CN113860334A

CN113860334A - Method for separating sodium sulfate and sodium chloride from industrial waste salt

Info

Publication number: CN113860334A
Application number: CN202111289179.3A
Authority: CN
Inventors: 王哲; 司新娜; 张德仕; 苏雪莹; 邢伊一
Original assignee: Shandong Jincheng Huirui Environmental Protection Technology Co ltd
Current assignee: Shandong Jincheng Huirui Environmental Protection Technology Co ltd
Priority date: 2021-11-02
Filing date: 2021-11-02
Publication date: 2021-12-31
Anticipated expiration: 2041-11-02
Also published as: CN113860334B

Abstract

The invention provides a method for separating sodium sulfate and sodium chloride from industrial waste salt, which comprises the following steps: s1, dissolving industrial waste salt with a certain mass by using water to obtain a mixed salt solution; s2, heating the mixed salt solution obtained in the step S1 to 100-115 ℃ for distillation, and filtering precipitated salt to obtain primary precipitated salt and primary filtrate when the distilled water amount is m 1; s3, cooling the primary filtrate obtained in the step S2 to 40-45 ℃, then carrying out reduced pressure distillation, and filtering precipitated salt to obtain secondary precipitated salt and secondary filtrate when the distilled water amount is m 2; s4, returning the secondary filtrate obtained in the step S3 to the mixed salt solution in the step S1 for circulation treatment; and S5, detecting the content of sodium sulfate in the primary precipitated salt and the secondary precipitated salt obtained in the steps S2 and S3. The method for separating sodium sulfate and sodium chloride from industrial waste salt disclosed by the invention can be used for separating sodium sulfate and sodium chloride and obtaining high-purity sodium sulfate and sodium chloride.

Description

Method for separating sodium sulfate and sodium chloride from industrial waste salt

Technical Field

The invention belongs to the technical field of industrial waste salt treatment, and particularly relates to a method for separating sodium sulfate and sodium chloride from industrial waste salt.

Background

The pharmaceutical production process can be accompanied by the production of a large amount of waste salt, wherein sodium chloride and sodium sulfate are more in the production process, a large amount of mixed salt wrapping organic matters can be obtained after the pharmaceutical waste liquid generated in the pharmaceutical production process is concentrated and crystallized by MVR at present, the part of salt is temporarily treated as industrial waste salt, but the purity and the content of the salt are not high, the value is not high due to the existence of the organic matters, and the salt-containing organic waste is treated by incineration along with the severe environment protection situation, so that the mainstream trend is reached. After the salt-containing organic matter is treated, most of the remaining salt does not contain organic impurities any more, and if the mixed salt can be separated by a separation method and industrial salt with the purity meeting the national standard is obtained, the problem of environmental protection is solved, benefits can be created for production enterprises, and therefore, how to further purify the mixed salt becomes a problem which needs to be solved urgently.

Disclosure of Invention

In order to solve the technical problems, the invention discloses a method for separating sodium sulfate and sodium chloride from industrial waste salt, which can separate the sodium sulfate and the sodium chloride and obtain the sodium sulfate and the sodium chloride with high purity.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for separating sodium sulfate and sodium chloride from industrial waste salt comprises the following steps:

s1, dissolving industrial waste salt with a certain mass by using water to obtain a mixed salt solution;

s2, heating the mixed salt solution obtained in the step S1 to 100-115 ℃ for distillation, and filtering precipitated salt to obtain primary precipitated salt and primary filtrate when the distilled water amount is m 1;

s3, cooling the primary filtrate obtained in the step S2 to 40-45 ℃, then carrying out reduced pressure distillation, and filtering precipitated salt to obtain secondary precipitated salt and secondary filtrate when the distilled water amount is m 2;

s4, returning the secondary filtrate obtained in the step S3 to the mixed salt solution in the step S1 for circulation treatment;

and S5, detecting the content of sodium sulfate in the primary precipitated salt and the secondary precipitated salt obtained in the steps S2 and S3.

Further, in step S1, the content of sodium sulfate in the industrial waste salt is 70%, the content of sodium chloride is 30%, and the mass M ratio of the industrial waste salt M to water is 1: 3.

Further, in step S2, α 1 is 32% to 35%.

Further, in step S3, the cooling rate is 2-4 ℃/min.

Further, in step S3, the degree of vacuum of the vacuum distillation is 0.09MPa to 0.093 MPa.

Further, in step S3, α 2 is 45% to 48%.

Further, the step S5 is to take a certain mass of the primary precipitated salt and the secondary precipitated salt to be dissolved in water, add a certain mass of barium chloride solution to both solutions, filter and precipitate, dry, weigh the mass of the precipitate, and finally obtain the mass of sodium sulfate in the primary precipitated salt and the secondary precipitated salt.

By adopting the separation method of sodium sulfate and sodium chloride in the industrial waste salt, the separated sodium sulfate is anhydrous sodium sulfate and does not need secondary treatment; when the temperature for evaporating the sodium sulfate at the high temperature is 115 ℃ and the concentration amount is 32% -35%, a qualified sodium sulfate product is obtained, when the sodium chloride is separated out by low-temperature evaporation crystallization, the evaporation temperature is set to be 45 ℃, and the concentration amount is set to be 45% -48%, the qualified sodium chloride product is obtained, the primary yield of the sodium chloride is about 60%, the primary qualified yield of the sodium sulfate is about 76%, when continuous production is realized, the residual filtrate is a saturated salt mother liquor, and the method can be repeatedly recycled without yield problems. The scheme has feasibility for separating sodium sulfate from sodium chloride.

