CN115010149A - Method for recycling sodium sulfate and ammonium sulfate from mixed salt - Google Patents
Method for recycling sodium sulfate and ammonium sulfate from mixed salt Download PDFInfo
- Publication number
- CN115010149A CN115010149A CN202210818513.8A CN202210818513A CN115010149A CN 115010149 A CN115010149 A CN 115010149A CN 202210818513 A CN202210818513 A CN 202210818513A CN 115010149 A CN115010149 A CN 115010149A
- Authority
- CN
- China
- Prior art keywords
- salt
- mother liquor
- ammonium sulfate
- sulfate
- ammonium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/24—Sulfates of ammonium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention relates to a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which comprises the following steps: (1) uniformly mixing the solvent, the mixed salt and the sodium removal mother liquor to obtain a mixed salt solution; (2) mixing a first magnesium salt with the mixed salt solution obtained in the step (1), and crystallizing to obtain a complex salt and a deamination mother liquor; (3) mixing a solvent, ammonium salt and the double salt obtained in the step (2), and performing solid-liquid separation to obtain ammonium sulfate mother liquor and a second magnesium salt; recycling the obtained second magnesium salt for the step (2); sequentially carrying out acid regulation and evaporation concentration on the obtained ammonium sulfate mother liquor to obtain ammonium sulfate; heating and salting out the deamination mother liquor in the step (2) in sequence, and separating solid from liquid to obtain sodium sulfate and a sodium removal mother liquor; the obtained sodium-removed mother liquor is recycled in the step (1). The invention introduces a quaternary system, combines a precipitation method and an evaporation concentration method, realizes the high-efficiency recovery of ammonium sulfate and sodium sulfate from mixed salt, and is suitable for industrial production.
Description
Technical Field
The invention relates to the technical field of solid waste treatment, in particular to a method for recycling sodium sulfate and ammonium sulfate from mixed salt.
Background
In the production of chemical industry, metallurgy industry and other industries, such as a sodium treatment vanadium extraction process, an H acid production process and a sodium sulfate alkali production process, a large amount of byproduct wastewater is generated, and the main components of the wastewater comprise inorganic salt and a small amount of heavy metal. At present, waste water is evaporated and concentrated into mixed salt containing sodium sulfate and ammonium sulfate, and the mixed salt is placed in a storage yard for stacking, on one hand, the mixed salt belongs to soluble salt and enters soil and rivers after being washed by rainwater, and great harm is caused to the environment; on the other hand, the stacking and disposal occupy a large space, and simultaneously, the resource waste is also caused.
CN 103570044a discloses a method for treating mixed waste liquid of sodium sulfate and ammonium sulfate with carbonate, which comprises mixing carbonate, mixed salt of sodium sulfate and ammonium sulfate uniformly, then carrying out high-temperature treatment, reacting ammonium sulfate with carbonate to generate ammonium carbonate or ammonium bicarbonate, decomposing the ammonium carbonate or ammonium bicarbonate into ammonia gas, carbon dioxide gas and water, cooling, collecting with water, dissolving residue with water, and filtering to obtain sodium sulfate. In the method, if sodium carbonate and sodium bicarbonate are used as the carbonate, the cost is greatly increased, and if calcium carbonate and calcium bicarbonate are used, calcium ions are introduced; and the water absorbs the tail gas to obtain a mixture of ammonium carbonate and ammonium bicarbonate, thereby further increasing the problem of tail gas treatment.
CN 107867708A discloses a method for processing a mixture of sodium sulfate and ammonium sulfate with sodium chloride, which comprises mixing sodium chloride with a mixed salt of sodium sulfate and ammonium sulfate, calcining at high temperature, allowing ammonium chloride to escape in a gaseous form and be absorbed by water, wherein the residue is sodium sulfate, but ammonium sulfate may decompose sulfur dioxide and sulfur trioxide at high temperature, thereby affecting the quality of ammonium chloride, and ammonium chloride needs to be evaporated and crystallized again after being absorbed by water, which increases energy consumption.
CN107188199A discloses a technology and equipment for recovering ammonium sulfate and sodium sulfate from waste water, the technology separates out sodium sulfate crystals at high temperature and supersaturated ammonium sulfate at low temperature, thereby realizing separation and recovery of sodium sulfate and ammonium sulfate in high-salt content waste water, obtaining industrial-grade sodium sulfate and ammonium sulfate products, and reducing the generation of solid waste or hazardous waste. However, in this method, a large amount of sodium sulfate is carried over when the ammonium sulfate is precipitated by cooling, and complete separation of sodium sulfate and ammonium sulfate cannot be achieved.
In view of the deficiencies of the prior art, it is desirable to provide a method for recovering sodium sulfate and ammonium sulfate with high efficiency, which is simple in operation and low in cost.
