Screening method and application of phosphoric acid product

Abstract

The invention belongs to the technical field of phosphorus chemical industry, and particularly relates to a screening method and application of a phosphoric acid product. The screening method comprises the following steps: obtaining the initial content of phosphorus pentoxide in a phosphoric acid product; obtaining the phosphoric acid product with the mass being the first mass, diluting and removing impurities to obtain diluted phosphoric acid with the mass being the second mass; obtaining the dilution content of phosphorus pentoxide in the dilute phosphoric acid; and calculating the recovery rate of phosphoric acid according to the initial content, the first mass, the second mass and the dilution content, and screening phosphoric acid products with the recovery rate of 95% or above. According to the method, the unqualified phosphoric acid product can be obviously screened, the phosphoric acid product which is excellent in quality and meets the process of a producer is obtained, and equipment damage and cost increase caused by the phosphoric acid product are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphorus chemical industry, and in particular relates to a screening method and application of phosphoric acid products. Background Art

[0002] Phosphoric acid is an important raw material in the organic synthesis industry. After being formulated and refined, phosphoric acid can be used to produce many downstream products, which are suitable for industries such as food, scientific research, electronics and medicine. In particular, phosphoric acid, as one of the raw materials for iron phosphate in the lithium battery positive electrode material manufacturing industry, plays an important role in lithium battery manufacturing; however, commercial phosphoric acid usually contains impurities, and the impurity elements in the dilute phosphoric acid produced interfere with the production process of lithium battery positive electrode materials. Common cation Al 3+ , Ca 2+ Mg 2+ and anion F - The content of impurities such as F - When the content is high, it will also cause corrosion to the production equipment. Therefore, in the existing process, the dilute phosphoric acid needs to be further purified to obtain the dilute phosphoric acid used in production. However, the phosphoric acid on the market is complicated. If the production process is adjusted according to the component content of different phosphoric acid products, it will increase the investment in equipment and costs, and the trial and error cost is high. Summary of the invention

[0003] To solve the above problems, the present invention proposes a method and application for screening phosphoric acid products. The method first screens out phosphoric acid products with good quality and in line with the producer's own process before putting them into production, thereby avoiding equipment damage and cost increase caused by phosphoric acid products.

[0004] The present invention is achieved through the following technical solutions: The first aspect of the present invention provides a method for screening phosphoric acid products, comprising the following steps: Obtaining the initial content of phosphorus pentoxide in the phosphoric acid product; Obtaining the phosphoric acid product of the first quality, diluting and removing impurities, and obtaining dilute phosphoric acid of the second quality; Obtaining the dilution content of phosphorus pentoxide in the dilute phosphoric acid; The recovery rate of phosphoric acid is calculated according to the initial content, the first mass, the second mass and the diluted content, and a phosphoric acid product with a recovery rate of more than 95% is screened.

[0005] In some possible implementations, the method for obtaining the initial content of phosphorus pentoxide in the phosphoric acid product is a weight method, and further a method for determining the phosphoric acid content of 6.3% of industrial phosphoric acid in standard HG / T 4068-2022.

[0006] In some possible implementations, the initial content is greater than 18%.

[0007] In some possible implementations, the initial content is 18% to 25%, and in a demonstration example, it can be 20%.

[0008] In some other possible implementations, the initial content is 25% to 38%, and in the exemplary embodiment, it can be 33%.

[0009] In some other possible implementations, the initial content is 38% to 48%, and in a demonstration example, it can be 40%.

[0010] In some other possible implementations, the initial content is greater than 48%, and in a demonstration example, it can be 50%.

[0011] In some possible implementations, the dilution comprises the following steps: Mixing the phosphoric acid product with water under stirring to obtain diluted phosphoric acid; Wherein, the mass volume ratio of the phosphoric acid product to water is (1.2~1.8)g:1ml.

[0012] In the above-mentioned diluted phosphoric acid product, the diluted phosphoric acid makes the impurity removal reaction more complete and the impurities in the phosphoric acid are easily removed. It should be noted that the stirring method of the diluted phosphoric acid is conventional in the art, and therefore, it is not particularly limited in the present invention.

[0013] In some possible implementations, the impurity removal includes the following steps: Under stirring conditions, alkali solution is added to the phosphoric acid, and the pH value is adjusted and then filtered to obtain the dilute phosphoric acid after impurities are removed.

[0014] In some possible implementations, the stirring rotation speed is 400 r / min~900 r / min.

[0015] In some possible implementations, the alkali solution is added at a rate of 150 d / min to 400 d / min.

[0016] In some possible implementations, the alkaline solution includes at least one of aqueous ammonia, sodium hydroxide solution, and potassium hydroxide solution.

