US1922037A - Treatment of metals - Google Patents

Description

Patented Aug. 15, 1933 TREATMENT OF METALS Charles Hardy, Pelham Hardy Metallurgical of Delaware Manor, N. Y., assignor to Company, a Corporation No Drawing. Application June 28, 1930. Seria 8 Claims.

This invention relates to the treatment of 'metals and has for its object certain improvements in the treatment of metals. The inventionrelates more particularly to the treatment of alkali metals in conjunctionwith other metals,

such as iron and its alloys.

Certain alkali metals are found to be effective deoxidizers, desulfurizers, decarbanizers and the like. Such alkali metals as calcium, magnesium,

10 lithium, barium and potassium have been employed for this purpose. These metals have also been employed to make alloys with certain other metals. When employed as deoxidizers, desulfurizers or decarbonizers, these alkali metals are diflicult to use because of their high reactivity. In the case of calcium, for example, its'rate of reaction is so rapid that it cannot satisfactorily be controlled when the metal is added as such to another metal in molten form as a deoxidizer,

desulfurizer or decarbonizer. When these alkali metals are employed to form alloys with other metals, a very substantial amount of the alkali metals are lost because of the rapidity with which they take on oxygen. Moreover, un-homogeneous alloys are formed.

- As a result of my investigations, I have determined that alkali metals may be suitably treated to place them in condition to be employed as deoxidizers, desulfurizers, decarbonizers, dehydrogenators, denitrogenators and the like. In

such manner, I substantially avoid the objections heretofore encountered when employing these metals in their metallic form. These alkali metals, moreover, when so treated are put into form for alloying with other metals without substantia'l loss due to oxidation, and in a manner to provide substantially homogeneous alloys.

In accordance with the practice of the present invention, the alkali metal, 'or metals, is appropriately admixed with-another metal ormetals. The mixture preferably consists of an agglomeration of the alkali metal with the other metal or metals.

Various methods may be employed in order to obtain an appropriate mechanical admixture of the metals to be employed in the practice of the invention. Thus, the alkali metal or metals may first be melted to form a molten bath. The other metal or metals is then appropriately mixed with th moltenlalkali metal. This mixture may be suitably prepared by introducing the other metal or metals in powdered lump or other suitable solid form. If the mixture is promptly stirred,

and then withdrawn from the furnace, the freezing metal closely holds the metallic elements forming the mixture.

For example, a specific quantity of metallic calcium was melted in an ordinary crucible, preferably under a protective cover. Iron in the form of solid powder was then introduced into the body of molten calcium, the mixture being stirred during the process of addition. After thorough mixing and agitation, the mixture was withdrawn from the furnace. The freezing metal closely held the metallic elements forming the mixture. If this process of mixing is carefully conducted, the admixed metals will agglomerate to form a relatively porous mass. Moreover, the metals will ,be substantially unfused. That is to say, the agglomerated mass consists of a mechanical mixture rather than a fused alloy. In the instant example, the agglomerated lumps held their shape and form without disintegration. The lumps could in fact be rubbed and made gradually to crumble.

Another procedure to form an agglomerated 'mass of the alkali metal or metals with another metal or metals is to take the alkali metal or metals in the form of shavings, powder, strips or other suitable solid form, and the other metal or metals in the same form, thoroughly mix them and press, or extrude, or by other mechanical means form the admixture into briquettes or agglomerates of any suitable shape.

For example, I have taken metallic calcium shavings and sponge iron, and after thoroughly mixing the same secured under pressure a briquette. The irregular form of the particles making up the mixture allows the formation of a briquette under pressure without the admixture of a binder. A suitable binder may of course' be employed if that is found desirable.

I When the alkali metal, or metals, is appropriately agglomerated or briquetted with another metal, or metals, as indicated above, to form what may in effect be considered as a mechanical mixture, the alkali metal or metals is substantially evenly distributed throughout the agglomerated mass. The larger the agglomerates, the better the alkali metal, or metals, locked in the interior of the agglomerate is protected from loss due to oxidation and the like. In other words, the alkali metal or metals, is suitably provided with a protective environment that peculiarly fits it for subsequent use.