Disclosure of Invention
The invention aims to provide a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which realizes the separation of the sodium sulfate and the ammonium sulfate by introducing a quaternary system, and obtains the ammonium sulfate by adopting a precipitation method and an evaporation concentration method.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which comprises the following steps:
(1) uniformly mixing the solvent, the mixed salt and the sodium-removed mother liquor to obtain a mixed salt solution;
(2) mixing a first magnesium salt with the mixed salt solution obtained in the step (1), and crystallizing to obtain a double salt and a deamination mother liquor;
(3) mixing a solvent, ammonium salt and the double salt obtained in the step (2), and performing solid-liquid separation to obtain ammonium sulfate mother liquor and a second magnesium salt; the obtained second magnesium salt is recycled in the step (2); sequentially carrying out acid regulation and evaporation concentration on the obtained ammonium sulfate mother liquor to obtain ammonium sulfate;
heating and salting out the deamination mother liquor in the step (2) in sequence, and separating solid from liquid to obtain sodium sulfate and a sodium removal mother liquor; the obtained sodium-removed mother liquor is reused in the step (1).
According to the method for recovering sodium sulfate and ammonium sulfate from mixed salt, provided by the invention, according to the phase diagram rule of a quaternary system of sodium sulfate, ammonium sulfate and magnesium salt, firstly, double salt is separated, and deamination mother liquor is heated and salted out to obtain sodium sulfate, so that the separation of ammonium sulfate and sodium sulfate is realized; the obtained double salt is subjected to precipitation and evaporative concentration to obtain ammonium sulfate; simultaneously, the second magnesium salt obtained by the reaction and the sodium-removing mother liquor can be recycled, and no waste water and waste residue are discharged; according to the method provided by the invention, the purity of the recovered sodium sulfate and ammonium sulfate is higher, the purity of the sodium sulfate meets the requirements of first-class products of industrial anhydrous sodium sulfate II in GB/T6009-2014, and the purity of the ammonium sulfate meets the requirements of first-type products in GB/T535-2020.
Preferably, the solvent of step (1) comprises water.
Preferably, the mixed salt in step (1) comprises sodium sulfate and ammonium sulfate in a mass ratio of (0.5-2):1, for example, 0.5:1, 1:1, 1.5:1 or 2:1, but not limited to the values listed, and other values not listed in the range of values are also applicable.
Preferably, the mass ratio of the solvent in step (1) to the ammonium sulfate in the mixed salt is (0.85-0.95):1, and may be, for example, 0.85:1, 0.88:1, 0.90:1, 0.92:1 or 0.95:1, but is not limited to the values recited, and other values not recited in the range of values are equally applicable.
Preferably, the first magnesium salt of step (2) comprises magnesium sulfate.
The invention is implemented by reacting to Na 2 SO 4 -(NH4) 2 SO 4 -H 2 Magnesium sulfate is added into the O ternary system, and then the system becomes Na 2 SO 4 -MgSO 4 -(NH4) 2 SO 4 -H 2 In the quaternary system, magnesium sulfate is added to ensure that the composition point of the system falls in a double salt crystallization area and double salt is separated out; and (3) after the temperature of the deamination mother liquor is raised, the composition point of the mother liquor falls into a crystallization area of sodium sulfate to separate out the sodium sulfate, then the sodium sulfate is removed from the mother liquor, and the mother liquor is cooled to dissolve mixed salt, and the steps are repeated in this way to realize the separation of the sodium sulfate and the ammonium sulfate.
Preferably, the molar ratio of the first magnesium salt in step (2) to the ammonium sulfate in the mixed salt in step (1) is (0.8-1.2):1, and may be, for example, 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1, but is not limited to the recited values, and other values not recited in the numerical ranges are equally applicable.
Preferably, the double salt of step (2) comprises MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 O。
The dosage of the first magnesium salt is to separate out MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 The quality of the O double salt has an effect that the molar ratio of the first magnesium salt to the ammonium sulphate increases from 0.8:1 to 1.2:1, MgSO 2 4 ·(NH 4 ) 2 SO 4 ·6H 2 The precipitation mass of the O double salt is increased and then decreased, and when the molar ratio is 1:1, MgSO is precipitated 4 ·(NH 4 ) 2 SO 4 ·6H 2 The mass of the O double salt is the largest.
Preferably, the crystallization temperature in step (2) is 15 to 45 ℃, for example 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃ or 45 ℃, but not limited to the recited values, and other values not recited within the range of values are equally applicable, preferably 25 to 35 ℃.
Preferably, the solvent of step (3) comprises water.
Preferably, the ammonium salt of step (3) comprises ammonium carbonate and/or ammonium bicarbonate.
Preferably, the second magnesium salt of step (3) comprises magnesium carbonate and/or magnesium hydroxide.
Preferably, when the second magnesium salt in the step (3) is reused in the step (2), the second magnesium salt reacts with sulfuric acid to generate the first magnesium salt.
Preferably, the amount of sulfuric acid is such that the second magnesium salt is completely converted to the first magnesium salt.
Preferably, the solvent in step (3) is added in an amount to completely dissolve the double salt obtained in step (2).
Preferably, the ammonium salt in step (3) is added in an amount such that the first magnesium salt in the double salt is completely converted into the second magnesium salt.
Preferably, the solution used for adjusting the acid in step (3) comprises sulfuric acid.
