US2594298A - Reduction and refining of ferrous ores in one continuous operation - Google Patents

Description

April 1952 w. E. DUDLEY REDUCTION AND REFINING OF FERROUS ORES IN ONE CONTINUOUS OPERATION 6 Sheets-Sheet 1 Filed Nov. 10, 1948 INVENTOR:

WALTER EDUDLEY PER M ATTORNEY April 29, 1952 w UD 2,594,298

REDUCTION AND REFINING OF FERROUS ORES IN ONE CONTINUOUS OPERATION Filed Nov. 10, 1948 6 Sheets$heet 2 El -w-mm E 5% INVE NTOR WALTER EDU LEY PER fi rn flf fl ATTORNEY April 29, 1952 w. E. DUDLEY REDUCTION AND REFINING OF FERROUS ORES IN ONE CONTINUOUS OPERATION 6 Sheets-Sheet 3 Filed NOV. 10, 1948 k 124... mu oH WALTER E. DUDLEY April 29, 1952 w. 5. DUDLEY REDUCTION AND REFINING OF FERROUS ORES IN ONE CONTINUOUS OPERATION 6 Sheets-Sheet 4 Filed NOV. 10, 1948 FIG. 9.

INVENTOR:

WALTER EDUDLEY PER ' ATTORNEY FIG. 8

April 29, 1952 w DUDLEY 2,594,298

REDUCTION AND REFINING OF FERROUS ORES IN ONE CONTINUOUS OPERATION Filed Nov. 10, 1948 6 Sheets-Sheet 5 INVENTOR:

ATT ORNEY 8 Edm April 29, 1952 w. E. DUDLEY REDUCTION AND REFINING OF FERROUS ORES IN ONE CONTINUOUS OPERATION 6 Sheets-Sheet 6 Filed NOV. 10, 1248 INVENTOR:

WALTER EDUDLEY PER My ATTORNEY GYWONNBLVM NOUA Patented Apr. 29, 1952 UNITED STATES PATENT OFFICE REDUCTION AND REFINING OF FERROUS ORES IN ONE CONTINUOUS OPERATION 7 Claims.

This invention relates to metallurgy and more particularly to the process of, and apparatus for, reducing and/or refining ferrous ores and the production of ferrous alloys without the necessity of an intervening cooling interval during the operation.

One of the objects of the invention is the production of a high grade ferrous material reduced directly from ferrous ores and immediately thereafter refining the same in an improved and novel manner while still in the heated condition.

A further object of the invention is the reduction and refining of ilmenite and other complex ferrous ores in pig iron, semi-pig steel and high grade commercial steel in one continuous operation.

Another object of the invention is the provision of a new and improved portable plant or apparatus that is capable of being located at the ore sources for cheaper transportation of the reduced material and that has its parts so constructed and arranged and so functionally correlated, electrically operated and controlled as to be economical in reducing and refining ferrous and other ores.

Another object of the invention is the utilization of novel compositions and proportions of reducing and refining agents for treating the ore material and for treating it in a novel manner.

Another object of the invention is anew and improved method for the application of electric heat and its control for pre-heating, reducing and/or refining ferrous ores during the ore treating operation.

A still further object of the invention is a novel method of reducing ferrous ores by the application of higher temperatures for shorter periods of time than is the conventional practice, for obtaining an improvement in the quality of the reduced metallic material.

Other and further objects and advantages of the invention will appear from the following description taken in connection with the accompanying drawings in which,

Fig. 1 is a side elevation of the preheater oven and reduction furnace shown diagrammatically, with parts in section, parts broken away and parts omitted for the sake of clearness.

Fig. 2 is a detailed view of a portion of the elevator belt shown in Fig. 1;

Fig. 3 is an enlarged side elevation of a portion of the preheater oven with parts broken away;

Fig. 4 is a transverse sectional view of Fig. 3;

Fig. 5 is a side elevation of the reduction furnace and operating mechanism;

Fig. 6 is a front elevation thereof;

Fig. 7 is a vertical section of a reduction furnace, with parts broken away, parts in section, and parts omitted for the sake of clearness;

Fig. 8 is a bottom plan view of the lower electrode holder with bus-bar and contacts;

Fig. 9 is a rear view of a lower portion of furnace showing electric contacts.

Fig. 10 is a plan view of upper electrode holder and associated parts;

Fig. 11 is a plan view of one section of the upper water cooled electrode holder;

Fig. 12 is a side view of the same section with parts in section;

Fig. 13 is a perspective view of a portion of the reduction furnace showing the pouring attachment applied thereto.

Fig. 14 is a front view thereof with parts in section;

Fig. 15 is a side elevation in section of the pouring attachment applied to a section of the furnace;

Fig. 16 is a plan view of Fig. 15 with parts in horizontal section;

Fig. 17 is a section on line IL-il of Fig. 14; Fig. 18 is a diagrammatic view of the mechanism for water-cooling the electrode holders with parts in section and parts omitted for the sake of clearness; and

Fig. 19 is a vertical section on line |9l9 of Fig. 10, of upper electrode holder with parts broken away.

The continually rising costs of transportation and reduction of ferrous and other ores being reflected as they are in the increased prices of the finished products, it becomes highly desirable to design ways and means to ofi'set this trend to higher prices. The present invention seeks to do this .by reducing the cost of such transportation and by improvements and economy in the beneficiation of the ores.

