Process for processing red mud and producing rare-earth metal salts

Abstract

The invention relates to a process for processing red mud, said process comprising the following steps: (a) providing red mud waste of alumina production (in the following: red mud); (b) further, providing waste containing organic material, and converting to synthesis gas by high temperature pyrolysis; (c) converting the sodium oxide present in the red mud in the form of soluble glass to sodium carbonate with carbonic acid; (d1) magnetizing the Fe 2 O 3 hematite ferric oxide present in the red mud and separating the anti-ferromagnetic Fe 2 O 3 hematite ferric oxide from the remained slurry by magnetic separator; (d2) converting the Fe 2 O 3 hematite ferric oxide present in the red mud to Fe 3 O 4 magnetite ferrous ferric oxide with synthesis gas, and separating the Fe 3 O 4 magnetite ferrous ferric oxide from the remained slurry by magnetic separator; (e) treating the remained slurry obtained in steps (d1) or (d2) with strong acid, thus obtaining metal sulphate solution and SiO 2 and TiO 2 suspension.

1 . Process for recovering the iron oxide content of red mud, said process comprising the step of converting the sodium oxide present in the red mud in the form of soluble glass to sodium carbonate with carbonic acid. 
     
     
         2 . Process for the utilization of red mud, said process comprising the following steps:
 (a) providing red mud waste of alumina production;   (b) further, providing waste containing organic material, and converting of it to synthesis gas by high temperature pyrolysis;   (c) converting the sodium oxide present in the red mud in the form of soluble glass to sodium carbonate with carbonic acid;   (d1) magnetizing the Fe 2 O 3  hematite ferric oxide present in the red mud and separating the anti-ferromagnetic Fe 2 O 3  hematite ferric oxide from the remained slurry by magnetic separator; and/or   (d2) converting the Fe 2 O 3  hematite ferric oxide present in the red mud to Fe 3 O 4  magnetite ferrous ferric oxide with synthesis gas, and separating the Fe 3 O 4  magnetite ferrous ferric oxide from the remained slurry by magnetic separator; and   (e) treating the remained slurry obtained in steps (d1) or (d2) with strong acid, thus obtaining metal sulphate solution and SiO 2  and TiO 2  suspension.   
     
     
         3 . The process as claimed in  claim 2 , said process comprising the following steps:
 (d3) treating the Fe 2 O 3  hematite ferric oxide obtained in step (d1) and/or the Fe 3 O 4  magnetite ferrous ferric oxide obtained in step (d2) with the synthesis gas obtained in step (b), in which pure iron (Fe) is obtained.   
     
     
         4 . The process as claimed in  claim 3 , said process comprising the following steps:
 (d4) treating the Fe iron obtained in step (d3) with CO carbon monoxide gas, in which Fe(CO) 5  iron pentacarbonyl is obtained.   
     
     
         5 . The process as claimed in  claim 2 , said process comprising the following steps:
 (e1) recovering the metals and rare-earth metals from the metal sulphates and rare-earth sulphates in the metal sulphate solution obtained in step (e) in a conventional manner.   
     
     
         6 . The process as claimed in  claim 2 , said process further comprising the following steps:
 (e2) separating the SiO 2  and TiO 2  slurry obtained in step (e) by conventional techniques, obtaining pure SiO 2  quartz sand, and pure TiO 2  titanium dioxide.   
     
     
         7 . The process as claimed in  claim 2 , wherein 1:1 mole ratio CO+H 2  synthesis gas is used. 
     
     
         8 . The process as claimed in  claim 2 , wherein the waste containing organic material is a waste containing cellulose, especially selected from the group of waste paper, rice husking residues, straw, hemp, flax, the products of them, and the like; and the pyrolyisis is performed in a drum-type furnace. 
     
     
         9 . The process as claimed in  claim 2 , wherein the waste containing organic material is a waste containing dioxin and/or furan, especially selected from the group of waste oil, transformer oil, agricultural chemicals residue, and the like, or other industrial hazardous waste, especially selected from the group of bated leather waste, oil sludge, contaminated gas black, tarry waste, and the pyrolysis is performed in a plasma forge. 
     
     
         10 . The process as claimed in  claim 2 , said process comprising the following steps:
 (a) providing red mud waste of alumina production (in the following: red mud);   (b) further, providing waste containing organic material, and converting to synthesis gas by high temperature pyrolysis;   (c) converting the sodium oxide present in the red mud in the form of soluble glass to sodium carbonate with carbonic acid;   (d1) magnetizing the Fe 2 O 3  hematite ferric oxide present in the red mud and separating the anti-ferromagnetic Fe 2 O 3  hematite ferric oxide from the remained slurry by magnetic separator; and/or   (d2) converting the Fe 2 O 3  hematite ferric oxide present in the red mud to Fe 3 O 4  magnetite ferrous ferric oxide with synthesis gas, and separating the Fe 3 O 4  magnetite ferrous ferric oxide from the remained slurry by magnetic separator; and/or   (d3) treating the Fe 2 O 3  hematite ferric oxide obtained in step (d1) and/or the Fe 3 O 4  magnetite ferrous ferri oxide obtained in step (d2) with the synthesis gas obtained in step (b), in which pure iron (Fe) is obtained;   (d4) treating the iron (Fe) obtained in step (d3) with carbon monoxide gas (CO), in which Fe(CO) 5  iron pentacarbonyl is obtained,   (e) treating the remained slurry obtained in steps (d1) or (d2) with strong acid, thus obtaining a metal sulphate solution and SiO 2  and TiO 2  suspension;   (e1) recovering the metals and rare-earth metals from the metal sulphates and rare-earth sulphates in the metal sulphate solution obtained in step (e) in a conventional manner.   
     
     
         11 . The process as claimed in  claim 10 , said process further comprising the following steps:
 (e2) separating the SiO 2  and TiO 2  slurry obtained in step (e) by conventional techniques, obtaining pure SiO 2  quartz sand, and pure TiO 2  titanium dioxide.