Process for preparing highly concentrated aqueous press cakes of solids

US4828622A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Joachim Weide · Kelkheim, DE
• Erwin Dietz · Kelkheim, DE
• Reinhold Deubel · Bad Soden am Taunus, DE

Key dates

• Filing date: May 5, 1988
• Grant date: May 9, 1989
• Expiry date: May 5, 2008

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B67/0096
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

According to the invention, addition of one or more surfactants having a cloud point in aqueous solution to an aqueous suspension of a solid gives after the isolation of the solid at a temperature above the cloud point aqueous press cakes containing a large amount of this solid. The direct processing of press cakes as obtained for example after the synthesis and isolation of dyes or pigments to give practical aqueous pastes or dispersions requires a minimum solids content in the press cakes. The minimum content is frequently not obtained when conventional methods of isolation are used, so that it is necessary to proceed via the indirect route of drying to obtain the powders and redispersing the powders. By using the process according to the invention it is possible to cut out the costly indirect route or, if desired, to reduce the expense of drying to obtain powders by an appreciable margin.