GB/T 5687.1-1985 Chemical analysis methods for ferrochromium - Ammonium persulfate oxidation volumetric method for determination of chromium content

This standard is applicable to the determination of chromium content in ferrochrome and ferronitride. Determination range: 45.00~80.00%. This standard complies with GB 1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". This standard is equivalent to Japan: Industrial Standard JIS G 1313/1978 "Analysis Method for Ferrochrome". GB/T 5687.1-1985 Chemical Analysis Method for Ferrochrome Determination of Chromium Content by Ammonium Persulfate Oxidation Capacitance Method GB/T5687.1-1985 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of ferrochromiumThe ammonium persulfate oxidation volumetricmethod for the determination of chromium contentThis standard is applicable to the determination of chromium content in ferrochromium and nitrided ferrochromium. Determination range: 45.00～80.00%. This standard complies with GB1467--78 "General Principles and General Provisions for Standards of Chemical Analysis Methods for Metallurgical Products". This standard is equivalent to the Japanese industry standard JISG1313/1978 "Analysis Methods for Ferrochromium". 1 Method Summary
UDC 669.15' 26
：543.24
GB 5687.1—85
After the sample is decomposed with phosphoric acid or alkali fused (acid-insoluble sample), sulfuric acid is added, chromium is oxidized with ammonium persulfate, permanganate is decomposed with hydrochloric acid and manganese sulfate, chromium is reduced with excess ammonium ferrous sulfate standard solution, and back titration is performed with potassium permanganate standard solution. 2 Reagents
2.1 Sodium peroxide.
2.2 Ammonium persulfate.
2.3 Nitric acid (1.42g/ml).
Sulfuric acid (p1.84g/ml).
2.5 Sulfuric acid (1+1).
Sulfuric acid (1+4).
Phosphoric acid (p1.70g/ml).
Hydrochloric acid (1+3).
Potassium permanganate solution (0.3%).
Silver nitrate solution (0.5%).
Manganese sulfate solution: weigh 100g manganese sulfate (MnSO·HzO), dissolve it in water and dilute to 1L, mix well. Ammonium persulfate solution (20%): prepare when used. Sodium diphenylamine sulfonate solution (0.1%).
2.14 Potassium permanganate standard solution [C (1/5KMnO.) = 0.1mol/L)). 2.14.1 Preparation
Weigh 3.3g potassium permanganate, add it to a flask containing about 1050ml of water, heat to a slight boil, keep it for 1 to 2 hours, place it in a dark place overnight, filter the upper clear liquid with a porous glass filter (do not wash it with water before and after filtering), transfer it to a brown bottle washed with steam for 30 minutes, mix well and store it in a dark place.
2.14.2 Calibration
Weigh 2.0000g sodium oxalate standard reagent dried at 150-200℃F for 1-1.5h, dissolve it in water, transfer it into a 250ml volumetric flask, dilute to scale, and mix. Transfer 25.00ml of this solution, add 200ml water and 10m sulfuric acid (2.4), heat the solution slightly to 25-30℃, titrate with potassium permanganate standard solution (2.14) while stirring until it turns slightly red, let it stand until the red color disappears, heat it to 55-60℃, and titrate with potassium permanganate standard solution (add it drop by drop 0.5-1㎡1 before the end point, and add the next drop after the previous drop fades) until the solution turns slightly red, and the end point is when it does not fade for 30s. Issued by the National Bureau of Standards on December 4, 1985
Implementation on October 1, 1986
GB5687.1-85
In addition, slowly add 10 ml of sulfuric acid (2.4) to 200 ml of water, heat to 55-60°C, and titrate with potassium permanganate solution as a blank test for correction.
Calculate the concentration of potassium permanganate standard solution according to the following formula: m × 25
C, =V,x 0.06701 × 250
Wherein: C,——concentration of potassium permanganate standard solution (2.14) after calibration, mol/L; —the amount of sodium oxalate weighed, g;
V,-—volume of potassium permanganate standard solution consumed after correction by empty test, ml, 0.06701
1.00ml potassium permanganate standard solution C (1/5KMnOg) = 1.000mol/L is equivalent to the amount of sodium oxalate, g. 2.15 Ammonium ferrous sulfate standard solution C [NH.) 2Fe (SO) 2.6HzO) = 0.1mol/L2.15.1 Preparation
In a beaker 1 containing 300ml of water, add 30ml of sulfuric acid (2.4), cool it down, add 40g of ammonium ferrous sulfate ((NH.) 2Fe (SO) 2·6HzO], and add about 700ml of water after it is completely dissolved, and mix well.2.15.2 Calibration
Take 25.00ml of ammonium ferrous sulfate standard solution (2.15.1), add 25ml of water and 5ml of phosphoric acid (2.7), and titrate with potassium permanganate standard solution (2.14) until it turns slightly red. Calculate the concentration of the ammonium ferrous sulfate standard solution according to the following formula: C2|| tt||Wherein: C2-
--concentration of ammonium ferrous sulfate standard solution (2.15), mal/L; C,--concentration of potassium permanganate standard solution (2.14) after calibration, mol/L; V--volume of potassium permanganate standard solution consumed during titration, ml; V--volume of ammonium ferrous sulfate standard solution transferred, ml. 3 Sample
3.1 High carbon ferrochrome sample should pass through 0.125mm sieve hole. 3.2 Nitride ferrochrome sample should pass through 0.088mm sieve hole. 3.3 Micro-carbon, low-carbon, 1 carbon samples (drilling samples) should pass through 1.68mm sieve hole. 4 Analysis steps
4.1 Sample quantity
Weigh 0.5000g sample.
4. 2 Determination
4.2.1 Acid dissolution method of sample
4.2.1.1 Place the sample (4.1) in a 300ml beaker, add 20ml phosphoric acid (2.7), cover with surface III, heat until the sample is completely dissolved and slightly smokes, remove it, and when it is slightly cool but the solution still maintains fluidity, immediately add 20ml sulfuric acid (2.6) and 5ml nitric acid (2.3), boil for about 1 minute to drive away nitrogen oxides. 4.2.1.2 After cooling, transfer to a 250ml volumetric flask, dilute to full scale with water, and mix. Transfer 50.00ml of the solution to a 500ml beaker, add 20ml sulfuric acid (2.5), and dilute to about 200ml with warm water. 4.2.1.3 .5ml potassium permanganate solution (2.9), then add 10ml silver nitrate solution (2.10) ~ 20 ~ 25ml ammonium persulfate solution (2.12), heat to boiling point to oxidize chromium into dichromic acid, wait for the solution to show the reddish color of permanganate, and then boil for 5 minutes to decompose the excess ammonium persulfate, add 5ml hydrochloric acid (2.8) and 5ml manganese sulfate solution (2.11), boil until the permanganate is completely decomposed, and continue to boil for 2 ~ 3 minutes. If there is still the color of permanganate or the precipitation of manganese dioxide, add 2 ~ 3ml hydrochloric acid (2.8), continue to heat and boil until the permanganate is completely dissolved and the precipitation of manganese dioxide disappears completely. Cool to room temperature and add water to keep the solution volume about 250ml.322
GB 5687.1—85
4.2.1.4 Titrate with ammonium ferrous sulfate standard solution (2.15) until dichromic acid is reduced, and add 5-10 ml excess, then immediately titrate with potassium permanganate standard solution (2.14) until the solution turns purple, which is the end point. Note: If the end point is unclear, add 2-3 drops of sodium aniline sulfonate solution (2.13), and titrate with potassium permanganate standard solution until the solution turns purple, which is the end point. .4.2.2 Alkali fusion method of sampleWww.bzxZ.net
4.2.2.1 Place the sample (4.1) in a 30 ml nickel crucible (or high alumina), add 10 g of sodium peroxide (2.1), stir carefully to mix, and then cover with 1 g of sodium peroxide (2.1), slowly heat to melt the sample, keep it at about 700℃ for about 5 minutes, and shake it continuously to melt it.
4.2.2.2 After cooling, place the crucible in a 500ml beaker, add about 100ml hot water, let the melt leach out, then take out the crucible, wash with water, add 60ml sulfuric acid (2.5) after the solution cools, and boil for about 10 minutes. 4.2.2.3 After cooling, transfer to a 250ml volumetric flask, dilute to the mark with water, and mix well. Transfer 50.00ml of the solution to a 500ml beaker, add 5ml phosphoric acid (2.7) and 20ml sulfuric acid (2.5), dilute to about 200ml with warm water, and proceed as per 4.2.1.3 and 4.2.1.4. 5 Calculation of analysis results
Calculate the percentage of chromium by the following formula:
Cr (%) --Cz(V+-V,. k) ×0.01733.mo×r
Wherein: C2-
Standardized ammonium ferrous sulfate standard solution (2.15) concentration, mol/L, volume of ammonium ferrous sulfate standard solution (2.15) consumed during titration, ml; V2--volume of potassium permanganate standard solution (2.14) consumed during titration, ml; k
-volume ratio of potassium permanganate standard solution to ammonium ferrous sulfate standard solution, sample volume, g,
split ratio of test solution;
6 allowable difference
-1.00ml ammonium ferrous sulfate standard solution C[(NH)2Fe(SO)2]=1.000mol,L is equivalent to the amount of chromium, g.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. %
Additional remarks:
This standard was proposed by the Ministry of Metallurgy of the People's Republic of China.
Allowable difference
This standard was drafted by Shanghai Ferroalloy Factory. From the month this standard is implemented, the former Metallurgical Industry Standard YB584-65 "Methods for Chemical Analysis of Ferrochromium" will be invalidated.
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