Some standard content:
National Standard of the People's Republic of China
Determination of germanium in coals
Determination of germanium
in coals
This standard applies to the determination of germanium in lignite, bituminous coal and anthracite. Distillation separation - benzophenone colorimetric method
This method is used as an arbitration method.
UDC 662. 66 : 543
.06: 546.289
GB 8207-87
Method highlights: After the coal sample is ashed, it is decomposed with a mixed acid of nitric acid, phosphoric acid and hydrofluoric acid, and then a 6 mol/L hydrochloric acid solution is prepared and slurried to make the germanium escape in the form of germanium tetrachloride, which is absorbed by water and separated from the interfering ions. At a hydrochloric acid concentration of about 1.2 mol/L, benzophenone is used for color development and colorimetric determination is performed.
1.1 Reagents
1.1.1 Water: distilled water.
1.1.2 Nitric acid (GB 626--78): chemically pure. 1.1.3 Phosphoric acid (GB1282-77): chemically pure. Hydrofluoric acid (GB620--77): chemically pure. 1.1.4
1.1.5 Hydrochloric acid (GB 622--77): chemically pure, cHCI) = 6 mol/L and 7 mol/L. 1.1.6 Boric acid (GB628-78); chemically pure. 12% sodium sulfite solution: Take 12g of chemically pure anhydrous sodium sulfite (HG3-1078-77); dissolve it in 100mL of water. 1. 1. 7
1.1.81% animal glue solution: Take 1g of animal glue and dissolve it in 100mL of 80~～90℃ water and filter it. Prepare it when using. *.90.05% benzophenone ethanol solution: Take 0.5g of analytical pure benzophenone (9-benzene-2,3,7-trihydroxy-6-benzophenone) in a beaker, add 1.3mL of hydrochloric acid and about 400mL of analytical pure 95% ethanol (GB679-80), heat to dissolve, rinse with ethanol into a 1L volumetric flask, cool and dilute to the scale with ethanol, shake well. 1.1.10 Germanium standard solution: weigh 0.1441g of spectrally pure germanium dioxide into a 100mL beaker, add 1mL of 0.1mol/L analytical pure sodium hydrogen peroxide ((B629·81) solution) and 50mL of water, and heat to dissolve. Then neutralize with 0.1mol/L hydrochloric acid and add 1mL in excess. Then rinse with water into a 1L volumetric flask, dilute to the scale, and shake well. This solution contains 100ug of germanium permL. Or weigh 0.1000g of high-purity metallic germanium into a beaker containing a slightly ammoniacal aqueous solution, add 6% analytical pure hydrogen peroxide (HG3-77), heat on a water bath to slowly dissolve it, then wash it into a platinum crucible with water and evaporate to dryness, add 5g of analytical pure anhydrous sodium carbonate (GB1082
125577) and melt at high temperature, leaching with hot water, dilute sulfur Acid (GB625-77), boil to drive out carbon dioxide. After cooling, wash with water in a 1L volumetric flask and dilute to the mark, shake to hook. 1mL of this solution contains 100ug of germanium. When using, take the above solution and dilute with water to make 1mL of standard solution containing 10μg germanium and 1ug germanium respectively. 1.2 Instruments and equipment
Analytical balance: sensitivity 0.1mg.
Spectrophotometer: wavelength accuracy 510±3nm. Muffle furnace: temperature controllable to 625℃, with a smoke window of 25-30mm diameter on the upper part of the rear wall of the furnace. Electric heating plate: equipped with a temperature control device.
Distillation device for germanium: see figure.
Approved by the Ministry of Coal Industry of the People's Republic of China on August 7, 1987 350
Implementation on July 1, 1988
GB 8207—87
Distillation apparatus for germanium
1—Distillation flask, capacity 50mL; 2—Standard ground mouth with diameter 14mm; 3—Fractional distillation column, the number of herringbone shaped columns is not less than 24; 4—Latex tube; 5—Condenser; 6—Receiver: 50mL viewing tube, cylindrical; 7—Bend pipe with buffer ball, the diameter of the lower end of the bend pipe is 0.5mm8—Electric furnace: furnace plate diameter 50mm, 300W1.2.6 Polytetrafluoroethylene crucible: capacity 30mL. 1.2.7 Volumetric flask: capacity 50mL.
