US2701762A - Integrated cyclic process for producing metallic iron from iron oxidecontaining material - Google Patents

Description

CROWLEY Feb. 8, 1955 2,701,762 INTEGRATED CYCLIC PROCESS FOR PRODUCING METALLIC IRON FROM IRON OxIDE-CONTAINING MATERIAL Filed Sept. 13. 1951 3 Sheets-Sheet. 2

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H. L. CROWLEY Feb. 8, 1955 2,701,762 INTEGRATED CYCLIC PROCESS FOR PRODUCING METALLIC IRON FROM IRON OXIDE-CONTAINING MATERIAL Filed Sept. 15. 1951 5 Sheets-Sheet I5 I N V EN TOR, franz/zy HDD MMWR@ WTEGRATED CYCLIC PROCESS FOR PRODUC- ING METALLIC IRON FROM IRON OXIDE- CONTAINING MATERIAL Henry L. Crowley, South Orange, N. J., assignor, by mesne assignments, to Henry L. Crowley & Company, Inc., West Orange, N. J., a corporation of New Jersey Application September 13, 1951, Serial No. 246,466

8 Claims. (Cl. 75-34) 'Ihe present invention relates to an integrated cyclic process for producing metallic iron from iron oxidecontaining material. More particularly, the present invention relates to a balanced process by which iron oxide-containing material may be processed, without going through the usual blast furnace and open hearth processes for the recovery of iron therefrom, land by resorting to more strictly chemical methods, the process being adapted to raw materials which are leaner or poorer in iron content than those required for use in present commercial ferrous-metallurgy methods.

In the present process for the treatment of iron ores in the blast furnace to make cast iron and subsequently in an open hearth to refine this cast iron to eliminate many of the known impurities thereof, large amounts of heat are required as well as other materials such as limestone in order that the gangue portion of the ore be fluidized and separable as such from the molten iron. As such, these known processes are practically restricted by economic limitations to handling ore having a substantially high iron content, for example, an iron content approaching or exceeding 50%. Such iron ores are used up in the course of time, at least in any given locality, so that that locality is forced to use lower grade ores, which may still be available in abundant supply, but are useful in accordance with conventional processes, only at a considerably higher cost per ton of iron produced. The lower grade ores may, however, provide the raw material for some new and essentially different process. The present invention provides such a new and different process. This new process is practicable when applied to relatively low grade sources of iron, as it operates to lift the iron out of the accompanying non-volatile material or gangue, in a manner which is substantially independent of the relative amounts of iron and gangue in the ore.

Certain of the detailed steps of the present process form the subject matter of separate applications, which will be referred to particularly as the present description proceeds. The present process, however, covers the entire cyclic process, which is so integrated together as to the several steps, re-cycling of some of the materials used, control of the ow of materials from one step to the next, etc. that the process as a whole is practicable, not only from a technical point of View, but also from an economic point of view, to compete successfully with the known process aforesaid in the production of metallic iron.

summarizing the present process, it comprises the steps of introducing an iron oxide-containing material, which may contain FezOa, FesO4 and/or FeO in any desired proportions as between each other and as compared with the total material present (including gangue) and may also contain relatively small amounts of metallic iron, into a chloridizing zone. This material is solid as introduced into the chloridizing zone and remains in the solid phase throughout this zone. 'Ihe chloridizing zone may be constituted by one or more such part zones arranged at different portions of a single piece of equipment, or arranged as a succession of the same or different types of pieces of equipment. In the chloridizing zone, whether this Zone is considered as a single zone or one or more part zones, the solid material aforesaid is brought into contact with a chloridizing gas, which contains as essential ingredients, HC1 and hydrogen. This gas may also contain more or less inert gas, such4 as nited States Patent O ICC nitrogen, and may also (in some' special instances) include some one or more reducing gases, such as carbon monoxide. In any event, the gaseous mixture which is brought into contact with the solid material in the chloridizing zone must include HCl and hydrogen, irrespective of whether or not it includes some one or more other gases.

The next step is to pass the solid material from the chloridizing zone, and at a rate which is preferably adjustably controlled into a vaporizing zone. In this vaporizing zone the temperature is surlciently high so that ferrous chloride is vaporized and in this way is lifted out of the gangue and/or any remaining non-volatile materials. The gases including vaporized ferrous chloride are thus separated from the remaining non-volatile materials in the vaporizing zone; and the non-volatile materials, irrespective of their proportion in the original raw material, may be discarded or used for any other desired purpose, forming no part of the present invention. It is noted that this solid material is never melted during the process thus far described, so that much heat is saved in this respect as compared with prior art processes.

The ferrous chloride vapor from the vaporizing zone is then conducted to a condenser or a condensing zone, wherein sufficient heat is abstracted from it, so that the material condenses to liquid form. It is, of course, possible to condense the ferrous chloride completely to a solid form and thereafter melt it, but this mode of operation is usually not desired by reason of the unnecessary loss of heat involved in the further condensation to solid form and the equivalent amount of heat which must again be introduced into the ferrous chloride to bring it to a molten state. It is desired in accordance with the present invention that the ferrous chloride be introduced into a reducing zone in the liquid state.

A second point or the sole control may be introduced into the cyclic process at this point thereof, in that liquid ferrous chloride may be suitably maintained in a storage tank therefor with suitable heating means and/or heat insulation provisions to the end that the ferrous chloride will remain in the liquid state. The control of the flow of liquid ferrous chloride from the storage reservoir to the reducing zone thus provides an additional or the sole control point for the operation of the process as a Whole.

The ferrous chloride is then introduced into a reducing zone in the liquid state and there brought into contact with a gas or gaseous medium, the essential active ingredient of which is hydrogen. The liquid ferrous chloride and the gas, including or consisting of hydrogen, must be introduced separately into the reducing zone as here-A inafter set forth. The reduction reaction occurs in this zone, resulting in the reduction of a large portion, but usually not all, of the ferrous chloride. The materials resulting from the reaction in the reducing zone consist, therefore, of reduced metallic iron in solid powder form, some unreacted hydrogen, HC1 produced by the reaction, some unreacted FeCl2, and any inert gases which were introduced with the hydrogen, including in most instances some water vapor and possibly some nitrogen. The metallic iron produced may then be separated from the remaining gaseous materials and unreduced ferrous chloride; and the materials other than powdered iron may be recycled in the process.

Two methods of separation of the products of the reducing reaction are included in the present invention. First, there is contemplated a hot separation, that is, one in which all materials, other than powdered iron, are converted into gaseous form, if they are not already in this form, and are separated from the powdered iron by a separation as between gaseous and solid materials. For this purpose, it is necessary to supply suflicient heat to the materials to be separated to vaporize any liquid FeClz present, while at the same time preventing the condensation of any other condensable gases or potentially gaseous materials. The solid iron remains in solid form. This solid iron is then separated by conventional means, for example, means similar to the well known cyclone type separators; and the gaseous materials are preferably recycled through to the chloridizing zone. this hot separation cycle, any ferrous chloride returned to the chloridizing zone with the recycled gases asaforesaid will be condensed in that zone due to the lower temperatures maintained therein, and thereafter will be recycled in the process. Any excess hydrogen included in the gases being recycled from the reducing zone will also pass through the chloridizing zone and may there be used to some extent in reducing any trivalent iron to bivalent iron. The HCl content in these recycled gases will be used in the chloridizing zone to convert the iron therein to ferrous chloride.

In the cold separation phase of the process, the products from the reducing zone will be cooled to the point where not only metallic iron, but also any remaining ferrous chloride will condense out in solid form. There will then be a separation effected between solid materials resulting from this condensation and gaseous materials, particularly including hydrogen and HCl, and possibly also including any inert gases which may be present. It is preferable, even under these circumstances, that the temperature of the gases be kept sufficiently high, so that any water vapor present therein will not con dense out. The gaseous material resulting from this separation may then be returned to the chloridizing zone to react in that Zone in the same way as described in connection with the hot separation cycle. The solid materials resulting from this cold condensation of the products from the reducing zone may then be separated from each other, for example, by leaching out the ferrous chloride from the iron by use of a suitable solvent, followed by evaporation or other separation as between solid iron and the solution of ferrous chloride. In the event that some organic solvent is used to dissolve the ferrous chloride at this stage of the process, a suitable solvent recovery system is contemplated for use, so that the solvent may be recycled in the process and the ferrous chloride discharged for such use as may be desired therefor, or, alternatively returned to the cycle, for example, to the chloridizing zone or to the vaporizing zone.

The objects of the invention will be apparent from the foregoing. While the principal features of the invention have been outlined above, these features will be brought out in greater detail in the following description of some preferred embodiments of the invention, which are illustrated in the accompanying drawings, in which:

Figure 1 is a diagrammatic representation, with certain parts in section, of apparatus for carrying out the process of this invention using the hot separation phase of the process aforesaid;

Fig. 2 is a similar View of apparatus for the entire cycle adapted for the cold separation phase of the process;

Fig. 3 is a foreshortened view, with parts principallyy in central section, illustrating a device which can be used to provide a chlordizing zone or part zone;

Fig. 4 is a fragmentary view, principally in transverse vertical section taken on the line 4 4 of Fig. 3;

Fig. 5 is a view, principally in central vertical section and somewhat diagrammatic, illustrating an apparatus usable to provide a vaporizing zone for the process; and

Fig. 6 is a diagrammatic view of apparatus usable to provide a reducing zone for the process.

In considering the particular process contemplated in accordance with the present invention, the` first point to consider is the composition of the raw material supplied to the process. This material is herein described generally as an iron oxide-containing material. The iron oxide content of this material may be in any one or more of the forms FezOa, Fe304 or FeO. There may also be present relatively small amounts of metallic iron. The remainder of the material may be of any desired composition, so long as this composition does not substantially interfere with any of the processes contemplated for use in accordance with the present invention. Such other material may, therefore, be earthy or rock-type material, such as silica, which is completely inert. This other solid material may also include, for example, oxides of one or more other metals, such as calcium or magnesium, which could react with the HCl in the chloridizing zone to form the corresponding chlorides, but wherein the chlorides would not be volatilizedv in the vaporizing zone along with the ferrous chloride, but would pass out in the gangue and non-volatiles. It is further contemplated, that if desired, an original rawmaterial or ore could be pre-treated in some way, for` Iny 4 example, for reducing the iron content thereof to a ferrous state with carbon monoxide, so that the iron oxidecontaining material as supplied to the present process may include a part or all the iron in ferrous form.

