Reduction mechanism of oxides

Generally, the reduction of oxides is a complex and multi-stage process including the phenomenon with multiple independent. Each process has its unique law. Because the law is complex, the overall image is a complex, often extremely difficult to be explained clearly. 

Under normal status, two fundamental questions for any reduction process need to be solved. 

Typically, the interaction between oxygen and metal oxide happens in gas, in 

A mechanism about reduction of oxide is the thermal-decomposition theory. 

The process is composed of two stages The decomposition of metal oxides (MeO), as well as oxidation of reductant by oxygen expelled from oxide. Advantages of this model are that it is simple and convenient for calculation. It continues to be widely used when calculating the heat consumption and heat balance of the reduction process. 

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Some hazardous metals such as chromium (Cr) and radioactive fission products such as technetium (Tc) exhibit exactly opposite solubility characteristics as compared to the metals discussed above. These metals in higher oxidation states, e.g., chromates (Cr ) and pertechnetate (Tc ), are more soluble than their counterparts, e.g., chromium and technetium oxide (Cr and Tc " "). Chromium is a hazardous metal and technetium ( Tc) is a radioactive isotope. As we shall see in Chapters 16 and 17, one way to reduce their dispersibility is to reduce their solubility in ground water and reduce them into their lower oxidation state, and then encapsulate them in the phosphate ceramic. Thus, the reduction approach is also useful in stabilization of hazardous metal oxides of high oxidation states. Because of these reasons, a good understanding of the reduction mechanism of oxides... 

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