Structures of Pb-BHA Complexes Adsorbed on Scheelite Surface.

Area of Science:

• Mineral processing and surface chemistry.
• Application of coordination chemistry in mineral flotation.

Background:

• Lead-benzohydroxamic acid (Pb-BHA) complexes show promise as flotation collectors.
• The specific structures of Pb-BHA complexes adsorbed on mineral surfaces are not well understood.
• Understanding these structures is crucial for optimizing flotation processes.

Purpose of the Study:

• To investigate the adsorption behavior of Pb-BHA complexes on scheelite.
• To elucidate the structural characteristics of Pb-BHA complexes adsorbed on the scheelite surface.
• To correlate adsorption structures with flotation performance.

Main Methods:

• Flotation experiments were conducted to assess collecting ability.
• Adsorption capacity measurements quantified the amount of adsorbed species.
• X-ray photoelectron spectroscopy (XPS) analyzed surface elemental composition and chemical states.
• Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provided detailed structural information.

Main Results:

• Higher BHA adsorption was observed during Pb-BHA flotation compared to activation flotation.
• XPS and TOF-SIMS revealed similar adsorbed Pb-BHA species in both flotation methods.
• The quantity of adsorbed complexes, rather than their type, influenced flotation behavior.
• Complexes featured five- and four-membered ring structures, with lead ions potentially forming monomers with BHA and interacting with lead hydroxide polymers.

Conclusions:

• Pb-BHA complexes adsorb onto the scheelite surface, forming hydrophobic layers that facilitate flotation.
• The structural analysis indicates the formation of monomeric Pb-BHA complexes and interactions with lead hydroxide polymers.
• The concentration of these complexes on the scheelite surface is the key factor determining flotation effectiveness.