  The analysis of hard X-ray INTEGRAL observations (2003-2008) of
superaccreting galactic microquasar SS433 at precessional phases of the source
with the maximum disk opening angle is carried out. It is found that the shape
and width of the primary X-ray eclipse is strongly variable suggesting
additional absorption in dense stellar wind and gas outflows from the optical
A7I-component and the wind-wind collision region. The independence of the
observed hard X-ray spectrum on the accretion disk precessional phase suggests
that hard X-ray emission (20-100 keV) is formed in an extended, hot,
quasi-isothermal corona, probably heated by interaction of relativistic jet
with inhomogeneous wind outflow from the precessing supercritical accretion
disk. A joint modeling of X-ray eclipsing and precessional hard X-ray
variability of SS433 revealed by INTEGRAL by a geometrical model suggests the
binary mass ratio $q=m_x/m_v\simeq 0.25\div 0.5$. The absolute minimum of joint
orbital and precessional $\chi^2$ residuals is reached at $q\simeq 0.3$. The
found binary mass ratio range allows us to explain the substantial precessional
variability of the minimum brightness at the middle of the primary optical
eclipse. For the mass function of the optical star $f_v=0.268 M_\odot$ as
derived from Hillwig & Gies data, the obtained value of $q\simeq 0.3$ yields
the masses of the components $m_x\simeq 5.3 M_\odot$, $m_v\simeq 17.7 M_\odot$,
confirming the black hole nature of the compact object in SS433.