[0017] In some possible implementations, the mass concentration of the alkali solution is 10% to 30%.

[0018] In some possible implementations, the mass concentration of the ammonia water is 10% to 30%.

[0019] In some possible implementations, the mass concentration of the sodium hydroxide solution is 10% to 30%.

[0020] In some possible implementations, the mass concentration of the potassium hydroxide solution is 10% to 30%.

[0021] In some possible implementations, the pH value is 4-6.

[0022] In some possible implementations, the filtering method is Buchner funnel filtration, wherein the pore size of the filter paper is less than 20 μm.

[0023] In some possible implementations, during the impurity removal, the temperature of the diluted phosphoric acid is below 50° C., preferably 20° C. to 40° C. In this case, the endpoint pH is more accurate, the reaction rate is stably controlled, the reaction is more complete, and the precipitation is more stable.

[0024] In some possible implementations, the method for obtaining the content of phosphorus pentoxide in the dilute phosphoric acid is a weight method, and further a method for determining the content of 6.3 phosphoric acid in industrial phosphoric acid in standard HG / T 4068-2022.

[0025] In some possible implementations, the recovery rate calculation model calculates the recovery rate based on the ratio of the mass of phosphorus pentoxide in the second mass of dilute phosphoric acid to the mass of phosphorus pentoxide in the first mass of the phosphoric acid product.

[0026] In some possible implementations, the recovery rate calculation model is:

[0027] Wherein, P is the recovery rate, w1 is the initial content, m1 is the first mass, w2 is the content of phosphorus pentoxide in dilute phosphoric acid, and m2 is the second mass.

[0028] A second aspect of the present invention provides an application of a method for screening phosphoric acid products in the field of lithium battery materials.

[0029] Compared with the prior art, the screening method for phosphoric acid products provided by the present invention has at least the following beneficial technical effects: (1) The method for screening phosphoric acid products provided by the present invention uses the content of phosphorus pentoxide before and after impurity removal of dilute phosphoric acid to calculate the recovery rate, and selects phosphoric acid products with a recovery rate of more than 95%. The higher the recovery rate, the less slag samples are produced, indicating that less phosphoric acid is lost by removing impurities in the phosphoric acid product. The screening method can screen out unqualified phosphoric acid products and obtain phosphoric acid products with good quality and in line with the producer's own process, thereby avoiding equipment damage and cost increase caused by unqualified phosphoric acid products.

[0030] (2) The method for screening phosphoric acid products provided by the present invention comprises selecting at least one of ammonia water, sodium hydroxide solution and potassium hydroxide solution for adjusting the pH value, and these alkaline solutions can promote the 3+ , Ca 2+ Mg 2+ While generating precipitation, no other harmful impurities are introduced. In addition, it can promote the formation of complex complex precipitation between fluoride ions, metal cations and hydroxide ions to remove fluoride ion impurities. The concentration of alkali solution is 10%~30%, which can control the reaction rate and reduce the heat brought by the chemical reaction process, so that it can fully react while ensuring the safety of the experimenter.

[0031] (3) The method for screening phosphoric acid products provided by the present invention adjusts the pH value to 4-6. The precipitate exists stably within this pH value range, which prevents the precipitated impurities from dissolving again and reducing the impurity removal effect.

[0032] (4) The method for screening phosphoric acid products provided by the present invention uses the Büchner funnel to filter so that the liquid passes through the filter paper faster, thereby improving the filtration efficiency; using filter paper with a pore size of less than 20 μm can reduce the accumulation of particles on the surface of the filter paper, reduce the filtration resistance, and further accelerate the filtration speed; and the filter paper with a smaller pore size can more effectively intercept fine solid particles, improve the purity of the filtrate, and thus improve the accuracy of the method for screening phosphoric acid products.

[0033] (5) The method for screening phosphoric acid products provided by the present invention can calculate the recovery rate of phosphoric acid products after they are made into dilute phosphoric acid and impurities are removed. The utilization rate of phosphoric acid in subsequent production of the corresponding phosphoric acid products can be determined by the recovery rate. The utilization rate of phosphoric acid products with low recovery rates in subsequent production is also correspondingly low, and vice versa. Therefore, the quality of phosphoric acid products can be evaluated based on the recovery rate, and phosphoric acid products with excellent quality and in line with the producer's own process can be screened out to avoid equipment damage and cost increase caused by phosphoric acid products.

