Method for detecting content of boron in iron ore and application

Abstract

The invention belongs to the technical field of boron detection, and particularly relates to a method for detecting the content of boron in iron ore and application. The method comprises the following steps: adding a mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid into a to-be-detected iron ore sample, and completely decomposing the to-be-detected iron ore sample through microwave digestion to obtain a sample solution; adding calcium salt into the sample solution, adjusting the pH value, enabling fluorine ions in the sample solution to form calcium fluoride precipitates, enabling iron and niobium interference elements in the sample solution to form hydroxide precipitates, and filtering out the calcium fluoride precipitates and the hydroxide precipitates to obtain a filtrate without matrix interference; a standard addition method is adopted, a series of boron standard solutions are added into the filtrate, the spectral line intensity of the series of solutions at the position of 249.678 nm is measured, a working curve is established, and the boron content in the iron ore sample to be measured is calculated through an extrapolation method. The three major pain points of iron and niobium interference, fluorine corrosion and lengthy process are solved in series.

Description

Technical Field

[0001] This application belongs to the field of boron detection technology, and in particular relates to a method for detecting boron content in iron ore and its application. Background Technology

[0002] The current raw materials for blast furnace ironmaking are mainly magnetite, hematite, and limonite, all of which contain trace amounts of boron (0.0005 wt%–0.10 wt%). While trace amounts of boron can significantly improve the hardenability, strength, and wear resistance of steel, ≥0.005 wt% leads to grain boundary embrittlement, resulting in surface cracks, edge cracks, and even fracture bands during hot rolling, and a sharp drop in room temperature impact toughness. Therefore, boron content must be controlled below 0.003 wt% before entering the furnace, but there are currently no domestic or international standards for boron testing in iron ore.

[0003] Existing technology 1 (CN120890968A) uses the sodium peroxide fusion-spectrophotometric method, which requires backlighting for 10–16 hours for color development. It has a high detection limit, a lengthy process, and involves the danger of strong oxidants. Existing technology 2 (CN109406496A) uses (1+1) aqua regia to digest boron ore, but aqua regia cannot decompose iron ore, and its recommended wavelength of 249.773 nm is strongly overlapped by the spectral line of Fe at 249.772 nm. Existing technology 3 (CN10162) 9910A) Hydrochloric acid (1+1) is used to dissolve boron-magnesium ore, but it is insoluble in iron ore. The selected wavelength is 208.893 nm, but it is affected by B 208.884 nm and Ni 208.898 nm. Other existing technologies generally use nitric acid-hydrofluoric acid high pressure sealed for 24 hours to digest boron ore. Although the selected wavelength is 249.677 nm, Fe 249.653 nm and Nb 249.697 nm raise the baseline, resulting in insufficient accuracy for trace boron. In addition, a hydrofluoric acid resistant sample introduction system is required, which limits its widespread use. Summary of the Invention

[0004] This application provides a method and application for detecting boron content in iron ore to solve the following technical problem: how to quickly and accurately determine boron in blast furnace iron ore and eliminate interference from iron and niobium and fluorine corrosion.

[0005] In a first aspect, embodiments of this application provide a method for detecting boron content in blast furnace iron ore, characterized in that the method includes:

[0006] A mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid is added to the iron ore sample to be tested, and the sample is completely decomposed by microwave digestion to obtain a sample solution. Calcium salts are added to the sample solution and the pH is adjusted so that fluoride ions in the sample solution form calcium fluoride precipitate, and iron and niobium interfering elements in the sample solution form hydroxide precipitates. After filtering out the calcium fluoride precipitate and the hydroxide precipitate, a filtrate with matrix interference removed is obtained. A series of boron standard solutions were added to the filtrate using the standard addition method. The spectral intensity of the series of solutions at 249.678 nm was measured and a working curve was established. The boron content in the iron ore sample to be tested was calculated by extrapolation.

[0007] Optionally, the volume ratio of nitric acid, hydrochloric acid and hydrofluoric acid in the mixed acid is (3–5):(0.8–1.2):(0.8–1.2).

[0008] Optionally, the microwave digestion temperature is 200–230°C and the time is 20–40 min.

