HG 2958.2-1988 Determination of barium content in celestite ore - Barium chromate volumetric method
Some standard content:
Chemical Industry Standard of the People's Republic of China
Determination of barium content in celestite ore
Barium chromate volumetric method
Celestite ores-Determination of barium cantent -Bariumchromate volumetric method
1 Subject content and scope of application
This standard specifies the determination of barium content in celestite ore by chromic acid volumetric method. This standard is applicable to celestite ore products with an oxidation content of 0.5% to 10%. 2 Reference Standards
GB9018.1 Determination of Sr and Calcium Content in Celestite Ore-EDTA Volumetric Method 3 Method Summary
UDC549.761.3
：543.06
HG/T 2958.2-1988 (1997)
Replaces GB9018.2-88
The sample is melted with sodium carbonate and sodium hydroxide to convert it into carbonate, and the sulfate ion is separated. The precipitate is dissolved with hydrochloric acid and indirectly determined by the barium iodine method with ammonium dichromate precipitation in acetic acid-sodium acetate solution with pH~5.9. The interference of iron and strontium is eliminated by adding a certain amount of EDTA.
4 Reagents and solutions
4.1 Anhydrous sodium carbonate (GB639-77);
4.2 Sodium carbonate; 5% solution;
4.3 Sodium carbonate washing solution: 1% solution;
4.4 Sodium hydroxide (GB629-81);
4.5 Sodium peroxide;
4.6 Triethanolamine: 1+4 solution;
Hydrochloric acid (GB622-77): 1+1 solution;
Hydrochloric acid: 1+4 solution;
Hydrochloric acid: 1+9 solution;
Water ( GB631-77): 1+1 solution;
Methyl red (HG3-958-76): 0.1% ethanol solution; ammonium acetate (GB1292-77): 1% solution; 4.12
Ethylenediaminetetraacetic acid disodium (EDTA) (GB1401-78): 5% solution; EDTA: 2% solution;
Ammonium thiocyanate (GB660-78): 1% solution; ammonium dichromate (GB656-77): 10% solution; 4.16www.bzxz.net
Potassium iodide (GB1272-77): 20% solution. Paste in a brown bottle; 4.18
Starch: 1% solution. Weigh 1g soluble starch and dissolve it in 100ml boiling water (prepare before use); Approved by the Ministry of Chemical Industry of the People's Republic of China on March 21, 1988 and implemented on December 1, 1988
4.19 Glacial acetic acid (GB676-78);
4.20 Anhydrous sodium acetate (GB694-81);
HG/T2958.2-1988(1997)
4.21 Acetic acid-sodium acetate buffer solution (pH~5.9): Weigh 164g anhydrous sodium acetate (4.20) and dissolve it in water, add 7.5ml glacial acetic acid (4.19), dilute with water to 1000ml, and shake to hook; 4.22 Potassium dichromate standard solution: c
K,CrO)=0.01000mol/L. Weigh 0.4904g of potassium dichromate (standard reagent) dried at 120℃ to constant weight and place it in a 250ml beaker. After dissolving in water, transfer it to a 1000ml volumetric flask, dilute with water to the mark, and shake well; 4.23 Sodium thiosulfate (Na2S,O·5H,O) (GB637-77); 4.24 Sodium thiosulfate standard solution: c (Na,S,O·5H,O) = 0.01mol/L; 4.24.1 Preparation: Weigh 2.5g of sodium thiosulfate (4.23) and dissolve it in freshly boiled and cooled distilled water, add 0.2g of anhydrous sodium carbonate (4.1), dilute to 1000ml with freshly boiled and cooled distilled water, shake well, and store in a brown bottle. After leaving for 10 days, filter and calibrate and use.
4.24.2 Calibration: Pipette 20.00ml potassium dichromate standard solution (4.22) into a 250ml beaker, add 6ml hydrochloric acid (4.7), dilute to 100ml with water, and proceed as per analysis step 6.5. Perform a blank test at the same time.
4.24.3 Calculation of concentration:
The concentration (c) of sodium thiosulfate standard solution is calculated according to formula (1): GV
c=VV.
