Fine powder classification by ferrofluid density separation
US3951784A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 1975 |
| Grant date | Apr 20, 1976 |
| Priority date | — |
| Expiry date | Jan 29, 1995 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB03C1/32
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A method of separating small diameter non-magnetic particles of different densities by using a low magnetic saturation ferrofluid and a high magnetic gradient to produce levitation by overcoming the magnetic attraction of the particles. Application of a constant gradient field of a level below the magnetic saturation level of the ferrofluid forms the ferrofluid into a density gradient column. Each non-magnetic particle levitates to the level inside the ferrofluid having the same apparent density as the particle. The ferrofluid contains magnetic particles with a mean effective core diameter less than about 50 angstroms and a stabilizing agent layer on the particle exceeding about 50 angstroms. Perfluorinated carriers and surfactants are preferred for their relatively high intrinsic density.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.