  A new generalization of the t-J model with a nearest-neigbor hopping is
formulated and solved exactly by the Bethe-ansatz method. The model describes
the dynamics of spin-S fermions with isotropic or anisotropic interactions. In
the case S=1 the magnetic interaction is biquadratic in the spin operators. In
contrast to the SU(N) generalization of the t-J model, studied previously in
the literature, the present model possesses beyond a massless excitation also a
massive one. The physical properties indicate the existence of Cooper-type
pairs with finite binding energy.