Detailed Description

The present invention will be further described with reference to the following specific examples.

s1, dissolving 100g of industrial waste salt by 300g of water to obtain a mixed salt solution;

s3, cooling the primary filtrate obtained in the step S2 to 40-45 ℃, then carrying out reduced pressure distillation under the condition that the vacuum degree is 0.09MPa, and filtering the precipitated salt when the distilled water amount is m2 to obtain secondary precipitated salt and secondary filtrate;

s5, detecting the content of sodium sulfate in the primary precipitated salt and the secondary precipitated salt obtained in the steps S2 and S3, specifically, dissolving a certain mass of the primary precipitated salt and the secondary precipitated salt in water respectively, adding a certain mass of barium chloride solution into the two solutions, filtering, precipitating, drying, weighing the precipitated mass, and finally obtaining the mass of the sodium sulfate in the primary precipitated salt and the secondary precipitated salt.

In step S2, when m1 is 122g, that is, when the concentration α 1 is 32%, the mass m of the first precipitated salt is 23g, which is written as SH161011A, the mass of the filtrate is 251g, after 20g of water is distilled off, that is, m1 is 142g, when the concentration α 1 is 33%, the mass m of the first precipitated salt is 7.1g, which is written as SH161011B, the mass 25g of water is distilled off, that is, m1 is 167g, and when the concentration α 1 is 35%, the mass m of the first precipitated salt is 6.6g, which is written as SH161011C, and the mass of the remaining filtrate is 192 g; in step S3, when m2 is 60g, that is, when the concentration α 2 is 45%, the mass m of the precipitated salt precipitated twice is 26.5g, lot No. SH161011D, the mass of the filtrate is 101.5g, the mass of distilled water is 30g, that is, m2 is 90g, when the concentration α 2 is 46%, the mass m of the precipitated salt precipitated twice is 10.9g, lot No. SH161011E, the mass of the remaining filtrate is 55g, the mass m of distilled water is 10g, that is, m2 is 100g, and when the concentration α 2 is 48%, the mass m of the precipitated salt precipitated twice is 3.2g, lot No. SH161011F, and the mass m of the remaining filtrate is 39.6 g.

By performing the detection using step S5, experimental data shown in the following table were obtained:

batch number	Na₂SO₄Content (wt.)	NaCl content	Product(s)
				SH161011A	99.3％	---	Na₂SO₄
SH161011B	98.2％	---	Na₂SO₄
				SH161011C	90.6％	---	Na₂SO₄
SH161011D	---	99.3％	NaCl
				SH161011E	---	99.5％	NaCl
SH161011F	39.7％	60.3％	NaCl and Na₂SO₄

As can be seen from the above table, when the temperature for evaporating sodium sulfate at a high temperature is 115 ℃, the amount of evaporated water is 140g, i.e., the concentration amount is 32% -35%, a qualified sodium sulfate product is obtained, the content of sodium sulfate is 98.2% -99.3%, when the evaporation temperature is set to 45 ℃ and the amount of evaporated water is 90g, i.e., the concentration amount is 45% -48%, a qualified sodium chloride product is obtained, the content of sodium chloride is 99.3% -99.5%, the primary yield of sodium chloride is approximately 60%, the primary qualified yield of sodium sulfate is approximately 76%, when continuous production is realized, the remaining filtrate is a saturated salt mother liquor, and the filtrate can be recycled, and the yield problem does not exist.

Those of ordinary skill in the art will understand that: the invention is not to be considered as limited to the specific embodiments thereof, but is to be understood as being modified in all respects, all changes and equivalents that come within the spirit and scope of the invention.

Claims

1. A method for separating sodium sulfate and sodium chloride from industrial waste salt is characterized by comprising the following steps:

s2, heating the mixed salt solution obtained in the step S1 to 100-115 ℃ for distillation, and filtering the precipitated salt to obtain primary precipitated salt and primary filtrate when the distilled water amount is m1 and the concentration amount is alpha 1;

s3, cooling the primary filtrate obtained in the step S2 to 40-45 ℃, and then carrying out reduced pressure distillation, wherein when the distilled water amount is m2 and the concentration amount is alpha 2, the separated salt is filtered to obtain secondary separated salt and secondary filtrate;

2. The method of claim 1, wherein in step S1, the content of sodium sulfate in the industrial waste salt is 70%, the content of sodium chloride is 30%, and the mass M ratio of industrial waste salt M to water is 1: 3.

3. The method for separating sodium sulfate and sodium chloride in industrial waste salt according to claim 1, wherein in step S2, α 1=32% -35%.

4. The method as claimed in claim 1, wherein the temperature reduction rate in step S3 is 2-4 ℃/min.

5. The method for separating sodium sulfate from sodium chloride in industrial waste salt according to claim 1, wherein the vacuum degree of the reduced pressure distillation in step S3 is 0.09MPa to 0.093 MPa.

6. The method for separating sodium sulfate and sodium chloride from industrial waste salt according to claim 1, wherein α 2=45% to 48% in step S3.

7. The method according to claim 1, wherein the step S5 is to dissolve a certain amount of the first and second separated salts in water, add a certain amount of barium chloride solution to both solutions, filter, precipitate, dry, weigh the mass of the precipitate, and obtain the mass of sodium sulfate in the first and second separated salts.