Quaternary sulfuric acid molten salt heat storage material based on salt lake resources as well as preparation method and application of quaternary sulfuric acid molten salt heat storage material

Abstract

The invention discloses a quaternary sulfuric acid molten salt heat storage material based on salt lake resources as well as a preparation method and application of the quaternary sulfuric acid molten salt heat storage material. The preparation method comprises the following steps: freezing and recrystallizing first sulfate type salt lake raw brine to prepare sodium sulfate decahydrate; carrying out evaporative crystallization and recrystallization treatment on the second sulfate type salt lake raw brine to prepare magnesium sulfate heptahydrate; mixing the sodium sulfate decahydrate, the magnesium sulfate heptahydrate, the potassium sulfate and the calcium sulfate, heating to a first dehydration temperature at a first heating rate for first heat treatment, heating to a second dehydration temperature at a second heating rate for second heat treatment, and heating to a melt blending temperature at a third heating rate for third heat treatment, the quaternary sulfuric acid molten salt heat storage material is prepared. The quaternary sulfuric acid molten salt is prepared by a one-step method through a dehydration and coupling technology, so that high-valued utilization of sodium, potassium, magnesium and calcium resources of a salt lake is realized, the process flow is simplified, and the cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat storage materials, and in particular relates to a quaternary sulfuric acid molten salt heat storage material based on salt lake resources, and a preparation method and application thereof. Background Art

[0002] Due to the continuous use of fossil energy, fossil energy is gradually becoming exhausted, and the environmental and climate problems caused by it are becoming increasingly serious. Renewable energy plays an important role in alleviating global warming and climate change. Solar energy is considered to be one of the most promising alternative energy sources because it is pollution-free and has abundant reserves, and solar thermal power generation (CSP) is one of the main ways to utilize solar energy. According to the type and cycle efficiency of thermodynamic cycles, CSP technology can be divided into three generations. The first and second generation CSP technologies both use Rankine cycles, and the peak cycle temperatures are all below 550°C. Using Solar Salt (NaNO3-KNO3) for heat transfer and heat storage can achieve an annual power generation efficiency of 10~20%. In the third generation CSP technology, the utilization efficiency of solar energy can be further improved by using the Brayton cycle with a peak cycle temperature of >700°C. At present, the most commonly used heat storage materials in solar thermal power stations are nitrate Solar Salt and nitrite Hitec. However, the lower decomposition temperature (550°C) limits its application in the third generation CSP. Therefore, for the third generation CSP, it is very important to design and develop molten salts that can operate stably at high temperatures.

[0003] Chlorides, carbonates, sulfates and fluorides are considered to be potential candidate molten salts in the field of high-temperature heat transfer and have therefore been widely studied. Tian et al. prepared NaCl-CaCl2 eutectic salt. Wei et al. developed a ternary chloride molten salt composed of NaCl, CaCl2 and MgCl2. Patange et al. studied the CuCl-KCl-NaCl ternary molten salt. It can be seen that the existing molten salts are mostly nitrates, carbonates and chlorides, and the raw materials prepared are mostly industrial-grade or molten salt-grade nitrates, carbonates and chlorides, and the quaternary molten salt of sodium sulfate-potassium sulfate-magnesium sulfate-calcium sulfate has not been reported. Summary of the invention

[0004] The main purpose of the present invention is to provide a quaternary sulfuric acid molten salt heat storage material based on salt lake resources and its preparation method and application, so as to overcome the shortcomings of the prior art.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes: The embodiment of the present invention provides a method for preparing a quaternary sulfuric acid molten salt heat storage material based on salt lake resources, which comprises: The first sulfate salt lake raw brine is subjected to freezing and recrystallization treatment to obtain sodium sulfate decahydrate; The raw brine of the second sulfate salt lake is subjected to evaporation, crystallization and recrystallization to obtain magnesium sulfate heptahydrate; Furthermore, the sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate, and calcium sulfate are mixed and heated to a first dehydration temperature at a first heating rate for a first heat treatment, then heated to a second dehydration temperature at a second heating rate for a second heat treatment, and then heated to a melt blending temperature at a third heating rate for a third heat treatment to obtain a quaternary sulfuric acid molten salt heat storage material.

[0006] The embodiment of the present invention also provides a quaternary sulfuric acid molten salt heat storage material based on salt lake resources prepared by the aforementioned preparation method, wherein the quaternary sulfuric acid molten salt heat storage material has a melting point of 680-700°C and a decomposition temperature of 1005-1100°C.

