Method for detecting tin in multivalent arsenic material

Abstract

The invention belongs to the technical field of analysis and detection, and discloses a method for detecting tin in a multivalent arsenic material. Adding coal into the multivalent arsenic material, completely roasting, adding a reducing reagent, covering sodium chloride, and sintering; adding iron powder into the sample, putting the sample into hydrochloric acid for leaching, adding aluminum particles for reduction after leaching is completed, and introducing carbon dioxide gas before reduction is completed; and after reduction is completed, adding an indicator, titrating the content of tin by using a potassium iodate standard solution, and calculating an analysis result. The method provided by the invention can reduce the error rate of analysis and detection of tin in the multivalent arsenic material, can be applied to analysis and detection of tin in the multivalent arsenic material, and solves the problems that when tin in the multivalent arsenic material is titrated by using the existing potassium iodate titration method, the end point color is slightly black, the end point cannot be observed, and the result accuracy is poor.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical detection, and more specifically, to a method for detecting tin in multi-valent arsenic materials. Background Art

[0002] Multi-valent arsenic materials are materials containing arsenic elements with different valence states. Arsenic in different valence states has different effects on tin detection. The presence of multi-valent arsenic will wrap tin, consume potassium iodate standard solution, affect the judgment of the end point color, etc., resulting in inaccurate and unstable tin results. Traditionally, hydrochloric acid and potassium chloride are used for decomposition, and arsenic is volatilized and removed in the form of chloride. This method has a long process, is complex to operate, and is not easy to master. Moreover, this method can only process trivalent arsenic materials and cannot process multi-valent arsenic materials. If the traditional method is used to process multi-valent arsenic materials, the accuracy rate of tin results will be greatly reduced.

[0003] Therefore, it is an urgent problem for those skilled in the art to provide a method for accurately detecting tin in multi-valent arsenic materials. Summary of the Invention

[0004] In view of this, the present invention provides a new method for detecting tin in multi-valent arsenic materials, which can simultaneously process materials containing multi-valent arsenic, and is simple to operate and can accurately determine the content of tin. The detection method of the present invention can reduce the interference of tin detection in multi-valent arsenic materials, so as to accurately provide the content of tin in multi-valent arsenic materials.

[0005] In order to achieve the above object, the present invention provides a method for detecting tin in multi-valent arsenic materials, including the following steps:

[0006] (1) Add coal to the multi-valent arsenic material, stir evenly, and transfer it to a muffle furnace for roasting.

[0007] (2) After complete roasting, take out and cool, add reducing agents to the sample in sequence, and finally cover with sodium chloride, and place it in a muffle furnace for sintering.

[0008] (3) After complete sintering, take out and cool, add iron powder to the sample, and leach it in hydrochloric acid.

[0009] (4) After complete leaching, add aluminum pellets for reduction. Before the complete reduction of aluminum pellets, introduce carbon dioxide gas. After the reduction is completed, cool the sample in running water to obtain a test solution.

[0010] (5) Add an indicator to the test solution, titrate the content of tin with a potassium iodate standard solution, and calculate the analysis result.

[0011] Further, in step (1), the mass ratio of the multi-valent arsenic material to coal is 1:0.5 - 10, and the fixed carbon content of the coal is 40% - 90%.

[0012] Further, in step (1), the temperature of the roasting is 600°C to 900°C, and the time is 5 minutes to 30 minutes.

[0013] The technical effect of adopting the above dosage relationship and roasting temperature is that arsenic in the high valence state can be reduced to arsenic in the low valence state, and arsenic in the low valence state is easily volatilized and removed.

[0014] Further, in step (2), the reducing agents are zinc powder - sodium hydroxide - zinc powder in sequence, and the mass ratio of zinc powder, sodium hydroxide, and zinc powder is (1 - 3):1:(0.5 - 5);

[0015] The mass ratio of the multi-valent arsenic material, the reducing agent, and the sodium chloride is (0.1 - 0.5):(2.5 - 5):(0.5 - 2).

[0016] Further, in step (2), the temperature of the sintering is 650°C to 800°C, and the time is 10 minutes to 30 minutes.

[0017] Further, in step (3), the particle size of the iron powder is ≤150 μm, and the concentration of the hydrochloric acid is 0.500 g / mL to 1.00 g / mL;

[0018] The solid-liquid ratio of the multi-valent arsenic material, iron powder, and hydrochloric acid is (0.1 - 0.5) g:(0.4 - 2.5) g:(100 - 150) mL.

