US1715155A - Method of reducing oxides or oxide ores - Google Patents

Description

May 28, 1929.

s. WESTBERG METHOD OF REDUCING OXIDES OR OXIDE ORES Filed June 27, 1925 ATTORNEYS Patented May. 28, .1929.

- UNITED STATES PATENT OFFICE.

SIGURD WESTBERG, OF PITTSBURGH, PENNSYLVANIA.

METHOD OF REDUCING OXIDES OR OXIDE 03118.

Application filed June 27, 1925. Serial No. 40,092.

' fuel or both, produces a; carbonized bath which, if a low carbon product is desired,

10 necessitates a subsequent oxidization ofthe carbides formed or the carbon in solution.

This is wrong in principle, since the interaction between carbon (either free or combined) and oxides, according to the law of 1 mass action, is increasingly retarded as the bath is deprived of its-carbon.

The practice of having the reducing material or fuel submerged in the metal bath constitutes an inherent defect in all present 2 reduction methods.

1 I have found that the principal cause for preventing the various equilibria from being quickly reached, is the inertia of slag reactions. I have further found that the 2. v oxides or oxide ores should be reduced before coming in contact with the metal bath or if not so reduced, contact should only exist between the ore or oxide slag and the bath and not between the bath and the carbon reducing material.

It isto some extent possible to prevent the formation of carbides and at the same time maintain a good recovery by treating the right proportion of carbon and oxides at extremely high temperatures, since the affinity of carbon for oxygen takes the ascend- ,ency and out-balances all other reactions. The vapor pressure of the metals, however,

' the vast amount of heat or equivalent'electric power due to the extreme cooling required and the extreme hardships to which allfurnace parts are subjected prevent the general-use ,of this so-called high temperature method. Aside from this, the control of the carbon content under'such method is at best very uncertain. Carbides under I these extremely high temperatures should become unstabilized inasmuch as the formation of the same is an exothermicprocess. Their stability is only apparent and not real, however, and this is due to thefactthat the heatof vaporization may be as much as ten times the heat of formation.

One object of this invention is to provide a method of reducing oxides or oxide ores to metallic form in which the controlof the carbon in the ultimate; product can be effectively obtained.

Another object is to provide a method by ,meansof which inertia, due to slag reactions is overcome, whereby the various equilibria may be quickly reached.

A further object is to provide a method whereby the temperature of reactions is lowered and the velocity of reactions increased.

A still further object is to provide a method whereby the recovery over-present methods is increased and the possibility of the reduction material dissolving in or alloying with the bath before reacting with the oxides is materially lessened.

These and other objects which will readil appear to those skilled in the art to whic this invention relates, I attain by means of.

the method described in the specification and pointed out in the appended claims.

In most of the present metallurgical op erations with which I am familiar, the gaseous phase is to my mind not given proper importance. The mode of introducing or obtaining the heat necessary for reduction is usually considered the governing factor. Even in .the electric furnace operations of making ferro alloys and steels no attention so far as I know has ever been paid to the very important point .of gas variation as a controllingfactor. This also applies to the making of a great number of other metals and alloys. v

The atmosphere of furnaces for such purposes is not regulatedat present. The reduction with carbon (producing carbon monoxide) will produce a certain carburization of the metalbath depending upon the temperature and pressure of the carbon monoxide. i

My investigations have shown that, in order to obtain the control of the reactions, the high frecovery and the other objects above enumerated, it is essential to control the ratio of oxides to carbon, to hydrogen or hydrogenous gas introduced into the reaction zone per unit of time and also to have sufficient heat to cause the difierent materials to interact in the same unit of time; in other words, to act instantaneously.

In c arryin out the method of this inven-' tion, I have. ound that there are three principal' conditions in performing the reducthe carbon is in excess of the metal oxides to be reduced, the hydrogen or hydrogenous as has the function of accelerating the veocity of the reaction, thus increasing the recovery and also controlling the percentage of,carbon in the ultimate product.

Under the second condition, where the carbon is approximately equal to the oxide to be reduced (in order to produce a low carbon product), the hydrogen insures a high recovery and prevents the carburiza tion of /the metal or alloy and keeps the metal of uniform analysis.

