SOLID-LIQUID SEPARATION
In many hydrometallurgical processes, one or more steps are required to separate liquids from solids. A variety of options are available, including screening, settling, filtration, and centrifuging, depending on the size and physical characteristics of the solids in the slurry. Solid-liquid separation steps can be quite costly, and Hazen's experience with commercial operations can help clients determine the most cost-effective option.
Thickeners and clarifiers are used extensively in many processes. Hazen can perform standard batch settling tests on slurries to determine preliminary unit thickener areas and thickener underflow densities. Flocculants are screened to determine the dose necessary to achieve rapid settling rates and clear thickener overflow liquors. For applications in which countercurrent decantation (CCD) is required to wash the solids, data can be generated from settling tests to size the CCD circuit.
Vacuum filtration and pressure filtration are used in many commercial operations. Standard filtration tests are used to provide preliminary filtration sizing information for either of these filtration options. When required, flocculants are tested to enhance filtration rates.