Stauffer Chemical Company

Helmut W Majewski

Fawzy G Sherif

Francis A Via

Julian E Blanch

Kon S Chen

Dicalcium phosphate dihydrate compositions having improved monofluorophosphate compatibility are prepared by adding pyrophosphoric acid to the dicalcium phosphate dihydrate reactor and terminating the reaction by which the dicalcium phosphate dihydrate is formed at a pH ranging from above about 2.2 to below about 4.9.

Dicalcium phosphate dihydrate having improved monofluorophosphate

Dicalcium phosphate dihydrate compositions having improved monofluorophosphate compatibility are prepared by reacting a lime slurry with phosphoric acid to form a monocalcium phosphate solution, and then further reacting the monocalcium phosphate solution with additional lime slurry to a pH in the range of from above about 2.2 to below about 5.5.

The mercury content of electrolysis cell brine sludge is reduced by sequentially: (1) acidifying the sludge to a pH below 2.5 and (2) leaching the sludge with aqueous hypochlorite solvent. The mercury content removed from the sludge may optionally be isolated from the solvent and reused as mercury cathode for brine electrolysis.

Process for removing mercury from brine sludges

The heavy metal content of sludge waste is fixed in a cementitious solid product by mixing the waste sludge with fixing ingredients comprising vermiculite and cement.

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Nyack, NY, United States of America

Helmut W Majewski