Backfilling with flotation wastes

摘要

For backfilling cavities arising underground, in particular in bituminous coal mining, flotation wastes are used which are mixed with crude gypsum from flue gas desulphurisation plants. In this case, the crude gypsum is dehydrated to less than 10% moisture content, the degree of dehydration being adjusted according to the moisture content of the flotation wastes with which it is mixed. This mixture which has a calcium chloride content of more than 3.5%, favouring the immobilisation of dust, can then be backfilled underground by pneumatic packing.