Method for detecting content of boric acid in foundry molding sand

Abstract

The invention discloses a method for detecting the content of boric acid in foundry molding sand, which comprises the following steps: covering to-be-detected molding sand with liquid, and heating after stirring; after heating, separating the molding sand from the solution; fixing the volume of the separated solution; and carrying out titration analysis on the solution, and calculating the content of boric acid. The method comprises the following steps: adding deionized water into molding sand to be detected, and stirring under a heating condition to dissolve boric acid out of the molding sand; separating the sand from the boric acid solution by a centrifugal machine; glycerol and boric acid are complexed into a strong acid solution, the price of glycerol is lower than that of mannitol, and compared with hydroxyl groups of mannitol, the activity of multiple hydroxyl groups of glycerol is higher, and the high activity is beneficial to complexing with boric acid to form strong acid. The titration method is adopted for titration, the detection steps are simple, and the boric acid content can be rapidly calculated.

Description

Technical Field

[0001] The invention belongs to the field of detection technology, and in particular relates to a method for detecting the content of boric acid in foundry sand. Background Art

[0002] Boric acid in the molding sand plays a protective role on the casting material and has a bonding effect. The more it contains, the more it is beneficial to protect the alloy. However, too much can easily affect the performance of the molding sand and the quality of the casting. When the boric acid in the sand is baked, it is easy to volatilize, causing the content to decrease, which reduces the protective effect on the casting material. Ensuring the right amount of boric acid is very important to improve the qualified rate of castings. Therefore, accurate detection of the boric acid content in the molding sand is very important for the casting process.

[0003] Since boric acid and molding sand are tightly combined into one, the boric acid and sand must be separated first. However, conventional separation methods cannot separate the boric acid in the molding sand very well. Therefore, this technology must first solve the problem of separating molding sand and boric acid. Boric acid is quantitatively analyzed. The existing detection technology uses mannitol and boric acid to form a strong acid, and titration is used for titration detection. Since mannitol is expensive, it is necessary to use low-cost substances instead of mannitol to form a strong acid with boric acid.

[0004] Existing boric acid detection methods include: 1. Titration method, which requires mannitol, but the disadvantage of this method is that the mannitol used is expensive; 2. Spectrophotometry, which has the disadvantage that it can only detect trace amounts of boric acid and requires the purchase of spectrophotometer equipment, which is costly; 3. Ion chromatography, which has the disadvantage that plasma chromatography is easily interfered by a large number of matrix elements and impurity elements in the detection solution, resulting in poor detection results. In addition, in these three detection methods, boric acid is in the form of a solution, not a solid mixture.

[0005] A patent document with announcement number CN113533461A discloses a method and system for detecting the boric acid content in an electro-galvanizing solution. The method adds mannitol complexing acid to the electro-galvanizing solution and then uses sodium hydroxide to perform titration analysis on the boric acid content. However, this detection method is only applicable to boric acid in a liquid solution, and the mannitol used in the process is relatively expensive.

[0006] Patent document No. CN113514450A discloses a method for detecting boric acid and / or borate, which uses turmeric test paper for detection, but only performs qualitative analysis rather than quantitative analysis on boric acid.

[0007] The patent document with announcement number CN111679016A introduces an ion chromatography detection method for boric acid content, but it is easily affected by the presence of a large amount of collective elements and organic matter in the solution, resulting in spectral interference and inaccurate detection results. Therefore, it is necessary to establish a research method for detecting boric acid content in solid substances. Summary of the invention

[0008] The invention provides a method for detecting the content of boric acid in foundry sand, which solves the technical problems of separating foundry sand from boric acid and reducing the detection cost.

[0009] The present invention is achieved through the following technical solutions.

[0010] The present invention provides a method for detecting the content of boric acid in foundry sand, comprising the following steps:

[0011] S1: Cover the molding sand to be tested with liquid and heat it after stirring;

[0012] S2: After heating, the molding sand and solution are separated;

[0013] S3: adjust the volume of the separated solution;

[0014] S4: Perform titration analysis on the solution and calculate the content of boric acid.

[0015] Preferably, in step S1, the molding sand to be tested is covered with plasma water, and heated at 50-90° C. for 3-6 minutes after stirring.

