Composition and method for improved aluminum hydroxide production

Abstract

An improved method and composition for producing aluminum hydroxide crystals from precipitation liquor, involves the addition of an emulsified crystal growth modifier comprising a C 8 -C 10 fatty acid, precursors, salts or blends thereof. The emulsified crystal growth modifier also facilitates an upward shift in particle size distribution of aluminum hydroxide and an upward shift in oxalate ball size.

1 . An emulsified crystal growth modifier comprising: a C 8  to C 10  fatty acid, precursor, salt or blends thereof; an oil carrier, wherein said oil carrier content of said modifier is at least about 15% by weight; and water. 
     
     
         2 . A Bayer process for producing aluminum hydroxide crystals having a reduced formation of product fines concurrent with an upward shift in particle size distribution of aluminum hydroxide and an upward shift in oxalate ball size, the process comprising the addition of the crystal growth modifier of  claim 1  to the precipitation liquor. 
     
     
         3 . The process of  claim 2  wherein the oxalate balls precipitate to a size in the range of from about 200 to about 10,000 μm. 
     
     
         4 . The process of  claim 2  wherein the oxalate balls precipitate to a size in the range of about 300 μm. 
     
     
         5 . The process of  claim 2  further comprising separating said oxalate balls and said aluminum hydroxide crystals. 
     
     
         6 . The process of  claim 2  wherein said separation occurs with a separation method containing one or more screens. 
     
     
         7 . The process of  claim 6  wherein said separation occurs with a separation method containing one or more cyclones.