US2285487A - Method of and apparatus for producing sponge iron - Google Patents

Description

J. E. BATIE June 9, 1942.

METHOD 0F AND APPARATUS FOR PRODUCINGSPONGE IRON `Filed Jan. 15, 1940 I NV EN TOR.

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Patented June 9, 1942 METHOD or AND APPARATUS Foa Paonccmc sPoNGE -moN Joseph E. Batie, Detroit, Mich.; assigno to Kelsey-Hayes Wheel Company, Detroit, Mich., a corporation of Delaware Application January l5, 1940, Serial No. 313,987

7 Claims.

conveyor and the reduced metal is discharged from the outlet end thereof.

Another object of the invention is to provide improved means for maintaining the oxide separate from the materials with which it is reacted, thereby-facilitating the separation of the reduced metal from the excess reducing agent.

A further and more speciiic object of the invention is to produce sponge iron at low cost by a continuous, low temperature reduction process.

shown, these pulleys are mounted on a frame 23, which in turn projects outwardly from and is secured to the shell 24 of the furnace I0. A suitable drive mechanism for the conveyor belt is provided, but as this is conventional practice, it is not illustrated in detail but indicated only diagrammatically as being a shaft 25 journaledv in a bearing 26 attached to the frame 23. 'I'his shaft is connected by suitable means, not shown, to the pulleys 2| and 22 which, therefore, become the driving pulleys. Means is also providedfor taking up the slack in the conveyor belt, and this is illustrated diagrammatically by the adjustingy screw 21 threadedly engaging a lug These and other objects are attained by the improved process and apparatus hereinafter more fully described and illustrated in the accompanying drawingyrwherein Figure 1 is a longitudinal section through an apparatus embodying my invention;

Figure 2 is a cross section through the reducing passageway taken on the line 2--2 of Figure l1;

Figures 3 and 4 are similar cross sections on lines 3-3 and 4 4, respectively, of Figure 1.

IB represents a furnace of suitable construction adapted to maintain the temperatures at which the metal oxide to be reduced reacts with the reducing material. 'I'he furnace is preferably provided with insulating walls, the inside surfaces of which are shown by the dotted line Ill- A. Extending lengthwise through this furnace is a rectangular tube Il which forms the reduction passageway l2 of the apparatus. The tube projects beyond the ends of the furnace, and at the inlet end is provided with loading apparatus hereinafter more fully described, and at the outlet end I3 it is connected to a vertical conduit or well I4. belt which extends throughout the length of the reduction passageway and is supported on the lower wall I6 thereof. |1 and I8 are pulleys for the conveyor belt which are mounted within the well I4 and are arranged one above the other so that the conveyor belt passes downwardly as inf dicated at I9 in the vertical well and then backwardly through a slot 2U in the wall of the well. At the entrance end of the apparatus are two other pulleys 2l and 22 over which the conveyor belt rides to complete the endless circuit. As

l5 is an endless conveyor 28 on the frame 23 and adapted to bear against the end plate 29 of the shell 24.

At the entrance end of the reducing passageway, the tube H has the upper wall thereof cut away and replaced by the cover plate 21. 'I'his plate is provided with suitable apertures through which project the discharge ends of three hoppers 28, 29 and 30. The'int'ermediate hopper 29 is filled with the metal oxide to be reduced, while the hoppers 28 and 30 on opposite sides thereof are filled with .the material which is to be used for obtaining the reducing reaction., 3| is the iront wall of the tube II which extends downwardly from the cover plate 21, leaving suilicient space below the same for the conveyor belt I5 to enter the tube.

The reducing material from the hopper 28 fills the portion 32 of the tube Il as indicated in Figure 2, it being discharged through the mouth of the hopper by gravity. 33 is a gate between hoppers 28 and 29, and the lower edge 34 is spaced from the bottom wall I6 of the tube by a predetermined distance designed to form a layer of reducing material on the belt to the desired depth. The gate also is provided with a slot 35 through which a thin strip 31 of flexible material, such as paper, may pass. This strip covers the top of the lower layer 35 of reducing material and separates the same from the material discharged from the hoppers 29 and 30.

The strip 31 is obtained from a roll 39 of material arranged in a suitable location for convenient feeding into the apparatus.

The hopper 29 discharges the metal oxide into the portion 40 of the reducing passageway onto the strip 31 above the layer 36. The depth of the layer of oxide is controlled by the gate .4|- between hoppers 29 and 30. The gate 4I has on each side thereof a downwardly projecting portion 42 which extends inwardly from the side walls of the tube Il so as to make the layer of so that the material in the upper layer spreads over the lower and intermediate layers as indicated in Figure 4.

With the apparatus as thus far described, it

will be seen that the arrangement of hoppersA and gates causes the conveyor belt I5 to be loaded with consecutive layers of reducing mate- In carrying out the process of this invention,

' the reduction passageway is heated to a tempervature at which the-carbonaceous material reacts with the iron' oxide to reduce the same to the metallic state. A suitable temperature is vapproximately 1800 F., but this may be increased under some circumstances to as high as 2200 F. thereby increasing the speed of reaction.

