US3351459A - Pelleting iron ore fines - Google Patents

Description

1967 I K. L. MILLS 3,351,459

PELLETING IRGN ORE FINES Filed Aug. 16, 1965 IRoN LIME oRE l6 FINES l4 L9 MIxER AND PELLETIZER RESIDUM TAR,ETc. I2

I8 CRACKED HYDROCAIRBONS 30 28 co & H2

I PA I W I I sTEAM COKE -ORE I \co & N2

sTEAM HOT GASES WATER 24 WATER & PELLETS I r L INVENTOR K L, MILLS ATTORNEYS United States Patent 3,351,459 PELLETING IRON ORE FINES King L. Mills, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Filed Aug. 16, 1965, Ser. No. 479,839 6 Claims. (Cl. 75-3) ABSTRACT OF THE DISCLOSURE Iron ore is admixed with heavy hydrocarbon coke-producing material such as residuum, pitch, or asphaltenes, to which lime may be added, and the resulting mixture in pellet form is coked at a temperature in the range of about 800 to 2000 F. under cracking conditions in a reducing ambient to produce beneficiated iron ore. The hot coked pellets are cooled with water in the bottom of the coking tower and the resulting steam ascends the tower to provide CO and H by reaction with the hydrocarbon material and/ or coke in the pellets.

This invention relates to a process for producing pellets of iron ore fines and coke in which the iron ore is partially reduced or beneficiated.

The conventional method for the production of iron comprises mixing iron ore, limestone, and metallurgical coke and feeding the mixture to the top of a blast furnace. Molten iron and slag are separately recovered from the bottom of the furnace. The metallurgical coke employed is of high strength so as to support the charge without crushing and thus give sufficient porosity to the reaction bed for blasting.

Iron ore deposits exist in proximity to petroleum fields but remote from coal deposits which might provide coke for the manufacture of iron.

This invention is concerned with a method or process for utilizing petroleum residues and heavy coke-forming hydrocarbons in preparing beneficiated iron ore for smeltmg.

Accordingly, it is an object of the invention to provide a process for forming beneficiated iron ore pellets or briquets containing adequate coke produced from heavy hydrocarbon materials in suificient quantity for smelting, with or without the incorporation of lime therein. Another object is to provide a process for making such pellets or briquets which utilizes relatively cheap hydrocarbon materials as the cokeforming agent. A further object is to provide a process for beneficiating an iron ore and simultaneously forming coked pellets or briquets thereof while preventing formation of fines from the pellets or briquets. Other objects of the invention will become apparent to one skilled in the art upon consideration of the accompanying disclosure.

A broad aspect of the invention comprises forming a mixture of heavy hydrocarbon material having coke forming properties and iron ore fines, gravitating the resulting pellets or briquets thru an ascending tream of hot combustion gas including CO and H so as to crack the heavy hydrocarbon to coke and lighter hydrocarbons, gravitating the coked hardened pellets into a mass of liquid so as to cool the pellets without forming fines thereof, and recovering the cooled, hardened, and coked pellets from the liquid. The preferred liquid is water since gravitating the hot coked pellets into Water produces steam which ascends the coking tower and reacts with the hydrocarbon material to form CO and H this in turn reducing a portion of the iron ore in the pellets. The temperature in the coking zone is maintained at cracking and coking temperatures in the range of 800 to 2000 F. and preferably above 1200" F. Pressures in the range of 0 to 50 p.s.i.g. are maintained in the coking zone. Hot combustion gases produced from any suitable source are fed of the coking zone at sufiiciently said range to maintain cracking into the lower section high temperatures in and coking conditions.

A moving stream of liquid, such as water, is passed thru the bottom section of the coking tower so as to cool the pellets or briquets and carry same to suitable recovery means for separating the liquid from the coked pellets. Light hydrocarbon oils may also be used as the liquid in the bottom of the coking tower. In this event, sufficient steam and/or CO and H must be introducd with the combustion gas to provide substantial reduction of the iron ore to beneficiate the same. Lime in flux providing proportions is preferably introduced to the iron ore and heavy hydrocarbon mixture prior to or during the pelleting or briqueting step.

A more complete understanding of the invention may be had by reference to the accompanying drawing which is a flow sheet illustrating a preferred embodiment of the process. A mixer and pelletizer 10 is supplied with heavy hydrocarbon coke-producing material such as residuum, tar, pitch, or asphaltenes, iron ore fines, and lime (when desired) thru line 12, the iron ore fines being introduced to line 12 thru line 14 and the lime being added thru line 16. Vessel 10 may be any type of mixer and pelletizer, this piece of equipment being commercially available. The proportions of the various ingredients of the pellets required for the process are Well known in the art and are set forth in US. Patents 3,072,474 and 3,097,156. It is preferred to form the pellets at least A and up to 2" in size.

The pellets or briquets formed in apparatus 10 are passed via line 18 into a coking tower 20' and there gravitated thru the tower in contact with an ascending stream of hot combustion gases introduced thru line 21 at a temperature sufiicient to maintain cracking and coking conditions such as in the range of 800 to 2000 F. and at a pressure in the range of 0 to 50 p.s.i.g. Sufficient CO and H are present in the coking zone to effect substantial reduction of the iron ore and sinter same to form hard coked pellets.

The coked and sintered pellets are gravitated into the bottom section 22 of tower 20 thru which a stream of liquid is passed from line 24 to line 26, maintaining a mass of water in section 22 for receiving the gravitating pellets or briquets from the coking zone. Any conventional method of maintaining a liquid level in section 22 near the top of this section may be utilized, such as a liquid level controller (not shown). It is also feasible to operate a submerged conveyor in the form of a perforate belt in the bottom of section 22 for removing sintered and partially reduced iron ore pellets.

