Process for reducing the grain size of phosphate rock

US4116390A · kind A · utility

Assignee

• UHDE GMBH · DE

Inventors

• Wilhelm Wengeler · Bochum, DE
• Egbert Hoffmann · Bochum, DE

Key dates

• Filing date: Apr 4, 1977
• Grant date: Sep 26, 1978
• Expiry date: Apr 4, 1997

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01B25/22
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Freshly mined phosphate rock is subjected to screen classification in at least two stages. Only coarse grained phosphate rock with a grain size over 2 mm from the last screen classification step is fed to a plain-roller grinding mill. The rollers of the grinding mill run at different peripheral speeds, so that the grains are ground by radial and tangential forces. This produces a fine grained phosphate rock whose natural moisture content is advantageous when further processed to phosphoric acid by means of sulphuric acid.