Enhanced flotation of Pb(II)-activated wolframite using a novel collector

Abstract

ABSTRACT The flotation enrichment of fine-particle wolframite played a crucial role in production of strategic key metal tungsten. In this paper, N-[(3-hydroxyamino)-propoxy]-N-hexyl dithiocarbamate (HAHD) was designed to strengthen the flotation recovery of wolframite. The in situ AFM images clearly exhibited that the pre-activation of wolframite with Pb2+ ions significantly enhanced the self-assemble and aggregation of HAHD on its surface, and its surface hydrophobicity and floatability dramatically improved. The FTIR and XPS results recommended a chemisorption of HAHD to the Pb(II)-activated wolframite, and in the surface HAHD-Pb(II) complexes, both dithiocarbamate and hydroxamate groups chelated Pb(II) to deliver the four-membered and five-membered ring configurations. The double-site adsorption rendered a closed loop anchor of HAHD on the Pb(II)-activated wolframite surface, which essentially weakened the hydration of OH- ions toward Pb2+, Fe2+ or Mn2+ ions in/on wolframite interface. In addition, the hexyl group exhibits a strong hydrophobization, and the dithiocarbamate displays a selective affinity against alkaline earth metal minerals. These encouraged HAHD to be a strong-power and selective collector for wolframite versus calcite at its low dose.