EXTRACTION OF ELEMENTS AND/OR COMPOUNDS FROM IRON-CONTAINING MATERIALS SUCH AS IRON-CONTAINING TAILINGS, RECOVERY OF MAGNETICALLY SUSCEPTIBLE MATERIALS, AND RELATED SYSTEMS AND PRODUCTS
Extraction of elements and/or compounds from iron-containing materials, such as iron-containing tailings, and related systems and products are generally described. The systems and methods described herein can provide, in accordance with certain embodiments, the ability to efficiently process iron-containing (e.g., iron-rich) tailings even in the presence of aluminosilicates and/or other impurities. In addition, in accordance with some embodiments, the systems and methods described herein can provide the ability to efficiently extract different minerals and/or other compounds (e.g., metal(s), salt(s), etc.) from complex tailings structures. Furthermore, reactors and methods for recovery of a reaction product with a relatively high magnetic susceptibility are generally described. Certain reactors are configured such that, during operation, the reaction products are selectively transported to the magnetic field source, relative to the reactants.
1 . A method for extracting iron from an iron-containing material, comprising:
leaching the iron-containing material to produce solids comprising an iron-containing compound and a leachate comprising dissolved aluminosilicate and/or other impurities; and
reducing the iron-containing compound to metallic iron.
2 . The method of claim 1 , wherein the iron-containing compound comprises an oxide, hydroxide, and/or oxyhydroxide of iron.
3 . The method of any one of claims 1-2 , wherein the iron-containing compound comprises hematite, magnetite, and/or goethite.
4 . The method of any one of claims 1-3 , further comprising, prior to the reducing, subjecting the iron-containing compound to magnetic separation.
5 . The method of any one of claims 1-4 , wherein the reducing comprises a first step of reducing the iron-containing compound to magnetite prior to a second step of reducing the magnetite to metallic iron.
6 . The method of claim 5 , further comprising magnetically separating the magnetite from the solids prior to the second step.
7 . The method of any one of claims 1-6 , wherein a mass fraction of the iron-containing compound relative to the sum of the iron-containing compound and the aluminosilicate and/or other impurities in the solids is greater than the mass fraction of the iron-containing compound relative to the sum of the iron-containing compound and the aluminosilicate and/or other impurities in the iron-containing material.
8 . The method of any one of claims 1-7 , wherein a mass fraction of the aluminosilicate and/or other impurities relative to the sum of the iron-containing compound and the aluminosilicate and/or other impurities in the leachate is greater than the mass fraction of the aluminosilicate and/or other impurities relative to the sum of the iron-containing compound and the aluminosilicate and/or other impurities in the iron-containing material.
9 . A method for extracting iron from an iron-containing material, comprising:
leaching the iron-containing material to produce solids comprising hematite and/or goethite and a leachate comprising dissolved aluminosilicate and/or other impurities;
reducing the solids such that a magnetite-rich stream is produced; and
subjecting the magnetite-rich stream to magnetic separation such that a stream that is further enriched in magnetite compared to the magnetite-rich stream is produced.
10 . The method of claim 9 , further comprising reducing the stream that is further enriched in magnetite to metallic iron.
11 . The method of any one of claims 1-10 , wherein the iron-containing material comprises mining tailings, bauxite residues, sodalite, phyllosilicate, and/or iron slimes.
12 . The method of any one of claims 1-11 , wherein the impurities comprise an oxide, a sulfide, a sulfate, an oxalate, a carbonate, a phosphate, and/or a salt.
13 . The method of any one of claims 1-12 , wherein the impurities comprise a compound containing an alkali metal, an alkaline earth metal, a rare earth metal, a transition metal, a post-transition metal, and/or a metalloid.
14 . The method of claim 13 , wherein the post-transition metal comprises aluminum and/or gallium.
15 . The method of any one of claims 13-14 , wherein the metalloid comprises silicon and/or germanium.
16 . The method of any one of claims 1-15 , further comprising roasting the iron-containing material prior to the leaching.
17 . The method of any one of claims 1-16 , wherein, when a mass ratio of the total amount of alkali metal and/or alkaline earth metal relative to the total amount of metals that are not alkali or alkaline earth metal is greater than 1:6 in the iron-containing material, the leaching comprises acid leaching.
18 . The method of claim 17 , wherein the leaching comprises selectively leaching one or more compounds comprising an alkali metal, an alkaline earth metal, and/or a rare earth metal from the iron-containing material.
19 . The method of any one of claims 17-18 , wherein the acid leaching is carried out at a pH of less than 1.
20 . The method of any one of claims 17-19 , wherein the acid leaching is carried out at a temperature of greater than 50° C. and less than 100° C.
21 . The method of any one of claims 1-16 , wherein, when a mass ratio of the total amount of alkali metal and/or alkaline earth metal relative to the total amount of metals that are not alkali or alkaline earth metal is less than 1:10 in the iron-containing material, the leaching comprises caustic leaching.
22 . The method of claim 21 , wherein the leaching comprises selectively leaching one or more compounds comprising an alkali metal, aluminum, silicon, and/or a rare earth metal from the iron-containing material.
23 . The method of any one of claims 21-22 , wherein the caustic leaching is carried out at a pH of greater than 12.
24 . The method of any one of claims 21-23 , wherein the caustic leaching is carried out at a temperature of greater than 50° C. and up to 300° C.
25 . The method of any one of claims 1-24 , wherein the reducing comprises exposing the solids to a reducing gas comprising hydrogen, syngas, and/or methane.
26 . The method of any one of claims 1-25 , further comprising at least partially separating the leachate and the solids prior to the reducing.
27 . The method of any one of claims 1-26 , wherein the reducing is carried out at a temperature of greater than or equal to 300° C. and less than or equal to 650° C.