The acid adjustment means that residual ammonium carbonate or ammonium bicarbonate in the obtained ammonium sulfate mother liquor is removed by using sulfuric acid, so that the impurity content can be reduced, and the purity is effectively improved.
Preferably, the sulfuric acid is added in an amount such that the pH of the ammonium sulfate mother liquor is 5.5 or less, and may be, for example, 5.5, 5.4, 5.2, 5.0, 4.8 or 4.5, but is not limited to the recited values, and other values not recited in the numerical ranges are also applicable.
Preferably, the temperature of the evaporative concentration in step (3) is 80 ℃ or more, for example 80 ℃, 82 ℃, 85 ℃, 88 ℃, 90 ℃, 92 ℃ or 95 ℃, but not limited to the recited values, and other values not recited within the range of values are equally applicable.
When the evaporation concentration temperature is lower than 80 ℃, the evaporation concentration speed of the ammonium sulfate mother liquor after acid adjustment is reduced, and the recovery rate of the obtained ammonium sulfate is reduced.
Preferably, the temperature of the temperature-rising salting-out is 50 to 100 ℃, for example, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, or 100 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable, preferably 60 to 80 ℃.
The temperature of the temperature rise salting-out has certain influence on the recovery rate of the sodium sulfate, when the temperature is lower than 50 ℃, sodium sulfate crystals cannot be completely separated out, and the recovery rate of the sodium sulfate is reduced to some extent; when the temperature is higher than 100 ℃, the recovery rate of the sodium sulfate is not increased remarkably.
As a preferred technical scheme of the method, the method comprises the following steps:
(1) uniformly mixing the solvent, the mixed salt and the sodium-removed mother liquor to obtain a mixed salt solution;
the mixed salt comprises sodium sulfate and ammonium sulfate in a mass ratio of (0.5-2) 1; the mass ratio of the solvent to the ammonium sulfate in the mixed salt is (0.85-0.95): 1;
(2) mixing a first magnesium salt with the mixed salt solution obtained in the step (1), and crystallizing at 15-45 ℃ to obtain a double salt and a deamination mother liquor;
the molar weight ratio of the first magnesium salt to the ammonium sulfate in the mixed salt in the step (1) is (0.8-1.2): 1; sequentially heating and salting out the deamination mother liquor at 50-100 ℃ and separating solid from liquid to obtain sodium sulfate and a sodium removal mother liquor; recycling the obtained sodium-removed mother liquor in the step (1);
(3) mixing a solvent, ammonium salt and the double salt obtained in the step (2), and performing solid-liquid separation to obtain ammonium sulfate mother liquor and a second magnesium salt; recycling the obtained second magnesium salt for the step (2); sequentially carrying out acid regulation and evaporation concentration at the temperature of more than or equal to 80 ℃ on the obtained ammonium sulfate mother liquor to obtain ammonium sulfate;
when the second magnesium salt is reused in the step (2), the second magnesium salt reacts with sulfuric acid to generate a first magnesium salt; the adding amount of the solvent is to completely dissolve the double salt obtained in the step (2); the addition amount of the ammonium salt is that the first magnesium salt in the double salt is completely converted into the second magnesium salt; the addition amount of the sulfuric acid used for adjusting the acid is that the pH value of the ammonium sulfate mother liquor is less than or equal to 5.5.
Compared with the prior art, the invention has the following beneficial effects:
according to the method for recovering sodium sulfate and ammonium sulfate from mixed salt, provided by the invention, according to the phase diagram rule of a quaternary system, through temperature rise salting-out and combining a precipitation method and an evaporation concentration method, the high-efficiency recovery of ammonium sulfate and sodium sulfate from the mixed salt is realized, the recovery rate of ammonium sulfate can reach 97%, and the recovery rate of sodium sulfate can reach 96%; the purity of the recovered sodium sulfate can reach 99.2 percent, the requirement of class II first-class products of industrial anhydrous sodium sulfate in GB/T6009-2014 is met, the nitrogen content of the ammonium sulfate can reach 21.06 percent, and the purity of the recovered sodium sulfate can meet the requirement of type I products in GB/T535-2020;
the second magnesium salt and the sodium-removed mother liquor obtained by the reaction in the method can be recycled, no wastewater and waste residues are discharged, and the method is simple to operate, short in flow and suitable for industrial production.