[0016] Preferably, in step S2, the molding sand and the solution are centrifuged on a separator at a centrifugal speed of 3000-6000 rpm for 2-7 min.

[0017] Preferably, in step S4, glycerol is added to the titration analysis to form an acidic solution, and a phenolphthalein indicator is added.

[0018] Preferably, in step S4, the fixed volume solution is titrated using potassium hydroxide solution.

[0019] Preferably, the concentration of the potassium hydroxide solution is calibrated using potassium hydrogen phthalate, and the calculation formula is:

[0020] C KOH =1000·M 邻 / 204.22 V NaOH ,

[0021] M 邻 is the weight of potassium hydrogen phthalate; V KOH is the volume of potassium hydroxide, in L.

[0022] Preferably, in step S4, the content of boric acid is calculated based on the volume of potassium hydroxide consumed.

[0023] Preferably, the boric acid content calculation formula is:

[0024] H3BO3%=C KOH·V KOH 30.92 / m 硼酸 ,

[0025] C KOH is the concentration of potassium hydroxide, in mol / L; V KOH is the volume of potassium hydroxide consumed, in L; m 硼酸 Weigh the boric acid to be tested in grams.

[0026] The beneficial effects of the present invention are:

[0027] In the method of the present invention, deionized water is added to the molding sand to be tested, and the mixture is stirred under heating conditions to dissolve the boric acid from the molding sand; a centrifuge is used to separate the sand and the boric acid solution; glycerol is used to complex with the boric acid to form a strong acid solution, and glycerol is cheaper than mannitol. Compared with the hydroxyl group of mannitol, the multiple hydroxyl groups of glycerol are more active, and the high activity is conducive to complexing with boric acid to form a strong acid. The titration is performed by titration, and the detection steps are simple, and the boric acid content can be quickly calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0030] Embodiment 1:

[0031] like Figure 1 As shown, a method for detecting the content of boric acid in foundry sand comprises the following steps:

[0032] S1: Cover the molding sand to be tested with plasma water, stir it, and heat it on a hot plate at 80°C for 5 minutes, stirring continuously during heating;

[0033] S2: After heating, the molding sand and solution are centrifuged on a separator at a centrifugal speed of 5000 rpm for 5 min;

[0034] S3: The separated solution is fixed to 250 ml;

[0035] S4: Take 50 ml of the fixed volume solution for titration analysis and calculate the boric acid content.

[0036] In step S4, 5 g of glycerol is added to the titration analysis to form a strong acid solution with a pH of 1.8, and a phenolphthalein indicator is added, and the fixed volume solution is titrated using a potassium hydroxide solution.

[0037] The concentration of the potassium hydroxide solution is calibrated using potassium hydrogen phthalate, and the calculation formula is:

[0038] C KOH =1000·M 邻 / 204.22 V NaOH ,

[0039] M 邻 is the weight of potassium hydrogen phthalate; V KOH is the volume of potassium hydroxide, in L.

[0040] In step S4, the content of boric acid is calculated according to the volume of potassium hydroxide consumed, and the boric acid content calculation formula is:

[0041] H3BO3%=C KOH ·V KOH 30.92 / m 硼酸 ,

[0042] C KOH is the concentration of potassium hydroxide, in mol / L; V KOH is the volume of potassium hydroxide consumed, in L; m 硼酸 Weigh the boric acid to be tested in grams.

[0043] Embodiment 2:

[0044] like Figure 1 As shown, a method for detecting the content of boric acid in foundry sand comprises the following steps:

[0045] S1: Cover the molding sand to be tested with plasma water, stir it, and heat it on a hot plate at 50°C for 3 minutes, stirring continuously during heating;

[0046] S2: After heating, the molding sand and solution are centrifuged on a separator at a centrifugal speed of 3000 rpm for 2 min;

[0047] S3: The separated solution is fixed to 250 ml;

[0048] S4: Take 50 ml of the fixed volume solution for titration analysis and calculate the boric acid content.

[0049] In step S4, 5 g of glycerol is added to the titration analysis to form a strong acid solution with a pH of 2.5, and a phenolphthalein indicator is added, and the fixed volume solution is titrated using a potassium hydroxide solution.