[0007] An embodiment of the present invention further provides an energy storage material, which at least includes the aforementioned quaternary sulfuric acid molten salt heat storage material based on salt lake resources.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate and calcium sulfate, which are abundant in salt lakes, as raw materials, and prepares quaternary sulfate molten salt in a one-step method through dehydration and coupling technology, which not only makes high-value utilization of salt lake sodium, potassium, magnesium and calcium resources, but also reduces the energy consumption of preparing sulfate by dehydration followed by high-temperature blending in a one-step method, simplifies the process flow and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 It is a melting point diagram of the quaternary sulfuric acid molten salt heat storage material in Embodiment 3 of the present invention; Figure 2 This is a decomposition temperature diagram of the quaternary sulfuric acid molten salt heat storage material in Implementation 3 of the present invention. DETAILED DESCRIPTION

[0011] In view of the defects of the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0012] Specifically, as one aspect of the technical solution of the present invention, a method for preparing a quaternary sulfuric acid molten salt heat storage material based on salt lake resources includes: The first sulfate salt lake raw brine is subjected to freezing and recrystallization treatment to obtain sodium sulfate decahydrate; The raw brine of the second sulfate salt lake is subjected to evaporation, crystallization and recrystallization to obtain magnesium sulfate heptahydrate; Furthermore, the sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate, and calcium sulfate are mixed and heated to a first dehydration temperature at a first heating rate for a first heat treatment, then heated to a second dehydration temperature at a second heating rate for a second heat treatment, and then heated to a melt blending temperature at a third heating rate for a third heat treatment to obtain a quaternary sulfuric acid molten salt heat storage material.

[0013] In some preferred embodiments, the preparation method specifically includes: mixing sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate and calcium sulfate evenly and heating the mixture to 50-100°C at a first heating rate of 1-10°C / min for a first heat treatment, then heating the mixture to 250-350°C at a second heating rate of 1-10°C / min for a second heat treatment, then heating the mixture to 750-850°C at a third heating rate of 10-20°C / min for a third heat treatment, and finally cooling the mixture to room temperature to obtain the quaternary sulfuric acid molten salt heat storage material.

[0014] In some preferred embodiments, the mass ratio of the sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate and calcium sulfate is 57.6-61.6:25-28:4.4:1-10.

[0015] In some preferred embodiments, the first heat treatment is performed for 1 to 4 hours.

[0016] In some preferred embodiments, the second heat treatment is performed for 1 to 4 hours.

[0017] In some preferred embodiments, the third heat treatment lasts for 3 to 6 hours.

[0018] In some preferred embodiments, the preparation method specifically comprises: The first sulfate salt lake raw brine is subjected to freezing treatment to obtain a crude sodium sulfate decahydrate product; wherein the first sulfate salt lake raw brine has a sodium ion concentration of 10.0-11.0 wt%, a potassium ion concentration of 0.45-0.51 wt%, a magnesium ion concentration of 0.25-0.35 wt%, a chloride ion concentration of 14.5-15.2 wt%, and a sulfate ion concentration of 3.3-4.0 wt%; And, the crude sodium sulfate decahydrate product is recrystallized to obtain sodium sulfate decahydrate.

[0019] Furthermore, the freezing treatment is carried out at a temperature of -20 to 5°C and for a time of 4 to 10 hours.

[0020] Furthermore, the heating temperature used in the recrystallization treatment is 40-80°C.

[0021] Furthermore, the cooling temperature used during the recrystallization treatment is -20~5°C.

[0022] Furthermore, the purity of the crude sodium sulfate decahydrate product is 85% to 95%.

[0023] Furthermore, the purity of the sodium sulfate decahydrate is greater than 99.0%.

[0024] In some preferred embodiments, the preparation method specifically comprises: The second sulfate salt lake raw brine is subjected to evaporation and crystallization treatment to obtain a crude magnesium sulfate heptahydrate product; wherein the second sulfate salt lake raw brine has a sodium ion concentration of 6.0-8.0 wt%, a potassium ion concentration of 0.70-0.8 wt%, a magnesium ion concentration of 2.0-2.5 wt%, a chloride ion concentration of 14.5-16.0 wt%, and a sulfate ion concentration of 3.3-5.0 wt%; And, the crude magnesium sulfate heptahydrate product is recrystallized to obtain magnesium sulfate heptahydrate.

[0025] Furthermore, the evaporation crystallization treatment is carried out at a temperature of 20-35°C and for a time of 6-12 hours.