[0019] The technical effect of adopting the above reducing agent is to decompose the test sample, and at the same time reduce tetravalent tin to divalent tin, preparing for the later reduction with aluminum pellets.

[0020] Further, in step (3), the temperature of the leaching is 100°C to 250°C, and the time is 30 minutes to 50 minutes.

[0021] The technical effect of adopting the above conditions is that the test sample can be transferred out, changing the test sample from solid state to liquid state, preparing for the later titration.

[0022] Further preferably, the cooling time is 10 minutes - 30 minutes.

[0023] The beneficial effect of introducing carbon dioxide and the timing of introducing carbon dioxide is to isolate air and prevent divalent tin from being oxidized to tetravalent tin by oxygen in the air.

[0024] Further preferably, the cooling time is 10 minutes - 30 minutes.

[0025] Further, in step (5), the indicator is starch indicator with a concentration of 5 g / L to 10 g / L.

[0026] Further, in step (5), the solid-liquid ratio of the multi-valent arsenic material to the indicator is 0.1 g: 5 mL.

[0027] Compared with the prior art, the technical concept of the present invention is as follows: coal is added to the test sample, and the arsenic compound is removed in advance by roasting, eliminating the influence of arsenic compounds with different valence states on the determination of tin, so as to accurately determine the content of tin.

[0028] It can be seen from the above technical solutions that, compared with the prior art, the technical effects achieved by the present invention are as follows:

[0029] In the detection method provided by the present invention, arsenic in the sample is volatilized and removed in advance by coal at high temperature. The sample is sintered with a reducing solvent, leached with hydrochloric acid, reduced with aluminum pellets, and finally titrated, so as to accurately measure the content of tin. This method is simple to operate, has good arsenic removal effect, and can accurately determine the content of tin in multi-valent arsenic materials.

[0030] The present invention solves the problems that when titrating tin in multi-valent arsenic materials by the existing potassium iodate titration method, the end point color is too dark to observe the end point, and the result accuracy is poor. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative work.

[0032] Figure 1 It is a comparison of the arsenic removal effects between the traditional method and the method of the present invention. Detailed Embodiments

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0034] Example 1

[0035] The present invention provides a method for detecting tin in multi-valent arsenic materials, and the specific steps are as follows:

[0036] (1) Weigh 0.1 g of the multi-valent arsenic material (accurate to 0.0001 g) into a crucible. Add 0.05 g of coal to the crucible, stir evenly, transfer it to a muffle furnace at 600 °C for roasting for 30 min, take it out and cool. Among them, the fixed carbon content of the coal is 40%;

[0037] (2) Add 1 g of zinc powder, 0.5 g of sodium hydroxide, 1.5 g of zinc powder, and 0.5 g of sodium chloride to the roasted sample in sequence. Transfer it to a muffle furnace at 650 °C for sintering for 30 min, take it out and cool;

[0038] (3) Add 0.5 g of iron powder to the sintered sample, put it into a conical flask pre-added with 100 mL of hydrochloric acid, and leach it on an electric furnace at 150 °C for 50 min. Among them, the particle size of the iron powder is ≤150 μm, and the concentration of the hydrochloric acid is 0.600 g / mL;

[0039] (4) Add 1 g of aluminum pellets to the leached test solution. Before the reduction of the aluminum pellets is completed, introduce carbon dioxide gas for 5 min, take it down and cool for 10 min;

[0040] (5) Add 3 mL of indicator to the solution in step (4), titrate the tin content with potassium iodate standard solution, and calculate the analysis result. Among them, the concentration of the indicator is 6 g / L.

[0041] Use the method of Example 1 to test the tin in the multi-valent arsenic material, and conduct parallel determination 6 times. Compare with the traditional method, and the comparison results are shown in Table 1:

[0042] Among them, the traditional method is as follows: The test sample is decomposed with hydrochloric acid and potassium chlorate, arsenic is volatilized and removed in the form of chloride. In the presence of disodium ethylenediaminetetraacetate, using beryllium hydroxide as a carrier, tin is precipitated with ammonia water to separate it from elements such as copper, tungsten, antimony, and bismuth. The precipitate is ashed, melted with zinc powder - borax - boric acid, leached with hydrochloric acid, tin is reduced to divalent with iron powder and aluminum pellets, and starch is used as an indicator, and it is titrated with potassium iodate standard solution.

