Quantitative characterization method for rare earth content in blast furnace pig iron
By crushing, digesting, filtering, and melting blast furnace pig iron, combined with ICP-MS determination, the problem of inaccurate determination of rare earth content in blast furnace pig iron in existing technologies has been solved, and comprehensive analysis and accurate determination of rare earth elements in various phases of pig iron have been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INNER MONGOLIA UNIV OF SCI & TECH
- Filing Date
- 2026-04-14
- Publication Date
- 2026-05-12
AI Technical Summary
Existing methods for determining rare earth content cannot accurately measure the rare earth content in blast furnace pig iron, especially neglecting the rare earth element content in the graphite phase.
The method involved crushing blast furnace pig iron samples into granules, digesting them in concentrated hydrochloric acid, filtering them, mixing and melting the filter residue with KOH and K2CO3, rinsing with HCl and deionized water, adding concentrated hydrochloric acid to clarify the suspension, and then determining the concentration of rare earth elements using inductively coupled plasma mass spectrometry (ICP-MS).
This method enables comprehensive analysis of the content of rare earth elements in each phase of blast furnace pig iron, ensuring the accuracy of the measurement results. Furthermore, the experimental process is safe, the pretreatment is efficient, and the reagents are inexpensive and easy to store.
Smart Images
Figure CN122016994A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of materials analysis technology, specifically, it relates to a quantitative characterization method for the rare earth content in blast furnace pig iron. Background Technology
[0002] The Bayan Obo mine, the world's largest associated deposit of iron, rare earth elements, and niobium, contains abundant valuable elements. With the continuous development of science and technology, research on the Bayan Obo mine has become a hot topic in the scientific community. As one of the main iron ore sources for Baotou Steel Group, trace amounts of rare earth elements from the Bayan Obo mine were discovered in the 1990s to remain in steel products after the iron and steel metallurgical process. Recent studies on the inheritance behavior of associated rare earth elements in the Bayan Obo mine during the iron and steel metallurgical process have revealed that trace amounts of rare earth elements associated with iron concentrate remain in the blast furnace ironmaking process and enter the converter steelmaking process. This finding differs from the traditional thermodynamic explanation that rare earth oxides in iron concentrate cannot be reduced to molten iron and instead enter the blast furnace slag during blast furnace ironmaking. Therefore, the blast furnace ironmaking process is one of the key processes for whether associated rare earth elements from the Bayan Obo mine can be inherited into steel products. Therefore, accurately and quantitatively analyzing the rare earth content in blast furnace molten iron is a key characterization technique for proving whether rare earth elements associated with iron concentrate can remain in molten iron after blast furnace ironmaking.
[0003] Currently, the main methods for determining the rare earth content in steel materials include: In 1994, the State Bureau of Technical Supervision issued GB / T 223.49-1994, "Chemical Analysis Methods for Iron and Steel and Alloys: Extraction and Separation - Azochlorophosphine mA Spectrophotometric Method for Determination of Total Rare Earth Content." This standard uses hydrochloric acid + nitric acid digestion, followed by extraction to separate rare earth ions from iron ions, and then colorimetric determination of the rare earth content in steel materials using a spectrophotometer. The determination range is 0.0010%–0.20%. In 2022, the State Administration for Market Regulation and the Standardization Administration of China issued GB / T 26416.1-2022, "Chemical Analysis Methods for Rare Earth Ferroalloys - Part 1: Determination of Total Rare Earth Content." This method uses the oxalic acid gravimetric method, EDTA titration method, and inductively coupled plasma atomic emission spectrometry. These methods are suitable for measuring the rare earth content in rare earth ferroalloys, with a measurement range of 1.00%–20.00%. Wang Yapeng et al. of Benxi Iron & Steel disclosed a method for detecting cerium content in rare earth steel. This method uses an electrolytic method combined with a chemical separation method to determine the content of rare earth cerium in oxides, sulfides, and sulfur