Method and apparatus for sodium slag recovery

Patent metadata

Field	Value
Publication number	US-12392013-B2
Application number	US-202218070250-A
Country	US
Kind code	B2
Filing date	Nov 28, 2022
Priority date	Apr 14, 2022
Publication date	Aug 19, 2025
Grant date	Aug 19, 2025

Abstract

The present disclosure relates to the field of the preparation of high purity sodium and the safe treatment of sodium calcium slag, and discloses a method and apparatus for sodium slag recovery by using gravity separation—controllable combustion—alkaline liquor leaching process for the preparation of high purity sodium and safe treatment of sodium calcium slag. The method comprises the following steps: (1) subjecting a liquid sodium slag to a gravity stratification to obtain pure metallic sodium and high calcium content sodium slag; (2) roasting the high calcium content sodium slag to obtain a roasting slag; and (3) leaching the roasting slag by using an alkaline liquor to obtain the sodium hydroxide solution and calcium hydroxide. The method and apparatus provided by the present disclosure have advantages including high efficiency separation of sodium and calcium, saving separation time, safe and controllable production process, and continuous production process, thereby providing a safe and efficient method for the preparation of high purity sodium and safe treatment of new sodium calcium slag generated by the method, allowing continuous production of high purity sodium and safe recycle of new sodium calcium slag.

First claim

The invention claimed is:

1. A method for sodium slag recovery, the method comprising:
(1) subjecting a liquid sodium slag to a gravity stratification to obtain pure metallic sodium and high calcium content sodium slag;
(2) roasting said high calcium content sodium slag to obtain a roasting slag; and
(3) leaching said roasting slag by using an alkaline liquor to obtain a sodium hydroxide solution and calcium hydroxide,
wherein the gravity stratification in step (1) is a supergravity centrifugation,
wherein a separation factor of the supergravity centrifugation in step (1) is within a range of 500-5,500, and
wherein the time for said supergravity centrifugation is within a range of 1-500 minutes.

2. The method of claim 1 , wherein the sodium slag comprises sodium and calcium and wherein sodium is contained in an amount of 60-90 wt % and calcium is contained in an amount of 10-40 wt %, based on the total amount of said sodium slag.

3. The method of claim 1 , wherein a separation factor of the supergravity centrifugation in step (1) is within a range of 1,500-4,500 and wherein the time for said supergravity centrifugation is within a range of 2-20 minutes.

4. The method of claim 1 , wherein the roasting in step (2) further comprises the following steps:
(2-1) subjecting the high calcium content sodium slag to a first roasting to obtain a first roasted product slag; and
(2-2) pulverizing the first roasted product slag, and then subjecting the first roasted product slag to a second roasting to obtain the roasting slag.

5. The method of claim 4 , wherein the first roasting in step (2-1) is carried out for 5-180 minutes, wherein the temperature of said first roasting in step (2-1) is within a range of 200-720° C., wherein the second roasting in step (2-2) is carried out for 10-240 minutes, and wherein the temperature of said second roasting in step (2-2) is within a range of 230-800° C.

6. The method of claim 5 , wherein the first roasting in step (2-1) is carried out for 10-90 minutes, wherein the temperature of said first roasting in step (2-1) is within a range of 220-450° C., wherein the second roasting in step (2-2) is carried out for 10-60 minutes, and wherein the temperature of said second roasting in step (2-2) is within a range of 260-600° C.

7. The method of claim 4 , wherein the first roasting in step (2-1) and the second roasting in step (2-2) are each independently a controllable oxygen roasting, wherein the controllable oxygen roasting causes conversion of the high calcium content sodium slag into sodium peroxide, sodium oxide, calcium oxide and residual sodium calcium slag under the condition of satisfying the safe operation, wherein the volumetric oxygen concentration of said first roasting in step (2-1) is within a range of 5-30%, wherein the oxygen flow rate of said first roasting in step (2-1) is within a range of 0.5-10 m 3 /t-minute, in terms of per ton of high calcium content sodium slag, wherein the volumetric oxygen concentration during said second roasting in step (2-2) is within a range of 10-60%, and wherein the oxygen flow rate in the second roasting process of step (2-2) is within a range of 1-20 m 3 /t-minute, in terms of per ton of first roasted product slag.

