US3856509A

US3856509A - Process for the reduction of iron ores or the like in the production of pig iron in the blast furnace

Info

Publication number: US3856509A
Application number: US00248137A
Authority: US
Inventors: G Heynert; K Peters
Original assignee: August Thyssen Huette AG
Current assignee: Thyssen AG
Priority date: 1971-04-30
Filing date: 1972-04-27
Publication date: 1974-12-24
Anticipated expiration: 1991-12-24
Also published as: ZA722447B; SE376015B; DE2121241A1; AT315881B; DE2121241B2; LU65273A1; BR7202539D0; DE2121241C3; ES401684A1; NL147481B; NL7200315A

Abstract

An improvement in a process for the reduction of an iron ore, sinter or other such starting materials in a blast furnace in which as the reducing agent there is employed a water in oil emulsion, the water content being between 3 and 15% by volume. The water in oil emulsion is introduced into the tuyeres of the blast furnace through tubular lances terminating therein, the tubular lances having an aperture between 4 and 6 mm in diameter.

Description

United States Patent Heynert et al.

[ Dec. 24, 1974 PROCESS FOR THE REDUCTION OF IRON ORES OR THE LIKE IN THE PRODUCTION OF PIG IRON IN THE BLAST FURNACE Inventors: Gerhard Heynert, Mulheim;

Karl-Heinz Peters, Duisburg-Hamborn, both of Germany August Thyssen-I-Iutte Aktiengesellschaft, Duisburg-Hamborn, Germany Filed: Apr. 27, 1972 Appl. N0.: 248,137

Assignee:

[30] Foreign Application Priority Data Apr. 30, 1971 Germany 2121241 US. Cl. 75/42 Int. Cl C21b 5/00 Field of Search 75/41, 42; 44/51 [56] References Cited] UNITED STATES PATENTS 2,152,196 3/1939 Kokatnur 44/51 2,175,517 10/1939 Ditto 75/41 Primary Examiner-L. Dewayne Rutledge Assistant Examiner-M. J. Andrews Attorney, Agent, or Firm-Burgess, Dinklage & Sprung [57] ABSTRACT An improvement in a process for the reduction of an iron ore, sinter or other such starting materials in a blast furnace in which as the reducing agent there is employed a water in oil emulsion, the water content being between 3 and 15% by volume. The water in oil emulsion is introduced into the tuyeres of the blast furnace through tubular lances terminating therein, the tubular lances having an aperture between 4 and 6 mm in diameter.

14 Claims, l Drawing Figure PROCESS FOR THE REDUCTION OF IRON ORES OR THE LIKE IN THE PRODUCTION OF PIG IRON IN THE BLAST FURNACE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a process for the reduction of iron ores, sinters or other such starting materials in the blast furnace, in which coke and oil are used as reducing agents.

2. Discussion of the Prior Art In the classical processes of pig iron production in the blast furnace, the reduction of the iron oxides is per formed by means of high-quality carbonaceous reducing agents such as coke or wood charcoal. Years of efforts to achieve an increase of efficiency combined with a reduction of the cost of pig iron production in the blast furnace have led to the replacement of some of the expensive and bulky metallurgical coke with oil or gas,.such as natural gas.

The prior art has suggested replacing the more expensive coke in the blast furnace in part with oil. This proposal resulted in use of 60 to 80 kg of oil per ton of pig iron, depending on operating conditions. Any further increase in the proportion of oil is blocked by the fact that as the amount of oil increases the size of the oil drops increases and thus there is not enough time for the gasification of the oil in the reaction chamber (area between the lance orifice and the coke face). The result is that the ungasified oil drops, upon encountering the hot coke, form carbon black whichcan create trouble in operation.

The formation of carbon black can be restrained by the use of commercial burner designs, such as pressurespray burners, steam-spray burners or compressed-air spray burners, which under certain circumstances permit a sufficiently fine atomization of the oil. Experiments with these types of burners, however, have shown that the installation of these systems entails appreciable expense. Furthermore, difficulties arise in their operation, and the systems are not entirely reliable.

