US964868A - Method of reducing metallic oxids. - Google Patents

Description

G. M. JOHNSON.

METHOD OF REDUCING METALLIC OXIDS.

APPLICATION FILED JUNE 19, 1909.

Patented July 19, 1910.

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G. M. JOHNSON.

METHOD or nnnuome METALLIC oxms.

APPLICATION FILED JUNE 19, 1909.

-Ptented July 19, 1910.

2 SHEETS-SHEET 2.

.NVENTOR- Z v 6 g 6 Atty ll|l l 1 l I I l I UNITED STATES PATENT OFFICE.

'CHARLES moms-JonNsoN, or AVALON, PENNSYLVANIA, ASSIGNOR TO oIt'UcIBLE STEEL COMPANY OF AMERICA, A CORPORATION OF NEW JERSEY.

To all whom it may. concern:. Y

Be it known that 1, CHARLES MORRIS JOHN- -son, residing at Avalon, in the county of .Allegheny and State of Pennsylvania, a citizen of the UnitedSta'tes, have inventedor, discovered certain new and useful Im rovements in Methods of Reducing etallic Oxids, of which improvement the following is a specification.

My invention relates to improvements in reducing metallic ores and oxids, and more particularly to the reduction of tungsten oxids, and the object of my invention isto produce metallic tungsten in a commercial manner and peculiarly free from impurities.

, Tungsten oxld has heretofore been reduced'ln a crucible by mixing it with charcoal and bringin the mixture to a high temperature. A di 'culty in this operation has" been the presence of an excess of carbon,

which'together with the ash from the carbonaceous material employed, it is practi cally impossible to eliminate, and which re: mains as a dross or impurity in the metallic tungsten produced by this operation.

My invention consists in bringing. the

tungsten ore or oxid to a reducing tempera;

. tu-re in a closed chamber in which is contained in addition to the body ofiore or oxid to bereduced a body of carbon or other carbonaceous material, separated from bodily contact with the tungsten ore or oxid, and which at such temperature will effect the reduction of the tungsten oreor oxid.

In the accompanying drawings which form part of this specification, I have shown an apparatus in which myimproved method may be performed. I do notlimit myself to an articular form-of apparatus, but a description of this apparatus will serve to explainmy invention;

-Figu're' 1 shows in vertical longitudinal section a reducing furnace in which my improved method may be performed. Fig. 2 1s a v1ew in perspective and on larger scale of one of the receptacles used in charging the furnace. Fig.3 shows in cation of the'structure.

Like parts are designated by the same nu merals m'the several figures.

The furnace chamber is shown in the plan a modifildrawings at- 1, and as there shown, this chamber may conveniently be formed of a section of iron pipe closed at its opposite a HETHOD OF REDUCING METQL LLIC OXIDS.

ends by caps 2 and '3. The chamber is mounted in a furnace 4:; preferably, remov-,

ably mounted therein; and I' have found it advantageous, though by no .means necessary, 'to have a substantial part of the chamber protrude beyond the furnace wall. Any adequate means of heating may be employed. In the drawings I have shown gas burners, 5.

Specification of Letters Patent. Patented J uly 19, 1910. Application filed June 19, 1909. Serial No."5os,112."

for a chamber of the Shapeshown are conveniently'semi-cylindrical in form and relatively short as compared with the entire length of the chamber, and in these receptacles the materials for the reducing operation are charged. If, for example, the furnace chamber is 9 feetlong and 6 inches in diame'ter, these small receptacles will be of sufficient diameter to permit their ready introduction into the chamber, and in length they may be from 6 inches to 1 foot. Some of these receptacles I fill with the ore or oxid to be reduced; some of them I fill with car bon, or cztrbomcontaining substance, preferably. finely divided charcoal. The ore-containing receptacles I conveniently make about one foot long, the carbon-containing receptacles about 6 inches long.

I charge the furnace by introducing 1n succession a number of receptacles 8 containing the substances requisite to accomplish the desired reduction. Preferabl I first introduce a smaller receptacle fi led with charcoal, which will be pushed along to the rear end of the furnace chamber as other receptacles are introduced. Followlng the carbon-containingreceptacle, I introduce a .la'r er receptacle filled with the oreoi' oxid to e reduced, and after it another smaller carbon-containin receptacle, and so I introduce the receptac es with their difierentcontents inalternation, until I have charged into the furnace chamber all of the material that temperature throughout the operrtion.

receptacles that each oreor oxid-containingreceptacle shall have a receptacle containing carbon on either side of it.

