US3865574A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of low-sulfur prereduced iron pellets
Assignee: Lummus Technology LLC
•
Filing: 1972-07-20
•
Granted: 1975-02-11
•
Expires: 1992-07-20
Abstract
Abstract The present invention discloses a process for producing iron oxide pellets of low residual sulfur. In the pelletizing of finely divided ore with carbonaceous materials as binder, varying amounts of sulfur are introduced. Green pellets are heated under conditions leading to coking of the binder and recovery of the cracked vapors. The coked pellets are then further heated to achieve the desired degree of reduction and to diminish the residual sulfur content. A sulfur scavenger is initially sprayed on the ore. For pellets that will be reduced 85 percent or less, all necessary reductant is incorporated in the pellet, in the form of the coked binder and, optionally, added carbon. Heating to the reduction and calcining temperature is rapid. For highly reduced pellets (+85 percent), the same procedure may be followed, but heating to reduction and calcining temperature must be slow for good desulfurization. A preferred alternative for highly prereduced pellets involves reduction in two stages: initially a 25-50 percent reduction is carried out with rapid heating and with all reductant in the pellet. Then, the pellets are further reduced with a stoichiometric excess of reductant external to the pellet, with fast heating to reduction temperature. Because of the inherently porous nature of pellets produced with liquid carbonaceous binders, reduction is significantly faster and more complete than with conventional pellets.
Inventors
- 👤 Raymond H Long
- 👤 William V Bauer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:20
CPC Classifications
C; C21; C21B; C21B13/00; C21B13/0046; C22; C22B; C22B1/00; C22B1/14; C22B1/24; C22B1/2406; Y; Y02; Y02P; Y02P10/00; Y02P10/10; Y02P10/134; Y02P10/20
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
146 words
A PROCESS FOR PRODUCING PRE-REDUCED IRON OXIDE PELLETS OF LOW-SULFUR CONTENT FROM ORE AND A SULFUR-BEARING FLUID CARBONACEOUS MATERIAL COMPRISING: PELLETIZING SAID ORE AND A MINOR PROPORTION OF A SULFURSCAVENGING COMPOUND BY SPRAYING SAID CARBONACEOUS MATERIAL THEREON WHILE AGITATING SAME, SAID CARBONACEOUS MATERIAL BEING HEATED TO A FLOWABLE TEMPERATURE AND MAINTAINING THE TEMPERATURE IN THE PELLETIZING MIXTURE BELOW THE CRACKING TEMPERATURE AND SAID CARBONACEOUS MATERIAL; COKING THE PELLETS THUS FORMED, THE COKED PELLETS CONTAINING SUFFICIENT CARBON TO EFFECT ABOUT 25 TO 70 PERCENT REDUCTION OF SAID ORE; HEATING THE COKED PELLETS TO RAISE THE TEMPERATURE OF THE PELLETS TO A FINAL REDUCTION TEMPERATURE IN THE RANGE OF 1,9000* TO 2,100*F, DURING SAID HEATING THE TEMPERATURE OF THE PELLETS BEING RAISED FROM 1,500*F TO SAID FINAL TEMPERATURE IN LESS THAN ABOUT 1 HOUR; AND RETAINING SAID PELLETS AT SAID FINAL TEMPERATURE FOR FROM / TO 2 HOURS.