Drawings
Fig. 1 is a process flow diagram of a method for recovering sodium sulfate and ammonium sulfate from mixed salt provided in example 1.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a method for recovering sodium sulfate and ammonium sulfate by mixed salt, as shown in fig. 1, the method includes the following steps:
(1) uniformly mixing water, mixed salt and sodium-removed mother liquor to obtain mixed salt dissolved solution;
the mixed salt comprises sodium sulfate and ammonium sulfate in a mass ratio of 1: 1; the mass ratio of the water to the ammonium sulfate in the mixed salt is 0.9: 1;
(2) mixing magnesium sulfate with the mixed salt solution obtained in the step (1), and crystallizing at 30 ℃ to obtain MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt and deamination mother liquor;
the molar weight ratio of the magnesium sulfate to the ammonium sulfate in the mixed salt in the step (1) is 1: 1; sequentially carrying out temperature rise salting-out and solid-liquid separation on the deamination mother liquor at 70 ℃ to obtain sodium sulfate and a sodium removal mother liquor; recycling the obtained sodium-removed mother liquor in the step (1);
(3) mixing water, ammonium carbonate and MgSO obtained in step (2) 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt, and obtaining ammonium sulfate mother liquor and magnesium carbonate through solid-liquid separation; recycling the obtained magnesium carbonate in the step (2); adjusting the pH value of the obtained ammonium sulfate mother liquor to 4.5 by sulfuric acid, and then evaporating and concentrating at 90 ℃ to obtain ammonium sulfate;
the water is added in an amount of MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 The O double salt is completely dissolved; the ammonium carbonate is added in such an amount that MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 The magnesium sulfate in the O double salt is completely converted into magnesium carbonate.
Example 2
The embodiment provides a method for recovering sodium sulfate and ammonium sulfate by mixed salt, which comprises the following steps:
(1) uniformly mixing water, mixed salt and sodium-removed mother liquor to obtain mixed salt dissolved solution;
the mixed salt comprises sodium sulfate and ammonium sulfate in a mass ratio of 0.7: 1; the mass ratio of the water to the ammonium sulfate in the mixed salt is 0.88: 1;
(2) mixing magnesium sulfate with the mixed salt solution obtained in the step (1), and crystallizing at 40 ℃ to obtain MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt and deamination mother liquor;
the molar weight ratio of the magnesium sulfate to the ammonium sulfate in the mixed salt in the step (1) is 1.1: 1; sequentially carrying out temperature rise salting-out and solid-liquid separation on the deamination mother liquor at 60 ℃ to obtain sodium sulfate and a sodium removal mother liquor; recycling the obtained sodium-removed mother liquor in the step (1);
(3) mixing water, ammonium carbonate and MgSO obtained in step (2) 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt, and obtaining ammonium sulfate mother liquor and magnesium carbonate through solid-liquid separation; recycling the obtained magnesium carbonate in the step (2); adjusting the pH value of the obtained ammonium sulfate mother liquor to 5 by sulfuric acid, and then evaporating and concentrating at 92 ℃ to obtain ammonium sulfate;
the water is added in an amount of MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 Completely dissolving the O double salt; the ammonium carbonate is added in such an amount that MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 The magnesium sulfate in the O double salt is completely converted into magnesium carbonate.
Example 3
The embodiment provides a method for recovering sodium sulfate and ammonium sulfate by mixed salt, which comprises the following steps:
(1) uniformly mixing water, mixed salt and sodium-removed mother liquor to obtain mixed salt dissolved solution;
the mixed salt comprises sodium sulfate and ammonium sulfate in a mass ratio of 1.5: 1; the mass ratio of the water to the ammonium sulfate in the mixed salt is 0.92: 1;
(2) mixing magnesium sulfate with the mixed salt solution obtained in the step (1), and crystallizing at 20 ℃ to obtain MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt and deamination mother liquor;
the molar weight ratio of the magnesium sulfate to the ammonium sulfate in the mixed salt in the step (1) is 0.9: 1; sequentially carrying out temperature rise salting-out and solid-liquid separation on the deamination mother liquor at 80 ℃ to obtain sodium sulfate and a sodium removal mother liquor; recycling the obtained sodium-removed mother liquor in the step (1);
(3) mixing water, ammonium carbonate and MgSO obtained in step (2) 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt, and obtaining ammonium sulfate mother liquor and magnesium carbonate through solid-liquid separation; recycling the obtained magnesium carbonate in the step (2); adjusting the pH value of the obtained ammonium sulfate mother liquor to 4.8 by sulfuric acid, and then evaporating and concentrating at 85 ℃ to obtain ammonium sulfate;
the water is added in an amount of MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 Completely dissolving the O double salt; the ammonium carbonate is added in such an amount that MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 The magnesium sulfate in the O double salt is completely converted into magnesium carbonate.
Example 4
The embodiment provides a method for recovering sodium sulfate and ammonium sulfate by mixed salt, which comprises the following steps:
(1) uniformly mixing water, mixed salt and sodium-removed mother liquor to obtain mixed salt dissolved solution;
the mixed salt comprises sodium sulfate and ammonium sulfate in a mass ratio of 2: 1; the mass ratio of the water to the ammonium sulfate in the mixed salt is 0.85: 1;
(2) mixing magnesium carbonate, sulfuric acid and the mixed salt solution obtained in the step (1), and crystallizing at 45 ℃ to obtain MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt and deamination mother liquor;
the molar weight ratio of magnesium sulfate generated by the reaction of the magnesium carbonate and sulfuric acid to ammonium sulfate in the mixed salt in the step (1) is 0.8: 1; sequentially carrying out temperature rise salting-out and solid-liquid separation on the deamination mother liquor at 50 ℃ to obtain sodium sulfate and a sodium removal mother liquor; recycling the obtained sodium-removed mother liquor in the step (1);
(3) mixing water, ammonium carbonate and MgSO obtained in step (2) 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt, and obtaining ammonium sulfate mother liquor and magnesium carbonate through solid-liquid separation; recycling the obtained magnesium carbonate in the step (2); adjusting the pH value of the obtained ammonium sulfate mother liquor to 5.5 by sulfuric acid, and then evaporating and concentrating at 95 ℃ to obtain ammonium sulfate;
the water is added in an amount of MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 Completely dissolving the O double salt; the ammonium carbonate is added in such an amount that the MgSO is present 4 ·(NH 4 ) 2 SO 4 ·6H 2 The magnesium sulfate in the O double salt is completely converted into magnesium carbonate.
