Method for digesting iron-silicon alloy and application of method in ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) test of iron-silicon alloy

Abstract

The invention provides a method for digesting an iron-silicon alloy and application of the method in ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) test of the iron-silicon alloy. The method comprises the following steps: (1) mixing an iron-silicon alloy, nitric acid and hydrochloric acid, and carrying out a heating reaction to obtain a reaction solution; (2) uniformly mixing hydrofluoric acid and the reaction solution obtained in the step (1) to obtain a digestion solution; through primary dissolution of nitric acid and hydrochloric acid and secondary dissolution of hydrofluoric acid, the dissolution effect of the iron-silicon alloy can be effectively improved, meanwhile, the method has the advantages of being fast, safe and efficient, and the detection standard of ICP-OES on a machine can be met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of element detection, and particularly relates to a method for digesting ferrosilicon alloy and application of the method in ICP-OES testing of ferrosilicon alloy. BACKGROUND

[0002] In the fields of metallurgy and materials, ferrosilicon alloy (FeSi) is an important alloy material, and the contents of iron (Fe) and silicon (Si) elements are key indicators for measuring the performance and quality of the ferrosilicon alloy. Accurate and rapid determination of the contents of Fe and Si in the ferrosilicon alloy is of great significance for the research and development, production and quality control of related products.

[0003] Inductively coupled plasma optical emission spectrometry (ICP-OES) has become a commonly used detection method in material composition analysis due to its high sensitivity, good accuracy and simultaneous determination of multiple elements. However, the accuracy of ICP-OES detection largely depends on the pretreatment effect of the sample, especially for alloy samples such as FeSi. Whether the dissolution can be achieved quickly, completely and without element loss is a key prerequisite to ensure the reliability of the subsequent detection results.

[0004] At present, the commonly used sample digestion method in ICP-OES testing is acid dissolution method, but this method has obvious defects when applied to FeSi: under normal temperature conditions, the dissolution speed of FeSi by acid dissolution method is too fast, which will cause the loss of silicon elements due to volatilization and other reasons, and thus the Si content data obtained by ICP-OES testing is low, which cannot accurately reflect the actual content of Si in FeSi.

[0005] From the chemical properties of Fe and Si, Fe has strong chemical activity and can easily react with many elements under different temperatures and environments, for example, it can react with hydrogen, nitrogen, ammonia and most non-metals to form corresponding compounds under high temperature, and the reaction products of Fe and oxygen will change due to different temperatures and oxygen contents, which increases the difficulty of controlling the Fe dissolution process and avoiding the formation of interfering compounds. The chemical properties of Si are also relatively active, it can combine with many elements under high temperature, and its dissolution characteristics are special - it is not soluble in water, nitric acid and hydrochloric acid, but only soluble in hydrofluoric acid and alkali solution. However, Si is easy to volatilize in hydrofluoric acid, which further increases the difficulty of Si element preservation in the FeSi dissolution process.

[0006] In the prior art, there are few detection methods for the main content of FeSi. X-ray fluorescence spectrometry (XRF) can be used for analysis, but has the problems of low accuracy and large deviation, and cannot meet the high-precision detection requirement; the traditional wet digestion method has the disadvantages of large acid consumption and complicated operation, and also faces the problem of inaccurate detection results due to the volatilization of Si under the action of hydrofluoric acid.

[0007] Therefore, it is urgent to develop a dissolution method capable of quickly dissolving FeSi and effectively avoiding the loss of Fe and Si elements, and suitable for detecting Fe and Si elements in FeSi by ICP-OES, so as to solve the problems of poor detection accuracy, inconvenient operation, and easy loss of elements in the prior art, and meet the needs of rapid and accurate analysis of FeSi composition in related fields. SUMMARY

[0008] In view of the deficiencies in the prior art, the purpose of the present application is to provide a method for digesting iron-silicon alloy and its application in ICP-OES testing of iron-silicon alloy. The digestion method provided by the present application can directly dissolve iron-silicon alloy, has the characteristics of rapidity, safety and high efficiency, and has good digestion effect, and can meet the detection standard of ICP-OES.

[0009] To achieve the purpose of the present application, the following technical solutions are adopted:

[0010] In a first aspect, the present application provides a method for digesting iron-silicon alloy, comprising the following steps:

[0011] (1) mixing iron-silicon alloy, nitric acid and hydrochloric acid for heating reaction to obtain a reaction solution;

[0012] (2) uniformly mixing hydrofluoric acid and the reaction solution obtained in step (1) to obtain a digestion solution.