The gas vent above described'will in'the.

chargin of the furnace be guarded by a body. 0 v carbon-containing material, maintained at oxidizing temperature during the operation at a point ad'acent to the vent, so t at any enterin air w ich might otherwise reach and reoxi ize the furnace charge will as it enters give 'up its oxygen to this body of carbon-containin materlal. This result is effected by intro ucing last of all while charging the furnace a receptacle filled with carbon-containing material.

It will be understood that it is not essential that there be separate removable receptacles for each of the two substances which constitute the furnace charge. One substance may be char ed loose into the furnace chamber and t e other introduced in rece tacles.

Y en the furnace chamber has'thus been charged, I apply heat, until the. temperature of the chamber is brought approximately to '1000" C.,.and I maintain approximately At this temperature, the reaction occurs, the carbon 1n the carbon-containing vessels comblnes with the oxygen of the air within the chamber to form carbon monoxidwhich fills the chamber. Carbon monoxid in turn reacts with the tungsten oxid, taking oxygen from the tungsten oxid to form carbon dioxid; and the'carbon dioxid, as it is formed, in the 'resence of carbon, takes up more carbon to orm again carbon monoxid. Thus the operatlon goes on, the carbon combining wlth the oxygen of the tungsten oxid, until the su ply 0 oxygen thus available is substant1a y consumed; and, if the initial charge of tungsten oxidwas pure, the-re- 45 sultant body will be chemically pure metal- 110 tungsten.-

It will be observed from the foregoing de scription that my method is performed within a single uninterrupted chamber, and does not require the forcmg of currents of gas to and fro through the apparatus, but that on the contrary the reactlon occurs automatically when the method which I have described is followed.

In the foregoing specification I have described what theoretically are the reactions which take place within the furnace chamber. I do not limit my invention by, nor make it dependent upon, the absolute accuracy of that theor All that is capableof absolute detection these two bodies of tungsten oxid and carbon are brought t such a-t'em erature in a a closed chamber an maintaine at that temthe senses is that when burning at the escape end of the pipe 6 is a means to detect when the operation is completed, for the flame will contmue so long as carbon'monoxid' is generated, but when the tungsten has been wholly reduced and the supply of oxygen is gone, the flame will fail When the reduction is brought to completion, as will be detectedby the fall of the flame at the vent from the furnace chamber, the heat is cut ofi, and the furnace. and its ontents allowed to cool before the char e is drawn. During this time of coolingt e vent 6 will be plugged, to prevent the ingross of air, which otherwise freely entering would tend to reoxidize the product before it has become sufficiently cool to resist such oxidation.

Instead of allowing the excess of reducing gas to escape freely as described, I may utilize it to reduce a further body of oxid,'as illustrated in Fig. 3. The vent 6 of chamber '1 is there plugged, but the chamber opens through a valve-controlled passage 9 to another like chamber 1, also heated, and the carbon monoxid escaping into this second chamber there reacts with a further charge of oxid; and from chamber 1, any excess of gas escapes at the vent 6. The char e-in chamber 1 may be entirely of oxi or small quantities; furthermore there is practical difficulty in making the cap 3 secure If in operation it is subjected to a high degree of heat. When the furnace has cooled below the point where tungsten will take up oxygen, the charge may be drawn, and 1t will be found that the receptacles 1n wh1ch the tungsten oxid was charged contam metallic tungsten. I

It will be understood that instead of cooling the furnace after each operation, the chamber 1 may be made removable (as m-- dicated in Fig. 1) and drawn out 'on the completion of the operation, to be replaced by. another newly charged chamber.

The method which I have described (as additional body of carbon, bodily separated from the tungsten oxid-, which additional body of carbon shall continue the reduction, beyond the point where the carbon whlch 1s mingled with the tungsten oxid fails, and

shall carry on the operation from that point to the desired conclusion. Thus an excess of carbon in the finished product is avoided.

