Method for detecting content of alumina in aluminum-manganese-calcium alloy

Abstract

This invention discloses a method for detecting the alumina content in aluminum-manganese-calcium alloys, mainly solving the technical problem that existing methods cannot accurately and rapidly detect the alumina content in aluminum-manganese-calcium alloys. The technical solution is as follows: a method for detecting the alumina content in aluminum-manganese-calcium alloys, comprising: 1) sample preparation: after removing the oxide layer on the sample surface, the sample is placed in a reagent bottle containing organic solvent for storage; 2) alumina extraction from the sample: first, alumina is extracted from the sample by electrolysis, the sample is placed in an electrolytic cell for electrolysis, the sample is the anode, a platinum electrode is the cathode, and a saturated calomel electrode is the reference electrode; 3) detection of alumina in the sample: the filter membrane and filter material from step 2) are placed in a platinum crucible, and the filter membrane is removed by high-temperature ashing; 4) calculation of the mass percentage of alumina in the aluminum-manganese-calcium alloy. The method of this invention for determining the alumina content in aluminum-manganese-calcium alloys has a relative standard deviation (RSD) of less than 3%, indicating good precision, accuracy, and reliability of the detection data.

Description

Technical Field

[0001] This invention relates to a method for detecting the chemical composition of aluminum-manganese-calcium alloys, and particularly to a method for detecting the alumina content in aluminum-manganese-calcium alloys. Specifically, it relates to a method for detecting the alumina content in aluminum-manganese-calcium alloys used in steelmaking, and belongs to the field of chemical analysis technology in iron and steel metallurgy. Background Technology

[0002] Steel deoxidation is the most crucial step in steelmaking. It involves adding a metal element with a stronger affinity for iron to the molten steel. This metal reacts with oxygen to form oxides that are insoluble in the steel, thus removing dissolved oxygen. Commonly used deoxidizers in steelmaking include manganese, calcium, silicon, and aluminum.

[0003] Aluminum-manganese-calcium alloy (AMC-calcium) is a common composite deoxidizer in steelmaking. It primarily utilizes the reaction of metallic aluminum, manganese, and calcium elements with oxygen to achieve deoxidation. The effective deoxidizing components of AMC-calcium alloy are mainly metallic elements; however, the alumina in the alloy not only fails to deoxidize molten steel but also directly affects the deoxidation effect and the quality of the molten steel.

[0004] Current technology cannot measure and rate the alumina in aluminum-manganese-calcium alloys. The quality evaluation of aluminum-manganese-calcium alloys is only judged by measuring the aluminum content in the sample, which poses a huge risk to steelmaking deoxidation.

[0005] The main methods for detecting alumina content include volumetric methods, photometric methods, inductively coupled plasma atomic emission spectrometry (ICP-AES), and X-ray fluorescence spectrometry. These methods basically determine the aluminum content in the sample and report it as alumina. They do not distinguish between metallic aluminum and alumina in the sample and cannot detect the aluminum oxide content in samples containing metallic aluminum.

[0006] Chinese patent application CN104215541A discloses a method for efficiently and accurately detecting the content of high-purity alumina and its impurities. The method involves treating the sample with hydrochloric acid, detecting impurity elements in the alumina, and then weighing the unreacted alumina to calculate the content of alumina and impurity elements. However, this method is only suitable for detecting high-purity alumina materials and cannot separate and detect metallic aluminum and alumina, thus failing to meet the requirements for detecting the alumina content in aluminum-manganese-calcium alloys.

[0007] Chinese patent application CN109001192A discloses an automated titration analysis method for soluble alumina. This method employs a computer-controlled peristaltic pump to titrate the test liquid, and a machine vision sensor to capture images of color changes during the titration process. Digital image processing algorithms analyze and determine the images, and the peristaltic pump is shut off when the titration endpoint is reached. After titration, the soluble alumina content is calculated. However, this method is only suitable for the determination of soluble alumina and does not address the separation and detection of alumina and metallic aluminum, thus failing to meet the requirement for detecting alumina content in aluminum-manganese-calcium alloys.

[0008] Chinese patent application CN112986486A discloses a method for detecting the aluminum content in aluminum slag deoxidizers and a sample preparation method. The method involves preparing the sample into a powder form and selectively reacting it with aluminum using FeCl3 solution to distinguish between aluminum and alumina. However, this method requires the sample to be prepared into a powder form, which cannot avoid the problem of rapid oxidation of powdered aluminum and therefore cannot meet the requirements for detecting the alumina content in aluminum-manganese-calcium alloys.

[0009] Chinese patent application CN102607934A discloses a fusion sample preparation method for X-ray fluorescence spectrometry analysis of aluminum-manganese-calcium-iron alloys. This invention method is only suitable for detecting the aluminum content in aluminum-manganese-calcium alloys and does not distinguish between the alumina and metallic aluminum content in aluminum-manganese-calcium alloys.

[0010] The existing methods disclosed in the technology cannot accurately separate and extract aluminum oxide from aluminum manganese calcium samples; the existing technology cannot accurately determine the aluminum oxide content in the sample. Summary of the Invention

[0011] The purpose of this invention is to provide a method for detecting the alumina content in aluminum-manganese-calcium alloys, mainly solving the technical problem that existing technologies cannot accurately and rapidly detect the alumina content in aluminum-manganese-calcium alloys. The method of this invention achieves accurate and rapid determination of alumina in aluminum-manganese-calcium alloys by effectively separating alumina from metallic aluminum and effectively extracting alumina.

[0012] The technical concept of this invention is to use an electrolysis method to electrolyze an aluminum-manganese-calcium alloy. Under the action of electrolysis, the metallic aluminum in the aluminum-manganese-calcium alloy loses electrons to form aluminum ions, which then complex with disodium ethylenediaminetetraacetate in the solution. The alumina in the aluminum-manganese-calcium alloy cannot be electrolyzed, thus achieving accurate separation of alumina from metallic aluminum. The alumina particles are collected, and after being processed into a solution, the alumina content in the aluminum-manganese-calcium alloy is calculated.

[0013] The technical solution adopted in this invention is a method for detecting the alumina content in aluminum-manganese-calcium alloys, comprising the following steps:

[0014] 1) Prepare the sample, cut the sample, and control the sample size to be 20-50 mm in length, 20-40 mm in width, and 0.5-2.0 mm in thickness. After removing the oxide layer on the sample surface, store the sample in a reagent bottle containing organic solvent.

[0015] 2) Extracting alumina from the sample: First, extract the alumina from the sample using electrolysis. Place the sample in an electrolytic cell for electrolysis, with the sample as the anode, a platinum electrode as the cathode, and a saturated calomel electrode as the reference electrode. The electrolysis current is 70–120 mA, the electrolysis capacity is 500–10000 °C, and the electrolyte temperature is 50–60 °C. The electrolyte components include: hydrochloric acid with a volume concentration of 5%–10%, triethanolamine with a volume concentration of 1%–1.5%, tartaric acid with a mass concentration of 2%–3%, and disodium ethylenediaminetetraacetate solution with a mass concentration of 1%–2%.

[0016] Next, the sample after electrolysis was soaked in the cleaning solution, and then the sample in the cleaning solution was ultrasonically cleaned using ultrasound.

[0017] Then, the electrolyte after electrolyzing the sample and the cleaning solution after washing the sample after electrolysis were filtered under reduced pressure, and the filtrate and filter membrane were collected.

[0018] 3) To detect alumina in the sample, place the filter membrane and filter material from step 2) in a platinum crucible and remove the filter membrane by high-temperature ashing;

[0019] Next, add 1.0–2.0 g of potassium pyrosulfate to the crucible, place the crucible in a high-temperature furnace at 300–400°C, melt at high temperature for 15–25 minutes, and then remove and cool.

[0020] The molten material in the crucible is dissolved by heating with 10-20 mL of hydrochloric acid solution, the volume concentration of which is 20-30%.

[0021] After complete dissolution, add 5-10 mL of 50% sodium hydroxide solution and 10-25 mL of 0.0100 mol / L disodium ethylenediaminetetraacetate standard solution to the solution.

[0022] Adjust the pH of the solution to 4-5;

[0023] Add 15–20 mL of acetic acid-ammonium acetate buffer solution to the solution; heat to boiling for 2–3 minutes, then remove and cool to 25–35°C.

[0024] Add 3-5 mL of a 0.1% (w / w) nitroso-R salt solution to the solution, using the nitroso-R salt solution as an indicator;

[0025] Titrate the solution with a 0.0100 mol / L copper sulfate standard solution until the solution turns yellow-green, then stop the titration and read the titration volume of copper sulfate.

[0026] 4) Calculate the mass percentage of alumina in the aluminum-manganese-calcium alloy. The mass percentage of alumina in the aluminum-manganese-calcium alloy is calculated according to Formula 1. In Formula 1, W is the mass percentage of alumina in the aluminum-manganese-calcium alloy (%); v1 is the volume of EDTA standard solution added (mL); c1 is the concentration of the EDTA standard solution added (mol / L); v2 is the volume of copper sulfate standard solution used for titration (mL); c2 is the concentration of the copper sulfate standard solution used for titration (mol / L); M is the molar mass of aluminum oxide (g / mol); m1 is the mass of the sample before electrolysis (g); and m2 is the mass of the sample after electrolysis (g).

[0027] Furthermore, in step 1), the oxide layer on the sample surface is polished with zirconium oxide sandpaper; the organic solvent is any one of acetone, diethyl ether, and methanol, which has good effect.

[0028] Furthermore, in step 2), the hydrochloric acid, tartaric acid, disodium ethylenediaminetetraacetate, and triethanolamine in the electrolyte solution are all of analytical grade or higher; the water in the electrolyte is laboratory analytical water of grade II or higher; during electrolysis, the electrolytic cell is placed in a constant temperature water bath at a temperature of 50–60°C; the cleaning solution is a hydrochloric acid solution with a volume concentration of 5–10%; the filter membrane is made of polytetrafluoroethylene with a pore diameter of 0.05–0.10 μm, which provides excellent results.

[0029] Furthermore, in step 3), the ashing temperature of the filter membrane is 300–500℃, and the ashing time is 20–30 min for optimal results. The acetic acid-ammonium acetate buffer solution is prepared by weighing 77g of ammonium acetate, dissolving it in water, adding 59mL of glacial acetic acid, diluting with water to 1000mL, and shaking well.

[0030] This invention is based on the applicant's research as follows:

[0031] 1) Electrolyte setting

[0032] Based on the main components of aluminum-manganese-calcium alloy and the complexation properties of various ions after ionization, this study found that under dilute hydrochloric acid conditions, electrolysis of the aluminum-manganese-calcium alloy sample transforms metallic aluminum, manganese, and calcium into ionic forms. These ionized metal ions, under certain temperature conditions, complex with disodium ethylenediaminetetraacetate, tartaric acid, and triethanolamine in the electrolyte, preventing the ionized metal ions from precipitating out of the solution and solving the problem of separating metallic aluminum from alumina. The main reactions are as follows:

[0033] Al-3e - →Al3+

[0034] Mn-2e - →Mn 2+

[0035] Ca-2e - →Ca 2+

[0036] Al 3+ +EDTA 4- =Al-EDTA -

[0037] Mn 2+ +EDTA 4- =Mn-EDTA 2-

[0038] Ca 2+ +EDTA 4- =Ca-EDTA 2-

[0039] 2) Setting electrolysis parameters

[0040] Further research by the applicant revealed that controlling the electrolysis current to 70–120 mA and the electrolysis rate to 500–10000 C allows for the stable electrolysis of metals in the sample into metal ions at a controlled rate. Simultaneously, controlling the electrolyte temperature to 50–60 °C ensures that the electrolyzed metal ions immediately complex with disodium ethylenediaminetetraacetate in the electrolyte, avoiding the problem of rapid ionization and precipitation of large amounts of metal ions and preventing the deposition of large amounts of electrolytic sludge. Furthermore, the reaction of unelectrolyted metal oxides with hydrochloric acid in the electrolyte further improves the purity of alumina extraction and resolves the interference problem caused by other metal elements. The main reactions are as follows:

[0041] CaO + 2HCl = CaCl₂ + H₂O

[0042] MnO + 2HCl = MnCl₂ + H₂O

[0043] 3) Treatment to separate alumina

[0044] The applicant's research found that by adding 1.0–2.0 g of potassium pyrosulfate to collected alumina particles and controlling the temperature at 300–400 °C, the sample can be completely melted to prepare a soluble salt. The solution to be tested can then be prepared by reverse acidification with hydrochloric acid solution. The main reaction is as follows: Al₂O₃ + 3K₂S₂O₇ = Al₂(SO₄)₃ + 3K₂SO₄

[0045] 4) Determination of alumina content

[0046] The applicant further investigated by adding a quantitative and excess amount of disodium ethylenediaminetetraacetate (EDTA) standard solution, ensuring that all aluminum ions in the solution were complexed with the disodium EDTA. The pH of the solution was then adjusted to 4-5 to prevent the formation of aluminum hydroxide precipitate. The uncomplexed disodium EDTA standard solution was then titrated with copper sulfate standard solution. The main reactions are as follows: Al 3+ +EDTA 4- =Al-EDTA - Cu+EDTA 4- =Cu-EDTA 2- .

[0047] This invention solves the technical challenge of accurately detecting alumina in aluminum-manganese-calcium alloys, meeting the needs of steelmaking production for accurate quality evaluation of aluminum-manganese-calcium alloys and assessment of steel deoxidation effects. Through research on sample electrolysis and detection technologies, an innovative isothermal-constant current electrolysis pretreatment-copper sulfate titration method is proposed for determining the alumina content in aluminum-manganese-calcium alloys.

[0048] Compared with existing technologies, this invention has the following advantages: 1. The method of this invention, through research on electrolyte and electrolysis parameters, solves the problem of effective separation of alumina and metallic aluminum in the sample, enabling the extraction of high-purity alumina, ensuring accurate and reliable detection data, and is easy to operate. It is applicable to the detection of alumina in aluminum-manganese-calcium alloys used in steelmaking; it achieves accurate and rapid detection of alumina content in aluminum-manganese-calcium alloys used in steelmaking, meeting the needs of the steel industry for quality evaluation and use of aluminum-manganese-calcium alloys and for assessing the deoxidation effect of molten steel, and solving the technical problem that existing technologies cannot accurately detect the alumina content in aluminum-manganese-calcium alloys. 2. The method of this invention has a wide parameter control window, is easy to operate, has a short detection process, high detection efficiency, strong operability, and does not require expensive large-scale analytical equipment, meeting the requirements of online detection in production. 3. The method of this invention determines the alumina content in aluminum-manganese-calcium alloys with a relative standard deviation (RSD) of less than 3%, and the zinc recovery rate in the recovery test is 99.0%-102.0%. The detection data has good precision, high recovery rate, and is accurate, reliable, and highly automated, fully meeting the needs of steelmaking for the detection of alumina content in aluminum-manganese-calcium alloys. Detailed Implementation

[0049] The present invention will be further described below with reference to Embodiment 1, as shown in Tables 1-2.

[0050] A method for detecting the alumina content in an aluminum-manganese-calcium alloy, comprising the following steps:

[0051] 1) Sample preparation: The sample length is controlled to be 40 mm, the width to be 20 mm, and the thickness to be 2 mm. After removing the surface oxide layer by polishing with zirconium oxide sandpaper, the sample is immediately placed in a beaker containing liquid acetone. After ultrasonicating the beaker for 3 minutes, the sample is removed, the sample surface is cleaned with liquid acetone, and the sample is stored in a reagent bottle containing liquid acetone for later use.

[0052] 2) Electrolyte preparation: In a 1L beaker, add 500mL deionized water, 80mL hydrochloric acid, 30g tartaric acid, 20g disodium ethylenediaminetetraacetate, and 10mL triethanolamine. Stir with a glass rod until the solids are completely dissolved, then transfer to a 1000mL volumetric flask, dilute with water to the mark, and shake well.

[0053] 3) Extract alumina from the sample. The sample is connected to the positive electrode of the electrolyzer via a wire, the platinum electrode is connected to the negative electrode via a wire, and the saturated calomel electrode is connected to the electrolyzer via a wire. Place the sample, platinum electrode, and saturated calomel electrode in the electrolytic cell, and inject electrolyte into the cell to completely cover the sample. Simultaneously, place the electrolytic cell in a 60℃ constant temperature water bath. Set the electrolyzer parameters to an electrolysis current of 100mA and an electrolysis rate of 8000C. Electrolysis is then performed. After electrolysis, place the sample in a container with a concentrated solution. The sample was placed in a beaker containing a 5% hydrochloric acid solution and sonicated for 5 minutes using an ultrasonic instrument. The sample surface was then cleaned with a 5% hydrochloric acid solution. The resulting hydrochloric acid solution was combined with the electrolyte in the electrolytic cell. The combined solution was then filtered under reduced pressure using a polytetrafluoroethylene (PTFE) membrane. After filtration, the sample was washed five times with a 5% hydrochloric acid solution, followed by five washes with deionized water. The deionized water used was classified as Class II or higher laboratory analytical water. The PTFE membrane had a pore size of 0.05 μm.

[0054] 4) For the determination of alumina in the sample, place the filter membrane and filter material from step 3 into a platinum crucible. Place the crucible in a 300℃ high-temperature furnace and ignite for 20 minutes, then remove and cool. Add 2.0 g of potassium pyrosulfate to the crucible, then place the crucible in a 400℃ high-temperature furnace and melt for 15 minutes, then remove and cool. Dissolve the melt in the crucible with 20 mL of 20% hydrochloric acid solution by heating. After complete dissolution, add 10 mL of 50% sodium hydroxide solution and 25 mL of 0.0100 mol / L disodium ethylenediaminetetraacetate standard solution to the solution. Adjust the pH of the solution to 4.5, add 20 mL of acetate-ammonium acetate buffer solution, heat to boiling for 3 minutes, remove and cool to 35℃, add 5 mL of 0.1% nitroso-R salt solution as an indicator, and titrate with 0.0100 mol / L copper sulfate standard solution until the solution turns yellow-green. Stop the titration and read the volume of copper sulfate titrated.

[0055] 5) Calculate the mass percentage of alumina in the aluminum-manganese-calcium alloy. The mass percentage of alumina in the aluminum-manganese-calcium alloy is calculated according to Formula 1. Formula 1: In Formula 1, W represents the mass percentage of alumina in the aluminum-manganese-calcium alloy (%); v1 is the volume of EDTA standard solution added (mL); c1 is the concentration of the EDTA standard solution added (mol / L); v2 is the volume of copper sulfate standard solution used for titration (mL); c2 is the concentration of the copper sulfate standard solution used for titration (mol / L); M is the molar mass of aluminum oxide (g / mol); m1 is the mass of the sample before electrolysis (g); and m2 is the mass of the sample after electrolysis (g).

[0056] The precision and accuracy of the method of the present invention were confirmed by the precision of the sample and spike recovery experiments.

[0057] Precision experiments were conducted to determine the alumina content in the five groups of aluminum-manganese-calcium alloys nine times. The results are shown in Table 1.

[0058] Table 1 Sample Precision Experiment

[0059]

[0060] A certain amount of alumina was added to two groups of aluminum-manganese-calcium alloy electrolytes, and the alumina content was determined using the method of this invention. The recovery rate was calculated, and the analytical results are shown in Table 2.

[0061] Table 2 Spike Recovery Test of Samples

[0062]

[0063]

[0064] The above experimental results show that the method of the present invention for determining the alumina content in aluminum-manganese-calcium alloys has a relative standard deviation (RSD) of less than 3%, and the zinc recovery rate in the recovery test is in the range of 99.0%-102.0%. The detection data has good precision, high recovery rate, and the method is accurate, reliable, and highly automated, fully meeting the requirements of steelmaking for detecting the alumina content in aluminum-manganese-calcium alloys.

[0065] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for detecting the alumina content in an aluminum-manganese-calcium alloy, characterized in that, The method includes the following steps: 1) Prepare the sample, cut the sample, and control the sample size to be 20-50 mm in length, 20-40 mm in width, and 0.5-2.0 mm in thickness. After removing the oxide layer on the sample surface, store the sample in a reagent bottle containing organic solvent. 2) Extracting alumina from the sample: First, extract the alumina from the sample using electrolysis. Place the sample in an electrolytic cell for electrolysis, with the sample as the anode, a platinum electrode as the cathode, and a saturated calomel electrode as the reference electrode. The electrolysis current is 70–120 mA, the electrolysis capacity is 500–10000 °C, and the electrolyte temperature is 50–60 °C. The electrolyte components include: hydrochloric acid with a volume concentration of 5%–10%, triethanolamine with a volume concentration of 1%–1.5%, tartaric acid with a mass concentration of 2%–3%, and disodium ethylenediaminetetraacetate solution with a mass concentration of 1%–2%. Next, the sample after electrolysis was soaked in the cleaning solution, and then ultrasonically cleaned in the cleaning solution. Then, the electrolyte after electrolyzing the sample and the cleaning solution after washing the sample were subjected to reduced pressure filtration, and the filtrate and filter membrane were collected. 3) To detect alumina in the sample, place the filter membrane and filter material from step 2) in a platinum crucible and remove the filter membrane by high-temperature ashing; Next, add 1.0–2.0 g of potassium pyrosulfate to the crucible, place the crucible in a high-temperature furnace at 300–400°C, melt at high temperature for 15–25 minutes, and then remove and cool. The molten material in the crucible is dissolved by heating with 10-20 mL of hydrochloric acid solution, the volume concentration of which is 20-30%. After complete dissolution, add 5-10 mL of 50% sodium hydroxide solution and 10-25 mL of 0.0100 mol / L disodium ethylenediaminetetraacetate standard solution to the solution. Adjust the pH of the solution to 4-5; Add 15–20 mL of acetic acid-ammonium acetate buffer solution to the solution; heat to boiling for 2–3 min, then remove and cool to 25–35 °C; Add 3-5 mL of a 0.1% (w / w) nitroso-R salt solution to the solution, using the nitroso-R salt solution as an indicator; Titrate the solution with a 0.0100 mol / L copper sulfate standard solution until the solution turns yellow-green, then stop the titration and read the titration volume of copper sulfate. 4) Calculate the mass percentage of alumina in the aluminum-manganese-calcium alloy. The mass percentage of alumina in the aluminum-manganese-calcium alloy is calculated according to Formula 1. In Formula 1, W represents the mass percentage of alumina in the aluminum-manganese-calcium alloy (%); v1 represents the volume of EDTA standard solution added (mL); c1 represents the concentration of the EDTA standard solution added (mol / L); v2 represents the volume of copper sulfate standard solution used for titration (mL); c2 represents the concentration of the copper sulfate standard solution used for titration (mol / L); M represents the molar mass of aluminum oxide (g / mol); m1 represents the mass of the sample before electrolysis (g); and m2 represents the mass of the sample after electrolysis (g).

2. The method for detecting the alumina content in aluminum-manganese-calcium alloy as described in claim 1, characterized in that, The oxide layer on the sample surface described in step 1) is polished with zirconium oxide sandpaper; the organic solvent is any one of acetone, diethyl ether and methanol.

3. The method for detecting the alumina content in aluminum-manganese-calcium alloy as described in claim 1, characterized in that, The hydrochloric acid, tartaric acid, disodium ethylenediaminetetraacetate, and triethanolamine in the electrolyte are all of analytical grade or higher; the water in the electrolyte is laboratory analytical water grade II or higher.

4. The method for detecting the alumina content in aluminum-manganese-calcium alloy as described in claim 1, characterized in that, During the electrolysis process, the electrolytic cell is placed in a constant temperature water bath, where the water temperature is 50–60°C.

5. The method for detecting the alumina content in aluminum-manganese-calcium alloy as described in claim 1, characterized in that, The cleaning solution is a hydrochloric acid solution with a volume concentration of 5-10%.

6. The method for detecting the alumina content in aluminum-manganese-calcium alloy as described in claim 1, characterized in that, The filter membrane is made of polytetrafluoroethylene, and the pore diameter of the filter membrane is 0.05 to 0.10 μm.

7. The method for detecting the alumina content in aluminum-manganese-calcium alloy as described in claim 1, characterized in that, The ashing temperature of the filter membrane is 300-500℃, and the ashing time is 20-30 min.

8. The method for detecting the alumina content in aluminum-manganese-calcium alloy as described in claim 1, characterized in that, The method for preparing the acetic acid-ammonium acetate buffer solution includes: weighing 77g of ammonium acetate, dissolving it in water, adding 59mL of glacial acetic acid, diluting it with water to 1000mL, and shaking well.

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