YB/T 178.3-2000 Chemical analysis methods for silicon-aluminium alloys and silicon-barium-aluminium alloys - EDTA titration method for determination of aluminium content
Some standard content:
YB/T178.3---2000
Silicon aluminum alloy and silicon barium aluminum alloy are highly effective deoxidation, desulfurization or grain refinement additives. In order to match its product standards, this industry standard is formulated
This standard was comprehensively tested during the formulation process, focusing on the decomposition conditions of the sample, the separation conditions of coexisting elements, the acid buffer medium of the titration and the recovery rate of aluminum. YB/T178 includes the following parts under the general title of "Chemical Analysis Methods of Silicon Aluminum Alloys and Silicon Barium Aluminum Alloys", and this standard is Part 3.
Determination of silicon content by weight method of perchloric acid dehydration
Determination of barium content by weight method of barium sulfate
Determination of aluminum content by EDTA titration
4) Determination of manganese content by sodium periodate spectrophotometry5)
Determination of phosphorus content by phosphomolybdenum blue spectrophotometry
6) Determination of carbon content by infrared absorption method
Determination of sulfur content by infrared absorption method
This standard is proposed and managed by the Metallurgical Information Standard Research Institute. The drafting unit of this standard is Sichuan Chuantou Emei Ferroalloy (Group) Co., Ltd. The main drafters of this standard are Tang Huaying and He Yanming. 662
1 Scope
Ferrous Metallurgy Industry Standard of the People's Republic of China Methods for chemical analysis of silicon-aluminiumalloy and silicon-barium-aluminium alloyThe EDTA titrimetric method for thedetermination of aluminium contentThis standard specifies the EDTA titrimetric method for the determination of aluminium content. This standard is applicable to the determination of aluminium content in silicon-aluminium alloy and silicon-barium-aluminium alloy. Determination range: 10.00% (m/m) 55.00% (m/m). 2 Referenced standardsbzxZ.net
YB/T 178.3—2000
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T4010--1994 Collection and preparation of samples for chemical analysis of ferroalloys 3 Method Summary
The sample is decomposed with nitric acid-hydrofluoric acid, fluorine is driven out with perchloric acid, and the residue is melted with sodium carbonate-boric acid. After two separations, excess EDTA is added to the slightly acidic solution. At pH 4.5-5.5, xylenol orange is used as an indicator. After the excess EDTA is titrated with zinc standard solution, fluoride ions are used to replace the EDTA coordinated with aluminum, and then titrated with zinc standard solution. 4 Reagents and materials
In the analysis, unless otherwise specified, the instrument uses recognized analytical reagents and distilled water or water of equivalent purity. 4.1 Mixed flux: 200g anhydrous sodium carbonate and 100g boric acid are finely ground and mixed. 4.2 Nitric acid (p=1.42g/ml).