[0034] (6) In the method for screening phosphoric acid products provided by the present invention, the stirring speed and the rate of adding alkali solution when adjusting the pH value can be fine-tuned according to the amount of precipitate actually generated, thereby improving accuracy. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described and illustrated in conjunction with the embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0036] Obviously, the following descriptions are only some examples or embodiments of the present invention, and for those of ordinary skill in the art, the present invention can also be applied to other similar scenarios without creative work. In addition, it can also be understood that although the efforts made in such a development process may be complex and lengthy, for those of ordinary skill in the art related to the contents disclosed in the present invention, some changes in design, manufacturing or production based on the technical contents disclosed in the present invention are just conventional technical means, and should not be understood as the contents disclosed in the present invention being insufficient.

[0037] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present invention and is not intended to limit the subject matter described in the claims.

[0038] If not otherwise specified, all embodiments and optional embodiments of the present invention may be combined with each other to form a new technical solution, and all technical features and optional technical features of the present invention may be combined with each other to form a new technical solution.

[0039] The term "content" refers to mass fraction.

[0040] Example 1 Example 1 provides a method for screening phosphoric acid products, the steps are as follows: (1) Select phosphoric acid product: Select a phosphoric acid product with a theoretical phosphorus pentoxide content of 20%.

[0041] (2) According to HG / T 4068-2022 Industrial Phosphoric Acid 6.3 Determination of Phosphoric Acid Content - Gravimetric Method (Arbitration Method), obtain the initial content w1 of phosphorus pentoxide in the phosphoric acid product.

[0042] (3) Weigh the phosphoric acid product with a mass of m1 = 260.5 g (200 ml).

[0043] (4) Dilution: Under stirring conditions, dilute the phosphoric acid product in (3) with water in a mass volume ratio of 1.3 g:1 ml (260.5 g is added to about 200 ml or 200 g of water) to obtain diluted phosphoric acid.

[0044] (5) Impurity removal: At 500 r / min and 40°C, add ammonia water with a mass concentration of 18% to the diluted phosphoric acid at a rate of 200 d / min. As the amount of slag increases, gradually increase the speed to 800 r / min. Use a pH meter to measure the pH of the solution and control the pH at the end of the reaction to 4.5. Record the reaction volume of ammonia water as 176 g. Use precipitation reaction to generate aluminum hydroxide, calcium hydroxide, magnesium hydroxide and other precipitates to remove impurities.

[0045] (6) Filtration: Select a filter paper with a pore size of 20 μm, filter the reaction liquid through a Buchner funnel, rinse the filtered residue with pure water and filter it again. Repeat this process three times to obtain a total mass m2 of the filtrate (dilute phosphoric acid).

[0046] (7) According to HG / T 4068-2022 Industrial Phosphoric Acid 6.3 Determination of Phosphoric Acid Content - Gravimetric Method (Arbitration Method), the content of phosphorus pentoxide w2 in the filtrate (dilute phosphoric acid) obtained in step (6) is determined.

[0047] (8) Substitute m1, m2, w1 and w2 into the following recovery rate calculation model to calculate the recovery rate:

[0048] Wherein, P is the recovery rate.

[0049] Example 2 Example 2 proposes a method for screening phosphoric acid products, the steps are basically the same as those in Example 1, except that: In step (1), a phosphoric acid product is selected: a phosphoric acid product having a theoretical phosphorus pentoxide content of 33% is selected.

[0050] In step (3), the mass of the phosphoric acid product m1 = 298.51 g.

[0051] In step (4), the mass volume ratio of the phosphoric acid product and water is 1.5 g:1 ml (298.51 g plus about 200 ml or 200 g of water).

[0052] In step (5), impurity removal: NaOH (aq) with a mass concentration of 25% was added dropwise to the diluted phosphoric acid at 600 r / min and 30° C., and the addition rate was 350 d / min. The pH of the solution was measured using a pH meter, and the pH at the reaction end point was controlled to be 5.0. The reaction volume of NaOH (aq) was recorded as 327 g, and precipitates such as aluminum hydroxide, calcium hydroxide, and magnesium hydroxide were generated by precipitation reaction, and impurities were removed by filtration.

[0053] Example 3 Example 3 proposes a method for screening phosphoric acid products, the steps are basically the same as those in Example 1, except that: In step (1), a phosphoric acid product is selected: a phosphoric acid product having a phosphorus pentoxide content of 40% is selected.

[0054] In step (5), impurity removal: KOH (aq) with a mass concentration of 30% was added dropwise to the diluted phosphoric acid at 450 r / min and 35°C, and the addition rate was 300 d / min. As the amount of slag sample increased, the speed was gradually increased to 900 r / min. At the same time, the pH of the solution was measured using a pH meter, and the pH at the end of the reaction was controlled to be 5.5. The reaction volume of KOH (aq) was recorded as 457 g, and precipitates such as aluminum hydroxide, calcium hydroxide, and magnesium hydroxide were generated by precipitation reaction, and impurities were removed by filtration.