Example 5
The embodiment provides a method for recovering sodium sulfate and ammonium sulfate by mixed salt, which comprises the following steps:
(1) uniformly mixing water, mixed salt and sodium-removed mother liquor to obtain mixed salt dissolved solution;
the mixed salt comprises sodium sulfate and ammonium sulfate in a mass ratio of 0.5: 1; the mass ratio of the water to the ammonium sulfate in the mixed salt is 0.95: 1;
(2) mixing magnesium carbonate, sulfuric acid and the mixed salt solution obtained in the step (1), and crystallizing at 15 ℃ to obtain MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt and deamination mother liquor;
the molar weight ratio of magnesium sulfate generated by the reaction of the magnesium carbonate and sulfuric acid to ammonium sulfate in the mixed salt in the step (1) is 1.2: 1; sequentially carrying out temperature rise salting-out and solid-liquid separation on the deamination mother liquor at 100 ℃ to obtain sodium sulfate and a sodium removal mother liquor; recycling the obtained sodium-removed mother liquor in the step (1);
(3) mixing water, ammonium carbonate and MgSO obtained in step (2) 4 ·(NH 4 ) 2 SO 4 ·6H 2 O double salt, and obtaining ammonium sulfate mother liquor and magnesium carbonate through solid-liquid separation; recycling the obtained magnesium carbonate in the step (2); adjusting the pH value of the obtained ammonium sulfate mother liquor to 5.2 by sulfuric acid, and then evaporating and concentrating at 80 ℃ to obtain ammonium sulfate;
the water is added in an amount of MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 Completely dissolving the O double salt; the ammonium carbonate is added in such an amount that MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 The magnesium sulfate in the O double salt is completely converted into magnesium carbonate.
Example 6
This example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is the same as example 1 except that the crystallization temperature in step (2) is adjusted to 50 ℃.
Example 7
This example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 1 in that the crystallization temperature in step (2) is adjusted to 10 ℃, and is the same as example 1.
Example 8
This example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 1 in that the ratio of the molar weight of the magnesium sulfate in the step (2) to the molar weight of the ammonium sulfate in the mixed salt in the step (1) is adjusted to 1.3:1, and the method is the same as example 1.
Example 9
This example provides a process for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 1 in that the process is the same as example 1 except that the molar ratio of the magnesium sulfate in step (2) to the ammonium sulfate in the mixed salt in step (1) is adjusted to 0.7: 1.
Example 10
This example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 1 in that the temperature of heating and salting out of the deamination mother liquor in step (2) is adjusted to 110 ℃, and the rest is the same as example 1.
Example 11
This example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 1 in that the same as example 1 except that the temperature of temperature rising and salting out of the deamination mother liquor in step (2) is adjusted to 40 ℃.
Example 12
This example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 1 in that the temperature of evaporation concentration in step (3) is adjusted to 70 ℃, and is the same as example 1.
Example 13
This example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 1 in that the same as example 1 except that the mother liquor of ammonium sulfate in step (3) is adjusted to pH 6 by sulfuric acid.
Example 14
This example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 4 in that the method comprises the steps (2) and (3)Replacing magnesium carbonate with magnesium hydroxide in equimolar amount, and replacing ammonium carbonate in the step (3) with ammonium bicarbonate in an amount of MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 The magnesium sulfate in the O double salt was completely converted into magnesium hydroxide, and the rest was the same as in example 4.
Comparative example 1
This comparative example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which is different from example 1 in that step (3) is not treated with acid adjustment, and the rest is the same as example 1.
Comparative example 2
The comparative example provides a method for recovering sodium sulfate and ammonium sulfate from mixed salt, which adopts the process for recovering ammonium sulfate and sodium sulfate from wastewater disclosed in CN107188199A, and comprises the following steps:
s1, filtering the wastewater, settling and filtering the wastewater, separating solid suspended matters in the wastewater, and storing the wastewater after the solid suspended matters are filtered;
s2, preheating and evaporating the wastewater, preheating the wastewater treated in the step S1, raising the temperature and the pressure, and then carrying out flash evaporation and gas-liquid separation to obtain an unsaturated concentrated solution;
s3, circulating the concentrated solution, evaporating and concentrating the unsaturated concentrated solution obtained by gas-liquid separation in the step S2 again until sodium sulfate in the wastewater is concentrated into a supersaturated state, and obtaining supersaturated mother liquor;
s4, crystallizing sodium sulfate, carrying out flash evaporation and gas-liquid separation reaction on the supersaturated mother liquor, separating out and precipitating sodium sulfate crystals, and carrying out solid-liquid separation to obtain sodium sulfate crystals and unsaturated ammonium sulfate mother liquor;
s5, circulating unsaturated ammonium sulfate mother liquor, and circularly evaporating the unsaturated ammonium sulfate mother liquor until ammonium sulfate in the wastewater is concentrated to a supersaturated state;
s6, precipitating ammonium sulfate, and cooling and crystallizing the saturated ammonium sulfate mother liquor obtained in the step S5 to obtain ammonium sulfate crystals;
s7, recycling the liquid obtained in the step S6 to the step S2, and evaporating and concentrating again.
