Method for detecting content of zinc element in zinc ingot and zinc alloy

Abstract

The invention discloses a method for detecting the content of a zinc element in a zinc ingot and a zinc alloy, which comprises the following steps: dissolving a sample with acid liquor, sequentially adding solid ammonium chloride, ammonia water and ammonium persulfate, adding water for boiling, filtering and collecting precipitate and filtrate; washing the precipitate with ammonium chloride, boiling and fixing the volume to obtain a washed solution; mixing the washed solution with the filtrate, sequentially adding sodium fluoride, ascorbic acid and a dimethyl phenol orange indicator, and adjusting the solution to be pink from yellow by using hydrochloric acid and ammonia water; neutralizing with sulfuric acid until the solution is changed from pink to yellow; in the presence of a buffer solution, titrating with a thiourea saturated solution until the solution is converted from yellow to pink, and then titrating with an EDTA standard solution until the solution is converted from pink to luminous yellow; and calculating the content of the zinc element in the sample. According to the method, the content of the zinc element in the zinc and the zinc alloy can be accurately, simply and conveniently measured.

Description

Technical Field

[0001] The invention relates to the technical field of materials and metallurgy, and more specifically, to a method for detecting the content of zinc in zinc ingots and zinc alloys. Background Art

[0002] At present, the commonly used detection methods for determining zinc content all have the problem of narrow detection range. For example, the Chinese patent application number 201810431970.5 discloses a method for determining cadmium, copper, palladium and zinc elements in Au82Ni alloy, in which the detection range is 0.001%-0.5%. And the current detection method is not suitable for the determination of zinc content in zinc and zinc alloys. The conventional standard method is complicated to operate, has a narrow detection range, cannot exclude interfering ions, and is not suitable for the detection and analysis of zinc and zinc alloys. At the same time, zinc alloys or zinc ingots contain iron, aluminum, manganese and other elements that interfere with the titration endpoint, resulting in large deviations in the results.

[0003] Therefore, there is an urgent need to find an accurate and simple detection method to determine the zinc content in zinc and zinc alloys. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a method for detecting the content of zinc in zinc ingots and zinc alloys. First, the interfering elements in zinc and zinc alloys are removed or masked, and then EDTA standard solution is used as a titrant and dimethylphenol orange is used as an indicator, so as to achieve accurate and simple determination of the content of zinc in zinc and zinc alloys.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for detecting the zinc content in zinc ingots and zinc alloys comprises the following steps:

[0007] (1) After the sample is dissolved in acid solution, solid ammonium chloride, ammonia water and ammonium persulfate are added in sequence, water is added and boiled, and the precipitate and filtrate are collected by filtration;

[0008] (2) washing the precipitate with ammonium chloride at 50° C. to 60° C., and obtaining a washed solution after boiling and constant volume;

[0009] (3) combining the washed solution with the filtrate, adding sodium fluoride, ascorbic acid and dimethylphenol orange indicator in sequence, and adjusting the solution from yellow to pink using hydrochloric acid and ammonia water;

[0010] (4) neutralizing with sulfuric acid until the solution in step (3) changes from pink to yellow;

[0011] (5) in the presence of a buffer solution, titrating with a saturated thiourea solution until the solution in step (4) changes from yellow to pink, and then titrating with an EDTA standard solution until the solution changes from pink to bright yellow as the end point;

[0012] (6) Calculate the zinc content C in the sample zn :

[0013]

[0014] Among them, C EDTA : molar concentration of EDTA, mol / L; V: volume of EDTA standard solution consumed by the titration solution, ml; m: sample weight, g.

[0015] Optionally, in step (1), the acid solution is hydrochloric acid.

[0016] Optionally, the step (1) comprises the following steps: placing 0.1 g to 0.2 g of the sample in a 400 ml beaker, adding 10 ml to 15 ml of hydrochloric acid and mixing, heating to 240° C. to 300° C. to completely dissolve, removing the sample and rinsing the cup wall with 50 ml to 60 ml of water to convert the solid zinc into a solution state; adding 5 g to 10 g of solid ammonium chloride to the resulting solution, neutralizing it with ammonia water until the precipitation is complete and then adding an excess of 10 ml to 20 ml, then adding 0.5 g to 1.0 g of ammonium persulfate, diluting it to 100 ml with water and boiling it to destroy the ammonium persulfate, removing the sample, and collecting the precipitate and filtrate by filtering with quick filter paper while hot.

[0017] Optionally, in step (2), the mass concentration of ammonium chloride is 2%; the number of washings is 5 to 6 times; and the volume is fixed to 120 ml.

