FeSO4 center dot H2O from TiO2 prodn. was used as a filler for prepn. of multicomponent mineral fertilizers in a lab. drum granulator (vol. 20 L, granulation temp. 60-70 degrees C). The fertilizers were studied for the content of mineral components, phase compn., crit. relative humidity and mech. properties. The replacement of magnesite with FeSO4 center dot H2O in the fertilizers resulted in a decrease in the citrates-soL and H2O center dot sol.P2O5 content but did not affect the quality of the fertilizers produced.