[0009] Optionally, the calcium salt is calcium carbonate, and the ratio of calcium carbonate to hydrofluoric acid is (1.0–2.0 g): 1 mL.

[0010] Optionally, the pH is adjusted by adding ammonia to the sample solution until the pH of the sample solution is 6.5–7.5.

[0011] Optionally, before filtration, the solution containing the calcium fluoride precipitate and the hydroxide precipitate is heated on a hot plate at 140–210°C for 5–15 minutes.

[0012] Optionally, the filtration uses slow-speed filter paper and the calcium fluoride precipitate and the hydroxide precipitate are washed with hot water 4–6 times.

[0013] Optionally, the concentration gradient of the series of boron standard solutions covers 0–0.10 wt%, and the concentration points include at least 0, 0.0050 wt%, 0.010 wt%, 0.030 wt%, 0.050 wt%, and 0.10 wt%.

[0014] Optionally, the spectral line intensity is measured using an inductively coupled plasma atomic emission spectrometer (ICP-AES). The measurement conditions for the ICP-AES are: power 1100–1200W, pump speed 35–45rpm, vertical observation height 8–13mm, cooling gas flow rate 0.9–1.1L / min, nebulizer pressure 0.25–0.35MPa, and integration time 5–15s. The sample weight of the iron ore to be tested was 0.08–0.12 g, and the volume was adjusted to 200 mL.

[0015] Secondly, embodiments of this application provide the use of a method for detecting boron content in iron ore as described in any of the first aspects, the method being applicable to the determination of boron content in magnetite, hematite, and limonite within the range of 0.0005wt%–0.10wt%.

[0016] The technical solutions provided in this application have the following advantages compared with the prior art: The continuous background and baseline elevation caused by Fe and Nb in the iron ore matrix at 249.678 nm, which drowns out trace B signals, are the core factors leading to "iron-niobium interference and insufficient boron accuracy." Simultaneously, the current high-pressure closed hydrofluoric acid system requires a fluoride-resistant sample introduction system and causes equipment corrosion, constituting another bottleneck limiting the widespread use of fluoride corrosion. In this application, HNO3-HCl-HF is first added to the mixed acid and digested under a microwave field: microwave heating causes the mineral lattice to disintegrate instantaneously, and HF specifically attacks the silicate and iron oxide framework, thereby simultaneously transferring Fe, Nb, and B into the solution, achieving "complete decomposition of iron ore" and reducing the time from 24 hours to <1 hour, thus laying the foundation for a homogeneous system for subsequent "simultaneous removal of the two major interferences."

[0017] Calcium salt was then added to the sample solution and the pH was adjusted: Ca 2+ With free F - Instantly generating and precipitating CaF2 crystal nuclei reduces the concentration of corrosive fluoride ions to a minimum, thus eliminating the need for a fluoride-resistant sample introduction system and allowing the use of a conventional glass coaxial nebulizer, overcoming the "fluoride corrosion" bottleneck; simultaneously, the adjusted pH approaches neutral, allowing Fe... 3+ Nb(V) coprecipitates in the form of Fe(OH)3 and Nb(OH)5, while borate ions remain in the liquid phase. This "coprecipitation traps" the two major spectral interference sources of iron and niobium in one step, thereby reducing the baseline background at 249.678 nm to near the level of pure water and eliminating the core defect of signal submersion caused by "iron-niobium overlap-baseline elevation".

[0018] Finally, the standard addition method - ICP-OES is adopted: a series of B standards are directly added to the "matrix-free" filtrate to make the calibration matrix completely consistent with the test solution, thereby offsetting the trace inhibition / enhancement effect that the residual matrix may bring. Then, the true concentration of the sample is obtained by extrapolation, avoiding the potential risk of "systematic deviation caused by matrix differences in the external standard method", and realizing "rapid and accurate determination of trace boron".