The raw material supplied to the process of the present invention should preferably be sufliciently comminuted so that a desired intimate gas-to-solid contact reaction can take place without having some of the iron oxide or iron physically protected from contact with the gases by surrounding solid material. For this purpose, it is preferred to comminute the raw material in any suitable way tol a particle size, probably about 48 to 50 mesh or smaller. Itis also preferred to have the raw ma-terial substantially dryv as it is supplied to the chloridizing zone in order to facilitate proper handling of the solid material' and to avoid the expenditure of any heat which otherwise might have to be used in evaporating water therefrom.

As shown in Figs. 1 and 2 of the accompanying drawings, this iron oxide-containing material is supplied in any suitable way, forming no part of the present invention, to a suitable supply hopper 10. From this hopper the material is supplied at a desired and preferably controllable rate into a chloridizing zone here generally indicated as comprising a first chloridizer 11. The supply of this raw material may be effected in any suitable way. As shown, thel material from the hopper 1t) may discharge by gravity into a screw conveyor housing 12, in which is arranged a helical screw feed member 13, driven by a variable speed motor 14 or other suitable source of power, the speed of which is preferably controllable. From the housing 12, the raw material may then pass through a passage means generally indicated at 15 under control of a suitable means such as a star valve 16 to prevent the outow of gases from the chloridizing zone through the solid material input passage means 15 and 12. If desired, means may be provided to purge the-incoming solid material of included air or oxygen-containing gases, as by passing through some selected part of the solid material feeding system above described an inert purging gas, such as nitrogen. This will prevent the formation of a combustible gaseous mixture in the chloridizing zone due to the presence of hydrogen in this zone as hereinafter particularly set forth. The means. by which thiszpurging of the solid material is effected. arev not particularlyshown, as any suitable means may be used for this purpose.

In bothFigs. l and 2 of the accompanying drawings, theV chloridizing zoney consists of two chloridizers, the rst of which is shown at 11 and the second of which is. shown at 17. The chloridizing Zone may generally be comprised by one` or more independent pieces of apparatus with provision for moving the solid material therethrough andv preferably with independent control for the temperatures at different portions thereof, although tlie last is not absolutely essential.

As shown in Figs. l and 2, the chloridizers 11 and 17` are substantially identical. Again, this is not essential as the same or different types of apparatus may be used in any desired sequence and mayy collectively constitute a chloridizing zone. As shown in these two iig ures, the solid material from the first chloridizer 11' is passed through a suitable passage 18 to a screw feed chamber 19 provided with a helical feed member 2) driven by a` suitable prime mover, such as a variable speed motor 21.

In each of the chloridizers 11 and 17, there is illustrated a substantially helical material feeding and agitating meansv 22, each of which is driven by a suitable prime mover, again illustrated as a variable speed motor 23. Surrounding each of the chloridizers 17 and 22 is a temperature controlling jacket 24 through which a temperature controlling fluid may be passed for controlling the temperatures in the different portions of the chloridizing zone. Each jacket 24 is provided with inlet and outlet passages 25 and 26.

In starting up the apparatus, it is necessary to bring up the temperature of the solid material in the chloridizingy zone byy the addition'of heat to this zone. l'n some instances, however, after the chloridizing operation is progressing in a continuous manner, no further heat ad dition is necessary as the chloridizing reaction is excthermic, and in some cases, some heat may have to be withdrawn and dissipated. This may be done by suitablecontrol ofthe rfluid circulated through the jackets 24.

The temperatures to be maintained in the various portions of the chloridizing zone are generally from about 500 F. to about 1200 F. ln some cases, it may be desired to operate with a progressively increasing temperature gradient, following the teachings of the Graham et al. application, Ser. No. 127,428, led November 15, 1949, now Patent No. 2,665,191, issued Jan. 5, 1954. In other instances, it may be desired to carry on the chloridizing at a substantially constant temperature.

In general, the rate of the chloridizing reaction is increased with higher temperatures, although the equilibrium to which this reaction proceeds may be more desirable under one set of temperature conditions than under another, as particularly discussed in the Graham et al. Patent No. 2,665,191 aforesaid. ln a preferred embodiment of the invention which follows the cycle set forth in the Graham et al. application aforesaid, the temperatures for the solid material are progressively raised during its passage through the chloridizing zone starting, for example, with a temperature in the range from about 500 F. to about 800 F. in the first chloridizer ll, and rising to temperatures in the range of about 800 E. to about 1200D F. in the second or last chloridizer 117. This may advantageously be effected by passing heated gases into the jackets 24 of each chloridizer adjacent to the exit end thereof and exhausting such gases from the jackets adjacent to the ends of the chloridizers through which the solid material enters. These gases may be controlled as to their temperature at or before they are introduced into the jackets 24 and may, if desired, be further controlled, for example, by diluting them with air from the atmosphere at one or more selected points along the jackets, in a manner not shown, but which will be obvious to those skilled in the art from this description.

Each or either of the chloridizers 11 and 17 may, for example, be substituted by a device constructed as particularly illustrated in Figs. 3 and 4. ln these figures there is shown a substantially cylindrical housing 27, which is provided at its ends with suitable bearing means means (not shown), in which is journalled a central rorating shaft 28. The shaft 28 may also be journalled in a suitable bearing 29 mounted on a rigid structure adjacent to but outside the chloridizer. The shaft 28 is provided with a plurality of spiders 30 supporting substantially longitudinal extending blades 31. lf desired, the blades 3l may be given a helical form, so as to assist in feeding the solid material from the entrance end portion of the chloridizer to the exit end portion thereof. downwardly to some extent from the inlet end toward the delivery end for the solid material, so that the agitation of this material by longitudinal blades Without a helical twist to the blades 31 may be effective in conjunction with gravity to move the solid material from the inlet to the outlet end of the housing 27. Surrounding the housing 27 is shown a substantially cylindrical jacket 32, which is provided in a manner not particularly illustrated with inlet and outlet means, through which a heated fluid, such as products of combustion, may be circulated for controlling and maintaining the temperatures of the materials within the housing 27.

While there is illustrated and described in a general way two more or less similar types of equipment which may be used to provide a chloridizing zone, it will be understood that other gas-to-solid contact equipment capable of withstanding the chemical effect of HC1 gas, the erosive eect of the solid material flowing therethrough, and the temperatures involved as aforesaid, may be used in lieu of either or both types of equipment herein illustrated and particularly described.

in the chloridizing zone, the solid material is brought into contact with a gaseous mixture, the essential active ingredients or" which are HCl and hydrogen. The other gases which may be present in this mixture include inert gases such as nitrogen, and under certain special circumstances some carbon monoxide, as has been discussed hereinabove in the general summary of the invention. For the purposes of the present application, only two gases are essential as constituents in the chloridizing zone, namely, HC1 and hydrogen.

In the chloridizing zone, iron in oxide form as FeO may be converted to ferrous chloride; and further if the iron is introduced into the chloridizing zone in a trivalent condition as Fe2O3, it must also be reduced to a bivalent Alternatively, the housing 27 may be inclined 6 condition. In the event that some or all the iron is introduced as trivalent iron oxide such as FezOa or FesOi, then the reduction of the iron to a bivalent condition preferably takes place substantially simultaneously with the chloridizing thereof, or immediately prior to such chloridizing as to any particular portion of the iron. This also is discussed to a substantial extent in the Graham et al. Patent No. 2,665,191 aforesaid. lA relatively small amount of iron introduced into the chloridizing zone in metallic form and any metallic iron formed therein by reduction of any of the iron oxides by the reducing gas present (as hydrogen) may be converted to ferrous chloride by reaction with the HCl present in the gases. In the event that reduction of the iron is required, hydrogen is present to effect such reduction. The HC1 is present to effect a conversion of the iron to ferrous chloride. ln the usual case, it is contemplated that the gases supplied to the chloridizing zone will pass therethrough in a direction substantially countercurrent to the flow of solid material through this zone. Here again, this is not essential, but is usually desirable and is the process illustrated in the drawings, Figs. 1 and 2.

The constituents of the entering gas, which have been described aforesaid as to their essential ingredients, may now be described as to proportions. In these gases there should be about 2% to about 35% HCl based on the total of hydrogen and HCl. A preferred range of HC1 concentration is restricted to the narrower limits of about 5% to about 25% on the same basis. There may, in addition, be more or less diluent gases, the proportions of which to the combined hydrogen and HC1 total is not particularly critical as long as there is suiiicient HC1 brought into contact with the solid material to chloridize the amount of iron which it is desired to chloridize. Usually, this will be all the iron content of the raw material, even though in some instances all this iron may not be 100% chloridized in practice.

There are several ways in which the chloridizing step of the process may be operated. If it is desired to use up all the HCl in the gases, so that the gases leaving the chloridzing Zonewill contain substantially no HC1, then the rate of supply of the solid material supplied to the chloridizing zone may be maintained high in respect to the amount of gases passing therethrough and particularly the HC1 content thereof. Under these circumstances, the HC1 efliciency of the entire process may be kept at a maximum, even though at the cost of losing some iron, which Willbe discharged with the gangue, usually as unchloridized iron oxide, but possibly including some metallic iron reduced from the oxide by the hydrogen present in the gases.

On the other hand, if it is desired to operate the process so as to recover the maximum amount of iron, while possibly losing some HCl, then the amount of raw material will be relatively less in respect to the rate of supply of HC1 in the gases to the chloridizing zone. In this way, little or none of the iron will be lost in the gangue, although the gases leaving the chloridizing zone may have some substantial HC1 content. It is contemplated that some compromise between these two extremes of operation may be preferred as by using a plurality of chloridizers such as 11 and 17 as shown in Figs. 1 and 2 with a substantially countercurrent flow of solid material and gases. In this Way it is possible to use up almost all the HCI while converting almost all the iron to ferrous chloride.

