GB/T 7731.4-2021Ferrotungsten—Determination of phosphorus content—Phosphorus molybdenum blue spectrophotometric method (English PDF)

Foreword

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

This document is Part 4 of GB/T 7731.GB/T 7731 currently publishes the following parts.

---Determination of tungsten iron tungsten content Cinchonine gravimetric method and ammonium nitrate gravimetric method;

---Determination of tungsten, ferromanganese, periodate spectrophotometry and flame atomic absorption spectrometry;

---Determination of tungsten iron copper content dicyclohexanone oxalyl dihydrazone photometry and flame atomic absorption spectrometry;

---Determination of ferrotungsten and phosphorus content Phosphomolybdenum blue spectrophotometric method;

---Determination of tungsten iron silicon content silicon molybdenum blue spectrophotometric method;

---Determination of tungsten, iron, arsenic content, molybdenum blue photometry and inductively coupled plasma atomic emission spectrometry;

---Determination of tungsten iron tin content phenylfluorone photometric method and inductively coupled plasma atomic emission spectrometry;

---Determination of iron tungsten and antimony content Rhodamine B photometric method and inductively coupled plasma atomic emission spectrometry;

---Determination of bismuth tungsten iron bismuth iodide photometric method and inductively coupled plasma atomic emission spectrometry;

---Determination of tungsten iron carbon content infrared absorption method;

---Determination of ferro-tungsten and sulfur content infrared absorption method and combustion neutralization titration method;

---Determination of tungsten, iron and lead content by polarography and inductively coupled plasma atomic emission spectrometry.

This document replaces GB/T 7731.4-1987 "Methods for Chemical Analysis of Ferrotungsten Molybdenum Blue Photometric Method for the Determination of Phosphorus Content", and is compatible with GB/T 7731.4-1987 Compared with 1987, in addition to structural adjustments and editorial changes, the main technical changes are as follows.

a) Modified the measurement range from "< 0.06%" to "0.010%~0.080%" (see Chapter 1, Chapter 1 of the 1987 edition);

b) Add "sulfuric acid (1+1)" (see 5.6), "potassium sodium tartrate solution" (see 5.13);

c) Modified the adding amount and phenomenon of ammonium hydroxide solution, from "adding ammonium hydroxide to make the solution brownish red with an excess of 20mL" changed to "adding Add ammonium hydroxide until a white precipitate appears in the solution and an excess of 30 mL" (see 7.3.3, 4.3.1 of the 1987 edition);

d) Modified the reagents added in the color development process of the test solution, and added "potassium sodium tartrate solution" (see 7.3.5, 4.3.2 of the 1987 edition);

e) The allowable error in the laboratory has been added (see Chapter 9, Chapter 6 of the 1987 edition);

f) Added "Test Results Acceptance Flow Chart" (see Appendix A).

Introduction

As there are many elements involved in the detection process of ferrotungsten, the applicable scope and applicable methods of the elements are different. In order to guarantee tungsten The iron detection standards are convenient and accurate. We have established a national standard for the analysis of different elements of ferrotungsten.

The GB/T 7731 ferro-tungsten series analysis method is the basic standard for the detection of ferro-tungsten in my country, and it is planned to be composed of the following fourteen parts. But some The points have been abolished, and you need to pay attention to it during use.

---GB/T 7731.1 Determination of tungsten iron tungsten content Cinchonine gravimetric method and ammonium nitrate gravimetric method. The purpose is to measure the tungsten iron For the tungsten content, the cinchonine gravimetric method and the ammonium nitrate gravimetric method are used.

---GB/T 7731.2 Determination of Tungsten Ferromanganese Content Periodate Spectrophotometry and Flame Atomic Absorption Spectrometry. Aim at To measure the manganese content in ferrotungsten, periodate spectrophotometry and flame atomic absorption spectrometry were used.

---GB/T 7731.3 Determination of tungsten-iron-copper content. Dicyclohexanone oxalyl dihydrazone spectrophotometry and flame atomic absorption spectrometry. Item The method is to measure the copper content in ferro tungsten, using dicyclohexanone oxalyl dihydrazone spectrophotometry and flame atomic absorption spectrometry.

---GB/T 7731.4 Determination of Tungsten Ferrophosphorus Content Phosphomolybdenum Blue Spectrophotometric Method. The purpose is to measure the phosphorus content in ferro tungsten, Using phosphomolybdenum blue spectrophotometry.

---GB/T 7731.5 Determination of tungsten ferrosilicon content Silicon molybdenum blue spectrophotometric method. The purpose is to measure the silicon content in ferro tungsten, Using silicon molybdenum blue spectrophotometry.