The purity tests of the sodium sulfate obtained in the above examples and comparative examples are carried out according to GB/T6009-2014, the purity tests of the ammonium sulfate obtained in the above examples and comparative examples are carried out according to GB/T535-2014, and the recovery rates of the obtained sodium sulfate and ammonium sulfate are calculated, and the results are shown in Table 1.
TABLE 1
As can be seen from Table 1, as can be seen from comparison of example 1 with examples 2-5, separation of ammonium sulfate and sodium sulfate is achieved by introducing a magnesium salt and controlling the crystallization temperature; by combining a precipitation method and reasonable acid regulation and evaporation concentration temperature, the ammonium sulfate and the sodium sulfate with higher purity and recovery rate are finally obtained;
as is clear from comparison between example 1 and examples 6 and 7, too high or too low crystallization temperature causes less ammonium sulfate to be crystallized and precipitated as double salt, and part of sodium sulfate enters into the double salt, which affects the purity and recovery rate of sodium sulfate and ammonium sulfate; as is clear from comparison of example 1 with examples 8 and 9, excessive addition of magnesium sulfate partially left the mother liquor, and precipitated together with sodium sulfate when the temperature was raised to crystallize sodium sulfate, affecting the quality of sodium sulfate, while too little addition resulted in insufficient amount of precipitated ammonium sulfate, and lowering the recovery rate of ammonium sulfate;
as can be seen from comparison between example 1 and examples 10 and 11, when the temperature rise salting-out temperature is too low, the precipitation amount of sodium sulfate is significantly reduced, the recovery rate is reduced to some extent, and when the temperature is too high, the energy consumption and the operation cost are greatly increased, and the purity of sodium sulfate is not increased any more; as is clear from comparison of example 1 with example 12, when the evaporation concentration temperature is 80 ℃ or lower, ammonium sulfate is not sufficiently precipitated, and the recovery rate thereof is significantly lowered; as can be seen from comparison between example 1 and example 13, when sulfuric acid is used to adjust the acid of the ammonium sulfate mother liquor, the pH value is too high, ammonium carbonate or ammonium bicarbonate remains in the ammonium sulfate mother liquor, and a part of ammonium ions are converted into ammonia gas to enter condensed water during evaporation and concentration, so that the recovery rate of ammonium sulfate is reduced; comparing example 1 with example 14, it is known that the purity and recovery rate of the obtained ammonium sulfate are still high by adopting ammonium bicarbonate to precipitate magnesium salt;
compared with the comparative example 1, the ammonium sulfate mother liquor which is not treated by acid adjustment is evaporated and concentrated, and part of ammonium ions are converted into ammonia gas to enter condensed water, so that the recovery rate of the ammonium sulfate is reduced; in the method for recovering sodium sulfate and ammonium sulfate provided in comparative example 2, residual sodium sulfate in the mother liquor is still carried over when the ammonium sulfate is precipitated by cooling, so that complete separation of sodium sulfate and ammonium sulfate cannot be realized, and the purity of ammonium sulfate is reduced.
In conclusion, according to the method for recovering sodium sulfate and ammonium sulfate from mixed salt, provided by the invention, according to the phase diagram rule of a quaternary system, ammonium sulfate and sodium sulfate can be efficiently recovered from mixed salt by heating and salting out and combining a precipitation method and an evaporation concentration method, wherein the recovery rate of ammonium sulfate can reach 97%, and the recovery rate of sodium sulfate can reach 96%; the purity of the recovered sodium sulfate can reach 99.2 percent, the requirement of class II first-class products of industrial anhydrous sodium sulfate in GB/T6009-2014 is met, the nitrogen content of the ammonium sulfate can reach 21.06 percent, and the purity of the recovered sodium sulfate can meet the requirement of type I products in GB/T535-2020;
the second magnesium salt and the sodium-removed mother liquor obtained by the reaction in the method can be recycled, no wastewater and waste residues are discharged, and the method is simple to operate, short in flow and suitable for industrial production.
The above description is only for the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the protection scope and the disclosure of the present invention.