It is common practice to build exceedingly large plants, requiring the services of an army of workmen for reducing and refining ferrous and other ores, and to locate such plants at commercial centers, usually distant from the mines,

thus necessitating the shipment of the ores often over great distances.

Since the ores contain a great amount of waste material over the reduced metal, the cost of transportation of this added material becomes important-and adds materially to the transportation costs.

In order to avoid this added cost, especially where conditions are favorable, it is desirable to locate the plant, or plants, each of which may be preferably, although not necessarily, a small complete plant, at the site of the ore mines or deposits whereby only the reduced metal need be shipped to the mills, thereby effecting a material saving in the cost of transportation by the elimination of the waste material.

The present invention also effects a material economy in the beneficiation of ores of various kinds and more especially in the reduction and refining of ferrous ores which are accomplished in functionally successive steps in one continous operation by an apparatus consisting of units arranged similar to an assembly line in a manufacturing plant. The units are operated by electric motors which are controlled by switches assembled on a switchboard whereby the entire plant may be operated and controlled by a small number of employees, usually some 4 or 5-being sufficient.

In the conventional method of reducing and refining'iron ores it is common practice to employ in'the reducing and refining furnaces temperatures'below 3500 F. maximum, and requiring considerable time to complete the reduction and refining operations. Several hours are usually required for these purposes, especially where blast furnaces for reducing the ore are employed. It has been discovered that a better quality of ferrous metal may be obtained if electric furnaces be employed with temperatures within the reduction furnace at an estimated 3500 F. and above for a materially shortened period of time, usually 15 or 20 minutes, and during this time increasing this temperature for alternate short periods very materially above the fusing point of the ores. The temperatures for brief periods usually rises materially above 3500 F. and sometimes as high as an estimated 6000 F. to 8000 F., but is at all times under control. This method requires no cooling period. Furthermore, the furnace being of the electric type is under control and the product obtained is not only denser, but is more duticle, stronger and tougher than the conventional productand'is not troubled with slag, occluded gases nor blow holes.

Since there are various types and compounds of ferrous ores requiring somewhat different treatments and different proportions of the materials of the fiuxing, reducing and refining agents, it is thought that description of the treatment of one type of ore will be sufficient for illustrative purposes and for an understanding of the invention and for that reason the method of treating the ferrous ore known as ilmenite or black sand has been selected as illustrative of the inventors method for reducing and refining various types of ferrous ores and alloys. The ilmenite ore found in the lower valley of the St. Lawrence River in Canada has been actually successively treated by the process and apparatus herein disclosed. This material varie somewhat in composition.

In describing the method and apparatus employed, the treatment of the ore will be traced through the apparatus and reference will be had to the drawings. Ore suitably dried and pulverized to a fine mesh, say 300 mesh and finer (having the form of an exceedingly fine or impalpable ore dust or powder) is mixed with weighed quantities of fiuxing, deoxidizing and reducing agents.

Powdered charcoal or other powdered carbon is a suitable reducing agent.

The reducing, fluxing and deoxidizing agents may vary somewhat for different ores but the following materials and proportion have been found to give excellent results for reducing ilmenite ores:

For each lbs. of the powdered ore add the following in powdered form:

10 lbs. of charcoal (C) 3.5 lbs. sodium carbonate (NazCOa commercial soda) 1.5 lbs. powdered manganese oxide (MnO) .5 lb. fiuorspar (CaFz) .10 lb. burnt lime (CaO) .05 lb. barium (Ba) .01 lb. beryllium oxide (BeO) The batch is thoroughly mixed in a batch mixer, which is of the conventional form except that it is provided with heating units, which maintain 'themixer container at about 200 to 350 .F. for drying the mixed material, including the binder, before .it is delivered to the press. It take about 20 to 30 minutes to get the mixture dry enough to flow freely as required for the press. Suitable binder ingredients are added before drying and mixing the material preparatory to compressing it into small briquettes. The following .binder ingredients have been found to give excellent results. For each 100 pounds of the powdered ore add:

1-3 pounds of corn starch (which may be commercial bulk form) 1-3 pound heavy molasses mixed with sufficient boiling water to make a heavy thick paste If desired, the reducing, fiuxing and deoxidizing agents and the binder ingredients may be mixed andthis mixture .thenadded to the powdered ore in the batch container before the materials are transferred to the batch mixer.

After theground ore and the other powdered materials, including .the binder, are thoroughly mixed and dried the mixture is transferred to the briquette press I, where it is compressed under considerable pressure into briquettes 23, Figs. 3 and 4 of suitable size-and form. In the form shown, which is by way of example only, they are cylindrical with their edges beveled and are approximately 1%" long and 1 in diameter, each weighingabout four ounces.