[0026] Furthermore, the heating temperature used in the recrystallization treatment is 40-80°C.

[0027] Furthermore, the cooling temperature used during the recrystallization treatment is 5-15°C.

[0028] Furthermore, the purity of the crude magnesium sulfate heptahydrate product is 80% to 95%.

[0029] Furthermore, the purity of the magnesium sulfate heptahydrate is greater than 99.0%.

[0030] In some more specific embodiments, the method for preparing the quaternary sulfuric acid molten salt heat storage material based on salt lake resources comprises the following steps: (1) Using a sulfate salt lake brine as raw material, freezing at a certain temperature to obtain a crude sodium sulfate decahydrate product, and recrystallizing the crude sodium sulfate decahydrate product to obtain sodium sulfate decahydrate with a grade of 99.0%. The sodium ion concentration of the sulfate salt lake brine is 10.0% to 11.0%, the potassium ion concentration is 0.45% to 0.51%, the magnesium ion concentration is 0.25% to 0.35%, the chloride ion concentration is 14.5% to 15.2%, and the sulfate ion concentration is 3.3% to 4.0%. The freezing temperature is -20°C to 5°C; the purity of the crude sodium sulfate decahydrate product is 85% to 95%; the recrystallization heating temperature is 40°C to 80°C, and the recrystallization cooling temperature is -20°C to 5°C; the purity of the sodium sulfate decahydrate product is greater than 99.0%.

[0031] (2) Using a sulfate salt lake brine as raw material, evaporating and crystallizing at a certain temperature to obtain a crude magnesium sulfate heptahydrate product, and recrystallizing the crude magnesium sulfate heptahydrate product to obtain 99.0% magnesium sulfate heptahydrate. The sodium ion concentration of the sulfate salt lake brine is 6.0%~8%, the potassium ion concentration is 0.70%~0.8%, the magnesium ion concentration is 2.0%~2.5%, the chloride ion concentration is 14.5%~16%, and the sulfate ion concentration is 3.3%~5.0%. The evaporation temperature is 20℃~35℃; the purity of the crude magnesium sulfate heptahydrate product is 80%~95%; the recrystallization heating temperature is 40℃~80℃, and the recrystallization cooling temperature is 5℃~15℃; the purity of the magnesium sulfate heptahydrate product is greater than 99.0%.

[0032] (3) According to a certain proportion, 20 g of sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate and calcium sulfate, which are abundant in salt lakes, are weighed in sequence, put into a crucible and mixed evenly, the mixture crucible is placed in a muffle furnace, the temperature is increased to a first dehydration temperature at a certain heating rate and kept at a constant temperature for a certain time, the temperature is further increased to a second dehydration temperature at a certain heating rate and kept at a constant temperature for a certain time, the temperature is further increased to a molten blending temperature at a certain heating rate and kept at a constant temperature for a certain time, and the mixture is cooled to room temperature to obtain a quaternary sulfate molten salt heat storage material. The mixture includes the following components: sodium sulfate decahydrate with a mass fraction of 57.6% to 61.6%, magnesium sulfate heptahydrate with a mass fraction of 25% to 28%, potassium sulfate with a mass fraction of 4.4% and calcium sulfate with a mass fraction of 1% to 10%; the first stage heating rate is 1 to 10°C / min, the first dehydration temperature is 50 to 100°C, and the temperature is kept constant for 1 to 4 hours; the second stage heating rate is 1 to 10°C / min, the first dehydration temperature is 250 to 350°C, and the temperature is kept constant for 1 to 4 hours; the third stage heating rate is 10 to 20°C / min, the melt blending temperature is 750 to 850°C, and the temperature is kept constant for 3 to 6 hours. The sodium sulfate-potassium sulfate-magnesium sulfate-calcium sulfate quaternary molten salt has a melting point of 680 to 700°C and a decomposition temperature of 1005 to 1100°C.

[0033] Another aspect of the embodiments of the present invention further provides a quaternary sulfuric acid molten salt heat storage material based on salt lake resources obtained by the aforementioned preparation method, wherein the quaternary sulfuric acid molten salt heat storage material has a melting point of 680-700°C and a decomposition temperature of 1005-1100°C.

[0034] Another aspect of an embodiment of the present invention further provides an energy storage material, which at least includes the aforementioned quaternary sulfuric acid molten salt heat storage material based on salt lake resources.

