Method for integrally separating and refining sodium bicarbonate

Abstract

The invention belongs to the technical field of chemical refining, and particularly relates to a method for integrally separating and refining sodium bicarbonate. The method comprises the following steps: inputting a sodium bicarbonate double-decomposition cold separation solution into a filter press for primary filter pressing and primary solid-liquid separation to obtain a first filtrate and a first crude product; the first crude product is sequentially subjected to first-time air blowing and first-time water washing, and first washing liquid and a second crude product are obtained; sequentially carrying out secondary air blowing and secondary water washing on the second crude product to obtain a second washing solution and a third crude product; the third crude product is subjected to squeezing and filter pressing through a filter press, and refined sodium bicarbonate is obtained. According to the method provided by the invention, sodium bicarbonate can be integrally separated and refined, the moisture of the obtained sodium bicarbonate is relatively low and is below 10%, and the quality and the recovery rate of the sodium bicarbonate are ensured.

Description

Technical Field

[0001] This invention belongs to the field of chemical refining technology, specifically relating to an integrated method for separating and refining sodium bicarbonate. Background Technology

[0002] In the technology of producing sodium carbonate and co-producing ammonium sulfate from sodium sulfate waste salt and ammonium bicarbonate through metathesis, the solid-liquid separation and refining washing of sodium bicarbonate and ammonium sulfate solutions are key process steps affecting the quality and recovery rate of sodium bicarbonate. Furthermore, the yield and quality of sodium bicarbonate directly determine the yield and quality of sodium carbonate.

[0003] Currently, sodium bicarbonate is generally separated using a "thick slurry tank-vacuum disc filter-thrust centrifuge" method, but the sodium bicarbonate obtained by this separation method has a high moisture content, generally higher than 12%. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated method for separating and refining sodium bicarbonate, which yields sodium bicarbonate with low moisture content.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides an integrated method for separating and purifying sodium bicarbonate, comprising the following steps:

[0007] (1) The sodium bicarbonate double decomposition cold precipitation solution is fed into a filter press for the first filter press and the first solid-liquid separation to obtain the first filtrate and the first crude product;

[0008] (2) The first crude product is subjected to a first air blowing and a first water washing in sequence to obtain a first washing liquid and a second crude product;

[0009] (3) The second crude product is subjected to a second air blowing and a second water washing to obtain a second washing solution and a third crude product;

[0010] (4) The third crude product is pressed and filtered by a filter press to obtain refined sodium bicarbonate.

[0011] Preferably, the pressure of the first filter press is 0.7-1 MPa, and the time is 1-15 min.

[0012] Preferably, the moisture content of the crude product after the first blowing is less than 12%.

[0013] Preferably, the pressure of the first blowing is 0.6-0.8 MPa, and the time is 1-5 minutes.

[0014] Preferably, the washing pressure of the first water wash is 0.8-1.2 MPa, and the time is 1-4 min.

[0015] Preferably, the pressure of the second blowing is 0.6-0.8 MPa, and the time is 1-5 min.

[0016] Preferably, the washing pressure of the second water wash is 0.8-1.2 MPa, and the time is 1-4 min.

[0017] Preferably, the pressing and filtration pressure is 1-1.4 MPa and the time is 3-6 min.

[0018] Preferably, the solid content of the sodium bicarbonate metathesis reflux solution is 15-35%.

[0019] Preferably, after pressing and filtration, the moisture content of the refined sodium bicarbonate is ≤10%.

[0020] This invention provides an integrated method for separating and refining sodium bicarbonate, comprising the following steps: (1) feeding a sodium bicarbonate metathesis cold precipitation solution into a filter press for a first filtration and a first solid-liquid separation to obtain a first filtrate and a first crude product; (2) subjecting the first crude product to a first air blowing and a first water washing to obtain a first washing liquid and a second crude product; (3) subjecting the second crude product to a second air blowing and a second water washing to obtain a second washing liquid and a third crude product; (4) pressing and filtering the third crude product through a filter press to obtain refined sodium bicarbonate. The method provided by this invention can integrate the separation and refining of sodium bicarbonate, resulting in sodium bicarbonate with low moisture content (below 10%), ensuring the quality and recovery rate of sodium bicarbonate. Detailed Implementation