Claim 2
Dependent Claim
146 words
A PROCESS FOR PRODUCING PRE-REDUCED IRON OXIDE PELLETS OF LOW-SULFUR CONTENT FROM ORE AND A SULFUR-BEARING FLUID CARBONACEOUS MATERIAL COMPRISING: PELLETIZING SAID ORE AND A MINOR PROPORTION OF A SULFURSCAVENGING COMPOUND BY SPRAYING SAID CARBONACEOUS MATERIAL THEREON WHILE AGITATING SAME, SAID CARBONACEOUS MATERIAL BEING HEATED TO A FLOWABLE TEMPERATURE AND MAINTAINING THE TEMPERATURE IN THE PELLETIZING MIXTURE BELOW THE CRACKING TEMPERATURE AND SAID CARBONACEOUS MATERIAL; COKING THE PELLETS THUS FORMED, THE COKED PELLETS CONTAINING SUFFICIENT CARBON TO EFFECT ABOUT 25 TO 70 PERCENT REDUCTION OF SAID ORE; HEATING THE COKED PELLETS TO RAISE THE TEMPERATURE OF THE PELLETS TO A FINAL REDUCTION TEMPERATURE IN THE RANGE OF 1,9000* TO 2,100*F, DURING SAID HEATING THE TEMPERATURE OF THE PELLETS BEING RAISED FROM 1,500*F TO SAID FINAL TEMPERATURE IN LESS THAN ABOUT 1 HOUR; AND RETAINING SAID PELLETS AT SAID FINAL TEMPERATURE FOR FROM / TO 2 HOURS.
Claim 3
Dependent Claim
25 words
The process as claimed in claim 1, wherein said fluid carbonaceous material is selected from the group consisting of residual oils and coal tar pitch.
Claim 4
Dependent Claim
165 words
A process for producing prereduced iron oxide pellets of low-sulfur content from ore and a sulfur-bearing fluid carbonaceous material comprising: forming a mixture of finely divided ore, a minor proportion of a sulfur-scavenging compound and a predetermined amount of finely divided carbon under non-agglomerating conditions; pelletizing said mixture by spraying said carbonaceous material thereon while agitating same, said carbonaceous material beig heated to a flowable temperature and maintaining the temperature in the pelletizing mixture below the cracking temperature of said carbonaceous material; coking the pellets thus formed, the coked pellets containing sufficient carbon to effect about 25 to 85 percent reduction of said ore; heated the coked pellets to raise the temperature of the pellets to a final reduction temperature in the range of 1,900* to 2, 100*F, during said heating the temperature of the pellets being raised from 1,500*F to said final temperature in less than about 1 hour; and retaining said pellets at said final temperature for from 1 1/2 to 2 hours.
Claim 5
Dependent Claim
165 words
A process for producing prereduced iron oxide pellets of low-sulfur content from ore and a sulfur-bearing fluid carbonaceous material comprising: forming a mixture of finely divided ore, a minor proportion of a sulfur-scavenging compound and a predetermined amount of finely divided carbon under non-agglomerating conditions; pelletizing said mixture by spraying said carbonaceous material thereon while agitating same, said carbonaceous material beig heated to a flowable temperature and maintaining the temperature in the pelletizing mixture below the cracking temperature of said carbonaceous material; coking the pellets thus formed, the coked pellets containing sufficient carbon to effect about 25 to 85 percent reduction of said ore; heated the coked pellets to raise the temperature of the pellets to a final reduction temperature in the range of 1,900* to 2, 100*F, during said heating the temperature of the pellets being raised from 1,500*F to said final temperature in less than about 1 hour; and retaining said pellets at said final temperature for from 1 1/2 to 2 hours.
Claim 6
Dependent Claim
16 words
The process as claimed in claim 3, wherein said fluid carbonaceous material is a residual oil.
Claim 7
Dependent Claim
166 words
A process for producing highly prereduced iron oxide pellets of low-sulfur content from ore and a sulfur-bearing fluid carbonaceous material comprising: forming a mixture of finely ore, a minor proportion of a sulfur-scavenging compound and a predetermined amount of finely divided carbon under non-agglomerating conditions; pelletizing said ore mixture by spraying said carbonaceous material thereon while agitating same, said carbonaceous material being heated to a flowable temperature and maintaining the temperature in the pelletizing mixture below the cracking temperature of said carbonaceous material; coking the pellets thus formed, the coked pellets containing sufficient carbon to effect about 85 to 100 percent reduction of said ore; heating the coked pellets to raise the temperature of the pellets to a final reduction temperture in the range of 1,900* to 2,100*F, during said heating the temperature of the pellets being raised from 1,500*F to said final temperature in from about 1 1/2 to 3 hours; and retaining said pellets at said final temperature for from 3/4 to 2 hours.
