A kind of preparation method of calcium hexaborate

Abstract

The invention provides a preparation method of calcium hexaborate. The method comprises the following steps: mixing antarcticite, a byproduct of oilfield brine, and deionized water, heating and stirring, dissolving to obtain a calcium chloride solution, filtering and separating the solution, cooling and crystallizing the solution, and obtaining recrystallized calcium chloride hexahydrate; the recrystallized calcium chloride hexahydrate and a sodium borate solution are reacted under stirring conditions in a constant temperature water bath to obtain calcium hexaborate tetrahydrate or calcium hexaborate pentahydrate.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of salt lake resources, in particular to calcium hexaborate and a preparation method thereof, in particular to a method for preparing calcium hexaborate by utilizing oilfield brine byproducts. Background Art

[0002] Boron is a typical non-metallic element, located in the third main group of the second period in the periodic table. It has a unique electron-deficient characteristic and exists mainly in the form of inorganic boric acid and boric acid salt in nature. 2 Planar triangle or sp 3 The tetrahedral form forms a variety of borate compounds with complex and diverse structures with oxygen atoms and boron atoms. Calcium borate is an important emerging chemical raw material that can be used in ceramics, alkali-free glass fiber and other industries. It replaces the original boric acid, borax and natural boron magnesium stone, greatly reducing the volatilization of boron oxide. It is currently an ideal raw material for direct spinning in imported glass melting furnaces. The strength of glass fiber with calcium borate is greatly improved. Calcium borate is also an excellent inorganic flame retardant with the advantages of high thermal stability, non-toxicity, smoke elimination, low toxicity of combustion products, environmental protection and permanent flame retardancy. It is also used as an additive in gasoline, diesel and other fuel oils to improve combustion efficiency.

[0003] Calcium borate exists in two forms: natural and synthetic. There are many different calcium borate compositions. Natural calcium borates mainly include: colemanite (2CaO·3B2O3·5H2O), ulexite (NaCaB3B2O7(OH)4·6H2O), monetite (2CaO·3B2O3·7H2O) and monoclinic colemanite (2CaO·3B2O3·13H2O). The first two calcium borates are mainly used in industry. These natural calcium borate minerals contain a large amount of impurities and need to be deeply processed before they can be used. Synthetic calcium borates mainly include binary diborates (CaO·B2O3·nH2O), binary tetraborates and tetrabasic hexaborates (2CaO·3B2O3·nH2O). Among them, binary diborates mainly include tetrahydrates and hexahydrates, and tetrabasic hexaborates mainly include tetrahydrates and pentahydrates. The latter has a higher content of boron trioxide, about 62% and 59% respectively, and is the main compound required for industrial production.

[0004] The main methods for synthesizing calcium borate include borate lime milk method, sodium polyborate lime method, borax sodium hydroxide calcium sulfate method and double decomposition reaction method. Calcium hexaborate is the most acidic calcium borate synthesized in aqueous solution. Chinese invention patent CN1083398C discloses a method for producing crystalline calcium hexaborate tetrahydrate using boric acid and calcium oxide. Chinese invention patent CN1099375C discloses a method for producing boric acid from colemanite and colemanite with sulfuric acid at 90-100°C, and then reacting boric acid with calcium hydroxide to obtain calcium borate with high purity. Chinese invention patent CN109928401A discloses a method for preparing calcium borate, which is to prepare the ingredients according to the molar ratio of calcium oxide to boric acid of 1:3, and then obtain the product by dry mixing, potting and low-temperature sintering, wherein the sintering temperature is 220-470°C. Chinese invention patent CN104556082A discloses a method for preparing calcium borate, wherein the ingredients are prepared according to a molar ratio of calcium oxide to boric acid of 1:2, and then the product is obtained by dry mixing, potting, and low-temperature sintering, wherein the sintering temperature is 120-470°C. Through analysis of the above disclosed technical solutions, it can be seen that in the prior art, high-purity calcium hexaborate is prepared by high-temperature sintering of calcium oxide and boric acid, which has high energy consumption; or, calcium-containing ore is reacted with boric acid at high temperature, and under high temperature conditions, the risk factor is high during the operation process, which increases the difficulty of the production process.

