US2108043A - Process for making steel and iron alloys - Google Patents

Process for making steel and iron alloys Download PDF

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US2108043A
US2108043A US744893A US74489334A US2108043A US 2108043 A US2108043 A US 2108043A US 744893 A US744893 A US 744893A US 74489334 A US74489334 A US 74489334A US 2108043 A US2108043 A US 2108043A
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ore
tube
furnace
ores
reduction
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Donald M Crist
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TITANIUM STEEL ALLOY Co
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TITANIUM STEEL ALLOY Co
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/14—Multi-stage processes processes carried out in different vessels or furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/008—Use of special additives or fluxing agents
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/08—Making spongy iron or liquid steel, by direct processes in rotary furnaces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
    • Y02P10/134—Reduction of greenhouse gas [GHG] emissions by avoiding CO2, e.g. using hydrogen

Definitions

  • This invention relates to methods and apparatus for the production of iron and steel, including alloys containing iron together with one or more other metals such as nickel, cobalt, chro- 5 mium, manganese, titanium, vanadium, hafnium,
  • an important object of the invention is to provide a method for the reduction and smelting of the ores whereby the refined final product may be secured directly from the crude ores.
  • a further object of the invention is to provide a method whereby this result may be achieved with much less consumption of time and energy and at much less expense than methods formerly employed for the manufacture of like products.
  • a further object of the invention is to provide a method whereby titanium may be caused to form a stable alloy withiron containing a percentage of titanium far in excess of that which has heretofore been procurable in metals low in silicon and/or carbon.
  • a still further object of the invention has to do with the provision of novel apparatus whereby the methods referred to may be eillciently and economically performed.
  • Figure 1 is a sectional side elevation of the receiving end of a preferred form of apparatus employed in carrying out the invention
  • Figure 2 is a view similarto Figure 1 illustrating the furnaceor delivery end of the apparatus partly illustrated in Figure 1;
  • Figure 3 is a transverse sectional view in ele- 4 vationjllustrating certain details of construction of the reduction tube of Figures 1 and 2 and associated parts;
  • Figure 4 is a sectional detail view illustrating a form of stufilng box which may be employed in connection with the reduction tube;
  • Figure 5 is a detail view partly in section and partly broken away illustrating an electrode clamp.
  • Figure 6 is a sectional detail view illustratin features of an electrode guide employed in the a roof of the furnace;
  • Figure 'l is a detail view illustrating a relief valve employed in the reduction tube.
  • Figure 8 is a fragmentary detail view illustrating a modified form of the apparatus of Figures 1 to 6 wherein oil is utilized as the reducing material in place of gas or solidreducing agents. o v
  • the general nature of the process may be briefly indicated as follows: The process is adapted Application September 21, 1934, Serial No. 744,893
  • the ores may be derived from certain black sea sand deposits, in which case they are already soaked with a saturated salt solution which plays an important part in the reduction pr0cess.- If the ores are derived from black sea sand deposits care is taken to separate the desired ore or ores from the source material by-a s process of such a nature that the salt content (about 2%) is not impaired. If the ores are derived from some other source they are preferably first ground and then soaked in a saturated salt solution.
  • the ores either before or after the salt treatment are classified as to size as by screggirg to cause all of the particles of a given ore alloy is'tobe produced the ores of the different alloying metals are mixed together in suitable proportions according to their metallic contents to yield the desired products, the ores being graded as to size range in accordance with their ease of reduction, the more refractory ores being of smaller size, so that all of the different ore constituents will be reduced in about the same time. If plain steel is to be made only iron ore is used.
  • the ores are preferably thoroughly dried before being subjected to the reducing and smelting all within a definite size range, and if an action of the disclosed apparatus. .They are then fed into the upper end of an inclined reduction tube or equivalent retort which discharges at'its I lower end into a smelting furnace. Suitable reducing gases are introduced into the apparatus I through the furnace and passthrough the tube to a point of discharge, a reducing atmosphere being maintained throughout the apparatus at all times. As the ore passes down the tube it is first preheated by external tube heating and/or the gases, then reduced in whole or part, without fusion, and then delivered into the fumace where the reduction is completed and smelting takes place.
  • Suitable fluxing material is supplied to the furnace for causing undesired ingredients to be separated out with the slag while leaving the desired ingredients in the"alloy.
  • Me from .the resulting molten bath is desirabl transferred from time to time to a refining furnace in which the metal is treated with additional fluxing materials for adjusting the carbon conunobtainable, such for instance as low carbon,
  • the apparatus is from a receiving hopper i.
  • the finely ground ores 2 pass into a screw feeder 3 in a tube 4 and thence into the upper end of a long inclined rotatable reduction tube 5 which discharges at its lower end into an electric furnace 6.
  • the molten product may be tapped off through a suitable tap opening (not shown) in the furnace wall.
  • the electric furnace 6 is also fitted with a screw feeder 8 working in a water cooled tube 9 supplied with.
  • Both feeders terminate within their tubes so as to maintain their inner ends firmly packed with material for a relatively long distance to form a seal against entry of air or loss of internal gases.
  • the two feeders may be driven separately or at desired proportionate speeds from the gears l2 indicated at their outer ends.
  • the reduction tube 5 is preferably of stainless steel fitted with lifting blades l3, and is rotatably supported as by trunnion wheels [4 resting on several rollers I5, and driven by any suitable'means such as a chain (not shown) running over a sprocket wheel I! secured to the upper trunnion wheel, so as to revolve slowly and cause the material to travel slowly downward in' the tube.
  • the reduction tube passes through a heating furnace I 8 which may be heated by any desired means such as burners I9, preferably supplied with waste fixed gases from the reduction tube.
  • the chain drive and the trunnions are protected from the heat by fire brick partitions 20 surmounted by water cooled jackets 2i
  • the lower end of the reduction tube where it enters the furnace passes through a water cooled stuffing box 22.
  • This stufiing box comprises a pair of circular jackets 23 spaced from one another and connected by a cylindrical plate 24.
  • a packing gun 25 which communicates with the space surrounding the reduction tube and lying between the jackets 23.
  • This packing gun is initially filled with a fine mixture of graphite and flake asbestos.
  • the head 26 of the gun has threadedthrough it a stem 21 which carries a piston or plunger head 28.
  • the plunger head 28 is adapted to be depressed through operation of a handle member 28 to rotate the stem 21.
  • the packing is kept relatively cool by the water jackets andmay be replenished from time to time by operation of the packing gun.
  • the stuffing box fits the reduction tube loosely, and the packing material is retained between asbestos washers 23a to form an airtight joint.
  • the upper end of the reduction tube is also provided with a suitable water cooled stuffing box 30 of the same construction as the stufilng box 23.
  • extends outward.
  • the flue is provided at its extreme end with a large gravity relief door or hinged valve plate 32 which carries a suitable weight 33 for holding the door closed.
  • the relief valve 32 is illustrated in detail in Figure 7 which shows the inner side of the valve. 7
  • the relief valve is provided with a multiplicity of openings 32a whichare normally covered by a plate 34 of a suitable asbestos composition.
  • the plate 34 is held to the-valve 32 by means of resilient clips 35.