[0018] Optionally, step (3) includes the following steps: adding 0.5 g to 1.0 g of sodium fluoride and 0.1 g to 0.2 g of ascorbic acid, stirring to dissolve, adding 4 to 5 drops of dimethylphenol orange indicator, and adjusting the solution from yellow to pink with hydrochloric acid and ammonia water; wherein the concentration of the dimethylphenol orange indicator is 5 g / ml.

[0019] Optionally, in step (5), the buffer solution is acetic acid-sodium acetate.

[0020] Optionally, step (5) includes the following steps: adding 5 ml to 10 ml of a saturated thiourea solution and 20 ml to 40 ml of a buffer solution to obtain a sample solution, titrating with an EDTA standard solution until the color of the sample solution changes from pink to bright yellow, and calculating the zinc content in the sample based on the molar concentration of the EDTA standard solution, the volume of the EDTA standard solution consumed by the sample solution, and the sample weight.

[0021] Optionally, the preparation of the EDTA standard solution includes the following steps: drying sodium ethylenediaminetetraacetate at 105° C. to 110° C. for 2 hours, weighing 3.7224 g to 3.7225 g, dissolving it in 300 ml of water, and diluting the volume to 1000 ml.

[0022] Optionally, the zinc content in the sample is 45.00% to 99.50%.

[0023] Implementing the embodiments of the present invention will have the following beneficial effects:

[0024] 1. The detection method of the present invention is simple and fast to operate, and is easy for other experimenters to learn. In addition, the accuracy and precision of the analysis method are good, which plays an important role in accurately and reliably guiding production without the need to invest a large amount of additional equipment purchase costs.

[0025] 2. The testing of drugs is routine and easy for other laboratories to use.

[0026] 3. It can detect zinc in zinc and zinc alloys.

[0027] 4. The present invention removes or masks other interfering elements in zinc and zinc alloys, and then performs analysis and detection. The detection process has less interference, the titration end point is obvious, and the detection error is small, which provides an accurate data basis for on-site personnel to understand the zinc content. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way. The present invention discloses a method for detecting the zinc content in zinc ingots and zinc alloys, comprising the following steps:

[0029] (1) Dissolve the sample in acid solution and then add solid ammonium chloride, ammonia water and ammonium persulfate in sequence. Boil with water and collect the precipitate and filtrate by filtration.

[0030] In one specific embodiment, in step (1), the acid solution is hydrochloric acid.

[0031] In a specific embodiment, step (1) comprises the following steps: placing 0.1 g to 0.2 g of the sample in a 400 ml beaker, adding 10 ml to 15 ml of hydrochloric acid and mixing, heating to 240° C. to 300° C. to completely dissolve, removing the sample and rinsing the beaker wall with 50 ml to 60 ml of water to convert the solid zinc into a solution state; adding 5 g to 10 g of solid ammonium chloride to the resulting solution, neutralizing the solution with ammonia water until the precipitation is complete and then adding an excess of 10 ml to 20 ml, then adding 0.5 g to 1.0 g of ammonium persulfate, diluting the solution to 100 ml with water and boiling to destroy the ammonium persulfate, removing the sample, and filtering the precipitate and filtrate with quick filter paper while hot.

[0032] Specifically, after the sample of the present invention is dissolved by acid, an excess amount of ammonia water is added to the filtrate, and in a strong alkaline medium, the iron, manganese, lead and other ions in the filtrate are precipitated, while zinc exists in the solution as zincate, thereby separating zinc from the iron, manganese, lead and other ions by filtration, and removing most of the interfering ions.

[0033] (2) The precipitate is washed with ammonium chloride at 50°C to 60°C, and a washed solution is obtained after boiling and constant volume.

[0034] In a specific embodiment, in step (2), the mass concentration of ammonium chloride is 2%; the number of washings is 5 to 6 times; and the volume is fixed to 120 ml.

[0035] (3) The washed solution is combined with the filtrate, and sodium fluoride, ascorbic acid and dimethylphenol orange indicator are added in sequence. Hydrochloric acid and ammonia water are used to adjust the solution from yellow to pink.

[0036] In a specific embodiment, step (3) comprises the following steps: adding 0.5 g to 1.0 g of sodium fluoride and 0.1 g to 0.2 g of ascorbic acid, stirring to dissolve, adding 4 to 5 drops of dimethylphenol orange indicator, and adjusting the solution from yellow to pink with hydrochloric acid and ammonia water; wherein the concentration of the dimethylphenol orange indicator is 5 g / ml.

[0037] (4) Neutralize with sulfuric acid until the solution in step (3) changes from pink to yellow.

