Method for making ultrafine calcium sulfate dihydrate crystals

Claim 1

IN A PROCESS FOR MANUFACTURE OF A QUICK SETTING WATER SLURRY OF CALCINED GUPSUM WHEREIN AN AQUEOUS CALCIUM SULATE HEMIHYDRATE SLURRY IS MIXED WITH ACCELERATORY, THE IMPROVEMENT WHICH COMPRISES ADDING AS ACCELERATORY FROM ABOUT 1/10 TO ABOUT 3% SOLIDS BASIS OF AN AQUEOUS SUSPENSION OF ULTRAFINE CALCIUM SULFATE DIHYDRATE CRYSTALS PREPARED BY THE METHOD COMPRISING: (A) CONTINUOUSLY FORMING A SUSPENSION OF CALCUIN SULFATE HEMIHYDRATE IN ABOUT 20 TO ABOUT 80 PARTS OF WATER PER PART OF HEMIHYDRATE; (B) CONTINUOUSLY FEEDING SAID SUSPENSION INTO A CHAMBER SUBSTANTIALLY FILLED WITH MOVABLE ELEMENTS, SAID SUSPENSION SUBSTANTIALLY FILLING THE VOID SPACES BETWEEN SAID ELEMENTS; (C) EFFECTING RELATIVE MOVEMENTS OF SAID ELEMENTS; (D) PROGRESSIVELY ADVANCING SAID SUSPENSION THROUGH SAID CHAMBER IN A TORTUOUS PATH WHILE SUBDIVIDING AND IMPACTING THE SAME BY MEANS OF SAID MOVEMENT OF SAID ELEMENTS; AND (E) CONTINUOUSLY WITHDRAWNG THE THUS FORMED AQUEOUS SUSPENSION OF ULTRAFINE CALCIUM SULFATE DIHYDRATE CRYSTALS.