Method for comprehensive utilization of ulexite mineral resources

Abstract

The present application relates to the technical field of inorganic chemistry, and particularly relates to a method for comprehensive utilization of sodium borolite mineral resources, which comprises the following steps: taking sodium borolite as raw material, and obtaining boric acid, calcium sulfate hemihydrate and sodium nitrate through a series of coupled processing procedures in a production system, wherein the boric acid meets the quality index of superior product of the national standard boric acid product standard, the purity of the calcium sulfate hemihydrate reaches more than 99%, and the sodium nitrate meets the national standard sodium nitrate product standard. The method has the beneficial effect that the method for comprehensive utilization of sodium borolite mineral resources makes the elements such as boron, calcium, sodium and magnesium in the sodium borolite and the raw materials such as sulfuric acid, sulfate and nitric acid used in the processing enter the products as much as possible, not only makes the sodium borolite mineral resources be fully utilized, but also greatly reduces the discharge of "three wastes" in the production process.

Description

Technical Field

[0001] This invention relates to the field of inorganic chemistry, and in particular to a method for the comprehensive utilization of sodium borate mineral resources. Background Technology

[0002] According to the "China Boric Acid Market Forecast and Investment Strategy Report (2022 Edition)" released by Limu Information Consulting, global boron mining companies are mainly concentrated in Turkey, the United States, Russia, South American countries, and China. Mining companies with global influence include Turkey's Eti Mining Group, the US Borax Company, Argentina's Santa Rita, and Chile's Cummica Borax Company. Among them, Eti Mining Group is the world's largest boron resource mining and production company, producing 900,000 tons of boron annually, accounting for 30%-40% of global production. Its products include boric acid, borax, and boron oxide concentrates.

[0003] my country has 63 boron mines, including 3 large mines, 6 medium-sized mines, and 54 small mines, with an annual output of 616,500 tons (raw ore). There are over 40 boric acid enterprises. Due to resource limitations and production technology, domestic borax and boric acid production enterprises are relatively small in scale. Only 10% of the boric acid industry has a production capacity exceeding 50,000 tons, and the quality of products still lags behind that of foreign countries, requiring the import of high-quality boric acid. The future demand for both the quantity and quality of boric acid products is continuously increasing, and the requirements for comprehensive resource utilization and the treatment of "three wastes" (waste gas, wastewater, and solid waste) are also becoming increasingly stringent. Therefore, it is necessary to develop new boric acid production technologies.

[0004] Sodium borate (NaCa[B3B2O7(OH)4]·6H2O) is a borate mineral with a theoretical composition (w%) of: Na2O 7.65, CaO 13.85, B2O3 42.95, and H2O 35.55. Common sodium borate in nature is a crystalline aggregate, white in color, soluble in hot water, and partially dissolves in cold water after prolonged soaking, forming a paste-like consistency. It is an important mineral resource, found in arid regions, formed by the decomposition of boron in sediments and volcanic debris by water erosion. It is distributed in South America, Turkey, the western United States, and the Qinghai-Tibet Plateau in my country, and is a major ore type in the boron deposits of Qinghai Salt Lake.

[0005] Overview of Sodium Boronite Resource Utilization Technology: Some literature and patent reports disclose technical solutions for preparing calcium borate using sodium borate. For example, Wang Pei et al. used natural sodium borate mineral powder as raw material to prepare calcium borate through hydrothermal depolymerization and phase transformation. The liquid-to-solid volume-to-mass ratio of the reaction system was 250 mL / 100 g, the depolymerization temperature was 120℃, the time was 8 h, the drying temperature was around 200℃, and the sodium oxide mass fraction of the product was below 0.5%, which meets the requirements of the alkali-free glass fiber industry for boron-containing raw materials.

[0006] Numerous researchers have published literature and patents on the production of boric acid from sodium borate. Chinese patent 201310309554.5 discloses a process for preparing boric acid, calcium carbonate, and sodium nitrate by decomposing sodium borate with nitric acid. However, it does not mention technical measures for treating other impurities in the mineral, nor does it address the quality indicators achievable by the obtained product or the key technologies that may arise during the engineering scale-up process. Chinese patent 201610890282.6 relates to a method for preparing boric acid from sodium borate, but it does not address the comprehensive utilization of other chemical components in the sodium borate ore.

