Scheelite is sometimes associated with sulfide minerals, molybdenite, barite, fluorite, and calcite. Gangue minerals are often quartz, etc. Separation of scheelite from these minerals is a common problem in scheelite flotation.

(1) Separation of scheelite from sulfide minerals: Generally, sulfide minerals are first floated with xanthate, and then scheelite is floated in the tailings with a fatty acid collector. If the sulfide minerals are not completely floated, a small amount of sulfide mineral inhibitor can be added to suppress them during scheelite flotation.

(2) Separation of scheelite from molybdenite: Molybdenite is first floated with kerosene, and then scheelite is floated with oleic acid.

(3) Separation of scheelite from barite is more difficult. Generally, scheelite and barite are first floated together in an acidic slurry using sodium hydroxide sulfate, and then water glass is added to the mixed concentrate in a strongly acidic medium (pH 2) for separation. Barite is then floated out using hydrocarbon sulfates, and the product in the tank is scheelite.

(4) Separation of scheelite from fluorite and calcite can be achieved using either the ambient temperature stirring method or the concentrated slurry high-temperature stirring method.

The ambient temperature stirring method involves concentrating the scheelite rough concentrate containing fluorite and calcite, adding water glass (10–20 kg/t), and stirring at room temperature for 14–16 hours. Then, the slurry is diluted for flotation, where fluorite and calcite are suppressed, while scheelite still floats. This method is rarely used due to the long stirring time.

The concentrated slurry high-temperature stirring method is also known as the “Petrov process.” The slurry is first concentrated to a solid content of 60%–70%, water glass is added, and the temperature is raised to 80°C and stirred for 30–60 minutes. Then, water is added, and flotation is performed at room temperature. The desorption and detachment of the collector film on the surface of calcite and fluorite are suppressed, while scheelite still floats. (5) For the separation of scheelite from silicate minerals such as quartz, water glass can be used to suppress quartz and silicate minerals, and oleic acid can be used to float scheelite.