Processes for treating red mud
There are provided processes for treating red mud. For example, the processes can comprise leaching red mud with HCl so as to obtain a leachate comprising ions of a first metal (for example aluminum) and a solid, and separating said solid from said leachate. Several other metals can be extracted from the leachate (Fe, Ni, Co, Mg, rare earth elements, rare metals, etc.). Various other components can be extracted from solid such as TiO 2 , SiO 2 etc.
1. A process for preparing titanium oxide, said process comprising:
leaching red mud with HCl to obtain a first leachate comprising ions from at least one metal and a solid, and separating said solid from said first leachate;
at least substantially isolating said ions of said at least one metal from said first leachate;
leaching said solid with HCl in the presence of a chloride chosen from alkali metal chlorides and alkaline earth metal chlorides to obtain a second leachate comprising titanium chloride; and
converting said titanium chloride into titanium oxide.
2. The process of claim 1 , wherein said chloride is chosen from alkaline earth metal chlorides.
3. The process of claim 1 , wherein said chloride is calcium chloride or magnesium chloride.
4. The process of claim 1 , wherein said chloride is magnesium chloride.
5. The process of claim 1 , wherein said at least one metal comprises a first metal chosen from aluminum, iron, zinc, copper, gold, silver, molybdenum, cobalt, magnesium, lithium, manganese, nickel, palladium, platinum, thorium, phosphorus, uranium and titanium, at least one rare earth element or at least one rare metal.
6. The process of claim 5 , wherein said first metal is aluminum.
7. The process of claim 6 , wherein said process comprises reacting said first leachate with gaseous HCl as to obtain said liquid and said precipitate comprising aluminum ions, said precipitate being formed by crystallization of AlCl 3 .6H 2 O.
8. The process of claim 6 , wherein said process comprises reacting said first leachate with dry gaseous HCl to obtain said liquid and said precipitate comprising aluminum ions, said precipitate being formed by crystallization of AlCl 3 .6H 2 O.
9. The process of claim 8 , wherein said first leachate comprises Al ions and/or Fe ions.
10. The process of claim 8 , wherein said Al ions are substantially selectively precipitated from said first leachate under the form of AlCl 3 .
11. The process of claim 9 , wherein said Fe ions are substantially selectively extracted by converting them into Fe 2 O 3 via an hydrolysis.
12. A process for preparing titanium oxide, said process comprising:
leaching red mud with HCl to obtain a first leachate comprising ions from at least one metal and a solid that comprises TiO 2 and SiO 2 , and separating said solid from said first leachate;
at least substantially isolating said ions of said at least one metal from said first leachate;
reacting said solid with Cl 2 and a carbon source to obtain a liquid portion comprising titanium chloride and a solid portion, and separating said liquid portion from said solid portion;
and
converting said titanium chloride into titanium oxide.
13. The process of claim 12 , wherein said leaching is carried out at a temperature of about 125 to about 225° C.
14. The process of claim 13 , comprising heating titanium chloride to convert same into TiO 2 .