[0007] Boron is not only an important mineral resource in sodium borate calcite, but also has significant application value. Due to the complex chemical composition of sodium borate calcite, the utilization of its other chemical components is also gaining importance due to socio-economic development trends such as environmental protection and comprehensive resource utilization. Therefore, it is necessary to continuously optimize the utilization methods of sodium borate calcite based on its varying chemical composition and properties. Summary of the Invention

[0008] The technical problems to be solved by this invention are: first, to make full use of sodium borate mineral resources, significantly reduce the discharge of "three wastes" and achieve green production; second, to optimize the production process of preparing boric acid, calcium sulfate hemihydrate whiskers and calcium nitrate products from sodium borate ore and optimize their coupling; and third, to solve the engineering problems of industrial scale-up to achieve the above objectives.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for comprehensive utilization of sodium borate mineral resources, comprising the following steps:

[0010] 1) The sodium borate ore is pretreated by water washing to obtain washed ore. The decomposition of the washed ore to produce boric acid is completed by two steps of nitric acid hydrolysis.

[0011] The first step is acid hydrolysis, in which the washed ore is added to water at a ratio of 3 to 7 times its weight, and 75% to 85% of the total amount of nitric acid required for decomposing the ore is added. The reaction time is 30 to 60 minutes and the reaction temperature is 70 to 85°C to obtain the first slurry. The solute concentration of the added nitric acid is 50%.

[0012] 2) The first slurry is filtered using a vacuum filter to obtain the first filtrate and solids. The solids are then washed and discharged.

[0013] 3) Add the remaining portion of nitric acid required for acid hydrolysis to the first filtrate to complete the second step of acid hydrolysis. Cool the temperature to 10℃-30℃ to precipitate boric acid crystals.

[0014] 4) Filtration yields boric acid crystals and a second filtrate. The boric acid crystals are washed and dried to obtain the boric acid product.

[0015] 5) The second filtrate reacts with the decalcifying agent to obtain calcium sulfate dihydrate whiskers or calcium sulfate hemihydrate whiskers under different process conditions, and a third filtrate is obtained.

[0016] 6) If Mg in the third filtrate + Concentration reaching 35g / L or Na + When the concentration reaches 40 g / L, the filtrate is concentrated, cooled and crystallized, and filtered to obtain a mixture mainly composed of sodium nitrate and the fourth filtrate.

[0017] 7) Prepare sodium nitrate product from the mixture obtained in step 6);

[0018] 8) If the sodium and magnesium content of the third filtrate in step 5) is not higher than the limit in step 6), you can proceed directly to step 10).

[0019] 10) Repeat steps 1)-8), but before adding nitric acid to the water-washed ore in step 1), the third filtrate is used as the circulating mother liquor. The water-washed ore and the circulating mother liquor are mixed at a mass ratio of 1:(3-8) to replace the water.

[0020] Preferably, in the above-mentioned method for comprehensive utilization of sodium borate ore resources, in step 1), 75% to 85% of the total amount of nitric acid required for decomposing the ore is added, the reaction time is 48 minutes, and the reaction temperature is 80°C to obtain the first slurry.

[0021] Preferably, in the above-mentioned method for comprehensive utilization of sodium borate mineral resources, step 4) of "obtaining boric acid product after washing and drying boric acid crystals" specifically means: the boric acid crystals are washed three times in countercurrent and dried in an oven at 60°C for 2 hours to obtain the boric acid product.

[0022] Preferably, in the above-mentioned method for comprehensive utilization of sodium borate mineral resources, the decalcifying agent in step 5) is one or a mixture of sulfuric acid and sulfate.

[0023] Preferably, in the above-mentioned method for comprehensive utilization of sodium borate mineral resources, the sulfuric acid is a 30%-98% sulfuric acid aqueous solution.

[0024] Preferably, in the above-mentioned method for comprehensive utilization of sodium borate mineral resources, step 7) specifically involves: the obtained mixture being a solid phase with B2O3 content less than 0.25%, which is discharged for the preparation of sodium nitrate products.

[0025] In the above-mentioned method for comprehensive utilization of sodium borate ore resources, the decomposition of sodium borate ore is completed in two steps. In step 2), the obtained slurry can be separated using filtration equipment such as a vacuum filter, and the waste residue is discharged after countercurrent washing. In step 5), the decalcifying agent is sulfuric acid of different concentrations. When the decalcification operation temperature is below 82℃, calcium sulfate dihydrate whiskers are obtained; when the decalcification operation temperature is between 85 and 98℃, calcium sulfate hemihydrate whiskers are obtained.

