US845819A - Treatment of alloys to alter their composition. - Google Patents

Description

UN ITED- STATES,"

ROBERTS OF NEW roan, N. Y., ASSIGNOR OF ONE-HALF TQ JAMES TURNER MOREHEAD, on NEW YORK, N.'Y.

ISAIAH L.

PATENT OFFICE.

V TRE TMENT OF ALLOYS T 'ALTER'THEIR comPoslrlou Application filed July 23,

Specification of Letters Patent.

1904. Serial No. 217.797.

Patented March 5, 1907.

To all whmn it inrty concern:

Be it known that I, ISAIAH L. ROBERTS, a citizen of the United States, residing at New York, in the county of Kings, State of New York, have invented a certain new and useful Treatment of Metallic Alloys to Alter Their Composition, of which the following is a specification.

In various arts it is frequently found desirable to remove part or all of one or more constituents from an alloy, mixture, or compound. For example, in certain processes of extractingv meta from ores the metal is obtained in a crude state -that is, containing one or more other substances. .As an in stance of such a case crude copper may be noted, which usually contains a certain amount of iron. Ifpure metal is desired, it

therefore becomes necessary to get rid of the impurities in the crude product, and for this purpose a great number of methods have been devised. In other instances it, may be desirable to substitute another metal, or metals for the impurities in the crude prod uct. mention the manufacture of chrome steel, nickel steel, & c. Here it is advantageous for economical reasons to produce the steel direct-from the crude iron by removing the undesirable impurities, proportioning the amount of carbon by removal or addition,

and adding the proper quantity of the alloying metal. In still other cases it may be' at timesdesirable to remove part or all of a constituent from an artificial alloy to alter its quantitative composition, or to substitute a foreign metal for one already present in the alloy to vary its qualitative composition.

The object of my present invention is to provide a method by which such removals or substitutions ma be effected, and it will therefore be seen that my invention has a wide range of application.

In practicing my method I add to the molten metal, alley, 01' compound in which the desired change is to be made a molten com' pound containing a substance which has a greater ailimt for the constituent which is to be remove than have the other constit J.-

56 outs of the alloy or compound in which the said constituent exists. -The compound which I use with the material to be treated may be a salt, a mixture of salts, an oxid,

As an example of this case I may 1 metal tobe treated becomes molten. 'fusibility of the flux depends 'upon its quanor a mixture of one or more oxids and one or 'more salts. I prefer to use fluorids for this.

Eprpose, for thereason that they can stand gh tem eratures without being volatilized but chlor1ds and bromids may be used, if de sired, and also other salts provided the nonmetallic element of the salt has a greater afiinity for the elementto be removed from the given material than the saidrion-metallic element has for the substance with which it is already combined, or stated otherwise, the metal of the saltmust be less basic than the element -to be'removed from the given crude metal, alloy, or compound. Under certain circumstances oxids may be employed, depending on the particular object to be attained; as will appear more clearly hereinafter.

A suitable flux must be provided to form a I slag in which the new compound, produced by the substitution, may float, and for this purpose I prefer to use a mixture of calcium and sodium fluorids. The flux also serves as a solvent for the oxide or salts which .are used as the reagents in the various applications of -my process. It will of course be understood that other fluxes may be employed, depending upon the conditions in a particular case; but the fiiix mentioned isnot only comparatively inexpensive, but its constituent salts are extremely stable, and therefore with the possible exception of a very few cases Wlll remain unchanged in the variousap lica-' tions of my methodthat is to say, t e sodium (or potassium, which is equivalent" fluorids are not affected the'reto) and calcium and by-the material treated, and vice versa,

therefore'they are not a source of impurity for the final product. The fluorids are preferable for the additional reason that they can stand a higher temperature without volatilizing than the bromids or chlorids; but '95 where the temperature necessary to keep the materials molten is low the flux may be composed of bromids, chloride, for other salts, desired. 'As a rule aflux should be chosen which fusesat the temperature at which the 'titative composition; but as the diiferences ingredientsof the ux arewell understood they need not be recited here. general it The produced by 'varyin the-proportions of the other.

. treatment.