The press is of the usual or well known construction and need not be described. It may operate at different speeds so as to be made to synchronize with the other cooperating mechanismsof'the plant and is'provided with a briquette supporting station 24 for receiving the briquettes discharged from the press I. The outer portion of the station v24 extends downwardly and outwardly in the form of fingers 25 for holdingithe briquettes until they are picked up by cooperating fingers 26 forming the bottom wall of the buckets of the elevator belt 21. These fingers 26 pass upwardly between the fingers 25 and carry the briquettes upwardly and drop them .ontoan inclined guide or chute 28, where they gradually slide onto the carrier or conveyor belt 29', which travels about one foot per minute through the drier or preheater oven J, Figs. 1 and 3 for progressively increasing the temperature of the briquettes and thoroughly drying the same throughout their mass preparatory to delivering them into the reduction furnace K, where the heat is so intense it would cause any moisture left in the briquettes to explode and cause unnecessary agitation and splashing of the molten material within said furnace. a

The preheating and drying oven J comprises an elongated tubular casing or housing, preferably formed of three sections 29, 3| and 32, Fig. 3, of about equal lengths, totaling about 24 feet. A partition 33, Fig. 4, in the form of a truncated-V in cross section supported by its upper edges from the inner upper side walls of the sections 29, 3| and 32, extends lengthwise of the housing and divides the same into an upper preheating and drying oven proper 34, and a lower chamber 35 which extends the full length of the housing.

Extending throughout the heating oven 34 and rigidly supported by bars or posts 36 from the bottom portion of the partition 33 is a channel member 31, Figs. 1, 3 and 4, facing upward for receiving theupper run of a conveyor belt 38 for guiding and supporting the same with the briquettes within the heating oven proper 34. The lower run of the belt 38 is supported on rollers 39 within the air chamber 35, Fig. 3.

Each section 29, 3| and 32 of the casing or preheater oven J is provided with an air admission conduit 4| on its under surface and having a sliding valve 42 for controlling admission of air into the lower portion of the air chamber35 and a discharge conduit 42 through which fumes, gases and the like may escape upwardly from the preheater oven 34. The fresh air entersthrough the valves 42 into the air chamber and flows upward through suitable openings within the bottom of the preheater oven 34, Fig. 4, around the conveyor and is discharged with the gases, fumes and the like through the discharge conduits 42 in the upper portion of the preheater casing sections 29, 3| and 32 as indicated by the arrows in Fig. 4. The conduits 43 may discharge into the atmosphere through the roof of the plant.

The preheater or drying oven J or preheater oven proper 34, Fig. 4, is heated by electric elements in a plurality of stages in successive increases in temperature. In the form of construction shown, sections 29, 3| and 32 are provided with separate electric heating units 44 which maintain the section 29 at approximately 200 F., the section 3| at about'300 F. and the section 32 at a temperature of approximately 500 'F. By thus progressively increasing the heat of the briquettes as they are carried by the conveyor they are thoroughly dried without chipping or cracking.

- The electric heating units 44 are under control andextend longitudinally of their respective sections along one focus of a two part parabolic reflector 45 which concentrates the heat from the element 44 onto the briquettes 23. In order to give access to the elements 44 for replacement and repairs, the reflectors 45 are each formed in two sections hinged as at 46 and 41 to the opposite sides of the partition 33. Access may be had to the interior of the casing of the preheater oven J through doors 48 hinged as at 49, each extending longitudinally of its corresponding sections 29, 3| and 32 of the preheater.

It will thus be seen that by means of this arrangement the briquettes are gradually dried and thoroughly heated throughout their mass to a temperature of approximately 500 F. or above Without blistering or cracking, within a period of about 24 minutes.

The conveyor or conveyor belt 38 deposits the briquettes into a chute5| pivotally supported at its upper end, Fig. 1, which is about four feet long and along which the briquettes are conducted by gravity into the reduction furnace K. This chute is in two sections, hinged together at their lower sides about midway whereby the lower section may be elevated and moved from the opening '65 in the closure 63 of the reduction furnace K as indicated in dotted lines in Fig. 1 and as will presently appear.

Heated gases from the furnace K escape upwardly through this chute 5| into a duct or chimney H5 extending to the atmosphere from the adjacent .end of the preheater. section 32. Since gases generated in the furnace Kare at a very high temperature and can escape upward through the chute 5|, and .the adjacent chimney I15, thiscounterflow of heated gases very materially increases the temperature of the incoming briquettes andprepares them for their entry into, the reduction furnace K. The weight of the compressed. briquettes causes the same to sink to the bottom of the molten mass within the reduction furnace K and are promptly reducedto molten form by the intense heat of the Fig. 5, which are journaled on a base 56 that permits the furnace to be tilted forwardly when desired. The base 56 is provided with swiveled supporting'wheels 51 for permitting movement of the furnace when necessary. This is considered an important feature of the invention since it permits the removal of one furnace and the substitution of another within a period of about 15 minutes, when in need of replacement or repairs. This is a great advantage where the plantis organized in a continuous operating line forwhen one unit breaks down the whole line must stop. By providing three furnaces, it will beseen that while one is being repaired another oan be in operation and the third ready to be substituted in case of failure of the one inoperation, thus insuring substantial continuous operation of the plant so far as the furnace is concerned.

Appropriate mechanism is provided for tilting the furnace K forwardly for pouring the molten material therefrom and for returning the furnace to upright position. This construction will now be described. Rigidly mounted on one of the trunnions 55, Fig. 5, is a worm wheel 58 operated by a worm 59, which in turn is operated by a reversible motor 6| through suitable reduction gearing 62. The worm 59 is mounted on a heavy base member I8 6 that is vertically adjustable for taking up play between the worm and the gear 58.. This worm is provided with a thrust bearing. at each end, one of which is ad justable for taking up end play of said worm.

The base;| 8fi is vertically adjustable in guides' by a screw extending through a lug I81 fixed on the base 56, Fig. 5, and engaging the lower end of the adjustable base I86 for taking up play between the Worm and gear.

Thrust bearings I83 are inserted between the trunnion bearings I82 and the sides of the furnace K for preventing side play of the furnace. A magnetic brake l84 that is energized for stopping the tilting of the furnace K when the motor is stopped and de-energized when the motor is started, is provided and mounted on the trunnion 55 opposite the gear '58.

The opening through the top. of the furnace is provided with a cover or closure 63 which sits on top of the furnace as shown in Fig. 1. This cover has an axial opening 64 through which the upper electrodes extend downwardly into'the reduction furnace as will presently appear, and an opening 65 into whichthe chute extends as shown in said figure. In order to prevent heat radiation from the interior of the furnace K through the closure 63, the same is adapted to be covered by a layer 18! of heat insulating material. If desired, theinsulating material may have an axial opening closed by an annular cover I90 having two small openings through which the upper electrodes extend. When the electrodes are elevated beyond a certain point this small annular cover is elevated also by two flexible insulated cables attached thereto and'to the electrode carrier beam 92.

The front wall of the furnace K is provided with an opening adjacent to its upper edge in which is rigidly secured a pouring or discharge pipe 66 lined with refractory material 61, Fig. 15.

Suitable means are provided for conducting the molten material flowing outward from the pouring pipe 66, Fig. 14, to a suitable ladle or mold without unduly exposing the molten material to the atmosphere, thereby avoiding sparks and reducing oxidation to a minimum. As shown, a pouring attachment is provided for this purpose. This attachment comprises a funnel member 68 comprising an upper cylindrical section, an intermediate tapered section and a lower reduced cylindrical section. This member 68 is lined with refractory material 69, and is pivotally supported by ball bearings 12 on oppositely extending shafts H rigidly fixed to the tube 66, Fig. 16. The ball bearings 12 permit the funnel to remain in vertical position while the furnace is being tilted and are located below the top edge of the funnel member so that the top edge thereof is notched or slotted as at 13, Fig. 14, for receiving the tube or pipe 66 when the furnace is in upright position. The funnel 68 is provided with a cover 14, having a radial notch 15 therein registering with notch or slot 13, so that when the furnace is tilted forwardly the pipe or tube 63 may enter the slot 15, whereby the funnel is very nearly closed to the admission of air while the 'furnace is being discharged.

Ball bearings '76 have their inner races rigidly mounted on the ends of arms H and'have hooks T! on their outer races to which chains or other supporting members 18 may be attached for supporting the conventional bottom discharging ladle for receiving the slag and moltenmaterial from the reduction furnace K. As shown, the hooks Tl support'chains 18, which in turn may support an ingot mold 80 for receiving molten metal from a refining furnace or from the furnace K when functioning asarefining furnace. In Fig. 14 the chains l8 areshown as removably engaging hooks 19 on the upper portion of a two part casing 8! of an ingot mold 80 lined with suitable material 82, suchas carbon. Thesecarbon-lined molds and the like are preferably painted with a water" mixture of natural earth materials known as thermalude to prevent absorption by the hot metal of carbon, etc. from the carbon-lined containers. The two sections of the mold have abutting flanges, bolted together in the usual manner, as shown at 83, Fig. 17. The cavity of the mold is shown as being cylindrical with its upper end enlarged for receiving the lower end of the funnel, as shown in Fig. 14, thus excluding as much air as possible during the pouring operation.

The furnaces K and L are of the electric type of low voltage and very high amperage, and the current employed may be and preferably is a single phase which may be converted from a 3- phase current.

Suitable means are provided for electrically heating both the reduction and the refining furnaces and for applying increased heat at very high temperatures, especially to the reduction furnace for alternate short intervals of time over a period of only a few minutes. Excellent results are obtained by applying the increased heat for each alternate 30 seconds of time for a period of approximately 15 minutes.

Each furnace has a lower electrode 84 and two upper vertically movable electrodes 85 and .86 arranged in multiple. The lower electrode holder 81 and the upper electrode holder 93 are twopart and each part or section is water cooled independently, as will presently appear.

The upper electrodes are moved downward into contact with the lower one for starting the arc and alternately raised or lowered at the end of every 30 seconds for a period of about 15 minutes. In other words, the upper electrodes are lowered for a space of 30 seconds and then elevated for a space of 30 seconds and thus continued for a period of 15 minutes. During this time the temperature within the furnace may vary considerably. These variations are estimated to be from 3500 F. to possibly 8000 F. due to the periodic raising and lowering of the upper electrodes for varying the resistance of the current and to the exothermic reactions of the materials.

The heat may be controlled by controlling the amount or distance of the raising and lowering of the upper electrodes or the frequency of such action. After the upper electrodes have been lowered into contact with the lower one for starting the are or circuit it may not be necessary to lower the electrodes'only part way since the ore material, especially if molten, will to an extent become a conductor.

Suitable means are provided for raising and lowering the upper electrodes. Any appropriate means may be employed for this purpose. As shown in Figs. 1, 5 and 7, a tower 8B in the form of a square in cross section, made of bars or standards extending vertically at the rear of the furnace K is provided. Slidably mounted in guides 89 on the tower 88 are a pair of plates 9| between which are fixed a pair of transverse supporting arms or beams 92. These beams or arms extend horizontally in opposite directions from the plates and on the inner ends of which is the upper electrode holder 93, and on their outer ends is a counterweight at, Fig. 5. The inner ends of the arms or beams 92 extend inwardly to a point where the upper electrodes 85 and 88 are supported vertically above the lower electrode 8 1, Fig. 1, within the furnace K.

A flexible member or drive chain 95, Fig. '7, having its upper end portion anchored to the plates 9! extends upwardly andaround the pulley or sprocket wheel 96 journalled at the upper end of the tower 88 and downwardly around a lower pulley or sprocket wheel 9'I journalled at the lower end of the tower, and has its lower end also anchored to the plates 9|. The pulley 9! is driven through a suitable flexible gear mechanism or flexible belt 98 by a motor and change gear apparatus 99, Fig. 7.

When it is desired to lower the upper electrodes from the position shown in Fig. 7, the motor is operated to cause the pulley 91 to rotate right handed as seenin Fig. 7, as will be obvious from an inspection of said figure. Reversing the rotation of the pulley 91 will obviously elevate the upper electrodes from any lowered position.

Threaded on the upper end of the lower electrode 84 is a contact plate IOI (Fig. 4) engaging the insulating refractory material 54. The lower ends of the upper electrodes 85 and 86 are threaded into a contact plate I80, Fig. 1, which is adapted to contact the plate IOI and register therewith when the upper electrodes are lowered. These contact plates IOI and I60 make perfect contact and when slightly separated provide a zone of intense heat between them. In order to insure an even wear or pitting of the contact plates WI and I80, appropriate mechanism is provided for rotating the upper electrodes 85 and 86 together with contact-plate I80 at will, as will now be described. The upper electrode holder 93 has a ring gear I02, Figs. 7 and 19, rigidly attached thereto, but insulated therefrom by the insulation I12, Fig. 19. This ring gear is swivelly or rotatably mounted on a base plate I03 rigidly mounted on the arms or beams 92. The base plate I03 is provided with an arcuate slot in the form of an inverted T and the gear I02 has depending bolts I13 that are screwed into plates I14. slidable in said slot. A pinion I04 meshes with the ring gear I02 for turning the latter in either direction for changing the positions of the upper contact plate I80 relative to the contact plate IOI. The pinion is rotated in either direction by turning a handle I05 secured on the lower end of the pinion shaft, as shown in Fig. '7.

Suitable electric conductors are provided for conducting the current from the transformer, not shown, to the electrodes. The eurernt being very high amperage requires heavy bus bar conductors. As shown, the current may be considered as passing from the transformer through the bus bar I06, Figs. 5 and 6. The bus bar I06 is positioned above the tower 88, Fig. 5, and extends down along the same, Fig. 6 in slightly spaced relation, and is insulated therefrom by insulating mechanism I01. Since thefurnace K must be tilted to discharge the reduced materials, the bus bar I06 cannot run directly to the lower electrode. Appropriate mechanism is provided for causing a break in the circuit when the furnace K is tilted, as will now be described. The lower end of the bus bar I06, Figs. 7 and 8, extends between the rear ends of two parallel horizontally arranged smaller bus bars I08 and is rigidly connected thereto. The forward ends of the smaller bus bars I08 are offset toward the furnace K to the plane of the vertical axis thereof that is parallel with the bus bar I06 and receive between them a central reduced portion of a fixed contact plate member I09, Fig. 9. The plate member I09 has an upper flat, smooth, broad face that contacts a corresponding 'flat broad, smooth face on the 'lower side pf a contact plate member I II], on the reamends V lapping parts together.

1o of a "pair of short bus bars III. The rear ends of the short bus bars III receive between them the reduced portion of a contact member 0 and the parts are rigidly connected together. The forward ends of the short bus bars I II have clamped between them lugs on sections of the lower electrode holder 81, as shown in Fig. 8. The contact plate member I09 remains immovable and the contact plate member IIO moves with the furnace K when the latter is tilted. The engaging faces of the contact plate members I09 and H0 being in flat engagement throughout their areas, the lower contact plate rests on a block of resilient material, such as a heat resistant rubber block I I2. A similar block of rubber or other electrical insulation H3 is inserted between the upper contact plate member H0 and the bottom of the furnace K. The resiliency of these rubber members and the slight flexibility of the short bus bars III will permit the contact plate members to adjust themselves to make a perfect electrical contact throughout their entire faces when forced together when the furnace is tilted to vertical position. These rubber members H2 and H3 also assist in electrically insulating the bus bars and electrode and holder from the furnace and other parts of the apparatus as is necessary in order to prevent shorting cf the circuit.

The forward ends of the short bus bars I I I have clamped between them lugs I I4 which are on the rear ends of the two sections of the electrode holder 81, the same bolts being used to clamp the The forward ends of the two-part electrode holder are provided with similar lugs I I5 for clamping the two parts of the'electrode holder together for holding the lower electrode in position.