When the alkali metal, or metals, is subjected to the preparatory treatment procedure outlined above, it is in an excellent condition to be used as a decarbonizing, 'desulfurizing, dehydrogenating, denitrogenating, deoxidizing agent and the like. For example, the agglomerated alkali metal, or metals, may be appropriately employed for the refining of metal or metal alloys, such as iron and its numerous alloys; or of other materials, for example, when it is desired to effect the removal of hydrogen, nitrogen and the like. Thus, the carbon content of iron may be materially lowered, when the iron in a molten state is subjected to a purification treatment with agglomerates of a suitable alkali metal with another metal, such as iron. Agglomerates of metallic calcium with iron may be suitably mixed with a molten bath of iron to be purified. The agglomerates are soon melted, and the available calcium is distributed throughout the body of molten iron. Due to its high reactivity, the calcium promptly combines with the carbon contaminant of the iron to form calcium carbide. The calcium carbide eventually reaches the surface of the molten metal bath to unite with'the slag resting thereon.

The problem of lowering the carbon content of iron in order to make certain ferro-alloys, such as ferro-chrome, ferro-manganese, ferro-nickel and the like, alone or in combination with one another, has been one of considerable concern. Such alloys are deemed particularly useful in order to obtain a substantially stainless iron or steel product.

In the preparation of ferro-chrome, iron or steel, for example, chromium is added to the iron. The carbon content of the ferro-chrome alloy is usually lowered by an oxidation process; for example, by the introduction into the body of molten ferro-chrome of an oxide of iron, or the like. As a result of this purification step, the carbon is oxidized, but a substantial part of the chromium is also oxidized. In fact, at normal refining temperatures, the chromium combines with the oxygen made available by theoxides of iron more rapidly than does the carbon. The net result is to cause a considerable portion of the chromium to enter the slag on the top surface of the molten metal as an oxide of chromium. Special steps must then be taken to cause the chromium in the slag to passdown into the body of molten iron. Thus, a reducing agent is suitably admixed with the slag as it rests on the top surface, in order to effect aconversion 'of the chromium oxide to metallic chromium, which may then be made to enter the molten body of iron below.

What has been said above with respect to ferrochrome applies equally well and for the most part to otherferro-alloys, such as ferro-magnanese, ferro-nickel or suitable combinations of these and other metals.

According to the practice of the present invention, such ferro-alloys may be subjected to suitable treatment'process with a purifying agent made in accordance with the principles outlined above. For'example, in the case of a ferro-chrome alloy containing objectionable amounts of carbon, a suitable amount of agglomerated calcium and iron may be introduced in solid form into a molten bath of the ferro-chrome. In conducting this purification step, a protective blanket or layer is advantageously provided on the top surface of the molten bath to keep out oxidizing influences. Any of the usual fluxes or 'slags may be employed for this purpose. When the molten l bath with the agglomerates of calcium and iron is suitably agitated and mixed, the calcium rapid lyand selectively combines with the carbon in the alloy to' form calcium carbide. The calcium carbide ultimately finds it way to the surface and joins with the slag. The net result is to produce a ferro-chrome alloy with a materially lowered carbon content.

Since the carbon content of the ferro-chrome alloy to be treated is at least known approximately, the agglomerated calcium and iron added to the molten bath may be appropriately regulated in order to take out the desired amount of carbon. Thus, the more carbon it is desired to remove from the molten ferro-chrome alloy, the

more calcium is introduced throughout the body of molten metal. It will thus be seen that the agglomerated lumps of calcium and-iron may in the first instance be made in such a manner as to contain regulated amounts of colcium'.

In another practice of the invention, the prepared alkali metal or metals is first introduced into a mold in which the molten metal is to be poured, The poured metal at once covers and mixes with the agglomerated or. briquetted alkali metal, thus subjecting itself to a purification treatment. For this purpose, the agglomerates or briquettes of alkali metal, such as calcium admixed with iron,

may be made to have a definite calcium content,-

so that the molten iron poured into a given mold may be brought into contact with a given and predetermined amount of calcium; that amount of calcium being deemed sufficient to efiect the desired purification.