[0035] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments. This embodiment is implemented on the premise of the technical solution of the invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0036] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0037] Example 1 1) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 10.0%, the potassium ion concentration is 0.45%, the magnesium ion concentration is 0.25%, the chloride ion concentration is 14.5%, and the sulfate ion concentration is 3.3%. Freeze the brine at -20°C for 4 hours to obtain a crude sodium sulfate decahydrate product with a purity of 85%. The crude sodium sulfate decahydrate product is dissolved at 40°C and recrystallized at -20°C to obtain a sodium sulfate decahydrate product with a purity of 99.2%.

[0038] 2) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 6%, the potassium ion concentration is 0.7%, the magnesium ion concentration is 2.0%, the chloride ion concentration is 14.5%, and the sulfate ion concentration is 3.3%. Evaporate and crystallize the brine at 20°C to obtain a crude magnesium sulfate heptahydrate product with a purity of 80%. The crude magnesium sulfate heptahydrate product is dissolved and evaporated at 40°C for 6 hours, and crystallized at 5°C to obtain a magnesium sulfate heptahydrate product with a purity of 99.0%.

[0039] 3) Weigh 20 g of the above raw materials in a ratio of 57.6% sodium sulfate decahydrate, 28% magnesium sulfate heptahydrate, 10% calcium sulfate and 4.4% potassium sulfate, put them into a crucible and mix them evenly, place the mixture crucible in a muffle furnace, heat it to 50°C at a heating rate of 1°C / min, keep it at this temperature for 1 hour, then heat it to 250°C at a heating rate of 1°C / min, keep it at this temperature for 1 hour, then heat it to 750°C at a heating rate of 10°C / min, keep it at this temperature for 3 hours, and obtain a sodium sulfate-potassium sulfate-magnesium sulfate-calcium sulfate quaternary molten salt with a melting point of 680°C and a decomposition temperature of 1005°C.

[0040] Example 2 1) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 11.0%, the potassium ion concentration is 0.51%, the magnesium ion concentration is 0.35%, the chloride ion concentration is 15.2%, and the sulfate ion concentration is 4.0%. Freeze the brine at 5°C for 10 hours to obtain a crude sodium sulfate decahydrate product with a purity of 95%. The crude sodium sulfate decahydrate product is dissolved at 80°C and recrystallized at 5°C to obtain a sodium sulfate decahydrate product with a purity of 99.0%.

[0041] 2) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 8%, the potassium ion concentration is 0.8%, the magnesium ion concentration is 2.5%, the chloride ion concentration is 16%, and the sulfate ion concentration is 5.0%. Evaporate and crystallize the brine at 35°C to obtain a crude magnesium sulfate heptahydrate product with a purity of 95%. The crude magnesium sulfate heptahydrate product is dissolved and evaporated at 80°C for 12 hours, and crystallized at 15°C to obtain a magnesium sulfate heptahydrate product with a purity of 99.3%.

[0042] 3) Weigh 20 g of the above raw materials in a ratio of 61.6% sodium sulfate decahydrate, 33% magnesium sulfate heptahydrate, 1% calcium sulfate and 4.4% potassium sulfate, put them into a crucible and mix them evenly, place the mixture crucible in a muffle furnace, heat it to 100°C at a heating rate of 10°C / min, keep it constant for 4 hours, then heat it to 350°C at a heating rate of 10°C / min, keep it constant for 4 hours, then heat it to 850°C at a heating rate of 20°C / min, keep it constant for 6 hours, and obtain a sodium sulfate-potassium sulfate-magnesium sulfate-calcium sulfate quaternary molten salt with a melting point of 700°C and a decomposition temperature of 1100°C.

[0043] Example 3 1) Weigh 1 kg of raw brine from a sulfate salt lake, in which the sodium ion concentration is 10.05%, the potassium ion concentration is 0.48%, the magnesium ion concentration is 0.30%, the chloride ion concentration is 15.0%, and the sulfate ion concentration is 3.5%. Freeze the brine at -10°C for 6 hours to obtain a crude sodium sulfate decahydrate product with a purity of 90%. The crude sodium sulfate decahydrate product is dissolved at 60°C and recrystallized at 0°C to obtain a sodium sulfate decahydrate product with a purity of 99.3%.

[0044] 2) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 7%, the potassium ion concentration is 0.75%, the magnesium ion concentration is 2.2%, the chloride ion concentration is 15%, and the sulfate ion concentration is 4%. Evaporate and crystallize the brine at 30°C to obtain a crude magnesium sulfate heptahydrate product with a purity of 90%. The crude magnesium sulfate heptahydrate product is dissolved and evaporated at 60°C for 8 hours, and crystallized at 10°C to obtain a magnesium sulfate heptahydrate product with a purity of 99.1%.

