A novel method for efficient recovery of boron from boron-bearing iron concentrate: Mineral phase transformation and low-temperature separation via super-gravity

Abstract

As the tailings of complex paigeite ore through the multistep magnetic separation process, the boron-bearing iron concentrate is mainly used in the ironmaking process for the recovery of iron, while the boron is hard to be recovered. In this study, a novel method was proposed for efficient recovery of boron from boron-bearing iron concentrate through mineral phase transformation and low-temperature separation via super-gravity. The mineral phase transformation of boron-bearing iron concentrate in the reduction process as a function of the temperature mainly included three stages, Stage I: The iron minerals were fully reduced to metallic iron at 1373–1423 K, Stage II: The boron was mainly transformed from suanite (Mg2B2O5) into the boron-rich slag with a high concentration at 1473–1523 K, Stage III: The forsterite (Mg2SiO4) was further melted into slag and some boron was also reduced and entered into liquid iron which caused a significant decrease in boron concentration in the slag at 1573–1623 K. Thus, low-temperature separation of boron-rich slag from the iron phase was conducted at 1523 K via super-gravity. The boron was efficiently recovered into the boron-rich slag with a high recovery of 98.24 % and a high mass fraction of B2O3 of 39.27 wt%, and almost all boron was enriched into a form of suanite. Low-temperature separation greatly improves the recovery of boron in boron-rich slag and prevents boron from entering metallic iron, and also improves the activity of boron-rich slag for sustainable utilization.