[0005] Cao Chun'e et al. disclosed in Study on Process Parameters and Performance Characterization of Synthesizing Calcium Hexaborate Tetrahydrate from Boric Acid and Calcium Oxide, Rare Metal Materials and Engineering, 2007.8, 36 (suppl. 1) that calcium hexaborate tetrahydrate is prepared by reacting calcium oxide and boric acid, and gave the reaction conditions and the morphology of calcium hexaborate tetrahydrate. Chemical raw materials are used as the raw materials for the reaction, and calcium oxide is derived from the product of high-temperature calcination of light calcium carbonate. The cost and energy consumption are relatively high, and the pH is mainly adjusted as the main means of adjusting the synthesis of calcium hexaborate tetrahydrate, which has great limiting factors in actual operation.

[0006] Furthermore, Shi Chunhui et al. prepared calcium hexaborate pentahydrate by hydrothermal method at 120 °C for 3 h using boric acid and calcium hydroxide as raw materials in the study of hydrothermal synthesis and high temperature phase transition of calcium hexaborate pentahydrate, Inorganic Salt Industry, July 2019, Vol. 51(7), to give CaB6O 10 The basic unit in is B3O7, so the crystalline CaB6O with the basic structural unit of B3O7 10 It may become a potential nonlinear optical crystal material.

[0007] In summary, in the prior art, the preparation of calcium hexaborate tetrahydrate or pentahydrate using chemical raw materials as reactants has high raw material costs and has the defects of high cost and high energy consumption, which limits large-scale promotion and application.

[0008] The southern wing mountain area of ​​the Qaidam Basin has abundant CaCl2 oilfield brine, which contains mineral resources such as potassium, boron, lithium, strontium, rubidium, bromine and iodine, and has great development and application value. Studies have shown that the oilfield brine is saturated with calcium chloride in the later stage of evaporation and concentration, which is used for the separation and extraction of lithium, bromine and iodine, but a large amount of by-product calcium chloride solution or solid has not been comprehensively developed and utilized. Therefore, the present invention uses the by-product calcium chloride hexahydrate solid of oilfield brine as a raw material to provide a method for preparing calcium hexaborate, thereby realizing the high-value utilization of oilfield brine calcium resources, and has the advantages of simple preparation process, easy operation, low production cost, low energy consumption, etc. Summary of the invention

[0009] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a method for preparing calcium hexaborate, which uses calcium chloride, a by-product of oilfield brine, as a raw material to prepare calcium hexaborate, thereby solving the technical problems of low purity, high cost and high energy consumption of calcium hexaborate, and has the characteristics of simple process engineering, easy operation and low energy consumption, thereby reducing production costs; at the same time, the utilization efficiency of oilfield brine calcium resources is improved, and the high-value utilization path of salt lake calcium resources is broadened.

[0010] To achieve the above objectives, the present invention provides the following technical solutions.

[0011] A method for preparing calcium hexaborate comprises the following steps: mixing antarcticite, a byproduct of oilfield brine, with deionized water, heating and stirring, dissolving to obtain a calcium chloride solution, filtering and separating, and cooling and crystallizing to obtain recrystallized calcium chloride hexahydrate; the recrystallized calcium chloride hexahydrate and a sodium borate solution are reacted under a constant temperature water bath and stirring to obtain calcium hexaborate tetrahydrate or calcium hexaborate pentahydrate.

[0012] Preferably, the content of calcium chloride hexahydrate in the Antarcticite is 85-95%.

[0013] Preferably, the molar ratio of the oilfield brine byproduct Antarcticite and deionized water is 0.3-0.65:1; the raw material purity of the oilfield brine byproduct calcium chloride hexahydrate is 85-95%.

[0014] Preferably, the molar ratio of the recrystallized calcium chloride hexahydrate to the boron in the sodium borate solution is 0.2-1.5:1.

[0015] Preferably, the temperature of the heating and stirring process is 25 to 45° C.; and / or the number of cooling crystallization is 1 to 3 times; the temperature of the cooling crystallization is -25 to -15° C., and the time is 12 to 48 hours.

[0016] Preferably, the purity of the recrystallized calcium chloride hexahydrate is ≥99%, and the shape is needle-shaped crystals.

[0017] Preferably, the sodium borate solution is prepared by dissolving sodium hydroxide and solid boric acid in water, and the molar ratio of boric acid to water is 0.02 to 0.05:1.

[0018] Preferably, the molar ratio of sodium hydroxide solid to boric acid is 0.1-0.3:1.

