GB/T 1508-2002Manganese Ores - Determination of Total Iron Content - Potassium Dichromate Titrimetric Method and 1,10-Phenanthroline Spectrophotometric Method (English PDF)

3.1 Principle

The sample shall be decomposed by hydrochloric acid; the residue slag shall be

melted by potassium pyrosulfate. After leaching, the iron was precipitated and

separated by ammonia water; use the hydrochloric acid to dissolve the precipitate.

3.2 Reagents and materials

Unless otherwise specified, only the reagents that are determined to be analytically

pure and distilled water or water with equivalent purity shall be used in the analysis.

3.2.1 Potassium pyrosulfate.

3.2.2 Sodium fluoride.

3.2.9 Hydrochloric acid (1+4).

3.2.10 Hydrochloric acid (1+50).

3.2.11 Sulfuric acid (1+1).

3.2.12 Phosphoric acid (1+1).

3.2.13 Sulfur-phosphorus mixed acid. slowly add 150mL of sulfuric acid (rho1.84g/mL)

into 500mL of water; after cooling off, add 150mL of phosphoric acid (3.2.5); use water

to dilute to 1000mL; mix evenly.

3.2.14 Ammonia water (1+50).

3.2.15 Hydrogen peroxide (volume fraction of 30%).

3.2.20 Neutral red indicator solution (1g/L).

3.2.21 Sodium diphenylamine sulfonate indicator solution (2g/L).

3.3 Instrument

The general laboratory instruments are used for analysis.

3.4 Sampling and sample preparation

The sampling and sample preparation shall be carried out as per the provisions of

GB/T 2011; the specimen shall pass through a 0.080mm sieve.

3.5 Analytical procedures

3.5.1 Sample mass

Take the air-dried sample according to Table 1, accurate to 0.0001g.

Meanwhile, take the air-dried sample according to the wet storage water content

measured by GB/T 14949.8-1994.

3.5.2 Blank test

Pipette 10.00mL of iron standard solution (3.2.19); perform the blank test together with

the sample.

3.5.3 Determination

3.7 Tolerance

The difference in analysis results between laboratories shall be no more than the

tolerance in Table 2.

3.8 Test report

The test report shall include the following contents.

4.1 Principle

The sample is decomposed by hydrochloric acid; the remaining slag is melted by

potassium pyrosulfate. Use hydroxylamine hydrochloride to reduce the ferric iron into

ferrous iron. At the acidity of pH 4~5, the ferrous iron and 1,10-phenanthroline forms a

red complex; then measure the absorbance at the wavelength of 510nm; calculate the

total iron content.

4.2 Reagents and materials

Unless otherwise specified, the reagents determined to be analytically pure and

distilled water or water with equivalent purity shall be used in the analysis.

4.3 Instrument

The general laboratory instruments are used for analysis.

4.4 Sampling and sample preparation

The sampling and sample preparation shall be carried out as per the provisions of

GB/T 2011; the specimen shall pass through a 0.080mm sieve.

4.5 Analytical procedures

4.5.1 Sample mass

Take the air-dried sample according to Table 3, accurate to 0.0001g.

Meanwhile, take the air-dried sample according to the wet storage water content

measured by GB/T 14949.8-1994.

4.5.2 Blank test

The blank test shall be performed together with sample.

4.5.3 Determination

4.5.3.1 Place the sample (4.5.1) into 300mL beaker; moisten it with water. Add 30mL

of hydrochloric acid (4.2.3); cover the stopper; heat slightly to dissolve; use warm water

to dilute to about 50mL. Filter by the medium-speed filter paper with a small amount of

pulp; use hot hydrochloric acid (4.2.4) and hot water to wash the precipitate for 4~5

times, respectively. Collect the filtrate and washings into 300mL beaker; reserve as the

main solution.

4.5.3.3 Separately-take test solution into 100mL volumetric flask according to Table 3;

add 50mL of water; add 5mL of hydroxylamine hydrochloride solution (4.2.6), mix

evenly. Stand for 5min; add 10mL of acetic acid-sodium acetate buffer solution (4.2.8),

10mL of 1,10-phenanthroline solution (4.2.7); stand for 1h at the room temperature or

in the 30°C water bath for 15min; cool off; dilute with water to the scale, mix evenly.

Measure the absorbance at the wavelength of 510nm by 1cm absorber with water as

reference on the spectrophotometer. After deducting the absorbance measured in the

blank test (4.5.2); find out the iron content form the calibration curve.

4.7 Tolerance

The difference in analysis results between laboratories shall be no more than the

tolerance in Table 4.

4.8 Test report

The test report shall include the following contents.

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