  In this paper, we consider the quantum MHD equations with both the viscosity
coefficient and the magnetic diffusion coefficient are depend on the density.
we prove the global existence of weak solutions and perform the lower planck
limit in a 3-dimensional torus for large initial data. The global existence is
shown by using Faedo-Galerkin method and weak compactness techniques for the
adiabatic exponent $\gamma>1$.
