DE1558752B2 - FIRE-RESISTANT LINING FOR TUBS OF SINGLE-CELL OR MULTI-CELL FURNACES FOR MELT FLOW ELECTROLYSIS OF ALUMINUM - Google Patents

Description

heat is very low. Stable and long-lasting walls can be built easily, even at great heights Manufacture way. The cryolite lining can be inserted directly into the actual metal tub.

The refractory lining is expediently manufactured from prefabricated cryolite fittings. These are produced by the practically pure molten cryolite in Pours a mold, solidifies it in it by cooling, then the one from the casting shell or form removed fittings put together on the spot and the individual fittings welded to one another with heating in a manner known per se. Before welding can expediently a thin layer of powdered or melted cryolite in the weld be distributed.

This has the advantage that the furnace lining and the individual fittings are easy to assemble are sealingly connected to each other.

Claims (3)

1 2 separates, which cannot be resolved again in the weld pool. In addition, the soil is characterized by deformations due to seeping through components. 1. Refractory lining for tubs of sets, eliminating local changes in current density Single-cell or multi-cell furnaces for the melting 5 and thus overheating occur, whereby a Flow electrolysis of aluminum, which means that higher power requirements are required for operation indicates that the lining is being made. The entire tub or its most essential parts have therefore already been made ready for use Moldings made from practically pure, for example, the side walls of the tubs with natural silicon or synthetic cryolite. Lining io nitride-bonded silicon carbide. If- 2. Process for producing a refractory probably this material is extremely temperature resistant, Lining according to claim 1 made of prefabricated is its ohmic resistance in the case of high tempera cryolite fittings, characterized by doors, i.e. when it is immersed in the melt, that you get the practically pure molten relatively low. Plus the material will, though Pouring cryolite in an internal form, it is chemically resistant to a high degree, in more cooling can solidify, then from the cell ovens, which operated at higher voltages Shells or moldings removed from the mold are attacked electrochemically. Assembled on the spot and the individual It is also known to use metallurgical furnaces nen molded pieces with heating in a solidified melt of sodium chloride and welded together in a known manner. so to coat cryolite (German patent specification 3. The method according to claim 2, characterized in that 871 355). For furnaces for the production of aluminum, it is known that before welding minium by fusible electrolysis, a thin layer of powdered or poured tub linings made of a material to be melted cryolite adjust into the weld, which divides 20 to 75% of a refractory oxide . 25 holds and the remainder consists of cryolite. Included For example, the refractory oxide can be aluminum oxide (German Auslegeschrift 1 209 303). Included a relatively high aluminum oxide content has proven to be particularly favorable for the properties of the wall The invention relates to a refractory lining 30 materials. However, this means that for for tubs of single-cell or multi-cell furnaces for the production of a melt from this material for the melt flow electrolysis of aluminum. Forming the walls very high temperatures It is well known that the tubs are usually required, which means very high performance for those used Aluminum furnaces with graphite charcoal means heating and causes difficulties in the dressed that serves as a cathode. The tubs are deformed. Plus, it's hard to do with hold molten cryolite in which the aluminum multi-cell furnace as a result of the use of bipolar dissolved miniumoxide is present. Due to the particularly high side immersion ends required in the melt Establish anodes and feed of the required walls. Electrical power differs as a result of the - Finally, it is also known, the gaps electrolysis to manufacture metallic aluminum at 4 ° between the anodes of a furnace From the bottom of the tub. of aluminum by molten electrolysis with These aluminum ovens have the disadvantage that a pack of compacted powdery the side walls made of graphite charcoal are filled with cryolite or alumina (Austrian wear, for example through chemical reactions (patent 193 620). with the melt, through changes in the composition and the temperature of the melt is now a refractory lining for and the like solidify, as soon as the temperature to create melt electrolysis of aluminum, the melt is 50 to 100 ° C below that at 950 ° C, which is free of the electrolysis temperature due to the use of aluminum, is formed at 5 ° miniumoxide.
Such temperature changes at the tank This object is achieved by replacing the wall with a semi-solid to solid layer of the melt, clothing of the entire tank or its essential part, by the missing graphite carbon. Most of the parts from prefabricated shaped pieces "from prak-thickness of this layer depends on the change in the table pure natural or synthetic cryolite temperature of the melt. In this process 55 consists. Finally, the side walls always exist. Such a lining has the advantage that As the proportion of solidified melt increases, its melting point is above the temperature of the electric with a different proportion of cryolite. Since the melt flow is and the melt temperature of these walls is very low, that is, it is neither chemically nor electrochemically less than 940 ° C., which is gripped with the melt 60. A dissolution of the walls in contact with the cryolite wall is semi-solid and thus counteracted by the melt, unstable, and the wall thickness is locally different, so that the temperature of the melt in the ¹ wall near the wall is different and, for optimal furnace operation, layers by appropriate dimensioning and expedient . Order of the anodes low, e.g. B. below 900 ° C, Another disadvantage is that between 65 is maintained. Another advantage results from the graphite carbon base and the fact that the thickness of the cryolite layer only needs to be a solid to a strong centimeter in the thickness of the cryolite layer.