Preparation method of disodium octaborate tetrahydrate

Abstract

The invention discloses a preparation method of disodium octaborate tetrahydrate, and belongs to the field of chemical engineering. The method comprises the following steps: (1) preparing raw materials, namely respectively grinding boric acid with the purity of more than or equal to 99.5% and borax pentahydrate with the purity of more than or equal to 99% until the particle size is less than or equal to 50 microns; (2) dissolving ingredients; (3) reaction: firstly adding boric acid into the reaction kettle at the temperature of 75 DEG C, stirring and dissolving, then adding borax pentahydrate, heating to 100-105 DEG C, keeping slight boiling, and continuously stirring and reacting for 30 minutes; (4) solid-liquid separation: after the reaction is finished, filtering to remove insoluble substances to obtain a clear reaction solution; and (5) multi-stage drying. According to the invention, through accurate proportioning proportion control and strict raw material pretreatment, the mass ratio of boric acid to borax pentahydrate is ensured to be within a reasonable range, and the purity (greater than or equal to 99.5%) and the boron content stability (20.5 + / -0.5%) of the disodium octaborate tetrahydrate product are significantly improved. Meanwhile, a multi-stage drying technology is adopted, so that the problem of product caking is effectively avoided, the particle size distribution is uniform, and the strict requirements of high-end agricultural and industrial application are met.

Description

TECHNICAL FIELD

[0001] The application relates to the chemical industry, in particular to a preparation method of disodium octaborate tetrahydrate. BACKGROUND

[0002] Disodium octaborate tetrahydrate is an important borate compound and is widely used in agriculture, wood protection, industrial fire retardation, corrosion prevention and other fields. In agriculture, as a high-efficiency instant boron fertilizer, it can effectively supplement the lack of boron elements in the soil, promote crop growth and increase yield. About 60% of the cultivated land in China has soil boron deficiency, and the demand for high-quality boron fertilizer is increasing.

[0003] The existing disodium octaborate tetrahydrate production process usually adopts the reaction of boric acid and borax pentahydrate, and the process mainly includes the steps of raw material batching, heating reaction, drying and molding. However, the existing technology has the following disadvantages: most production processes lack scientific and precise batching ratio data support, resulting in large fluctuations in product purity, and it is difficult to stably control the boron content in the ideal range (20.0%-21.3%), which affects the product quality. Key process parameters such as reaction temperature, solution density and drying temperature lack systematic optimization, resulting in low reaction efficiency, high energy consumption, long production cycle and low production efficiency. The traditional drying method is easy to cause material caking, the processing process is complex, the solubility and uniformity of the product are reduced, and the continuity and stability of production are affected. The detection methods for product purity, moisture content and particle size in the existing technology are not standardized, and there is a lack of standardized detection process, which makes it difficult to ensure the consistency and stability between product batches.

[0004] Therefore, the existing technology cannot meet the demand of modern agriculture and industry for high-purity, high-stability and high-efficiency disodium octaborate tetrahydrate products, and it is urgent to develop a scientific and reasonable production process with simple operation and high production efficiency to overcome the above technical defects and improve the product quality and production efficiency. SUMMARY

[0005] The application aims to provide a preparation method of disodium octaborate tetrahydrate to solve the problems in the background art: most production processes lack scientific and precise batching ratio data support, resulting in large fluctuations in product purity, and it is difficult to stably control the boron content in the ideal range (20.0%-21.3%), which affects the product quality. Key process parameters such as reaction temperature, solution density and drying temperature lack systematic optimization, resulting in low reaction efficiency, high energy consumption, long production cycle and low production efficiency. The traditional drying method is easy to cause material caking, the processing process is complex, the solubility and uniformity of the product are reduced, and the continuity and stability of production are affected. The detection methods for product purity, moisture content and particle size in the existing technology are not standardized, and there is a lack of standardized detection process, which makes it difficult to ensure the consistency and stability between product batches.