It has been proposed to use emulsions of water in oil from combustion. Such emulsions contain at least 25 percent by volume water and up to 70 percent by volume to provide for the desired atomization of the oil. Such emulsions, however, are undesirable because the droplet size is still not as small as desired. Specifically, the droplet size of the oil in water emulsion is about 50 microns in diameter whereas a smaller size, say, 30 microns or less in diameter is desired. Additionally, because of the large proportion of water in the emulsion more reducing agent was required to provide the desired oil level in the blast furnace. Furthermore, use of large amounts of water in the water-in-oil emulsion provides an undesirably high heat loss factor.

Pursuant to the present invention, such difficulties are prevented. Thus, it is an object of the invention to provide a considerable diminution of the proportion of expensive an bulky coke used in iron ore reduction. It is another object of the invention to prevent the undesirable formation of carbon black, and to permit the injection of large amounts of oil by means of the simple tubular lances whose practicality has long been established.

SUMMARY OF THE INVENTION Broadly, this invention contemplates an improvement in a process for the reduction of iron ore, sinters or other such starting materials wherein at least a portion of the reducing agent is an oil, the improvement which comprises utilizing as such oil a water-in-oil emulsion having a water content between 3 and 15 percent by volume.

This invention contemplates, in a desirable embodiment, utilization of a water-in-oil emulsion having a water content between 3 and 15 percent by volume, preferably between 3 and 10 percent by volume. The said waterin-oil emulsion is introduced through tubular lances terminating in the tuyeres of the blast furnace, said tubular lances having an aperture between 4 and 6 mm in diameter. In such particularly desirable embodiment the quantity of oil employed is between and 200 kilograms of oil per metric ton of pig iron, preferably between and kilograms of oil per metric ton of pig iron.

In accordance with another highly desirable embodiment of the invention the reduction of the iron ore, sinter or other starting material in the blast furnace is accomplished by passing the water-in-oil emulsion through the aforesaid tubular lances terminating in the tuyeres of the blast furnace and conducting the reduction in said blast furnace at a blast velocity of between 100 and 300 m/sec. at a blast temperature of between I,OO0 and I,400C.

DISCUSSION OF PREFERRED EMBODIMENTS The objects of the invention outlined above are achieved through use of an oil, distillate or residuum, especially heavy oil, residual oil or fuel oil, in the form of waterin-oil emulsion having a very low water content. The water content of the water-in-oil emulsion is at least 3 percent by volume. In no case, however, must the water content exceed 15 percent by volume. This emulsion is injected, in accordance with the invention, through tubular lances which terminate in the tuyeres of the blast furnace. Water contents of between 3 and 10 percent by volume are preferred. When such small portions of water are used, micro explosions are obtained which are caused by the vaporization of tiny water droplets enveloped by the oil phase, resulting in an extremely fine vaporization of the oil. Accordingly, it is surprising that, in the process of the invention, water-in-oil emulsions having a very low water content, amounting to only a few percent of water, can be so finely atomized in the blast furnace that oil particles ranging from virtually 0 to 30 microns are formed. This oil particle size is achieved when the water-in-oil emulsion is introduced into the tuyeres of the blast furnace at a blast velocity of 100 to 300 m/sec and a blast temperature of 800 to l,400C, preferably l,O00 to 1,400C.

Through use of such water-in-oil emulsions a large portion of the expensive coke otherwise needed for the reduction in the blast furnace can be replaced by emulsion such that at least 90 kg of oil is injected into the blast furnace for each ton of pig iron.