Claim 8
Dependent Claim
166 words
A process for producing highly prereduced iron oxide pellets of low-sulfur content from ore and a sulfur-bearing fluid carbonaceous material comprising: forming a mixture of finely ore, a minor proportion of a sulfur-scavenging compound and a predetermined amount of finely divided carbon under non-agglomerating conditions; pelletizing said ore mixture by spraying said carbonaceous material thereon while agitating same, said carbonaceous material being heated to a flowable temperature and maintaining the temperature in the pelletizing mixture below the cracking temperature of said carbonaceous material; coking the pellets thus formed, the coked pellets containing sufficient carbon to effect about 85 to 100 percent reduction of said ore; heating the coked pellets to raise the temperature of the pellets to a final reduction temperture in the range of 1,900* to 2,100*F, during said heating the temperature of the pellets being raised from 1,500*F to said final temperature in from about 1 1/2 to 3 hours; and retaining said pellets at said final temperature for from 3/4 to 2 hours.
Claim 9
Dependent Claim
16 words
The process as claimed in claim 5, wherein said fluid carbonaceous material is a residual oil.
Claim 10
Dependent Claim
192 words
A process for producing highly procedured iron oxide pellets of low-sulfur content from ore and a sulfur-bearing fluid carbonaceous material comprising: pelletizing said ore and a minor proportion of a sulfur-scavenging compound by spraying said carbonaceous material thereon while agitating same, said carbonaceous material being heated to a flowable temperature and mantaining the temperature in the pelletizing mixture below the cracking temperature of said carbonaceous material; coking the pellets thus formed, the coked pellets containing sufficient carbon to effect about 25 to 70 percent reduction of said ore; heating the coked pellets to raise the temperature of the pellets to a final reduction temperature in the range of 1, 900* to 2,100*F, during said heating the temperature of the pellets being raised from 1,500*F to said final temperature in less than about 1 hour; retaining said pellets at said final temperature for from 1/2 to 2 hours; and mixing said partially reduced pellets with a stoichiometric excess of carbon containing a minor proportion of a sulfur-scavenging compound and maintaining the pellet-carbon mixture at said final reduction temperature for a period sufficient to effect in excess of 90 percent reduction of said ore.
Claim 11
Dependent Claim
192 words
A process for producing highly procedured iron oxide pellets of low-sulfur content from ore and a sulfur-bearing fluid carbonaceous material comprising: pelletizing said ore and a minor proportion of a sulfur-scavenging compound by spraying said carbonaceous material thereon while agitating same, said carbonaceous material being heated to a flowable temperature and mantaining the temperature in the pelletizing mixture below the cracking temperature of said carbonaceous material; coking the pellets thus formed, the coked pellets containing sufficient carbon to effect about 25 to 70 percent reduction of said ore; heating the coked pellets to raise the temperature of the pellets to a final reduction temperature in the range of 1, 900* to 2,100*F, during said heating the temperature of the pellets being raised from 1,500*F to said final temperature in less than about 1 hour; retaining said pellets at said final temperature for from 1/2 to 2 hours; and mixing said partially reduced pellets with a stoichiometric excess of carbon containing a minor proportion of a sulfur-scavenging compound and maintaining the pellet-carbon mixture at said final reduction temperature for a period sufficient to effect in excess of 90 percent reduction of said ore.
Claim 12
Dependent Claim
16 words
The process as claimed in claim 7, wherein said fluid carbonaceous material is a residual oil.
Claim 13
Dependent Claim
160 words
A process for producing prereduced iron oxide pellets of low-sulfur content from iron oxide pellets containing integral carbon comprising: pelletizing iron oxide with a sulfur-bearing carbonaceous fluid as binder to produce iron oxide pellets; subjecting the iron oxide pellets to coking conditions to coke said binder and produce integral carbon, said binder providing at least a portion of the integral carbon in said pellets, the coked pellets containing sufficient integral carbon to effect from about 25 to about 85 percent prereduction of the iron oxide pellets; heating the iron oxide pellets containing integral carbon to raise the temperature of the iron oxide pellets to a final prereduction temperature of from about 1,800* F, during said heating the temperature of the pellets being raised from a temperature of about 1,500*F to the final reduction temperature in a time of less than about 1 hour; and maintaining the iron oxide pellets at the final reduction temperature to produce prereduced iron oxide pellets.
