Abstract:
The steel industry in Brazil generated in 2019 about 5,0 Mton of slag from the LD/BOF process. Even though this slag has been utilized on civil engineering projects there are still several restrictions on its use, mainly due to the volumetric expansion caused by the free CaO. Studies on curing processes using water have shown effectivity on the reduction of the negative effects caused by free CaO. This work aimed to investigate the free CaO passivation reactions and the pH variation of the residual water generated for the humectation process. In such way, using samples from a steel manufacturer, experiments were appropriately planned where two slag stacks were being prepared for the aqueous solutions treatment during the period of 100 days. The techniques used for monitoring the calcium compounds were the chemical procedure using ethylene glycol, Thermogravimetry-TG and ICP-OES. The results showed a decrease of the free lime content from 11,67% to 0,36% along the 100 days and the pH reduction for the residual water generated during the humectation process, from 12,57 to 10,65, in the same period of 100 days. Finally, using a databank for “in situ” slag treatment, was possible an useful comparison with the results obtained.