Method for preparing boehmite by liquid phase carbonating decomposition of sodium aluminate solution and sodium bicarbonate

Abstract

The invention discloses a method for preparing boehmite by liquid phase carbonating decomposition of a sodium aluminate solution and sodium bicarbonate, which belongs to the field of industrial aluminum oxide. The method comprises the steps of: carrying out decomposition reaction between a NaHCO3 solution and a sodium aluminate solution, adding boehmite seed crystal to induce the sodium aluminate solution to crystallize and separate out boehmite; performing diaphragm electrolysis on a carbonate mother liquor obtained after decomposition of the sodium aluminate solution to dissociate carbon from alkali; preparing sodium bicarbonate in an anode region; and returning to the decomposition process, thereby recycling a carbon source. The method is suitable to a Bayer-process and a sintering-process decomposition of the sodium aluminate solution, the decomposition rate is high and the energy consumption of aluminum oxide roasting can be lowered.

Description

technical field

[0001] The invention relates to the technical field of alumina production, in particular to a new method for preparing boehmite by utilizing sodium aluminate solution and sodium bicarbonate liquid-phase carbon content. technical background

[0002] As the basic raw material for the production of aluminum metal, alumina production occupies an extremely important position in the aluminum industry. At present, the methods of alumina production at home and abroad mainly include Bayer method, sintering method and combined method. The combined method is a combination of the Bayer method and the sintering method. The Bayer method has low energy consumption, but it has higher requirements on the quality of bauxite. The sintering method can process low-grade bauxite, but the disadvantage is that the energy consumption is relatively high.

[0003] The seed separation process adopted by the Bayer method to decompose the sodium aluminate solution, due to the influence ...

Examples

Embodiment 1

[0027] Prepare 200ml of sodium aluminate solution with industrial aluminum hydroxide and sodium hydroxide, the chemical composition is Al 2 o 360 g / L, causticization coefficient is 1.3, decomposition solution temperature is 85°C, stirring speed is 100r·min -1 Under these conditions, add boehmite seed crystals with a seed coefficient of 0.1, and use a peristaltic pump to add a concentration of 60 g / L NaHCO 3 Solution, adding rate 0.2g·L -1 min -1 , the decomposition time is 2h, and the precipitated boehmite is separated from the carbon mother liquor to obtain the product boehmite. The obtained carbon fraction mother liquor is electrolyzed by a diaphragm, the temperature of the electrolytic solution is 40°C, the electrolysis time is 4h, and the current density is 0.01A / cm 2 , getting NaHCO in the anode region 3 solution, adjusted to an appropriate concentration for use.

[0028] The decomposition products of sodium aluminate solution and the results of electrolysis of carb...

Embodiment 2

[0032] Prepare 200ml of sodium aluminate solution with industrial aluminum hydroxide and sodium hydroxide, the chemical composition is Al 2 o 3 120 g / L, causticization coefficient 1.7, decomposition solution temperature 95°C, stirring speed 200r·min -1 Under these conditions, add boehmite seed crystals with a seed coefficient of 1.0, and use a peristaltic pump to add NaHCO with a concentration of 80 g / L 3 Solution, adding rate 0.8g·L -1 min -1 , the decomposition time is 4h, and the precipitated boehmite is separated from the carbon mother liquor to obtain the product boehmite. The obtained carbon fraction mother liquor is electrolyzed by a diaphragm, the temperature of the electrolytic solution is 50°C, the electrolysis time is 8h, and the current density is 0.1A / cm 2 , getting NaHCO in the anode region 3 solution, adjusted to an appropriate concentration for use.

[0033] The results are shown in Table 2

[0034] Table 2 Sodium aluminate solution decomposition product...

Embodiment 3

[0037] Prepare 200ml of sodium aluminate solution with industrial aluminum hydroxide and sodium hydroxide, the chemical composition is Al 2 o 3 140 g / L, causticization coefficient 1.5, decomposition solution temperature 85°C, stirring speed 300r·min -1 Under these conditions, add boehmite seed crystals with a seed coefficient of 2.0, and use a peristaltic pump to add NaHCO with a concentration of 100 g / L 3 Solution, adding rate 0.4g·L -1 min -1 , the decomposition time is 7h, and the precipitated boehmite is separated from the carbon mother liquor to obtain the product boehmite. The obtained carbon fraction mother liquor is electrolyzed by a diaphragm, the temperature of the electrolytic solution is 60°C, the electrolysis time is 16 hours, and the current density is 0.02A / cm 2 , getting NaHCO in the anode region 3 solution, adjusted to an appropriate concentration for use.

