Electrolytic method for controlling the precipitation of alumina

An alumina and precipitation technology, applied in chemical instruments and methods, inorganic chemistry, aluminum compounds, etc., can solve the problems of poor quality, excessive purchase cost of lime, etc., and achieve the effect of improving precipitation efficiency

Inactive Publication Date: 2010-07-07
ALCOA OF AUSTRALIA LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in addition to producing alumina of inferior quality compared to current practice, liquid carbonation necessitates the excessive purchase cost of lime, which requires the regeneration of caustic from sodium carbonate

Method used

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  • Electrolytic method for controlling the precipitation of alumina
  • Electrolytic method for controlling the precipitation of alumina
  • Electrolytic method for controlling the precipitation of alumina

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0227] The following examples demonstrate that effluents can be supersaturated by removal of soda ash using membrane electrolysis and seeded to produce significant amounts of alumina compared to a control sample of effluent that was not subjected to prior electrolysis.

[0228] A sample of ex-precipitation liquid (LXP) with a TC of 241 (expressed as g / L of sodium carbonate) and an A / TC of 0.48 from the applicant's Kwinana refinery was divided into two parts. Some of the fractions were electrolyzed at 90°C using a Nafion 324 membrane, reducing the TC to 167 g / L and increasing the A / TC to 0.68. Both LXP and electrolyte (100 mL each) were transferred to separate polypropylene bottles, and gibbsite seeds (10 g) were added to each solution. The vial was sealed and placed in a rotating water bath at 70°C for 24 hours, after which time the solid was collected by filtration, dried at 105°C, and weighed. Both filtrates were analyzed for alumina and TC content. The results of two expe...

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Abstract

A method for controlling the precipitation of alumina from a Bayer process solution, the method comprising the steps of: applying a potential between a first region comprising a Bayer process liquor and a second region comprising a caustic solution, wherein an ion permeable membrane is provided between the first region and the second region; and causing transfer of an ion across the ion permeable membrane from one region to the other region, wherein the Bayer process liquor is not directed to the second region.

Description

field of invention [0001] The present invention relates to an electrolytic process for the controlled precipitation of alumina from Bayer process solutions. Background technique [0002] The Bayer process is widely used for the production of alumina from alumina-containing ores such as bauxite. The process involves contacting an alumina-containing ore with a recycled caustic aluminate solution at elevated temperature in a process commonly referred to as digestion. Solids were removed from the resulting slurry and the solution was cooled to induce a state of supersaturation. [0003] Alumina is added as seed crystals to the solution to induce precipitation of more aluminum hydroxide from it. Precipitated alumina is separated from the caustic aluminate solution, known as spent liquor, with a portion of the alumina recycled for seeding and the remainder recovered as product. The remaining caustic aluminate solution is recycled for further digestion of the alumina-containing ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/00C01F7/144C01F7/0606
CPCC01F7/0606C01F7/144
Inventor 约翰·贝西达戈登·帕金森J·戴维·亨德尔斯
Owner ALCOA OF AUSTRALIA LTD
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