oxides in steel, and finally sums them to obtain the total rare earth cerium content in the steel. This method actually measures the rare earth content in inclusions in the steel, ignoring the trace amounts of rare earth cerium dissolved in the steel. Zhang Jie et al. of Xinyu Iron & Steel used nitric acid, hydrochloric acid, and perchloric acid to digest steel samples and then used spectrophotometry to determine the rare earth content in the steel. This method is also only suitable for determining the total amount of rare earth in steel. The literature, including "Rapid Determination of Total Rare Earth Content in Ductile Iron," "Determination of Total Rare Earth Content in Ductile Iron—Direct Spectrophotometric Method of Azochlorophosphine III," "Determination of Trace Rare Earth Content in Ductile Iron—Direct Spectrophotometric Method of Tribromoazophosphine," "Rapid Analysis of Total Rare Earth Content in Ductile Iron and Low Alloy Steel—Oxalic Acid Masking—Direct Spectrophotometric Method of Azochlorophosphine III," and "Rapid Determination of Total Rare Earth Content in Ductile Iron—Extraction-Colorimetric Method," all employ acid dissolution to digest the cast iron sample before determining the rare earth ion concentration in the solution, and finally converting it into the rare earth content in the cast iron. These methods share a common problem: they neglect the rare earth element content in the graphite phase within the cast iron. It is clear that existing methods for determining the rare earth content in steel materials can only determine the rare earth content in the steel itself or the rare earth content in the graphite phase of cast iron materials. However, blast furnace pig iron, similar to cast iron, contains a large amount of graphite phase due to its high carbon content. Existing methods for determining rare earth content often overlook the rare earth content in the graphite phase, thus failing to obtain the accurate rare earth content in blast furnace pig iron.
[0004] In view of this, the present invention is proposed. Summary of the Invention
[0005] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:
[0006] A quantitative characterization method for rare earth content in blast furnace pig iron includes the following steps:
[0007] (1) Crush the blast furnace pig iron sample into granules;
[0008] (2) Place the above granular pig iron sample into a conical flask or beaker containing concentrated hydrochloric acid and digest it at a temperature of 50 ℃~95 ℃. After digestion, filter the solution.
[0009] (3) Collect the filtered solution into a beaker and let it cool naturally to room temperature. Then transfer it to a volumetric flask and make up to volume for testing.
[0010] (4) Transfer the filter residue collected after filtration to a covered crucible and add KOH and K2CO3 and mix well. Then cover the crucible and put it into a muffle furnace to heat and melt.
[0011] (5) Take out the crucible after heating and heat preservation, and rinse the crucible lid and inside the crucible alternately with 1% to 10% HCl aqueous solution and deionized water until clean, and collect the rinsed suspension into a beaker;
[0012] (6) Stir the above suspension and heat it to 70 ℃~95 ℃, then add concentrated hydrochloric acid while stirring until the suspension becomes a clear aqueous solution. Then stop heating and let it cool naturally to room temperature. Transfer the above solution to a volumetric flask and make up to volume for testing.
[0013] (7) The concentration of rare earth elements in the solution to be tested after the above volume is determined by inductively coupled plasma mass spectrometry (ICP-MS), and the amount of rare earth elements dissolved in the steel material can be calculated.
[0014] In a preferred embodiment of the present invention, the particle size range of the granular pig iron in step (1) is 1 mm to 10 mm.
[0015] As a preferred embodiment of the present invention, the digestion process in the temperature range of 50 ℃ to 95 ℃ in step (2) can be carried out on a water bath, electric hot plate or resistance wire furnace. At the same time, deionized water needs to be added intermittently to the conical flask or beaker to prevent the liquid in the container from being evaporated.
[0016] In a preferred embodiment of the present invention, the filtration process in step (2) uses an organic filter membrane with a pore size of 0.2 μm to 0.4 μm in a sand core filter or uses 3 to 6 layers of slow quantitative filter paper in a Buchner funnel for vacuum-accelerated filtration. After the first filtration, 10 mL to 15 mL of deionized water is added to continue rinsing the filter residue 3 to 5 times and then filtering.