In particular, the process of the present invention can be performed by injecting oil in quantities of 90 to 200 kg of oil per metric ton of pig iron, 100 to 160 kg of oil per ton of pig iron being perferred. In this manner considerable amounts of coke can be saved, the saving amounting to as much as 30 percent. Furthermore, by using tubular lances terminating in the tuyeres of the blast furnace, the oil feed is made mechanically very simple, avoiding the difficulties involved in complex atomizers. The aperture of the lances is optimumly between 4 and 6 mm. in diameter.

Normally, the reducing agent of the invention can be injected into the tuyere at a pressure that is l to 2 atmospheres higher than the pressure of the hot blast. It is advantageous, however, to increase this pressure to 10 to 60 atmospheres, for example. Special advantages are achieved when the additional pressure amounts to 40 to 50 atmospheres. The proportion of extremely fine oil droplets is greatly increased by the use of elevated pressure.

The water-in-oil emulsions can be prepared in a conventional manner by homogenizers, e.g., colloid mills.

It is especially advantageous to use a high-pressure homogenizer but to prevent heat losses in the blast furnace only as much water is added in accordance with the invention as is needed barely to assure sufficient atomization of the oil in the reaction chamber.

It may be desirable, under certain circumstances, as for example in cases in which the emulsions are to be stocked to add emulsifiers to them. Examples of suitable emulsifiers are alcali salts of fatty acids.

In order to more fully illustrate the nature of the invention in the manner of practicing the same, the following Example is presented.

EXAMPLE A heavy oil was made into a water-in-oil emulsion in a high-pressure homogenizer using water in a volume ratio of 5: 95. 150 kg of oil per metric ton of'pig iron, in the form of the emulsion, was injected through lances having an aperture of 5 mm diameter into the tuyeres of a blast furnace having a hearth diameter of 9.5 m, at a pressure of 12 atmospheres.

The blast furnace was operated with a burden consisting of 70 wt-percent sinter and 30 wt-percent lump ore plus fluxes. The blast velocity amounted to 200 m/s and the blast temperature was l,l00C. No carbon black formation or any other trouble was encountered. The coke charge amounted to 370 kg per ton of pig iron. Previously the same furnace with the same burden required a coke charge of 450 kg and 60 to 80 kg of heavy heating oil per ton of pig iron.

These figures show that more than twice the amount of oil and about 15 percent less coke can be used, while the smelting of the iron ore takes place much more uniformly and under better control. This contributes, also, to longer furnace'life. Furthermore, less coke slag is produced and a qualitatively better blast-furnace gas is obtained.

By the process of theinvention, therefore, in contrast to the prior art procedures, it is possible to inject more than twice the amount of oil into the blast furnace without causing the undesirable formation of carbon black. The lower proportion of coke made possible by the use of oil makes it possible to charge the furnace with correspondingly more ore, so that the production of pig iron can be considerably increased. Furthermore, the lower proportion of coke results in correspondingly less slag, and the gas has a higher heat value.

The drawing shows in a horizontal section a tuyere l of a blast furnace having a centrally arranged tuyere pipe 2. From the left side a tubular lance 3 is introduced under an acute angle 4 to the middle axis 5 of the tuyere pipe 2.

Through tuyere pipe 2 blast gas is blown into the blast-furnace indicated by numeral 6 and through tubular lance 3 water-in-oil emulsion is introduced into the interior of the tuyere pipe 2.

The terms and expressions used herein have been used as terms of description and not of limitation as there is no intention, in the use of such terms and descriptions, of excluding any equivalents, or portions thereof, as many modifications and departures will become obvious to one skilled in the art. For instance, the method in which the water-in-oil emulsion is injected into the tuyeres of the blast furnace can be modified.

Additionally, while the present invention has been illustrated in particular in reducing sinter and lump iron ore, it will be apparent that other blast furnace starting materials can be employed. Similarly, other hydrocarbonaceous oils can be employed as the composition of the oil is not especially critical. Oils generally suitable for blast furnace operations can be used in the waterin-oil emulsions provided pursuant to the process of the present invention.