4.3 Hydrofluoric acid (p=1.15g/mL).
4.4 Perchloric acid (p=1.67g/mL).
4.5 Hydrochloric acid (p=1.19g/mL).
4.6 Hydrochloric acid (1+1).
4.7 Hydrochloric acid (1+2).
4.8 Hydrochloric acid (2+98).
4.9 Nitrogen water (o=0.90 g/mL).
4.10 Ammonia water (1+1).
4.11 Saturated sodium fluoride solution: Store in a bottle. Approved by the State Metallurgical Industry Bureau on July 26, 2000, implemented on December 1, 2000
YB/T178.3—2000
4.12 Sodium hydroxide solution (500g/1.): Store in a plastic bottle. 4.13 Hexamethylenetetramine solution (250 g/L). 4.14 Hexamethylenetetramine solution (5 g/L). 4.15 Aluminum standard solution
4.15.1 Weigh 2.5000 g of high-purity aluminum L99.99% (m/m) into a 400 mL polytetrafluoroethylene beaker, add 20 mL of sodium hydroxide solution (4.12) and 100 mL of water, heat on a hot plate until completely dissolved, cool, neutralize with hydrochloric acid (4.6) until the precipitate is dissolved and the excess is 10 mL, cool to room temperature, transfer to a 1000 mL volumetric flask, dilute to scale with water, and mix. 1.00 mL of this solution contains 2.500 mg of aluminum. 4.15.2 Accurately transfer 100.00 mL of solution (4.15.1) into a 250 mL volumetric flask, add 5 mL of hydrochloric acid (4.6), dilute to scale with water, and mix. 1.00mL of this solution contains 1.000mg of aluminum. 4.16 EDTA (dihydrate containing disodium ethylenediaminetetraacetate) solution (0.025mol/L): weigh 9.3g EDTA into a 500mL beaker, add 200ml water, dissolve, transfer to a 1000mL volumetric flask, dilute to scale with water, and mix. 4.17 Zinc standard solution (0.02500mol/L) 4.17.1 Preparation: weigh 2.0477g of standard zinc oxide that has been kept at 800℃ for 1h and cooled to room temperature in a desiccator into a 300mL beaker, add 20mL hydrochloric acid (4.6), dissolve completely with slight heat, add about 200mL water, and drop ammonia water (4.10) until the Congo red test paper turns from blue to purple. Cool to room temperature, transfer to a 1000ml volumetric flask, dilute to scale with water, and mix. 4.17.2 Calibration: Pipette 25.00mL aluminum standard solution (4.15.2) into a 500mL conical flask, add 50mL water, 50mL EDTA solution (4.16), 3 drops of p-nitrophenol indicator (4.18), adjust with ammonia (4.10) and hydrochloric acid (4.6) until the yellow color just disappears and add 5-8 drops of hydrochloric acid (4.6) in excess, add 10mL hexamethylenetetramine solution (4.13), boil for 3min~5min, cool to room temperature, add 6 drops of xylenol orange indicator solution (4.19), and titrate with zinc standard solution (4.17) until red, regardless of volume; add 25ml saturated sodium fluoride solution (4.11), boil for 2min~3min, cool to room temperature, add 2 drops of xylenol orange indicator solution (4.19), and titrate with zinc standard solution (4.17) until red is the end point.
Calculate the titer of zinc standard solution to aluminum according to formula (1): 25.00
Wherein: T--titer of zinc standard solution to aluminum·g/mL; V.--volume of zinc standard solution consumed during calibration, mL; V.--volume of zinc standard solution consumed in reagent blank test during calibration, mL. 4.18 p-Nitrophenol solution (2g/1.).
4.19 Dimethylol orange indicator solution (2g/1.): Prepare it in summer and use it for no more than one week after preparation in winter. 5 Instruments and equipment
Only common laboratory instruments and equipment are used in the analysis. 6 Sample preparation
Sample preparation is carried out in accordance with GB/T4010. The sample should pass through a 0.125mm sieve and be stored in a sealed dry container for 6 months.
7 Analysis steps
Safety instructions: Usually in the presence of ammonia, organic matter, etc., the emission of perchloric acid fumes may cause an explosion. Hydrofluoric acid can seriously burn the human body, and safety measures should be taken when using it.
7.1 Sample quantity
Weigh the sample according to Table 1, accurate to 0.0001g. 664
Aluminum content, %
10.00~40.00
≥40. 00~55.00
7.2 Blank test
Perform a blank test with the sample.
7.3 Determination
YB/T 178. 3--2000
Sample amount g
Dilution volume, ml
7.3.1 Place the sample (7.1) in a platinum beaker (or polytetrafluoroethylene beaker), add 10 ml of nitric acid (4.2), slowly add hydrofluoric acid (4.3) until the sample is dissolved, then add 3 ml to 4 ml of hydrofluoric acid (4.3), heat and evaporate to about 10 ml, remove, rinse the beaker with water, add 15 ml of perchloric acid (4.4), heat until nearly dry, remove, rinse the beaker with water again, add 10 ml of perchloric acid (4.4), continue to evaporate until nearly dry with perchloric acid fumes.
