Flotation of fine scheelite

With the depletion of easily recoverable tungsten resources, the flotation of fine-grained scheelite has become a critical challenge for efficient tungsten utilization. These ores are characterized by fine dissemination, high surface energy, and surface property convergence with calcium-containing gangue minerals (e.g., calcite), leading to inefficiencies in conventional flotation. The main difficulties include low particle momentum hindering bubble adhesion, non-selective aggregation due to large specific surface area, interference from unavoidable ions in pulp, and excessive foam stability complicating concentrate purification.

Innovations focus on three aspects: processes, reagents, and equipment. In processes, selective flocculation flotation uses polymeric flocculants (e.g., PG) to induce selective aggregation of scheelite, increasing apparent particle size and improving recovery by 2.75%. Shear flocculation enhances collision of hydrophobic particles under high shear forces, boosting recovery by up to 20%. Carrier flotation employs coarse particles or artificial carriers (e.g., polystyrene) to "load" fine particles, improving bubble adhesion and reducing slime interference. Combined processes (e.g., "flotation-magnetic-gravity separation") achieve over 80% recovery for complex ores through multi-technology synergy.

Reagents are pivotal for fine particle separation. Sodium oleate, a traditional collector, requires selective inhibitors (e.g., water glass, SNF) or metal ions (e.g., Pb²⁺) to enhance adsorption due to its poor selectivity. Novel reagents like metal complexes (Pb-BHA) regulate surface charge and hydrophobicity, achieving 95% scheelite recovery. For depressants, sulfonated naphthalene formaldehyde (SNF) shows superior selectivity for calcite, with adsorption four times higher than on scheelite, enabling high-grade concentrates.

Equipment advancements prioritize microbubble generation and fluid dynamics. Cyclone-static microbubble flotation columns utilize countercurrent collision principles in low-turbulence environments, reducing tailings grade to 0.10%. Horizontal baffled flotation columns generate uniform bubbles through microchannels, achieving over 65% recovery across particle sizes. Cavitation flotation cells (CFC) integrate turbulent flow and static separation, matching multi-cleaner performance in a single step while increasing recovery by 3.2%.

Future research requires deeper exploration of multi-factor synergies. Balancing bubble size and reagent concentration, optimizing grinding for surface properties, and elucidating particle interactions for carrier effects remain crucial. Developing eco-friendly reagents, refining combined processes, and modeling internal flow fields will drive breakthroughs. Only through integrated technological innovation and mechanistic studies can clean and efficient recovery of fine scheelite be realized, alleviating resource scarcity and environmental pressures.