It is further contemplated that more than two individual chloridizers could be used if desired. Under such circumstances, for example, three or more units could be provided with appropriate piping connections and material handling connections, so arranged that some one, or any one chloridizer, could be by-passed for inspection or repair while using the remaining chloridizers. For example, if a third chloridizer were used, it could be operated in a temperature range of about 1000 F. to about 1200 F. following the two chloridizers shown in the drawings, the third chloridizer being connected to the second chloridizer 17 in the same way that that chloridizer is connected to the first chloridizer 11. Under such circumstances, HCl concentrations in the entering gases should be relatively high in order that the hydrogen present in this gas will not serve to reduce the ferrous chloride formed to metallic iron, which is undesired at this stage of the process. If under these circumstances, there is suflicient HCl present in the gases, any metallic iron,'which may have been formed in the earlier portions of the chioridizing zone, may be converted to ferrous chloride.

Thus, in general, the first chloridizer 11 or the iirst portion of the chloridizing zone from the point of view of solid material may be said to be elfective to remove the last portions of the HC1 content of the gases by providing an ample amount of unchloridized iron oxide; the second or central section of the chloridizing zone is effective for such reduction as may be necessary and chloridization in a relatively rapid manner; While the last portion of the chloridizing zone or a third chloridizer, if such a third chloridizer be provided, is usable to obtain a relatively high yield of FeClz from the iron present by contacting the solid material with a gas having a relatively high percentage of HC1, and also for chloridizing any metallic iron formed by reduction of a compound of iron in any previous portion of the chloridizing zone to form FeClz.

The solid material from the chloridizing zone is then supplied through to a suitable storage point indicated in Figs. l and 2 as a hopper 33. This is shown only diagrammatically in these figures; although in practice the solid material will be moved by gravity or by the use of suitable conveyor means from the chloridizing zone into the hopper 33. Suitable means, such as a star valve 34,

may be provided for preventing gases from the chloridizing zone passing into the hopper 33.

While the chloridized material is in the hopper 33, suitable means (not shown) may be provided for purging therefrom any hydrogen in the solid material, so that when the ferrous chloride is vaporized from the solid material in the vaporizing zone, there will be no hydrogen present to react with the ferrous chloride vapor in this zone. This purging is normally eifected by the use of an inert gas, such as nitrogen.

The next principal operation in the process is the vaporizing of the ferrous chloride to lift it out of the non-volatile material, including any gangue, which may have been present in the original raw material, and any non-chloridized oxides of iron.

As shown in Figs. 1 and 2, the material is supplied by gravity from the hopper 33 through a feeding means 35 to a vaporizer 36. The feeding means 35 may be provided as shown with a helical screw feeding device 37, which may be driven by a variable speed source of power, such as a variable speed motor 38. The solid material may pass from the feeding device 35 by gravity into the left hand end, as seen in Figs. l and 2, of a tubular member 39, and be moved through this tubular member by any suitable means such as a ram 40, driven by any suit- I able source of power (not shown) in a manner which will now be obvious to those skilled in the art. In the diagrammatic showing of the vaporizer 36 in Figs. l and 2, there is illustrated a jacket 41 surrounding the tubular member 39 and provided with inlet and outlet passages 42 and 43 for a heating fluid such, for example, as hot products of combustion. Alternatively, any suitable and available source of heat may be provided for the vaporizing zone, which in this instance, comprises the tube 39.

In Fig. 5 there is shown a tubular member 44 located in a furnace generally indicated at 45. Heat may be supplied to` the furnace by combustion therein. For this purpose there is illustrated a plurality of fuel burners 46 supplied from a common supply line 47, products of cornbustion leaving the furnace through a stack 48. The material may be moved through the vaporizing zone by a ram 40, which is reciprocated in a conventional manner by any suitable means (not shown). Solid materials may be supplied to the tube 44 through a passage 49. Ferrous chloride vapor may leave the tube 44 through a means indicated at 50 and pass thence to a condenser or condensing zone hereinafter described. Solid material from which the volatile portions have been vaporized may pass through to the right hand end of the tube 44, as seen in Fig. 5, and move by gravity through a passage 51, which may be provided with means for permitting the removal of this solid material without introducing any diluent gas or permitting the escape of gas from the vaporizer. Such means in the present instance comprises a portion of the passage means S1 provided with spaced apart valves 52 and 53. The solid material may then be taken to any suitable disposal point and used for any desired purpose for which it is adaptable.

While it is contemplated that ferrous chloride could be distilled out of solid material by a simple distillation op erationy and thereby be lifted away from this solid material, it may be desired to pass a carrier or sweep gas through the vaporizing zone. Such a gas will normally be an inert gas, as nitrogen, and will be supplied through the vaporizing zone in a manner more particularly hereinafter described. Due to the partial pressure of this carrier gas, the vaporization point temperature of the ferrous chloride will be somewhat less than it would otherwise be. Thus, there is attained a minimum heat supply requirement for the vaporizing zone by reason of the lower temperature required to be maintained in this zone. This will result in corresponding savings in various parts of the process as will be obvious to those skilled in the art.

The ferrous chloride vapor passing from the vaporizing zone is preferably puried in any suitable manner to remove therefrom any entrained solid particles. The means for accomplishing this purpose are not shown in the drawings as such means are substantially conventional whenever relatively pure gases are required. This means may, therefore, take the form of one or more conventional ltering means.

As it is the purpose of the present application to effect the reduction of the ferrous chloride in the liquid phase, the next operation which must take place is the condensation of the ferrous chloride vapor to ferrous chloride liquid. ln this Way, the present application distinguishes from my copending application, Ser. No. 224,770 filed May 5, 1951 and having the same title as the present application, which is restricted to vapor phase reduction as distinguished from liquid phase reduction, to which the present application is limited. The gases may pass, as shown in both Figs. l and 2, through a suitable passage means S4 to a condenser or condensing zone 55. This condenser may be supplied with suitable heat absorbing duid, passing into and out of the condenser through suitable passages 56 and 57 in a conventional manner. As shown, the condenser 55 may be constructed in a manner similar to a waste-heat boiler with the heat removed therefrom, for example, in the form of low pressure steam, which may be used as process steam at any place where such steam is desirable. Condensed liquid ferrous chloride may pass from thc condenser or the condensing zone 55 through a passage 53 to a ferrous chloride liquid storage chamber generally indicated at 59. Suitable means may be provided in conjunction with this storage chamber for maintaining this ferrous chloride in liquid form and at a temperature at which it is desired to be used in the reducing Zone portion of the process.

As set forth above, it may be desired to use a sweep gas passing through the vaporizing zone, shown as the vaporizer 36. Any inert gas may be used for this purpose. Nitrogen is a desired inert gas for use in this respect. As shown, there is a cycle for the recirculation of this nitrogen or inert gas, including a passage or conduit 60, and a conduit 61 communicating therewith. A suitable pump 62 may be inserted for insuring the circulation of the inert gas. The conduit 60 communicates with the tube 39 of the vaporizer 36. The inert gas ilows from the vaporizer along with the vaporized ferrous chloride through the passage means 5'4, thence from the condenser 55 with the liquid ferrous chloride to the liquid storage chamber 59. At this point, the gas may be separated from the liquid and pass out of the chamber 59 from the space above the liquid therein through the pipe 61 to be recirculated by the pump 62. Any make-up nitrogen, or other inert gas, required to compensate for leakage losses or otherwise, may be introduced into the cycle through a suitable branch pipe 63 under control of a valve 64.

The liquid ferrous chloride from the chamber 59 is conducted under control of a valve 65 to a reducing zone and is there reduced by the use of a reducing gas, which has as its active reducing ingredient, hydrogen. This reduction reaction and the apparatus in which it is effected is disclosed in greater detail in the copending application of Darner et al., Serial No. 188,128, led October 3, 1950, now Patent No. 2,664,352, issued Dec. 29, 1953, and entitled Process and Apparatus for Reducing Ferrous Chloride in Liquid Form to Elemental Iron. The nozzle through which ferrous chloride may be introduced into the reducing zone may further be that particularly illustrated and described in the copending application of Walters, Serial No. 190,520, iled October 17, 1950, now Patent No. 2,645,527, issued July 14, 1953,

and entitled Nozzle Construction. In general, however, liquid ferrous chloride is introduced into the reducing zone, here shown diagrammatically as an apparatus 66, through a suitable nozzle; and hydrogen is separately introduced into the reducing zone. In a preferred embodiment of the invention, as particularly disclosed in the Darner et al. application aforesaid, premature contact between the liquid ferrous chloride and the hydrogen is prevented by the use of a shielding gas, which may be an inert gas such as nitrogen. The use of the process of Darner et al. and the apparatus particularly disclosed therein is to be considered within the purview of the present invention. The present invention may also employ the nozzle construction particularly illustrated and described in the Walters application aforesaid.

In general, the reducing reaction is carried on to a substantial extent, but rarely to 100% completion, notwithstanding the normal use of an excess amount of hydrogen over and above the stoichiometric equivalent of the ferrous chloride supplied to the reducing zone. As a result, there will be produced in the reducing zone as products of the reduction reaction therein, a substantial amount of solid powdered iron, and some ferrous chloride which has not been reduced because the reaction tends to proceed to an intermediate equilibrium rather than going to 100% completion. There will also remain in the gases, a substantial amount of hydrogen, which has not reacted with ferrous chloride and the hydrogen supplied in excess of that necessary for reaction, also any nitrogen or other inert gas supplied to the process along with the hydrogen, plus such gas supplied as a shielding gas to prevent premature contact between hydrogen and ferrous chloride aforesaid, HC1 produced as a product of the process of reducing the ferrous chloride with hydrogen, and possibly some additional inert gas as water vapor. All these materials pass from the reducer 66 or reducing zone through a suitable passage indicated at 67 to a separator hereinafter described.

In Fig. 6, there is illustrated in slightly greater detail an apparatus which can be used for the apparatus shown generally in Figs. l and 2 at 66. Referring now to Fig. 6, there is illustrated a substantially vertically disposed cylindrical chamber provided in a hollow cylindrical member 68. Liquid ferrous chloride may be supplied to this chamber through a conduit 69 corresponding to the valved passage shown in Figs. l and 2, and including the valve 65. The reducing gas, including or consisting of hydrogen, may be supplied to the chamber forming member 68 through a conduit 70; and products of the reaction may be removed from the chamber forming member 68 through a passage or conduit 71. In order that the materials within the reducing zone, i. e. within the chamber forming member 68, may be maintained at a desired temperature, and particularly for preventing heat loss through the walls of this chamber, the entire chamber may, if desired, be enclosed within a suitable furnace 72, to which heat may be supplied by a plurality of fluid fuel burners 73 of any usual or desired type. The supply of fluid fuel to these burners may be from a single pipe 713 under control of a suitable valve 75. The products of combustion may pass from the furnace through a suitable stack under control of a damper therein as shown.