[0038] The results are shown in Table 3

[0039] Table 3 Sodium aluminate solution decomposition...

technical field

[0001] The invention relates to the technical field of alumina production, in particular to a new method for preparing boehmite by utilizing sodium aluminate solution and sodium bicarbonate liquid-phase carbon content. technical background

[0002] As the basic raw material for the production of aluminum metal, alumina production occupies an extremely important position in the aluminum industry. At present, the methods of alumina production at home and abroad mainly include Bayer method, sintering method and combined method. The combined method is a combination of the Bayer method and the sintering method. The Bayer method has low energy consumption, but it has higher requirements on the quality of bauxite. The sintering method can process low-grade bauxite, but the disadvantage is that the energy consumption is relatively high.

[0003] The seed separation process adopted by the Bayer method to decompose the sodium aluminate solution, due to the influence ...

Examples

Embodiment 1

[0027] Prepare 200ml of sodium aluminate solution with industrial aluminum hydroxide and sodium hydroxide, the chemical composition is Al 2 o 360 g / L, causticization coefficient is 1.3, decomposition solution temperature is 85°C, stirring speed is 100r·min -1 Under these conditions, add boehmite seed crystals with a seed coefficient of 0.1, and use a peristaltic pump to add a concentration of 60 g / L NaHCO 3 Solution, adding rate 0.2g·L -1 min -1 , the decomposition time is 2h, and the precipitated boehmite is separated from the carbon mother liquor to obtain the product boehmite. The obtained carbon fraction mother liquor is electrolyzed by a diaphragm, the temperature of the electrolytic solution is 40°C, the electrolysis time is 4h, and the current density is 0.01A / cm 2 , getting NaHCO in the anode region 3 solution, adjusted to an appropriate concentration for use.

[0028] The decomposition products of sodium aluminate solution and the results of electrolysis of carb...

Embodiment 2

[0032] Prepare 200ml of sodium aluminate solution with industrial aluminum hydroxide and sodium hydroxide, the chemical composition is Al 2 o 3 120 g / L, causticization coefficient 1.7, decomposition solution temperature 95°C, stirring speed 200r·min -1 Under these conditions, add boehmite seed crystals with a seed coefficient of 1.0, and use a peristaltic pump to add NaHCO with a concentration of 80 g / L 3 Solution, adding rate 0.8g·L -1 min -1 , the decomposition time is 4h, and the precipitated boehmite is separated from the carbon mother liquor to obtain the product boehmite. The obtained carbon fraction mother liquor is electrolyzed by a diaphragm, the temperature of the electrolytic solution is 50°C, the electrolysis time is 8h, and the current density is 0.1A / cm 2 , getting NaHCO in the anode region 3 solution, adjusted to an appropriate concentration for use.

[0033] The results are shown in Table 2

[0034] Table 2 Sodium aluminate solution decomposition product...

Embodiment 3

[0037] Prepare 200ml of sodium aluminate solution with industrial aluminum hydroxide and sodium hydroxide, the chemical composition is Al 2 o 3 140 g / L, causticization coefficient 1.5, decomposition solution temperature 85°C, stirring speed 300r·min -1 Under these conditions, add boehmite seed crystals with a seed coefficient of 2.0, and use a peristaltic pump to add NaHCO with a concentration of 100 g / L 3 Solution, adding rate 0.4g·L -1 min -1 , the decomposition time is 7h, and the precipitated boehmite is separated from the carbon mother liquor to obtain the product boehmite. The obtained carbon fraction mother liquor is electrolyzed by a diaphragm, the temperature of the electrolytic solution is 60°C, the electrolysis time is 16 hours, and the current density is 0.02A / cm 2 , getting NaHCO in the anode region 3 solution, adjusted to an appropriate concentration for use.

[0038] The results are shown in Table 3

[0039] Table 3 Sodium aluminate solution decomposition...

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