In a skillet over medium heat, brown chorizo. Add salsa and simmer for 5 minutes. Lay pizza crusts on pizza pan or baking sheet covered in foil. Spread refried black beans over top of pizza crusts. Evenly spread chorizo mixture over beans. Cover in cheese and bake for 10 to 12 minutes. Remove from oven and top with lettuce, followed by tomatoes, and then tortilla chips. Place ranch dressing in a resealable plastic bag and snip corner off of bag; pipe over pizzas. Serve hot.