Kinetics of coagulation-fragmentation in a disperse system represented by different-scale fractions was studied using two-fraction model (Dolgonosov, B.M., Kolloidn. Zh., 2001, vol. 63, no. 1, p. 27). A model accounting originally only for the interaction between different fractions was extended, by introducing interactions between the particles of coarse fraction, to describe considerable deviations from the equilibrium. The threshold dependence of the coagulation efficiency on the sizes of colliding aggregates was introduced. According to this dependence, the efficiency vanishes when the aggregate sizes exceed a certain threshold value. The scheme of discretization of integro-differential equations of a model was proposed to numerically solve these equations. The results of calculations demonstrated the evolution of dispersed phase to the equilibrium, which is accompanied by (1) the transformation of initial bimodal spectrum into polymodal, (2) complex evolution of the latter with the change in the position and height of peaks and their merging, and, finally, (3) a return to bimodal spectrum with changed characteristics.