US4274879A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synthetic bone ash
Assignee: Tate and Lyle PLC
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Filing: 1980-06-03
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Granted: 1981-06-23
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Expires: 2000-06-03
Abstract
Abstract Hydroxyapatite suitable for incorporation as a synthetic bone ash in a "bone" china body is produced by continuously contacting a stream of a slurry of hydrated lime with a stream of at least about 60% by weight phosphoric acid at an approximately stoichiometric ratio of 10 Ca(OH) 2 to 6 H 3 PO 4 and a temperature of from about 80° to about 85° C. at a controlled reaction mixture of pH of from about 9.0 to about 11.0 and then calcining at a temperature of at least 1,000° C.
Inventors
- 👤 George D. Irvine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:10
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/26; C01B25/32; C01B25/322; C04; C04B; C04B33/00; C04B33/24
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
129 words
A process for producing a hydroxyapatite which has less than 5% by weight content of orthophosphates which comprises contacting a stream of a slurry of hydrated lime with a stream of at least about 60% by weight phosphoric acid at an approximately stoichiometric ratio of 10 Ca(OH) 2 to 6 H 3 PO 4 at a temperature of from about 80° to about 85° C. at a controlled substantially constant reaction mixture pH value which is in the range of from about 9.0 to about 11.0 by continuously introducing said streams into and withdrawing the resulting mixture from a reaction zone wherein the precipitated particulate hydroxyapatite resulting from said contacting is separated from said reactants and wherein the residence time in said reaction zone is up to 90 minutes.
Claim 2
Dependent Claim
129 words
A process for producing a hydroxyapatite which has less than 5% by weight content of orthophosphates which comprises contacting a stream of a slurry of hydrated lime with a stream of at least about 60% by weight phosphoric acid at an approximately stoichiometric ratio of 10 Ca(OH) 2 to 6 H 3 PO 4 at a temperature of from about 80° to about 85° C. at a controlled substantially constant reaction mixture pH value which is in the range of from about 9.0 to about 11.0 by continuously introducing said streams into and withdrawing the resulting mixture from a reaction zone wherein the precipitated particulate hydroxyapatite resulting from said contacting is separated from said reactants and wherein the residence time in said reaction zone is up to 90 minutes.
Claim 3
Dependent Claim
25 words
A process according to claim 1, in which the the lime is added as a suspension of about 10 to about 30% by weight concentration.
Claim 4
Dependent Claim
13 words
A process according to claim 1, in which the maximum pH is 10.5
Claim 5
Dependent Claim
22 words
A process according to claim 2 in which the lime is added as a suspension of 15 to 20% by weight concentration.
Claim 6
Dependent Claim
20 words
A process according to claim 1 wherein the phosphoric acid is of a concentration from 80 to 90% by weight.
Claim 7
Independent Claim
142 words
A method for making a synthetic bone ash for use in "bone" china, which comprises contacting a stream of a slurry of hydrated lime with a stream of at least about 60% by weight phosphoric acid at an approximately stoichiometric ratio of 10 Ca(OH) 2 to 6 H 3 PO 4 and a temperature of from about 80° to about 85° C. at a substantially constant controlled reaction mixture pH value which is in the range of from about 9.0 to about 11.0 by continuously introducing said streams into and withdrawing the resulting mixture from a reaction zone and then separating the precipitated particulate hydroxyapatite and calcining it at a temperature of at least 1,000° C.; and wherein the hydroxyapatite has less than 5% by weight content of orthophosphates and the residence time in said reaction zone is up to 90 minutes.
Claim 8
Independent Claim
142 words
A method for making a synthetic bone ash for use in "bone" china, which comprises contacting a stream of a slurry of hydrated lime with a stream of at least about 60% by weight phosphoric acid at an approximately stoichiometric ratio of 10 Ca(OH) 2 to 6 H 3 PO 4 and a temperature of from about 80° to about 85° C. at a substantially constant controlled reaction mixture pH value which is in the range of from about 9.0 to about 11.0 by continuously introducing said streams into and withdrawing the resulting mixture from a reaction zone and then separating the precipitated particulate hydroxyapatite and calcining it at a temperature of at least 1,000° C.; and wherein the hydroxyapatite has less than 5% by weight content of orthophosphates and the residence time in said reaction zone is up to 90 minutes.
Claim 9
Dependent Claim
16 words
A method according to claim 6 in which the calcining temperature is at least 1150° C.
Claim 10
Dependent Claim
39 words
A method according to claim 6 in which the hydroxyapatite is calcined by being heated at a rate of about 200° C. per hour to about 1050° C. and is then held at this temperature for about 1 hour.
Claim 11
Dependent Claim
29 words
A method according to claim 6 in which the hydroxyapatite is calcined by being passed through a rotating tube calciner lined with refractory material and inclined to the horizontal.
Claim 12
Dependent Claim
35 words
A "bone" china body comprising up to 50% by weight of synthetic bone ash obtained by the method of claim 6 together with about 25% by weight each of china clay and a stone flux.
Claim 13
Dependent Claim
14 words
A ceramic "bone" china obtained by firing a body as claimed in claim 10.
Claim 14
Dependent Claim
34 words
A process according to claim 1 in which said streams are free of metal ions which might lead to a colored ceramic body being produced when said product is thereafter used in "bone" china.
Claim 15
Dependent Claim
16 words
A process according to claim 7 in which the calcining temperature is at least 1200° C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-06-22 | 1984-12-22 | 1985-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-22 | 1988-12-22 | 1989-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-22 | 1992-12-22 | 1993-06-23 | $7700.00 | Window Closed / Lapsed |