  • the normal path for the waste gases is downward through an outlet pipe 36, through a water seal 31,111 a tank 38, and out of a final vent 39, or the gases may be conducted through a dephlegmator to recover the by-products from the waste gases and the fixed waste gas may be stored in a suitable receiver to be used for fuel purposes.
  • an electric furnace of any type such as the Heroult, Rennerfelt, induction, or high frequency type may be employed, depending upon the kind of metal to be produced.
  • the Heroult type is preferable; for low carbon steel alloys the Rennerfelt type is preferable; and for extreme low carbon steel alloys the induction or high frequency type is preferable.
  • An open hearth, top fired furnace can also be employed, if the ore material is discharged from i the tube 5 into a reducing part of the flame.
  • Coal, oil or gas fired melting furnaces of any suitable type can be used instead of electric furnaces if the proper reducing conditions are maintained.
  • the furnace illustrated is of the Heroult type.
  • a feature of the invention has to do with the mounting and packing of electrodes 40 ofthe furnace.
  • Each electrode is supported in a clamp 4
  • a screw 48 is mounted to rotate the jaw 42 in an opening and is threaded into the jaw 43.
  • the screw has fastened upon it a bevel pinion 49, the hub of which engages the outer face of the jaw 42.
  • a second bevel pinion 5U mesheswith the pinion 49 and is fastened upon a shaft 5
  • is provided with a crank handle 54 for operating the pinions to release and reset the jaws.
  • a cable 55 secured to the trolley runs upon pulleys 56, 51 and 58. When the jaws have been released the cable 55 is actuated to raise the trolley and the jaws carried by it. The jaws may then be clamped in position, and the trolley released for normal operation.
  • each electrode operates through a water cooled guide and seal in the furnace roof which is best illustrated in Figure 6.
  • This structure comprises an outer sleeve 59, an inner sleeve 50, and an intermediate or bailie sleeve 5
  • terminates short of the sleeves 59 and 50.
  • Water is introduced into the outer water space through a pipe 52 and is conducted" away from the'inner water space through a pipe communicating with the inner water space through a port 53.
  • the inner and a oaoss outer sleeves are connected by water tight walls at their upper and lower ends.
  • the upper partition wall comprises an inner ring portion 64, which substantially fits the electrode.
  • This ring is surmounted by a washer or ring SI of refractory material such as an asbestos composition.
  • a washer or ring SI of refractory material such as an asbestos composition.
  • Within the sleeve It and above the ring 66 provision is made for a quantity of loose asbestos packing 86.
  • a ring 61 which is of substantial weight, and which preferably has its lower face bevelled so as to tend to crowd the packing material inward toward the electrode. rests upon the packing material.
  • a retainin! ring 68 is secured by releasable fasteners a to a flange 69 provided at the upper end of the tube 69.
  • the furnace is desirably provided with an upwardly opening relief door or plate "which car-,
  • the door It is of large area similar to the door 32 at the end of the reduction tube so as to provide safety against explosions of
  • a pipe 12 is arranged to communicate with K passes thence through the reduction tube to intermingle with the finely divided are 2 which is being agitated and slowly fed therein.
  • the heated gases cause reduction of the ore to occur in the reduction tube and serve to preheat the ore in the upper portion of the tube.
  • the waste gases find their way outv through the water seal, as heretofore explained.
  • the water seal is so designed as to maintain a small gas pressure within the apparatus corresponding for instance to a head of about 2 inches of water,
  • the reduction tube is desirably from twentyfive to forty feet in length. I have found that for optimum conditions, about one-quarter of the cross sectional area of the tube should be occupied by the ore. Tubes having diameters of 12 inches to 28 inches have been used successfully, but somewhat larger diameters may also be found suitable.
  • the tube is revolved rapidly enough to expose the ore thoroughly to the reducing gases, and the size of the tube and the rate of supply of the ore to the tube are so selected that the tube will be kept approximately one-quarter full.
  • the tube is turned at such a rate (six to twelve revolutions per miute, for
  • a tumbling bar I5 is pivoted in the tube, the bar being universally supported by a rigid cross bar 18 located at a distance from the lower end of the tube and preferably at a point where the "tube is externally supported by one of the trunnion wheels.
  • the tumbling bar passes loosely through an opening 11 formed in the cross bar It and is provided with balls 18 for engaging opposite sides ofthe cross bar It.
  • the tumbling bar may be provided at its lower end with a ball it which runs upon the inner surface of the lower end of the tube, the lifting blades I! being caused to terminate a little short of the lower end or the tube so as to avoid interference with:
  • the tumbling bar prevents the formation of dams or rings which might be formed by agglomeration of material which is likely to occur from the super-heating of particles toward the lower end of the tube.
  • the entire operation including both reducing and smelting is carried out in a reducing atmosphere with complete exclusion of air.
  • the gas entering the furnace through the port 1.4 passes-over the molten bath which is in a state of ebullition. From the furnace the gas all passes along the tube 6. Additional heat may v be supplied to the tube from the burners I! so as to maintain the operation at the desired level of efliciency, the aim being to cause the ore to be brought to the reduction temperature at'a point 7 well up the tube from the furnace. but to avoid heating of the ore to the fusion temperature in the tube. To this end it is desirable that the average temperature of the ore in the reduction zone be maintained within range, say of 1400 to 1600 F. The best temperature range depends,
  • the molten bath in the furnace is maintained at atemperature far abovethat of the materials in the reduction tube.
  • Figure 8 disclosure is made of means for injecting oil into the lower end of the reduction tube.
  • the apparatus is in all respects the same as that of the other figures save that the gas connections are omitted, and in place thereof a water cooled pipe is led through the elbow or furnace roof into the lower end of the reduction tube.
  • the pipe Bills surrounded by a jacket ll containing a partition sleeve or tube I! which terminates short of the lower end of the jacket. Water is introduced into the outer jacket chamber and discharged from the inner jacket chamber through suitable pipes (not shown).
  • the melting chamber becomes sufficiently filled with molten metal and slag, the entire charge is taped off allowing the metal to flow into a second or refining furnace, (not shown) the slag being by-passed to suitable disposing vessels.
  • the carbon content of the bath in the refining furnace may be reduced to any desired factor by the use of a slag containing a large percentage of barium carbonate made liquid and of low specific gravity by the addition of sodium carbonate or sodium chloride and that the silicon content-of the metal may be reduced by further additions of sodium carbonate to the slag, all, however, without the presence of fluo rides or fluorine.
  • a slag containing a large percentage of barium carbonate made liquid and of low specific gravity by the addition of sodium carbonate or sodium chloride and that the silicon content-of the metal may be reduced by further additions of sodium carbonate to the slag, all, however, without the presence of fluo rides or fluorine.
  • chromium, titanium or hafnium alloys I have found that the carbon and silicon content of the metal can be reduced to the desired point with barium carbonate and sodium carbonate slag without substantial loss of these easily oxidizable metals.
