US1092936A - Process for purifying aluminum and its alloys. - Google Patents

Description

uninn STATES PAT GRnNviLLn MELLEN, or EAST ORANGE, NEW JERSEY, ASSIGNOIR, or ONE-HALF r0 7 PROCESS FOR PURIFYING ALUMINUM ANDITS ALLOYS.

Specification of Letters Patent.

No Drawing. Original application filed'June 26, 1912, Serial No. 706,041.

filed. October 10, 1912. Serial No. 725,059.

' UNITED ALUMINUM INGO'I COMPANY, A CORPORATION OF NEW ,YORK.

Divided and this application purifying molten aluminum or its alloys from impurities, such as aluminum oxid,

and is a division of my application Serial Number 706,041, filed June 26, 1912. The impurities are largely aluminum oxid, resulting from the superficial oxidation of the metalwhen molten; said oxids being stirred in the mass of the metal and mechanically held therein.

If a material which is non-oxidizing, and which boils at a temperature lower than the melting-point of aluminum, and of lower specific gravity than aluminum, be injected into the ower level of the molten metal, the vapors on arising through the metal will have the result of carrying the impurities to the surface where they may dissolve or combine with a flux on the surface; or if such impurities chemically or mechanically combine with the vaporizable material added, the resulting compound or mixture will rise to the surface, from which it may be removed in any suitable 'manner. I have found that the addition of sulfur to molten aluminum or its alloys has this property; and on injecting solid sulfur to the bottom of a container filled with the molten metal or alloy,'t-he sulfur boils and its vapors passing through the molten metal stir it vigorously,v combining with the impurities either mechanically or chemically and carry them to the surface, from which they may be removed. It is advantageous to also add a fusible material having a low specific gravity which acts as a flux and serves to mechanically entrain or to chemically combine with the impurities, carrying them to the surface, from which they may be removed. I have further found that by adding sodium chlorid (salt) to molten sulfur, thoroughly stirring,

and casting into rods, I obtain a material particularly adapted to remove the impurities above referred to. A rod of this material is plunged into the molten metal or alloy, and stirred, the salt melting and the sulfur boiling from the surface of the rod, the sulfur vapors bubbling through the molten metal, while the molten salt passes up more slowly. The combined action of the sulfur "apors and salt is to free the metal from its impurities by carrying them to the surface, where they form. a flux or scoria with the salt, or with any other flux present, and from which they can readily be removed. The treatment ofthe molten metal or alloy is of greater or less duration depending upon the quantity of impurities present. The rod of salt and sulfur may contain from 0 to 70 per cent. of salt, an excess of salt or away; its vapors causing. violent ebullition of the mass of metal, thoroughly agitating it,

and carrying its impurities to the surface.

Instead of sodium chlorid, I may melt together sulfur and sodium sulfid. I

.To the surface of the molten metal maybe added a flux such as sodium meta-phosphate or zinc chlorid which fuses readily and combines with the salt and sulfur scoria or Patented Apr. 14, ram.

dross; it will further serve to effect a ready separation ofthe scoria from the molten metal.

I have found that aluminumscrap from different sources, such as scrap sheet, turnings, and castings that have been corroded by use and exposureto air and water, and which, if melted without any purifying agent, would produce a very impure metal,

will, upon being treated with the purifying agency herein described, produce a metal equal in every way to new and hitherto un- I used metal.

I claim: 1. The process of purifying aluminum 3. The process of purifying aluminum and its alloys, comprising adding to the and its alloys, comprising subjecting the I melted metal to a sulfur-containing purifymelted metal to the action of sulfur vapors l ing agent, and reacting upon theimpurities bubbling therethrough. in the melted metal with the sulfur in the 4:. The process of purifying aluminum sulfur-containing agent.

5 and its alloys, comprising adding sulfur and In testimony whereof I afiix my signature 15 a fusible solid to the molten metal, said solid in presence of two witnesses. having a lower specific gravity than the GRENVILLEMELLEN. metal. Witnesses:

5. The processof purifying aluminum JOHN O.B1cELow, 10 and its alloys, comprising subjecting the STUART A. YOUNG.