Claims (10)
1. A method for recovering sodium sulfate and ammonium sulfate from mixed salt is characterized by comprising the following steps:
(1) uniformly mixing the solvent, the mixed salt and the sodium-removed mother liquor to obtain a mixed salt solution;
(2) mixing a first magnesium salt with the mixed salt solution obtained in the step (1), and crystallizing to obtain a double salt and a deamination mother liquor;
(3) mixing a solvent, ammonium salt and the double salt obtained in the step (2), and performing solid-liquid separation to obtain ammonium sulfate mother liquor and a second magnesium salt; recycling the obtained second magnesium salt for the step (2); sequentially carrying out acid regulation and evaporation concentration on the obtained ammonium sulfate mother liquor to obtain ammonium sulfate;
heating and salting out the deamination mother liquor in the step (2) in sequence, and separating solid from liquid to obtain sodium sulfate and a sodium removal mother liquor; the obtained sodium-removed mother liquor is reused in the step (1).
2. The method of claim 1, wherein the solvent of step (1) comprises water;
preferably, the mixed salt in the step (1) comprises sodium sulfate and ammonium sulfate in a mass ratio of (0.5-2): 1;
preferably, the mass ratio of the solvent in the step (1) to the ammonium sulfate in the mixed salt is (0.85-0.95): 1.
3. The process of claim 1 or 2, wherein step (2) the first magnesium salt comprises magnesium sulfate;
preferably, the molar weight ratio of the first magnesium salt in the step (2) to the ammonium sulfate in the mixed salt in the step (1) is (0.8-1.2): 1;
preferably, the double salt of step (2) comprises MgSO 4 ·(NH 4 ) 2 SO 4 ·6H 2 O；
Preferably, the temperature of said crystallization in step (2) is 15-45 ℃, preferably 25-35 ℃.
4. The method according to any one of claims 1 to 3, wherein the solvent of step (3) comprises water;
preferably, the ammonium salt of step (3) comprises ammonium carbonate and/or ammonium bicarbonate.
5. The method of any one of claims 1-4, wherein the second magnesium salt of step (3) comprises magnesium carbonate and/or magnesium hydroxide;
preferably, when the second magnesium salt in the step (3) is reused in the step (2), the second magnesium salt reacts with sulfuric acid to generate the first magnesium salt.
6. The method according to any one of claims 1 to 5, wherein the solvent in step (3) is added in an amount such that the double salt obtained in step (2) is completely dissolved;
preferably, the ammonium salt in step (3) is added in an amount such that the first magnesium salt in the double salt is completely converted into the second magnesium salt.
7. The method according to any one of claims 1 to 6, wherein the solution for adjusting the acid in step (3) comprises sulfuric acid;
preferably, the addition amount of the sulfuric acid is that the pH value of the ammonium sulfate mother liquor is less than or equal to 5.5.
8. The method according to any one of claims 1 to 7, wherein the temperature of the evaporative concentration in step (3) is 80 ℃ or higher.
9. The method according to any of claims 1 to 8, wherein the temperature of the temperature-rising salting-out is 50 to 100 ℃, preferably 60 to 80 ℃.
10. A method according to any of claims 1-9, characterized in that the method comprises the steps of:
(1) uniformly mixing the solvent, the mixed salt and the sodium-removed mother liquor to obtain a mixed salt solution;
the mixed salt comprises sodium sulfate and ammonium sulfate in a mass ratio of (0.5-2) 1; the mass ratio of the solvent to the ammonium sulfate in the mixed salt is (0.85-0.95): 1;
(2) mixing a first magnesium salt with the mixed salt solution obtained in the step (1), and crystallizing at 15-45 ℃ to obtain a double salt and a deamination mother liquor;
the molar weight ratio of the first magnesium salt to the ammonium sulfate in the mixed salt in the step (1) is (0.8-1.2): 1; sequentially heating and salting out the deamination mother liquor at 50-100 ℃ and separating solid from liquid to obtain sodium sulfate and a sodium removal mother liquor; recycling the obtained sodium-removed mother liquor in the step (1);
(3) mixing a solvent, ammonium salt and the double salt obtained in the step (2), and performing solid-liquid separation to obtain ammonium sulfate mother liquor and a second magnesium salt; recycling the obtained second magnesium salt for the step (2); sequentially carrying out acid regulation and evaporation concentration at the temperature of more than or equal to 80 ℃ on the obtained ammonium sulfate mother liquor to obtain ammonium sulfate;
when the second magnesium salt is reused in the step (2), the second magnesium salt reacts with sulfuric acid to generate a first magnesium salt; the adding amount of the solvent is to completely dissolve the double salt obtained in the step (2); the addition amount of the ammonium salt is that the first magnesium salt in the double salt is completely converted into the second magnesium salt; the addition amount of the sulfuric acid used for adjusting the acid is that the pH value of the ammonium sulfate mother liquor is less than or equal to 5.5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210818513.8A CN115010149A (en) | 2022-07-12 | 2022-07-12 | Method for recycling sodium sulfate and ammonium sulfate from mixed salt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210818513.8A CN115010149A (en) | 2022-07-12 | 2022-07-12 | Method for recycling sodium sulfate and ammonium sulfate from mixed salt |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115010149A true CN115010149A (en) | 2022-09-06 |
