Section I Determination of Calcium and Magnesium Oxides Content
EDTA Titrimetric Method
1 Subject Content and Application Scope
This standard specifies the determination of calcium and magnesium oxides content by EDTA titrimetric method.
This standard is applicable to the determination of calcium and magnesium oxides content in limestone products for chemical industry and the determination range is 1%~4% for magnesium oxide and greater than 49% for calcium oxide.
2 Normative References
GB 6682 Water for Analytical Laboratory Use - Specification and Test Methods
GB 601 Chemical Reagent - Preparations of Standard Volumetric Solutions for Titrimetric Analysis (Volumetric Analysis)
GB/T 15057.4 Limestone for Chemical Industry - Determination of Iron and Aluminium Oxides Content - Gravimetric Method
3 Method Summary
Decompose the specimen with hydrochloric acid, hydrofluoric acid and perchloric acid, mask interference elements such as iron and aluminium with triethanolamine, and titrate calcium with EDTA standard titration solution by taking calcium carboxylic acid as indicator in the solution greater than 12.5 in pH value. When pH≈10, titrate the total calcium and magnesium with EDTA standard titration solution by taking neolan blue K - naphthol green B as mixed indicator and calculate the magnesium oxide content by subtraction method.
4 Reagents and Solutions
Water used in this standard shall conform to the specification of Grade 3 water specified in GB 6682; unless otherwise specified, the adopted reagents refer to analytical reagents.
4.1 Hydrochloric acid (GB 622) solution: 1+1.
4.2 Hydrofluoric acid (GB/T 620).
GB/T 15057.2-1994 The following standards are cited：
GB/T 15057.2-1994 Cited by the following standards：
