HG 2958.6-1988 Determination of silicon content in celestite ore Perchloric acid dehydration gravimetric method HG2958.6-1988 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of silicon content in celestite ore
Perchloric acid dehydration gravimetric method
Celestite ores-Determination of silicon content—Perchloric acid zciddchydration gravimetric method Subject content and scope of application
This standard specifies the determination of silicon content in celestite ore by perchloric acid dehydration gravimetric method. This standard is applicable to celestite ore products with silicon monohydride content greater than 15%. 2 Method Summary
UDC 549.761. 3
GB 9018.6—88
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The sample is pre-burned at 1200℃ to remove most of the sulfate, melted with sodium hydroxide, leached with hydrochloric acid, evaporated with pernitrogen acid to remove the smoke, and dehydrated the silicate. Filter, burn, and remove silicon with hydrochloric acid. Weigh the residue and calculate the base content of silicon dioxide by its weight loss. 3 Reagents and solutions
3.1 Sodium hydroxide (G1629-81),
3.2 Sodium perhydride;
3.3 Hydrochloric acid (GB622-77);
3.4 ​​Hydrochloric acid: 1+1 solution:
3.5 Hydrochloric acid: 119 solution;
3.6 Hydrochloric acid: 1-99 solution:
3.7 Hydrogen acid (GB62377) (70%);
3.8 Sulfuric acid (GB625-77): 1+1 solution; 3.9 Hydrofluoric acid (CB620-77) (40%).
The sample passes through a 75mm sieve (GB6003-85): 105110℃ dry to constant weight, place in a desiccator and cool to room temperature, 5 Analysis steps
5.1 Weigh 0.3~~0.5g of sample (accurate to 0.0002%) and place in a corundum crucible, send it into a muffle furnace that has been heated to 800℃, continue to heat to 1200, and burn at this temperature for 1h. Take it out and cool it. 5.2 Add 4% sodium hydroxide (3.1) to the burned sample. Add a little sodium peramide (3.2), place the crucible in a muffle furnace, raise the temperature to 300℃, stay for 10min, continue to raise the temperature to 700℃, keep it for 30min, take it out and cool it. Place it in a muffle furnace In a 250mL beaker containing 40ml of hot water, cover the surface with blood, and immediately add 30mL of hydrochloric acid (3.3) from beaker 11 slowly, shaking while adding to avoid too intense reaction. After the reaction stops, wash with a small amount of hydrochloric acid (3.4) and hot water. 5.3 Place the beaker and its contents on the electric hot plate 1: heat and evaporate the solution to 70mL, add 10mL of hydrochloric acid (3.3), 25mL of perchloric acid (3.7), and continue evaporating until thick perchloric acid white smoke appears, but avoid evaporating downward. 5.4 Dissolve Liquid cooling. Add 1.5mL hydrochloric acid (3.4), rinse the surface blood and the wall of the beaker with hot water, heat and stir to dissolve the soluble salts and let it stand for a while. bzxz.net
Filter with medium-speed filter paper with a small amount of paper pulp, wipe the precipitate on the wall of the beaker with a glass beaker with an eraser, and transfer the precipitate to the filter paper. Wash the beaker with water 2~3 times, wash the precipitate with hot hydrochloric acid (3.5) 6~7 times, and finally wash it with warm water more than 8 times (the perchloric acid must be washed off). 5.5 Evaporate the filtered solution to 70mL, add 15mL perchloric acid (3.7), and repeat the evaporation until thick perchloric acid white smoke is emitted. Avoid evaporation and dryness. The following analysis steps are carried out according to 5.1. In which the hydrochloric acid washing solution (3.5) is replaced with a more diluted Hydrochloric acid washing solution (3.6). 5.6 Place the filter paper with precipitate obtained twice in a platinum crucible, carefully dry it to ashes, then place it in a muffle furnace and burn it at 950C for 1h. Take it out, cool it in a desiccator, weigh it, and repeat the burning until constant weight. Moisten the precipitate with a few drops of water, add 5 drops of sulfuric acid (3.8), 5~15mL of hydrofluoric acid (3.9), and heat to evaporate all the white smoke of sulfur trioxide. Place the crucible in a muffle furnace and burn it at 950C for 30min, take it out, cool it in a desiccator, weigh it, and repeat the burning until constant weight, and do a blank test at the same time.
6 Calculation of analytical results
The content (X) of silicon monoxide (SiO2) is calculated as follows: (m, - m,) -(m- m) × 100
Wherein: , - — the mass of the precipitate and the platinum crucible before hydrofluoric acid treatment, B; - — the mass of the precipitate and the platinum crucible after hydrofluoric acid treatment, B; the mass of the precipitate and the platinum crucible of the blank test before hydrofluoric acid treatment, L; the mass of the precipitate and the platinum crucible of the blank test after hydrofluoric acid treatment, M; the mass of the sample, m.
7 Allowable difference
The difference in the results of the measurements within the same laboratory should be less than the value shown in the following table. Chemical
15.00~25.00
25.00~35.00
Additional remarks:
( Sto,)
This standard is attributed to the Chemical Industry and Mining Design Institute of the Ministry of Chemical Industry. This standard was drafted by the Chemical Industry and Mining Design Institute of the Ministry of Chemical Industry. The main drafters of this standard are Tu Heban and Zi Lihua.
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