' determined.

may be said that the more mobile the flux the more rapid the reactions will be.

total quantity of flux used is largely immaterial; but sufficient should be used to dis solve the reagent and take up the compound produced thereby from the material under A quantity of flux in excess of such amount does no harm, though more heat will be required to fuse it and keep it molten than where a smaller quantity is used.

In the practical application of the invention I prefer first to melt the alloy or com pound which .is to be treated and then add the flux containing the oxid or salt required to effect the desired result. Instead of following this procedure all the materials may be melted together or one added after an- In general they may be brought together in any convenient way and in any convenient apparatus. During the process samples may be taken from the mixture, by which the progress of the operation may be The time required for the completion of the process will of course vary with the naturcof the material under treatment and also the quantities used. The reactions will be facilitated by occasional or constant agitation, as will be readily understood. It will, as a rule, be found advisable to use more of the reagents than is calledfor by the valences of the substances which react to insure that substantially all of the substance to be taken from the material treated will be removed, where such complete removal is ,desired.

Ilaving now explained my invention in broad terms, several of its practical applications may now' be described. One instance in which it will be found of value is the purification of raw or crude copper. As pre viously stated, this product frequently contains iron in greater or less quantities, an impurity which may be readily removed by my process.

The operation is as follows: The copper is melted 1na suitable crucible, and the flux mentioned above, containing a suflicient cfipantity of copper fluorid, is then added, and t e whole agitatcd- The amount of copper fluorid used depends upon the amount of iron to be removed; but if all the iron is to be eliminated, as will usually'be the case, the fluorid'should be in excess of-that necessary. to provide fluorin sufficient to take up all the iron. The result is that the iron, being more basic .to fluorin than copper is, or, stated otherwise, the fluorin having, a greater aflinity for iron than for copper, the copper in the fluorid contained in the flux is released and iron'from' the crude coppertakes its place Zinc, cadmium, and anybther metal for which fluorin has a stronger affinity than for copper may be removed in the same .way,

either singly or simultaneously. An oxid of copper may be used instead of the fluorid, if

The

desired, or a mixture of oxid and fluorid. The iron, zinc, 620., will then be removed as oxids or as oxids and fluorids.

The application of the invention to the purification of crude or impure metals is of course not limited to copper or to zinc and cadmium as impurities,nor are metals the only substances which can be removed in this way. Carbon, phosphorus, and sulfur may be removed by my method; but these elements, and also arsenic, can be removed only by oxidation, and the reagent must' therefore be an oxid of a metal for which oxygen has less afiinit-y than for the particular element or elements to be eliminated. The metal with which the oxygen was first in combination will then take the place of the carbon, sulfur, &c. If this metal of the reagent is not the same as that which is to be purified, the product will of course be amixture or an alloy of the two.

My invention will also find an important steelfor example, by melting common castiron with a suitable flux (such as that previouslymentioned) containing an oxid of nickel'such substances in the iron, as carbon, sulfur, phosphorus, arsenic, &c., will be oxidized by oxygen from the nickel oxid and will be taken up by theflux, while the metallic nickel thus freed will alloy with the iron. In the same way chromium, titanium, manganese, tungsten, and other metals may be substituted for other substances in the iron. Y

The product is then nickel steel, chrome steel, &e., as the case may be, the amount of carbon therein being regulated by removing,

more or less from the quantity thereof present in the iron. 1 j

If it is desired to remove sodium from an aluminium-sodium alloy, it may be effected by using aluminium fluorid in a suit able fluxas, for example, that described hereinbefore composed of a mixture of calcium and sodium fluorids. Then the fluorin in the aluminium fluorid will take up the sodium from the aluminium-sodium alloy, releasing the aluminiumewith which it was in-combination, or if fluorid ofmagnesium is used to remove the sodium the product will be an alloy of alumi nium and magnesium, since the sodium and magnesium will exchange places. If it is desired to remove sodium from an alloy with zinc, the fluorid of magnesium may be used, and the product will bean alloy of zinc and magnesium with the sodium in the flux as a fluorid. The same is true in the case of an alloy of copper, aluminium, zinc, and sodium t-hat is, the magnesium in the fluorid will be released and the sodium taken up.

