Comprehensive Utilization of Boron-Concentrate by Hydrometallurgy

A new eco-friendly process to comprehensively utilize boron-concentrate is proposed in this paper. In this process, Iron-concentrate, silicon dioxide, magnesium oxide, and boric acid could be produced from boron-concentrate. The highlight of this process was minimal waste discharge during the whole process. Iron removal was a key step to ensure the quality of boric acid and magnesium oxide. The introduced goethite precipitation method could remove iron to a very low level. With the addition of 3 cm(3) H2O2 (5 vol. %) as an oxidizing agent, more than 99% of iron was removed from the leaching liquor. After the removal of iron, the resulting liquor was used to prepare magnesium precipitate. And the optimal preparation conditions were: the temperature of 30 degrees C and precipitation time of 60 min, ammonium- magnesium ratio of 1.5, the magnesium ion concentration of 34.8 g.L-1. Under those conditions, the magnesium precipitation efficiency was up to 98.5%. Magnesium oxide was obtained by roasting magnesium precipitate at 550 degrees C for 2 h. Then the mixed crystals of ammonium sulfate and boric acid were obtained by evaporating the liquor after iron removing and magnesium precipitating. Boric acid was separated from ammonium sulfate by dissolving the mixed crystals in ethanol solution

Automated summary

A new eco-friendly process for comprehensively utilizing boron-concentrate was proposed in this paper, with minimal waste discharge and production of various products. Iron removal was highlighted as a key step, with goethite precipitation method effectively removing iron. Additional oxidizing agent H2O2 was used to achieve over 99% iron removal, ensuring high quality boric acid and magnesium oxide.