Recovering molybdenite from ultrafine waste tailings by oil agglomerate flotation

Neutral oils like kerosene, diesel, transformer and rapeseed oil were used as collectors or bridging reagents in conventional flotation and oil agglomeration flotation (OAF) process, and a promising OAF process has been developed for the recycling of ultrafine molybdenite resources from the waste tailings. The average size of collected particles (d(50)(p)), agglomerates (d(50)(a)) and their distribution of the froth concentrate were determined by laser particle size analyzer or sieve analysis. Conventional flotation froth cannot catch the ultrafine particles, so it is an ineffective process to recover molybdenum metal in the waste tailings, while OAF has some advantages to recover fine minerals. And the best result was obtained from transformer oil due to its appropriate length of carbon chain, kinematic viscosity and cyclical structure. The oil amount plays a very important role on average size of the particles, with the increase of transformer oil from 2.0 to 13.8 kg/t, d(50)(d) increases from 0.15 to 0.68 mm and d(50)(p) decreases from 9.06 to 2.05 mu m. This finding suggests the bigger the d(50)(a), the smaller the d(50)(p), and the higher the recovery of molybdenite. The appropriate conditions for recovering ultrafine molybdenite were determined as follows: dosage of frother: 0.5 kg/t, natural pH: 6.2, stirring time: 3 min, and stirring intensity:400-600 r/min. Lastly, the closed cycle test and industrial application in the producing scale of 500 t/d were carried out, and result shows 95% molybdenum was recovered with a satisfied grade of 22.62%. (C) 2012 Elsevier Ltd. All rights reserved.