US431912A - Ctjet netto - Google Patents

Description

(No Model.)

O. N ETTO. rnoczss OF MAKING ALUMINIUM.

Patented July 8, 1890.

UNITED STATES PATENT OFFICE.

CURT NETTO, OF DRESDEN, GERMANY.

PROCESS OF MAKING ALUMINIUM.

SPECIFICATION forming part of Letters Patent No. 431,912, dated July 8, 1890.

Application filed July 21,1887. Serial No. 244,861. (No specimens.) Patented in England March 21, 1887, No.4,228; in Germany March 26,1887,N0. 45,198; in Belgium March 26, 1887, No. 76,860; in France March 26, 1887, No.182,464,' in Norway June 14, 1887,110. 668: in Sweden June 14, 1887,1510. 1,206;in Luxemburg June 15, 1887,1510. 854 in Italy June 30,1887, XLIII, 232,XXI, 21,838 in Spain August 24, 1887,1To. 7,108, and in Austria-Hungary November 29,1888, No. 21,211 and To all whom, it may concern:

Be it known that I, CURT NETTO, engineer, a subject of the King of Saxony, residing at Dresden, Saxony, German Empire, have invented certain new and useful Improvements in the Process of Making Aluminium, (for which I have obtained Letters Patent as follows: in Germany Mai-ch26, 1887, No. 15,198; in Belgium March 26, 1887, No. 76,860; in France March 26,1887, No. 182,464, and June 9, 1887, N0.182,4:64:; in Great Britain March 21, 1887, No. 4,228; in Italy June 30, 1887, No. XLIII, 232, XXI, 21,838; in Luxemburg June 15, 1887, No. 854; in Norway June 14, 1887, No. 668 in Austria-Hungary November 29, 1888, No. 21,211, and No. 39,313; in Sweden June 14, 1887, No. 1,206, and in Spain August 2 1, 1887 No. 7,108); andI do hereby declare the following to be afull,clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification, in which- Figurel is a plan view, partiallyin section, of the dipping-rod with a piece of potassium thereon. Fig. 2 is a side, and Fig. 3 a top, view of the ladle or cover. Fig. 4 is a vertical sectional view of a crucible with the dipping-rod and ladle therein; and Fig. 5, a horizontal sectional View of the same, taken on the line A B of Fig. 4.

The present invention has relation to processes for the manufacture of aluminium; and it consists in a process for manufacturing aluminium from cryolite by means of the alkaline metals, asherein after fullydescribed, and specifically claimed.

As early as 1855 Percy, Rose, WVoehler, and Deville proposed methods of manufacturing aluminium from cryolite by means of sodium. Though this mineral is found in nature in great quantities, it has not been sufficiently employed for the manufacture 011 a commercial scale of aluminium, for the reason that the chloride of aluminium is so (llfllGlllt to produce that its double combination with chloride of sodium has generally been used. The reason for this is that the reduction of cryolite by means of alkaline metals is subject to the objection that its melting-point, being even in the presence of a suitable flux between 750 and 800 centigrade, surpasses the evaporatingpoint of sodium and also of potassium. It, therefore,

as in the Deville process, a charge of cryolite flux and alkaline metals is heated,the better part of the latter escapes in vapor before the temperature is reached necessary for the melting or the reduction of the cryolite. The profit with reference to the. sodium employed is of course thereby much reduced. This Deville himself corroborates by the following sentence: I have verified all of Mr. Roses observations, and I agree with him concerning the return of metal, which I have always found very small. (Richards, manufacturer of aluminium, Philadelphia, 1887, pages 119 and 120.)

The object of my invention is to effect the melting of the cryolite contrary to the De ville process, not in the presence of the alkaline metal, but (and this is the characteristic point of the invention) to melt the cryolite to be decomposed and then to add the transferring metal. This process offers, also, the great advantage that aluminium may be obtained on a large scale from cryolite by means of sodium, and that the great loss of this metal by evaporation, now inevitable, is avoided.

