Method for continuously producing polyaluminum chloride form aluminum slag

Patent metadata

Field	Value
Publication number	US-2023312360-A1
Application number	US-202217848530-A
Country	US
Kind code	A1
Filing date	Jun 24, 2022
Priority date	Mar 30, 2022
Publication date	Oct 5, 2023
Grant date	—

Abstract

Disclosed is a method for continuously producing polyaluminum chloride from aluminum slag, comprising: blending the aluminum slag with water into a slurry in a mixing tank; pumping the slurry and a sodium hydroxide solution into a first mixing reactor; introducing the mixture obtained in the first mixing reactor into a second mixing reactor and pumping hydrochloric acid into the second mixing reactor; and filtering the resulting mixture and allowing filtrate for ripening, polymerization and sedimentation to obtain liquid polyaluminum chloride; wherein each of the reactors is pipeline-shaped, arranged horizontally and provided with a spiral conveyor shaft inside which is arranged horizontally and configured to stir and convey the mixture in a pipeline. This method realizes a continuous treatment of aluminum slag together with a continuous recovery of ammonia nitrogen and produces PAC, thereby achieving resourceful utilization and improved operability.

First claim

What is claimed is:

1 . A method for continuously producing polyaluminum chloride from aluminum slag, comprising the following steps:
1) mixing and stirring the aluminum slag and water into a slurry in a mixing tank; 2) pumping the slurry into an inlet of a first mixing reactor, and pumping sodium hydroxide solution; 3) introducing the mixture obtained in the first mixing reactor into a second mixing reactor, and pumping hydrochloric acid into the second mixing reactor; and 4) filtering the mixture obtained in the second mixing reactor, and allowing filtrate for ripening, polymerization and sedimentation to obtain liquid polyaluminum chloride; wherein the first mixing reactor and the second mixing reactor each are pipeline-shaped, arranged horizontally, and provided with a spiral conveyor shaft inside; wherein the spiral conveyor shaft is arranged horizontally, and configured to stir and convey the mixture from one end to the other end of a pipeline.

2 . The method for continuously recovering ammonia from hazardous waste of aluminum slag according to claim 1 , wherein the first mixing reactor is provided with an inlet connected to the mixing tank and a sodium hydroxide solution injection port at one end thereof, and with an outlet and an exhaust port at the other end thereof;
the second mixing reactor is provided with an inlet connected to the outlet of the first mixing reactor and a hydrochloric acid injection port at one end thereof, and with an outlet and an exhaust port at the other end thereof; and a mechanical sealing mechanism is provided between the spiral conveyor shaft and the inner wall of the mixing reactor.

3 . The method for continuously recovering ammonia from hazardous waste of aluminum slag according to claim 2 , wherein
the mixing tank comprises a tank body, a stirring shaft is provided inside the tank body, an aluminum slag feed port and a water injection port are provided on the top of the tank body, a feed bin is provided above the aluminum slag feed port for holding the aluminum slag, a discharge port is provided at the bottom of the feed bin, a primary valve is provided at the discharge port, a secondary valve is provided above the primary valve, and a buffer bin is formed between the primary valve and the secondary valve, wherein only one of the primary valve and the secondary valve is opened during a time period, and both of the primary valve and the secondary valve are opened at a set interval.

4 . The method for continuously recovering ammonia from hazardous waste of aluminum slag according to claim 1 , wherein gas overflowing from the exhaust port of the first mixing reactor is introduced into hydrochloric acid.

5 . The method for continuously recovering ammonia from hazardous waste of aluminum slag according to claim 1 , wherein sodium hydroxide in the sodium hydroxide solution and the aluminum slag are introduced into the mixing reactor at a mass ratio of 1:10-1:20.

6 . The method for continuously recovering ammonia from hazardous waste of aluminum slag according to claim 1 , wherein the hydrochloric acid has a concentration of 10-20%.

Assignees

• Univ Tongji

Inventors

• Li Fengting
• Wang Ying
• Gu Yifan
• Kong Tao
• Li Zekun

Classifications

• C01F7/57 Primary

  Basic aluminium chlorides, e.g. polyaluminium chlorides · CPC title

• C01F7/56 Primary

  Chlorides (containing fluorine C01F7/52) · CPC title

• B01D53/58

  Ammonia · CPC title

• B01D53/78

  with gas-liquid contact · CPC title

• B01J19/1862

  placed in series · CPC title