The products resulting from the reaction in the reducing zone may then be treated in either of two ways: (a) by hot separation in accordance with the cycle illustrated in Fig. l; or (b) by cold separation in accordance with the cycle illustrated in Fig. 2. In either case, the iron produced is eventually separated from the other products and is the principal product of the entire process.

Turning now to the Fig. l form of the invention including hot separation, the products resulting from the reaction in the reducer or reducing zone are introduced as aforesaid into a separator 76. This separator may take any desired form, the details of which are per se no part of the present invention.

In the present instance, however, when hot separation is to be carried on, a different type of separator is required from that disclosed in my copending application, Serial No. 224,770 aforesaid, in that there is required to be supplied sufcient heat, so as to vaporize any ferrous chloride which may pass into the separator 76 in either liquid or solid form. For this purpose the separator may include a heating chamber which may take the form of an annular jacket or a series of tubes, or both, and through which` a heating fluid is supplied from a suitable source thereof, for example, through an inlet 77 and an outlet 78. Once the ferrous chloride is Vaporized, the only solid material left will be the metallic iron powder produced, which may be separated from the other materials, all of which are gaseous, by any suitable method, for example, that employed in conventional cyclone separators.

The metallic iron produced is collected in the conical lower portion of the separator 76 and may be removed therefrom through a passage 79 having spaced valves 80 therein. As the separation is effected while the gases are hot, any ferrous chloride passing to the separator 76 in any physical state, will pass therefrom as a gas, mixed with unreacted hydrogen and with the HCl produced by the reaction in the reducing zone. In addition to this, there may be inert gases, such as nitrogen, which may be supplied as aforesaid into the reducing zone. These gases then pass through a passage 81 into the last stage or portion of the chloridizing zone here shown as the chloridizer 17. in the preferred form of the present invention, the chloridizing gases are those derived from the separation of the solid material following the reducing action in the reducing zone. Means (not shown) are preferably provided for retaining these gases hot, so that heat loss is minimized and so that condensation of ferrous chloride in the lines is effectively prevented. This also serves as a method of introducing a substantial amount of heat into the chloridizing zone. In the chloridizing zone, due to the lower temperatures therein in respect to those in the reducing zone, any ferrous chloride present will be condensed, so as to pass out of the chloridizing zone as a solid along with ferrous chloride produced in that Zone. The remaining gases will supply the gases required to be present in the chloridizing zone as aforesaid. In the event that it is necessary to supply additional HCl to the cycle, this gas may be supplied from any suitable source thereof to the gases passing between the separator and the chloridizing zone, i. e., to the passage 81. Such make-up HCl may be introduced through a pipe 82 connected to the pipe 3l and provided with a suitable valve (as shown).

In completing the cycle, the only portion thereof which has not been fully explained is the disposition of gases leaving the chloridizing zone. These gases will contain some hydrogen, which has not been used in reducing iron oxide and which it is desired to recirculate, water vapor produced in the chioridizing zone by the reaction between hydrogen and iron oxide and between HC1 and iron oxide, and also any water vapor introduced as moisture in the raw material, and any unreacted HCl. There may also be present more or less inert gas. These mixed gases are then preferably cooled and scrubbed in a suitable scrubbing device generally indicated at 83. For this purpose, these gases may be passed through a spray chamber through which cold water is supplied through a passage 34. The function of this scrubbing device is to condense out a large portion of the water vapor, and also to remove from the gas substantially all the HCl, which will pass out of the scrubber in the waste water as an HCl solution. This waste water including the dissolved HCl passes out, as shown, through a pipe 85. If the concentration of HC1 in this waste water were suficiently high, it could be recovered therefrom by means known to the art and which per se form no part of the present invention. The gases leaving the scrubbing device 83 pass through a pipe S6 en route to the reducing zone.

As an inert gas, such as nitrogen, is supplied to the rcducing zone as aforesaid, it is necessary to bleed out and waste some of the recirculating gases, so as to prevent the building up of the concentration of the inert gas in the recirculating gases to an undesired high value. This bleeding of gases may be done either before or after passing the gases through the scrubbing device 83. In the event that it is desired to recover HC1 from the gases, this bleed out point is preferably located after the scrubbing device. However, it is normally the desired practice to use a maximum of the HCl in the chloridizing zone, so that the amount thereof in the gases leaving this zone is quite small and a bleeding of excess gases in advance of the scrubbing device may be effected, Under these conditions, the small loss of HC1 in the gases bled out of the recirculation is compensated for by the smaller total amount of gases which remain to be treated in the scrubbing device S3. As shown, a branch pipe S7 is provided, ow through which is controlled by a valve 88, the gases being discharged to the atmosphere or disposed of in any desired manner.

source of hydrogen (not shown) to the pipe $6 and provided with a suitable valve 91, by which the hydrogen being supplied to the system may be controlled. in order to determine and control the ow of gas and particularly the rate of supply of hydrogen to the reducing zone, a

iiow meter generally indicated at 92 is preferably interposed in the pipe 86 between the make-up hydrogen branch pipe 90 and the reducer 66. The pipe 36 leads to the reducer as shown in Figs. l and 2 and communicates with the pipe 70 shown in Fig. 6, if that form of the reducer is employed.

Turning now to the Fig. 2 form of the invention in which cold separation is employed, effective on the products leaving the reducing zone, such products are shown passing from the reducer 66 through a pipe 67 to a cold separator 93, in which these gases are cooled at least to a temperature such that any ferrous chloride present will be condensed to solid form. For this purpose, the separator 93 may be formed in a manner similar to the separator 76 except that a cooling medium may be passed through an inlet 94 and an outlet 95 thereof, so as to effect the desired solidication of any ferrous chloride supplied to this separator. Thus, both the iron and the ferrous chloride will be solid in the separator 93 and may be separated therein from the remaining gases. The remaining gases may then pass through the pipe 81 to the chloridizing zone as described in connection with the Fig. l form of the invention, being augmented as may be necessary by malte-up HCl through the branch pipe 82 under control of the valve therein.

Solid materials from the separator 93, which consists essentially of metallic iron and uureduced ferrous chloride, may then be passed from the separator under suitable control (not shown) to a recovery system, by which the iron may be separated from the ferrous chloride, so that both may be used as desired. One such system is indicated diagrammatically in Fig. 2 as including a leaching bath 96, in which the ferrous chloride may be dis solved in a suitable solvent. This solvent may be water, with suitable provisions being made to prevent undesired rusting of the iron. The undissolved iron may then be separated from the solution of ferrous chloride in a suitable separating means, such as a filter 97, and the iron passed to a suitable point where it may be used. The solution may then be evaporated to leave the ferrous chloride, which may be used for any desired purpose, includ* ing admixing it with the raw material introduced into the chloridizing zone, so that it may thus be returned to the process. Alternatively, this ferrous chloride may be used for any other purpose for which it is adapted. ln the event that some relatively expensive solvent is used in the leaching bath 96, such as one or more of the organic solvents, it may be desired to save the solvent and recycle it to the leaching bath through a passage 93 in which a pump 99 is interposed. The details of this leaching and solvent extraction process form per se no part of the present invention and may be replaced by equivalent apparatus of any desired type. With this exception, the cycle illustrated in Fig. 2 may be essentially the same as in Fig. l, so that the various common elements are indicated by the same reference characters.

The cycle as to some of the materials employed, which has been explained in considerable detail as to the several apparatus elements used in the process, must be coordinated together in practice, so that there will be a balance effected throughout all the operations.

The process is preferably primarily controlled by controlling the rate of supply of liquid ferrous chloride to the reducer 66 from the supply or storage chamber 59. In this respect, the present process differs somewhat from the process of my copending application, Ser. No. 224,770. ln view of the control being effected at this point, it is no longer necessary that there be a storage means provided as shown by the hopper 33, or equivalent storage point for the solid chloridized material; but this material could be fed directly from the chloridizer 17 to the vaporizer 36. In any event, the operation of vaporization of the chloridizing zone.

the ferrous chloride is necessary to be accomplished only at such a rate as to provide an ample supply of liquid ferrous chloride in the chamber S9. Thus, the vaporizer is normally operated at the same rate as that at which the raw material used is chloridized, so that the storage chamber or hopper 33 is useful only by reason of convenience in material handling and is not a necessary storage point in the process. As in my copending application, it is preferred to use a flash type of vaporizing in the vaporizer 36, so that the vaporization may proceed at the saine rate that chloridized material is supplied to the vaporizer.

if then the rate of supply of hydrogen to the reducing zone is carefully controlled by controlling the amount of make-up hydrogen admitted through the pipe 90 by the valve 91, with the rate of supply of the gases indicated by the reading of the flow meter 92, the reaction within the reducing zone may be carefully and properly controlled. This, in turn, will control the amount of HCl produced in the reducing zone. This amount of HC1, coupled with the amount of make-up HC1 introduced into the system through the pipe 82. under control of the valve therein, will control the amount of HCl introduced into This amount of HCl can then be balanced by the amount of raw material supplied to the chloridizing zone under control of the variable speed motor 14. Thus, there is required in the entire system to assure a balance throughout, only one intermediate storage point, namely, the storage chamber 59 for the liquid ferrous chloride. With this one storage point, it is possible to effect accurate control of all the elements of the system and of the recirculations therein.

Another interlocking arrangement in the process, which is necessary to be provided in order that the process as a whole shall be effective, is in connection with the hot separation cycle disclosed in Fig. l. lf the gases passing from the separator through the pipe 8l to the chloridizing zone are at a temperature higher than about l250 F., ferrous chloride contained as a vapor in these gases may tend to condense as a liquid in the chloridizing zone, rather than as a solid; and also these highly heated gases will tend to melt the ferrous chloride produced in the chloridizing zone upon their initial contact therewith. Any molten ferrous chloride in the chloridizing zone will tend to agglomerate with the rest of the solid materials in this zone and will prevent a desired, substantially free flow of these materials through the chloridizing zone. This will also result in hindering chloridization by mechanically masking the unchloridized material and preventing contact between it and the chloridizing gases. As a result and in order to avoid all these diiculties, it is practically necessary that the gases being supplied to the chloridizing zone be at a temperature below about l250 F., and preferably, in order to conserve heat, be almost up to this temperature, such as about l200 F. Under these circumstances, due to the partial pressures of the other gases present, ferrous chloride will not condense out in the pipe 81, but will condense out in the chloridizer as a solid, rather than as a liquid.