Claim 14
Dependent Claim
160 words
A process for producing prereduced iron oxide pellets of low-sulfur content from iron oxide pellets containing integral carbon comprising: pelletizing iron oxide with a sulfur-bearing carbonaceous fluid as binder to produce iron oxide pellets; subjecting the iron oxide pellets to coking conditions to coke said binder and produce integral carbon, said binder providing at least a portion of the integral carbon in said pellets, the coked pellets containing sufficient integral carbon to effect from about 25 to about 85 percent prereduction of the iron oxide pellets; heating the iron oxide pellets containing integral carbon to raise the temperature of the iron oxide pellets to a final prereduction temperature of from about 1,800* F, during said heating the temperature of the pellets being raised from a temperature of about 1,500*F to the final reduction temperature in a time of less than about 1 hour; and maintaining the iron oxide pellets at the final reduction temperature to produce prereduced iron oxide pellets.
Claim 15
Dependent Claim
26 words
The process of claim 9 wherein the iron oxide pellets heated to the final reduction temperature integrally include a minor proportion of a sulfur scavenging compound.
Claim 16
Dependent Claim
44 words
The process of claim 10 wherein the sulfur scavenging compound is at least one member selected from the group consisting of calcium chloride, magnesium chloride, ferric chloride, a mixture of sodium chloride and calcium carbonate and a mixture of sodium chloride and calcium oxide.
Claim 17
Dependent Claim
41 words
The process of claim 9 wherein the final reduction temperature is from 1,900* to 2,100*F, and the temperature of the pellets is raised from a temperature of about 1,500*F to the final reduction period in a time less than 3/4 hour.
Claim 18
Dependent Claim
39 words
The process of claim 12 wherein the coked binder provides a portion of the integral carbon, the remainder of the integral carbon being provided by the addition of finely divided carbon to said iron oxide prior to the pelletizing.
Claim 19
Dependent Claim
51 words
The process of claim 13 wherein the finely divided carbon is added to the iron oxide by spraying fluid carbonaceous material onto a preheated, agitated bed of finely divided iron oxide, said iron oxide being at a temperature sufficient to crack the fluid carbonaceous material to produce a finely divided carbon.
Claim 20
Dependent Claim
44 words
The process of claim 9 wherein said iron oxide pellets are reduced at the final reduction temperature in the presence of external carbon in a stoichiometric excess of the amount required to achieve the prereduction and a minor portion of a sulfur scavenging material.
Claim 21
Dependent Claim
21 words
The process of claim 15 wherein the external carbon is selected from the group consisting of coal, coke and mixtures thereof.
Claim 22
Dependent Claim
20 words
The process of claim 16 wherein the sulfur scavenging compound is selected from the group consisting of limestone and dolomite.
Claim 23
Dependent Claim
43 words
The process of claim 17 wherein the final reduction temperature is from about 1,900* to about 2,100*F, the temperature of the pellets being raised from a temperature of 1, 500*F to the final reduction temperature in a time of less than 3/4 hour.
Claim 24
Dependent Claim
26 words
The process of claim 15 wherein the iron oxide pellets heated to the final reduction temperature integrally include a minor proportion of a sulfur scavenging compound.
Claim 25
Dependent Claim
39 words
The process of claim 15 wherein the coked binder provides a portion of the integral carbon, the remainder of thE integral carbon being provided by the addition of finely divided carbon to said iron oxide prior to the pelletizing.
Claim 26
Dependent Claim
51 words
The process of claim 20 wherein the finely divided carbon is added to the iron oxide by spraying fluid carbonaceous material onto a preheated, agitated bed of finely divided iron oxide, said iron oxide being at a temperature sufficient to crack the fluid carbonaceous material to produce a finely divided carbon.