What is claimed is:

1. In a process for the reduction of an iron ore, sinter or other such starting material in a blast furnace in which at least a portion of the reducing agent comprises an oil, the improvement comprising introducing said oil into the blast furnace in the form of a water-inoil emulsion having a water content between 3 and 15 percent by volume, said emusion being introduced in the tuyeres of the blast furnace, the amount of oil charged into the blast furnace being at least kg of oil per metric ton of pig iron in the blast furnace.

2. A process according to claim 1 wherein the water content of the water-in-oil emulsion is between 3 and 10 percent by volume.

3. A process according to claim 1 wherein the oil droplets have a diameter of less than 30 microns.

4. A process according to claim ll wherein the waterin-oil emulsion is introduced into the tuyeres of the blast furnace at a blast velocity of to 300 m/sec. at a blast temperature of 800 to l,400C.

5. A process according to claim 4 wherein the blast temperature is between 1,000 and l,4009C.

6. A process according to claim 1 wherein between 90 and 200 kilograms of oil are charged into said blast furnace per metric ton of pig iron.

7. A process according to claim 6 wherein between 100 and kilograms of oil per metric ton of pig iron are charged into said blast furnace.

8. A process according to claim 1 wherein the waterin-oil emulsion is under a pressure of between 10 and 60 atmospheres.

9. A process according to claim 8 wherein the waterin-oil emulsion is under a pressure of between 40 and 50 atmospheres.

10. A process according to claim 1 wherein the water-in-oil emulsion contains an emulsifier.

iii. A process according to claim ll wherein the oil is a heavy oil and the charge to the blast furnace comprises a mixture of sinter and lump iron ore containing fluxes said mixture containing a major amount of said sinter.

12. A process according to claim 1 wherein at least 90 kilograms of oil per metric ton of pig iron is charged into the blast furnace.

13. A process according to claim 12 wherein between 90 and 200 kilograms of oil are charged into said blast furnace per metric ton of pig iron.

114. A process according to claim 13 wherein between 100 and 160 kilograms of oil per metric ton of pig iron are charged into said blast furnace.

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Claims

1. IN A PROCESS FOR THE REDUCTION OF AN IRON ORE, SINTER OR OTHER SUCH STARTING MATERIAL IN A BLAST FURNACE IN WHICH AT LEAST A PORTION OF THE REDUCING AGENT COMPRISES AN OIL, THE IMPROVEMENT COMPRISING INTRODUCING SAID OIL INTO THE BLAST FURNACE IN THE FORM OF A WATER-IN-OIL EMULSION HAVING A WATER CONTENT BETWEEN 3 AND 15 PERCENT BY VOLUME, SAID EMUSION BEING INTRODUCED IN THE TUYERES OF THE BLAST FURNACE, THE AMOUNT OF OIL CHARGED INTO THE BLAST FURNACE BEING AT LEAST 90 KG OF OIL PER METRIC TON OF PIG IRON IN THE BLAST FURNACE.

4. A process according to claim 1 wherein the water-in-oil emulsion is introduced into the tuyeres of the blast furnace at a blast velocity of 100 to 300 m/sec. at a blast temperature of 800* to 1,400C.

5. A process according to claim 4 wherein the blast temperature is between 1,000* and 1,400C.

7. A process according to claim 6 wherein between 100 and 160 kilograms of oil per metric ton of pig iron are charged into said blast furnace.

8. A process according to claim 1 wherein the water-in-oil emulsion is under a pressure of between 10 and 60 atmospheres.

9. A process according to claim 8 wherein the water-in-oil emulsion is under a pressure of between 40 and 50 atmospheres.

11. A process according to claim 1 wherein the oil is a heavy oil and the charge to the blast furnace comprises a mixture of sinter and lump iron ore containing fluxes said mixture containing a major amount of said sinter.

14. A process according to claim 13 wherein between 100 and 160 kilograms of oil per metric ton of pig iron are charged into said blast furnace.