US2231760A - Method of reducing iron ores and the like - Google Patents

Description

1941- i c. v. FOERSTER, JR., ETAL 2,231,760"

METHOD OF REDUCING IRON ORES AND THE LIKE I Filed July 12,1959

Fig.2 7 INVENTOR.

319275225 r' CAPE ATTORNEY. 7

Patented Feb. 11,

METHOD OF REDUUENG IRON GEES AND siren stares rArsNr "OFFICE Charles V. Foerster, Jr; Howard L. Griswold, and; Arthur '1. Cape, Santa Cruz, Calif.

Application July 12, 1939, Serial No. 284,076

'3 Claims.

space thus formed with a suitable refractory cement 9.

The tower section 4 rests on an annular plate ill-mounted on the base of the tower portion oi the furnace, and a collar il,.which may be secured to the plate 18 provides a seal at this point and serves to facilitate the central positioning of the tower section 4.

In the accompanying drawing, forming a part 4 of this specification, and in which like numerals are employed to designate like parts throughout the same. 5

Fig. 1 is a fragmentary view, showing apparatus which may be employed for practicing the present invention;

Fig. 2 is a vertical cross-sectional view,- on an enlarged scale, showing the reducing tower; and Fig. 3 is a transverse cross-sectional View, taken on the line 3-3 of Fig. 2.

Referring more particularly to the drawing, A designates generally a furnace formed of a suitable refractory material and comprising a reducing gas inlet portion I, a portion 2 for supplying heat to the reducing tower, and a tower portion 8.

Disposed vertically within the tower portion formed of a heat and corrosion-resistant alloy steeland of generally cylindrical form, and consisting of a lower section 4 and an upper section 5, separated from each other, as by an annularplate 6, which is desirably welded or otherwise secured to eitherthe upper end of the lower section or lower end of the upper section. The ,tower sections thus provide a lower chamber C and an upper chamber D.

Secured, as by welding, to the outer surface Mounted within the lower end of the tower section 4 is a. hopper II which communicates 10 I with a conduit l3, within the upper end of which is secured a nozzle it having a central vertical passageway l5 and a plurality of radially extending openings l6 communicating the interior of the conduit I: with, such passageway I5. 15

The upper surface of the nozzle I4 is in effect a continuation of the hopper surface, thereby facilitating the discharge of the reduction products, as will be presently described.

A conduit H, which serves a purpose tobe 20 presently described, is in communication with the conduit l3, and the conduit IS, 'in turn is connected as by means of a discharge pipe to with a sponge cooler i9. A plug 29 is movable 3 of the furnace is a metallic tower B,preferably f' nozzle which is similar in an respects to the nozzle N, that is to say, it has a vertically extending passageway 23 and a plurality of radially extending openings 24, which communicate the interior of the tower section 5 with such passageway 23. Each of the tower sections I and 5 is provided with a multiplicity .of circumferentially spaced radially extending reinforcing fins or ribs 25, which are also eflective to increase the heatretentlvity of such tower sections.

of the section 4 adjacent its upper end is a collar Secured, as by hold-down rods 28, to brackets 21 within the upper end or the tower section 5, is an exhaust gas header 28 having an opening 45 29 therein for chargingthe ores or'like products to. be reduced into the chamber D. A reducing gas exhaust stack 30 extends upwardly, in an inclined direction from the header 28, and has adamper 3| mounted therein. A number of circumferentially spaced poke-hole openings 32 are provided in the base flange 3'3 of the header 28, and a gas-tight sealis provided between the tower section 5 and the flange 33 by filling the annular space between a ring 34, secured to the base flange 33, and the upper end of the tower section 5, with cement packing 35.

Means are also provided, in the form of a burnernozzle 36, for supplying heat to the space which surrounds the tower sections 4 and 5 for heating suchsections, the exhaust gases being discharged through a stack 31.

Thermo- couple wells 38 and 39 are provided for respectively determining the temperatures within and without the reducing tower sections, and slotted tubes 40 and ll are also provided for extraction of analysis samples of the gases within these tower sections. Sight tubes 42 are also provided for observing conditions within the tower section 4.

The apparatus which has been described is particularly adapted for reducing ores in a relatively fine state of subdivision, such for example, as certain sands, massive ores which have been crushed and sized, as well as iron oxide obtained from various chemical processes.

For the purpose of reducing these ores and/or oxides, a reducing gas is employed, such gas being preferably one consisting of a mixture oi carbon monoxide, hydrogen and nitrogen, and containing a minimum of carbon dioxide and water vapor. Such a; gas is produced, for example, by the method disclosed in the United States Reissue Patent No. 19,770 to William D. Brown. The hot gases, produced in accordance with the aforesaid patent, are introduced into the apparatus through the conduit II and pass upwardly into the chamber C through the conduit l3 and nozzle II and into the chamber D through the nozzle 22. At the same time, the ore or oxide which is to be reduced, is introduced into the chamber D through the opening 29, and by suitable adjustment of the gas flow, the ore or oxide is maintained in the chamber D, the velocity of the gases in the passageway 23 of the nozzle 22 being sumcient to overcome any tendency of the ore in thechamber D to pass downwardly through such passageway. The velocity of the gases which pass into the chamber D is suflicient to maintain the ore in a relatively violent state of agitation, so that the gases are thoroughly intermingled with the ore and the ore is partially re duced in the chamber D.