There follows examples illustrative of the various conditions under which the process of the invention may be practiced and of the interrelation of the several steps of the process. In these examples7 the quantities given throughout are based on the production of one ton of iron powder in order that there may be a uniform basis for comparison of the various conditions as set forth.

Example I This example illustrates the conditions under which the process is practiced when the reduction step is carried out in such a manner as to produce an exhaust gas, used directly and as such for chloridizing and containing a relatively low HCl content, i. e., about 2% by volume.

For each ton of iron powder produced, 8800 lbs. of Tobin Formation ore are fed into the chloridizing zone. This ore has the following average analysis:

Per cent Ignition loss 4.1 Gangue 49.3 FesOs 46.6

The ore is fed into the cold end of the chloridizing zone at a temperature of about 300 F. to prevent condensation of water vapor and HCl in the vapor. The ore moves through the chloridizing zone countercurrent to the stream of chloridizing gas and is gradually raised in temperature to about 900 F. Because of the relatively high percentage of hydrogen in the chloridizing gas, it is necessary to keep the temperature of the solid material in the chloridizer below about 950 F. in order to prevent reduction of the FeClz formed to metallic iron at this time.

The chloridizing gas which is recycled directly from the reducing zone, has a composition of about 0.5% FeClz vapor (based upon hot separation as described in connection with Fig. 1), 48.5% H2, 1.0% HC1 and 50% N2 all by volume. Since one-half of the volume of this chloridizing gas consists of inert nitrogen, it can be considered that HCl makes up about 2% by volume of the active chloridizing gas entering the chloridizing zone. For each ton of iron produced the amounts of gas entering the chloridizing zone are: 460 lbs. FeClz, 2900 lbs. HC1, 6900 lbs. H2 and 101,000 lbs. N2. This includes about 265 lbs. make up HC1.

During its passage through the chloridizing zone the Fe2Os in the ore is chloridized to the extent of about 70%, thus producing 10,140 lbs. of chloridized ore per ton of iron produced. This chloridized ore, together with about 460 lbs. FeClz, which has condensed from the chloridizing gas in the chloridizing zone, is passed to a vaporizing zone, where the temperature is raised to about 1750 F. In order to accomplish this vaporization, a stream of nitrogen is passed through the vaporizing zone which may be at the rate of about 1110 lbs. of nitrogen per ton of powdered iron produced. By this operation 5,020 lbs. of FeClz vapor are produced and there is left in the vaporization zone 5,120 lbs. of gangue to be discharged. This FeClz vapor is then passed to a condenser where it is cooled to a temperature of about l300 F. and thereby condensed to a liquid. From the condenser the FeClz liquid is passed to a storage tank and the nitrogen is drawn oif from the space above the liquid and recycled into the vaporizer.

ln the chloridizing zone, the gas stream loses over 90% of its HC1 and some of its hydrogen content, while picking up water vapor from the moisture content of the ore and from the products of the reduction and chloridizing reactions. The resulting exhaust gas from the chloridizing zone contains, per ton of iron produced, about 265 lbs. of HC1, 1,020 lbs. water vapor, 6,900 lbs. of H2 and 101,000 lbs. of nitrogen. A portion of this gas is then bled out of the system amounting, on the basis of each ton of powdered iron produced, to about 1.5 lbs. of HCl, 7.5 lbs. of water vapor, 37.5 lbs. of hydrogen and 550 lbs. of nitrogen. The gas stream from which this exhaust gas has been taken is then passed through a scrubbing zone, wherein substantially all of the HCl and water vapor content are removed, leaving a substantially dry gas con sisting, per ton of powdered iron produced, of about 100,450 lbs. of nitrogen and 6,850 lbs. of hydrogen. To this gaseous stream, about 152 lbs. of make-up hydrogen are added and the resultant mixture passed into the reducing zone. This gas contains about 25% nitrogen and 48% hydrogen by Volume. When the FeClz liquid is introduced into the reducing zone in the amount stated vso y14 reduction of the FeClz formed to metallic iron at this point, since the hydrogen content of the chloridizing gas is still relatively high. l

The chloridizing gas leaving the reducing zone has a composition of about 0.7% FeClz, 2.5% of HC1, 46.8% of hydrogen and of nitrogen, all by volume. Thus with respect to the active ingredients, the HC1 represents about 5% of the total volume. For each ton of iron produced, the weights of the several gases entering the chloridizing zone are: 270 lbs. FeClz, 2,750 lbs. of HC1, 2,750 lbs. of hydrogen and 40,500 lbs. of nitrogen. This includes about 105 lbs. of HCl added as a make-up.

During its passage through the chloridizing zone, the Fe203 is chloridized to an extent of about 85%, thus producing 8,640 lbs. of chloridized ore per ton of iron produced. This chloridized ore, together with 270 lbs. or FeClz, which is condensed from the chloridizing gas in the chloridizing zone (again using the Fig. 1, hot separation form of the process), is passed to a vaporizing zone where its temperature is raised to about 1,750 F. and a gas stream of about 1,060 lbs. of nitrogen per ton of metallic iron produced is passed over the surface of the chloridized ore as a carrier or sweep gas. This drives olf 4,830 lbs. of FeClz vapor and leaves behind 4,080 lbs. of gangue to be discharged. The FeClz vapor is then passed to a cooling zone, where it is condensed to liquid FeClz at a temperature of about 1300 F. This liquid is then passed to and through a storage tank; and about 1,060 lbs. of nitrogen are drawn oil? from the space above the liquid surface and recycled as a sweep gas into the vaporizing zone. In the chloridizing zone, the chloridizing gas loses most of its HCl content and some of its hydrogen content, so that for each ton of metallic iron produced, the gas leaving the chloridizing zone contains about 105 lbs. of HC1, 1,020 lbs. of water vapor, 2,720 lbs. of hydrogen and 40,500 lbs. of nitrogen.

After leaving the chloridizing zone, a portion of the gas stream is bled off in order to prevent the building up of too much nitrogen in the system; and during the course of this bleeding operation, the gas stream loses about 1.5 lbs. of HC1, 17.5 lbs. of water vapor, 35.5 lbs. of hydrogen and 530 lbs. of nitrogen. The remaining gas is then passed through the scrubbing zone, Where substantially all of the HC1 and water Vapor contained are removed, so that a dry gas consisting substantially of about 45% hydrogen and 55% nitrogen by volume leaves the scrubbing zone. To this dried gas is added about 150 lbs. of make-up hydrogen per ton of metallic iron produced, so that the reducing gas entering the reducing zone (5,020 lbs.), a quantity of nitrogen used as a shield gas I around the nozzle amounting to about 555 lbs. of nitrogen per ton of iron powder produced is introduced into the system. The hydrogen and liquid FeClz introduced in these proportions into the reducing zone and maintained at a temperature of about 1250 F. react in such a manner that about 91% of the FeCl2 is reduced to metallic iron. After separation from the metallic iron, the exhaust gases, having the composition set forth above, are recycled to the chloridizing zone.

Example II this example, about 85% of the iron values of the Tobin Formation ore (the same as in Example l) are converted to FeClz, so that in this case only 7,240 lbs. of ore need be introduced into the chloridizing zone per ton of powdered iron produced. It is necessary under these circumstances, to keep the temperature of the solid material of :l

the chloridizer below about 1050 F. in order to prevent contains, per ton of metallic iron produced, about 39,970 lbs. of nitrogen and 2,820 lbs. of hydrogen. In addition to the nitrogen contained in the reducing gas, about 530 lbs. of additional nitrogen are introduced into the reducing zone in the form of a shield gas, introduced around the nozzle through which the liquid FeClz is introduced. The hydrogen and FeClz introduced in these proportions in the reduction zone and maintained at a temperature of 1250 F. are reacted in such a manner that about 94.5% of the FeCl2 is reduced to metallic iron. After separation from the metallic iron, the exhaust gases having the composition set forth above, are recycled to the chloridizing zone.

Example III This example illustrates the operation of the process when the reduction of the liquid ferrous chloride is carried out in such a manner as to produce exhaust gas from the reducing zone, the active ingredients of which contain about 15% HC1. As in the previous example, 7,240 lbs. of Tobin ore of the composition given in Example l is introduced into the chloridizing zone for each ton of metallic iron produced. Because of the lower hydrogen concentration of the chloridizing gas, it is now possible to raise the temperature in thevhot end of the chloridizing zone to about 1200 F. without the formation of metallic iron produced by the reduction of solid FeClz. However, at this temperature, certain mechanical diiculties begin to be encountered due to the agglomeration of the solid material. Thus, 1200 F. appears to be about the maximum practical temperature at which the hot end of the chloridizing zone can be maintained. As a result of this higher temperature limit, it is possible to chloridize still more rapidly than under the conditions described ,in either of the two preceding examples.

The chloridizing gases as recycled from the reducing zone contain about 0.4% of FeClz vapor, 7.5% HC1,

15 42.1% of hydrogen and 50% of nitrogen, all by volume. Thus, for each ton of metallic iron produced, there is fed into the chloridizing zone about 490 lbs. of FeCl2 vapor, 2,640 lbs. of HCl (including about 33 lbs. of make-up HC1), 810 lbs. of hydrogen and 13,420 lbs. of nitrogen.

During its passage through the chloridizing zone the FezOa in the ore is chloridized t-o the extent of about 85 thus producing about 8,640 lbs. of chloridized ore per ton of iron produced. This chloridized ore, together With about 490 libs. of FeClz, which has condensed from the chloridizing gas in the chloridizing zone, is passed to a vaporizing zone where the temperature is raised to about 1750 F. In order to facilitate this vaporization, a stream of nitrogen is passed through the vaporizing zone at the rate of about 1,120 lbs. of nitrogen per ton of iron produced. By this operation about 5,050 lbs. of FeClz vapor is produced and there is left in the vaporizingzone 4,080 lbs. of gangue to be discharged. This FeCl2 vapor is then passed to the condenser where it is cooled to a temperature of about 1300 F. to form liquid FeClz. From the condenser this liquid is passed to a storage tank and 1,120 lbs. of nitrogen are drawn off from the space above the liquid and recycled to the vaporizer for reuse as a sweep gas.