Instead of the yellow tungsten oxid of commerce (W0 I may in like manner use other tungsten oxids and compounds, as for instance, the scale which is formed upon,

and has been removed from the surface of tungsten steel, or other steel of which tungsten is a component. In such cas the operation is performed without substantial change from that described, reducing again tosuit'able metallic form the valuable tungsten containing scale or oxid.

The body of carbon, though preferably in form of finely divided charcoal, may be of any preferred form; finely divided coke may be employed, or even the drillings and filings I of irons which are rich in carbon, though I believe these substances less satisfactory.

It will be understood that the operation may be employed not only for obtaining metallic tungsten from the commercial oxid of tungsten, ut from the same material I may obtain lower oxids of tungsten in which the oxygen content relatively small. This will be accomplished by stopping the operation short of the point at wlnch metallic tungsten is obtained. At what point the operation shall be terminated to obtain the desired low oxid may be determined experimentally. Tungsten, like iron, combines with oxygen to form a series of oxids, each of which hasits reco ized character'and commercial uses, the ye low oxid (W0 being richest in oxygen. The blue oxid of tungsten, for example (W 0 may be ob tained by this process in relative y short time it has recognized commercial value as a pigment, and may be valuable for other uses.

i I have in this specification described apparatus for performin my improved method, but it will be un erstood that'I do not limit myself to the particular apparatus shown, it being only requisite that-the re- It will be understood too, as has been intimated in the body of the specification, that' the invention is not limited to the reduction of tungsten, but may be employed in the reduction of the oxids of tungsten alloys,

particularly in the reduction of the scale which forms upon tun ten steel; it may also be employed in the re uction of the oxids of other metals, and alloys of other metals, notably vanadium, molybdenum, chromium, and various steels containing these valuable materials, now largely used in tool steels.

It will of course be understood that .the temperature of the operation must be suited to the particular substance treated. Molybdenum oxid, for example, is volatile at a relatively low temperature.

The material of which the receptacles are formed in which the furnace charge is placed may vary, and of course the chamber wall may beof any preferred material. I have shown chamber walls formed of iron pipe; it is good material, since the temperature at which the operation is conducted is below the melting point of iron, and the gas within the chamber is during the operation a reducing gas. In'like manner, I preferably form the receptacles of wrought-iron, which in the operation is protected from oxidation by the reducing gas, but I may employ some other metal, as n1ckel for example, or I may employ non-metallic material, as for examplefire-clay, fused silica, or porcelain.

When chemically pure tungsten is my end, I preferably do not mix any carbon content with the tungsten oxid, for though the carbon might be wholly removed, some ash would surely remain, but where a less pure though commercially satisfactory tungsten is desired, I preferably mingle carbon with the charge of tungsten oxid and employ a separate body of carbon'inthe' manner already described, because in so doing I greatly shorten the time consumed in the operation. It will thus be seen that while my method is capable of giving me. chemically pure metal, it is so far within my control that I can roduce also lower from higher oxids; and urther, if it is desirable to have a prodnot containing carbon, I can secure the presence of that element in the desired amount. In some cases I have'found it desirable to introduce into the interior of the reducing chamber, while the operation is in progress supplemental quantities of a gas of a reducing nature, as for example natural gas.

These quantities of gas may be introduced from time to time as thegperation progresses. I have found that an excess of natural gas is undesirable in that,ittends to, produce a but in moderate quantities I have found it advanta eous in assisting the reduction. Gas may e introduced at the beginning of the operation if desired, to expel the air entirel and at the end of the operation to exclu e the air entirely.

M invention may be more fully understoo by explaining certain structural features of the furnace herein described.

It will be found that if tungsten ore or oxid to be reduced be placed in a compact mass within a crucible as in the ordinary procedure, and if the reducing operation be carried on in a furnace chamber of ordinary proportions, great difficulty will be experienced in excluding air, and under ordinary working conditions the product will be inferior because of the deleterious efi'ect of enterin air; relatively long intervals of time Wlll be consumed in the heating and cooling of the furnace which is economically a disadvantage in itself, and incidentally affords the opportunity for the ingress of air in larger and more deleterious quantities.

