The invention discloses a method of preparing
sodium dichromate, comprising the steps of (1), subjecting
chromite and alkali solution to liquid oxidation, subjecting
slurry to
solid-liquid separation after reacting to obtain
liquid phase A and
solid phase B; (2), washing the
solid phase B with circulatory alkali liquid, subjecting post-washing
slurry to solid-liquid separation to obtain
liquid phase C and solid phase D; (3),
crystal-dissolving the solid phase D with
sodium chromate
crystal with water and iron residue washing liquid, carrying out solid-liquid separation to obtain
crystal-dissolved liquid and iron residue, washing the iron residue with water, and returning the washing liquid to crystal
dissolution; (4), preparing circulatory alkali liquid with the
liquid phase C and crystal-dissolved liquid, adding an acid solution to the remaining crystal-dissolved liquid to adjust pH, and carrying out aluminum-
silicon removal, acidifying, crystallizing and separating to obtain
sodium dichromate and
sodium sulfate; preparing. The process of the invention is simple, the flow is short, and the method is highly operable, low in cost and free of
wastewater and is an effective way of
chromium salt industry to make recycle use and reduce
pollution.