US2078225A - Decopperizing lead with phosphorus - Google Patents

Description

Patented Apr. 27, 1937 PATENT OFFICE DECOPPERIZING LEAD WITH PHOS- PHORUS Jesse 0. Better-ton and Yurii E. Lebedefi, Me-

tuchen, N. J., assignors to American Smelting and Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application March 2, 1935,

. Serial No. 9,106

8 Claims.

This invention relates to the metallurgy of lead and has for its object the provision of certain improvements in removing copper from lead.

The invention provides a process for decopperizing lead (including certain alloys thereof) which is of particular importance in treating lead containing copper in the relatively small amounts such as often persist or remain in the metal after many of the usual metallurgical proc- 10 esses to which lead is ordinarily subjected.

In accordance with the invention, the copperbearing lead is melted, and phosphorus, either in elemental or appropriate alloy form, is thoroughly incorporated in the molten bath. As a result the copper in the molten bath combines with the phosphorus present to form a dross and as such is eliminated from the metal. The formation of the copper phosphide dross and its separation from the resulting decopperized metal may be facilitated by liquation of the bath to its freezing point. As will be apparent from the. specific examples hereinafter set forth, a virtually complete elimination of copper may be readily affected by the present process.

As above indicated, the phosphorus may be added either in elemental or suitable alloy form. Also, it may be incorporated in the bath in a variety of manners, as, for example, by addition to the vortex created by the action of an ordinary mixing machine, by submergence in a basket in the bath through which the metal is circulated, etc. Thorough incorporation of the phosphorus in the metal is readily insured by stirring.

Naturally the amount of phosphorus or phosphorus alloy (of known composition) used will depend upon the copper content of the metal and the degree of separation desired, the normal operation being to supply that amount of phosphorus or phosphorus-yielding material whichis suflicient to combine with the copper content of the metal. Any residual or excess phosphorus, that is, phosphorus remaining in the metal after elimination of the copper, may be readily removed by means of niter or other oxidizing agents, or by any other suitable procedure.

For the purpose of more fully illustrating the improved process of the invention, the following typical examples of the process as applied to the treatment of copper-bearing lead and antimonial lead are given:

' Example 1 In this instance, 141.1 parts byweight of copper-bearing antimonial lead were melted in a suitable kettle provided with a mixer and melting dross amounting to 1.3 parts by weight was skimmed. To the remaining bath (139.8 parts by weight) which analyzed 6.31% antimony and 0.091% copper, 0.263 part by weight of phosphorus was added via the vortex created by the mixer with which the bath was continuously stirred. The bath was maintained within a temperature range of 650 F. to 720 F. throughout the period in which the phosphorus was added. This period was forty minutes, following which the mixing was continued for five additional minutes to insure complete incorporation of the phosphorus in the antimonial lead bath and to permit the reaction between the phosphorus and copper to run to completion.

The dross which formed was removed from the kettle at a temperature of 650 F. and amounted to 15.5 parts by weight with a copper content of 0.82%. The bath (124.5 parts by weight) contained 6.05% antimony and was found by spectro graphic analysis to be entirely free from copper.

Example 2 One hundred fifty two parts by weight of copper-bearing refined lead were melted in a suitable kettle and melting dross amounting to 1.9 parts by weight was skimmed, leaving a bath comprising 160.1 parts by weight which analyzed 0.081% copper.

Five parts by weight of phosphor-tin alloy containing 2.61% phosphorus were added to the bath at a temperature of 650 F. and allowed to melt and the entire charge was then stirred for ten minutes. The resulting dross, which was removed at a temperature of 650 F. and which analyzed 1.03% copper was of a very crystalline metallic nature and readily amenable to pressing.

The residual bath comprised 143.3 parts by weight and contained only spectroscopic traces of copper, less than 0.0001%.

Example 3 Apart from some details of operation, this example Was substantially a repetition of the preceding one, except for the use of phosphorus in elemental instead of alloy form.

In this instance 154.3 parts by weight of copper-bearing refined lead were melted and 1.7 parts by weight of melting dross skimmed from the kettle. The bath then comprised 152.6 parts by weight and analyzed 0.081% copper.

The bath was stirred and 0.130 parts by weight of free phosphorus added to the vortex of the mixer, the operation consuming a period of twenty minutes and the bath being maintained r within a temperature range of 650 F. to 670 F.

Stirring of the bath was continued for ten minutes at the same temperature following the addition of the last of the phosphorus.

The dross of a crystalline and metallic nature as above and which amounted to 9.75 parts by weight was skimmed at 650 F. The lead bath amounting to 142.9 parts by weight was analyzed and found to contain only 0.001% copper.

Following the removal of the dross, the bath was reheated to 750 F. and 0.1 part by weight of free phosphorus was added within a period of fifteen minutes. The stirring was continued for four additional minutes and the dross,

amounting to 2.5 parts by weight, skimmed.

Upon examination the final lead which amounted to 140.4 parts-by weight was found to be spectroscopically copper free.

It will thus be appreciated that the present invention provides a. direct, eflicient and clean out process for removing copper from lead and certain alloys thereof.

It has further been found that the lead prodnot itself exhibits certain improved properties which it is believed are probably due to the presence of minute quantities of phosphorus, distributed throughout the final product. For example, the metal remains bright and does not tarnish for an indefinite period of time. tion, it is of exceptionally high quality as to appearance, softness and other characteristics.

While various specific disclosures have been made in order to fully illustrate and explain the invention, it will readily be appreciated by those skilled in the art that various changes and modifications are embraced within the scope of the invention and may be employed in adapting it to varying situations, conditions and uses.

What is claimed is:

1. The process for removing copper from lead which comprises establishing a molten bath of the metal, incorporating a phosphorus-yielding substance therein, cooling said bath and separating the dross therefrom.

2. The process for treating lead and antimoniallead containing copper which comprises reacting a molten bath of the metal with phosphorus and separating the resulting dross in which copper is concentrated from the metal.

In addi- 3. The process for treating ,copperrbearing lead which comprises establishing a' molten bath thereof having a temperature not materially exceeding 750 F., incorporating suflicient phosphorus therein to insure complete reaction with the copper, cooling the bath to approximately its freezing point and separating the dross from the decopperized lead.

- 4. The process for removing copper from copper-bearing lead which comprises treating-the lead while molten with phosphorus in quantities suiiicient to completely convert the copper in the lead into phosphor-copper, and separating the resulting phosphor-copper from the remaining lead.

5. The process for removing copper from copper-bearing lead which comprises preparing a molten bath of the lead, mixing therein phosphor-tin alloy containing a known amount of phosphorus and in quantities sufiicient to react with the amount of copper in the lead, and separating the resulting phosphor-copper dross from the lead.

6. The process for removing copper from. copper-bearing antimonial lead which comprises mixing with a molten bath of the said metal suficient phosphor-tin of known composition to reaction to proceed and separating the resultingphosphor-copper reaction products from the metal of the bath.

7. The process for decopperizing lead which comprises melting a bath of lead containing predetermined amounts of copper, adding to the bath an amount of phorphorus in reactive form sufiicient to combine with the copper while maintaining the bath 'at a temperature range of approximately 650 F.'to approximately 720 F'., and separating the resulting copper-containing dross.

8. The process for treating lead contaminated with copper which comprises forming a molten bath thereof, incorporating in the bath sufilcient phosphorus in available form to combine with all of the copper in the bath and impart thereto a small residual phosphorus content and sep-, arating the resulting dross and decopperized lead.

JESSE O. BETTERTON. YURII E. LEBEDEFF,