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United States Patent Office Patented Feb. 21, 1928, 1,660,220 UNITED STATES PATENT OFFICE. ANTHONY-G. DE GOLYER, OF BROOKYN, NEW YORK. CoPPER BEFINING. NoDrawing. Application filed April 16, 1927. serial No. 184,443. My present invention relates to a new and copper, cement copper, scrap copper, etc. It improved process for the refining of copper, is also adapted for use in both the produc-65 and relates particularly to methods for the tion of cast shapes to be used in the produc production of copper which is entirely free tion of wire, tubes, sheets and other wrought from dissolved and occluded gas and from articles, and for the production of finished oxygen. or semi-finished castings in sand or other In response to industrial and technical de molds, PE, castings having high 60 mands, many attempts have been made to electrical conductivity, high tensile strength produce oxygen free copper by direct refin and excellent machining qualities. O ing methods and otherwise. While it has Before describing my invention I will been possible heretofore to produce oxygen give, for the purpose of comparison, an out free copper by means of previously proposed line of the pyrometallurgical method which 05 methods, copper so produced did not have has heretofore been generally used for the the necessary additional qualities of high refining of copper, and the aii Opera 5 metallic copper content, high electrical con tions required for the production of deoxi ductivity, and freedom from dissolved or dized copper. occluded gas which, latter, resulted in gas or Electrolytic copper in the form of cath-0 “blow holes in the solid copper. Conse odes has an average metallic copper content quently, copper produced by previously pro of 99.975%, and an electrical conductivity of 20 posed methods does not possess the neces 101% or more (Matthissen standard), and sary properties and qualities to meet the is substantially free from oxygen. How general industrial and technical require ever, cathode copper is not in suitable con- 75 ments, hence, none of such previously pro dition for rolling or other working, and posed processes have been of commercialim must be subjected to a pyrometallurgical re portance. fining process before it can be rolled, drawn, I have discovered that by means of the etc. W hereinafter described process I can produce The cathodes are melted in fuel fired re- 80 copper which is entirely free from dissolved verberatory furnaces, the charges ranging or occluded gas, such as carbon monoxide, from 20 to 250 tons. The major portion of 3) and entirely free from oxygen. Further the melting is accomplished by indirect dis more, the copper so produced contains lower solving, i.e., the solid copper is under the percentages of various impurities, such as surface of the bath and not in direct contact 85 iron and sulphur, than copper produced by with the fuel flames. The charging and heretofore known pyrometallurgical meth melting operations require from 0 to 13 35 ods, and copper produced by means of the hours, regardless of the size of the charge, present invention is entirely free from resid and during this time the molten copperab ual impurities resulting from reagents used sorbs a relatively large amount of sulphur 90 in effecting complete removal of oxygen. from the fuel flames, By reason of the combined advantageous When the charge is molten, air is blown 40 factors-absence of dissolved or occluded into the copper until the bath consists of gases, absence of oxygen, and high metallic the saturated copper-copper oxide eutectic, copper content-copper produced by the op containing .39% oxygen, and, in addition, 95 eration of the present invention possesses some free cuprous oxide, so that the bath higher percentage of electrical conductivity, generally contains from 45% to .55% oxy 45 higher tensile strength and greater reduction gen. Oxidation in this manner removes sub in area and percentage of elongation than stantially all sulphur from the bath, Epper refined by previously known meth as sulphur dioxide; and substantially a 100 OS, M iron, and a portion of certain other impuri The present process is equally adapted for ties, such as arsenic and antimony. The 50 the refining of cathode copper produced by latter impurities are removed from the cop electrolytic refining and the direct refining r as oxides which enter the slag. Fol of copper bearing material which has not owing oxidation, a large proportion of the l been refined electrolytically, such as blister slag is removed. 