Hyperbaric disk filter for high capacity dewatering of hematite and magnetite ore

G. Krammer*, Graz University of Technology; R. Raberger, Andritz AG, Austria

During beneficiation of iron ore the dewatering stage is particularly crucial prior the pelletizing plant where a product with 8 to 9 % residual moisture is optimal and thus targeted. For this large volume but rather low margin business, hyperbaric disk filter (HBF) technology is a superior choice to cope with this task since it combines high throughput of up to 500 tons per hour per unit on a small footprint and, due to the elevated pressure difference across the filter cake, fast filtration but also high product dryness are ensured. Moreover hyperbaric filters are particularly versatile in accepting varying feed conditions. Iron ore suspensions are prone to material abrasion. Due to recent design improvements abrasion attack is significantly reduced with lower operating costs and increased plant availability as a consequence.

Generally, the suspension properties together with the targeted performance, i.e., throughput, final product dryness and filtrate quality decide upon the principle applicability of a certain dewatering technology, e.g. HBF. Subsequently the suspension properties, particularly particle size and shape distributions, and the targeted performance are the basis of the actual design and operating conditions of the selected dewatering stage. In turn, the suspension properties are decided by the upstream beneficiation process and, of course, the intrinsic ore material.

A comparative study with different iron ores reveals that the cake formation performance is markedly influenced by the origin of the ore: Under approximately the same operating conditions and for similar particle size and shape distributions, zeta potentials, densities, Magnetite shows significantly better filtration performance compared with Hematite. Based upon Darcy’s law, the apparent filter media resistance and cake resistance are derived from experimental data. The apparent filter media resistance – a measure for the combined filter media and primary particle layer resistance – decreases with increasing Magnetite content; this trend is also found for the cake resistance parameter which is a measure for the cake permeability....

Session: L7 - Cake Filtration IV - Continuous Vacuum and Pressure Filters
Day: 12 October 2016
Time: 09:00 - 10:15 h