[0006] Technical solution: A preparation method of disodium octaborate tetrahydrate, comprising the following steps: (1) Raw material preparation: select boracic acid with purity ≥ 99.5% and borax pentahydrate with purity ≥ 99%, and grind them to particle size ≤ 50 μm respectively; (2) Preparation and dissolution: weigh raw materials according to the mass ratio of boracic acid to borax pentahydrate 0.80-0.90:1, and add them into deionized water to prepare a solution with density 1.45-1.50 g / cm 3 ; (3) Reaction: first, add boracic acid into a reaction kettle at 75 ℃ to be dissolved by stirring, then add borax pentahydrate, increase the temperature to 100-105 ℃ and keep it slightly boiling, and continuously stir for 30 minutes; (4) Solid-liquid separation: after the reaction, remove the insoluble substances by filtration to obtain a clear reaction liquid; (5) Multi-stage drying: a) spray dry the reaction liquid, the atomization pressure is 0.8-1.0 MPa, the inlet air temperature is 130-200 ℃, the outlet air temperature is 95-120 ℃, so that the moisture content is reduced to ≤ 1%; b) send the spray-dried material into a tray dryer, the hot water temperature is 95-98 ℃, the rake speed and the residence time are controlled, so that the moisture content of the final product is ≤ 0.1%; (6) Detection and packaging: detect the product purity, boron content, particle size and moisture content, and package the finished product after passing the test; Among them, the product purity is ≥ 99.5%, the boron content is 20.5 ± 0.5%, the 325 mesh residue is ≤ 0.5%, and the pH of 1% aqueous solution is 8.0-9.5.

[0007] Preferably, the mass ratio of boracic acid to borax pentahydrate is 0.853187:1.

[0008] Preferably, the grinding is carried out by using a maroon ball mill to prevent the introduction of metal impurities.

[0009] Preferably, after the solution preparation is completed, it is filtered through a 5 μm precision filter to remove fine suspended particles.

[0010] Preferably, the atomization particle size is controlled at 50-100 μm during the spray drying process to ensure the uniformity and solubility of the particles.

[0011] Preferably, the rake speed of the tray dryer is 3-8 rpm.

[0012] Preferably, the reaction process can be carried out at a pressure of 0.15 MPa, and the reaction temperature is increased to 115 ℃ to shorten the reaction time.

[0013] Preferably, the borax pentahydrate can be replaced by borax decahydrate, and heated to remove part of the crystal water before the reaction.

[0014] Preferably, the boron content is detected by ICP-MS method.

[0015] Compared with the prior art, the present application has the following advantages: (1) The present application controls the precise proportion of ingredients and strictly pretreats the raw materials to ensure that the mass ratio of boric acid to borax pentahydrate is within a reasonable range, thereby significantly improving the purity (≥99.5%) and boron content stability (20.5±0.5%) of the product.

[0016] (2) The present application controls the reaction temperature and adopts a multi-stage drying process combining spray drying and disc drying, thereby significantly shortening the production cycle (4-5 hours) and saving more than 50% of the time compared with the traditional process, thereby improving the production capacity and response speed of the production line.

[0017] (3) The present application optimizes the reaction process and drying parameters, realizes a distillation water recycling rate of ≥80%, reduces the grinding process and energy waste in multi-stage drying, and reduces the overall energy consumption by 20-25%, thereby reducing production costs and improving economic benefits.

[0018] (4) The present application establishes a standardized ingredient and detection system, strictly controls key process parameters, and ensures that the purity deviation of different batches of products does not exceed 0.3%, thereby significantly improving the consistency and reliability of the product and meeting the market demand for high-quality boron fertilizer and industrial materials.

