METHODS FOR PREPARING HEMATITE
There are provided methods for preparing hematite. For example, the method can comprise reacting a basic aqueous composition comprising the iron and the aluminum with hematite under conditions suitable for at least partially converting the iron into hematite under the form of a precipitate, thereby obtaining a liquid phase and a solid phase; and separating the liquid phase from the solid phase.
1 . A method for preparing hematite, said method comprising obtaining said hematite from a basic aqueous composition comprising at least one precipitated iron ion, having a pH of about 10.5 to about 13 and being at temperature of about 50° C. to about 150° C., by reacting said composition with a predetermined quantity of hematite in the absence of a growth regulating agent, thereby promoting, catalyzing and/or enhancing formation of said hematite, wherein said basic aqueous composition is obtained by:
leaching an iron-containing material comprising said at least one iron ion with an acid so as to obtain a leachate and a solid residue;
separating said leachate from said solid residue; and
reacting said leachate with a base
or by:
leaching said iron-containing material comprising said at least one iron ion with an acid so as to obtain a leachate and a solid residue;
optionally removing at least a portion of said at least one iron ion from said leachate;
separating said leachate from said solid residue; and
reacting said leachate with a base.
2 . The method of claim 1 , wherein said at least one precipitated iron ion is chosen from Fe 3+ , Fe 2+ , and a mixture thereof.
3 . The method of claim 1 , wherein said at least one precipitated iron ion is under the form of Fe(OH) 3 .
4 . The method of claim 1 , wherein said at least one precipitated iron ion is under the form of Fe(OH) 2 , Fe(OH) 3 , or a mixture thereof.
5 . The method of claim 1 , wherein said predetermined quantity of hematite is added to said composition, over a predetermined period of time, under agitation.
6 . The method of claim 1 , wherein said basic aqueous composition has a temperature of about 50° C. to about 70° C.
7 . The method of claim 1 , wherein said basic aqueous composition has a temperature of about 80° C. to about 100° C.
8 . The method of claim 1 , wherein said basic aqueous composition has a temperature of about 70° C. to about 120° C.
9 . The method of claim 1 , wherein said basic aqueous composition has a pH of about 10.8 to about 11.8.
10 . The method of claim 1 , wherein said basic aqueous composition has a pH of about 11.0 to about 11.6.
11 . The method of claim 1 , wherein said basic aqueous composition has a pH of about 11.2 to about 11.5.
12 . The method of claim 1 , wherein said basic aqueous composition has a pH of about 10.5 to about 12.
13 . The method of claim 1 , wherein said basic aqueous composition has a pH of about 11.5 to about 12.5.
14 . The method of claim 1 , wherein said basic aqueous composition has a pH of about 11.8 to about 12.2.
15 . The method of claim 1 , wherein said basic aqueous composition is maintained at said pH when being reacted with said hematite.
16 . The method of claim 1 , wherein said basic aqueous composition is maintained at said temperature when being reacted with said hematite.
17 . The method of claim 1 , wherein said predetermined quantity of hematite is added at a molar ratio hematite/said at least one iron ion of about 0.01 to about 0.1.
18 . The method of claim 1 , wherein said iron-containing material is chosen from argillite, red mud, fly ashes and mixtures thereof.
19 . The method of claim 1 , wherein said base has a concentration of about 3 to about 4 M.
20 . The method of claim 1 , wherein said base has a concentration of about 30 to about 60 weight %.
21 . The method of claim 1 , wherein said leachate and a first portion of said base are added simultaneously into a reactor comprising a second portion of said base.
22 . The method of claim 1 , wherein said basic aqueous composition is obtained by:
leaching said iron-containing material comprising said at least one iron ion with an acid so as to obtain a leachate and a solid residue;
separating said leachate from said solid residue; and
reacting said leachate with said base.
23 . The method of claim 1 , wherein said basic aqueous composition is obtained by:
leaching said iron-containing material comprising said at least one iron ion with said acid so as to obtain a leachate and a solid residue;
optionally removing at least a portion of said at least one iron ion from said leachate;
separating said leachate from said solid residue; and
reacting said leachate with a base.