Novel material and production thereof for use as storage medium in a sensitive energy storage system in the low-; medium- or high temperature sector

Abstract

The present invention relates to a modified red sludge or a modified bauxite residue and processes for producing same, and to a storage medium comprising a modified red sludge, a heat store comprising a storage medium and numerous uses of a It modified red sludge as storage medium, more particularly in a heat store system. The modified red sludge here contains the following components: —haematite (Fe 2 O 3 ), —corundum (Al 2 O 3 ), —rutile (TiO 2 ) and/or anatase (TiO 2 ), —quartz (SiO 2 ), —optionally perovskite (CaTiO 3 ) and —optionally pseudobrookite ((Fe 3+ , Fe2+) 2 (Ti, Fe 3+ )O 5 ) and/or nepheline ((Na,K)[AlSiO 4 ]). A novel material is thus provided, and production thereof is described for use as storage medium in a sensitive energy storage system in the low-, medium- or high-temperature sector.

1 - 31 . (canceled) 
     
     
         32 . A modified red mud comprising:
 haematite (Fe 2 O 3 ),   corundum (Al 2 O 3 ),   rutile (TiO 2 ) and/or anatase (TiO 2 ), and   quartz (SiO 2 ).   
     
     
         33 . The modified red mud of  claim 32  further comprising at least one of perovskite (CaTiO 3 ) and pseudobrookite ((Fe 3+ ,Fe 2+ ) 2 (Ti,Fe 3+ )O 5 ). 
     
     
         34 . The modified red mud of  claim 32  further comprising nepheline ((Na,K)[AlSiO 4 ]). 
     
     
         35 . The modified red mud of  claim 32  comprising:
 48 to 55% by weight of haematite (Fe 2 O 3 ), 
 13 to 18% by weight of corundum (Al 2 O 3 ), 
 8 to 12% by weight of rutile (TiO 2 ) and/or anatase (TiO 2 ), and 
 2 to 5% by weight of quartz (SiO 2 ). 
 
     
     
         36 . The modified red mud of  claim 32 , wherein the modified red mud has a density in the range from 3.90 to 4.0 g/cm 3 . 
     
     
         37 . The modified red mud of  claim 32 , wherein the modified red mud has a mean particle size d50 in the range from 3 to 10 μm. 
     
     
         38 . The modified red mud of  claim 32 , wherein the modified red mud has a particle size d10 in the range from 0.5 to 2.5 μm and/or a particle size d90 in the range from 15 to 50 μm. 
     
     
         39 . The modified red mud of  claim 32 , wherein the modified red mud has a specific thermal capacity at 20° C. in the range from 0.6 to 0.8 kJ/(kg*K) and/or a specific thermal capacity at 726.8° C. in the range from 0.9 to 1.3 kJ/(kg*K). 
     
     
         40 . The modified red mud of  claim 32 , wherein the modified red mud has a specific thermal conductivity in the range from 3 to 35 W/(m*K). 
     
     
         41 . The modified red mud of  claim 32  further comprising one or more of the following components:
 an agent for preventing inclusion of air and air adsorption, 
 an agent for improvement of the thermal conductivity, in particular selected from the group consisting of metal colloids, metal powder, graphite and substances containing silicon, and 
 an agent for formation of a thixotropic composition. 
 
     
     
         42 . The modified red mud of  claim 32  wherein the modified red mud comprises an energy storage medium that can be repeatedly heated and cooled. 
     
     
         43 . The modified red mud of  claim 42  further comprising at least one device for charging and discharging heat to and from the modified red mud. 
     
     
         44 . The energy storage system of  claim 43  wherein the at least one device comprises resistance wires. 
     
     
         45 . A method for producing a modified red mud comprising heating a red mud with a mineral composition of 10 to 55% by weight of iron compounds, 12 to 35% by weight of aluminium compounds, 3 to 17% by weight of silicon compounds, 2 to 12% by weight of titanium dioxide, and 0.5 to 6% by weight of calcium compounds, to a temperature of at least 800° C. in an oxygen (O 2 ) atmosphere. 
     
     
         46 . The method of  claim 45  further comprising heating the red mud to a temperature of at least 1000° C. 
     
     
         47 . The method of  claim 45  further comprising compressing the red mud after the heating. 
     
     
         48 . A method of storing energy comprising:
 repeatedly heating and cooling a modified red mud that comprises the following components:   haematite (Fe 2 O 3 ),   corundum (Al 2 O 3 ),   rutile (TiO 2 ) and/or anatase (TiO 2 ), and   quartz (SiO 2 ).   
     
     
         49 . The method of  claim 48  further comprising storing heat energy within the modified red mud at a temperature of more than 100° C. and up to 1000° C. 
     
     
         50 . The method of  claim 48  further comprising simultaneously heating and cooling the modified red mud. 
     
     
         51 . The method of  claim 48  further comprising heating the modified red mud by means of electrical current and/or cooling the modified red mud while electrical current is generated. 
     
     
         52 . The method of  claim 51  further comprising heating the modified red mud by means of electrical power obtained from at least one renewable energy source. 
     
     
         53 . The method of  claim 51  further comprising heating the modified red mud by applying electrical current to resistance wires located within the modified red mud. 
     
     
         54 . The method of  claim 51  further comprising cooling the modified red mud by transferring thermal power stored in the modified red mud to another medium, wherein the another medium comprises one of water, molten salt, and thermal oil.