WO 2022/194499 A1

A process for the continuous preparation of alpha-calcium sulphate hemihydrate and a particulate gypsum

(22) 22.02.2022

(43) 22.09.2022

(57) The present application describes a process for the continuous production of alpha-calcium sulphate hemihydrate, the process comprising the steps of: providing particulate gypsum; providing water; mixing the particulate gypsum and the water to form a gypsum slurry; and maintaining said gypsum slurry under raised pressure and temperature to convert the particulate gypsum into alpha-calcium sulphate hemihydrate and provide an alpha-calcium sulphate hemihydrate slurry. Additionally, the particulate gypsum comprises a D 10 value greater than or equal to 2 µm, a D90 value smaller than or equal to 90 pm and a D50 value smaller than or equal to 25 µm. Particulate gypsum for use in the process is also provided.

(71) Saint-Gobain Placo, Tour Saint-Gobain, 12 Place de l’Iris, 92400 Courbevoie (FR)

x

Related articles:

Issue 2017-5 WO 2017/045519 A1

Method for producing wet-process phosphoric acid and ­byproducing alpha-hemihydrate gypsum and high-purity and high-whiteness alpha-hemihydrate gypsum

(22) 26.08.2016 (43) 23.03.2017 (57) Provided is a method for producing wet-process phosphoric acid and by-producing alpha-hemihydrate gypsum and high-purity and high-whiteness alpha-hemihydrate...

more
Issue 2020-10 UNIVERSITY OF SIEGEN

Investigation of hydration mechanisms of alpha and beta hemihydrate

1 Introduction Calcium sulfate hemihydrate [CaCO4???0.5H2O(s)] can be found naturally in very dry climate regions in Egypt, Australia, Death valley and Kuwait as bassanite, but in the presence of...

more
Issue 2015-7-8 WO?2015/062749?A1

Water-resistant binder based on beta-calcium sulphate hemihydrate

(22) 03.07.2014 (43) 07.05.2015 (57) The invention relates to a binder composition comprising (a) beta-­calcium sulphate hemihydrates (b-­CaSO4???0.5?H2O), (b) Portland cement and (c) zeolite, and...

more
Issue 2021-6 WO 2021/120705 A1

Method for preparing ?-hemihydrate gypsum

(22) 07.09.2020 (43) 24.06.2021 (57) Disclosed is a method for preparing ?-hemihydrate gypsum, the method involving using citric acid as a crystal transformation agent to prepare dihydrate gypsum, and...

more
Issue 2015-5 UNIVERSITY OF SIEGEN

Investigations of the hydration of calcium sulfate hemihydrate

1 Introduction Gypsum is one of the most used materials in the world; 119 million tons of natural gypsum were extracted worldwide in 2006 (MINERAL COMMODITY 2007). Additionally another...

more