherein the member selected from said first group is added as an aqueous solution having a concentration of at least about 10 weight percent.