US4979987A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Precious metals recovery from refractory carbonate ores
Assignee: FIRSTMISS GOLD Inc A CORP OF NV
•
Filing: 1988-07-19
•
Granted: 1990-12-25
•
Expires: 2008-07-19
Abstract
Abstract Precious metal values, particularly gold and silver, are liberated from refractory, carbonate ores by adjusting the molar ratio of sulfide to total acid consumers to between about 1.2 and about 3.2 in the ore feed to a pressure oxidation process. The ore is contacted with oxygen to oxidize sulfide in the ore with at least about 65 percent of the sulfide oxidation occurring in a first oxidation zone at a temperature above about 360 DEG F. The oxidation of sulfide forms at least about 5 grams of free sulfuric acid in the first oxidation zone. The oxidation process is continued in subsequent oxidation zones. A gas stream is removed from the oxidation zones and oxygen is separated from carbon dioxide and other inerts in the gas stream and the purified oxygen is recycled to the oxidation zones.
Inventors
- 👤 Peter C. Mason
- 👤 Patrick T. O'Kane
- 👤 Robert Pendreigh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 00:02
CPC Classifications
C; C22; C22B; C22B11/00; C22B11/04
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
192 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed, wherein said molar ratio of sulfide to total acid consumers is adjusted by contacting said ore feed with sulfuric acid to convert carbonate to carbon dioxide; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone.
Claim 2
Independent Claim
192 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed, wherein said molar ratio of sulfide to total acid consumers is adjusted by contacting said ore feed with sulfuric acid to convert carbonate to carbon dioxide; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone.
Claim 3
Independent Claim
182 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone, and wherein said final oxidized pulp slurry has an EMF of at least about 500 millivolts.
Claim 4
Independent Claim
182 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone, and wherein said final oxidized pulp slurry has an EMF of at least about 500 millivolts.
Claim 5
Independent Claim
185 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone, and wherein said final oxidized pulp slurry contains at least about 10 grams of free sulfuric acid per liter.
Claim 6
Independent Claim
185 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone, and wherein said final oxidized pulp slurry contains at least about 10 grams of free sulfuric acid per liter.
Claim 7
Independent Claim
168 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 70 percent of said conversion of sulfide occurs in said first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone.
Claim 8
Independent Claim
168 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 70 percent of said conversion of sulfide occurs in said first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone.
Claim 9
Independent Claim
214 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, and wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone; and (c) contacting said final oxidized pulp slurry with an alkaline solution containing cyanide to solubilize precious metal values, wherein said solubilized metal values are adsorbed on activated charcoal, said charcoal is separated from said pulp, and said metal values are then stripped from said charcoal and recovered.
Claim 10
Independent Claim
214 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, and wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone; and (c) contacting said final oxidized pulp slurry with an alkaline solution containing cyanide to solubilize precious metal values, wherein said solubilized metal values are adsorbed on activated charcoal, said charcoal is separated from said pulp, and said metal values are then stripped from said charcoal and recovered.
Claim 11
Independent Claim
167 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of between about 1.4 and about 1.7 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone.
Claim 12
Independent Claim
167 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of between about 1.4 and about 1.7 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone.
Claim 13
Independent Claim
180 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed, wherein at least about 90 mole percent of said acid consumers is carbonate; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone and wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone.
Claim 14
Independent Claim
180 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed, wherein at least about 90 mole percent of said acid consumers is carbonate; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone and wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone.
Claim 15
Independent Claim
207 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone, and wherein the slurry in said oxidation zones is between about 360° F. and about 440° F., said oxygen is present in said gas phase with a partial pressure of at least 25 psia, and the total gas pressure in said first oxidation zone is about 300 to about 500 psia.
Claim 16
Independent Claim
207 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; and (b) contacting an aqueous slurry of said adjusted ore feed with oxygen in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone, and wherein the slurry in said oxidation zones is between about 360° F. and about 440° F., said oxygen is present in said gas phase with a partial pressure of at least 25 psia, and the total gas pressure in said first oxidation zone is about 300 to about 500 psia.
Claim 17
Dependent Claim
34 words
The method of claim 8 wherein the temperature in said oxidation zones is between about 400° F. and about 420° F. and the partial pressure of said oxygen is at least about 80 psia.