With the ore thus partially reduced, the flow of gases into the chamber D is decreased or entirely stopped, permitting the partially reduced ore to fall through the passageway 23 of the nozzle 22 and into the chamber C, the plug 20 having flrst been elevated to close the lower end of the passageway IS in the nozzle ll, to thereby prevent any of the partially reduced ore from falling into the conduit I 3. The flow of gases in the chamber C is then resumed, the gases entering the chamber through .the radial openings l6 and passageway. IS in the nozzle II. The velocity of these gases, in their passage through the relatively small passageway I5, is sufllcient to overcome any tendency of the partially reduced ore in the chamber C to pass downwardly through such passageway, it being understood that as soon as .the flow of gases has been resumed, the plug 20 is'lowered. The velocity of the hot gases which pass into the chamber C is sufllcient to maintain --the-partially reduced ore-in a 'Violentstate of agitation, so that the gases are thoroughly intermingled with such ore, and the reduction of the ore is completed.

When the flow of gases into the chamber'C has been resumed, and a suflicient time interval has elapsed for such gases to pass upwardly into the chamber D, a second charge or batch of ore is introduced into the chamber D.

When the orein the chamber C has been completely reduced, the flow of gases is decreased or stopped, permitting the sponge iron to fall through the passageway I 5, through conduit l3 and pipe I 8 into a coolerl9. At the same time the partially reduced ore in vthe chamber D falls into the chamber C. Y

The burner 36 supplies suflicient heat to the tower sections 4 and 5 to compensate for radiation losses, so that the heat necessary for the reducing reactions is supplied primarily by the reducing gases themselves. In other words, the heat is supplied under most eflicient conditions. Moreover, the gas-ore contact is ideal, and no mechanical parts are essential to'the satisfactory operation of the apparatus.

The reducing reactions are primarily between the iron oxide and the carbon monoxide and hydrogen.

The method thus embodies the counter-current principle of operation, but is intermittent to the extent that the ore is not falling continuously but is maintained in each of the chambers for a 'period of time suflicient to produce the degree of reduction desired in such chamber. As the gases rise, theybecome increasingly cooler, of course, so that the minimum degree of reduction occurs in the upper or cooler portion of '2 the tower, and the maximum degree of reduction in the lower or hotter portion of .the tower.

It will be understood that the apparatus need not necessarily be confined to the use of two superposed tower sections, but that as many sections and chambers as may be required to accomplish the desired reduction may be employed, depending on the nature of the ore, the state of subdivision thereof, and other factors well known in the art to which this invention relates. Moreover, it is not essential thatthe tower sections be cylindrical or that they be of uniform crosssectional area throughout.

It is to be understood that the form of our invention, herewith shown and described, is to be taken as a preferred example of the same,- and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of our invention, or the scope of the subioined claims.

Having thus described our invention, we claim:

1. In a method of reducing iron ores and the like in a vertical tower having vertically-spaced ore passage points of restricted cross-sectional area, the steps which comprise flowing the ore downwardly in said tower and flowing hot reducing gases upwardly through the tower in countercurrent relation to the flow of ore, the velocity of the gases through said points of restricted cross-sectional area being sufllcient to overcome any tendency of the ore passing downwardly I like in a vertical tower having a point of restricted cross-sectional area, the steps which comprise flowing the ore downwardly in said tower and flowing hot reducing gases upwardly through said point of restricted area and into said tower, the velocity of said gases at said point being suflicient to prevent the ore from flowing downwardly through said point of restricted area and the velocity of the gases which pass into said tower above said point being suflicient to maintain the ore in a relatively violent state of agitation, so that the gases are thoroughly intermingled with the ore, and. thendecreasing the flow of gases sufficiently to permit the ore to fall through said point of restricted area. I

3. In a method of reducing iron ores and the like in a vertical tower having at least two vertically-spaced reaction chambers and points of smaller cross-sectional area than said chambers below said chambers, the steps which comprise flowing the ore downwardly in said toWerand into the uppermost chamber, flowing hot reducing gases upwardly through the uppermost of said points and into said uppermost chamber, the

velocity of the gases passing through said upper- I most point being suificient to prevent thetores from flowing downwardly through saidaupper'inost point, reducing the gas pressure topermit the partially reduced ore to flow through said upper point, flowing hot reducing gases upwardly through the lower of said points and into the lower chamber, the velocity of the gases passing through said lower point being sufficient tqprevent the partially reduced ore from flowing through said lower point, and then reducing .the gas pressure to permit the ore in said lower chamber to flow through said point.

CHARLES V. FOERSTER, JR. HOWARD L. GRISWOLD. ARTHUR T. CAPE.

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