HG 2957.7-1984 Determination of potassium and sodium content of alum ore Potassium tetraphenylborate gravimetric method and flame emission spectrophotometric method
Some standard content:
National Standard of the People's Republic of China
Determination of potassium and sodium contents of alunite ore
Potassium borate gravimetric method and flame emission spectrophotometric nethodsAlunite ores-Determination of potassium and sodium contents-Potassium tetraphenylborate gravimetricmethod and flame emission spectrophotometric nethodsScope of application
This standard specifies the following method for determining the content of oxide and sodium oxide in alunite ore:UDC 549.762:543
.21 + 543.42
:546,32.33
GB 4581.T-84
Sea: e
Formula 1: Potassium tetraphenylborate gravimetric method for determining the potassium oxide content of alunite ore less than 1.00% to 7.00%! Method II: Flame emission spectrophotometry was used to determine the potassium oxide content of 1.00-7.00% and the sodium oxide content of 0.10-2.00% in alum stone.
2 Relevant standards
GB4581.1-84 (General rules for the analysis of alum ores). GB4581.2-84 "Methods for the sampling and preparation of alum ores". Method "Potassium tetraphenylborate gravimetric method
3 Summary of the method
The sample is decomposed by hydrofluoric acid and leached with alkali solution. In a slightly acidic medium, potassium ions react with sodium tetraphenylborate to form potassium tetraphenylborate precipitate. The precipitate is dried at 160℃, weighed, and the potassium oxide content is calculated. 4 Reagents and solutions
Potassium chloride (GB 646-77).
4.2 Aluminum hydroxide.
Hydrochloric acid (GB622-77) (specific gravity 1.19): 1+1.4.3
4.4 Sulfuric acid (GB 625-77) (specific gravity 1.84): 1+1 . Hydrofluoric acid (GB620-77) (40%).
4.B Citric acid (HG 3--1108-81): 10%. 4.7
Sodium hydroxide (GB629-81): 8%.
Sodium hydroxide: 20%.
4.9 Methyl orange (HGB 3089-59): 0.1%. 4.10 Sodium tetraphenylborate (HG3-1164-78): 1. Weigh 5 g of sodium tetraphenylborate in a 600 ml beaker, add 500 ml of water to dissolve, then add 0.5 g of aluminum hydroxide (4.2), stir to mix, and adjust the pH of the solution to 7-8 with sodium hydroxide solution (4.8). Filter with dense filter paper before use.
4.11 Potassium tetraphenylborate saturated wash solution, dissolve about 40 mg of analytical pure potassium chloride (1.1) in water, and add dichloromethane to make the solution slightly acidic (pH*4) , dilute to about 100 ml. Add 25 ml of sodium tetraborate solution (4.10) dropwise while stirring. Let stand for 10 to 15 minutes. Filter. Wash with water 10 times. Transfer the obtained precipitate into 1000 liters of water, add 1 gram of aluminum hydroxide (4.2), and stir vigorously for several minutes. Then leave it overnight and filter before use. 4.12 Bo Nao Kun crucible (No. 4)
5 Determination procedures
GB 4581.784www.bzxz.net
Weigh 0.5 g of the sample, put it in a plastic crucible, moisten it with a little water, add 1 ml of hydrochloric acid (4.5), add 5 drops of sulfuric acid solution (4.4), heat it on a hot plate at low temperature to dissolve the sample, and shake it from time to time, and increase the temperature to evaporate all the sample. Add 5 millimolar hydrofluoric acid (4.4) and continue to evaporate until white smoke disappears. Add 10 ml of sodium hydroxide solution (4.7) and boil it for 20 minutes. Remove it and cool it, then transfer it to a 100-liter bottle, dilute it with water to 40°, shake it well. Dry filter it. Pipette 50 ml of the filtrate into a 150-ml beaker. Add 10 ml of citric acid solution (4.6). Stir well, add 2 drops of methyl orange indicator solution (4.9), neutralize it with hydrochloric acid solution (1.3) until it turns red, then neutralize it with sodium hydroxide solution (4.8) until the solution turns yellow, and dilute it with water to 100 ml. Add 20 ml of sodium tetraphenylborate solution (4.10) dropwise while stirring continuously. Cover with surface III and let the precipitate stand for 10-15 minutes. Filter with a heavy glass crucible (4.12). Wash the precipitate 3 times with saturated potassium tetraborate washing solution (4.11), transfer the precipitate to a glass, wash the precipitate 8 times, and finally wash the precipitate 2 times with water (about 5 ml of water each time). After filtration, place the crucible in an oven at 1.60℃ and dry for 1.5 hours, take out, cool, weigh, and dry again to constant weight. 6. Expression and calculation of results
The percentage of potassium oxide (K,O) (X) is calculated according to (1): ×G×0.1314
Where: V
7Tolerance
Method Summary
Total volume of test solution, ml
Volume of aliquoted solution, ml,
Weight of potassium tetraphenylborate precipitate, g:
Weight of sample, g;
Factor for converting potassium tetraphenylborate into potassium oxide. Potassium oxide content, %,
1. 00 ~ 5. 00
Tolerance (absolute),
Method II Flame Emission Spectrophotometry
The sample is decomposed by hydrofluoric acid and sulfuric acid. Extracted by dilute nitric acid. The radiation intensity is measured by potassium filter and sodium filter respectively on the flame photometer. Use the standard curve method to analyze the content of potassium oxide and sodium oxide. Instruments
Light flame photometer: potassium filter (wavelength 766 nanometers or K·77J) sodium filter (wavelength 590 nanometers or Na·59J) 15