1660,220 Partial deoxidation of the bath is then un oxygen, in the form of cuprous oxide, in dertaken by "poling’ i. e., logs or poles of such copper renders it entirely or partially green wood are introduced under the surface unsuitable for many industrial applications. of the metal, the wood being converted into Many attempts have been made to pro charcoal which in turn reacts with the cu duce oxygen free copper by means of a com 70 prous oxide of the bath. Reduction of the bination of the above described method and cuprous oxide in this manner is continued un the additional operation of adding a metal til the oxygen content of the bath is between lic deoxidizing agent, such as phosphorus .035% and 055%, within which range the or silicon, to the “poled' copper, i.e., the O metal is said to be “tough pitch’ copper. At copper containing between .035% and .06.0% 75 this stage the copper is cast into wire bars, OXygen. cakes, ingots, etc. While it is possible to produce copper The “poling' operation requires from 3 to which is substantially oxygen free by such 4A hours, and from 4 to 6 hours are con methods, the cast copper is invariably un 5 sumed in casting, and during these peri sound, due to the presence of gas in the 80 ods the copper again absorbs appreciable molten metal, hence it is not suitable for amounts of sulphur, as well as iron and rolling, drawing, or other mechanical work other impurities. - ing. Furthermore, such copper always cont In the refining of copper by the above de tains impurities in the form of residual 20 scribed method it is essential that the oxy metallics of the deoxidizing agent, hence the gen content be maintained within the range percentage of electrical conductivity is ma of from .035% to .055%, as when the oxygen terially reduced, being, in such cases, be exceeds approximately .060% the cast cop tween 85% and 92% (Matthissen standard), per is unsound, apparently due to the pres so that the copper is not suitable for use in 25 ence of a gas. Furthermore, the relatively wire or other wrought forms for the trans 9. high oxygen content reduces the percentage mission of electrical energy. of reduction in area and elongation to such It will be apparent that it is not possible an extent that the copper does not possess to produce copper, by methods heretofore sufficient ductility for mechanical working. available, which possesses the following 30 In a similar manner, when the oxygen combined properties: (a) entire freedom 95 content is reduced to less than .035% the from oxygen; (b) entire freedom from dis cast copper is unsound, the metal invariably solved or carbon monoxide or other gases; rising or “swelling' in the molds, due to (c) metallic copper content of 99.970% or the presence of carbon monoxide, and pos higher; (d) electrical conductivity of sibly other gas, and such copper, termed 100.5% (Matthissen standard) or higher. 00 “over-poled', is also unsuitable for me By means of the process of the present in chanical working by reason of porosity, im vention I convert cathode copper into any paired ductility, low electrical conductivity, desired shapes or forms for use in the manu etc. facture of wrought products, or for use as 40 It will be apparent, therefore, that the finished or semi-finished castings, and the 105 poling operation can not be utilized for the copper so produced is characterized by en production of oxygen free copper having tire freedom from dissolved or occluded car the requisite reduction in area and elonga bon monoxide and other gases; entire free tion, i. e., ductility, tensile strength, elec dom from oxygen; a metallic copper con 45 trical conductivity and other essential or tent as high as, or higher than in the orig 0. desirable physical properties. inal cathode copper; a percentage of elec Copper produced by the above described trical conductivity as high or higher than pyrometallurgical method, generally termed that of the original cathode copper; high electrolytic copper', thus contains between tensile strength; high percentage of reduc 50 .035% and 060% oxygen and has a metallic tion in area, e. g., approximately 80% in 5 copper content of between 99.900% and the case of annealed wrought products. 99.960%. Wire of approximately .080 of an Furthermore, by means of this invention I inch diameter drawn from such copper and also refine copper containing material which annealed, will have an electrical conduc has not been refined electrolytically, such as 55 tivity of from 99.5% to 100.8%; a reduction blister copper, cement copper and scrap 120 in area of from 35% to 47%; elongation in copper, and convert such copper into any 10 inch lengths of from 30% to 38%, and desired forms for use in the manufacture will show an average of between 38 and 44 of wrought products, or for use in finished twists in 6 inch lengths. or semi-finished castings, and the copper so 60 Therefore, the metallic copper content produced is characterized by; entire free 25 and the percentage of electrical conductivity dom from dissolved or occluded carbon - of copper refined by such methods are sub monoxide and other gases; entire freedom stantially lower than the copper content and from oxygen; a metallic copper content ap electrical conductivity of the original cath: preciably higher than in the original copper 65 ode copper.
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