Heat the oil in a large skillet over medium heat. Add the rice and toast, stirring constantly, until it begins to smell nutty, about 2 minutes. Stir in the cumin, garlic powder, paprika, celery seeds, mace and 1 teaspoon pepper and cook, stirring occasionally, 2 minutes more. Stir in the broth, tomato sauce, corn and 1/2 teaspoon salt. Cover the skillet and simmer until the rice is cooked and has absorbed all the liquid, 30 to 40 minutes. Fluff with a fork before serving.