Technique for extracting alumina from materiel containing calcium aluminate

Abstract

The invention provides a new technology for extracting aluminium oxide from the material containing carbon aluminate. The carbon aluminate is dissolved out the material by weak sodium carbonate solution to be made into carbon aluminate solution that density is less than 100 g / f, gas CO2 is send into the carbon aluminate solution to do decomposition to generate high-silicon aluminium hydroxide and carbon decomposition mother solution which circulately dissolving out carbon aluminate, the high-silicon aluminium hydroxide is processed by low-temp. dissolving, seed-decomposed decomposing and burning to produce quality sand-type aluminium oxide.

Description

Technical field: [0001] The invention relates to an alumina extraction process, in particular to a process for extracting alumina from materials containing calcium aluminate. Background technique: [0002] The traditional process of extracting alumina from calcium aluminate-containing materials is a one-stage dissolution-desilication-partial carbon process or a two-stage dissolution-desilication-partial carbon process (see the appendix for the process. figure 1 ). The specific process is as follows: the calcium aluminate material is dissolved with sodium carbonate solution, and the dissolved solution is filtered and separated to obtain a low-concentration sodium aluminate solution and dissolved slag. The dissolution slag is added to the secondary stirring dissolution tank, and the adjustment solution is added at the same time for secondary dissolution, and the dissolution slurry is filtered and separated, and the filtrate is the secondary liquid. Then add the secondary liq...

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Problems solved by technology

[0005] (1) When lime is added to medium-pressure desiliconization, the temperature is about 150°C, the silicon content index after desiliconization is between 400 and 550, and the solution after desiliconization does not meet the requirements for producing high-quality alumina;

[0006] (2) The concentration of alumina in the solution is low, the material flow rate is large, the desiliconization time is as long as 2 hours, and the steam consumption is large;

[0007] (3) The solution contains a relatively high concentration of sodium carbonate. When lime is added for deep desiliconization, the loss of alumina is too large, and a certain amount of calcium water and alkali is generated, and the material flow is large.

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