Method for synthesizing ferrum-aluminium spinelle

Abstract

The invention relates to a synthesis method of hercynite and has the technical proposal that aluminium compound and iron compound are mixed according to the mol ratio of Al ion to Fe ion of two to one, added with TiO2 fine powder of 1-20wt percent of the mixture obtained from the mixing of the aluminium compound and the iron compound and 1-6wt percent of binding agent to be mixed for 5 to 180 minutes for formation and then dried for 20 to 30 hours under the temperature of 90 to 120 DEG C and warmed up to 1100 to 1700DEG C with a temperature rising speed of 0.5 to 10 DEG C / min in the atmosphere of nitrogen to be kept warm for 5 to 600 minutes and next naturally cooled so as to obtain the hercynite. The invention is characterized by simple technology, low reaction temperature, low cost of raw materials and no environmental pollution; due to the low oxygen content in the atmosphere of the nitrogen, Fe elements exist in the form of Fe<2+> and all aluminium and iron are transformed to FeAl2O4 under the firing temperature; in addition, as the TiO2 is introduced, Ti<4+> can easily enter into crystal lattice of the FeAl2O4 to produce oxygen-iron vacancy concentration and ferric-ion vacancy concentration so as to promote the sintering with apparent porosity less than or equal to 2 percent after sintering.

Description

technical field [0001] The invention belongs to the technical field of refractory materials. In particular, it relates to a method for synthesizing iron-aluminum spinel. Background technique [0002] The traditional alkaline material magnesia-chromium bricks used in the firing zone of cement kiln has excellent high temperature resistance and corrosion resistance. It is very large, which limits the application of magnesia-chrome bricks. With the enhancement of people's awareness of environmental protection, it is imperative to develop low-chromium or chromium-free basic bricks for cement kilns. For chromium-free basic bricks, if a stable kiln skin can be formed on the hot surface of the furnace lining, the life of the furnace lining can be significantly improved. The French Refa Group (RHI or Refratechnik) found that the introduction of iron-aluminum spinel into chromium-free basic bricks can significantly improve the adhesion of the kiln skin. The product has high refracto...

AI Technical Summary

Problems solved by technology

[0003] Iron-aluminum spinel (FeO.Al 2 o 3 ) exists very rarely in nature, and the iron-aluminum spinel is generally synthesized by electrofusion, such as Al 2 o 3 and Fe as raw materials (Journal of Magnetism and Magnetic Materials, 2003, 264: 264-274), but the reaction process is difficult to control, and the reaction is not sufficient

The method of mechanochemical synthesis of iron-aluminum spinel is to use planetary mill to combine Al and Fe 3 o 4 Grinding for a certain period of time, and then reacting and synthesizing in an argon atmosphere at 1200°C (Materials Chemistry and Physics, 2002, 76: 104-109), which adopts a two-step treatment method, the process is complicated, and the thermite reaction is easy to occur, resulting in the final product difficult to control

Liu Huiming et al. (Refractory Materials, 2003, 37(6): 333-335) synthesized ferroaluminum spinel by reaction sintering method using special-grade bauxite, iron scale and graphite as raw materials. However, the synthesis temperature was higher than 1550°C and the purity Low, if there is about 10% Fe remaining in the final phase 2 o 3 and Al 2 o 3 , leading to an increase in production costs and a decline in grade

"A Synthetic Ferroaluminum Spinel and Its Preparation Method" CN200510019267.6) Synthesizes Ferroaluminum spinel by embedding carbon, but the process is labor intensive, the atmosphere is difficult to control, and it pollutes the environment more