Abstract:
An inert alloy anode for aluminum electrolysis contains Fe and Cu as primary components and further contains Sn; addition of the metal Sn contributes to formation of an oxide film with strong oxidization resistance and stable structure on the surface of the inert alloy anode and to improvement of the corrosion resistance of the anode; on this basis, the inert alloy anode further contains Ni, Al and Y, addition of the metal Al can prevent the primary metal components from being oxidized, and addition of the metal Y can control alloy to present a desired crystal form in the preparation process to achieve oxidization resistance.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an inert alloy anode for aluminum electrolysis and a preparing method thereof, belonging to the field of aluminum electrolysis industry. 
       BACKGROUND OF THE INVENTION 
       [0002]    Aluminum electrolysis refers to acquisition of aluminum by alumina electrolysis. In the prior art, a traditional Hall-Heroult molten salt aluminum electrolysis process is typically adopted for aluminum electrolysis, this process is featured by use of a cryolite-alumina molten salt electrolysis method in which cryolite Na 3 AlF 6  fluoride salt melt is taken as flux, Al 2 O 3  is dissolved in the fluoride salt, a carbon body is taken as an anode, aluminum liquid is taken as a cathode, and electrolytic aluminum is obtained by performing electrochemical reaction at the anode and cathode of the electrolytic cell at a high temperature ranging from 940° C. to 960° C. after a strong direct current is introduced. In the traditional aluminum electrolysis process, a carbon anode is ceaselessly consumed in the electrolysis process, thus constant replacement for the carbon anode is required; moreover, carbon dioxide, carbon monoxide, toxic fluorine hydride and other waste gases are continuously generated at the anode during alumina electrolysis, emission of these gases into environment will be harmful to environment and health of human and livestock, so that the waste gases generated by aluminum electrolysis need to be purified before emission, which accordingly increases the investment cost of the alumina electrolysis production process. Consumption of the anode material in the process of aluminum electrolysis is mainly caused by oxidization reaction, in the electrolysis process, of the carbon anode material used in the traditional Hall-Heroult process. Therefore, many domestic and foreign researchers have commenced the study on anode material in order to reduce consumption of the anode material in the process of aluminum electrolysis and simultaneously lessen waste gas emission. For example, disclosed in Chinese patent document CN102230189A is a metal ceramic inert anode material for aluminum electrolysis, which is obtained by the steps of preparing an NiO—NiFe 2 O 4  metal ceramic matrix from raw materials including Ni 2 O 3  and Fe 2 O 3  and then adding metal copper powder and nano NiO, and which has an electric conductivity as high as 102 Ω −1 ·cm −1 . In the above art, the anode material with metal ceramic as the matrix, though hardly reacting with electrolyte, is large in resistance and high in overvoltage, which results in large power consumption of the process and high cost in the process of aluminum electrolysis; furthermore, the anode material with metal ceramic as the matrix has poor thermal shock resistance and consequently is liable to brittlement during use; and in addition, the processability in use of the anode made from the above materials is poor just because the anode material having the metal ceramic matrix is liable to brittlement, as a result, the anode in any shape cannot be obtained. To solve the problem that the anode material having the metal ceramic matrix is low in electric conductivity and brittle in structure, some researchers have brought forward use of alloy metals as the anode material, in order to improve the electric conductivity of the anode material and simultaneously improve the processability of the anode material. Disclosed in Chinese patent document CN1443877A is an inert anode material applied to aluminum, magnesium, rare earth and other electrolysis industries, this material is formed by binary or multi-element alloy composed of chromium, nickel, ferrum, cobalt, titanium, copper, aluminum, magnesium and other metals, and the preparation method thereof is a method of smelting or powder metallurgy. The prepared anode material is good in electric and thermal conductivity and generates oxygen in the electrolysis process, wherein in Example 1, an anode is made of the alloy material composed of 37 wt % of cobalt, 18 wt % of copper, 19 wt % of nickel, 23 wt % of ferrum and 3 wt % of silver and is used for aluminum electrolysis, the anode has a current density of 1.0 A/cm 2  in the electrolysis process at 850° C. and the cell voltage is steadily maintained within a range from 4.1V to 4.5V in the electrolysis process, the prepared aluminum has a purity of 98.35%. 
         [0003]    In the case that the alloy composed of a plurality of metals, including chromium, nickel, ferrum, cobalt, titanium, copper, aluminum and magnesium, is used as the anode material for aluminum electrolysis in the above art, this alloy anode material has higher electric conductivity than the anode ceramic matrix anode material, can be processed in any shape by a smelting or powder metallurgy method and is hardly consumed in the electrolysis process compared with the carbon anode material. However, a large amount of expensive metal materials are used in preparation of the alloy anode in the above art to result in high cost of the anode material, and thus this alloy anode fails to meet the demand on industrial cost; moreover, the alloy anode prepared from the above metal components is low in electric conductivity and high in overvoltage, so that the power consumption of the process is increased, thus the alloy anode cannot meet the needs of the aluminum electrolysis process. 