---GB/T 7731.6 Determination of tungsten, iron, arsenic content, molybdenum blue photometry and inductively coupled plasma atomic emission spectrometry. Item The purpose is to measure the arsenic content in ferro-tungsten, using molybdenum blue photometry and inductively coupled plasma atomic emission spectrometry.

---GB/T 7731.7 Determination of tungsten-iron-tin content-Phenylfluorone photometric method and inductively coupled plasma atomic emission spectrometry Law. The purpose is to measure the tin content in ferro tungsten, using phenylfluorone photometry and inductively coupled plasma atomic emission light Spectrum method.

---GB/T 7731.8 Determination of tungsten iron antimony content Rhodamine B photometric method and inductively coupled plasma atomic emission spectrometry Law. The purpose is to measure the antimony content in ferro tungsten, using rhodamine B photometry and inductively coupled plasma atomic emission light Spectrum method.

---GB/T 7731.9 Determination of bismuth tungsten iron bismuth iodide photometric method and inductively coupled plasma atomic emission spectrometry.

The purpose is to measure the bismuth content in ferro-tungsten, using bismuth iodide photometry and inductively coupled plasma atomic emission spectrometry.

---GB/T 7731.10 Determination of tungsten iron carbon content infrared absorption method. The purpose is to measure the carbon content in ferro tungsten, using Infrared absorption method.

---GB/T 7731.11 Ferrotungsten Chemical Analysis Method Coulometric Method for the Determination of Carbon Content. The purpose is to measure the carbon content in ferro tungsten, using Coulomb method. This part has been abolished.

---GB/T 7731.12 Determination of tungsten iron and sulfur content infrared absorption method and combustion neutralization titration method. The purpose is to measure tungsten The sulfur content in iron uses infrared absorption method and combustion neutralization titration method.

---GB/T 7731.13 Methods for chemical analysis of ferrotungsten. Combustion neutralization titration method for the determination of sulfur content. The purpose is to measure the sulfur in ferro tungsten For the content, use the combustion neutralization titration method. This part has been abolished.

---GB/T 7731.14 Determination of tungsten, iron and lead content by polarography and inductively coupled plasma atomic emission spectrometry. Purpose To measure the lead content in ferro-tungsten, polarography and inductively coupled plasma atomic emission spectrometry are used.

Warning---Personnel using this document should have formal laboratory work experience. This document does not indicate all possible safety issues question. The user is responsible for taking appropriate safety and health measures and ensuring compliance with the conditions stipulated by relevant national laws and regulations.

1 Scope

This document specifies the phosphomolybdenum blue spectrophotometric method for the determination of phosphorus content in ferrotungsten.

This document is applicable to the determination of phosphorus content in ferro-tungsten, the measurement range (mass fraction). 0.010%~0.080%.

2 Normative references

The contents of the following documents constitute the indispensable clauses of this document through normative references in the text. Among them, dated quotations Only the version corresponding to that date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to this document.

GB/T 4010 Collection and preparation of samples for chemical analysis of ferroalloys

GB/T 6682 Analytical laboratory water specifications and test methods

GB/T 8170 Numerical rounding rules and the expression and determination of limit values

3 Terms and definitions

There are no terms and definitions that need to be defined in this document.

4 Principle

The sample is decomposed with nitric acid and hydrofluoric acid, the perchloric acid is treated with white smoke, soluble salts are dissolved in water, and disodium ethylenediaminetetraacetic acid is used to mask the iron. Into beryllium sulfate, the phosphorus is generated in the ammonia solution to produce ammonium phosphate and beryllium hydroxide to co-precipitate. After separation, the precipitate is dissolved with hydrochloric acid and treated with perchloric acid. Physiologically, iron is reduced with sodium bisulfite, tungsten is masked with potassium and sodium tartrate, ammonium molybdate and hydrazine sulfate are added to react to form phosphomolybdenum blue, which is measured in a spectrophotometer. Measure the absorbance at 825nm and calculate the mass fraction of phosphorus.

5 Reagents

Unless otherwise specified, only use analytical reagents.

5.1 Water, GB/T 6682, level three.

5.2 Hydrochloric acid, rho = 1.19 g/mL.

5.3 Hydrofluoric acid, rho = 1.15 g/mL.

5.4 Perchloric acid, rho = 1.67 g/mL.

5.5 Ammonium hydroxide, rho = 0.90 g/mL.

5.6 Sulfuric acid (1+1).

5.7 Nitric acid (1+1).

5.8 Hydrochloric acid (1+3). […]