GB/T 5195.8-1985 Chemical analysis method of fluorite - Determination of silicon dioxide content by molybdenum blue spectrophotometry GB/T5195.8-1985 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis methods of fluorspar
The molybdenum blue photometric method for thedetermination of silicon dioxide contentThis standard applies to the determination of silicon dioxide content in fluorspar. Determination range: 0.10~2.00%. UDC 549.454
: 546.28 -- 31
GB5195.8—85
This standard complies with GB1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
The sample is melted with sodium carbonate-borax and leached with dilute hydrochloric acid. At an acidity of 0.05-0.20N, silicic acid and ammonium molybdate are reacted to form yellow silicomolybdic heteropoly acid, and ethanol is added to improve the sensitivity and stability of the method. Adjust the acidity to 3N to eliminate the interference of phosphorus and arsenic, and use ascorbic acid to reduce silicon copper yellow to silicon molybdenum blue. Measure its absorbance at a wavelength of 700nm on a spectrophotometer. 2 Reagents
2.1 Sodium carbonate (reference reagent).
2.2 Mix, grind and mix anhydrous sodium carbonate and borax (NazB.0, ·10H2O) in equal amounts. 2.3 Ethanol.
2.4 Hydrochloric acid (16+84).
2.5 Hydrochloric acid (1+1).
2.6 Ammonium molybdate solution (10%).
2.7 Ascorbic acid solution (1%), prepare it when needed. 2.8 Potassium permanganate solution (1%).
2.9Silicon dioxide standard solution: Weigh 0.2000g of silicon dioxide (reference reagent) that has been pre-calcined at 1050℃ for 5min and placed in a desiccator to cool to room temperature, place in a platinum crucible, mix with 2.0g of sodium carbonate (2.1), and cover with 1.0g. Cover with a lid and leave a small gap, place in a high-temperature furnace, heat to 950℃, melt for 30min, take out, and cool to room temperature. Place the crucible in a 250ml polyfluoroethylene beaker, add 100ml of water, heat to a slight boil, wash out the crucible and lid with water after the melt is completely dissolved, cool to room temperature, quickly transfer to a 1000ml volumetric flask, dilute to the mark with water, and mix. Then quickly transfer to a dry polyethylene bottle for use. This solution contains 0.0002g of silicon dioxide per ml.
3 Instruments
Spectrophotometer.
4 Sample
4.1 The sample should pass through a 240-day sieve.
4.2 The sample should be dried at 105±1℃ for 2h in advance and placed in a desiccator to cool to room temperature. National Bureau of Standards 1985-05-18 Issued
198603-01 Implementation
5 Analysis steps
GB 5195.8-85bzxz.net
5.1 Determination quantity
Three samples should be weighed for determination during analysis and the average value should be taken. 5.2 Sample quantity
Weigh 0.2000g sample.
5.3 Empty self-test
Carry out empty self-test with the sample.
5.4 Determination
5.4.1 Place the sample (5.2) in a platinum crucible pre-filled with 2.0g of sodium carbonate and borax mixed flux (2.2), mix carefully, and cover with 1.0g.
5.4.2 Cover the crucible with a small gap, place it in a high-temperature furnace, heat it from low temperature to 900~950℃, melt it for 20~30min, take it out and cool it.
5.4.3 Place the crucible in a 250ml polytetrafluoroethylene beaker, add 100ml hydrochloric acid (2.4), heat it to a slight boil, and after the melt is completely dissolved, wash out the crucible and lid with hot water, and cool the solution to room temperature. 5.4.4 Filter the solution (5.4.3) into a 200ml volumetric flask with fast filter paper, wash the beaker and filter paper with water 4~5 times each, and dilute to the scale. After mixing, transfer the test solution to another dry plastic cup immediately. 5.4.5 Take 5.00 ml of the test solution (5.4.4), place it in a 150 ml beaker, add 20 ml of water and 1 drop of potassium permanganate solution (2.8), and mix. Add 10 ml of ethanol (2.3) and mix, heat to boiling, and immediately transfer it to a 100 ml volumetric flask containing 2.5 ml of ammonium molybdate (2.6) and mix.
5.4.6 Let the solution (5.4.5) stand for 10 min, add 50 ml of hydrochloric acid (2.5), and mix. Let stand for 2 min, immediately add 5 ml of ascorbic acid (2.7), and mix. Let stand for 30 min, dilute to the mark with water, and mix. 5.4.7 Transfer part of the solution (5.4.6) into a 1 cm colorimetric blood, and measure its absorbance at a wavelength of 700 nm on a spectrophotometer, using the blank sample as a reference. Find the corresponding amount of silicon dioxide from the working curve. 5.5 Drawing of the working curve
Pipette 0.00, 0.10, 0.20, 0.30, 0.40, 0.50, 0.75, 1.00 ml of the silicon dioxide standard solution (2.9) into a set of 150 ml beakers pre-filled with 5.0 ml of blank test solution, and color develop simultaneously with the sample according to 5.4.5 and 5.4.6. Measure its absorbance according to 5.4.7. Draw a working curve with the amount of silicon dioxide as the horizontal axis and the absorbance as the vertical axis. 6 Calculation of analysis results
Calculate the percentage of silicon dioxide according to the following formula: Si02, (%) =
m1V℃×100
Formula: m-
—-Silicon dioxide amount found from the working curve, g!
V,--Volume of the test solution taken, ml;
7 Allowable difference
Sample volume, g.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. 168
Additional instructions:
0.10~0.20
:0.20～1.00
.1.00～2.00
GB5195.885
This standard is proposed by the National Nonferrous Metals Industry Corporation. This standard was drafted by Huainan Chongxing Mining Company of Zhejiang Province. This standard was drafted by Zhejiang Metallurgical Research Institute. The main drafters of the standard are Jiang Guohui and Tang Jinhui. From the implementation of this standard, the original metallurgical industry standard YB322-65 "Chemical Analysis Method" will be invalid.
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