[0019] Preferably, the constant temperature water bath temperature is 25-50° C., the recrystallized calcium chloride hexahydrate reacts with the sodium borate solution for 3-7 days, and the calcium hexaborate tetrahydrate is obtained after drying, and the drying temperature is 35-60° C. Preferably, when the molar ratio of the recrystallized calcium chloride hexahydrate to the boron in the sodium borate solution is 0.4-1.0:1, the ratio of boron oxide to calcium oxide in the prepared calcium hexaborate tetrahydrate is closest to the theoretical ratio, and the purity is higher.

[0020] Preferably, the constant temperature water bath temperature is 60-100° C., the recrystallized calcium chloride hexahydrate reacts with the sodium borate solution for 6-48 hours, and the calcium hexaborate pentahydrate is obtained after drying, and the drying temperature is 35-60° C. Preferably, when the molar ratio of the recrystallized calcium chloride hexahydrate to the boron in the sodium borate solution is 0.4-0.8:1, the ratio of boron oxide to calcium oxide in the prepared calcium hexaborate pentahydrate is closer to the theoretical ratio and has higher purity.

[0021] The invention prepares a sodium pentaborate solution by reacting boric acid with solid sodium hydroxide, and then reacts the solution with calcium chloride to prepare calcium hexaborate pentahydrate. The preparation process is simple in principle and low in raw material cost. A high-value calcium hexaborate pentahydrate product is obtained from low-cost oilfield brine, thereby broadening the high-value conversion pathway of the salt lake resource.

[0022] The technical effects of the technical solution of the present invention are as follows:

[0023] 1. By adopting the technical solution of the present invention, the preparation of calcium hexaborate tetrahydrate or calcium hexaborate pentahydrate is achieved by regulating the temperature of a constant temperature water bath. The conditions are mild, and there is no need to carry out an acid-base reaction under high temperature conditions. The process is simple, easy to operate, and has low production costs.

[0024] 2. By adopting the technical solution of the present invention, Antarcticite, a by-product of oilfield brine, is used as a raw material to prepare calcium hexaborate, which not only reduces the production cost of calcium hexaborate, but also improves the utilization efficiency of oilfield brine calcium resources and broadens the high-value utilization path of salt lake calcium resources.

[0025] 3. By adopting the technical solution of the present invention, the purity of calcium chloride is improved by multiple recrystallization of calcium chloride in oilfield brine. On the one hand, the process is simple and easy to control, and on the other hand, the purity of calcium hexaborate is further improved.

[0026] 4. By adopting the technical solution of the present invention, calcium hexaborate tetrahydrate or calcium hexaborate pentahydrate can be obtained only by adjusting the reaction conditions, which has strong process selectivity and comprehensive utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a comparison chart of the XRD diffraction patterns of the calcium hexaborate tetrahydrate prepared in Example 1 of the present invention and the standard calcium hexaborate tetrahydrate.

[0028] Figure 2 This is a comparison chart of the XRD diffraction spectra of the calcium hexaborate pentahydrate prepared in Example 3 of the present invention and the standard calcium hexaborate pentahydrate. DETAILED DESCRIPTION

[0029] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0030] The invention provides a preparation method of calcium hexaborate. The method comprises the following steps: mixing antarcticite, a byproduct of oilfield brine, and deionized water, heating and stirring, dissolving to obtain a calcium chloride solution, filtering and separating the solution, cooling and crystallizing the solution, and obtaining recrystallized calcium chloride hexahydrate; the recrystallized calcium chloride hexahydrate and a sodium borate solution are reacted under stirring conditions in a constant temperature water bath to obtain calcium hexaborate tetrahydrate or calcium hexaborate pentahydrate.

[0031] The technical solution of the present invention is further described in detail below through specific embodiments.

[0032] Example 1

[0033] This embodiment provides a calcium hexaborate tetrahydrate, and the specific preparation steps include:

[0034] 1. Weigh 320 g of solid Antarcticite (calcium chloride hexahydrate, purity ~95%) produced by oilfield brine and 45 g of deionized water, stir at 45°C, filter and separate to remove insoluble matter, place the filtrate in a refrigerator at -20°C for 12 hours to cool and crystallize, and separate the solid and liquid.

[0035] 2. The solid phase obtained by solid-liquid separation in step 1 was washed with a newly prepared saturated calcium chloride solution, and dried at room temperature to obtain a needle-shaped crystal recrystallized calcium chloride hexahydrate product with a purity of 99.1%.