[0038] (5) In the presence of a buffer solution, titrate with a saturated thiourea solution until the solution in step (4) changes from yellow to pink, and then titrate with an EDTA standard solution until the solution changes from pink to bright yellow, which is the end point.

[0039] In a specific embodiment, in step (5), the buffer solution is acetic acid-sodium acetate.

[0040] In a specific embodiment, step (5) includes the following steps: adding 5 ml to 10 ml of a saturated thiourea solution and 20 ml to 40 ml of a buffer solution to obtain a sample solution, titrating with an EDTA standard solution until the color of the sample solution changes from pink to bright yellow, and calculating the zinc content in the sample based on the molar concentration of the EDTA standard solution, the volume of the EDTA standard solution consumed by the sample solution, and the sample weight.

[0041] In a specific embodiment, the preparation of the EDTA standard solution includes the following steps: drying sodium ethylenediaminetetraacetate at 105° C. to 110° C. for 2 hours, weighing 3.7224 g to 3.7225 g, dissolving it in 300 ml of water, and diluting the volume to 1000 ml.

[0042] (6) Calculate the zinc content C in the sample zn :

[0043]

[0044] Among them, C EDTA : molar concentration of EDTA, mol / L; V: volume of EDTA standard solution consumed by the titration solution, ml; m: sample weight, g.

[0045] In a specific embodiment, the zinc content in the sample is 45.00% to 99.50%.

[0046] The following are specific embodiments

[0047] 1. Experimental reagents

[0048] Hydrochloric acid, ρ1.19 g / ml;

[0049] Sulfuric acid, ammonium chloride, solid;

[0050] Ammonium persulfate, solid;

[0051] Sodium fluoride, solid;

[0052] Ascorbic acid, solid;

[0053] Ammonia water, ρ0.91 g / ml;

[0054] Acetic acid, ρ1.05 g / ml;

[0055] Sodium acetate, solid;

[0056] Xylitol orange, 5 g / ml: weigh 0.5 g of Xylitol orange and dissolve it in 100 ml of water;

[0057] EDTA standard solution: Accurately weigh 3.7224 g of the working standard reagent sodium ethylenediaminetetraacetate that has been dried at 105-110℃ for 2 hours, dissolve it in 300 ml of water, transfer it into a 1000 ml volumetric flask, dilute to the scale with water, and shake well.

[0058] 2. Experimental steps

[0059] The method for detecting the zinc content in zinc ingots and zinc alloys of this embodiment comprises the following steps:

[0060] (1) Place 0.1 g of the sample in a 400 ml beaker, add 10 ml of hydrochloric acid and mix, heat to 300°C to completely dissolve, remove the beaker and rinse the beaker wall with 50 ml of water to convert the solid zinc into a solution state; add 5 g of solid ammonium chloride to the resulting solution, neutralize with ammonia water until precipitation is complete, then add 10 ml excess, then add 0.5 g of ammonium persulfate, dilute with water to 100 ml, boil to destroy the ammonium persulfate, remove the beaker, and filter with quick filter paper while hot.

[0061] (2) washing 5 to 6 times with ammonium chloride at 50° C. and a mass concentration of 2%, precipitating, boiling and fixing the volume to 120 ml to obtain a washed solution.

[0062] (3) The washed solution and the filtrate are combined, 0.5 g of sodium fluoride and 0.1 g of ascorbic acid are added in sequence, stirred to dissolve, and 4 to 5 drops of dimethylphenol orange indicator are added dropwise.

[0063] (4) Neutralize with sulfuric acid until the solution in step (3) changes from pink to yellow.

[0064] (5) Add 5 ml of saturated thiourea solution and 20 ml of acetic acid-sodium acetate buffer solution to obtain a sample solution, and titrate with EDTA standard solution until the color of the sample solution changes from pink to bright yellow. Calculate the zinc content in the sample based on the molar concentration of the EDTA standard solution, the volume of the EDTA standard solution consumed by the sample solution, and the sample weight.

[0065] (6) Calculate the zinc content C in the sample zn :

[0066]

[0067] Among them, C EDTA : molar concentration of EDTA, mol / L; V: volume of EDTA standard solution consumed by the titration solution, ml; m: sample weight, g.

[0068] Test Case

[0069] 1. Precision and accuracy of the method

[0070] Two zinc alloy standard samples were selected, and the sampling conditions are shown in Table 1. The detection method of the embodiment was used for continuous monitoring for 8 times, and the obtained results are shown in Table 2. The relative standard deviation RSD of the element determination results was calculated to be less than 5%, which met the detection requirements.

