| 摘要 |
The invention relates to processes for producing ferrates of alkali metals (mainly sodium), containing iron in oxidation level (VI), (V) and (IV)by solid phase reaction of activated iron compound (oxide or hydroxide) with peroxide of alkali metal at temperatures above 200°C. Activated oxide (hydroxide), e.g. FeO, is produced by maintaining a mixture of powder-like FeOand an activator compound at temperature above 70°C, the activator content in the mixture exceeds 1 wt.% and is a mixture of powders of sodium difluoride NaHF(potassium of ammonia) and hexafluorosilicate NaSiF, wherein the mass ratio of the difluoride of alkali metal and sodium hexafluorosilicate in the activator is within 1:3 - 3:1. Activated oxide FeOand sodium peroxide NaOare mixed in molar ratio 1:4 (mass ratio about 1:2) and the obtained mixture is subjected to tableting. The produced tablets are continuously sent to a conveyer belt moving through a slot furnace with a hot zone (synthesis zone) arranged in furnace middle. The hot zone has a permanent temperature between 210°C to 250°C and its length is from 1:7 to 1:10 of the total length. In moving along the belt tablets are surrounded by air atmosphere free from COand water air (oxygen, inert gas) during the time sufficient for reaction completion. For preventing sticking tablets to a metal band it is coated by a polymer film withstanding the synthesis temperature (e.g. the film is made from fluoroplast-4). At the furnace outlet ferrate tablets drop into a sealed container. |