1.2.8 Ash dish: bottom surface is 45mm×22mm, top is 55mm×25mm, height is 14mm. 1.3 Determination steps
1.3.1 Drawing of standard curve Preparation
Take the standard solution containing 0, 1, 5, 10, 15, 20, 30, 40μg germanium, inject it into 50mL volumetric flasks respectively, add 10mL of 6mol/L hydrochloric acid, 2mL of sodium sulfite solution, and 3mL of animal glue solution, and shake well. Then add 5.0mL of benzophenone ethanol solution, dilute to the scale with water, shake well, and place it at room temperature (15-30℃) for 1h, then move the color solution into the colorimetric tank (the colorimetric solution containing 0-10μg of germanium uses a 3cm thick colorimetric tank; 0-40μg uses a 1cm thick colorimetric tank), use the standard blank solution as a reference, and measure its absorbance on the spectrophotometer at a wavelength of 510nm. Use the absorbance as the ordinate and the germanium content as the abscissa to draw a standard curve. The drawing of the standard curve is carried out simultaneously with the determination of the sample solution. 1.3.2 Coal sample treatment
1.3.2.1 Coal sample ash: Weigh 1g of coal sample for analysis (accurate to 0.2mg) and spread it in ash III, then place it in a muffle furnace with the door half open. Gradually heat it from room temperature to 550℃ over about 30min, and keep it at this temperature for 2h, then raise it to about 625℃ and ash it for more than 2h until there are no black coal particles.
1.3.2.2 Ash decomposition: Transfer the ash in the ash dish into a polytetrafluoroethylene crucible, moisten the ash with a small amount of water, add 1mL nitric acid, 2mL phosphoric acid, and 5-7mL hydrofluoric acid (increase or decrease with the silicon content), place the crucible on a low-temperature electric heating plate and heat it until the hydrofluoric acid is driven out, then appropriately increase the temperature until the decomposition product becomes syrupy (volume about 2mL). Cool it slightly, add 2mL water, and heat it to near boiling. 1.3.3 Blank test
Carry out the coal sample treatment procedure, except that no coal sample is added. Two blanks are made for each batch of samples. 1.3.4 Distillation separation of germanium
Pour the ash decomposition product (including blank) into the distillation flask, and rinse the crucible with 15mL of 7mol/L hydrochloric acid three times, about 5mlL each time.351
GB8207-87
Collect the washing liquid in the same distillation flask, add about 0.2g of boric acid, and then connect according to the diagram. Add 10mL of water to the receiver, immerse the tail end of the condenser in water, pass cooling water into the condenser, heat the distillation flask with an electric furnace, and maintain a distillation rate of 1.52mL/min. Stop distillation immediately when the distillate reaches 10mL. Then remove the connection between the fractionation column and the condenser, rinse the condenser and its tail end with a small amount of water, and collect the washing liquid and the solution in the receiver into a 50mL volumetric flask. 1.3.5 Colorimetric determination
Add 2mL of sodium sulfite solution and 3mL of animal glue solution to the above volumetric flask (1.3.4), shake well, add 5.0mL of phenacyl alcohol solution, dilute to the mark with water, and shake well. Leave at room temperature for 1h, then transfer to a 1cm thick or 3cm thick colorimetric cell according to the color depth of the color-developing solution, use the standard blank solution as a reference, and measure its absorbance on a spectrophotometer at a wavelength of 510nm. Subtract the average absorbance of the blank solution from the absorbance of the sample solution, and find the amount of germanium from the corresponding standard curve. If the germanium content of the sample solution exceeds the range of the standard curve, the sample solution should be taken less or the sample weight should be reduced and re-measured, but attention should be paid to adjusting the acidity (the final hydrochloric acid acidity of the color-developing solution is 1.2mol/L). 1.4 Calculation of results
The germanium content in the coal sample is calculated according to the following formula: GV
Gead =Q
Wherein: Gead
The germanium content in the coal sample is analyzed, ppm;
The total volume of the test solution prepared from G (g) sample, mL; The volume of the test solution taken from 1 (mL), mL; The mass of the coal sample, g;
The amount of germanium in V (mL) test solution is obtained from the standard curve, μg. The calculation result is rounded to one decimal place and rounded to the unit place according to the digital rounding rules. The results are reported on a dry basis (Gedppm).