The furnace chamber which I employ is elongated in one dimension and made small in cross section, and the charge is in like manner extended to form a long body of relatively small thickness and with relatively great extent of exposed surface, thus, as the drawings show, and as already stated, the furnace chamber may consist of a len th of deposit of soot,

pipe of cast or wrought iron or stee, this pipe being of relatively great length compared with its diameter and lying preferably in horizontal position, and the receptacles for the charge may be boats of incomplete cylindrical form open at one side. The dimensions of the boat as explained above are such as to permit of their ready insertion and removal into and from the furnace chamber.

I am aware that it is not new to reduce metalsin furnace chambers having the form of a pipe; but in the prior use of furnace chambers of such form, so far as I am aware, it has been necessary to employ in combination with such furnace chambers, supplemental apparatus to generate reducing gases and drive such gases in streams through the furnace chamber. Now it is characteristic of my furnace, and herein lies my invention, to employ a prolonged furnace chamber and provide it w1th a vent to the atmosphere of relatively small size; in such an arrangement the reducing operation will proceed when the proper temperature is attained without the necessary assistance of any accessory part or instrumentality.

I have found that my improvements in furnace construction are such that in the preparation of tungsten for the makin of tungsten steel it is not necessary to fo low the process herein above described, but the old process herein above referred to, and

heretofore found defective and inadequate to give a tungsten of suflicient purity for stee -making, may be employed. I

By following. the process hereln above described a tungsten 0 great pur ty may be obtained in my furnace, the purity far exceeding that heretofore readily obtained for commercial purposes, and a purity reater than the conditions of steel manu acture require; but even the old process heretofore found faulty for steel-maklng may be practiced in my lmproved furnace; that 1s to say, the ore or oxid and the carbon-containing material may be mingled and charged in a single mass into the furnace and, proper proportions of iififigredients bein maintalned, a tungsten of su cient purity or steel-making ma be had. i

I claim herein as my 1nvent1on:

1. The herein described method of reducing metallic oxids which consists in inclosing within a single chamber a body of the oxi to be reduced, and a separate bod -of carbon-containing material, heating t e chamber to 'a temperature at which the carbon will unite with the oxygen of the oxid, and

maintaining that temperature until the desired reduction has been automatically effected.

2. The herein described method of reducing oxids of metals of the tungsten-vanadium-molybdenum-chromium group, which consists in inclosing within a single chamber a body of the oxid to be reduced, and a separate body of carbon-containing material, heating the chamber to a temperature at which the carbon will unite with the oxygen of the oxid, and maintaining that temperature until the desired reduction has been automatically eflected.

' ing tungsten oxid which consists in inclosing within a single chamber a body of the oxi to be reduced, and a separate body of carbon-containing material, heating the chamber to a temperature at which thecarbon will unite with the oxygen, and maintaining that temperature until the desired reduction has been automatically effected.

4. The herein described method of producin metallic tungsten which consists in maintaming at a reducing temperature a body of tungsten oxid, together with the body of carbon-containing material bodily separated from the body of tungsten oxid, within a single closed chamber, until the desired reduction is automatically accomplished.

5. The herein described method of reducing metallic oxids which consists in mingling a body of the oxids tobe reduced with the quantit of carbon insufficient in amount to effect re uction to the desired degree, and introducing such mixture together with a separate body of carbon-contalning material into a closed chamber, andmaintaming a rein introducing a bo ducing lit nperature until the desired reduction has been accomplished.

6, The herein described method of reducing the scale of tun ten steel which consists y of such scale together with a separate body of carbon-containing material into a single closed chamber, heating such chamber with such charge within it to a reducing temperature, and maintaining such temperature until the desired re-- action is automatically accom lished. 7. The herein descrlbed met od of reducing metallic oxids which consists in inclosing with a chamber a body of the duced, and-a separate body of carbon-containing material, heatingthe chamber to a temperature at which the carbom will unite with the oxygen of the oxid, intro'ducingl into the chamber a body of reducing gas, I

oxid to be re- 7 and maintaining the chamber at temperature until the desired reduction has been effected.

and causing the gaseous by-products of reduction to pass to the atmosphere through a prolongation of the closed chamber which is subjected toa temperature lower than the reduction temperature of the main portion thereof. i I

In testimony whereof, I have hereunto set my. hand. 7

CHARLES MORRIS JOHNSON. Witnesses:

CHARLES BARNETT. FRIEDA E. W'oLFn a reducing 20

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