  • the ores of the ferrous family it is desirable in order to reach optimum operation to -maintain the temperature of the ores in the reduction tube between 1400 F. and 1600" F. for a substantial portion of the length of the tube. It is also desirable to cause the ores to remain in the reduction tube for about twenty-five minutes, at least. If the temperature is lower the reaction is slower and either a longer tube is required or the rate of feed must be reduced. I have also found in connection with all of these ores that the correct sizing of the ore particles is of very substantial importance.
  • One purpose of treating the ore particles with salt is to obtain a lower temperature of reduction of the individual grains than is possible without the presence of the chlorine radical. While the reaction which takes place in the tube is not known with certainty it is thought to be a re cycling action of the chlorine present as there is notsufllcient chlorine'to combine atomically with the ore particles for the elimination of oxygen. As the ore travels down the tube. it is thought that the first reaction (in the cooler portion of the tube) is the conversion of the oxide to the chloride in the respective ores and that the second and last reaction (in the hotter portion of the tube and in the furnace) is the reduction of the chloride to the metallic state.
  • any alkaline chloride such as calcium chloride, magnesium chloride or barium chloride. From an economical commercial standpoint, however, sodium chloride is regarded as the 'most practicable.
  • the free carbonand hydrogen combine with the oxygen of the ore to form carbon monoxide and water.
  • the particles may be larger or smaller than produced by the screens mentioned if their relative sizes are kept within the range given.
  • the chromite is also screened to select particles within a range of sizessomewhat smaller than the range of sizes of the magnetite particles. It would be better if the particles of the iron size and theparticles of the chrome ore were all classified to a uniform size somewhat smaller than the particles of iron ore but this is dimcult to carry out in practice.
  • the size range of I the iron ore is, however, larger than the size contain magnetite, chromite and ilmeniteand some sands also carry a small percentage of hainium. Any of these ores may be separated from the sand by magnetic separation and used, after grading, without any previous soaking treatment.
  • any one of the ore ingredients is derived from a source other than sea sand, however, such ore is first ground and screened, then soaked in a saturated. salt solution and dried.
  • Suitable proportions of finely. divided iron ore such as hematite; or magnetite (preferably the latter) and finely divided chromium ore such as chromite, classified as to size, soaked with,a sat urated salt solution, and dried, are charged into the reduction tube of the furnace.
  • the graded materials are mixed in the proportion of about one thousand pounds of the chromite to twenty-two hundred pounds of the magnetic ore, and with ores of the above analyses about four hundred sixty pounds of the following fluxing compound prepared as explained later is used to feed into the melting chamber of the apparatus as the reduced, ore falls into the melting chamber from the reduction tuber a Pounds SiOz 24o NBzCOs 60 NSC] 20 B500: a C8003 60
  • the silicon dioxide converts any magnesia present to magnesium silicate, which becomes a part of the slag.
  • the bfarium carbonate removes sulphur, and avoids the'-. loss of chromium in the slag.
  • the sodium salts render the slag quite fluid without the use of fluorspar and react with any silicon present to form silicates which go into the slag, causing the silicon content to be. di-
  • the barium carbonate appears to be. a very important ingredient of the flux particularly in connection with the manufacture of chrome alloys. Itsuse and the elimination of fluorides avoids the separation of the chromium from the iron and the loss of the chromium in the slag.
  • the line mixd classified ores are loaded into the hopper i and theapparatus is brought up to working temperature by the application of extraneous heat-to' the reduction tube and/or starting up the electric furnace while circulating hot gases through the apparatus. Wherf the central portion ofthe reduction tube reaches an internal temperature suflicient for dissociation of the ore, yet not sufliciently high to. agglomerate the same, say about 1450 F. as indicated by a suitable pyrometer (not shown), and with the reduction tube set in motion, the charge is slowly fed into the upper end of the tube by means of the screw feeder at a rate taken with the in- Titania (T102) p.50
  • the chromium alloy steel is drawn directly, preferably by means of a trough, from the reducing furnace into the refining furnace, the reducing slag being by-passed during transfer.
  • a new refining slag is prepared of the following materials, preferably in about the proportions indicated:
  • sodium chloride can be substituted for sodium carbonate.
  • the soda promotes the fluidity of the slag and tends to reduce the silicon content of the metal, which is converted to sodium silicate;
  • the barium carbonate removes the last traces of the sulphur and phosphorous and acts as -a decarbonizing agent.
  • iron and steel alloys may be produced with a titanium content running as high as 16% if a titanium ore in a fine state' of division is intermixed with ironoxide ores such as hematite or magnetite and simultaneously reduced therewith in accordance with the general process heretofore described.
  • the titanium ore used is preferably the titanium oxide or ilmenite (-Fe T101) and the iron ore hematite or magnetite. These are preferably classified as previously explained to prevent recycling reactions, and fed into the reduction tube in the proportions desired, say 30% of ilmenite to 70% of magnetite to get a titanium content in the finished metal of about 8%.
  • Other ferrous titanium ores may be used in place of or mixed with the ilmenite.
  • the ores employed when derived by magnetic separation from black sea sand generally contain a small percentage of hafnium and this ingredient imparts highly desirable properties to the resulting metal.
  • the iron ore used was substantially that used for the production of chrome steels.
  • the ilmenite had approximately the following analyses:
  • the resulting metal may be transferred to another furnacefor teeming of! if the process is being carried out as a continuous one, or if being carried out one batch at a time may be kept under heat in the smelting furnace until sufliciently degassed.
  • This process will yield any desired percentage of carbon depending upon the reducing gases used as well as the nature of the charging aterial, and titanium steel alloys made by t process are of perfect'homogeneity and may be remelted without material loss of component characteristics if no fluorspar is used in the flux, andthe melting carried on in a reducing atmosphere, or under a protective slag.
  • This result I attribute to the fact that the titanium is added to the iron, particle by particle, in a reducing atmosphere. Since such a homogeneous alloy of iron with a high percentage of titanium has been hitherto unknown, I regard the alloy itself as novel and as a part of my invention.
  • the titanium alloy steel is drawn directly from the reducing furnace into the refining furnace as in the case of the chromium alloy described, and is there treated with a flux material of substantially the same composition as that described in e chr mium example.
  • said atmosphere being obtained by introducins'hydr gen gas under pressure into saidfurnace above the level of the metal bath therein, said gas being introduced in sufficient quantity to substantially exclude the entrance of atmospheric air into the apparatus, said' gas being heated in said electric furnace and passed in heated condition over the ores in said revolving tube to reduce or partially reduce the same, any ores not reduced in the revolving tube being reduced by the reducing atmosphere in the furnace so as to generate sufflcient heat to maintain a substantially balanced condition between the amount of reductiontaking place in the reaction chamber and the amount of reduction taking place in the furnace.
  • the method of making steel alloys which comprises selecting a plurality of finely divided ores of suitable metallic contents for making the desired product, grading the less refractory ore to cause the particles thereof to be .included within a predetermined size range, grading the more refractory ore to cause the particles thereof to .be included in a predetermined range of smaller size so that the particles of the ores will yield in substantially the same time to an identical reducing treatment, subjecting the mixed ores to the action of a reducing agent and heat fora sufflcient time to effect a major reduction of the ores, and then adding the product therefrom gradually to a molten bath of steel in a reducing atmosphere.