[0036] 3. Weigh 7.73 g (0.12 mol) of boric acid solid and 1.02 g of sodium hydroxide solid and dissolve them in 75 g of water to prepare a sodium borate solution, which is placed in a constant temperature water bath with a magnetic stirrer at 25°C. Add 11 g of recrystallized calcium chloride hexahydrate solid to the sodium borate solution in two equal batches, with an interval of 5 minutes between each batch addition to prepare a slurry.

[0037] 4. After stirring the slurry in step 3 for 4 days, separate the solid and liquid, wash the solid phase with water and ethanol respectively, and dry at 45°C to obtain the calcium hexaborate tetrahydrate product. 0.4:1

[0038] Example 2

[0039] The difference between this embodiment and embodiment 1 is that in step 3, the mass of calcium chloride hexahydrate solid added at one time is 11 g.

[0040] Example 3

[0041] The difference between this embodiment and embodiment 1 is that in step 3, 11 g of solid calcium chloride hexahydrate is added to the sodium borate solution in five equal batches, and the slurry is stirred and reacted for 6 days before solid-liquid separation.

[0042] Example 4

[0043] The difference between this embodiment and embodiment 1 is that in step 3, 40 g of solid calcium chloride hexahydrate is added in equal amounts in five batches.

[0044] Example 5

[0045] The difference between this embodiment and embodiment 1 is that in step 3, 26 g of solid calcium chloride hexahydrate is added in equal amounts in three batches.

[0046] Example 6

[0047] This embodiment provides a calcium hexaborate tetrahydrate, and the specific preparation steps include:

[0048] 1. Weigh 320g of solid Antarcticite (purity of calcium chloride hexahydrate is about 92%) produced by oilfield brine and 55g of deionized water, stir at 35℃, filter and separate, remove insoluble matter, and place the filtrate in a refrigerator at -22℃ for 24h to cool and crystallize, and separate the solid and liquid.

[0049] 2. Wash the solid phase with a newly prepared saturated calcium chloride solution and dry it at room temperature to obtain a needle-shaped crystal of recrystallized calcium chloride hexahydrate product with a purity of 99.0%.

[0050] 3. Weigh 7.73 g of boric acid solid and 1.02 g of sodium hydroxide solid and dissolve them in 50 g of water to obtain a sodium borate solution, which is placed in a constant temperature water bath magnetic stirrer at 45°C. Then, 20 g of recrystallized calcium chloride hexahydrate solid is added in equal amounts in two batches, with an interval of 5 minutes between each addition, to obtain a slurry.

[0051] 4. After the slurry obtained in step 3 has reacted for 7 days, the solid and liquid are separated, the solid phase is washed with water and ethanol respectively, and dried at 50° C. to obtain a calcium hexaborate tetrahydrate product.

[0052] Example 7

[0053] This embodiment provides a calcium hexaborate pentahydrate, and the specific preparation steps include:

[0054] 1. Weigh 320g of solid Antarcticite (purity of calcium chloride hexahydrate is about 89%) produced by oilfield brine and 65g of deionized water, stir at 30℃, filter and separate, remove insoluble matter, and place the filtrate in a refrigerator at -17℃ for 20h to cool and crystallize, and separate the solid and liquid.

[0055] 2. Wash the solid phase with a newly prepared saturated calcium chloride solution and dry it at room temperature to obtain a needle-shaped crystal calcium chloride hexahydrate product. The needle-shaped crystals are recrystallized once, and the purity of the obtained calcium chloride hexahydrate product is 99.2%.

[0056] 3. Weigh 7.73 g of boric acid solid and 1.02 g of sodium hydroxide solid and dissolve them in 60 g of water to obtain a sodium borate solution, which is placed in a constant temperature water bath with a magnetic stirrer at 60°C. Add 26 g of calcium chloride hexahydrate solid prepared in step 2 to the sodium borate solution in two equal batches, with an interval of 10 minutes between each batch addition, to obtain a slurry.

[0057] 4. After the slurry obtained in step 3 is reacted for 48 hours, the solid and liquid are separated, the solid phase is washed with water and ethanol respectively, and dried at 50° C. to obtain a calcium hexaborate pentahydrate product.

[0058] Example 8

[0059] The difference between this embodiment and embodiment 7 is that in step 3, 11 g of calcium chloride hexahydrate solid prepared in step 2 is added to the sodium borate solution in two equal batches.