Claim 27
Dependent Claim
27 words
The process of claim 9 wherein the sulfur bearing carbonaceous fluid employed as binder is selected from the group consisting of residual oils and coal tar pitch.
Claim 28
Dependent Claim
39 words
The process of claim 9 wherein the final reduction temperature is from 1,900* to 2,100*F, the temperature of the pellets being raised from a temperature of 1,500*F to the final reduction temperature in a time less than 3/4 hour.
Claim 29
Dependent Claim
23 words
The process of claim 23 wherein the iron oxide pellets are held at the final reduction temperature for from 1/4 to 6 hours.
Claim 30
Dependent Claim
153 words
A process for producing prereduced iron oxide pellets of low-sulfur content from iron oxide pellets containing integral carbon, comprising: pelletizing iron oxide with a sulfur-bearing carbonaceous fluid as binder to produce iron oxide pellets; subjecting the iron oxide pellets to coking conditions to coke said binder and produce integral carbon, said binder providing at least a portion of the integral carbon in said pellets, the coked pellets containing sufficient carbon to effect a greater than 85 percent prereduction; heating the iron oxide pellets containing integral carbon to raise the temperature of the iron oxide pellets to a final reduction temperature of from about 1,800* to about 2,500*F, during said heating the temperature of the pellets being raised from a temperature of 1,500*F to the final reduction temperature in a time of from 1 to 6 hours; and maintaining the iron oxide pellets at the final reduction temperature to produce prereduced iron oxide pellets.
Claim 31
Dependent Claim
153 words
A process for producing prereduced iron oxide pellets of low-sulfur content from iron oxide pellets containing integral carbon, comprising: pelletizing iron oxide with a sulfur-bearing carbonaceous fluid as binder to produce iron oxide pellets; subjecting the iron oxide pellets to coking conditions to coke said binder and produce integral carbon, said binder providing at least a portion of the integral carbon in said pellets, the coked pellets containing sufficient carbon to effect a greater than 85 percent prereduction; heating the iron oxide pellets containing integral carbon to raise the temperature of the iron oxide pellets to a final reduction temperature of from about 1,800* to about 2,500*F, during said heating the temperature of the pellets being raised from a temperature of 1,500*F to the final reduction temperature in a time of from 1 to 6 hours; and maintaining the iron oxide pellets at the final reduction temperature to produce prereduced iron oxide pellets.
Claim 32
Dependent Claim
26 words
The process of claim 25 wherein the iron oxide pellets heated to the final reduction temperature integrally include a minor proportion of a sulfur scavenging compound.
Claim 33
Dependent Claim
44 words
The process of claim 26 wherein the sulfur scavenging compound is at least one member selected from the group consisting of calcium chloride, magnesium chloride, ferric chloride, a mixture of sodium chloride and calcium carbonate and a mixture of sodium chloride and calcium oxide.
Claim 34
Dependent Claim
27 words
The process of claim 27 wherein the sulfur bearing carbonaceous fluid employed as binder is selected from the group consisting of residual oils and coal tar pitch.
Claim 35
Dependent Claim
42 words
The process of claim 27 wherein the final reduction temperature is from 1,900* to 2,100*F and the temperature of the pellets is raised from a temperature of 1,500*to the final reduction temperature in a time from one and 1/2 to 3 hours.
Claim 36
Dependent Claim
44 words
The process of claim 25 wherein said iron oxide pellets are reduced at the final reduction temperature in the presence of external carbon in a stoichiometric excess of the amount required to achieve the prereduction and a minor portion of a sulfur scavenging material.
Claim 37
Dependent Claim
39 words
The process of claim 25 wherein the coked binder provides a portion of the integral carbon, the remainder of the integral carbon being provided by the addition of finely divided carbon to said iron oxide prior to the pelletizing.