The electrode holder 01 is supported beneath the furnace K by two angle bars or members IIS and I I1 having their vertical flanges insulated from, and secured to, the adjacent sections of the electrode holders as at H8, Fig. '7. The horizontal flanges of these angle members are insulated from the furnace by insulation member I16 and are secured to the under surface of the furnace K. The horizontal flange of the angle member I I I is provided with transverse slots I I0 whereby the angle bar II'l may be slid outwardly to provide clearance for separating the sections of the electrode holder for removing the electrode 84 when desired.

The two sections of the upper holder for the two electrodes 05 and 86 are provided with terminals .I2I and I22, respectively, and insulated flexible conductors I23 and I24 are attached thereto. The conductors I23 and I24 are looped to provide suflicient length for the raising and lowering of the upper electrode mechanism. The outer ends of .these flexible conductors are both secured to a suitable fixed bus bar, which in turn is suitably ground-ed. All of these parts just described are insulated from the furnace so that when the furnace is upright and the upper electrodes arein contact with the contact plate IOI the current entering through the bus bar I06 passes through the smaller bus bars I08, the contact plates I09 and N0, the short bus bars II I, the lower electrode holder 81, the lower electrode 84,;the contact plate IGI, upward through the contact plate I89, the upper electrodes and 86, the upper electrode holder 93, the insulated looped flexible electric conductorsand connected busbar to thegrou-nd ,c i -,.;Elhe .electrode ho1ders .';8l and: 93 are; water cooled and the system for cooling the electrodes must beinsulated'from the water and sewersystems of the city furnishing this water. This arrangement shown diagrammatically in Fig. 18 will-now be described.

The lower electrode holder 81 and upper electrode holder 93 are both in two sections, the'sections of each holder being arranged in a horizontal plane. The lower holder has eachsection provided with a semi-circular recess I25, which to gether form a vertical circular opening for receiving the single electrode 84. Thetwo sections of the electrode holder 81, Fig. 8-, are provided at their rear ends with mating clamping lugs H4, and at their front ends with mating clamping lugs H for clamping the two sections together around the electrode 84. The upper electrode holder is similar to the lower but each section of the upper holder is provided with two semi-circular recesses I26 and I2'I, Figs. 10 and 11 for receiving the two electrodes 85 and 86 in parallel.

Each section of each electrode holder is hollow as indicated at 90 in Fig. 12 and is independent'of the others, as will presentlyappear.

The water for cooling the electrode holders is discharged from a water supply pipe I 28, Fig. 18, into a reservoir I29 elevated above the electrode holders so that the water is circulated by gravity and by the differential heat expansion or the water flowing through the hot electrode holders. The discharge end of the pipe I28 is spaced above the reservoir I29 to form a gap as at I3I so that the pipe is insulated from the reservoir. An overflow pipe I32 extends from below the reservoir I29 and upward into the same to near the top thereof and discharges into a tank I33 below the reservoir, which in turn discharges into a pipe I34 leading to the sewer. The overflow pipe I32 is spaced from the tank to form a gap as shown at I35, so as to insulate reservoir I29 from the sewer system. A main supply pipe I36 conducts cool water from the reservoir I29 to flexible branch conduits I31 and I38, which in turn conduct water-to the hollow cavities of the two separate sections of the upper electrode at the ends thereof, respectively. An auxiliary pipe I39 with flexible branch conduits MI and I42 conduct cool water from the reservoir I29 to one end of each section of the lower electrode holder, respectively. The hot water returns to the reservoir I29 from the upper electrode holder sections through branch flexible conduits I43 and I44 and a main discharge pipe I45. The hot' Wateris'returned-from the lower electrode holder sections to the upper portion of the reservoir I29 through the branch conduits I46 and I41, the auxiliary pipe I 48 and the main discharge pipe I45. It will be noted that the intake for each of the upper electrode holder sections is at one end and lower than the discharge at the opposite end. On the lower sections of the electrode holder, the intake and discharge openings are on the under side of the sections but are diagonally arranged. Both arrangements facilitate and insure the circulation of the water through the sections of both electrode holders. The branch conduits are of heat resistant rubber and are of suflicient length to permit tilting of the furnace and vertical movement'of the upper electrode holder.

Assuming now that the reduction furnace K is empty, that is, has been discharged and tilted back to its upright position, the preheater oven, including the. conveyor belt is set in operation to supply briquettes to the reductionifurnace, and the upper electrodes arexloweredxintoz contact. and

raised a short distance to draw the are. In the normal operation the preheater oven J operates to supply dry, heated briquettes to the reduction furnace, and the upper electrodes are lowered fora space of approximately Bil-seconds and then elevated for the same space of time. While the upper electrodes are in lowered position the contact plates NH and I may be spaced a short distance apart and an intense heat is created between the plates for heating the material. This heat fuses the ore and together with the heat released by the action of the fusing materialraises the temperature of the same temporarily toan estimated 4000" to 8000 F. which causes the molten metal between the plates to be forced radially outwardly and being highly heated expands and becoming lighter rises to the surface of the surrounding molten metal while the cooler surrounding liquid metal takes its place.

