Specialized metallurgical processes – compositions for use therei – Processes – Free metal or alloy reductant contains magnesium
Patent
1993-03-15
1994-11-15
Andrews, Melvyn J.
Specialized metallurgical processes, compositions for use therei
Processes
Free metal or alloy reductant contains magnesium
75651, 75652, C22B 1514
Patent
active
053644492
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for refining a crude material for copper or copper alloy, and more particularly to a process for efficiently removing impurity elements, such as Pb, Ni, Sb, S, Bi, As, Fe, Sn, and Zn, from a crude material for copper or copper alloy.
BACKGROUND ART
Because of its good thermal and electrical conductivity, copper or copper alloy is used in large quantities as an indispensable material for electric and electronic parts and heat exchanger and many other products. Its higher price than iron and its limited ore reserves necessitate, from the standpoint of effective resource usage, the recovery and recycling of its scrap produced from its use or machining. However, scrap copper cannot be recycled as such be:cause it contains a large amount of impurities such as foreign metals, solder, plating, and insulating materials. The common way of removing impurities from scrap copper is by manual separation and subsequent magnetic separation before its melting. Manual separation is limited in capacity and magnetic separation does not work on impurity elements in the form of solder, plating, or alloy components (such as Pb, Ni, Sb, S, Bi, As, Fe, Sn, and Zn). To cope with this situation, there was proposed a process for refining scrap copper by subjecting the melt of scrap copper to oxidation or reduction or to slagging by the aid of flux, thereby removing impurity elements. (Japanese Patent Publication Nos. 12409/1979 and 43094/1981 and Japanese Patent Laid-open Nos. 133125/1976, 27939/1983, 211541/1984, 226131/1984, and 217538/1986.) Improvement on this method has continued since its appearance. Of the above-mentioned methods, the one disclosed in Japanese Patent Laid-open No. 217538/1986 seems to be most effective. It consists of melting copper scrap, adding a small amount of phosphorus to the melt, performing oxidation to float impurity elements together with part of phosphorus oxide, removing residual phosphorus by oxidation while keeping the melt in a highly oxidative state, and finally removing oxygen by reduction. With this method, it is comparatively easy to remove Fe, Sn, and Zn, but it is hard to remove Pb, Ni, Sb, S, Bi, and As. Moreover, it poses a problem associated with contamination with a considerable amount of phosphorus.
The present invention was completed in view of the foregoing. It is an object of the present invention to provide a process for refining scrap copper or crude copper (called blister copper) by efficient removal of impurity elements such as Pb, Ni, Sb, S, Bi, As, Fe, Sn, and Zn in the course of melting, thereby recovering high-quality copper.
DISCLOSURE OF THE INVENTION
The present invention is embodied in a process for refining a crude material for copper or copper alloy which contains at least one species of Pb, Ni, Sb, S, Bi, and As which comprises the sequential steps of at least one species selected from the group consisting of Fe, Fe oxide, Mn, and Mn oxide, there-by causing Pb, Ni, Sb, S, Bi, and As in the melt to slag in the form of .compound oxide of Fe and/or Mn,
The present invention is also embodied in a process for refining a crude material for copper or copper alloy which contains at least one species of Pb, Ni, Sb, S, Bi, and As in combination with at least one species of Sn, Fe, and Zn which comprises the sequential steps of Fe, and Zn into slag, consisting of Fe, Fe oxide, Mn, and Mn oxide, thereby causing Pb, Ni, Sb, S, Bi, and As in the melt to slag in the form of compound oxide of Fe and/or Mn,
The step (2a) mentioned above is carried out such that the oxygen concentration in the melt increases to 500 ppm or above. This permits the efficient slagging of Sn, Fe, and Zn for their separation. In the step (2) or (2b) mentioned above, at least one of Fe, Fe oxide, Mn, and Mn oxide (preferably Fe and/or Fe oxide) is added in an amount of 10-50000 ppm of the weight of the melt. They are scattered over the surface of the melt and mixed with the melt by stirring (with bubbling of an inert gas). The resulting slag
REFERENCES:
patent: 3682623 (1972-08-01), Dierckx et al.
patent: 3744992 (1973-07-01), Lundquist
patent: 4318737 (1982-03-01), Canning, Jr.
Database WPI, Derwent Publications Ltd., AN 93-165432, SU-A-1 735 410, May 23, 1992.
Database WPI, Derwent Publications Ltd., AN 85-049378, SU-A-1 105 512, Jul. 30, 1984.
Arai Motohiro
Hamanaka Ryusuke
Ikeda Ryukichi
Nakamura Takashi
Oga Kiyomasa
Andrews Melvyn J.
Kabushiki Kaisha Kobe Seiko Sho
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