Study On The Utilization Of PSTC Blast Furnace Slag And Synthesis Of Titanium Phosphate

With the dilution of the global ore resources and the deterioration of the habitat environment, most people pay more attention to make rational use of resources. Slag of blast furnace discarded on the bank of the Jingsha river by Panzhihua Steel and Iron Cor (PSTC) has been threatened the security of the river system. Furthermore, the unhandled slag contains lots of useful elements, such as titanium, aluminum and magnesium, which would be kinds of resources to be exploited. Based on yielding 4 million tons' iron of PSTC every year, the output of slag of blast furnace will be over 3.2 million tons per year, in which the component TiO₂ reaches to 900 kt/y. Inland scholars have made a lot of investigations in the field of the utilization of blast furnace slag for seeking methods to recover titanium and solve the environment pollution. Therefore, it is very important to find out a sustained development way with recycle economic viewpoint for preventing second pollution and recovering resources.Aiming at the utilization of Ti from the blast furnace slag, some experimental research has been made in this paper. First, the thermal process about the correlative reactions was analyzed. The results show that magnesium and aluminum theoretically can be thoroughly dissolved from the blast furnace slag by diluted sulfuric acid pretreatment on the blast furnace slag even if the ended concentration of sulfuric acid is 0.001mol/L, while the titanium basically could not be dissolved. Therefore it is theoretically indicated that the separation of the magnesium and aluminum from the slag with the least titanium loss by diluted sulfuric acid pretreatment is possible. Secondly, the leaching rate of titanium, magnesium and aluminum has been researched in different conditions such as concentration of H₂SO₄, ratio of slag to sulfuric acid, reaction residence time and temperature. Finally, the waste acid was used to digest the slag of blast furnace, so as to recover the waste acid and eliminate the impurities of the slag. The impurities-removed slag could be digested again so as to obtain purified titanium solution, which is beneficial for it to processing to put other titanium products. Besides, enrichment of magnesium in the solution was also studied in this paper.To explore the applied prospect of the slag of blast furnace, productive condition of the titanium phosphate was researched based on titanium sulfate solution obtained by second digestion process. It is suitable for the digestion solution with lower concentration to produce titanium phosphate. A series of experimental parameters were researched such as operation methods, reaction residence time, reaction temperature, ratio of raw materials and the calcine temperature. The product was examined by XRD and TGA, and it was discovered that the amorphous titanium phosphate turns to crystalloid titanium phosphate at a proper calcine temperature. The product is composed of several compounds, among of which the main component is TiP₂O₇.