[0043] The traditional method in the following examples is the same as that in this example.

[0044] Table 1 Comparison table of tin detection results

[0045]

[0046]

[0047] Example 2

[0048] The present invention provides a method for detecting tin in multi-valent arsenic materials, and the specific steps are as follows:

[0049] (1) Weigh 0.2 g of multi-valent arsenic material (accurate to 0.0001 g) into a crucible. Add 0.15 g of coal to the crucible, stir evenly, transfer it to a muffle furnace at 650 °C and roast for 25 min. Take it out and cool. Among them, the fixed carbon content of the coal is 50%;

[0050] (2) Add 1.2 g of zinc powder, 0.7 g of sodium hydroxide, 1.7 g of zinc powder, and 0.7 g of sodium chloride to the roasted sample in sequence. Transfer it to a muffle furnace at 700 °C and sinter for 25 min. Take it out and cool;

[0051] (3) Add 0.7 g of iron powder to the sintered sample, put it into a conical flask pre-added with 120 mL of hydrochloric acid, and leach it on an electric furnace at 180 °C for 40 min. Among them, the particle size of the iron powder is ≤150 μm, and the concentration of hydrochloric acid is 0.65 g / mL;

[0052] (4) Add 1.5 g of aluminum pellets to the leached test solution. Before the reduction of the aluminum pellets is completed, introduce carbon dioxide gas for 10 min, take it down and cool for 15 min;

[0053] (5) Add 5 mL of indicator to the solution in step (4), titrate the tin content with potassium iodate standard solution, and calculate the analysis result. Among them, the concentration of the indicator is 7 g / L.

[0054] The tin in the multi-valent arsenic material is tested by the method of Example 2, and it is determined in parallel 6 times. Compared with the original traditional method, the comparison results are shown in Table 2:

[0055] Table 2 Comparison table of tin detection results

[0056]

[0057]

[0058] Example 3

[0059] The present invention provides a method for detecting tin in multi-valent arsenic material, and the specific steps are as follows:

[0060] (1) Weigh 0.3 g of multi-valent arsenic material (accurate to 0.0001 g) into a crucible. Add 1.0 g of coal to the crucible, stir evenly, transfer it to a muffle furnace at 750 °C and roast for 15 min. Take it out and cool. Among them, the fixed carbon content of the coal is 60%;

[0061] (2) Add 1.5 g of zinc powder, 0.8 g of sodium hydroxide, 1.0 g of zinc powder, and 1.2 g of sodium chloride to the roasted sample in sequence. Transfer it to a muffle furnace at 750 °C and sinter for 15 min. Take it out and cool;

[0062] (3) Add 0.9 g of iron powder to the sintered sample, place it in a conical flask pre-added with 130 mL of hydrochloric acid, and leach it on an electric furnace at 200 °C for 35 min. The particle size of the iron powder is ≤150 μm, and the concentration of hydrochloric acid is 0.700 g / mL;

[0063] (4) Add 2.0 g of aluminum particles to the leached test solution. Before the reduction of the aluminum particles is completed, introduce carbon dioxide gas for 20 min, and then remove and cool for 20 min;

[0064] (5) Add 7 mL of indicator to the solution in step (4), titrate the content of tin with potassium iodate standard solution, and calculate the analysis result. The concentration of the indicator is 8 g / L.

[0065] The tin in the multi-valent arsenic material was tested by the method of Example 3, and the parallel determination was carried out 6 times. Compared with the original traditional method, the comparison results are shown in Table 3:

[0066] Table 3 Comparison table of tin detection results

[0067]

[0068]

[0069] Example 4

[0070] The present invention provides a method for detecting tin in multi-valent arsenic materials, and the specific steps are as follows:

[0071] (1) Weigh 0.4 g of multi-valent arsenic material (accurate to 0.0001 g) into a crucible, add 0.6 g of coal to the crucible, stir evenly, transfer it to a muffle furnace at 820 °C for roasting for 10 min, take it out and cool. Among them, the fixed carbon content of the coal is 80%;

[0072] (2) Add 2.0 g of zinc powder, 1.0 g of sodium hydroxide, 1.2 g of zinc powder, and 1.0 g of sodium chloride to the roasted sample in sequence, transfer it to a muffle furnace at 800 °C for sintering for 10 min, take it out and cool;

[0073] (3) Add 1.5 g of iron powder to the sintered sample, place it in a conical flask pre-added with 150 mL of hydrochloric acid, and leach it on an electric furnace at 250 °C for 25 min. The particle size of the iron powder is ≤150 μm, and the concentration of hydrochloric acid is 0.800 g / mL;

[0074] (4) Add 2.5 g of aluminum particles to the leached test solution. Before the reduction of the aluminum particles is completed, introduce carbon dioxide gas for 30 min, and then remove and cool for 25 min;

[0075] (5) Add 10 mL of indicator to the solution in step (4), titrate the content of tin with potassium iodate standard solution, and calculate the analysis result. The concentration of the indicator is 10 g / L.