7.3.2 Remove and cool, add 10 ml of hydrochloric acid (4.6) and a small amount of water, and dissolve the salts with slight heat. Transfer to a 400mL beaker and adjust the volume to about 100mL~~150ml. Neutralize with ammonia water (4.9) until a precipitate is produced. Then add hydrochloric acid (4.6) until the precipitate is just dissolved, with an excess of 3~~5 drops. Add 20mL of hexamethylenetetramine solution (4.13), heat to near boiling and keep warm (80℃~90℃) for 15min~20min. Remove and cool slightly, filter with medium-speed filter paper, wash the precipitate 810 times with hexamethylenetetramine solution (4.14), dissolve the precipitate in the original beaker with 30ml hot hydrochloric acid (4.7), wash 8~10 times with hot hydrochloric acid (4.8), and save the solution as the main solution. 7.3.3 Move the filter paper into a platinum crucible, incinerate in a high-temperature furnace at 850℃ for 10min after low-temperature incineration, remove and cool. Add 3g~5g mixed flux (4.1), place in a high-temperature furnace at 950C for 10min to melt until decomposed completely. Take it out and cool it slightly, add about 10mL of hydrochloric acid (4.6) in several times and heat it to extract the melt and combine it with the main solution.
7.3.4 Adjust the volume to about 80ml~120mL, neutralize most of the acid with sodium hydroxide solution (4.12), neutralize with ammonia water (4.10) until a precipitate is produced, and then adjust with hydrochloric acid (4.6) until the precipitate is dissolved, and add 10mL in excess, and boil for 1min~2min. Take it out and cool it slightly, add 40mL of sodium hydroxide solution (4.12) at a time under constant stirring, and boil for 3min~5min. Take it out, cool it to room temperature, dilute it to the corresponding volume as specified in Table 1, and mix it. Let it stand and dry filter. Discard the initial filtrate. 7.3.5 Transfer 100.00mL of the filtrate (7.3.4) to a 500mL conical flask, add 3 drops of p-nitrophenol solution (4.18), adjust with hydrochloric acid (4.5) until the solution becomes colorless, add 50mL of DTA solution (4.16), and boil for 2min3min. Then adjust with hydrochloric acid (4.6) until the solution changes from yellow to colorless and with an excess of 5-8 drops, add 10mL of hexamethylenetetramine solution (4.13), and continue to boil for 2min~~3min. Remove and cool to room temperature. Add 6 drops of cresol orange indicator solution (4.19). Titrate with zinc standard solution (4.17) until red, ignoring the volume.
7.3.6 Add 25mL of saturated sodium fluoride solution (4.11), heat and boil for 2min3min. Remove and cool to room temperature [If the solution turns slightly red, add hydrochloric acid (4.5) while shaking until it just turns yellow and 2 drops are in excess, and add 5mL of hexamethylenetetramine solution (4.13). Add 2 drops of xylenol orange indicator solution (4.19) and titrate with zinc standard solution (4.17) until red is the end point. 8 Calculation of analytical results
Calculate the mass percentage of aluminum according to formula (2): Al (%) = () × 100
Where: T. - the titer of zinc standard solution for aluminum, g/mL; V, - the volume of zinc standard solution consumed when sodium fluoride is added to the test solution and titrated, ml; V2 - the volume of zinc standard solution consumed when sodium fluoride is added to the blank test with the sample and titrated. ml.; m - the amount of sample, g;
- the ratio of the test solution.
The analytical results are expressed to two decimal places. (2)
9 Allowable difference
YB/T 178.3—2000
The difference between two independent analysis results shall not be greater than the allowable difference listed in Table 2. Table 2
10.00~~25.00
>25.00～40.00
40.00~~55.00
10 Test report
The test report shall include the following contents:
a) information on identification of the test material, laboratory and analysis date; b) the degree of compliance with the provisions of this standard;
c) analysis results and their expression;
d) abnormal phenomena observed during the determination;
e) operations that may affect the analysis results but are not included in this standard, or optional operations. 666
%(m/m)
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