[0013] In the present application, first, the iron element in the iron-silicon alloy is dissolved by using a mixed acid of nitric acid and hydrochloric acid to obtain a clear and transparent reaction solution containing silicon particles; then the silicon particles are quickly digested by using hydrofluoric acid to obtain a digestion solution, thereby realizing complete dissolution of the iron-silicon alloy at high temperature and stable; and the digestion process is simple in operation, mild in conditions and low in loss, and can meet the detection standard of ICP-OES.

[0014] It is worth noting that the process of mixing acid solution in steps (1)-(2) is carried out in a polytetrafluoroethylene tube; and the device used for the heating reaction in step (1) is a graphite heater.

[0015] As a preferred technical solution of the present application, the Si content in the iron-silicon alloy in step (1) is ≤30wt%, for example, it can be 30wt%, 28wt%, 26wt%, 24wt%, 22wt% or 20wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0016] As a preferred technical solution of the present application, the concentration of the nitric acid is 68-70wt%, for example, it can be 68wt%, 68.4wt%, 68.8wt%, 69.2wt%, 69.6wt% or 70wt%, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0017] Preferably, the concentration of the hydrochloric acid is 65-68wt%, for example, it can be 65wt%, 65.5wt%, 66wt%, 66.5wt%, 67wt%, 67.5wt% or 68wt%, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0018] As a preferred technical solution of the present application, the solid-liquid ratio of the iron-silicon alloy, nitric acid and hydrochloric acid in step (1) is 1g:18-22mL:48-52mL, for example, it can be 1g:20mL:50mL, 1g:18mL:48mL, 1g:22mL:52mL, 1g:19mL:51mL or 1g:21mL:49mL, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0019] As a preferred technical solution of the present application, the temperature of the heating reaction in step (1) is 70-80℃, for example, it can be 70℃, 72℃, 74℃, 76℃, 78℃ or 80℃, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0020] Preferably, the time of the heating reaction in step (1) is 8-12min, for example, it can be 8min, 9min, 10min, 11min or 12min, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0021] The present application uses a mixed acid of hydrochloric acid and nitric acid to digest the iron element in the iron-silicon alloy. If the temperature is too high, it will cause the reaction to be violent during the digestion process, resulting in loss of Fe element. If the temperature is too low, it will result in incomplete dissolution of the Fe element.

[0022] As a preferred technical solution of the present application, the concentration of the hydrofluoric acid in step (2) is 38-42wt%, for example, it can be 38wt%, 39wt%, 40wt%, 41wt% or 42wt%, etc., but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0023] As a preferred technical solution of the present application, the solid-liquid ratio of the ferrosilicon alloy and the hydrofluoric acid is 1g:4-6mL, for example, it can be 1g:4mL, 1g:4.4mL, 1g:4.8mL, 1g:5.2mL, 1g:5.6mL or 1g:6mL, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0024] As a preferred technical solution of the present application, the method for digesting ferrosilicon alloy provided in the first aspect of the present application comprises the following steps:

[0025] (1) mixing the ferrosilicon alloy, nitric acid and hydrochloric acid in a solid-liquid ratio of 1g:18-22mL:48-52mL, and then performing a heating reaction at 70-80℃ for 8-12min to obtain a clear and transparent reaction solution;

[0026] Among them, the Si content in the ferrosilicon alloy is ≤30wt%; the concentration of the nitric acid is 68-70wt%; and the concentration of the hydrochloric acid is 65-68wt%;

[0027] (2) uniformly mixing the hydrofluoric acid and the reaction solution obtained in step (1) to obtain a digestion solution;

[0028] Among them, the solid-liquid ratio of the ferrosilicon alloy and the hydrofluoric acid is 1g:4-6mL; and the concentration of the hydrofluoric acid is 38-42wt%.

[0029] In the second aspect, the present application provides an application of the method as described in the first aspect in the ICP-OES testing of ferrosilicon alloy.

[0030] As a preferred technical solution of the present application, the specific steps of the application include: performing a constant volume treatment on the digestion solution, and then placing the constant volume digestion solution in an ICP-OES device to simultaneously detect Fe element and Si element.

[0031] Preferably, the standard solution used in the constant volume treatment comprises a dilute nitric acid solution.

