Selective flotation separation of bastnaesite from dolomite using beta-naphthyl sulfonate formaldehyde condensate as depressant: Experimental and calculational studies

It is difficult to recover bastnaesite from dolomite when using octyl hydroxamic acid (OHA) as collector owing to the similar chemical properties between bastnaesite and dolomite. In this work, beta-naphthyl sulfonate formaldehyde condensate (NSFC), as an effective depressant for dolomite has been employed. The flotation performance of NSFC in bastnaesite-dolomite system has been investigated with the help of single minerals flotation and artificially mixed minerals flotation. The depression mechanism has been first proposed from micro level by means of XPS analyses and molecular dynamic simulations. The flotation results demonstrate that NSFC showed a higher affinity towards dolomite instead of bastnaesite, and rare earth element can be effectively recovered using NSFC as depressant in bastnaesite-dolomite system. Mg active sites existing on dolomite surface are more prone to reacting with NSFC depressant through chemical bonding. The distance between Mg active sites on dolomite surface and oxygen components in sulfo groups became closer after interaction, which is opposite to that of Ca active sites, indicating that Mg active sites are the predominant place for NSFC attachment. The findings reveal that NSFC in conjunction with OHA could be used as an effective flotation reagent scheme for satisfactory recovery of bastnaesite when dolomite is the main associated gangue mineral.