Claim 18
Independent Claim
417 words
A method for liberating gold and silver present in refractory carbonate ores, said method comprising: (a) adding sufficient sulfuric acid to a water slurry containing particlized ore to convert a portion of inorganic carbonates in said ore to carbon dioxide and react with other acid consumers in said ore to provide a slurry of pretreated ore having a molar ratio of sulfide to total acid consumers in said pretreated ore of between about 1.2 and about 3.2; (b) heating said slurry of pretreated ore pulp to a temperature of at least about 260° F. to provide a heated pulp slurry; (c) subjecting said heated pulp slurry to a pressure oxidation process in which said slurry is added to a first oxidation zone and is then passed sequentially through at least four subsequent oxidation zones wherein at least 50 volume percent of the total volume of all the slurry contained in all the oxidation zones is contained in the first oxidation zone, wherein each oxidation zone has a gas phase and a slurry phase in which at least a portion of the sulfide in said pulp is oxidized to sulfuric acid by introducing oxygen into said slurry to provide an oxygen partial pressure of at least about 25 psia in a gas phase above said slurry; (d) maintaining said pulp in said first oxidation zone to allow at least about 65 percent of the sulfide oxidation to occur in said first oxidation zone to generate an amount of sulfuric acid sufficient to react with the remainder of said inorganic carbonates and said other acid consumers and also form at least about 5 grams of free sulfuric acid per liter in said first zone and wherein the temperature of the slurry in said first oxidation zone is between about 360° F. to about 440°; (e) introducing additional oxygen into the slurry phase of each subsequent oxidation zone while maintaining an oxygen partial pressure of at least about 25 psia in each of said gas phases and while maintaining the temperature of said slurry in each of said subsequent oxidation zones in the range of about 360° F. to about 440°F.; (f) removing a slurry containing a final oxidized slurry, said slurry having an EMF of at least about 500 millivolts; and (g) removing a gas stream from the gas phase of at least said first oxidation zone, cooling the gas stream, separating carbon dioxide from the oxygen in said cooled gas, and recycling said oxygen to said oxidation zones.
Claim 19
Independent Claim
417 words
A method for liberating gold and silver present in refractory carbonate ores, said method comprising: (a) adding sufficient sulfuric acid to a water slurry containing particlized ore to convert a portion of inorganic carbonates in said ore to carbon dioxide and react with other acid consumers in said ore to provide a slurry of pretreated ore having a molar ratio of sulfide to total acid consumers in said pretreated ore of between about 1.2 and about 3.2; (b) heating said slurry of pretreated ore pulp to a temperature of at least about 260° F. to provide a heated pulp slurry; (c) subjecting said heated pulp slurry to a pressure oxidation process in which said slurry is added to a first oxidation zone and is then passed sequentially through at least four subsequent oxidation zones wherein at least 50 volume percent of the total volume of all the slurry contained in all the oxidation zones is contained in the first oxidation zone, wherein each oxidation zone has a gas phase and a slurry phase in which at least a portion of the sulfide in said pulp is oxidized to sulfuric acid by introducing oxygen into said slurry to provide an oxygen partial pressure of at least about 25 psia in a gas phase above said slurry; (d) maintaining said pulp in said first oxidation zone to allow at least about 65 percent of the sulfide oxidation to occur in said first oxidation zone to generate an amount of sulfuric acid sufficient to react with the remainder of said inorganic carbonates and said other acid consumers and also form at least about 5 grams of free sulfuric acid per liter in said first zone and wherein the temperature of the slurry in said first oxidation zone is between about 360° F. to about 440°; (e) introducing additional oxygen into the slurry phase of each subsequent oxidation zone while maintaining an oxygen partial pressure of at least about 25 psia in each of said gas phases and while maintaining the temperature of said slurry in each of said subsequent oxidation zones in the range of about 360° F. to about 440°F.; (f) removing a slurry containing a final oxidized slurry, said slurry having an EMF of at least about 500 millivolts; and (g) removing a gas stream from the gas phase of at least said first oxidation zone, cooling the gas stream, separating carbon dioxide from the oxygen in said cooled gas, and recycling said oxygen to said oxidation zones.
Claim 20
Dependent Claim
21 words
The method of claim 10 wherein said temperature in said oxidation zones is between about 400° F. and about 420° F.
Claim 21
Dependent Claim
24 words
The method of claim 10 wherein ratio of moles of sulfide to moles of total acid consumers is between about 1.4 and about 1.7.
Claim 22
Dependent Claim
21 words
The method of claim 11 wherein at least about 70 percent of the sulfide oxidation occurs in said first oxidation zone.