  • the method of making metals and alloys incomprises providing ore in finely divided form which has been soaked in a catalyzing solution of a sodium chloride, subjecting the ore to the action of a. reducing agent and heat for a sufficient time to effect a major reduction of the ore, and then adding the product to a molten fer- 'rous bath.
  • the process of simultaneously reducing oxide ores having dissimilar reaction temperatures which comprises subjecting the mixed ores to contact with a reducing gas at a temperature sufficient to react on the most refractory of the ores while maintaining different size relation of. the ore particles to bring about substantial reduction of all the ores in about the same period of time.

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Description

3 sheets sheet 1 D. M. -CRlST Filed Sept. 21, 1934 PRQCESS FOR MAKING STEEL ANDIROH ALLOYS F b. 15, 93s;
A INVENTOR.
DONALD M. CE/ST A'ITORNEXS Feb. 15, 1938.- 0. M. CRIST PROCESS FOR MAKING STEEL AND IRON ALLOYS 3 Sheets-Sheet 3 Fild Sept. 21, 1934 INVENTOR. Down/.0 M Ce/sT ATTORNEYS Patented Feb. 15, 1938 PROCESS FOR 2,102,042 MAKING s'ms'r. nun mom armors Donald M. Grist, San Francisco, cane, mimito Titanium Steel Alloy Company, a corporation of Delaware Claims.
This invention relates to methods and apparatus for the production of iron and steel, including alloys containing iron together with one or more other metals such as nickel, cobalt, chro- 5 mium, manganese, titanium, vanadium, hafnium,
tungsten, molybdenum, etc.
-An important object of the invention is to provide a method for the reduction and smelting of the ores whereby the refined final product may be secured directly from the crude ores.
A further object of the invention is to provide a method whereby this result may be achieved with much less consumption of time and energy and at much less expense than methods formerly employed for the manufacture of like products. A further object of the invention is to provide a method whereby titanium may be caused to form a stable alloy withiron containing a percentage of titanium far in excess of that which has heretofore been procurable in metals low in silicon and/or carbon. I v
Further objects of the invention are to provide novel alloys containing iron together with titanium and with or without other alloying elements.
A still further object of the invention, has to do with the provision of novel apparatus whereby the methods referred to may be eillciently and economically performed.
Other objects and advantages will hereinafter appear.
In the drawings forming part of this specification,
Figure 1 is a sectional side elevation of the receiving end of a preferred form of apparatus employed in carrying out the invention;
Figure 2 is a view similarto Figure 1 illustrating the furnaceor delivery end of the apparatus partly illustrated in Figure 1; Figure 3 is a transverse sectional view in ele- 4 vationjllustrating certain details of construction of the reduction tube of Figures 1 and 2 and associated parts;
Figure 4 is a sectional detail view illustrating a form of stufilng box which may be employed in connection with the reduction tube;
Figure 5 is a detail view partly in section and partly broken away illustrating an electrode clamp.
Figure 6 is a sectional detail view illustratin features of an electrode guide employed in the a roof of the furnace;
Figure 'l is a detail view illustrating a relief valve employed in the reduction tube; and
Figure 8 is a fragmentary detail view illustrating a modified form of the apparatus of Figures 1 to 6 wherein oil is utilized as the reducing material in place of gas or solidreducing agents. o v The general nature of the process may be briefly indicated as follows: The process is adapted Application September 21, 1934, Serial No. 744,893
for making plain steel or steel alloys directly from the ores. The ores may be derived from certain black sea sand deposits, in which case they are already soaked with a saturated salt solution which plays an important part in the reduction pr0cess.- If the ores are derived from black sea sand deposits care is taken to separate the desired ore or ores from the source material by-a s process of such a nature that the salt content (about 2%) is not impaired. If the ores are derived from some other source they are preferably first ground and then soaked in a saturated salt solution. The ores either before or after the salt treatment are classified as to size as by screggirg to cause all of the particles of a given ore alloy is'tobe produced the ores of the different alloying metals are mixed together in suitable proportions according to their metallic contents to yield the desired products, the ores being graded as to size range in accordance with their ease of reduction, the more refractory ores being of smaller size, so that all of the different ore constituents will be reduced in about the same time. If plain steel is to be made only iron ore is used.
The ores are preferably thoroughly dried before being subjected to the reducing and smelting all within a definite size range, and if an action of the disclosed apparatus. .They are then fed into the upper end of an inclined reduction tube or equivalent retort which discharges at'its I lower end into a smelting furnace. Suitable reducing gases are introduced into the apparatus I through the furnace and passthrough the tube to a point of discharge, a reducing atmosphere being maintained throughout the apparatus at all times. As the ore passes down the tube it is first preheated by external tube heating and/or the gases, then reduced in whole or part, without fusion, and then delivered into the fumace where the reduction is completed and smelting takes place. Suitable fluxing material is supplied to the furnace for causing undesired ingredients to be separated out with the slag while leaving the desired ingredients in the"alloy. Me from .the resulting molten bath is desirabl transferred from time to time to a refining furnace in which the metal is treated with additional fluxing materials for adjusting the carbon conunobtainable, such for instance as low carbon,
high titanium alloys free from silicon or alumi- 'num.
Referring Y I supplied.with the proper simple or mixed. ore:
to the drawings, the apparatus is from a receiving hopper i. The finely ground ores 2 pass into a screw feeder 3 in a tube 4 and thence into the upper end of a long inclined rotatable reduction tube 5 which discharges at its lower end into an electric furnace 6. The molten product may be tapped off through a suitable tap opening (not shown) in the furnace wall. The electric furnace 6 is also fitted with a screw feeder 8 working in a water cooled tube 9 supplied with. fluxing material Hi from a hopper l l. Both feeders terminate within their tubes so as to maintain their inner ends firmly packed with material for a relatively long distance to form a seal against entry of air or loss of internal gases. The two feeders may be driven separately or at desired proportionate speeds from the gears l2 indicated at their outer ends. I
The reduction tube 5 is preferably of stainless steel fitted with lifting blades l3, and is rotatably supported as by trunnion wheels [4 resting on several rollers I5, and driven by any suitable'means such as a chain (not shown) running over a sprocket wheel I! secured to the upper trunnion wheel, so as to revolve slowly and cause the material to travel slowly downward in' the tube. The reduction tube passes through a heating furnace I 8 which may be heated by any desired means such as burners I9, preferably supplied with waste fixed gases from the reduction tube. The chain drive and the trunnions are protected from the heat by fire brick partitions 20 surmounted by water cooled jackets 2i The lower end of the reduction tube where it enters the furnace passes through a water cooled stuffing box 22. This stufiing box comprises a pair of circular jackets 23 spaced from one another and connected by a cylindrical plate 24. At the top of the cylindrical plate provision is made of a packing gun 25 which communicates with the space surrounding the reduction tube and lying between the jackets 23. This packing gun is initially filled with a fine mixture of graphite and flake asbestos. The head 26 of the gun has threadedthrough it a stem 21 which carries a piston or plunger head 28. The plunger head 28 is adapted to be depressed through operation of a handle member 28 to rotate the stem 21. The packing is kept relatively cool by the water jackets andmay be replenished from time to time by operation of the packing gun. The stuffing box fits the reduction tube loosely, and the packing material is retained between asbestos washers 23a to form an airtight joint. The upper end of the reduction tube is also provided with a suitable water cooled stuffing box 30 of the same construction as the stufilng box 23.
