Preliminary Study on Potential of EAF Slag as Nutrients Source for Mangrove Seedling

摘要

Electric Arc Furnace (EAF) slag generated from steel making process mainly consist of calcium oxide (CaO), iron oxide (FeO), silicon oxide (SiO_2), manganese oxide (MnO), aluminium oxide (Al_2O_3) and magnesium oxide (MgO) in different phases. Since the elements are matching some of the nutrients or micro-nutrients that are needed in plant growth, this study was carried out with the purpose of finding the potential of EAF Slag as nutrients source for mangrove seedling in nursery centre. EAF slag taken from steel making plant during normal production process was crushed and analysed with XRF to obtain chemical composition result and XRD for phase analysis. ICP-OES elemental test was done on leachate from kinetic leaching experiment to assess the leaching trend for each elements form EAF slag in distilled water. Result obtained shows Ca and Si are the major elements that leached from EAF slag with uptrend line, and achieved about 25 mg/l for Ca and 7.5 mg/l for Si after 10 days in distilled water with L/S ratio as main affecting factor. Fe and Mn leaching will be enhanced by stirring at highest speed of 700 rpm. Both elements show uptrend with highest leaching at 0.27 mg/l for Fe and 0.14 mg/l for Mn at day 10, and this shows good potential of EAF slag as slow release element. Mg as an important element in chlorophyll shows uptrend leaching to about 1.5 mg/l at day 10, with L/S ratio as main influential factor. Potassium (K) and sodium (Na) leaching fluctuated below 0.50 mg/l for K and below 0.08 mg/l for Na. Al is the only element that achieved highest level in between day 3 to 7, and then drop gradually to day 10, at about 1.0 mg/l for sample with 700 rpm stirring speed. The results showed good potential for EAF slag to be used as slow release nutrients source for mangrove seedling. Further studies are currently underway to evaluate the effect of EAF slag in altering pH of the soil, as well as efficiency of EAF slag as fertilizer for mangrove plant by observing the growth rate of seedling planted in mangrove nursery site.