Research on the process of improving the grade of high-iron red mud from the reductive Bayer process by the alkali hydrothermal and complexation dissolution method
The resource utilization of red mud is of crucial importance for the sustainable development of the alumina metallurgical industry,and it has also been a major challenge that has long constrained the progress of aluminum metallurgical processes.The breakthrough of the reductive Bayer process has dramatically improved the magnetic separation of iron from red mud and allowed the production of high-iron red mud,which has built the foundation for the co-metallurgy of Fe metal and alumina.However,there are harmful impurities such as Al,Si,and Ti in the high-iron red mud produced from the reductive Bayer process,which have adverse effects on iron smelting.What's more,Fe and Ti are highly isomorphism replaced.This makes it difficult to separate titanium from iron in red mud.This study used high-iron red mud as the raw material and characterized its physicochemical properties.The removal of Al and Si from the red mud by alkali leaching was studied based on the solubility of sodium aluminosilicate in an alkali solution.Under the optimized conditions,their removal was satisfactory;the Si content in the leached red mud was less than 0.l wt％,and the Al content was about 0.21wt％.The occurrence of the stubborn phases of calcium aluminosilicate and alumogoethit determines the leaching conditions for Al and Si.Using the principle of complexation dissolution of Ti,researched the complexation dissolving of titanium from the alkali-hydrothermal treated red mud.The results showed that the mixed system of H2O2,ammonia,and citric acid was capable of complexation dissolving amorphous metatitanic acid,and 21％titanium in the alkali-treated red mud can be complexation dissolved.However,after the alkaline leaching process,a significant portion of titanium in red mud was not yet in a favorable form for complexation dissolution.More future work on the regulation of titanium form and complexation medium is needed.
reductive Bayer processhigh-iron red mudco-metallurgy of iron and aluminaalkali dissolving of Al and Sicomplexation dissolution of Ti
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