METHOD OF PREPARING MAGNETIC LIQUID Russian patent published in 2010 - IPC H01F1/44 C01G49/08 C09G1/04 

FIELD: physics.

SUBSTANCE: method of preparing magnetic liquid involves formation of a suspension of magnetite nanoparticles, coating the surface of magnetite nanoparticles with an adsorbed layer of oleinic acid as a stabilising substance. The suspension of magnetite nanoparticles is then heated with the adsorbed layer of stabilising substance. A fraction containing the stabilised magnetite particles is separated from the suspension in kerosene as carrier liquid. The source of bi- or trivalent iron for obtaining the suspension of magnetite nanoparticles used is natural magnetite - wastes from Olenogorsk mining and concentration complex having the following chemical composition: Fe_total=65.6%, FeO=26.7%, Fe₂O₃=63.4, MnO_max=0.11%, CaO_max=0.60%, MgO_max=0.8%, Al₂O_3max=0.40%, S_max= 0.15%, P₂O_5max=0.025%, SiO_2max=7.75%, Na₂O_max=0.063%, K₂O_max=0.063%. Natural magnetite is preliminarily dissolved in hydrochloric acid and re-precipitated with 28% ammonium hydroxide.

EFFECT: obtaining cheaper magnetic liquid and wider area of using the said liquid.

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