[0021] This invention provides an integrated method for separating and purifying sodium bicarbonate, comprising the following steps:

[0022] (1) The sodium bicarbonate double decomposition cold precipitation solution is fed into a filter press for the first filter press and the first solid-liquid separation to obtain the first filtrate and the first crude product;

[0023] (2) The first crude product is subjected to a first air blowing and a first water washing in sequence to obtain a first washing liquid and a second crude product;

[0024] (3) The second crude product is subjected to a second air blowing and a second water washing to obtain a second washing solution and a third crude product;

[0025] (4) The third crude product is pressed and filtered by a filter press to obtain refined sodium bicarbonate.

[0026] In this invention, a sodium bicarbonate metathesis cold precipitation solution is fed into a filter press for the first filtration and the first solid-liquid separation to obtain the first filtrate and the first crude product.

[0027] In one embodiment of the present invention, the solid content of the sodium bicarbonate metathesis cold precipitation solution can be 15-35%.

[0028] In one embodiment of the present invention, the pressure of the first filter press can be 0.7-1 MPa, specifically 0.7 MPa, 0.8 MPa, 0.9 MPa, or 1.0 MPa; the time is 1-15 min, specifically 1 min, 5 min, 10 min, or 15 min. In this invention, filtration separation is achieved through the aforementioned pressure difference; in one embodiment of the present invention, the solid-liquid separation is preferably performed in situ within the filter press.

[0029] After obtaining the first crude product, the present invention sequentially performs a first air blowing and a first water washing on the first crude product to obtain a first washing liquid and a second crude product.

[0030] In one embodiment of the present invention, the moisture content of the crude product after the first blowing can be less than 12%. In another embodiment of the present invention, the pressure of the first blowing is 0.6-0.8 MPa, specifically 0.6 MPa, 0.7 MPa or 0.8 MPa; the time is 1-5 min, specifically 1 min, 2 min, 3 min, 4 min or 5 min.

[0031] In one embodiment of the present invention, the washing pressure of the first water wash can be 0.8-1.2 MPa, specifically 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa or 1.2 MPa; the time can be 1-4 min, specifically 1 min, 2 min, 3 min or 4 min.

[0032] After obtaining the second crude product, the present invention sequentially performs a second blowing and a second washing on the second crude product to obtain a second washing solution and a third crude product.

[0033] In one embodiment of the present invention, the pressure of the second blowing can be 0.6-0.8 MPa, specifically 0.6 MPa, 0.7 MPa or 0.8 MPa; the time can be 1-5 min, specifically 1 min, 2 min, 3 min, 4 min or 5 min.

[0034] In one embodiment of the present invention, the washing pressure of the second water wash can be 0.8-1.2 MPa, specifically 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa or 1.2 MPa; the time can be 1-4 min, specifically 1 min, 2 min, 3 min or 4 min.

[0035] After obtaining the third crude product, the present invention presses and filters the third crude product through a filter press to obtain refined sodium bicarbonate.

[0036] In one embodiment of the present invention, the pressing and filtration pressure can be 1-1.4 MPa, specifically 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa or 1.4 MPa; the time can be 3-6 min, specifically 3 min, 4 min, 5 min or 6 min.

[0037] In one embodiment of the present invention, the moisture content of the refined sodium bicarbonate after pressing and filtration can be ≤10%.

[0038] As one embodiment of the present invention, the integrated separation and purification of sodium bicarbonate can be carried out in a fully automatic plate and frame filter press provided by Shandong Jingjin Equipment.

[0039] To further illustrate the present invention, the following detailed description of the embodiments is provided in conjunction with the present invention, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0040] Example 1

[0041] This embodiment provides an integrated method for separating and refining sodium bicarbonate, using a fully automatic plate and frame filter press provided by Shandong Jingjin Equipment. The specific steps are as follows:

[0042] (1) The sodium bicarbonate double decomposition cold precipitation solution is fed into a filter press and filtered for 3 minutes under a feed pressure of 0.8 MPa. Then, solid-liquid separation is carried out by pressure difference to obtain the first filtrate and the first crude product.

