Selective separation of fine particles by a new flotation approach

Fine particles often create problems in flotation applications. In this article a new laboratory flotation system for the selective separation of small particles was designed and tested. The device contains an active counter current sedimentation that should prevent entrainment of the fine hydrophilic particles. The cell was used to selectively float fine particles in the size range 2-25 mum. To create small bubbles dissolved air was used. The study is linked to the problems that fine particles cause by remediation of soils and sediments. Therefore, small silica and small-oxidized carbon black (MT-OX) particles were used as model system. Three different frothers, sodium dodecylsulfate (SDS), Aerofroth, and Montanol were applied to obtain a stable froth. The results showed that the equipment works excellent to separate the fine MT-OX particles from the small silica particles. Especially with Aerofroth as frother, the Grade of the flotation experiments was extremely high (98.1%). The MT-OX Recovery was best with SDS (74.6%). The new flotation design provides a promising method for the remediation of contaminated sediments and soils. Next to that it offers an interesting option to separate fine particles and powders in other industrial applications