[0055] Example 4 Example 4 proposes a method for screening phosphoric acid products, the steps are basically the same as those in Example 1, except that: In step (1), a phosphoric acid product is selected: a phosphoric acid product having a phosphorus pentoxide content of 50% is selected.

[0056] In step (5), impurity removal: NaOH (aq) with a mass concentration of 20% was added dropwise to the diluted phosphoric acid at 450 r / min and 40° C., and the addition rate was 250 d / min. The pH of the solution was measured using a pH meter, and the pH at the reaction end point was controlled to be 5.0. The reaction volume of NaOH (aq) was recorded as 490 g, and precipitation reaction was used to generate precipitates such as aluminum hydroxide, calcium hydroxide, and magnesium hydroxide to remove impurities.

[0057] In order to verify the progressiveness of a method for screening a phosphoric acid product provided in an embodiment of the present invention, an inductively coupled plasma spectrometer and an ion chromatograph were used to measure the impurity elements before and after impurity removal. The impurity element content before and after impurity removal, the mass of dilute phosphoric acid before impurity removal, the initial content of phosphorus pentoxide in dilute phosphoric acid, the mass of dilute phosphoric acid after impurity removal, the content of phosphorus pentoxide in dilute phosphoric acid after impurity removal, and the recovery rate are shown in Table 1 below.

[0058]

[0059] From Table 1 above, we can at least draw the following conclusions: (1) According to the screening method of phosphoric acid products in the embodiments of the present invention, the recovery rate of dilute phosphoric acid is shown in Table 1. It can be seen from Examples 1 to 4 that the recovery rate of phosphoric acid products with high initial content is not necessarily high. This is because the impurities affect the recovery rate (phosphoric acid lost due to impurities removal), which further reflects that the utilization rate of the phosphoric acid product when it is put into use is not high.

[0060] (2) It can be seen from the F impurity removal in Examples 1 to 4 that the impurity Al 3+ , Ca 2+ Mg2+ High content, except F - The effect is better, because under the condition of pH 4-6, Al 3+ , Ca 2+ Mg 2+ With F - The reaction formed an insoluble coprecipitate.

[0061] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present invention are all included in the technical scope of the present invention. In addition, without departing from the scope of the main purpose of the present invention, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present invention.

Claims

1. A method for screening phosphoric acid products, characterized in that: The steps include: Obtaining the initial content of phosphorus pentoxide in the phosphoric acid product; Obtaining the phosphoric acid product of the first quality, diluting and removing impurities, and obtaining dilute phosphoric acid of the second quality; Obtaining the dilution content of phosphorus pentoxide in the dilute phosphoric acid; The recovery rate of phosphoric acid is calculated according to the initial content, the first mass, the second mass and the diluted content, and a phosphoric acid product with a recovery rate of more than 95% is screened.

2. The method for screening phosphoric acid products according to claim 1, characterized in that: The dilution comprises the following steps: Mixing the phosphoric acid product with water under stirring to obtain diluted phosphoric acid; Wherein, the mass volume ratio of the phosphoric acid product to water is (1.2~1.8)g:1ml.

3. The method for screening phosphoric acid products according to claim 2, characterized in that: The impurity removal comprises the steps of: Under stirring conditions, alkali solution is added to the phosphoric acid, and the pH value is adjusted and then filtered to obtain the dilute phosphoric acid after impurities are removed.

4. The method for screening phosphoric acid products according to claim 3, characterized in that: The alkali solution includes at least one of ammonia water, sodium hydroxide solution and potassium hydroxide solution.

5. The method for screening phosphoric acid products according to claim 4, characterized in that: The stirring speed is 400r / min~900r / min.

6. The method for screening phosphoric acid products according to claim 5, characterized in that: The addition rate of the alkali solution is 150d / min~400d / min.

7. The method for screening phosphoric acid products according to claim 6, characterized in that: The pH value is 4-6.

8. The method for screening phosphoric acid products according to claim 7, characterized in that: In the impurity removal, the temperature of the diluted phosphoric acid is 50° C. or lower.

9. The method for screening phosphoric acid products according to any one of claims 1 to 8, characterized in that: The recovery rate calculation model is to calculate the recovery rate based on the ratio of the mass of phosphorus pentoxide in the second mass of dilute phosphoric acid to the mass of phosphorus pentoxide in the first mass of the phosphoric acid product.

10. Application of the method for screening phosphoric acid products according to any one of claims 1 to 8 in the field of lithium battery materials.

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