Separation method of alkaline liquid in production of alumina

A technology of alkaline material liquid and separation method, applied in the direction of alumina/aluminum hydroxide, etc., can solve the problems of insufficient yield, low alkali purity, long time, etc., achieve fast separation speed, improve purity, and increase yield Effect

Inactive Publication Date: 2014-09-03
HEFEI UNIV OF TECH
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Problems solved by technology

[0006] In order to avoid the shortcomings of the above-mentioned prior art, the present invention provides a method for separating sodium hydroxide and sodium metaaluminate in the alkaline feed liquid during alumina production through electrodialysis, aiming to solve the existing problems. In alumina production, there are problems such as high energy consumption, long time, insufficient yield, and low purity of alkali in the mother liquor during the precipitation process of alumina

Method used

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  • Separation method of alkaline liquid in production of alumina
  • Separation method of alkaline liquid in production of alumina
  • Separation method of alkaline liquid in production of alumina

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Embodiment 1

[0023] This embodiment adopts such as figure 1 The electrodialysis device shown is composed of an anode chamber and a cathode chamber respectively located on both sides and an electrodialysis compartment sandwiched between the anode chamber and the cathode chamber; the electrodialysis compartment is composed of a cation exchange membrane C and an anion exchange membrane Two "alkali recovery chamber and material liquid chamber units" arranged in intervals are arranged repeatedly (the membrane stack is C-A-C-A-C); the anode and the adjacent cation exchange membrane form the anode chamber, and the cathode and the adjacent cations The exchange membrane interval constitutes the cathode chamber; the effective area of ​​a single cation exchange membrane or a single anion exchange membrane is 5.7cm 2 , the distance between the anode or cathode and the cation exchange membrane C, and between the cation exchange membrane C and the anion exchange membrane A is 1 cm. The cation exchange ...

Embodiment 2

[0031] The electrodialysis unit used in this embodiment, cation exchange membrane, anion exchange membrane, strong electrolyte solution and the dilute lye of alkali recovery chamber are identical with embodiment 1, and alkaline feed liquid is NaOH and NaAl(OH) 4 The mixed solution, the concentration of NaOH is 1.55mol / L, NaAl(OH) 4 The concentration is 0.81mol / L. The control current density is 87.5, 175.0, 262.5, 350.0, 437.5mA / cm 2 , the electrodialysis experiment was carried out, and the running time was 4 hours. The results are shown in Table 2.

[0032] Table 2 Effect of current density on alkali recovery rate, aluminum leakage rate, caustic ratio of solution in alkali recovery chamber (α k ), energy consumption and current efficiency

[0033]

[0034] From the results in Table 2, it can be seen that with the increase of current density, the alkali recovery rate, aluminum leakage rate and energy consumption all gradually increase, and the solution α in the alkali rec...

Embodiment 3

[0036] The strong electrolyte solution used in this example and the dilute lye in the alkali recovery chamber are the same as in Example 1, the alkaline feed solution is the same as in Example 2, the cation exchange membrane is the same as in Example 1, and the anion exchange membrane is based on Chinese patent ZL201210206572.6 (a method for preparing an organic-inorganic hybrid anion exchange membrane based on BPPO and PVA) produced AM-QP-30 membrane. After soaking in 2.0mol / L NaOH at 65°C for 60 hours, the swelling degree of the membrane was 91%, and the mass loss rate was 8%, which indicated that the membrane had strong alkali resistance.

[0037] The electrodialysis devices used in this example are as follows: figure 2 The three shown are respectively a unit containing one alkali recovery chamber and a feed liquid chamber (named model1), a unit containing two alkali recovery chambers and a feed liquid chamber (named model2), and a unit containing three alkali recovery cha...

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Abstract

The invention discloses a separation method of alkaline liquid in production of alumina. The separation method is characterized in that sodium hydroxide and sodium metaaluminate in alkaline liquid can be separated by an electroosmosis device. According to the separation method disclosed by the invention, the alumina production process is optimized, i.e., the sodium hydroxide and sodium metaaluminate in the alkaline liquid are subjected to membrane separation before crystal seeds are introduced, therefore, the energy consumption and time in the subsequent crystal seed precipitation process can be reduced and shortened, and the productivity of aluminum hydroxide is increased; in addition, the purity of alkali in mother liquor can be improved and recycling of alkali is facilitated.

Description

technical field [0001] The invention relates to a method for separating sodium hydroxide and sodium metaaluminate in alkaline feed liquid during alumina production. Background technique [0002] The production methods of alumina mainly include Bayer method, soda lime sintering method and Bayer-sintering combined method. Among them, the Bayer process has always been the main method of producing alumina, and its output accounts for about 95% of the world's total alumina production. The principle is to first crush and wet-grind bauxite, and then heat and dissolve aluminum with caustic soda (NaOH) solution After separating the residue (red mud) from the alumina in the soil ore, an alkaline feed liquid containing sodium hydroxide and sodium metaaluminate is obtained. The treatment process of the alkaline material liquid is generally as follows: lower the temperature, add aluminum hydroxide as a seed crystal, and stir for a long time to decompose sodium metaaluminate to precipita...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02
Inventor 吴翠明颜海洋吴永会
Owner HEFEI UNIV OF TECH
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