8. The method of claim 7 , wherein the volumetric oxygen concentration of said first roasting in step (2-1) is within a range of 10-25%, wherein the oxygen flow rate of said first roasting in step (2-1) is within a range of 1-6 m 3 /t-minutes, in terms of per ton of high calcium content sodium slag, wherein the volumetric oxygen concentration during said second roasting in step (2-2) is within a range of 15-40%, and wherein the oxygen flow rate in the second roasting process of step (2-2) is within a range of 1-10 m 3 /t minute, in terms of per ton of first roasted product slag.

9. The method of claim 4 , wherein the pulverizing in step (2-2) is performed to obtain a pulverized slag with a granularity of 10-160 mesh.

10. The method of claim 9 , wherein the pulverizing in step (2-2) is performed to obtain a pulverized slag with a granularity of 20-80 mesh.

11. The method of claim 4 , wherein the pulverizing is performed under a protective atmosphere provided by at least one of a first roasting tail gas, nitrogen gas, helium gas, argon gas and neon gas.

12. The method of claim 11 , wherein the protective atmosphere is provided by the first roasting tail gas.

13. The method of claim 1 , wherein a solute of the alkaline liquor in step (3) is a hydrate, wherein the concentration of said alkaline liquor is within a range of 20-100 wt %, based on the hydroxide hydrate, wherein a reaction temperature of the leaching is within a range of −18° C. to 45° C., wherein a reaction time of the leaching is within a range of 10-300 minutes, wherein the method further comprises subjecting the leached material to a solid-liquid separation to obtain a liquid and a solid, and wherein the method further comprises recycling at least part of said liquid to the leaching process for providing at least part of the alkaline liquor.

14. The method of claim 13 , wherein a solute of the alkaline liquor in step (3) is a sodium hydroxide hydrate and/or a calcium hydroxide hydrate, wherein the concentration of said alkaline liquor is within a range of 30-100 wt %, based on the hydroxide hydrate, wherein a reaction temperature of the leaching is within a range of −15° C. to 30° C., and wherein a reaction time of the leaching is within a range of 15-60 minutes.

15. The method of claim 14 , wherein a solute of the alkaline liquor in step (3) is a sodium hydroxide hydrate and wherein a reaction temperature of the leaching is within a range of −15° C. to 10° C.

16. An apparatus for the method of sodium slag recovery according to claim 1 , the apparatus method comprising:
providing a stratification unit ( 1 ), a first roasting unit ( 2 ), a pulverizer ( 3 ), a second roasting unit ( 4 ) and a reaction kettle ( 5 ) connected in series,
wherein subjecting a liquid sodium slag to a gravity stratification to obtain pure metallic sodium and high calcium content sodium slag using the stratification unit ( 1 ) is used for stratification of the sodium slag to obtain pure metallic sodium and high calcium content sodium slag,
roasting said high calcium content sodium slag in the first roasting unit to obtain a roasting slag; and
leaching said roasting slag by using an alkaline liquor to obtain a sodium hydroxide solution and calcium hydroxide,
wherein the stratification unit is provided with a high calcium content sodium slag outlet, and the high calcium content sodium slag outlet is in communication with an inlet of the first roasting unit,
wherein the reaction kettle is used for leaching the roasting slag obtained from the second roasting unit with the alkali liquor,
wherein the gravity stratification step is a supergravity centrifugation,
wherein a separation factor of the supergravity centrifugation is within a range of 500-5,500, and
wherein the time for said supergravity centrifugation is within a range of 1-500 minutes.

17. The apparatus method of claim 16 , wherein the stratification unit comprises a supergravity centrifuge and wherein an inlet of the supergravity centrifuge is in communication with a liquid sodium slag supply unit.

18. The apparatus method of claim 16 , wherein the first roasting unit further comprises a first roasting furnace for performing the first roasting, wherein the first roasting furnace is equipped with a first flowmeter and a first oxygen concentration meter for controlling an oxygen

Assignees

• Univ Beijing Chem Tech
• Inner Mongolia Ruixin Chemical Co Ltd

Inventors

• Pan Junqing
• Wang Qiuchen
• Wang Keyu
• Chen Yan
• Sun Yanzhi

Classifications

• C22B1/02 Primary

  Roasting processes (C22B1/16 takes precedence) · CPC title

• C22B7/008 Primary

  by an alkaline or ammoniacal leaching · CPC title

• C22B7/04

  Working-up slag · CPC title

• C22B26/10 Primary

  Obtaining alkali metals · CPC title

• Y02P10/20

  Recycling · CPC title