US2288613A

US2288613A - Process of reducing metallic oxides

Info

Publication number: US2288613A
Application number: US335763A
Authority: US
Inventors: Gilbert D Dill
Original assignee: MINERALS AND METALS CORP
Current assignee: MINERALS AND METALS Corp
Priority date: 1940-05-17
Filing date: 1940-05-17
Publication date: 1942-07-07
Anticipated expiration: 1959-07-07

Description

Jul 7, 1942. G. D. DlLL 2,288,613

PROCESS OF REDUCING METALLIC OXIDES Filed May 17, 1940 'INVENTOR Gasser 0. Our.

BY I

raenea -1, i942 OFFICE f Gilbert n. mu, Wilmette, nt, aasignor, by mesne assignments, to Minerals and Metals Corporation, New York,.N. Y., a corporation of Delaware Application May 17, 1940, Serial No. 335,763 (or 75-89) 4 Claims. This invention relates to the direct reduction of metals from their oxides or other compounds,

.and particularly to the preparation of metal oxides or othermetal compounds for direct reduction. a i

In the direct reduction of metallic oxides at temperatures below the melting point of the metal, it is important, since the metal, after reduction, will usually maintain substantiallythe physical form or frame in which it exists in the oxide, that the reducing agent be brought into intimate association with the various parts of .the oxide in order that it may perform its oxygen removing function throughout all parts of the metal skeleton. Many processes of effecting direct reduction of metals from their oxides, heretofore devised, have failed, when it has been attempted to practice them upon a commercial also'because of the presence of numerous cleavage planes, this catalytic cracking and decomposition will result in the carbon, which is released by the, catalytic decomposition, being deposited'not only upon but also within the oxides, substantiallycompletely filling the pores and iriterstices therescale, because it has been impossible, in com-' mercial scale opera ions, to secure the intimate association of the reducing agent with the various parts of the oxide requisite to complete reduction.

The present invention aims to take advantage of the catalytic characteristics of certain metallic compounds, either as they appear in nature or in forms to which they can readily be convert ed, to procure, by a preliminary treatment in which advantage is taken of the catalytic activity of the metallic compounds, such an intimate association of the reducing agent with the metallic compound that, when the compound is latersubiected to reducing conditions, a quick, com-' plete and clean reduction will take place.

It has been established that compounds of metals of the iron group, and particularly the oxides of iron, nickel, cobalt, and manganese,

of. If the oxides have been ground or otherwise brought into a fairly finely divided condition, not only will this catalytic reaction between the oxide and the heated hydrocarbon result in the particles of the oxide being given a protective coating of carbon to prevent sintering or sticking at the temperatures to which they are subjected in the ensuing reduction operation, but both the coating carbon and the carbon which has penetrated into the pores of or spaces within the oxide will be in such intimate association withthe oxide that when the oxide is raised to the reducing temperature the carbon will immediately react with the oxygen of the oxide and eflect a rapid and complete reduction thereof. a

The invention aims not only-to improve the treatment of metallic oxides preparatory to direct reduction, but also so to effect such treatment that the hydrocarbon employed to furnish the reducing reagent may itself be improved in composition vby the catalytic treatment which has decomposed and/or cracked and/or to some extent reformed its higher boiling point constituents. Furthermore, the invention contemplates so carrying-out the catalytic impregnation treatment as to provide or to assist in providing reducing gases for use in later stages of the process have the capacity, when brought into contact with hydrocarbon oils heated to temperatures in what is known as the catalytic cracking range of such hydrocarbon oils, which temperatures may range from 700 to 1000 F. for diil'erent oils, to effect a cracking of these oils with a considerable decomposition of the heavier constituents thereof and a resultant deposition of carbon, almostin molecular form. Such. catalytic activity of metals of the iron group extends also to cracking and/or decomposition of some of the hydrocarbons present in natural gases. Moreover, it is not confined to compounds in which only one of the metals is present but is also exhibited by complex compounds including two or more of the metallic elements. i

Because of theporous nature of the oxides of metals of the iron group as they appear in nature,

and. even in some of their artificial forms, and 55 stepb'ut that, with slight and also improved fuels for maintaining the required reaction temperatures.

Among the particular objects of the invention is to insure the bringing of the finely divided metallic oxide and the hydrocarbon into such intimate association with each other and under such conditions, particularly of temperature, that the desired decomposition and hydrocarbon reforming reaction will take place. A further object of the invention is to insure the maintenance of the intimate association until the desired impregnation of the oxide with the carbon resulting from thedecomposition has'taken place.

