Rhenania phosphate

Rhenania phosphate 3CaNaPO, Ca2SiO Insol. High... 

Rhenania Phosphate. Rhenania phosphate is another thermally produced phosphate fertilizer. It is made by calcining a... 

Potassium Phosphates.—Basic or neutral phosphates (Rhenania phosphates) may be made directly from rock phosphate by mixing it with potassium chloride, some form of carbon and soda, and heating to over 1000° C. in an electric furnace.2 One of these products has the composition Ca2KNaP208, with some silica. Such products may contain 23 to 31 per cent, of soluble phosphoric acid. Potassium superphosphate has been made by mixing potassium sulphate and calcium carbonate with concentrated phosphoric acid in a lead-lined vessel.3 The CaS04.2Ha0 is separated and the filter-pressed solution is evaporated to dryness by steam heat. The residue may be treated with more phosphoric acid and again evaporated. The reaction is expressed by the equation... 

Sinter phosphates Rhenania phosphates with a P2O5 content of ca. 29% are obtained by sintering apatite, silica and sodium carbonate or sodium hydroxide. Their annual production in the Federal Republic of Germany is over 300 10 t (corresponding to ca. 90 10- t/a P2O5). 

Rhenania phosphate is another thermally produced phosphate fertilizer. It is made by calcining a rriixture of phosphate rock, sodium carbonate, and silica in a rotary kiln at 1250 C [15]. Enough sodium carbonate is used to form the compound CaNaP04 and enough silica... 

The overall reaction in producing Rhenania phosphate is assumed to be ... 

Rhenania phosphate is made by sintering phosphate rock at 1200°C with soda ash and silica, cooling and then grinding. In this way the phosphate rock is opened up and made more suitable for application. Tetracalcium phosphate, Ca4P20g, can be formed as well as calcium sodium phosphates and calcium silicate. The main reaction has been represented as (12.12). 

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