From the above description it will be observed thatI have provided a method for low temperature reduction of iron oxide and other metal rial, oxide and reducing material, each of which is separated `from the other by a strip of paper or other suitable material. The oxide is thus entirely surrounded by thereducing material. As the conveyor passes through the passageway I2 the oxide and reducing materialare brought up to the temperature at which the reducing material is converted into reducing gases which in turn react with the separated body of oxide'. l

The length of the passageway I2 is suflicient so that with a given speed of the conveyor belt and the proper temperature within the furnace, the oxide is entirely reduced before it leaves the heated portions of the apparatus. vDuring this time the separating strips 31 and 44 are charred,

oxides which is relatively simple and is adapted for continuous production of iron sponge.

What I claim as myinvention is: 1. The method of reducing metal oxides which vcomprises forming on a conveyor belt a layer of metal oxide between' upper and lower layers of carbonaceous reducing material with separating strips between adjacent layers, moving said conveyor belt through a reduction passageway, and

heating said reduction passageway to a temperature at which said carbonaceous reducing material reacts with said oxide to reduce the same to the metallic state.

2. 'Ihe method of reducing metal oxides which comprises moving a' conveyor through a substantially horizontal reducing chamber, discharging carbonaceous material on said conveyor to form a layer, feeding a strip of paper on top of said layer, discharging metal oxide onto said paper strip to form a superposed layer, feeding but they nevertheless retain sufficient body so as to form an effective means for keeping the oxide and reducing materials separated. After the materials have completed the travel through the passageway I2, they enter the well I4 where the reduced metal and theexcess reducing material fall to the bottom thereof. To prevent reoxidation of the reduced metal while in the well I4, it is preferable to circulate a non-oxidizing gas, such for example as natural gas, and this is introduced into the well through the inlet nipple l48.

Below the well I4 is arranged a cooling chamber 49 separated from the well by a withdrawable gate 50. A non-oxidizing gas is also introduced into the cooling chamber through the inlet nipple 5I. At periodic intervals the gate 50 is opened, permitting the accumulated oxide and excess reducing material to fall into the same. A water jacket 52 surrounds the cooling chamber and serves to cool the materials within the a strip of paper fon top of said oxide layer, discharging carbonaceous material on said second paper strip, heating said reducing chamber to a temperature at which 'said oxide is reduced by said carbonaceous material to metal sponge, and discharging the reduced metal'and excess carbonaceous material from said conveyor.

3. The method of producing sponge iron which comprisesforming on va conveyor-belt a layer of iron oxide between upper and lower layers of carbonaceous material with separating strips between adjacent layers, moving said conveyor belt through a reduction passageway, and heating said reduction passageway'to a temperature at which lsaid carbonaceous material reacts with said iron oxide to reduce the same to sponge iron.

4. Apparatus for reducing oxides comprising a substantially horizontal reducing passageway, a

chamber to a temperature below that where re- With the apparatus as described, various metal oxides may be reduced' by selecting the'proper reducing material for the hoppers 28 and 30. As previously stated, the invention is particularly adapted for the production of sponge iron, and when it is used for this purpose the hopper 29 is lled with iron oxide while the hoppers 28 and 30 are lled with a carbonaceous' material such as wood charcoal, coal, coke, etc. The proper selection of the carbonaceous material is important.

One material which may be used advantageously in the apparatus of my invention is charcoal. Another material that is .effective is a mixture of ordinary coke breeze together with sodium nitrate. This latter material forms the subject matter of a copending application, Serial No. 313,988, filed January 15, 1940.

through a discharge gate 53 at the bottom thereconveyor in said passageway, means for feeding a charge of reducing material onsaid conveyor, means for feeding a separating strip over the charge on said conveyor, and means for feeding a charge of oxide on said separating strip.

5. Apparatus for reducing oxides comprising a substantially horizontal reducing passageway, a conveyor in said passageway, means for separately discharging a charge of oxide and a charge of reducing material onto said conveyor, means for feedingastrip between said charges to sepa- .rate the oxide from the reducing material, and' means for heating said passageway to a tem- -perature at which the separated reducing material reacts chemically on said oxidey the same to the metallic state.

6. Apparatus for reducing metal-oxides comprising areducing passageway, an endless conveyor belt extending through said passageway and returning outside of said passageway, a hopper for discharging a layer of carbonaceous material on said belt, a flexible strip adapted to to reduce be drawn over said layer, a second hopper for discharging a layer of metal oxide on said flexible strip, a second flexible strip adapted to be drawn over said oxide layer, a third hopper for dising strip on top of said layer, discharging metal 'oxide onto said separating strip to form a layer,

feeding a separating strip on top of said oxide layer, discharging carbonaceous material on said second separating strip, heating said reducing chamber tp a temperature at which said oxide is reduced by said carbonaceous material to the metallic state and discharging the reduced metal and excess carbonaceous material from said 10 conveyor.

JOSEPH E. BATIE.

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