Molybdenum ore beneficiation is primarily achieved through the flotation method and involves the recovery of molybdenite, the main molybdenum mineral. Sometimes, to further improve the quality of molybdenum concentrates and remove impurities, additional chemical processing is done outside the beneficiation grounds. Molybdenite has a crystal structure consisting of hexagonal layered or plate-shaped structures, and the layers contain S-Mo-S structures with polar covalent bonds. The weak bonding between layers and even stronger covalent bonding within layers allows for easy splitting along the flaky or tabular output, leading to the natural floatability of chalcocite.
It has been observed that the dissociation of molybdenite crystals occurs in the S-Mo-S layer when the grinding fineness is appropriate, resulting in a small proportion of the S-Mo surface being hydrophilic. However, with increased grinding time, the ratio of the S-Mo surface increases and the floatability decreases, even with the addition of polarity, such as xanthate collector class, which may be beneficial to the recovery of molybdenite. To avoid excessive wear during production and ensure high recovery of molybdenum concentrate, it is necessary to adopt a multi-stage grinding sub-sorting process to ensure monomer dissociation.
Molybdenum mining and processing techniques have been continuously improved since the first mine was established at Climax near Leadville, Colorado in 1916. Currently, the principal molybdenum mines, both primary and by-product, are found along the Great Continental Divide of the Americas, in China, and in the CIS. Many of these mines are among the most productive in the world, with the largest capable of processing over 50,000 tonnes of ore per day. Mining and processing plants are operated with minimal emissions under strict environmental protection regulations.