US1816007A - Refining molten metals - Google Patents

Description

Patented July 28, 1931 UNITED STATES PATENT OFFICE GEORGE S. EVANS, OF 'BRONXVILLE, NEW YORK, ASSIGNOB. TO THE MATHIESON ALKALI WORKS, INC., OF NEW YORK, 1\T.'Y., A CORPORATION OF NEW YORK BEFINING MOLTEN METALS No Drawing.

This invention relates to improvements in the refining of molten metals. The invention is of special value and application in connection with the refining of ferrous met- }5 als with soda ash refining agents, but it is also 'useful in connection with the refining of other metals and in connection with the use of other refining agents.

Refining agents fusible at the temperature of the molten metal and of density less than that of the molten metal, such as the soda ash refining agents described in Letters Patent Nos. 1,590,730 and 1,590,739, issued on applications filed by me, may be used with advantage in refining slags in furnace, forehearth or ladle operations, but as hitherto applied such refining agents have not been as effective as might be expected because of limitations of the period or extent of contact between the refining agent and the molten metal. This invention provides an improved method of applying such refining agents which makes possible more intimate contact between the refining agent andthe molten metal as well as prolongation of the period of contact, or progressive contact, 'between the refining agent and the molten metal. In some cases this improvement makes such refining agents of broader application and in other cases this improvement-makes possible important economy in the use of such refining agents.

1 According to the present invention, the molten metal to be refined is run into a refining receptacle onto a preformed matte of the metal and the refining agent so that the refining agent is progressively released from this preformed matte to rise through the metal bath in intimate contact with the molten metal as the matte is heated by the moltenmetal. The progressive release of the grefiningagent prolongs the period of contact and intimate contact is promoted not only by the travel of the released refining agent through the metal bath, but also by the motion in the metal bath induced by this travel. The tween the metal of the matte and the added molten metal, as well as the difference in 60 composition of the two, also tends to induce perature of the metal-bath in.

may be formed by adding difference in temperature be'- Application filed October 18, 1929. Serial No. 400,743.

motion in the metal bath. The operation may be carried out in a unified manner by forming a matte of the refining agent with an initial or primary charge of the molten metal in the refining receptacle and by running a secondary or major charge of the molten metal into the refining receptacle onto this thus formed matte, or the operation may be carried out upon continuously successive batches of molten metal by forming a matte with the refining agent and a portion of the molten metal from a preceding batch held in the refining receptable and running the molten metal into the refining receptacle onto this thus formed matte. The period of operation, and the rate at which the refining agent is released, can be controlled within limits by regulating the ratio between the weight of metal in the matte and the weight of metal run onto the preformed mattein the refining operation, the period being prolonged by increasing this ratio. The period of the operation can also be controlled within limits by regulating the temperature of the matte when the molten metal is run into the refining receptacle onto the matte. In generalthe matte should be permitted to 0001 only to a temperature low enough to retain, mechanically, the refining agent for the desired period as further cooling necessarily reduces the temwhich the refining operation is carried out. The proportion of the refining agent used may generally be reduced as compared to similar operations in which the refining agent is added to the surface of a metal bath or in which the refining agent is placed as such in the refining receptacle into which the molten metal is run.

In refining ferrous metals with fused, briquetted or sintered, soda ash, the matte soda ash per 100-200 pounds of molten metal and allowing the mixture to freeze and from20-25 times the weight of metal contained in the matte may then be run onto the matte, for example. In refining copper with fused, briquetted or sintered soda ash,

the matte may be formed by adding 5-10 2-20 pounds of may be secured with pounds of soda ash per 100-200 pounds of metal and allowing this mixture to freeze and from 20-25 times the metal content in the matte may then be run onto the matte, for example. The refining agent is advantageously used in proportion to effect a maximum purification, sulphur reduction for example, per unit of refining agent with a minimum removal of desirable elements and a minimum of injury to the lining of the refining receptacle.

In one aspect this invention provides an improved method of applying refining agents such as soda ash in refining operations in which a large weight of metal is treated per operation. Such o erations necessarily involve the use of a arge refining receptacle which necessity tends to reduce the effectiveness of the refining agent used, as hitherto applied, because of insufiicient contact, as to period or extent, between the refining agent and the metal bath. By means of this invention, just as intimate contact and just as prolonged contact between the refining agent and the metal bath a large metal bath as with a small metal bath.

It will also be apparent that the advantages of this invention many be enjoyed, in many cases, without modi cation of existing foundry or smelter equipment and without severe change in usual routine.

I claim:

1. In refining molten metals with refining agents fusible at the-temperature of the molten metal and of density less than that of the molten metal, the improvement which comprises running a primarycharge of the l molten metal into a refining receptacle and 4 the resulting metal mixture in Fi i permitting it to cool thereln in admixture with a charge of the refining agent to a temperature at which the -refining agent is mechanically retained by the metal, and thereafter running a secondary chargeof the molten metal into the refining receptacle onto the thus formed matte, and holding the refining receptacle until the matte has been heated by the addition of molten metal to a temperature at which the refining agent has been released.

2. In refining molten metals with refining agents fusible at the temperature of the molten metal and of density less than that of the molten metal, the improvement which comprises running a minor charge of the molten metal into a refining receptacle and permitting it to cool therein in admixture with a charge of the refining agent to a temperature at which the refining agent is mechanically retained by the metal, and thereafter running a major charge of the molten metal into the refining receptacle I matte, and holding in the refiningonto the, thus formed the resulting metal mixture receptacle until the matte has been heated by the addition of molten metal to a temperature at which the. refining agent has been released. i

3. In refining molten metals with refinin agents fusible at thetemperature of the molten metal and of density less than that of the molten metal, the improvement which comprises running a primary charge of the molten metal into a refining receptacle and permitting it to cool thereln in admixture with a charge of the refining agent to a temperature at which the refimng agent is mechanically retained by the metal, and thereafter running a secondary charge of the molten metal into the refining receptacle onto the thus formed matte.

4. In refining molten metals with soda ash refining agents, the improvement which comprises running the molten metal into a refining receptacle onto a solid preformed matte of the metal and holding the resulting metal mixture in the refining receptacle while the matte is heated by the addition of molten metal to a temperature at which the refining agent is progressively released and rises through the molten metal.

5. Inrefining molten metals with soda ash refining agents, the improvement which comprises running a primary charge of the molten metal into a refining receptacle and permitting it to cool therein in admixture with a charge of the refining agent to a temperature at which the refining agent is mechanically retained by the metal, and thereafter running a secondary charge of the molten metal into the'refining receptacle onto the thus formed matte.

In testimony whereof I afiix my signaand the refining agent