METHOD OF PREPARING MAGNETIC LIQUID Russian patent published in 2010 - IPC H01F1/28 C01G49/08 C02F9/04 C02F1/72 

FIELD: physics.

SUBSTANCE: invention relates to preparation of magnetic liquids which are colloidal solutions containing fine particles of ferro- and ferrimagnetic materials stabilised by fatty acids for use when separating nonmagnetic materials according to density in control and measuring devices, in medicine etc. The method of preparing magnetic liquid involves partial oxidation of an iron (II) solution, precipitation of fine magnetite particles using an alkaline solution, separation of the mother solution and stabilisation of the magnetite particles. The iron (II) solution is partially oxidised using hydrogen peroxide taken in amount of 0.5 mol H₂O₂/mol of iron (II). Before or after partial oxidation of the iron (II) solution, sulphuric acid is added in amount of up to 0.33 mol/mol FeSO₄. After stabilisation of magnetite particles and their peptisation in a dispersion medium to obtain an emulsion, magnetic liquid is removed. CaO is added to the mother solution while stirring. After removal of the formed CaSO₄ precipitate, the mother solution is mixed with a new portion of partially oxidised iron (II) solution to obtain an additional amount of magnetic liquid.

EFFECT: method provides wasteless and cheaper technology of preparing magnetic liquid due to additional material and without reducing stability of the obtained magnetic liquid.

4 cl, 4 ex