GB/T 40795.1-2021Chemical analysis method of lanthanum-cerium metals and their compounds—Part 1: Determination of cerium content—Ammonium ferrous sulfate titration 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 the first part of GB/T 40795 "Methods for chemical analysis of lanthanum and cerium metal and its compounds". GB/T 40795 has been released The following parts.

---Part 1: Determination of the amount of cerium ferrous ammonium sulfate titration method.

---Part 2: Determination of the amount of rare earths.

Introduction

Lanthanum cerium metal and its compound series products currently occupy a large share in the domestic market, and the demand for international trade is also very large.

Market demand is still expected to grow further. Lanthanum cerium metal is the main raw material for the rare earth hydrogen storage alloy used in the production of nickel-metal hydride batteries.

With the development of the automobile industry, it has become a trend to replace metal cerium with lanthanum cerium for the production of rare earth hydrogen storage alloys. At the same time, lanthanum cerium compound Mineral products are the rare earth products with the largest output, which are mainly used in the production of new polishing powders and petroleum catalytic cracking agents. Establish lanthanum cerium metal and its compound The method for determining the amount of cerium and the amount of rare earths can meet the basic needs of related production and trade, standardize the testing process of related products, and give precise Therefore, it can improve the comparability of test data, reduce the disputes between the supply and demand parties on the test results, and also help regulate the quality of related products. Control the amount and promote its application.

GB/T 40795 "Methods for chemical analysis of lanthanum and cerium metal and its compounds" consists of two parts.

---Part 1: Determination of the amount of cerium ferrous ammonium sulfate titration method;

---Part 2: Determination of the amount of rare earths.

Between the two parts, the detection of the amount of cerium overlaps. Part 1: Determination of lanthanum and cerium metals and their chemical compounds by ferrous ammonium sulfate titration method The content of cerium in the compound is suitable for the determination of higher content of cerium and cerium oxide; the second part is to first determine the rare earth impurities by the ICP-OES method Then, the amount of lanthanum and cerium is determined by the subtraction method. The lower limit of the analysis of rare earth impurity elements is low, which is convenient for comprehensive understanding and tracking of lanthanum and cerium metal and its compound system.

List the distribution of the amount of rare earth elements in the products. When the two parts overlap for the determination range of the amount of cerium, the accuracy of the ferrous ammonium sulfate titration method is taken into account Higher, the arbitration method should choose this method.

1 Scope

This document specifies the method for determining the cerium content in lanthanum-cerium metal and its compounds.

This document is applicable to the determination of cerium content in lanthanum cerium metal, and the determination of cerium oxide content in lanthanum cerium oxide, lanthanum cerium carbonate, and lanthanum cerium chloride. See Table 1 for the specified range.

Note: The measurement range of lanthanum cerium metal is the mass fraction of cerium, and the measurement range of lanthanum cerium oxide, lanthanum cerium carbonate and lanthanum cerium chloride is the mass fraction of cerium oxide.

2 Normative references

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

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 Principles of the method

After the sample is dissolved with hydrochloric acid or nitric acid, in the phosphoric acid medium, perchloric acid oxidizes the trivalent cerium to tetravalent; in the dilute sulfuric acid medium, add urine Use sodium nitrite solution to reduce purple-red high-valent manganese to colorless divalent manganese to eliminate the interference of manganese; refer to phenylanthranilic acid Indicating agent, titrate the cerium ion in the test solution with ferrous ammonium sulfate standard titration solution.

5 Reagents

Unless otherwise specified, only reagents and distilled water or deionized water or equivalent purity water are used in the analysis.