Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B15/00—Obtaining copper
  • C22B15/0026—Pyrometallurgy
  • C22B15/006—Pyrometallurgy working up of molten copper, e.g. refining

Definitions

• Oxidizable iron or oxidizable iron compounds are added to the material while this is in a molten condition, the said oxidizable iron or compound being of a type which are soluble in molten copper or copper sulphide and which have a low antimony content.
• the dissolved iron is then isolated from the melt by a partial oxidation process, simultaneously oxidizing antimony and binding the same to the iron oxide.
• the present invention relates to a method for removing antimony from a material comprising at least one of the substances copper and copper sulphide.
• the anodes used in the electrolysis have a copper content of from 98.099.5% Cu and 2.00.5% impurities, these impurities being substantially isolated during the actual process of electrolysis.
• the type and quantity of impurities present in the copper to be electrolytically refined play an important part in the endeavour to obtain a trouble-free electrolysis. Strict limits are placed on certain impurities, while greater tolerance is permitted with regard to other impurities. It may therefore be necessary to pre-refine the copper anode so that the permitted limits are not exceeded.
• Antimony is a metal which has a particularly deleterious effect on the quality of copper refined by electrolysis and endeavours have been made to reduce the quantity of antimony in such copper to a content of at most 1 gram/ton. If the percentage of antimony in the copper anode is too high, for example more than 350 gram/ ton, there is formed during the electrolysis a floating slime of antimony, arsenic and, in certain instances, bismuth, which is liable to infect the copper cathode in a manner whereby the tolerance limits placed on the presence of antimony in the electrolytically refined copper is exceeded, thereby jeopardizing the quality of the copper. Moreover, this floating slime is also liable to result in growths on the cathode, which may cause short circuiting between the anode and the cathode, resulting in a reduced current yield.
• Antimony can not generally be removed from antimony-containing copper minerals by enrichment processes, since in the majority of antimony-containing copper finds the antimony is chemically bound to the copper. Extensive separation of antimony by enrichment processe results in copper losses which are too high to make such processes economically feasible. In order to reduce the content of antimony in copper products, it has hitherto been necessary to select crude materials of restricted antimony content or to use various metallurgical processes which only afford limited antimony purification. A large number of ore finds, which can not be processed economically under present day conditions, would be ac- Patented July 10, 1973 cessible for the production of high grade copper if more effective antimony purification methods were to be devised.
• the copper is subjected to a pre-refining process before being electrolytically refined, the pre-refining process including a number of metallurgical treatment stages, such as roasting, matte smelting and conversion.
• metallurgical treatment stages such as roasting, matte smelting and conversion.
• Each stage of the refining process can be used to remove a certain percentage of antimony.
• antimony is removed by volatilization, although expulsion of antimony seldom exceeds roughly 20% of the total antimony content.
• a slag builder normally silicon dioxide, is charged to the process while smelting the roasted products, wherewith a slag and matte are formed which contain practically all the copper present in the charged material.
• the antimony content is distributed between the slag and matte phases. It is not economically possible to influence this distribution to any great extent, for example by varying the composition or quantity of the slag.
• the matte is transferred in a molten state to a converter, where it is oxidized with air or air enriched with oxygen-gas to form substantially copper metal, sulphur dioxide and iron oxides.
• the iron oxides are simultaneously converted to slag by adding silica sand.
• the relatively long oxidation treatment in the converter is, in itself, an effective copper refining method, although it is far from suflicient with respect to purifying the copper of antimony.
• molten copper sulphide or the copper is added with oxidizable iron or oxidizable iron compounds which are soluble in molten copper or copper sulphide and which have a low content of antimony, whereafter the dissolved iron is isolated in a conventional manner from the melt by partial oxidation with air or air enriched with oxygen-gas.
• suitable oxidizabie iron compounds are pyrites and pyrrhotite. These compounds are suitably charged to the process in pelletized form.
• Magnetite content Antimony content This confirms the assumption that there is a strong chemical bond between iron and antimony in oxidized form. By carefully following the copper conversion process, it was clearly established that the antimony transfer rate from copper matte and copper metal to slag is functionally directly correlated with the oxidation of iron in the matte or copper.
• the iron content is practically completely oxidized before any appreciable quantity of copper is oxidized.
• the sulphur from the sulphides is oxidized in parallel with the iron and reduces the slag forming rate with a constant supply of oxidant to the system.
• the iron oxide floats to the surface, bearing the isolated antimony. The iron oxide is then either mechanically scraped from the surface of the copper melt or, subsequent to forming slag with silicic acid, is decanted 01f in liquid form.
• the described refining method in which iron or iron compounds having a low antimony content are charged to the refining system, is suitably carried out in connection with copper conversion processes andin a copper converter, although, of course, it may be carried out in other types of furnaces, such as, for example, flame furnaces or rotary furnaces.
• Iron scrap, iron-copper-scrap, iron sulphides or chalcopyrite are examples of suitable iron additives free or essentially free from antimony which can be charged to the system.
• the most efiective of these with respect to removing antimony is naturally iron scrap, while the least effective is chalcopyrite, although when using iron scrap and iron sulphide the conversion period is lengthened without increasing the production of copper.
• Suitable oxidants are air-oxygen or air enriched with oxygen. The oxygen is preferably introduced beneath the surface of the bath, either by means of tuyeres or a lance.
• the copper sulphide charge approximately 130 tons, was treated with 10 tons of matte.
• the antimony content was reduced thereby from 0.06% to 0.03% in the ready-blown copper.
• the method of the present invention enables the antimony content in the produced copper to be considerably reduced and that this reduction enables a material rich in antimony to be processed without risk that the antimony content will impair the quality of the product.
• a method for removing antimony from copper sulphide characterized in that to the copper sulphide in molten state is added oxidizable metallic iron which is soluble in molten copper sulphide and has a low content of antimony, whereafter the dissolved iron is isolated from the melt by a partial oxidation, antimony being at the same time oxidized and bound to the iron oxide, which forms a separate insoluble phase in the melt.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

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Family Applications (1)

Country Status (7)

Cited By (1)

• 1969
  • 1969-12-23 SE SE17828/69A patent/SE346807B/xx unknown
• 1970
  • 1970-11-30 CA CA099424A patent/CA930959A/en not_active Expired
  • 1970-11-30 US US00093914A patent/US3744992A/en not_active Expired - Lifetime
  • 1970-12-02 DE DE19702059299 patent/DE2059299A1/de active Pending
  • 1970-12-08 ZM ZM142/70A patent/ZM14270A1/xx unknown
  • 1970-12-21 BE BE760604A patent/BE760604A/xx unknown
  • 1970-12-22 ES ES386735A patent/ES386735A1/es not_active Expired

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