[0071] Table 1 Sampling

[0072]

[0073] Table 2 Precision of zinc titration method

[0074]

[0075] 2. Spike recovery experiment

[0076] Samples 1# and 2# were selected for analysis according to the detection method of the embodiment to obtain the recovery rate. The results are shown in Table 3. It can be seen from the table that the recovery rate of the elements to be tested is between 98% and 103%.

[0077] Table 3 Zinc element titration spike recovery experiment

[0078]

[0079] 3. Method control experiment

[0080] Samples 1# and 2# were selected and compared using the detection method of the embodiment and the existing high-purity zinc detection method. The results are shown in Table 4:

[0081] Table 4 Comparison of zinc element method test results w / %

[0082]

[0083] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for detecting the zinc content in zinc ingots and zinc alloys, characterized in that: The following steps are involved: (1) After the sample is dissolved in acid solution, solid ammonium chloride, ammonia water and ammonium persulfate are added in sequence, water is added and boiled, and the precipitate and filtrate are collected by filtration; (2) washing the precipitate with ammonium chloride at 50° C. to 60° C., and obtaining a washed solution after boiling and constant volume; (3) combining the washed solution with the filtrate, adding sodium fluoride, ascorbic acid and dimethylphenol orange indicator in sequence, and adjusting the solution from yellow to pink using hydrochloric acid and ammonia water; (4) neutralizing with sulfuric acid until the solution in step (3) changes from pink to yellow; (5) in the presence of a buffer solution, titrating with a saturated thiourea solution until the solution in step (4) changes from yellow to pink, and then titrating with an EDTA standard solution until the solution changes from pink to bright yellow as the end point; (6) Calculate the zinc content C in the sample zn : Among them, C EDTA : molar concentration of EDTA, mol / L; V: volume of EDTA standard solution consumed by the titration solution, ml; m: sample weight, g.

2. The method for detecting the zinc content in zinc ingots and zinc alloys according to claim 1, characterized in that: In step (1), the acid solution is hydrochloric acid.

3. The method for detecting the zinc content in zinc ingots and zinc alloys according to claim 1, characterized in that: The step (1) comprises the following steps: Place 0.1g to 0.2g of the sample in a 400ml beaker, add 10ml to 15ml of hydrochloric acid and mix, heat to 240℃ to 300℃ to completely dissolve, remove and rinse the cup wall with 50ml to 60ml of water to convert the solid zinc into a solution state; add 5g to 10g of solid ammonium chloride to the resulting solution, neutralize with ammonia water until the precipitation is complete and then add 10ml to 20ml excess, then add 0.5g to 1.0g of ammonium persulfate, dilute with water to 100ml and boil to destroy the ammonium persulfate, remove, and collect the precipitate and filtrate with quick filter paper while hot.

4. The method for detecting the zinc content in zinc ingots and zinc alloys according to claim 1, characterized in that: In step (2), the mass concentration of ammonium chloride is 2%; The number of washings is 5 to 6 times; The volume was made up to 120 ml.

5. The method for detecting the zinc content in zinc ingots and zinc alloys according to claim 1, characterized in that: Step (3) comprises the following steps: adding 0.5 g to 1.0 g of sodium fluoride and 0.1 g to 0.2 g of ascorbic acid, stirring to dissolve them, adding 4 to 5 drops of dimethylphenol orange indicator, and adjusting the solution from yellow to pink with hydrochloric acid and ammonia water; wherein the concentration of the dimethylphenol orange indicator is 5 g / ml.

6. The method for detecting the zinc content in zinc ingots and zinc alloys according to claim 1, characterized in that: In step (5), the buffer solution is acetic acid-sodium acetate.

7. The method for detecting the zinc content in zinc ingots and zinc alloys according to claim 1, characterized in that: Step (5) comprises the following steps: adding 5 ml to 10 ml of a saturated thiourea solution and 20 ml to 40 ml of a buffer solution to obtain a sample solution, titrating with an EDTA standard solution until the color of the sample solution changes from pink to bright yellow, and calculating the zinc content in the sample based on the molar concentration of the EDTA standard solution, the volume of the EDTA standard solution consumed by the sample solution, and the sample weight.

8. The method for detecting the zinc content in zinc ingots and zinc alloys according to claim 7, characterized in that: The configuration of the EDTA standard solution comprises the following steps: After drying sodium ethylenediaminetetraacetate at 105°C-110°C for 2h, weigh 3.7224g-3.7225g and dissolve it in 300ml of water, and dilute to 1000ml.

9. The method for detecting the zinc content in zinc ingots and zinc alloys according to claim 1, characterized in that: The zinc content in the sample is 45.00% to 99.50%.

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