         [0004]    In addition, an oxide film is generated on the surface of the prepared alloy anode in the prior art, and if this oxide film is destroyed, the anode material exposed to the surface will be oxidized as a new oxide film. The oxide film on the surface of the alloy anode in the above art has low oxidization resistance and is further liable to oxidization reaction to generate products that are likely to be corroded by electrolyte, and the oxide film with low stability is liable to fall off the anode electrode in the electrolysis process; after the previous oxide film is corroded or falls off, the material of the alloy anode exposed to the surface will create a new oxide film by reaction with oxygen, such replacement between new and old oxide films results in continuous consumption and poor corrosion resistance of the anode material as well as short service life of electrodes; furthermore, the corroded or falling oxide film enters into liquid aluminum in the electrolysis process of alumina to degrade the purity of the final product aluminum, as a result, the manufactured aluminum product cannot meet the demand of national standards and accordingly cannot be directly used as a finished product. 
       SUMMARY OF THE INVENTION 
       [0005]    The first technical problem to be solved by the present invention is that the alloy anode in the prior art is expensive in metal materials used, high in process cost, low in electric conductivity and high in overvoltage, as a result, power consumption of the process is increased; therefore, provided is an inert alloy anode for aluminum electrolysis with low cost and overvoltage, and a preparing method thereof. 
         [0006]    Simultaneously, the second technical problem to be solved by the present invention is that, an oxide film on the surface of the alloy anode in the prior art is low in oxidation resistance and liable to fall off, which leads to continuous consumption of the alloy anode and poor corrosion resistance, furthermore, the corroded or falling oxide film enters into liquid aluminum to degrade the purity of the final product aluminum; therefore, provided is an inert alloy anode for aluminum electrolysis, which is strong in oxidization resistance of the oxide film formed on the surface and not liable to fall off so as to improve the corrosion resistance thereof and the purity of the product aluminum, and a preparing method of the inert alloy anode. 
         [0007]    To solve the aforementioned technical problems, the present invention provides an inert alloy anode for aluminum electrolysis, which contains Fe and Cu as primary components, and further contains Sn. 
         [0008]    The mass ratio of Fe to Cu to Sn is (23-40): (36-60): (0.2-5) or (40.01-80): (0.01-35.9): (0.01-0.19). 
         [0009]    The inert alloy anode further contains Ni. 
         [0010]    The mass ratio of Fe to Cu to Ni to Sn is (23-40): (36-60): (14-28): (0.2-5) or (40.01-80): (0.01-35.9): (28.1-70): (0.01-0.19). 
         [0011]    The inert alloy anode is composed of Fe, Cu, Ni and Sn, wherein the content of Fe is 23-40 wt %, the content of Cu is 36-60 wt %, the content of Ni is 14-28 wt % and the content of Sn is 0.2-5 wt %, or the content of Fe is 40.01-71.88 wt %, the content of Cu is 0.01-31.88 wt %, the content of Ni is 28.1-59.97 wt % and the content of Sn is 0.01-0.19 wt %. 
         [0012]    The inert alloy anode further contains Al. 
         [0013]    The inert alloy anode is composed of Fe, Cu, Ni, Sn and Al, wherein the content of Fe is 23-40 wt %, the content of Cu is 36-60 wt %, the content of Ni is 14-28 wt %, the content of Al is more than zero and less than or equal to 4 wt % and the content of Sn is 0.2-5 wt %, or the content of Fe is 40.01-71.88 wt %, the content of Cu is 0.01-31.88 wt %, the content of Ni is 28.1-59.97 wt %, the content of Al is more than zero and less than or equal to 4 wt % and the content of Sn is 0.01-0.19 wt %. 
         [0014]    The inert alloy anode further contains Y. 
         [0015]    The inert alloy anode is composed of Fe, Cu, Ni, Sn, Al and Y, wherein the content of Fe is 23-40 wt %, the content of Cu is 36-60 wt %, the content of Ni is 14-28 wt %, the content of Al is more than zero and less than or equal to 4 wt %, the content of Y is more than zero and less than or equal to 2 wt % and the content of Sn is 0.2-5 wt %, or the content of Fe is 40.01-71.88 wt %, the content of Cu is 0.01-31.88 wt %, the content of Ni is 28.1-59.97 wt %, the content of Al is more than zero and less than or equal to 4 wt %, the content of Y is more than zero and less than or equal to 2 wt % and the content of Sn is 0.01-0.19 wt %. 
         [0016]    A preparing method of the inert alloy anode comprises the following steps: melting and uniformly mixing the metals Fe, Cu and Sn, and then rapidly casting and cooling the mixture to obtain the inert alloy anode; 
         [0017]    or, melting the metals Fe, Cu and Sn at first, then adding and melting the metal Al or Y, and uniformly mixing, or adding and melting the metal Al at first, then adding and melting the metal Y, uniformly mixing, and rapidly casting and cooling the mixture to obtain the inert alloy anode; 