28 . The method of any one of claims 1-27 , wherein the metallic iron has a purity of at least 90%.
29 . The method of any one of claims 1-28 , further comprising producing iron oxide pigments from residual iron-containing material produced by the magnetic separation.
30 . The method of any one of claims 1-29 , further comprising extracting at least one rare earth metal from the leachate via precipitation and selective leaching.
31 . The method of claim 30 , further comprising at least partially separating the extracted rare earth metals into light rare earth metals and heavy rare earth metals via solvent extraction.
32 . The method of any one of claims 1-31 , further comprising recovering compounds comprising alkali and/or alkaline earth metal salts, alumina, silica, and/or titania from the leachate via selective leaching.
33 . The method of any one of claims 1-32 , further comprising recovering compounds comprising actinides from the leachate via scrubbing.
34 . A system, comprising:
a leaching unit comprising a first reactor, wherein the first reactor comprises a first vessel configured such that, during operation, an iron-containing material within the first vessel is leached to produce solids comprising an iron-containing compound and a leachate comprising dissolved aluminosilicate and/or other impurities;
a solid-liquid separator fluidically connected to an outlet of the first reactor, wherein the solid-liquid separator is configured to separate the solids from the leachate; and
an iron reduction unit comprising a second reactor, wherein the second reactor is fluidically connected to an outlet of the solid-liquid separator and comprising a second vessel, wherein the second vessel is configured to reduce the iron-containing compound in the solids to a magnetically susceptible iron-containing material.
35 . The system of claim 34 , further comprising a magnetic separator fluidically connected to an outlet of the second reactor, wherein the magnetic separator is configured to magnetically separate the magnetically susceptible iron-containing material from the solids.
36 . The system of claim 35 , further comprising an additional iron reduction unit comprising a third reactor, wherein the third reactor is fluidically connected to an outlet of the magnetic separator and comprising a third vessel, wherein the third vessel is configured such that, during operation, the magnetically susceptible iron-containing material is reduced to metallic iron.
37 . The system of any one of claims 34-36 , further comprising a gaseous source comprising one or more reducing gases and fluidically connected to an inlet of the second reactor and/or the third reactor.
38 . The system of any one of claims 34-37 , further comprising a heat exchanger and/or a gas scrubber fluidically connected to an outlet of the second reactor and/or the third reactor.
39 . The system of any one of claims 34-38 , further comprising a source of iron-containing material and a source of leaching agent fluidically connected to one or more inlets of the first reactor.
40 . A system, comprising:
a leaching unit comprising a first reactor, wherein the first reactor comprising a first vessel configured such that, during operation, an iron-containing material within the first vessel is leached to produce solids comprising an iron-containing compound and a leachate comprising dissolved aluminosilicate and/or other impurities; and
a magnetic separation unit comprising a second reactor, wherein the second reactor comprises a second vessel configured such that, during operation, the iron-containing compound in the solids is selectively reduced to a magnetically susceptible iron-containing material and subjected to magnetic separation.
41 . The system of claim 40 , the second reactor comprising:
a magnetic field source at least partially within the vessel; and
a mixer at least partially within the vessel;
wherein the second reactor is configured such that, during operation, the magnetically susceptible iron-containing material is selectively transported to the magnetic field source, relative to the iron-containing compound.
42 . A reactor comprising:
a vessel;
a magnetic field source at least partially within the vessel; and
a mixer at least partially within the vessel;
wherein the reactor is configured such that, during operation, the reaction products are selectively transported to the magnetic field source, relative to the reactants.
43 . The reactor of claim 42 , further comprising baffles within the vessel associated with one or more walls of the vessel.
44 . The reactor of any one of claims 42-43 , further comprising a liquid in the vessel.
45 . The reactor of claim 44 , wherein the liquid contains hematite as a reactant and magnetite as a reaction product.
46 . The reactor of any one of claims 42-45 , wherein the liquid comprises an aqueous solution.
47 . The reactor of any one of claims 42-46 , wherein the mixer comprises an impeller.
48 . The reactor of any one of claims 42-47 , wherein the magnetic field source is positioned proximate an outlet of the vessel.
49 . The reactor of any one of claims 42-48 , wherein the magnetic field source comprises a magnetic filter, such as a magnetic cage.
50 . A method comprising:
carrying out, in a vessel, a chemical reaction in which a product of the chemical reaction has a greater magnetic susceptibility than a reactant of the chemical reaction; and
simultaneously effecting, in the vessel, a separation between the product and the reactant with a magnetic field source.
51 . The method of claim 50 , wherein the chemical reaction is carried out in a liquid.
52 . The method of claim 51 , wherein the liquid comprises an aqueous solution.
53 . The method of any one of claims 50-52 , wherein the reactant is hematite and the product is magnetite.
54 . The method of any one of claims 50-53 , further comprising flowing a liquid comprising the reactant into the vessel through an inlet of the vessel.
55 . The method of any one of claims 50-54 , further comprising retrieving the product from the magnetic field source by flowing a liquid comprising the product through the magnetic field source and out of the vessel through an outlet of the vessel.
56 . The method of any one of claims 50-55 , wherein the chemical reaction is carried out at a temperature of greater than or equal to 60 degrees Celsius and less than or equal to 500 degrees Celsius.
57 . The method of claim 56 , wherein the chemical reaction is carried out at a temperature of greater than or equal to 200 degrees Celsius and less than or equal to 400 degrees Celsius.
58 . The method of any one of claims 51-57 , wherein carrying out the chemical reaction comprises stirring the liquid.
59 . The method of claim 58 , wherein stirring the liquid comprises rotating an impeller in the vessel.