In a large dutch oven, melt the butter over moderately high heat. Add the pork and cook, stirring to break up the meat, until lightly browned and cooked through, about 5 minutes. Add the celery, onions, bell peppers, garlic, thyme, bay leaves, ground pepper and crushed red pepper. Reduce the heat to moderately low and cook, stirring occasionally, until the vegetables are tender, about 12 minutes. Add the rice and cook, stirring occasionally, for 5 minutes longer.