The larger the amount of hydrogen or hydrogenous gas injected in the reaction zone,-the less carbon there will be in the product as the partial pressure of CO is correspondingly reduced. By varying the ratio C/H to ()mHn/H entering the re action zone .at any time, a corresponding check on the carbide content can be obtained. The hydrogen gas actually reduces some of the oxides, thus producing as an intermediate product H O which in turn chemically reacts with the hydro-carbons. Aside from this, the h drogen gas possesses a direct in hibiting e ect on the formation of any carbides according to the reaction Under the third condition, where the carbon is less than the available oxygen, the hydrogen may form a certain amount of H 0 whereb a compound-reduction is obtained. As un er the second condition, by controlling the ratio oxide/C/H introduced into the reaction zone per unit of time, a very low carbon content in the finished product can be obtained, which is of prime importance in making such materials as ferro-chromium, rustless iron, etc.

This invention may be carried out in apparatus of various types, but for the purpose of illustration and of illustration only, I have shown in the single sheet of drawings and in a dia rammatic manner one form of ap aratus w ich may be utilized.

furnace 2 lined with suitable lining material 3 and provided with a ta ping hole and spout collectively numbere 4 is also provided with a hollow electrode 5. This electrode is suitably carried by a ring 6 which ma' be water cooled and which may be utilize for raising and lowering the electrode within the furnace chamber. A'-'gas ofltake 7 is provided for the furnace chamber and a conduit 8 associated with the electrode may serve for the introduction of carbonaceous material and hydrogen or hydrogenous gas.

Such gas may be introduced through intake 9, the carbonaceous material through intake 10 and the oxide or oxide ores through an intake at the top of tube 8, which intake is preferably provided with a bell 11.

Under a given set of conditions to temperature and ratio of oxides to carbon, the greater the'amount of hydrogen gas introduced into the reaction zone, the less carbon there will be in the finished metal and the higher the recovery will be.

The larger the amount of oxide allowed to go to waste, so to speak, in the slag, the less hydrogen gas is needed to produce a certain carbon content in the finished metal. On the other hand, the larger the amount of hydrogen gas-used, the less amount of oxide will, so to speak, go to waste, all other conditions remaining the same.

I find that I can'make a finished product with a given carbon content at minimum cost, after determining the amount of oxide I am willing to have wasted by combining with the slag, by utilizing an amount of hydrogen gas that will give the highest recovery per unit of heat and per unit of time.

In the production of low carbon metals or alloys the amount of oxides or oxide ores introduced into the reaction zone and coming into contact with the metal or bath per unit of time, should always be in excess of the amount of carbonaceous reduction material introduced into the reaction zone in the same unit of time.

This excess of oxides or oxide ores may either be present as such or may be dissolved or combined in the slag and the amount of carbonaceous reducing material and hydrogen gas introduced per unit of time, will depend upon the heat input during the same unit of time. The ratio of carbonaceous reducing material to hydrogen gas is controlled in such a way as to obtain the desired carbon content in the finished prodnet.

The amount of hydrogen gas and the ratio of oxide to carbon to hydrogen introduced per unit of time will, to some extent, depend upon themode of introduction of these materials and the physio-chemical character of the carbonaceous material and oxides or oxide ores and their state of subdivision. I

The materials, that is, the oxides, carbonaceous material and hydrogen gas can be introduced in several ways. The oxides and carbonaceous material can be introduced around, between or through the electrodes in the case of an electric furnace. The hydrogen gas can be conveniently introduced at one ,or several places as for instance,.around the electrodes or through the roof or walls of the furnace or through the electrodes or if desired, through the metal bath itself.

The oxidesand the carbonaceousmaterial can, if desired, be introduced in the form of briquettes or the oxides 'or oxide ore and carbon may be formed into continuous electrodes for carrying the current. a

As carbonaceous reduction material a high carbon metal or alloy having carbon in solution or combination may be used. For instance, if iron chromium alloys are to be made, ferro-chromium containing from 4% to 12% carbon can be used as the carbonaceous material; such ferro-chromium is readily obtainable and is relatively cheap.

F erro-chromium such as this would preferably be introduced into the reaction zone in a finely divided state and will be introduced with the oxide or oxide ore and such proportion of hydrogen or hydrogenous gas as will give a high output per unit of time.

and per unit of heat with high recovery and the desired carbon content. ner an effective deoxidation ofrthe high carbon ferro-chrome and reduction of oxide can take place in the refining operation.

