  Equations of granular hydrostatics are used to compute the phase diagram of
the recently discovered van der Waals-like phase separation in a driven
granular gas. The model two-dimensional system consists of smooth hard disks in
a rectangular box, colliding inelastically with each other and driven by a
"thermal" wall at zero gravity. The spinodal line and the critical point of the
phase separation are determined. Close to the critical point the spinodal and
binodal (coexistence) lines are determined analytically. Effects of finite size
of the confining box in the direction parallel to the thermal wall are
investigated. These include suppression of the phase separation by heat
conduction in the lateral direction and a change from supercritical to
subcritical bifurcation.
