Method for measuring ferrous iron content in laterite nickel ore

Abstract

A method for measuring the ferrous iron content in a laterite nickel ore, comprising the following steps: (1) decomposing a laterite nickel ore sample by using a first mixed acid solution to obtain a sample solution; (2) mixing a second mixed acid solution and the sample solution, and dropwisely adding sodium diphenylamine sulfonate to the obtained mixed solution as an indicator; (3) titrating the mixed solution by using a potassium dichromate standard solution, a titration endpoint being reached when the color of the solution changes to purple blue; and (4) calculating the ferrous iron content in the laterite nickel ore sample on the basis of the consumption amount of the potassium dichromate standard solution, wherein the first mixed acid solution in step (1) comprises a sulfuric acid solution and a hydrofluoric acid solution, and the second mixed acid solution in step (2) comprises a sulfuric acid solution, a phosphoric acid solution and a boric acid solution.

Description

A method for detecting ferrous content in laterite nickel ore Technical Field

[0001] This application belongs to the field of chemical detection technology, and relates to a method for detecting ferrous content, and more particularly to a method for detecting ferrous content in laterite nickel ore. Background Technology

[0002] Lateritic nickel ore is an important mineral resource, and the determination of its ferrous content is of great significance for the selection of smelting processes, product quality control, and the rational utilization of resources. Existing detection methods mainly include titration, colorimetry, atomic absorption spectrometry, and electrochemical methods, but each of these methods has its own shortcomings and there is still considerable room for improvement.

[0003] The main drawback of titration is that it can be affected by interference from other reducing substances, leading to inaccurate results. Furthermore, titration typically requires complex procedures, including sample dissolution, titrant addition, and endpoint determination, increasing both operational complexity and the potential for error.

[0004] The main drawback of colorimetric methods is that they can be affected by interference from other colored ions, leading to inaccurate results. Furthermore, colorimetric methods typically require specific reagents and colorimetric agents, which may be unstable and easily degraded by environmental factors such as light and temperature. Colorimetric methods also generally require relatively expensive instruments, such as colorimeters or spectrophotometers, thus increasing the cost of the measurement.

[0005] The main drawback of spectroscopic analysis is its susceptibility to interference from other elements, requiring interference correction. Spectroscopic analysis typically requires expensive instruments and specialized personnel for operation and maintenance. Furthermore, it demands sophisticated sample pretreatment, potentially involving complex digestion and dilution procedures.

[0006] The main drawback of electrochemical methods is that electrodes may be contaminated or passivated, leading to unstable measurement results. Furthermore, electrochemical methods typically require more complex instrumentation, such as electrochemical workstations, increasing the cost of the assay. Additionally, electrochemical methods are highly sensitive to operating environment and conditions, such as temperature and stirring speed, further increasing operational complexity and the potential for error.

[0007] Therefore, it is evident that providing a method for detecting ferrous content in laterite nickel ore that overcomes the shortcomings of existing technologies, such as insufficient sensitivity, poor accuracy, cumbersome operation procedures, and high cost, has become an urgent problem for those skilled in the art.

[0008] Summary of the Invention

[0009] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0010] This application provides a method for detecting the ferrous content in laterite nickel ore. The method is highly sensitive, accurate, easy to operate, and does not require expensive instruments, thus reducing detection costs, improving economic efficiency, and facilitating large-scale application.

[0011] This application provides a method for detecting the ferrous content in laterite nickel ore, the method comprising the following steps:

[0012] (1) The laterite nickel ore sample was decomposed using the first mixed acid solution to obtain the sample solution;

[0013] (2) Mix the second mixed acid solution and the sample solution obtained in step (1), and add sodium diphenylamine sulfonate as an indicator to the resulting mixed solution;

[0014] (3) Titrate the mixed solution obtained in step (2) with potassium dichromate standard solution. The titration endpoint is reached when the solution color changes to blue-purple.

[0015] (4) Calculate the ferrous content in the laterite nickel ore sample based on the amount of potassium dichromate standard solution consumed in step (3).

[0016] In step (1), the first mixed acid solution includes sulfuric acid solution and hydrofluoric acid solution, and in step (2), the second mixed acid solution includes sulfuric acid solution, phosphoric acid solution and boric acid solution.

[0017] The detection method provided in this application allows for adjustment of sample volume and standard solution volume based on the ferrous content of laterite nickel ore samples, thus adapting to the analytical needs of samples with different concentration ranges. Specifically, the addition of phosphoric acid solution masks potential interference from ferric ions, helping to reduce the adverse effects of interfering factors on the analytical results and improving detection accuracy. Boric acid solution not only complexes fluorine in the solution but also accelerates the complete dissolution of the sample, further improving detection accuracy and stability. The mixed acid solutions used are all common and inexpensive reagents, avoiding the use of expensive equipment, reducing experimental costs, and improving the economic feasibility of the technology. The entire detection process is clear, requiring no complex instruments or advanced skills, making it easy for researchers and industry to accept and apply, facilitating large-scale promotion and application.

[0018] In one embodiment, the laterite nickel ore sample in step (1) is crushed and sieved before decomposition.

[0019] In one embodiment, the average particle size of the laterite nickel ore sample in step (1) is 80-120 mesh, for example, it can be 80 mesh, 85 mesh, 90 mesh, 95 mesh, 100 mesh, 105 mesh, 110 mesh, 115 mesh or 120 mesh, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0020] In one embodiment, the decomposition in step (1) includes: weighing the laterite nickel ore sample and placing it in a crucible, adding sulfuric acid solution preheated to near boiling, shaking the crucible until the sample disperses, covering the crucible with the lid, heating the crucible until the acid solution boils, adding hydrofluoric acid solution dropwise, continuing to heat the crucible until the acid solution boils, and maintaining a slight boiling state until the sample is completely decomposed.

[0021] In this application, since ferrous ions are easily oxidized by air during the decomposition of laterite nickel ore samples, the crucible lid is covered during the decomposition process to remove as much air as possible from the solution.

[0022] In one embodiment, the hydrofluoric acid solution is added dropwise in batches.

[0023] In this application, some silicates in the laterite nickel ore sample react violently with hydrofluoric acid, so it is necessary to add them dropwise in batches to avoid splashing and improve operational safety.

[0024] In one embodiment, a refractory plate is disposed below the crucible.

[0025] This application provides a refractory plate below the crucible, which helps to improve the uniformity of heating of the crucible and prevents the solution from splashing out due to sudden heating, thus avoiding injury to the operator.

[0026] In one embodiment, the weighing range of the laterite nickel ore sample is 0.2-1.5g, for example, it can be 0.2g, 0.3g, 0.4g, 0.5g, 0.6g, 0.7g, 0.8g, 0.9g, 1g, 1.1g, 1.2g, 1.3g, 1.4g or 1.5g, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] In one embodiment, the crucible includes a platinum crucible or a polytetrafluoroethylene crucible.

[0028] In one embodiment, the volume of the crucible is 30-50 mL, for example, it can be 30 mL, 32 mL, 34 mL, 36 mL, 38 mL, 40 mL, 42 mL, 44 mL, 46 mL, 48 mL or 50 mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] In one embodiment, the concentration of the sulfuric acid solution is 40-60 wt%, for example, it can be 40 wt%, 42 wt%, 44 wt%, 46 wt%, 48 wt%, 50 wt%, 52 wt%, 54 wt%, 56 wt%, 58 wt%, or 60 wt%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] In one embodiment, the added volume of sulfuric acid solution is 7-10 mL, for example, 7 mL, 7.2 mL, 7.4 mL, 7.6 mL, 7.8 mL, 8 mL, 8.2 mL, 8.4 mL, 8.6 mL, 8.8 mL, 9 mL, 9.2 mL, 9.4 mL, 9.6 mL, 9.8 mL, or 10 mL, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0031] In one embodiment, the concentration of the hydrofluoric acid solution is 30-50 wt%, for example, it can be 30 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, 40 wt%, 42 wt%, 44 wt%, 46 wt%, 48 wt%, or 50 wt%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0032] In one embodiment, the volume of hydrofluoric acid solution added is 10-15 mL, for example, 10 mL, 10.5 mL, 11 mL, 11.5 mL, 12 mL, 12.5 mL, 13 mL, 13.5 mL, 14 mL, 14.5 mL or 15 mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0033] In one embodiment, the duration of the simmering state is 8-15 minutes, for example, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In one embodiment, the mixing in step (2) includes: adding deionized water, sulfuric acid solution, phosphoric acid solution and boric acid solution to a beaker in advance and mixing them evenly, and then transferring the sample solution to the beaker.

[0035] In one embodiment, the volume of deionized water added is 150-250 mL, for example, 150 mL, 160 mL, 170 mL, 180 mL, 190 mL, 200 mL, 210 mL, 220 mL, 230 mL, 240 mL or 250 mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0036] In one embodiment, the concentration of the sulfuric acid solution is 40-60 wt%, for example, it can be 40 wt%, 42 wt%, 44 wt%, 46 wt%, 48 wt%, 50 wt%, 52 wt%, 54 wt%, 56 wt%, 58 wt%, or 60 wt%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] In one embodiment, the added volume of sulfuric acid solution is 8-12 mL, for example, 8 mL, 8.5 mL, 9 mL, 9.5 mL, 10 mL, 10.5 mL, 11 mL, 11.5 mL or 12 mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0038] In one embodiment, the concentration of the phosphoric acid solution is 60-80 wt%, for example, it can be 60 wt%, 62 wt%, 64 wt%, 66 wt%, 68 wt%, 70 wt%, 72 wt%, 74 wt%, 76 wt%, 78 wt%, or 80 wt%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0039] In one embodiment, the volume of phosphoric acid solution added is 4-6 mL, for example, 4 mL, 4.2 mL, 4.4 mL, 4.6 mL, 4.8 mL, 5 mL, 5.2 mL, 5.4 mL, 5.6 mL, 5.8 mL or 6 mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0040] In one embodiment, the concentration of the boric acid solution is 20-25 wt%, for example, it can be 20 wt%, 20.5 wt%, 21 wt%, 21.5 wt%, 22 wt%, 22.5 wt%, 23 wt%, 23.5 wt%, 24 wt%, 24.5 wt%, or 25 wt%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0041] In one embodiment, the volume of boric acid solution added is 20-30 mL, for example, 20 mL, 21 mL, 22 mL, 23 mL, 24 mL, 25 mL, 26 mL, 27 mL, 28 mL, 29 mL or 30 mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In one embodiment, the amount of sodium diphenylamine sulfonate added in step (2) is 3-6 drops, for example, 3 drops, 4 drops, 5 drops or 6 drops, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] In one embodiment, the titration process in step (3) is accompanied by continuous shaking of the solution to ensure that the solution is mixed evenly.

[0044] As an optional technical solution in this application, the detection method includes the following steps:

[0045] (1) The laterite nickel ore is crushed and sieved in sequence to obtain a laterite nickel ore sample with an average particle size of 80-120 mesh. Weigh 0.2-1.5g of the laterite nickel ore sample and place it in a platinum crucible or polytetrafluoroethylene crucible with a volume of 30-50mL. A refractory plate is set at the bottom of the crucible. Add 7-10mL of 40-60wt% sulfuric acid solution preheated to near boiling state. Shake the crucible until the sample is dispersed, then cover the crucible with the lid. Heat the crucible until the acid solution boils. Add 10-15mL of 30-50wt% hydrofluoric acid solution dropwise in batches. Continue to heat the crucible until the acid solution boils. Maintain a slight boiling state for 8-15min until the sample is completely decomposed to obtain the sample solution.

[0046] (2) Add 150-250 mL of deionized water, 8-12 mL of 40-60 wt% sulfuric acid solution, 4-6 mL of 60-80 wt% phosphoric acid solution and 20-30 mL of 20-25 wt% boric acid solution to a beaker and mix well. Transfer the sample solution to the beaker and add 3-6 drops of sodium diphenylamine sulfonate as an indicator to the resulting mixed solution.

[0047] (3) Titrate the mixed solution obtained in step (2) with potassium dichromate standard solution, and shake the solution continuously during the titration process. The titration endpoint is reached when the solution color changes to blue-purple.

[0048] (4) Calculate the ferrous content in the laterite nickel ore sample based on the amount of potassium dichromate standard solution consumed in step (3).

[0049] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific point values ​​included in the range.

[0050] Compared with related technologies, the beneficial effects of this application are as follows:

[0051] The detection method provided in this application allows for adjustment of sample volume and standard solution volume based on the ferrous content of laterite nickel ore samples, thus adapting to the analytical needs of samples with different concentration ranges. Specifically, the addition of phosphoric acid solution masks potential interference from ferric ions, helping to reduce the adverse effects of interfering factors on the analytical results and improving detection accuracy. Boric acid solution not only complexes fluorine in the solution but also accelerates the complete dissolution of the sample, further improving detection accuracy and stability. The mixed acid solutions used are all common and inexpensive reagents, avoiding the use of expensive equipment, reducing experimental costs, and improving the economic feasibility of the technology. The entire detection process is clear, requiring no complex instruments or advanced skills, making it easy for researchers and industry to accept and apply, facilitating large-scale promotion and application.

[0052] After reading and understanding the detailed description, other aspects can be understood. Detailed Implementation

[0053] The technical solution of this application will be further described below through specific implementation methods.

[0054] Example 1

[0055] This embodiment provides a method for detecting the ferrous content in laterite nickel ore, the method comprising the following steps:

[0056] (1) The laterite nickel ore was crushed and sieved in sequence to obtain a laterite nickel ore sample with an average particle size of 100 mesh. 0.5 g of the laterite nickel ore sample was weighed and placed in a 30 mL platinum crucible with a refractory plate at the bottom. 8 mL of 50 wt% sulfuric acid solution preheated to near boiling was added. The crucible was shaken until the sample was dispersed and then the crucible lid was covered. The crucible was heated until the acid solution boiled. 12 mL of 40 wt% hydrofluoric acid solution was added dropwise in batches. The crucible was heated until the acid solution boiled. The crucible was kept at a slight boiling state for 10 min until the sample was completely decomposed to obtain the sample solution.

[0057] (2) Add 200 mL of deionized water, 10 mL of 50 wt% sulfuric acid solution, 5 mL of 70 wt% phosphoric acid solution and 25 mL of 23 wt% boric acid solution to a beaker and mix well. Transfer the sample solution to the beaker and add 4 drops of sodium diphenylamine sulfonate as an indicator to the resulting mixed solution.

[0058] (3) Titrate the mixed solution obtained in step (2) with potassium dichromate standard solution, and shake the solution continuously during the titration process. The titration endpoint is reached when the solution color changes to blue-purple.

[0059] (4) Record the consumption of potassium dichromate standard solution in step (3) as 2.45 mL, and calculate the ferrous content in the laterite nickel ore sample as 0.32 wt%.

[0060] In this embodiment, the calculation formula for step (4) is as follows:

[0061] In the formula: ω is the ferrous content in the laterite nickel ore sample, wt%; V is the volume of potassium dichromate standard solution consumed in titrating the sample, mL; K1 = 1.28648, is the coefficient for the conversion of iron to ferrous iron; K2 = 0.50255, is the mass of ferrous iron equivalent to 1 mL of potassium dichromate standard solution, mg / mL; m is the mass of the sample, g.

[0062] Example 2

[0063] This embodiment provides a method for detecting the ferrous content in laterite nickel ore, the method comprising the following steps:

[0064] (1) The laterite nickel ore was crushed and sieved in sequence to obtain a laterite nickel ore sample with an average particle size of 80 mesh. 1.5 g of the laterite nickel ore sample was weighed and placed in a 50 mL polytetrafluoroethylene crucible with a refractory plate at the bottom. 10 mL of 60 wt% sulfuric acid solution preheated to near boiling was added. The crucible was shaken until the sample was dispersed and then the crucible lid was covered. The crucible was heated until the acid solution boiled. 15 mL of 50 wt% hydrofluoric acid solution was added dropwise in batches. The crucible was heated until the acid solution boiled. The crucible was kept at a slight boiling state for 15 min until the sample was completely decomposed to obtain the sample solution.

[0065] (2) Add 250 mL of deionized water, 12 mL of 60 wt% sulfuric acid solution, 6 mL of 80 wt% phosphoric acid solution and 30 mL of 25 wt% boric acid solution to a beaker and mix them evenly. Transfer the sample solution to the beaker and add 6 drops of sodium diphenylamine sulfonate as an indicator to the resulting mixed solution.

[0066] (3) Titrate the mixed solution obtained in step (2) with potassium dichromate standard solution, and shake the solution continuously during the titration process. The titration endpoint is reached when the solution color changes to blue-purple.

[0067] (4) Record the consumption of potassium dichromate standard solution in step (3) as 7.04 mL, and calculate the ferrous content in the laterite nickel ore sample as 0.30 wt%.

[0068] In this embodiment, the calculation formula for step (4) is as follows:

[0069] In the formula: ω is the ferrous content in the laterite nickel ore sample, wt%; V is the volume of potassium dichromate standard solution consumed in titrating the sample, mL; K1 = 1.28648, is the coefficient for the conversion of iron to ferrous iron; K2 = 0.50255, is the mass of ferrous iron equivalent to 1 mL of potassium dichromate standard solution, mg / mL; m is the mass of the sample, g.

[0070] Example 3

[0071] This embodiment provides a method for detecting the ferrous content in laterite nickel ore, the method comprising the following steps:

[0072] (1) The laterite nickel ore was crushed and sieved in sequence to obtain a laterite nickel ore sample with an average particle size of 120 mesh. 0.2 g of the laterite nickel ore sample was weighed and placed in a 30 mL platinum crucible with a refractory plate at the bottom. 7 mL of 40 wt% sulfuric acid solution preheated to near boiling was added. The crucible was shaken until the sample was dispersed and then the crucible lid was covered. The crucible was heated until the acid solution boiled. 10 mL of 30 wt% hydrofluoric acid solution was added dropwise in batches. The crucible was heated until the acid solution boiled. The crucible was kept at a slight boiling state for 8 min until the sample was completely decomposed to obtain the sample solution.

[0073] (2) Add 150 mL of deionized water, 8 mL of 40 wt% sulfuric acid solution, 4 mL of 60 wt% phosphoric acid solution and 20 mL of 20 wt% boric acid solution to a beaker and mix them evenly. Transfer the sample solution to the beaker and add 3 drops of sodium diphenylamine sulfonate as an indicator to the resulting mixed solution.

[0074] (3) Titrate the mixed solution obtained in step (2) with potassium dichromate standard solution, and shake the solution continuously during the titration process. The titration endpoint is reached when the solution color changes to blue-purple.

[0075] (4) Record the consumption of potassium dichromate standard solution in step (3) as 0.96 mL, and calculate the ferrous content in the laterite nickel ore sample as 0.31 wt%.

[0076] In this embodiment, the calculation formula for step (4) is as follows:

[0077] In the formula: ω is the ferrous content in the laterite nickel ore sample, wt%; V is the volume of potassium dichromate standard solution consumed in titrating the sample, mL; K1 = 1.28648, is the coefficient for the conversion of iron to ferrous iron; K2 = 0.50255, is the mass of ferrous iron equivalent to 1 mL of potassium dichromate standard solution, mg / mL; m is the mass of the sample, g.

[0078] Comparative Example 1

[0079] This comparative example provides a method for detecting the ferrous content in laterite nickel ore. Except that only sulfuric acid solution is added in step (1) and hydrofluoric acid solution is not added, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0080] Compared to Example 1, this example did not include hydrofluoric acid solution during the decomposition of laterite nickel ore, resulting in incomplete sample decomposition and a lower measured ferrous content.

[0081] Comparative Example 2

[0082] This comparative example provides a method for detecting the ferrous content in laterite nickel ore. Except for the absence of phosphoric acid solution in step (2), the other steps and conditions are the same as in Example 1, and therefore will not be repeated here.

[0083] Compared to Example 1, this example does not include phosphoric acid solution in the beaker, resulting in Fe... 3+ The color cannot be masked. This is because phosphoric acid can react with Fe... 3+ Formation of the complex ion [Fe(HPO4)2] - This complex ion is colorless and decreases Fe content. 3+ / Fe 2+ The redox potential can prevent Fe 3+ An oxidizing indicator is used to make the titration endpoint clear and stable. In this comparative example, the absence of phosphoric acid solution would lead to significant deviations in the experimental results.

[0084] Comparative Example 3

[0085] This comparative example provides a method for detecting the ferrous content in laterite nickel ore. Except for the absence of boric acid solution in step (2), the other steps and conditions are the same as in Example 1, and therefore will not be repeated here.

[0086] Compared to Example 1, this example does not add boric acid solution to the beaker, causing the remaining fluorine in the solution to react with Fe. 3+ Redox reactions occur, leading to significant deviations in experimental results.

[0087] Therefore, the detection method provided in this application can adjust the sample amount and standard solution volume according to the ferrous content of the laterite nickel ore sample, thereby adapting to the analytical needs of samples with different concentration ranges. Specifically, the addition of phosphoric acid solution can mask the interference of potential ferric ions, helping to reduce the adverse effects of interfering factors on the analytical results and improving the accuracy of detection; boric acid solution not only complexes fluorine in the solution but also helps to accelerate the complete dissolution of the sample, further improving the accuracy and stability of detection; the mixed acid solutions used are all common and inexpensive reagents, avoiding the use of expensive equipment, reducing experimental costs, and improving the economic feasibility of the technology; the entire detection process is clear, requiring no complex instruments or advanced skills, thus facilitating acceptance and application by researchers and industry, and promoting large-scale application.

[0088] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for detecting ferrous content in laterite nickel ore, comprising the following steps: (1) The laterite nickel ore sample was decomposed using the first mixed acid solution to obtain the sample solution; (2) Mix the second mixed acid solution and the sample solution obtained in step (1), and add sodium diphenylamine sulfonate as an indicator to the resulting mixed solution; (3) Titrate the mixed solution obtained in step (2) with potassium dichromate standard solution. The titration endpoint is reached when the solution color changes to blue-purple. (4) Calculate the ferrous content in the laterite nickel ore sample based on the amount of potassium dichromate standard solution consumed in step (3); In step (1), the first mixed acid solution includes sulfuric acid solution and hydrofluoric acid solution, and in step (2), the second mixed acid solution includes sulfuric acid solution, phosphoric acid solution and boric acid solution.

2. The detection method according to claim 1, wherein, The laterite nickel ore sample described in step (1) was crushed and screened before decomposition; Optionally, the average particle size of the laterite nickel ore sample in step (1) is 80-120 mesh.

3. The detection method according to claim 1 or 2, wherein, The decomposition in step (1) includes: weighing the laterite nickel ore sample and placing it in a crucible, adding sulfuric acid solution preheated to near boiling, shaking the crucible until the sample disperses, covering the crucible with the lid, heating the crucible until the acid solution boils, adding hydrofluoric acid solution dropwise, continuing to heat the crucible until the acid solution boils, maintaining a slight boiling state until the sample is completely decomposed.

4. The detection method according to claim 3, wherein, The hydrofluoric acid solution was added dropwise in batches; Optionally, a refractory plate is provided below the crucible.

5. The detection method according to claim 3 or 4, wherein, The weighing range of the laterite nickel ore sample is 0.2-1.5g; Optionally, the crucible includes a platinum crucible or a polytetrafluoroethylene crucible; Optionally, the volume of the crucible is 30-50 mL; Optionally, the concentration of the sulfuric acid solution is 40-60 wt%. Optionally, the volume of sulfuric acid solution added is 7-10 mL; Optionally, the concentration of the hydrofluoric acid solution is 30-50 wt%. Optionally, the volume of the hydrofluoric acid solution added is 10-15 mL; Optionally, the duration of the simmering state is 8-15 minutes.

6. The detection method according to any one of claims 1-5, wherein, The mixing in step (2) includes: adding deionized water, sulfuric acid solution, phosphoric acid solution and boric acid solution to a beaker beforehand and mixing them evenly, and then transferring the sample solution to the beaker.

7. The detection method according to claim 6, wherein, The volume of deionized water added is 150-250 mL; Optionally, the concentration of the sulfuric acid solution is 40-60 wt%. Optionally, the volume of the added sulfuric acid solution is 8-12 mL; Optionally, the concentration of the phosphoric acid solution is 60-80 wt%; Optionally, the volume of the added phosphoric acid solution is 4-6 mL; Optionally, the concentration of the boric acid solution is 20-25 wt%. Optionally, the volume of the boric acid solution added is 20-30 mL.

8. The detection method according to any one of claims 1-7, wherein, In step (2), the amount of sodium diphenylamine sulfonate added is 3-6 drops.

9. The detection method according to any one of claims 1-8, wherein, The titration process described in step (3) is accompanied by continuous shaking of the solution.

10. The detection method according to any one of claims 1-9, comprising the following steps: (1) The lateritic nickel ore is crushed and screened sequentially to obtain lateritic nickel with an average particle size of 80-120 mesh. For the mineral sample, weigh 0.2-1.5g of laterite nickel ore sample and place it in a 30-50mL platinum crucible or polytetrafluoroethylene crucible with a refractory plate underneath. Add 7-10mL of 40-60wt% sulfuric acid solution preheated to near boiling. Shake the crucible until the sample disperses, then cover the crucible with the lid. Heat the crucible until the acid solution boils. Add 10-15mL of 30-50wt% hydrofluoric acid solution dropwise in batches. Continue heating the crucible until the acid solution boils, and maintain a gentle boil for 8-15 minutes until the sample is completely decomposed to obtain the sample solution. (2) Add 150-250 mL of deionized water, 8-12 mL of 40-60 wt% sulfuric acid solution, 4-6 mL of 60-80 wt% phosphoric acid solution and 20-30 mL of 20-25 wt% boric acid solution to a beaker and mix well. Transfer the sample solution to the beaker and add 3-6 drops of sodium diphenylamine sulfonate as an indicator to the resulting mixed solution. (3) Titrate the mixed solution obtained in step (2) with potassium dichromate standard solution, and shake the solution continuously during the titration process. The titration endpoint is reached when the solution color changes to blue-purple. (4) Calculate the ferrous content in the laterite nickel ore sample based on the amount of potassium dichromate standard solution consumed in step (3).

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