In this specificationand the appended claims, the term highly reactive metal is intended to cover the commonly called alkali metals (such as'lithium, sodium, potassium, etc.) as well as the commonly called alkali-earth metals (such as magnesium, calcium, strontium, barium etc.)

The principles of the invention are particularly applicable to calcium, because of that metals excellent characteristics for the purposes in hand and its availabality in metallic form at reasonably low cost.

The metal associated with the calcium (or other alkali metal) in the practice of the present invention will depend to some extent .upon the subsequent use to which the agglomerated or briquetted mixture of metals is to be put. When treating iron, steel, ferro-alloys and the like, it is preferable to associate iron with the calcium. When treating bronze or similar copper-containing alloys, it is preferable to form the agglomerated or briquetted mixture of the invention of copper and calcium (or equivalent alkali metal). Similarly, when treating aluminum, the calcium (or other alkali metal) will preferably be agglomerated or briquetted-with aluminum, and when treating zinc or zinc-containing alloys, the calcium (or other alkali metal) may advantageously be agglomerated or briquetted with zinc. In other words, the calcium (or other alkali metal) should be agglomerated or briquetted with such other metal as will introduce no objectionable metallic constituent into the particular metal or alloy tov be treated. Any metal or alloy that may readily be reduced to the form of a powder, or granules or shavings may thus be associated withthe alkali metal in accordance with the principle of'this invention.

From what has been said above, it will be clear that the principles of the present inventionmay be practically applied in a large number of ways, and. with a relatively large number of metals, alloys, or other materials.

I claim:

l. The method of treating an alkaline earth metal in the form ofcalcium which comprises agglomerating the metallic calcium in molten form to yield an essentially mechanical admixture of the metals whereby the metals are not alloyed with another metal or metals in solid and sub-divided form.

2. The method of treating an alkaline earth metal in the form of calcium which comprises agglomerating the metallic calcium while molten under a protective covering with another metal or metals in solid and sub-divided form to yield an essentially mechanical admixture of the metals whereby the metals are not alloyed.

3. The method of treating an alkaline earth metal in. the form of calcium which comprises agglomerating the metallic calcium in molten form with iron in solid and subdivided form to yield an essentially mechanical admixture of the metals whereby the metals are not alloyed.

4. The method of treating an alkaline earth metal in the formof calcium which comprises agglomerating the metallic calcium in molten form with sponge iron'in solid and sub-divided form to yield an essentially mechanical admixture of the metals whereby the metals are not alloyed.

5. The method of treating an alkaline earth metal or metals in the form of metallic calcium which comprises heating metallic calcium to form a molten bath, adding another metal or metals in solid form to said calcium metal bath, and agwhich comprises heating the metallic calcium to form a molten bath, adding iron in solid form to said calcium metal bath, and agglomerating the mixture of metals by stirring to yield an essentially mechanical admixture of the metals whereby the metals are 'not alloyed.

7. The method of treating an alkaline earth metal or metals in the form of metallic calcium which comprises heating the metallic calcium to form a molten bath, adding'sponge iron in solid form to said calcium metal bath, and agglomerating the mixture of metals by stirring to yield an essentially mechanical admixture of the metals whereby the metals are not alloyed.

8. The method of treating highly reactive metals which comprises agglomerating at least one of the metals from the group consisting of lithium, sodium, potassium, magnesium, calcium, strontium and barium, while in molten form with a relatively less or non-reactive metal from the group consisting of iron, aluminum, copper and zinc while in solid form to yield an essentially mechanical admixture of the metals, whereby the metals are not alloyed.

CHARLES HARDY.

CERTIFICATE OF CORRECTION.

Patent No. 1.922, 037.

August 15, 1933.

CHARLES HARDY.

It is hereby certified that error appears in the printed specifications of the above numbered patent requiring correction as follows: Page 2, line 92, for

"colcium" read calcium; and line 116, for "availabality" read availability; page claim 1, strike out the words "to yield an essentially mechanical admixture of the metals whereby the metals are not alloyed" and insert 3, lines 3, 4 and 5,

the same after "form" in line 6, 'of same claim; and that the said Letters Patent should be read with these corrections therein that the same may conform to'the record of the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1933.

(Seal) F. M. Hopkins Acting Commissioner of Patents.