US2265812A - Method of reducing metallic oxides to metal without melting - Google Patents

Description

- Dec. 9, 1941.1 T. NAGEL. T 2,265,812 f METHOD oF REDUCING METALLIC' oxIDEs To METAL WITHOUTYMEL'T'ING Filed April 8, 1.941*u ATTORNEYS.

Patented Dec. 9, A1941 UNITED STATES `1 PATENT- OFFICE 7 METHOD oF REDUCING Mamme oxnmsv Y v f 'ro METAL WITHOUT `limL'rnza f;

'meedere Nagel, Brooklyn, N. Y. y Applicaun April s, 1941, serial No. 387.451

(cl. 15s-91) i 2' Claims.

My invention relates to a method for. reducing metallic oxide ore to metal.-

More speciiically my invention is directed to a method for reducing crushed metallic oxide ore to metal wherein the crushed ore continuously slides by gravity downwardly along a series of alized in that the reducing gas entering the shaft is at such a temperature Yand the ratio of reducing gas to ore-andthe relative velocities ofthe gas and ore are such as to eiect reduction of the oxides to metal without melting. i

In the accompanying drawing wherein I have illustrated an embodiment of my invention:

Fig. 1 shows in sectional elevation an apparatus suitable for the practice of the invention; and

Fig. 2 is a sectionon the line 2-2 of Fig. 1.

Referring to the drawing in detail: 2 designates an air sealed vertical shaft, equipped in its interior with a series of superimposed inclined chutes 4. These chutes are disposed in alternating or zigzag fashion so that the crushed metallic oxide ore (i` which is fed from conveyor l into a feed hopper 8 on topof the shaft, air seals thetop of the shaft 2, the crushed ore beingA continuously fed by gravity to the series of chutes down which it slides through ,the shaftv to the bottom thereof in Ainclined alternatingA The discharge for the metal and gangue is designated l and in the drawing takes the form of lan air-sealed screw conveyor |72. It will be appreciated that by controlling the `continuous discharge of the reduced ore by this conveyor the continuous movement of the furnace burden downwardly through theshaft 2 along the inclined chutes 4 is regulated.

Adjacent its lower end the shaft 2 is provided with a gasgenerating space I4 communicating directly with the shaft 2,-as shown at |6.`

Hydrocarbons are introduced by pressure into this chamber for decomposition to reducing' gas through valve controlled multiple nozzles I8. At the bottom of the space- I4 isa porous bed 20 of suitable material such as Cobble stones, brick, coke, or other suitable aggregate.

22 designates a damper controlledinlet for air. under pressure introduced at the bottom -of this porous bed.

The fuel admitted to the space I4 is a'hydrocarbon, as abovepoin'ted-out, and mayk take the form of. a liquid,` a vaporora gas.

The ratio of hydrocarbon to air {volume is readily controlled by the nozzle valves and lby the air inlet damper, these lbeing so'fadjusted that after ignition a lhot reducing gas will be pro` duced continuously under suiiicient pressure to cause the gas'continuously to 110W` upwardly of the reducing shaft 2' through the voids in the chargeof crushedfore sliding by `gravity down" wardly of the shaft. x

The reducing gas isproducedat atei'np'erature I not lower lthanapproximately 1650" F. and containscarbon dioxide in proportion ytotheconn bined volume of carbon monoxide and molecular a hydrogen approaching not more than 1 ,toi 5,;re'jspectively, While the r'atio of carbonlnonoxlde to molecularV hydrogen does not exceed approxi-v matelylto 1 by volume.

As the crushed metallic oxide ore slides'down,

. wardly through the shaft 2 through the reduc# ing gas flowing upwardly through-the shaftrthe reducing gas will percolate :through the voids of n i the mass of crushed orelacross the paths of the sliding ore. The ratej of movement of the ore, as.

above pointed out, is readily controlled by controlling the rate j of discharge of metaly andv gangue from the bottom of the shaft 2, while the ration of ore feedfto thev counte'riiowing gas volume feed is such that theore will nallyattain n the temperatureat which the .i'lnal phase oi.' re

duction will transfer oxygen from the ore tothe active reducing gas.y y

top'of the shaft 2. The gasexhausting'through this outlet is at a temperature above 212 F.'and

contains carbon dioxide in proportion tojthel combined volume of morellcarbon monoxide and molecular hydrogen-approaching not' more than approximately l to 2, respectively.

