Using polyvinyl alcohol to improve the deacidification performance of titanium white waste acid: Pilot tests

Titanium white waste acid (TWWA) is strongly acidic, and has high metatitanic acid (TiO(OH)₂) and n-hexane (C₆H₁₄) content. In this study, the effects of polyvinyl alcohol (PVA) on the modification of TWWA deacidification were evaluated via pilot testing. The results showed that the PVA solution can significantly improve the deacidification performance of TWWA. The TWWA specific resistance to filtration (SRF) decreased from the initial 2.42 × 10¹³ m/kg to 1.80 × 10¹² m/kg when 2% PVA solution was added at 25% (v/v). Furthermore, the amount of filter press-processed TWWA increased by 3.56 m³ relative to the control, and the moisture content of titanium white slag was only 42.02% after deacidification. In addition, distillation and phase separation was demonstrated to efficiently separate C₆H₁₄ and hydrochloric acid (HCl) from the mixed filtrate. Moreover, titanium white slag was converted into rutile after 60 min when the calcination temperature was 900 °C, with the titanium dioxide (TiO₂) purity of rutile reaching 91.83%. Accordingly, the TWWA recycling process proceeded as follows: PVA modification, solid-liquid separation, filtrate distillation and phase separation, and titanium white slag calcination. Our findings demonstrate that this process has unique practical application value.