The alloy of aluminium and magnesium mentioned above is known as niagnalium. It possesses many valuable properties, but at the present time, however, it is costly, since the method heretofore employed for making it requires the use of metallic magnesium,

is furnished by a salt 'of that metal-as, for

exa1nple, nagnesium fluorid, which iscomparatively cheap. This salt'is added to a molten bath of. aluminium and some other element which has a greater affinity for fiuorin than magnesium has. l/Vhereupon the magnesium and the said other metal change places, leaving magnalium as the product. If the aluminium as produced for the purpose does not contain this other metal or not enough of 1t to release the desired amount of magnesium from the iluorid, then the necessary amount of the more basic metal must be added to the aluminium. Sodium being both cheap and very effective, I prefer to use it for this purpose; but other metals may be employedas, for example, potassium.

It will now be seen that by my method a.

great-variety of alloys may be made without the necessity of first having the constituents thereof all in themetallic form. If the metallic ingredient or ingredients of the alloy (as the copper, iron, aluminium, &c., mentioned in the preceding examples of the :mplication of my invention) do not contain a metal more basic than that which is to be snbsti tuted therefor, such a more basic metal must be added to the metallic ingredient, whereupon the more basic metal ust added,

which if it remained would be an impurity in the product, will change places with the metal which is to be one of the constituents of the alloy and which is supplied by an oxid or salt thereof in the flux. ample, the alloy'of iron and nickel may be again referred-to. If the iron does not contain enough carbon, sulfur, or other impurities to combine with so much oxygen of the nickel oxid as is necessary to release the amount of nickel desired for the alloy, it is necessary to supply the iron with what might be called an artiticial impurity, which of eourse must be more basic (to the non-metallic component of the nickel compound used) than nickel itself is. For instance, aluminium is rery convenient for such purpose, especially in the present ex ample, since it has great aliinity for oxygen,-

and its oxidation also liberates a considerable uantiity of heat, thus-effecting a saving of line. The aluminium being added to the iron, the carbon and aluminium will both be removed by the liberating of the desired amount of nickel. The product will then be the desired alloy of iron and nickel. of using oxid of nickel in this (raise -that is, where aluminium is addedthe fluorid may be used; but the carbon is to be removed some oxid of nickel must also be used, since As a further ex- Instead carboncan be removed only by oxidationil" Carbon itselfanay be added as the artificial impurity, instead of aluminium; but the quantity of aluminium required is small and inexpensive and produces more-heat in the process, so I prefer that metal. Sodium and potassium, possessing extraordinary affinity for the halogens in fact, greater allinity therefor than is possessed by almost all other metals-are very effective for the purpose of liberating the metal of an oxid or halo en salt in my process, and by the use of eit .ler as explained a great variety of alloys may be cheaply and easily made.

What I claim is l. The. method of varying the composition of a metallic alloy or mixture, which consists in treating the same in the molten state with a flux composed of. iluorids and containing a compound of a metal less basic than the e ement to be removed from the. alley or mixture, asset forth.

2. The method of varying the composition f a metallic alloy or mixture, which consists in treating the same in the molten state with a tlux composed of salts of sodium and calcium and containing a compound of a metal less basic than the element to be removed from the alley or mixture, as set forth. 7

3. The method of varying the composition of a metallic alloy or mixture, which consists in treating the same in the molten state with a flux composed of iluorids of sodium and calcium and containing a compound of a metal less basic than the element to be removed from the alloy or mixture, as set forth.

4. The method of removing a metal from an alloy or mixture and substituting another and less basic metal therefor, which consists in reducing the alloy or mixture to the molten state, and treating the same with a compound of the metal to be substituted, in a flux composed of salts of sodium and calcium as set forth.

5. The method of making an alloy of- -alum inlum and m agnesium, which consists in treating, with a flux containing a salt of magneslum, a molten nuxture of aluminium and a substance more basic than magnesium,

7. The method of making an alloy of aluminium and magnesium, which consists in treating a molten mixture of aluminium and sodium with a flux containing magnesium fluorid, as set forth. f

ISAIAII L. ROBERTS.

\Vitnesses: 1

.Tons C. KERR, S. S. DUNIIAM.