From the upper end of the tube 5 a flue 3| extends outward. The flue is provided at its extreme end with a large gravity relief door or hinged valve plate 32 which carries a suitable weight 33 for holding the door closed. The relief valve 32 is illustrated in detail in Figure 7 which shows the inner side of the valve. 7
It is important when an explosion occurs not only that the valve be permitted to yield outward to permit escape of the explosion gases, but that care be taken to avoid the subsequent creation of a vacuum within the apparatus which might cause the apparatus to collapse. To this end the relief valve is provided with a multiplicity of openings 32a whichare normally covered by a plate 34 of a suitable asbestos composition. The plate 34 is held to the-valve 32 by means of resilient clips 35. When there is a substantial 'by cause air to be admitted freely enough to avoid the collapsing of the apparatus.
The normal path for the waste gases is downward through an outlet pipe 36, through a water seal 31,111 a tank 38, and out of a final vent 39, or the gases may be conducted through a dephlegmator to recover the by-products from the waste gases and the fixed waste gas may be stored in a suitable receiver to be used for fuel purposes.
For melting the products from the reduction tank an electric furnace of any type such as the Heroult, Rennerfelt, induction, or high frequency type may be employed, depending upon the kind of metal to be produced. For plain steel the Heroult type is preferable; for low carbon steel alloys the Rennerfelt type is preferable; and for extreme low carbon steel alloys the induction or high frequency type is preferable.
An open hearth, top fired furnace can also be employed, if the ore material is discharged from i the tube 5 into a reducing part of the flame. Coal, oil or gas fired melting furnaces of any suitable type can be used instead of electric furnaces if the proper reducing conditions are maintained. The furnace illustrated is of the Heroult type.
A feature of the invention has to do with the mounting and packing of electrodes 40 ofthe furnace. Each electrode is supported in a clamp 4| consisting of complementary clamping for releasing the clamping jaws, adjusting them and retightening them at the position desired. To this end a screw 48 is mounted to rotate the jaw 42 in an opening and is threaded into the jaw 43. The screw has fastened upon it a bevel pinion 49, the hub of which engages the outer face of the jaw 42. a collar 45a on the screw engaging the inner faceof the jaw. A second bevel pinion 5U mesheswith the pinion 49 and is fastened upon a shaft 5| which is journalled in ears 52 and 53 formed on the jaw 42. The outer end of the shaft 5| is provided with a crank handle 54 for operating the pinions to release and reset the jaws. A cable 55 secured to the trolley runs upon pulleys 56, 51 and 58. When the jaws have been released the cable 55 is actuated to raise the trolley and the jaws carried by it. The jaws may then be clamped in position, and the trolley released for normal operation.
In the combination shown each electrode operates through a water cooled guide and seal in the furnace roof which is best illustrated in Figure 6. This structure comprises an outer sleeve 59, an inner sleeve 50, and an intermediate or bailie sleeve 5|, dividing the -water circulating space between the inner and outer sleeves into inner and outer annular chambers. The baiile sleeve 6| terminates short of the sleeves 59 and 50. Water is introduced into the outer water space through a pipe 52 and is conducted" away from the'inner water space through a pipe communicating with the inner water space through a port 53. The inner and a oaoss outer sleeves are connected by water tight walls at their upper and lower ends. a
The upper partition wall comprises an inner ring portion 64, which substantially fits the electrode. This ring is surmounted by a washer or ring SI of refractory material such as an asbestos composition. Within the sleeve It and above the ring 66 provision is made for a quantity of loose asbestos packing 86. A ring 61 which is of substantial weight, and which preferably has its lower face bevelled so as to tend to crowd the packing material inward toward the electrode. rests upon the packing material. A retainin! ring 68 is secured by releasable fasteners a to a flange 69 provided at the upper end of the tube 69.
The furnace is desirably provided with an upwardly opening relief door or plate "which car-,
ries a weight 'H. The door It is of large area similar to the door 32 at the end of the reduction tube so as to provide safety against explosions of For the purpose of introducing reducing gas or gases a pipe 12 is arranged to communicate with K passes thence through the reduction tube to intermingle with the finely divided are 2 which is being agitated and slowly fed therein. The heated gases cause reduction of the ore to occur in the reduction tube and serve to preheat the ore in the upper portion of the tube. The waste gases find their way outv through the water seal, as heretofore explained. The water seal is so designed as to maintain a small gas pressure within the apparatus corresponding for instance to a head of about 2 inches of water,
.The reduction tube is desirably from twentyfive to forty feet in length. I have found that for optimum conditions, about one-quarter of the cross sectional area of the tube should be occupied by the ore. Tubes having diameters of 12 inches to 28 inches have been used successfully, but somewhat larger diameters may also be found suitable. The tube is revolved rapidly enough to expose the ore thoroughly to the reducing gases, and the size of the tube and the rate of supply of the ore to the tube are so selected that the tube will be kept approximately one-quarter full. The tube is turned at such a rate (six to twelve revolutions per miute, for
instance) that the ore will pass from one end of the tube to the other in about twenty-flve'minutes.
A tumbling bar I5 is pivoted in the tube, the bar being universally supported by a rigid cross bar 18 located at a distance from the lower end of the tube and preferably at a point where the "tube is externally supported by one of the trunnion wheels. The tumbling bar passes loosely through an opening 11 formed in the cross bar It and is provided with balls 18 for engaging opposite sides ofthe cross bar It. The tumbling bar may be provided at its lower end with a ball it which runs upon the inner surface of the lower end of the tube, the lifting blades I! being caused to terminate a little short of the lower end or the tube so as to avoid interference with:
the tumbling bar. The tumbling bar prevents the formation of dams or rings which might be formed by agglomeration of material which is likely to occur from the super-heating of particles toward the lower end of the tube.
Between thefumace body I and the furnace I dome or elbow to there is interposed a water cooled gland lb. .This'gland isof importance since it constitutes a means of preventing the dome portion from becoming frozen to the roof of the furnace, a result which might occur as a resultof the condensation of volatilized metal upon the walls of the furnace and the furnace dome.
The entire operation including both reducing and smelting is carried out in a reducing atmosphere with complete exclusion of air.
The gas entering the furnace through the port 1.4 passes-over the molten bath which is in a state of ebullition. From the furnace the gas all passes along the tube 6. Additional heat may v be supplied to the tube from the burners I! so as to maintain the operation at the desired level of efliciency, the aim being to cause the ore to be brought to the reduction temperature at'a point 7 well up the tube from the furnace. but to avoid heating of the ore to the fusion temperature in the tube. To this end it is desirable that the average temperature of the ore in the reduction zone be maintained within range, say of 1400 to 1600 F. The best temperature range depends,
of course, upon the characteristics of the materials being treated.
Should the percentage of reduction in the tube, however, fall below the desired thoroughness (85% to 90%) the unreduced ore reaching the 1 furnace will beth'ere reduced. The unred ced ore particles, tend to float with the slag an are exposed by the agitation .of the liquid bath to the action of the reducing gases.