[0019] (5) The present application provides flexible process adjustment schemes for different raw materials (such as borax pentahydrate and borax decahydrate) and drying equipment (disc drying and fluidized bed drying), which is convenient for adapting to different production conditions and raw material supply, and has strong popularization and application value. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the preparation method of the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] Example, please refer to Figure 1 Example 1 Take 100 mL of deionized water (26°C, mass 99.68 g), first add boric acid 50.6428 g (purity ≥ 99.5%, particle size ≤ 50 μm) when heated to 75°C, completely dissolved, then add borax pentahydrate 59.3572 g (purity ≥ 99%, particle size ≤ 50 μm), total amount of 110 g. The temperature is raised to 96-100°C, and the solution density is about 1.45 g / cm 3 , keep stirring until the solution is clear. At this time, the solution is saturated, the content of disodium octaborate tetrahydrate is about 40.124% of the solution mass ratio, and the total water content after reaction is 59.876%. The reaction solution is filtered through a 5 μm precision filter, enters the spray drying tower (atomization pressure 0.9 MPa, inlet air temperature 150°C, outlet air temperature 105°C), and is dried to moisture ≤1%; then it is sent to a disc dryer (hot water temperature 96°C, rake speed 5 rpm), and is dried again to moisture ≤0.1%, and is packaged after cooling to 40°C. The product purity is 99.52%, the boron content is 20.5%, and the 325 mesh residue is 0.4%.

[0023] Example 2 In a 10 m 3 L feeding kettle (effective volume 9 m 3 , built-in coil 0.714 m 3 ), add 6.2143 tons of deionized water, heat to 75°C, then add boric acid 3.1471 tons and borax pentahydrate 3.6886 tons in turn, raise the temperature to 102°C, and keep the temperature for 30 minutes. The reaction solution is filtered through a 5 μm filter, then spray dried (atomization pressure 0.85 MPa, inlet air temperature 160°C, outlet air temperature 110°C), and then disc dried (hot water 97°C, rake speed 4 rpm). The final product moisture is ≤0.1%, the purity is 99.53%, the boron content is 20.52%, and the production cycle is 4.5 hours.

[0024] Example 3 In the same reaction kettle, add 6.01 tons of deionized water, heat to 75°C, then add boric acid 3.4484 tons and borax pentahydrate 4.0418 tons in turn, raise the temperature to 103°C, and keep the temperature for 28 minutes. The drying conditions are the same as in Example 2. The product purity is 99.55%, the boron content is 20.48%, and the yield is increased by 3.4% under the condition of specific gravity 1.45.

[0025] Comparative Example 1 Under the condition of density 1.387 g / cm 3 , add water 5.554 tons, boric acid 3.208 tons, and borax pentahydrate 3.722 tons, reaction temperature 102°C, other conditions same as Example 2. The product purity is 98.5%, the boron content is 20.0%, the 325 mesh residue is 1.2%, and obvious clumping occurs.

[0026] Comparative Example 2 Density 1.387 g / cm 3 , the standard ratio of ingredients (0.853187:1), the reaction temperature was 102°C, and the drying conditions were the same. The product purity was 98.9%, the boron content was 20.1%, and the risk of caking increased.

[0027] Comparative Example 3 The standard ratio (density 1.45 g / cm 3 ), the reaction temperature was reduced to 95°C (normal pressure), the reaction time was extended to 45 minutes, and the other conditions were the same as in Example 2. The product purity was 98.8%, the boron content was 20.1%, the particles were uneven, and the dissolution rate was reduced by 15%.

[0028] Experiment 1: Laboratory solubility and ratio experiment Experimental procedure 1. Take 100 mL of deionized water (room temperature 26°C, mass 99.68 g) in a 250 mL beaker, place it on a constant temperature heating magnetic stirrer, and keep the heating speed at 2°C / min.

[0029] 2. When the water temperature rises to the target temperature (70°C, 80°C, 90°C, 96°C, 100°C, 104°C, 110°C, etc.), slowly add the pre-weighed mixture of boric acid and borax pentahydrate (mixed uniformly according to the set ratio), stirring while adding until completely dissolved.

[0030] 3. Record the total mass of the charge, the volume of the solution, the relative density, the mass percentage of water in the solution after the reaction, and observe the appearance of the solution (whether there is a flip, sticky, sticky glass rod or boiling phenomenon).

[0031] 4. Repeat the experiment 2 times at each temperature point to ensure accurate data, the results are shown in Table 1.

