Three-dimensional simulations of a three-phase flow in conical-bottom draft-tube bubble columns were performed using a finite-volume flow simulation technique. Simulated gas volume fraction and column circulation times agree with the experimental observations of Pironti el al. (Chemical Engineering Journal, 60, 155-160). Furthermore, the simulations showed the same loss of column circulation as observed experimentally when the column was operated with the draft-tube in its highest position. The simulation code employed an unstructured grid method along with a multifield description of the multiphase flow dynamics. Modeled physical phenomena included momentum exchange and turbulence due to both sheer and slip among phases.