[0032] Preferably, the concentration of the dilute nitric acid solution is 3-6wt%, for example, it can be 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt% or 6wt%, etc., but not limited to the listed values, and other values not listed in the value range are also applicable.

[0033] The numerical range of the present application includes not only the above-mentioned point values, but also any point values between the above-mentioned numerical ranges that are not mentioned. Due to the limited space and for the sake of simplicity, the present application does not exhaustively list the specific point values included in the range.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] The digestion method provided by the application can effectively improve the dissolution effect of the iron-silicon alloy by combining the primary dissolution of nitric acid and hydrochloric acid with the secondary dissolution of hydrofluoric acid, and has the characteristics of express delivery, safety and high efficiency, and can reach the detection standard of ICP-OES, and the ICP-OES on-machine standard rate can reach 100%. DETAILED DESCRIPTION

[0036] The technical solutions of the application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only used to understand the application and should not be regarded as specific limitations on the application.

[0037] The hydrochloric acid, nitric acid and hydrofluoric acid used in the following examples and comparative examples are commercially available products.

[0038] Example 1

[0039] The example provides a method for digesting an iron-silicon alloy, and the method comprises the following steps:

[0040] (1) mixing 0.1 g of the iron-silicon alloy, 2 mL of nitric acid and 5 mL of hydrochloric acid, and then performing a heating reaction at 75℃ for 10 min to obtain a clear and transparent reaction solution;

[0041] The Si content in the iron-silicon alloy is 5wt%; the concentration of the nitric acid is 69wt%; and the concentration of the hydrochloric acid is 67wt%.

[0042] (2) uniformly mixing the hydrofluoric acid and the reaction solution obtained in step (1) to obtain a digestion solution;

[0043] The solid-liquid ratio of the iron-silicon alloy and the hydrofluoric acid is 1g:5mL; and the concentration of the hydrofluoric acid is 40wt%.

[0044] Example 2

[0045] The example provides a method for digesting an iron-silicon alloy, and the method comprises the following steps:

[0046] (1) mixing 0.1 g of the iron-silicon alloy, 18 mL of nitric acid and 48 mL of hydrochloric acid, and then performing a heating reaction at 70℃ for 12 min to obtain a clear and transparent reaction solution;

[0047] The Si content in the iron-silicon alloy is 5wt%; the concentration of the nitric acid is 70wt%; and the concentration of the hydrochloric acid is 68wt%.

[0048] (2) uniformly mixing the hydrofluoric acid and the reaction solution obtained in step (1) to obtain a digestion solution;

[0049] The solid-liquid ratio of the iron-silicon alloy and the hydrofluoric acid is 1 g:4 mL; the concentration of the hydrofluoric acid is 42 wt%.

[0050] Example 3

[0051] The present example provides a method for digesting an iron-silicon alloy, the method comprising the following steps:

[0052] (1) mixing 0.1 g of the iron-silicon alloy, 22 mL of nitric acid and 52 mL of hydrochloric acid, and then performing a heating reaction at 80°C for 8 min to obtain a clear and transparent reaction solution;

[0053] The Si content in the iron-silicon alloy is 5 wt%; the concentration of the nitric acid is 68 wt%; and the concentration of the hydrochloric acid is 65 wt%.

[0054] (2) uniformly mixing the hydrofluoric acid and the reaction solution obtained in step (1) to obtain a digestion solution;

[0055] The solid-liquid ratio of the iron-silicon alloy and the hydrofluoric acid is 1 g:6 mL; the concentration of the hydrofluoric acid is 38 wt%.

[0056] Example 4

[0057] The present example provides a method for digesting an iron-silicon alloy, the method comprising the following steps:

[0058] (1) mixing 0.1 g of the iron-silicon alloy, 19 mL of nitric acid and 51 mL of hydrochloric acid, and then performing a heating reaction at 76°C for 11 min to obtain a clear and transparent reaction solution;

[0059] The Si content in the iron-silicon alloy is 5 wt%; the concentration of the nitric acid is 68.5 wt%; and the concentration of the hydrochloric acid is 66.8 wt%.

[0060] (2) uniformly mixing the hydrofluoric acid and the reaction solution obtained in step (1) to obtain a digestion solution;

[0061] The solid-liquid ratio of the iron-silicon alloy and the hydrofluoric acid is 1 g:5.5 mL; the concentration of the hydrofluoric acid is 40.2 wt%.