[0045] 3) Weigh 20 g of the above raw materials in a ratio of 59.67% sodium sulfate decahydrate, 30.93% magnesium sulfate heptahydrate, 5% calcium sulfate and 4.4% potassium sulfate, put them into a crucible and mix them evenly. Place the mixture crucible in a muffle furnace, heat it to 80°C at a heating rate of 5°C / min, keep it constant for 3 hours, then heat it to 300°C at a heating rate of 5°C / min, keep it constant for 2 hours, then heat it to 800°C at a heating rate of 15°C / min, keep it constant for 5 hours, and then obtain a sodium sulfate-potassium sulfate-magnesium sulfate-calcium sulfate quaternary molten salt with a melting point of 686.5°C, a decomposition temperature of 1045.79°C, and a specific heat of 1.32 J•K -1 •g -1 ; The melting point diagram of quaternary sulfuric acid molten salt heat storage material is as follows Figure 1 As shown, the decomposition temperature diagram of quaternary sulfuric acid molten salt heat storage material is as follows Figure 2 shown.

[0046] Comparative Example 1 1) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 10.05%, the potassium ion concentration is 0.48%, the magnesium ion concentration is 0.30%, the chloride ion concentration is 15.0%, and the sulfate ion concentration is 3.5%. Freeze the brine at -10°C to obtain a crude sodium sulfate decahydrate product with a purity of 90%. The crude sodium sulfate decahydrate product is dissolved at 60°C and recrystallized at 0°C to obtain a sodium sulfate decahydrate product with a purity of 99.3%.

[0047] 2) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 7%, the potassium ion concentration is 0.75%, the magnesium ion concentration is 2.2%, the chloride ion concentration is 15%, and the sulfate ion concentration is 4%. Evaporate and crystallize the brine at 30°C to obtain a crude magnesium sulfate heptahydrate product with a purity of 90%. The crude magnesium sulfate heptahydrate product is dissolved and evaporated at 60°C and crystallized at 10°C to obtain a magnesium sulfate heptahydrate product with a purity of 99.1%.

[0048] 3) Weigh 20 g of the above raw materials in a ratio of 59.67% sodium sulfate decahydrate, 30.93% magnesium sulfate heptahydrate, 5% calcium sulfate and 4.4% potassium sulfate, put them into a crucible and mix them evenly, place the mixture crucible in a muffle furnace, heat it to 80°C at a heating rate of 5°C / min, keep it at this temperature for 3 hours, then heat it to 300°C at a heating rate of 5°C / min, keep it at this temperature for 2 hours, then heat it to 650°C at a heating rate of 15°C / min, keep it at this temperature for 5 hours, the mixing is uneven, and no sodium sulfate-potassium sulfate-magnesium sulfate-calcium sulfate quaternary molten salt is formed.

[0049] Comparative Example 2 1) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 10.05%, the potassium ion concentration is 0.48%, the magnesium ion concentration is 0.30%, the chloride ion concentration is 15.0%, and the sulfate ion concentration is 3.5%. Freeze the brine at -10°C to obtain a crude sodium sulfate decahydrate product with a purity of 90%. The crude sodium sulfate decahydrate product is dissolved at 60°C and recrystallized at 0°C to obtain a sodium sulfate decahydrate product with a purity of 99.3%.

[0050] 2) Weigh 1 kg of raw brine from a sulfate salt lake, of which the sodium ion concentration is 7%, the potassium ion concentration is 0.75%, the magnesium ion concentration is 2.2%, the chloride ion concentration is 15%, and the sulfate ion concentration is 4%. Evaporate and crystallize the brine at 30°C to obtain a crude magnesium sulfate heptahydrate product with a purity of 90%. The crude magnesium sulfate heptahydrate product is dissolved and evaporated at 60°C and crystallized at 10°C to obtain a magnesium sulfate heptahydrate product with a purity of 99.1%.

[0051] 3) Weigh 20 g of the above raw materials in a ratio of 15% sodium sulfate decahydrate, 20% magnesium sulfate heptahydrate, 50% calcium sulfate and 15% potassium sulfate, put them into a crucible and mix them evenly, place the mixture crucible in a muffle furnace, heat it to 80°C at a heating rate of 5°C / min, keep it at this temperature for 3 hours, then heat it to 300°C at a heating rate of 5°C / min, keep it at this temperature for 2 hours, then heat it to 650°C at a heating rate of 15°C / min, keep it at this temperature for 5 hours, and no sodium sulfate-potassium sulfate-magnesium sulfate-calcium sulfate quaternary molten salt is formed.