         [0018]    or, melting and mixing the metals Fe, Cu, Ni and Sn and then casting the mixture to obtain the inert alloy anode; 
         [0019]    or, melting the metals Fe, Cu, Ni and Sn at first, then adding and melting the metal Al or Y, and uniformly mixing, or adding and melting the metal Al at first, then adding and melting the metal Y, uniformly mixing, and casting the mixture to obtain the inert alloy anode. 
         [0020]    Compared with the prior art, the inert alloy anode for aluminum electrolysis in the present invention has the beneficial effects below: 
         [0021]    (1) The inert alloy anode for aluminum electrolysis in the present invention contains Fe and Cu as primary components, and further contains Sn. The inert alloy anode with the above components is low in cost, low in overvoltage and small in power consumption of the aluminum electrolysis process; the anode material is alloy composed of Fe, Cu and Sn, so an oxide film formed on the surface of the inert alloy anode in the electrolysis process is high in oxidation resistance and is hardly corroded by electrolyte, and the formed oxide film is stable and not liable to fall off, therefore, the inert alloy anode is imparted with quite high oxidation resistance and corrosion resistance. It is precisely because of high oxidation resistance and corrosion resistance of the inert alloy anode, impurities entering into liquid aluminum, which are generated by corrosion or falling off of the anode material, are avoided, so as to ensure the purity of aluminum products, that is, the purity of the produced aluminum can reach 99.8%. The following problems are avoided: the alloy anode in the prior art has high cost and overvoltage and large power consumption of process, the oxide film on the alloy surface is low in oxidation resistance and liable to fall off, which leads to continuous consumption of the alloy anode and poor corrosion resistance, furthermore, the corroded or falling oxide film enters into liquid aluminum to degrade the purity of the final product aluminum. 
         [0022]    (2) The inert alloy anode for aluminum electrolysis in the present invention is composed of Fe, Cu, Ni and Sn, wherein the content of Fe is 23-40 wt %, the content of Cu is 36-60 wt %, the content of Ni is 14-28 wt % and the content of Sn is 0.2-5 wt %, or the content of Fe is 40.01-71.88 wt %, the content of Cu is 0.01-31.88 wt %, the content of Ni is 28.1-59.97 wt % and the content of Sn is 0.01-0.19 wt %. 
         [0023]    The alloy anode in the present invention contains Fe and Cu as primary components, their content proportions are high, so the material cost of the inert alloy anode is reduced, meanwhile, the inert alloy anode composed of the aforementioned metal components is high in electric conductivity and has a cell voltage as low as 3.1 V to 3.4V, power consumption for aluminum electrolysis is small, the power consumption for per ton of aluminum is not more than 11000 kw·h, so the production cost of electrolytic aluminum is low. The following problems are avoided: a large quantity of expensive metal materials are used in the anode material in the prior art, resulting in increase of the anode production cost; the prepared alloy anode is low in electric conductivity, large in power consumption for aluminum electrolysis and increased in cost, and cannot be applied to industrial production. The added metal Ni is capable of promoting firmer combination among other types of metals, and the added metal Sn ensures that an oxide film with high oxidization resistance, good corrosion resistance and high stability can be formed on the surface of the inert alloy anode in the electrolysis process. 
         [0024]    (3) The inert alloy anode for aluminum electrolysis in the present invention is composed of Fe, Cu, Ni, Sn, Al and Y, wherein the content of Fe is 23-40 wt %, the content of Cu is 36-60 wt %, the content of Ni is 14-28 wt %, the content of Al is more than zero and less than or equal to 4 wt %, the content of Y is more than zero and less than or equal to 2 wt % and the content of Sn is 0.2-5 wt %, or the content of Fe is 40.01-71.88 wt %, the content of Cu is 0.01-31.88 wt %, the content of Ni is 28.1-59.97 wt %, the content of Al is more than zero and less than or equal to 4 wt %, the content of Y is more than zero and less than or equal to 2 wt % and the content of Sn is 0.01-0.19 wt %. Similarly, the aforementioned inert alloy anode has the advantages of low material cost and high electric conductivity, in addition, the metal Al contained in the aforementioned inert alloy anode plays a role of oxidization resistance and can serve as a reducing agent for metallothermic reduction reaction with a metal oxide in the inert anode alloy, thus ensure the percentage of the primary components in the inert alloy anode, meanwhile, the added metal Y can be used for controlling a crystal structure for anode material formation in the preparation process of the inert anode, achieving the anti-oxidization purpose. 
         [0025]    (4) The inert alloy anode for aluminum electrolysis in the present invention has a melting point of 1360-1386° C., a specific resistivity of 68-76.8 μΩ·cm at 20° C. and a density of 8.1-8.3 g/cm 3 . The prepared inert alloy anode has a quite high melting point and accordingly can meet the demand of aluminum electrolysis on high temperature environment; furthermore, the aforementioned inert alloy anode has a quite low overvoltage, so power consumption of the aluminum electrolysis process can be reduced; the prepared inert alloy anode is even in texture and has a density within a range from 8.1 g/cm 3  to 8.3 g/cm 3 , in this way, stable service property of the inert alloy anode is guaranteed. 
         [0026]    (5) The preparing method of the inert alloy anode comprises the following steps: melting and uniformly mixing the metals Fe, Cu and Sn, and then rapidly casting and cooling the mixture to obtain the inert alloy anode; or, melting the metals Fe, Cu and Sn at first, then adding and melting the metal Al or Y, and uniformly mixing, or adding and melting the metal Al at first, then adding and melting the metal Y, uniformly mixing, and rapidly casting and cooling the mixture to obtain the inert alloy anode; or, melting and mixing the metals Fe, Cu, Ni and Sn and then casting the mixture to obtain the inert alloy anode; or, melting the metals Fe, Cu, Ni and Sn at first, then adding and melting the metal Al or Y, and uniformly mixing, or adding and melting the metal Al at first, then adding and melting the metal Y, uniformly mixing, and casting the mixture to obtain the inert alloy anode. The aforementioned inert alloy anode is simple in preparation process and can be prepared in any shape according to the actual needs. During preparation of the alloy containing the metals Al and Y, Al is added at first to prevent other molten metal components from being oxidized, and then, Y is added and molten to finally obtain the alloy having a desired crystal form. For more easily understanding the technical solution of the present invention, further description will be made below to the technical solution of the present invention in conjunction with the embodiments. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiment 1 
       [0027]    23 parts by weight of Fe metal blocks, 60 parts by weight of Cu metal blocks and 0.2 parts by weight of Sn metal blocks are molten and then uniformly mixed under high-speed electromagnetic stirring, the mixture is rapidly cast and then rapidly cooled at a speed of 20-100° C./s to obtain an inert alloy anode 1 which is homogeneous in texture. The inert alloy anode has a density of 8.3 g/cm 3 , a specific resistivity of 62 μΩ·cm and a melting point of 1400° C. 
       Embodiment 2 
       [0028]    40 parts by weight of Fe metal blocks, 36 parts by weight of Cu metal blocks and 5 parts by weight of Sn metal blocks are molten and then uniformly mixed under high-speed electromagnetic stirring, the mixture is rapidly cast and then rapidly cooled at a speed of 20-100° C./s to obtain an inert alloy anode 2 which is homogeneous in texture. The inert alloy anode has a density of 7.8 g/cm 3 , a specific resistivity of 82 μΩ·cm and a melting point of 1369° C. 
       Embodiment 3 
       [0029]    30 parts by weight of Fe metal blocks, 45 parts by weight of Cu metal blocks and 3 parts by weight of Sn metal blocks are molten and then uniformly mixed under high-speed electromagnetic stirring, the mixture is rapidly cast and then rapidly cooled at a speed of 20-100° C./s to obtain an inert alloy anode 3 which is homogeneous in texture. The inert alloy anode has a density of 7.9 g/cm 3 , a specific resistivity of 86 μΩ·cm and a melting point of 1390° C. 
       Embodiment 4 
       [0030]    30 parts by weight of Fe metal blocks, 50 parts by weight of Cu metal blocks, 20 parts by weight of Mo and 5 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 4. The inert alloy anode has a density of 8.2 g/cm 3 , a specific resistivity of 78 μΩ·cm and a melting point of 1370° C. 
       Embodiment 5 
       [0031]    23 parts by weight of Fe metal blocks, 60 parts by weight of Cu metal blocks, 14 parts by weight of Ni and 3 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 5. The inert alloy anode has a density of 8.3 g/cm 3 , a specific resistivity of 68 μΩ·cm and a melting point of 1360° C. 
       Embodiment 6 
       [0032]    40 parts by weight of Fe metal blocks, 36 parts by weight of Cu metal blocks, 19 parts by weight of Ni and 5 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 6. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 76.8 μΩ·cm and a melting point of 1386° C. 
       Embodiment 7 
       [0033]    25 parts by weight of Fe metal blocks, 46.8 parts by weight of Cu metal blocks, 28 parts by weight of Ni and 0.2 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 7. The inert alloy anode has a density of 8.2 g/cm 3 , a specific resistivity of 72 μΩ·cm and a melting point of 1350° C. 
       Embodiment 8 
       [0034]    23 parts by weight of Fe metal blocks, 60 parts by weight of Cu metal blocks, 14 parts by weight of Ni and 3 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 8. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 70 μΩ·cm and a melting point of 1330° C. 
       Embodiment 9 
       [0035]    40 parts by weight of Fe metal blocks, 36 parts by weight of Cu metal blocks, 19 parts by weight of Ni and 5 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 9. The inert alloy anode has a density of 8.2 g/cm 3 , a specific resistivity of 73 μΩ·cm and a melting point of 1340° C. 
       Embodiment 10 
       [0036]    24 parts by weight of Fe metal blocks, 47.8 parts by weight of Cu metal blocks, 28 parts by weight of Ni and 0.2 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 10. The inert alloy anode has a density of 8.0 g/cm 3 , a specific resistivity of 74 if and a melting point of 1350° C. 
       Embodiment 11 
       [0037]    30 parts by weight of Fe metal blocks, 41 parts by weight of Cu metal blocks and 5 parts by weight of Sn metal blocks are molten at first, then 3 parts by weight of Al metal blocks are added and sequentially molten, uniform mixing is performed under high-speed electromagnet stirring, and the mixture is rapidly cast and then rapidly cooled to obtain an inert alloy anode 11. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 68 μΩ·cm and a melting point of 1370° C. 
       Embodiment 12 
       [0038]    23 parts by weight of Fe metal blocks, 60 parts by weight of Cu metal blocks, 14 parts by weight of Ni and 0.2 parts by weight of Sn metal blocks are molten at first, then 2.8 parts by weight of Al metal blocks are added and sequentially molten, and an inert alloy anode 12 is obtained by casting. The inert alloy anode has a density of 8.4 g/cm 3 , a specific resistivity of 69 μΩ·cm and a melting point of 1340° C. 
       Embodiment 13 
       [0039]    40 parts by weight of Fe metal blocks, 36 parts by weight of Cu metal blocks, 15 parts by weight of Ni and 5 parts by weight of Sn metal blocks are molten at first, then 4 parts by weight of Al metal blocks are added and sequentially molten, and an inert alloy anode 13 is obtained by casting. The inert alloy anode has a density of 8.15 g/cm 3 , a specific resistivity of 69 μΩ·cm and a melting point of 1369° C. 
       Embodiment 14 
       [0040]    36 parts by weight of Fe metal blocks, 47 parts by weight of Cu metal blocks, 14 parts by weight of Ni and 2.9 parts by weight of Sn metal blocks are molten at first, then 0.1 parts by weight of Al metal blocks are added and sequentially molten, and an inert alloy anode 14 is obtained by casting. The inert alloy anode has a density of 8.0 g/cm 3 , a specific resistivity of 67.6 μΩ·cm and a melting point of 1379° C. 
       Embodiment 15 
       [0041]    27 parts by weight of Fe metal blocks, 50 parts by weight of Cu metal blocks and 4 parts by weight of Sn metal blocks are molten at first, then 1 part by weight of Y metal blocks are added and sequentially molten, uniform mixing is performed under high-speed electromagnet stirring, and the mixture is rapidly cast and then rapidly cooled to obtain an inert alloy anode 15. The inert alloy anode has a density of 8.4 g/cm 3 , a specific resistivity of 67 μΩ·cm and a melting point of 1358° C. 
       Embodiment 16 
       [0042]    35 parts by weight of Fe metal blocks, 45 parts by weight of Cu metal blocks, 24 parts by weight of Ni and 4 parts by weight of Sn metal blocks are molten at first, then 2 parts by weight of Y metal blocks are added and sequentially molten, and an inert alloy anode 16 is obtained by casting. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 70.9 μΩ·cm and a melting point of 1375° C. 
       Embodiment 17 
       [0043]    25 parts by weight of Fe metal blocks, 50 parts by weight of Cu metal blocks and 4 parts by weight of Sn metal blocks are molten at first, then 3 parts by weight of Al metal blocks are added and sequentially molten, finally, 1 part by weight of Y metal blocks are added and molten, uniform mixing is performed under high-speed electromagnet stirring, and the mixture is rapidly cast and then rapidly cooled to obtain an inert alloy anode 17. The inert alloy anode has a density of 8.3 g/cm 3 , a specific resistivity of 68.9 μΩ·cm and a melting point of 1381° C. 
       Embodiment 18 
       [0044]    23 parts by weight of Fe metal blocks, 60 parts by weight of Cu metal blocks, 14 parts by weight of Ni and 0.9 parts by weight of Sn metal blocks are molten at first, then 0.1 parts by weight of Al metal blocks are added and sequentially molten, finally, 2 parts by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 18. The inert alloy anode has a density of 8.3 g/cm 3 , a specific resistivity of 6842 μΩ·cm and a melting point of 1360° C. 
       Embodiment 19 
       [0045]    40 parts by weight of Fe metal blocks, 36 parts by weight of Cu metal blocks, 14.9 parts by weight of Ni and 5 parts by weight of Sn metal blocks are molten at first, then 4 parts by weight of Al metal blocks are added and sequentially molten, finally, 0.1 parts by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 19. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 76.8 μΩ·cm and a melting point of 1386° C. 
       Embodiment 20 
       [0046]    29 parts by weight of Fe metal blocks, 38.3 parts by weight of Cu metal blocks, 28 parts by weight of Ni and 0.2 parts by weight of Sn metal blocks are molten at first, then 3.5 parts by weight of Al metal blocks are added and sequentially molten, finally, 1 part by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 20. The inert alloy anode has a density of 8.2 g/cm 3 , a specific resistivity of 70 μΩ·cm and a melting point of 1365° C. 
       Embodiment 21 
       [0047]    40 parts by weight of Fe metal blocks, 36.5 parts by weight of Cu metal blocks, 18 parts by weight of Ni and 3 parts by weight of Sn metal blocks are molten at first, then 1.5 parts by weight of Al metal blocks are added and sequentially molten, finally, 1 part by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 21. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 76.8 μΩ·cm and a melting point of 1386° C. 
       Embodiment 22 
       [0048]    24.3 parts by weight of Fe metal blocks, 59 parts by weight of Cu metal blocks, 14 parts by weight of Ni and 0.2 parts by weight of Sn metal blocks are molten at first, then 2 parts by weight of Al metal blocks are added and sequentially molten, finally, 0.5 parts by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 22. The inert alloy anode has a density of 8.22 g/cm 3 , a specific resistivity of 68.2 μΩ·cm and a melting point of 1360° C. 
         [0049]    In the aforementioned embodiment, 1 part by weight is 10 g, and the inert anode alloy resulted from casting can be in any shape as required. 
       Embodiment 23 
       [0050]    40.01 parts by weight of Fe metal blocks, 35.9 parts by weight of Cu metal blocks and 0.19 parts by weight of Sn metal blocks are molten and then uniformly mixed under high-speed electromagnetic stirring, the mixture is rapidly cast and then rapidly cooled at a speed of 20-100° C./s to obtain an inert alloy anode 23 which is homogeneous in texture. The inert alloy anode has a density of 8.2 g/cm 3 , a specific resistivity of 61 μΩ·cm and a melting point of 1400° C. 
       Embodiment 24 
       [0051]    80 parts by weight of Fe metal blocks, 0.01 parts by weight of Cu metal blocks and 0.01 parts by weight of Sn metal blocks are molten and then uniformly mixed under high-speed electromagnetic stirring, the mixture is rapidly cast and then rapidly cooled at a speed of 20-100° C./s to obtain an inert alloy anode 24 which is homogeneous in texture. The inert alloy anode has a density of 7.5 g/cm 3 , a specific resistivity of 82 μΩ·cm and a melting point of 1369° C. 
       Embodiment 25 
       [0052]    60 parts by weight of Fe metal blocks, 25 parts by weight of Cu metal blocks and 0.1 part by weight of Sn metal blocks are molten and then uniformly mixed under high-speed electromagnetic stirring, the mixture is rapidly cast and then rapidly cooled at a speed of 20-100° C./s to obtain an inert alloy anode 25 which is homogeneous in texture. The inert alloy anode has a density of 7.9 g/cm 3 , a specific resistivity of 84 μΩ·cm and a melting point of 1390° C. 
       Embodiment 26 
       [0053]    50 parts by weight of Fe metal blocks, 30 parts by weight of Cu metal blocks, 20 parts by weight of Mo and 0.05 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 26. The inert alloy anode has a density of 8.4 g/cm 3 , a specific resistivity of 78 μΩ·cm and a melting point of 1370° C. 
       Embodiment 27 
       [0054]    40.01 parts by weight of Fe metal blocks, 35.9 parts by weight of Cu metal blocks, 70 parts by weight of Ni and 0.01 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 27. The inert alloy anode has a density of 8.5 g/cm 3 , a specific resistivity of 68 μΩ·cm and a melting point of 1360° C. 
       Embodiment 28 
       [0055]    80 parts by weight of Fe metal blocks, 0.01 parts by weight of Cu metal blocks, 28.1 parts by weight of Ni and 0.19 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 28. The inert alloy anode has a density of 7.7 g/cm 3 , a specific resistivity of 76.8 μΩ·cm and a melting point of 1386° C. 
       Embodiment 29 
       [0056]    71.88 parts by weight of Fe metal blocks, 0.01 parts by weight of Cu metal blocks, 28.1 parts by weight of Ni and 0.01 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 29. The inert alloy anode has a density of 8.2 g/cm 3 , a specific resistivity of 72 μΩ·cm and a melting point of 1350° C. 
       Embodiment 30 
       [0057]    40.01 parts by weight of Fe metal blocks, 31.88 parts by weight of Cu metal blocks, 28.1 parts by weight of Ni and 0.01 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 30. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 70 μΩ·cm and a melting point of 1330° C. 
       Embodiment 31 
       [0058]    40 parts by weight of Fe metal blocks, 0.02 parts by weight of Cu metal blocks, 59.97 parts by weight of Ni and 0.01 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 31. The inert alloy anode has a density of 8.2 g/cm 3 , a specific resistivity of 73 μΩ·cm and a melting point of 1340° C. 
       Embodiment 32 
       [0059]    45 parts by weight of Fe metal blocks, 4.81 parts by weight of Cu metal blocks, 50 parts by weight of Ni and 0.19 parts by weight of Sn metal blocks are molten and then cast to obtain an inert alloy anode 32. The inert alloy anode has a density of 8.0 g/cm 3 , a specific resistivity of 74 μΩ·cm and a melting point of 1350° C. 
       Embodiment 33 
       [0060]    60 parts by weight of Fe metal blocks, 35.9 parts by weight of Cu metal blocks and 0.1 parts by weight of Sn metal blocks are molten at first, then 4 parts by weight of Al metal blocks are added and sequentially molten, uniformly mixing is performed under high-speed electromagnetic stirring, and the mixture is rapidly cast and then rapidly cooled to obtain an inert alloy anode 33. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 68 μΩ·cm and a melting point of 1370° C. 
       Embodiment 34 
       [0061]    40.01 parts by weight of Fe metal blocks, 27.7 parts by weight of Cu metal blocks, 28.1 parts by weight of Ni and 0.19 parts by weight of Sn metal blocks are molten at first, then 4 parts by weight of Al metal blocks are added and sequentially molten, and an inert alloy anode 34 is obtained by casting. The inert alloy anode has a density of 8.4 g/cm 3 , a specific resistivity of 69 μΩ·cm and a melting point of 1340° C. 
       Embodiment 35 
       [0062]    71.88 parts by weight of Fe metal blocks, 0.005 parts by weight of Cu metal blocks, 28.1 parts by weight of Ni and 0.01 parts by weight of Sn metal blocks are molten at first, then 0.005 parts by weight of Al metal blocks are added and sequentially molten, and an inert alloy anode 35 is obtained by casting. The inert alloy anode has a density of 8.15 g/cm 3 , a specific resistivity of 69 μΩ·cm and a melting point of 1369° C. 
       Embodiment 36 
       [0063]    40.01 parts by weight of Fe metal blocks, 31.88 parts by weight of Cu metal blocks, 25.01 parts by weight of Ni and 0.1 parts by weight of Sn metal blocks are molten at first, then 3 parts by weight of Al metal blocks are added and sequentially molten, and an inert alloy anode 36 is obtained by casting. The inert alloy anode has a density of 8.0 g/cm 3 , a specific resistivity of 67.6 μΩ·cm and a melting point of 1379° C. 
       Embodiment 37 
       [0064]    66 parts by weight of Fe metal blocks, 31.88 parts by weight of Cu metal blocks and 0.01 parts by weight of Sn metal blocks are molten at first, then 2 parts by weight of Y metal blocks are added and sequentially molten, uniformly mixing is performed under high-speed electromagnetic stirring, and the mixture is rapidly cast and then rapidly cooled to obtain an inert alloy anode 37. The inert alloy anode has a density of 8.4 g/cm 3 , a specific resistivity of 67 μΩ·cm and a melting point of 1358° C. 
       Embodiment 38 
       [0065]    40 parts by weight of Fe metal blocks, 0.01 parts by weight of Cu metal blocks, 59.97 parts by weight of Ni and 0.01 parts by weight of Sn metal blocks are molten at first, then 0.01 parts by weight of Y metal blocks are added and sequentially molten, and an inert alloy anode 38 is obtained by casting. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 70.9 μΩ·cm and a melting point of 1375° C. 
       Embodiment 39 
       [0066]    62 parts by weight of Fe metal blocks, 31.88 parts by weight of Cu metal blocks and 0.19 parts by weight of Sn metal blocks are molten at first, then, 4 parts by weight of Al metal blocks are added and sequentially molten, finally, 2 parts by weight of Y metal blocks are added and molten, uniform mixing is performed under high-speed electromagnet stirring, and the mixture is rapidly cast and then rapidly cooled to obtain an inert alloy anode 39. The inert alloy anode has a density of 8.3 g/cm 3 , a specific resistivity of 68.9 μΩ·cm and a melting point of 1381° C. 
       Embodiment 40 
       [0067]    40 parts by weight of Fe metal blocks, 25.7 parts by weight of Cu metal blocks, 28.1 parts by weight of Ni and 0.19 parts by weight of Sn metal blocks are molten at first, then 4 parts by weight of Al metal blocks are added and sequentially molten, finally, 2 parts by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 40. The inert alloy anode has a density of 8.3 g/cm 3 , a specific resistivity of 68 μΩ·cm and a melting point of 1360° C. 
       Embodiment 41 
       [0068]    71.88 parts by weight of Fe metal blocks, 0.005 parts by weight of Cu metal blocks, 28.1 parts by weight of Ni and 0.01 parts by weight of Sn metal blocks are molten at first, then, 0.002 parts by weight of Al metal blocks are added and sequentially molten, finally, 0.003 parts by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 41. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 76.8 μΩ·cm and a melting point of 1386° C. 
       Embodiment 42 
       [0069]    36.92 parts by weight of Fe metal blocks, 31.88 parts by weight of Cu metal blocks, 28.1 parts by weight of Ni and 0.1 parts by weight of Sn metal blocks are molten at first, then 1 part by weight of Al metal blocks are added and sequentially molten, finally, 2 parts by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 42. The inert alloy anode has a density of 8.2 g/cm 3 , a specific resistivity of 70 μΩ·cm and a melting point of 1365° C. 
       Embodiment 43 
       [0070]    39.81 parts by weight of Fe metal blocks, 0.01 parts by weight of Cu metal blocks, 59.97 parts by weight of Ni and 0.01 parts by weight of Sn metal blocks are molten at first, then 0.1 parts by weight of Al metal blocks are added and sequentially molten, finally, 0.1 parts by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 43. The inert alloy anode has a density of 8.1 g/cm 3 , a specific resistivity of 76.8 μΩ·cm and a melting point of 1386° C. 
       Embodiment 44 
       [0071]    45 parts by weight of Fe metal blocks, 24.4 parts by weight of Cu metal blocks, 29 parts by weight of Ni and 0.1 parts by weight of Sn metal blocks are molten at first, then 1 part by weight of Al metal blocks are added and sequentially molten, finally, 0.5 parts by weight of Y metal blocks are added and molten, mixing is performed, and the mixture is cast to obtain an inert alloy anode 44. The inert alloy anode has a density of 8.22 g/cm 3 , a specific resistivity of 68.2 μΩ·cm and a melting point of 1360° C. 
         [0072]    In the aforementioned embodiments 23-44, 1 part by weight is 100 g, and the inert anode alloy resulted from casting can be in any shape as required. 
       Comparative Example 
       [0073]    The alloy powders containing 37 wt % of Co, 18 wt % of Cu, 19 wt % of Ni, 23 wt % of Fe and 3 wt % of Ag are subjected to powder metallurgic process to obtain an anode, and before use, an oxide film is formed on the surface of the metal anode by pre-oxidization at 1000° C. to obtain an inert alloy anode A. 
       Test Example 
       [0074]    The inert alloy anodes 1-44 and A are each taken as an anode, graphite is taken as a cathode, the anode and the cathode are vertically inserted into an electrolytic cell provided with a corundum liner, and the distance between the anode and the cathode is 3 cm. The anode has a current density of 1.0 A/cm 2  at 760° C., and is electrolyzed for up to 40 hours in an electrolyte having the components including 32 wt % of sodium fluoride, 57 wt % of aluminum fluoride, 3 wt % of lithium fluoride, 4 wt % of potassium fluoride and 4 wt % of alumina, and the test results are shown in the Table below: 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                   
                 Direct Current 
                 Purity of 
               
               
                   
                 Inert 
                 Cell 
                 Consumption for 
                 Product 
               
               
                   
                 Alloy 
                 Voltage 
                 Per Ton of 
                 Aluminum 
               
               
                   
                 Anode 
                 (V) 
                 Aluminum (kw · h) 
                 (%) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 1 
                 3.10 
                 10040 
                 99.80 
               
               
                   
                 2 
                 3.14 
                 10170 
                 99.81 
               
               
                   
                 3 
                 3.22 
                 10429 
                 99.85 
               
               
                   
                 4 
                 3.16 
                 10235 
                 99.80 
               
               
                   
                 5 
                 3.10 
                 10040 
                 99.85 
               
               
                   
                 6 
                 3.39 
                 10979 
                 99.82 
               
               
                   
                 7 
                 3.15 
                 10202 
                 99.85 
               
               
                   
                 8 
                 3.27 
                 10591 
                 99.85 
               
               
                   
                 9 
                 3.18 
                 10299 
                 99.83 
               
               
                   
                 10 
                 3.36 
                 10882 
                 99.81 
               
               
                   
                 11 
                 3.28 
                 10623 
                 99.80 
               
               
                   
                 12 
                 3.40 
                 11000 
                 99.82 
               
               
                   
                 13 
                 3.32 
                 10753 
                 99.84 
               
               
                   
                 14 
                 3.25 
                 10526 
                 99.82 
               
               
                   
                 15 
                 3.12 
                 10105 
                 99.80 
               
               
                   
                 16 
                 3.27 
                 10591 
                 99.81 
               
               
                   
                 17 
                 3.35 
                 10850 
                 99.83 
               
               
                   
                 18 
                 3.38 
                 10947 
                 99.80 
               
               
                   
                 19 
                 3.16 
                 10234 
                 99.82 
               
               
                   
                 20 
                 3.32 
                 10753 
                 99.83 
               
               
                   
                 21 
                 3.10 
                 10040 
                 99.81 
               
               
                   
                 22 
                 3.12 
                 10105 
                 99.82 
               
               
                   
                 23 
                 3.11 
                 10040 
                 99.80 
               
               
                   
                 24 
                 3.13 
                 10159 
                 99.81 
               
               
                   
                 25 
                 3.21 
                 10429 
                 99.85 
               
               
                   
                 26 
                 3.15 
                 10236 
                 99.80 
               
               
                   
                 27 
                 3.11 
                 10041 
                 99.90 
               
               
                   
                 28 
                 3.38 
                 10979 
                 99.82 
               
               
                   
                 29 
                 3.14 
                 10202 
                 99.85 
               
               
                   
                 30 
                 3.26 
                 10591 
                 99.91 
               
               
                   
                 31 
                 3.17 
                 10299 
                 99.83 
               
               
                   
                 32 
                 3.35 
                 10879 
                 99.81 
               
               
                   
                 33 
                 3.27 
                 10623 
                 99.80 
               
               
                   
                 34 
                 3.39 
                 11000 
                 99.82 
               
               
                   
                 35 
                 3.33 
                 10753 
                 99.84 
               
               
                   
                 36 
                 3.25 
                 10526 
                 99.82 
               
               
                   
                 37 
                 3.12 
                 10105 
                 99.80 
               
               
                   
                 38 
                 3.27 
                 10591 
                 99.81 
               
               
                   
                 39 
                 3.35 
                 10850 
                 99.83 
               
               
                   
                 40 
                 3.38 
                 10945 
                 99.80 
               
               
                   
                 41 
                 3.16 
                 10234 
                 99.82 
               
               
                   
                 42 
                 3.32 
                 10753 
                 99.83 
               
               
                   
                 43 
                 3.10 
                 10040 
                 99.81 
               
               
                   
                 44 
                 3.12 
                 10110 
                 99.82 
               
               
                   
                 A 
                 4.48 
                 14510 
                 98.35 
               
               
                   
                   
               
             
          
         
       
     
         [0075]    It can be seen from the test results of the aforementioned embodiments and the comparative example that in the process of aluminum electrolysis, the inert alloy anode in the present invention has a cell voltage much lower than that of the alloy anode in the comparative example, consequently, using the inert alloy anode in the present invention can reduce the power consumption in an aluminum electrolysis process remarkably, which further reduces energy waste and lower cost. Meanwhile, the inert alloy anode in the present invention can be used for producing aluminum products which meet the high-purity standard, i.e. the purity of these aluminum products can be over 99.8, which meets the national primary aluminum standard. Detailed description has been made to the specific contents of the present invention in the aforementioned embodiments, and it should be understood by those skilled in this art that modifications and detail variations in any form based upon the present invention pertain to the scope that the present invention seeks to protect.