It is not known why there is such a phenomenal increase of heat within the restricted zone between the conductor plates at the instant the material of the briquettes first encounter this zone. There is .a series of minute energy releasements of the ore briquettes caused from the heat of the electrode contacts and an increased heat created by the gases from the briquettes as the ore-is being thrown into liquid suspension. In other words it is a series of miniature violent explosions and the temperature of said zone rises from probably 3500 F. or 4000 F. to an estimated 6000 F.'to 8000 F. while the upper electrodes are in lowered position. This extremely high temperature is temporary and is localized in the zone between the contact plates and adjacent or closely surrounding space. As a result of this intense heat, the metal becomes extremely fluid which results in a homogeneous and more excellent product. When the upper electrodes are elevated thespace between the contact plates IUI and I80 is extended thereby increasing the electrical resistance-between those plates with a corresponding lowering of the temperature of all the parts thereby preventing injury to th lining, plates and other exposed parts. During the raising and lowering of the upper electrodes they are not elevated above the surface of the bath until it is desired to tip or discharge the furnace. As the bath increases and the slag increases, the heat in creases and the electrode contacts must be gradually separated to compensate for the increased volume of the bath.

This present reduction process is not one of steady continuous heat of comparatively low temperature that gradually, in due time, melts the ore. It is a reduction process whereby the ore is reduced into liquid suspension in seconds of time by a series of miniature explosions created by the introduction into the furnace of approximately" exact amounts of ore on approximately exact'timing'coming in contact with'the approximately exact timing of prepared heat to cause the immediate explosion and then the approximately exact' timing of cooling periods regulated by lifting of the upper electrodes and elapse of time between the periodsof introducin substantially definite amounts of ore into the furnace.

The'timing schedule is determined by the type of. ores being reduced, some ores require higher temperatures and shorter periods of time than others. In any event, the temperatures employed are. far above the conventional temperatures usually employed for reducing ferrous ores.

In; order to. protect-the furnace lining. and the contact:- plates from such intense'heat, the upper 13 electrodes are raised a considerable distance at the end of about 30 seconds for a period of 30 seconds to permit a slight cooling of the parts and for preventing burning of the molten metal. Thus the molten material is thoroughly agitated during the periods the upper electrodes are in lowered position and slightly reduced in temperature during about 30 seconds they are in their upper position. This alternate raising and lowering every 30 seconds is continued for a period of 15 minutes, after which the preheater oven 38 is stopped and the reduction furnace is tilted and the molten metal and slag are poured from the furnace through the funnel 68 into a conventional bottom discharge ladle for separating the molten metal from the slag by discharging the former from the bottom of the ladle into the refining furnace L. Instead of employing a bottom discharge ladle for separating slag and molten metal, the furnace K may be tilted to pour the slag off the molten metal into the slag mold through the funnel 68 and the furnace tipped back to upright position and then again tipped.

forwardly to pour the molten metal through the funnel 68 into the mold 80.

Itis the common practice at the present time if alloy steels and the like are to be made, to add theferro-alloy material to the reduced ferrous material after it has cooled and been reheated. But with the present invention the ferrQ-alloy material such as ferromanganese, ferro-nickel and the like are added to the reduction furnace during the reduction operation, in the required amounts to give the desired alloy.

It may, under certain circumstances, be desirable to mold the molten metal into ingots directly from the reduction furnace without first refining it in the refining furnace. In that event, the molten metal, with or without having the alloy material added, is discharged through the funnel member 68 of the reducing furnace into a suitable ladle having a bottom discharge, and from thence into the desired mold through this discharge in readiness for the market.

Assuming it is desired to refine the molten" metal directly from the reduction furnace, the reduced material is poured through the funnel member 68 into a ladle and the molten metal is then discharged from the ladle into the refining furnace L. This furnace is similar in construction to the reduction furnace K, except it ma be a little smaller but is heated in the same manner. After two 15 minute batches have been transferred from the reduction to the refining furnace, the refining flux agents are added to the extent of approximately to 1 lb. of refining material for each 100 pounds of the molten material within the refining furnace.

This pound of refining material is in dry powdered form and comprises:

, Percent Silicon dioxide (S102) 47.2 Iron (Fe) 1.7 Iron oxide (F6203) 12.5 Aluminum oxide (A1203) 19.1 Calcium oxide (CaO) 10.1 Magnesium oxide (MgO) 7.2 Sodium oxide (NazO) 1.7 Potassium oxide (K) 0.3

After the second batch is transferred from the reducing to the refining furnace and the refinin agents added, the material is treated in a manner similar to that employed in the reducing furnace but for only a period of about five minutes. That is, the upper electrodes are lowered for a space of seconds and then elevated fora space of about the same length of time over a period of about five minutes. About one minute before the expiration of the five minute period, a deoxidizer such as aluminum or barium or a sodium compound is introduced into the refining furnace. The following ingredients give satisfactory results:

Pounds Aluminum powder .10 Barium oxide powder .05 Bicarbonate soda powder .25 Silicon carbide .50 Borax .05 Calcium oxide .05

This deoxidizer is in powdered form and one tional bottom discharge ladle and from the ladle directly into the ingot mold 80.

