GB/T 14949.1-1994 Chemical analysis methods for manganese ores - Determination of chromium content
Some standard content:
National Standard of the People's Republic of China
Chemical analysis method of manganese ore
Determination of chromium content
Manganese ores--Determination of chromium contentThis standard is equivalent to IS) 619-1981 "Manganese ore--Determination of chromium content-Determination method".
GB/T 14949. 1--. 94Www.bzxZ.net
Diphenylcarbohydrazide photometric method and silver persulfate drop diphenylcarbohydrazide photometric method
Part I
1 Subject content and scope of application
This standard specifies the determination of chromium content by diphenylcarbohydrazide photometric method. This standard is applicable to the determination of chromium content in manganese ore. Determination range: ≤0.100%. 2 Method Summary
The sample is melted with anhydrous sodium carbonate and sodium peroxide, and the melt is taken with water. In the sulfuric acid medium, hexavalent chromium ions react with "phenylcarbonyl fat to form a purple-red complex, and its absorbance is measured at a wavelength of 540nm on a spectrophotometer. When the vanadium content exceeds (.1%), it interferes with the determination, which can be eliminated by extracting vanadium 8-hydroxyquinoline salt with dichloromethane. 3 Reagents
3.1 Mixed flux: anhydrous sodium carbonate and sodium peroxide (1+1). Prepare when needed. 3.2 Anhydrous ethanol,
3.3 Chloroform.
3.4 Sulfuric acid c(1/2H,S0,)=6 mol/L. 3.5 Sulfuric acid.c (1/2H, SO,) 2mol/L
3.6 Ammonium persulfate solution (250g/L). Prepare when using. 3.7 Diphenylcarbazide solution (1g/l): weigh 0.1g diphenylcarbazide and dissolve it in 10ml acetic acid solution (80%m/m). Dilute it with water to 100ml and mix well. Prepare when using 3.8 8-hydroxyquinoline solution (25g/L): weigh 2.5g 8-hydroxyquinoline and dissolve it in acetic acid solution [c (CH.COH) = 2mol/I.1+, and dilute it with this acetic acid solution to 100ml, mix well. 3.9 Silver sulfate solution (2.5 g/L).
3.10 Standard solution: Weigh (2828 g) potassium dichromate (basic reagent) which has been dried to constant weight at 180-200°C and cooled to room temperature in a desiccator, put it in a 250 ml beaker, dissolve it in water, transfer it to a 1000 ml volumetric flask, and dilute it to the mark with water. Mix: 1 ml of this solution equals 100 chromium.
3.11 Formaldehyde orange solution (1 g/L).
Approved by the State Administration of Technical Supervision on January 18, 1994 2
