Inside each mill are liners that are periodically changed. These liners both protect the mill shell from damage from the heavy tumbling rocks, and are shaped to assist in grinding the ore. The black iron ore rocks in the foreground of the photo to the left is not more than eight inches (20 cm) in size.
Part of the concentrate reclaim system. You will notice lots of conveyer belt tunnels that move the product from area to area. The smallest of these tunnels is approximately 12 feet (3½ m) tall by 12 feet (3½ m) across.