Study On Transformation Behavior Of Iron Minerals In Process Of Treating High-iron Bauxite By Starch Hydrothermal Method

The comprehensive utilization of aluminum and iron in high-iron bauxite is the focus of today's attention.This paper breaks through the traditional step-by-step treatment of high-iron bauxite mode,using starch as a reducing agent to reduce iron oxide while hydrothermally dissolving in a diaspore.Achieve the purpose of simultaneous separation and recovery of aluminum and iron.Thermodynamic calculation and experimental study of the p Hase transformation of iron oxide in an alkaline reduction system.By means of infrared spectroscopy,XRD,SEM-EDS,laser particle size analysis,magnetic separation and other analytical characterization methods,the transformation law of mineral p Hase in the dissolution process of diaspore and iron compounds in high-iron bauxite is studied.Research indicates:?1?The circulating mother liquor??k is 3.12,Nk is 210.27 g/L?as the dissolution system.When the dissolution temperature is 260 °C,the dissolution time is 60 min,the ratio of lime dosage to dry ore is 7%,one water The highest dissolution rate of diaspite is about 98.0%.When the temperature is 240 ° C,the reduction time is 40 min,the ratio of starch dosage to dry ore is 1:10,and the highest reduction rate of hematite is 97.5%.?2?In the process of high-pressure hydrothermal separation and recovery of aluminum-iron minerals in high-iron bauxite,the dissolution of Al2O3 and the reduction process of hematite promote each other.The increase of alkali concentration can increase the degradation rate of starch organic matter,and at the same time can improve the solubility of high-iron bauxite in alkaline solution,and finally reduce the reduction temperature of hematite.The calculation results show that for every 19 g/L increase in alkali concentration,the temperature required for reduction is reduced by about 7 °C.?3?Under the alkaline reduction system,the directed conversion of Fe₂O₃ to Fe3O4 is performed in three steps.Fe₂O₃ is first dissolved in an alkaline aqueous solution to form intermediate Fe O2-.Fe O2-is further converted into Fe?OH?4-in an alkaline solution.The strong reduction system formed by the degradation of starch under alkaline hydrothermal conditions converts the Fe?OH?4-is reduced to Fe?OH?3-,and Fe2+ and Fe3+ react further in the lye to form Fe?Fe O2?2.?4?The whole process of hydrothermal reduction of hematite by starch is controlled by chemical reaction and internal diffusion mixing,and the apparent activation energy of the reaction is 55.724 k J·mol-1.?5?The optimal magnetic field strength for the magnetic bath magnetic recovery of the product is 0.08 T.As the magnetic field strength increases,the magnetization coefficient decreases,which will cause the magnetic separation interval to expand.High magnetic fields are easy to form magnetic particle clusters due to magnetic flocculation,and the formation of such flocs is not selective,and it will coat some magnetically weak minerals to the magnetic poles.Although the magnetic separation rate has increased,its iron grade will decrease.