SN/T 5253-2020Determination of aluminum content in ferrosilicon EDTA titration (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard was proposed and managed by the General Administration of Customs of the People's Republic of China.

Drafting organizations of this standard. Hohhot Customs of the People's Republic of China, Nanjing Customs of the People's Republic of China.

1 Scope

This standard specifies the analytical method for the determination of aluminum content in ferrosilicon by EDTA titration.

This standard applies to the determination of aluminum content in ferrosilicon. Measuring range. 0.1%-3.0%.

2 Normative references

The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article Pieces. For undated reference documents, the latest version (including all amendments) is applicable to this document.

GB/T4010 Collection and preparation of samples for chemical analysis of ferroalloys.

GB/T 6379.2 Accuracy of measurement methods and results (accuracy and precision) Part 2 Determine the repeatability and accuracy of standard measurement methods the basic method of reproducibility.

GB/T 6682 Analyze laboratory water specifications and test methods.

3 Method summary

The sample is dissolved with nitric acid and hydrofluoric acid, perchloric acid is added to evaporate to nearly dryness, and other metal ions are formed by adding a strong alkali solution.

Formed a precipitate and removed by filtration. Add excess EDTA to complex with aluminum ion, and back titrate the excess EDTA with copper sulfate. Add sodium fluoride Replace the EDTA complexed with aluminum ion in the same amount, then titrate and record with copper sulfate standard solution, and get the result from the volume of copper sulfate consumed Aluminum content.

4 Reagents

Unless otherwise specified, the reagents used are all analytically pure, and the water is the first grade water specified in GB/T 6682.

4.1 Perchloric acid (rho1.67 g/mL).

4.2 Nitric acid (rho1.42 g/mL).

4.3 Hydrofluoric acid (rho1.15 g/mL).

4.4 Sulfuric acid (1 1).

4.5 Hydrochloric acid (1 1).

4.6 Saturated sodium fluoride solution. add 300 mL of water to a 500 mL beaker with a graduated cylinder, then add sodium fluoride, and stir well with a plastic rod.

Until the solution is saturated, store in a plastic bottle and let stand overnight.

4.7 Sodium hydroxide solution (250 g/L). Weigh 250 g of sodium hydroxide, dissolve it with water and dilute to 1 L, and store it in a plastic bottle.

4.8 Acetic acid-sodium acetate buffer solution. Weigh 100 g of sodium acetate, first dissolve it with a small amount of water, and then add 4.6 mL of glacial acetic acid to mix.

Dilute with water to 500 mL and mix well.

4.9 Sodium hydroxide lotion (10 g/L). Weigh 10 g of sodium hydroxide to dissolve in water and dilute to 1 L, and store it in a plastic bottle.

4.10 EDTA solution (about 0.02 mol/L). Weigh 7.5 g of disodium edetate, dissolve in water and dilute to 1000 mL, and mix well.

4.11 Aluminum standard solution (0.2000 mg/mL). accurately weigh 0.2000 g aluminum powder (high-purity reagent, content >= 99.99%) into 250 mL in the beaker, add 20 mL of hydrochloric acid (4.5), heat at low temperature to completely dissolve, transfer to a 1000 mL volumetric flask, dilute to the mark with water, and shake well.

4.12 Phenolphthalein indicator (10 g/L ethanol solution).

4.13 PAN indicator (2 g/L ethanol solution).

5 Equipment

5.1 Analytical balance, with a sensitivity of 0.0001 g.

5.2 Analytical balance, with a sense of 0.01 g.

5.3 Adjustable electric heating plate. the highest temperature can reach 500°C.

5.4 Single-scale pipette, 10 mL.

5.5 Single-scale pipette, 20 mL.

6 Sample preparation

Take samples according to GB/T4010, and the samples should pass through 0.125 mm sieve.

7 Analysis steps

8 Result calculation

Calculate the aluminum content (mass fraction) in the sample according to formula (2), and the value is expressed in %.

c- The concentration of the copper sulfate standard solution, in moles per liter (mol/L);

V1- The volume of the copper sulfate standard solution consumed by the titration sample, in milliliters (mL);

V0- the volume of the copper sulfate standard solution consumed by the blank sample, in milliliters (mL);

m- the mass of the sample, in grams (g);

0.0180- The mass of aluminum equivalent to 1.00 mL of copper sulfate solution (concentration of 1 mol/L), in grams (g).

The calculation result is kept to two decimal places.

9 Precision

8 laboratories conduct method precision tests on 3 levels of samples, and perform statistics in accordance with GB/T 6379.2.Method precision See Table 2.