Process for the production of sodium dichromate

专利名称：Process for the production of sodium

dichromate

发明人：Norbert Lonhoff,Bernhard

Spreckelmeyer,Hans-Dieter Block,RainerWeber,Jost Halstenberg,Bernd Rosenow

申请号：US07/824682申请日：19920121公开号：US05250274A公开日：19931005

摘要：The invention relates to a process for the production of sodium dichromate andsodium dichromate solutions by oxidative roasting of chrome ores under alkalineconditions, leaching of the furnace clinker obtained with water or an aqueous chromate-containing solution, adjustment of the pH to from 7 to 9.5, removal of the insolubleconstituents by filtration, a sodium monochromate solution being obtained, conversion ofthe monochromate ions of this solution into dichromate ions by acidification andcrystallization of sodium dichromate by concentration of this solution, characterized inthat the acidification is carried out with carbon dioxide under pressure with removal ofsodium hydrogen carbonate, the remaining solution is then very largely freed fromsodium monochromate by cooling to a temperature below 10° C. and filtration, anymonochromate ions still present in the remaining solution are converted into dichromateions by addition of an acid and the sodium monochromate filtered off is added to thesodium monochromate solution before conversion with carbon dioxide into a sodiumdichromate solution.

申请人：BAYER AKTIENGESELLSCHAFT

代理机构：Sprung Horn Kramer & Woods

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