Occurrence state of fluoride in barite ore and the complexation leaching process.

Barite ore is typically associated with difficult-to-remove vein minerals, but commercial barite products require a high BaSO4 content. We investigated the occurrence state of fluoride in barite ore using various analytical techniques, which indicated that elemental fluorine in barite predominantly exists as fluorite. Fluoride was then leached from barite ore via complexation. The effects of HCl and AlCl3 concentrations, temperature, time, and liquid-solid ratio on the leaching rate were examined, and the leaching conditions were optimized using an orthogonal array method. The fluorine leaching rate approached 93.11% after stirring for 30 min at 90 °C and 300 rpm with 3 mol/L HCl, 0.4 mol/L AlCl3, a liquid-solid ratio of 10:1 mL/g, and an ore sample size of -75 µm + 48 µm. According to the leaching kinetics, the process conformed to the solid membrane diffusion control model at a high temperature and the joint chemical reaction-diffusion control model at a low temperature. The apparent activation energy was 56.88 kJ/mol. Furthermore, aluminum and fluorine coordination numbers increased with increasing Al3+/F- molar concentration ratios. Competing complexation reactions of Al3+, H+, and F- occurred at three levels. This complexation approach effectively leaches fluoride from barite, improves barite product quality, and reduces environmental pollution.

Determination of carbonate content in barite ore by headspace gas chromatography.

This paper reports a method for determining the carbonate content in barite ore using headspace gas chromatography. Based on the acidification reaction, the carbonate in the barite ore was converted to CO2 in a closed headspace vial. When the carbonate content was significant, the pressure caused changes in the CO2 and O2 signals and affected the measurement accuracy. It was found that carbonate content is proportional to the intensity ratio of the CO2 to O2 signals. Thus, the carbonate content in barite ore can be measured indirectly using a theoretical model. The results showed that the carbonate in 3 g of barite ore sample with a particle size of 74 µm could react completely with a hydrochloric acid solution (2 mol/L) at 65°C for 5 min. The method described herein had good precision (relative standard deviation < 4.14%) and accuracy (relative differences < 6.12%). Further, the limit of quantification was 0.07 mol/L. Owing to its simplicity and speed, this method can be used for the batch determination of carbonate content in barite ore.

Determination of barium sulfate in barite ore by phase conversion-partial pressure-corrected headspace gas chromatography.

Barium sulfate (BaSO4) content is used to evaluate the grade of barite ore. In the present study, we report a method to determine the BaSO4 content in barite ore by phase conversion-headspace gas chromatography with partial pressure correction. In this method, the ore sample is roasted with sodium carbonate and potassium carbonate after pretreatment with hydrochloric acid. The roasted product is subsequently placed in a closed headspace bottle to react with hydrochloric acid. The ratio of CO2 to O2 signals is detected by a thermal conductivity detector for gas chromatography. Finally, the BaSO4 content in barite ore is calculated using this ratio. The method demonstrates good precision (relative standard deviation < 0.84%) and accuracy (relative error < 3.40%), with the uncertainty at 95% confidence interval at approximately +/- 0.57%. Moreover, this approach is expected to be used for the batch testing of BaSO4 content in barite ores in industrial applications.