Process for producing pellets of crude phosphate

• Main Authors: TIEDEMANN, JENS. DR., 5042 ERFTSTADT, DE, WEILER, HEINRICH., 5030 HUERTH, DE, STENDEL, JOACHIM. DR., 5040 BRUEHL, DE
• Format: Patent
• Language: English; German
• Published: 23.11.1989
• Subjects: CHEMISTRY; COMPOUNDS THEREOF; FERROUS OR NON-FERROUS ALLOYS; INORGANIC CHEMISTRY; METALLURGY; NON-METALLIC ELEMENTS; PRETREATMENT OF RAW MATERIALS; PRODUCTION AND REFINING OF METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

In the production of pellets of crude phosphate by drying, firing and cooling of granules using two travelling grates, the granules first pass as a bed on a first travelling grate through drying, firing and hardening zones separated from one another by intermediate walls. After passing through a heat-equilibration zone located between the two travelling grates, the pellets finally reach a second travelling grate serving as cooling zone. During this procedure, the granules are predried in the drying zone by means of hot waste gases flowing downwards from above, the predried granules are largely fired to give pellets in the firing zone by means of heating gases flowing downwards from above and in the hardening zone granules which are located at the bottom and have been only predried are further heated to the temperature required for strengthening by means of a gas stream drawn through downwards from above. Finally, all of the pellets are introduced with mixing into the heat-equilibration zone and the pellets are cooled in the cooling zone by means of air flowing upwards from below, before they are finally discharged. In this procedure, the heating gases flowing downwards from above in the firing zone are at least partially generated by combustion of lignite (brown coal) dust with air above the first travelling grate.