This standard is applicable to the determination of gallium in lignite, bituminous coal and anthracite. GB 8208-1987 Determination of gallium in coal GB8208-1987 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of gallium
in coals
This standard applies to the determination of gallium in lignite, bituminous coal and anthracite. UDC662.66:543
06:546.681
GB8208 --- 87
Method points: After the coal sample is ashed, it is decomposed with a mixed acid of sulfuric acid, hydrochloric acid and hydrofluoric acid to prepare a 6mol/L hydrochloric acid solution; or the coal ash is melted with alkali, acidified with hydrochloric acid, evaporated to dehydrate the silicic acid and prepare a 6mol/L hydrochloric acid solution. Then add titanium dichloride solution to the above solution to reduce iron (III), armor (II), antimony (V) and the like to low valence to remove interference. Then add rhodamine B solution to form a colored complex with chlorogallic acid, and extract with benzene-ethyl ether. Then perform colorimetric determination. 1 Reagents
1.1 Water: distilled water. www.bzxz.net
1.2 Sulfuric acid (GB625-77): chemically pure, (1+1) solution. Hydrochloric acid (GB 622-77): chemically pure, c(HCI)=6 mol/L. 1.3
Hydrofluoric acid (GB620-—77): chemically pure. 1.4
Sodium hydroxide (GB629--81): chemically pure. 1.6
Ethanol (GB679--80): chemically pure, 95%. Titanium trinitride solution (HGB3122--59): analytically pure. 1.7
1.80.5% Rhodamine B solution: weigh 0.5g of analytically pure Rhodamine B (HGB3509-62) and dissolve it in 100mL 6mol/L hydrochloric acid,
1.9 Benzene-ether mixed solvent: mix 1 part of analytically pure benzene (GB690--77) with 1 part of analytically pure ether (HG3-100276). 1.10 Gallium standard solution: weigh 0.1000g of pure metal gallium and put it in 6mol/L hydrochloric acid, heat it at low temperature to dissolve it. In order to promote dissolution, a platinum wire can be placed in contact with gallium. After it is completely dissolved, wash out the platinum wire with 6mol/L hydrochloric acid, cool it, transfer it to a 1L volumetric flask, and dilute it to the scale with 6mol/L hydrochloric acid, and shake it well. This solution contains 100ug of gallium in 1.mL. Or weigh 0.1344g of spectrally pure gallium trioxide into a beaker, add 20~~30mL of 6mol/L hydrochloric acid, heat on a water bath until completely dissolved, remove and cool. Wash into a 1L volumetric flask with 6mol/L hydrochloric acid, dilute to the mark with 6mol/L hydrochloric acid, and shake the hook. This solution contains 100μg of gallium in 1mL.
Take the above solution and prepare 1mL of standard solution containing 10μg gallium and 1μg gallium respectively with 6mol/L hydrochloric acid. 2. Instruments and equipment
2.1 Analytical balance: sensitivity 0.1mg.
Spectrophotometer: wavelength accuracy 560±3nm. 2.2
2.3 Muffle furnace: can control the temperature to 700℃, and there is a smoke window with a diameter of 25~30mm on the upper part of the back wall of the furnace. 2.4 Electric heating plate: equipped with a temperature control device.
2.5 Ash dish: bottom surface is 45mm×22mm, top is 55mm×25mm, height is 14mm. 2.6 Polytetrafluoroethylene crucible: capacity 30mL.
2.7 Silver snail: capacity 30mL, with cover.
Ministry of Coal Industry of the People's Republic of China approved 351 on August 7, 1987
implemented on July 1, 1988
2.8 Volumetric flask: capacity 50ml.
2.9 Book cover colorimetric tube: capacity 25ml
2.10 Beaker: capacity 250mL.
3 Determination steps
3.1 Drawing of standard curve
GB 8208--87
Take the standard solution containing 0, 1, 2, 3, 4, 5ug of gallium, respectively, and inject it into 25mL covered colorimetric tubes, and dilute it to 10.0ml with 6mol/L hydrochloric acid. Add 0.5mL of titanium chloride solution and spread it evenly. After standing for 5min, add 2mL of rhodamine B solution and shake it evenly. Then add 6.0mL of a-ether mixed solvent and extract for 2min. After standing and stratifying, wipe the mouth and cover of the colorimetric tube with filter paper, and carefully absorb the organic extract with a dry pipette, put it into a "cm thick cover colorimetric tank, use benzene-ether solvent as reference, and use a wavelength of 560 on the spectrophotometer. nn Measure its absorbance, use absorbance as the ordinate and gallium content as the abscissa to draw a standard curve. When comparing colors by Kawaguchi, the concentration interval of the standard series solution is required to be smaller. The color development procedure is the same as above. The drawing of the standard line or the preparation of the standard series solution should be carried out simultaneously with the determination of the sample solution. 3.2 Coal sample processing!
