Decontaminating soils and building materials in fixed bed gasifier - to immobilise non-volatile heavy metals in slag produced

Decontaminating soils and building material in fixed bed gasification comprises adding 1-70% contaminated soil as gasifying agent. The soil and building material are added to a sorting process, introducing into a comminuting appts. and then again adding to the sorting process. The sieve throughput material is added to the fixed bed gasifier together with a solid fuel of calorific value 8-35 MJ/kg. The amt. of solid fuel in the mixt. is adjusted so that the crude gas outlet temp. is 300-500 deg.C and the total solids throughput or gasifying agent input is controlled so that pressure loss over the fixed bed charge is less than 8 kPa. On carrying out the process, the gasifying agent, in an amt. of 30-99% of grain size 0-100 mm, is coal in the form of briquettes or coke and/or solid or agglomerated waste and/or coal agglomerate and a finely ground waste. USE/ADVANTAGE - To purify soils contaminated with pollutants. Non-volatile heavy metals are immobilised in the slag produced.