## 5 Conclusions and Future Work
This method differed from the previous one in terms of reactant addition, while adding also a timeframe to achieve the pH target (\(9\pm 2\) in 30 min), to mimic the industrial neutralization process. Only the slags that were successful in the previous experiments were used for the second one, while lime samples were once again used as a reference. The lime quantity needed to successfully raise the pH of the wastewaters did not change compared to the stepwise dosing method, while the quantities of slag were not sufficient to reach the target within the time limit; thus, more material was needed. This has been attributed to a slower kinetics for the reaction with slag compared to the one with lime. With this method, around eight times the amount of slag was needed compared to lime. * The chemical composition of the clean waters produced after single-step dosing trials, obtained with the OTK slag sample, was measured with ICP-MS analysis and compared to the original composition of the OTK wastewaters, also measured with the same method. The concentrations of six elements (Cr, Ni, Mo, F, Fe, and Zn) were measured and compared. The same procedure was used for clean waters produced with lime single-step dosing trials, as a reference. The slag sample proved capable of purifying the wastewaters to levels comparable to lime, and both the reactants managed to absorb the tested elements, reducing their concentrations in the waters below the legally permitted threshold values. The results of the trials performed, despite applied at a laboratory scale, thus, far from the industrial case, provided solid evidence that the vision drafted has a strong practical counterpart. After seeing the results of these preliminary tests, it is believed that slag should be tested thoroughly, both from an applied point of view, by closing the gap between industrial and laboratory conditions, and from a theoretical point of view analyzing the neutralization mechanism and what parameters can be modified to increase the neutralization efficiency. The two slags that could not reach the target pH value should not be excluded from the list of possible reactants, but more experiments with a finer and more homogenized PSD distribution across all the samples are needed to have a definite answer. Once single-step dosing trials are re-done, the samples used should be analyzed through XRD and SEM, to provide their complete characterization. Once the mineral content is characterized, it is possible to correlate it with the neutralization efficiency of the samples with a homogenous PSD. ICP-MS analysis on the slag samples was deemed unfit to the scope, because the mineral structure is not taken into account by this type of analysis, since it only measures the pure chemical composition. In particular, focusing only on the total amount of Ca present in the slag sample without considering how it is bound to other elements is not sufficient to draw any conclusions. This paper analyzes and presents experiments done via the route represented on the left-hand side of Figure 4, since it presents the first obstacle to achieving a zero-waste EAF process, even though more experiments need to be done on the second path, which revolves around the re-use of the saturated slag in the steelmaking process. First, it is important to understand their mineral composition; therefore, XRD and SEM are once again needed for a complete characterization. If the sediments will be used for high-temperature processes above their melting point, for instance as slag builders, then an ICP-MS may be sufficient. Saturated lime (since it is rich in CaF\({}_{2}\) after the neutralization) has already been used as a slag builder by OTK, and the authors believe similar applications can be applied for saturated slag as well, hence the reason why F removal was tested in the water purity trials.