Process for preparing low-salt heavy soda ash

A heavy soda ash and preparation technology, applied in the direction of carbonate preparations, etc., can solve the problems of inability to realize large-scale industrial production, non-continuous operation, complicated process, etc., and achieve the effect of simple structure, simple equipment and short process flow

Inactive Publication Date: 2010-05-19
DALIAN RES & DESIGN INST OF CHEM IND
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Problems solved by technology

[0007] Chinese patent application CN1111214A (Yu Zhongfu. The preparation method of heavy soda ash and the fixed decomposition reaction furnace used therefor. 1995-11-08.) Propose, produce heavy soda ash by sodium bicarbonate wet decomposition under the situation that catalyst exists, this The method uses a fixed device, which cannot be operated continuously and cannot realize...

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  • Process for preparing low-salt heavy soda ash
  • Process for preparing low-salt heavy soda ash

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preparation example Construction

[0030] The preparation method involved in the present invention is based on the inventor's theory and experimental results in this field. attached figure 1 The relationship between the decomposition temperature of precipitated anhydrous sodium carbonate and the minimum decomposition rate of sodium bicarbonate is given. It can be seen that Na 2 CO 3 -NaHCO 3 -H 2 The minimum decomposition rate of sodium bicarbonate required for the precipitation of anhydrous sodium carbonate in the O ternary system is first flat and then decreased with the increase of decomposition temperature. When the decomposition temperature is above 126 ° C, the required minimum decomposition rate is less than 83%. And this decomposition rate is very capable to achieve under the process conditions of pressurized wet decomposition. Applied Na 2 CO 3 -NaHCO 3 -H 2 O ternary system multi-temperature phase diagram, using the characteristics of the system to precipitate anhydrous sodium carbonate cryst...

Embodiment 1

[0038] Na after purification 2 CO 3 53.93g / L, NaHCO 3 The refined natural alkali brine of 81.54g / L and NaCl 4.01g / L (total alkalinity is 105g / L) is continuously added to the sub-tower of wet decomposition and decomposed under normal pressure; Decompose under the pressure of MPa (gauge pressure); the total decomposition time is 0.5h, and the decomposition rate reaches 92.63%. The decomposition liquid is concentrated and crystallized by three-effect evaporation, using 1.0MPa saturated steam as the heat source, and the pressures of I, II, and III effect evaporators are controlled separately At 0.7, 0.5, 0.3MPa, the crystal slurry taken out from the III effect is separated at 130°C to obtain anhydrous sodium carbonate filter cake, which is composed of Na 2 CO 3 97.79%, NaHCO 3 0.21%, NaCl 0.15%, H 2 O 1.85%, after drying, the composition is Na 2 CO 3 99.63%, NaHCO 3 0.21%, NaCl 0.15%, bulk density 0.97g / cm 3 , tightness 1.08g / cm 3 .

Embodiment 2

[0040] Contains NH 4 HCO 3 4.06%, Na 2 CO 3 6.69%, NaHCO 3 67.73%, NaCl 0.64%, H 2 O 20.88% combined alkali intermediate product - wet heavy alkali 17kg, add water 10kg to make slurry to become heavy alkali blending liquid, its composition is NH 4 HCO 3 2.55%, Na 2 CO 3 4.21%, NaHCO 3 42.64%, NaCl0.40%, H 2 O 50.18%, density 1.3g / cm 3 , the total alkalinity is 375g / L. Decompose in the sub-tower of wet decomposition at normal pressure, the main tower of wet decomposition is pressurized at 0.3MPa to decompose, the total decomposition time is 1.0h, and the decomposition rate reaches 88.67%; the decomposition liquid is concentrated and crystallized through three-effect evaporation, and 1.0MPa saturated steam is used as the heat source. The pressures of the II and III effect evaporators were controlled at 0.8, 0.6, and 0.4 MPa respectively, and the crystal slurry taken out from the III effect was separated at 140°C to obtain anhydrous sodium carbonate filter cake, ...

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Abstract

The invention relates to a method for preparing low-salt heavy soda ash by applying a multi-temperature phase diagram of a Na2CO3-NaHCO3-H2O ternary system, utilizing the feature that the system can precipitate anhydrous sodium carbonate crystals at the appropriate temperature and the composition and adopting the anhydrous sodium carbonate flow process. The method comprises the following steps: carrying out pressure wet decomposition on mixed solution of the heavy soda ash which is rich in sodium bicarbonate or refined natural alkali halide, leading the content of the sodium bicarbonate and the content of sodium carbonate in the solution to achieve the corresponding proportion, further leading the solution to enter into a multi-effect evaporator for evaporation and concentration, controlling the crystallization temperature to be above the phase transition point from anhydrous sodium carbonate to sodium carbonate monohydrate, and ensuring that the precipitated solid phase is the anhydrous sodium carbonate; and taking out a magma by self-pressure, carrying out thermal insulation and separation, obtaining a filter cake which mainly contains the anhydrous sodium carbonate, and drying the filter cake for preparing the low-salt heavy soda ash. The process can change the traditional two-step dry calcination to one-step wet calcination, simplify and shorten the process flow, reduce the area occupied by devices, improve the operation environment, simultaneously improve the quality of a product and reduce the energy consumption.

Description

technical field [0001] The invention relates to a method for preparing soda ash. Specifically, it relates to a method for preparing low-salt heavy soda ash with sodium bicarbonate. Background technique [0002] Heavy soda ash has the characteristics of high bulk density, uniform particle size, not easy to fly, good fluidity, etc., and is very popular with downstream users of soda ash, especially heavy soda ash with low salt content and uniform particle size. The production method of heavy soda ash, except that all the United States adopts trona through monohydrate process, most other countries use light soda ash produced by ammonia soda or combined soda as raw material for reprocessing. There are three processing methods: solid phase hydration, liquid phase hydration and extrusion. Among them, solid phase hydration is the most common method. Among the three processes, the extrusion method is the lowest in production cost, and the other two methods are basically the same; ...

Claims

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Application Information

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IPC IPC(8): C01D7/12
Inventor 郜长水窦进良高权李楠徐晓辉张泽福杨凤君门闯
Owner DALIAN RES & DESIGN INST OF CHEM IND
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