Determination of Boron in Ores by Fluoride Titration

Significance of the Topic

Determining boron content in ores such as borax and ulexite is critical for quality control in industries including ceramics, glass production, agriculture and metallurgy. Thermometric titration using fluoride offers a rapid, precise and interference-resistant approach, allowing accurate quantification even in the presence of metal ions. It streamlines sample analysis and enhances laboratory efficiency.

Objectives and Study Overview

The primary objective of this study was to demonstrate a validated procedure for quantifying boron in boron-bearing ores via fluoride thermometric titration. Key goals included:

• Establishing an acid digestion protocol for ulexite in slurry and powder forms
• Applying thermometric detection of exothermic reactions between boric acid and fluoride
• Evaluating method precision, accuracy and blank correction

Methodology

Samples of ulexite were subjected to acid digestion using concentrated HCl followed by dilution and silica removal by filtration. Aliquots were titrated with 2 mol/L KF in acidic medium (25 % H2SO4). Thermometric endpoints were detected by measuring temperature changes, with one main exothermic inflection recorded. Blank determinations were performed by regression of titrant volume versus sample mass. KF titrant was standardized according to reference procedures.

Used Instrumentation

• Thermometric titrator with thermistor endpoint detection
• Magnetic stirrer hotplate
• Wide-neck Erlenmeyer flasks and volumetric glassware
• Precision balance and pipettes

Main Results and Discussion

Analysis of ulexite slurry yielded boron contents of 4.36 % and 4.34 % w/w for two samples (n=6 and n=12 respectively), while ulexite powder returned 9.85 % w/w (n=7). Precision was high (RSD ≤ 0.7 %). Blank correction (y-intercept 0.1722 mL) ensured accuracy. The thermometric titration plot showed clear temperature and second-derivative inflections despite slower kinetics in the second reaction step.

Benefits and Practical Applications

• High selectivity for boric acid, unaffected by metal-fluoride complexes
• Independence from other acids in the sample matrix
• Rapid throughput and reproducible results suitable for routine QA/QC
• Minimal sample preparation effort and high tolerance to interferences

Future Trends and Potential Applications

Advances may include integration with automated titration platforms, miniaturization of sample handling, and coupling with complementary techniques such as ICP-MS for multi-element analysis. Enhanced data modeling and AI-driven endpoint detection could further improve precision and speed.

Conclusion

Fluoride thermometric titration presents an efficient and reliable method for boron determination in ores. Its robustness against interferences and strong precision make it a valuable tool for laboratories in mineral analysis and industrial QA/QC.