[0062] Example 5

[0063] The present example provides a method for digesting an iron-silicon alloy, the method being different from that of Example 1 only in that:

[0064] In the present example, the solid-liquid ratio of the iron-silicon alloy, the nitric acid and the hydrochloric acid in step (1) is adjusted to 1 g:15 mL:50 mL.

[0065] Example 6

[0066] The present example provides a method for digesting ferrosilicon alloy, which is different from example 1 only in that:

[0067] In the present example, the solid-liquid ratio of the ferrosilicon alloy, nitric acid and hydrochloric acid in step (1) is adjusted to 1 g: 20 mL: 42 mL.

[0068] Example 7

[0069] The present example provides a method for digesting ferrosilicon alloy, which is different from example 1 only in that:

[0070] In the present example, the solid-liquid ratio of the ferrosilicon alloy, nitric acid and hydrochloric acid in step (1) is adjusted to 1 g: 20 mL: 42 mL.

[0071] Example 8

[0072] The present example provides a method for digesting ferrosilicon alloy, which is different from example 1 only in that:

[0073] In the present example, the solid-liquid ratio of the ferrosilicon alloy, nitric acid and hydrochloric acid in step (1) is adjusted to 1 g: 20 mL: 42 mL.

[0074] Example 9

[0075] The present example provides a method for digesting ferrosilicon alloy, which is different from example 1 only in that:

[0076] In the present example, the temperature of the heating reaction in step (1) is adjusted to 60°C.

[0077] Example 10

[0078] The present example provides a method for digesting ferrosilicon alloy, which is different from example 1 only in that:

[0079] In the present example, the temperature of the heating reaction in step (1) is adjusted to 85°C.

[0080] Example 11

[0081] The present example provides a method for digesting ferrosilicon alloy, which is different from example 1 only in that:

[0082] In the present example, the solid-liquid ratio of the ferrosilicon alloy and hydrofluoric acid in step (2) is adjusted to 1 g: 3 mL.

[0083] Example 12

[0084] The present example provides a method for digesting ferrosilicon alloy, which is different from example 1 only in that:

[0085] The solid-liquid ratio of the iron-silicon alloy and hydrofluoric acid in step (2) is adjusted to 1 g:7.2 mL in this example.

[0086] Comparative Example 1

[0087] This comparative example provides a method for digesting an iron-silicon alloy, which is only different from Example 1 in that:

[0088] This comparative example omits the use of nitric acid in step (1).

[0089] Comparative Example 2

[0090] This comparative example provides a method for digesting an iron-silicon alloy, which is only different from Example 1 in that:

[0091] This comparative example omits the use of hydrochloric acid in step (1).

[0092] Comparative Example 3

[0093] This comparative example provides a method for digesting an iron-silicon alloy, which is only different from Example 1 in that:

[0094] This comparative example adjusts the nitric acid and hydrochloric acid in step (1) to a mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid, and the amount of nitric acid is 2 mL, the amount of hydrochloric acid is 5 mL, and the amount of hydrofluoric acid is 0.5 mL.

[0095] Comparative Example 4

[0096] This comparative example provides a method for digesting an iron-silicon alloy, which is only different from Example 1 in that:

[0097] This comparative example omits the process of mixing hydrofluoric acid in step (2).

[0098] Performance Test

[0099] The digestion solution provided by the above examples and comparative examples is placed in a volumetric flask, 5wt% nitric acid is used to constant volume to 100 mL, and then diluted by 100 times, and then placed in an ICP-OES device to detect Fe element and Si element at the same time, and the detection results are shown in Table 1.

[0100] Table 1

[0101]

[0102]

[0103] According to Table 1, the following contents can be known:

[0104] (1) Comprehensive analysis of examples 1-4 can be known that, by the preliminary dissolution of nitric acid and hydrochloric acid, combined with the secondary dissolution of hydrofluoric acid, the dissolution effect of iron-silicon alloy can be effectively improved, and it has the characteristics of express, safety and high efficiency, and can reach the detection standard of ICP-OES on machine;

[0105] (2) Comprehensive analysis of examples 1 and examples 5-8 can be known that, the amount of acid liquid in the heating reaction process of step (1) will affect the digestion effect of iron-silicon alloy;

[0106] The amount of nitric acid or hydrochloric acid is too low or too high, which will cause the measured value of Si element in the iron-silicon alloy to be too low, and the deviation is large;