[0026] In the above-mentioned method for comprehensive utilization of sodium borate ore resources, the material obtained after concentrating the third filtrate from decalcification in step 7) contains less than 0.25% B2O3, and the total amount is small, with a total boron utilization rate of more than 98%. However, since the content of other magnesium and calcium salts is about 3.5%, which does not meet the quality indicators of industrial sodium nitrate products, it is sent out of the system for processing using traditional purification methods.

[0027] The beneficial effects of this invention are as follows: The method for comprehensive utilization of sodium borate ore resources according to this invention has the following advantages:

[0028] 1. The main technical solution is to use sodium borate as raw material and adopt a two-step nitric acid decomposition method to prepare boric acid, which reduces the decomposition temperature and makes the liquid-solid separation of the decomposition slurry very simple, making it easy to achieve large-scale industrial production.

[0029] 2. This invention utilizes nitric acid to decompose sodium borate ore and sulfuric acid as a decalcifying agent. Its functions are: firstly, sulfuric acid removes calcium from the circulating mother liquor; secondly, the calcium sulfate whiskers obtained from this decalcification process are directly produced as a product; and thirdly, the use of sulfuric acid for decalcification simultaneously regenerates nitric acid, saving on nitric acid consumption.

[0030] 3. By reducing the amount of nitric acid added, the formation of nitrates is significantly reduced, which lowers the processing difficulty, energy consumption and production cost, and has a positive effect on reducing boron loss.

[0031] 4. In the comprehensive utilization method of sodium boron calcite ore resources, the solid obtained after concentrating the decalcified filtrate is mainly sodium nitrate, containing about 3.5% of other calcium and magnesium salts, with a B2O3 content of less than 0.25% and a total boron utilization rate of greater than 98%. Discharging this material from the system is beneficial for optimizing the system's continuous operating conditions. After this material is discharged from the system, it can be further processed using traditional and mature methods to obtain sodium nitrate products.

[0032] 5. This invention, within a single production system, through a series of coupled processes, successively yields boric acid and calcium sulfate whisker products with a purity of over 99%. Elements such as boron, calcium, and sodium in the sodium borate ore, as well as raw materials such as sulfuric acid and nitric acid used in this processing method, are all utilized, improving the utilization rate of mineral resources and significantly reducing the emission of waste gas, wastewater, and solid waste. Attached Figure Description

[0033] Figure 1 The diagram shown is a flowchart illustrating the method for comprehensive utilization of sodium borate ore resources according to a specific embodiment of the present invention. Detailed Implementation

[0034] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0035] This invention focuses on the comprehensive utilization of mineral resources and studies key technologies for engineering scale-up and large-scale production. This invention develops a novel decomposition system that utilizes the physicochemical properties of sodium borate to develop a two-step decomposition process, making solid-liquid separation of the slurry after ore decomposition very simple and conducive to industrialization. This invention uses sulfuric acid as a system decalcifying agent, regenerating nitric acid while obtaining high-value hemihydrate calcium sulfate whiskers, reducing nitric acid consumption and sodium nitrate production, optimizing the mother liquor circulation process, and improving boric acid production capacity while reducing process energy consumption.

[0036] This invention reduces the amount of high-value nitric acid used, and makes full use of elements such as boron, calcium, and sodium in minerals, saving production costs and realizing comprehensive resource utilization.

[0037] This invention proposes a series of new process solutions that can be used for large-scale production, aiming to provide a reference for large-scale industrial production.

[0038] Since there are no quality standards for sodium borate ore, targeted solutions are needed for mineral materials with different chemical compositions.

[0039] The sodium borate ore targeted by this invention has the following main composition as shown in Table 1 below (mass percentage, the remainder being impurities, including water of crystallization and attached water).

[0040] Table 1

[0041] <![CDATA[B2O3]]> <![CDATA[Na2O]]> CaO <![CDATA[Cl - ]]> MgO <![CDATA[SiO2]]> <![CDATA[CO2]]> whole water 25～40％ 4～8％ 10～20％ 1～4％ 1～5％ 2～10％ 1～5％ 30～35％

[0042] Please see Figure 1 This invention provides a method for the comprehensive utilization of sodium borate mineral resources, comprising the following steps:

[0043] 1) Wash the sodium borate ore, add water at a mass ratio of 1:(4-8), grind, wash, separate the liquid and solid, discharge the filtrate after treatment, and dry the washed ore for later use;

[0044] Add 75%–85% of the total amount of nitric acid required for decomposition to the washed ore, react for 20–40 minutes, and at a temperature of 60–80°C to obtain the first slurry; the solute concentration of the added nitric acid is 50%.