[0019] In summary, the embodiments of this application integrate four steps—microwave total decomposition, calcium salt defluorination, co-precipitation to remove iron and niobium, and standard addition correction—to solve the three major pain points of "iron and niobium interference, fluoride corrosion, and lengthy process." This allows for the first time, under conventional laboratory conditions, the quantitative limit of boron in blast furnace iron ore to below 0.0005 wt%, meeting the requirements for furnace front control. Its innovative approach lies in combining matrix separation and equipment corrosion prevention into one step using the concept of "simultaneous precipitation," and compensating for trace residual effects with the standard addition method, thus overcoming the limitations of existing technologies that are "individual and incomplete." Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The spectrum at B249.678 nm of the matrix-interference-free filtrate provided in this embodiment of the application; Figure 2 The spectrum at B249.678 nm is for a solution that has not undergone precipitation and whose matrix interference has not been removed. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0025] In a first aspect, embodiments of this application provide a method for detecting boron content in blast furnace iron ore, characterized in that the method includes: A mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid is added to the iron ore sample to be tested, and the sample is completely decomposed by microwave digestion to obtain a sample solution. Calcium salts are added to the sample solution and the pH is adjusted so that fluoride ions in the sample solution form calcium fluoride precipitate, and iron and niobium interfering elements in the sample solution form hydroxide precipitates. After filtering out the calcium fluoride precipitate and the hydroxide precipitate, a filtrate with matrix interference removed is obtained. A series of boron standard solutions were added to the filtrate using the standard addition method. The spectral intensity of the series of solutions at 249.678 nm was measured and a working curve was established. The boron content in the iron ore sample to be tested was calculated by extrapolation.

[0026] Definitions: "Iron ore sample to be tested": refers to any one or a mixture of magnetite, hematite, and limonite, which can be solid powder with a particle size ≤0.074mm after crushing and drying. "Microwave digestion": refers to the process of placing the iron ore sample to be tested and a mixed acid in a sealed microwave digestion vessel, using a microwave field to raise the temperature inside the vessel, thereby chemically decomposing the iron ore sample and obtaining a sample solution. "Series of boron standard solutions": refers to aqueous solutions of boron with known concentrations and gradient distributions, used in the standard addition method. "Spectral line intensity at 249.678nm": refers to the emission signal intensity measured by an inductively coupled plasma atomic emission spectrometer at a wavelength of 249.678nm, corresponding to the characteristic emission of boron.

[0027] A mixed acid mixture of nitric acid, hydrochloric acid, and hydrofluoric acid was added to the iron ore sample to be tested. Microwave digestion was then used to completely decompose the sample, yielding a sample solution. This process converted all boron, which might exist as borate or adsorbed form in the solid ore, into solution-state boric acid or fluoroboric acid. Calcium salts were then added to the sample solution, and the pH was adjusted to cause fluoride ions to precipitate as calcium fluoride. Simultaneously, iron and niobium interference elements in the sample solution precipitated as hydroxides, thus simultaneously solidifying fluoride ions, iron, and niobium interference elements into particles. After filtering out the calcium fluoride and hydroxide precipitates, a filtrate free of matrix interference was obtained, thereby preventing fluoride ions from interfering with volumetric flask and inductively coupled plasma atomic emission spectrometry (ICP-AES). The corrosion of the quartz sample introduction system is eliminated, and spectral overlap between iron and niobium at 249.678 nm is avoided. A standard addition method is employed, adding a series of boron standard solutions to the filtrate, measuring the spectral intensity of each solution at 249.678 nm, and establishing a working curve. The boron content in the iron ore sample is calculated by extrapolation, thus eliminating the influence of matrix residues and directly reading the boron content in the original ore. This overall scheme is the first to connect "mixed acid microwave digestion—calcium salt precipitation for fluoride removal—ammonia co-precipitation of iron and niobium—standard addition method ICP-OES" in series, thereby solving the technical problem of "how to quickly and accurately determine boron in blast furnace iron ore and eliminate iron-niobium interference and fluoride corrosion."

[0028] In some embodiments, the volume ratio of nitric acid, hydrochloric acid and hydrofluoric acid in the mixed acid is (3–5):(0.8–1.2):(0.8–1.2).

[0029] The volume ratio of nitric acid, hydrochloric acid, and hydrofluoric acid in the mixed acid is (3–5):(0.8–1.2):(0.8–1.2). This ensures that nitric acid provides the main oxidizing power, while hydrochloric acid provides chloride ions to synergistically complex iron, and hydrofluoric acid provides fluoride ions to decompose silicates, thereby ensuring the complete decomposition of the iron ore sample during the microwave digestion step. This ratio range avoids excessive hydrofluoric acid, which would lead to excessive subsequent calcium fluoride precipitation, thus returning to the endpoint of "eliminating iron-niobium interference and fluorine corrosion." Volume ratios include, but are not limited to, 3:0.8:0.8, 4:1:1, 5:1.2:1.2, etc.

[0030] In some embodiments, the microwave digestion temperature is 200–230°C and the time is 20–40 min.

[0031] Microwave digestion operates at temperatures of 200–230℃ for 20–40 minutes, providing sufficient energy to disrupt the iron ore lattice and ensure complete boron infiltration into the solution within a short time, thereby shortening the overall detection cycle. This temperature-time coupling range is lower than the traditional 24-hour high-pressure closed-loop acid dissolution but higher than atmospheric-pressure open-loop acid dissolution, thus achieving the goal of "rapid and accurate" results. Temperature-time combinations include, but are not limited to, 200℃-40 min, 210℃-35 min, 220℃-30 min, and 230℃-20 min.

[0032] In some embodiments, the calcium salt is calcium carbonate, and the ratio of calcium carbonate to hydrofluoric acid is (1.0–2.0):1 mL.

[0033] The calcium salt is calcium carbonate, and the ratio of calcium carbonate to the hydrofluoric acid is (1.0–2.0 g): 1 mL, thereby providing sufficient calcium ions to precipitate all fluoride ions in the sample solution as calcium fluoride precipitate, thus avoiding corrosion of glassware and quartz sample introduction system by free fluoride ions; this ratio range avoids fluoride residue due to insufficient calcium carbonate, and also avoids the introduction of excessive calcium carbonate into solid suspension, thus returning to the endpoint of "eliminating fluoride corrosion".

[0034] In some embodiments, the pH adjustment is performed by adding ammonia to the sample solution until the pH of the sample solution is 6.5–7.5.

[0035] The pH was adjusted by adding ammonia to the sample solution until the pH reached 6.5–7.5, which allowed iron and niobium interference elements to precipitate completely in the form of hydroxides, thus avoiding spectral overlap between iron and niobium at 249.678 nm. This pH range is lower than strong alkalinity, reducing the loss of borate ions co-precipitated with iron, while being higher than acidity, ensuring the hydrolysis of iron and niobium, thus returning to the endpoint of "eliminating iron and niobium interference".

[0036] In some embodiments, prior to filtration, the solution containing the calcium fluoride precipitate and the hydroxide precipitate is heated on a hot plate at 140–210°C for 5–15 minutes.

[0037] Before filtration, the solution containing calcium fluoride and hydroxide precipitates is heated on a hot plate at 140–210°C for 5–15 minutes. This promotes the aggregation and enlargement of precipitate particles, thereby increasing the filtration speed and reducing the risk of filter breakage. This heating range is below the boiling point of the solution, which would cause splashing, and above room temperature, it would prevent aggregation, thus returning to the endpoint of "fast and accurate" filtration. Temperature-time combinations include, but are not limited to, 140°C-15 min, 160°C-12 min, 180°C-10 min, 200°C-8 min, and 210°C-5 min.

[0038] In some embodiments, the filtration uses slow-speed filter paper and the calcium fluoride precipitate and the hydroxide precipitate are washed with hot water 4–6 times.

[0039] The filtration process uses slow-speed filter paper, and the calcium fluoride and hydroxide precipitates are washed 4–6 times with hot water. This physically retains all the precipitates and removes soluble boric acid adsorbed on the precipitate surface with hot water, thus avoiding boron loss and cross-contamination. This number of washes ensures that impurity ions are fully removed, thus returning to the endpoint of "accurate determination." The number of washes includes, but is not limited to, 4, 5, or 6 times.

[0040] In some embodiments, the concentration gradient of the series of boron standard solutions covers 0–0.10 wt%, and the concentration points include at least 0, 0.0050 wt%, 0.010 wt%, 0.030 wt%, 0.050 wt%, and 0.10 wt%.

[0041] The concentration gradient of the series of boron standard solutions covers 0–0.10 wt% and includes at least 0, 0.0050 wt%, 0.010 wt%, 0.030 wt%, 0.050 wt%, and 0.10 wt%. This allows the working curve to cover all possible boron contents in the iron ore sample being tested through the standard addition method extrapolation, thus ensuring that the calculation results fall within the calibration range. This gradient setting avoids extrapolation distortion caused by the absence of high concentration points, thus returning to the endpoint of "accurate determination".

[0042] In some embodiments, the spectral line intensity is measured using an inductively coupled plasma atomic emission spectrometer (ICP-AES) with the following measurement conditions: power 1100–1200 W, pump speed 35–45 rpm, vertical observation height 8–13 mm, cooling gas flow rate 0.9–1.1 L / min, nebulizer pressure 0.25–0.35 MPa, and integration time 5–15 s. The sample weight of the iron ore to be tested was 0.08–0.12 g, and the volume was adjusted to 200 mL.

[0043] Spectral line intensities were measured using an inductively coupled plasma atomic emission spectrometer (ICP-AES). The ICP-AES measurement conditions were: power 1100–1200 W, pump speed 35–45 rpm, vertical observation height 8–13 mm, cooling gas flow rate 0.9–1.1 L / min, nebulizer pressure 0.25–0.35 MPa, and integration time 5–15 s. This ensured a stable boron signal and suppressed baseline drift within the specified window, thereby improving the signal-to-noise ratio. This condition range avoided background enhancement due to excessive power and signal instability due to excessively short integration time, thus achieving the goal of "accurate measurement".

[0044] The iron ore sample to be tested is weighed at a rate of 0.08–0.12 g and diluted to a volume of 200 mL. This ensures that the boron signal is above the detection limit while keeping the solution salinity below the tolerance of the inductively coupled plasma atomic emission spectrometer, thus enabling direct sample injection. The weighing-volume combination includes, but is not limited to, 0.08 g–200 mL, 0.10 g–200 mL, and 0.12 g–200 mL.

[0045] Secondly, embodiments of this application provide the use of a method for detecting boron content in iron ore as described in any of the first aspects, the method being applicable to the determination of boron content in magnetite, hematite, and limonite within the range of 0.0005wt%–0.10wt%.

[0046] This method is applicable to the determination of boron content in magnetite, hematite, and limonite within the range of 0.0005 wt%–0.10 wt%, thus covering the entire range required for boron control in blast furnace feedstocks. This weighing-volume coupling range avoids both insufficient sample volume leading to a low signal and insufficient volume leading to salting out, thus returning to the endpoint of "rapid and accurate determination." Examples of applicable boron content ranges include, but are not limited to, 0.0005 wt%, 0.0010 wt%, 0.0050 wt%, 0.010 wt%, 0.050 wt%, and 0.10 wt%.

[0047] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0048] Example 1 A method for detecting boron content in iron ore used in blast furnaces, the method comprising: Add a mixture of 4 mL nitric acid, 1 mL hydrochloric acid and 1 mL hydrofluoric acid to 0.1000 g of iron ore sample to be tested. Then, use a microwave digester to keep the sample at 220℃ for 30 min to completely decompose the iron ore sample and obtain a sample solution. The sample solution was transferred to a 300 mL polytetrafluoroethylene beaker. 1.5 g of calcium carbonate was added to the sample solution and ammonia was added dropwise to adjust the pH until iron and niobium interfering elements formed hydroxide precipitates, and fluoride ions formed calcium fluoride precipitates. The polytetrafluoroethylene beaker was heated on a hot plate at 150-200 °C for 10 min. The calcium fluoride precipitate and the hydroxide precipitate were then filtered out using slow-speed filter paper to obtain a filtrate with matrix interference removed. Take 6 parallel filtrates (each equivalent to 0.1000g of sample) and place them in 200mL volumetric flasks. Add 0, 0.50, 1.00, 3.00, 5.00, and 10.00 mL of 10µg / mL boron standard solution to each flask in sequence, and dilute to volume with ultrapure water.

[0049] The intensity of spectral lines in each solution was measured at 249.678 nm using an inductively coupled plasma atomic emission spectrometer. A working curve was established with boron concentration as the abscissa and spectral line intensity as the ordinate. The boron content in the iron ore to be tested was calculated to be 0.0035 wt% by extrapolation.

[0050] Comparative Example 1 A method for detecting boron content in iron ore used in blast furnaces, the method comprising: Sodium peroxide was added to 0.2000g of the iron ore sample to be tested, and the sample was decomposed by melting to obtain a melt. A crucible containing the melt was immersed in a beaker containing deionized water, and the mixture was heated to dissolve the components of the melt into the water in the beaker. The crucible was then removed. Ethanol was added to the beaker, and the mixture was boiled for 3–5 minutes. After cooling, the solution was diluted with water to 500ml, mixed well, and allowed to stand. The resulting solution was filtered to obtain the first filtrate. 100ml of the first filtrate was transferred to adjust the pH to acidic, and sodium peroxide was added. After hydrogenation, heat to a gentle boil, maintain gentle boiling for 20-40 minutes, and then cool to 60-80°C. Add barium carbonate paste to the resulting solution, continue heating to a boil, maintain gentle boiling for 1-3 minutes, and then cool. Dilute the resulting solution with water to 100 ml, shake well, and filter to obtain a second filtrate. Then take 25 ml of the second filtrate, develop the color using an ammonium acetate-hydrochloric acid-color reagent system, dilute with water to 50 ml, place the color reagent in a backlit area and let it stand for 10-16 hours, and then measure the absorbance at 420 nm using a spectrophotometer. The boron content in the iron ore sample was calculated to be 0.008% based on the working curve.

[0051] Comparative Example 2 A method for detecting boron content in iron ore used in blast furnaces, the method comprising: Add 20 mL of (1+1) aqua regia to 0.1000 g of iron ore sample to be tested, and heat the sample to a gentle boil for 30 min to obtain the sample solution. After the sample solution was diluted to 100 mL in a volumetric flask, the intensity of the boron spectral line was measured at 249.773 nm using an inductively coupled plasma atomic emission spectrometer. The boron content in the iron ore sample was calculated to be 4.76% using the external standard method.

[0052] Comparative Example 3 A method for detecting boron content in iron ore used in blast furnaces, the method comprising: Add 15 mL of hydrochloric acid (1+1) to 0.1000 g of iron ore sample to be tested, and heat at low temperature for 30 min to obtain sample solution; After the sample solution was diluted to 100 mL in a volumetric flask, the intensity of the boron spectral line was measured at 208.893 nm using an inductively coupled plasma atomic emission spectrometer. The boron content in the iron ore sample was calculated to be 0.0030% using the external standard method. However, the signal strength was low and the stability was poor.

[0053] Comparative Example 4 A method for detecting boron content in iron ore used in blast furnaces, the method comprising: Add 2 mL of nitric acid and 2 mL of hydrofluoric acid to 0.1000 g of iron ore sample to be tested, place it in a sealed sample dissolving vessel and keep it at 190℃ for 24 h to obtain the sample solution, and make up to 100 mL in a volumetric flask. The sample solution was introduced into an inductively coupled plasma atomic emission spectrometer using a hydrofluoric acid resistant injection system, and the boron spectral line intensity was measured at 249.677 nm. The boron content in the iron ore sample was calculated to be 0.0035% using the external standard method.

[0054] III. Results Data Experimental methods for evaluating results: Instrument: Inductively coupled plasma atomic emission spectrometer, power 1150W, pump speed 40rpm, observation height 9mm, cooling gas flow rate 1.0L / min, nebulizer pressure 0.3MPa, integration time 10s.

[0055] Spectral line analysis: 249.678 nm.

[0056] Standard addition method procedure: Add 0, 0.50, 1.00, 3.00, 5.00, and 10.00 mL of 10 µg / mL boron standard solution to six parallel filtrates, respectively, and dilute to 200 mL. Measure the net spectral intensity. Plot the intensity on the ordinate and the boron concentration on the abscissa. The distance from the intersection of the extrapolated line and the abscissa to the origin is the boron content of the sample.

[0057] Table 1. Effect data of each embodiment and comparative example.

[0058] As shown in Table 1, the technological advancements of this application's technical solution compared to the comparative example include: 1. Stable test data; 2. The data accuracy is good, consistent with Comparative Example 4, but it saves more time and does not require hydrofluoric acid resistant systems, making it more universally applicable.

[0059] Detailed description of the attached diagram: Figure 1 The spectrum at B249.678 nm of the matrix-interference-free filtrate provided in this embodiment of the application; Figure 2 The spectrum at B249.678 nm is for a solution that has not undergone precipitation and whose matrix interference has not been removed.

[0060] By comparison Figure 1 (The filtrate after precipitation and removal of matrix interference) and Figure 2 From the spectrum at B249.678 nm of the solution (without precipitation or removal of matrix interference), we can conclude that: Signal strength differences: Figure 2The spectral signal intensity (peak value exceeding 400) without matrix interference removal is much higher than... Figure 1 The spectral signal intensity (peak value approximately 300) indicates that matrix interference significantly enhances the spectral response at this wavelength; Baseline stability: Figure 1 The baseline is more stable, while Figure 2 There are interference peaks on both sides and the baseline fluctuates greatly, which shows that the spectral baseline is more stable and less interference is achieved after removing matrix interference. Corrected peak signal value: Figure 1 The corrected peak signal value (46.33) is much lower than Figure 2 (64.84) ​​further illustrates that matrix interference amplifies the signal interference of the target element, and precipitation treatment can effectively reduce the influence of the matrix on the detection of element B.

[0061] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for detecting boron content in iron ore, characterized in that, The method includes: A mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid is added to the iron ore sample to be tested, and the sample is completely decomposed by microwave digestion to obtain a sample solution. Calcium salts are added to the sample solution and the pH is adjusted so that fluoride ions in the sample solution form calcium fluoride precipitate, and iron and niobium interfering elements in the sample solution form hydroxide precipitates. After filtering out the calcium fluoride precipitate and the hydroxide precipitate, a filtrate with matrix interference removed is obtained. A series of boron standard solutions were added to the filtrate using the standard addition method. The spectral intensity of the series of solutions at 249.678 nm was measured and a working curve was established. The boron content in the iron ore sample to be tested was calculated by extrapolation.

2. The method according to claim 1, characterized in that, The volume ratio of nitric acid, hydrochloric acid and hydrofluoric acid in the mixed acid is (3–5):(0.8–1.2):(0.8–1.2).

3. The method according to claim 1, characterized in that, The microwave digestion temperature is 200–230℃ and the time is 20–40 min.

4. The method according to claim 1, characterized in that, The calcium salt is calcium carbonate, and the ratio of calcium carbonate to hydrofluoric acid is (1.0–2.0 g): 1 mL.

5. The method according to claim 1, characterized in that, The pH is adjusted by adding ammonia water dropwise to the sample solution until the pH of the sample solution is 6.5–7.

5.

6. The method according to claim 1, characterized in that, Before filtration, the solution containing the calcium fluoride precipitate and the hydroxide precipitate is heated on a hot plate at 140–210°C for 5–15 minutes.

7. The method according to claim 1, characterized in that, The filtration process uses slow-speed filter paper and washes the calcium fluoride precipitate and the hydroxide precipitate with hot water 4–6 times.

8. The method according to claim 1, characterized in that, The concentration gradient of the series of boron standard solutions covers 0–0.10 wt%, and the concentration points include at least 0, 0.0050 wt%, 0.010 wt%, 0.030 wt%, 0.050 wt%, and 0.10 wt%.

9. The method according to claim 1, characterized in that, The spectral line intensities were measured using an inductively coupled plasma atomic emission spectrometer (ICP-AES). The ICP-AES measurement conditions were: power 1100–1200W, pump speed 35–45rpm, vertical observation height 8–13mm, cooling gas flow rate 0.9–1.1L / min, nebulizer pressure 0.25–0.35MPa, and integration time 5–15s. The sample weight of the iron ore to be tested was 0.08–0.12 g, and the volume was adjusted to 200 mL.

10. Use of a method for detecting boron content in iron ore according to any one of claims 1-9, wherein the method is applicable to the determination of boron content in magnetite, hematite and limonite in the range of 0.0005wt%–0.10wt%.

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