[0032]

[0033] Table 1: Solubility and yield data at different temperatures under laboratory conditions Experiment 2: Flip temperature and charge amount correction experiment 1. According to the optimal dissolution state of each temperature point in Table 1, select a temperature close to the saturated solution state as the starting temperature (96°C, 98°C, 96°C).

[0034] 2. Keep the stirring speed unchanged, slowly add the mixed boric acid and borax pentahydrate to the solution, and observe the solution state while adding. When obvious flip phenomenon (solution surface forms vortex-shaped bubbles) appears, record the temperature and total mass of the charge immediately.

[0035] 3. Continue to feed until boiling, record the boiling temperature and the final feed mass.

[0036] 4. Measure the solution specific gravity, and correct the feed mass according to the specific gravity data, calculate the safe and stable feed ratio, the results are shown in Table 2.

[0037]

[0038] Table 2: Turnover temperature and feed mass correction data Experiment 3: Comparative experiment According to the data of the comparative examples, the results are shown in Table 3.

[0039]

[0040] Table 3 The above shows and describes the basic principles, main features and advantages of the present application; those skilled in the art should understand that the present application is not limited by the above examples, the above examples and descriptions described in the specification are only preferred examples of the present application, and are not used to limit the present application, various changes and improvements of the present application can be made without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application; the scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing disodium octaborate tetrahydrate, characterized by, The method comprises the following steps: (1) Raw material preparation: select boric acid with purity ≥99.5% and borax pentahydrate with purity ≥99%, and grind them to particle size ≤50μm respectively; (2) batching and dissolving: raw materials are weighed according to the mass ratio of boric acid to borax pentahydrate of 0.80-0.90:1, and then added into deionized water to prepare a solution with a density of 1.45-1.50 g / cm 3 ; (3) Reaction: first, dissolve the boric acid in the reaction kettle at 75℃, then add the borax pentahydrate, heat to 100-105℃ and keep it slightly boiling, and continue stirring for 30 minutes; (4) Solid-liquid separation: after the reaction, remove the insoluble substances by filtration to obtain the clear reaction liquid; (5) Multi-stage drying: a) spray dry the reaction liquid, atomization pressure 0.8-1.0MPa, inlet temperature 130-200℃, outlet temperature 95-120℃, so that the moisture content is ≤1%; b) send the spray-dried material into a tray dryer, hot water temperature 95-98℃, control the rake speed and residence time, so that the final product moisture content is ≤0.1%; (6) Detection and packaging: detect the product purity, boron content, particle size and moisture content, and package the finished product after passing the test; The product purity is ≥99.5%, the boron content is 20.5±0.5%, the 325 mesh residue is ≤0.5%, and the 1% aqueous solution pH is 8.0-9.

5.

2. The method for preparing disodium octaborate tetrahydrate according to claim 1, characterized in that, The mass ratio of the boric acid to the borax pentahydrate is 0.853187:

1.

3. The method for preparing disodium octaborate tetrahydrate according to claim 1, characterized in that, The grinding is performed by using a maroon ball mill to prevent the introduction of metal impurities.

4. The method for preparing disodium octaborate tetrahydrate according to claim 1, characterized in that, After the solution preparation, perform 5μm precision filtration to remove fine suspended particles.

5. The method for preparing disodium octaborate tetrahydrate according to claim 1, characterized in that, During the spray drying process, control the atomization particle size at 50-100μm to ensure the uniformity and solubility of the particles.

6. The method for preparing disodium octaborate tetrahydrate according to claim 1, characterized in that, The rake speed of the tray dryer is 3-8rpm.

7. The method for preparing disodium octaborate tetrahydrate according to claim 1, characterized in that, The reaction process can be performed at 0.15MPa, and the reaction temperature is increased to 115℃ to shorten the reaction time.

8. The method for preparing disodium octaborate tetrahydrate according to claim 1, characterized in that, The borax pentahydrate can be replaced by borax decahydrate, and part of the crystal water is removed by heating before the reaction.

9. The method for preparing disodium octaborate tetrahydrate according to claim 1, characterized in that, The boron content detection is performed by using ICP-MS method.

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