[0045] The above parameters limit and optimize the acidolysis process of sodium borate ore, controlling the acidolysis reaction to proceed in two steps. First, 75% to 85% nitric acid is added to complete the first step of the decomposition reaction.

[0046] 2) The reaction slurry is separated using a filter to obtain the first filtrate and acid-insoluble matter. The B2O3 content of the acid-insoluble matter is less than 0.25%. After washing, it is discharged from the system. Separation can be achieved using a vacuum filter or other liquid-solid separation equipment. Stepwise acid addition facilitates the liquid-solid separation of the first slurry, allowing acid-insoluble impurities to be easily discharged from the system.

[0047] 3) Add the remaining nitric acid required for decomposition to the first filtrate to complete the second decomposition step. Cool to 10℃-30℃ to obtain boric acid crystals. Cooling crystallization can obtain flaky boric acid crystals that are easy to filter and wash. The amount of nitric acid added in the two steps is controlled by the pH of the system.

[0048] 4) Separate the slurry obtained in step 3) to obtain the second filtrate and solid. After washing and drying, the solid yields boric acid products that meet national standards. Multiple countercurrent washing is used to ensure product quality, and the washing liquid is used in the system.

[0049] 5) The second filtrate reacts with the decalcifying agent. Under controlled conditions, calcium sulfate dihydrate or calcium sulfate hemihydrate whisker products can be obtained. The decalcifying agent is sulfuric acid of different concentrations, and the amount added is 90%-105% of the amount of gypsum generated. Calcium sulfate dihydrate whiskers can be obtained by controlling the reaction temperature below 82℃, while calcium sulfate hemihydrate whiskers can be obtained when the temperature is 85-98℃.

[0050] The slurry was separated to obtain calcium sulfate whiskers and a third filtrate. The whiskers were washed and dried in a countercurrent manner to obtain the calcium sulfate whisker product.

[0051] The filtration and washing of calcium sulfate hemihydrate whiskers should be carried out at a temperature above 95°C.

[0052] 6) Mg in the third filtrate 2+ Concentration reaching 35g / L or Na + When the concentration reaches 40 g / L, the filtrate is concentrated, cooled, and then separated to obtain a material mainly composed of sodium nitrate and a fourth filtrate.

[0053] 7) The material obtained in step 6) is mainly sodium nitrate, containing small amounts of calcium and magnesium salts of sulfuric acid, hydrochloric acid and boric acid. After deep separation of the liquid, it is sent out of the system and purified using well-known mature technology to prepare sodium nitrate products, thus completing the comprehensive utilization of this mineral resource.

[0054] 8) If the calcium and magnesium content of the filtrate is not higher than the limit in step 6), then you can proceed directly to the next step;

[0055] 9) The third filtrate is used as mother liquor and decomposed minerals at a mineral liquor mass ratio of 1:(3-8) for recycling.

[0056] Each washing step utilizes counter-current washing, preventing the wastewater from being discharged, thus reducing water consumption, avoiding pollution, and improving the comprehensive utilization of resources.

[0057] Example 1

[0058] A method for comprehensive utilization of sodium borate ore resources includes the following steps:

[0059] The composition of sodium borate ore is shown in Table 2 below (dry basis mass percentage, the remainder being impurities, including water of crystallization).

[0060] Table 2

[0061] <![CDATA[B2O3]]> <![CDATA[Na2O]]> CaO Cl- <![CDATA[SiO2]]> MgO <![CDATA[CO2]]> water 30％ 6％ 15％ 1.5％ 5％ 2.5％ 10％ 28％

[0062] 1) Take 100 grams of sodium borate ore, add 500 grams of tap water, grind, wash, filter, separate liquid and solid, discharge the filtrate after treatment, and dry the washed ore at 50℃ for later use.

[0063] 2) The pretreated ore is added to 500g of tap water, and 36g of 50% nitric acid is gradually added. The temperature is raised to 85℃, and the reaction is carried out for 48 minutes to obtain the first slurry. The total amount of nitric acid required in this embodiment is the amount required for all calcium, magnesium, sodium, and other ions in the water-washed ore reaction material to be converted into nitrates, calculated based on the actual chemical composition of the material. The chemical composition of minerals in nature is quite complex, especially since the composition of minerals from different origins varies greatly. Nitric acid decomposes other components in the minerals while decomposing borates to produce boric acid. The total amount of nitric acid required can only be obtained experimentally based on different minerals. In this specific embodiment, 46g of 50% nitric acid is required for every 100g of boron ore.