The molten bath in the furnace is maintained at atemperature far abovethat of the materials in the reduction tube. When unreduce d ore reaches the bath in the furnace, therefore, its
reduction at that point results not only in the gas taking on the heat resulting from the exothermic character of the union of the liberated oxygen with carbon or hydrogen, but also in the gas liberated from the ore carrying with it a considerable quantity of heat derived from the molten bath in the furnace.- This extra heat is I carried by the gas into the reduction tube and causes the tube to be heated to reduction temperature for a greater distance upward from the furnace than before.
This in turn causes the reductionto be accomplished more thoroughly in the tube so that less of the unreduced ore reaches the furnace. Thus the heat supplied from the. furnace to the tube is again reduced and this balancing action goes on until the optimum conditionis substantially maintained.
As an alternative to the employment of gas. as a. reducing agent I have used lignite coal, bituminous coal, anthracite coal, charcoal, peat, sawdust and coke. but I have found the most .easily volatilized hydro-carbons such as lignite coal to be preferable. They are pro-mixed with carbon monoxide ',the charge of ore in theproportionrequired to 'v The majority of the oils thoroughly decompose at a temperature of 1100 F. and as the temperature at the lower end of the tube is always far in excess of this, complete volatilization is assured. The oils are broken down into carbon and hydrogen. The gases therefrom till the furnace and the reduction tube and the waste and unused gases, traveling counter-current to the incoming ore charge are finally discharged through the water seal.
In Figure 8 disclosure is made of means for injecting oil into the lower end of the reduction tube. The apparatus is in all respects the same as that of the other figures save that the gas connections are omitted, and in place thereof a water cooled pipe is led through the elbow or furnace roof into the lower end of the reduction tube. The pipe Bills surrounded by a jacket ll containing a partition sleeve or tube I! which terminates short of the lower end of the jacket. Water is introduced into the outer jacket chamber and discharged from the inner jacket chamber through suitable pipes (not shown).
When the melting chamber becomes sufficiently filled with molten metal and slag, the entire charge is taped off allowing the metal to flow into a second or refining furnace, (not shown) the slag being by-passed to suitable disposing vessels.
I have found that the carbon content of the bath in the refining furnace may be reduced to any desired factor by the use of a slag containing a large percentage of barium carbonate made liquid and of low specific gravity by the addition of sodium carbonate or sodium chloride and that the silicon content-of the metal may be reduced by further additions of sodium carbonate to the slag, all, however, without the presence of fluo rides or fluorine. In the case of chromium, titanium or hafnium alloys, I have found that the carbon and silicon content of the metal can be reduced to the desired point with barium carbonate and sodium carbonate slag without substantial loss of these easily oxidizable metals. In all prior operations of which I have any knowledge there is a very great diiliculty encountered in reducing the carbon in high chromium low carbon alloys, as any oxidizing medium causes extreme loss of the chromium metal content before any substantial reduction of the carbon content occurs. I have found that the presence of calcium carbonate or calcium oxide does not prevent these reactions, but if calcium compounds are used in large quantities the reactions will be slowed up.
For all of the ores of the ferrous family it is desirable in order to reach optimum operation to -maintain the temperature of the ores in the reduction tube between 1400 F. and 1600" F. for a substantial portion of the length of the tube. It is also desirable to cause the ores to remain in the reduction tube for about twenty-five minutes, at least. If the temperature is lower the reaction is slower and either a longer tube is required or the rate of feed must be reduced. I have also found in connection with all of these ores that the correct sizing of the ore particles is of very substantial importance.
One reason for this is that when the particles vary greatly in relative diameters (or in their refractory properties) there is a retarding action in the tube which inhibits the process to such an extent as to perhaps destroy its commercial application. This is thought due to a recycling or de-oxidizing and re-oxidizing of the particles brought about by the finer particles in travelling through the tube reaching the dissociation.temperature first and being reduced at once by contact with the gases within the tube and later coming into intimate contact with much larger particles which are just about reaching the dissociatlon temperature to be re-oxidized with nascent oxygen from these larger particles, buried perhaps for an instant below the eflect of the gases but subsequently yielding to the gases the next moment or at a point further down the tube. This action may repeat itself many times with the effect of prohibitively slowing down the process. Experiments have shown this difficulty to be entirely overcome by maintaining the grains of material within the size ranges mentioned. In' mixed ores separate grading is essential to keep the less easily reduced ores of smaller sized particles so that the time required to completely reduce them will be substantially the same as that required to reduce the larger particles ofthe less refractory ore of the charge mixture. A further reason for eliminating the very fine particles is that there is a greater tendency toward agglomeration when such particles are present. I
I have further found that it is of great importance in the interest of speed, economy and ef-' ficiency to saturate the ore with a saturated solution of sodium chloride so as to cause the ore to absorb a quantity of sodium chloride; for instance amounts in the neighborhood of 2% of the weight oithe ore have been successfully used. The ore after soaking is thoroughly dried before use. The purpose is to obtain as far as possible a saturation or an absorption of sodium chloride within the grains so that each grain is given sufflcient chloride to start a chlo'ridizzlng reaction of the individual grains. After the ores have been thoroughly saturated and dried they are weighed and mixed in the proper proportions according to their metallic content to form the desired alloy.
One purpose of treating the ore particles with salt is to obtain a lower temperature of reduction of the individual grains than is possible without the presence of the chlorine radical. While the reaction which takes place in the tube is not known with certainty it is thought to be a re cycling action of the chlorine present as there is notsufllcient chlorine'to combine atomically with the ore particles for the elimination of oxygen. As the ore travels down the tube. it is thought that the first reaction (in the cooler portion of the tube) is the conversion of the oxide to the chloride in the respective ores and that the second and last reaction (in the hotter portion of the tube and in the furnace) is the reduction of the chloride to the metallic state. Probably this second reaction releases the chlorine, which then travels countercurrent to the ore, and in the cooler part of the reduction tube again displaces the oxygen of the incoming ore. It may also be possible that there may be a formation of hydrochloric acid which attacks the ore particles and assists in the particle reduction.
I believe that the sodium or other alkaline element may possibly act catalytically. It is possible to use. any alkaline chloride such as calcium chloride, magnesium chloride or barium chloride. From an economical commercial standpoint, however, sodium chloride is regarded as the 'most practicable.
Instead of utilizing an alkaline chloride in the manner stated the reduction may be carried out in the presence of a mixture of a reducing gas out fusion. I
age range of important constituents:
' "Iron Chromium and free chlorine, or the chlorine may be introduced in the form of other available compounds.