Claim 23
Dependent Claim
21 words
The method of claim 10 wherein said partial pressure of oxygen in each oxidation zone is at least about 80 psia.
Claim 24
Dependent Claim
22 words
The method of claim 10 wherein the free acid in said final oxidized slurry is at least about 10 grams per liter.
Claim 25
Independent Claim
206 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone; and (c) removing a portion of a gas phase containing oxygen and carbon dioxide from at least one of said oxidation zones and separating substantially all of the carbon dioxide from said oxygen before recycling the oxygen to the oxidation zones.
Claim 26
Independent Claim
206 words
A method for liberating precious metal values from refractory carbonate ores which contain inorganic sulfides and acid consumers, said method comprising: (a) adjusting a molar ratio of sulfide to total acid consumers to within a range of about 1.2 to about 3.2 to provide an adjusted ore feed; (b) contacting an aqueous slurry of said adjusted ore feed with oxygen at a slurry temperature of at least about 360° F. in a first oxidation zone and at least one subsequent oxidation zone, each of said oxidation zones having a slurry phase and a gas phase, to form a final oxidized pulp slurry and convert at least a portion of said sulfide to sulfuric acid wherein at least about 65 percent of said conversion occurs in the first oxidation zone, wherein sulfuric acid is generated in an amount sufficient to react with said acid consumers and also form at least about 5 grams of free sulfuric acid per liter of slurry in said first oxidation zone; and (c) removing a portion of a gas phase containing oxygen and carbon dioxide from at least one of said oxidation zones and separating substantially all of the carbon dioxide from said oxygen before recycling the oxygen to the oxidation zones.
Claim 27
Dependent Claim
23 words
The method of claim 16 wherein said carbon dioxide is separated from said oxygen by contacting said gas phase with hot potassium carbonate.
References Cited (Backward Citations)
US1308639A
Cited
US1461807A
Cited
US2147009A
Cited
US2234140A
Cited
US2315187A
Cited
US2502490A
Cited
US2479930A
Cited
US2545239A
Cited
US2476420A
Cited
US2470707A
Cited
US2478652A
Cited
US2519770A
Cited
US2612470A
Cited
US2579531A
Cited
US2588450A
Cited
US2658827A
Cited
US2726934A
Cited
US2646347A
Cited
US2836490A
Cited
US2989380A
Cited
US2777764A
Cited
US2804379A
Cited
US2893846A
Cited
US3010803A
Cited
US3010804A
Cited
US2827372A
Cited
US2919802A
Cited
US2954290A
Cited
US2867529A
Cited
US3130015A
Cited
US3088820A
Cited
US3018170A
Cited
US3013866A
Cited
US3322505A
Cited
US3266872A
Cited
US3285705A
Cited
US3522018A
Cited
US3215611A
Cited
US3174848A
Cited
US3357823A
Cited
US3293027A
Cited
US3463710A
Cited
US3529026A
Cited
US3477928A
Cited
US3537824A
Cited
US3440256A
Cited
US3523762A
Cited
US3547589A
Cited
US3549351A
Cited
US3574600A
Cited
US3639925A
Cited
US3599601A
Cited
US3615260A
Cited
US3672873A
Cited
US3687635A
Cited
US3846124A
Cited
US3809549A
Cited
SU364574A1
Cited
US3743501A
Cited
US3761566A
Cited
US3909248A
Cited
US3867268A
Cited
SU487971A1
Cited
US4029736A
Cited
US3914162A
Cited
US3879270A
Cited
US3962402A
Cited
US3961908A
Cited
US4052151A
Cited
US3935006A
Cited
GB1491851A
Cited
US4004991A
Cited
US4044096A
Cited
US4097271A
Cited
US4124462A
Cited
US4056261A
Cited
US4085266A
Cited
US4123600A
Cited
US4053305A
Cited
US4038362A
Cited
US4135918A
Cited
US4094668A
Cited
US4219354A
Cited
US4126757A
Cited
US4167470A
Cited
US4188208A
Cited
US4149880A
Cited
SU722971A1
Cited
US4267069A
Cited
US4304644A
Cited
US4372918A
Cited
US4266972A
Cited
US4252924A
Cited
US4249032A
Cited
US4289532A
Cited
US4259107A
Cited
US4298379A
Cited
US4279867A
Cited
US4431613A
Cited
US4279868A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-24 | 1994-06-25 | 1994-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-24 | 1998-06-25 | 1998-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-24 | 2002-06-25 | 2002-12-25 | $7700.00 | Window Closed / Lapsed |