GB/T 40795.2-2021Chemical analysis methods of lanthanum-cerium metals and their compounds—Part 2: Determination of rare earth content (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 second 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. "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 or cerium oxide; Part 2, using the ICP-OES method, first determine the rare earth impurities 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 amount of rare earth in lanthanum cerium metal and its compounds.

This document applies to the determination of the amount of rare earths in lanthanum cerium metal, lanthanum cerium oxide, lanthanum cerium carbonate, and lanthanum cerium chloride. The measurement range is shown in Table 1.

Note: The measurement range of lanthanum cerium metal is the same as the mass fraction of each corresponding rare earth oxide in the measurement range of lanthanum cerium oxide, lanthanum cerium carbonate and lanthanum cerium chloride.

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

The sample is dissolved in nitric acid, excited by an argon plasma light source in a dilute nitric acid medium, and the spectrum is measured. Among them, other than lanthanum and cerium The content of each rare earth element is determined by the matrix matching method, and the total content is calculated, and then the total content of lanthanum and cerium is calculated by the subtraction method, and then the normalization method is used for analysis. Do not calculate the content of lanthanum and cerium.