[0064] 3) The first slurry was separated by vacuum filtration to obtain the first filtrate and acid-insoluble matter. The acid-insoluble matter was discharged from the system after being washed and dried three times by countercurrent. Its mass was 3.1 grams and it contained 0.13% B2O3.

[0065] 4) Add 10 grams of 50% nitric acid to the first filtrate while stirring and cool to 10°C to allow crystallization.

[0066] 5) Boric acid crystals and a second filtrate were obtained by vacuum filtration. The boric acid crystals were washed three times by countercurrent and dried in an oven at 60°C for 2 hours to obtain 31 grams of boric acid product.

[0067] 6) At room temperature, the second filtrate was added dropwise to 83 g of 30% dilute sulfuric acid for decalcification treatment for 30 min. Then, the third filtrate and calcium sulfate dihydrate whiskers were obtained by vacuum filtration. The whiskers were washed three times by countercurrent and dried in an oven at 60℃ for 2 hours to obtain 42 g of calcium sulfate dihydrate whisker product, of which the B2O3 content was 0.41%.

[0068] 7) The third filtrate is mixed with fresh washed ore and acid is added for decomposition.

[0069] Example 2

[0070] A method for comprehensive utilization of sodium borate ore resources includes the following steps:

[0071] 1) Take 100g of water-washed and dried ore, add it to 500g of the third filtrate from Example 1, and gradually add 13.6g of 36g of 50% nitric acid. Heat the mixture to 80°C and react for 40min.

[0072] 2) The above slurry was separated by vacuum filtration to obtain the first filtrate and acid-insoluble matter. The acid-insoluble matter was discharged from the system after one washing and drying. Its mass was 3.5 grams and its B2O3 content was 0.11%.

[0073] 3) Add 3.8 g of 36 g of 50% nitric acid to the first filtrate while stirring, cool to 10°C, and allow it to cool and crystallize to precipitate boric acid crystals.

[0074] 5) Boric acid crystals and a second filtrate were obtained by vacuum filtration; the boric acid crystals were washed three times by countercurrent and dried in an oven at 60°C for 2 hours to obtain 49 grams of boric acid product.

[0075] 6) At room temperature, the second filtrate was added to 80 g of 30% sulfuric acid for decalcification reaction for 30 min. Then, the slurry was filtered by a vacuum filter to obtain the third filtrate and calcium sulfate dihydrate whiskers. The whiskers were washed three times in countercurrent and dried in an oven at 60℃ for 2 hours to obtain 42.2 g of calcium sulfate dihydrate whisker product, of which the B2O3 content was 0.048%.

[0076] 7) The third filtrate is used to decompose the newly entered washed ore.

[0077] Example 3

[0078] A method for comprehensive utilization of sodium borate ore resources includes the following steps:

[0079] 1) Take 100 grams of water-washed and dried ore and add it to the third filtrate of Example 2. Gradually add 13.6 grams of 36 grams of 50% nitric acid, heat to 80°C, and react for 60 minutes.

[0080] 2) The above slurry was separated by vacuum filtration to obtain the first filtrate and acid-insoluble matter. The acid-insoluble matter was discharged from the system after one washing and drying. Its mass was 3.6 grams and its B2O3 content was 0.098%.

[0081] 3) Add 3.8 g of 50% nitric acid to the first filtrate while stirring, cool to 10°C, and allow it to cool and crystallize to precipitate boric acid crystals.

[0082] 4) Boric acid crystals and a second filtrate were obtained by vacuum filtration. The boric acid crystals were washed three times by countercurrent and dried in an oven at 60°C for 2 hours to obtain 52 grams of boric acid product, of which the B2O3 content was 56.10%.

[0083] 5) The second filtrate was added to 88.8 g of 30% sulfuric acid and heated to 90-95°C for 30 min to obtain calcium sulfate hemihydrate whiskers.

[0084] 6) The slurry from step 5) was filtered using a vacuum filter to obtain the third filtrate and calcium sulfate hemihydrate whiskers. The whiskers were washed three times in countercurrent and dried in an oven at 60°C for 2 hours to obtain the calcium sulfate hemihydrate whisker product, in which the B2O3 content was 0.052%.

[0085] 7) The third filtrate is used to decompose the newly entered washed ore.

[0086] Purification of circulating fluid

[0087] 1) In the embodiment, the third filtrate is continuously recycled for the decomposition of new minerals. To ensure the quality of boric acid, when Mg in any second filtrate is... 2+ Concentrations reaching 35 g / L or Na + When the concentration reaches 40 g / L, the filtrate is heated to 90-95°C, and saturated sodium sulfate solution is added according to the measured amount to generate calcium sulfate hemihydrate whiskers.

