Granular fertiliser prodn. from organic sludge - by direct contact with hot gas in a fluidised bed

摘要

In the prodn. of granulated fertilisers from organic sludge from biological waste-water purificn. plants, the mechanically thickened sludge is brought into direct contact with hot (>150 degrees C) gas in high dilution in a mechanically stirred fluid bed zone with high angular momentum, and the granulated and dried prod. is removed from the fluid bed zone pneumatically by means of the waste gas and separated in a separator. Drying by direct contact with hot gas at a high ratio of gas to moist sludge gives rapid evapn. of the liq. constituents to leave the solids in granular form.