[0043] (2) The first crude product was blown with air at 1 MPa for 1 min and washed at 0.7 MPa for 1 min. The water content of the crude product was 14%, and the first washing solution and the second crude product were obtained.

[0044] (3) The obtained second crude product was blown with air at 1 MPa pressure for 1 min and washed at 0.7 MPa pressure for 1 min. The water content of the crude product was 12%, and the second washing solution and the third crude product were obtained.

[0045] (4) The obtained third crude product is pressed and filtered for 5 minutes under a pressure of 1.2 MPa to obtain refined sodium bicarbonate. The water content of the refined sodium bicarbonate is 10%.

[0046] Comparative Example 1

[0047] This comparative example uses a negative pressure vacuum disc filter. The sodium bicarbonate metathesis precipitate solution enters the filter through a thickened slurry tank, is washed once, and then automatically separated to obtain sodium bicarbonate with a moisture content of 16%. However, it is impossible to guarantee product quality throughout the entire process.

[0048] Comparative Example 2

[0049] This comparative example uses a positive-pressure vacuum disc filter (intelligent pressurization). The sodium bicarbonate metathesis reflux solution enters the filter through a thickened slurry tank, is washed once, and then automatically separated to obtain sodium bicarbonate with a moisture content of 18.3%. However, it is impossible to guarantee product quality throughout the entire process.

[0050] Comparative Example 3

[0051] This comparative example uses a thrust centrifuge. The sodium bicarbonate metathesis reflux solution enters the centrifuge through a thickened slurry tank, is washed once, and then automatically separated to obtain sodium bicarbonate with a moisture content of 12.6%. The biggest drawback of the thrust centrifuge is material leakage, making it impossible to collect all the separated sodium bicarbonate at once. Furthermore, it cannot guarantee product quality throughout the entire process.

[0052] As can be seen from the above embodiments, the method provided by the present invention controls the moisture content of sodium bicarbonate to below 10% and ensures product quality in one working process, which is far superior to the comparative example, and provides good prerequisites for improving the quality and recovery rate of sodium bicarbonate.

[0053] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for the integrated separation and purification of sodium bicarbonate, characterized in that, Includes the following steps: (1) The sodium bicarbonate double decomposition cold precipitation solution is fed into a filter press for the first filter press and the first solid-liquid separation to obtain the first filtrate and the first crude product; (2) The first crude product is subjected to a first air blowing and a first water washing in sequence to obtain a first washing liquid and a second crude product; (3) The second crude product is subjected to a second air blowing and a second water washing in sequence to obtain a second washing solution and a third crude product; (4) The third crude product is pressed and filtered by a filter press to obtain refined sodium bicarbonate.

2. The method as described in claim 1, characterized in that, The pressure for the first filter press is 0.7-1 MPa, and the time is 1-15 min.

3. The method as described in claim 1, characterized in that, The moisture content of the crude product after the first air blowing is less than 12%.

4. The method as described in claim 1, characterized in that, The pressure of the first blow is 0.6-0.8 MPa, and the time is 1-5 minutes.

5. The method as described in claim 1, characterized in that, The washing pressure for the first water wash is 0.8-1.2 MPa; the washing time is 1-4 min.

6. The method as described in claim 1, characterized in that, The pressure of the second blowing is 0.6-0.8 MPa, and the time is 1-5 minutes.

7. The method as described in claim 1, characterized in that, The second water wash has a washing pressure of 0.8-1.2 MPa and a time of 1-4 minutes.

8. The method as described in claim 1, characterized in that, The pressing and filtration pressure is 1-1.4 MPa, and the time is 3-6 min.

9. The method as described in claim 1, characterized in that, The solid content of the sodium bicarbonate metathesis reflux solution is 15-35%.

10. The method as described in claim 1, characterized in that, After pressing and filtration, the refined sodium bicarbonate has a moisture content of ≤10%.