GB/T 26019-2010 in English

《GB/T 26019-2010高杂质钨矿化学分析方法 三氧化钨量的测定 二次分离灼烧重量法》由TC243（全国有色金属标准化技术委员会）归口，TC243SC3（全国有色金属标准化技术委员会稀有金属分会）执行，主管部门为中国有色金属工业协会。

Methods for chemical analysis of high impurity tungsten mineral - Determination of tungsten trioxide content - Twice separation and igniting gravimetric method

1 Scope

This standard specifies the determination of tungsten trioxide content in high impurity tungsten mineral.

This standard is applicable to the determination of tungsten trioxide content in tungsten mineral with phosphorus content of less than 2%, titanium content of less than 1% and tin content of less than 2%. The determination range of tungsten trioxide is over 20%.

2 Principle

In the presence of a small amount of ammonium fluoride, the specimen is dissolved with hydrochloric acid, nitric acid and perchloric acid, concentrated until white smoke is emitted to remove excess fluoride ions and nitrate, tungsten is precipitated into tungstic acid, filtered, separated from most of the co-existing elements, tungstic acid is dissolved with aqueous ammonia, ferric nitrate and beryllium nitrate are added to precipitate and separate other impurities, and tungsten trioxide is weighed after the filtrate is evaporated, ignited, desilicated with hydrofluoric acid, and reignited. The tungsten trioxide content in residue is determined by spectrophotometry, and the result is corrected. When the molybdenum content is greater than 0.3%, the result needs to be corrected.

3 Reagents

Unless otherwise specified, analytically-pure reagents and distilled water meeting the requirements of national or professional standards shall be used for purpose of this part.

3.1 Sodium peroxide.

3.2 Ammonium fluoride.

3.3 Ethylenediamine tetraacetic acid disodium (EDTA).

3.4 Hydrochloric acid (ρ=1.19g/mL).

3.5 Nitric acid (ρ=1.42g/mL).

3.6 Hydrofluoric acid (ρ=1.15g/mL).

Foreword i
1 Scope
2 Principle
3 Reagents
4 Specimen
5 Analysis steps
6 Calculation of analysis results
7 Precision
8 Quality assurance and control