JB/T 9220.8-1999 Chemical analysis of acidic slag from foundry cupola - Determination of magnesium oxide content by DDTC separation and EDTA volumetric method
Some standard content:
JB/T 9220.8--1999
This standard is a revision of JB/Z284.8-87 "Chemical analysis method of acidic slag of foundry cupola furnace DDTC separation EDTA volumetric method for determination of magnesium oxide content". During the revision, editorial changes were made to the original standard, and the main technical content remained unchanged. This standard replaces JB/Z284.887 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Foundry Standardization. The drafting units of this standard are: Shanghai Diesel Engine Factory, Nanchang Diesel Engine Factory, Guiyang Foundry, Shenyang Foundry, Shanghai Tractor Company, Huafeng Steel Factory, Wuxi Diesel Engine Factory, Changzhou Diesel Engine Factory, etc. The main drafters of this standard are: Wang Zhihan, etc. 448
Standard of the Machinery Industry of the People's Republic of China
Chemical analysis methods for acid slay of cupola Determination of magnesium oxide by DDTCseparation process and EDTA volumetric method1999
JB/T 9220.8
Replace JB/7284.8--87
This standard specifies the determination of magnesium oxide in chemical analysis methods. Determination range: 0.40%~10.00%. This standard is applicable to the analysis of the composition of acid slag of cupola in foundry. 2 Test conditions
The sample is dissolved in hydrochloric acid and hydrofluoric acid to evaporate silicon. Nitric acid and perchloric acid are used to smoke to drive off fluoride ions. Under acidic conditions of pH 6.5, the reagent is precipitated to separate interfering elements such as iron, aluminum, manganese, titanium, chromium, bismuth, and rare earth. Before titration, add EGTA to mask calcium, potassium sodium tartrate-triethanolamine to mask the iron, lead and manganese ions remaining in the filtrate after precipitation and separation. In an ammonium hydroxide medium at pH 10, use chrome black T as an indicator and titrate with EIDTA standard solution.
3 Reagent preparation
3.1 Hydrochloric acid (density 1.19g/mL).
3.2 Hydrochloric acid (1+1).
3.3 Hydrofluoric acid (density 1.15g/mL).
3.4 Nitric acid (density 1.42g/ml).
Perchloric acid (density 1.67g/mL).
Ammonium hydroxide (1+1).
Sodium diethyldithiocarbamate (copper reagent, DDTC) solution (20%), prepare when needed. 3.8
Triethanolamine (1+1).
Propanol (1+1).
3.10 Sodium hydroxide solution (20%).
3.11 Calcium indicator: 1g calcium indicator is mixed with 100g sodium chloride and ground evenly, then dried for use. Ethylene glycol bis(α-aminoethyl) ether tetraacetic acid (EGTA) standard solution 3. 12
3.12.10.02M, weigh 7.6070g EGTA and dissolve it in water, add sodium hydroxide solution (3.10) dropwise to dissolve it completely, transfer it into a 1000ml volumetric flask, dilute it to the mark with water, and mix well. 3.12.20.01M, transfer 100mL EGTA standard solution (3.12.1) into a 200ml volumetric flask, dilute it to the mark with water, and mix well.
3.13 Potassium sodium tartrate solution (10%).
3.14 Ammonium hydroxide-ammonium chloride buffer solution (pH 10): Weigh 67.6 g of ammonium chloride and dissolve it in 200 mL of water. Add 570 ml of ammonium hydroxide (density 0.90 g/ml), dilute with water to 1000 ml, and mix. Approved by the State Bureau of Machinery Industry on June 24, 1999, and implemented on January 1, 2000
JB/T9220.8-1999
3.15 Eriochrome Black T solution (0.5%): Prepared with ethanolamine, or 0.1 g of Eriochrome Black T is mixed with 50 g of sodium chloride and ground evenly. Store in a dry place. 3.16 Disodium Ethylaminetetraacetic Acid (CH4NONa2·2H2O)TA) standard solution 3.16.10.01000M. Weigh 3.7224 g of EDTA (reference reagent) and dry it at 105°C to a constant amount. Place it in a 400 ml beaker, dissolve it with water, and then transfer it to a 1000 ml volumetric flask, dilute it to the mark with water, and mix evenly. 3.16.20.005000M, weigh 100.00mL of DTA standard solution (3.16.1), place in a 200mL volumetric flask, dilute to the mark with water, and mix well.
4 Analysis steps
4.1 Sample volume
Weigh 1.0000g of sample.
4.2 Blank test
Carry out a blank test together with the sample.
