Process for manufacturing ready-mixed setting alpha-calcium sulphate hemi-hydrate and kit for same

A process of manufacturing a stable product comprising α-calcium sulfate hemihydrate consisting essentially of the steps of:

• mixing calcium sulfate dihydrate, water and at least one first crystal modifier, to control particle morphology, to form a mixture, the at least one first crystal modifier selected from at least one member of the group consisting of maleic acid, succinic acid, lactic acid, citric acid, tartaric acid, monosodium gluconate, ethylene diamine tetra-acetic acid or sodium salt thereof, and aspartic acid;
• calcining the mixture in a reactor at conditions sufficient to form a calcined slurry comprising water and alpha-calcium sulfate hemihydrate;
• adding to the calcined slurry at least one second crystal modifier as a set preventer or set retarder, when the calcination is essentially complete and the slurry contains at least a majority of the water from the reactor, to form the stable product, the at least one second crystal modifier selected from at least one member of the group consisting of citric acid, tartaric acid, polyacrylic acid, aspartic acid;
• monosodium gluconate, tri-polyphosphate, gelatin, organic polyphosphonic compound, ethylene diamine tetra-acetic acid or sodium salt thereof, diethylene triamine penta-acetic acid, tetra-sodium pyrophosphate, and sodium polyacrylate,
• wherein the stable product is a ready-mixed slurry composition comprising the calcined slurry and the at least one second crystal modifier as the set preventer or set retarder, and
• packaging the stable product to produce packages of the stable ready mix slurry product,
• wherein there is an absence of drying before said adding to the calcined slurry at least one second crystal modifier,
• wherein there is an absence of filtering before said adding to the calcined slurry at least one second crystal modifier,
• wherein there is an absence of drying before said packaging, and
• wherein there is an absence of filtering before said packaging.