The motive power for operating the various units is electrical and is controlled by switches I50, assembled on one or more switchboards H51, whereby a minimum number of employees are required to operate the plant.

While the method herein described is especially adapted for reducing ilrnenite ferrous ore and alloys, it is understood that it is not so limited as it is also adapted'for reducing ferrous ores and alloys of other types, such as haematite, magnetite, siderite, and the like. The apparatus may also be used in Whole or in part in the production of other metals.

Instead of reducing the ores, reducing, oxidizing, fiuxing and refining agents, to exceedingly fine powders they may be reduced to coarser particles and employed in the reducing and refining processes but the results obtained with the use of coarser particles are not so desirable.

The ingredients of the formulas given above may be varied somewhat for difierent types of ores, for instance, the formula given for the reducing, fluxing and deoxidizing agents may vary in different ferrous ores and alloys substantially as follows for each pounds of grounds ore add the following:

Pounds Charcoal 8-20 Sodium carbonate 1 /z3 /2 Powdered manganese 1 1 -3 Fluorspar .05-50 Burnt lime .05-.15 Barium .01-.10 Beryllium oxide ill-.10

all in powdered form.

,comprises mixing together finely divided ore with fine1y divided fluxing and reducing agents and applying to the mixture intermittent applications of heat at temperatures greatly in excess of the fusing temperature of the ore for successive closely spaced short durations of time to reduce the ore.

2. The method of reducing ferrous ores which comprises maintaining a pool of molten metal, subjecting the molten metal in the pool to successive closely spaced applications of increased heat of short duration at temperatures materially above the fusing temperature of the ore and charging into the pool briquettes of finely divided ore mixed with fiuxing and reducing agents.

3. The method of reducing ferrous ores, which comprises mixing the finely ground ferrous ore with finely divided fiuxing and reducing agents, pre-heating the mixture by successively increasing the temperature applied thereto and immediately thereafter reducing the pre-heated ore by successive intermittent applications of increased heat of short duration and closely spaced time intervals at a high temperature materially above the fusing point of the ore.

4. A method of reducing ferrous ores which comprises maintaining a pool of molten metal, subjecting the pool of molten metal to an electric arc and varying the intensity of the electric are for frequent time intervals at short duration to apply intermittent increments of temperature materially in excess of the melting point of the ore, and charging comparatively small briquettes containing admixed finely divided ferrous ore, and fiuxing and reducing agents into the molten pool at frequent intervals.

5. A method of reducing ferrous ores which comprises maintaining a pool of molten metal, subjecting the pool intermittently to an arc of temperature materially in excess of the melting point of the ore for time intervals of thirty seconds out of each minute, preheating comparatively small briquettes comprising finely divided ore and fluxing and reducing agents in admixture and charging the briquettes into the pool at frequent intervals.

6. A method of reducing ilmenite ore from the lower St. Lawrence River section in one continuous operation, which comprises pre-heating briquettes of finely ground ilmenite ore mixed with finely ground reducing and fluxing agents,

maintaining a pool of molten metal at a temperature of 3500 F. and above, immediately after pre-heating discharging the briquettes into the pool of molten metal, and subjecting the pool to increments of temperature materially in excess of the melting point of the ore for alternate periods of thirty seconds out of each minute.

7. A method of reducing and refining ferrous ore which comprises pre-heating briquettes comprising the ore of fineness below 300 mesh mixed with finely divided charcoal, sodium carbonate, manganese oxide, fluorspar, burnt lime, barium and beryllium oxide, maintaining a charge of molten ferrous metal at a temperature well above 3000 F., charging the briquettes into the pool of molten iron, and periodically at close spaced short successive time intervals increasing the temperature of the melt to a temperature Well above 3500 F.

WALTER E. DUDLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 285,135 Johnston Sept. 13, 1883 790,390 Price May 23, 1905 937,120 Tone Oct. 19, 1909 980,369 Walker Jan. 3, 1911 1,058,991 Lindblad Apr. 15, 1913 1,334,004 Van der Toorn Mar. 16, 1920 1,584,763 Gaudy May 18, 1926 1,665,778 Fredrickson Apr. 10, 1928 1,691,272 Flodin Nov. 13, 1928 1,719,558 Mills July 2, 1929 1,823,604 Holbeck Sept. 15, 1931 1,831,596 Harper Nov. 10, 1931 1,848,710 Gustaffson Mar. 8, 1932 1,864,593 Gustaffson June 28, 1932 1,970,291 Everhard Aug. 14, 1934 2,028,105 Head Jan. 14, 1938 2,252,760 Dulcos Aug. 19, 1941 2,261,587 Moore Nov. 4, 1941 2,286,218 Martin June 16, 1942 2,290,031 Brooke July 14, 1942 2,363,371 Vignos Nov. 21, 1944

Claims (1)

1. A METHOD OF REDUCING FERROUS ORES WHICH COMPRISES MIXING TOGETHER FINELY DIVIDED ORE WITH FINELY DIVIDED FLUXING AND REDUCING AGENTS AND APPLYING TO THE MIXTURE INTERMITTENT APPLICATIONS OF HEAT AT TEMPERATURES GREATLY IN EXCESS OF THE FUSING TEMPERATURE OF THE ORE FOR SUCCESSIVE

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