Efiluent gases and vapors are removed from the upper section of tower 20 via line 28 and are passed thru conventional separation means 30 so as to recover cracked hydrocarbons thru line 32, CO and H thru line 34, and other gases such as steam, N and CO thru line 36.

When utilizing water as the cooling medium in the bottom of tower 20, a substantial amount of steam is formed a the hot coked pellets enter the cooling water and this steam ascends the tower where it reacts with a portion of the coke to form CO and H in accordance with the well known watergas reaction. These gases (CO and H have a reducing effect on the ore in the pellets, causing reduction and sintering thereof to further harden the pellets and beneficiate the iron ore. When utilizing a liquid other than water, such as oil, in section 22 to receive the gravitating pellets, it is advantageous to recycle CO and H from line 34 to line 21. This may also be done even though water is used as the cooling liquid in section 22 of the tower.

To illustrate the invention,

pounds of residuum having a 300 F. ring and ball softening point is admixed a with 200 pounds of iron ore fines (Fe O and pelleted in mixer 10 at 325 F. The pellets are cooled in line 18 to about 100 F. and gravitated thru tower 20 under retarded flow conditions caused by ascending combustion gases introduced thru line 21 at a temperature of about 2000 F. so as to heat the pellets to about 1800 F. About 1800 pounds of sintered partially reduced iron ore (Fe O fall into the mass of water in the bottom of the tower and are recovered in line 26 with subsequent separation from the Water therein. The steam produced by the cooling of the pellets in the quench water rises thru the tower to react with the coke in the pellets, producing CO reducing gas.

Certain modifications of the invention will become apparent to those skilled in the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.

I claim:

1. A process for producing partially reduced iron ore and coke pellets which comprises the steps of:

(1) mixing iron ore fines and heavy coke-forming hydrocarbon in proportions to form pellets;

(2) forming pellets of the mixture of step (1);

(3) gravitating the pellets of step (2) thru a coking zone in an ascending stream of hot combustion gas so as to maintain a temperature in said zone in the range of 800 to 2000 F., thereby cracking said hydrocarbon to form coke and lighter hydrocarbons;

(4) producing hard pellets of coke and iron ore in the coking zone of step (3);

(5) gravitating the pellets of step (4) directly from the coking zone into water to cool'said pellets and form steam;

(6) passing the steam formed in step (5) upwardly thru said coking zone so as to react with a portion of the coke in said pellets to form CO and H said CO and H effecting partial reduction and sintering of iron ore in said pellets; and

(7) recovering the cooled pellets from step (6).

2. The process of claim 1 wherein the heavy hydrocarbon is selected from the group consisting of residuum, tar, pitch, asphaltenes, and mixtures thereof.

3. The process of claim 1 including the step of incor- 4 porating lime in the pellets in step (1) and (2) in fiuxing proportions.

4. The process of claim 1 including the steps of:

(8) recovering a gaseous stream from the upper section of the coking zone;

(9) separating hydrocarbons from the stream of step (8) as a product of the process; and

(10) recycling at least a portion of the remaining gases from step (9), including CO and H to the coking zone.

5. A process for producing partially reduced iron ore and coke pellets which comprises the steps of:

(1) mixing iron ore fines and heavy coke-forming hydrocarbon in proportions to form pellets;

(2) forming pellets of the mixture of step (1);

(3) gravitating the pellets of step (2) thru a coking zone in an ascending stream of hot combustion gas, including CO, H and steam, at a cracking and coking temperature in the range of 800 to 2000 F. so as to produce lighter hydrocarbons and hard pellets containing coke and partially reduced iron ore;

(4) gravitating the pellets from the coking zone of step (3) into a mass of Water to cool said pellets and form steam while avoiding formation of fines;

(5) passing the steam formed in step (4) upwardly thru said coking zone to react a portion thereof with said coke to provide CO, H and steam for step (3); and

(6) recovering cooled pellets from step (4).

6. The process of claim 5 including the steps of:

(7) recovering the lighter hydrocarbons of step (3);

(8) recovering CO and H formed in step (3); and

(9) recycling the CO and H from step (7) to step (3).

References Cited UNITED STATES PATENTS 1,116,024 11/1914 Crusius -3 1,848,710 3/1932 Gustafsson 75-3 2,204,576 6/1940 Davis 751 2,808,325 10/1957 Subervie 753 3,264,092 8/1966 Ban 75--3 BENJAMIN HENKIN, Primary Examiner.

Claims (1)

1. A PROCESS FOR PRODUCING PARTIALLY REDUCED IRON ORE AND COKE PELLETS WHICH COMPRISES THE STEPS OF: (1) MIXING IRON ORE FINES AND HEAVY COKE-FORMING HY DROCARBON IN PROPORTIONS TO FORM PELLETS; (2) FORMING PELLETS OF THE MIXTURE OF STEP (1); (3) GRAVITATING THE PELLETS OF STEP (2) THRU A COKING ZONE IN AN ASCENDING STREAM OF HOT COMBUSTION GAS SO AS TO MAINTAIN A TEMPERATURE IN SAID ZONE IN THE RANGE OF 800 TO 2000*F., THEREBY CRACKING SAID HYDROCARBON TO FORM COKE AND LIGHTER HYDROCARBONS; (4) PRODUCING HARD PELLETS OF COKE AND IRON ORE IN THE COKING ZONE OF STEP (3); (5) GRAVITATING THE PELLETS OF STEP (4) DIRECTLY FROM THE COKING ZONE INTO WATER TO COOL SAID PELLETS AND FORM STEAM; (6) PASSING THE STEAM FORMED IN STEP (5) UPWARDLY THRU SAID COKING ZONE SO AS TO REACT WITH A PORTION OF THE COKE IN SAID PELLETS TO FORM CO AND H2, SAID

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