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Method for producing alumina by using sodium bicarbonate to decompose sodium aluminate solution

A technology of sodium bicarbonate and aluminum hydroxide, applied in chemical instruments and methods, aluminum compounds, inorganic chemistry, etc., can solve the problems of poor alumina quality, increased investment, air pollution and other environmental problems

Inactive Publication Date: 2009-12-23
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But with gas CO 2 The carbon content of carbon has many disadvantages. First, the quality of the alumina produced is poor (mostly the third-grade product); secondly, it is necessary to increase the preparation of CO in the production process. 2 process, that is, the lime production process, which increases investment and complicates the production process; the third is the gas CO 2 Carbon is a gas-liquid reaction, the reaction is violent, and there is a lot of CO 2 Discharge into air pollution environment

Method used

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  • Method for producing alumina by using sodium bicarbonate to decompose sodium aluminate solution
  • Method for producing alumina by using sodium bicarbonate to decompose sodium aluminate solution
  • Method for producing alumina by using sodium bicarbonate to decompose sodium aluminate solution

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Example 1 One-time sufficient addition of sodium bicarbonate to decompose bauxite eluate

[0019] Under stirring conditions, the temperature is controlled at 80°C, the total alkalinity (as Na 2 O) is 172g / L, Al content (as A1 2 o 3 Calculated) is 185g / L, caustic alkali content (as Na 2 (O meter) add 100g / L sodium bicarbonate solution in the bauxite eluate of 156g / L, the addition of sodium bicarbonate is controlled at the ratio of the equivalent number with the caustic alkali of eluate to be 1.05, decomposes 2 hours, decomposes The rate reached 99.65%. The obtained aluminum hydroxide product was roasted and kept at 1200° C. for 4 hours to obtain an alumina product. The analysis results are shown in Table 1.

[0020] Table 1

[0021]

Embodiment 2

[0022] Example 2 Add a sufficient amount of sodium bicarbonate and sodium carbonate mixed solution to decompose the bauxite eluate

[0023] Under stirring conditions, the temperature is controlled at 60 ° C, the total alkalinity (as Na 2 O) is 173g / L, Al content (as A1 2 o 3 Calculated) is 186g / L, caustic alkali content (as Na 2 (O meter) is the mixed solution that sodium bicarbonate content is 80g / L, sodium carbonate content is 40g / L in the bauxite stripping solution that adds sodium bicarbonate content of 156g / L, and the addition of mixed solution is controlled at the total equivalent number of its sodium bicarbonate The ratio to the total equivalent number of caustic in the eluate is 0.95, and the decomposition rate reaches 99.7% after 5 hours of decomposition. The obtained aluminum hydroxide product was roasted and kept at 1200° C. for 4 hours to obtain an alumina product. The analysis results are shown in Table 2.

[0024] Table 2

[0025]

Embodiment 3

[0026] Example 3 The first step is to control the amount of sodium bicarbonate to decompose the bauxite eluate

[0027] Under stirring conditions, the temperature is controlled at 80°C, the total alkalinity (as Na 2 O) is 173g / l, Al content (as A1 2 o 3 Calculated) is 186g / L, caustic alkali content (as Na 2 (O meter) is the mixed solution that sodium bicarbonate content is 90g / L, sodium carbonate content is 30g / L in the bauxite stripping solution that adds sodium bicarbonate content of 156g / L, and the addition of mixed solution is controlled at the total equivalent number of its sodium bicarbonate The ratio to the total equivalent number of caustic in the eluate is 0.8, and the decomposition rate reaches 90.2% after 5 hours of decomposition. The obtained aluminum hydroxide product is roasted and kept at 1200°C for 4 hours to obtain an alumina product; a sufficient amount of sodium bicarbonate is added to the remaining mother liquor within 2 hours to obtain a mixture of alum...

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Abstract

The invention discloses a method for producing alumina by using sodium bicarbonate to decompose sodium aluminate solution. The method uses sodium bicarbonate or mixed solution of sodium bicarbonate and sodium carbonate as neutralizing agent to decompose and separate out aluminum hydroxide from alumina dissolving solution, namely sodium aluminate solution. The decomposition is carried out by two steps: a first step, controlling the ratio of the total equivalents of the added sodium bicarbonate to caustic alkali of the alumina dissolving solution to be not more than 0.9 so as to ensure that the obtained aluminum hydroxide and a roasted alumina product have high quality; and a second step, controlling the ratio of the total equivalents of the added sodium bicarbonate to the residual caustic alkali to be not less than 1.0 so as to ensure that the residual sodium aluminate is totally separated out in a form of mixed sediment of aluminum hydroxide and dawsonite and the product can be used as a raw material for producing an alumina chemical product. The decomposing mother liquor, namely the sodium carbonate solution of the method can be converted into sodium hydroxide and sodium bicarbonate through a film electrolysis mode after purifying so as to realize the cycle of the materials. The method develops various advantages of seed separation and carbon separation of CO2 gas, overcomes various defects of the seed separation and the carbon separation, and has the advantages of high decomposition rate, short consumed time, energy conservation, environmental protection, and remarkable economic and social benefits.

Description

technical field [0001] The invention relates to the field of alumina production, in particular to a method for producing aluminum hydroxide and alumina by using sodium bicarbonate to decompose bauxite eluate-sodium aluminate solution. technical background [0002] At present, the methods of alumina production at home and abroad mainly include Bayer method, sintering method and combined method. The combined process is simply a combination of the Bayer process and the sinter process. The Bayer process has low energy consumption and is currently the alumina production process commonly used in countries all over the world. The Bayer process accounts for about 80% of alumina production in my country. The energy consumption of the sintering method is 3 to 4 times that of the Bayer method. It is only used in the production of low-grade bauxite with high silicon content, and is rarely used in countries all over the world. The quality of bauxite in our country is poor, and the sint...

Claims

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Application Information

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IPC IPC(8): C01F7/20
Inventor 钮因健万平玉吕子剑张吉龙吴钢张学英陈咏梅潘军青孟杰邓洁
Owner BEIJING UNIV OF CHEM TECH