Family
ID=83079972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210818513.8A Pending CN115010149A (en) | 2022-07-12 | 2022-07-12 | Method for recycling sodium sulfate and ammonium sulfate from mixed salt |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115010149A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115893749A (en) * | 2022-12-19 | 2023-04-04 | 中南大学 | Resource utilization method for lithium battery anode ternary precursor production wastewater |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103570044A (en) * | 2013-10-23 | 2014-02-12 | 王家文 | Method for processing waste mixed liquid of sodium sulfate and ammonium sulfate by using carbonate |
| DE102015003289A1 (en) * | 2015-03-14 | 2016-09-15 | K-Utec Ag Salt Technologies | Process for the preparation of potassium sulfate from ammonium sulfate and potassium chloride |
| CN106830247A (en) * | 2017-03-10 | 2017-06-13 | 衢州华友钴新材料有限公司 | A kind of magnesium sulfate ammonium sulfate composite waste recycling treatment process and system |
| CN113912084A (en) * | 2021-12-09 | 2022-01-11 | 中国科学院过程工程研究所 | Method for preparing sodium carbonate, ammonium sulfate and ammonium chloride by using mixed salt of sodium sulfate and sodium chloride |
-
2022
- 2022-07-12 CN CN202210818513.8A patent/CN115010149A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103570044A (en) * | 2013-10-23 | 2014-02-12 | 王家文 | Method for processing waste mixed liquid of sodium sulfate and ammonium sulfate by using carbonate |
| DE102015003289A1 (en) * | 2015-03-14 | 2016-09-15 | K-Utec Ag Salt Technologies | Process for the preparation of potassium sulfate from ammonium sulfate and potassium chloride |
| CN106830247A (en) * | 2017-03-10 | 2017-06-13 | 衢州华友钴新材料有限公司 | A kind of magnesium sulfate ammonium sulfate composite waste recycling treatment process and system |
| CN113912084A (en) * | 2021-12-09 | 2022-01-11 | 中国科学院过程工程研究所 | Method for preparing sodium carbonate, ammonium sulfate and ammonium chloride by using mixed salt of sodium sulfate and sodium chloride |
Non-Patent Citations (1)
| Title |
|---|
| 巩学敏等: "Na2SO4－MgSO4－(NH4)2SO4－H2O四元体系相图研究及其应用", 工业安全与环保, vol. 42, no. 7, pages 96 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115893749A (en) * | 2022-12-19 | 2023-04-04 | 中南大学 | Resource utilization method for lithium battery anode ternary precursor production wastewater |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7214355B2 (en) | Production of lithium compounds directly from lithium containing brines | |
| US6936229B1 (en) | Recovery of lithium compounds from brines | |
| US7390466B2 (en) | Production of lithium compounds directly from lithium containing brines | |
| CN111039310B (en) | Method for preparing sodium bicarbonate and co-producing ammonium sulfate from sodium sulfate | |
| JP2023500313A (en) | Extraction - Method for extracting lithium by back-extraction separation and purification | |
| CN102531025B (en) | Method for treating rare earth ammonium chloride wastewater | |
| CN108707748B (en) | Method for purifying stone coal pickle liquor and recovering aluminum, potassium and iron | |
| BR112018003045B1 (en) | Methods for producing a scandium-containing concentrate from waste sludge, and for producing a scandium oxide of high purity | |
| CN113045089B (en) | Method for refining and purifying etching waste liquid | |
| CN110143604B (en) | Method for recovering alkali, selenium and arsenic from antimony smelting arsenic alkali slag | |
| CN110116991B (en) | Recovery process for purifying waste acid by making acid from smelting flue gas | |
| CN111039305B (en) | Method for preparing sodium bicarbonate and ammonium sulfate by sodium sulfate in short process | |
| CN108396158A (en) | A kind of processing method of the complex salt crystal object of electrolytic manganese process | |
| CN108793200B (en) | Method for separating potassium sulfate by using sodium-potassium-sulfur-chlorine quaternary system | |
| CN115010149A (en) | Method for recycling sodium sulfate and ammonium sulfate from mixed salt | |
| CN113336260B (en) | Method for recovering copper sulfate in acidic copper sulfate waste liquid | |
| CN102328947B (en) | Method for recovering strontium slag | |
| CN113896209A (en) | Method for preparing sodium carbonate and byproducts potassium sulfate, ammonium sulfate and ammonium chloride from waste salt | |
| CN113023749A (en) | Method for resource utilization of etching process waste | |
| CN109110783B (en) | Separation method of sodium sulfate and ammonium sulfate mixed salt and treatment method of vanadium precipitation waste | |
| CN108946767B (en) | Method for separating potassium sulfate by using sodium-potassium-sulfur-chlorine quaternary system | |
| CN113930629A (en) | Method for treating crystallization mother liquor of calcification vanadium precipitation process | |
| CN101659422B (en) | Ammonium salt solution concentration method | |
| CN114369725B (en) | Method for treating low-concentration electrolytic manganese wastewater and preparing trimanganese tetroxide and magnesium ammonium phosphate | |
| CN111689520B (en) | Method for two-stage vacuum preparation of ammonium paratungstate decahydrate |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |