  The Heisenberg model in 3d is studied from a dual point of view. It is shown
that it can have vortex configurations, carrying a conserved charge(U(1)
symmetry). Vortices condens in the disordered phase. A disorder parameter
$\leftangle\mu\rightangle$ is defined dual to the magnetization $\leftangle\vec
n\rightangle$, which signals condensation of vortices, i.e. spontaneous
breaking of the dual U(1) symmetry. This study sheds light on the procedure
known as abelian projection in non abelian gauge theories.