Partial combustion occurs in the space il'ln 'I the presence of excess carbon with the air which the voids of the plied by the nozzles i8 to molecular carbon required for maintaining partial 'combustion, the combustion products ubeing carbon monoxide with comparatively smaller -volume of carbon dioxide. The resulting. gas mixture con# y tains oxidizing gas in proportionfto the volume of reducing gas approaching not; more.than approximately 1 to 5, respectively, Aand the ratio of carbon monoxide to thevolumeuof,.lriolec'ulary hydrogen approaches not more than approxi-y mately 1 to 1. y It will be seen, therefore, that in this manner hydrocarbons are'fcontinuously converted-Tte a 26 designates an exhaust gas outletlnear the- (2240 lbs.) of4 iron fromtwo long tons of hema'- highly active reducing gas at the temperature required for the final phase of reduction of metallic oxides, after the ore by counterflow heat exchange with the hot gas has been preheated to the temperature required for this nal phase 5 of reduction. Following is an example of the practice of my invention with respect to thewreduction of iron ore to metallic iron. Itis understood, of course, I that this is amere illustrative example, inasmuch as other oxides may require temperature ranges and ratios of ore feed to gas volume feed different from those presently to be set out. Let us consider the production of one long ton tite (FezOs), this ore, we willassume, contains 50% iron. 'I'he temperature range of reductionstarts at approximately 800 F. and the final temperature reached by the burden is approximately 1800 F.

Three barrels of fueloll decompose .-to 91,000.. cubic feet (S. T. P.) 135 B.t. u. .fuel value per cu. ft. gas, the gas having a temperature of 2000 F. Top gas 91,000 cu; ft.` (VS. T. PJ, wet gas exhausted at 300 F.is composed of approximately 16,800 cu. ft. steam and approximately 74,200 cu. ft. dry gas of approximately 79k B.t. u.

, fuel value per cu. ft. Under the above conditions the heat balance as shown on drawing Fig. 1

approximatesz'y `Flnuimcn'(insana, Bmo'rxoNs AND Haar Bananen Furnace 'burden-4480 lbs. ore (2240 lbs.

Fe+960 lbs. Ori-1280 lbs. gangue (rock) Furnace blast-91,000 cu.'ft (S. T. P.) l135 net B. t. u./C. Fs

Highly active reducing gas` at 2000 F.

` Heat input 15,750,000 B. t. u.

Gas mma/sisA 40 CO: 3% by volume, CO 21%v by volume Ha 25%by volume N2 51% byvolume l 45 100% aanstaan/C F.

Gaseous reduction reactions of liezCav to Fe Furnace heat. balance Dry ads analysis f,

coz' 11.7% byvolme CO 17.5% by volume` 8.0% by volume N: 02.8% by volume 79 net B. t.u./C. F.`

In the above,l example oil has been taken as the hydrocarbon from which the desiredhighly reactive lhot reducing gas isproduced by atomizing a controlled supply of oil into a hot gas which is continuouslygenerated by" partial vcombustion of carbon with air'in the gas generating-space of the furnace, the carbon being liberated through decomposing thel oil to molecular hydrogen and carbon most of which carbon supplies the fuel for the above mentioned partial combustion.

It is to be understoodthat the process above 1 described may be varied asto its details without departingirom the spirit and scope of my ir-v vention. Y What I claim is: 1. The method oi' reducing metallic oxide ore to metal, whichmethod comprises continuously sliding crushed metallic oxide-ore by gravity in controlled flow'v in inclined alternating paths through an air-sealedv shaft, simultaneouslyand continuously producing av hot CO+H2 reducing gas under pressure near'the lower end of the Y said shaft, and while confining the gas to the shaft flowing allv of the gas upwardly-through the voids of 'the mass of crushed oreacross the paths of said sliding crushed ore,` the" gas temperature, the ratio of gas to crushed ore and the relative velocities of the gas and crushed ore being such as continuously to effect progressive reduction of the ore to metal4 without melting as they temperature of the crushed ore progressively `in creases. y

- 2. Thefmethodof `reducing metallic oxidefore to metal, which method comprises continuously sliding crushed metallic oxide ore by gravity in controlled flow1'in"inc1ined alternating paths throughfan air-sealed shaft, simultaneously and continuously producing a reducing gas near the lower end of the shaft, the gas beingproduced under pressure at a temperature not less than approximately 1650 F. and containing CO: in

volume relative to CO+H1 not more than approximately 1 to 5, respectively, and lCO in volume relativeto Hz not more than approximately 1 to '1, andwhile confining this gas to the airsealed 'shaft flowing all of the gas upwardly through the voids Vof the porous mass of crushed ore across the paths thereof, the gas temperature, the ratio of gas to ore and the relative velocitiesofthe gas and ore being such that the gas after thus flowing through the voids of the mass o f crushed ore will be at a temperature above 212` F. and contain CO2 in volume relative to e CO-l-Hz of not more than approximately' lf-to 2, respectively, and progressive andcontinuous reduction of the ore to metal without melting will be effected as the temperature of the sliding crushed ore progressively increases.

, THEoDoRE NAGL.

CERTIFICATE OF CORRECTION. Patent No. 2,265,812. December 9, 19).;1..v

THEODORE NAGEIJ.

It is hereby ertfed that error appears in the printed specification ofthe above numbered patent requiring correctionas' follows: Page l, second column, lne'O, for "ration" read -erat1o;,lne59, strike ont the l wor-d "more"; and that the said Letters Patent `should be read with this cor` recton therein that the same may onoz'm to the record of the case in the Patent office. q

Signed and sealed this 15th day of January, A.- D. 1911.2.

v y Henry van Arsdale, (Seal) Acting ICozmnissioner of Patents.

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