Torsion classes generated by silting modules

We study the classes of modules which are generated by a silting module. In the case of either hereditary or perfect rings it is proved that these are exactly the torsion $\mathcal{T}$ such that the regular module has a special $\mathcal{T}$-preenvelope. In particular every torsion enveloping class in $\text{Mod-}R$ are of the form $\mathrm{G}\mathrm{e}\mathrm{n}(T)$ for a minimal silting module $T$. For the dual case we obtain for general rings that the covering torsion-free classes of modules are exactly the classes of the form $\mathrm{C}\mathrm{o}\mathrm{g}\mathrm{e}\mathrm{n}(T)$, where $T$ is a cosilting module.