Primary traffic on the railway has always been mineral, first with nitrate (an essential ingredient of explosives prior to World War I) and as of 2020 copper being very important. Sulphuric acid is transported uphill and copper comes down.
The primary transportation of minerals on the railway includes nitrate (an essential component of explosives before World War I) and, as of 2020, copper, which has become crucial. Sulphuric acid is transported uphill, whereas copper flows downhill.