[0107] (3) Comprehensive analysis of examples 1 and examples 9-10 can be known that, the temperature of the heating reaction in step (1) is too high, which will cause the reaction to be intensified, and then the loss of Si element is more, the measured value is too low, and the deviation is large, and the temperature is too low, which will cause the alloy solution to be incomplete;

[0108] (4) Comprehensive analysis of examples 1 and examples 11-12 can be known that, the amount of hydrofluoric acid in step (2) is too low, which will cause the measured value of Si element to be too low, and the deviation is large, and the amount is too high, which will cause the loss of Si element, and then the Si content is too low;

[0109] (5) Comprehensive analysis of examples 1 and comparative examples 1-2 can be known that, omitting any kind of acid in step (1) will cause the measured value of Si element to be too low, and the deviation is large;

[0110] Comprehensive analysis of examples 1 and comparative example 3 can be known that, if the HF used in step (2) is mixed into the heating reaction in step (1), the measured value of Si element will be too low, and the deviation is large;

[0111] Comprehensive analysis of examples 1 and comparative example 4 can be known that, if step (2) is omitted, the dissolution of Si element will be incomplete, and the measured value is too low.

[0112] In summary, by the preliminary dissolution of nitric acid and hydrochloric acid, combined with the secondary dissolution of hydrofluoric acid, the dissolution effect of iron-silicon alloy can be effectively improved, and it has the characteristics of express, safety and high efficiency, and can reach the detection standard of ICP-OES on machine.

[0113] The applicant declares that the above-mentioned specific examples have further detailed the purpose, technical scheme and beneficial effects of the present application, and it should be understood that the above-mentioned is only a specific embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for digesting iron-silicon alloys, characterized in that, The method includes the following steps: (1) Mix iron-silicon alloy, nitric acid and hydrochloric acid and heat to react to obtain a reaction solution; (2) Mix hydrofluoric acid and the reaction solution obtained in step (1) evenly to obtain a digestion solution.

2. The method for digesting iron-silicon alloys according to claim 1, characterized in that, In step (1), the Si content in the iron-silicon alloy is ≤30wt%.

3. The method for digesting iron-silicon alloys according to claim 1 or 2, characterized in that, The concentration of the nitric acid is 68-70 wt%. Preferably, the concentration of the hydrochloric acid is 65-68 wt%.

4. The method for digesting iron-silicon alloys according to any one of claims 1-3, characterized in that, The solid-liquid ratio of the iron-silicon alloy, nitric acid and hydrochloric acid in step (1) is 1g:18-22mL:48-52mL.

5. The method for digesting iron-silicon alloys according to any one of claims 1-4, characterized in that, The heating reaction in step (1) is carried out at a temperature of 70–80°C; Preferably, the heating reaction time in step (1) is 8 to 12 minutes.

6. The method for digesting iron-silicon alloys according to any one of claims 1-5, characterized in that, The concentration of hydrofluoric acid in step (2) is 38–42 wt%.

7. The method for digesting iron-silicon alloys according to any one of claims 1-6, characterized in that, The solid-liquid ratio of the iron-silicon alloy and hydrofluoric acid is 1g:4-6mL.

8. The method for digesting iron-silicon alloys according to any one of claims 1-7, characterized in that, The method includes the following steps: (1) Mix iron-silicon alloy, nitric acid and hydrochloric acid in a solid-liquid ratio of 1g:18~22mL:48~52mL, and then heat the mixture at 70~80℃ for 8~12min to obtain a clear and transparent reaction solution. Wherein, the Si content in the iron-silicon alloy is ≤30wt%; the concentration of the nitric acid is 68-70wt%; and the concentration of the hydrochloric acid is 65-68wt%. (2) Mix hydrofluoric acid and the reaction solution obtained in step (1) evenly to obtain a digestion solution; The solid-liquid ratio of the iron-silicon alloy and hydrofluoric acid is 1g:4-6mL; the concentration of the hydrofluoric acid is 38-42wt%.

9. An application of the method as described in any one of claims 1-8 in ICP-OES testing of iron-silicon alloys.

10. The application according to claim 9, characterized in that, The specific steps of the application include: adjusting the volume of the digestion solution, and then placing the adjusted digestion solution in an ICO-OES device to simultaneously detect Fe and Si elements; Preferably, the standard solution used in the volume adjustment process includes a dilute nitric acid solution; Preferably, the concentration of the dilute nitric acid solution is 3-6 wt%.

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