Production of Maddrell salt
AssigneeHoechst Aktiengesellschaft
InventorsRenate Adrian, Raban VON Schenck, Klaus Somme, Hermann Weber
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Abstract
Pure Maddrell salt is produced by heating sodium phosphate to temperatures of 250.degree. to 420.degree. C. The sodium phospate used as starting material is sodium trimetaphosphate or a mixture of sodium trimetaphosphate with Maddrell salt, monosodium orthophosphate or disodium pyrophosphate, the mixture containing Na and P in a molar ratio of 1:1. Prior to heating the starting material, it is admixed with 0.5 to 5 weight% of orthophosphoric acid, polyphosphoric acid, phosphorus pentoxide or at least one salt of a volatile base forming polyphosphoric acid at the temperatures specified. The resulting mixture is calcined over the period necessary to transform the starting material to Maddrell salt.
Claims4
A process for making pure Maddrell salt by heating a sodium phosphate to temperatures of 250.degree. to 420.degree. C., which comprises using as the sodium phosphate starting material sodium trimetaphosphate, admixing the starting material, prior to heating it, with 0.5 to 5 weight % of orthophosphoric acid, polyphosphoric acid, phosphorus pentoxide or at least one salt of a volatile base forming polyphosphoric acid at the temperatures specified, and calcining the resulting mixture over the period necessary to transform the starting material to Maddrell salt.
Dependencies are inferred from the claim text.