Implemented on October 1, 1994| |tt||4 Instruments and equipment
Common laboratory instruments and equipment and
4.1 Corundum crucible.
GB/T14949.1-94
4.2 Muffle furnace: The temperature can be controlled at 650-750℃4.3 Spectrophotometer: There is a near-ultraviolet and visible spectrophotometer. 5 Sample
The sample should pass through a (.100mm sieve) and be placed under wind in laboratory conditions. 6 Analysis steps
6.1 Sample quantity
Weigh about 1g of sample, accurate to 0.0001g. Weigh the sample at the same time as the determination of wet water content Mass percentage (A). When calculating the chromium content, the result (mass percentage) should be multiplied by the conversion factor (K), which is the mass percentage of the chromium content measured in the completely dried sample. Conversion factor (K) = 100A
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, cover with a small amount of mixed flux (3.1). Place in a muffle furnace (4.2) at about 700℃ and melt for 15 to 20 minutes. 6.3.2 After the melt is cooled, place it in a 400ml beaker pre-filled with 150 to 200mL of near-boiling water, heat it and take it out, remove the beaker, cool it slightly, wash the corundum crucible with water and take it out. Heat the solution to boiling, boil for 15-20 minutes, add anhydrous ethanol (3.2) dropwise until the green color disappears and continue boiling for 1-2 minutes. After the solution cools, transfer it together with its precipitate into a 250ml volumetric flask, dilute to the mark with water, stir, let stand to allow the precipitate to settle, and dry filter the solution into a 250ml beaker. 6.3.3 Transfer 10.00ml of the filtrate into a 100ml beaker, add 2-3 drops of methyl orange solution (3.11) and mix with sulfuric acid (3.5) until the yellow changes to orange-red, and mix for 2 minutes. 6.3.4 When the vanadium content is greater than 0.1%, transfer 10.00 mL of the filtrate to a 100 mL separatory funnel, neutralize according to 6.3.3, add 0.2~0.3 mL of 8-hydroxyquinoline (3.8) and 3~5 mL of chloroform (3.3), shake vigorously for 1~2 min, let stand for 23 min, drain and discard the trichloromethane layer. Repeat the extraction with chloroform (3.3) 2~3 times to ensure that the 8-hydroxyquinoline salt of vanadium is completely extracted. Filter the extracted chromium-containing solution into a 100 mL beaker, wash with warm water 5~6 times, and proceed as in 6.3.5. 6.3.5 Add 2 ml of sulfuric acid (3.4) and 4 ml of silver sulfate solution (3.9), boil, add 2 ml of ammonium persulfate solution (3.6) to the boiling liquid, and continue to boil for 10 min. After the solution is cooled, transfer it to a 50mL volumetric flask and add 5mL of phenylcarbohydrazide solution (3.7). Mix well for 20-30 seconds, dilute with water to the mark, and mix again. 6.3.6 Transfer part of the solution (6.3.5) to an absorption dish (if the chromium content of the sample is not more than 0.03%, use 3cm absorption dish; if the chromium content is more than 0.03%, use 1cm absorption dish). Take water as reference and measure its absorbance at a wavelength of 540nm on a spectrophotometer (photometric measurement should be carried out between 10 and 15 minutes). Subtract the absorbance of the blank made with the sample and find the corresponding chromium content from the working curve. 6.4 Drawing of working curve
When the sample content is not more than 0.03%, take 0.0.50, 1.00, 2.00, 3.00mL of chromium standard solution (3.10); when the chromium content is 10.03%, take 0, 3.00.5.00, 7.00, 10.00mL of chromium standard solution (3.10), put it into a corundum crucible, and evaporate it at low temperature. The rest is carried out according to 6.3.1 to 6.3.6. With the amount of chromium as the abscissa and the absorbance after subtracting the blank of the working curve as the ordinate, draw 1. Draw the line:
Calculation of results
The mass percentage of chromium is calculated as follows:
GB/T14949.1--94
Cr(%)=m ×10 × K
-The amount of chromium found from the working curve, g; In the formula; m, ---
-The mass of the sample, g,
K--The conversion factor of the mass percentage of chromium in the completely dried sample. 8 Allowable difference
The difference in the analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table 1
<0:005 0
>0. 005 0~ 0. 010 0
>0. 010 0~0. 050 0
>0. 050 0~0. 100
Part II
9 Subject content and scope of application
This standard specifies the determination of chromium content by silver persulfate titration. Silver persulfate titration
This standard is applicable to the determination of chromium content in manganese ore. Determination range:>0.10%. 10 Method summary
Tolerance
The sample is melted with sodium carbonate and sodium peroxide, and the melt is leached with water. In an acidic medium, in the presence of catalyst silver nitrate, low-valent chromium ions are oxidized to chromate ions by ammonium persulfate. Use ammonium ferrous sulfate to reduce chromate ions, and titrate the excess ammonium ferrous sulfate with potassium permanganate standard solution. 11 Reagents
11.1 Mixed flux: anhydrous sodium carbonate and sodium peroxide (1+1), prepare when needed. Anhydrous ethanol.
Phosphoric acid (pl.70g/ml.).
Sulfuric acid (1+1).
