Selective separation of elements or commodities of interest in aqueous streams

Patent metadata

Field	Value
Publication number	US-2018119252-A1
Application number	US-201615566430-A
Country	US
Kind code	A1
Filing date	Apr 15, 2016
Priority date	Apr 15, 2015
Publication date	May 3, 2018
Grant date	—

Abstract

A process for selectively separating a metallic constituent from other metals and other materials accompanying the metallic constituent in a mixture is described. The process comprises the step of providing the mixture in an aqueous solution such that the metallic constituent forms a complex anion in the solution. One or more of the other metals forms a cation or a complex cation in the solution. Another step includes contacting the solution with one or more additives to form layered double hydroxide (LDH) material in situ such that the complex anion is intercalated within interlayers of the LDH material and wherein one or more of the other metals are incorporated into the LDH material's crystal structure or matrix. Another step involves the addition of an LDH to an aqueous solution. The process involves selectively recovering the metallic constituent from the interlayer of the LDH by subjecting the LDH to a recovery treatment step(s) and as required, methods to modify the LDH to facilitate metal separation and recovery or contaminant stabilisation.

First claim

1 . A process for selectively separating a metallic constituent from other metals and other materials accompanying the metallic constituent in a mixture, the process comprising:
(a) providing the mixture in an aqueous solution such that the metallic constituent forms a complex anion in the solution and wherein one or more of the other metals forms a cation or a complex cation in the solution; (b) contacting the solution with one or more additives to form layered double hydroxide (LDH) material in situ such that the complex anion is intercalated within interlayers of the LDH material and wherein one or more of the other metals are incorporated into the LDH material's crystal structure or matrix; and (c) selectively recovering the metallic constituent from the interlayer of the LDH by subjecting the LDH obtained from step (b) to a recovery treatment step.

2 . A process for selectively separating a metallic constituent from other metals and other materials accompanying the metallic constituent in a mixture, the process comprising:
(a) providing the mixture in an aqueous solution such that the metallic constituent forms a complex anion in the solution and wherein one or more of the other metals forms a cation or a complex cation in the solution; (b) contacting the solution with a layered double hydroxide (LDH) material such that the complex anion is intercalated within interlayers of the LDH material; and (c) selectively recovering the metallic constituent from the interlayer of the LDH by subjecting the LDH from step (b) to a recovery treatment step.

3 . (canceled)

4 . A process in accordance with claim 1 further comprising separating the LDH from the solution and wherein the recovery treatment step comprises an ion exchanging step involving the addition of at least one substituent anion to an ion-exchanging solution such that the substituent anion displaces at least some of the intercalated complex anion by an ion exchange mechanism thereby resulting in the complex anion being released from the interlayer into the ion exchange solution.

5 - 7 . (canceled)

8 . A process in accordance with claim 1 wherein the recovery treatment step comprises subjecting the LDH material to heat treatment or thermal decomposition thereby forming a collapsed or metastable LDH material.

9 - 12 . (canceled)

13 . A process in accordance with claim 1 wherein the recovery treatment step comprises optimisation of the crystal structure or matrix of the LDH material for selectively incorporating one or more of the other metals into the crystal structure or matrix of the LDH in step (b).

14 . A process in accordance with claim 1 wherein the metallic constituent comprises uranium, vanadium, chromium or a transuranic metal capable of forming a complex anion in solution and wherein the one or more of the other metals comprises rare earth metals or a transuranic element.

15 - 22 . (canceled)

23 . A process in accordance with claim 1 wherein the LDH from step (b) is separated from the aqueous solution before subjecting the LDH to the recovery treatment step (c).

24 . A process in accordance with claim 2 wherein the step of contacting the LDH material with the aqueous solution comprises dissolving at least a part of the LDH material into the solution thereby obtaining dissolved LDH in the solution followed by controlling the reaction conditions in the aqueous solution for in situ precipitation of LDH material from the dissolved LDH material such that the complex anion is intercalated within interlayers of the LDH material formed in situ and wherein one or more of the other metals are incorporated into the crystal structure or matrix of the LDH material formed in situ.

25 - 26 . (canceled)

27 . A process in accordance with claim 1 wherein the step of contacting the solution with one or more additives to form layered double hydroxide (LDH) material in situ further comprises:
(a) adding a magnesium and/or aluminium containing silicate material in the aqueous solution and dissolving at least a part of the silicate material in the solution thereby leaching at least a part of the magnesium and/or aluminium from the silicate material into the water; and
(b) controlling reaction conditions for achieving an appropriate Mg:Al ratio in the solution for formation of the layered double hydroxide (LDH) in situ.

28 - 33 . (canceled)

34 . A process in accordance with claim 27 wherein the step of controlling the reaction conditions comprises addition of at least one Mg-containing compound and/or at least one Al-containing compound for achieving the appropriate Mg:Al ratio in the solution for formation of the LDH in situ.

35 - 36 . (canceled)

37 . A process in accordance with claim 27 wherein the step of controlling the reaction conditions further comprises providing substantially alkaline reaction conditions for formation of the LDH in situ.

38 . A process in accordance with claim 27 wherein the step of controlling the reaction conditions further comprises addition of alkaline or acid-neutralising material for formation of the LDH in situ.

39 . (canceled)

40 . A process in accordance with claim 27 further comprising the step of removing at least a part of the LDH formed in situ, wherein the at least one of the said dissolved cation and/or anion species is incorporated in the LDH.

41 . A process in accordance with claim 27 wherein the silicate material one or more of: Attapulgite; Clinoptilolite; Sepiolite; Talc; Vermiculite.

42 . A process in accordance with claim 27 wherein at least a part of the silicate material from step (a) and the LDH formed in situ in step (b) form an insoluble clay material mixture wherein the clay material mixture incorporates said at least one or more dissolved cation species and/or the one or more dissolved anion species.

43 . A process in accordance with claim 27 wherein undissolved clay material particles from step (a) provide nucleation sites for formation of at least a part of the LDH formed in situ in step (b).

44 . A process in accordance with claim 27 wherein the one or more dissolved cation species in the water comprises magnesium and/or aluminium cations such that the magnesium and/or aluminium is incorporated into the lattice of the LDH formed in situ.

45 . A process in accordance with claim 27 wherein at least one of the dissolved anions in the water is a complex anion such the at least one of the complex ions is intercalated in an interlayer of the LDH formed in situ.

46 . A process in accordance with claim 27 wherein step (c) comprises adding a mixture to the solution, the mixture comprising the silicate material and an additional material.

47 . A process in accordance with claim 1 wherein the LDH formed in situ comprises hydrotalcite.

48 - 49 . (canceled)

Assignees

• Douglas Grant Brian
• Commw Scient Ind Res Org

Inventors

• Douglas Grant Brian

Classifications

• C22B60/0252 Primary

  treatment or purification of solutions or of liquors or of slurries (C22B60/0221 takes precedence) · CPC title

• G21Y2002/60

  Physics · mapped topic

• C22B3/12

  in inorganic alkaline solutions · CPC title

• C02F1/42

  by ion-exchange (ion-exchange in general B01J) · CPC title

• C02F2001/422

  using anionic exchangers · CPC title