[0017] In a preferred embodiment of the present invention, in step (3), after the solution is collected into the beaker and the volume is adjusted, after the first transfer of the solution, the filtration flask is rinsed with 10 mL to 15 mL of deionized water 3 to 5 times. Then, when transferring the solution from the beaker to the volumetric flask, after the first transfer of the solution, the beaker is rinsed with 5 mL to 10 mL of deionized water 3 to 5 times. Finally, the concave liquid surface of the solution is filled to the graduation line of the volumetric flask with deionized water.
[0018] In a preferred embodiment of the present invention, the filter residue in step (4) is transferred together with the filter membrane or quantitative filter paper into a crucible. The crucible can be made of nickel, silver or platinum metal. The ratio of the amount of KOH and K2CO3 added to the mass of the blast furnace pig iron sample is (1.5-3):(1-1.5):1. The melting temperature of the muffle furnace is 600 ℃ to 900 ℃, and the holding time is 25 min to 60 min.
[0019] In a preferred embodiment of the present invention, the volume adjustment process in step (6) involves rinsing the beaker 3 to 5 times with 10 mL to 15 mL of deionized water after the initial transfer of the solution, and finally filling the concave meniscus of the solution to the graduation line of the volumetric flask with deionized water.
[0020] In a preferred embodiment of the present invention, the quantitative process described in step (7), after the concentration is measured using an inductively coupled plasma mass spectrometer, can be expressed by the formula...
[0021] Perform measurements;
[0022] W represents the rare earth element content in the blast furnace pig iron; C1 represents the concentration of rare earth elements in the solution after the filtrate is brought to a constant volume; V1 represents the volume of the filtrate after the filtrate is brought to a constant volume; C2 represents the concentration of rare earth elements in the solution after the filter residue is brought to a constant volume; V2 represents the volume of the solution after the filter residue is brought to a constant volume; and M represents the mass of the sample after electrolysis.
[0023] Compared with the prior art, the present invention has the following advantages:
[0024] This technical solution first involves crushing the blast furnace pig iron sample into granules and heating it in concentrated hydrochloric acid for digestion. After digestion, the solution is filtered, the filtrate is collected, and the volume is adjusted for analysis. Then, the filter residue is reacted with KOH and... The mixture is placed in a crucible and melted in a muffle furnace. The molten material is then rinsed alternately with HCl aqueous solution and deionized water. The collected suspension is clarified by adding concentrated hydrochloric acid and cooled to a final volume for analysis. Finally, the concentration of rare earth elements in the test solution is measured using inductively coupled plasma mass spectrometry (ICP-MS). The rare earth content in blast furnace pig iron can then be calculated using a formula. This invention enables comprehensive analysis of the rare earth element content in various phases of blast furnace pig iron in laboratory research and production practice, thus accurately determining the rare earth content in blast furnace pig iron. It features a safe experimental process, efficient pretreatment, and inexpensive and easily stored reagents.
[0025] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description
[0026] In the attached diagram:
[0027] Figure 1 This is a flowchart of the present invention. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention.
[0029] Example 1
[0030] A quantitative characterization method for rare earth content in blast furnace pig iron, such as... Figure 1 As shown, it includes the following steps:
[0031] (1) A 5 g sample of pig iron produced by the No. 1 blast furnace of a certain enterprise was crushed into granular samples with a particle size of 2 mm to 5 mm.
[0032] (2) Place the above granular pig iron sample into a conical flask containing 50 mL of concentrated hydrochloric acid and digest it in a water bath at 80 °C. During the process, add deionized water to the conical flask intermittently to prevent the liquid in the container from being evaporated. After digestion, filter the solution.
[0033] The filtration process described in step (2) uses an organic filter membrane with a pore size of 0.22 μm to perform vacuum filtration in a sand core filter. After the first filtration is completed, 10 mL of deionized water is added to rinse the filter residue 4 times and then filter again.
[0034] (3) Collect the filtered solution into a beaker and let it cool naturally to room temperature. Then transfer it to a volumetric flask and make up to volume for testing.
[0035] In step (3), after the filtered solution is collected into the beaker and the volume is adjusted, after the first transfer of the solution, the filtration flask is rinsed with 10 mL of deionized water four times. Then, when transferring the solution from the beaker to the volumetric flask, after the first transfer of the solution, the beaker is rinsed with 10 mL of deionized water four times. Finally, the concave liquid surface of the solution is filled to the graduation line of the volumetric flask with deionized water.
[0036] (4) Transfer the filter residue collected after filtration to a covered crucible and add KOH and K2CO3 and mix well. Then cover the crucible and put it into a muffle furnace to heat and melt.
[0037] The filter residue mentioned in step (4) is transferred together with the filter membrane or quantitative filter paper into the nickel crucible. The ratio of the amount of KOH and K2CO3 added to the mass of the blast furnace pig iron sample is 2:1:1. The melting temperature of the muffle furnace is 650 ℃ and the holding time is 35 min.
[0038] (5) Take out the crucible after heating and heat preservation, and rinse the crucible lid and inside the crucible alternately with 1% HCl aqueous solution and deionized water until clean, and collect the rinsed suspension into a beaker.
[0039] (6) Stir the above suspension and heat it to 90 °C. Add concentrated hydrochloric acid while stirring until the suspension becomes a clear aqueous solution. Then stop heating and let it cool naturally to room temperature. Transfer the solution to a volumetric flask and make up to volume for testing.
[0040] In step (6), after the solution is transferred for the first time, the beaker is rinsed four times with 10 mL of deionized water. Finally, the concave meniscus of the solution is filled with deionized water to the graduation line of the volumetric flask.
[0041] (7) The concentration of rare earth elements in the solution to be tested after the above-mentioned volume adjustment is measured by inductively coupled plasma mass spectrometry (ICP-MS), and the amount of rare earth elements dissolved in the steel material can be calculated. The quantitative process described in step (7) can be quantified by formula (1) after the concentration is measured by inductively coupled plasma mass spectrometry.
[0042] (1)
[0043] In the formula, W is the content of rare earth elements in blast furnace pig iron; C1 is the concentration of rare earth elements in the solution after the filtrate is brought to a fixed volume; V1 is the volume of the filtrate after the filtrate is brought to a fixed volume; C2 is the concentration of rare earth elements in the solution after the filter residue is brought to a fixed volume; V2 is the volume of the solution after the filter residue is brought to a fixed volume; and M is the mass of the sample after electrolysis.
[0044] Finally, the contents of rare earth elements La and Ce in the above blast furnace pig iron were found to be 4.1 ppm and 2.2 ppm, respectively.
[0045] Example 2
[0046] A quantitative characterization method for rare earth content in blast furnace pig iron, such as... Figure 1 As shown, it includes the following steps:
[0047] (1) A 5 g sample of pig iron produced by blast furnace No. 6 of a certain enterprise was crushed into granular samples with a particle size of 4 mm to 8 mm.
[0048] (2) Place the above granular pig iron sample into a beaker containing 60 mL of concentrated hydrochloric acid and digest it in a water bath at 85 °C. During the process, add deionized water to the beaker intermittently to prevent the liquid in the container from being evaporated. After digestion, filter the solution.
[0049] Preferably, the filtration process described in step (2) uses four layers of slow quantitative filter paper to perform vacuum filtration in a Buchner funnel. After the first filtration, 15 mL of deionized water is added to rinse the filter residue three times and then filtration is performed again.
[0050] (3) Collect the filtered solution into a beaker and let it cool naturally to room temperature. Then transfer it to a volumetric flask and make up to volume for testing.
[0051] In step (3), after the filtered solution is collected into the beaker and the volume is adjusted, after the first transfer of the solution, the filtration flask is rinsed three times with 15 mL of deionized water. Then, when transferring the solution from the beaker to the volumetric flask, after the first transfer of the solution, the beaker is rinsed three times with 15 mL of deionized water. Finally, the concave liquid surface of the solution is filled to the graduation line of the volumetric flask with deionized water.
[0052] (4) Transfer the filter residue collected after filtration to a covered crucible and add KOH and K2CO3 and mix well. Then cover the crucible and put it into a muffle furnace to heat and melt.
[0053] Preferably, the filter residue in step (4) is transferred together with the filter membrane or quantitative filter paper into a silver crucible, the ratio of the amount of KOH and K2CO3 added to the mass of the blast furnace pig iron sample is 2.5:1.5:1, the melting temperature of the muffle furnace is 750 ℃, and the holding time is 45 min.
[0054] (5) Take out the crucible after heating and heat preservation, and rinse the crucible lid and inside the crucible alternately with 3% HCl aqueous solution and deionized water until clean, and collect the rinsed suspension into a beaker.
[0055] (6) After stirring the above suspension and heating it to 93 °C, add concentrated hydrochloric acid while stirring until the suspension becomes a clear aqueous solution. Then stop heating and allow it to cool naturally to room temperature. Transfer the solution to a volumetric flask and make up to volume for testing. In the volume-making process described in step (6), after the first transfer of the solution, rinse the beaker three times with 15 mL of deionized water. Finally, use deionized water to fill the concave meniscus of the solution to the graduation mark on the volumetric flask.
[0056] (7) The concentration of rare earth elements in the solution to be tested after the above volume is determined by inductively coupled plasma mass spectrometry (ICP-MS), and the amount of rare earth elements dissolved in the steel material can be calculated.
[0057] Preferably, in the quantitative process described in step (7), after the concentration is measured by inductively coupled plasma mass spectrometry, the quantification can be performed using formula (1).
[0058] (1)
[0059] In the formula, W represents the content of rare earth elements in blast furnace pig iron; The concentration of rare earth elements in the solution after the filtrate has been diluted to the desired volume; The volume of the filtrate after dilution; The concentration of rare earth elements in the solution after the filter residue has been prepared into a solution and brought to volume; M represents the volume of the solution prepared from the filter residue and brought to a constant volume; M represents the mass of the sample after electrolysis. Finally, the contents of rare earth elements La and Ce in the above blast furnace pig iron were found to be 2.8 ppm and 2.5 ppm, respectively.
[0060] This technical solution first involves crushing the blast furnace pig iron sample into granules and heating it in concentrated hydrochloric acid for digestion. After digestion, the solution is filtered, the filtrate is collected, and the volume is adjusted for analysis. Then, the filter residue is reacted with KOH and... The mixture is placed in a crucible and melted in a muffle furnace. The molten material is then rinsed alternately with HCl aqueous solution and deionized water. The collected suspension is clarified by adding concentrated hydrochloric acid and cooled to a final volume for analysis. Finally, the concentration of rare earth elements in the test solution is measured using inductively coupled plasma mass spectrometry (ICP-MS). The rare earth content in blast furnace pig iron can then be calculated using a formula. This invention enables comprehensive analysis of the rare earth element content in various phases of blast furnace pig iron in laboratory research and production practice, thus accurately determining the rare earth content in blast furnace pig iron. It features a safe experimental process, efficient pretreatment, and inexpensive and easily stored reagents.
[0061] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.
Claims
1. A method for quantitatively characterizing the rare earth content in blast furnace pig iron, characterized in that, Includes the following steps: (1) Crush the blast furnace pig iron sample into granules; (2) Place the above granular pig iron sample into a conical flask or beaker containing concentrated hydrochloric acid and digest it at a temperature of 50 ℃~95 ℃. After digestion, filter the solution. (3) Collect the filtered solution into a beaker and let it cool naturally to room temperature. Then transfer it to a volumetric flask and make up to volume for testing. (4) Transfer the filter residue collected after filtration to a covered crucible and add KOH and K2CO3 and mix well. Then cover the crucible and put it into a muffle furnace to heat and melt. (5) Take out the crucible after heating and heat preservation, and rinse the crucible lid and inside the crucible alternately with 1% to 10% HCl aqueous solution and deionized water until clean, and collect the rinsed suspension into a beaker; (6) Stir the above suspension and heat it to 70 ℃~95 ℃, then add concentrated hydrochloric acid while stirring until the suspension becomes a clear aqueous solution. Then stop heating and let it cool naturally to room temperature. Transfer the above solution to a volumetric flask and make up to volume for testing. (7) The concentration of rare earth elements in the solution to be tested after the above volume is determined by inductively coupled plasma mass spectrometry (ICP-MS), and the amount of rare earth elements dissolved in the steel material can be calculated.
2. The method for quantitative characterization of rare earth content in blast furnace pig iron according to claim 1, characterized in that, The particle size range of the granular pig iron in step (1) is 1 mm to 10 mm.
3. The method for quantitative characterization of rare earth content in blast furnace pig iron according to claim 1, characterized in that, The digestion process in step (2) with a temperature range of 50 ℃ to 95 ℃ can be carried out in a water bath, electric hot plate or resistance wire furnace. At the same time, deionized water needs to be added intermittently to the conical flask or beaker to prevent the liquid in the container from being evaporated.
4. The method for quantitative characterization of rare earth content in blast furnace pig iron according to claim 1, characterized in that, The filtration process described in step (2) involves using an organic filter membrane with a pore size of 0.2 μm to 0.4 μm in a sand core filter or using 3 to 6 layers of slow quantitative filter paper in a Buchner funnel for vacuum-accelerated filtration. After the first filtration, 10 mL to 15 mL of deionized water is added to continue rinsing the filter residue 3 to 5 times and then filtering again.
5. The method for quantitative characterization of rare earth content in blast furnace pig iron according to claim 1, characterized in that, In step (3), after the filtered solution is collected into the beaker and the volume is adjusted, after the first transfer of the solution, the filtration flask is rinsed with 10 mL to 15 mL of deionized water 3 to 5 times. Then, when transferring the solution from the beaker to the volumetric flask, after the first transfer of the solution, the beaker is rinsed with 5 mL to 10 mL of deionized water 3 to 5 times. Finally, the concave liquid surface of the solution is filled to the graduation line of the volumetric flask with deionized water.
6. The method for quantitative characterization of rare earth content in blast furnace pig iron according to claim 1, characterized in that, In step (4), the filter residue, along with the filter membrane or quantitative filter paper, is transferred to a crucible. The crucible can be made of nickel, silver, or platinum metal. The ratio of the amount of KOH and K2CO3 added to the mass of the blast furnace pig iron sample is (1.5-3):(1-1.5):
1. The melting temperature of the muffle furnace is 600 ℃ to 900 ℃, and the holding time is 25 min to 60 min.
7. The method for quantitative characterization of rare earth content in blast furnace pig iron according to claim 1, characterized in that, In step (6), after the solution is transferred for the first time, the beaker is rinsed with 10 mL to 15 mL of deionized water 3 to 5 times. Finally, the concave meniscus of the solution is filled with deionized water to the graduation line of the volumetric flask.
8. The method for quantitative characterization of rare earth content in blast furnace pig iron according to claim 1, characterized in that, The quantitative process described in step (7), after the concentration is measured using an inductively coupled plasma mass spectrometer, can be expressed by the formula... Perform measurements; W represents the rare earth element content in the blast furnace pig iron; C1 represents the concentration of rare earth elements in the solution after the filtrate is brought to a constant volume; V1 represents the volume of the filtrate after the filtrate is brought to a constant volume; C2 represents the concentration of rare earth elements in the solution after the filter residue is brought to a constant volume; V2 represents the volume of the solution after the filter residue is brought to a constant volume; and M represents the mass of the sample after electrolysis.