The optimal pulp concentration for flotation depends on the ore properties and flotation conditions. The general rules are:
(1) For minerals with high density and coarse particle size, a thicker pulp is often used. Conversely, for minerals with low density and fine particle size, a thinner pulp is used.
(2) Thicker pulps are used in roughing and scavenging operations to ensure higher recovery rates and save reagents.
(3) Thinner pulps are used in cleaning operations to improve grade. Separation of difficult-to-separate mixed concentrates should also use thinner pulps to ensure higher quality qualified concentrates.
The typical pulp concentrations for flotation of metallic minerals are: roughing, 25%–45%; cleaning, 10%–20%; scavenging, 20%–40%. The highest pulp concentration for roughing can reach 50%–55%, while the lowest pulp concentration for cleaning is 6%–8%.