The caking and adhesion of intermediate product on reactor surfaces during TiO2 production via the NaOH molten salt method are a serious problem. The consolidation of intermediate product can lead to low heat transfer efficiency and low titanium fractional conversion. Furthermore, frequent cleaning is generally required. An anti-caking method that can be applied during low-grade titanium slag decomposition in the NaOH system was studied. The method, which involves the two-step reaction of low-grade titanium slag with molten NaOH without the introduction of additives, can significantly reduce the extent of caking. The NaOH and low-grade titanium slag mixture was first reacted at 350 degrees C for 60 min. The temperature was then increased to 550 degrees C in 40 min. Finally, the mixture was reacted at 550 degrees C for 75 min. The effects of the reaction temperatures. NaOH-to-slag mass ratio and the reaction time on the titanium extraction were investigated. The Brunauer-Emmett-Teller (BET) surface area and apparent density were used to characterize the extent of caking. In the low grade titanium slag, silicate phase prior to pseudobrookite phase reacts with molten NaOH at 350 degrees C in the process of two-step molten reaction and formed sodium silicate. Microstructural and Fourier transform infrared (FT-IR) absorption results show that the firstly formed sodium silicate did not diffuse into the entire reaction system and powder-shaped intermediate product was formed. Approximately 97% of titanium in the titanium slag could be extracted under the optimal reaction conditions. In addition, the content of TiO2 obtained in the product reached 99.3%. (C) 2012 Elsevier B.V. All rights reserved.