METHOD OF RECYCLING RAILROAD WOODEN SLEEPERS Russian patent published in 2020 - IPC B09B3/00 B27L11/00 

FIELD: waste processing and disposal.

SUBSTANCE: invention relates to recycling wastes, particularly to recycling wood sleepers. Sorters are sorted, and sleepers are impregnated with impregnating compound. Sawdust impregnated with impregnating composition is subjected to extraction and drying with technical propane in supercritical fluid state, at pressure exceeding its critical pressure from 1.6 to 10 times, and temperature up to 1.15 times, exceeding its critical value, measured in degrees Kelvin. Reynolds number of flow of technical propane, which is in supercritical fluid state and passing through sawdust, must not exceed value of 10. At that mass of technical propane passed through sawdust should exceed weight of impregnating composition not less than (5.69–1.72 lnπ) times, where lnπ is the natural logarithm of the ratio of pressure to its critical value. After extraction, the impregnating composition is separated from the technical propane for its repeated use, ecologically clean saw-timbers and sawdust are simultaneously produced.

EFFECT: increased amount of impregnated material extracted from surface layer.

1 cl, 3 tbl