The sample is decomposed by hydrofluoric acid and sulfuric acid, and leached with saturated ammonium oxalate, so that calcium precipitates with calcium oxalate and is separated from tungsten, iron, manganese and other elements. After filtration, nitric acid-perchloric acid is used to dissolve the precipitate and destroy the filter paper. In dilute hydrochloric acid solution, use triethanolamine to mask residual iron, manganese, etc. Use calcein-thymolphthalein as indicator, and titrate with EDTA standard solution when the pH value is greater than 12.
T/GZNFS 001.5-2019 history
2019T/GZNFS 001.5-2019 Methods for Chemical Analysis of Tungsten Slag Part 5: Determination of Calcium Content