Dry mineral processing by the gas-solid fluidized bed

Fluidized bed medium separation (FBMS) was carried out in order to separate ores by a dry method. The FBMS utilizes the floating and sinking of different-density objects in a gas-solid fluidized bed. Although the apparent density of the fluidized bed is the main factor for determining the floating and sinking of separating objects, it is also affected by the size and shape of separating objects, the fluidized bed dimensions, as well as the fluidization stability. In the present work, the distribution of apparent density was estimated by measuring the equilibrium height of spheres with various densities immersed in the fluidized bed. Silicastone and pyrophyllite were used as the ores for separation, the density of which differed by about 250 kg/m³. The apparent density of the fluidized bed was adjusted between the separating ores by mixing glass beads and steel shot which had about the same minimum fluidization velocity. For continuous separation, the FBMS was combined with devices that can continuously remove floating and sinking objects. As a result, a high separation efficiency of about 95% was attained for each ore although the ore recovery is dependent on the experimental conditions.