Process for making abrasion-resistant sodium tripolyphosphate
AssigneeHoechst Aktiengesellschaft
InventorsHans Haas, Werner Kowalski
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Abstract
The disclosure relates to a process for making granular sodium tripolyphosphate of high abrasion resistance. To this end, the disclosure provides for sodium orthophosphate to be subjected to a one-stage spray-drying operation inside a heated spray tower by means of a nozzle with condensation of the orthophosphate. More particularly the orthophosphate is sprayed jointly with a solution of a high molecular weight phosphate of sodium, potassium or ammonium.
Claims8
A process for making granular sodium tripolyphosphate of high abrasion resistance which comprises:
- spray-drying a sodium orthophosphate solution or suspension containing Na.sub.2 O and P.sub.2 O.sub.5 in essentially the molar ratio required for the sodium tripolyphosphate in a one-stage spray-drying operation by means of a nozzle inside a heated spray tower with the resultant formation of the tripolyphosphate, the orthophosphate solution or suspension being sprayed jointly with a solution of a high molecular weight phosphate of sodium, potassium or ammonium containing between 60 and 73 weight % P.sub.2 O.sub.5, the proportion of the said solution being 0.005 to 5 weight %, calculated as solid substance and based on the P.sub.2 O.sub.5 -content of the orthophosphate solution or suspension.
A process for making abrasion-resistant, granular, substantially anhydrous sodium tripolyphosphate which consists essentially of:
- mixing a sodium orthophosphate solution or suspension containing Na.sub.2 O and P.sub.2 O.sub.5 in essentially the molar ratio required for the sodium tripolyphosphate with a solution of a high molecular weight phosphate of sodium, potassium or ammonium containing between 60 and 73 weight % P.sub.2 O.sub.5, the proportion of the said solution being 0.005 to 5 weight %, calculated as solid substance and based on the P.sub.2 O.sub.5 -content of the orthophosphate solution or suspension;
- spray-drying the resulting mixture in a one-stage spray-drying operation by means of a nozzle inside a heated spray tower;
- recovering from the spray tower the abrasion-resistant, granular, substantially anhydrous sodium tripolyphosphate which results from the one-stage spray-drying operation.
Dependencies are inferred from the claim text.