`In the chloridizing zone, the gas stream loses practically all of its HC1 content and a small portion of its hydrogen content, While picking up water vapor from the products of the reaction and from the moisture content of the ore. The resulting gas leaving the chloridizing zone contains, per ton of iron produced, about 33 lbs. of HCl, 775 lbs. of hydrogen, 1,020 lbs. of water vapor and 13,420 lbs. of` nitrogen.

About of the volume of this exhaust gas is then bled out of the system in order to prevent excessive buildup of nitrogen; and the resulting gas stream is then passed through a scrubbing zone, wherein it loses substantially all its water and HC1 content. The content of the gas stream leaving this scrubbing zone contains, per ton of metallic iron produced, about 740 lbs. of hydrogen and 12,850 lbs. of nitrogen. To this gas is added about 147 lbs. of make-up hydrogen, so Athat the gas entering the reducer contains about 887 lbs. of hydrogen and 12,850 lbs. of nitrogen. At the same time about 555 lbs. of nitrogen is introduced through the nozzle in the reducing zone along with the FeClz liquid, this nitrogen serving as a shielding gas. FeClz liquid and hydrogen react in these proportions at the temperature of the reducing zone, namely about 1250 F. t-o etect a reduction of about 90% of the FeClz to metallic iron. After separation from the metallic iron, the exhaust gases, having the composition set forth above, are recycled to the chloridizing zone.

Example IV This example illustrates the operation of the process when the reducing cycle is carried out under conditions similar to those of Example III above, but wherein the circuit carries a recycled load of about half as much nitrogen as previously, so that the chloridizing gas recycled from the reducing zone contains only about 25 nitrogen by volume. The operation of the process is much the same as that described in Example Ill above, except that the composition of the gases leaving the reducing zone is about 0.6% FeClz, 11.2% of HCl, 67.2% of hydrogen and 25% of nitrogen, all by volume. Thus, of the active -components of this gas, about of the content by volume is HCl. The chloridizing step takes place somewhat more eiciently at this low concentration of nitrogen and only about 21.5 lbs. of make-up HCl need be added to the system per ton of metallic iron produced, Whereas 33 lbs. of make-up HC1 were required when operating the system with the higher nitrogen content in accordance with Example III.

Example V When the process is operated with a higher nitrogen recycled load, but with the same ratio of HC1 to hydrogen, as illustrated in Examples lll and IV above, the operation of the cycle is much the same, except that a greater loss of HC1 occurs in the chlorodizing system and, consequently, a greater amount of make-up .HC1 ymust be added to the exhaust gas :from the reducing zone. Thus, when operating under conditions in which a recycled load of nitrogen is employed of about three times as much as that illustrated by Example IV, the exhaust gases leaving the reducing zone have a content of about 0.2% of 16 FeClz, 3.75% of HCl, 21.05% of H2, and 75% of nitrogen, all by volume. The active ingredients of this gas still contain about 1,5% HCl, with the balance hydrogen. The total amount of nitrogen recirculated through the system under these conditions is about 40,400 lbs. per ton of metallic iron produced.

Using the exhaust gas of the composition set forth above, it is found necessary to add about 67.5 lbs. of make-up HCl to the system, per ton of metallic iron produced, as compared with correspondingly smaller amounts, such as 33 and 21.5 lbs. necessary when operating under the conditions set forth in Examples III and lV, respectively. This appears to be due to the larger quantity of gases passed through the chloridizer. The chloridizing gas is in the chloridizing zone a shorter time and has less chance of utilizing the last traces of HCl.

Example VI This example illustrates the method of operating the process when the reduction of the liquid FeClz is carried out in such a manner as to produce an exhaust gas for chloridizing containing about 25% HCl, by volume of the active ingredients in this gas. When operating in this manner, 7,240 lbs. of Tobin ore of the composition given in Example l are introduced into the chloridizing zone, per ton of powdered iron produced.

The chloridizing gas leaving the reducing zone has a composition of about 2.5% of FeClz, 35% of hydrogen, 12.5% of HC1 and 50.0% of nitrogen, all by volume. Thus, with respect to the active ingredients, the HC1 is about 25% of the total volume. For each ton of metallic iron produced, the gases entering the chloridizing zone amount to about 1,930 lbs. of FeClz, 2,660 lbs. of HCl, including 20 lbs. of make-up HC1, 361 lbs. of hydrogen and 8,100 lbs. of nitrogen.

During its passage through the chloridizing zone, the FezOa in the ore is chloridized to the extent of about as described in the previous examples. Because of the greater amount of the FeClz condensed in the chloridizing zone from the exhaust gases from the reducing zone, a total of about 6,490 lbs. of liquid FeClz are thus obtained from the passage of 7,240 lbs. of ore through the chloridizing zone. The FeCl2 liquid is obtained by vaporizing the FeClz from the chloridized ore and condensing it to a liquid, as previously described.

ln the chloridizing zone the chloridizing gas loses most of its HC1 content, together with some hydrogen, so that the gases leaving the chloridizing zone contain, for each ton of metallic iron produced, about 20 lbs. of HC1, 325 lbs. of hydrogen, 1,020 lbs. of Water vapor, which has been picked up from the products of the chloridizing reaction, and 8,100 lbs. of nitrogen.

After leaving the chloridizing zone, about 10% by volume of this gas .is bled off to prevent the building up of too much nitrogen in the system. The remaining exhaust gas from the chloridizing zone is passed through a scrubbing Zone Where the Waterand HC1 contents thereof are substantially removed, leaving a relatively dry gas containing, per ton of metallic iron produced, about 330 lbs. of hydrogen and 7,380 lbs. of nitrogen. To this gas stream are added about lbs. of make-up hydrogen, while an additional 710 lbs. of nitrogen are introduced into the reducing zone as a shield gas around the jet of FeClz liquid. When the temperature in the reducing zone is maintained at about 1250o F. and the hydrogen and nitrogen are reacted in these proportions, the efficiency of reduction of FeClz to metallic iron is only about 71%. After separation from the metallic iron, the exhaust gases having a composition set forth above, are recycled to the chloridizing zone.

Example VII This example illustrates the method of operating the process when the reduction of ferrous chloride vapor is carried out in such a manner as to produce an exhaust gas for chloridizing containing about 35% HCl by volume. When operating in this manner, 7,240 lbs. of Tobin ore of the composition given in Example I are introduced into the chloridizing zone for each ton of metallic iron produced. The reduction operation is relatively inefficient in this instance as in order to produce a gas having such a Vrelatively high HCl content, the exhaust gas from the reducer is rrelatively rich in unreacted FeClz.` The exhaust jgas from the .reducing zone contains about 14.75% of FeClz, 17.5% of HC1, 17.75% of hydrogen and-`50:0%2'1'of nitrogen; allfbyfvo'lunie.'A T hus the'content of; the active chloridizngingredientsf'of this gas, namely, hydrogen 'and HC1, is' abouty 35% HC1 and 65% hydrogen, by' volume. On the` vbasis of. each tonv metallic iron produced, there' is introduced'into the chloridizing zone about-l 7,7005 lbs; of.l FeCI2`,.;2`,65O\lbs. of. HC1, .148 lbs; of hydrogen and 5,750'lb's. of nitrogen. The gases leaving the chloridizing zone contain about 11.5 lbs. of HCl, 105y lbs. of hydrogen, 1,020' lbs. of water vapor. and 5,750- lbs. of nitrogen. After about 25% .of the volume of'this exhaust gas is1bledout"`of the: systeml to prevent build-up fofY excessive amounts of nitrogen, thegas is 'passedto ai'scrubbing zone, .wherein' substantially allthe water :vapor' and: HC1 content are Iremoved. .The relativelyA dry-"gasaleavingy 'ther scrub'- bing zone. thenv contains aboutrSO-'llbs of hydrogen-fand 4,400 lbspof nitrogen, lper -tonof'metallic ironfproduced: Toy this mixture about 1401.1bs;oflmakempfrhydrogen are added. ln addition, about'. 1,350'lbs'. of nitrogen arefintroduced` into. the reducing zone-nasa shield gas for-:theliquid` FeClz jet.-

BecauseY of .they .high' HC1'. content'iof thei clrlo'ridizing gas, `a large amount .of ferrous lchlorideitis nowi con'- densedin the` chloridizing zone, so.` that for. eachton ofrironproduced, about` 12,260 lbs. 'of ferrouschloride liquid; are f now passed. into a .the:. reducingl zone :per ton of'fmetallic f iron, produced.-` When. .the FeCla'. and: hydro; gen are reacted: in thesefzproportions, atrthentemperalturezof `12507 F.,`. the reduction reactioniis 'onl'ysabout 35.5% eflicient;-

After separation from# the .metallic; iron, .-thei exhaust gases..from the reducingv zone.;.havingifthetfcomposition set for-.th iabove',4 are .recycledfto the lchloridizi-ng zone :i

While several. embodiments offthe :inventionrhave been disclosedt in the., specification; and' drawings an'dfhave been illustratedin Ythe Vexamples .,given'; itl '.Willf-.be milder;A stood thatgthe .processrmayfbef furtherf'varied.: aszwill occurntov those-.skilledin.the;art1 from the foregoing: dis4 closure.r The appendedclaims.. are to ben-consid'el'ed as embracing f such: equivalentsl wherever-x. thisA is :inotfi pre'- cluded .by expressed-:limitations therein.

