With this work we study the microscopic dynamics of liquid aluminium at T=973K and develop the theoretical model which satisfies all corresponding sum rules. The investigation covers the inelastic features as well as the crossover of our theory into the hydrodynamical and the free-particle regimes. A comparison between our results with those following from generalized hydrodynamical approaches is also presented. The main results describe (i) the inherent relation of the high-frequency collective excitations observed in experimental spectra of dynamic structure factor $S(k,\omega)$ with the two-, three- and four-particle correlations, and (ii) the pronounced influence of the screening of the electron gas for the high-frequency collective dynamics.