Leaching Characteristics of Iron and Manganese from Steel Slag with Repetitive Replenishment of Leachate

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Leaching Characteristics of Iron and Manganese from Steel Slag with Repetitive Replenishment of Leachate

Han, Longxi / Chen, Bo / Liu, Tiantian / Choi, Yongju

Abstract Steel slag reuse as a construction material is an attractive solution for the management of the industrial byproduct. However, concern exists on the release of steel slag constituents when a massive amount of the material is reused in the field. This study is aimed to improve the understanding on the leaching characteristics of iron and manganese, two heavy metals that are present in steel slag at relatively high contents. Concentrations of iron and manganese in the batch leaching experiment readily reach close to equilibrium within 1 hour. Batch leaching experiments conducted with exchange of the leaching solution at 1 hour intervals show that the leaching occurs consistently with relatively constant concentration up to 50 events of exchange. The leaching is a strong function of salinity showing factors of 11.6 and 3.8 increase in iron and manganese leachate concentrations, respectively. Despite the wide size ranges (<0.5 to >25 mm) tested, effect of slag grain size is less pronounced compared to the salinity effect. The average concentration in the leachate for 50 leaching events is sub-mg L−1 level for iron at most and an order of magnitude lower for manganese than the value for iron. These results show that steel slag is an almost permanent but a very low-level source of iron and manganese when reused in the environment.