Moisture content is a vital factor in assessing iron ore operations. All iron ore products contain between 1.5% and 10% moisture content by weight, so any comparison of production tonnages and prices requires appropriate adjustment. Moisture also affects processing circuit design, transport costs and materials handling of fine-grained products, where cost and customer requirements must be balanced against safety and environmental considerations.
The following table, extracted from 33 published specifications worldwide for various iron ore concentrates and fines, indicates the range of moisture content. Moisture content for lump ore is typically one to three percentage points lower than fines.
Moisture Levels in Iron Ore Products
* Number of individual products with this moisture specification
Iron ore absorbs moisture from groundwater, process water, rainwater and from water added for dust control. Mining above the water table in an arid environment typically results in a moisture content of 0.5% to 3%. In regions of high rainfall, such as in India and Brazil, the moisture content is variable and seasonal.