Other objects and important features of'the invention will appear from the following descrip- J tion inwhich the manner of practicing the invention is particularly described in its application to the carbon impregnation and/or coating of oxides of iron. It will be understood, however,

that the invention is not restricted to the prepa-' ration of iron ores or oxides for the final reducing variations in the physical planes or the iron oxide.

conditions surrounding the reaction, the invention is equally applicable to the preparation the ores or oxides of nickel, cobalt and manganese tor the anal reducing step and also to the preparation for reduction of any other metal oxides or mixtures of metal oxides whichhave the requisite capacity for catalytically decomposing hydrocarbons.

In preparing iron. ore for treatment by the process or the present invention, the ore will be cleaned and crushed to that degree of fineness necessary iorthe removal 01 the gangue to the desired degree, which in most cases will be from 80 mesh up to 100 mesh or even finer, depending upon the character or the ore. From this crushed and now finely divided ore substantially all or the gangue or impurities will be removed by any of the known methods of concentration suitable to the particular type oi ore, such as the magnetic separation employed with ores comprising principally the magnetic oxide FeaOs. Other known methods may be employed in concentrating the ores comprising principally rerric oxide, FesOs The ore, having been concentrated until it consists mainly of FeaO: or these oxides, is then thoroughly heated and brought to the temperature most suitable for efiecting the partial decomposition or cracking of the particular hydrocarbon to be used in effecting the carbon impregnation and/or coating oi the ore. with an iron oxide as the catalytically active oxide to be treated and with a hydrocarbon oil having, among its constituents, high boiling point hydrocarbons; decomposition will begin in the neighborhood oi 800 1}. and the ore may, therefore, be heated to that temperature.

The selected hydrocarbon oil will also be heated to substantially the same temperature, that is 800 'I*., at which temperature it will be con-. verted into a vapor, and the heated ore and the heated vaporwill then be brought into such intimate association with each other that the catalytically induced reaction will .take place and some at least orthe constituents oi the hydrocarbon will be decomposed, leaving iree carbon within the pores, recesses and interstices or cleavage The decomposition will usually be accompanied the hydrocarbons into lower boiling point hydrocarbons which can be separated in iractionating towers in the form oi more marketable petroleum products, such as gasoline. The heavier portions which have not been decomposed or cracked in their first passage through the reaction zone may be recirculated.

In order to efiect the desired intimate association and to maintain it for a sufilciently long time to secure the desired impregnation, the process is preierably practiced in apparatus in which the finely divided ore may be entrained in a stream or the hydrocarbon vapor, which is brought into a turbulent state, and in which the ore, by partaking oi the turbulent movements or the hydocarbon vapor, is causedto be thoroughly commingled therewith and thus brought into and maintained in reactive relation thereto.

A suitable apparatus for efiecting the desired commingling and interaction of the finely divided ore and the hydrocarbon vapor is that described in my co-pending application Serial No. 244,612; filed December 8, 1938, and in my co-pending application Serial No. 341,478 filed June 20, 1940, which is a continuation in part of application Serial No. 244,612 in which provision is made for F8304 or oi mixtures orby cracking 01 some of bringing a fiuid such as the hydrocarbon vapor here employed into a turbulent state by causin it to fiow throughsuccessive zones of higher than average velocity and lower than average pressure and or lower than average velocity and higher than average pressure. The finely divided material, such as the oxide to be treated, may be entrained in thefiuid to partake oi the turbulent movements thereof. In this apparatus of my copending application, a thorough commingling oi the hydrocarbon vapor and the finely divided oxide can be eflected. A selective recycling is also provided for, thus insuring that eve y particle of the oxide, from the finest to the largest, will be sufilciently coated and/or impregnated with carbon to bring about the desired rapid and complete reduction when raised to the reducing temperature of metallic oxide upon which the process is being practiced.

In the accompanying drawing is illustrated apparatus for practicing the. novel process of the present invention.

Referring to the drawing, the vaporized and preheated hydrocarbon, having the preheated finely divided ore entrained therein, is introduced into the intake pipe 2 of reaction apparatus such as disclosed in my copending application Serial -No. 244,612. The intake pipe 2 has connected to its upper end one section 4 oi a venturi, the section 4 having a comparatively steeply tapering interior passage 0 to produce the desired increase in velocity and reduction in pressure of, the infiowing fluid. The upper end of the section 4 of the venturi the bottom of an inverted irusto-conical partition orbaiiie 8 and, to permit making the opening in the batle 4 not much larger than the "outlet oi the passage 4, the outeriace oi the section 4 may be tapered substantially to an edge where it meets the upper end of the substantially straight throat It in the upper part of the passage 8.

The inverted irusto-conical partition or baiiie 8 forms the bottom of the lower reaction chamber l2 and a similar partition or bailie l4 forms the bottom or the upper reaction chamber it. Each of these irusto-conical partitions or baiiles II and i4 also serves as a hopper-like structure .to direct the vaporized hydrocarbon and any entrained ore to be re-circulated to the low pressure part-oi the venturi, more fully to be described hereinafter.

Positioned above the upper end of the section 4 of the venturi is a section it in which is formed the expansion end of the venturi, the a section l8 having at its lower end a bell-mouthed opening 20, this lower end of the section it being spaced from the upper end of the section 4 sufiiciently to provide an annular passage into the passage through the venturi. The conical or bell-mouthed lower end 20 of the passage through the section is communicates at its upper end with the expansion passage 22 of the venturi which discharges into the reaction chamber l2. Located above the expansion passage 22 of the venturi and preferably in coaxial alignment therewith is a streamlined baile 24 ot'substantially the ideal streamlining of a tear drop. This bai'iie 24 is supported by sheet metal supports 24 carried by the partition member 8 and spaced apart. These supports 24 also carry the upper section is of the lower venturi.

Carried by the irusto-conical partition member I4 is the lower section 28 or a second venturi bearing the same relation to the partition l4 that. Y

passes through with respect to its associated venturi as the hat-- fie 2 a The side wall ofthe chambers l2 and I6 is formed bya cylindrical casing member 36 closed by

end members

38 and 40, the end member 38 being provided with an opening in which the section 4 of the lower venturi is fitted and the in which the discharge pipe 42 is fitted. The entire casing is preferably surrounded by an insulating covering 44 to prevent the loss .of heat during the carbon impregnationreaction.

The apparatus of my co-pending application having been operated and controlled to produce the requisite coating and/or impregnation of the oxide with carbon, the stream of cracked and and I6 1 the reformed hydrocarbon and impregnated ore enter the discharge pipe. 42, the ore being now thoroughly impregnated and/or coated with carbon position of the hydrocarbon and the hydrocarbon having been reformed as a result of the catalytic action of theo The discharge pipe 42 is connected with a centrifugal-separator 46 which may be of any usual construction in which 1 by centrifugal action the carbon coated and imend member 40 being provided with an opening partly decomposed, hydrocarbon vapor, which has entrained therein the coated and/or impregnate-d ore, is discharged from the reaction chambers of the apparatus. A separation of the impregnated ore from the vapor can be effected by any suitable dust separating process, for example, by centrifugal separation, and the vapor then conducted to a condensing tower, where its heat may be given up to the incoming hydrocarbon or otherwise conserved, while the coated and impregnated ore, in its still heated condition, is conducted to the reduction chamber of suitable reducing apparatus.

Apparatus particularly adapted for handling finely divided ore is that described and illustrated in the co-pending application of James C. Hartley, Serial No. 338,560, filed June 3, 1940 and in the co-pending application of Herman A. Brassert and James C. Hartley, Serial No. 323,076, filed March 9, 1940, of which application the application Serial No. 338,560 is a continuation in part, in which the finely divided ore is maintained in a condition of substantially continuous agitation and progression while being exposed to reducing heat, the agitation and progression being effected by means of a heated fluid through which a substantialpart of the reducing heat is supplied to the oxide to be reduced. In the case of the carbon impregnated ore, the heating and agitating fluid or gas may be a neutral non-oxidizing gas, or it may be a reducing gas,-such as carbon monoxide or hydrogen or amixture of carbon monoxide and hydrogen, depending somewhat upon the nature of the impurities that may still remain in the coated and impregnated ore.

The preheated hydrocarbon vapor with its entrained preheated ore passes in succession through the chambers l2 and I6 of the impregnating apparatus hereinabove described, in which apparatus it travels insuccession through zones of relatively high velocity and reduced pressure and of relatively lowervelocity and higher pressure and is thus subjected to marked turbulence resulting from these sudden changes of pressure and velocity and also from the acincidental recirculation back through the ven-' turis. After undergoing the thorough com mingling .and interaction in the chambers I2 pregnated ore is separated from the reformed hydrocarbon gases and/or vapors, the ore passing downwardly through the discharge pipe 46 into the reduction chamber paratus presently to be described and such as shown in the co-pending application of Herman A. Brassert and James C. Hartley, Serial No. 323,076, filed March 9, 1940, of which the application of James C. Hartley, Serial No. 338,560, filed June 3, 1940, is a continuation in part. The reformed hydrocarbon gas or vapor passes out through the discharge pipe 66 by which it may be conducted to any suitable condensing tower or fraetionating apparatus as hereinabove suggested.

The finely divided ore which has been coated and impregnated with carbon in the reaction chamber hereinabove described and separated 4 from the'reformed hydrocarbon vapor or gas in the centrifugal apparatus 46 is delivered by the pipe or chute 46 upon the refractory hearth 62 which is perforate, the perforations 64 being all inclined forwardly in the same general direction as shown. The reaction chamber 48 may be enclosed by a wall 66 of heat-resisting material and in turn be located within a heating chamber 68 having a surrounding wall of heat-resisting material, which, inturn, is surrounded by heat insulating material 62. Bumers 64, located beneath the floor of the chamber 48 and supplied by a gas manifold 66, provide means for supplying external heat to the chamber 46 and also to the manifolds 68 which supply heating and agitating gases to the perforations or jet orifices 64. The heating and agitating gases for the orifice manifolds 68 are supplied to these manifolds through a longitudinal manifold 10. The manifold 10 is heated by the products of the reaction leaving the chamber 46 through the discharge pipe 12 and passing through a jacket 14 surrounding said manifold.

