GB/T 32786-2016Pig iron contenting nickel—Determination of iron content—Dichromate titration method (English PDF)

1 Scope

This Standard specifies the potassium dichromate titration method for the determination of iron content.

This Standard applies to the determination of iron content in pig iron contenting nickel; the determination range (mass fraction): 65.00% ~ 90.00%.

2 Normative references

The following documents are indispensable for the application of this document.

For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 4010, Ferroalloys sampling and preparation of samples for chemical analysis

GB/T 6682, Water for analytical laboratory use - Specification and test methods

GB/T 12805, Laboratory glassware - Burettes

GB/T 12806, Laboratory glassware - One-mark volumetric flasks

GB/T 12808, Laboratory glassware - One mark pipettes

3 Principle

After the sample is decomposed by acid, the ammonia water precipitates iron.

In hydrochloric acid solution, use stannous chloride and titanium trichloride to reduce iron to divalent. In the presence of the sulfuric acid-phosphoric acid

4 Reagents

4.15 Potassium dichromate standard titration solution, c(K2Cr2O7) = 0.04 000 mol/L. Accurately weigh 1.961 2 g of potassium dichromate (reference) that has been dried at 105 °C ± 5 °C for 1 h and cooled to room temperature in a 500 mL beaker; add 100 mL of water. After the potassium dichromate is fully dissolved, transfer it to a 1 000 mL volumetric flask; use water to dilute to the mark; mix well.

4.16 Sodium diphenylamine sulfonate indicator solution, 5g/L.

5 Instruments

Ordinary laboratory instruments; burettes, one-mark volumetric flasks, and one mark pipettes shall meet the requirements of GB/T 12805, GB/T 12806 and GB/T 12808, respectively.

6 Sample taking

Laboratory samples for analysis shall be taken and prepared in accordance with GB/T 4010. The crushed and ground sample shall pass through the 0.125 mm sieve; the drilled sample shall pass through the 1.68 mm sieve.

7 Analysis steps