[0060] Example 9

[0061] The difference between this embodiment and embodiment 7 is that in step 3, 40 g of calcium chloride hexahydrate solid prepared in step 2 is added to the sodium borate solution in two equal batches.

[0062] Example 10

[0063] This embodiment provides a calcium hexaborate pentahydrate, and the specific preparation steps include:

[0064] 1. Weigh 320 g of solid Antarcticite (purity of calcium chloride hexahydrate is 85%) produced by oilfield brine and 80 g of deionized water, stir at 25°C, filter and separate to remove insoluble matter, and place the filtrate in a refrigerator at -15°C for 24 hours for cooling and crystallization, and then separate the solid and liquid.

[0065] 2. Wash the solid phase with a newly prepared saturated calcium chloride solution and dry it at room temperature to obtain a needle-shaped crystal of calcium chloride hexahydrate. The needle-shaped crystals are recrystallized twice, and the product purity can reach 99.2%.

[0066] 3. Weigh 7.73 g of boric acid solid and 1.02 g of sodium hydroxide solid and dissolve them in 75 g of water to obtain a sodium borate solution, which is placed in a constant temperature water bath magnetic stirrer at 95°C. Then, 11 g of recrystallized calcium chloride hexahydrate solid is added in equal amounts in two batches, with an interval of 5 minutes between each addition, to obtain a slurry.

[0067] 4. After the slurry prepared in step 3 is reacted for 12 hours, the solid-liquid separation is carried out, the solid phase is washed with water and ethanol respectively, and dried at 55° C. to obtain a calcium hexaborate pentahydrate product.

[0068] Comparative Example 1

[0069] The only difference between this comparative example and Example 1 is that Antarcticite (calcium chloride hexahydrate with a purity of about 95%) produced as a by-product of oilfield brine is directly used and added to the sodium borate solution in step 3. The other steps are the same to obtain a calcium hexaborate tetrahydrate product.

[0070] Comparative Example 2

[0071] The only difference between this comparative example and Example 7 is that Antarcticite (purity of calcium chloride hexahydrate is 89%) produced as a byproduct of oilfield brine is directly used and added to the sodium borate solution in step 3. The other steps are the same to obtain calcium hexaborate pentahydrate product.

[0072] Performance characterization:

[0073] See also Figure 1 , which is a comparison diagram of the XRD diffraction pattern of the solid phase of calcium hexaborate tetrahydrate of Example 1 (the red spectrum in the figure) and the XRD diffraction pattern of the standard calcium hexaborate tetrahydrate (the black spectrum in the figure). It can be seen from the figure that the synthetic crystal has strong peaks and secondary strong peaks at diffraction angles of 12.92°, 17.06°, 25.78° and 43°, and each diffraction peak is consistent with the diffraction peak of the standard spectrum, indicating that the synthetic substance is calcium hexaborate tetrahydrate.

[0074] See also Figure 2, which is a comparison of the XRD diffraction pattern of the solid phase of calcium hexaborate pentahydrate of Example 7 (the blue pattern in the figure) and the XRD diffraction pattern of the standard calcium hexaborate pentahydrate (the black pattern in the figure). It can be seen from the figure that the synthetic crystals have strong peaks and secondary strong peaks at diffraction angles 2θ of 10.97°, 21.69° and 32.79°, respectively, and each diffraction peak is consistent with the diffraction peak of the standard spectrum, indicating that the synthetic substance is calcium hexaborate pentahydrate.

[0075] Therefore, the XRD diffraction pattern shows that the calcium chloride hexahydrate tetrahydrate and the calcium chloride hexahydrate pentahydrate can be prepared by controlling the process using the technical solution of the present invention.

[0076] Furthermore, the purity of the calcium hexaborate tetrahydrate or calcium hexaborate pentahydrate prepared in each example was analyzed. The total calcium concentration was determined by the EDTA method, expressed as CaO content; the total boron concentration was determined by the mannitol method, expressed as B2O3. See Table 1 for specific results.