What is claimed'is:v f

1. The process of preparingfmetallic iron fromlfa solid: iron oxidefcontaining; material;'comprisingfthe steps ofchloridizing a. substantialxproportion of :theuiron oxide ofsaid material to form ferrouschloridetzby'f'com tacting'- said.solidfmaterialin'a chloridizingszone and at atemperatureof lat leastn500"Y F. but belowrthesfmelte ing point; of said ferrous* chloridewitlrza gaseouszmixf' ture containing, as essential= ingredients, HG1n and: hy#y drogen-and wherein thefHCl concentration'fis from about to labout l25% .by'volume based. upon-thetotaly of hydrogen plus HClin,said. gaseous mixture, and pree venting, the reduction of iron tothe@ metallic...state by keeping said temperature always belowftheflimitinrea spect 1 to yHC1 concentration as-.definedcin.thefffollowing table.: passing..A the` remaining solid material-f as.- .thus

Temperature 1imit;( F.)

below which temperature must.b ..v maintained` HC1 fconcentration, ptcxb by volume basedi on` C1 about 5.

and over chloridized from said chloridizing zoneto 'a vaporizing zone, and-there raising the'temperature `thereofy suf-1 cientlyt to vvaporize thev ferrous chloride content fof; this material; separating thefvaporized ferrouschloridel produced in said vaporizing zone from-the. non-volatile material therein,- and passing thevaporized ferrous chloride into a condensing zone; condensing thevaporizedfrrous chloride in said condensing zone to form liquid ferrous chloride vby abstracting heat therefrom; introducingvthediquid ferrous chloride thus produced into a reducing zone-as a iinel-liquidpspray, separately' intro ducinginto said reducing zone a Vgaseous medium, the essential active reducing ingredient of which is hydrogenyforreaction with the ferrous chloride droplets of said spray, so as to reduce at least a substantial portion taining the *temperature in saidreducing zone at least as high-as' the meltingpomtcf ferrous chloride?butbe low'7 theimelfing point ofv'vsad metallic iron; separating the products resulting from `the reactionin sai'd'redu'cring'y zonebetween said gaseous medium `including hydrogen' and the liquid ferrous chloride droplets', into solid material including the metallic ironand (b.) .ga's cousl materials; including make-up lH Cl in said gaseous materials in amount@ required' to providejthe aforesaid relative'p'roportions of HC1 andhydrogen in sa'id Chlo 'dfizing' step andI passing: ther resultingga'seous materials tosaidt'chloridizing zone assaid gaseous mixture which is supplied to said chloridi'zing; zone' for yuse'as aforesaid; removingthe gaseous yproducts of' the', react-icuii; said' chloridiz'in'g.y zone froml such'y zone and `separating therefrom a substantial amount of l water vapo content thereof, and-passing th'e'sefremaining' gase'srfrbmiwhich water vaporl'l'as been' removedA and togvvhich rn'alefup hydrogen is added, into'v said reducingzzonegas said` gase'onsfmediurn whichis separately introducedinto' said reducing zone. l y

2 The processv in"a`ccordance with; claim11, wherein said gaseous materials ,resulting-y from said reaction b efjtween'y hydrogen and ferrous chloride droplets insaid reducing'v zorreand which are passed to said, chjloridizfing1zone contain about-1,5%" of HCl by volumevv based upon'the to'talof hydrogen andHCl. y ,i

3.1The-proces`s of'- preparing metallicv iron` from" a solidiiron oxide-containing material, comprising the steps. ofchloridizing a substantial proportion of the iron oxideof saidy material to' form .'ferrousuchlor'ide by contacting said solid material infa'chloridizing zone and ata temperature of at least 500 F. but below the melting-@point of said ferrous chloride with a gaseous mixture containing; asl essentialu ingredientsg'-HCl" andhyl drogen and wherein ,the HC1, concentration isf from about 5% to about-25% by volume based upon y'th'eto'tl of hydrogenvplus HClin said gaseous mixture, and-prevent-ingthe reduction of ironto the metallic'l state.,by keepingf" saidtemperature always .below th`elimit-1iri respectto -HCl concentration Vas dened vinthe] following; table passing i the remainingI 'solid materials as thus Temperature limit F2),-` belo'mwbichf temperature 'i mustvbe maintained:

HG1 concentration, pclllt by volume based on chloridized ffrornA said chloridizing zone to a jvaporizig zone",y and there "raisin'g' -the temperature l thereof sufciently vto vap'orizel the'ferrous 'chloride' conten'twoi this'fimaterial;separatingfthe vaporized ferrous chloride produced: in said' vaporizing -zone fr'o m"`theKV non-volatile material therein,j and passing the vaporized ferrous chloride into a condensing zone; condensing the vapoiw' izedA ferrous'I chloride vin said condensing'zone to form liquidi ferrous chloride by abstrac'ting heat therefrom, and:V collecting vsaidy 1iquid"ferrous' chloride ini a storagel chamber thereforinv which the ferrous chloride ismainftained/'in the liquid: state; supplying liquid ferrouschlo ride from-said storage chamber to a reducing zone and introducinghitinto the reducing 1zone as affine liquid sprayg." separately introducing int said reducing zone aj gas,'the essential active reducing-'ingredient of which'is hydrogen; fory reaction with thefer'rous chloride,L drop lets of'lsaid spray, `so as to reduce' at leastfa substantial portion'ofthe'ferrous chloride to metallic iron, .while maintaining-the temperature in said reducing'v zoneatv leastf'aslhigh as the'melting point of ferrous [chlorideg'l butfbelowthe melting 'point of vsaidinetallicY iron; sepr,` aratingtheproducts resulting from the'nreactionfinisaid reducing-zone between saidgas including hydrogen and? saidv -liquid ferrouschloride into` (a) solidmaterialfin-f cludingfthemetall'ic iron and (b)^ gaseous ,rmterialsf` including malte-upV I-IClv in saidf'gase'ous materialsy in amount-required toprovi'de the aforesaid "relativeprf)-r portions of :HC1 and' hydrogen in said chloridizing' stepl and?!v passing Y the resulting" gaseous materials` to.-k saidj chloridiz-ing'zonefas vrsaid gaseous, mixture which is su plied to said chloridi'zin'gI 'zone`"for use as 'af, r'es'ai`d;

rem'ov ng the gaseous productsof. the reactionfin s aid passing these remaining gases, from which water vapor Ahas been removed and to which make-up hydrogen is added, into said reducing zone as said gas which is separately introduced into said reducing zone, and controlling and balancing the operation of the several steps ofthe process aforesaid by controlling the rate at which liquid ferrous chloride is supplied from said Storage chamber to said reducing zone, the rate of supply of hydrogen to said reducing zone and the amount of make-up HCl included in said gaseous materials passing to said chloridizing zone.

4. The process of continuously preparing metallic iron from a solid iron oxide-containing material, comprising the steps of continuously chloridizing a substantial proportion of the iron oxide of said material to form ferrous chloride by continuously contacting said solid material in a chloridizing zone and at a temperature of at least 500 F. but below the melting point of said ferrous chloride with a gaseous mixture containing, as essential ingredients, HCl and hydrogen and wherein the HCl concentration is from about to about 25 by volume based upon the total of hydrogen plus HC1 in said gaseous mixture, and preventing the reduction of iron to the metallic state by keeping said temperature always below the limit in respect to HC1 concentration as defined in the following table: continuously Temperature limit; F.) below which temperature must be maintained HC1 concentration, pzrlcit by volume based on C1 about 5. 15 and over-.

passing the remaining solid material as thus chloridized from said chloridizing zone to a vaporizing zone, and there continuously raising the temperature thereof sufticiently to Vaporize the ferrous chloride content of this material; continuously separating the vaporized ferrous chloride in said vaporizing zone from the non-volatile material therein, and continuously passing' the vaporized ferrous chloride into a condensing zone, continuously condensing the vaporized ferrous chloride in said condensing zone to form liquid ferrous chloride by abstracting heat therefrom; continuously introducing the liquid ferrous chloride thus produced into a reducing zone as a tine liquid spray, separately and continuously introducing into said reducing zone a gaseous medium, the essential active ingredient of which is hydrogen, for continuous reaction with the ferrous chloride droplets of said spray, so as continuously to reduce at least a substantial portion of the ferrous chloride to metallic iron, while maintaining the temperature in said reducing zone at least as high as the melting point of ferrous chloride; but below the melting point of said metallic iron; continuously separating the products from the reaction in said reducing zone between said gas including hydrogen and the liquid ferrous chloride droplets into (a) solid material including the metallic iron and (b) gaseous materials; including make-up HCl in said gaseous materials in an amount required to provide the aforesaid relative proportions of HC1 and hydrogen in said chloridizing step and continuously passing the resulting gaseous materials to said chloridizing zone as said gaseous mixture which is continuously supplied to said chloridizing zone for use as aforesaid; continuously removing the gaseous products of the reaction in said chloridizing zone from said zone, continuously separating therefrom a substantial amount of the water content thereof, and continuously passing these remaining gases from which water vapor has been removed and to which make-up hydrogen is continuously added into said reducing zone as said gaseous medium which is separately introduced into said reducing zone, and controlling and balancing the operations of the several steps of the process by controlling the rate at which liquid ferrous chloride is supplied to said reducing zone, the rate of supply of hydrogen to said reducing zone and the amount of make-up HC1 included in said gaseous materials passing to said chloridizing zone.

5. The process of preparing metallic iron from a solid iron oxide-containing material including some iron in a,t ri valent state, comprising the steps of converting a substantial proportion of the iron oxide of said material to ferrous chloride by substantially simultaneous reduction and chloridization by contacting said material, while passing it through a chloridizing zone, with a gaseous mixture containing hydrogen and HCl, and while progressively raising the temperature of said material as it passes through said chloridizing zone from a temperature in the range of about 500 F. to about 800 F. to a temperature in the range of about 800 F. to about 1200" F. and wherein the HC1 concentration is from about 5% to about 25% by volume based upon the total of hydrogenplus HCl in said gaseous mixture, and preventing the reduction of iron to the metallic state by keeping said temperature always below the limit in respect to HCl concentration as defined in the following table: passing the remaining solid material as thus chloridized from said chloridizing zone to a vaporizing zone, and there raising the temperature thereof sufficiently to vaporize the ferrous chloride content of this material; separating the vaporized ferrous chloride produced in said vaporizing zone from non-volatile material therein, and passing the vaporized ferrous chloride into a condensing zone; condensing the vaporized ferrous chloride in said condensing zone to form liquid ferrous chloride by abstracting heat therefrom; introducing the liquid ferrous chloride thus produced into a reducing zone as a iine liquid spray, separately introducing into said reducing zone a gaseous medium, the essential active reducing ingredient of which is hydrogen, for reaction with the ferrous chloride droplets of said spray, so as'to reduce at least a substantial portion of the ferrous chloride to metallic iron, while maintaining the temperature in said reducing zone at least as high as the melting point of the ferrous chloride; but below the melting point of said metallic iron; separating the products resulting from the reaction in said reducing zone between said gaseous medium including hydrogen and the liquid ferrous chloride droplets into (a) solid material including the metallic iron and (b) gaseous materials; including make-up HCl in said gaseous materials in amount required to provide the aforesaid relative proportions of HC1 and hydrogen in said chloridizing step and passing the resulting gaseous materials to said chloridizing zone as said gaseous mixture which is supplied to said chloridizing zone for use as aforesaid; removing the gaseous products of the reaction in said chloridizing zone from such zone and separating therefrom a substantial amount of the water vapor content thereof, passing these remaining gases, from which water vapor has been removed and to which make-up hydrogen is added, into said reducing zone as said gaseous medium which is separately introduced into said reducing zone, and controlling and balancing the operations of the several steps of the process aforesaid by controlling the rate at which liquid ferrous chloride is supplied to said reducing zone, the rate of supply of hydrogen to said reducing zone and the amount of make-up HCl included in said gaseous materials passing to said chloridizing zone.

