Methods for chemical analysis of lithium carbonate, lithium hydroxide monohydrate and lithium chloride—Part 1: Determination of lithium carbonate content—Titration
GB/T 11064.1-2024 Methods for chemical analysis of lithium carbonate, lithium hydroxide monohydrate and lithium chloride - Part 1: Determination of lithium carbonate content - Titration
1 Scope
This document describes methods for the determination of lithium carbonate content in lithium carbonate products, including the acid-base titration (Method I) and potentiometric titration (Method II).
This document is applicable to the determination of lithium carbonate content in lithium carbonate products, with the determination range from 95.00% (m/m) upwards. Other forms of carbonate, if any, are converted to lithium carbonate and deducted.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 12805 Laboratory glassware - Burettes
GB/T 17433 Foundation terms for chemical analysis of metallurgical products
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T 17433 apply.
4 Method I: Acid-base titration
4.1 Principle
The test portion is dissolved in a certain amount of water. With methyl red-bromocresol green as the indicator, hydrochloric acid standard volumetric solution is applied to titrate until the solution changes from green to burgundy. The content of lithium carbonate is calculated according to the volume of consumed hydrochloric acid standard volumetric solution.
4.2 Reagents or materials
Unless otherwise specified, only reagents of analytical grade are used.
4.2.1 Water, GB/T 6682, Grade II, boiled, sealed and cooled to room temperature.
4.2.2 Methyl red-bromocresol green indicator: Weigh 0.1 g of bromocresol green, dissolve it in ethanol (95%), dilute with ethanol (95%) to 100 mL (Solution I); weigh 0.2 g of methyl red, dissolve it in ethanol (95%), and dilute with ethanol (95%) to 100 mL (Solution II). Take 30 mL of Solution I and 10 mL of Solution II and mix them well.
4.2.3 Hydrochloric acid standard volumetric solution (about 0.50 mol/L): Pipette 45 mL of hydrochloric acid (ρ = 1.19 g/mL), put it in a 1,000 mL volumetric flask, dilute it with water to the mark and mix well. Perform standardization as follows.
a) Take three portions of 0.65 g (accurate to 0.000 1 g) of anhydrous sodium carbonate (reference reagent) pre-dried at 270 ℃ ~ 300 ℃ to a constant weight, separately place them into 250 mL conical flasks, add 50 mL of water to dissolve, add 10 drops of methyl red-bromocresol green indicator (4.2.2), use hydrochloric acid standard volumetric solution (4.2.3) to titrate until the solution turns from the green to burgundy, boil for 2 min, continue the titration until the solution turns to burgundy again and the color does not fade for 30 s to reach the end point. The extreme difference in the volume of hydrochloric acid standard volumetric solution consumed for the parallel standardization shall not exceed 0.05 mL, and the mean value shall be taken. The calculation result is rounded to 4 significant figures. Carry out blank test along with the standardization.
Foreword i Introduction iii 1 Scope 2 Normative references 3 Terms and definitions 4 Method I: Acid-base titration 5 Method II: Potentiometric titration 6 Test report Annex A (Informative) Statistical results of the raw data of accuracy test
