This standard specifies the determination of vanadium content by phosphotungstic acid photometry. This standard is applicable to the determination of vanadium content in dry manganese ore. Determination range: <0.05% GB/T 14949.4-1994 Chemical analysis method for manganese ore Determination of vanadium content GB/T14949.4-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of manganese ore
Determination of vanadium content
Manganese ores ---Determination of vanadium content1 Subject content and scope of application
This standard specifies the determination of vanadium content by phosphotungstovanadic acid photometry. This standard is applicable to the determination of vanadium content in manganese ore. Determination range: <0.05%. 2 Method summary
GB/T 14949.4
The sample is melted with sodium peroxide-sodium carbonate, leached with water, and dry filtered. After removing part of the filtrate for acidification and dehydration to remove silicon, in the hydrochloric acid medium: high-valent vanadium forms a soluble yellow complex with phosphoric acid and sodium tungstate. Measure its absorbance at a wavelength of 420130nm on a spectrophotometer. 3 Reagents
3.1 Mixed flux: anhydrous sodium carbonate and sodium peroxide (1+3). Prepare when used. 3.2 Hydrochloric acid (1+1).
3.3 Phosphoric acid (1+2).
3.4 ​​Potassium permanganate solution (10g/L).
3.5 Sodium nitrite solution (10g/1.).
3.6 Sodium tungstate (Na,WO,·2H,O) solution (10g/L). 3.7 Hydrogen peroxide solution (10g/L).
3.8 Vanadium standard solution
Weigh 0.2296g ammonium metavanadate (superior purity) and place it in a 250mL beaker, add 100ml sulfuric acid (1+1), heat to dissolve, and cool. Transfer to a 1000ml volumetric flask, cool, dilute to scale with water, and mix. This solution contains 100μg vanadium in 1ml, 3.9 Methyl orange solution (1 g/L).
4 Instruments and equipment
Common laboratory instruments and equipment and
4.1 Corundum crucible.
4.2 Muffle furnace: The temperature can be controlled at 700~~750℃. 4.3 Spectrophotometer with near-ultraviolet and visible spectrophotometer. 5 Sample
The sample should pass through a 0.100mm sieve and be air-dried under laboratory conditions. Approved by the State Bureau of Technical Supervision on January 18, 1994 and implemented on October 1, 1994
6 Analysis steps
6.1 Sample quantity
GB/T14949.4--94
Weigh the sample according to Table 1, accurate to 0.0001g. Table 1
Vanadium content, %
Sample quantity, g
Weigh the sample at the same time as the determination to determine the mass percentage of mixed water (A). When calculating the vanadium content, the result (mass percentage) should be multiplied by the conversion factor (K), which is the mass percentage of the vanadium content measured in the completely dry sample. 100
Conversion factor (K) =,
6.2 Blank test
Carry out a blank test with the sample.
6.3 Determination
6.3.1 Place the sample (6.1) in a corundum crucible (4.1), add about 8g of mixed flux (3.1), mix well, cover with about 2g, and bake at low temperature. Leave it in a 750℃ muffle furnace (4.2) to melt for about 10min. Take it out and cool it. Place it in a 250ml beaker pre-filled with 100mL boiling water. Heat it. After boiling, add ethanol dropwise until the green color disappears. Continue heating to boiling for 12min. Wash out the precipitate while it is hot. After cooling, transfer the solution together with the precipitate into a 250mL volumetric flask, dilute it to the scale with water, mix it, and let it stand to clarify. 6.3.2 Dry filtration, transfer 2 portions of 50.0 ml of the filtrate, place each portion in a 150 ml beaker, add 1 drop of methyl orange solution (3.9), neutralize with hydrochloric acid (3.2) until the solution turns red and has an excess of 5 ml, evaporate to dryness at low temperature, add 3 ml of hydrochloric acid (3.2) and about 15 ml of water, heat to boiling, filter with medium-speed quantitative filter paper, wash the filter paper and beaker with hot water 3 to 4 times each, and collect the filtrate and washing liquid in a 50 ml volumetric flask. 6.3.3 Cool. Add 0.5 mL of hydrogen peroxide solution (3.7) (when the hexavalent chromium in the color developing solution is greater than 1 mg, add 1 mL of hydrogen peroxide solution (3.7), add potassium permanganate solution (3.4) dropwise until the solution turns purple-red and stabilizes for 2~~3 minutes, then add sodium nitrite solution (3.5) dropwise until the purple-red color of the solution disappears completely and 1~2 drops are added in excess, add 2 mL of phosphoric acid (3.3), mix well, add 1 mL of sodium tungstate solution (3.6) to one portion, dilute to the scale with water, and mix well. 6.3.4 After 10 minutes, transfer the solution (6.3.3) into a 5 cm absorption dish, use the solution without sodium tungstate as the reference solution, and measure its absorbance at a wavelength of 420~430 nm on a spectrophotometer. Degree, minus the absorbance of the blank test solution (the solution without sodium tungstate is used as the reference solution), and then find the corresponding vanadium content from the working curve.
6.4 Drawing of working curve
Pipette 0, 1.00, 2.00, 3.00, 4.00, 6.00, 8.00mL of vanadium standard solution (3.8) into a corundum crucible (4.1) and evaporate to dryness at low temperature. After adding the test materials according to Table 1, measure according to 6.3, use the color developing solution of the test material without adding vanadium standard solution as the reference solution, measure its absorbance, and draw the working curve with the vanadium content as the horizontal axis and the absorbance as the vertical axis. 7
Calculation of results
The mass percentage of vanadium is calculated as follows:
V(%) =
Wherein: V-total volume of test solution, mL;
V,---volume of test solution taken, mL.;
m.--the amount of vanadium found from the working curve. g:
m--mass of the sample, g;
×100×K
GB/T14949.4-94
K--conversion factor of the amount of vanadium in a completely dry sample. 8 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2| |tt||>0.01~0.03bzxz.net
>0.030.05
Additional remarks:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. Allowable difference
This standard is drafted by the Mineral Geology Research Institute of China Nonferrous Metals Industry Corporation and the Changsha Research Institute of Mining and Metallurgy of the Ministry of Metallurgical Industry. This standard is drafted by the Changsha Research Institute of Mining and Metallurgy of the Ministry of Metallurgical Industry. The main drafters of this standard are Li Wenran, Li Jinchun, Wang Huipan, Chen Ziruo, Cao Shitiao, Zhang Jinian, Xia Youwen, and Zhang Shuiju.
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