10, Reagents and solutions
10.1 Potassium chloride (GB 646-77).
10.2 Sodium chloride (GB 1266-77).
GB 4581.7-84
10.3 Nitric acid (GB626-78) (specific gravity 1.42): 1+1. Sulfuric acid (GB 625-77) (specific gravity 1.84): 1 + 1. 10.4
10.5 Hydrofluoric acid ((GB 620-77)) (40%). 10.6 Potassium oxide, sodium oxide mixed standard solution: each milliliter contains 1.000 mg potassium oxide and 0.200 mg sodium oxide. Weigh 1.5829 g potassium fluoride (10.1) and 0.3772 g sodium chloride (10.2) dried to constant weight at 105-110°C in a beaker, add water to dissolve, transfer to a 1000 ml volumetric flask, dilute with water to the mark, and shake to hook. 11 Determination procedures
11.1 Drawing of standard curve
Use a burette to place 10.00, 20.00, 30.00, 40.00, and 50.00 ml of the mixed standard solution of potassium oxide and sodium oxide (10.6) in a 1000 ml volumetric flask, add 10 ml of nitric acid solution (10.3) to each, dilute to the scale with water, and shake the hook. Take out a small amount of solution and measure its radiation intensity on a flame photometer using a potassium filter and a sodium filter, respectively. Use the concentration of potassium oxide and sodium oxide as the horizontal pendant and the galvanometer reading as the vertical axis to draw the standard curves of potassium oxide and sodium oxide, respectively. 11.2 Sample analysis
Weigh 0.1~0.2 g of sample into a plastic crucible, moisten it with a small amount of water, add 5 drops of acid solution (10.4) and 10 ml of hydrofluoric acid (10.5). Heat on a hot plate at low temperature for decomposition, and shake from time to time to increase the temperature. Heat until sulfuric acid smoke is exhausted. Remove and cool, add 1 ml of nitric acid solution (10.3) and 10 ml of water. Heat to dissolve soluble salts. After cooling, transfer to a 100 ml volumetric flask, dilute with water to the mark, shake the spoon, and dry filter.
Take part of the filtrate on a flame photometer, use potassium filter and sodium filter to measure its radiation intensity respectively. Compare with the standard curve to calculate its content.
Note: ① If the content is high or the measured value falls on the curved part of the standard curve, you can reduce the amount of sample or dilute the solution so that the measured value falls on the straight line.
② When using a domestic flame photometer, the standard solution must be prepared according to the ratio of sodium to potassium in the sample. 12 Expression and calculation of results
The percentage content (X) of potassium oxide (K20) or sodium oxide (NazO) is calculated according to formula (2): X
Where: Gr
G ×10-3×n
-The maximum weight of potassium oxide or sodium oxide in the test solution obtained from the standard curve, mg sample weight, g,
-The ratio of the total volume of the test solution to the volume of 100 ml. 2
Tolerance
Potassium oxide content, %
1.00 ~ 5. 00
Sodium oxide content, %
0.10~0.50
0. 51 ~1. 00
1. 01 ~ 2. 00
GB 4581.7-84
Tolerance (absolute value), %
Additional remarks:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China and is under the jurisdiction of the Chemical Industry Design and Research Institute of the Ministry of Chemical Industry. This standard is drafted by the Chemical Industry Design and Research Institute of the Ministry of Chemical Industry. The main drafter of this standard is Cheng Maomei.
From the date of implementation of this standard, the Xia Chemical Industry Department Standard HG1-353-66 "Alum Stone System·Analysis Method" shall be invalid.
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