# US 4,394,368 A · High temperature hydrolysis of aluminum sulfate solutions

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- Number: US 4,394,368 A
- Document ID: US4394368A
- Status: Granted
- Kind: A
- Application number: 06/327,539
- Filed: 1981-12-04
- Granted: 1983-07-19
- Earliest claimed: 1981-12-04
- Assignees: The United States of America as represented by the Secretary of the Interior
- Inventors: Donald E. Shanks
- Web page: https://patentgrep.com/patent/US4394368A

## CPC

- C01F 7/74: Sulfates
- C01F 7/32: Thermal decomposition of sulfates including complex sulfates, e.g. alums
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})

## Abstract

Aqueous aluminum sulfate solution is hydrolyzed at temperatures above about 300.degree. C. to produce a basic aluminum sulfate product that is readily purified and converted to Al.sub.2 O.sub.3.

## Claims

### Claim 1

A process for hydrolysis of dilute aqueous aluminum sulfate solution containing about 100-300 grams per liter of aluminum sulfate and minor amounts of impurities consisting essentially of maintaining said solution in a closed system at a hydrolysis temperature above 300.degree. C. for a time sufficient to convert a high percentage of the aluminum sulfate to the insoluble basic aluminum sulfate, Al(OH)SO.sub.4, and subsequently quenching the closed system in water.

### Claim 2 (depends on 1)

The process of claim 1 in which the hydrolysis temperature is about 320.degree. C.

### Claim 3 (depends on 1)

The process of claim 1 in which the pressure employed is about 1230 to 1620 psig.