The reduction method above described may be used for finishing partly reduced metals such as partly gas reduced iron ores or other metal oxides in a solid .or liquid state. This method can also be applied for de-oxidizing iron or steel containing dissolved oxides or it can be used in the place of the usual scavenging. agents, thus givi'ng'gas products of reaction without carburization. r a i The method of reduction hereby set forth v is of particular advantage in making low carbon iron or alloy steels directly from ore or concentrates and for making low car bon ferro alloys as ferro-chromium. It makes possible the manufacture of metals such as titanium, uranium, zirconium and alloys of the same which metals in a pure state, up to the present time, have not been produced in commercial quantities.

Having thus described my invention, what I claim is 1. The method of reducing oxides to metallic form, which consists in bringing together in a reaction zone such oxides, solid carbonaceous material and hydrogen containing gas in the presence of suflicient heat to efi'ect'a reaction therebetween and cause the major part ofthe carbonaceous material to be converted into carbon monoxide in the reaction zone during reaction, in keeping such carbonaceous material separated from the molten metal. and in controlling the proportions of the materials entering into the reaction in such manner as to oh- 7 tain a, maximum recovery of metal having the desired carbon content. B i "2. The method of reducing oxides to metallic form, which consists in bringing together in a reaction zone such oxides, carbonaceous material and hydrogen containing a reaction therebetween and cause the major In this manpart of the carbonaceous material to he converted into carbon monoxide in the reaction zone, in maintaining the proportions of the oxide or oxide ores in excess of the carbonaceous material and in maintaining the proportion of hydrogen or hydrogenous gases entering the reaction zone such that relatively small amounts of the oxides or oxide ores are wasted in the slag and such that the desired carbon content of the finished product is obtained.

3. The. method of reducing oxides to metallic form, which consists in bringing'together in a reaction zone such oxides, solid carbonaceous material and hydrogen containing gas in the presence of suflicient heat to effect areaction therebetween and cause the major part of the carbonaceous material to be converted into carbon monoxide in the reaction zone,.in maintaining the proportions of the oxide or oxide ores in excess of the carbonaceous material and in maintaining the proportion of hydrogen or hydrogenous gases entering the reaction zone such that relatively small amounts of the and such that the desired carbon content of the finished product is obtained.

4. The methodof reducing oxides to metallic form, which consists in bringing together in a reaction zone such oxides carbonaceous materlal and hydrogen conta ning gas in the presencev of suificient heat toefiect a reaction therebetween and cause thef'major part of the carbonaceous material to be converted into carbon monoxide in the reaction zone during reaction, in keeping the carbonaceous material out of contact with the molten metal resulting from the reaction, in maintaining the oxides or oxide ores in'excess of; the carbonaceous material and the hydrogen or hydrogenous gas in suflicient quantity to obtain a maximum re covery with a minimum of carbon in the finished metal.

5. The method of reducing oxides to metallic form, which consists in bringing together in a reaction zone. such oxides, solid carbonaceous material and hydrogen containing gas in the presence of suflicient heat to effect a reaction therebetween to cause the majofpart of the carbonaceous material to be converted into carbon monoxide in the reaction zone during reaction, in

keeping the carbonaceous material out of contact with the molten metal resulting from the reaction, in maintaining the oxides or oxide ores in excess of the carbonaceous material and the hydrogen or hydrogenous gas in sufficientquantity to obtain a maximum recovery with a minimum of carbon in the finished metal.

6. The method of deoxidizing metals containing oxygen, which consists in subjecting such metals "to the action of carbonaceous 90 oxides or oxide ores are Wasted in the slag i tem a 1 tom} 'UWW? MW W101] bonaceous material and the hydrogen or hydrogenous gas and convert the major part of the carbonaceous material into carbon monoxide in the presence of such metal; the

roportions of carbonaceous material to iiydrogen or hydrogenous gas' being such as to leave a minimum amount of oxygen and control the amount of carbon contained in the finished metal.

In testimony whereof, I have hereunto subscribed my name this 25th day of June,

SIGURD \VESTBERG.

21am) MEELBEBG'

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