[0088] 2) The whisker filtrate was concentrated to 50% of its volume, cooled, and crystallized to obtain the fourth filtrate and 4.3 g of white dry solid. The test results are shown in Table 3 (w%).

[0089] Table 3

[0090] Ca <![CDATA[SO4 2- ]]> MgO <![CDATA[B2O3]]> Na <![CDATA[Cl - ]]> <![CDATA[NO3 - ]]> water 1.38 1.18 0.18 0.93 23.45 0.67 61.95 9

[0091] 3) The fourth filtrate is used to decompose new minerals and is recycled.

[0092] In the above-mentioned method for the comprehensive utilization of sodium boron calcite resources, the entire boron ore processing process, except for the wastewater from washing the ore with clean water at room temperature in step one, which is treated to meet the standards before being discharged, has no other wastewater discharge.

[0093] B2O3 loss rate: (total boron discharged from the system) × 100 / total boron entering the system;

[0094] The B2O3 loss rates in the above embodiments are shown in Table 4.

[0095] Table 4

[0096] Example 1 Example 2 Example 3 Circulating fluid purification <![CDATA[Loss rate of B2O3]]> 0.07％ 0.08％ 0.08％ 0.04％

[0097] The technical solution of this invention has a low B2O3 loss rate, and elements such as boron, calcium, and sodium in sodium borate ore, as well as raw materials such as sulfuric acid and nitric acid used in the processing of this solution, are incorporated into the product as much as possible, thereby improving the utilization rate of mineral resources and significantly reducing the emission of "three wastes" (waste gas, wastewater, and solid waste). The above description is merely an embodiment of this invention and does not limit the patent scope of this invention. Any equivalent modifications made based on the description and drawings of this invention, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of this invention.

Claims

1. A method for comprehensive utilization of sodium borate ore resources, characterized in that, Includes the following steps: 1) The sodium borate ore is pretreated by water washing to obtain washed ore. The decomposition of the washed ore to produce boric acid is completed by two steps of nitric acid hydrolysis. The first step, acid hydrolysis, involves adding 3 to 7 times its weight of water to the washed ore, along with 75% to 85% of the total amount of nitric acid required for ore decomposition. The reaction time is 48 minutes, and the reaction temperature is 80°C, yielding the first slurry. The solute concentration of the added nitric acid is 50%. 2) The first slurry is filtered using a vacuum filter to obtain the first filtrate and solids. The solids are then washed and discharged. 3) Add the remaining nitric acid required for acid hydrolysis to the first filtrate to complete the second step of acid hydrolysis. Cool the temperature to 10℃-30℃ to precipitate boric acid crystals. 4) Filtration yields boric acid crystals and a second filtrate. The boric acid crystals are washed and dried to obtain the boric acid product. 5) The second filtrate reacts with the decalcifying agent to obtain calcium sulfate dihydrate whiskers or calcium sulfate hemihydrate whiskers under different process conditions, and a third filtrate is obtained. 6) If Mg in the third filtrate 2+ Concentration reaching 35g / L or Na + When the concentration reaches 40 g / L, the filtrate is concentrated, cooled and crystallized, and filtered to obtain a mixture mainly composed of sodium nitrate and the fourth filtrate. 7) Prepare sodium nitrate product from the mixture obtained in step 6); 8) If the sodium and magnesium contents of the third filtrate in step 5) are not higher than the limits in step 6), you can proceed directly to step 9). 9) Repeat steps 1)-8), but before adding nitric acid to the water-washed ore in step 1), the third filtrate is used as the circulating mother liquor. The water-washed ore and the circulating mother liquor are mixed at a mass ratio of 1:(3-8) to replace the water mixture. The specific steps of step 4) "washing and drying boric acid crystals to obtain boric acid product" are as follows: the boric acid crystals are washed three times in countercurrent and then dried in an oven at 60°C for 2 hours to obtain the boric acid product. The decalcifying agent in step 5) is sulfuric acid.

2. The method for comprehensive utilization of sodium borate ore resources according to claim 1, characterized in that, The sulfuric acid is a 30%-98% aqueous solution of sulfuric acid.

3. The method for comprehensive utilization of sodium borate ore resources according to claim 1, characterized in that, Step 7) specifically involves: the resulting mixture being a solid with less than 0.25% B2O3, which is then discharged for the preparation of sodium nitrate products.

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