[0052] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0053] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical deformation made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a quaternary sulfuric acid molten salt heat storage material based on salt lake resources, characterized in that: include: The first sulfate salt lake raw brine is subjected to freezing and recrystallization treatment to obtain sodium sulfate decahydrate; The raw brine of the second sulfate salt lake is subjected to evaporation, crystallization and recrystallization to obtain magnesium sulfate heptahydrate; Furthermore, the sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate, and calcium sulfate are mixed and heated to a first dehydration temperature at a first heating rate for a first heat treatment, then heated to a second dehydration temperature at a second heating rate for a second heat treatment, and then heated to a melt blending temperature at a third heating rate for a third heat treatment to obtain a quaternary sulfuric acid molten salt heat storage material.

2. The preparation method according to claim 1, characterized in that: Specifically include: Sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate and calcium sulfate are uniformly mixed and heated to 50-100°C at a first heating rate of 1-10°C / min for a first heat treatment, then heated to 250-350°C at a second heating rate of 1-10°C / min for a second heat treatment, then heated to 750-850°C at a third heating rate of 10-20°C / min for a third heat treatment, and finally cooled to room temperature to obtain the quaternary sulfuric acid molten salt heat storage material.

3. The preparation method according to claim 1 or 2, characterized in that: The mass ratio of the sodium sulfate decahydrate, magnesium sulfate heptahydrate, potassium sulfate and calcium sulfate is 57.6-61.6:25-28:4.4:1-10.

4. The preparation method according to claim 1 or 2, characterized in that: The first heat treatment time is 1 to 4 hours; And / or, the second heat treatment time is 1 to 4 hours; And / or, the third heat treatment is performed for 3 to 6 hours.

5. The preparation method according to claim 1, characterized in that: Specifically include: The first sulfate salt lake raw brine is subjected to freezing treatment to obtain a crude sodium sulfate decahydrate product; wherein the first sulfate salt lake raw brine has a sodium ion concentration of 10.0-11.0 wt%, a potassium ion concentration of 0.45-0.51 wt%, a magnesium ion concentration of 0.25-0.35 wt%, a chloride ion concentration of 14.5-15.2 wt%, and a sulfate ion concentration of 3.3-4.0 wt%; And, the crude sodium sulfate decahydrate product is recrystallized to obtain sodium sulfate decahydrate.

6. The preparation method according to claim 5, characterized in that: The freezing treatment temperature is -20~5°C and the time is 4~10h; And / or, the heating temperature used in the recrystallization treatment is 40-80° C.; And / or, the cooling temperature used in the recrystallization treatment is -20~5°C; And / or, the purity of the crude sodium sulfate decahydrate product is 85% to 95%; And / or, the purity of the sodium sulfate decahydrate is greater than 99.0%.

7. The preparation method according to claim 1, characterized in that: Specifically include: The second sulfate salt lake raw brine is subjected to evaporation and crystallization treatment to obtain a crude magnesium sulfate heptahydrate product; wherein the second sulfate salt lake raw brine has a sodium ion concentration of 6.0-8.0 wt%, a potassium ion concentration of 0.70-0.8 wt%, a magnesium ion concentration of 2.0-2.5 wt%, a chloride ion concentration of 14.5-16.0 wt%, and a sulfate ion concentration of 3.3-5.0 wt%; And, the crude magnesium sulfate heptahydrate product is recrystallized to obtain magnesium sulfate heptahydrate.

8. The preparation method according to claim 7, characterized in that: The evaporation crystallization treatment is performed at a temperature of 20 to 35°C for 6 to 12 hours; And / or, the heating temperature used in the recrystallization treatment is 40-80° C.; And / or, the cooling temperature used in the recrystallization treatment is 5-15°C; And / or, the purity of the crude magnesium sulfate heptahydrate product is 80% to 95%; And / or, the purity of the magnesium sulfate heptahydrate is greater than 99.0%.

9. A quaternary sulfuric acid molten salt heat storage material based on salt lake resources prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The melting point of the quaternary sulfuric acid molten salt heat storage material is 680-700°C, and the decomposition temperature is 1005-1100°C.

10. An energy storage material, characterized in that At least includes the quaternary sulfuric acid molten salt heat storage material based on salt lake resources as described in claim 9.

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