Copper refining method

FIELD: metallurgy.

SUBSTANCE: method involves preparation of charge, its melting and oxidation of the obtained copper melt. Charge is prepared by classification of copper scrap and its cleaning from tin and lead solder, oxidation of copper melt is performed by batch supply to the melt of NaOH sodium hydroxide in the quantity of 0.5-3 wt % of the charge weight with simultaneous blowdown by means of oxygen-containing gas.

EFFECT: reduction of content of undesirable impurities in copper scrap melt; improvement of refining degree.

3 cl, 1 tbl

 

Method of refining copper relates to the field of non-ferrous metallurgy and can be used for fire refining of copper scrap, mainly used for electrical purposes, polluted, mainly by impurities solder and foreign inclusions.

Known "Method of fire refining of copper" by the request of EN No. 2007126129 from 09.07.2007, publ. 20.01.2009, IPC SW 15/14 (2006.01), including the melting of the copper-containing material with the addition of a flux, which includes iron and silicon oxide., the oxidation of the copper melt with the addition of fluxes in amounts corresponding to a mass ratio of SiO2:Fe=1,2...1,5, with a mass fraction of the flux from a mixture of 0.3...0.4% and the separation of slag from copper.

However, this method is applicable only when substantial content of impurities, since the introduction of iron in the molten copper, complicates the process, as subsequently leads to the necessity of its removal.

Known "Method of refining copper and copper alloys (options)" on the application of EN No. 2005135994/02 from 21.11.2005, publ. 27.05.2007, IPC SW 15/14, SS 1/02, including the melting of the charge in the furnace with the cover flow to the surface of the melt through a lance gaseous oxidant and subsequent recovery in the melt at the melt surface between at least two lances, set the frame and the area of the inner surface, costall the ment of 0.3-0.5 surface area of the entire melt, which is placed in refining flux, and when reaching the oxygen concentration in the metal is not less than 0.8 wt.% the gaseous oxidant stop, lances raised, providing free movement of the frame with flux on the surface of the melt; or, in this case, the gaseous oxidant to carry out the melt surface inside the frame, and refining flux is placed on the other surface of the melt, and, upon reaching the oxygen concentration in the metal is not less than 0.8 wt.% the gaseous oxidant stop, lance and raise the frame, ensuring the distribution of flux across the surface of the melt; as a gaseous oxidant use oxygen, or a mixture of water vapor with air, or a mixture of saturated hydrocarbons with air; as the ultimate hydrocarbon use methane; as a refining flux, a mixture of salts of alkali and alkaline earth metals and silica.

This method is applicable only if the refining furnaces, which allow the frame to the melt surface, mainly in the furnace crucible type.

The closest is "the way of the fire refining of copper" in patent RU No. 2391420 on 24.06.2009, publ.: 10.06.2010, IPC SW 9/10 (2006.01), SW 15/14 (2006.01), which includes the melting of the copper-containing mA the materials containing silicon oxide, with flux, and iron, further oxidation of the obtained copper melt at a temperature 1220-1240C, with the addition of a flux containing aegirine concentrate composed of aegirine, and the silicon oxide - SiO2with the following ratios, wt.%: concentrate - 75-15%, silicon oxide - 25-85%, and separating the slag from the copper melt.

This method is also applicable when significant contamination with impurities of the copper melt. Aegirine concentrate contains significant amounts of iron oxide, which is undesirable due to the need for further removal. In addition, the application produces an acidic slag, adversely affecting the lining of the furnace, as a rule, basic or neutral.

The goal is to reduce the content of undesirable impurities in the melt of copper scrap, mainly used for electrical purposes, polluted, mainly by impurities solder and foreign inclusions.

The problem is solved owing to the method of refining copper, including batch preparation, melting and oxidation of the obtained copper melt, while the mixture is prepared by sorting copper scrap and cleansing it from the tin and lead solder, oxidation of the copper melt lead by batch feeding to the melt of sodium hydroxide NaOH in the amount of 0.5-3 wt.% by weight of the mixture with simultaneous produce the oxygen-containing gas; after each purge control chemical composition rathinasamy copper; the calculated amount of sodium hydroxide NaOH, distribute the blow.

The technical result is to achieve a degree of refinement that allows you to get commodity copper quality up to the mark M0 GOST 859-2001, due to portions of the feed to the melt of sodium hydroxide NaOH, in the amount of 0.5-3 wt.% by weight of the mixture with simultaneous blowing of oxygen-containing gas, which can reduce the content of undesirable impurities in the melt, at times, for example: Sn (tin) and Fe (iron) to 10, Pb (lead) up to 4, Sb (antimony) to 2. The data are summarized in table.

The method is as follows.

Cook the mixture, filtering from scrap impurities from foreign metals and alloys, and nonmetallic impurities.

After melting of copper-bearing materials in the melt, portions, or on the surface of the melt, served sodium hydroxide (NaOH) in an amount of from 0.5% to 3% by weight of the mixture, depending on indicators of contamination of metal impurities. At the same time the melt blown oxygen-containing gas (in the particular case - air), to oxidize impurities and simultaneous stirring of the melt.

The total required quantity of sodium hydroxide from 0.5% to 3%, determined empirically, on the basis of the experience is imentally data distribute the number of operations of the purge, which is held in conjunction with the introduction of NaOH.

After each purge control chemical composition rafinirovannogo metal, and based on Istochnik data, decide on the continuation of the operations of the introduction of NaOH and purging, or about the end stage of refinement and transition to a drain of the slag.

Upon completion of these operations the melt to stand, before the formation on the surface of a melt of molten slag having a low viscosity, which is a mixture of copper oxide and oxides of impurities. The slag from the surface of the melt is removed in any convenient way, for example by draining, or on the surface of the melt serves alkali metal polyphosphate, resulting slag is transferred into the solid phase, and it is removed mechanically.

After removal of the slag, restore (rascist) melt any known method: the flow in the melt wet logs (irritation), or blowing natural gas, or the introduction into the melt mixture of heavy hydrocarbons, periodically controlling the melt to obtain a satisfactory, below 300 ppm., measure the oxygen content in the melt.

The proposed method has proven its effectiveness during fire refining of copper scrap for electrical purposes, polluted, mainly by impurities solder and outsiders, including enemy, through the use of sodium hydroxide, can reduce the content of undesirable impurities in the melt, at times, for example: Sn (tin) and Fe (iron)to 10, Pb (lead) up to 4, Sb (antimony) to 2.

Original contentThe final contentThe degree of refining
Sn (tin)100-21012-307-9
Pb (lead)15-805-203-4
Fe (iron)50-1505-1010-15
Sb (antimony)10-155-101,5-2

The technical result is to achieve a degree of refinement that allows you to get commodity copper quality up to the mark M0 GOST 859-2001, provided the relevant preparation charge, and the slag has a low viscosity, which facilitates its removal.

1. Method of refining copper, including batch preparation, melting and oxidation obtained the region of the melt, characterized in that the mixture is prepared by sorting copper scrap and cleansing it from the tin and lead solder, oxidation of the copper melt lead by batch feeding to the melt of sodium hydroxide NaOH in the amount of 0.5-3 wt.% by weight of the mixture with simultaneous blowing of oxygen-containing gas.

2. The method according to claim 1, characterized in that after each purge control chemical composition rathinasamy copper.

3. The method according to claim 1, characterized in that the calculated amount of sodium hydroxide NaOH distribute the number of operations of the purge.



 

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