Effect of Mechanically Ground Ferrous Extraction Tailing of Nickel Slag on the Properties of Cement-Based Materials

In order to realize the full resource utilization of ferronickel slag (FNS) in cement-based materials, this paper studied the influences of mechanical grinding activation on the physical and chemical properties and reactivity of ferrous extraction tailing of nickel slag (FETNS). Four grinding processes of 5, 10, 20 and 30 min were set up to evaluate the influence of grinding process on the physical and chemical properties of FETNS with the aid of BET, XRD, Rietveld analysis and particle size distribution. The cement-FETNS composite cementitious material was prepared by replacing cement with 0%, 10%, 15%, 20%, 25% and 30% FETNS. The influence of FETNS fineness and content on the properties of composite cementitious system were characterized by mechanical properties, reaction products, early hydration process and pore structure characteristics. The results show that the grinding process can effectively improve the pozzolanic activity of FETNS. The compressive strength of FETNS-M-30 paste is higher than that of FETNS-M-5 paste in the early and late stages, and the later strength is higher than that of the baseline group when the content of FETNS-M-30 is 10%-25%. The pozzolanic activity of FETNS-M-30 powder is significantly improved and higher than that of FETNS-M-5 powder. Under the same content, the Ca/Si ratio of C-S-H gel in FETNS-M-30 paste is small, and the degree of silicate polymerization is higher. When the FETNS-M-30 content is 10%, the proportions of favorable pores d<50 nm (harmless pores and less-harmful pores) of FETNS-M-5 paste and FETNS-M-30 paste is 95.3% and 95.4%, respectively, indicating a denser pore structure of the FETNS-M-30 paste.