1.5 Allowable error
Parallel determination error shall not exceed the following table: GeabzxZ.net
2 Extraction separation-benzophenone colorimetric method
Relative error, %
Allowable error
Absolute error, ppm
Method points: After the coal sample is ashed, it is decomposed with a mixed acid of nitric acid, phosphoric acid and hydrofluoric acid, and germanium is extracted and separated with carbon tetrachloride in a 9-10 mol/L hydrochloric acid solution. In the slightly acidic medium of carbon tetrachloride ethanol, germanium and benzophenone form an orange-red complex, which is then subjected to colorimetric determination.
2.1 Reagents
2.1.1 Nitric acid, phosphoric acid, hydrofluoric acid, hydrochloric acid, 0.05% benzophenone anhydrous ethanol solution and standard solution of germanium are the same as those in this standard 1.1. Carbon tetrachloride (GB688-79): analytical grade. 2.1.2
Sulfurous acid (HG 3-1083-77): analytical grade. Acetylacetone: analytical grade.
Anhydrous ethanol (GB678-78): analytical grade. 2.2 Instruments and equipment
Analytical balance, spectrophotometer, muffle furnace, electric hot plate, ash blood and polytetrafluoroethylene crucible are the same as those in 1.2 of this standard. 2.2.1
Separatory funnel: conical, capacity 50mL.
2.2.3 Volumetric flask: capacity 25mL.
2.2.4 Colorimetric tube: with cover, capacity 25mL. 2.3 Determination steps
2.3.1 Drawing of standard curve
GB 8207-87
Take the standard solution containing 0, 1, 2, 3, and 4 μg of germanium, respectively, and inject it into the separatory funnel containing 10.0 mL of carbon tetrachloride, and dilute it with water to 5.0 mL. Add 2 drops of sulfurous acid and 20 mL of hydrochloric acid, and shake for 2 minutes. After standing and stratification, put the carbon tetrachloride extract into a dry small container.
Add 0.2 mL of acetylacetone, 1 mL of benzophenone anhydrous ethanol solution, and 5.0 mL of carbon tetrachloride extract to a 25 mL colorimetric tube, dilute it to 10 mL with anhydrous ethanol, and shake well. After 5 minutes, transfer the color-developing solution into a 1 cm thick covered colorimetric tank, use the standard blank solution as a reference, and measure its absorbance at a wavelength of 510 nm on a spectrophotometer. Draw a standard curve with absorbance as the ordinate and germanium content as the abscissa.
The drawing of the standard curve is carried out simultaneously with the determination of the sample solution. 2.3.2 Coal sample treatment: Same as 1.3.2 of this standard, except that a 25mL volumetric flask is used for dilution. 2.3.3 Blank test: Same as 1.3.3 of this standard, except that a 25mL volumetric flask is used for dilution. 2.3.4 Extraction and separation of germanium
Take 5.0mL of the above solution (2.3.2 and 2.3.3) (when the germanium content is greater than 4μg, a small amount of test solution can be taken and diluted to 5.0mL with water), put it into a separatory funnel containing 10.0mL of carbon tetrachloride, add 5-10 drops of sulfurous acid and 20mL of concentrated hydrochloric acid, and shake for 2min. After standing and stratification, transfer the carbon tetrachloride extract into a dry small container with a lid. 2.3.5 Colorimetric determination
Add 0.2mL of acetylacetone, 1mL of benzophenone anhydrous ethanol solution, and 5.0mL of carbon tetrachloride extract to a 25mL colorimetric tube. Dilute to 10mL with anhydrous ethanol and shake well. After 5 minutes, transfer the color solution into a 1cm thick covered colorimetric tank, use the standard blank solution as a reference, and measure its absorbance at a wavelength of 510nm on a spectrophotometer. Subtract the average absorbance of the blank solution from the absorbance of the test solution, and find the amount of germanium from the standard curve.
2.4 Result calculation: Same as 1.4.
2.5 Allowable difference: Same as 1.5.
Additional remarks:
This standard is under the jurisdiction of the Beijing Coal Chemistry Research Institute of the Coal Research Institute. This standard was drafted by the Beijing Coal Chemistry Research Institute of the Coal Research Institute and the laboratory of the Hebei Coalfield Geological Exploration Company. The main drafter of this standard is Ma Zunmei.
This standard is entrusted to the Beijing Coal Chemistry Research Institute of the China Coal Research Institute for interpretation.
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.