Purification of alkaline electrolytes

Patent metadata

Field	Value
Publication number	US-2025161842-A1
Application number	US-202418793146-A
Country	US
Kind code	A1
Filing date	Aug 2, 2024
Priority date	Aug 7, 2023
Publication date	May 22, 2025
Grant date	—

Abstract

A method of purifying an alkaline electrolyte includes contacting the alkaline electrolyte with an aluminum compound to provide a purified alkaline electrolyte. The alkaline electrolyte includes a metal hydroxide, a compound comprising aluminum, silicon, or a combination thereof, and a solvent. The method can be particularly advantageous when used with a method of processing an iron-containing feedstock.

First claim

1 . A method of purifying an alkaline electrolyte, the method comprising:
providing the alkaline electrolyte, wherein the alkaline electrolyte comprises
a metal hydroxide,
a compound comprising aluminum, silicon, or a combination thereof, and
a solvent; and
contacting the alkaline electrolyte with an aluminum compound to provide a purified alkaline electrolyte.

2 . The method of claim 1 , wherein the alkaline electrolyte has a pH of 9 to 17.5.

3 . The method of claim 1 ,
wherein the alkaline electrolyte has a total hydroxide concentration of greater than 1 molar, or wherein the alkaline electrolyte has a total hydroxide concentration of less than 10 molar, or wherein the alkaline electrolyte has a total hydroxide concentration of 5 molar to 20 molar, each based on a total volume of the alkaline electrolyte.

4 . The method of claim 1 , wherein the alkaline electrolyte comprises an alkali metal hydroxide.

5 . The method of claim 1 , wherein the alkaline electrolyte comprises sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, or a combination thereof.

6 . The method of claim 1 , wherein the compound comprising aluminum, silicon, or a combination thereof comprises Al 2 O 3 ·2SiO 2 ·2H 2 O, SiO 2 , Al(OH) 3 , (Mg x Fe 1−x ) 3 Si 4 O 10 (OH) 2 wherein 0≤x≤1, KAlSi 3 O 8 , (K m Na n Ca o )0.6(Mg p Fe 2+ q Fe 3+ 1−q )6Si 8 Al(O s OH 1−s ) 24 ·2H 2 O wherein 0≤m≤1, 0≤n≤1, 0≤o≤1 and m+n+o=1, 0≤p≤1, 0≤q≤1, and p+q=1, and 0≤s≤1, NaAlSi 3 O 8 , or a combination thereof.

7 . The method of claim 1 , wherein the alkaline electrolyte further comprises an anionic impurity comprising SO 4 2− , CO 3 2− , C 2 O 4 2− , 2Al(OH) 4 − , 2Cl − , 2OH − , F − , or a combination thereof.

8 . The method of claim 1 , wherein the solvent is an aqueous solvent.

9 . The method of claim 1 , wherein the aluminum compound comprises aluminum oxide, aluminum hydroxide, sodium aluminate, kaolin, calcium aluminate, or a combination thereof.

10 . The method of claim 1 , wherein the aluminum compound comprises sodium aluminate.

11 . The method of claim 1 , wherein the aluminum compound is added to the alkaline electrolyte in an amount effective to provide a weight ratio of aluminum compound:dissolved silicon of 0.75:1 to 1.75:1.

12 . The method of claim 1 , wherein the aluminum compound, when contacted with the compound comprising aluminum, silicon, or a combination thereof, forms an aluminum compound, a silicon compound, an aluminosilicate compound, or a combination thereof.

13 . The method of claim 1 , wherein the aluminum compound, a silicon compound, an aluminosilicate compound, or a combination thereof precipitates out of the alkaline electrolyte.

14 . The method of claim 1 , wherein the compound comprising aluminum, silicon, or a combination thereof comprises a silicon oxide.

15 . The method of claim 1 , wherein the contacting is at a temperature of 50 to 200° C., at a pressure of greater than or equal to 1 atmosphere, or a combination thereof.

16 . The method of claim 1 , further comprising one or more of contacting the alkaline electrolyte with an alkaline earth metal compound; or
contacting the alkaline electrolyte with activated carbon; or contacting the alkaline electrolyte with an ion exchange resin; or crystallization; or contacting the alkaline electrolyte with sodium carbonate.

17 . The method of claim 1 , wherein the purified alkaline electrolyte has a residual silicon concentration of less than 0.02 molar, based on a total volume of the alkaline electrolyte.

18 . The method of claim 1 , wherein the purified alkaline electrolyte has a residual aluminum concentration of less than 0.11 molar, based on a total volume of the alkaline electrolyte.

19 . The method of claim 1 , wherein the purified alkaline electrolyte has a residual silicon concentration that is 10% or less of an initial concentration of the compound comprising silicon.

20 . The method of claim 1 , wherein the alkaline electrolyte has a dissolved Al 2 O 3 concentration of less than 100 grams per liter.

21 . A method of processing an iron-containing feedstock to produce an iron particle, the method comprising:
continuously flowing an alkaline electrolyte stream comprising the iron-containing feedstock through a channel of an electrochemical cell, the electrochemical cell comprising an anode, and a cathode disposed in the channel; electrochemically reducing at least a portion of the iron-containing feedstock to produce a plurality of iron particles at a surface of the cathode; separating at least a portion of the plurality of iron particles from the alkaline electrolyte; purifying the alkaline electrolyte according to the method of claim 1 to provide a purified alkaline electrolyte; and recycling the purified alkaline electrolyte to the alkaline electrolyte stream to process the iron-containing feedstock.

22 . An alkaline electrolyte purifier, comprising
a mixing unit having
a first inlet configured to receive an alkaline electrolyte feedstock, the alkaline electrolyte feedstock comprising
a metal hydroxide,
a compound comprising aluminum, silicon, or a combination thereof, and
a solvent,

a second inlet configured to receive a precipitant comprising an aluminum compound, and
an outlet configured to provide a slurry; and
a first separator configured to separate the slurry and provide a solid component and a first alkaline electrolyte stream.

23 . The alkaline electrolyte purifier of claim 22 , further comprising
an ion exchange unit configured to receive the first alkaline electrolyte stream from the first separator to provide a second alkaline electrolyte stream.

24 . The alkaline electrolyte purifier of claim 22 , further comprising
an adsorption unit configured to receive the first alkaline electrolyte stream from the first separator, wherein the adsorption unit comprises activated carbon; and a second separator configured to separate the first alkaline electrolyte stream and the activated carbon and provide a third alkaline electrolyte stream.

Assignees

• Form Energy Inc

Inventors

• Luyima Alex
• Manser Joseph Stephen

Classifications

• C25C7/06

  Operating or servicing · CPC title

• C25C1/06

  or iron group metals, refractory metals or manganese · CPC title

• B01D21/01

  using flocculating agents (for purifying water C02F1/52; for liquid radioactive waste G21F9/10) · CPC title

• C25C7/08

  Separating of deposited metals from the cathode · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title