[0050] The concentration of the potassium hydroxide solution is calibrated using potassium hydrogen phthalate, and the calculation formula is:

[0051] C KOH =1000·M 邻 / 204.22 V NaOH ,

[0052] M 邻 is the weight of potassium hydrogen phthalate; V KOH is the volume of potassium hydroxide, in L.

[0053] In step S4, the content of boric acid is calculated according to the volume of potassium hydroxide consumed, and the boric acid content calculation formula is:

[0054] H3BO3%=C KOH ·V KOH 30.92 / m 硼酸 ,

[0055] C KOH is the concentration of potassium hydroxide, in mol / L; V KOH is the volume of potassium hydroxide consumed, in L; m 硼酸 Weigh the boric acid to be tested in grams.

[0056] Embodiment 3:

[0057] like Figure 1 As shown, a method for detecting the content of boric acid in foundry sand comprises the following steps:

[0058] S1: Cover the molding sand to be tested with plasma water, stir it, and heat it on a hot plate at 90°C for 6 minutes, stirring continuously during the heating period;

[0059] S2: After heating, the molding sand and solution are centrifuged on a separator at a centrifugal speed of 6000 rpm for 7 minutes;

[0060] S3: The separated solution is fixed to 250 ml;

[0061] S4: Take 50 ml of the fixed volume solution for titration analysis and calculate the boric acid content.

[0062] In step S4, 5 g of glycerol is added to the titration analysis to form a strong acid solution with a pH of 2.1, and a phenolphthalein indicator is added, and the fixed volume solution is titrated using a potassium hydroxide solution.

[0063] The concentration of the potassium hydroxide solution is calibrated using potassium hydrogen phthalate, and the calculation formula is:

[0064] C KOH =1000·M 邻 / 204.22 V NaOH ,

[0065] M 邻 is the weight of potassium hydrogen phthalate; V KOH is the volume of potassium hydroxide, in L.

[0066] In step S4, the content of boric acid is calculated according to the volume of potassium hydroxide consumed, and the boric acid content calculation formula is:

[0067] H3BO3%=C KOH ·V KOH 30.92 / m 硼酸 ,

[0068] C KOH is the concentration of potassium hydroxide, in mol / L; V KOH is the volume of potassium hydroxide consumed, in L; m 硼酸 Weigh the boric acid to be tested in grams.

Claims

1. A method for detecting the content of boric acid in foundry sand, characterized in that: The following steps are involved: S1: Cover the molding sand to be tested with liquid and heat it after stirring; S2: After heating, the molding sand and solution are separated; S3: adjust the volume of the separated solution; S4: Perform titration analysis on the solution and calculate the content of boric acid.

2. A method for detecting the content of boric acid in foundry sand according to claim 1, characterized in that: In the step S1, the molding sand to be tested is covered with plasma water, and heated at 50-90° C. for 3-6 minutes after stirring.

3. A method for detecting the content of boric acid in foundry sand according to claim 1, characterized in that: In the step S2, the molding sand and the solution are centrifuged on a separator at a centrifugal speed of 3000-6000 rpm for 2-7 minutes.

4. A method for detecting the content of boric acid in foundry sand as claimed in claim 1, characterized in that: In step S4, glycerol is added to the titration analysis to form an acidic solution, and a phenolphthalein indicator is added.

5. A method for detecting the content of boric acid in foundry sand according to claim 1, characterized in that: In the step S4, the fixed volume solution is titrated using potassium hydroxide solution.

6. A method for detecting the content of boric acid in foundry sand as claimed in claim 5, characterized in that: The concentration of the potassium hydroxide solution is calibrated using potassium hydrogen phthalate, and the calculation formula is: C KOH =1000·M 邻 / 204.22·V NaOH , M 邻 is the weight of potassium hydrogen phthalate; V KOH is the volume of potassium hydroxide, in L.

7. A method for detecting the content of boric acid in foundry sand according to claim 1, characterized in that: In step S4, the content of boric acid is calculated based on the volume of potassium hydroxide consumed.

8. A method for detecting the content of boric acid in foundry sand according to claim 7, characterized in that: The boric acid content calculation formula is: H3BO3%=C KOH ·V KOH ·30.92 / m 硼酸 , C KOH is the concentration of potassium hydroxide, in mol / L; V KOH is the volume of potassium hydroxide consumed, in L; m 硼酸 Weigh the boric acid to be tested in grams.

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