GB/T 30072-2025Ferronickel — Determination of nickel content — EDTA titrimetric method (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents". Drafting.

This document replaces GB/T 30072-2013 "Determination of Nickel Content in Iron by EDTA Titration Method" and is consistent with GB/T 30072-2013.

Aside from structural adjustments and editorial changes, the main technical changes are as follows.

a) The measurement range has been changed (see Chapter 1, Chapter 1 of the 2013 edition);

b) The conditions for the ammonium fluoride reagent have been changed (see 5.9, 4.1 of the 2013 edition);

c) The conditions for the hydroxylamine hydrochloride reagent have been changed (see 5.10, 4.2 of the 2013 edition);

d) The preparation of EDTA standard solutions has been modified (see 5.16, 4.13 in the 2013 edition);

e) The sample quantity has been changed (see 8.1, 7.1 in the 2013 edition);

f) The recommended amount of EDTA standard solution has been increased (see 8.3);

g) The determination and representation of analytical results have been improved (see 9.2);

h) The precision has been changed (see Chapter 10, Chapter 9 in the 2013 edition);

i) A flowchart of the test results acceptance procedure has been added (see Appendix A).

Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.

This document was proposed by the China Iron and Steel Association.

This document is under the jurisdiction of the National Technical Committee on Standardization of Pig Iron and Ferroalloys (SAC/TC318).

This document was drafted by: Hebei HBIS Materials Technology Research Institute Co., Ltd., Shanxi Taiyuan Iron & Steel Stainless Steel Co., Ltd., and Nanjing Iron & Steel Co., Ltd.

Limited Liability Company, Fangtongzhou Holdings Co., Ltd., Zhejiang Huanyi Resources Utilization Co., Ltd., Sichuan Chuantou Emei Ferroalloy (Group) Co., Ltd.

Limited Liability Company, CITIC (Liaoning) New Materials Technology Co., Ltd., Qingdao Dehong Jinxin Technology Co., Ltd., Jilin Iron & Steel Ferroalloy Co., Ltd.

Company, Inner Mongolia Xintaiyuan New Materials Co., Ltd., and Metallurgical Industry Information and Standardization Research Institute.

The main drafters of this document are: Zhang Caidong, Ge Jingjing, Liu Jie, An Zhiguo, Ren Lingling, Tan Shengnan, Niu Weibin, Zhao Linlin, Fang Yan, and Li Qiang.

Xiong Chunhua, Zhang Yu, Lan Lan, Bai Weipeng, Tang Huaying, Liu Fei, Li Jie, Pu Haiyan, Wang Chao, Yang Zhigang, Tang Lanlan, Wang Jun, Xu Feng, Liu Huili Ye Xiaoqing, Lu Junya, Wu Lei, Zhang Li, Zheng Haidong, Liu Jinfeng, Lu Chunsheng, Liu Yanting.

This document was first published in 2013, and this is its first revision.

Determination of nickel content in iron by EDTA titration Warning---Personnel using this document should have practical experience working in a formal laboratory. This document does not address all possible safety issues.

Users are responsible for taking appropriate safety and health protection measures and complying with the conditions stipulated in relevant national regulations.

1 Scope

This document specifies the method for determining the nickel content in ferronickel using EDTA titration.

This document applies to the determination of nickel content in ferronickel, with a determination range (mass fraction) of 5.00% to 92.00%.

2 Normative references

GB/T 6379.1

GB/T 6379.2

GB/T 6682

GB/T 8170

GB/T 12806

GB/T 12808

GB/T 24585

GB/T 25050

GB/T 25051

3 Terms and Definitions

This document does not contain any terms or definitions that need to be defined.

4 Principles

The sample was prepared with nitric acid-hydrochloric acid; for samples with high silicon content, hydrofluoric acid was added as a dissolving agent. Perchloric acid caused fuming and decomposition. Fluoride was used as a masking agent in a slightly acidic solution.

Iron, aluminum, titanium, and sodium hexametaphosphate mask manganese. Excess EDTA is added in an acetate-sodium acetate buffer solution at pH 4.6, with PAN...

As an indicator, excess EDTA is titrated with copper standard titration solution, and the amount of nickel in the sample is calculated based on the amount of copper standard titration solution consumed.

The total amount of copper and cobalt was used to subtract the amount of copper and cobalt using a mathematical correction method to calculate the mass fraction of nickel in the sample.

5 Reagents

Unless otherwise specified, only reagents of analytical purity or higher shall be used in the analysis, and the test water shall be of the standard grade specified in GB/T 6682.

Distilled water of grade 1 or 3 or higher, or water of equivalent purity.

5.1 Nitric acid, rho~1.42g/mL.

5.2 Hydrochloric acid, rho~1.19g/mL.

5.3 Sulfuric acid, rho~1.84g/mL.

5.4 Perchloric acid, rho~1.67g/mL.

5.5 Hydrofluoric acid, rho~1.15g/mL.

5.6 Ammonia water, rho~0.90g/mL.

5.7 Glacial acetic acid, rho~1.05g/mL. 5.8 Hydrochloric acid, 1 1.

5.9 Ammonium fluoride, 250 g/L. Weigh 125 g of ammonium fluoride (NH4F) into a 600 mL plastic beaker, add 300 mL of water, and add 3 drops of...

Add 5 drops of hydrochloric acid (5.2), stir until completely dissolved, then dilute with water to 500 mL and mix well. Prepare and use immediately.

5.10 Hydroxylamine hydrochloride, 100 g/L. Weigh 10 g of hydroxylamine hydrochloride (NH2OH-HCl) into a.200 mL beaker, add 50 mL of water, and stir.

After stirring until completely dissolved, dilute with water to 100 mL and mix well. Prepare and use immediately.

5.11 Acetic acid-sodium acetate buffer solution, pH=4.6.Weigh 144g of anhydrous sodium acetate (CH3COONa) and dissolve it in 500mL of water.

Add 115 mL of glacial acetic acid (5.7) to the solution, dilute with water to 1 L, and mix well.

5.12 Sodium hexametaphosphate solution, 250 g/L. Weigh 25 g of sodium hexametaphosphate [(NaPO3)6] into a.200 mL beaker, add 50 mL of...

Add water, stir until completely dissolved, then dilute with water to 100mL and mix well.

5.13 Nickel standard solution, 1.000 mg/mL. Weigh 1 0000 g of pure nickel (>=99.99%) into a 400 mL beaker, add 30 mL of...

Nitric acid (5.1) was completely dissolved by heating at low temperature, then boiled to remove nitrogen oxides and evaporated to a small volume. It was then removed and allowed to cool slightly. The salts were dissolved in water and cooled to room temperature.

Transfer the solution to a 1000mL volumetric flask, dilute to the mark with water, and mix well. 1mL of this solution contains 1.000mg of nickel. Alternatively, commercially available certified solutions may be used. Standard solution.

5.14 PAN indicator, PAN[1-(2-pyridiniazo)-2-naphthol] ethanol solution, 2.0 g/L.

5.15 Copper sulfate standard titration solution, 0.010 mol/L.

a) Preparation. Weigh 2.5000g of copper sulfate (CuSO4-5H2O) into a 300mL beaker, dissolve it in water, and then transfer it to...

Add 2 to 3 drops of sulfuric acid (5.3) to a 1000 mL volumetric flask, dilute with water to the mark, and mix well.

b) Standardization. Transfer 10.00 mL (V1) of EDTA standard solution (5.16) into three 500 mL Erlenmeyer flasks, add water...

Add 100 mL of water, then add 2-3 mL of hydrochloric acid (5.2), then add 25 mL of acetate-sodium acetate buffer solution (5.11), boil, remove from heat, and add...

Add 7 drops of PAN indicator (5.14), and titrate with copper sulfate standard titration solution (5.15) while hot, with constant shaking, until a red color is obtained.

The endpoint is reached, and the volume consumed (V0) is recorded.

Calculate the volume of copper sulfate standard titration solution (5.15) equivalent to EDTA standard solution (5.16) using formula (1). k= V1 V0 (1) In the formula.

k --- conversion factor, which is the number of milliliters of EDTA standard solution equivalent to 1 mL of copper sulfate standard titration solution;

V1 --- The volume of EDTA standard solution transferred, in milliliters (mL);

V0 --- The volume of copper sulfate standard titration solution consumed during titration, in milliliters (mL).

Perform three parallel titrations, ensuring the range of copper sulfate standard titration solution consumption does not exceed 0.10 mL. Take the average value; otherwise, repeat the titration.

The result should be rounded to four significant figures.

5.16 EDTA standard solution, 0.018 mol/L.

a) Preparation. Weigh 6 7003 g of disodium ethylenediaminetetraacetate dihydrate (C10H14N2O8Na2-2H2O) and dissolve it in 500 mL of water.

Dilute with water to 1L and mix well.

b) Standardization. Transfer 25.00 mL (V2) of nickel standard solution (5.13) into three 500 mL Erlenmeyer flasks and add water to the appropriate volume.

Add 60 mL of EDTA standard solution, then add 2-3 mL of hydrochloric acid (5.2), and accurately add 30.00 mL of EDTA standard solution (5.16).

25 mL of acetate-sodium acetate buffer solution (5.11) was boiled and removed from the heat. 7 drops of PAN indicator (5.14) were added, and the solution was immediately labeled with copper sulfate.

Titrate with the quasi-titration solution (5.15) with continuous shaking until a red color appears as the endpoint, and record the volume consumed (V4).

Calculate the actual concentration of the EDTA standard solution (5.16) according to formula (2). c = rho V2 (V3-kV4)x58.69 (2) In the formula.

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

rho --- The concentration of the nickel standard solution, expressed in milligrams per milliliter (mg/mL);

V2 --- The volume of nickel standard solution transferred, in milliliters (mL);

V3 --- The volume of EDTA standard solution added, in milliliters (mL);

k --- conversion factor, which is the number of milliliters of EDTA standard solution equivalent to 1 mL of copper sulfate standard titration solution;

V4 --- The volume of copper sulfate standard titration solution consumed when standardizing nickel standard solution, in milliliters (mL);

58.69 --- Molar mass of nickel, in grams per mole (g/mol).

Perform three parallel titrations, ensuring the range of copper sulfate standard titration solution consumption does not exceed 0.10 mL. Take the average value; otherwise, repeat the titration.

The result should be rounded to four significant figures.

6 Instruments

7 Taking samples

Sampling shall be performed in accordance with the provisions of GB/T 25050 and GB/T 25051.Powder and granular samples shall pass through a 0.154 mm sieve.

The sample (drilled) should pass through a 2.5mm sieve.

8 Test Procedure