6. The process of preparing metallic iron from a solid iron oxide-containing material, comprising the steps of chloridizing a substantial proportion of the iron oxide of said material to form ferrous chloride by contacting said solid material in a chloridizing zone and at a temperature of at least 500 F. but below the melting point of said ferrous chloride with a gaseous mixture containing, as essential ingredients, HCl and hydrogen and wherein the HC1 concentration is from about 5% to about 25% by volume based upon the total of hydrogen plus HC1 in said gaseous mixture, and preventing the reduction of iron to the metallic state by keeping said temperature always below the limit in respect to HCl concentration as defined in the following table: passing the remaining solid material as thus Temperature limit F.) below which temperature must be maintained HC1 concentration, pxilit by volume based on aaworgrea chloridized 4fromsaidchloridizingezone tofavaporizing --`-zone, and there raxsing=1the Itemperature lthereof"` sufi ferrous chloride `byrabstractingheat .therefromg in tro-A 'ducinggthe liquid ferrous, .chloride ,thus .f produced -1nto l a reducinglzone as"` anefvliquidf spraywseparatelyamtroducing into said reducing zone a gaseous medium, the essential active reducing ingredient of which is hydrogen, for reaction with the ferrous chloride dropletsof said spray, so as to reduce at least a substantial portlon of the ferrous chloride to metallic iron, while maintaining the temperature in said reducing zone at least as high as the melting point of ferrous chloride; but below the melting point of said metallic iron; passing all the materials remaining after the reaction in said reducing zone to a separator and therein raising the temperature of these materials up to the vaporizing temperature of ferrous chloride at the pressure existing m said separator and thereby vaporizing ferrous chloride, separating the solid metallic iron from the gaseous materials in said separator including HC1 and ferrous chloride vapor; including make-up HC1 in said gaseous materials in amount required to provide the aforesaid relative proportions of HCl and hydrogen in said chloridizing step and passing the resulting gaseous materials to said chloridizing zone as the gaseous mixture which is supplied to said chloridizing zone for use as aforesaid; condensing the ferrous chloride contained in said resulting gaseous mixture to solid form in said chloridizing zone; removing the gaseous products of the reaction in said chloridizing zone from such zone and separating therefrom a substantial amount of the water vapor content thereof, and passing these remaining gases, from which water vapor has been removed and to which make-up hydrogen is added, into said reducing zone as said gaseous medium which is separately introduced into said reducing zone.

7. The process of preparing metallic iron from a solid iron oxide-containing material, comprising the steps of chloridizing a substantial proportion of the iron oxide of said material to form ferrous chloride by contacting said solid material in a chloridizing zone and at a temperature of at least 500 F. but below the melting point of said ferrous chloride with a gaseous mixture containing, as essential ingredients, HCl and hydrogen and wherein the HCl concentration is from about 5% to about 25% by volume based upon the total of hydrogen plus HC1 in said gaseous mixture, and preventing the reduction of iron to the metallic state by keeping said temperature always below the limit in respect to HCl concentration as defined in the following table:

Temperature limit F.) below which temperature must be maintained HC1 concentration, pcxllt by volume based on HCH-Hz O1 about 5- and over..

passing the remaining solid material as thus chloridized from said chloridizing zone to a vaporizing zone, and there raising the temperature thereof suiciently t0 vaporize the ferrous chloride content of this material; separating the vaporized ferrous chloride produced in said vaporizing zone from the non-volatile material therein, and passing the vaporized ferrous chloride into a condensing zone; condensing the vaporized ferrous chloride in said condensing zone to form liquid ferrous chloride by abstracting heat therefrom; introducing the liquid ferrous chloride thus produced into a reducing zone as a fine liquid spray, separately introducing into said reducing zone a gaseous medium, the essential active reducing ingredient of which is hydrogen, for reaction with the ferrous chloride droplets of said spray, so as to reduce at least a substantial portion of the ferrous chloride to metallic iron, while maintaining the temperature in said reducing zone at least as high as the melting point of ferrous chloride; but below the melt- 22 1 fing point i of H"said 5*metallic irony cooling Ethe* products Jffffthe reaction '"insaid reducing' zone :to form al *solid mixture of *metallic firon and fnnreact'edL ferrous 'chloride and 1- remaining gaseous materials, lseparating-said L"solid f =mixturefv from said`l gaseous materials" anderecovering'ythe metallic iron content thereoflfasfa'productoffthe proc ess; including make-up HCl kin ,v said gaseous materials in amount requiredeto'providedhe" aforesaid relative proportionsvof-l-ICI and,hydrogen=fin:'fsaid chloridizing step and passing the resulting gaseous materials to said #chloridizing zoneas-saidgaseousmixture which is. sup- -plied-tof said chloridizing-zone'.forjuse as aforesaid; removing the gaseous products of-the reaction "ine said chloridizing zone from such zone and separating therefrom a substantial amount of the water vapor content thereof, and passing these remaining gases, from which Water vapor has been removed and to which hydrogen is added, into said reducing zone as said gaseous medium which is separately introduced into said reducing zone.

8. The process of preparing metallic iron from a solid iron oxide-containing material, comprising the steps of chloridizing a substantial proportion of the iron oxide of said material to form ferrous chloride by contacting said solid material in a chloridizing zone and at a temperature of at least 500 F. but below the melting point of said ferrous chloride with a gaseous mixture containing, as essential ingredients, HC1 and hydrogen and wherein the HC1 concentration is from about 5% to about 25% by volume based upon the total of hydrogen plus HC1 in said gaseous mixture, and preventing the reduction of iron to the metallic state by keeping said temperature always below the limit in respect to HCl concentration as dened in the following table: passing the remaining solid material as thus Temperature limit F.) below which temperature must be maintained HC1 concentration, pefrrclt by volume based on H Cl-l-Ha C; about 5. 15 and oven.--

chloridized from said chloridizing zone to a vaporizing zone, and there raising the temperature thereof suiciently to vaporize the ferrous chloride content of this material; separating the vaporized ferrous chloride produced in said vaporizing zone from the non-volatile material therein, and passing the vaporized ferrous chloride into a condensing zone; condensing the vaporized ferrous chloride in said condensing zone to form liquid ferrous chloride by abstracting heat therefrom; introducing the liquid ferrous chloride thus produced into a reducing zone as a tine liquid spray, separately introducing into said reducing zone a gaseous medium, the essential active reducing ingredient of which is hydrogen, for reaction with the ferrous chloride droplets of said spray, so as to reduce at least a substantial portion of the ferrous chloride to metallic iron, while maintaining the temperature in said reducing zone at least as high as the melting point of ferrous chloride, but below the melting point of said metallic iron; introducing an inert gas into said reducing zone as an annular stream surrounding said ne liquid spray of ferrous chloride as the latter is introduced into said reducing zone, so as to prevent premature initial contact between the ferrous chloride droplets of said spray and the hydrogen separately introduced into said reducing zone; separating the products resulting from the reaction in said reducing zone between said gaseous medium including hydrogen and the liquid ferrous chloride droplets into (a) solid material including the metallic iron and (b) gaseous materials; including make-up HCl in said gaseous materials in amount required to provide the aforesaid relative proportions of HCl and hydrogen in said chloridizing step and passing the resulting gaseous materials to said chloridizing zone as said gaseous mixture which is supplied to said chloridizing zone for use as aforesaid; bleeding out and discarding some of the gaseousproducts from said chloridizing zone so as to prevent the building up of the concentration of inert gases being recycled in the system more than a predetermined amount, removing from the remaining gases 23 24 from the chloridizng zone a substantial amount of the 2,596,072 Graham et al. May 6, 1952 water content thereof, and passing these remaining 2,663,633 Crowley et al. Dec. 22, 1953 gases, from which water vapor has been removed and to which mak-up hydrogeni is adgedf1 into said educing 5 FOREIGN PATENTS zone as sai gaseous me ium w ic is separate y intro- 346 921 Great Britain A pr. 23, 1931 duced Into Said feducmg 20ne- 723J7O3 Germany Dec 2, 1942 References Cited in the le of this patent OTHER REFERENCES UNITED STATES PATENTS lo AlCprehensiveb Treatile on llnoranic gidh'lhegretica emistry, y Me or, vo. 1 pu is e y 212 leii: @Si 272 i332 Lfmgmans Green & C0 1935 Pages 1 and -11- 2,290,843 Kinney July 21, 1942

Claims (1)

1. THE PROCESS OF PREPARING METALLIC IRON FROM A SOLID IRON OXIDE-CONTAINING MATERIAL, COMPRISING THE STEPS OF CHLORIDIZING A SUBSTANTIAL PROPORTION OF THE IRON OXIDE OF SAID MATERIAL TO FORM FERROUS CHLORIDE BY CONTACTING SAID SOLID MATERIAL IN A CHLORIDIZING ZONE AND AT A TEMPERATURE OF AT LEAST 500* F. BUT BELOW THE MELTING POINT OF SAID FERROUS CHLORIDE WITH A GASEOUS MIXTURE CONTAINING, AS ESSENTIAL INGREDIENTS, HC1 AND HYDROGEN AND WHEREIN THE HCI CONCENTRATION IS FROM ABOUT

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