A novel approach for resource utilization of stainless steel pickling sludge via nickel–iron blast furnace molten slag
摘要
Stainless steel pickling sludge (SSPS) is a by-product of pickling and passivation treatment of stainless steel in the process of stainless steel production. A novel approach for the treatment of the SSPS using the high-temperature nickel–iron blast furnace molten slag (NBFS) was investigated. The results show that the flow temperature of the slag decreases with the increase in the proportion of SSPS. In a certain range, the flow temperature decreases by about 7 °C when the proportion of SSPS increases by 1%. The computational results from FactSage indicate that the addition of SSPS leads to a reduction in MgO content and an increase in CaO and CaSO4 contents, which are the reasons for the decrease in the flow temperature. Mortar blocks were prepared by mixing the slag powder prepared by water-quenched slag drying ball milling with 425 Portland cement in a certain proportion. As the proportion of SSPS increased from 0 to 5%, the 7-day strength of mortar blocks increased from 22.32 to 26.98 MPa, and the 28-day strength increased from 37.28 to 41.43 MPa. The 28-day activity index is above 75%, and its activity index meets the requirements of S75 ground granulated blast furnace slag. The industrial application program in the nickel–iron blast furnace with a volume of 550 m3 was also put forward, which provides a new way for realizing the resource utilization of SSPS.