4.3 Determination
4.3.1 Place the sample (4.1) in a 250ml polytetrafluoroethylene beaker. Moisten the sample with a small amount of vortex, add 20ml hydrochloric acid (3.1) and 10ml hydrofluoric acid (3.3), heat at low temperature to dissolve, remove and cool slightly after most of the sample has dissolved, add 5ml nitric acid (3.4) and 10ml perchloric acid (3.5) and heat until thick white perchloric acid smoke is emitted for 5~10min, remove and cool, rinse the inner wall with water, add 2ml pernitrogen acid (3.5), continue heating and emit thick white perfluoric acid smoke until 2~3ml solution remains in the cup. Note: The temperature of the heated decomposition sample may not be too high - it usually takes about 30min to dissolve by heating. 4.3.2 Remove and cool, rinse the wall of the cup with water, add 20ml hydrochloric acid (3.2), heat to dissolve the salts, remove and cool, transfer the solution to a 10)ml volumetric flask, dilute to the mark with water, and mix. Note: 4.3.1~4.3.2 are the same as the analytical steps for determining the amount of aluminum monoxide. The dilution can be used for the determination of lead, calcium, and magnesium systems. 4.3.3 Take 25.00ml of the test solution and place it in a 100ml steel volumetric flask. Add 25ml of water. Use ammonium hydroxide (3.6) and hydrochloric acid (3.2) to adjust the pH to 5-6 (use pH test paper to check the pH value). Add 10mL of copper reagent solution (3.7), dilute with water to the scale, and mix. Let it stand for 2h and filter.
Note: 4.3.3 is the same as the analytical steps for determining the amount of calcium oxide. The dilution can be used for the determination of calcium and magnesium systems. 4.3.4 Take two portions of 25.00ml of the filtrate and place them in 250ml conical flasks respectively. 4.3.5-Add 25mL water, 5ml lanthanolamine (3.8). Mix and place, add 5ml propanol (3.9), 10ml sodium hydroxide solution (3.10), calcium indicator (3.11) in appropriate amount, and titrate with EGTA standard solution (3.12.2) until the red color changes to blue-purple. After standing for 1 minute, it turns blue as the end point. Read the titration milliliters (V). Note: The stability constant of calcium-EGTA complex 1gKc-EGTA=10.7, the stability constant of magnesium-EGTA complex 1gKM-EGTA5.1. The difference is five orders of magnitude, so selective titration can be performed. However, in the operation, it is still necessary to prevent excessive EGTA titration, which will cause the magnesium to be too low. Follow 4.3.5 and strictly control the titration end point of calcium. 4.3.6 Add 5mL potassium sodium tartrate solution (3.13), 5mL ethanolamine (3.8), mix and let stand, add 10mL ammonium hydroxide-ammonium chloride buffer solution (3.14), add VmL EGTA standard solution (3.12.2), and add 0.2mL excess, let stand for a while, add appropriate amount of chrome black T solution (3.15), and titrate with EDTA standard solution (3.16.1) until the color changes from red to blue. When the magnesium oxide content of the sample is less than 2%, take 25.00 and 50.00mL of the filtrate respectively. Perform 4.3.5 on the 25.00mL filtrate and titrate with EGTA standard solution (3.12.1). Titration milliliters (V). A 50.00 ml portion of the filtrate was treated according to 4.3.6, with 2 times V mL of EGTA standard solution (3.12.1) added in an excess of 0.2 ml. Titrate with EITA standard solution (3.16.2) to the endpoint.
2 The titration endpoint of magnesium oxide should be blue; if it is green, it is excessive; when the titration is close to the endpoint, the titration speed should be slowed down to ensure the complexation of EIYTA and magnesium and prevent excessive titration.
5 Calculation of analysis results
JB/T 9220.8-1999
Calculate the percentage of magnesium oxide according to formula (1): MgO (V-Vo)MX40. 32)
mX1000bZxz.net
×100%
Where: V.-the volume of EIDTA standard solution consumed in titrating magnesium oxide, mL; Vc-the volume of EDTA standard solution consumed in blank test, mL; M-the molar concentration of EDTA standard solution;
6 Tolerance
Take the sample amount.g:
Molecular weight of magnesium oxide.
The difference in analysis results between laboratories should not be greater than the tolerances listed in Table 1. When calibrated with standard samples, the deviation should not exceed 1/2 of the tolerances listed in Table 1.
Magnesium oxide content
0.40-1.00
21. 00~ 2. 00
Magnesium oxide content
72. 00~5. 00
>5.00~10.00
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