1 , the decomposition of the sample
1) acid decomposition [vanadium content of less than 0.05% (m / m), Mo and Cu content of less than 0.1% (m / m) sample]
Weigh 0.2000g sample in a 300mL beaker, add 30mL of hydrochloric acid, cover the watch glass , slowly heating the sample decomposition, can not boil, so as not to volatilize ferric chloride. Rinse the watch glass and beaker wall with shot water to a volume of approximately 50 mL . The insoluble residue is filtered with medium-speed filter paper, and the residue is washed with hot hydrochloric acid (1+50) until no yellow ferric chloride is visible, and then washed with hot water for 6 to 8 times. The filtrate and washings were collected in a 600 mL beaker. This was the main solution.
The filter paper and the residue were placed in platinum crucibles, ashed, burned at 800° C. for 20 minutes , and cooled. The residue was wetted with sulfuric acid (1+1) , 5 mL of hydrofluoric acid was added , and the sulfur trioxide was heated at low temperature to remove silica and sulfuric acid. Remove, add 2g of potassium pyrophosphate in the cooled crucible, slowly heated to about 650 °C and melt for about 5min , cooling. The crucible was placed in the original beaker, about 25 mL of water and 5 mL of hydrochloric acid were added, and the melt was warmed and dissolved. The crucible was washed out and the solution was incorporated into the main liquid. Evaporate to about 100 mL without boiling .
Note: After the sample is decomposed by hydrochloric acid, if there is a small amount of white slag, no slag can be returned, which has no significant effect on the result .
2) Melt - acidification [ Specimen with vanadium content less than 0.05% (m/m) , molybdenum and copper content less than 0.1% (m/m) ]
Weigh 0.2000g sample in corundum, add 3g mixed flux ( sodium peroxide + sodium carbonate = 2 + 1) , mix well, cover 1 g of mixed flux, melt at 800 °C for about 15min .
The melt was cooled, the crucible was placed in a 600 mL beaker, 100 mL of warm water was added , and heated and boiled for several minutes to dip the melt. Add 20 mL of hydrochloric acid and heat until the decomposition of sodium carbonate and sodium peroxide is no longer foaming. Wash the crucible and add the wash solution to the solution. Evaporate to about 100 mL without boiling .
3) melt - Filter [vanadium content greater than 0.05% (m / m), a molybdenum content greater than 0.1% (m / m), the copper content is less than 0.1% (m / m) sample]
Weigh 0.2000 g of sample in corundum, add 3 g of flux ( sodium peroxide + sodium carbonate = 2 + 1) , mix well, and cover 1 g of flux. Melted at 800 °C for about 15 min .
The melt was cooled, the crucible was placed in a 600 mL beaker, 100 mL of warm water was added , and heated and boiled for several minutes to dip the melt. Wash the crucible with hot water and add the wash solution to the solution. Keep it. The solution was cooled, filtered through filter paper using medium speed, with sodium hydroxide solution (20g / L) was washed twice, and the filtrate was discarded.
The precipitate on the filter paper was washed with water into the original beaker, 10 mL of hydrochloric acid was added , and the precipitate was heated and dissolved. Original solution was filtered with filter paper, the filter paper washed with hot hydrochloric acid (1 + 1) 3 times, washed several times with hydrochloric acid (1 + 50), and finally with warm water until the washings were acid-free so far. The filtrate and washings were collected in a 600 mL beaker. This was the main solution. The remaining melt in the crucible was dissolved with hot hydrochloric acid (1+1) and washed into the main liquid. Evaporate to about 100 mL without boiling .
Nanjing Ningbo Analysis Instrument Co., Ltd.
2016.06.29
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