Fluorine removal from high-fluorine beryllium ore by roasting and leaching pretreatment

• A synthetic mechanism for fluorine separation and removal is proposed.
• Additives transform calcium fluoride into solubility compound.
• Roasting and acid-leaching make fluorine removal feasible.
• Beryllium ore was treatment under low temperature and less treating time.

To avoid the influence of fluorine on the extraction of beryllium, separating fluorine from high-fluorine beryllium ore was discussed in this study. The factors affecting on fluorine removal, such as roasting temperature, roasting time, dosage of the additive in roasting process, and the variety and concentration of acid in the leaching process, were separately investigated. The intermediates and final products were identified by XRD. Under the following roasting and leaching conditions: heating temperature 800 °C, treatment time 120 min, additive dosage of Na2CO3 by 60% weight, leaching by distilled water at 50 °C for 30 min and acid (1.7 mol/L HNO3) at 60 °C for 60 min, the percentage of fluorine and beryllium oxide was 1.6%; heating temperature 800 °C, treatment time 180 min, additive dosage of Na3PO4 by 50% weight, leaching by distilled water at 50 °C for 30 min and acid (1.7 mol/L HNO3) at 60 °C for 60 min, the percentage of fluorine and beryllium oxide was 7.12%. Both of the results with additive Na2CO3 and Na3PO4 can meet the requirement of the industrial production of beryllium after the pretreatment, while Na2CO3 is more efficient. Results also indicated that nitric acid was more reactive than sulfuric acid.