US1882998A - Process of refining copper - Google Patents

Description

Patented Oct. '18, 1932 UNITED STATES PATENT OFFICE JAMES W. SCOTT OF CHICAGO, ILLINOIS, ASSIGNOB 'IO WESTERN ELECTRIC COMPANY, INCORPORATED, OI YORK, N. Y., A CORPORATION OF NEW-YORK rnocnss or mmme corrm Io Drawing.

This invention relates to a rocess of refinloading material the desired electrical and magnetic properties. Tough pitch copper, by reason of its high electrical conductivity, is ordinarily used in forming the conductors or core in such telephone cable, and when the cable is subjected to the heat treatment above mentioned, the copper is embrittled since tough pitch copper contains a copper-copper oxide eutectic (01101120) the oxygenofwhich reacts with the reducing gas to disrupt the copper crystals and weaken the metallic.

structure of the copper. It is, therefore, very desirable to provide a copper having the lowest possible oxygen content thereby eliminating this deleterious reaction when heated in the presence of a reducing gas.

An object of this invention is the produc tion of copper having a markedly low oxygen content and a high degree of electrical conductivity while retaining suflicient ductility to facilitate subsequent working thereof.

- It has been determined by extensive experimentation that copper having so small an oxygen content that it will not embrittle when subjected to heat in an atmosphere of hydrogen may be obtained if a'deoxidizing agent is intimately enough mixed with tough pitch copper in a crucible coated with a material which will not contaminate the deoxidized copper. Experiments have also proved that copper having an oxygen content known to be less than 005% and which -will not embrittle when heated in an atmosphere of hydrogen may be produced by intimately mixing a reagent such as calcium boride, aluminum boride, or silicon boride with tough pitch copper in the type of crucible described. In general, these features constitute the subject matter of the present invention.

Application med September 9, 1880. Serial l lo. 480,821.

The preferred form of the invention comprises providing a clay graphite crucible,

lining the crucible with a material devoid of any substance which will contaminate the copper when the molten bath thereof is poured intothe crucible, sprinkling a small amount of calcium boride over the surface of the crucible thus treated, pouring molten tough pitch copper into the crucible, and adding to the stream of copper'being poured co per foil capsules containin calcium bori e. An aluminum oxide was has been determined to be a very'satisfactory surfacing material for lining the crucible, and if su-fli ciently pure will not be reduced to metallic elements which might be dissolved into the copper. In the preferred form of the invention, the steps thereof are as follows: First, melting the-copper in a mother furnace, oxidizing it by any of the well known methods to minimize the impurities in the copper, and

while in a molten state poling it thereby reducing the oxygen content to from approximately .03% to approximately .08% of oxygen by weight; second, covering the bath in the mother furnace with a carbonaceous material such as charcoal; third, ladling the molten tough pitch copper so produced from ,the mother furnace into a heated crucible to I which a. lining has been applied by washing or painting the interior of the crucible with a mixture of about 20% aluminum oxide (A1 0,) in water, and upon which lining calcium boride has been sprinkled; fourth, as the molten tough pitch cop er is poured from the ladle into the crucib e, adding to the stream being-poured copper foil capsules containing calcium boride in the ratio of approximately one gram for each pound of metal being treated.

This method of mixing calcium boride with molten tough pitch copper results in an intimate mixture of the reagent with the copper. Copper produced by the method of the present invention has an oxygen content of less than .005% by weight. In fact, the oxygen content is so low that when copper treated in this manner is heated to between 850 C. and 950 C. in an atmosphere of hydrogen, no

appreciable amount of embrittling occurs.

. wherein a clay Althou h a specific embodiment of the invention as been described hereinbefore, graphite crucible lined with a layer of alumlnum oxide (A1,,O.) is used and foil capsules containing calcium boride are added to the stream of molten copper being poured into the crucible it is to be understood that a pure silica crucible might be used and calcium boride and copper filings or dust mi ht be compressed into pellets and added to t e stream of molten copper. Numerous other substitutions might be made without depart-in from the scope of the invention which is lmited only by the scope of the appended claims.

What is claimed is:

1. A method of producing copper substantially free from oxygen which com rises poling molten copper in a mother urnace to reduce the oxygen content thereof to from approximately .03% to a proximately .08% by weight, providing a c ay graphite crucible lined with a layer of aluminum oxide, sprinkling the lining with calcium boride, ladling the molten copper from the mother furnace and pouring it into the crucible, and

adding copper containers containing calcium boride to the stream of molten metal being poured into the crucible to mix intimately the calcium boride with the molten copper.

2. A method of producing copper substantially free from oxygen which comprises poling molten copper in a mother furnace to reduce the oxygen content thereof to from approximately .03% to approximately .08% by weight, providing a clay. graphite crucible lined with a layer of aluminum oxide, sprinkling the lining with calcium boride, ladling the molten copper from the mother furnace and pouring it into the crucible, and adding copper capsules containing calcium boride in the proportion of one gram of calcium boride to one pound of metal being treated to the stream of molten metal being poured into the crucible to mix intimately the calcium boride with the molten copper.

In witness whereof, I hereunto subscribe my name this 29th day of August A. D., 1930.

JAMES W. SCOTT.