The free carbonand hydrogen combine with the oxygen of the ore to form carbon monoxide and water. 7
While the soaking of the ores with the saturated solution of sodium chloride has been described as being performed after the ore. has been ground and graded as to size, it is a fact that ore advantageously eflected by means of a magnetic ore separator as disclosed in my pending application, Serial No. 751,273, filed November 3, 1934, for Magnetic ore separators. Some'sea sands The ore not derived from sand is ground. The magnetite is screened to pass a sixteen mesh per inch screen and with most of the fine particles which would pass an eighty or ninety mesh per inch screen removed so that the relative size range or particles would be from about 1 to 5 or 1 to 6. The particles may be larger or smaller than produced by the screens mentioned if their relative sizes are kept within the range given. The chromite is also screened to select particles within a range of sizessomewhat smaller than the range of sizes of the magnetite particles. It would be better if the particles of the iron size and theparticles of the chrome ore were all classified to a uniform size somewhat smaller than the particles of iron ore but this is dimcult to carry out in practice. The size range of I the iron ore is, however, larger than the size contain magnetite, chromite and ilmeniteand some sands also carry a small percentage of hainium. Any of these ores may be separated from the sand by magnetic separation and used, after grading, without any previous soaking treatment.
When any one of the ore ingredients is derived from a source other than sea sand, however, such ore is first ground and screened, then soaked in a saturated. salt solution and dried.
I regard as a part of my invention the method which consists in separating ore from sea sand magnetically or by other mechanical means so as to retainthe salt content, and then subjecting the flnely divided ore to a reducing action with- The features of the process and of the apparatus thus far described are applicable to all metals and alloys of the ferrous family. The apparatus and process have been employed for the making of plain steel and various ferrous alloys. Qne such alloy is a non-corroding chrome steel made direct from the ores. An example of such product involves the following percent Per cent Fe e.. 70 to 91 Cr 9 to 30 C .01 to 1.10
Suitable proportions of finely. divided iron ore such as hematite; or magnetite (preferably the latter) and finely divided chromium ore such as chromite, classified as to size, soaked with,a sat urated salt solution, and dried, are charged into the reduction tube of the furnace.
As an example chromite ore concentrates of substantially the following analysis have been used:
7 Per cent Iron Chromium 35.10 Alumina 11.34 Lime LPSS than .10
Black sand magnetite concentrates of substantially the following analysis have been used:
' s Per cent 1.64
Silica Alunn Magnesi range of the chrome ore.
The graded materials are mixed in the proportion of about one thousand pounds of the chromite to twenty-two hundred pounds of the magnetic ore, and with ores of the above analyses about four hundred sixty pounds of the following fluxing compound prepared as explained later is used to feed into the melting chamber of the apparatus as the reduced, ore falls into the melting chamber from the reduction tuber a Pounds SiOz 24o NBzCOs 60 NSC] 20 B500: a C8003 60 The silicon dioxide converts any magnesia present to magnesium silicate, which becomes a part of the slag. The bfarium carbonate removes sulphur, and avoids the'-. loss of chromium in the slag. The sodium salts render the slag quite fluid without the use of fluorspar and react with any silicon present to form silicates which go into the slag, causing the silicon content to be. di-
minished as desired. The proportions of the' fiuxing materials may be varied according to the ore used and the product desired. Potassium Y and calcium chloride act similarly to sodium chloride.
The barium carbonate appears to be. a very important ingredient of the flux particularly in connection with the manufacture of chrome alloys. Itsuse and the elimination of fluorides avoids the separation of the chromium from the iron and the loss of the chromium in the slag.
- The fact that fluorides are unnecessary and are scrupulously avoided enables chrome steel to be manufactured by the present process wltha far higher percentage of chromium recovery than has heretofore been possible.
The line mixd classified ores are loaded into the hopper i and theapparatus is brought up to working temperature by the application of extraneous heat-to' the reduction tube and/or starting up the electric furnace while circulating hot gases through the apparatus. Wherf the central portion ofthe reduction tube reaches an internal temperature suflicient for dissociation of the ore, yet not sufliciently high to. agglomerate the same, say about 1450 F. as indicated by a suitable pyrometer (not shown), and with the reduction tube set in motion, the charge is slowly fed into the upper end of the tube by means of the screw feeder at a rate taken with the in- Titania (T102) p.50
clination and rate of revolution of the tube so ore were all classified to a substantially uniform that a quantity of material occupying approximately one-quarterof the capacity of the tube is maintained in the tube, and so that the particles will be exposed to the heat for a period of time running from twenty to thirty minutes, more or less, depending upon the nature and fineness of the ore as well as the hot reducing gas used which is simultaneously and continuously run through the apparatus. As soon as the reduced ores begin to fall into the furnace chamber, the ground flux is fed slowly into the furnace by the screw feeder 8 operated in proper relation with the ore feeder 3 so as-to maintain the proportions stated, and when a sufficient mass of material is in the hearth the molten mass is tapped oif into, an adjacent electric furnace for teeming off. If the proportions of the ores are properly determined by an analysis of their metallic contents, any desired alloy relation may definitely be produced, though if it is desired to modify any given batch of metal this may be done by introducing other metals into the molten bath.
The chromium alloy steel is drawn directly, preferably by means of a trough, from the reducing furnace into the refining furnace, the reducing slag being by-passed during transfer.
A new refining slag is prepared of the following materials, preferably in about the proportions indicated:
Parts NazCOa 3 NaCl 1 BaCOa 4 I. CaCOa 2 These materials are intimately mixed and sufficient water is added to thoroughly wet themass which is allowed to dry and then the resultant cake is broken up to the desired size for use.
This method of slag preparation allows the materials to be added tothe refining furnace without loss of the sodium carbonate which, if used in a finely divided state, will create violent reactions. y I v i 7 It will be noticed that the substantial constituents of the flux are sodium carbonate and barium carbonate with the complete absence of fluorides.
If desired sodium chloride can be substituted for sodium carbonate.
The value which I have found particularly attributable to this composition are: first, the soda promotes the fluidity of the slag and tends to reduce the silicon content of the metal, which is converted to sodium silicate; second, the barium carbonate removes the last traces of the sulphur and phosphorous and acts as -a decarbonizing agent. Y
In the example given above, four cubic feet of natural gas and three cubic feet of hydrogen per pound of metal obtained were used, and while much of this would ordinarily escape without entering the reaction, still in a large industrial installation it could be collected, separated and recycled together with fresh gas or otherwise advantageously disposed of as by utilizing it for fuel to heat the reduction tube. The escaping gas in the example given contains about 40% carbon monoxide. 1
I have discovered that iron and steel alloys may be produced with a titanium content running as high as 16% if a titanium ore in a fine state' of division is intermixed with ironoxide ores such as hematite or magnetite and simultaneously reduced therewith in accordance with the general process heretofore described.
The titanium ore used is preferably the titanium oxide or ilmenite (-Fe T101) and the iron ore hematite or magnetite. These are preferably classified as previously explained to prevent recycling reactions, and fed into the reduction tube in the proportions desired, say 30% of ilmenite to 70% of magnetite to get a titanium content in the finished metal of about 8%. Other ferrous titanium ores may be used in place of or mixed with the ilmenite. The ores employed (when derived by magnetic separation from black sea sand) generally contain a small percentage of hafnium and this ingredient imparts highly desirable properties to the resulting metal.
The iron ore used was substantially that used for the production of chrome steels. The ilmenite had approximately the following analyses:
cno= 1.4a T101- 3329 F9203 -2 62.76 s10: -i 2.50
As before the ores are classified as to sine,
soaked in a saturated salt solution, dried, fed
into the reduction tube, and treated generally in the Manner already described.
