METHOD OF PREPARING MAGNETIC LIQUID Russian patent published in 2011 - IPC H01F1/28 C01G49/08 

FIELD: chemistry.

SUBSTANCE: method of preparing magnetic liquid involves dissolving starting iron-containing material in an inorganic acid, obtaining a solution which contains Fe²⁺ and Fe³⁺ salts, adding an alkaline solution to the obtained solution in order to deposit fine particles of magnetite, followed by stabilisation of the deposited fine particles of magnetite and peptisation of the stabilised magnetite particles in a dispersion medium. In the disclosed method, natural magnetite is first crushed in an inert medium to particle size 0.020-0.040 mm, and the fine particles of magnetite are stabilised with a mixture of synthetic fatty acids and oleic acid or naphthenic acids or a mixture of petroselinic and oleic acid. Also, the acids used to dissolve the starting iron-containing material can be sulphuric or orthophosphoric acid, and the fatty acids used are C₇-C₉, C₁₀-C₁₃ or C₁₄-C₁₆ fatty acids.

EFFECT: high stability of the magnetic liquid in gradient magnetic field, simple and cheap method.

3 cl, 5 ex