Spheres prepared by air-quenching of the blast furnace titanium slag melts and its secondary thermal treatment

Considerable blast furnace titanium slags (BFTS) are generated during the V-Ti magnetite smelting process, which had been low-value utilized as aggregates in construction and building areas. In this study, an air-quenching process was proposed to treat BFTS melts directly to obtain spherical BFTS particles. The obtained BFTS spheres (ATS) were sieved into 16–30 mesh (S1), 40–70 mesh (S2) and 70–140 mesh (S3). The morphological parameters (including roundness and sphericity), mineral and chemical compositions of all ATSs were determined by image analysis, scanning emission microscopes (SEM), X-ray fluorescence spectrometry (XRF), and X-ray diffraction (XRD), etc. While their properties were also measured experimentally. It is concluded that all ATSs have a smooth spherical shape with relatively higher sphericity and roundness. ATSs exhibit a better close packing and lower water absorptions as compared with raw BFTS. ATS S3 showed relatively lower acid solubility and excellent crushing resistance as compared with those of ATS S1 and ATS S2. A secondary thermal treatment method is proposed to further improve the acid solubility and crushing resistance of ATSs. Glass phases in ATSs are transformed into crystalline phases, thus improved the acid solubility and crushing resistance of the ATS samples, excluding the crushing resistance of ATS S3. It is expected that the preparation of ATS through air-quenching and the consequent secondary thermal treatment was one of the most proper way in the treatment and high-value utilization of BFTS. And the obtained ATS can be used as a special and functional high-performance aggregate/filler in the construction field or others.