Ammonium persulfate solution (250g/L), prepare when needed. 11.5
Sodium chloride solution (50g/L).
Ammonium ferrous sulfate solution (12g/L): Dissolve 12g ammonium ferrous sulfate (CNH), Fe(SO.)2·6HO) in 1L sulfuric acid (5+95) silver nitrate solution (2.5g/L).
Standard potassium permanganate solution, c (1/5KMnO.) = 0.03mol/L. 11.9.1
Preparation of solution
GB/T 14949.1-94
Add 0.Dissolve 95g potassium permanganate in 1L water and mix well. Leave the solution for 6 days. If manganese dioxide precipitates, do not stir. Filter into a brown glass bottle by siphoning or through a layer of glass wool and burned asbestos. Leave for 2 to 3 days before calibration. Store the solution in a cool place and prevent dust and various gases from penetrating. 11.9.2 Calibration of solution
Weigh about 0.05g of anhydrous sodium oxalate (reference reagent) dried to a constant amount at 110~120℃, accurate to 0.0001g, cover it in a 250ml conical flask, add 100mL sulfuric acid (1+9), heat the solution to 7080℃, and after the salts are dissolved, titrate with potassium permanganate solution (11.9.1) while hot until a light red color appears and stabilizes for 1min. Take a portion of anhydrous sodium oxalate for calibration. The extreme difference of the number of liters of potassium permanganate standard solution (11.9.1) consumed shall not exceed 0.10 mL, and the average value shall be taken. The titration degree T of potassium permanganate standard solution (11.9) on chromium shall be calculated according to formula (1): T = m × 0. 258 7
Wherein: T.--1ml. The amount of chromium equivalent to potassium permanganate standard solution, gm1-the mass of anhydrous sodium oxalate?g
V,---the volume of potassium permanganate standard solution (11.9.1) consumed during titration, mL; 0.2587-the factor converted to chromium amount when potassium permanganate standard solution titrates anhydrous sodium oxalate. 11.10 Methyl orange solution (1g/L).
12 Instruments and equipment
12.1 Common laboratory instruments and equipment
12.2 Corundum crucible.
12.3 Muffle furnace: The temperature can be controlled at 650～750℃. 13 Sample
The sample should pass through a 0.100mm sieve and be air-dried under laboratory conditions. 14 Analysis steps
14.1 Sample quantity
Weigh about 1g of sample, accurate to 0.0001g. +(1)
Weigh the sample at the same time as the measurement to determine the mass percentage of wet water (A). When calculating the chromium content, the result (mass percentage) should be multiplied by the conversion factor (K), which is the mass percentage of chromium measured in the completely dry sample. Conversion factor (K)=
100-A
14.2 Blank test
Perform a blank test along with the sample.
14.3 Determination
14.3.1 Place the sample (14.1) in the corundum (12.2), add about 8g of mixed flux (11.1), mix well, cover with a little mixed flux (11.1) and place in a muffle furnace (12.3) at about 700℃, and melt for 15 to 20 minutes. 14.3.2 After the melt is cooled, place it in a 400mL beaker pre-filled with about 200ml of near-boiling water, heat and pour, remove the beaker, cool it slightly, wash the corundum with water and take it out, heat the solution to boiling, boil for 15 to 20 minutes, add anhydrous ethanol (11.2) drop by drop until the green color disappears and continue to boil for 1 to 2 minutes. After cooling, transfer it to a 500mL volumetric flask together with the precipitate, dilute with water to the mark, and stir to let the precipitate settle. Dry filter the solution into a 400mL beaker. 14.3.3 Transfer 250 mL of the filtrate (14.3.2) to a 500 mL conical flask, heat and boil for 15 to 20 min, remove the flask, add 2 to 3 drops of methyl orange solution (11.10), neutralize with sulfuric acid (11.4) until the solution changes color. Add 10 mL of sulfuric acid (11.4) and 10 mL of phosphoric acid (11.3), and heat to boiling. Add 10 ml of silver nitrate solution (11.8) and 30 ml of ammonium persulfate solution (11.5), boil for 8-10 min, remove, cool slightly, slowly add 5 ml of sodium chloride solution (11.6). Continue boiling for about 15 min, cool the solution to 10-25 °C, add 15.00 ml of ammonium ferrous sulfate solution (11.7) with a burette, mix thoroughly, and titrate the excess ammonium ferrous sulfate with potassium permanganate standard solution (11.9) until a light red color appears. Keep for about 1min light red color does not fade. At the same time as the sample is measured, determine the ratio of ammonium ferrous sulfate solution to potassium permanganate standard solution (11.9). Measure 250ml of water and place them in 500ml conical flasks respectively. Proceed as per 14.3.3. The number of milliliters of potassium permanganate standard solution consumed by one solution shall not exceed 0.05ml. Take the average value.
15 Calculation of results
The mass convex fraction of chromium is calculated according to formula (2):
TE(V,- V) -(VV)J× 100 × KCr(%) -
Formula: T
-1mL of permanganate standard solution equivalent to the amount of chromium, g; V—the volume of potassium permanganate standard solution equivalent to the ammonium ferrous sulfate solution added to the test solution, mI.V. The volume of potassium permanganate standard solution consumed by titrating the excess ammonium ferrous sulfate solution, mL; V.--the volume of potassium permanganate standard solution consumed by titrating the excess ammonium ferrous sulfate solution during the test, ml.m
The mass of the test material·g:
K—conversion factor converted to the mass percentage of chromium in the completely dried sample 16 Allowable difference
The difference in analysis results between laboratories should not be less than the allowable difference listed in Table 2. Table 2
>0. 10~0. 20
>0.20~0.50
Additional remarks:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. The tolerance is
In this standard, the Mineral Geology Research Institute of China Nonferrous Metals Industry Corporation and Changsha Mining and Metallurgical Research Institute of Metallurgical Industry are responsible for drafting. This standard is drafted by Xinyu Iron and Steel Plant.
The main drafters of this standard are Xia Youwen, Zhang Shuiju, Zhou Juhan, Wan Jiebao, He Sha, and Xie Guozheng. S2) Continue boiling for 1 to 2 minutes until the green color disappears. After cooling, transfer the precipitate to a 500 mL volumetric flask, dilute to the mark with water, and stir to allow the precipitate to settle. Dry filter the solution into a 400 mL beaker. 14.3.3 Transfer 250 mL of the filtrate (14.3.2) to a 500 mL conical flask, heat and boil for 15 to 20 minutes, remove the flask, add 2 to 3 drops of methyl orange solution (11.10), and neutralize with sulfuric acid (11.4) until the color of the solution changes. Add 10 mL of sulfuric acid (11.4) and 10 mL of phosphoric acid (11.3), and heat to boiling. Add 10 ml of silver nitrate solution (11.8) and 30 ml of ammonium persulfate solution (11.5), boil for 8-10 min, remove, cool slightly, slowly add 5 ml of sodium chloride solution (11.6). Continue boiling for about 15 min, cool the solution to 10-25 °C, add 15.00 ml of ammonium ferrous sulfate solution (11.7) with a burette, mix thoroughly, and titrate the excess ammonium ferrous sulfate with potassium permanganate standard solution (11.9) until a light red color appears. Keep for about 1min light red color does not fade. At the same time as the sample is measured, determine the ratio of ammonium ferrous sulfate solution to potassium permanganate standard solution (11.9). Measure 250ml of water and place them in 500ml conical flasks respectively. Proceed as per 14.3.3. The number of milliliters of potassium permanganate standard solution consumed by one solution shall not exceed 0.05ml. Take the average value.
15 Calculation of results
The mass convex fraction of chromium is calculated according to formula (2):
TE(V,- V) -(VV)J× 100 × KCr(%) -
Formula: T
-1mL of permanganate standard solution equivalent to the amount of chromium, g; V—the volume of potassium permanganate standard solution equivalent to the ammonium ferrous sulfate solution added to the test solution, mI.V. The volume of potassium permanganate standard solution consumed by titrating the excess ammonium ferrous sulfate solution, mL; V.--the volume of potassium permanganate standard solution consumed by titrating the excess ammonium ferrous sulfate solution during the test, ml.m
The mass of the test material·g:
K—conversion factor converted to the mass percentage of chromium in the completely dried sample 16 Allowable difference
The difference in analysis results between laboratories should not be less than the allowable difference listed in Table 2. Table 2
>0. 10~0. 20
>0.20~0.50
Additional remarks:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. The tolerance is
In this standard, the Mineral Geology Research Institute of China Nonferrous Metals Industry Corporation and Changsha Mining and Metallurgical Research Institute of Metallurgical Industry are responsible for drafting. This standard is drafted by Xinyu Iron and Steel Plant.
The main drafters of this standard are Xia Youwen, Zhang Shuiju, Zhou Juhan, Wan Jiebao, He Sha, and Xie Guozheng. S2) Continue boiling for 1 to 2 minutes until the green color disappears. After cooling, transfer the precipitate to a 500 mL volumetric flask, dilute to the mark with water, and stir to allow the precipitate to settle. Dry filter the solution into a 400 mL beaker. 14.3.3 Transfer 250 mL of the filtrate (14.3.2) to a 500 mL conical flask, heat and boil for 15 to 20 minutes, remove the flask, add 2 to 3 drops of methyl orange solution (11.10), and neutralize with sulfuric acid (11.4) until the color of the solution changes. Add 10 mL of sulfuric acid (11.4) and 10 mL of phosphoric acid (11.3), and heat to boiling. Add 10 ml of silver nitrate solution (11.8) and 30 ml of ammonium persulfate solution (11.5), boil for 8-10 min, remove, cool slightly, slowly add 5 ml of sodium chloride solution (11.6). Continue boiling for about 15 min, cool the solution to 10-25 °C, add 15.00 ml of ammonium ferrous sulfate solution (11.7) with a burette, mix thoroughly, and titrate the excess ammonium ferrous sulfate with potassium permanganate standard solution (11.9) until a light red color appears. Keep for about 1min light red color does not fade. At the same time as the sample is measured, determine the ratio of ammonium ferrous sulfate solution to potassium permanganate standard solution (11.9). Measure 250ml of water and place them in 500ml conical flasks respectively. Proceed as per 14.3.3. The number of milliliters of potassium permanganate standard solution consumed by one solution shall not exceed 0.05ml. Take the average value.
15 Calculation of results
The mass convex fraction of chromium is calculated according to formula (2):
TE(V,- V) -(VV)J× 100 × KCr(%) -
Formula: T
-1mL of permanganate standard solution equivalent to the amount of chromium, g; V—the volume of potassium permanganate standard solution equivalent to the ammonium ferrous sulfate solution added to the test solution, mI.V. The volume of potassium permanganate standard solution consumed by titrating the excess ammonium ferrous sulfate solution, mL; V.--the volume of potassium permanganate standard solution consumed by titrating the excess ammonium ferrous sulfate solution during the test, ml.m
The mass of the test material·g:
K—conversion factor converted to the mass percentage of chromium in the completely dried sample 16 Allowable difference
The difference in analysis results between laboratories should not be less than the allowable difference listed in Table 2. Table 2
>0. 10~0. 20
>0.20~0.50
Additional remarks:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. The tolerance is
In this standard, the Mineral Geology Research Institute of China Nonferrous Metals Industry Corporation and Changsha Mining and Metallurgical Research Institute of Metallurgical Industry are responsible for drafting. This standard is drafted by Xinyu Iron and Steel Plant.
The main drafters of this standard are Xia Youwen, Zhang Shuiju, Zhou Juhan, Wan Jiebao, He Sha, and Xie Guozheng. S
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