The process can be carried into effect in the following manner: The cryolite, together with the flux, is melted in a crucible, and a piece of solid sodium or potassium is suddenly introduced and forced to the bottom of the crucible by means of an iron rod, to which the metal has been attached. The alkaline metal being excluded from the air and surrounded by the molten cryolite, which is now at the temperature of reduction of alun1inium, it cannot burn. It will, on the contrary, producean immediate change or reduction of the fluoride of aluminium contained in a latent state in the cryolite. The introduction of the alkaline metal into the molten mass is not dangerous when care has been taken that it is quite dry, free of inner hollow. spaces, and of adhering or other particles of carburet of hydrogen. When the change is finished, as soon as the mass commences to flow more quietly the contents of the crucible are thrown into a suitable conical mold narrowing toward the bottom, where they are allowed to cool. Thereupon the mold is turned upside down, and the regulus of aluminium, having gathered at the bottom, is separated from the adhering scoria by striking it with a hammer. Instead of effecting the fusion of the cryolite mixed with flux (it is best to take one hundred parts, by weight, of cryolite to one hundred parts of chloride of sodium as flux) and the reduction in the same vessel, I can effect the melting in one and the reduction in a separate vessel. In this case I can make use of melting devices which will allow the melting of great quantities of cryolite, thereby securing a great economy in fuel, crucibles, and labor. To effect this I can make use of reverberatory furnaces, on the bottom of which the charge of cryolite is melted, after having covered it with a material free from silicon. thin it is drawn off into a vessel similar to a casting-pan having an inside lining of basic material, and metallic sodium or potassium in the form of a cone attached to an iron rod is plunged to the bottom, whereupon a lively reaction takes place, considerable heat being developed, so that the mass without any further heating reaches atemperature necessary to the completion of the reduction. In a few seconds the alkaline metal is consumed, and this operation is repeated with new quantities of sodium or potassium until the theoretical quantity (to one hundred parts, by weight, of cryolite about thirty-three parts of sodium or fifty-six parts of potassium) is added. WVhen the alkaline metal is not submerged fast enough in the bath or in the molten cryolite, some of the melting alkaline metal being specifically lighter, comes to the surface, where it would uselessly burn away in contact with the air and be lost. In this case I make use As soon as the mass is liquid and' of a suitable dipper consisting of a concave iron head of a somewhat smaller diameter than that of the reducing-vessel. This head is provided in the center of its convex side with an iron rod, so that it may be, after the introduction of the alkaline metal, plunged into the bath to any depth with its concave side downward in order to press down the coming to the surface.

As soon as the proper quantity of sodium or of potassium is introduced into the molten cryolite the contents of the reducing-vessel are thrown into a reservoir, where it can cool and wherein the produced aluminium gathers in a large mass. The alkaline metal may be also introduced in a liquid state into the previously-melted mass of cyolite without departing from the spirit of my invention, or an alloy of sodium and potassium can be employed in place of using these metals separately.

As the liquid alkaline metal could not be carried to the bottom of the molten mass by means of a rod, other means must be employed to mix the specifically-lighter alkaline metal with the mass of cryolite. For this purpose I can introduce the liquid alkaline metal into the bath near the bottom of the reducing metal by means of pressure or mix it by stirring, the most important point of the process being that the cryolite is heated or melted and is afterward while in a liquid state suddenly mixed with the alkaline metal.

Having described my invention, I claim- The herein-described process for the manufacture of aluminium from cryolite by the use of the alkaline metals, such as potassium or sodium, which consists in first melting the cryolite with its flux and then suddenly introducing the alkaline metal or metals into the molten mass, substantially as described. In testimony whereof I affix my signature in presence of two witnesses.

OURT NETTO.

\Vitnesses:

ROBT. M. HOOPER, PIERRE ERNEST EIPISY.

melting alkaline'metal and to prevent it from

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