Nalco Company

Ecolab USA Inc.

David H Slinkman

Dmitri L Kouznetsov

Jianjun Liu

John David Kildea

Ji Cui

Timothy La

James A Counter

Everett C Phillips

Kailas B Sawant

Kevin O'Brien

Frederick J Swiecinski

Kim Richard Coleman

Kevin L O'Brien

The invention provides methods and compositions for the addition of a CGM to precipitation liquor of a Bayer process. The CGM comprises a neopolyol, an ester derived from a neopolyol, and/or an ether derived from a neopolyol. Optionally the CGM may comprise water and/or an antifoaming agent and/or a hydrocarbon carrier liquid. The CGM is quite effective and results in a significant increase in mean particle size of produced alumina crystals.

Neopolyols suitable for crystal growth modification in the Bayer process

The invention provides a method of inhibiting the accumulation of DSP scale in the liquor circuit of Bayer process equipment. The method includes adding one or more particular silane based small molecules to the liquor fluid circuit. These scale inhibitors reduce DSP scale formation and thereby increase fluid throughput, increase the amount of time Bayer process equipment can be operational and reduce the need for expensive and dangerous acid washes of Bayer process equipment. As a result, the invention provides a significant reduction in the total cost of operating a Bayer process.

Reducing aluminosilicate scale in the bayer process

Reducing aluminosilicate scale in the Bayer process

The invention provides a method of controlling silica in the liquor circuit of the Bayer process. The method involves addition of a promoter material to enhance the precipitation of DSP and includes adding one or more silica dispersion materials or dry silica forms to those parts of the circuit where precipitation of DSP and removal of silica from solution is desirable; for example the desilication stage of a Bayer process plant. The removal of DSP from solution reduces silica concentration in the liquor and thereby enables better control of process issues such as silica contamination in alumina product and DSP formation in later stages of the process where precipitation as scale onto vessel walls and equipment is problematical. As a result, the invention provides a significant reduction in the total cost of operating a Bayer process.

Approach in controlling DSP scale in bayer process

An improved method and composition for producing aluminum hydroxide crystals in a Bayer process pregnant liquor, involve the addition of an emulsified crystallization modifier comprising a C-Cfatty acid, precursors, salts or blends thereof. The alkyl chain of the fatty acid crystallization modifier is free of functional groups. The modifier yields a commercially viable product in the presence and absence of a hydrocarbon oil which dissolves the fatty acid. Further, the modifier, prepared in either an emulsified form or as a fatty acid neat, facilitates formation of oxalate aggregates greater than 200 &#x3bc;m which may be readily screened out with minimum trihydrate loss.

Composition and method for improved aluminum hydroxide production

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-Cfatty 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.

The present invention relates ways to increase the output of a high quality product from the aluminum hydroxide recovery processes such as the Bayer process. The invention is a method of increasing the size of precipitated aluminum hydroxide while not reducing the total production amounts. The invention relates to the use of a crystal growth modifier compositions added to the precipitation liquor to increase the particle size distribution of the precipitated alumina trihydrate.

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Lombard, IL, United States of America

David H Slinkman