Claim 38
Dependent Claim
51 words
The process of claim 31 wherein the finely divided carbon is added to the iron oxide by spraying fluid carbonaceous material onto a preheated, agitated bed of finely divided iron oxide, said iron oxide being at a temperature sufficient to crack the fluid carbonaceous material to produce a finely divided carbon.
Claim 39
Dependent Claim
150 words
A process for producing 70-85 percent prereduced iron oxide pellets of low-sulfur content from ore and a coal tar pitch, comprising: pelletizing said ore and a mInor proportion of a sulfur-scavenging compound by spraying said pitch thereon while agitating same, said pitch being heated to a flowable temperature and maintaining the temperature of the pelletizing mixture below the cracking temperature of said pitch; coking the pellets thus formed, the coke pellets containing sufficient integral carbon to effect 70-85 percent reduction; heating the iron oxide pellets containing integral carbon to raise the temperature of the pellets to a final reduction temperature of from 1,900* to 2,100*F, during said heating the temperature of the pellets being raised from a temperature of 1,500*F to the final reduction temperature in a time of less than 1 hour; and holding the iron oxide pellets at the final reduction temperature to produce prereduced iron oxide pellets.
Claim 40
Dependent Claim
150 words
A process for producing 70-85 percent prereduced iron oxide pellets of low-sulfur content from ore and a coal tar pitch, comprising: pelletizing said ore and a mInor proportion of a sulfur-scavenging compound by spraying said pitch thereon while agitating same, said pitch being heated to a flowable temperature and maintaining the temperature of the pelletizing mixture below the cracking temperature of said pitch; coking the pellets thus formed, the coke pellets containing sufficient integral carbon to effect 70-85 percent reduction; heating the iron oxide pellets containing integral carbon to raise the temperature of the pellets to a final reduction temperature of from 1,900* to 2,100*F, during said heating the temperature of the pellets being raised from a temperature of 1,500*F to the final reduction temperature in a time of less than 1 hour; and holding the iron oxide pellets at the final reduction temperature to produce prereduced iron oxide pellets.
Claim 41
Dependent Claim
158 words
A process for producing prereduced iron oxide pellets of greater than 85 percent prereduction and low-sulfur content from ore and a coal tar pitch, comprising: pelletizizng said ore and a minor proportion of a sulfur-scavenging compound by spraying said pitch thereon or agitating same, said pitch being heated to a flowable temperature and maintaining the temperature of the pelletizing mixture below the cracking temperature of said pitch; coking the pellets thus formed, the coked pellets containing sufficient integral carbon to effect a greater than 85 percent prereduction; heating the iron oxide pellets containing integral carbon to raise the temperature of the pellets to a final reduction temperature of from 1,900* to 2,100*F, during said heating the temperature of the pellets being raised from a temperature of 1,500*F to the final reduction temperature in a time of from 1 to 6 hours; and holding the iron oxide pellets at the final reduction temperature to produce prereduced iron oxide pellets.
Claim 42
Dependent Claim
158 words
A process for producing prereduced iron oxide pellets of greater than 85 percent prereduction and low-sulfur content from ore and a coal tar pitch, comprising: pelletizizng said ore and a minor proportion of a sulfur-scavenging compound by spraying said pitch thereon or agitating same, said pitch being heated to a flowable temperature and maintaining the temperature of the pelletizing mixture below the cracking temperature of said pitch; coking the pellets thus formed, the coked pellets containing sufficient integral carbon to effect a greater than 85 percent prereduction; heating the iron oxide pellets containing integral carbon to raise the temperature of the pellets to a final reduction temperature of from 1,900* to 2,100*F, during said heating the temperature of the pellets being raised from a temperature of 1,500*F to the final reduction temperature in a time of from 1 to 6 hours; and holding the iron oxide pellets at the final reduction temperature to produce prereduced iron oxide pellets.
References Cited (Backward Citations)
US2805141A
Cited
US2811434A
Cited
US2944884A
Cited
US3093474A
Cited
US3218152A
Cited
US3219436A
Cited
US3314780A
Cited
US3420656A
Cited
US3427148A
Cited
US3495971A
Cited
US3642465A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |