Method for measuring content of chromium element in high-carbon ferro-chrome

Abstract

The invention relates to a method for measuring the content of chromium in high-carbon ferrochrome, which comprises the following steps: placing a high-carbon ferrochrome sample to be measured, sodium peroxide and sodium carbonate in a corundum crucible, uniformly mixing, covering with sodium peroxide, and melting at 710-730 DEG C for 10-15 minutes to obtain a melt; then, the melt is leached with hot water, sulfuric acid is added for neutralization, then boiling is conducted, and a molten test solution is obtained; adding mixed acid into the molten test solution to adjust the pH value to be acidic, and diluting to obtain a diluted test solution; adding a manganese sulfate solution, a silver nitrate solution and an ammonium persulfate solution into the diluted test solution, heating and boiling for the first time, adding a sodium chloride solution, heating and boiling for the second time, and cooling to obtain a solution to be detected; and finally, adding an N-phenyl o-aminobenzoic acid indicator into the to-be-detected solution, titrating with an ammonium ferrous sulfate standard solution until a reaction endpoint, and calculating. The determination method is accurate, reliable and rapid in determination, and the detection cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and detection, in particular to a method for determining the chromium content in high-carbon ferrochrome. Background Art

[0002] Sodium peroxide is the main reagent for melting high-carbon ferrochrome and is an explosive chemical. In recent years, due to market control reasons, sodium peroxide has changed from granular to powdery. The change in state has led to a poor melting effect of the sample. Since only powdered sodium peroxide can be used, according to the national standard "GBT 4699.2-2008 Determination of chromium content in ferrochrome and silicon-chromium alloys", 3.5.2.1.3 is used for melting. The nickel crucible can only be used once and is costly. The dissolution effect is poor when the melting temperature is controlled at 700°C. In addition, the national standard operating procedures are cumbersome and time-consuming. Summary of the invention

[0003] The purpose of the present invention is to provide a method for determining the chromium content in high-carbon ferrochrome, thereby improving the analysis and determination time of the chromium content in high-carbon ferrochrome and reducing the detection cost. The analysis and detection results are accurate and reliable.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a method for determining the chromium content in high-carbon ferrochrome, comprising the following steps: S1: Place the high carbon ferrochrome sample, sodium peroxide and sodium carbonate in a corundum crucible, mix well and cover with sodium peroxide, melt at 710-730℃ for 10-15min to obtain a melt; S2: leaching the molten material with hot water, adding sulfuric acid to neutralize it and then boiling it to obtain a molten test solution; S3: adding mixed acid to the molten test solution to adjust the pH to acidic and then diluting to obtain a diluted test solution; S4: adding manganese sulfate solution, silver nitrate solution and ammonium persulfate solution to the diluted test solution, heating and boiling once, then adding sodium chloride solution and heating and boiling again, and cooling to obtain a test solution; S5: Add N-phenylanthranilic acid indicator to the test solution, titrate to the reaction end point with ammonium ferrous sulfate standard solution, and calculate the chromium content in the high carbon ferrochrome according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标 *m 标 / (5*V 标 *100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

[0005] Furthermore, the mass ratio of the high carbon ferrochrome sample to be tested, the sodium peroxide and the sodium carbonate is 0.5:7~8:2~3.

[0006] Furthermore, in step S2, the hot water leaching temperature is 90-100°C.

[0007] Furthermore, in step S2, the sulfuric acid is 1+1 sulfuric acid, and the amount of the 1+1 sulfuric acid is 60 mL.

[0008] Furthermore, in step S3, the mixed acid is a mixed solution of phosphoric acid and sulfuric acid, and the volume ratio of the phosphoric acid to the sulfuric acid is 1:4.

[0009] Further, in step S4, the concentration of the manganese sulfate solution is 40 g / L, and / or the concentration of the silver nitrate solution is 10 g / L, and / or the concentration of the ammonium persulfate solution is 200 g / L, and / or the concentration of the sodium chloride solution is 50 g / L.

[0010] Furthermore, the volume ratio of the manganese sulfate solution, the silver nitrate solution, the ammonium persulfate solution and the sodium chloride solution is 0.5:10:20:7.

[0011] Furthermore, in step S4, the first heating and boiling time is 5 min to 8 min, and / or the second heating and boiling time is 8 min to 10 min.

[0012] Furthermore, in step S5, the concentration of the N-phenylanthranilic acid indicator is 2 g / L, and / or the concentration of the ammonium ferrous sulfate standard solution is 0.1 mol / L.

[0013] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: The present invention uses a corundum crucible to replace the nickel crucible in the prior art for melting (the price of a corundum crucible is low, about 1 / 3 of the price of a nickel crucible, and can be reused 3-4 times), synchronously adjusts the melting temperature and melting time of the sample, optimizes the redox titration process, and thereby improves the analysis and detection speed of the chromium content in high-carbon ferrochrome, reduces the detection cost, and the analysis and detection data are accurate and reliable. DETAILED DESCRIPTION

[0014] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] A method for determining the chromium content in high carbon ferrochrome provided in the present invention comprises the following steps: S1: Place the high carbon ferrochrome sample, sodium peroxide and sodium carbonate in a corundum crucible, mix well and cover with sodium peroxide, melt at 710-730℃ for 10-15min to obtain a melt; S2: Immerse the above molten material in hot water, add sulfuric acid to neutralize it, and then boil it to obtain a molten test solution; S3: adding mixed acid to the above molten test solution to adjust the pH to acidic and then diluting to obtain a diluted test solution; S4: Add manganese sulfate solution, silver nitrate solution and ammonium persulfate solution to the diluted test solution, heat and boil once, then add sodium chloride solution and heat and boil again, and cool to obtain the test solution; S5: Add N-phenylanthranilic acid indicator to the above test solution, titrate to the reaction end point with ammonium ferrous sulfate standard solution, and calculate the chromium content in high carbon ferrochrome according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标 *m 标 / (5*V 标 *100)(Ⅱ) In formula (II), WCr标 Represents the chromium content in high carbon ferrochrome standard material; The m mark represents the mass of high carbon ferrochrome standard material, g; The V mark represents the volume of ammonium ferrous sulfate standard solution consumed in titrating the high carbon ferrochrome standard substance, mL.

[0016] For the above melting process, an iron-nickel crucible is usually used for sample melting, but the crucible needs to be replaced frequently due to the strong oxidizing and corrosive properties of sodium peroxide, which increases the analysis cost. Therefore, in the embodiment of the present invention, a corundum crucible is used instead of an iron-nickel crucible, which reduces the detection cost accordingly.

[0017] Furthermore, in the embodiment of the present invention, before the sample is melted at high temperature, the crucible containing the high carbon ferrochrome sample to be tested, sodium peroxide and sodium carbonate is slowly heated to avoid splashing caused by the violent reaction of sodium peroxide, which may lead to inaccurate analysis results and cause safety accidents.

[0018] In addition, in order to completely melt the sample and oxidize all chromium to hexavalent chromium, the melting temperature and melting time need to be properly controlled. If the chromium cannot be completely oxidized to hexavalent chromium, the analysis result may be low; if the melting temperature is too high or the melting time is too long, the sample will not be easy to leach, which will lead to inaccurate analysis results.

[0019] The present invention is further described below through several specific embodiments.

[0020] Example 1 The present embodiment provides a method for determining the chromium content in high carbon ferrochrome, comprising the following steps: S1: Before use, a clean corundum crucible (30ml) was placed in a muffle furnace and burned at 750℃ for 3-5min. Then, 0.5g of the high-carbon ferrochrome sample with sample number W202402180003, 7g of sodium peroxide and 2g of sodium carbonate were weighed and placed in the corundum crucible. After mixing evenly, 1g of sodium peroxide was added to cover the crucible. The 30ml corundum crucible was placed in a 50ml porcelain crucible, and the crucible was placed in a muffle furnace and heated slowly. The crucible was heated at 630℃ for 10 min, and then heated to 680℃ for 5 min. After the sample was dissolved, the crucible was heated to 730℃ and kept warm for 10 min to obtain a molten material. S2: After taking out of the furnace, wait for the crucible to cool naturally, then transfer the crucible to a 500ml beaker, add 100ml hot water to wash out the crucible, then add 60ml sulfuric acid (1+1), boil for 10min, cool to room temperature and transfer to a 250ml volumetric flask, dilute with water to the fixed volume, shake well and set aside to obtain the molten test solution; S3: Pipette 50 ml of the above molten test solution into a 500 ml conical flask, add 5 ml of phosphoric acid (AR) and 20 ml of sulfuric acid (1+1), and dilute to 200 ml with warm water to obtain the diluted test solution; S4: Add 4 drops of manganese sulfate solution (40 g / L), 10 ml of silver nitrate solution (10 g / L), and 20 ml of ammonium persulfate solution (200 g / L) to the diluted test solution, heat and boil until permanganate red appears for about 5 minutes, continue heating until large bubbles appear to decompose excess ammonium persulfate, then add 7 ml of sodium chloride solution (50 g / L), boil until the red color disappears and silver chloride precipitates, and cool to room temperature to obtain the test solution; S5: Dilute the above test solution with distilled water to 250 ml, then titrate with ammonium ferrous sulfate standard titration solution (0.1 mol / L) until it turns light yellow, add 5 drops of N-phenylanthranilic acid indicator solution (2 g / L), and continue to titrate with ammonium ferrous sulfate standard titration solution. The end point is when the solution turns from purple to purple-black and then to bright green, and record the titration volume in milliliters; The chromium content in high carbon ferrochrome is calculated according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标 *m mark / (5*V mark*100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

[0021] After calculation, the chromium content in sample W202402180003 is 53.73%.

[0022] Example 2 The present embodiment provides a method for determining the chromium content in high carbon ferrochrome, comprising the following steps: S1: Before use, a clean corundum crucible (30ml) was placed in a muffle furnace and burned at 750℃ for 3-5min. Then, 0.5g of the high-carbon ferrochrome sample with sample number W202403130080, 7g of sodium peroxide and 2g of sodium carbonate were weighed and placed in the corundum crucible. After mixing evenly, 1g of sodium peroxide was added to cover the crucible. The 30ml corundum crucible was placed in a 50ml porcelain crucible, and the crucible was placed in a muffle furnace and heated slowly. The crucible was heated at 630℃ for 10 min, and then heated to 680℃ for 5 min. After the sample was dissolved, the crucible was heated to 710℃ and kept warm for 15min to obtain a molten material. S2: After taking out of the furnace, wait for the crucible to cool naturally, then transfer the crucible to a 500ml beaker, add 100ml hot water to wash out the crucible, then add 60ml sulfuric acid (1+1), boil for 10min, cool to room temperature and transfer to a 250ml volumetric flask, dilute with water to the fixed volume, shake well and set aside to obtain the molten test solution; S3: Pipette 50 ml of the above molten test solution into a 500 ml conical flask, add 5 ml of phosphoric acid (AR) and 20 ml of sulfuric acid (1+1), and dilute to 200 ml with warm water to obtain the diluted test solution; S4: Add 4 drops of manganese sulfate solution (40 g / L), 10 ml of silver nitrate solution (10 g / L), and 20 ml of ammonium persulfate solution (200 g / L) to the diluted test solution, heat and boil until permanganate red appears for about 5 minutes, continue heating until large bubbles appear to decompose excess ammonium persulfate, then add 7 ml of sodium chloride solution (50 g / L), boil until the red color disappears and silver chloride precipitates, and cool to room temperature to obtain the test solution; S5: Dilute the above test solution with distilled water to 250 ml, then titrate with ammonium ferrous sulfate standard titration solution (0.1 mol / L) until it turns light yellow, add 5 drops of N-phenylanthranilic acid indicator solution (2 g / L), and continue to titrate with ammonium ferrous sulfate standard titration solution. The end point is when the solution turns from purple to purple-black and then to bright green, and record the titration volume in milliliters; The chromium content in high carbon ferrochrome is calculated according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标*m mark / (5*V mark*100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

[0023] After calculation, the chromium content in sample W202403130080 is 46.83%.

[0024] Example 3 The present embodiment provides a method for determining the chromium content in high carbon ferrochrome, comprising the following steps: S1: Before use, a clean corundum crucible (30ml) was placed in a muffle furnace and burned at 750℃ for 3-5min. Then, 0.5g of the high carbon ferrochrome sample with sample number W202404140045, 7g of sodium peroxide and 2g of sodium carbonate were weighed and placed in the corundum crucible. After mixing evenly, 1g of sodium peroxide was added to cover the crucible. The 30ml corundum crucible was placed in a 50ml porcelain crucible and placed in a muffle furnace and heated slowly. The crucible was heated at 630℃ for 10 min, then heated to 680℃ for 5 min. After the sample was dissolved, the crucible was heated to 720℃ for 10 min to obtain a molten material. S2: After taking out of the furnace, wait for the crucible to cool naturally, then transfer the crucible to a 500ml beaker, add 100ml hot water to wash out the crucible, then add 60ml sulfuric acid (1+1), boil for 10min, cool to room temperature and transfer to a 250ml volumetric flask, dilute with water to the fixed volume, shake well and set aside to obtain the molten test solution; S3: Pipette 50 ml of the above molten test solution into a 500 ml conical flask, add 5 ml of phosphoric acid (AR) and 20 ml of sulfuric acid (1+1), and dilute to 200 ml with warm water to obtain the diluted test solution; S4: Add 4 drops of manganese sulfate solution (40 g / L), 10 ml of silver nitrate solution (10 g / L), and 20 ml of ammonium persulfate solution (200 g / L) to the diluted test solution, heat and boil until permanganate red appears for about 5 minutes, continue heating until large bubbles appear to decompose excess ammonium persulfate, then add 7 ml of sodium chloride solution (50 g / L), boil until the red color disappears and silver chloride precipitates, and cool to room temperature to obtain the test solution; S5: Dilute the above test solution with distilled water to 250 ml, then titrate with ammonium ferrous sulfate standard titration solution (0.1 mol / L) until it turns light yellow, add 5 drops of N-phenylanthranilic acid indicator solution (2 g / L), and continue to titrate with ammonium ferrous sulfate standard titration solution. The end point is when the solution turns from purple to purple-black and then to bright green, and record the titration volume in milliliters; The chromium content in high carbon ferrochrome is calculated according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标 *m mark / (5*V mark*100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

[0025] After calculation, the chromium content in the W202404140045 sample is 52.2%.

[0026] Example 4 The present embodiment provides a method for determining the chromium content in high carbon ferrochrome, comprising the following steps: S1: Before use, a clean corundum crucible (30ml) was placed in a muffle furnace and burned at 750℃ for 3-5min. Then, 0.5g of the high-carbon ferrochrome sample with sample number W202404280034, 7g of sodium peroxide and 2g of sodium carbonate were weighed and placed in the corundum crucible. After mixing evenly, 1g of sodium peroxide was added to cover the crucible. The 30ml corundum crucible was placed in a 50ml porcelain crucible, and the crucible was placed in a muffle furnace and heated slowly. The crucible was heated at 630℃ for 10 min, and then heated to 680℃ for 5 min. After the sample was dissolved, the crucible was heated to 730℃ and kept warm for 10 min to obtain a molten material. S2: After taking out of the furnace, wait for the crucible to cool naturally, then transfer the crucible to a 500ml beaker, add 100ml hot water to wash out the crucible, then add 60ml sulfuric acid (1+1), boil for 10min, cool to room temperature and transfer to a 250ml volumetric flask, dilute with water to the fixed volume, shake well and set aside to obtain the molten test solution; S3: Pipette 50 ml of the above molten test solution into a 500 ml conical flask, add 5 ml of phosphoric acid (AR) and 20 ml of sulfuric acid (1+1), and dilute to 200 ml with warm water to obtain the diluted test solution; S4: Add 4 drops of manganese sulfate solution (40 g / L), 10 ml of silver nitrate solution (10 g / L), and 20 ml of ammonium persulfate solution (200 g / L) to the diluted test solution, heat and boil until permanganate red appears for about 5 minutes, continue heating until large bubbles appear to decompose excess ammonium persulfate, then add 7 ml of sodium chloride solution (50 g / L), boil until the red color disappears and silver chloride precipitates, and cool to room temperature to obtain the test solution; S5: Dilute the above test solution with distilled water to 250 ml, then titrate with ammonium ferrous sulfate standard titration solution (0.1 mol / L) until it turns light yellow, add 5 drops of N-phenylanthranilic acid indicator solution (2 g / L), and continue to titrate with ammonium ferrous sulfate standard titration solution. The end point is when the solution turns from purple to purple-black and then to bright green, and record the titration volume in milliliters; The chromium content in high carbon ferrochrome is calculated according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标 *m mark / (5*V mark*100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

[0027] After calculation, the chromium content in sample W202404280034 is 49.52%.

[0028] Example 5 The present embodiment provides a method for determining the chromium content in high carbon ferrochrome, comprising the following steps: S1: Before use, a clean corundum crucible (30ml) was placed in a muffle furnace and burned at 750℃ for 3-5min. Then, 0.5g of the high-carbon ferrochrome sample with sample number W202405260036, 7g of sodium peroxide and 2g of sodium carbonate were weighed and placed in the corundum crucible. After mixing evenly, 1g of sodium peroxide was added to cover the crucible. The 30ml corundum crucible was placed in a 50ml porcelain crucible, and the crucible was placed in a muffle furnace and heated slowly. The crucible was heated at 630℃ for 10 min, and then heated to 680℃ for 5 min. After the sample was dissolved, the crucible was heated to 730℃ and kept warm for 10 min to obtain a molten material. S2: After taking out of the furnace, wait for the crucible to cool naturally, then transfer the crucible to a 500ml beaker, add 100ml hot water to wash out the crucible, then add 60ml sulfuric acid (1+1), boil for 10min, cool to room temperature and transfer to a 250ml volumetric flask, dilute with water to the fixed volume, shake well and set aside to obtain the molten test solution; S3: Pipette 50 ml of the above molten test solution into a 500 ml conical flask, add 5 ml of phosphoric acid (AR) and 20 ml of sulfuric acid (1+1), and dilute to 200 ml with warm water to obtain the diluted test solution; S4: Add 4 drops of manganese sulfate solution (40 g / L), 10 ml of silver nitrate solution (10 g / L), and 20 ml of ammonium persulfate solution (200 g / L) to the diluted test solution, heat and boil until permanganate red appears for about 5 minutes, continue heating until large bubbles appear to decompose excess ammonium persulfate, then add 7 ml of sodium chloride solution (50 g / L), boil until the red color disappears and silver chloride precipitates, and cool to room temperature to obtain the test solution; S5: Dilute the above test solution with distilled water to 250 ml, then titrate with ammonium ferrous sulfate standard titration solution (0.1 mol / L) until it turns light yellow, add 5 drops of N-phenylanthranilic acid indicator solution (2 g / L), and continue to titrate with ammonium ferrous sulfate standard titration solution. The end point is when the solution turns from purple to purple-black and then to bright green, and record the titration volume in milliliters; The chromium content in high carbon ferrochrome is calculated according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标 *m mark / (5*V mark*100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

[0029] After calculation, the chromium content in sample W202405260036 is 53.43%.

[0030] Example 6 The present embodiment provides a method for determining the chromium content in high carbon ferrochrome, comprising the following steps: S1: Before use, a clean corundum crucible (30ml) was placed in a muffle furnace and burned at 750℃ for 3-5min. Then, 0.5g of the high-carbon ferrochrome sample with sample number W202406150032, 7g of sodium peroxide and 2g of sodium carbonate were weighed and placed in the corundum crucible. After mixing evenly, 1g of sodium peroxide was added to cover the crucible. The 30ml corundum crucible was placed in a 50ml porcelain crucible, and the crucible was placed in a muffle furnace and heated slowly. The crucible was heated at 630℃ for 10 min, and then heated to 680℃ for 5 min. After the sample was dissolved, the crucible was heated to 730℃ and kept warm for 10 min to obtain a molten material. S2: After taking out of the furnace, wait for the crucible to cool naturally, then transfer the crucible to a 500ml beaker, add 100ml hot water to wash out the crucible, then add 60ml sulfuric acid (1+1), boil for 10min, cool to room temperature and transfer to a 250ml volumetric flask, dilute with water to the fixed volume, shake well and set aside to obtain the molten test solution; S3: Pipette 50 ml of the above molten test solution into a 500 ml conical flask, add 5 ml of phosphoric acid (AR) and 20 ml of sulfuric acid (1+1), and dilute to 200 ml with warm water to obtain the diluted test solution; S4: Add 4 drops of manganese sulfate solution (40 g / L), 10 ml of silver nitrate solution (10 g / L), and 20 ml of ammonium persulfate solution (200 g / L) to the diluted test solution, heat and boil until permanganate red appears for about 5 minutes, continue heating until large bubbles appear to decompose excess ammonium persulfate, then add 7 ml of sodium chloride solution (50 g / L), boil until the red color disappears and silver chloride precipitates, and cool to room temperature to obtain the test solution; S5: Dilute the above test solution with distilled water to 250 ml, then titrate with ammonium ferrous sulfate standard titration solution (0.1 mol / L) until it turns light yellow, add 5 drops of N-phenylanthranilic acid indicator solution (2 g / L), and continue to titrate with ammonium ferrous sulfate standard titration solution. The end point is when the solution turns from purple to purple-black and then to bright green, and record the titration volume in milliliters; The chromium content in high carbon ferrochrome is calculated according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标 *m mark / (5*V mark*100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

[0031] After calculation, the chromium content in sample W202406150032 is 53.27%.

[0032] Example 7 The present embodiment provides a method for determining the chromium content in high carbon ferrochrome, comprising the following steps: S1: Before use, a clean corundum crucible (30ml) was placed in a muffle furnace and burned at 750℃ for 3-5min. Then, 0.5g of the high-carbon ferrochrome sample with sample number W202407170065, 7g of sodium peroxide and 2g of sodium carbonate were weighed and placed in the corundum crucible. After mixing evenly, 1g of sodium peroxide was added to cover the crucible. The 30ml corundum crucible was placed in a 50ml porcelain crucible, and the crucible was placed in a muffle furnace and slowly heated at 630℃ for 10 min, then heated to 680℃ for 5 min. After the sample was dissolved, the crucible was heated to 730℃ for 10 min to obtain a molten material. S2: After taking out of the furnace, wait for the crucible to cool naturally, then transfer the crucible to a 500ml beaker, add 100ml hot water to wash out the crucible, then add 60ml sulfuric acid (1+1), boil for 10min, cool to room temperature and transfer to a 250ml volumetric flask, dilute with water to the fixed volume, shake well and set aside to obtain the molten test solution; S3: Pipette 50 ml of the above molten test solution into a 500 ml conical flask, add 5 ml of phosphoric acid (AR) and 20 ml of sulfuric acid (1+1), and dilute to 200 ml with warm water to obtain the diluted test solution; S4: Add 4 drops of manganese sulfate solution (40 g / L), 10 ml of silver nitrate solution (10 g / L), and 20 ml of ammonium persulfate solution (200 g / L) to the diluted test solution, heat and boil until permanganate red appears for about 5 minutes, continue heating until large bubbles appear to decompose excess ammonium persulfate, then add 7 ml of sodium chloride solution (50 g / L), boil until the red color disappears and silver chloride precipitates, and cool to room temperature to obtain the test solution; S5: Dilute the above test solution with distilled water to 250 ml, then titrate with ammonium ferrous sulfate standard titration solution (0.1 mol / L) until it turns light yellow, add 5 drops of N-phenylanthranilic acid indicator solution (2 g / L), and continue to titrate with ammonium ferrous sulfate standard titration solution. The end point is when the solution turns from purple to purple-black and then to bright green, and record the titration volume in milliliters; The chromium content in high carbon ferrochrome is calculated according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标*m mark / (5*V mark*100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

[0033] After calculation, the chromium content in sample W202407170065 is 55.23%.

[0034] Comparative Example 1 This embodiment provides a commercially available standard substance YSBC28621-2010. The chromium content is detected by the detection method in Example 1. After calculation, the chromium content in the YSBC28621-2010 standard sample is 56.62%.

[0035] Comparative Example 2 This embodiment provides a commercially available standard substance GBW (E) 010257. The chromium content is detected by the detection method in Example 1. After calculation, the chromium content in the GBW (E) 010257 standard sample is 56.23%.

[0036] The test results of Examples 1 to 7 and Comparative Examples 1 to 2 were compared with the third-party test data / standard values, and the table is as follows: Table 1 Table 2 It can be seen from Table 1 and Table 2 that the detection method for the chromium content in high carbon ferrochrome provided by the present invention has a smaller difference between the detection results and the third party data, a higher accuracy rate and a better reproducibility. On the basis of significantly reducing the cost, the detection speed is improved, the determination method is simple to operate, the calculation is simple, and it is conducive to large-scale promotion.

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the chromium content in high carbon ferrochrome, characterized in that: The following steps are involved: S1: Place the high carbon ferrochrome sample, sodium peroxide and sodium carbonate in a corundum crucible, mix them evenly and cover them with sodium peroxide, and melt them at 710-730℃ for 10-15min to obtain a melt; S2: leaching the molten material with hot water, adding sulfuric acid to neutralize it and then boiling it to obtain a molten test solution; S3: adding mixed acid to the molten test solution to adjust the pH to acidic and then diluting to obtain a diluted test solution; S4: adding manganese sulfate solution, silver nitrate solution and ammonium persulfate solution to the diluted test solution, heating and boiling once, then adding sodium chloride solution and heating and boiling again, and cooling to obtain a test solution; S5: Add N-phenylanthranilic acid indicator to the test solution, titrate to the reaction end point with ammonium ferrous sulfate standard solution, and calculate the chromium content in the high carbon ferrochrome according to the formula shown in formula (I): W Cr %=T*V*5 / m*100%(Ⅰ) In formula (I), T represents the titer of ammonium ferrous sulfate against chromium, g / mL; V represents the volume of ammonium ferrous sulfate consumed in titrating the sample to be tested, mL; m represents the mass of the sample to be tested, g; The T value in formula (I) is tested by three different high carbon ferrochrome standard substances and calculated according to the formula shown in formula (II): T=W Cr标 *m 标 / (5*V 标 *100)(Ⅱ) In formula (II), W Cr标 Represents the chromium content in high carbon ferrochrome standard material; m 标 Represents the mass of high carbon ferrochrome standard material, g; V 标 Represents the volume of ammonium ferrous sulfate standard solution consumed in titrating high carbon ferrochrome standard substance, mL.

2. The method for determining the chromium content in high carbon ferrochrome according to claim 1, characterized in that: The mass ratio of the high carbon ferrochrome sample to be tested, the sodium peroxide and the sodium carbonate is 0.5:7-8:2-3.

3. The method for determining the chromium content in high carbon ferrochrome according to claim 1, characterized in that: In step S2, the hot water leaching temperature is 90-100°C.

4. The method for determining the chromium content in high carbon ferrochrome according to claim 1, characterized in that: In step S2, the sulfuric acid is 1+1 sulfuric acid, and the amount of the 1+1 sulfuric acid is 60 mL.

5. The method for determining the chromium content in high carbon ferrochrome according to claim 1, characterized in that: In step S3, the mixed acid is a mixed solution of phosphoric acid and sulfuric acid, and the volume ratio of the phosphoric acid to the sulfuric acid is 1:

4.

6. The method for determining the chromium content in high carbon ferrochrome according to claim 1, characterized in that: In step S4, the concentration of the manganese sulfate solution is 40 g / L, and / or the concentration of the silver nitrate solution is 10 g / L, and / or the concentration of the ammonium persulfate solution is 200 g / L, and / or the concentration of the sodium chloride solution is 50 g / L.

7. The method for determining the chromium content in high carbon ferrochrome according to claim 6, characterized in that: The volume ratio of the manganese sulfate solution, the silver nitrate solution, the ammonium persulfate solution and the sodium chloride solution is 0.5:10:20:

7.

8. The method for determining the chromium content in high carbon ferrochrome according to claim 1, characterized in that: In step S4, the first heating and boiling time is 5 minutes to 8 minutes, and / or the second heating and boiling time is 8 minutes to 10 minutes.

9. The method for determining the chromium content in high carbon ferrochrome according to claim 1, characterized in that: In step S5, the concentration of the N-phenylanthranilic acid indicator is 2 g / L, and / or the concentration of the ammonium ferrous sulfate standard solution is 0.1 mol / L.

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