[0076] The tin in the multi-valent arsenic material was tested by the method of Example 4, and the parallel determination was carried out 6 times. Compared with the original traditional method, the comparison results are shown in Table 4:

[0077] Table 4 Comparison table of test results of tin

[0078]

[0079] It can be seen from the results of the examples that for the tin in the multi-valent arsenic material, the method provided by the present invention has good precision and high accuracy. In order to verify the accuracy of the results of the method of the present invention, a standard addition recovery experiment was carried out, and the relevant experimental conditions are shown in Table 5:

[0080] Table 5 Record table of recovery rate results

[0081]

[0082] It can be seen from the above table that the standard addition recovery rate is between 99.33% and 100.83%, indicating that the analysis method of the present invention is feasible, the results are accurate and reliable, and the error rate of the analysis of tin in the multi-valent arsenic material can be reduced.

[0083] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting tin in multi-valent arsenic materials, characterized in that, It includes the following steps: (1) Add coal to the multi-valent arsenic material, stir evenly, and roast. (2) After complete roasting, take out and cool, add reducing agents in sequence, and finally cover with sodium chloride and sinter. (3) After complete sintering, take out and cool, add iron powder, and leach in hydrochloric acid. (4) After complete leaching, add aluminum pellets for reduction. Before the complete reduction of aluminum pellets, introduce carbon dioxide gas. After the reduction is completed, cool to obtain the solution to be measured. (5) Add an indicator to the solution to be measured, titrate with a potassium iodate standard solution, and calculate the analysis result.

2. The detection method of tin in a multi-valent arsenic material according to claim 1, characterized in that, In step (1), the mass ratio of the multi-valent arsenic material to coal is 1:0.5 - 10, and the fixed carbon content of the coal is 40% - 90%.

3. The detection method of tin in a multi-valence arsenic material according to claim 1, characterized in that, In step (1), the roasting temperature is 600°C - 900°C, and the time is 5 min - 30 min.

4. The detection method of tin in polyvalent arsenic materials according to claim 1, characterized in that, In step (2), the reducing agents are zinc powder - sodium hydroxide - zinc powder in sequence, and the mass ratio of zinc powder, sodium hydroxide, and zinc powder is (1 - 3):1:(0.5 - 5). The mass ratio of the multi-valent arsenic material to the reducing agent and the sodium chloride is (0.1 - 0.5):(2.5 - 5):(0.5 - 2).

5. The detection method of tin in polyvalent arsenic materials according to claim 1, characterized in that, In step (2), the sintering temperature is 650°C - 800°C, and the time is 10 min - 30 min.

6. The detection method of tin in a multi-valent arsenic material according to claim 1, characterized in that, In step (3), the particle size of the iron powder is ≤150 μm, and the concentration of the hydrochloric acid is 0.500 g / mL - 1.00 g / mL. The solid-liquid ratio of the multi-valent arsenic material, iron powder, and hydrochloric acid is (0.1 - 0.5) g:(0.4 - 2.5) g:(100 - 150) mL.

7. The detection method of tin in polyvalent arsenic materials according to claim 1, characterized in that, In step (3), the leaching temperature is 100°C - 250°C, and the time is 30 min - 50 min.

8. The detection method of tin in polyvalent arsenic materials according to claim 1, characterized in that, In step (4), the mass ratio of the multi-valent arsenic material to the aluminum pellets is 1:(5 - 20). The time for introducing carbon dioxide gas is 5 min - 40 min, and the rate is 1 - 5 L / min.

9. The detection method of tin in a multi-valence arsenic material according to claim 1, wherein, In step (5), the indicator is a starch indicator with a concentration of 5 g / L - 10 g / L.

10. The detection method of tin in polyvalent arsenic materials according to claim 1, wherein In step (5), the solid-liquid ratio of the multi-valent arsenic material to the indicator is 0.1 g:5 mL.

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