Where: V. - Volume of sodium thiosulfate standard solution consumed in titration of blank test solution, ml; V, - Volume of potassium dichromate standard solution absorbed, ml; V--Volume of sodium thiosulfate standard solution consumed during titration, ml; C
5 Sample
-Concentration of potassium dichromate standard solution, mol/L. (1)
The sample is passed through a 0.075mm sieve (GB6003-85), dried at 105~110°C to constant weight, and placed in a desiccator to cool to room temperature. 6 Analysis steps
6.1 Weigh 0.2g of sample (0.1g of sample when the barium oxide content is greater than 5%) (weigh to 0.0002g), carefully mix in a silver crucible pre-paved with 3g of sodium carbonate (4.1), add a small amount of sodium peroxide (4.5) and 3g of sodium hydroxide (4.4), and cover the crucible (leave a gap).
Place in a muffle furnace, slowly raise from low temperature to 500°C, stay for 10 minutes, continue to raise to 700~750°C, keep for 30 minutes, take out and cool. Place the crucible in a 250ml beaker containing 100ml sodium carbonate solution (4.2), add 15ml triethanolamine (4.6), cover the surface blood, and heat on a hot plate to extract (slightly boil for more than 1h). Wash the crucible with water [if necessary, use 2~3 drops of hydrochloric acid (4.9) to dissolve the residue on the crucible wall].
Filter with dense filter paper, wash the beaker with sodium carbonate solution (4.3) 4~5 times, and wash the precipitate more than 12 times (wash until there is no sulfate). 6.2 Cover the funnel with a watch glass, dissolve the precipitate on the filter paper with 10ml hydrochloric acid (4.8) in batches in the original beaker, and wash the filter paper with hot water [containing a few drops of hydrochloric acid (4.8)]. Dilute the solution to 100ml with water, heat and boil for 23min to drive out all the carbon dioxide. Remove and cool slightly, add 2 drops of ammonium thiocyanate solution (4.15), add EDTA solution (4.14) drop by drop until the red color disappears and the solution is light yellow or colorless. Note: You can also take 100.0ml of solution (if the barium oxide content is greater than 5%, take 50.00ml of solution) from the B solution prepared in 5.2 of GB9018.1 into a 250ml beaker, and proceed as follows 6.3 to 6.5. 6.3 Add 2 drops of methyl red indicator solution (4.11), adjust the solution to yellow with ammonia water (4.10), and then adjust it with hydrochloric acid (4.8) until light red just appears: (If silicate precipitates at this time, it will not affect the determination). Add 10 ml of acetic acid-sodium acetate buffer solution (4.21), heat to 7050
HG/T2958.2-1988 (1997)
80℃, remove, add 5 ml of ammonium dichromate solution (4.16) dropwise while stirring constantly, and add 7.0 ml of EDTA solution (4.13) dropwise while stirring continuously (add 3.0 ml of EDTA solution for samples with oxidation content less than 1%). Place the beaker and its contents in a 80~90℃ water bath for 2 hours, remove, and let stand for more than 2 hours.
6.4 Filter the precipitate with dense filter paper, wash the precipitate on the filter paper 3 times with ammonium acetate solution (4.12), and wash the beaker 4~5 times. Wash the precipitate on the filter paper again until the orange color of the filter paper disappears and the filter paper of the blank test is colorless. Discard the filtrate. Use 15ml hydrochloric acid (4.8) to dissolve the precipitate in the original beaker, wash the filter paper with hot water, dilute the solution to 100ml with water, and cool to room temperature.
6.5 Add 10ml potassium iodide solution (4.17), stir well, titrate with sodium thiosulfate standard solution (4.24) until the solution turns light yellow, add 2ml starch solution (4.18), and continue titrating until the blue color disappears as the end point. Record the volume of sodium thiosulfate standard solution consumed. Perform a blank test at the same time.
7 Calculation of analysis results
The percentage content of oxide (X) is calculated according to formula (2): c(V-Vo)x0.05111
Where: V. —Volume of sodium thiosulfate standard solution consumed by titrating blank test solution, ml; -Volume of sodium thiosulfate standard solution consumed by titrating test solution, ml; V
Concentration of sodium thiosulfate standard solution, mol/L; Mass of sample, g;
0.05111——1.00ml sodium thiosulfate standard solution (c(NazS,0)=1.000mol/L) is equivalent to the mass of oxidation, g. 8 Allowable difference
The difference of the results of determination in the same laboratory should be less than the value shown in the table below. %
Oxidation collar
0.50~1.00
>1.00~3.00
>3.00~5.00
>5.00-10.00
Additional Notes:
This standard is under the jurisdiction of the Chemical Industry Mine Design and Research Institute. This standard was drafted by the Chemical Industry Mine Design and Research Institute. The main drafter of this standard is Liu Lihua.
Allowance
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