Dehydration behaviour of a natural gypsum and a phosphogypsum during milling

The paper describes an investigation into the dehydration behaviour of a na tural and a phosphogypsum under isothermal conditions. The purpose of the w ork was to assess whether there is a difference in the dehydration behaviou r and what effects it could possibly have in practical applications in the cement industry. It was found that there is a significant difference in the amounts of moisture loss from the two materials under the same temperature conditions as well as their respective surface areas after dehydration. Th e results of the investigation indicate that great care should be exercised under production conditions when changing from the use of a natural gypsum as set retarder for cement to using a phosphogypsum. (C) 1999 Elsevier Sci ence B.V. All rights reserved.