Fertiliser pellets based on slurry or sewage - contg. lime, perlite, cement and fly ash

摘要

Fertiliser pellets based on farmyard slurry or sewage sludge contain an additive mixt. comprising 40-53 wt.% Ca-contg. minerals, 20 wt.% perlite, 2-4 wt.% cement, 30 wt.% TAV fly ash (from coal-fired power stations) and opt. 5-6 wt.% of other additives. the pellets pref contain 2-4% MgO and/or K2O, 2% phosphate, and trace elements. In the prepn. a mixt of 60 vol.% slurry or sewage sludge and 40 vol.% of the additive mixt. is forced through a die matrix having convergent conical openings to form pellets, which are irradiated with UV and opt. dusted with a small amt. of the additive mixt. Gases escaping during pressing may be recycled or absorbed in H2SO4 or H3PO4. The whole operation may be performed in a transportable appts.