Processes for treating aluminium dross residues
There is provided a process for preparing aluminium chloride comprising leaching aluminium dross residues with H 2 SO 4 so as to obtain a leachate; and hydrochlorinating the leachate so as to obtain aluminium chloride. If desired, aluminium chloride can then be converted into alumina.
1. A process for treating aluminium dross residues comprising:
leaching aluminium dross residues, at a temperature of at least 200° C., with H 2 SO 4 having a concentration of about 98% so as to obtain a mixture comprising a solid and a liquid, and separating said solid from said liquid;
solubilizing in water at least a portion of minerals and metals contained in said solid so as to obtain a leachate;
hydrochlorinating said leachate so as to obtain aluminium chloride; and
converting said aluminium chloride into alumina,
wherein in said process, at least 80% by weight of the Al atoms contained in the aluminium dross residues are converted into alumina.
2. The process of claim 1 , wherein said leaching is carried out at a temperature of at least 225° C.
3. The process of claim 1 , wherein said leaching is carried out at a temperature of about 275° C.
4. The process of claim 1 , wherein said leaching step is carried out at a temperature of at least 250° C.
5. The process of claim 1 , wherein the solid is treated with water having a temperature of at least 50° C. so as to solubilize metals and minerals contained therein and to obtain said leachate.
6. The process of claim 1 , wherein the solid is treated with water having a temperature of at least 70° C. so as to solubilize metals and minerals contained therein and to obtain said leachate.
7. The process of claim 6 , wherein said leachate is hydrochlorinated with gaseous HCI.
8. The process of claim 7 , wherein said hydrochlorination is carried out at a temperature of about −10° C. to about 20° C.
9. The process of claim 2 , wherein said hydrochlorination is carried out at a temperature of about −10° C. to about 0° C.
10. The process of claim 1 , wherein in said process, at least 90% by weight of the Al atoms contained in the aluminium dross residues are converted into alumina.
11. The process of claim 8 , wherein the aluminium chloride is converted into alumina at a temperature of about 950° C. to 1150° C.
12. A process for treating aluminium dross residues comprising:
treating aluminium dross residues so as to reduce the amount of aluminium nitride present therein;
leaching said aluminium dross residues having a reduced amount of aluminium nitride, at a temperature of at least 200° C., with H 2 SO 4 having a concentration of about 98% so as to obtain a mixture comprising a solid and a liquid, and separating said solid from said liquid;
solubilizing in water at least a portion of minerals and metals contained in said solid so as to obtain a leachate; and
hydrochlorinating said leachate so as to obtain aluminium chloride; and
converting said aluminium chloride into alumina,
wherein in said process, at least 80% by weight of the Al atoms contained in the aluminium dross residues are converted into alumina.
13. The process of claim 12 , wherein the amount of aluminium nitride is reduced by converting aluminium nitride into aluminium hydroxide.
14. The process of claim 13 , wherein aluminium nitride is converted into aluminium hydroxide by reacting said aluminium dross residues with water having a temperature of at least 80° C.
15. The process of claim 13 , wherein aluminium nitride is converted into aluminium hydroxide by reacting said aluminium dross residues with water being at temperature around its boiling point.
16. The process of claim 14 , wherein at least 80% of the aluminium nitride present in the aluminium dross residues is converted into aluminium hydroxide.
17. The process of claim 12 , wherein in said process, at least 95% by weight of the Al atoms contained in the aluminium dross residues are converted into alumina.
18. The process of claim 14 , wherein the aluminium chloride is converted into alumina at a temperature of about 950° C. to 1150° C.
19. A process for treating aluminium dross residues comprising:
treating aluminium dross residues so as to reduce the amount of aluminium nitride present therein by treating said aluminium dross residues with water having a temperature of at least 80° C. so as to obtain a first solid and a first liquid, and separating said first solid from said first liquid;
pre-leaching said first solid with H 2 SO 4 recovered from a H 2 SO 4 leaching step so as to obtain a second solid and a second liquid, and separating said second solid from said second liquid;
carrying out said H 2 SO 4 leaching step by leaching said second solid at a temperature of at least 200° C., with H 2 SO 4 having a concentration of about 98% so as to obtain a mixture and treating said mixture with water so as to solubilize at least a portion of minerals and metals contained in said mixture and carrying out a filtration so as to obtain a third liquid that comprises said H 2 SO 4 recovered from a H 2 SO 4 leaching step and;
hydrochlorinating said second liquid so as to obtain aluminium chloride; and
converting said aluminium chloride into alumina,
wherein in said process, at least 80% by weight of the Al atoms contained in the aluminium dross residues are converted into alumina.
20. The process of claim 19 , wherein said leaching is carried out at a temperature of at least 250° C.
21. The process of claim 19 , wherein said leachate is hydrochlorinated with gaseous HCI.
22. The process of claim 21 , wherein said hydrochlorination is carried out at a temperature of about −10° C. to about 20° C.
23. The process of claim 20 , wherein the aluminium chloride is converted into alumina at a temperature of about 950° C. to 1150° C.
24. A process for preparing alumina comprising:
optionally treating aluminium dross residues so as to reduce the amount of aluminium nitride present therein;
leaching said aluminium dross residues optionally having a reduced amount of aluminium nitride, at a temperature of at least 200° C., with H 2 SO 4 having a concentration of about 98% so as to obtain a mixture comprising a solid and a liquid, and separating said solid from said liquid;
solubilizing in water at least a portion of minerals and metals contained in said solid so as to obtain a leachate;
hydrochlorinating said leachate so as to obtain aluminium chloride; and
converting said aluminium chloride into alumina,
wherein in said process, at least 80% by weight of the Al atoms contained in the aluminium dross residues are converted into alumina.
25. The process of claim 24 , wherein at least 90% by weight of the Al atoms contained in the aluminium dross residues are thereby obtained in the form of alumina.
26. The process of claim 25 , wherein the alumina obtained has a purity of at least 90%.
27. The process of claim 24 , wherein in said process, at least 95% by weight of the Al atoms contained in the aluminium dross residues are converted into alumina.
28. The process of claim 24 , wherein the aluminium chloride is converted into alumina at a temperature of about 950° C. to 1150° C.