3.2.1 Coal sample decomposition: Weigh 1g of the analytical coal sample (accurate to 0.2mg) and spread it flat in ash III, then place it in a muffle furnace, half open the furnace door, gradually heat it from air humidity to 550c after about 30min, and keep it at this temperature for 2h, then raise it to about 700℃, and decompose it for more than 2h. No color coal particles:
3.2.2 Decomposition of decomposition ||tt ||3.2.2.1 Alkali fusion method; This method is used as a secondary loading method. Move the ash from ash III into a silver glass with a lid, moisten the ash with ethanol, and add 2-4g of sodium hydroxide as appropriate according to the amount of ash. Then send the crucible into a muffle furnace, gradually raise the temperature from 650 to 700°C, and melt for 15 minutes. Cool it and place it in a 250mL beaker with a lid, add 1mL of alcohol and 100mL of boiling water to the crucible. After the leaching is completed, wash out the crucible and its lid with hot water. Slowly add 10mL of hydrochloric acid from the mouth of the beaker. After the molten material is completely dissolved, remove the lid of the beaker and rinse with water. Then place the beaker on a low-temperature electric heating plate and heat it to evaporate the solution. When the salts are precipitated and slightly dry, use a flat-headed glass rod to continuously stir. Stir and crush the salt block until it is completely dry and cool slightly, then add 50.0mL of 6Inol/L hydrochloric acid and stir thoroughly. Let it stand to clarify and prepare for colorimetric determination. 3.2.2.2 Acid dissolution method: transfer the ash from the ash m into a polytetrafluoroethylene crucible, moisten the ash with a small amount of water, add 0.5mL of sulfuric acid (1+1) solution, 3mL of hydrochloric acid, and 5~7mL of hydrofluoric acid (increase or decrease with the silicon content), place the crucible on a low-temperature electric heating plate and heat until the hydrofluoric acid is completely driven out and then increase the temperature appropriately. Stop until white smoke from sulfuric anhydride is emitted. Let it cool slightly, then add about 5mL of 6mol/L hydrochloric acid and heat to basically dissolve the salts. Cool and rinse with 6mol/L hydrochloric acid into a 50mL salt bottle to make up the volume, shake well and let it stand for comparison. For color determination. 3.3 Blank test
The sample is processed in reverse order, and no coal sample is added. Two blank tests are performed for each batch of samples. 3.4 Colorimetric determination (spectrophotometry as arbitration method) Take 10.0 mL of the above-mentioned liquid (3.2.2 and 3.3) (if the gallium content is high, less test solution can be taken and diluted to 10.0 mL with 6 mol/L hydrochloric acid) into a colorimetric tube with a cap, add the slaked titanium solution dropwise until the solution turns a stable purple color, then add 0.5 mL more, let stand for 5 minutes, add 2 ml of rhodamine B solution and shake with a spoon. Then add 6.0 mL of benzene-ether mixed solvent and extract for 2 minutes. After static stratification, use filter paper to burn the colorimetric tube clean, and use a dry pipette to carefully draw the organic solution into a 1 cm thick colorimetric trough with a cap, use benzene-ether solvent as a reference, and measure its absorbance at a wavelength of 560 nm on a spectrophotometer. Subtract the average absorbance of the blank solution from the absorbance of the test solution, and find the gallium content from the standard curve. When using the standard curve, the gallium content in the blank solution should be obtained, and then deducted from the measurement result. 4 Calculation of results: The gallium content in the analyzed coal sample is calculated according to the following formula: GE: Where: Gaad: Gallium content in the analyzed coal sample, ppm;
-mass of the analyzed coal sample, g;
GB8208---87: Total volume of the test solution prepared from G (g) coal sample, mL; Volume of the test solution taken from (mL), mL; Find the gallium content in (mL) test solution from the standard curve, ug. G: The calculated result is rounded to one decimal place and rounded to the unit place according to the digital rounding rules. The result is reported on a dry basis (Gaa, ppm). Allowable difference
Parallel measurement difference shall not exceed the following table:
Gaa content
10～50
Additional instructions:
Relative difference, %
Allowable difference
Absolute difference, ppm
This standard is under the jurisdiction of Beijing Coal Chemistry Research Institute of Coal Science Research Institute. This standard was drafted by Beijing Coal Chemistry Research Institute of Coal Science Research Institute and the laboratory of Hebei Coalfield Geological Exploration Company. The main drafter of this standard is Ma Zunmei.
This standard is entrusted to Beijing Coal Chemistry Research Institute of Coal Science Research Institute for interpretation. 356
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