As the substantially reduced mixture falls into the furnace, it is slagged with a suitable material depending upon the ore analyses but a mixture substantially as follows has been found satisfactory.
Parts by weight SiOz 4 NazCO: 3 NaCl 1 BaCO: 4 CaCOa 3 The ingredients of the fluxing material perform substantially the same functions indicated in connection with the chromium example. A titanium iron alloy is thus produced in which the silicon content is very low, preferably less than .5%, so that a steel is formed which has excellent forging properties.
After smelting, the resulting metal may be transferred to another furnacefor teeming of! if the process is being carried out as a continuous one, or if being carried out one batch at a time may be kept under heat in the smelting furnace until sufliciently degassed.
This process will yield any desired percentage of carbon depending upon the reducing gases used as well as the nature of the charging aterial, and titanium steel alloys made by t process are of perfect'homogeneity and may be remelted without material loss of component characteristics if no fluorspar is used in the flux, andthe melting carried on in a reducing atmosphere, or under a protective slag. This result I attribute to the fact that the titanium is added to the iron, particle by particle, in a reducing atmosphere. Since such a homogeneous alloy of iron with a high percentage of titanium has been hitherto unknown, I regard the alloy itself as novel and as a part of my invention.
The titanium alloy steel is drawn directly from the reducing furnace into the refining furnace as in the case of the chromium alloy described, and is there treated with a flux material of substantially the same composition as that described in e chr mium example.
I have found that ore containing a substantial amount of hafnium and also titanium when reduced in this furnace produces a metal of outstanding merit and physical properties for example an ore of the following analysis was used.
The metal produced from this ore analyzed'as follows:
Carbon .340 Sulphur .008 Phosphorus J .024 Silicon .088 Manganese a .24 Chromium .25 Titanium .89 Hafnium .80 Iron -L Balance Thismetal showed by microscopic examination I eluding a substantial proportion of iron, which a very thorough dissemination of carbon and the absence of carbide segregations.
The tensile strengths, elongation and reduction of area were greatly increased, as compared with similar metal not containing the titanium and hafnium and when this ore was mixed with component ores for the production of non corroding irons or steels it was found that the present low range of carbon content required to guarantee non corrosive properties can be substantially increased and still maintain non corrosive properties. There is also marked difference in the malleability and workability of the metal, it being more easily forged and machined.
The denseness of structure and improved homogeneity of this metal is shown to produce cut ting edge tools of marked superiority. Plain steels containing as low as-'.01% of each titani um and hafnium show a vast diflerence in physical and microscopical characteristics, as compared with similar steels which do not carry these elements.
'I claim:
1. The method of producing substantially carbon-i'ree metals or alloys whichconsists in passing the finely divided ores or concentrates of said metals or alloys continuously through'a. revolving tube, discharging the reduced and partially reduced material into the melting chamber of an electric furnace and melting said material 'into a molten bath in said furnace together with the desired fluxes for slag making purposes, all of said operations being performed. in an atmosphere of heated non-carbonaceous reducing gas. said atmosphere being obtained by introducins'hydr gen gas under pressure into saidfurnace above the level of the metal bath therein, said gas being introduced in sufficient quantity to substantially exclude the entrance of atmospheric air into the apparatus, said' gas being heated in said electric furnace and passed in heated condition over the ores in said revolving tube to reduce or partially reduce the same, any ores not reduced in the revolving tube being reduced by the reducing atmosphere in the furnace so as to generate sufflcient heat to maintain a substantially balanced condition between the amount of reductiontaking place in the reaction chamber and the amount of reduction taking place in the furnace.
2. The method of making steel alloys which comprises selecting a plurality of finely divided ores of suitable metallic contents for making the desired product, grading the less refractory ore to cause the particles thereof to be .included within a predetermined size range, grading the more refractory ore to cause the particles thereof to .be included in a predetermined range of smaller size so that the particles of the ores will yield in substantially the same time to an identical reducing treatment, subjecting the mixed ores to the action of a reducing agent and heat fora sufflcient time to effect a major reduction of the ores, and then adding the product therefrom gradually to a molten bath of steel in a reducing atmosphere.
3. The method of making metals and alloys incomprises providing ore in finely divided form which has been soaked in a catalyzing solution of a sodium chloride, subjecting the ore to the action of a. reducing agent and heat for a sufficient time to effect a major reduction of the ore, and then adding the product to a molten fer- 'rous bath.
means of reducing carbon in the bath, and the amount of sodium carbonate being sufflcient to remove the silicon from the metal bath to the extent desired and to cooperate with the barium carbonate in the production of a fluid slag.
5. The process of simultaneously reducing oxide ores having dissimilar reaction temperatures which comprises subjecting the mixed ores to contact with a reducing gas at a temperature sufficient to react on the most refractory of the ores while maintaining different size relation of. the ore particles to bring about substantial reduction of all the ores in about the same period of time.
- DONALD M. CRIST.
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US2515764A (en) * 1948-01-10 1950-07-18 Roy A Driscoll Apparatus for converting metals
US2771354A (en) * 1953-06-01 1956-11-20 Nat Lead Co Concentration of iron ores
US3194648A (en) * 1962-07-30 1965-07-13 Mannesmann Ag Methods of obtaining metal powder from ores or oxides
US3753687A (en) * 1970-12-07 1973-08-21 Bethlehem Steel Corp A process of treating iron oxide pellets with a chloride and producing iron pellets therefrom
US4392822A (en) * 1978-08-02 1983-07-12 Klockner-Humboldt-Deutz Ag System for burning fine-grained material, particularly for the manufacture of cement clinkers
US4425092A (en) 1978-08-02 1984-01-10 Klockner-Humboldt-Deutz Ag System for burning fine-grained material, particularly for the manufacture of cement clinkers
WO2014105795A1 (en) * 2012-12-28 2014-07-03 Hackett Micah J Iron-based composition for fuel element
US10157687B2 (en) 2012-12-28 2018-12-18 Terrapower, Llc Iron-based composition for fuel element

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2515764A (en) * 1948-01-10 1950-07-18 Roy A Driscoll Apparatus for converting metals
US2771354A (en) * 1953-06-01 1956-11-20 Nat Lead Co Concentration of iron ores
US3194648A (en) * 1962-07-30 1965-07-13 Mannesmann Ag Methods of obtaining metal powder from ores or oxides
US3753687A (en) * 1970-12-07 1973-08-21 Bethlehem Steel Corp A process of treating iron oxide pellets with a chloride and producing iron pellets therefrom
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CN104981559A (en) * 2012-12-28 2015-10-14 泰拉能源公司 Iron-based composition for fuel element
US9303295B2 (en) 2012-12-28 2016-04-05 Terrapower, Llc Iron-based composition for fuel element
CN104981559B (en) * 2012-12-28 2018-11-30 泰拉能源公司 Iron-based compositions for fuel element
US10157687B2 (en) 2012-12-28 2018-12-18 Terrapower, Llc Iron-based composition for fuel element
US10930403B2 (en) 2012-12-28 2021-02-23 Terrapower, Llc Iron-based composition for fuel element

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