Claims
- 1. A method of preparing high purity barium sulfate having a maximum total of 5 ppm impurities comprising:
- reacting a barium compound selected from the group consisting of barium nitrate, barium perchlorate, barium nitrite, barium thiosulfate, and barium salts of formic and acetic acid with a sulfur-containing species selected from the group consisting of ammonium sulfate, ammonium bisulfate and ammonium pyrosulfate compounds, free sulfur and mixtures thereof at an elevated temperature of at least about 150.degree. C. under solid state conditions, with the proviso that where said barium compound is a barium salt of formic and acetic acid, then said sulfur-containing species is selected from the group consisting of ammonium sulfate, ammonium bisulfate and ammonium pyrosulfate compounds.
- 2. The method of claim 1 wherein said barium compound consists essentially of barium nitrate.
- 3. The method of claim 1 wherein said sulfur-containing species is present in an excess relative to said barium compound.
- 4. The method of claim 3 wherein said sulfur-containing species is present in a molar ratio of at least about 5:1 relative to said barium compound.
- 5. The method of claim 1 wherein said sulfur-containing species comprises both sulfur and an ammonium sulfate salt.
- 6. The method of claim 1 wherein during the step of reacting, said barium compound and said sulfur-containing species are heated to a first temperature for a first period of time and sequentially to a second temperature, which is higher than said first temperature, for a second period of time, the total of both said periods of time being sufficient to effect formation of said barium sulfate.
- 7. The method of claim 1 wherein said solid-state reaction is carried out at a first temperature ranging from about 150.degree. to 350.degree. C. for a first period of time and then at a second temperature ranging from about 600.degree. to 700.degree. C. for a second period of time in the presence of free sulfur.
- 8. The method of claim 7 wherein said first temperature ranges from about 200.degree. to 250.degree. C.
- 9. The method of claim 1 wherein said solid-state reaction is carried out at a first temperature ranging from about 150.degree. to 350.degree. C. for a first period of time and then at a second temperature ranging from about 400.degree. to 550.degree. for a second period of time in the presence of at least one sulfur-containing species which includes a sulfur-containing compound selected from the group consisting of ammonium sulfate, ammonium bisulfate and ammonium pyrosulfate compounds.
- 10. The method of claim 1 wherein said solid-state reaction is carried out at a temperature ranging from about 400.degree. to 450.degree. C. for a period of time sufficient to effect formation of said barium sulfate in the presence of at least one sulfur-containing species which includes a sulfur-containing compound selected from the group consisting of ammonium sulfate, ammonium bisulfate and ammonium pyrosulfate compounds.
- 11. A method of preparing high purity barium sulfate having a maximum total of 5 ppm impurities comprising reacting a barium nitrate with a sulfur-containing species comprising at least one member selected from the group consisting of free sulfur and ammonium sulfate and ammonium bisulfate compounds, said sulfur-containing species being present in an excess relative to said barium nitrate, said reaction being carried out at an elevated temperature of at least about 150.degree. C. under solid state conditions.
- 12. The method of claim 11 wherein said sulfur-containing species is present in a molar ratio of at least about 5:1 relative to said barium nitrate.
- 13. The method of claim 11 wherein said sulfur-containing species comprises both sulfur free and an ammonium sulfate salt.
- 14. The method of claim 11 wherein during the step of reacting, said barium nitrate and said sulfur-containing species are heated to a first temperature for a first period of time and sequentially to a second temperature, which is higher than said first temperature, for a second period of time, the total of both said periods of time being sufficient to effect formation of said barium sulfate.
- 15. The method of claim 11 wherein said solid-state reaction is carried out at a first temperature ranging from about 150.degree. to 350.degree. C. for a period of time and then at a second temperature ranging from about 600.degree. to 700.degree. C. for a period of time in the presence of free sulfur.
- 16. The method of claim 15 wherein said first temperature ranges from about 200.degree. to 250.degree. C.
- 17. The method of claim 11 wherein said solid-state reaction is carried out at a first temperature ranging from about 150.degree. to 350.degree. C. for a period of time and then at a second temperature ranging from about 400.degree. to 550.degree. C. for a period of time in the presence of at least one sulfur-containing species which includes a sulfur-containing compound selected from the group consisting of ammonium sulfate, ammonium bisulfate and ammonium pyrosulfate compounds.
- 18. The method of claim 11 wherein said solid-state reaction is carried out at a temperature ranging from about 400.degree. to 450.degree. C. for about 30 to 60 min in the presence of at least one sulfur-containing species which includes a sulfur-containing compound selected from the group consisting of ammonium sulfate, ammonium bisulfate and ammonium pyrosulfate compounds.
Parent Case Info
This is a continuation of application Ser. No. 07/678,088, filed Apr. 1, 1991, now abandoned.
US Referenced Citations (5)
Foreign Referenced Citations (7)
Number |
Date |
Country |
2307254 |
Aug 1973 |
DEX |
2449649 |
Sep 1980 |
FRX |
47-1008 |
Jan 1972 |
JPX |
49-11728 |
Mar 1974 |
JPX |
55-42233 |
Mar 1980 |
JPX |
779298 |
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SUX |
2216510 |
Oct 1989 |
GBX |
Continuations (1)
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Number |
Date |
Country |
Parent |
678088 |
Apr 1991 |
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