The gases introduced into the orifice manifolds 68 through the longitudinal manifold 10 are under pressure and as they pass up through the orifices 54 in the hearth 62 they effect an agita- 0 which in the case of a carbon impregnated ore -tion of'the streamlined baiiies24 and 34, with neednot contain any reducing constituents, are, of course, non-oxidizing, their purpose being to provide agitation, additional heat to raise the ore to the reduction temperature and advancing movement of the ore over the hearth into the discharge pipe 16. Any suitable non-oxidizing gas may be used for this purpose, but I' prefer to use carbon monoxide since it will mix with the carbon monoxide formed as the product of the reduction in the chamber and thus can readily be recovered in any suitable recovering or reforming apparatus.

It is important, of course, in the reduction of ,,finely dividedviron'ores, at temperatures below the melting point of the iron, that the sponge 46 of reduction ap-' iron resulting from products,

' nish the carbon will the reduction, which is very' readily oxidizable, I and, when produced at low temperatures, is pyrophoric, be protected against reoxidization until it is eiher converted into a finished product or reduced to a temperature at which it is not so readily oxidized. Sponge iron. produced at the temperatures preferable employed in the reduction of the oxide in accordance with the present process, that is, from 1400 F. up to 1800 F., does not usually show pyrophoric characteristics and it is therefore primarily essential to insure its protection-against reoxidization.

This protection can be afforded either by maintaining the sponge iron, resulting from the reduction, in a protective non-oxidizing atmosphere until it is cooled below the temperature at which'it is readily oxidizable or it may be handled in such a way that the heat still remaining in it at the end of the reduction operation may be conserved. Processes for converting the reduced sponge iron intofinished products, in which processes at least part of the heat remaining in the iron at the end of the reduction step is utilized in the next step, are disclosed in the patent applications of Herman A. Brassert, for improvements in'the Manufacture of metal Serial No. 316,717, filed Feb. 1, 1940; 318,814, filed Feb. 14, 1940; and Serial No.. 319,197, filed Feb. 16, 1940.

As hereinabove suggested, the hydrocarbon vapors, after having passed overthe catalytically active oxide, will have one or more oi their higher boiling point constituents decomposed to furfor treating the oxide and this decomposition, and possibly some cracking without carbon deposition, will usually effect such a reformation of the higher boiling point constituents of the hydrocarbon as to produce a resultant hydrocarbon oil having a lower end boiling point. This hydrocarbon can be condensed in the manner hereinabove suggested and preferably in such manner that its contained heat be utilized, as, for example, in preheating the hydrocarbon which has not yet been brought into reactive association with the ore.

From the foregoing that the process of the present invention in- Serial No;

is catalytically quite active 1 below the reduction description it will be seen v.to the reducing sures such an intimate association of a solid reducing agent with an oxide to be reduced that when the treated ore or oxide has been brought temperature a quick and complete reduction will result.

What is claimed as new is:

. 1. That step in the reduction of metallic oxides capable of effecting catalytic decomposition and/or cracking of hydrocarbonsunder certain temperature conditions, which consists in entraining the metallic oxide in a stream of a hydrocarbon, which is in the vapor state and is heated to the temperature at which the metallic oxide will effect catalytic decomposition of at least some of the constituents of the hydrocarbon, said oxide being in a finely divided condition and also heated to the said hydrocarbon decomposition temperature, setting up turbulence in said stream and maintaining the oxide and the hydrocarbon vapor in the-intimate association thus brought about until the particles of the oxide have recei ed the desired deposit therein and thereon of carbon resulting from the catalytic decomposition thus brought about.

2. A process according to claim 1, in which the temperature maintained in the reaction zone is above the decomposition temperature of at least some of the constituents of the hydrocarbon but temperature of the oxide;

3. A process according to claim 1, in which the hydrocarbon vapor is brought into a turbulent state by causing it to flow in a laterally confining, overall speed-determining conduit through successive zones of higher than average velocity and lower than average pressure and of lower than average velocity and higher than average pressure'and in which the oxide, in a finely divided condition, is entrained in the stream of hydrocarbon vapor to partake of the turbulence therein thus created.

4. A processaccording to claim 1, in which a separation of the entrained treated oxide from the reformed hydrocarbon is effected without cooling and the treated oxide is then raised to and maintained at until the oxide is reduced.

GILBERT D. DILL.

the reduction temperature