  In general-mass variable-flavor-number (GM-VFN) scheme, the `heavy quark
mechanisms' of $B_c(B_c^*)$ meson hadroproduction via the sub-processes $g+c\to
B_c(B_c^*)+...$ and $g+\bar{b}\to B_c(B_c^*)+...$ are investigated. In the
scheme, possible double counting from these mechanisms and the `light
mechanisms' (the gluon-gluon fusion and quark-antiquark annihilation
mechanisms) is subtracted properly. The numerical results show that the
transverse momentum, $p_t$, distribution of the produced $B_c(B_c^*)$ from the
`intrinsic heavy quark mechanisms' (i.e. the heavy quark mechanisms in which
the double counting components have been subtracted accordingly) declines
faster with the increment of the $p_t$ than that from the `light mechanisms',
and only in small $p_t$ region ($p_t\lesssim 7.0$ GeV) the `intrinsic heavy
quark mechanisms' themselves may make remarkable contributions. The combined
contributions from the `intrinsic heavy quark mechanisms' and the `light
mechanisms' to the production are compared with that obtained by the most
calculations in literature, which in some sense are within the fixed flavor
number (FFN) scheme at leading order, and we find that the production by virtue
of the GM-VFN scheme is more or less the same as the one in literature, except
in the small $p_t$ region.