[0077] Table 1 Solid phase composition analysis table of calcium hexaborate tetrahydrate or calcium hexaborate pentahydrate prepared in Examples and Comparative Examples

[0078]

[0079]

[0080] It can be seen from the results in Table 1 that the calcium hexaborate tetrahydrate prepared by Examples 1-6 is close to the theoretical value, wherein when the molar ratio of the recrystallized calcium chloride hexahydrate to the boron in the sodium borate solution is 0.2-1.5:1, the ratio of boron oxide to calcium oxide in the prepared calcium hexaborate tetrahydrate is close to the theoretical ratio, and the purity is high. Preferably, when the molar ratio is 0.4-1.0:1, the purity is higher; more preferably, Example 3 is the best example. Compared with Comparative Example 1, the only difference between Example 1 and Comparative Example 1 is that Example 1 recrystallizes calcium chloride. Obviously, the purity of the prepared calcium hexaborate tetrahydrate product can be significantly improved after recrystallization of calcium chloride using the technical solution of the present invention.

[0081] The calcium hexaborate pentahydrate prepared by the preparation method of Examples 7-10 has a boron oxide to calcium oxide ratio close to the theoretical value when the molar ratio of the recrystallized calcium chloride hexahydrate to the boron in the sodium borate solution is 0.2 to 1.5:1, wherein when the molar ratio of the recrystallized calcium chloride hexahydrate to the boron in the sodium borate solution is 0.4 to 0.8:1, the ratio of the boron oxide to the calcium oxide in the prepared calcium hexaborate pentahydrate is close to the theoretical ratio. Further, the calcium hexaborate pentahydrate obtained in Example 8 is closest to the theoretical ratio and is the best example.

[0082] The only difference between Example 7 and Control Example 2 is that the calcium chloride is recrystallized in Example 7. Obviously, by adopting the technical solution of the present invention, the purity of the prepared calcium hexaborate tetrahydrate product can be significantly improved after the calcium chloride is recrystallized.

[0083] The above are only preferred embodiments of the present invention, which do not limit the protection scope of the present invention. For those skilled in the art, the present invention may have various modifications and changes. Within the spirit and principle of the present invention, changes, modifications, replacements, integrations and parameter changes to these embodiments by conventional substitutions or by being able to achieve the same functions without departing from the principles and spirit of the present invention all fall within the protection scope of the present invention.

Claims

1. A method for preparing calcium hexaborate, characterized in that: Antarcticite, a byproduct of oilfield brine, is mixed with deionized water, heated and stirred, dissolved to obtain a calcium chloride solution, filtered and separated, and then cooled and crystallized to obtain recrystallized calcium chloride hexahydrate; the recrystallized calcium chloride hexahydrate and the sodium borate solution are reacted under stirring conditions in a constant temperature water bath, and the temperature of the constant temperature water bath is adjusted to respectively prepare calcium hexaborate tetrahydrate or calcium hexaborate pentahydrate; The temperature of the heating and stirring process is 25~45°C; The temperature of the cooling crystallization is -25 to -15°C and the time is 12 to 48 hours; The temperature of the constant temperature water bath is adjusted to 25-50° C., and the recrystallized calcium chloride hexahydrate reacts with the sodium borate solution for 3-7 days to obtain the calcium hexaborate tetrahydrate; The temperature of the constant temperature water bath is regulated to be 60-100° C., and the recrystallized calcium chloride hexahydrate reacts with the sodium borate solution for 6-24 hours to obtain the calcium hexaborate pentahydrate.

2. The method for preparing calcium hexaborate according to claim 1, characterized in that: The content of calcium chloride hexahydrate in the Antarcticite is 85-95%.

3. The method for preparing calcium hexaborate according to claim 2, characterized in that: The molar ratio of the oilfield brine byproduct Antarcticite and deionized water is 0.3-0.65:1; the raw material purity of the oilfield brine byproduct calcium chloride hexahydrate is 85-95%.

4. The method for preparing calcium hexaborate according to claim 2, characterized in that: The purity of the recrystallized calcium chloride hexahydrate is ≥99%, and the shape is needle-shaped crystals.

5. The method for preparing calcium hexaborate according to any one of claims 1 to 4, characterized in that: The cooling crystallization is performed 1 to 3 times.

6. The method for preparing calcium hexaborate according to any one of claims 1 to 4, characterized in that: The molar ratio of the recrystallized calcium chloride hexahydrate to the boron in the sodium borate solution is 0.2-1.5:

1.

7. The method for preparing calcium hexaborate according to claim 6, characterized in that: The sodium borate solution is prepared by dissolving boric acid and sodium hydroxide solid in water, and the molar ratio of boric acid to water is 0.02-0.05:

1.

8. The method for preparing calcium hexaborate according to claim 7, characterized in that: The molar ratio of sodium hydroxide solid to boric acid is 0.1-0.3:1.

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