Corrosion of mild steel by coal and iron ore

The variation of corrosion rate of mild steel as a function of the quantity of moisture of coal and iron ore is investigated. Two types of black coal sieved to three different size fractions up to 2360 μm particle diameter and one type of iron ore of 600–1180 μm particle diameter were tested. A pronounced increase in corrosion rate was observed at a moisture content between 60% and 80% of the maximum water holding capacity for all samples. The corrosion rate was also observed to increase with decreasing particle size distribution. Parameters influencing the corrosion rate of coal and iron ore, as identified in this study and others, are discussed. Corrosion rates were measured inside a bulk carrier (ship) cargo hold that carried coal and iron ore cargo on successive voyages and are shown to be similar to those measured in the laboratory. The relevance of laboratory experiments using fine-particle samples for simulating the corrosion of steel exposed to coal and iron ore cargo is discussed.